JP2023163895A - Motor control method and motor control device - Google Patents

Abstract

To properly perform battery warm-up control in a motor control system in which battery charging/discharging power is determined according to a request output to a polyphase motor.SOLUTION: A motor control method includes generating a switching command signal Sp by pulse width modulation based on a carrier signal C and a phase voltage command value, and controlling power to be supplied from a battery 30 to a polyphase motor 10 by operating an inverter 40 on the basis of the switching command signal Sp. In a case where it is determined that the temperature of the battery 30 is low, at least two phases of the carrier signal C are set to different values, and the switching command signal Sp is generated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor control method and a motor control device.

Patent Document 1 describes a warm-up control device that controls charging and discharging of a battery mounted on a hybrid vehicle and raises the temperature using internal heat generation of the battery. In particular, in the battery warm-up control described in Patent Document 1, a charging pattern is adopted in which charging and discharging are alternately repeated in a pulsed manner to promote temperature rise of the battery.

Japanese Patent Application Publication No. 2005-332777

However, the battery warm-up control of Patent Document 1 is considered to be applied to a motor control system that determines battery charging/discharging power according to the required output (required driving force or required regenerative power) for a load (especially a multiphase motor). It has not been. In such a motor control system, the charging and discharging power of the battery is determined in consideration of the control over the output of the multiphase motor, so the warm-up control for changing the battery charging pattern described above may not be applied smoothly.

Therefore, an object of the present invention is to realize more suitable battery warm-up control in a motor control system that determines battery charging and discharging power according to the required output for a multiphase motor.

According to an aspect of the present invention, a switching command signal is generated by pulse width modulation based on a carrier signal and a phase voltage command value, an inverter is operated based on the switching command signal, and electric power is supplied from a battery to a polyphase motor. A motor control method is provided. In this motor control method, when it is determined that the battery is at a low temperature, a switching command signal is generated by setting the phases of at least two phases of the carrier signal to mutually different values.

According to the present invention, more suitable battery warm-up control can be realized in a motor control system that determines battery charging/discharging power according to the required output for a multiphase motor.

FIG. 1 is a block diagram showing the configuration of a motor control system in which a motor control method according to each embodiment is executed. FIG. 2 is a diagram illustrating one embodiment of frequency control. FIG. 3 is a diagram illustrating one embodiment of frequency control. FIG. 4 is a diagram illustrating one embodiment of frequency control. FIG. 5 is a diagram illustrating an embodiment of transfer characteristic improvement processing. FIG. 6 is a diagram illustrating an embodiment of transfer characteristic improvement processing. FIG. 7 is a diagram illustrating an embodiment of transfer characteristic improvement processing. FIG. 8 is a diagram illustrating one embodiment of modulation rate adjustment control.

Embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a block diagram showing the configuration of a motor control system 100 in which a motor control method according to the present embodiment is executed. As illustrated, the motor control system 100 mainly includes a motor 10, a motor control device 20, a battery 30, and an inverter 40.

The motor 10 is, for example, a permanent magnet (IPM) three-phase synchronous motor.

The motor control device 20 calculates a phase voltage command value corresponding to the AC voltage to be applied to the motor 10 based on a torque command value determined according to a desired required output, and calculates a phase voltage command value corresponding to the AC voltage to be applied to the motor 10 based on the phase voltage command value and the battery voltage. Then, the modulation rate M (U phase modulation rate M _u , V phase modulation rate M _v , W phase modulation rate M _w ) is calculated.

Further, the motor control device 20 generates a PWM (Pulse Width Modulation) signal _Sp from the modulation rate M and a carrier signal (carrier C) generated by a predetermined carrier generator. More specifically, the motor control device 20 compares the magnitude relationship between the modulation factors M _u , M _v , M _w of each phase and the carriers C _u , C _v , C _w of each phase, and calculates the comparison result. Based on this, an on/off pattern (duty pattern) of each switching element SW is determined, and this is defined as a PWM signal _Sp . In particular, the motor control device 20 turns on the upper arm and turns off the lower arm of the switching element SW u corresponding to the U phase when the U phase modulation factor M _u is larger than the U phase carrier C _u , and when it is smaller, the motor control device 20 turns on the upper arm and turns off the lower arm of the switching element SW _u corresponding to the U phase. Define a U-phase duty pattern that turns off the upper arm and turns on the lower arm. The V-phase duty pattern and the W-phase duty pattern are similarly set.

Further, the motor control device 20 of the present embodiment sets the control mode to either the basic control mode or the warm-up control mode according to the detected temperature value of the battery 30 (hereinafter also simply referred to as "battery temperature T _B "). Execute. Then, the motor control device 20 generates a PWM signal _Sp in the basic control mode using a basic carrier C1, which will be described later. On the other hand, in the warm-up control mode, the motor control device 20 generates the PWM signal _Sp using a warm-up carrier C2, which will be described later, which is different from the basic carrier C1. Note that details of the basic control mode and warm-up control mode will be described later.

Further, the motor control device 20 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input/output interface (I/O interface), and is capable of executing each of the above-described configurations. This is realized by a computer programmed as follows. It is also possible to configure the motor control device 20 with a plurality of computer hardware that executes each process in a distributed manner.

The inverter 40 includes a smoothing capacitor 42 connected in parallel to the battery 30 and each switching element SW described above. Further, the inverter 40 includes a drive circuit (not shown) for driving each switching element SW _u according to a switching pattern defined by a PWM signal generated by the motor control device 20.

The battery 30 is comprised of a vehicle-mounted secondary battery such as a lithium ion secondary battery.

Details of the processing by the motor control device 20 will be described below. The motor control device 20 executes the basic control mode when the battery temperature T _B is equal to or higher than a predetermined threshold temperature, and executes the warm-up control mode when the battery temperature T _B is less than the threshold temperature. Note that the threshold temperature is appropriately determined from the viewpoint of determining whether or not the battery temperature _TB has fallen to a degree that requires warming up.

The basic control mode is a control mode in which a carrier C is set to determine a duty pattern according to a phase voltage command value based on a torque command value of the motor 10, taking energy efficiency (electricity cost) into consideration. In particular, in the basic control mode, the PWM signal _Sp is generated using the basic carrier C1 in which the phases of each phase are set to be the same.

On the other hand, the warm-up control mode is a control mode that sets a carrier C that defines a duty pattern that promotes temperature rise of the battery 30 while satisfying the torque command value of the motor 10 in a low-temperature environment or the like. In particular, in the warm-up control mode, the PWM signal _Sp is generated using a warm-up carrier C2 different from the basic carrier C1.

Here, in the warm-up carrier C2, at least two of the phases of each phase are set to different values. In particular, in this embodiment, as shown in FIG. 1, the phase of the U-phase carrier C2 _u is determined to be shifted by 180 degrees with respect to each phase of the V-phase carrier C2 _v and the W-phase carrier C2 _w .

As a result, in the warm-up control mode, the switching elements SW _u , SW _v , SW _w of each phase are driven using the warm-up carrier C2 having a phase difference between the phases. Therefore, a larger current amplitude (hereinafter also referred to as "ripple current I") is applied to the bus bar 44 that electrically connects each switching element SW _u , SW _v , SW _w and the smoothing capacitor 42 compared to the basic control mode. can be caused. When this ripple current I is transmitted to the battery 30 via the electrical connection 50 between the inverter 40 and the battery 30, a ripple current I' having the same frequency component as the carrier frequency f is induced in the battery 30. Ru. As a result, due to the generation of the ripple current I' in the current flowing through the battery 30, the current (heat amount) flowing through the internal resistance R increases, and temperature rise is promoted.

For simplicity, FIG. 1 shows a mode in which the modulation factors M _u , M _v , M _w of each phase are fixed to zero (coinciding with the center of displacement of the carrier), assuming that the motor 10 is stopped. ing. On the other hand, when the motor is driven, the modulation factors M _u , M _v , M _w of each phase change in synchronization with the driving situation (phase voltage command value, motor induced voltage, etc.), but the above control logic also applies in that case. Similarly applicable.

The effects of the motor control method of the present embodiment described above will be summarized.

In the motor control method of this embodiment, a switching command signal (PWM signal S _p ) is generated by pulse width modulation based on a carrier signal (carrier C) and a phase voltage command value, and the inverter 40 is activated based on the PWM signal S _p . It is operated to control the power supplied from the battery 30 to the multiphase motor (motor 10). In particular, in this motor control method, when it is determined that the battery 30 is at a low temperature, the warm-up carrier signal (warm-up carrier C2) in which the phases of at least two phases of the carrier C are set to mutually different values is used. Based on this, a PWM signal _Sp is generated.

As a result, the phase of the carrier C is adjusted based on the motor control system 100 that generates the PWM signal _Sp based on the phase voltage command value corresponding to the required output of the motor 10 and supplies power to the motor 10 from the battery 30. By this simple method, the self-heating of the battery 30 can be increased to promote warm-up. As a result, in a scene where warm-up is required, such as in a low-temperature environment, it is possible to increase the temperature raising effect of the battery 30 and improve the charging/discharging characteristics while maintaining control over the motor 10.

In particular, in this embodiment, the phase voltage command value corresponding to the required output for the motor 10 is maintained, and the phase of the carrier C is adjusted to increase the current flowing through the battery 30 to promote temperature rise. Therefore, the temperature of the battery 30 can be raised while suppressing the influence on the drive control of the motor 10.

More specifically, in this embodiment, when the battery temperature T _B is equal to or higher than a predetermined threshold temperature, the PWM signal S _P Executes basic control mode that generates . On the other hand, when the battery temperature T _B is less than the predetermined threshold temperature, a PWM signal S _p is generated from a warm-up carrier signal (warm-up carrier C2) in which the phases of at least two phases are set to mutually different values. Execute warm-up control mode.

Thereby, the carrier C can be appropriately selected between the basic carrier C1 and the warm-up carrier C2 depending on whether or not the battery 30 needs to be warmed up. Therefore, in scenes that do not require warm-up of the battery 30, the basic carrier C1, which is more suitable for drive control of the motor 10, is used, while in scenes that require warm-up, the warm-up carrier C2, which is suitable for raising the temperature of the battery 30, is used. A concrete control logic that enables this is realized.

Furthermore, in this embodiment, a motor control device 20 suitable for executing the above motor control method is provided.

In the present embodiment, an example has been described in which the phase of the U-phase carrier C2 _u in the warm-up carrier C2 is shifted by 180 degrees with respect to each phase of the V-phase carrier C2 _v and the W-phase carrier C2 _w . However, the specific aspect regarding the phase setting of each phase carrier C2 _u , C2 _v , C2 _w of the warm-up carrier C2 is not limited to this, and the influence on the drive control of the motor 10 and the battery 30 It can be adjusted as appropriate, taking into consideration the balance of the magnitude of the temperature increase effect, etc.

[Second embodiment]
The second embodiment will be described below. Note that in each of the subsequent embodiments, descriptions of the same configurations as those described in the previous embodiments will be omitted as appropriate.

The motor control device 20 of this embodiment performs control (hereinafter referred to as "frequency (also referred to as "control").

Specifically, the motor control device 20 sets the carrier frequency f (that is, the frequency of the basic carrier C1) in the basic control mode to the basic frequency f1. Note that the fundamental frequency f1 is a frequency that is appropriately determined in consideration of reducing switching loss during driving of the motor 10.

On the other hand, the motor control device 20 sets the carrier frequency f (that is, the frequency of the warm-up carrier C2) during the warm-up control mode to a warm-up frequency f2 different from the basic frequency f1. Note that the warm-up frequency f2 is appropriately determined from the viewpoint of further increasing the temperature increase effect of the battery 30 during warm-up.

In particular, in this embodiment, the warm _- up frequency is Define f2. The details will be explained below.

FIG. 2(A) is a diagram showing a main part of the circuit configuration between the battery 30 and the inverter 40 in this embodiment.

As already explained, the ripple current I' generated in the battery 30 is induced by the ripple current I generated in the bus bar 44 of the inverter 40. Therefore, the transfer characteristic T _I'/I (f) from the ripple current I to the ripple current I' depends on the configuration of the electrical connection 50 between the bus bar 44 and the battery 30.

More specifically, assuming the circuit configuration shown in FIG _. becomes.

FIG. 2(B) is a diagram showing the transfer characteristic T _I'/I (f) according to the circuit configuration shown in FIG. 2(A).

As illustrated, the transfer characteristic T _I'/I (f) in this embodiment indicates a first-order low-pass filter characteristic based on the ripple current I of the bus bar 44. Therefore, assuming the above circuit configuration, the lower the carrier frequency f, the better the transfer characteristic T _I'/I (f). That is, the lower the carrier frequency f is, the larger the ripple current I' is induced for the same ripple current I.

Therefore, in this embodiment, the warm-up frequency f2 is set lower than the basic frequency f1 (first frequency control). Thereby, the ripple current I' during the warm-up control mode can be made larger to increase the amount of self-heating of the battery 30.

According to the motor control method of this embodiment described above, in the basic control mode, the carrier frequency f of the basic carrier C1 is set to the predetermined basic frequency f1. On the other hand, in the warm-up control mode, the carrier frequency f of the warm-up carrier signal (warm-up carrier C2) is set to a warm-up frequency f2 different from the basic frequency f1.

Thereby, the carrier frequency f can be switched to a preferable value in each mode during non-warm-up (during basic control mode) and warm-up (during warm-up control mode). More specifically, there is a specific method for generating a PWM signal S _p suitable for driving the motor 10 when not warmed up, and at the same time generating a PWM signal S _p that can further promote self-heating of the battery 30 when warmed up. Control logic is implemented.

In particular, in this embodiment, the warm-up frequency f2 is set lower than the basic frequency f1.

As a result, when a specific circuit configuration (FIG. 2A) between the battery 30 and the inverter 40 is assumed, a specific control logic for increasing the temperature increase effect of the battery 30 during warm-up is realized.

[Third embodiment]
In this embodiment, an example will be described in which the motor control device 20 executes the second frequency control. More specifically, in the second frequency control, the warm-up frequency f2 is set so that the effective value of the current flowing through the battery 30 is larger than the effective value of the phase current of the motor 10. Note that the effective value of the current flowing through the battery 30 and the effective value of the phase current of the motor 10 can be respectively calculated from detected values detected by a current sensor (not shown).

Thereby, the ripple current I' in the warm-up control mode can be further increased, and the effect of raising the temperature of the battery 30 can be further enhanced.

[Fourth embodiment]
In this embodiment, an example will be described in which the motor control device 20 executes the third frequency control.
In particular, in this embodiment, in the same circuit configuration (FIG. 3(A)) as the circuit configuration (FIG. 2(A)) described in the second embodiment, a scene in which the internal resistance R of the battery 30 is below a certain value is described. The warm-up frequency f2 is determined in consideration of the transfer characteristic T _I'/I (f) in (more specifically, a scene where the battery temperature T _B is particularly low).

FIG. 3(B) is a diagram showing the transfer characteristic T _I'/I (f) of a specific scene based on the circuit configuration of FIG. 3(A).

During the warm-up control mode, especially in a scene where the internal resistance R of the battery 30 is low, a resonance phenomenon occurs between the capacitance of the smoothing capacitor 42 and the parasitic inductance L of the electrical connection 50. Therefore, as shown in FIG. 3(B), the transfer characteristic T _I'/I (f) shows a profile having a peak at a specific frequency (resonant frequency). Therefore, in this scene, the effect of increasing the temperature of the battery 30 can be further improved by setting the warm-up frequency f2 to be the same as the resonance frequency or a frequency in the vicinity thereof.

Note that the resonant frequency is calculated in advance from the known capacitance and parasitic inductance L of the smoothing capacitor 42, stored, and referenced by the motor control device 20 as appropriate.

As described above, in this embodiment, the inverter 40 includes the smoothing capacitor 42 connected in parallel to the battery 30. In the warm-up control mode, the warm-up frequency f2 is approximately the same as the resonant frequency in the resonant system including the smoothing capacitor 42 and the parasitic inductance L generated by the electrical connection 50 between the battery 30 and the smoothing capacitor 42. stipulated in

As a result, self-heating of the battery 30 is suitably promoted in consideration of the transfer characteristic T _I'/I (f) shown in a specific scene (such as in a low-temperature environment) where the internal resistance of the battery 30 is below a certain value. The warm-up frequency f2 to be used can be determined. As a result, the effect of increasing the temperature of the battery 30 during the warm-up control mode can be further improved.

[Fifth embodiment]
In this embodiment, a fourth frequency control aspect will be described.

FIG. 4(A) is a diagram showing a main part of the circuit configuration between the battery 30 and the inverter 40 in this embodiment. As shown in the figure, in the circuit configuration of the present embodiment, a resonance characteristic adjustment capacitor 60 is provided between the smoothing capacitor 42 of the inverter 40 and the battery 30 and connected in parallel thereto. That is, the circuit configuration of FIG. 4(A) differs from the circuit configuration of FIG. 3(A) in that a capacitor 60 for adjusting resonance characteristics is provided.

By providing the resonance characteristic adjustment capacitor 60 in this way, the characteristics of the electrical connection 50 from the inverter 40 to the battery 30 change. Therefore, the profile (peak frequency, peak position, and/or peak width) of the transfer characteristic T _I'/I (f) is changed by adjusting the characteristics of the resonance system for the circuit configuration shown in FIG. 3(A). be able to.

FIG. 4(B) is a diagram showing the transfer characteristic T _I'/I (f) based on the circuit configuration of FIG. 4(A). As shown in the figure, the transfer characteristic T _I'/I (f) of this embodiment has a narrower peak width and a higher peak height than the transfer characteristic T _I'/I (f) shown in FIG. 3(B). It's getting bigger. Therefore, by setting the warm-up frequency f2 to be the same as the resonant frequency, the value of the ripple current I' per ripple current I becomes larger, and the effect of increasing the temperature of the battery 30 can be further improved.

As described above, in this embodiment, the resonance characteristic adjustment capacitor 60 connected in parallel to the battery 30 is provided in the electrical connection 50 between the battery 30 and the smoothing capacitor 42 .

Thereby, the profile of the transfer characteristic T _I'/I (f) can be adjusted by changing the characteristics of the resonance system in the circuit configuration including the inverter 40 and the battery 30. In particular, in this embodiment, the profile of the transfer characteristic T _I'/I (f) is adjusted so that it takes a higher value at the peak frequency (ie, the resonant frequency). Therefore, by making the warm-up frequency f2 match the resonant frequency, the effect of increasing the temperature of the battery 30 can be further improved.

In particular, with the control of this embodiment, even in situations where the internal resistance of the battery 30 is low, such as in an extremely low temperature environment, it is possible to appropriately promote self-heating of the battery 30 and achieve a sufficient temperature increase effect. .

In addition, in this embodiment, an example will be described in which the resonance characteristic (transfer characteristic profile) is changed by connecting the resonance characteristic adjustment capacitor 60 in parallel to the battery 30 based on the circuit configuration shown in FIG. 4(A). did. On the other hand, the specific configuration for changing the resonance characteristics is not limited to this, and can be changed as appropriate depending on the underlying circuit configuration.

[Sixth embodiment]
In this embodiment, a fifth frequency control aspect will be described.

Specifically, in this embodiment, a process (frequency search process) of measuring the current of the battery 30 according to a change in the carrier frequency f during the warm-up control mode and determining the warm-up frequency f2 according to the measurement result. Execute.

More specifically, in the frequency search process, the carrier frequency f is swept in a predetermined range using a predetermined timing such as the start of the warm-up control mode as a base point. Then, a frequency at which the current of the battery 30 becomes maximum is specified within the swept predetermined range, and the frequency is set as the warm-up frequency f2. Furthermore, frequency search processing is executed at predetermined time intervals to update the warm-up frequency f2 as appropriate.

Thereby, the warm-up frequency f2 that can induce a high ripple current I' can be appropriately determined depending on the actual current behavior of the battery 30 during the warm-up control mode.

According to the motor control method of the present embodiment described above, in the warm-up control mode, a frequency search process is executed to search and set the warm-up frequency f2 at predetermined intervals. In particular, in the frequency search process, the current of the battery 30 is observed while changing the carrier frequency f in a predetermined search range, and the frequency at which the current of the battery 30 is highest in the search range is set as the warm-up frequency f2.

As a result, even if the frequency at which a high ripple current I' can be achieved changes due to changes in the battery temperature T _B during the warm-up control mode, the ripple current I' can be maximized as appropriate. A frequency can be specified and set as the warm-up frequency f2. Therefore, the effect of increasing the temperature of the battery 30 in the warm-up control mode can be further improved.

As explained in the fourth embodiment, when the transfer characteristic T _I'/I (f) takes a profile having a peak at the resonance frequency due to the resonance system derived from the circuit configuration, the frequency including the peak is determined in advance. A configuration may be adopted in which a range is specified and frequency search processing is executed. Thereby, after observing the behavior of the actual current of the battery 30, it is possible to more accurately specify the frequency at which the transfer characteristic T _I'/I (f) takes a peak. In particular, as explained in the fifth embodiment, when the peak width of the transfer characteristic T _I'/I (f) is relatively narrow (relatively sharp), frequency search processing is performed to determine the transfer characteristic T By more reliably identifying the frequency at which _I'/I (f) peaks, it is possible to reduce the ripple current I' significantly (as the battery 30 increases (deterioration of thermal effect) can be more reliably prevented.

[Seventh embodiment]
In this embodiment, the motor control device 20 executes control to further improve the transfer characteristic T _I'/I (f) from the ripple current I to the ripple current I' (hereinafter referred to as "transfer characteristic improvement process"). Explain.

FIG. 5A is a diagram showing a circuit configuration for determining the transfer characteristic T _I'/I (f) from the ripple current I to the ripple current I' in this embodiment. As shown in the figure, in the circuit configuration of this embodiment, the smoothing capacitor 42 of the inverter 40 is composed of two capacitor elements 42a and 42b connected in parallel to the battery 30. Further, of these two, a switch 70 is provided on the capacitor element 42a provided on the bus bar 44 side. Then, by controlling the on/off operation of the switch 70, the motor control device 20 changes the electrical connection between the capacitor element 42a and the battery 30 into a connected state (on state) and a disconnected state (off state). can be switched between.

In particular, in this embodiment, the motor control device 20 turns on the switch 70 when the rate of temperature increase of the battery 30 is equal to or higher than a predetermined threshold rate. On the other hand, if the temperature increase rate of the battery 30 is less than the threshold value, the switch 70 is turned off (first transfer characteristic improvement process). Note that the temperature increase rate of the battery 30 can be determined based on, for example, changes in temperature sensor values over time.

FIG. 5(B) is a diagram showing the transfer characteristic T _I'/I (f) depending on the on/off state of the switch 70.

As shown in the figure, when the switch 70 is turned off and the capacitor element 42a is electrically disconnected from the battery 30, the transfer characteristic T _I'/I (f ) value improves. Therefore, if the temperature increase rate of the battery 30 does not reach the desired rate during warm-up, the transfer characteristic T _I'/I (f) is improved by turning off the switch 70, and the temperature increase rate of the battery 30 is increased. It can further promote warmth.

According to the motor control method of the present embodiment described above, in the warm-up control mode, the electrical connection between the inverter 40 and the battery 30 is controlled based on the temperature parameter (heating rate) that indicates the temperature of the battery 30. The switch 70 is operated to increase the ripple current (ie, ripple current I') generated in the battery 30 per current flowing through the electrical wiring of the inverter 40 (ie, per ripple current I).

As a result, the transfer characteristic improvement process is executed as appropriate depending on the temperature increase state of the battery 30 during the warm-up control mode, so that the effect of increasing the temperature of the battery 30 can be further improved.

In particular, the smoothing capacitor 42 of the inverter 40 of this embodiment is configured by a plurality of (two in this embodiment) capacitor elements 42a and 42b connected in parallel to the battery 30. In the warm-up control mode, when the rate of temperature increase of the battery 30 is less than a predetermined threshold rate, the switch 70 is operated to select one of the capacitor elements 42a and 42b (in this embodiment, the capacitor element 42a). is electrically disconnected from the battery 30.

Thereby, it is possible to appropriately detect a scene in which the intended heating effect of the battery 30 is not obtained during warm-up, and to execute processing for improving the heating effect.

[Eighth embodiment]
In this embodiment, an aspect of the second transfer characteristic improvement process will be described.

FIG. 6 is a diagram showing a main part of the circuit configuration between the battery 30 and the inverter 40 in this embodiment.

As shown in the figure, battery 30 includes a plurality of (two in the figure) unit power storage units 30a and 30b that are connected in parallel to inverter 40. Further, each unit power storage unit 30a, 30b is provided with a switch 70a, 70b for switching the electrical connection with the inverter 40, respectively.

In the warm-up control mode, motor control device 20 individually turns on or off each switch 70a, 70b depending on the magnitude of temperature variation in each unit power storage section 30a, 30b.

More specifically, if the temperature variation is above a certain value, one of the unit power storage units 30a, 30b that has a relatively higher temperature is identified. For example, when unit power storage unit 30a has a relatively high temperature, switch 70a is turned off and switch 70b is turned on. As a result, unit power storage section 30a, which has a relatively high temperature, is electrically disconnected from inverter 40, and only unit power storage section 30b, which has a relatively low temperature, is electrically connected to inverter 40. Note that even when unit power storage section 30b has a relatively high temperature, the on/off of each switch 70a, 70b is controlled using the same logic.

As a result, in a scene where the temperature variation between each unit power storage unit 30a, 30b is large, the gain of the transfer characteristic T _I'/I (f) (ripple current I' per ripple current I) can be adjusted to a relatively low temperature. By concentrating on unit power storage section 30b, it is possible to give priority to raising the temperature of unit power storage section 30b.

As explained above, in this embodiment, the battery 30 includes a plurality of unit power storage units 30a and 30b. In the warm-up control mode, when the temperature variation of each unit power storage unit 30a, 30b is equal to or higher than a certain value, unit power storage unit 30a, which has a relatively high temperature among each unit power storage unit 30a, 30b, is switched to an inverter. electrically disconnected from 40.

Thereby, even if the temperature variation between unit power storage units 30a and 30b increases during warm-up, it is possible to preferentially raise the temperature of unit power storage unit 30b, which is relatively low temperature. As a result, the temperature of the plurality of unit power storage units 30a, 30b can be raised uniformly, and the time (warm-up time) required to raise the temperature of the entire battery 30 to a desired temperature can be shortened.

Note that the circuit configuration shown in this embodiment is an example, and any circuit configuration may be adopted as long as it is possible to turn on/off the electrical connection between the plurality of power storage units and the inverter 40 according to temperature variations. be able to.

[Ninth embodiment]
In this embodiment, an aspect of the third transfer characteristic improvement process will be described.

In particular, in this embodiment as well, the battery 30 includes a plurality of (two in the figure) unit power storage units 30a and 30b, similar to the ninth embodiment. Then, depending on the temperature of battery 30, the electrical connection state of each unit power storage unit 30a, 30b to inverter 40 is individually switched.

FIG. 7 is a diagram showing a main part of the circuit configuration between the battery 30 and the inverter 40 in this embodiment.

As shown in the figure, with the circuit configuration of this embodiment, each unit power storage section 30a, 30b can be electrically connected to the inverter 40 by individually operating each switch 70c, 70d, 70e according to the temperature of the battery 30. The state (parallel, series, or disconnected) can be switched.

Specifically, in the basic control mode, the motor control device 20 sets the switch 70c to on, the switch 70d to off, and the switch 70e to off. On the other hand, in the warm-up control mode, the switch 70c is set to OFF, the switch 70d is set to ON, and the switch 70e is set to ON.

As a result, each unit power storage section 30a, 30b is connected in series to the inverter 40 when not warmed up (when the motor is normally driven), and a high battery output can be ensured. On the other hand, during warm-up, each unit power storage unit 30a, 30b is connected in series to inverter 40. Therefore, the combined internal resistance value of the battery 30 decreases, the transfer characteristic T _I'/I (f) improves, and the temperature rise of the battery 30 is further promoted.

As explained above, in this embodiment, the battery 30 includes a plurality of unit power storage units 30a and 30b. In the basic control mode, each unit power storage unit 30a, 30b is directly connected to the inverter 40. On the other hand, in the warm-up control mode, each unit power storage section 30a, 30b is connected in parallel to the inverter 40.

As a result, a control logic that secures a high battery output in the basic control mode and improves the transfer characteristic T _I'/I (f) in the warm-up control mode to further enhance the temperature raising effect of the battery 30 is realized. Ru.

Note that the circuit configuration shown in this embodiment is an example, and if it is possible to switch the connection between the multiple unit power storage units and the inverter 40 between direct connection and parallel connection in the basic control mode and warm-up control mode. For example, any circuit configuration can be adopted.

[Tenth embodiment]
In the present embodiment, the motor control device 20 executes modulation rate adjustment control that adjusts the modulation rate M in the warm-up control mode from the viewpoint of promoting temperature rise of the battery 30.

Specifically, in the modulation rate adjustment control of this embodiment, the modulation rate M is determined so that the direction of the composite magnetomotive force generated within the motor 10 coincides with the rotor magnetic pole position.

FIG. 8(A) shows the modulation rate M adjusted by the modulation rate adjustment control, each phase current of the motor 10 according to the modulation rate M, and the average value of each phase current (especially the average value per carrier cycle). FIG. Moreover, FIG. 8(B) is a phasor diagram showing the relationship among each phase current vector, the direction of the composite magnetomotive force, and the rotor magnetic pole position when modulation rate adjustment control is executed.

As shown in the figure, in modulation rate adjustment control, the direction of the composite vector of each phase current vector (that is, the direction of the composite magnetomotive force created by each phase current vector) is determined on the phasor display based on the three-phase AC coordinate system. The modulation rate M is adjusted so as to match the rotor magnetic pole position (that is, the d-axis direction) detected in advance by a predetermined sensor or the like.

According to the motor control method of the present embodiment described above, in the warm-up control mode, the modulation factor M based on the phase voltage command value is adjusted so that the direction of the composite magnetomotive force generated in the motor 10 coincides with the rotor magnetic pole position. stipulated in In particular, the direction of the combined magnetomotive force is determined by the average value per carrier period in each phase current.

As a result, as described above, during the warm-up control mode, the influence on the drive control of the motor 10 (unintended motor _torque occurrences, etc.) can be more reliably prevented.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. do not have. Furthermore, the above embodiments can be arbitrarily combined to the extent possible.

10 motor 20 motor control device 30 battery 40 inverter 42 smoothing capacitor 50 electrical connection 60 resonance characteristic adjustment capacitor 70 switch 100 motor control system

Claims (14)

A motor control method that generates a switching command signal by pulse width modulation based on a carrier signal and a phase voltage command value, and controls power supplied from a battery to a multiphase motor by operating an inverter based on the switching command signal. ,
If it is determined that the battery is at a low temperature, generating the switching command signal by setting the phases of at least two phases of the carrier signal to mutually different values;
Motor control method. The motor control method according to claim 1, comprising:
When the battery temperature is equal to or higher than a predetermined threshold temperature, executing a basic control mode in which the switching command signal is generated from a basic carrier signal in which the phases of each phase are set to be the same;
When the battery temperature is less than the threshold temperature, executing a warm-up control mode in which the switching command signal is generated from a warm-up carrier signal in which the phases of at least two phases are set to mutually different values;
Motor control method. The motor control method according to claim 2,
In the basic control mode, the carrier frequency of the basic carrier signal is set to a predetermined basic frequency,
In the warm-up control mode, the carrier frequency of the warm-up carrier signal is set to a warm-up frequency different from the basic frequency;
Motor control method. 4. The motor control method according to claim 3,
setting the warm-up frequency lower than the basic frequency;
Motor control method. 4. The motor control method according to claim 3,
setting the warm-up frequency so that the effective value of the current flowing through the battery is larger than the effective value of the phase current of the multiphase motor;
Motor control method. 4. The motor control method according to claim 3,
The inverter includes a smoothing capacitor connected in parallel to the battery,
In the warm-up control mode,
Setting the warm-up frequency to be approximately the same as a resonant frequency in a resonant system including a capacitance of the smoothing capacitor and a parasitic inductance caused by an electrical connection between the battery and the smoothing capacitor.
Motor control method. 7. The motor control method according to claim 6,
providing a resonance characteristic adjustment capacitor connected in parallel to the battery in the electrical connection between the battery and the smoothing capacitor;
Motor control method. 4. The motor control method according to claim 3,
In the warm-up control mode, a frequency search process is executed to search and set the warm-up frequency at predetermined time intervals;
In the frequency search process,
observing the current of the battery by changing the carrier frequency in a predetermined search range;
setting a frequency at which the current of the battery is highest in the search range as the warm-up frequency;
Motor control method. The motor control method according to claim 2,
In the warm-up control mode,
operating a switch that changes an electrical connection state between the inverter and the battery to increase ripple current generated in the battery per current flowing through the electrical connection of the inverter compared to when the basic control mode is executed;
Motor control method. The motor control method according to claim 9,
The smoothing capacitor of the inverter is composed of a plurality of capacitor elements,
In the warm-up control mode,
If the temperature increase rate of the battery is less than a predetermined threshold rate, electrically disconnecting any of the capacitor elements from the battery;
Motor control method. The motor control method according to claim 9,
The battery includes a plurality of unit power storage units,
In the warm-up control mode,
When the temperature variation of each of the unit power storage units is equal to or higher than a certain value, electrically disconnecting the unit power storage unit having a relatively high temperature among the unit power storage units from the inverter;
Motor control method. The motor control method according to claim 9,
The battery includes a plurality of unit power storage units,
In the basic control mode, each unit power storage unit is directly connected to the inverter,
In the warm-up control mode, each of the unit power storage units is connected in parallel to the inverter;
Motor control method. The motor control method according to claim 2,
In the warm-up control mode,
determining a modulation rate based on the phase voltage command value such that the direction of the composite magnetomotive force generated in the multiphase motor coincides with the rotor magnetic pole position;
The direction of the composite magnetomotive force is determined by the average value per carrier period in each phase current of the multiphase motor.
Motor control method. A motor control device that generates a switching command signal by pulse width modulation based on a carrier signal and a phase voltage command value, operates an inverter based on the switching command signal, and controls power supplied from a battery to a multiphase motor. ,
If it is determined that the battery is at a low temperature, generating the switching command signal by setting the phases of at least two phases of the carrier signal to mutually different values;
Motor control device.