DESC:TECHNICAL FIELD
[0001] The present subject matter described herein generally relates to a vehicle, and
particularly but not exclusively relates to an electrical machine of a vehicle.
[0002] BACKGROUND Conventionally, the motor that converts the alternating
10 current into mechanical power by using an electromagnetic induction
phenomenon is called an Alternating Current (AC) motor. This motor is driven by
an alternating current. The stator and the rotor are the two most important parts of
the AC motors. The stator is the stationary part of the motor, and the rotor is the
rotating part of the motor. The AC motor can be either single phase or three
15 phase.
[0003] The three phase AC motors are mostly applied in the industry for bulk power
conversion from electrical to mechanical. For small power conversion, the single
phase AC motors are used. Usually, the single phase AC motor is small in size,
and provides a variety of services in the home, office, business concerns,
20 factories, etc. Almost all the domestic appliances such as refrigerators, fans,
washing machine, hair dryers, mixers, etc., use single phase AC motor.
[0004] The AC motor is mainly classified into two types. They are the synchronous
motor and the induction motor. Synchronous motors convert the AC electrical
power into mechanical power and are operated at synchronous speed. When
25 electrical supply is given to synchronous motor, a revolving field is set up. This
field tries to drag the rotor with it, but faces hindrance because of the rotor inertia.
Hence, no starting torque is produced. Thus, inherently synchronous motors are
not self-starting motors. The motor which can convert the AC electric power into
mechanical power by using an electromagnetic induction phenomenon in called
30 an induction motor. The induction motor is mainly classified into two types, i.e., a
single phase induction motor and a three phase induction motor.
3
5 BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The detailed description is described with reference to a two wheeled vehicle
along with the accompanying figures. The same numbers are used throughout the
drawings to reference like features and components.
[0006] Fig. 1 illustrates a side view of a conventional scooter type vehicle when
10 viewed from left hand side of the rider while he is in riding position.
[0007] Fig. 2 illustrates a cross section of a two pole and twelve slot motor, as per
an embodiment of the present subject matter.
[0008] Fig. 2a illustrates a cross section of a two pole and twelve slot motor, as per
an embodiment of the present subject matter.
15 [0009] Fig. 2b illustrates a schematic conventional three phase winding connection
of a two pole and twelve slot motor, with a concentrated conventional winding
pattern.
[00010] Fig. 2c illustrates a block diagram of conventional three phase winding
connection all four coils of a phase A.
20 [00011] Fig. 2d illustrates the four coils of phase A and the direction of flow of
current on the stator windings as per an embodiment of the present subject matter.
[00012] Fig 3a illustrates a six phase winding connection of a three phase motor as
per an embodiment of the present subject matter.
[00013] Fig. 3b illustrates a block diagram of a motor using a six phase winding
25 connection as per an embodiment of the present subject matter.
[00014] Fig. 4 illustrates a graph showing per slot MMF distribution in a motor
using both conventional three phase winding connection and presently claimed
six phase winding connection.
[00015] Fig. 5 illustrates a graph between the intensity of the harmonics and the
30 number of harmonics produced while using both conventional three phase
winding connection and presently claimed six phase winding connection in a
motor.
4
5
DETAILED DESCRIPTION
[00016] Conventionally, in an induction motor the rotor winding serves as both the
armature winding and field winding and when the stator windings are connected
to an AC supply a flux is produced in the air gap. The flux rotates at a fixed speed
10 called synchronous speed. This rotating flux induces voltage in the rotor winding.
If the rotor circuit is closed, current flows through the rotor winding, reacts with
the rotating flux and thereby produces a torque. In the steady state, the rotor
rotates at a speed which is very close to synchronous speed.
[00017] Currently, permanent magnet synchronous motors (PMSMs) are used
15 instead of AC induction motors due to their advantages over the AC induction
motors. These advantages include higher torque with smaller frame size and no
rotor current. These permanent magnet synchronous motors are brushless and
have very high reliability and efficiency.
[00018] The PMSMs exhibit high torque density and high energy efficiency over a
20 wide operation range, due to the presence of the permanent magnets. Therefore,
they have increasingly been employed in a variety of applications, such as
industrial drives, hybrid and electric vehicles, wind turbine, aerospace, marine,
and domestic appliances, etc. With their high power-to-size ratio, the PMSMs can
help in making the motor design smaller without the loss of torque. Subject to the
25 locations of the permanent-magnets, PMSMs can be classified into Surfacemounted Permanent-magnet Machines (SPMs) and Interior Permanent-magnet
Machines (IPMs). With magnets mounted on the rotor surface, SPMs produce
torque by the interaction of the magnetic field contributed by permanent-magnets
with the armature reaction field produced by the stator magnetic-motive force
30 (MMF).
[00019] Therefore, SPMs exhibit a relatively linear torque-current characteristic,
good controllability, and low torque ripple. Nevertheless, the surface-mounted
magnets result in a large equivalent air-gap because the relative permeability of
5
5 magnets is close to 1. Hence, synchronous inductance of the machine is relatively
low, leading to a high characteristic current, defined as the ratio of the PM flux to
the synchronous inductance, and thereby low field weakening capability.
[00020] In some known arts concentrated windings on SPMs has been employed and
hence the developed SPM is capable of delivering constant power over a specified
10 speed range by increasing the inductance and meeting the optimum field
weakening conditions.
[00021] In some other known arts, a synthesis of SPMs with concentrated windings
is performed and subsequently their performances are compared with those of
SPMs using conventional distributed windings. In such known arts it is shown
15 that by using the concentrated winding configuration, the copper loss can be
reduced dramatically owing to both the short end-winding length and the high
copper packing factor (if the segmented stator structure is employed). Moreover,
the cogging torque can also be significantly reduced when the least common
multiple of the slot number and the pole number increases. Therefore, SPMs with
20 concentrated windings exhibit advantages such as high torque density, low copper
loss, good field weakening capability, and low cogging torque.
[00022] However, by employing concentrated winding configurations in SPMs, the
rotor magnets are subjected to a large amount of stator MMF harmonics which are
asynchronous with the rotor speed, and consequently incur high eddy current loss.
25 For example, in a two pole three phase motor with twelve slots design, a
significant 5th and 7th harmonics in the magneto motive force (MMF) is noticed,
which can result in increased rotor loss, hence reduced performance.
[00023] This can further lead to a high rotor temperature particularly at high speeds,
and hence the rotor magnets will suffer from a high risk of irreversible
30 demagnetization.
[00024] Compared with SPMs, IPMs have magnets buried in the rotor iron. The IPM
rotor topology gives rise to asaliency in reluctances. To maximize the reluctance
torque, the distributed winding configurations are usually employed in IPMs.
6
5 However, compared to the concentrated windings, the conventional distributed
windings have lower copper packing factor (slot fill factor), longer end-winding
length, higher cogging torque, and less fault tolerant owing to higher mutual
inductance and winding overlapping.
[00025] Thus, the concentrated winding configurations are of potential to be
10 employed in IPMs, given that the lower and higher order space harmonics in the
stator MMF can be suppressed to a desirable level. This can increase IPMs’
reluctance torque production, reduce the eddy-current losses in both rotor magnets
and rotor iron, and suppress acoustic noise and vibrations. Therefore, both SPMs
and IPMs can greatly benefit from the reduction of the stator MMF harmonics in
15 the concentrated windings.
[00026] In other known arts MMF harmonic reduction techniques are employed in
three-phase motors. Such techniques include MMF harmonic reduction by
alteration of the stator geometry which requires optimization of the motor design.
For example, increasing the number of slots of the stator and use of multiple layer
20 of the winding. Such alteration of the stator geometry results in increase of the
size and the weight of the motor.
[00027] The increasing of the number of slots of the stator without increasing the
size and weight of the motor is ideally not desired to be employed in a motor
which is designed to rotate at a high speed. This is because, with the increase in
25 the number of slots in the same available space, the material width between the
slots decreases. This decrease in the material width compromises with the torque
of the motor, when working at high speeds. Also there exists a challenge of
improving reliability of the motor since known art designs of motors come to halt
in case of any fault in the windings of the motor.
30 [00028] Hence there is a need of a reliable and robust winding scheme of a motor
which results in significant reduction in the MMF harmonics without changing
the stator geometry; and size and weight of the motor.
7
5 [00029] The present subject matter has been devised in view of the above
circumstances as well as solving other problems of the known art.
[00030] In an embodiment of the present subject matter, the present subject matter
relates to a winding scheme of an electrical machine, for example a motor that has
reduced MMF harmonics characteristics. As per an aspect of the present
10 embodiment the claimed winding scheme has total six phases that includes two
separate sets of three phase winding connection, instead of a single winding
connection, when compared with a conventional winding scheme of a motor. The
second set of three phase system has a separate power supply. As per another
aspect of the present embodiment the two separate sets of the three-phase winding
15 connection has a phase shift of 30 degree where the coil in the leading slot i.e.
second set of three phase system is leading and hence the two sets of power
supply has a phase difference of 30 degree.
[00031] As per an efficacy of the present embodiment because of the two sets of
three phase winding connection, in case of fault in any one set of winding the
20 other set can keep the motor working and hence aid in increasing the redundancy
and reliability of the motor.
[00032] As per another aspect of the present embodiment the fundamental harmonics
are dominating while the higher order harmonics for example, a fifth and a
seventh harmonics are considerably reduced, when compared with a three -phase
25 two pole conventional winding scheme of a motor. Resultant to which as an
efficacy, the claimed winding scheme has improved fundamental harmonics when
compared to the fundamental harmonics of a conventional winding scheme.
[00033] As per another embodiment of the present subject matter the claimed
scheme of winding scheme of the motor is capable of being applied to a motor
30 design of a two wheeled electric vehicle, a three wheeled electric vehicle and
designing of a motor for industrial applicability.
8
5 [00034] As per another efficacy of the present claimed subject matter, the claimed
winding scheme is capable of achieving reduced harmonics without increasing the
weight or size of the motor on which the present claimed winding scheme is being
applied. Therefore the present claimed winding scheme does not involve any
vehicular structural layout changes and enables a compact design of the vehicle.
10 [00035] As per another efficacy the present claimed subject matter, since the claimed
winding design does not lead to altering of the stator geometry, the torque of the
motor is maintained even at high speed and therefore efficient high-speed
operation of the motor is maintained and better motor performance is achieved.
[00036] Exemplary embodiments detailing features regarding the aforesaid and other
15 advantages of the present subject matter will be described hereunder with
reference to the accompanying drawings. Various aspects of different
embodiments of the present invention will become discernible from the following
description set out hereunder. Rather, the following description provides a
convenient illustration for implementing exemplary embodiments of the
20 invention.It should be noted that the description and figures merely illustrate
principles of the present subject matter. Various arrangements may be devised
that, although not explicitly described or shown herein, encompass the principles
of the present subject matter. Moreover, all statements herein reciting principles,
aspects, and examples of the present subject matter, as well as specific examples
25 thereof, are intended to encompass equivalents thereof.Further, it is to be noted
that terms “upper”, “down”, “right”, “left”, “front”, “forward”, “rearward”,
“downward”, “upward”, “top”, “bottom”, “exterior”, “interior” and like terms are
used herein based on the illustrated state or in a standing state of the two wheeled
vehicle with a driver riding thereon. Furthermore, arrows wherever provided in
30 the top right corner of figure(s) in the drawings depicts direction with respect to
the vehicle, wherein an arrow F denotes front direction, an arrow R indicates rear
direction, an arrow Up denotes upward direction, an arrow Dw denotes downward
9
5 direction, an arrow RH denotes right side, and an arrow LH denotes left side.
Also, it is to be understood that the phraseology and terminology used herein is
for the purpose of description and should not be regarded as limiting.
[00037] Fig. 1 illustrates a side view of a conventional scooter type vehicle 100
when viewed from left hand side of the rider while he is in riding position. The
10 conventional scooter type vehicle 100 is generally provided with a power unit 101
that generates the power required to propel the vehicle forward, and a frame 102,
which further includes a front frame (not shown), a central frame (not shown) and
a rear frame 105 joined together to form the frame 102, and a power transmission
unit 106, which transfers the power generated by the power unit 101 to the rear
15 wheel 107, and a front wheel 108 at front portion of the vehicle 100 below the
front frame which is steerable by the rider, and a handle bar unit 109 comprising
of a left handle bar grip 110 and a right handle bar grip (not shown) which the
rider can use to steer the front wheel 108 in the desired direction, and a front
suspension unit 112 for smooth force transmission to the front wheel 108, and a
20 rear suspension unit 113 for smooth force transmission to the rear wheel 107.In
such vehicles especially which are fast charging, high voltage system parts of
battery, controller, motor, charger, charging socket and DC charging protective
relays needs to be packaged. Therefore, at times all high voltage system parts are
packaged nearby in one location, which reduces the high voltage wires length
25 connecting these parts and thus increasing safety and minimizing power loss.
[00038] The front frame (not shown) includes a head tube (not shown) and a down
tube (not shown); the head tube supports the front suspension unit 112, which
further supports the handle bar unit 109 in a steerable manner and the down tube
extends rearward and downward of the head tube. The central frame has two
30 tubes (not shown) on the left and right of the conventional scooter type vehicle
100 extending away and then substantially parallel from each other in a rearward
direction. The left and right tubes are connected by a cross frame (not shown)
extending in vehicle width direction. These left and right tubes further extend
10
5 rearward and upward to form the rear frame 105, which supports other units of the
vehicle 100 at rear portion.
[00039] A front panel 116 is provided ahead of the head tube for covering the head
tube when viewed from the front of the vehicle 100. A panel rear (not shown),
extending downwards from the head tube, covers the head tube and down tube
10 from the rear side. A front fender 119 is provided above the front wheel 108, in
the vicinity of the front suspension unit 112, to prevent mud splashing onto the
internal articles of the vehicle 100 at the front portion. A handle bar panel rear
(not shown), at least partly covers the handle bar unit 109, from the rear side. A
handle bar front panel 121 at least partly covers the handle bar unit 109 from front
15 side. A glove box 118 is mounted on the panel rear, below the handle bar panel
rear and above the floor board 124. A headlamp unit 122 is disposed on the
handle bar front panel 121 and mirror units 123 are disposed on the handle bar
unit 109 through the handle bar front panel 121.Asthere are many electrical parts
in the vehicle 100. Therefore, the routing of wiring harness in many such vehicles
20 100 is done along an RH side of the frame 102. The fuel tank (not shown) being
positioned in a floor board 124 area, the wires are routed to connect to the floor
board 124 mounted electrical parts like fuel pump, fuel sensor unit and then the
wires are extended to connect to the side stand switch.
[00040] An interfacing portion of the handle bar front panel 121 and the handle bar
25 panel rear has a cut-out zone (not shown) on left side and right side for projecting
the left handle bar grip 110 and right handle bar grip respectively. A floor board
124 as leg resting panel is provided above the central frame to cover a top portion
of the central frame and a bottom panel 125 is provided below the central frame to
cover a bottom portion of the central frame.
30 [00041] On the rear side, a utility unit 126 is disposed, at the space between the left
and right tubes at the rear portion of the vehicle 100 above the power unit 101, to
store articles. The utility unit 126 is mounted onto the cross tube at the front
11
5 portion and rear portion, thus getting supported by the rear frame. A seat unit 127
is provided, above the utility unit 126 and extending throughout the rear frame,
for the rider to sit over and maneuver the vehicle 100. The seat unit 127 is
mounted onto the vehicle 100 through a hinge unit 128, provided on the utility
unit 126, such that the seat can be opened by rotating it about the hinge unit 128
10 to provide access to the storage area 129 of the utility unit 126.
[00042] A side panel LH 130 is provided on the left side of the rear frame and a side
panel RH (not shown) is provided on the right side of the rear frame so as to
cover the internal components when viewed from left and right sides of the
conventional scooter type vehicle 100 respectively. A front cover 131 is disposed
15 ahead of the utility unit 126 and below the seat unit 127 to cover the internal
components, such as the power unit 101, frame 102 in a vehicle perspective view.
A rear cover 132 is provide rearward to the rear frame and an opening formed by
assembling the rear cover 132 and the side panel units 130 is used to place a tail
lamp117 on the rear side. A rear fender 120 is disposed above the rear wheel 107
20 to prevent mud splashing onto internal components while riding. A grab rail 111
is disposed in the vicinity of the seat unit 127, on the rear portion of the
conventional scooter type vehicle 100, to enable a pillion rider to grab for support.
[00043] Fig. 2 illustrates a cross section of a two pole and twelve slot motor 200, as
per an embodiment of the present subject matter. The main components of the
25 motor 200 are a stator 205 and a rotor 215. The stator 205 is the fixed part of the
motor 200 and the rotor 215 is the rotating part of the motor 200. For most motors
200 the rotor 215 is located inside the stator 205.
[00044] The stator 205 consists of a stator outer frame 205a and a stator core 205b
with a predefined number of stator windings 220. The stator outer frame 205a is
30 called back-iron and 205b is called teeth of the stator 205. The stator core 205b is
assembled from thin-sheet technical steel, usually 0.5 mm thick, covered with
12
5 insulating varnish. Stator core 205b laminations significantly limit the losses
(eddy currents losses) arising in the process of magnetic reversal of the stator core
205b by a rotating magnetic field. The stator windings 220 are wound across the
motor 200 by means of plurality of slots 210 present on the stator core 205b.
[00045] The rotor 215 of the electric motor 200 consists of a core and a shaft 225.
10 The rotor core also has a laminated construction. There is a small distance
between the rotor 215 and the stator 205 of the motor 200, called as an air gap
235, which typically ranges between 0.5 mm to 2 mm.
[00046] As per the present illustration, a three-phase set of stator windings 220 is
inserted in the designated slot 210 present on the inside portion of the stator 205.
15 These stator windings 220 may be connected either in a wye configuration,
normally without external connection to the neutral point, or in a delta
configuration. The rotor 215 consists of a cylindrical iron core with magnets (not
shown) placed in slots 210 around the surface. In the most usual form, these rotor
magnets (not shown) are connected together at each end of the rotor 215 by a
20 conducting end ring 230.The principle of operation of a three-phase motor 200 is
based on the ability of a three-phase stator windings 220 to create a rotating
magnetic field when it is connected to a three-phase electric power system. Since
the stator windings 220 are connected to a three-phase electric supply, therefore a
set of three sinusoidal currents flow in the stator windings 220. As a result of
25 which a magnetic field across the air gap 235 of the electric motor 200 is
produced.
[00047] Fig. 2a illustrates a cross section of a two pole and twelve slot motor 200, as
per an embodiment of the present subject matter. The three phases of each three
phase motor 200 include phase A, phase B and phase C. A1, A2, A3 and A4 are
30 the four coils of Phase A. Similarly, B1, B2, B3 and B4 are the four coils of Phase
B and C1, C2, C3, and C4 are four coils of the Phase C. The positive sign of the
respective coil, for example, A1+, represents one end of the respective coil and
the negative sign of the respective coil, for example, A1-, represents another end
13
5 of the respective coil. The positive or negative sign notation after coil numbering
represents the direction of flow of the current in that respective coil. The positive
sign (A1+, A2+ etc.) represents the ongoing path of the current and similarly
negative sign (in A1-, A2- etc.) denotes the return path of the supplied current.
Therefore, as the motor winding of the present illustrated figure is a double layer
10 winding, there are total 12 coils in the stator windings 220 (shown in Fig. 2).
Since the present motor 200 is a three-phase motor so, there are 4 coils for every
phase (A or B or C).
[00048] The winding of four coils of every phase (A or B or C) is placed inside the
slots 210 are wound across the teeth 205b present on the stator 205 of the motor
15 200. In the present illustrated figure the number of slots 220 is 12.
[00049] Fig. 2b illustrates a schematic conventional three phase winding connection
300 of a two pole and twelve slot motor 200, with a concentrated conventional
winding pattern. In case of three-phase supply all the four coils of each phase are
connected in series. For example, for phase A, the coils A1, A2, A3 and A4 are
20 connected in series. Similarly, for phase B, the coils B1, B2, B3 and B4 are
connected in series. Similarly for phase C, the coils C1, C2, C3 and C4 are
connected in series.
[00050] Fig. 2c illustrates a block diagram of conventional three phase winding
connection 300 of all four coils of a phase A. In case of three-phase supply all the
25 four coils of each phase are connected in series. For example, for phase A, the
coils A1, A2, A3 and A4 are connected in series. Such series connection results in
decreasing the motor 200 redundancy, as failure of one coil can result in the
failure of the motor 200.
[00051] Fig. 2d illustrates the four coils of phase A and the direction of flow of
30 current on the stator windings 220 as per an embodiment of the present subject
matter. The present illustration shows four coils of phase A, i.e. A1, A2, A3 and
A4 as stator windings 220. The arrows present on the stator windings 220 shows
the direction of flow of current, that is the current is flowing from the positive end
14
5 of each coil towards its respective negative end. As per the illustration the motor
200 moves in an anticlockwise direction. The plurality of slots 210 present on the
stator core 205b (shown in Fig. 2) comprises of at least one leading slot 210ls and
at least one lagging slot 210ts.
[00052] Fig 3a illustrates a six phase winding schematic connection 400 of a three
10 phase motor 200 as per an embodiment of the present subject matter. The present
illustration shows the winding connection of a two pole three-phase motor 200
that includes two coils for each phase (A or B or C) for both set of three-phase
connection. Each phase (A or B or C) includes a first set 305 and a second set
310. Each of the first set 305 and the second set 310 further include two coils per
15 set. For example, for phase A alone, the stator windings 220 is done in a manner
that phase A has a first set 305 including A2 and A4 and phase A has a second set
310 including A1 and A3. The first set 305 and the second set 310 have two
separate power supply with a suitable phase-shift among them. Resultant to which
waveform of A1 is similar to A3 and waveform of A2 is similar to A4. Because
20 of this two sets of three phase winding connection, in case of a fault in any one of
the set of the six phase winding connection 400, i.e. either the first set 305 or the
second set 310, the other set is capable of keeping the motor 200 in working
condition and hence redundancy of the motor 200 is increased and thereby
reliability is improved.
25 [00053] The second set 310 of each of the 3 phases (A or B or C) is positioned such
that the second set 310 is always 30-degree electrically leading with respect to the
first set 305 of each of the three phases (A or B or C) of the six phase winding
connection 400.
[00054] As per the proposed six phase winding connection 400,the two pole three
30 phase motor 200 has poly-phase offset of 1 slot i.e. the second set 310 of three
phase winding is starting from one slot 210 (shown in Fig. 2) next to the starting
slot 210 of the first set 305 of stator windings 220 (shown in Fig. 2).The second
set 310 of the stator windings 220 is leading with respect to the first set 305, as
15
5 the second set 310 starts from the leading slot 220 of the stator 205 (shown in Fig.
2).
[00055] The winding connection of two separate three phase motor 200 is shown in
Fig. 3a, which illustrates that the coils A1 and A3 belong to a single subset, while
the coils A2 and A4 belong to another subset. When the rotor 215 is moving in
10 anticlockwise direction, at any point of time, as shown in Fig. 2d, the second
subset starts with offset of 1 slot and there is a poly-phase offset of one slot 110
between at least one leading slot 210ls and at least one lagging slot 210ts. Similar
winding scheme is followed for subset of coils B and C.
[00056] As per the proposed six phase winding connection 400, the slot pitch
15 is 30-degree mechanical, as there are 12 slots in the stator 205.
Therefore, the slot pitch mechanical ????= (360 degree/number of slots);
= 360 degree /12 = 30 degree
[00057] Similarly, as per the proposed six phase winding connection 400, the
slot pitch in the electrical degree ????
is also 30-degree electrical as there are two
20 poles in the motor 200.
???? =
??
2
????
where P = number of poles
???? =
2
2
????
???? = ????= 30 degree
25 [00058] Therefore, the back EMF induced in the leading slot 210ls will aid the
leading slot 210ls to lead the trailing slot 210ts by 30-degree angle. For example,
the leading slot 210ls includes the slots 210 containing A1 and A3; and trailing
slots 210ts include slots containing A2, A4. . Since the back-EMF in leading slot
210ls is 30 degree leading which is induced by the rotor 215 magnetic field; and
30 as per present subject matter the current supply in the leading slot 210ls is at 30
degree with respect to the current supplied in the lagging slot 210ts, thus
16
5 maximizing the interaction between the two fields and enabling achievement of
the best possible MMF harmonics reduction.
[00059] With reduced MMF harmonics without increasing the weight or size
of the motor 200 the present claimed six phase winding connection 400 scheme
does not involve any vehicular structural layout changes.
10 [00060] Because of the present configuration of six phase winding connection
400 the fundamental harmonics dominates while the higher order harmonics for
example, a fifth and a seventh harmonics are considerably reduced, when
compared with a three -phase two pole conventional winding scheme of a motor
200. The reduction of the fifth and the seventh harmonic of the motor 200 and
15 improvement of fundamental harmonic, reduces the rotor 215 losses of the motor
200, hence increases the motor 200 performance.
[00061] Moreover, the proposed design does not lead to altering of the
geometry of the stator 205 and hence aids in reducing the size and weight of the
motor 200.Thus the torque of motor 200 is maintained even at high speeds of the
20 motor 200 and therefore efficient high-speed operation of the motor 200 is
maintained and better motor performance is achieved when compared with
motors 200 having three phase conventional winding connection 300 (shown in
Fig. 2b).
[00062] Fig. 3b illustrates a block diagram of the winding connections of a motor
25 200 using a six phase winding connection 400 as per an embodiment of the
present subject matter. As per the present illustrated block diagram for the six
phase winding connection 400 includes a two phase set of three phase system.
The coils are connected in set of two coils in series. For example, for phase A,
two sets of coils are present. One set includes coil A1 and coil A3 and the other
30 set includes coil A2 and coil A4. And these two sets 305, 310 (shown in Fig.
3a)further have separate power supply..
[00063] Fig. 4 illustrates a graph showing MMF distribution per slot 210
(shown in Fig. 2) in a motor 200 using both conventional three phase winding
17
5 connection 300 and presently claimed six phase winding connection 400. As per
the illustrated graph the proposed six-phase winding configuration 300 is depicted
by straight line X and the conventional three phase winding connection 300 is
depicted by dashed line Y. A sinusoidal wave in form of dotted Z line is drawn
mapping the MMF distribution of both X and Y line on the graph. It is clear from
10 the graph that the MMF distribution of the line X is more sinusoidal when
compared to the MMF distribution of the line Y, because the line graph depicting
X shows more steps when compared to the line graph depicting Y.. Also it can be
seen that the deviation of the line X from the sine wave Z at any point of time is
less with respect to deviation of line Y which depicts more sinusoidal form of line
15 X. Therefore, more sinusoidal form of MMF distribution depicts lesser harmonics
hence reduced eddy current losses. This further result in decreased rotor 215 loss
hence increased performance.
[00064] Fig. 5 illustrates a graph between the intensity of the harmonics and
the number of harmonics produced while using both conventional three phase
20 winding connection 300 and presently claimed six phase winding connection 400
in a motor 200. The graph illustrates that the intensity of the harmonics
especially, the intensity of the fifth and seventh harmonics are considerably
reduced in situation where the proposed six phase winding connection 400 is used
as depicted by dashed Y bar. The dark shade X bar depicts number of harmonics
25 produced when conventional winding methods are used. The graph further depicts
that it is the first harmonic, that is the fundamental harmonic,and is additionally
improved when proposed six phase winding connection 400 is used. This
improving of the fundamental harmonic and the considerable reduction of the
fifth and seventh harmonic aid in reduction of the iron losses of the motor 200.
30 Hence reduced eddy current losses are reduced, which further results in decreased
rotor 215 loss and increased performance of the motor 200.
[00065] Many modifications and variations of the present subject matter are
possible in the light of above disclosure. Therefore, within the scope of claims of
18
5 the present subject matter, the present disclosure may be practiced other than as
specifically described.
,CLAIMS:I/We Claim:
1. An electrical machine (200), of a vehicle (100) characterized in that:
said electrical machine (200) comprises:
a rotor (215); and
a stator (205), wherein said stator (205) includes circumferentially spaced
10 twelve slots (210); wherein,
said twelve slots (210) comprise a plurality of winding connection
(400); wherein,
said plurality of winding connection (400) comprises two
sets of three phase winding (A,B,C); wherein,
15 each phase (A,B,C) of said two sets of three phase
windings (A,B,C) comprises two or more set of coils (305,
310); wherein,
said two or more set of coils (305, 310)
are shifted by an electrical angle
20 30 degrees (????)with respect to each other.
2. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
two or more set of coils (305, 310) includes a first set of coils (305) and a second
set of coils (310) of separate three phases (A,B,C) of stator winding (220).
3. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
25 said electrical machine (200) is a motor.
4. The electrical machine (200) of a vehicle (100) as claimed in claim 2, wherein
said second set (310) is leading with respect to said first set (305).
5. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
each phase (A or B or C) of said two sets of three phase winding (A,B,C)
30 includes two or more coils (A1, A2, A3, A4, B1, B2. B3, B4, C1, C2, C3, C4).
6. The electrical machine (200) of a vehicle (100) as claimed in claim 5, wherein
said two or more coils (A1, A2, A3, A4, B1, B2. B3, B4, C1, C2, C3, C4) in
20
5 each phase (A or B or C) of said two sets of three phase winding (A,B,C) are
connected in series with each other.
7. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
said first set (305) and said second set (310) have separate power supply.
8. The electrical machine (200) of a vehicle (100) as claimed in claim 2, wherein
10 said first set (305) and said second set (310) includes two or more coils (A1,
A2, A3, A4, B1, B2. B3, B4, C1, C2, C3, C4) having similar wave form.
9. The electrical machine (200) of a vehicle (100) as claimed in claim 3, wherein
said motor (200) is a two pole three phase motor (200).
10. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
15 said twelve slots (210) include one or more leading slots (210ls) and one or
more lagging slots (210ts).
11. The electrical machine (200) of a vehicle (100) as claimed in claim 9, wherein
said two pole three phase motor (200) has a poly-phase offset of at least one
slot (110) between at least one leading slot (210ls) and at least one lagging slot
20 (210ts).
12. The electrical machine (200) of a vehicle (100) as claimed in claim 11, wherein
a back-EMF induced by a rotor (215) magnetic field, in said one or more
leading slot (210ls) is 30 degrees leading.
13. The electrical machine (200) of a vehicle (100) as claimed in claim 12, wherein
25 a current supply in said leading slot (210ls) is at 30 degree difference with
respect to the current supplying in said lagging slot (210ts).
14. The electrical machine (200) of a vehicle (100) as claimed in claim 9, wherein
said two pole three phase motor (200) has a poly-phase offset in the windings
of one slot (110).
30 15. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
stator windings (220) are connected in a wye configuration.
16. The electrical machine (200) of a vehicle (100) as claimed in claim 1, wherein
stator windings (220) are connected in a delta configuration.