JP7415579B2 - Vehicle drive control system - Google Patents

Description

The present disclosure relates to a vehicle drive control system.

Japanese Unexamined Patent Publication No. 2015-223070 (Patent Document 1) discloses a vehicle drive control system including a DC/DC converter that is connected to a DC power supply and boosts the DC power supply voltage. In this drive control system, in order to reduce loss in the DC/DC converter, intermittent step-up control is performed to stop the DC/DC converter when a predetermined stop condition is met during step-up operation of the DC/DC converter. (See Patent Document 1).

Japanese Patent Application Publication No. 2015-223070 Japanese Patent Application Publication No. 2019-146281

Intermittent step-up control, which operates the converter intermittently, is useful in that it can reduce converter loss. The fluctuation of the voltage VH (sometimes referred to as "voltage VH") becomes large. Therefore, pulse width modulation control (hereinafter referred to as "PWM (Pulse Width Modulation) control") is based on the modulation degree (sometimes referred to as "voltage utilization rate"), which is the ratio of the inverter output voltage (motor voltage) to the voltage VH. When controlling an inverter by switching between PWM control and square wave control, the degree of modulation changes in accordance with fluctuations in voltage VH due to intermittent boost control, resulting in frequent switching between PWM control and square wave control. As a result, although the details will be described later, the d-axis voltage command value gradually increases, and as a result, the followability of the actual torque to the torque command value may deteriorate, resulting in a torque deviation. In addition, if the torque followability decreases, various deviations that would not otherwise occur may occur, and there is a concern that if the system is monitored based on such deviations, it may be falsely detected as an abnormality. Ru.

The present disclosure has been made in order to solve such problems, and the purpose of the present disclosure is to reduce loss in the converter through intermittent boost control of the converter, while suppressing deterioration in torque followability caused by intermittent boost control. It is an object of the present invention to provide a drive control system for a vehicle that is possible.

A vehicle drive control system according to the present disclosure includes a power storage device, an inverter, a converter, and a control device. The inverter drives the electric motor for driving. The converter is provided between the power storage device and the inverter, and boosts the voltage of DC power supplied from the power storage device to the inverter to a voltage higher than the voltage of the power storage device. The control device controls the inverter and converter. The control device controls the inverter by switching between PWM control and rectangular wave control depending on the degree of modulation. Further, the control device controls the converter in either a continuous control mode in which the converter is operated continuously, or an intermittent control mode (boost intermittent control) in which the converter is intermittently operated. The control gain of the rectangular wave control when the converter operates in the intermittent control mode is greater than the control gain of the rectangular wave control when the converter operates in the continuous control mode.

As mentioned above, in the intermittent control mode, fluctuations in the voltage VH increase, so the d-axis voltage command value gradually increases due to frequent switching between PWM control and square wave control, and as a result, the torque followability improves. may result in a decrease in The inventors attempted a detailed analysis of this phenomenon and obtained the following knowledge.

During the intermittent control mode, when the voltage VH decreases with respect to the command value due to stopping of the converter, the actual q-axis voltage decreases with respect to the q-axis voltage command value in PWM control. Then, the d-axis current increases to the negative side, and the d-axis voltage command value increases in accordance with the d-axis current deviation. As a result, the degree of modulation increases and the control of the inverter switches from PWM control to square wave control. In the rectangular wave control, the voltage phase is manipulated, and the increased d-axis voltage command value decreases. On the other hand, regarding the converter, when voltage VH drops to a predetermined level, the converter operates and voltage VH increases. When voltage VH increases, the degree of modulation decreases, and rectangular wave control is switched to pulse width modulation control.

Incidentally, a smoothing capacitor is usually provided on the input side (DC side) of an inverter, and the capacitance of the capacitor may be reduced in order to downsize the device. In this case, since the voltage VH tends to fluctuate in accordance with load fluctuations, the control gain of the rectangular wave control may be set lower in consideration of robustness due to disturbances such as sensor errors.

Therefore, before the d-axis voltage command value that has increased during PWM control returns (decreases) to an appropriate level due to the square wave control, the square wave control may be switched to the PWM control due to an increase in the voltage VH due to converter operation. . Then, PWM control is performed from a state where the d-axis voltage command value is larger than that at the time of the previous switching to PWM control, and the d-axis voltage command value further increases. In this way, when PWM control and square wave control are frequently switched, the d-axis voltage command value gradually increases.

Therefore, in the drive control system of the present disclosure, regarding the control gain of the rectangular wave control, the control gain when the converter operates in the intermittent control mode is made larger than the control gain when the converter operates in the continuous control mode. Thereby, in the intermittent control mode, it becomes possible to return the d-axis voltage command value increased in PWM control to an appropriate level in rectangular wave control. Therefore, according to this drive control system, it is possible to reduce the loss of the converter through the intermittent boost control of the converter, while suppressing a decrease in torque followability caused by the intermittent boost control.

According to the vehicle drive control system of the present disclosure, it is possible to reduce the loss of the converter through intermittent boost control of the converter, while suppressing a decrease in torque followability caused by the intermittent boost control.

1 is an overall configuration diagram of a vehicle equipped with a drive control system according to a first embodiment of the present disclosure. FIG. 2 is a block diagram functionally showing the configuration of the control device shown in FIG. 1. FIG. FIG. 3 is a block diagram showing a configuration example of a PWM control section shown in FIG. 2. FIG. FIG. 3 is a block diagram showing a configuration example of a rectangular wave control section shown in FIG. 2. FIG. 5 is a timing chart showing changes in various parameters during an intermittent control mode. 5 is a flowchart illustrating an example of a processing procedure of rectangular wave control executed by the control device according to the first embodiment. 7 is a flowchart illustrating an example of a PWM control processing procedure executed by the control device according to the second embodiment.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. Although a plurality of embodiments will be described below, it has been planned from the beginning of the application to appropriately combine the configurations described in each embodiment. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

[Embodiment 1]
<Configuration of drive control system>
FIG. 1 is an overall configuration diagram of a vehicle equipped with a drive control system according to Embodiment 1 of the present disclosure. Referring to FIG. 1, vehicle 100 includes DC voltage generator 10#, capacitor C0, inverter 14, electric motor M1, and control device 30.

DC voltage generation unit 10# includes power storage device B, system relays SR1 and SR2, capacitor C1, and converter 12. Power storage device B is a power storage element configured to be rechargeable. Power storage device B is configured to include, for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery, and a power storage element such as an electric double layer capacitor. Note that a lithium ion secondary battery is a secondary battery that uses lithium as a charge carrier, and may include not only a general lithium ion secondary battery whose electrolyte is a liquid, but also a so-called all-solid-state battery that uses a solid electrolyte.

Voltage Vb of power storage device B and current Ib input/output to power storage device B are detected by voltage sensor 10 and current sensor 11, respectively. System relay SR1 is connected between the positive terminal of power storage device B and power line 6, and system relay SR2 is connected between the negative terminal of power storage device B and power line 5. System relays SR1 and SR2 are turned on/off by a signal SE from control device 30.

Converter 12 includes a reactor L1, switching elements Q1, Q2, and diodes D1, D2. Switching elements Q1 and Q2 are connected in series between power line 7 and power line 5. On/off of switching elements Q1 and Q2 is controlled by switching control signals S1 and S2 from control device 30. Diodes D1 and D2 are connected antiparallel to switching elements Q1 and Q2, respectively. Reactor L1 is connected between the connection node of switching elements Q1 and Q2 and power line 6. Capacitor C0 is connected between power line 7 and power line 5.

Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17, which are provided in parallel between power line 7 and power line 5. Each phase arm includes a switching element connected in series between power line 7 and power line 5. For example, U-phase arm 15 consists of switching elements Q3 and Q4, V-phase arm 16 consists of switching elements Q5 and Q6, and W-phase arm 17 consists of switching elements Q7 and Q8. Diodes D3 to D8 are connected in antiparallel to the switching elements Q3 to Q8, respectively. On/off of the switching elements Q3 to Q8 is controlled by switching control signals S3 to S8 from the control device 30.

Note that as the switching elements Q1 to Q8, IGBTs (Insulated Gate Bipolar Transistors), power MOS (Metal Oxide Semiconductor) transistors, power bipolar transistors, etc. can be used.

Electric motor M1 generates torque for driving drive wheels (not shown). Alternatively, the electric motor M1 may be configured to have the function of a generator driven by an engine (not shown), or may be configured to have the functions of both an electric motor and a generator. The electric motor M1 is typically a three-phase permanent magnet type synchronous motor, and is configured such that one ends of three coils of U, V, and W phases are commonly connected to a neutral point. The other ends of the U, V, and W phase coils are connected to the intermediate points of the switching elements of the U, V, and W phase arms 15 to 17, respectively.

Converter 12 is basically controlled such that switching elements Q1 and Q2 are complementary and alternately turned on and off within each switching period. Converter 12 boosts voltage VH to voltage Vb or higher. This boosting operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q2 to the power line 7 via the switching element Q1 and the diode D1.

The voltage conversion ratio (ratio of VH and Vb) in this boosting operation is controlled by the on-period ratio (duty ratio) of the switching elements Q1 and Q2 with respect to the switching period. Incidentally, if the switching elements Q1 and Q2 are respectively fixed on and off, it is also possible to set VH=Vb (voltage conversion ratio=1.0).

Capacitor C0 smoothes the DC voltage from converter 12 and supplies the smoothed DC voltage to inverter 14. Voltage sensor 13 detects the voltage across capacitor C0, that is, voltage VH, and outputs the detected value to control device 30.

When the torque command value of the electric motor M1 is positive (Trqcom>0), the inverter 14 converts the DC voltage into an AC voltage by the switching operation of the switching elements Q3 to Q8 in response to the switching control signals S3 to S8, and converts the DC voltage into an AC voltage. The electric motor M1 is driven so as to output a torque of . Further, when the torque command value of the electric motor M1 is zero (Trqcom=0), the inverter 14 converts the DC voltage into an AC voltage by a switching operation in response to the switching control signals S3 to S8, and the torque becomes zero. The electric motor M1 is driven as follows. As a result, the electric motor M1 is driven to generate zero or positive torque specified by the torque command value Trqcom.

Furthermore, during regenerative braking of the vehicle, the torque command value of electric motor M1 is set to be negative (Trqcom<0). In this case, inverter 14 converts the AC voltage generated by motor M1 into DC voltage by a switching operation in response to switching control signals S3 to S8, and supplies the converted DC voltage to converter 12. Note that regenerative braking here refers to braking that involves regenerative power generation when the driver of an electric vehicle operates the foot brake, or to turning off the accelerator pedal while driving without operating the foot brake. This includes decelerating the vehicle (or stopping acceleration) while generating regenerative power.

Current sensor 24 detects motor current i flowing through electric motor M1, and outputs the detected value to control device 30. Note that since the sum of the instantaneous values of the three-phase currents iu, iv, and iw is zero, the current sensor 24 is arranged to detect the motor current for two phases (for example, the V-phase current iv and the W-phase current iw). It's enough.

The rotation angle sensor (resolver) 25 detects the rotation angle θ of the rotor of the electric motor M1, and outputs the detected value to the control device 30. The control device 30 can calculate the rotation speed and angular velocity ω (rad/s) of the electric motor M1 based on the rotation angle θ. Note that the rotation angle sensor 25 may be omitted by directly calculating the rotation angle θ from the motor voltage and current using the control device 30.

The control device 30 is composed of an electronic control unit (ECU), and inputs a CPU (Central Processing Unit), memory (ROM (Read Only Memory) and RAM (Random Access Memory)), and various signals. It is configured to include an input/output port for output (none of which is shown). Control device 30 executes various controls such as the running state of vehicle 100 and charging/discharging of power storage device B, based on signals received from each sensor, programs and maps stored in memory, and the like. Note that these controls are not limited to processing by software, but can also be constructed and processed by dedicated hardware (electronic circuits).

As a typical function, the control device 30 performs a control method described later based on the torque command value Trqcom, voltage Vb, current Ib, voltage VH, motor current iv, iw, rotation angle θ, etc. detected by each sensor. The operation of the inverter 14 is controlled so that the electric motor M1 outputs torque according to the torque command value Trqcom.

Further, control device 30 controls converter 12 in either continuous control mode or intermittent control mode. The continuous control mode is a mode in which the converter 12 operates without stopping the boost operation. The intermittent control mode is a mode in which converter 12 intermittently repeats boosting operation and stopping the boosting operation. Since the intermittent control mode includes a stopped state of the converter, the loss of the converter 12 can be reduced by operating the converter 12 in the intermittent control mode.

Control device 30 operates converter 12 in an intermittent control mode, for example, when vehicle 100 is running under low load and current consumption of electric motor M1 is low. In the intermittent control mode, control device 30 stops converter 12 when the deviation between command value VHr of voltage VH and voltage VH is smaller than a predetermined value, and stops converter 12 when the deviation exceeds a predetermined value. is activated to boost voltage VH to command value VHr. Note that when converter 12 performs a boost operation, switching elements Q1 and Q2 are turned on and off, and when converter 12 stops, both switching elements Q1 and Q2 are turned off.

Note that the case where converter 12 does not step up the voltage in continuous control mode and the case where converter 12 stops in intermittent control mode are different in the following points. That is, when converter 12 does not step up the voltage in continuous control mode, switching elements Q1 and Q2 are fixed on and off, respectively (duty ratio 1), and voltage VH becomes the voltage of power storage device B. On the other hand, when converter 12 is stopped in the intermittent control mode, switching elements Q1 and Q2 are both turned off, and unless voltage VH becomes lower than voltage Vb of power storage device B, the voltage of power storage device B is passed through converter 12. It is not supplied to the inverter 14.

<Control of electric motor M1>
In this drive control system, PWM control and rectangular wave control are switched and used for controlling the electric motor M1.

In PWM control, for example, the on/off of each phase arm element is controlled according to a voltage comparison between a sinusoidal voltage command and a carrier wave (typically a triangular wave) (sinusoidal PWM control). As a result, the duty is set so that the fundamental wave component becomes a sine wave within a certain period for the set of the high level period corresponding to the on period of the upper arm element and the low level period corresponding to the on period of the lower arm element. is controlled.

In addition, in the sine wave PWM control, since the amplitude of the sine wave voltage command is limited to the range below the carrier wave amplitude, the fundamental wave component of the voltage applied to the motor M1 (hereinafter also referred to as "motor applied voltage") is The voltage can only be increased to about 0.61 times the voltage VH. The modulation degree, which is the ratio of the fundamental wave component (effective value) of the motor applied voltage (line voltage) to the voltage VH, is expressed, for example, by the following equation.

Modulation degree = √(Vd ² +Vq ² )/VH…(1)
Note that the PWM control may include overmodulation PWM control that performs PWM control similar to sine wave PWM control in a range where the amplitude of the voltage command (sine wave component) is larger than the carrier wave amplitude. In overmodulation PWM control, the fundamental wave component can be increased by distorting the voltage command from the original sine wave waveform (amplitude correction), and the modulation degree can be increased by 0.78 from the highest modulation rate in the sine wave PWM control mode. It can be increased to a range. In addition, below, PWM control shall be sine wave PWM control.

In the rectangular wave control, a voltage corresponding to one pulse of a rectangular wave with a ratio of high level period to low level period of 1:1 is applied to the motor M1 within the above-mentioned fixed period. As a result, the modulation rate can be increased to 0.78 under square wave control.

In the electric motor M1, as the rotational speed and output torque increase, the induced voltage increases, so the required drive voltage (motor required voltage) increases. Voltage VH needs to be set higher than this motor required voltage. On the other hand, voltage VH has a limit value. Therefore, PWM control and square wave control are selectively applied depending on the operating state of electric motor M1. In addition, in rectangular wave control, the amplitude of the motor applied voltage is fixed, so the phase control of the rectangular wave voltage pulse is performed based on the torque deviation with respect to the torque command value (the difference between the actual torque value (estimated value) and the torque command value). Torque control is performed.

FIG. 2 is a block diagram functionally showing the configuration of the control device 30 shown in FIG. 1. As shown in FIG. Referring to FIG. 2, control device 30 includes a PWM control section 200, a square wave control section 400, and a control mode switching section 500.

PWM control unit 200 receives torque command value Trqcom, motor currents iv and iw detected by current sensor 24, and rotation angle θ detected by rotation angle sensor 25. Based on these signals, the PWM control unit 200 generates voltage command values Vd#, Vq# to be applied to the inverter 14 by current feedback control, and based on the generated voltage command values Vd#, Vq#. , generates switching control signals S3 to S8 for driving the inverter 14, and outputs them to the control mode switching section 500.

Rectangular wave control section 400 receives torque command value Trqcom, motor currents iv and iw, and rotation angle θ. Based on these signals, the rectangular wave control unit 400 sets the phase of the rectangular wave voltage applied to the inverter 14 by torque feedback control, and drives the inverter 14 based on the set voltage phase. The switching control signals S3 to S8 are generated and output to the control mode switching unit 500.

Control mode switching section 500 receives voltage command values Vd#, Vq# from PWM control section 200 and receives voltage VH from voltage sensor 13. Control mode switching section 500 then switches between PWM control and square wave control based on the degree of modulation calculated from voltage VH and voltage command values Vd#, Vq#. Specifically, the control mode switching unit 500 switches from PWM control to square wave control when the modulation degree increases to M1. Moreover, the control mode switching unit 500 switches from rectangular wave control to PWM control when the modulation degree decreases to M2 (M2<M1). The reason for setting M2<M1 is to prevent switching chattering near the threshold value.

<PWM control>
FIG. 3 is a block diagram showing a configuration example of the PWM control section 200 shown in FIG. 2. As shown in FIG. Referring to FIG. 3, PWM control section 200 includes a current command generation section 210, coordinate conversion sections 220 and 250, PI calculation sections 240 and 242, and PWM modulation section 260.

Current command generation unit 210 uses a map or table prepared in advance showing the relationship between torque, d-axis current, and q-axis current to generate d-axis current command values Idcom and q corresponding to torque command value Trqcom of electric motor M1. Generate an axial current command value Iqcom. The coordinate conversion unit 220 converts the V-phase current iv and W-phase current iw detected by the current sensor 24 into the d-axis current Id and the q-axis by coordinate conversion (uvw3 phase → dq2 phase) using the rotation angle θ of the electric motor M1. Convert to current Iq.

The PI calculation unit 240 calculates the d-axis voltage command value Vd# by performing a PI (proportional integral) calculation on the d-axis current deviation ΔId (ΔId=Idcom-Id) with respect to the d-axis current command value Idcom according to the following formula. .

Vd#=Kdp×ΔId+Kdi×ΣΔId…(2)
The PI calculation unit 242 calculates the q-axis voltage command value Vq# by performing a PI calculation on the q-axis current deviation ΔIq (ΔIq=Iqcom−Iq) with respect to the q-axis current command value Iqcom according to the following equation.

Vq♯=Kdq×ΔIq+Kqi×ΣΔIq…(3)
Note that in equations (2) and (3), Kdp and Kdq are proportional gains, and Kdi and Kqi are integral gains.

The coordinate transformation unit 250 converts the d-axis voltage command value Vd# and the q-axis voltage command value Vq# into U-phase, V-phase, and W-phase by coordinate transformation (dq2 phase → uvw3 phase) using the rotation angle θ of the electric motor M1. are converted into respective phase voltage command values Vu, Vv, and Vw. The PWM modulator 260 generates switching control signals S3 to S8 (PWM signals) for driving the inverter 14 based on a comparison between each phase voltage command value Vu, Vv, Vw and a carrier wave. Note that the carrier wave is composed of a triangular wave or a sawtooth wave of a predetermined frequency.

<Square wave control>
FIG. 4 is a block diagram showing a configuration example of the rectangular wave control section 400 shown in FIG. 2. As shown in FIG. Referring to FIG. 4, rectangular wave control section 400 includes a coordinate transformation section 410, a torque estimation section 420, a PI calculation section 430, and a switching command calculation section 440.

The coordinate conversion unit 410 converts the V-phase current iv and W-phase current iw detected by the current sensor 24 into the d-axis current Id and the q-axis by coordinate conversion (uvw3 phase → dq2 phase) using the rotation angle θ of the electric motor M1. Convert to current Iq. The torque estimation unit 420 calculates the estimated torque value Trq of the electric motor M1 from the d-axis current Id and the q-axis current Iq using a map or table prepared in advance that shows the relationship between the d-axis current and the q-axis current and the torque. do.

The PI calculation unit 430 calculates the phase φv of the rectangular wave voltage by performing a PI calculation on the torque deviation ΔTrq (ΔTrq=Trqcom−Trq) with respect to the torque command value Trqcom according to the following equation.

φv=Kp×ΔTrq+Ki×ΣΔTrq…(4)
Kp and Ki are a proportional gain and an integral gain, respectively, and both are positive values. With such torque feedback (F/B) control, when positive torque is generated (Trqcom>0), the voltage phase is advanced (φv>0) when torque is insufficient (ΔTrq>0), while when torque is excessive When (ΔTrq<0), the voltage phase is delayed (φv<0), and when negative torque is generated, the voltage phase is delayed when torque is insufficient, while the voltage phase is advanced when torque is excessive.

The switching command calculation unit 440 generates each phase voltage command value (rectangular wave pulse) Vu, Vv, Vw according to the voltage phase φv, and generates switching control signals S3 to S8 based on each phase voltage command value Vu, Vv, Vw. generate. Then, as the inverter 14 performs a switching operation according to the switching control signals S3 to S8, a rectangular wave pulse according to the voltage phase φv is applied as each phase voltage of the motor M1.

Note that by arranging a torque sensor in place of the coordinate conversion section 410 and the torque estimating section 420, the torque deviation ΔTrq may be determined based on the detected value of the torque sensor.

<Occurrence of torque deviation in intermittent control mode>
While converter 12 is in the intermittent control mode, voltage VH fluctuates greatly in response to load fluctuations while converter 12 is stopped. Therefore, the degree of modulation changes in accordance with changes in voltage VH, and PWM control and square wave control are frequently switched. As a result, the d-axis voltage command value Vd# gradually increases, and as a result, the followability of the actual torque to the torque command value Trqcom may decrease, resulting in a torque deviation. The mechanism of this torque deviation generation will be explained below.

FIG. 5 is a timing chart showing changes in various parameters during the intermittent control mode. In FIG. 5, voltage VH, operating state of converter 12 (prohibited/activated), control of inverter 14 (square wave control/PWM control), d-axis current Id, d-axis voltage command value Vd#, modulation degree, motor M1 A time-series change in the actual torque (estimated torque value Trq) is shown.

Referring to FIG. 5, at time t1, voltage VH reaches command value VHr, so driving of converter 12 is prohibited and converter 12 stops. At time t2, since the degree of modulation falls below M2, inverter control is switched from rectangular wave control to PWM control.

After time t1, converter 12 is stopped, so voltage VH decreases. When voltage VH decreases with respect to command value VHr, in PWM control, actual q-axis voltage Vq decreases with respect to q-axis voltage command value Vq#. When the q-axis voltage Vq decreases, the d-axis current Id increases to the negative side. Then, in PWM control, the d-axis voltage command value Vd# increases based on the d-axis current deviation ΔId (ΔId=Idcom-Id).

As the d-axis voltage command value Vd# increases, the modulation degree increases. Then, at time t3, when the modulation degree reaches M1, inverter control is switched from PWM control to square wave control. In the rectangular wave control, the phase of the motor applied voltage is manipulated, and the d-axis voltage command value Vd#, which has increased in the PWM control, tends to decrease.

On the other hand, regarding converter 12, at time t4, voltage VH has decreased by a predetermined value or more with respect to command value VHr, so the drive prohibition of converter 12 is canceled, converter 12 is activated, and voltage VH increases. As voltage VH increases, the modulation degree decreases.

Then, at time t5, voltage VH reaches command value VHr, so driving of converter 12 is prohibited and converter 12 is stopped. At time t6, since the degree of modulation falls below M2, the inverter control is switched again from square wave control to PWM control.

By the way, in rectangular wave control, the control gain may be set to be low from the viewpoint of control stabilization. In particular, when reducing the capacitance of the smoothing capacitor C0 in order to downsize the device, the voltage VH tends to fluctuate in response to load fluctuations. The control gain of the wave control is set to be low.

In this case, before the d-axis voltage command value Vd#, which increased during the PWM control from time t2 to t3, returns to (decreases) to an appropriate level due to the rectangular wave control from time t3 to t6, at time t6, the voltage of converter 12 increases. Due to the rise in voltage VH caused by the operation, the square wave control is switched again to PWM control. Then, PWM control is performed from a state where d-axis voltage command value Vd# is larger than when switching to PWM control at the previous time t2, and d-axis voltage command value Vd# further increases.

Then, from time t6 to t10, the d-axis voltage command value Vd# increases as a whole, similarly to time t2 to t6. As described above, when PWM control and square wave control are frequently switched, d-axis voltage command value Vd# gradually increases, and as a result, torque deviation Trq increases.

Therefore, in the drive control system according to the first embodiment, the control gain of the rectangular wave control is made larger during the intermittent control mode of the converter 12 than the control gain during the continuous control mode. As a result, in the intermittent control mode, it is possible to return the d-axis voltage command value Vd#, which has increased during the PWM control, to an appropriate level during the rectangular wave control. Therefore, according to this drive control system, it is possible to reduce the loss of the converter 12 through the intermittent boost control of the converter 12, and to suppress the torque deviation caused by the intermittent boost control.

Note that the control gain of the rectangular wave control that is made larger in the intermittent control mode than in the continuous control mode may be both the integral gain Ki and the proportional gain Kp, or only the integral gain Ki. Since the increase in the d-axis voltage command value Vd# is due to an increase in the integral term of the PI calculation unit 430 in the rectangular wave control unit 400, it is effective to increase the integral gain Ki. Only the proportional gain Kp may be increased if this property can be obtained.

FIG. 6 is a flowchart illustrating an example of a processing procedure of rectangular wave control executed by the control device 30 according to the first embodiment. The series of processes shown in this flowchart are repeatedly executed every predetermined period.

Referring to FIG. 6, control device 30 acquires a detected value of rotation angle θ of electric motor M1 from rotation angle sensor 25, and acquires currents iv and iw of electric motor M1 from current sensor 24 (step S10). Next, in step S20, the control device 30 uses the acquired rotation angle θ to convert the V-phase current iv and W-phase current iw detected by the current sensor 24 into a d-axis current Id and a q-axis current Iq ( uvw3 phase → dq2 phase conversion).

Next, the control device 30 estimates the actual torque of the electric motor M1 from the d-axis current Id and the q-axis current Iq using a map or table prepared in advance that shows the relationship between the d-axis current and the q-axis current and the torque. The estimated torque value Trq is calculated (step S30).

Subsequently, control device 30 determines whether converter 12 is in the intermittent control mode (step S40). For example, control device 30 operates converter 12 in the intermittent control mode when vehicle 100 is running under low load and the current consumption of electric motor M1 is less than a predetermined value.

When it is determined that the mode is not in the intermittent control mode, that is, in the continuous control mode (NO in step S40), the control device 30 sets the F/B control gain K1 for the continuous control mode as the control gain for the rectangular wave control. (proportional gain Kp1 and integral gain Ki1) are set (step S50).

On the other hand, if it is determined in step S40 that the intermittent control mode is in effect (YES in step S40), the control device 30 sets the F/B control gain K2 (proportional gain Kp2 and integral gain Ki2) are set (step S60 ).

Here, the F/B control gain K2 for the intermittent control mode is larger than the F/B control gain K1 for the continuous control mode. In the first embodiment, for both the proportional gain Kp and the integral gain Ki, the gain for the intermittent control mode is larger than the gain for the continuous control mode, that is, Kp2>Kp1 and Ki2>Ki1. Note that each gain Kp1, Ki1, Kp2, and Ki2 is stored in the memory (ROM) of the control device 30.

Next, the control device 30 calculates the deviation ΔTrq between the torque command value Trqcom and the estimated torque value Trq, and executes PI control (torque F/B control) based on the calculated torque deviation ΔTrq (step S70). Specifically, the control device 30 calculates a control deviation by performing a PI calculation on the torque deviation ΔTrq, and sets the phase φv of the rectangular wave voltage according to the control deviation.

Then, the control device 30 generates each phase voltage command value (rectangular wave pulse) Vu, Vv, Vw according to the set voltage phase φv, and generates a switching control signal based on each phase voltage command value Vu, Vv, Vw. S3 to S8 are generated (step S80). Then, as the inverter 14 performs a switching operation according to the switching control signals S3 to S8, a rectangular wave pulse according to the voltage phase φv is applied as each phase voltage of the motor.

As described above, in this first embodiment, regarding the control gain of the square wave control, the control gain K2 when the converter 12 operates in the intermittent control mode is the control gain K2 when the converter 12 operates in the continuous control mode. Larger than K1. Thereby, in the intermittent control mode, the d-axis voltage command value Vd# increased in PWM control can be returned to an appropriate level in rectangular wave control. Therefore, according to the first embodiment, it is possible to reduce the loss of the converter 12 through the intermittent boost control of the converter 12, while suppressing a decrease in torque followability caused by the intermittent boost control.

[Embodiment 2]
In the first embodiment, in order to return the d-axis voltage command value Vd# increased in PWM control to an appropriate level in square wave control in intermittent control mode, the control gain of square wave control is changed to F/ in continuous control mode. The control gain was set to be larger than the B control gain. In the second embodiment, in the intermittent control mode, the control gain of the PWM control is made smaller than the control gain in the continuous control mode in order to suppress an increase in the d-axis voltage command value Vd# in the PWM control.

The overall configuration of vehicle 100 and the drive control system installed therein in Embodiment 2 is the same as the configuration shown in FIGS. 1 to 4.

FIG. 7 is a flowchart illustrating an example of a PWM control processing procedure executed by the control device 30 according to the second embodiment. The series of processes shown in this flowchart are repeatedly executed every predetermined period.

Referring to FIG. 7, control device 30 acquires a detected value of rotation angle θ of electric motor M1 from rotation angle sensor 25, and acquires currents iv and iw of electric motor M1 from current sensor 24 (step S110). Next, in step S120, the control device 30 converts the V-phase current iv and W-phase current iw detected by the current sensor 24 into a d-axis current Id and a q-axis current Iq using the acquired rotation angle θ ( uvw3 phase → dq2 phase conversion).

Next, the control device 30 calculates the d-axis current command value Idcom and the q-axis current from the torque command value Trqcom using a map or table prepared in advance that shows the relationship between the torque of the electric motor M1 and the d-axis current and the q-axis current. A command value Iqcom is calculated (step S130).

Subsequently, control device 30 determines whether the control mode of converter 12 is in the intermittent control mode (step S140). For example, control device 30 operates converter 12 in the intermittent control mode when vehicle 100 is running under low load and the current consumption of electric motor M1 is less than a predetermined value.

If it is determined that the mode is not in the intermittent control mode, that is, in the continuous control mode (NO in step S140), the control device 30 sets the F/B control gain K3 (for the continuous control mode) as the control gain for the PWM control. A proportional gain Kdp3 and an integral gain Kdi3 for calculating the d-axis voltage command value Vd#, and a proportional gain Kqp3 and an integral gain Kqi3 for calculating the q-axis voltage command value Vq# are set (step S150).

On the other hand, if it is determined in step S140 that the intermittent control mode is in effect (YES in step S140), the control device 30 sets the F/B control gain K4 (d-axis voltage A proportional gain Kdp4 and an integral gain Kdi4 for calculating the command value Vd#, and a proportional gain Kqp4 and an integral gain Kqi4 for calculating the q-axis voltage command value Vq# are set (step S160).

Here, the F/B control gain K4 for the intermittent control mode is smaller than the F/B control gain K3 for the continuous control mode. In the first embodiment, for both the proportional gains Kdp, Kqp and the integral gains Kdi, Kqi, the gains for the intermittent control mode are smaller than the gains for the continuous control mode, that is, Kdp4<Kdp3, Kdi4<Kdi3, Kqp4<Kqp3, Kqi4<Kqi3.

Next, the control device 30 calculates the deviation ΔId between the d-axis current command value Idcom and the d-axis current Id, and the deviation ΔIq between the q-axis current command value Iqcom and the q-axis current Iq, and calculates the calculated deviation ΔId, PI control (current F/B control) based on ΔIq is executed (step S170). Specifically, the control device 30 calculates a control deviation by performing a PI calculation on the d-axis current deviation ΔId, and sets the d-axis voltage command value Vd# according to the control deviation. Further, the control device 30 calculates a control deviation by performing a PI calculation on the q-axis current deviation ΔIq, and sets the q-axis voltage command value Vq# according to the control deviation.

Next, in step S180, the control device 30 uses the rotation angle θ acquired in step S110 to change the set d-axis voltage command value Vd# and q-axis voltage command value Vq# to the U phase, V phase, W phase. Convert to each phase voltage command Vu, Vv, Vw (dq2 phase→uvw3 phase conversion).

Then, the control device 30 generates switching control signals S3 to S8 for driving the inverter 14 based on the comparison between the generated phase voltage commands Vu, Vv, and Vw and the carrier wave (step S190). Then, as the inverter 14 performs a PWM switching operation according to the switching control signals S3 to S8, voltages according to the d-axis voltage command value Vd# and the q-axis voltage command value Vq# are applied as each phase voltage of the motor. Ru.

As described above, in this second embodiment, regarding the control gain of PWM control, the control gain K4 when the converter 12 operates in the intermittent control mode is the control gain K3 when the converter 12 operates in the continuous control mode. smaller than Thereby, in the intermittent control mode, it is possible to suppress an increase in d-axis voltage command value Vd# in PWM control, and it is possible to return the increased d-axis voltage command value Vd# to an appropriate level in rectangular wave control. Therefore, according to the second embodiment as well, it is possible to reduce the loss of the converter 12 through the intermittent boost control of the converter 12, while suppressing a decrease in torque followability caused by the intermittent boost control.

It is also planned that the embodiments disclosed herein will be implemented in appropriate combinations within a technically consistent range. The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

5, 6, 7 power line, 10, 13 voltage sensor, 10# DC voltage generator, 11, 24 current sensor, 12 converter, 14 inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm, 25 rotation angle sensor, 30 control device, 100 vehicle, 200 PWM control section, 210 current command generation section, 220, 250, 410 coordinate transformation section, 240, 242, 430 PI calculation section, 260 PWM modulation section, 400 square wave control section, 420 Torque estimation section, 440 Switching command calculation section, 500 Control mode switching section, C0, C1 Capacitor, D1 to D8 Diode, L1 Reactor, M1 Electric motor, Q1 to Q8 Switching element.

Claims (1)

A power storage device;
An inverter that drives the electric motor for driving,
a converter that is provided between the power storage device and the inverter and boosts the voltage of DC power supplied from the power storage device to the inverter to a voltage higher than the voltage of the power storage device;
comprising a control device that controls the inverter and the converter,
The control device includes:
controlling the inverter by switching between pulse width modulation control and rectangular wave control depending on the degree of modulation;
controlling the converter in either a continuous control mode in which the converter is operated continuously or an intermittent control mode in which the converter is intermittently operated;
A drive control system for a vehicle, wherein a control gain of the rectangular wave control when the converter operates in the intermittent control mode is larger than a control gain of the rectangular wave control when the converter operates in the continuous control mode. .

Images