FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CONTROL DEVICE FOR ROTARY MACHINE
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TITLE OF THE INVENTION: CONTROL DEVICE FOR ROTARY MACHINE
TECHNICAL FIELD
[0001] The present disclosure relates to a control device5
for a rotary machine.
BACKGROUND ART
[0002] A control device for a rotary machine having a
field winding and a stator winding generates current commands10
for currents flowing through the field winding and the stator
winding, in accordance with operation commands for torque, a
rotational speed, and the like of the rotary machine, which
are inputted from the outside. The control device for the
rotary machine performs control so that currents flowing15
through the field winding and the stator winding follow the
current commands. In general, the impedance of the field
winding is greater than the impedance of the stator winding,
and thus it is known that response of the current flowing
through the field winding is slower than response of the20
current flowing through the stator winding. Therefore, in
order to appropriately control the rotary machine, the
conventional control device for the rotary machine performs
control while taking into consideration the fact that current
response of the field winding is slower than current response25
3
of the stator winding.
[0003] In one conventional control method for a rotary
machine, a current command for a stator winding is calculated
on the basis of variation in torque caused by variation in
delay of current response of a field winding (see, for5
example, Patent Document 1). In another control method,
response delay of current of a field winding with respect to
a current command is simulated, and a current command for a
stator winding is calculated on the basis of the simulated
response delay (see, for example, Patent Document 2).10
CITATION LIST
PATENT DOCUMENT
[0004] Patent Document 1: Japanese Laid-Open Patent
Publication No. 2022-8390515
Patent Document 2: WO2020/217438
SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0005] However, in such conventional control methods for a20
rotary machine, in a case where delay of current response of
the field winding is slower than assumed, or in a case where
current actually flowing through a stator winding cannot
follow a current command for the stator winding because of
variation in specifications, the amplitude of the current25
4
command for the stator winding might become greater than
assumed. In this case, if the amplitude of the current
command for the stator winding exceeds an upper limit value
of voltage that the control device can output, a voltage
command might be saturated. If the voltage command is5
saturated, windup of integral control in the control device,
magnetic flux interference between the stator winding and the
field winding in the rotary machine, and the like are caused.
As a result, current control for the rotary machine becomes
unstable.10
[0006] The present disclosure has been made to solve the
above problem, and an object of the present disclosure is to
provide a control device for a rotary machine that can
perform stable current control while suppressing saturation
of a voltage command for a stator winding, even in a case15
where the amplitude of a current command for the stator
winding might become greater than assumed.
MEANS TO SOLVE THE PROBLEM
[0007] A control device for a rotary machine according to20
the present disclosure is a control device for a rotary
machine including a rotor having a field winding and a stator
having a stator winding, the control device including: a
current command generation unit which generates a field
winding current command for current flowing through the field25
5
winding and a stator winding current command for current
flowing through the stator, on the basis of an operation
command inputted from outside; a field winding voltage
command unit which generates a field winding voltage command
for voltage to be applied to the field winding, on the basis5
of the field winding current command; a stator winding
voltage command unit which generates a stator winding voltage
command for voltage to be applied to the stator winding, on
the basis of the stator winding current command; a field
winding power conversion unit which applies voltage to the10
field winding on the basis of the field winding voltage
command; and a stator winding power conversion unit which
applies voltage to the stator winding on the basis of the
stator winding voltage command. The current command
generation unit includes: a field winding current command15
generation unit which generates the field winding current
command on the basis of the operation command and DC voltage
inputted from outside; a stator winding current command
correction unit which generates a state variable for
correcting the stator winding current command, on the basis20
of the current flowing through the field winding and the
field winding current command generated by the field winding
current command generation unit; and a stator winding current
command generation unit which generates the stator winding
current command on the basis of the operation command and the25
6
state variable generated by the stator winding current
command correction unit.
EFFECT OF THE INVENTION
[0008] In the control device for the rotary machine5
according to the present disclosure, the current command
generation unit includes: the field winding current command
generation unit which generates the field winding current
command on the basis of the operation command and the DC
voltage inputted from outside; the stator winding current10
command correction unit which generates the state variable
for correcting the stator winding current command, on the
basis of the current flowing through the field winding and
the field winding current command generated by the field
winding current command generation unit; and the stator15
winding current command generation unit which generates the
stator winding current command on the basis of the operation
command and the state variable generated by the stator
winding current command correction unit. Thus, it is
possible to perform stable current control while suppressing20
saturation of the voltage command for the stator winding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] [FIG. 1] FIG. 1 is a configuration diagram of a
control device for a rotary machine according to embodiment25
7
1.
[FIG. 2] FIG. 2 is a configuration diagram of a
stator winding power conversion unit according to embodiment
1.
[FIG. 3] FIG. 3 is a configuration diagram of a5
field winding power conversion unit according to embodiment
1.
[FIG. 4] FIG. 4 is a configuration diagram of a
field winding power conversion unit according to embodiment
1.10
[FIG. 5] FIG. 5 is a configuration diagram showing
a function of a processor according to embodiment 1.
[FIG. 6] FIG. 6 is a configuration diagram showing
a function of a current command generation unit according to
embodiment 1.15
[FIG. 7] FIG. 7 is a configuration diagram showing
a function of a stator winding current command correction
unit according to embodiment 1.
[FIG. 8] FIG. 8 shows a final field winding
current command outputted from a field winding current20
command selection unit according to embodiment 1.
[FIG. 9] FIG. 9 shows a DC voltage value outputted
from a DC voltage correction unit according to embodiment 1.
[FIG. 10] FIG. 10 illustrates operation with
respect to a stator winding voltage margin in embodiment 1.25
8
[FIG. 11] FIG. 11 shows characteristics of a
control device for a rotary machine in a comparative example
with respect to embodiment 1.
[FIG. 12] FIG. 12 shows characteristics of the
control device for the rotary machine according to embodiment5
1.
[FIG. 13] FIG. 13 shows characteristics of the
control device for the rotary machine according to embodiment
1.
10
DESCRIPTION OF EMBODIMENTS
[0010] Hereinafter, a control device for a rotary machine
according to embodiments for carrying out the present
disclosure will be described in detail with reference to the
drawings. In the drawings, the same reference characters15
denote the same or corresponding parts.
[0011] Embodiment 1
FIG. 1 is a configuration diagram of a control
device for a rotary machine according to embodiment 1. A
control device 1 for a rotary machine according to the20
present embodiment controls a rotary machine 2. The control
device 1 is driven by DC voltage of an external DC power
supply 3. The control device 1 includes a stator winding
power conversion unit 4, a field winding power conversion
unit 5, a stator winding current detection unit 6 which25
9
detects current flowing through a stator winding, a field
winding current detection unit 7 which detects current
flowing through a field winding, a processor 8, and a storage
device 9. The control device 1 for the rotary machine
according to the present embodiment controls the rotary5
machine 2 on the basis of operation commands inputted from a
host device. The operation commands inputted from the host
device are, for example, a torque command and a rotational
speed command for respectively determining torque and a
rotational speed of the rotary machine 2, and the like.10
[0012] The rotary machine 2 includes a rotor having a
permanent magnet and the field winding, and a stator having
one set of stator windings for three phases, i.e., U phase, V
phase, and W phase. The rotor may not necessarily have a
permanent magnet. The stator windings are not limited to a15
configuration of having one set of three phases, and a
configuration of having one or more sets of three or more
phases may be adopted.
[0013] The stator winding power conversion unit 4 converts
DC voltage of the DC power supply 3 to AC voltage, and20
applies AC voltage to the stator windings. The field winding
power conversion unit 5 converts DC voltage of the DC power
supply 3 to DC voltage having a different amplitude, and
applies the DC voltage as field winding voltage Vf to the
field winding. The stator winding current detection unit 625
10
detects currents flowing through the stator windings for U
phase, V phase, and W phase of the rotary machine 2. The
field winding current detection unit 7 detects current
flowing through the field winding of the rotary machine 2.
[0014] FIG. 2 is a configuration diagram of the stator5
winding power conversion unit according to the present
embodiment. FIG. 2 shows an example of the stator winding
power conversion unit 4 in the present embodiment. As shown
in FIG. 2, the stator winding power conversion unit 4 in the
present embodiment is a three-phase full-bridge inverter10
composed of six switching elements and six diodes. The
configuration of the stator winding power conversion unit 4
is a configuration for a case where the rotary machine has
one set of stator windings for three phases, i.e., U phase, V
phase, and W phase. Each switching element is formed of a15
MOS-FET (metal oxide semiconductor-field effect transistor),
an IGBT (insulated gate bipolar transistor), or the like.
The stator winding power conversion unit 4 applies AC
voltages to the stator windings for U phase, V phase, and W
phase of the rotary machine 2 in accordance with a stator20
winding switching command inputted from the processor 8.
Specifically, the stator winding power conversion unit 4
applies AC voltages according to switching commands UH and UL
for U phase, switching commands VH and VL for V phase, and
switching commands WH and WL for W phase from the processor25
11
8, to the stator windings for U phase, V phase, and W phase
of the rotary machine 2. The stator winding power conversion
unit 4 is not limited to an inverter, and may be a converter.
The configuration of the inverter of the stator winding power
conversion unit 4 may be any configuration having one or more5
sets of three or more phases in accordance with the number of
phases of the stator windings of the rotary machine 2.
[0015] FIG. 3 is a configuration diagram of the field
winding power conversion unit according to the present
embodiment. FIG. 3 shows an example of the field winding10
power conversion unit 5 in the present embodiment. As shown
in FIG. 3, the field winding power conversion unit 5 in the
present embodiment is a two-phase full-bridge converter
composed of four switching elements and four diodes. Each
switching element is formed of a MOS-FET, an IGBT, or the15
like. The field winding power conversion unit 5 applies DC
voltage to the field winding of the rotary machine 2 in
accordance with a field winding switching command inputted
from the processor 8. Specifically, the field winding power
conversion unit 5 converts DC voltage inputted from the DC20
power supply 3 to DC voltage having a different amplitude in
accordance with switching commands F1H, F1L, F2H, F2L for the
field winding from the processor 8, and applies the converted
DC voltage to the field winding of the rotary machine 2. For
example, in a case where a torque command inputted to the25
12
processor 8 is a command for increasing an amplitude, the
field winding power conversion unit 5 controls application
voltage so that current of the field winding increases in the
positive direction. Conversely, in a case where a torque
command inputted to the processor 8 is a command for5
decreasing an amplitude, the field winding power conversion
unit 5 controls application voltage so that current of the
field winding increases in the negative direction.
[0016] FIG. 4 is a configuration diagram of the field
winding power conversion unit according to the present10
embodiment. FIG. 4 shows another example of the field
winding power conversion unit 5 in the present embodiment.
As shown in FIG. 4, the field winding power conversion unit 5
is configured such that, in the field winding power
conversion unit shown in FIG. 3, the switching elements for15
applying voltage in the negative direction to the field
winding are replaced with diodes. Therefore, this field
winding power conversion unit 5 is reduced in cost as
compared to the field winding power conversion unit shown in
FIG. 3. However, this field winding power conversion unit 520
cannot apply voltage in the negative direction to the field
winding. Therefore, in a case where a torque command is to
decrease an amplitude, current response of the field winding
greatly depends on a time constant of a resistance and an
inductance of the field winding, and thus the current25
13
response of the field winding is extremely slow as compared
to current response of the stator winding.
[0017] The stator winding current detection unit 6 and the
field winding current detection unit 7 are, for example,
current sensors of a resistance detection type, a magnetic5
field detection type, or the like. The stator winding
current detection unit 6 detects stator winding currents IU,
IV, IW flowing through the stator windings for U phase, V
phase, and W phase of the rotary machine 2. The field
winding current detection unit 7 detects field winding10
current If flowing through the field winding of the rotary
machine 2.
[0018] The processor 8 is, for example, a CPU (Central
Processing Unit), and executes a program read from the
storage device 9, to implement various functions. The15
program to be executed by the processor 8 is stored in the
storage device 9. The storage device 9 includes a volatile
storage device such as a random access memory and an
auxiliary storage device such as a flash memory. When the
processor 8 reads the program from the storage device 9, the20
processor 8 reads the program stored in the auxiliary storage
device via the volatile storage device. The processor 8 may
output data such as a calculation result to the volatile
storage device of the storage device 9, or may store such
data into the auxiliary storage device via the volatile25
14
storage device.
[0019] FIG. 5 is a configuration diagram showing a
function of the processor. As shown in FIG. 5, the processor
8 includes a current command generation unit 81, a stator
winding voltage command unit 82, a stator winding switching5
command generation unit 83, a field winding voltage command
unit 84, and a field winding switching command generation
unit 85.
[0020] The current command generation unit 81 receives
operation commands such as a torque command and a rotational10
speed command, DC voltage of the DC power supply 3, the
stator winding currents IU, IV, IW detected by the stator
winding current detection unit 6, and the field winding
current If detected by the field winding current detection
unit 7. The current command generation unit 81 generates15
stator winding current commands Id*, Iq* and a field winding
current command If* on the basis of the above inputs. Here, a
d axis is a center axis of a magnetic pole formed by the
permanent magnet and the field winding of the rotor, and a q
axis is an axis orthogonal to the d axis. Hereinafter,20
indices d and q attached to notations of current and voltage
mean the d axis and the q axis, respectively.
[0021] On the basis of the stator winding current commands
Id*, Iq* generated by the current command generation unit 81
and the stator winding currents IU, IV, IW detected by the25
15
stator winding current detection unit 6, the stator winding
voltage command unit 82 generates stator winding voltage
commands so that stator winding currents follow the stator
winding current commands. At this time, the stator winding
voltage command unit 82 performs coordinate conversion of the5
stator winding currents IU, IV, IW to Id, Iq on the basis of
rotor position information of the rotary machine 2, and then
calculates voltage commands Vd*, Vq* using decoupling control
and PI (Proportional-Integral) control so that Id and Iq
follow Id* and Iq*. Further, the stator winding voltage10
command unit 82 converts Vd* and Vq* through coordinate
conversion to stator winding voltage commands VU*, VV*, VW*.
The rotor position information of the rotary machine 2 can be
detected by means such as a resolver or an encoder attached
to the rotary machine 2, although not shown. Alternatively,15
rotor position information estimated by a rotor position
estimator may be used as the rotor position information of
the rotary machine 2.
[0022] In a case where voltage amplitudes of the stator
winding voltage commands VU*, VV*, VW* calculated by the stator20
winding voltage command unit 82 exceed a voltage amplitude
that the stator winding power conversion unit 4 can output,
the stator winding voltage command unit 82 limits the voltage
amplitudes as described later, and outputs VU*, VV*, VW* having
the limited voltage amplitudes to the stator winding25
16
switching command generation unit 83. Hereinafter, a case
where voltage amplitudes of the stator winding voltage
commands exceed the voltage amplitude that the stator winding
power conversion unit 4 can output is referred to as voltage
saturation.5
[0023] Although depending on the performances of the
rotary machine, the control device, and the DC power supply,
wirings thereof, and the like, voltage saturation is less
likely to occur in a control region in which the rotational
speed of the rotary machine is smaller than 20% of the10
maximum rotational speed. However, as the rotational speed
of the rotary machine increases, induced voltage becomes
higher, so that voltage saturation becomes more likely to
occur. When voltage saturation has occurred, windup of
integral control in the control device and the like occur, so15
that current control for the rotary machine becomes unstable
and response becomes slow or oscillates. Therefore, it is
desirable that the stator winding voltage commands VU*, VV*,
VW* are set so as not to cause voltage saturation if
possible. Here, windup of integral control refers to a20
phenomenon in which, in a case where there is a great
deviation between a target value and the present value when
integral control is started, if voltage saturation has
occurred, the present value cannot approach the target value
and an integral value becomes excessive, resulting in25
17
overshoot.
[0024] However, in a case where, due to variation in the
specifications of the rotary machine and the like, an
inductance and a magnetic flux generated in the rotary
machine are different from those assumed, voltage saturation5
can occur accidentally. When voltage saturation has
occurred, it is desired that control (hereinafter, referred
to as flux weakening control) for correcting the stator
winding current commands Id*, Iq* and the field winding
current command If* so as to reduce the voltage amplitudes is10
incorporated.
[0025] The method for performing control so that Id and Iq
follow Id* and Iq* in the stator winding voltage command unit
82 is not limited to PI control. Control performed by the
stator winding voltage command unit 82 may be control in15
which one or more of P (proportional) control, I (integral)
control, and D (derivative) control are combined, for
example. Control performed by the stator winding voltage
command unit 82 is not limited to feedback control such as PI
control and may be feedforward control. In a case of20
employing decoupling control, feedforward control, or the
like as control performed in the stator winding voltage
command unit 82, rotational speed information needed for
voltage calculation can be calculated from rotor position
information.25
18
[0026] The stator winding switching command generation
unit 83 compares the stator winding voltage commands VU*, VV*,
VW* calculated by the stator winding voltage command unit 82
with a carrier wave, to generate the switching commands UH
and UL for U phase, the switching commands VH and VL for V5
phase, and the switching commands WH and WL for W phase. The
stator winding switching command generation unit 83 outputs
the generated switching commands to the stator winding power
conversion unit 4. In general, a triangular wave is used as
the carrier wave, but the carrier wave may not necessarily be10
a triangular wave. The stator winding switching command
generation unit 83 may generate the switching commands
without comparison with a carrier wave.
[0027] On the basis of the field winding current command
If* generated by the current command generation unit 81 and15
the field winding current If detected by the field winding
current detection unit 7, the field winding voltage command
unit 84 generates a field winding voltage command so that the
field winding current follows the field winding current
command. At this time, the field winding voltage command20
unit 84 calculates the field winding voltage command Vf*
using PI control so that the field winding current If follows
the field winding current command If*.
[0028] In a case where the voltage amplitude of the field
winding voltage command Vf* calculated by the field winding25
19
voltage command unit 84 exceeds a voltage amplitude that the
field winding power conversion unit 5 can output, the field
winding voltage command unit 84 limits the voltage amplitude
and outputs Vf* having the limited voltage amplitude to the
field winding switching command generation unit 85. As in5
the case of the stator winding voltage command, a case where
the voltage amplitude of the field winding voltage command
exceeds the voltage amplitude that the field winding power
conversion unit 5 can output is referred to as voltage
saturation. As with the stator winding voltage command, it10
is desirable that the field winding voltage command Vf* is
set so as not to cause voltage saturation if possible.
[0029] The method for performing control so that If
follows If* in the field winding voltage command unit 84 is
not limited to PI control. Control performed by the field15
winding voltage command unit 84 may be control in which one
or more of P control, I control, and D control are combined,
for example. Control performed by the field winding voltage
command unit 84 is not limited to feedback control such as PI
control and may be feedforward control.20
[0030] The field winding switching command generation unit
85 compares the field winding voltage command Vf* calculated
by the field winding voltage command unit 84 with a carrier
wave, to generate a field winding switching command. In a
case where the field winding power conversion unit 5 has the25
20
configuration shown in FIG. 3, the field winding switching
command generation unit 85 generates the field winding
switching commands F1H, F1L and F2H, F2L. In a case where
the field winding power conversion unit 5 has the
configuration shown in FIG. 4, the field winding switching5
command generation unit 85 generates the switching commands
F1H, F1L. Then, the field winding switching command
generation unit 85 outputs the generated switching commands
to the field winding power conversion unit 5. In general, a
triangular wave is used as the carrier wave, but the carrier10
wave may not necessarily be a triangular wave. The field
winding switching command generation unit 85 may generate the
switching commands without comparison with a carrier wave.
[0031] FIG. 6 is a configuration diagram showing the
function of the current command generation unit. As shown in15
FIG. 6, the current command generation unit 81 includes a
field winding current command generation unit 810, a stator
winding current command correction unit 811, and a stator
winding current command generation unit 812.
[0032] The field winding current command generation unit20
810 receives DC voltage, and the torque command and the
rotational speed command which are operation commands. The
field winding current command generation unit 810 has a
lookup table having combinations of a torque command, a
rotational speed command, DC voltage, and a field winding25
21
current command. On the basis of the lookup table, the field
winding current command generation unit 810 generates the
field winding current command If* from the received operation
commands and DC voltage. The lookup table is determined by a
power factor, an output, loss, and the like of the rotary5
machine. In a case of a usage method in which DC voltage
does not change, DC voltage need not be inputted. The field
winding current command generation unit 810 may not
necessarily use a lookup table to generate the field winding
current command. The field winding current command10
generation unit 810 may generate a field winding current
command on the basis of a relational equation among a torque
command, a rotational speed command, DC voltage, and a field
winding current command.
[0033] The stator winding current command correction unit15
811 receives the field winding current If, the field winding
current command If* generated by the field winding current
command generation unit 810, and DC voltage. The stator
winding current command correction unit 811 generates a state
variable described later, on the basis of the field winding20
current If, the field winding current command If*, and DC
voltage, and outputs the state variable to the stator winding
current command generation unit 812.
[0034] The stator winding current command generation unit
812 receives the state variable, and the torque command and25
22
the rotational speed command which are operation commands.
The stator winding current command generation unit 812 has a
map or a function representing the relationship among the
operation command, the state variable, and the stator winding
current commands Id*, Iq*. On the basis of the map or the5
function, the stator winding current command generation unit
812 generates the stator winding current commands Id*, Iq*
from the received operation command and state variable. For
example, the stator winding current command generation unit
812 generates the stator winding current commands Id*, Iq* so10
that the power factor, output, torque, current response
followability, and the like of the rotary machine become a
maximum value, a minimum value, or a value therebetween.
[0035] In the rotary machine, as the rotational speed
increases, induced voltage increases. Therefore, the stator15
winding current command generation unit 812 needs to have
such a map or a function that implements flux weakening
control so that the amplitude of the stator winding voltage
command does not exceed the upper limit value of voltage that
the stator winding power conversion unit 4 can output, in20
accordance with the rotational speed. As the flux weakening
control, for example, control in which a d-axis magnetic flux
and a q-axis magnetic flux are weakened, and in particular,
control in which a d-axis magnetic flux is decreased, are
generally used.25
23
[0036] FIG. 7 is a configuration diagram showing the
function of the stator winding current command correction
unit. As shown in FIG. 7, the stator winding current command
correction unit 811 includes a field winding current response
simulation unit 8110, a field winding current separation5
determination unit 8111, a field winding current command
selection unit 8112, a DC voltage correction unit 8113, and a
stator winding voltage margin calculation unit 8114.
[0037] The field winding current response simulation unit
8110 receives the field winding current command If* generated10
by the field winding current command generation unit 810.
The field winding current response simulation unit 8110 has a
LPF (low pass filter), a state equation, a map, a function,
and the like for simulating response of current flowing
through the field winding. On the basis of the LPF, the15
state equation, and the like, the field winding current
response simulation unit 8110 generates a field winding
current command If** simulating response of current flowing
through the field winding, from the received field winding
current command If*. Here, current flowing through the field20
winding on the basis of the field winding current command If**
simulating response of current flowing through the field
winding is referred to as field winding response current.
[0038] In a case where the stator winding current command
correction unit 811 includes the field winding current25
24
response simulation unit 8110 when generating the stator
winding current command on the basis of the field winding
current command, the stator winding current command can be
generated at a value closer to response of current flowing
through the field winding, as compared to a case of not5
including the field winding current response simulation unit
8110. Thus, the control device for the rotary machine
according to the present embodiment provides an effect of
improving transient efficiency change, torque response, and
the like of the rotary machine. However, the stator winding10
current command correction unit 811 in the present embodiment
may not necessarily include the field winding current
response simulation unit 8110.
[0039] The field winding current separation determination
unit 8111 receives the field winding current If, and the15
field winding current command If** which is generated by the
field winding current response simulation unit 8110 and
simulates response of current. The field winding current
separation determination unit 8111 determines the magnitude
of separation between If and If**. Here, the field winding20
current separation determination unit 8111 outputs the
determined magnitude of separation to the field winding
current command selection unit 8112 and the DC voltage
correction unit 8113.
[0040] The field winding current command selection unit25
25
8112 receives the field winding current If, the field winding
current command If** which is generated by the field winding
current response simulation unit 8110 and simulates response
of current, and the magnitude of separation between If and
If** determined by the field winding current separation5
determination unit 8111. On the basis of the magnitude of
separation between If and If**, the field winding current
command selection unit 8112 outputs a final field winding
current command If*** for stator winding current command
generation. As described later, the field winding current10
command selection unit 8112 also receives a stator winding
voltage margin calculated by the stator winding voltage
margin calculation unit 8114.
[0041] FIG. 8 shows the final field winding current
command outputted from the field winding current command15
selection unit. In FIG. 8, the horizontal axis indicates the
magnitude of separation between If and If**, and the vertical
axis indicates the final field winding current command If***
outputted from the field winding current command selection
unit 8112. As shown in FIG. 8, when the separation between20
If and If** is small, the field winding current command
selection unit 8112 outputs If** as the final field winding
current command, and when the separation between If and If**
is great, the field winding current command selection unit
8112 outputs If as the final field winding current command.25
26
When the separation between If and If** is middle, the field
winding current command selection unit 8112 outputs a
weighted average value between If and If** according to the
separation, as the final field winding current command.
[0042] In the control device for the rotary machine5
configured as described above, in a steady state, the stator
winding current command can be generated so as not to be
influenced by harmonic current of If detected by the field
winding current detection unit, and in a transient state, the
stator winding current command according to current If10
actually flowing through the field winding can be generated.
Therefore, not only transient efficiency change and torque
response of the rotary machine can be improved, but also the
stator winding current commands Id*, Iq* can be appropriately
generated even in a case where there is separation between If15
and If**.
[0043] The separation between If and If** is due to error
and variation regarding characteristic values assumed in the
control device and electrical and mechanical specifications
of the rotary machine, for example. Therefore, it is20
impossible to perfectly eliminate separation between If and
If**. In a case where the configuration of the field winding
power conversion unit is simplified as in the configuration
shown in FIG. 4, the separation between If and If** further
increases.25
27
[0044] The DC voltage correction unit 8113 receives DC
voltage and the magnitude of separation between If and If**
determined by the field winding current separation
determination unit 8111. The DC voltage correction unit 8113
corrects DC voltage on the basis of the received magnitude of5
separation between If and If**, and outputs the corrected DC
voltage value. As described later, the DC voltage correction
unit 8113 also receives the stator winding voltage margin
calculated by the stator winding voltage margin calculation
unit 8114.10
[0045] FIG. 9 shows a DC voltage value outputted from the
DC voltage correction unit 8113. In FIG. 9, the horizontal
axis indicates the magnitude of separation between If and
If**, and the vertical axis indicates the corrected DC voltage
value outputted from the DC voltage correction unit 8113. As15
shown in FIG. 9, when the separation between If and If** is
small, the DC voltage correction unit 8113 does not correct
the DC voltage of the DC power supply 3 or corrects the DC
voltage by a reduced correction amount, and when the
separation between If and If** is great, the DC voltage20
correction unit 8113 corrects the DC voltage of the DC power
supply 3 to a smaller value. As shown in FIG. 9, it is
preferable that determination for whether to increase or
decrease the correction value with respect to the magnitude
of separation is imparted with a hysteresis characteristic25
28
for preventing chattering due to pulsation of the magnitude
of separation.
[0046] As described above, in a case where the amplitude
of If is greater in the positive direction than the amplitude
of If**, it is likely that the amplitude of the voltage5
command for the stator winding exceeds the upper limit value
of voltage that the stator winding power conversion unit can
output and thus voltage saturation occurs. In the control
device for the rotary machine configured as described above,
the stator winding current command can be generated so that10
the voltage amplitude has a margin from the upper limit value
of voltage that the stator winding power conversion unit can
output. Thus, it is possible to assuredly suppress transient
voltage saturation with fast response.
[0047] The stator winding voltage margin calculation unit15
8114 receives the field winding current If, the field winding
current command If** which is generated by the field winding
current response simulation unit 8110 and simulates response
of current, and DC voltage. The stator winding voltage
margin calculation unit 8114 has a map or a function20
representing the relationship among the field winding current
If, the field winding current command If** simulating response
of current, DC voltage, and the stator winding voltage
margin. Here, the stator winding voltage margin is a
difference between the amplitude of the stator winding25
29
voltage command calculated from If and If** and the upper
limit of the voltage amplitude that the stator winding power
conversion unit 4 can output. On the basis of the map or the
function, the stator winding voltage margin calculation unit
8114 calculates the stator winding voltage margin from the5
received field winding current If and the received field
winding current command If** simulating response of current.
Then, the stator winding voltage margin calculation unit 8114
outputs the calculated stator winding voltage margin to the
field winding current command selection unit 8112 and the DC10
voltage correction unit 8113.
[0048] The stator winding voltage margin calculation unit
8114 may calculate the stator winding voltage margin on the
basis of the torque command and the rotational speed command
which are operation commands, the stator winding voltage15
command, DC voltage, and the like.
[0049] FIG. 10 illustrates operation with respect to the
stator winding voltage margin. As shown in FIG. 10, in a
case where the stator winding voltage margin is great, it is
determined that correction in the field winding current20
command selection unit 8112 and the DC voltage correction
unit 8113 is not needed. In a case where the stator winding
voltage margin is small, correction in the field winding
current command selection unit 8112 and the DC voltage
correction unit 8113 is needed. As shown in FIG. 10, it is25
30
preferable that determination for whether or not correction
is needed with respect to the stator winding voltage margin
is imparted with a hysteresis characteristic for preventing
chattering. Here, correction in the field winding current
command selection unit 8112 means selecting If** or a weighted5
average value between If and If** as the final field winding
current command If***, instead of selecting If. Correction in
the DC voltage correction unit 8113 means correcting DC
voltage on the basis of the magnitude of separation between
If and If**.10
[0050] Determination for whether or not correction shown
in FIG. 10 is needed may be performed in the stator winding
voltage margin calculation unit 8114, or may be performed in
each of the field winding current command selection unit 8112
and the DC voltage correction unit 8113.15
[0051] By the stator winding voltage margin calculation
unit 8114 operating as described above, it is possible to
perform operation so as not to unnecessarily exert flux
weakening control in a low rotational speed region in which
the stator winding voltage has a margin. Basically, the20
field winding current separation determination unit 8111 and
the stator winding voltage margin calculation unit 8114 are
provided as one set including these two. However, in a case
where only one of them can be provided due to constraints in
program capacity, only one of them may be provided as an25
31
alternative configuration using the fact that separation of
the field winding current and the stator winding voltage
margin are correlated with each other.
[0052] The stator winding current command correction unit
811 sends, as state variables, the final field winding5
current command If*** outputted from the field winding current
command selection unit 8112 and the corrected value of DC
voltage outputted from the DC voltage correction unit 8113,
to the stator winding current command generation unit 812.
That is, the state variables include at least one of10
information about current flowing through the field winding
and information about DC voltage of the DC power supply 3.
Here, information about current flowing through the field
winding is the final field winding current command If*** and
is at least one of the value of current flowing through the15
field winding, the field winding current command, and the
field winding response current simulating response of current
flowing through the field winding, or information obtained by
combining at least two of these.
[0053] Voltage saturation is less likely to occur in a20
control region in which the rotational speed of the rotary
machine is smaller than 20% of the maximum rotational speed.
Therefore, in the control device for the rotary machine
according to the present embodiment, the stator winding
current command correction unit may be set so as to operate25
32
in a case where the rotational speed of the rotary machine is
not smaller than 20% of the maximum rotational speed.
[0054] Next, operation of the control device for the
rotary machine according to the present embodiment will be
described.5
In the control device for the rotary machine
according to the present embodiment, behaviors of the stator
winding current, the field winding current, and the amplitude
of the stator winding voltage command in a case where the
torque command is changed to 0 from a predetermined value10
(hereinafter, referred to as a prescribed value) greater than
0, will be described. First, behaviors in a control device
for a rotary machine in a comparative example in which the
stator winding current command correction unit is not
provided, will be described.15
[0055] FIG. 11 shows the stator winding current, the field
winding current, and the amplitude of the stator winding
voltage command, in a case where the torque command is
changed from the prescribed value to 0, in the control device
for the rotary machine in the comparative example in which20
the stator winding current command correction unit is not
provided. In FIG. 11, FIG. 11(a) shows the torque command,
FIG. 11(b) shows the stator winding current, FIG. 11(c) shows
the field winding current, and FIG. 11(d) shows the amplitude
of the stator winding voltage command.25
33
[0056] As shown in FIG. 11(b), in the control device for
the rotary machine in the comparative example in which the
stator winding current command correction unit is not
provided, since the torque command, the rotational speed
command, the uncorrected DC voltage, and the field winding5
current command If* (in this comparative example, the field
winding current command has a waveform that does not simulate
field current response) are inputted to the stator winding
current command generation unit 812, the stator winding
current commands Id*, Iq* sharply change following the10
waveform of the torque command. Similarly, as shown in FIG.
11(c), in the control device for the rotary machine in the
comparative example in which the stator winding current
command correction unit is not provided, the field winding
current command If* also sharply changes following the15
waveform of the torque command. Since current response of
the field winding is slower than current response of the
stator winding, the field winding current If actually flowing
through the field winding cannot follow If*. Therefore, the
stator winding currents Id, Iq actually flowing through the20
stator windings cannot follow Id*, Iq*. As a result, as shown
in FIG. 11(d), the amplitude of the stator winding voltage
command exceeds the upper limit value of voltage that the
stator winding power conversion unit can output. When the
amplitude of the stator winding voltage command exceeds the25
34
upper limit value, windup of integral control in the control
device, unexpected magnetic flux interference between the
stator winding and the field winding in the rotary machine,
and the like are caused. As a result, current control for
the rotary machine might become unstable.5
[0057] FIG. 12 shows the stator winding current, the field
winding current, and the amplitude of the stator winding
voltage command, in a case where the torque command is
changed from the prescribed value to 0, in the control device
for the rotary machine in the present embodiment in which the10
stator winding current command correction unit is provided.
Here, the characteristics shown in FIG. 12 are
characteristics under the condition that only the field
winding current command selection unit of the stator winding
current command correction unit operates and the DC voltage15
correction unit does not operate. In FIG. 12, FIG. 12(a)
shows the torque command, FIG. 12(b) shows the stator winding
current, FIG. 12(c) shows the field winding current, and FIG.
12(d) shows the amplitude of the stator winding voltage
command.20
[0058] As shown in FIG. 12(c), the field winding current
command If* sharply changes following the waveform of the
torque command. At this time, separation between the field
winding current command If* or If** and the field winding
current If increases, and the stator winding voltage margin25
35
decreases. Therefore, the stator winding current commands
Id*, Iq* are generated on the basis of the field winding
current If. Therefore, as shown in FIG. 12(b), the stator
winding current commands Id*, Iq* mildly change without
sharply changing following the waveform of the torque5
command. The stator winding currents Id, Iq change following
the stator winding current commands Id*, Iq*. As a result, as
shown in FIG. 12(d), the amplitude of the stator winding
voltage command is less likely to exceed the upper limit
value of voltage that the stator winding power conversion10
unit can output.
[0059] FIG. 13 shows the stator winding current, the field
winding current, and the amplitude of the stator winding
voltage command, in a case where the torque command is
changed from the prescribed value to 0, in the control device15
for the rotary machine in the present embodiment in which the
stator winding current command correction unit is provided.
Here, the characteristics shown in FIG. 13 are
characteristics in a case where both of the field winding
current command selection unit and the DC voltage correction20
unit of the stator winding current command correction unit
operate. In FIG. 13, FIG. 13(a) shows the torque command,
FIG. 13(b) shows the stator winding current, FIG. 13(c) shows
the field winding current, and FIG. 13(d) shows the amplitude
of the stator winding voltage command.25
36
[0060] As shown in FIG. 13(c), the field winding current
command If* sharply changes following the waveform of the
torque command. At this time, separation between the field
winding current command If* or If** and the field winding
current If increases, and the stator winding voltage margin5
increases. Therefore, the stator winding current commands
Id*, Iq* are generated on the basis of the field winding
current If. Thus, as shown in FIG. 13(b), the stator winding
current commands Id*, Iq* mildly change without sharply
changing following the waveform of the torque command. In10
addition, since the DC voltage correction unit operates, the
waveform of Id* changes more mildly than in a case where the
DC voltage correction unit shown in FIG. 12 does not operate.
Thus, flux weakening control is more exerted than in the
operation shown in FIG. 12. As a result, change in the15
amplitude of the stator winding voltage command shown in FIG.
13(d) becomes even smaller than change in the amplitude of
the stator winding voltage command shown in FIG. 12(d), so
that the amplitude of the stator winding voltage command is
even less likely to exceed the upper limit value.20
[0061] Although the disclosure is described above in terms
of an exemplary embodiment, it should be understood that the
various features, aspects, and functionality described in the
embodiment are not limited in their applicability to the
particular embodiment with which they are described, but25
37
instead can be applied alone or in various combinations to
the embodiment of the disclosure.
It is therefore understood that numerous
modifications which have not been exemplified can be devised
without departing from the scope of the present disclosure.5
For example, at least one of the constituent components may
be modified, added, or eliminated.
DESCRIPTION OF THE REFERENCE CHARACTERS
[0062] 1 control device10
2 rotary machine
3 DC power supply
4 stator winding power conversion unit
5 field winding power conversion unit
6 stator winding current detection unit15
7 field winding current detection unit
8 processor
9 storage device
81 current command generation unit
82 stator winding voltage command unit20
83 stator winding switching command generation
unit
84 field winding voltage command unit
85 field winding switching command generation unit
810 field winding current command generation unit25
38
811 stator winding current command correction unit
812 stator winding current command generation unit
8110 field winding current response simulation
unit
8111 field winding current separation5
determination unit
8112 field winding current command selection unit
8113 DC voltage correction unit
8114 stator winding voltage margin calculation
unit10
39
We Claim :
[Claim 1] A control device (1) for a rotary machine (2)
including a rotor having a field winding and a stator having
a stator winding, the control device (1) comprising:5
a current command generation unit (81) which
generates a field winding current command for current flowing
through the field winding and a stator winding current
command for current flowing through the stator, on the basis
of an operation command inputted from outside;10
a field winding voltage command unit (84) which
generates a field winding voltage command for voltage to be
applied to the field winding, on the basis of the field
winding current command;
a stator winding voltage command unit (82)15
which generates a stator winding voltage command for voltage
to be applied to the stator winding, on the basis of the
stator winding current command;
a field winding power conversion unit (5) which
applies voltage to the field winding on the basis of the20
field winding voltage command; and
a stator winding power conversion unit (4)
which applies voltage to the stator winding on the basis of
the stator winding voltage command, wherein
the current command generation unit (81)25
40
includes
a field winding current command generation
unit (810) which generates the field winding current command
on the basis of the operation command and DC voltage inputted
from outside,5
a stator winding current command
correction unit (811) which generates a state variable for
correcting the stator winding current command, on the basis
of the current flowing through the field winding and the
field winding current command generated by the field winding10
current command generation unit (810), and
a stator winding current command
generation unit (812) which generates the stator winding
current command on the basis of the operation command and the
state variable generated by the stator winding current15
command correction unit (811).
[Claim 2] The control device (1) for the rotary machine (2)
according to claim 1, wherein
the state variable is at least one of20
information about the current flowing through the field
winding and information about the DC voltage.
[Claim 3] The control device (1) for the rotary machine (2)
according to claim 2, wherein25
41
the information about the current flowing
through the field winding is at least one of a value of the
current flowing through the field winding, the field winding
current command, and field winding response current
simulating response of the current flowing through the field5
winding, or information obtained by combining at least two of
these.
[Claim 4] The control device (1) for the rotary machine (2)
according to any one of claims 1 to 3, wherein10
the stator winding current command correction
unit (811) includes a field winding current command selection
unit (8112), and
the field winding current command selection
unit (8112) selects one of a value of the current flowing15
through the field winding, the field winding current command,
and field winding response current simulating response of the
current flowing through the field winding, or a value
obtained by combining two or more of these.
20
[Claim 5] The control device (1) for the rotary machine (2)
according to claim 4, wherein
the stator winding current command correction
unit (811) includes a field winding current separation
determination unit (8111), and25
42
the field winding current separation
determination unit (8111) calculates separation between the
value of the current flowing through the field winding and
the field winding current command or the field winding
response current simulating the response of the current of5
the field winding.
[Claim 6] The control device (1) for the rotary machine (2)
according to claim 5, wherein
the stator winding current command correction10
unit (811) includes a stator winding voltage margin
calculation unit (8114), and
the stator winding voltage margin calculation
unit (8114) calculates a stator winding voltage margin which
is a difference between an amplitude of the stator winding15
voltage command and an upper limit of a voltage amplitude
that the stator winding power conversion unit (4) can output,
on the basis of one or more of the value of the current
flowing through the field winding, the field winding current
command, the field winding response current simulating the20
response of the current of the field winding, the operation
command, and the DC voltage.
[Claim 7] The control device (1) for the rotary machine (2)
according to claim 6, wherein25
43
the field winding current command selection
unit (8112) selects one of the value of the current flowing
through the field winding, the field winding current command,
and the field winding response current simulating the
response of the current flowing through the field winding, or5
the value obtained by combining two or more of these, on the
basis of at least one of a magnitude of the separation of the
field winding current separation determination unit (8111)
and the stator winding voltage margin of the stator winding
voltage margin calculation unit (8114).10
[Claim 8] The control device (1) for the rotary machine (2)
according to claim 7, wherein
the stator winding current command correction
unit (811) includes a DC voltage correction unit (8113), and15
the DC voltage correction unit (8113) corrects
a value of the inputted DC voltage on the basis of at least
one of the magnitude of the separation determined by the
field winding current separation determination unit (8111)
and the stator winding voltage margin calculated by the20
stator winding voltage margin calculation unit (8114).
[Claim 9] The control device (1) for the rotary machine (2)
according to any one of claims 1 to 8, wherein
the stator winding current command correction25
44
unit (811) operates in a case where a rotational speed of the
rotary machine (2) is not smaller than 20% of a maximum
rotational speed.