ELECTRIC MOTOR, GENERATOR AND COMMUTATOR SYSTEM, DEVICE
AND METHOD
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority benefit of US Provisional Patent
Application No. 62/014,1 14, titled "True Brushless DC Motor, Generator and
Commutator", and filed on June 19, 2014; the entire contents of this application
are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention is in the field of electric motors, generators and
commutator systems.
BACKGROUND OF THE INVENTION
[0003] The direct current (DC) electric motor was invented in the early 1800's,
and the alternating current (AC) electric motors were invented about 50 years
later in the later 1800's. Since then both types of electric motors have become
highly developed and are used to provide mechanical force for a wide variety of
different applications.
Brief review of Basic Electromagnetism and Electric Motor Design
[0004] Ampere's Law describes the generation of a magnetic field in the
presence of an electric current. Magnetic fields produced via Ampere's Law are
used to generate physical magnetic forces in devices such as electromagnets
and electric motors. Faraday's Law of Induction, in addition to being important
for electric motors, also serves as the conceptual foundation for most of the
world's electrical generating and distribution systems. Faraday's Law of
Induction describes the generation of an electric field from a magnetic field that
changes in intensity over time. An electric field produced via Faraday's Law also
gives rise to an electromotive force (EMF) which in turn produces an electric
current. Electric fields produced via Faraday's Law are used to generate
electrical currents in devices such as electric transformers and electric
generators.
[0005] Motors are generally composed of a stationary part, called the stator,
and a moving part, called the rotor. Additional components, such as commutator,
are also often used (particularly with DC motors) to operate the motor by
switching the direction of current between the rotor and an external power
supply. Rotors typically comprise rotatable shafts and can be constructed in
different ways. Different types of rotors known in the art include permanent
magnetic rotors, as well as electromagnetic coil based rotors including squirrel
cage rotors, synchronized rotors, and reluctance based devices including
reluctance rotors, stepper rotors, and the like. Although stators with permanent
magnets are known, generally stators are constructed with a stator body that
incorporates multiple pairs of coils of wire (coils). These stator electric coils are
often, but not always, arranged in a radial manner around the center of the body
of the stator. Rotors often, but not always, fit inside openings that are often in the
center of the stator body.
[0006] In an AC induction motor, such as a three-phase AC electric motor, the
timely alternating sinusoidal current from the AC power supply naturally switches
the direction of the current flowing through the various motor stator coils, usually
many times per second. This creates an alternating magnetic field on the stator
winding which, when combined with the phase angle differences between the
different phases of the applied AC current, creates a rotating magnetic field on
AC motor stator. In effect, the sinusoidal variations in the three-phase AC
current provide a natural self-commutation process. The natural speed of the
motor is in effect set by the frequency of the AC current.
[0007] For both AC and DC motors, many applications require that the speed of
the motor be precisely controlled. Although for some applications, various types
of gearing arrangements may be used to regulate speed; often it is important to
regulate the underlying speed of the motor itself. This is not entirely always
easy. In order to regulate the natural (e.g., neglecting gearing arrangements)
speed of an AC motor, usually the frequency of the AC power supply must be
changed. A common method of doing this is to utilize Variable Frequency Drive
(VFD) methods. VFD devices create AC current at different frequencies by
acting as inverters to transform a DC current from a DC power supply into AC
current at the desired frequency. However instead of providing a smoothly
varying sinusoidal AC current, as might be obtained from a real rotational AC
generator, inverters, such as VFD typically uses Pause Width Modulation (PWM)
methods to create pseudo sinusoidal waves. The jagged, step function type
nature of the AC current provided by a VFD creates Total Harmonic Distortion
(THD) effects, and this THD effects in turn create various types of inefficiencies
and other problems in AC electric motors and other devices.
[0008] Thus, for example, when a typical VFC driver switches between
producing 2 KiloHertz (kHz) to 15 kHz AC current, and is used to drive an AC
motor, at the higher frequency, there are typically greater VFD power switching
losses as well as a greater AC skin effects on the motor winding. This causes
both waste energy and creates unwanted heat. These effects further act to limit
the VFC and PWM's maximum switching frequency which turn limits how fast the
AC motor can rotate. Nonetheless, VFD devices are highly useful because they
allow AC motors to operate with precision speed control. As a result, AC motors
are slowly starting to replace the use of traditional DC motors in a wide variety of
applications.
[0009] For an AC motor, when sinusoidal AC current is used to power the coil,
the induced EMF produced by collapsing AC is effectively and naturally
suppressed. However AC motors are often not as strong as DC motors. This is
because the AC current caused magnetic field is varying continuously, thus
preventing the magnetic field in the AC motor's coils from ever staying at their
peak for any appreciable amount of time. This limits the maximum starting
torque that an AC motor can exert.
[0010] An additional problem with AC motors is that the varying magnetic field
causes induction resistance which, relative to DC motors, further restricts current
flow at the maximum supply voltage. This further limits the strength of the AC
motor coil's magnetic fields, and thus further limits maximum torque, especially at
high rotations per minute (RPM). Another problem with AC motors is that AC
skin effect (AC tends to travel along the outside "skin" of a wire, rather than
inside the wire) further resists current flow at a high frequency which again limits
its performance. Other problems associated with AC controllers, such as total
harmonic distortion (THD), which converts into heat in the stator core, waste
energy and reduce the motor's power density for a given motor frame size.
BRIEF SUMMARY OF THE INVENTION
[001 1] Aspects of this disclosure include a direct current (DC) electric motor
system comprising: a stator having a closed type winding including at least three
coils which produce a stator rotating magnetic field which is coupled with a rotor
magnetically, the rotor capable of rotating when induced by the stator rotating
magnetic field; a commutator coupled to the stator and which controls the stator
rotating magnetic field through a timed commutation sequence; and wherein the
stator and the at least three coils are configured so that energy released from a
collapsing stator rotating magnetic field on a de-energizing commutation step in a
first of the at least three coils is captured by a second of the at least threes coils
energized on a next step of an energizing commutation step.
[001 2] Further aspects of the disclosure include an alternating current (AC)
induction electric motor system comprising: a stator having a closed type winding
including at least three coils which produce a stator rotating magnetic field which
is coupled with a rotor magnetically, the rotor capable of rotating when induced by
the stator rotating magnetic field; a variable frequency drive coupled to the stator
and which controls the stator rotating magnetic field; and wherein the stator and
the at least three coils are configured so that energy released from a collapsing
stator rotating magnetic field in a first of the at least three coils is captured by a
second of the at least three coils.
[0013] Further aspects of the disclosure include a method for producing a stator
rotating magnetic field in a direct current (DC) electric motor system
comprising producing the stator rotating magnetic field from a closed type winding
of a stator including at least three coils coupled with a rotor magnetically, the rotor
capable of rotating when induced by the stator rotating magnetic field; controlling
the stator rotating magnetic field with a commutator through a timed commutation
sequence; and wherein the stator and the at least three coils are configured so
that energy released from a collapsing stator rotating magnetic field on a deenergizing
commutation step in a first of the at least three coils is captured by a
second of the at least threes coils energized on a next step of an energizing
commutation step.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FigIA is a perspective view of a motor assembly 100 as described
herein.
[001 5] Fig1 B is an axial view of the motor assembly 100 with commutator 400.
[001 6] Fig1 C shows the body of a four slot stator 110 in three-dimensional (3D)
perspective, with parallel lengthwise ridges along the internal surface of the stator.
[001 7] Figure 1D shows the front face of the body of the four slot electric motor
stator 100 from Figure 1C above, along with a simple two pole permanent magnet
rotor 120 operating inside of the stator 100.
[001 8] Fig 2A shows details of four individual coils for the four slots electric
motor stator 110 of Fig. 1C.
[0019] Fig 2B shows a closed type stator winding diagram of the four slot
electric motor stator 110 from Fig 1A.
[0020] Figs 3A-3D show individual coil details for the four slot electric motor
stator 110 previously illustrated in Figure 2B.
[0021] Figs. 3E-3J show a series of winding diagrams of stator 110 each paired
with a side view of the stator 110 (pairs Figs. 3E and 3F; 3G and 3H; and 3I and
3J) to show a current flow direction and stator magnetic flux direction at different
steps of the commutation sequence.
[0022] Fig 4 shows one embodiment of sixteen steps timed commutation
sequence for the four segment closed type stator winding, each commutation step
advances 22.5 degree to generate one 360 degree rotation of the magnetic field.
[0023] Figs. 5A-5P illustrates a four segment closed type winding in a series of
diagrams showing the sixteen step timed commutation sequence of Figure 4 for
one full magnetic field rotation.
[0024] Fig 6 shows an alternative commutation switching option that is
interchangeable with the commutation sequence of Figure 4 and creates the
same field effect.
[0025] Figs. 7A-7H shows the four segment closed type winding commutated
with the eight step timed commutation sequence for one full magnetic field
rotation.
[0026] Fig. 7 1 shows a segments potential graph of one full magnetic field
revolution of an eight step timed commutation sequence.
[0027] Fig. 8 shows stator 110 coupled with an embodiment of commutator 400
(e.g., a switch commutator) with an electric half bridge switch presentation.
[0028] Fig. 9A is an alternative embodiment of the commutator 400 in the form
of a rotary mechanical commutator shown in operation and Fig. 9B shows an
exploded view of the rotary mechanical commutator.
[0029] Fig. 9C shows an electromechanical diagram of the rotary mechanical
commutator of Figs. 9A and 9B.
[0030] Fig. 10A shows a winding diagram of stator 110 with conventional
electric currents flow and magnetic poles produced during a commutation step on
the timed commutation sequence,
[0031] Fig. 10B shows a winding diagram of alternative embodiment of Fig. 10A
to illustrate the coil routing.
[0032] Fig. 10C shows a front view of the stator 110 illustrating the stator
magnetic pole vector (magnetic field pointing direction) in their geometric positions
in reference to the slot at this timed commutation sequence step.
[0033] Fig. 10D is the corresponding settings of the commutator 400 switches.
[0034] Fig. 11A shows an example of a three segment closed type stator
winding.
[0035] Fig. 11B shows an electromechanical diagram of one embodiment of a
rotary commutator for a twelve step timed commutation sequence.
[0036] Fig. 11C shows a twelve step time commutation sequence for the three
segments closed type stator winding,
[0037] Figs. 12A-1 2L shows the current and stator magnetic field geometric
positions in reference to the stator slot for the twelve steps time commutation
sequence for the three segments closed type stator winding of Figures 11A-1 1C.
[0038] Figs. 13A-1 3F shows a front view of a three slot stator with current flow
direction and stator magnetic flux direction.
[0039] Figs. 13A-1 3F show a series of winding diagrams of the three slot stator
each paired with a side view of the three slot stator (pairs Figs. 13A and 13B; 13C
and 13D; and 13E and 13F) to show a current flow direction and stator magnetic
flux direction at different steps of the commutation sequence.
[0040] Fig. 14 shows segments potential graph of one full magnetic field
revolution of a twelve steps timed commutation sequence for the three slot stator.
[0041] Fig. 15A shows a six step timed commutation sequence for the three slot
stator. Fig. 15B shows segments potential graph of one full magnetic field
revolution of a six step timed commutation sequence for the three slot stator.
[0042] Fig 16 shows an embodiment of a twenty step timed commutation
sequence for a five segments closed type stator winding.
[0043] Fig. 17 shows a wiring diagram for a three segments four pole closed
type stator winding where P=3, N=1 , R=2, and S=6.
[0044] Fig. 18 shows a three segments six pole closed type stator winding
where P=3, N=4, R=3, and S=36.
[0045] Fig. 19 shows a three segments sixteen pole closed type stator winding
where P=3, N=2, R=8, and S=48.
[0046] Fig. 20 shows a four segments two pole closed type stator winding where
P=4, N=2, R=1 , and S=8.
[0047] Fig. 2 1 shows a four segments six pole closed type stator winding where
=4, N=3, R=3, and S=36.
[0048] Fig. 22 shows a five segments two pole closed type stator winding where
P=5, N=1 , R=1 , and S=5.
[0049] Fig. 23 shows a six segments two pole closed type stator winding where
P=6, N=1 , R=1 , and S=6.
[0050] Figs. 24A-24B show a six segments two pole closed type stator winding
where P=6, N=2, R=1 , and S=1 2. Figs. 24A shows one de-energize step and
Figs. 24B shows one energize step.
[0051 ] Fig. 25 shows an eight segments two pole closed type stator winding
where P=8, N=1 , R=1 , and S=8.
[0052] Fig. 26 shows a ten segments two pole closed type stator winding where
P=1 0, N=1 , R=1 , and S=1 0.
[0053] Fig. 27 shows a twelve segments two pole closed type stator winding
P=1 2, N=1 , R=1 , and S=1 2.
[0054] Fig. 28A shows a three phase AC current with artificially predetermined
twelve step segments potential points to match the timed commutation sequence
shown in Figure 28B.
[0055] Figure 29 is a perspective view of an AC motor assembly 2900.
DETAILED DESCRIPTION
[0056] In contrast to AC motors, DC electrical motors don't have a "natural
commutator". To operate a DC electrical motor, the DC current passing through
the various coils of the DC motor must be varied using various types of
commutator devices. In some DC electric motor designs, the stator may
incorporate either permanent magnets or non-switched electromagnets (e.g., non
switched stator coils), and instead the magnetic field of the rotor may be varied
by a function of time, usually by switching the direction of current flowing through
the windings of the various rotor coils.
[0057] In some alternative DC motor designs, a rotating magnetic field is
generated on the DC electric stator instead. In these designs, the motor stator
generally comprises various coils (each coil usually formed from multiple wire
windings). The motor stator can be operated by sequentially switching or
commutating the direction of the current flowing through the windings of the
various motor stator coils in a manner that produces a rotating magnetic field.
This rotating magnetic field in turn can be used to induce rotation in a rotor with
suitable magnetization or reluctance.
[0058] In some types of DC motors, such as step motors and reluctance
motors, the coil windings are electrically driven by individual electric half bridges
(allow connected terminal connect to either positive or negative of DC power
supply). When a particular coil winding is powered with electrical current, it
creates a magnetic field, and in essence there is energy stored in this magnetic
field.
[0059] More specifically, applying electric current through a conductor coil (e.g.,
a coil of conducting wire) creates a magnetic field. Energy is stored in this
magnetic field, in a manner not unlike storing kinetic energy in a rotating flywheel.
When this applied electrical current is removed, an EMF (electromagnetic force)
is induced, and this stored magnetic field energy is discharged in the form of an
electric current at a voltage (electrical potential). According to Lenz's law, an
induced electromotive force (EMF) always gives rise to a current whose magnetic
field opposes the original change in magnetic flux. Thus the discharged electrical
current flows in the same direction as the original applied current.
[0060] The problem with such types of DC motors is that during the
commutation process, once power is removed from a previously powered coil,
that coil's magnetic field promptly collapses. The energy stored in the coils
collapsing magnetic field (e.g., self-induced EMF) previously stored in the coil
winding, is now released. Where does it go? For AC motors, the AC sinusoidal
current acts to suppress this self-induced EMF naturally. However for DC
motors, the energy in the coil winding's self-induced EMF comes back as selfinduced
EMF electrical current and this has to go somewhere. With present
designs, the self-induced EMF electrical current generally travels back to the DC
power supply or is consumed into ballast resistors. This is not a problem for
small DC motors, but for high power motors, the magnitude of the self-induced
EMF electrical current is quite high, and it can become very challenging to
handle. This is a major reason why prior art step motors can only handle low
amounts of power (e.g., up to few hundred watts); and even prior art DC
reluctance motors can only handle a few kilowatts of power.
[0061] At the same time DC motors, in particular DC brushed motors, have
some compelling advantages for some applications. For example, DC brushed
motors can be designed with a stationary field coil and commutated armature coil
winding scheme. Rush starting a DC current can create very large amounts of
starting torque. As a result, such DC motor designs are often favored in various
types of high starting torque applications, such as for traction motors on railways,
city trolleys and subway third rail systems.
[0062] One problem with DC brushed motors, however, is due to the brushes
themselves. The brushes create friction, contact resistance heat loss, plus
armature winding resistance loss. These effects create large amount of heat
trapped in the relatively small rotor part of the motor, it is difficult to remove this
armature heat, as a result, brushed DC motors are typically built on an open
frame design to allow excess heat to escape or force vented. As the brushes
used to provide current to the armature usually wear quickly, the DC brushed
motors of large size are often high maintenance devices, and their
armatures/rotors have to be frequently removed and reworked for maintenance.
[0063] In the detailed description of the embodiments disclosed herein, there
will be described an improved electric motor, which can be driven by multiphase
AC current or commutated by DC current. Because AC is naturally commutating
as its name stands for, it does not require a commutator and a sinusoidal AC
naturally suppresses self-induced EMF. Electric motor DC commutation is
explained in detail in this disclosure. In at least one embodiment, the improved
electric motor will generally comprise at least one stator and commutation system
for DC operation. However alternate embodiments are also contemplated
accordingly (e.g., universal motors with multiple stators and even possibly multiple
rotors). The embodiments disclosed herein will typically operate using electrical
current (power, energy) from at least one DC power source (i.e., DC power
supply, DC energy source, DC current source). More specifically, there is
disclosed herein a direct current (DC) electric motor assembly with a closed type
overlap stator winding which is commutated with a timed commutating sequence
that is capable of generating a stator rotating magnetic field. The coil overlap of
the winding and a tinned commutation sequence is such that the current in each
slot of the stator is additive and when part of a previous magnetic pole collapses
according to a commutation sequence; the energy released by that part of a
previous collapsing magnetic field is captured to strengthen the next magnetic
field on the commutation sequence schedule. Electrical currents produced by
the collapsing magnetic fields flow to low electric potential and add or subtract to
the DC current provided by the commutator thus promoting formation of the next
magnetic field on commutation schedule. When used with a suitable commutator
and rotor, the electric motor assembly provides a true brushless high torque
speed controlled DC motor that operates with higher efficiency and higher power
density.
[0064] Fig. 1A is a perspective view of a Real Direct Current (RDC) motor
assembly 100 as will be described in detail. Besides stator 110, the motor
assembly features rotor 120 and coil windings 112 connected to commutator 400
(e.g., a switch commutator). The simple permanent magnet rotor 120, with a
North and South Pole, can rotate inside the stator 110 in response to stator
rotating magnetic fields created by the coil windings 112. Coil windings 112 are
classified into two different types in this disclosure: i) closed type winding or ii)
open type winding. In a closed type winding, a closed path is formed around the
stator. The starting point of the winding is reached again after passing through
part or all the turns. Commutator segments (described below) are connected to
various winding coils 112 and as a result the current in the coil windings gets
divided into different parallel paths. The current flowing through the coil windings
changes continuously. In contrast, in open type windings such as star connected
AC machines, a commutator is not used. In such cases the ends of each section
of the winding can be brought at terminals to do the required type of
interconnection externally. The open type of winding is often preferred over
closed type as it gives better flexibility in design and freedom of connections. In
this disclosure to allow the stator closed type winding to be clearer and more
easily appreciated, rotors (e.g., 120) are not necessarily shown in the other
figures of this description. However, all stators described herein should be
assumed to be associated with an appropriate rotor(s) to form an electric motor
assembly. Also, although only a four slot stator and closed type winding is shown
in detail in Figures 1A-1 D for use in motor assembly 100 it is to be understand
that the number of slots in alternative embodiments of the stator can range from a
minimum of three to one hundred and even greater than one hundred in number
since there are actually no set, fixed upper limits on the number of slots in a
stator. It should be noted that the recitation of ranges of values in this disclosure
are merely intended to serve as a shorthand method of referring individually to
each separate value falling within the range, unless otherwise indicated herein,
and each separate value is incorporated into the specification as if it were
individually recited herein. Therefore, any given numerical range shall include
whole and fractions of numbers within the range. For example, the range " 1 to
10" shall be interpreted to specifically include whole numbers between 1 and 10
(e.g., 1, 2, 3, . . . 9) and non-whole numbers (e.g., 1.1 , 1.2, . . . 1.9). Therefore,
for example, when describing operation of a 4 slot stator, the description would
apply equally to a 3, 8, 16, 72 or 100 plus slot stator (for example) and those
different numbered slotted stators should be considered to be implemented
according to the methods and systems described herein and are part of this
disclosure.
[0065] When electric motors were originally developed in the 1800's, the
available mechanisms to control the operation of electric motors were limited to
relatively crude mechanical devices which had less than perfect timing and
flexibility. Due to rapid advancing of modern solid state electronic technology, the
performance of electric motors such as motor assembly 100 can be considerably
improved. Because the coils in this closed type stator winding are interconnected,
as described above the "closed type" means that from any point of the winding, it
can be traced back to the same point along the coils. Because electric current
flows naturally from high to low potential through least resistance, and the
interconnected coils offer the least resistance path, it is regardless whether this
current comes from external power or self-induced current from collapsing
magnetic field on the coils. Therefore, closed type windings enable DC current
switching on the coils without the penalty of self-induced high potential/voltage
build up on the closed type stator winding. Also, when the closed winding is
properly commutated, the self-induced current is facilitated to advance the stator
rotating magnetic field and/or strengthen the next magnetic field on timed
commutation sequence. The energy from collapsing field is therefore effectively
captured inside the winding with the embodiments described herein.
[0066] Fig. 1B is an axial view of motor assembly 100 with commutator 400
located on the exterior of the assembly. Compared with traditional brushed DC
motor, the maintenance problems of brushes inside the motor's body can be
avoided by instead using an external type commutator system as shown in Figure
1B. (However, in alternative embodiments, the commutator may be located inside
the motor assembly 100). The commutator 400 is typically integrated electronics
similar to AC motor VFD driver, made up of microprocessor, sensors, switches,
input/output interface, and software to control the commutation of the motor
assembly 100. The timed commutation sequence may be generated by
coupling the rotor position mechanically or electronically with built n
position sensors inside motor assembly 100 as a dosed loop feedback such that
when a first commutation step is commanded and the rotor 120 is induced to a
detected position, a second commutation step is commanded so that the
rotor 120 is induced to next position. On and on, so that the closed type stator
winding DC motor is self-commutating. The position sensors can be any
magnetic sensor, optical sensor, or solid state switch.
[0067] Fig. 1C shows a three-dimensional perspective view of the body of a four
slot (or segment) stator 110 with parallel lengthwise ridges along the internal
surface of the stator. The spaces between the ridges are the "slots" (e.g., S 1 -
S4) and the coils are formed from conductor wires that are wound inside each slot
around the ridges so that the coils pass through the slot. The cylinder (stator
body 110) is generally made of magnetically permeable material and the ridges
thus form the center of cores that concentrate and shape the magnetic fields
created by current flowing through the coil windings 112.
[0068] Figure 1D shows the front face of the body of the four slot electric motor
stator 110 from Figure 1C above, along with a simple two pole permanent magnet
rotor 120 placed inside of the stator for illustration purposes. As previously stated,
each of the motors disclosed herein should be assumed to have a rotor whether
shown or not.
[0069] As will be discussed, the methods and systems described herein may be
used to produce and operate a universal electric motor 100 comprising at least
one rotor 120, one stator 110 and a commutator 400. The stator 110 will
generally comprise a plurality of stator winding coils 112 that are held in a defined
geometric position with respect to each other. These stator winding coils 112 are
configured to be energized and deenergized with DC electrical energy by
commutator 400 (e.g., a switch commutator). The stator coil and timed
commutation sequence will generally be constructed to produce additive current
in the stator slots (S1 to S4) to create a magnetic field. The magnetic field will
produce a plurality of time varying and geometrically separated stator magnetic
poles that in turn produce a DC created stator rotating magnetic field. The timed
commutation sequence and the closed type winding schemes should be such that
when self-induced EMF occurs from an electrically energized to deenergized coil
or coils, it produces a current from the collapsing magnetic field. The self-induced
EMF current should advance the stator magnetic field and help build the next
magnetic field on the timed commutation schedule. The timed commutation
sequence can be generated with a logic circuit(s) or micro processor(s) for open
loop control, it can also be generated by detecting the rotor position with built in
Hall-effect or magnetic sensors inside motor assembly 1 0 as a closed
loop feedback such that when first commutation step is commanded and the
rotor 120 is induced to a detected position, a second commutation step is
commanded so that the rotor 120 is induced to next position. On and on, it can
be phrased as self-commutation.
[0070] The system and method disclosed herein may produce improved DC
electric motors that are efficient and potentially more durable than prior art DC
electrical motors of this type. In addition to lower efficiency, prior art motors also
tend to impose additional stress on various types of electronic circuitry. The
embodiments disclosed herein can also help to achieve precision control over the
speed of the DC motor.
[0071] The rotor 120 shown in Figure 1D can be configured to produce rotor
magnetic poles inside electric motor 100. This rotor 120 will generally be
geometrically constrained proximate to the stator 110 (usually by various
mechanical fixtures) in a manner that allows the rotor magnetic field to interact
with a stator magnetic field produced by the closed type stator winding 112 and
also allow the rotor to rotate about a rotor axis of rotation. As will be discussed
herein, a stator created rotating magnetic field induces rotation in the rotor 120.
The rotor 120 may be of various types including a squirrel cage induction rotor,
wounded rotor, permanent magnet rotor, or reluctance rotor. In at least one
embodiment, the rotor 120 and its corresponding magnetic poles may be shaped
to match the configuration of the stator ridges, as well as to maximize the torque
produced as the result of the stator's rotating magnetic field produced by the
closed type stator winding 112. Note that in many constructions although the
rotor may often be placed inside the stator, however, this need not always be the
case. In alternative embodiments, the motor 100 may be designed with
substantial portions of the rotor or even the entire rotor, held outside of the stator.
The rotor and stator can also be configured in a horizontal flux motor design in
which the rotor and stator are held in a face to face configuration.
[0072] Although the stator 110 is a brushless stator as described so far, in
alternative embodiments the commutator used to provide power to the stator
closed type winding need not be brushless. So long as the closed type stator
winding can receive DC electrical energy, according to a timed commutation
sequence, from a DC electrical power source by using a commutator system that
commutator system may include mechanical switches, rotary switches,
mechanical relays, solid state switches, logical devices, H-bridges, and/or
computer processors (e.g., microprocessors, microcontrollers, other logical
devices, and the like).
[0073] Various types of coil winding 112 schemes can be used as well. These
schemes include brushed DC motor armature winding methods such as any of a
group consisting of: lap winding, wave winding, and Gramme-ring winding
methods.
[0074] Fig. 2A illustrates details of four individual coils 112 for the four slots S 1-
S4 electric motor stator 110 of Fig. 1C. Fig. 2B shows a closed type stator
winding diagram of the four slot electric motor stator 110 from Fig. 1A. Fig. 2B is
diagrammed according to the convention in which the stator body 110 is shown in
flat format as if the stator 110 is cut lengthwise in between one of its slot of the
stator cylinder then unrolled to a flat state. Commutation segments are shown
with segments marked as X* squares (e.g., 1* , 2* , 3* , and 4* ) .
[0075] Figs. 3A-3D show individual coil winding details (Coil # 1, Coil #2, Coil #3,
and Coil #4) for the four slots electric motor stator 110 previously illustrated in
Figs. 1A-2B. It should be noted how the coil bypasses slots. In Fig. 3A, the
starting end of the Coil # 1 (designated as 1s at commutation segment 1* ) goes
into stator Slot 1 (S1 ) , marked as 1f, bypasses Slot 2 (S2), and is returned on
stator Slot 3 (S3) (designated as 1b). The tail end of Coil # 1 (designated as 1t) is
then connected to the start end of next successive Coil #2 and connected to
commutation segment or phase 2* . (This convention will be used throughout this
disclosure). In Fig 3B, the starting end of Coil #2 (designated as 2s) goes into
stator Slot 2, marked as 2f, bypasses Slot 3, and is returned on stator Slot 4
(marked as 2b). The tail end of Coil #2 (designated as 2t) is then connected to
the start end of next successive coil #3 and connected to commutation segment
or phase 3* . In Fig 3C, the starting end of the Coil #3 (designated as 3s) goes
into stator Slot 3, marked as 3f, bypasses Slot 4, and is returned on stator Slot 1
(designated as 3b). The tail end of Coil #3 (designated as 3t) is then connected
to the start end of next successive Coil #4 and connected to commutation
segment or phase 4* . In Fig 3D, the starting end of the Coil #4 (designated as 4s)
goes into stator Slot 4 (marked as 4f) bypasses Slot 1 and is returned on stator
Slot 2 (designated as 4b). The tail end of the Coil #4 (designated as 4t) is then
connected to the start end of next successive Coil # 1 and connected to
commutation segment or phase 1* . Here each (front side) coil occupies one slot
and this convention will be used throughout the various figures of this disclosure.
Generally "commutation segment", "segment" and "phase" alternative
terminologies will also be used herein.
[0076] Figs. 3E-3J show a series of winding diagrams of stator 110 each paired
with a side view of the stator 110 (pairs Figs. 3E and 3F; 3G and 3H; and 3 I and
3J) to show a current flow direction and stator magnetic flux direction at different
steps of the commutation sequence. In Figs. 3E, 3H and 3J, the coils are shown
in two turns for easy of illustrating the end winding (outside of slot coil winding)
current direction. A coil in the back is shown in dashed line and in the front in
solid line. A plus sign in a circle shows current going into the slot and a dot in the
circle shows current flow out of slot. Figs. 3E and 3F show Coil # 1 being
energized together with Coil #2, Coil #3 and Coil #4 and in the moment Coil # 1
trail end is commutated to high potential segment *2. Between Figs. 3E and 3G,
the Coil # 1 energized magnetic field starts collapsing; current generated from the
collapsing field continues to flow to low potential segment 3* through coil #2 which
strengthens the Coil #2 generated magnetic field. The result of the energy from
the collapsing field is redirected to build or strengthen a coming magnetic field in
the commutation schedule and energy is captured inside the closed type stator
winding. Also at the same moment, the Coil #3 trail end is commutated to low
potential segment 4* . From Figs 3E to 3G, the Coil #3 energized magnetic field
starts collapsing; current generated from the collapsing field continues to flow to
low potential segment 4* through Coil #4 which strengthens the Coil #4 generated
magnetic field. Again the result of the energy from the collapsing field is
redirected to build or strengthen a coming magnetic field in the commutation
schedule and energy is captured inside the closed type stator winding. The stator
magnetic field is effectively advanced approximately 45 degrees on this deenergize
commutation step. From Fig. 3G to 3I, when the Coil # 1 start end is
released from high potential segment 1* , Coil # 1 is getting charged with electric
energy as current which effectively advances the stator magnetic field. At
substantially the same moment when the Coil #3 start end is released from low
potential segment 3* , Coil #3 is getting charged with electric energy as current
which effectively advances the stator magnetic field. The stator magnetic field is
advanced approximately 45 degrees on this energize commutation step. In the
traditional AC motor lap or concentric winding, the current in the end coil portion of
the coil (i.e., the outside of the slot portion) does not contribute to generate the
stator magnetic field. All the coils in this closed type winding include coil portions
outside of slots substantially equally contributing to energize the stator magnetic
field, in other words the end coil portion and the in slot coil portion are all integrally
part of the coil winding.
[0077] Fig. 4 shows an alternative sixteen step timed commutation sequence for
the four segment closed type stator winding 112 described in Figures 1A-3J, each
commutation step advances approximately 22.5 degrees to generate one 360
degree rotation of a magnetic field. Figs. 5A-5P show the four segment closed
type windings 112 commutated with a sixteen step timed commutation sequence
for one full magnetic field rotation. Current and direction in the windings 112 of
Figures 5A-5P are shown by up and down arrows. Note that with each step of
commutation, the magnetic field is advanced from the previous 22.5 degree step
to create a counterclockwise rotating magnetic field. The reversed timed
commutation sequence reverses the stator magnetic field direction of advancing,
consequently reversing the rotor rotation. Figs. 5A-5P best interpret this. Moving
from Figure 5A to Figure 5B to Figure 5C, it should be noted how current
regenerated from the discharging magnetic field of Fig. 5B from a just
deenergized Coil # 1 is redirected to the next charging magnetic field of step #3
(Figure 5C) because the electric current flows from high electric potential to low
electric potential. At the instance of Fig. 5C, segment 2* is connected to positive
DC power source; Coil # 1 at both ends is placed at substantially the same high
potential; the magnetic field generated by Coil # 1 is starting to collapse; Coil # 1
current created by the collapsing magnetic field will continue to flow into low
potential on the closed type winding, which is segment 3* ; and Coil #2 is offering
the route for said current until the field is completely collapsed. The net effect of
the discharging current from Coil # 1 generated from the collapsing magnetic field
have effectively advanced magnetic field approximately 22.5 degrees in this timed
commutation sequence step and the discharging current is advancing and helping
build next on the coming magnetic field on the timed commutation schedule.
There is no high voltage generated on this closed coil winding induced by
collapsing magnetic field. Figs. 5A-5P are also interpret the charging and
discharging step. There is a charging step when at least one more coil is
energized on the closed type winding to advance the stator magnetic field and a
discharging step when at least one more coil's both end is commutated to the
same electric potential and the coil or coils would discharge the magnetic field
energy stored from previous charging step. The discharging of the field induces
current to continue to flow in a previous current direction until the discharging
magnetic field is completely collapsed. The induced current together with current
from the DC power supply results in advancing the rotating magnetic field one
commutation step. The timed commutation sequence continuously commutating
the closed type winding and advance the magnetic field forward, the advance
magnetic field forward creates a DC generated stator rotating magnetic field and
the rotating magnetic field rotates on the pace and direction of the timed
commutation sequence. The timed commutation sequence on the closed type
winding enables DC commutation without the penalty of inducing high electric
potential on the closed type winding and this closed type winding can handle large
DC electric current (e.g., over hundreds of amperes).
[0078] Fig. 6 is an example of one of the alternative commutation switching
options that are interchangeable and may be used to create the same field effect
of Fig. 4 in the motor assembly 100 illustrated in Figures 1A-3D. The eight
commutation steps shown in Fig. 5B, Fig. 5D, Fig. 5F, Fig. 5H, Fig. 5J, Fig. 5L,
Fig. 5N, and Fig. 5P can also be combined to create an eight step timed
commutation sequence with each commutation step advancing substantially 45
degrees of the magnetic field as shown in Figs. 7A-7H. Fig. 7 I shows a segments
potential graph of one full magnetic field revolution of an eight step timed
commutation sequence. The basic operation principle behind the four slot closed
type stator winding 112 and corresponding timed commutation sequence shown
above can apply to any segment count of closed type winding and corresponding
timed commutation sequence described herein. The closed type stator winding
112 and timed commutation sequence should be configured so that self-induced
current from a collapsing magnetic field contributes to advance the stator rotating
magnetic field and facilitate current in the slot additive to create the magnetic pole.
Current cancelation in the same slot should be avoided unless to advance the
stator magnetic field. For the closed type winding to consist of more than four
segments, there are many more options with how many more slots a coil can
pass over and how the commutator can be placed on the segments. The general
method and system described herein still applies and additionally, balanced
magnetic pole placement and paced commutation is preferred whenever possible.
[0079] The total slot count of the closed type stator winding can be described
with the stator winding formula: S = P x N x R where S is total slot count on the
stator; P is at least three Segments/Phases; N is at least one slot each coil
occupies; and R is at least one for stator pole pair count on the stator (e.g., R=2
for a four pole winding). Basically unlimited motor stator poles and slots
combinations can be configured with this formula (or methodology) and are
included in this disclosure herein. Similar like a Brushless DC (BLDC) motor, R
time's winding magnetic field revolution makes one rotor revolution.
[0080] Fig. 8 shows an embodiment of commutator 400 (e.g., switch
commutator) which may be used in connection with Figs. 1A-7I discussed above
in an electric half bridge switch presentation. The electric half bridge is connected
(through wire 801 ) to the closed type stator winding 112 through commutation
segment 1* to facilitate the timed commutation sequence. Note the other
commutation segments are also connected to the corresponding half bridge via
other wires (802, 803, and 804). In order to keep the drawings simple, generally
these half bridges and connecting wires between the electric half bridge and the
commutation segment are not shown. Thus each of the commutation segments
(with segments marked as X* squares) are connected to their corresponding half
bridge (X' circles), which in turn connect to a DC positive power supply (not
shown) through a high switch and is also connected to the DC ground through a
lower switch.
[0081 ] Fig. 9A is an alternative embodiment of a commutator 900 which may be
used with the embodiments of Figs. 1A-7I. Fig. 9A illustrates a rotary mechanical
commutator 900 in operation and Fig. 9B is an exploded view. The stationary
spring loaded commutation segment brushes 1* , 2* , 3* , and 4* shown in Fig. 9B
are sequentially mounted around the rotating electric poles 902 and 904. The
rotary electric pole assembly 906 can be mechanically coupled to the motor rotor
120 for self-commutation or be driven by a second commutation motor governed
by a timed commutation sequence. DC power is delivered to the rotating electric
pole assembly 906 through slip rings 908 and 9 10 which are electrically
interconnected with the electric poles 902 and 904 through wires 912 and 914,
and the slip rings 908 and 910 are electrically in contact with spring loaded pole
brushes 916 and 918 which are in turn electrically connected with stationary
power supply. Fig. 9C shows an electromechanical side view diagram of Figs. 9A
and 9B highlighting the stator magnetic field vector. The commutation segments
are sequentially and equally spaced around the rotary electric poles. The electric
pole and the segment angular space (time angle) is three fourths of the angular
space (time angle) of the segment pitch such that each of the eight commutation
steps will have the same time interval or a paced commutation. However the
segment and electric pole time angle can vary which will create a limitless unpaced
commutation sequence. In Figure 9C, slot numbers S 1-S4 are in between
the segments. A paced commutation is used in the sense that each timed
commutation sequence step has a substantially equal interval, or accelerated
pace, or decelerated pace as its name stand for.
[0082] Fig. 10A shows electric current flows and magnetic poles produced
during a commutation step on the timed commutation sequence. The Magnetic
North Pole is drawn on an upward current slot and Magnetic South Pole is drawn
on a downward current slot. The timed commutation sequence is present as: a
plus symbol in a box attached to segments 1* and 2* represents commutator
switch 1h and 2h is closed and connected to DC power positive; a negative
symbol in a box attached to segments 3* and 4* represents commutator switch 31;
and 4 1 is closed and connected to DC power negative. (This convention is used
throughout this disclosure). Fig. 10A also uses a number to represent stator slot
number (i.e., Slot 1 is simplified as S 1; Slot 2 is simplified as S2; Slot 3 simplified
as S3; and Slot 4 simplified as S4). Fig. 10B shows an alternative way of
interconnected coil routing to that of Figure 10A with an independent coil winding
for each pair of poles. Fig. 10C shows a front view of the stator 110 illustrating
the stator magnetic pole vector (magnetic field pointing direction), in their
geometric positions reference to the slot at this timed commutation sequence
step. Fig. 10D is the corresponding settings of the commutator 400 switches.
[0083] Fig 11A illustrates an alternative embodiment of a three segment closed
type stator winding 1100. Fig 11B shows an electromechanical diagram of one
embodiment of a rotary commutator 1110. Fig. 11C shows a twelve step time
commutation sequence for the three segments closed type stator winding 1100.
Figs. 12A-12L show the current and stator magnetic field geometric positions with
reference to the stator slot for the twelve steps time commutation sequence for
the three segments closed type stator winding 1100. Each commutation step
advances approximately 30 degrees of magnetic field. Note all the even steps
have current cancelation in one slot which is undesirable. This even stepped
interval should ideally be kept as short as possible in the twelve step timed
commutation sequence or simply removed and instead electric half bridge dead
time control to facilitate the charging step should be used. The dead time control
is at no time both the high and low switch of the half bridges which would turn on
the same time to avoid current shoot through (or "short the power supply"). The
"dead time control" is performed by software or hardware. The physical time it
takes to perform dead time control provides enough time for the coils get charged
to advance the magnetic pole.
[0084] Figs. 13A-F show a front view of three slot stator 110 with current flow
direction and stator magnetic flux direction. In corresponding Figs. 13A and 13B,
the coils are drawn in two turns for easy of showing the end winding (outside of
slot coil winding) current direction. A coil in the back is drawn in dashed line and
drawn in solid line in the front. A plus sign in a circle shows current going into the
slot and a dot in the circle shows current flow out of slot. Fig.13A shows Coil # 1
getting charged together with Coil #2 and Coil #3. At this moment Coil # 1 trail
end is commutated to high potential segment *2 . In Figs. 13C and 13D, the Coil
# 1 charged magnetic field starts collapsing; current generated from the collapsing
field continues to flow to low potential segment 3* through Coil #2 which
strengthens the Coil #2 generated magnetic field; the result of the energy from the
collapsing field is redirected to build or strengthen an coming magnetic field in
commutation schedule and energy is captured inside the closed type stator
winding. The stator magnetic field is effectively advanced approximately 30
degrees on this commutation step. In Figs. 13E and 13F, when the Coil # 1 start
end is released from high potential segment 1* , Coil # 1 is getting charged with
electric energy as current which effectively advance the stator magnetic field.
Notice that the current in the end coil (outside of the slot) substantially equally
contributes to energize the stator magnetic field and is an integral part of the coil
winding to generate the stator magnetic field. As a result, this closed type stator
winding results in more stator power density. This characteristic of current flow is
especially beneficial for a very short slot motor stator.
[0085] FIG. 14 shows a segments potential graph of one full magnetic field
revolution of a twelve step timed commutation sequence for the three slot stator
100.
[0086] Fig. 15A shows an alternative six step timed commutation sequence for
the three slot stator 1100 version of DC motor assembly 100. Fig. 15B shows
segments potential graph of one full magnetic field revolution of the six step timed
commutation sequence. For such six step pseudo paced timed commutation
sequence, the stator magnetic field is advanced approximately sixty degrees from
the previous step with each step of commutation. Again there are unlimited
combinations of timed commutation sequences with varying step intervals,
however, only one twelve step paced timed commutation sequence and one
pseudo-paced six steps timed commutation sequence.
[0087] Fig 16 shows an embodiment of a twenty step timed commutation
sequence for a five segments closed type stator winding version of DC motor
assembly 100. Again all the even steps have current cancelation in one slot
which is vary undesirable and this even stepped interval should kept as short as
possible in the twenty step timed commutation sequence .
[0088] Fig. 17 shows a three segments four pole closed type stator winding
where P=3, N=1 , R=2, and S=6. Each coil occupies two slots one pair poles
apart.
[0089] Fig. 18 shows three segments six pole closed type stator winding where
P=3, N=4, R=3, and S=36. Each coil occupies four adjacent slots; the winding is
spilt into three same groups.
[0090] Fig. 19 shows three segments sixteen pole closed type stator winding
where P=3, N=2, R=8, and S=48. Each coil occupies two adjacent slots; the
winding is spilt into eight same groups.
[0091] Fig. 20 shows four segments two pole closed type stator winding where
P=4, N=2, R=1 , and S=8. Each coil occupies two adjacent slots.
[0092] Fig. 2 1 shows four segments six pole closed type stator winding where
P=4, N=3, R=3, and S=36. Each coil occupies three adjacent slots; the winding is
spilt into three equal groups.
[0093] Fig. 22 shows five segments two pole closed type stator winding where
P=5, N=1 , R=1 , and S=5.
[0094] Fig. 23 shows six segments two pole closed type stator winding where
P=6, N=1 , R=1 , and S=6.
[0095] Figs. 24A and 24B show six segments two pole closed type stator
winding where P=6, N=2, R= , and S= 2. Fig. 24A shows one de-energize step
and Figs. 24B shows one energize step
[0096] Fig. 25 shows eight segments two pole closed type stator winding where
P=8, N=1 , R=1 , and S=8.
[0097] Fig. 26 shows ten segments two pole closed type stator winding where
P=1 0, N=1 , R=1 , and S=1 0.
[0098] Fig. 27 shows twelve segments two pole closed type stator winding
P=1 2, N=1 , R=1 , and S=1 2.
[0099] A method of constructing a first specific example is described in relation
to the winding scheme of Fig. 9. A motor stator was constructed by taking apart
and rewinding from the beginning an electric sedan traction motor produced by
CODA Automotive™ of Los Angeles, California. This motor was a QUM™ brand
OEM three phase AC motor having a 48 slot stator. It was constructed with three
phase lap winding using 52 strand AWG 22 magnet wires for each phase. The
rotor for this motor was a 16 pole permanent magnetic type rotor. This motor
stator was then re-constructed and re-winded according to the methodology of
P=3, N=2, R=8, S = P x N x R=48. The eight three segment coil winding was
connected in parallel, each of the three coils in the winding, according to the
embodiments described herein, using 36 turns, 2 strand AWG #19 magnet wires
and occupies two slots. The commutator used for this reconstructed motor
utilized original analog portion of the VFD driver equipped with the sedan, and
reprogramed the Arduino Mega microprocessor, with the Fig. C commutation
sequence.
[01 00] A method of constructing a second specific example is described as
follows. A McLean Engineering™ model K33HXBLS-673 AC induction motor was
taken apart and rewound per Fig. 20, to form a four pole squirrel cage type DC
induction motor. Here the methodology used was: P=4, N=2, R=2, S = P x N x
R=16. The closed type stator winding was internally parallel connected. Each of
the eight windings was wound using 10 turns of AWG22 magnet wire. One
Atmel™ 328 MCU (ATmega328 8-bit AVR RISC-based microcontroller) was used
to drive four electric half bridges to generate the timed commutation sequence Fig
4A. The half bridge commutated 24VDC power from the DC power supply to the
motor windings to create four rotating magnetic poles on the stator.
[01 0 1] A method of constructing a third specific example is described as follows.
An Oriental Motor USA™ model E01 44-344 AC induction motor was taken apart
and reconstructed and rewound from the beginning to form a four pole squirrel
cage type DC induction motor. The stator was constructed as 12 segment closed
type winding Fig. 27. This winding was internally parallel connected and each
segment was connected to one pair of mechanical relays. Here the rotor was a
squirrel cage type rotor design. Each of the 24 windings was wound using 16
turns of AWG21 magnet wire. The commutator also used was one Atmel™ 328
MCU (ATmega328 8-bit AVR RISC-based microcontroller) to control the timed
commutation sequence. This device commutated DC power from generic 12V
DC power supply to the motor windings to create four rotating magnetic poles on
the stator.
[01 02] Motor assembly 100 described herein is similar to a universal motor.
The universal motor is so named because it is a type of electric motor that can
operate on both AC and DC power. It is a commutated series-wound motor
where the stator's field coils are connected in series with the rotor windings
through a commutator. The universal motor is very similar to a DC series motor
in construction, but is modified slightly to allow the motor to operate properly on
AC power. This type of electric motor can operate well on AC because the
current in both the field coils and the armature (and the resultant magnetic fields)
will alternate (reverse polarity) synchronously with the supply. Hence the
resulting mechanical force will occur in a consistent direction of rotation,
independent of the direction of applied voltage, but determined by the
commutator and polarity of the field coils.
[01 03] Fig. 28A shows a three phase AC current with artificially predetermined
twelve step segments potential points to match the timed commutation sequence
shown in Figure 28B (similar to Figure 1 C) for operation of an AC motor (e.g.,
AC motor assembly 2900 illustrated in Figure 29). The three segments closed
type stator segments have match potential as if it is commutated with DC,
however, now it is AC. This closed type winding can be naturally driven by a
three phase off grid utility alternating current (i.e., AC motors are self-commutating
as its name stands for alternating current). However this closed type stator
winding may be interpreted as a DC commutated winding. It is inherently an AC
motor stator winding while driven by a synchronized naturally self-commutating
AC. The AC may have a 120 degree phase angle offset. This closed type
winding is driven by self-commutating AC current does not need a commutator.
The closed type stator winding is AC/DC or universal winding.
[01 04] Figure 29 is a perspective view of an AC motor assembly 2900. The AC
motor assembly 2900 features a stator 2910, rotor 2920 and coil windings 291 2.
An AC motor assembly would be manufactured and operated in the same way
described herein as DC motor assembly 100 with the same varying number of
slots. As discussed in connection with DC motor assembly 100, the rotor 2920
can rotate inside the stator 291 0 in response to stator rotating magnetic fields
created by the coil windings 291 2. Very similar in structure to the DC motor
except the AC motor does not have a commutator but rather instead the speed of
the AC motor assembly 2900 is controlled by a variable frequency driver 2940
(shown external to the AC motor assembly 2900 but in alternative embodiments
may be located inside the AC motor assembly).
[01 05] A generator assembly would be manufactured and operate in the same
way described herein as DC motor assembly 100 and AC motor assembly 2900.
[01 06] As discussed, some of the benefits of the electric motors 100 and 2900
disclosed herein with reference to Figs. 1A-29 may include the following. First, an
electric motor that can operate at very high starting torque because the coils are
fully energized with DC current. This is generally comparable to the starting
torque provided by a brush type DC electric motor with permanent magnetic field,
but without the drawbacks of brushes inside the motor body. Second, an
electrical motor with a rotational speed that can be precisely controlled because
the rotation is progressed by timed commutation sequence steps. Such steps are
precisely controlled (for example by accurately timed electronics and/or electronic
processors) to a very high degree of accuracy. Third, an electric motor that
operates at higher efficiency and power density. This is because the improved
electrical motor stator can operate without brush related contact loss and the
winding is on the stator and easier to dissipate heat, thereby creating less heat
and improving efficiency. Fourth, an electric motor capable of operating with AC
current or DC current with commutation. It is more capable of variable speeds at
higher efficiencies than prior art AC motors powered by variable frequency drives
(VFD). This is because the motor avoids problems due to various VFD effects,
such as higher frequency pulse width modulation (PWM) switching loss, AC skin
effects, and motor total harmonic distortion (THD) related core losses. Fifth, in
some alternative embodiments, where the stator and rotator can be viewed as
having an almost infinite diameter meaning that there are no set limits on the
number of slots, there is also provided an improved linear DC electric motor as
well. Sixth, in some alternative embodiments, when paired with a permanent
magnetic rotor or squirrel cage rotor, there also may be provided a regenerative
motor, and act as a generator (based on Faraday's law of induction) when
external power is applied to the rotor. Seventh, other embodiments described
herein can also be applied in other types of electromechanical devices as well,
such as rotating magnetic bearings. Indeed any type of electromechanical device
where AC rotating magnetic fields are used may potentially be improved
according to the motors and methods described herein. Eighth, with up to four
steps per slot count commutation resolution when commutated, the stator winding
with timed commutation sequence together create a step motor, the stator
winding. Ninth, with a commutator placed outside the motor body, the DC motor
can be built enclosed. Traditional DC motors can be replaced by the motors
disclosed herein with much reduced maintenance cost. For example, the
commutator body can be easily replaced without ever opening the motor body.
Tenth, with end coil equally contributing to build the stator magnetic field, the
motors disclosed herein are more energy efficient and have more power density.
Tenth, with end coil equally contribute to create stator magnetic field, this closed
type stator winding saves copper. Eleventh, the motors disclosed herein are DC
motors while commuted with the timed commutation sequence and have the
advantage of traditional DC brush motor high starting torque and precision speed
control of AC motor. Twelfth, the electric motors are AC motors when powered by
utility AC or off the shelf VFDs. Thirteenth, the electric motors are stepper motors
with four steps per slot. Fourteenth, the electric motor disclosed herein is a
reluctant motor if fit with a reluctant rotor (i.e., a reluctant motor is a type of
electric motor that induces non-permanent magnetic poles on a ferromagnetic
rotor). Fifteenth, in the electric motors of this disclosure because current from a
collapsing magnetic field flows to low electric potential on the closed type stator
winding, there is no penalty for DC current switching. Sixteenth, the electric motor
is a high power true brushless DC, stepper and reluctant motor which can be built
with the simple control nature of DC current.
[01 07] The motor embodiments described herein provide an improved high
power density, high torque traction motor. This motor may be suitable for road
and track vehicles, marine vessel, railways, trolleys, subways, and other
applications where high torque, high power, and high efficiency is useful. Such
motors may also be used for automobiles, appliances, industrial automations,
medical devices, power tools robotics or any application that converts electric
energy to kinetic energy.
[01 08] The foregoing described embodiments have been presented for
purposes of illustration and description and are not intended to be exhaustive or
limiting in any sense. Alterations and modifications may be made to the
embodiments disclosed herein without departing from the spirit and scope of the
invention. No language in the specification should be construed as indicating any
non-claimed element as essential to the practice of the invention. The actual
scope of the invention is to be defined by the claims.
[01 09] The definitions of the words or elements of the claims shall include not
only the combination of elements which are literally set forth, but all equivalent
structure, material or acts for performing substantially the same function in
substantially the same way to obtain substantially the same result.
[01 10] The words used in this specification to describe the invention and its
various embodiments are to be understood not only in the sense of their
commonly defined meanings, but to include by special definition in this
specification any structure, material or acts beyond the scope of the commonly
defined meanings. Thus if an element can be understood in the context of this
specification as including more than one meaning, then its use in a claim must be
understood as being generic to all possible meanings supported by the
specification and by the word itself.
[01 11] Although process (or method) steps may be described or claimed in a
particular sequential order, such processes may be configured to work in
different orders. In other words, any sequence or order of steps that may be
explicitly described or claimed does not necessarily indicate a requirement that
the steps be performed in that order unless specifically indicated. Further, some
steps may be performed simultaneously despite being described or implied as
occurring non-simultaneously (e.g., because one step is described after the other
step) unless specifically indicated. Moreover, the illustration of a process by its
depiction in a drawing does not imply that the illustrated process is exclusive of
other variations and modifications thereto, does not imply that the illustrated
process or any of its steps are necessary to the embodiment(s), and does not
imply that the illustrated process is preferred. Where a process is described in
an embodiment the process may operate without any user intervention.
[01 12] Devices that are described as in "communication" with each other or
"coupled" to each other need not be in continuous communication with each
other or in direct physical contact, unless expressly specified otherwise. On the
contrary, such devices need only transmit to each other as necessary or
desirable, and may actually refrain from exchanging data most of the time. For
example, a machine in communication with or coupled with another machine via
the Internet may not transmit data to the other machine for long period of time
(e.g. weeks at a time). In addition, devices that are in communication with or
coupled with each other may communicate directly or indirectly through one or
more intermediaries.
[01 13] Neither the Title (set forth at the beginning of the first page of the present
application) nor the Abstract (set forth at the end of the present application) is to
be taken as limiting in any way as the scope of the disclosed invention(s). The
title of the present application and headings of sections provided in the present
application are for convenience only, and are not to be taken as limiting the
disclosure in any way.
CLAIMS
1. A direct current (DC) electric motor system comprising:
a stator having a closed type winding including at least three coils which
produce a stator rotating magnetic field which is coupled with a rotor magnetically,
the rotor capable of rotating when induced by the stator rotating magnetic field;
a commutator coupled to the stator and which controls the stator rotating
magnetic field through a timed commutation sequence; and
wherein the stator and the at least three coils are configured so that energy
released from a collapsing stator rotating magnetic field on a de-energizing
commutation step in a first of the at least three coils is captured by a second of
the at least threes coils energized on a next step of an energizing commutation
step.
2 . The motor system of claim 1 wherein the stator comprises:
at least three stator slots in mechanically defined geometric positions with
respect to each other separated by ridges formed from magnetically active
material.
3 . The motor system of claim 1, wherein each of said at least three coils have at
least one conductor, at least one turn and occupy at least one of the at least three
stator slots.
4 . The motor system of claim 1, wherein at least one of the at least three coils is
wound in the stator by having the at least one coil front side going in a first slot of
the at least three stator slots and bypassing at least one other of the at least three
stator slots to have the at least one coil back side return in a second slot of the at
least three stator slots and a trail end of the said at least one coil connected to the
start end of a next successive coil of the at least three coils to form a commutation
segment connection.
5 . The motor system of claim 1, wherein the closed type winding further
generates at least one pair of magnetic poles when current flows through the at
least one coil of the winding while commutated with the commutator.
6 . The motor system of claim 1, wherein the closed type winding is wound to
create a multiple pole stator winding by using the stator winding formula: S = P x
N x R, where S is total slot count on the stator, P is at least three commutation
segments of the closed type stator winding with at least two pole, N is at least one
actual slots count each coil occupies, and R is at least one stator magnetic pole
pair count and S ranges from 3 to 500.
7 . The motor system of claim 1 wherein the de-energizing commutation step is at
both ends of the first of the at least three coils which is commutated to less
differential potential and changes the current flow pattern in the closed type
winding so as to advance the rotating magnetic field by a commutation step of the
commutation sequence.
8 . The motor system of claim 1 wherein the energizing commutation step is at
both ends of the second of the at least three coils which is commutated to more
differential potential and changes the current flow pattern in the closed type
winding so as to advance the stator rotating magnetic field by a commutation step
in the commutation sequence.
9 . The motor system of claim 1 wherein at the de-energizing commutation step,
the current generated from part of a collapsing stator rotating magnetic field
continuously flows in the direction of a previous current direction to a lowest
electric potential inside the closed type stator winding until part of a the collapsing
stator rotating magnetic field is substantially completely collapsed and the current
generated from the collapsing stator rotating magnetic field helps build a next
rising stator rotating magnetic field in a next step of the commutation sequence.
10. The motor system of claim 1, wherein the stator rotating magnetic field
advances at least one step at a time to generate a time varying geometrically
separated magnetic field according to a timed commutation.
11. The motor system of claim 1, each of the at least three coils further
comprising:
a slot coil portion and an out of slot portion, wherein the current in the slot
portion and the out of slot portion contribute to generate the stator rotating
magnetic field to improve a power density of the closed type winding.
12. The motor system of claim 1, wherein the commutator is configured to
produce a timed commutation sequence which controls commutator switches to
switch commutation segments progressively to positive or negative or disconnect
to a DC power source to create the stator rotating magnetic field.
13. The motor system of claim 1, wherein the commutator comprises:
at least six commutator switches to connect or disconnect each of the
commutation segments to positive or negative of a DC power source according to
a timed commutation sequence so as to change the electric potential of a
switched commutation segment which is energizing or de-energizing the at least
three coils to advance the stator rotating magnetic field.
14. The motor system of claim 1 wherein the commutator comprises:
a plurality of electric switches selected from the group consisting of: a
rotary mechanical switch, a mechanical relay, silicon electronic solid state
switches, a transistor, a metal-oxide-semiconductor field-effect transistor
(MOSFET), an insulated gate bipolar transistor (IGBT), an integrated gatecommuted
thyristor (IGCT),
15. The motor system of claim 1 wherein the commutator comprises:
a rotary mechanical switch including at least three commutation segments
sequentially arranged in circular pattern and coaxially there with mechanically and
electrically to contact a rotary electric pole.
16. The motor system of claim 1 wherein the commutator comprises:
a rotary mechanical switch further including at least two rotating electric
poles which are configured to rotate coaxially there with and to mechanically and
electrically contact the stationary of at least three commutation segments
sequentially according to the commutation sequence.
17. The motor system of claim 16 wherein the at least two rotating electric poles
comprise:
a positive electric pole and a negative electric pole, said positive electric
pole configured to allow current flow into a contacted commutation segment and
said negative electric pole configured to allow current to flow out of the contacted
commutation segment.
18. The motor system of claim 1, wherein the motor system can be used in any of
the group consisting of: an electric traction motor, a railway engine, a trolley
engine, a subway engine, an electric vehicle traction motor, a vehicle's auxiliary
motor, an industrial automation control motor, an aviation vehicle, a marine
vessel, a robotic machine, an automobile, an appliance, industrial automation
equipment, a medical device, and a power tool.
19. An alternating current (AC) induction electric motor system comprising:
a stator having a closed type winding including at least three coils which
produce a stator rotating magnetic field which is coupled with a rotor magnetically,
the rotor capable of rotating when induced by the stator rotating magnetic field;
a variable frequency drive coupled to the stator and which controls the
stator rotating magnetic field; and
wherein the stator and the at least three coils are configured so that energy
released from a collapsing stator rotating magnetic field in a first of the at least
three coils is captured by a second of the at least three coils.
20. A method for producing a stator rotating magnetic field in a direct current
(DC) electric motor system comprising:
producing the stator rotating magnetic field from a closed type winding of a
stator including at least three coils coupled with a rotor magnetically, the rotor
capable of rotating when induced by the stator rotating magnetic field;
controlling the stator rotating magnetic field with a commutator through a
timed commutation sequence; and
wherein the stator and the at least three coils are configured so that energy
released from a collapsing stator rotating magnetic field on a de-energizing
commutation step in a first of the at least three coils is captured by a second of
the at least threes coils energized on a next step of an energizing commutation
step.
2 1. The motor system of claim 12, wherein the timed commutation sequence
is generated by coupling a position of the rotor with built in position sensors in
the stator as a closed loop feedback and the commutator is configured so that
when a first commutation step is commanded and the rotor is induced to a first
detected position then a second commutation step is commanded so that the
rotor is induced to a second detected position.
22. The motor system of claim 2 1 wherein the position sensors can be any of
the group consisting of: a magnetic sensor, an optical sensor, and a solid state
switch.