JP2010172139A - Device and method for drive controlling vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce excessive generation of a capacitor voltage at a low battery temperature. <P>SOLUTION: A motor MG2 is provided to drive a drive wheel. The motor MG2 is electrically connected to a battery B through an inverter 30. A smoothing capacitor and a converter 15 having a step-up function are interposed between the inverter 30 and the battery B. A step-up voltage target value Vbo* of the converter 15 is limited to be lower when the temperature of the battery B is lower than a predetermined value in comparison with the case in which the temperature of the battery B is high. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a driving control technique for a vehicle capable of driving driving wheels with a motor.

As a vehicle drive control device, there is a device described in Patent Document 1. In this device, when the engine (internal combustion engine) is stopped, the first motor generates the stopping force of the engine with the power generation torque. At that time, the first motor supplies the generated power to the battery to store it. The second motor electrically connected to the battery can be driven and regenerated with respect to the drive wheel.
When the input power to the battery exceeds the allowable value of the battery, the operation of the power transfer circuit is controlled so that the power consumption increases.

JP 2007-290483 A

The output of the second motor connected to the drive wheel is suddenly reduced due to a sudden decrease in the rotational speed of the drive wheel due to the drive wheel changing from the slip state to the grip state and a sudden limit of the drive torque during the traction control operation for suppressing the slip. In this case, the second motor cannot consume all of the generated power of the first motor that extracts the engine output as drive output power, and the surplus becomes the battery input.
At this time, since the battery at low temperature has a small amount of regenerative power received, it cannot receive the surplus power, and the inverter or the boost converter capacitor positioned between the first motor and the second motor and the battery may receive it. is there. In this case, the capacitor voltage may rise excessively and affect the durability.
The present invention pays attention to the above points, and an object of the present invention is to control the driving of a vehicle that can reduce the occurrence of excessive capacitor voltage when the battery temperature is low.

  In order to solve the above-described problems, the present invention includes a motor that drives drive wheels. The motor is electrically connected to the battery via an inverter. A converter having a boosting function and a smoothing capacitor are interposed between the inverter and the battery. Then, the boosted voltage target value of the converter is limited to be lower when the battery temperature is lower than a predetermined value compared to when the battery temperature is high.

According to the present invention, when the battery temperature is low and the amount of regenerative power received by the battery is small, the boosted voltage is limited to be low. As a result, even if the motor generated power exceeds the regenerative power acceptance amount of the battery, the boosted voltage is suppressed, so that the power that the smoothing capacitor can primarily receive within the withstand voltage increases.
As a result, it is possible to reduce the occurrence of excessive capacitor voltage when the battery temperature is low.

It is a figure explaining the system configuration of the vehicle concerning the embodiment based on the present invention. It is a figure which shows an example of the process of the smoothing capacitor protection control which concerns on 1st Embodiment based on this invention. It is a figure which shows the structure of the smoothing capacitor protection process part which concerns on 1st Embodiment based on this invention. It is a figure which shows the map of the coefficient K1 for calculating | requiring the limiting value of boost voltage target value. It is a figure which shows the map for calculating | requiring the coefficient K1a. It is a figure which shows the map for calculating | requiring the coefficient K1b. It is a figure which shows the map for calculating | requiring the coefficient K1c. It is a figure which shows the map for calculating | requiring the coefficient b. It is a figure which shows the structure of the smoothing capacitor protection process part which concerns on 2nd Embodiment based on this invention. It is a figure which shows the map for calculating | requiring the coefficient K4. It is a figure which shows the map for calculating | requiring the coefficient K4.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram for explaining a hybrid vehicle 100 in the present embodiment.
(Constitution)
As shown in FIG. 1, the hybrid vehicle 100 includes an engine 110, a power split mechanism 120, first motors MG <b> 1 and MG <b> 2, a speed reducer 130, a drive shaft 140, and wheels (drive wheels) 150. The hybrid vehicle 100 further includes a DC voltage generator DVG, a smoothing capacitor C0, first and second inverters 20 and 30, an engine controller 61, an integrated control device 60, and a drive control device 50.

The hybrid vehicle 100 includes an accelerator pedal sensor 62, a brake pedal sensor 63, and a vehicle speed sensor 64.
The accelerator pedal sensor 62 detects the accelerator opening as an acceleration instruction by the driver, and outputs a detection signal to the integrated control device 60.
The brake pedal sensor 63 detects the amount of brake depression as a deceleration instruction by the driver, and outputs a detection signal to the integrated control device 60.
The vehicle speed sensor 64 detects the vehicle speed based on the rotational speed of the wheels and outputs a detection signal to the integrated control device 60.

The integrated control device 60 calculates a target value Power ^* of the required driving force based on the accelerator opening and the vehicle speed. Then, the integrated control device 60 calculates the engine drive torque command value, the torque command value of the first motor MG1, and the torque command value of the second motor MG2 based on the target value Power ^* of the required drive force. The integrated control device 60 outputs the engine drive torque command value to the engine controller 61. The integrated control device 60 outputs the torque command value of the first motor MG1 and the torque command value of the second motor MG2 to the drive control device 50. Further, the integrated control device 60 calculates a target value of the required braking force based on the brake depression amount. Then, the integrated control device 60 calculates a control signal RGE (2) for regeneration of the second motor MG2 based on the target value of the required braking force, and outputs it to the drive control device 50.

The engine controller 61 controls the driving force of the engine according to the engine driving torque command value.
The engine 110 is constituted by an internal combustion engine such as a gasoline engine or a diesel engine, for example. The engine 110 is provided with a cooling water temperature sensor 112 that detects the temperature of the cooling water. The coolant temperature sensor 112 outputs a detection signal to the drive control device 50.

  Power split device 120 is configured to be able to split the power generated by engine 110 into a route to drive shaft 140 and a route to first motor MG1. As the power split mechanism 120, for example, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary gear, and a ring gear may be employed. In this case, for example, the rotor of the first motor MG1 is hollow, and the crankshaft of the engine 110 is passed through the center thereof. Thus, engine 110 and first motors MG1 and MG2 can be mechanically connected to power split device 120. Specifically, the rotor of the first motor MG1 is connected to the sun gear. The output shaft of engine 110 is connected to the planetary gear. Further, output shaft 125 of power split device 120 is connected to the ring gear. The output shaft 125 is also connected to the rotation shaft of the second motor MG2. And the output shaft 125 is connected to the drive shaft 140 for rotationally driving the drive wheel 150 via the reduction gear 130. Note that a speed reducer for the rotation shaft of the second motor MG2 may be further incorporated.

The first motor MG1 has both functions of an electric motor and a generator. That is, the first motor MG1 operates as a generator driven by the engine 110. In addition, first motor MG1 operates as an electric motor that starts engine 110.
Similarly, the second motor MG2 has both functions for an electric motor and a generator. That is, the second motor MG2 transmits its output to the drive shaft 140 via the output shaft 125 and the speed reducer 130. That is, the second motor MG2 constitutes an electric motor for generating vehicle driving force. Further, second motor MG2 generates regenerative power by generating output torque in the direction opposite to the rotation direction of wheel 150.

Next, a configuration for driving and controlling the first motors MG1 and MG2 will be described.
The DC voltage generator DVG includes a battery B, a smoothing capacitor C1, and a step-up / down converter 15.
As the battery B, a secondary battery such as a nickel metal hydride, lithium ion, or lead acid battery can be applied. An electric double layer capacitor or the like can be applied as the battery B.

  Here, the voltage sensor 10 detects the battery voltage Vb output from the battery B. The voltage sensor 10 outputs the detected battery voltage Vb to the drive control device 50. The current sensor 11 detects a battery current Ib input / output to / from the battery B. The current sensor 11 outputs the detected battery current Ib that has been detected to the drive control device 50. Further, the temperature sensor 12 detects the battery temperature Tb of the battery B. The temperature sensor 12 outputs the detected battery temperature Tb to the drive control device 50. Note that the temperature of the battery B may be locally different. For this reason, the temperature sensor 12 may be provided at a plurality of locations of the battery B.

The smoothing capacitor C <b> 1 is connected between the ground line 5 and the power supply line 6. A relay (not shown) is provided between the positive terminal of battery B and power line 6 and between the negative terminal of battery B and ground line 5. This relay (not shown) is turned on when the vehicle is driven and turned off when the vehicle is stopped.
The step-up / down converter 15 (hereinafter also simply referred to as a converter) includes a reactor L1 and power semiconductor elements (hereinafter referred to as “switching elements”) Q1 and Q2 that are controlled to be switched. Reactor L1 is connected between a connection node of switching elements Q1 and Q2 and power supply line 6. Further, the smoothing capacitor C 0 is connected between the power supply line 7 and the ground line 5.

The power semiconductor switching elements Q1 and Q2 are connected in series between the power supply line 7 and the ground line 5. On / off of the power semiconductor switching elements Q1 and Q2 is controlled by switching control signals S1 and S2 from the drive control device 50.
Here, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used as the switching element. Anti-parallel diodes D1 and D2 are arranged for switching elements Q1 and Q2. In the present embodiment, a case where an IGBT is used as a switching element will be described as an example. The same applies to other switching elements.

The DC voltage on the power supply line 7 can be variably controlled without being fixed to the output voltage of the battery B by the step-up / down converter 15 described later. As a result, the amplitude of the AC voltage applied to the first motors MG1 and MG2 can be variably controlled to enable highly efficient motor control.
The DC voltage sides of the first and second inverters 20 and 30 are connected to the buck-boost converter 15 through the common ground line 5 and the power supply line 7. The buck-boost converter 15, the smoothing capacitor C0, and the first and second inverters 20 and 30 constitute a power transfer circuit.

  First inverter 20 includes U-phase arm 22, V-phase arm 24, and W-phase arm 26. U-phase arm 22, V-phase arm 24, and W-phase arm 26 are provided in parallel between power supply line 7 and ground line 5. Each phase arm is composed of a switching element connected in series between the power supply line 7 and the ground line 5. For example, the U-phase arm 22 includes switching elements Q11 and Q12, the V-phase arm 24 includes switching elements Q13 and Q14, and the W-phase arm 26 includes switching elements Q15 and Q16. Further, antiparallel diodes D11 to D16 are connected to switching elements Q11 to Q16, respectively. The switching elements Q11 to Q16 are turned on / off by switching control signals S11 to S16 from the drive control device 50.

  First motor MG1 includes a U-phase coil winding U1, a V-phase coil winding V1 and a W-phase coil winding W1 provided on the stator, and a rotor (not shown). One ends of the U-phase coil winding U1, the V-phase coil winding V1, and the W-phase coil winding W1 are connected to each other at a neutral point N1. The other ends of the U-phase coil winding U1, the V-phase coil winding V1, and the W-phase coil winding W1 are connected to the U-phase arm 22, the V-phase arm 24, and the W-phase arm 26 of the first inverter 20, respectively. The first inverter 20 is connected between the DC voltage generator DVG and the first motor MG1 by on / off control (switching control) of the switching elements Q11 to Q16 in response to switching control signals S11 to S16 by vector control from the drive control device 50. Bidirectional power conversion is performed.

  Specifically, the first inverter 20 converts the DC voltage received from the power supply line 7 into a three-phase AC voltage according to switching control by the drive control device 50. Then, the converted three-phase AC voltage is output to the first motor MG1. Thereby, the first motor MG1 is driven so as to generate a designated torque. The first inverter 20 receives the output of the engine 110 and converts the three-phase AC voltage generated by the first motor MG1 into a DC voltage according to switching control by the drive control device 50. Then, the converted DC voltage is output to the power supply line 7.

The second inverter 30 is configured similarly to the first inverter 20. The second inverter 30 includes switching elements Q21 to Q26 that are on / off controlled by switching control signals S21 to S26 and antiparallel diodes D21 to D26.
The second motor MG2 is configured similarly to the first motor MG1. That is, the second motor MG2 includes a U-phase coil winding U2, a V-phase coil winding V2 and a W-phase coil winding W2 provided on the stator, and a rotor (not shown). Similarly to the first motor MG1, one ends of the U-phase coil winding U2, the V-phase coil winding V2, and the W-phase coil winding W2 are connected to each other at a neutral point N2. The other ends of the U-phase coil winding U2, the V-phase coil winding V2, and the W-phase coil winding W2 are connected to the U-phase arm 32, the V-phase arm 34, and the W-phase arm 36 of the second inverter 30, respectively.

The second inverter 30 is connected between the DC voltage generator DVG and the second motor MG2 by on / off control (switching control) of the switching elements Q21 to Q26 in response to switching control signals S21 to S26 by vector control from the drive control device 50. Bidirectional power conversion is performed.
Specifically, the second inverter 30 converts the DC voltage received from the power supply line 7 into a three-phase AC voltage according to switching control by the drive control device 50. Then, the converted three-phase AC voltage is output to the second motor MG2. As a result, the second motor MG2 is driven to generate a designated torque. The second inverter 30 receives the rotational force from the wheel 150 during regenerative braking of the vehicle, and converts the three-phase AC voltage generated by the second motor MG2 into a DC voltage according to switching control by the drive control device 50. Then, the converted DC voltage is output to the power supply line 7.

The regenerative braking here means braking with regenerative power generation when the driver operating the hybrid vehicle performs a foot brake operation, or turning off the accelerator pedal while driving, although the foot brake is not operated. This includes decelerating the vehicle (or stopping acceleration) while generating regenerative power.
A current sensor 27 and a rotation angle sensor (resolver) 28 are provided for each of the first motors MG1 and MG2. Each current sensor 27 detects motor currents MCRT (1), MCRT (2) of the first motors MG1, MG2, and supplies detection signals to the drive control device 50. Here, the sum of instantaneous values of the three-phase currents iu, iv, iw is zero. Therefore, it is sufficient to arrange current sensor 27 so as to detect motor currents for two phases (for example, V-phase current iv and W-phase current iw).

  Each rotation angle sensor 28 detects the rotor rotation angle rotor rotation angle θ (1), θ (2) of the rotor (not shown) of the first and second motors MG1, MG2. The rotation angle sensor 28 supplies the detection signal to the drive control device 50. The drive control device 50 calculates the rotational speed Nmt (rotational angular velocity ω) of the first and second motors MG1 and MG2 based on the rotational angle θ. Note that the term “number of revolutions” refers to the number of revolutions per unit time (typically per minute) unless otherwise specified.

Further, the drive control device 50 receives a torque command value Tqcom (1) of the first motor MG1 and a control signal RGE (1) indicating a regenerative operation as a motor command from the integrated control device 60, and the second motor MG2. A torque command value Tqcom (2) and a control signal RGE (2) indicating a regenerative operation are input.
The drive control device 50 follows the predetermined program processing so that the first motor MG1, MG2 operates based on the motor command input from the host integrated control device 60, the step-up / down converter 15, the first and second inverters 20, Switching control signals S1 and S2 (step-up / down converter 15), S11 to S16 (first inverter 20), and S21 to S26 (second inverter 30) for switching control of 30 are generated. In order to perform this inverter control, the drive control device 50 includes a first vector control unit 72 that performs vector control of the first inverter 20 and a second vector control unit 73 that performs vector control of the second inverter 30.

Further, the drive control device 50 is input with information such as a charge rate (SOC: State of Charge) of the battery B and input powers Pin and Pout indicating charge / discharge restrictions. Accordingly, the drive control device 50 has a function of limiting the power consumption and the generated power (regenerative power) in the first motors MG1 and MG2 as necessary so that the battery B is not overcharged or discharged. .
Here, in the present embodiment, the mechanism for switching the switching frequency in the inverter control by the single drive control device 50 has been described. However, a similar control configuration can be realized by cooperative operation of a plurality of control devices.

Next, operations of the step-up / down converter 15 and the first and second inverters 20 and 30 in the drive control of the first motors MG1 and MG2 will be described.
Drive controller 50 sets voltage command value VHref of DC voltage VH in accordance with the operating state of first motors MG1 and MG2 during the step-up operation of buck-boost converter 15. Here, the DC voltage VH corresponds to the DC voltage of the first and second inverters 20 and 30. This DC voltage VH is hereinafter also referred to as “system voltage VH”. Further, voltage command value VHref of DC voltage VH is also referred to as system voltage command value VHref.

The drive control device 50 generates the switching control signals S1 and S2 based on the system voltage command value VHref and the detection value of the voltage sensor 13 so that the output voltage of the buck-boost converter 15 becomes equal to the system voltage command value VHref. . That is, the output voltage of the buck-boost converter 15 is controlled with the system voltage command value VHref as the boost voltage target value Vbo ^* .
The step-up / down converter 15 supplies the system voltage VH obtained by boosting the DC voltage (battery voltage) Vb supplied from the battery B to the first and second inverters 20 and 30 in common during the boosting operation. More specifically, in response to the switching control signals S1 and S2 from the drive control device 50, the duty ratios (ON period ratios) of the switching elements Q1 and Q2 are set, and the boost ratio is determined according to the duty ratio. Become.

  Further, during the step-down operation, the step-up / down converter 15 steps down the DC voltage (system voltage) supplied from the first and second inverters 20 and 30 via the smoothing capacitor C0 and charges the battery B. More specifically, in response to switching control signals S1 and S2 from drive control device 50, a period in which only switching element Q1 is turned on and a period in which both switching elements Q1 and Q2 are turned off are alternately provided. The step-down ratio is in accordance with the duty ratio in the ON period.

The smoothing capacitor C0 smoothes the DC voltage (system voltage) from the step-up / down converter 15 and supplies the smoothed DC voltage to the first and second inverters 20 and 30. The voltage sensor 13 detects the voltage across the smoothing capacitor C 0, that is, the system voltage VH, and outputs the detected value to the drive control device 50.
Power is also supplied from the power line 7 to other loads 170 such as auxiliary machines. For example, a DC / DC converter 160 for converting the system voltage VH to the auxiliary machine operating voltage Va is provided between the ground line 5 and the power supply line 7 and the load 170. As a result, the power on the power supply line 7 can be consumed by the load 170. The load 170 includes, for example, a warm water heater, a temperature control device (air conditioner), a blower motor, a defroster heater, and the like. The power consumption by the load 170 varies depending on the operating state (on / off setting, operating condition setting) of these loads.

  The second inverter 30 outputs torque according to the torque command value Tqcom (2) by the on / off operation (switching operation) of the switching elements Q21 to Q26 in response to the switching control signals S21 to S26 from the drive control device 50. Thus, the second motor MG2 is driven. The torque command value Tqcom (2) is a positive value (Tqcom (2)> 0), zero (Tqcom (2) = 0) in accordance with an output (torque × rotational speed) request to the second motor MG2 according to the driving situation. Or a negative value (Tqcom (2) <0) as appropriate.

  In particular, during regenerative braking of the hybrid vehicle, the torque command value of the second motor MG2 is set to a negative value (Tqcom (2) <0). In this case, the second inverter 30 converts the AC voltage generated by the second motor MG2 into a DC voltage by a switching operation in response to the switching control signals S21 to S26, and the converted DC voltage (system voltage). The voltage is supplied to the buck-boost converter 15 via the smoothing capacitor C0.

Similarly to the operation of the second inverter 30 described above, the first inverter 20 controls the first motor MG1 by on / off control of the switching elements Q11 to Q16 according to the switching control signals S11 to S16 from the drive control device 50. Power conversion is performed so as to operate according to the command value.
In this way, the drive control device 50 drives and controls the first and second motors MG1 and MG2 in accordance with the torque command values Tqcom (1) and Tqcom (2). Thus, in hybrid vehicle 100, generation of vehicle driving force due to power consumption by second motor MG2, generation of charging power of battery B or power consumption of second motor MG2 due to power generation by first motor MG1, and second Generation of charging power of the battery B by regenerative braking operation (power generation) by the motor MG2 can be appropriately executed according to the driving state of the vehicle.

That is, in the hybrid vehicle 100, the engine 110 controls its operation and stop regardless of the amount of accelerator operation by the driver. Specifically, engine 110 can be operated intermittently according to the vehicle running state (load, vehicle speed, etc.) and the state of charge of battery B. Accordingly, it is possible to significantly improve fuel consumption and exhaust gas by operating the engine 110 and the second motor MG2 individually or in cooperation as the vehicle driving force source.
As described above, the engine 110 is intermittently driven even during traveling, and the stop control is frequently performed. Here, engine stop control in the hybrid vehicle 100 will be described.

In hybrid vehicle 100, when engine 110 is stopped, fuel injection in engine 110 is stopped. Further, similarly to the processing of Japanese Patent Laid-Open No. 10-306739, engine stop control is executed in which the first motor MG1 applies torque in the direction opposite to the rotation direction (forward rotation) of the engine 110. As a result, when the engine is stopped, the engine speed can be quickly reduced and the resonance region can be quickly passed, so that the occurrence of torsional resonance can be prevented. At this time, the torque command value Tqcom (1) of the first motor MG1 is set to a predetermined value (negative value) at which a desired deceleration obtained experimentally in advance is obtained. The torque command value at this time may be set as a fixed value, or may be set to be variable according to the engine speed at that time.
In such engine stop control, generation of negative torque by the first motor MG1 generates generated power corresponding to torque × rotation speed. This generated power is converted into DC power by the first inverter 20 and supplied to the power supply line 7. Hereinafter, in the present embodiment, the power consumption is indicated by a positive value, and the generated power is indicated by a negative value.

Next, the smoothing capacitor protection control process among the processes of the drive control device 50 will be described with reference to FIG. This process operates at a predetermined sampling period.
First, in step S10, it is determined whether or not the driving wheel 150 is accelerating slip more than a predetermined value. If it is determined that acceleration slip has occurred, the process proceeds to step S20. If it is determined that the acceleration slip has not occurred, it returns as it is. This processing may be a part of other processing such as ABS control.
Whether or not it is an acceleration slip is determined as an acceleration slip when the vehicle speed difference is greater than or equal to a predetermined speed based on, for example, the vehicle speed difference between the vehicle speed of the driving wheel 150 and the vehicle speed of the driven wheel.
In step S20, the process of the smoothing capacitor protection control unit 70 is performed.
Next, in step S30, the processing of the phase advance processing unit 71 is executed.
Then return.

Next, the processing of the smoothing capacitor protection control unit 70 will be described with reference to the processing block shown in FIG.
The smoothing capacitor protection control unit 70 includes a boost voltage target value limit processing unit 70A, a first boost voltage target value limit correction coefficient calculation unit 70B, a second boost voltage target value limit correction coefficient calculation unit 70C, and a third boost voltage target value limit. A correction coefficient calculation unit 70D, a multiplication unit 70E, an addition / subtraction unit 70H, and an IGBT carrier frequency limiting unit 70G are provided.

The boost voltage target value restriction processing unit 70A receives the boost voltage target value Vbo ^* and the battery temperature Tb. Then, using the map as shown in FIG. 4, a coefficient K1 (<1) is calculated according to the battery temperature Tb. That is, the coefficient K1 becomes higher as the battery temperature Tb is lower below the predetermined threshold. For example, when the battery temperature Tb is equal to or higher than zero ° C. (predetermined threshold), K1 = 0, and the coefficient K1 increases as the battery temperature Tb becomes lower than zero ° C. (predetermined threshold). The predetermined threshold need not be zero degrees Celsius.
Then, the boost voltage limit value ΔVdown is calculated based on the following equation.
ΔVdown = K1 × Vbo ^*

Next, the first boosted voltage target value limit correction coefficient calculation unit 70B will be described.
The first boosted voltage target value limit correction coefficient calculation unit 70B receives the inverter IGBT temperature, converter IGBT temperature, and smoothing capacitor temperature. Here, the inverter IGBT temperature is, for example, the inverter IGBT temperature of the second inverter. As the inverter IGBT temperature, the higher one of the inverter IGBT temperatures among the first and second inverters 20 and 30 may be adopted. The same applies to other processes.

Correction coefficients K2a, K2b, and K2c are calculated for each input temperature using the maps shown in FIGS. Next, the maximum value among the correction coefficients K2a, K2b, and K2c is set as a coefficient a. The minimum value among the correction coefficients K2a, K2b, and K2c is set as a coefficient c. Alternatively, the correction coefficients a and c may be calculated using a map as shown in FIG. 5 based on the input maximum temperature and minimum temperature. Here, the maps shown in FIGS. 5 to 7 have a larger value when the temperature is higher than when the temperature is low. In FIG. 3, α is less than 1.
The first boosted voltage target value limit correction coefficient calculating unit 70B outputs the calculated coefficient a to the third boosted voltage target value limit correction coefficient calculating unit 70D. Also, the first boosted voltage target value limit correction coefficient calculation unit 70B outputs the calculated coefficient c to the IGBT carrier frequency limit unit 70G.

Next, the second boosted voltage target value limit correction coefficient calculation unit 70C will be described.
Second boosted voltage target value limit correction coefficient calculation unit 70C receives the motor temperature. Then, the correction coefficient b is calculated using the map shown in FIG. The map shown in FIG. 8 has a larger value when the temperature is higher than when the temperature is low.
The third boosted voltage target value limit correction coefficient calculation unit 70D performs a selection high of the correction coefficients a and b, and outputs the larger coefficient d to the multiplication unit 70E.

The multiplier 70E multiplies the boost voltage limit value ΔVdown by the output value d of the third boost voltage target value limit correction coefficient calculator 70D to correct the boost voltage limit value ΔVdown.
ΔVdown ← d × ΔVdown
As a result, the boost voltage limit value ΔVdown is decreased when the inverter IGBT temperature, the motor temperature, or the like is low.
The subtraction unit 70H, limits the boost voltage target value Vbo ^* by subtracting the boost voltage limit value ΔVdown corrected from the boosted voltage target value Vbo ^*.
Vbo_limit ^* = Vbo ^* −ΔVdown
Further, the IGBT carrier frequency limiting unit 70G subtracts the coefficient c from the IGBT carrier frequency target value to limit the IGBT carrier frequency.

Next, processing of the phase advance processing unit 71 will be described.
The phase advance processing unit 71 includes a phase advance and a loss map (not shown) that can be consumed by the first motor MG1 and the second motor MG2.
The surplus power generated by the acceleration slip of the drive wheel 150 is calculated based on the slip amount.
Then, referring to the respective loss maps of the first motor MG1 and the second motor MG2 from the calculated surplus power, the phase advance amount of each of the first motor MG1 and the second motor MG2 to the −d axis is calculated. To do. Then, the calculated phase advance amount is output to the vector controllers 72 and 73 of the first and second inverters in the processing of the drive control device 50.

  Here, the vector control units 72 and 73 of the first and second inverters respectively set the current command value for the torque command value to the motors MG1 and MG2 to be controlled to be the normal efficiency optimum and the maximum torque operating point. Vector control by carrier variable PWM control, overmodulation control, rectangular wave control, etc. is performed. However, when the phase advance amount is acquired from the phase advance processing unit 71, the current command value is corrected so that the phase is advanced to the −d axis side by the phase advance amount.

Further, the vector controllers 72 and 73 of the first and second inverters 20 and 30 are controlled by the smoothing capacitor protection controller 70 using the IGBT carrier frequency target value after limitation.
Here, the allowable input power Pin of the battery B changes according to the battery state (SOC and / or battery temperature, etc.). In particular, when the battery temperature Tb is low, the allowable input power Pin decreases due to an increase in internal resistance or the like. The allowable input power Pin is obtained from a separately provided control device for battery control, or a map with the battery temperature Tb, SOC, etc. as an argument is stored in the drive control device 50, and allowed by referring to this map. The input power Pin can be obtained.

Further, the generated power Pg of the first motor MG1 by the engine stop control can be expressed by the following equation. At this time, the current rotation speed Nmt1 and MG1 torque command value Tqcom (1) of the first motor MG1 are used.
Pg = Nmt1 · Tqcom (1)
Here, since the torque command value Tqcom (1) <0 during engine stop control, the generated power Pg is a negative value (Pg <0).

  The total power consumption Pttl, which is the power consumption in the path through which the power generated by the first motor MG1 is input to the battery B, is the loss power Lmg1 in the first motor MG1, the execution power Pmg2 and the loss power Lmg2 in the second motor MG2. Calculated as the sum of power loss Liv1 and Liv2 in the first and second inverters 20 and 30, power loss Lcv in the buck-boost converter 15, accumulated power change ΔPc in the smoothing capacitor C0, and auxiliary machine power consumption Pa in the load 170 I can do it.

Here, the power loss generated in each switching element of the first and second inverters 20 and 30 will be described.
The switching operation in each switching element of the first and second inverters 20 and 30 is basically set according to pulse width modulation control (PWM control). Specifically, in the PWM control, on / off of the switching element in each phase arm of the first and second inverters 20 and 30 is controlled based on a voltage comparison between a predetermined carrier wave and a voltage command wave. Here, the carrier wave is generally a triangular wave or a sawtooth wave having a predetermined frequency. The voltage command wave indicates a voltage (AC voltage) applied to the motor for generating each phase current necessary for operating the motor MG according to the torque command value Tqcom. The switching elements constituting the same arm are turned on and off when the carrier wave is higher than the voltage command wave and vice versa. When the switching element is turned on, the collector-emitter voltage vce = 0, while the collector-emitter current ice is generated. On the other hand, when the switching element is turned off, the collector-emitter current ice = 0, while the collector-emitter voltage vce = VH. Here, when the switching element is turned on / off, during the period until it is completely turned on or off, that is, during the period until the collector-emitter voltage vce = 0 or the collector-emitter current ice = 0, the collector-emitter A switching loss Ploss (Ploss = vce · ice) corresponding to the product of the inter-voltage vce and the collector-emitter current ice occurs. Due to the occurrence of the switching loss Ploss, the switching element generates heat and its temperature rises.

  Here, the amplitude of the collector-emitter voltage vce corresponds to the system voltage VH, and the collector-emitter current ice is a current corresponding to the supply current to the motor MG. Therefore, at the same torque output, that is, under the same torque command value, the switching loss Ploss increases as the system voltage VH increases. Then, the greater the number of switching operations per unit time, that is, the higher the carrier wave frequency is set and the higher the switching frequency, the greater the power loss associated with the switching operation. Therefore, the power loss accompanying the switching operation is a value dependent on the torque or output of the motor, the DC voltage to be switched (system voltage VH), and the switching frequency determined by the carrier frequency.

Even during the ON period of the switching element, although it is smaller than the switching loss Ploss, loss power is generated according to the product of the ON resistance of the switching element and the square of the current ice. The power loss due to this on-resistance can be estimated based on a torque command value that determines the current supplied to the motor MG.
By referring to the predetermined map, based on the output (rotation speed × torque) or torque (torque command value Tqcom (1)) of the first motor MG1 and the system frequency VH and the carrier frequency fiv1 used in the first inverter 20, The loss power Liv1 in one inverter 20 can be estimated. The map is configured in advance so as to obtain an estimated value of the loss power Liv1 with the rotation speed, torque (torque command value Tqcom (1)), system voltage VH, and carrier frequency fiv1 of the first motor MG1 as arguments.

  Similarly, by referring to a predetermined map, the output (rotation speed × torque) or torque (torque command value Tqcom (2)) of the second motor MG2 and the carrier frequency fiv2 used in the system voltage VH and the second inverter 30 are set. Based on this, the loss power Liv2 in the second inverter 30 can be estimated. The map is configured in advance so as to obtain an estimated value of the loss power Liv2 using the rotation speed, torque (torque command value Tqcom (2)), system voltage VH, and carrier frequency fiv2 of the second motor MG2.

  Next, the power consumption in the buck-boost converter 15 is mainly the sum of the power loss in the switching elements Q1 and Q2 and the power loss in the reactor L1. In these, as the converter passing current (that is, the battery current Ib) is smaller and the system voltage VH is lower, the power loss becomes smaller. Further, the power loss in the switching elements Q1 and Q2 increases in proportion to the number of switchings per unit time, that is, the increase in the carrier frequency fcv.

  Therefore, by referring to the predetermined map, the power loss Lcv in the buck-boost converter 15 can be estimated based on the system voltage VH, the battery current Ib, and the carrier frequency fcv used in the buck-boost converter 15. The map is configured in advance so as to obtain an estimated value of the loss power Lcv using the system voltage VH, the battery current Ib, and the carrier frequency fcv as arguments.

  In the smoothing capacitor C0, the voltage difference ΔVH between the current system voltage VH and the voltage command value VHref affects the input power to the battery B. That is, when VHref> VH, the electric power according to this voltage difference among the electric power generated by the first motor MG1 is accumulated in the smoothing capacitor C0. On the other hand, when VH> VHref, power according to this voltage difference is discharged from the smoothing capacitor and added to the input power to battery B.

  Therefore, the stored power change ΔPc in the smoothing capacitor C0 can be estimated based on the system voltage VH and the voltage command value VHref by referring to a predetermined map. The map is configured in advance so as to obtain the stored power change ΔPc using the system voltage VH and the voltage command value VHref as arguments. Here, the accumulated power change ΔPc is obtained by ΔPc = C0 · ΔVH2 / 2 (where ΔVH = VHref−VH).

Furthermore, by referring to a predetermined map, the auxiliary machine power consumption Pa can be estimated based on the operating state (on / off setting, operating condition setting) of the load (auxiliary machine) 170. The above map is pre-configured so as to obtain an estimated value of the auxiliary machine power consumption Pa using the operation state of the auxiliary machine load (for example, a heater for heating hot water, a temperature control device (air conditioner), a blower motor, a heater for defroster, etc.) as an argument. Is done.
The input power to the battery B can be estimated from the sum of the estimated generated power Pg and the total power consumption Pttl estimated in step S120. That is, the estimated input power Pb can be expressed by the following equation.
Pb = Pg + Pttl

(Operation / Action)
The drive wheel is driven by a sudden decrease in the rotational speed of the drive wheel 150 due to the grip from a slip state of the vehicle drive wheel 150 that occurs when traveling on a low μ road or an irregular road, or by a sudden limit of the drive torque during traction control operation that suppresses slip. The output of the second motor MG2 connected to 150 suddenly decreases. In this case, the second motor MG2 cannot consume all the generated power of the first motor MG1 that extracts the engine output as drive output power, and the surplus is input to the battery B.

  Here, when the temperature of the battery B is low, the regenerative power acceptance amount of the battery B is small. For this reason, when the transition from the slip state to the grip state or the traction control operation is performed, the battery B may not receive the surplus power. In this case, since the capacitors of the inverter and boost converter sandwiched between the first motor MG1 and the second motor MG2 and the battery B are received, the capacitor voltage rises excessively, and the capacitor and the switching element are in an overvoltage withstand state. The drivability may be impaired.

As means for solving this, there are the following methods (a) to (c).
(A) The battery B is warmed to increase the acceptability of regenerative power.
In particular,
-Warm from the outside by engine exhaust heat, A / C, etc.-Energy is taken in and out of the battery B, inverter and converter, and the first motor MG1 and second motor MG2 within a range that has little influence on the driving force. Heat from the inside due to heat generated by the loss of the internal resistance of B.

(B) In order to suppress the generated power of the first motor MG1 and the power running power of the second motor MG2 when the battery temperature is low, the torque command values of the first motor MG1 and the second motor MG2 are limited to suppress the absolute value of surplus power.
(C) The engine torque is limited, the generated power of the first motor MG1 is suppressed, and the absolute value of surplus power is suppressed.
However, the countermeasures (a) to (c) have the following rebound.
That is, in (a), there is a loss of power balance and a delay in warm-up time. In (b) and (c), the driving force is suppressed, and the power performance may be greatly reduced.

In this embodiment, a smoothing capacitor is used as a buffer. And when using together with said (a)-(c), it becomes possible to suppress the said bounce.
In other words, when the battery temperature Tb is low and the amount of regenerative power received is small, the boosted voltage is limited to a low value when the drive wheel 150 slips. As a result, even if the power overflowed by the power balance deviation between the first motor MG1 and the second motor MG2 that occurs during the transition between the slip state and the grip state exceeds the regenerative power acceptance amount of the battery B, the boost voltage is suppressed. Therefore, the electric power that the smoothing capacitor can primarily receive within the withstand voltage increases.

  Moreover, by synchronizing and advancing the current phase of at least one of the inverters 20 and 30, the power generation efficiency of the first motor MG1 and the efficiency of the second motor MG2 are deteriorated, and surplus power is absorbed by the deterioration. The amount of power that the capacitor accepts temporarily decreases by the amount of deterioration, and the remaining power can be used to relax the output limits of the first motor MG1 and the second motor MG2. As a result, drivability is improved.

Here, in the said embodiment, the case where it implements when it determines with the process of the smoothing capacitor protection control part 70 as shown in FIG. 3 having carried out the acceleration slip of the driving wheel 150 was illustrated. Instead of this, the processing of the smoothing capacitor protection control unit 70 may be always performed to prepare for acceleration slip.
In addition, among the processes of the smoothing capacitor protection control unit 70, the boost voltage target value limit processing unit 70A is always executed, and the first to third boost voltage target value limit correction coefficient calculation units 70B to 70D are executed at the time of acceleration slip. You may make it do.

Moreover, the hybrid vehicle which this embodiment makes object is not limited to the said structure. As long as it is a hybrid vehicle having a boosting function, it may be a two-motor parallel type, a two-motor series parallel type, a two-motor series hybrid, or a plug-in hybrid type.
Further, the control of the boosting function of the converter is not limited to the above configuration. For example, control in voltage F / B control + F / F compensation or control in which current F / B control + F / F compensation is added to voltage F / B control + F / F compensation can be exemplified.
Here, the smoothing capacitor protection control unit 70 constitutes boosted voltage control means. The phase advance processing unit 71 constitutes a phase advance processing means. Step S10 constitutes slip detection means.

(Effect of this embodiment)
(1) The boosted voltage limiting means limits the boosted voltage target value Vbo ^* of the converter to be lower when the temperature of the battery B is lower than a predetermined value compared to when the temperature of the battery B is high.
Even if the surplus power due to the power balance deviation between the first motor MG1 and the second motor MG2 exceeds the regenerative power acceptance amount of the battery B, the boost voltage is suppressed, so that the smoothing capacitor is within the withstand voltage. The power that can be temporarily received increases.
As a result, it is possible to reduce the occurrence of excessive capacitor voltage when the battery temperature is low.
For example, even if the power overflowed by the power balance deviation between the first motor MG1 and the second motor MG2 that occurs at the time of transition between slip and grip exceeds the regenerative power acceptance amount of the battery B, the boost voltage is suppressed. Therefore, the electric power that the smoothing capacitor can primarily receive within the withstand voltage increases.

(2) The boost voltage limiting means corrects the limit amount of the boost voltage target value Vbo ^* according to at least one of the motor temperature, the inverter and converter temperature, and the capacitor temperature, compared with a case where the temperature is high. If it is low, the limit amount is corrected to be small.
When the motor temperature or the like is low, there is a margin for increasing the loss due to the motor temperature or the like. For this reason, the restriction | limiting of the said boost voltage target value can be eased.

(3) The slip detection means detects the slip of the drive wheel 150. If the phase advance processing means determines that the drive wheel 150 has slipped based on the detection by the slip detection means, the current command value for the torque command value for at least one of the second motor MG2 and the first motor MG1 is − Advance the phase toward the d-axis.
This makes it possible to absorb surplus due to heat generation due to increased loss.
That is, by advancing the current phase, the power generation efficiency of the first motor MG1 and the efficiency of the second motor MG2 are deteriorated, and surplus power is absorbed by the deterioration. The power that the capacitor temporarily accepts is reduced by the deterioration. Then, the remaining power can be used for relaxing the output restriction of the first and second motors MG1 and MG2, which leads to improved drivability.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. In addition, about the structure similar to said each embodiment, the same code | symbol is attached | subjected and demonstrated.
The basic configuration of this embodiment is the same as that of the first embodiment.
However, the configuration of the smoothing capacitor protection controller 70 is different as shown in FIG.
Next, processing of the smoothing capacitor protection control unit 70 of the present embodiment will be described with reference to FIG.
The processing of the smoothing capacitor protection control unit 70 includes a boost voltage target value limit processing unit 70A, a first boost voltage target value limit correction coefficient calculation unit 70B, a second boost voltage target value limit correction coefficient calculation unit 70C, and a third boost voltage target. A value limit correction coefficient calculation unit 70D, a drive request driving force limit unit 70H, a multiplication unit 70E, an IGBT carrier frequency correction coefficient calculation unit 70K, and an IGBT carrier frequency limit unit 70G are provided.

The processing of the boost voltage target value restriction processing unit 70A is the same as that in the first embodiment.
The first boosted voltage target value limit correction coefficient calculation unit 70B is basically the same as that in the first embodiment. However, in the first boosted voltage target value limit correction coefficient calculation unit 70B of the present embodiment, only the coefficient a is obtained. Then, the first boosted voltage target value limit correction coefficient calculating unit 70B outputs the calculated coefficient a to the third boosted voltage target value limit correction coefficient calculating unit 70D.

Next, the second boosted voltage target value limit correction coefficient calculation unit 70C is the same as that in the first embodiment.
The third boosted voltage target value limit correction coefficient calculation unit 70D performs a select row of the correction coefficients a and b, and outputs the smaller coefficient e to the multiplication unit 70E and the IGBT carrier frequency correction coefficient calculation unit 70K.
The requested drive force limiter 70H inputs the requested drive force target value Power ^* . Further, the coefficient K4 is calculated based on the battery temperature Tb using the map shown in FIG. Then, the limit value Plimit ^* is calculated by multiplying the input target value Power ^* of the requested driving force by the coefficient K4. The coefficient K4 becomes a smaller value as the temperature is lower than a predetermined temperature (zero in FIG. 10).

The multiplication unit 70E multiplies the limit value Plimit ^{* by} the coefficient e from the third boosted voltage target value limit correction coefficient calculation unit 70D, thereby correcting the limit value Plimit ^* of the drive request driving force, and Plimit_adj ^*. And
Then, the integrated control device 60 uses the limit value Plimit_adj ^* value from the target value Power ^* of the required driving force as the target value Power ^* of the required driving force.
Power ^* ← Power ^* −Limit_adj ^*

Further, the IGBT carrier frequency correction coefficient calculation unit 70K receives the coefficient e from the third boosted voltage target value limit correction coefficient calculation unit 70D and the increase rate of the d-axis current.
A limiting coefficient K5 is obtained from the input d-axis current increase rate using the map shown in FIG. The larger one of the limiting coefficient K5 and the coefficient e from the third boosted voltage target value limiting correction coefficient calculating unit 70D is set as a coefficient c. Then, the coefficient c is output to the IGBT carrier frequency limiting unit 70G.
Further, the IGBT carrier frequency limiting unit 70G subtracts the coefficient c from the IGBT carrier frequency target value to limit the IGBT carrier frequency.

(Operation, action)
When the battery temperature is low, the target value Power ^* of the required driving force is limited. This suppresses the boosted voltage.
Further, when the increase rate of the d-axis current is large or when the motor temperature is high, the IGBT carrier frequency is limited. This cancels out the inverter heat generation.
From the inverter temperature, the allowable value of the motor and inverter loss that increases by advancing the current phase is calculated, and the capacitor capacity is effectively utilized by correcting the limit of the boost voltage and torque command value according to the allowable amount. However, overvoltage can be avoided.

Here, in the said embodiment, the case where it implements when the process of the smoothing capacitor protection control part 70 as shown in FIG. 9 determines with the driving wheel 150 carrying out the acceleration slip was illustrated. Instead of this, a smoothing capacitor protection control process may be performed at all times to prepare for an acceleration slip.
Of the smoothing capacitor protection control processing, only the boosted voltage target value restriction processing unit 70A may be always executed, and the other processing may be executed at the time of acceleration slip.
Moreover, in the said embodiment, the case of the hybrid vehicle provided with the internal combustion engine was illustrated. Instead, it can be applied to so-called plug-in hybrid vehicles that have an internal combustion engine, an electric vehicle, a fuel cell vehicle, and an internal combustion engine that can be charged from an external power source. it can.

(Effect of embodiment)
(1) When the temperature of the battery B is lower than a predetermined value, the target value of the required driving force is limited to be lower than that when the temperature of the battery B is high, and the target value of the required driving force is limited to the inverter temperature And when the temperature of at least one of the motor temperatures is low, the temperature is reduced.
When the battery temperature is low, the target value Power ^* of the required driving force is limited. As a result, the boosted voltage is suppressed, and the power that the smoothing capacitor can primarily receive within the withstand voltage increases.
However, when at least one of the inverter temperature and the motor temperature is low, the restriction on the target value Power ^* of the required driving force can be relaxed by reducing the restriction.

(2) The carrier frequency of the switching element of at least one of the first inverter and the second inverter is limited according to the increasing rate of the d-axis current.
By limiting the inverter IGBT switching carrier frequency to be low, the loss of the inverter itself can be reduced.
(3) The limit amount of the carrier frequency is made smaller when the temperature of at least one of the motor temperature and the inverter temperature is lower than when the temperature is high.
When the inverter temperature or the like is high, the allowable value of the loss increased inverter heat resistance by advancing the current phase of motor control is limited. In this case, the inverter IGBT switching carrier frequency is lowered to reduce the loss of the inverter itself.

B Battery C0 Smoothing capacitor C1 Smoothing capacitor DVG DC voltage generator MG1 First motor MG2 Second motor Tb Battery temperature Vbo ^* Boost voltage target value 15 Buck-boost converter 20 First inverter 30 Second inverter 50 Drive controller 60 Integrated controller 61 Engine Controller 62 Accelerator Pedal Sensor 63 Brake Pedal Sensor 64 Vehicle Speed Sensor 70 Smoothing Capacitor Protection Control Unit 70A Boost Voltage Target Value Limit Processing Unit 70B Boost Voltage Target Value Limit Correction Coefficient Calculation Unit 70C Boost Voltage Target Value Limit Correction Coefficient Calculation Unit 70D Boost Voltage target value limit correction coefficient calculation unit 70E Multiplication unit 70G Carrier frequency limit unit 70H Addition / subtraction unit 70H Drive required drive force limit unit 70K Carrier frequency correction coefficient calculation unit 71 Phase advance processing unit 72 First vector control unit 73 Third vector Control unit 110 engine 150 driving wheel

Claims (8)

A motor capable of driving the drive wheel and regenerating by the drive wheel;
A battery, an inverter that electrically connects the battery and the motor, a converter and a smoothing capacitor having a boosting function interposed between the inverter and the battery,
Boost voltage limiting means for limiting the boost voltage target value of the converter when the battery temperature is lower than a predetermined value compared to when the battery temperature is high;
A vehicle drive control device comprising: An internal combustion engine for driving the drive wheels; a first motor capable of generating electric power by rotation of the internal combustion engine; a second motor capable of driving the drive wheels and regenerating by the drive wheels;
A battery, a first inverter that electrically connects the battery and the first motor, a second inverter that electrically connects the battery and the second motor, and between the first inverter, the second inverter, and the battery A converter and a smoothing capacitor having a step-up function to be interposed;
Boost voltage limiting means for limiting the boost voltage target value of the converter when the battery temperature is lower than a predetermined value compared to when the battery temperature is high;
A vehicle drive control device comprising:   The boost voltage limiting means corrects the limit amount of the boost voltage target value according to at least one of a motor temperature, an inverter and converter temperature, and a capacitor temperature, and when the temperature is lower than the higher temperature The vehicle drive control device according to claim 2, wherein correction is performed so that the limit amount is reduced. The inverter is controlled by vector control, and
Slip detecting means for detecting slip of the drive wheel;
When it is determined that the drive wheel has slipped based on the detection of the slip detection means, the phase advance is made to advance the phase of the current command value for the torque command value for at least one of the second motor and the first motor to the -d axis side. The vehicle drive control device according to claim 3, further comprising a processing unit. In a vehicle drive control device that obtains a target value of a required driving force based on an accelerator opening, and drives and controls the internal combustion engine and the second motor with a command value based on the target value of the required driving force.
When the target temperature of the required driving force is lower than the predetermined value when the temperature of the battery is lower than the predetermined value,
5. The target value of the required driving force is made smaller when the temperature of at least one of the inverter temperature and the motor temperature is lower than when the temperature is high. A drive control device for a vehicle according to any one of the preceding claims.   6. The carrier frequency of at least one inverter switching element of the first inverter and the second inverter is limited according to an increase rate of the d-axis current, and is described in any one of claims 2 to 5. Vehicle drive control device.   7. The vehicle drive control device according to claim 6, wherein the limit amount of the carrier frequency is reduced when the temperature of at least one of the motor temperature and the inverter temperature is lower than when the temperature is high.   A motor capable of driving the drive wheel and regenerating by the drive wheel is provided, and the motor is electrically connected to the battery via a converter having a boost function, a smoothing capacitor, and an inverter, and the boost voltage target value of the converter is determined. When the battery temperature is lower than a predetermined value, the vehicle is controlled to be lower than the battery temperature is high.

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