JP2019193558A - Electric vehicle - Google Patents

Abstract

To improve acceleration responsiveness to an accelerator operation.SOLUTION: In an electric vehicle including a first motor that outputs torque to one of front wheels and rear wheels and a second motor that outputs torque to the other wheels, when the torque of a negative value is required as required torque for travel, the second motor is controlled so as to output torque with the lowest torque of a positive value as the lowest limit, and the first motor is controlled to travel by the required torque. With this, the torque of the second motor does not require gradual change processing for suppressing a torque shock that may occur due to gear play, and the torque output from the second motor can be quickly raised. As a result, acceleration responsiveness to an accelerator operation can be improved.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an electric vehicle including a first motor capable of outputting a driving force to one of a front wheel and a rear wheel and a second motor capable of outputting a driving force to the other wheel.

  Conventionally, in this type of electric vehicle, when the required torque changes from deceleration torque (negative torque) to acceleration torque (positive torque), the required torque falls within a predetermined torque range including a value of zero. In the meantime, there has been proposed one in which the required torque is changed by a gradual change process (see, for example, Patent Document 1). In this electric vehicle, the torque shock that can be caused by the play of the differential gear can be suppressed by gently changing the torque when the sign of the required torque changes.

JP 2012-196082 A

  However, in the above-described electric vehicle, if the torque is gradually changed by the gradual change process, the driving force rises with respect to the accelerator operation. In an electric vehicle including a motor as a power source for traveling, there is generally a high expectation for acceleration response to an accelerator operation. Therefore, if the driving force is delayed, the driver feels uncomfortable.

  The electric vehicle of the present invention is mainly intended to improve acceleration response to an accelerator operation.

  The electric vehicle of the present invention employs the following means in order to achieve the main object described above.

The electric vehicle of the present invention is
A first motor capable of outputting a driving force to one of the front wheels and the rear wheels;
A second motor capable of outputting a driving force to the other wheel of the front wheel and the rear wheel;
A power storage device capable of exchanging electric power with the first motor and the second motor;
A control device for controlling the first motor and the second motor to travel with a required driving force required for traveling;
An electric vehicle comprising:
When a negative driving force is required as the required driving force, the control device controls the second motor with a predetermined positive driving force as a lower limit, and controls the first motor to travel with the required driving force. Execute driving force offset control to control,
This is the gist.

  The electric vehicle according to the present invention includes a first motor capable of outputting a driving force to one of the front wheels and the rear wheels, and a second motor capable of outputting a driving force to the other wheel. In this electric vehicle, when a negative driving force (braking force) is required as a required driving force, the second motor is controlled with a predetermined positive driving force as a lower limit, and the first motor is driven to travel with the required braking force. The driving force offset control to be controlled is executed. As a result, when the required driving force changes from a negative driving force to a positive driving force, it is not necessary to perform a gradual change process for loosening the gear between the second motor and the wheels. The driving force to be output can be quickly started up. As a result, acceleration response to accelerator operation can be improved. Of course, the negative driving force (braking force) output from the first motor can cope with the negative required driving force.

  In such an electric vehicle of the present invention, the control device may not execute the driving force offset control when an abnormality occurs in the system. In this way, it is possible to prevent the vehicle from running with an unexpected driving force when an abnormality occurs in the system.

  The electric vehicle of the present invention includes an engine capable of outputting power to the one wheel, and travels by switching between a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode as a travel mode, The control device may not execute the driving force offset control in the CS mode. When the required driving force is a negative driving force, that is, a braking force, when all the required braking force is output from the first motor, the required braking force is distributed to the first motor and the second motor. Compared with the case of outputting, the loss of the entire system is increased due to the non-linearity of the motor loss. Therefore, in the CD mode and the CS mode, the driving force offset control is executed in the CD mode in which the drivability (acceleration responsiveness) is given priority over the maintenance of the power storage ratio of the power storage device, and the maintenance of the power storage ratio is prioritized in the CS mode. By not executing the driving force offset control, it is possible to execute control suitable for each mode.

  Furthermore, in the electric vehicle according to the present invention, when the maximum charging power that can be charged by the power storage device is less than a predetermined power, when the temperature of the second motor is higher than a predetermined temperature, or when the vehicle speed is lower than a predetermined vehicle speed, the driving force The offset control may not be executed.

  Further, in the electric vehicle of the present invention, when acceleration traveling is requested during deceleration traveling by the driving force offset control, vibration that may be caused by an increase in the driving force of the first motor and an increase in the driving force of the second motor. The first motor and the second motor may be controlled so as to start increasing the driving force at different timings so that the vibrations that can be caused by the above are in opposite phases. If it carries out like this, the vibration which may be generated by the increase in the driving force from the 1st motor and the vibration which may be generated by the increase in the driving force from the 2nd motor can be mutually canceled, and an acceleration shock can be suppressed.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as an Example of this invention. 5 is a flowchart showing an example of a deceleration control routine executed by an HVECU 70. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is a characteristic view which shows an example of the relationship between the output torque of a motor, and the loss (loss) of a motor. 7 is a flowchart showing an example of a routine for determining whether or not driving force offset control is executed by an HVECU. 3 is a flowchart showing an example of an acceleration control routine executed by an HVECU 70. 4 is a time chart showing an example of a time change of an accelerator opening Acc, a total driving force, a motor MG2 torque Tm2, a motor MG3 torque Tm3, and a timer counter C. It is a block diagram which shows the outline of a structure of the electric vehicle 120 of a modification. It is a block diagram which shows the outline of a structure of the electric vehicle 220 of a modification.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1, MG2, and MG3, inverters 41, 42, and 43, a battery 50, a charger 60, and a hybrid electronic control. A unit (hereinafter referred to as “HVECU”) 70.

  The engine 22 is configured as an internal combustion engine that outputs power using gasoline or light oil as a fuel. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as “engine ECU”) 24.

  Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The engine ECU 24 receives signals from various sensors necessary for controlling the operation of the engine 22, for example, a crank angle θcr from a crank position sensor 23 that detects the rotational position of the crankshaft 26 of the engine 22 via an input port. Have been entered. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via an output port. The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotational speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor 23.

  The planetary gear 30 is configured as a single pinion type planetary gear mechanism. The sun gear of planetary gear 30 is connected to the rotor of motor MG1. A drive shaft 36F connected to the front wheels 38a and 38b via a differential gear 37F is connected to the ring gear of the planetary gear 30. A crankshaft 26 of the engine 22 is connected to the carrier of the planetary gear 30 via a damper 28.

  The motor MG1 is configured as, for example, a synchronous generator motor, and the rotor is connected to the sun gear of the planetary gear 30 as described above. The motor MG2 is configured as a synchronous generator motor, for example, and the rotor is connected to the drive shaft 36F. The motor MG3 is configured as, for example, a synchronous generator motor, and a rotor is connected to a drive shaft 36R that is coupled to rear wheels 38c and 38d via a differential gear 37R. Inverters 41, 42, and 43 are connected to battery 50 through power line 54. The motors MG1, MG2, and MG3 are rotationally driven by switching control of a plurality of switching elements (not shown) of the inverters 41, 42, and 43 by a motor electronic control unit (hereinafter referred to as “motor ECU”) 40. .

Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The motor ECU 40 includes signals from various sensors necessary for driving and controlling the motors MG1, MG2, and MG3, for example, rotational position detection sensors 44, 45, and 46 that detect rotational positions of the rotors of the motors MG1, MG2, and MG3. , And the motor temperature tm2 from the temperature sensor 47 that detects the temperature of the motor MG2 are input via the input port. From the motor ECU 40, switching control signals to a plurality of switching elements (not shown) of the inverters 41, 42, and 43 are output via an output port. The motor ECU 40 is connected to the HVECU 70 via a communication port. The motor ECU 40 includes a rotational position detection sensor 44.
, 45, 46, the rotational speeds Nm1, Nm2, Nm3 of the motors MG1, MG2, MG3 are calculated based on the rotational positions θm1, θm2, θm3 of the rotors of the motors MG1, MG2, MG3.

  The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery. As described above, the battery 50 is connected to the inverters 41 and 42 via the power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter referred to as “battery ECU”) 52.

  Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The battery ECU 52 is attached to signals from various sensors necessary for managing the battery 50, for example, the battery voltage Vb from the voltage sensor 51 a installed between the terminals of the battery 50, and the output terminal of the battery 50. The battery current Ib from the current sensor 51b, the battery temperature Tb from the temperature sensor 51c attached to the battery 50, and the like are input via the input port. The battery ECU 52 is connected to the HVECU 70 via a communication port. The battery ECU 52 calculates the storage ratio SOC based on the integrated value of the battery current Ib from the current sensor 51b. The storage ratio SOC is a ratio of the capacity of power that can be discharged from the battery 50 to the total capacity of the battery 50. Battery ECU 52 also calculates input / output limits Win and Wout as maximum values of power that can be charged / discharged from battery 50 based on calculated storage ratio SOC and battery temperature Tb from temperature sensor 51c.

  The charger 60 is connected to the power line 54. When the power plug 61 is connected to an external power source 69 such as a home power source or an industrial power source at a charging point such as a home or a charging station, the external power source 69 is connected. It is comprised so that the external charge which charges the battery 50 using the electric power from can be performed.

  Although not shown, the HVECU 70 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. Signals from various sensors are input to the HVECU 70 via input ports. Examples of the signal input to the HVECU 70 include an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator pedal that detects the depression amount of the accelerator pedal 83. Examples include the accelerator opening Acc from the position sensor 84 and the brake pedal position BP from the brake pedal position sensor 86 that detects the amount of depression of the brake pedal 85. Further, the vehicle speed V from the vehicle speed sensor 88, the switch signal SWC from the mode changeover switch 92, the connection switch 62 that is attached to the power plug 61 and determines whether the power plug 61 is connected to the external power supply 69 or not. A connection signal SWC can be cited. Various control signals such as a control signal to the charger 60 are output from the HVECU 70 via the output port. Further, as described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port.

In the electric vehicle 20 of the embodiment, as the shift position SP of the shift lever 81, a parking range (P range) used during parking, a reverse range (R range) for reverse travel, a neutral range (N range), and forward travel In addition to the normal drive range (D range), the setting of the driving force when the accelerator is on is the same as that of the D range, but the braking force applied to the vehicle when the accelerator is off during traveling is set to be larger than the D range. A sequential shift range (S range) having a brake range (B range), an upshift instruction range, and a downshift instruction range is prepared.

  In the electric vehicle 20 of the embodiment configured in this way, hybrid traveling (HV traveling) or electric traveling (EV traveling) is performed in a CD (Charge Depleting) mode or a CS (Charge Sustaining) mode. Here, the CD mode is a mode in which EV traveling is given priority over the CS mode. The CS mode is a mode in which HV traveling and EV traveling are used together so that the storage ratio SOC of the battery 50 is maintained at a predetermined target ratio. The HV traveling is a mode that travels with the operation of the engine 22. EV traveling is a mode in which the vehicle travels without the engine 22 being operated.

  In the embodiment, when the power plug 61 is connected to the external power supply 69 when the vehicle is stopped with the system off (system stopped) at a charging point such as a home or a charging station, the HVECU 70 receives power from the external power supply 69. Is used to control the charger 60 so that the battery 50 is charged. When the power storage ratio SOC of the battery 50 is larger than a threshold value Shv1 (for example, 45%, 50%, 55%, etc.) when the system is turned on (system activation), the power storage ratio SOC of the battery 50 is a threshold value Shv2 (for example, 25%). , 30%, 35%, etc.) or less), and in the CS mode until the system is turned off after the storage ratio SOC of the battery 50 reaches the threshold value Shv2. When the system is turned on and the storage ratio SOC of the battery 50 is less than or equal to the threshold value Shv1, the vehicle travels in the CS mode until the system is turned off. If the mode switch 92 is operated while traveling in the CD mode, the vehicle travels in the CS mode. If the mode switch 92 is traveled again while traveling in the CS mode by operating the mode switch 92, the vehicle travels in the CD mode.

  Next, the operation of the electric vehicle 20 of the embodiment configured as described above will be described. In particular, in the CD mode in which EV traveling is prioritized, an operation when the accelerator pedal is stepped back during traveling to decelerate traveling and an operation when the accelerator pedal is depressed again to accelerate traveling will be described. FIG. 2 is a flowchart showing an example of a deceleration control routine executed by the HVECU 70. This routine is repeatedly executed at predetermined time intervals (for example, every several msec or several tens of msec) when the accelerator pedal 83 is stepped back during driving to request deceleration driving.

When the deceleration control routine is executed, the HVECU 70 first inputs the accelerator opening Acc and the vehicle speed V (step S100), and sets the required torque Td * based on the input accelerator opening Acc and the vehicle speed V. (Step S110). The required torque Td * is set using a required torque setting map illustrated in FIG. As shown in the figure, the required torque Td * is set so as to increase as the accelerator opening Acc increases. However, when the accelerator opening Acc is 0% during traveling, a negative torque, that is, a braking force is set. Is done. Subsequently, a value obtained by multiplying the required torque Td * by the driving force distribution ratio k is set to the rear wheel side required torque Trreq as a torque to be output from the motor MG3, and the required torque Td * is set from the value 1 to the driving force distribution ratio. A value obtained by multiplying the value obtained by subtracting k is set as the front wheel side required torque Tfreq as the torque to be output from the motor MG2 (step S120). The driving force distribution ratio k is a distribution ratio to the rear wheels 38c and 38d in the embodiment. When k = 0, the driving force distribution ratio k is 100% for the front wheels 38a and 38b and 0% for the rear wheels 38c and 38d. When 1, the distribution is 0% to the front wheels 38a and 38b and 100% to the rear wheels 38c and 38d. Further, the driving force distribution ratio k is set, for example, such that the sum of losses of the motor MG2 and the motor MG3 is minimized. FIG. 4 is a characteristic diagram showing an example of the relationship between the motor output torque and the motor loss. In general, the loss of the motor increases as the output torque increases. Therefore, by distributing the torque to be output from the motor MG2 and the motor MG3 so that the sum of the loss of the motor MG2 and the loss of the motor MG3 is minimized, the loss of the entire system is minimized. Note that when the motor MG2 or the motor MG3 is subjected to drive restriction due to overheating or the like, the driving force distribution ratio k is set so that the sum of the losses of the motor MG2 and the motor MG3 is minimized within the range. Next, it is determined whether or not the driving force offset control flag F is a value 1 (step S130). Here, the driving force offset control flag F indicates whether or not execution of driving force offset control, which will be described later, is permitted. A value of 1 indicates that execution of driving force offset control is permitted, and a value of 0 indicates driving force. Indicates that execution of offset control is prohibited. If it is determined that the driving force offset control flag F is not the value 1 but the value 0, the driving force offset control is not executed. That is, the front wheel side required torque Tfreq is set to the front wheel side execution torque Tf * as it is, and the rear wheel side request torque Trreq is set to the rear wheel side execution torque Tr * as it is (step S140). Subsequently, a value 0 is set in the torque command Tm1 * of the motor MG1, a front wheel side execution torque Tf * is set in the torque command Tm2 * of the motor MG2, and a rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3. Is set (step S180). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S190), and this routine is finished. The motor ECU 40 that has received the torque commands Tm1 *, Tm2 *, Tm3 * switches the switching elements of the inverters 41, 42, 43 so that the motors MG1, MG2, MG3 are driven by the torque commands Tm1 *, Tm2 *, Tm3 *. Take control.

  On the other hand, when it is determined that the driving force offset control flag F is 1, the driving force offset control is executed. In the driving force offset control, first, it is determined whether or not the rear wheel side required torque Trreq is less than a lower limit torque Trmin that is a positive value torque slightly larger than 0 (step S150). If it is determined that the rear wheel side required torque Trreq is equal to or greater than the lower limit torque Trmin, the front wheel side required torque Tfreq is set to the front wheel side execution torque Tf * as it is, and the rear wheel side request torque Trreq is directly set to the rear wheel side execution torque Tr *. Set (step S140). On the other hand, if it is determined that the rear wheel side required torque Trreq is less than the lower limit torque Trmin, a lower limit guard process for setting the lower limit torque Trmin to the rear wheel side execution torque Tr * is performed (step S160), and the front wheel side execution torque Tf *. Is set by subtracting the rear wheel side execution torque Tr * from the required torque Td * (step S170). Subsequently, a value 0 is set in the torque command Tm1 * of the motor MG1, a front wheel side execution torque Tf * is set in the torque command Tm2 * of the motor MG2, and a rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3. Is set (step S180). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S190), and this routine is finished. The motor ECU 40 that has received the torque commands Tm1 *, Tm2 *, Tm3 * switches the switching elements of the inverters 41, 42, 43 so that the motors MG1, MG2, MG3 are driven by the torque commands Tm1 *, Tm2 *, Tm3 *. Take control. As described above, the driving force offset control controls the motor MG3 so that torque is output to the drive shaft 36R connected to the rear wheels 38c and 38d with the lower limit torque Trmin having a positive value slightly larger than 0 as the lower limit. At the same time, the motor MG2 is controlled so that the necessary braking force (required torque Td *) is output to the drive shaft 36F connected to the front wheels 38a, 38b. The reason for executing the driving force offset control will be described later.

  Next, a process for determining whether or not to execute the driving force offset control will be described. FIG. 5 is a flowchart illustrating an example of a determination routine for determining whether or not the driving force offset control is executed by the HVECU 70. This routine is repeatedly executed every predetermined time (for example, every several milliseconds or several tens of milliseconds).

  When the routine for determining whether to execute the driving force offset control is executed, the HVECU 70 first inputs the vehicle speed V, the shift position SP, the travel mode M, the motor temperature tm of the motor MG3, and the input limit Win of the battery 50 (step S200). ). Then, whether the system is normal (step S210), whether the driving mode M is the CD mode (step S220), whether the shift position SP is the D position (step S230), and the vehicle speed V is Whether the vehicle speed is less than the predetermined vehicle speed Vref (step S240), whether the input limit Win (negative power) is less than the predetermined power Wref (step S250), and whether the motor temperature tm3 is less than the predetermined temperature tref. No (step S260) and whether the required torque Td * is greater than the motor lower limit torque Tm2min of the motor MG2 (step S270). If any of the determinations in steps S210 to S270 is positive, it is determined that the situation is suitable for execution of the driving force offset control, and the driving force offset control is permitted so as to permit the driving force offset control. A value 1 is set in the flag F (step S280), and this routine is terminated. On the other hand, if a negative determination is made in any of the determinations in steps S210 to S270, it is determined that the situation is not suitable for execution of the driving force offset control, and the driving force offset control is prohibited. The value 0 is set to the force offset control flag F (step S290), and this routine is finished. Here, in the determination in step S210, for example, it is determined whether a communication abnormality has occurred between the HVECU 70 and the motor ECU 40, that is, the torque commands Tm1 *, Tm2 *, Tm3 * are normally transmitted from the HVECU 70 to the motor ECU 40. The determination of whether or not it has been performed is included. The determination in step S220 is intended to perform the driving force offset control only in the CD mode that prioritizes EV traveling and improves drivability. That is, in the driving force offset control, since all of the required torque Tr * (negative value torque) is handled only by the front wheels 38a, 38b (motor MG2 side), as shown in FIG. The overall system loss increases. For this reason, in the CS mode where priority is given to maintaining the storage ratio SOC of the battery 50 over drivability, the driving force offset control is not executed with emphasis on efficiency. The determination in step S240 is intended not to execute the driving force offset control in the vehicle speed region in which a positive value torque is set as the required torque Td * when the accelerator opening Acc is 0%. The predetermined vehicle speed Vref is set to the upper limit vehicle speed in the creep travel region, as shown in FIG. The determinations in steps S250 and S260 are intended not to execute the driving force offset control when the motor MG3 is subjected to torque limitation. The predetermined power Wref is a threshold value for determining whether charging of the battery 50 is restricted, and the predetermined temperature tref is a threshold value for determining overheating of the motor MG3. The determination in step S270 is to determine whether all of the required torque Td * (negative torque) can be output from the motor MG2. The motor lower limit torque Tm2min is, for example, a negative rated torque of the motor MG2.

  Next, the operation when the accelerator pedal 83 is depressed again during acceleration traveling by the driving force offset control and acceleration traveling is performed will be described. FIG. 6 is a flowchart showing an example of an acceleration control routine executed by the HVECU 70. This routine is repeatedly executed at predetermined time intervals (for example, every several milliseconds or several tens of milliseconds) when the accelerator pedal 83 is depressed and acceleration traveling is requested during deceleration traveling by the driving force offset control.

  When the acceleration control routine is executed, similar to steps S100 to S120 of the deceleration control routine, necessary data is input to set the required torque Td *, and the front wheel side required torque Tfreq and the rear wheel side required torque Trreq are set. Set (steps S300 to S320). Next, whether or not the front wheel side execution torque set last time (previous Tf *) is equal to or larger than a predetermined negative torque (−Tref) slightly smaller than the value 0 (step S330), and the previous Tf * is a value 0. It is determined whether or not it is less than the predetermined torque Tref having a slightly larger positive value (step S340). These determinations are processes for determining whether or not the previous front wheel side execution torque (previous Tf *) is within a predetermined torque range including a value of zero. Immediately after the accelerator pedal 83 is depressed during the deceleration traveling by the driving force offset control, it is usually determined that the previous front wheel side execution torque (previous Tf *) is less than the negative predetermined torque (−Terf). In this case, a relatively large first rate value Tfrt1 used in normal time is set as the front wheel side rate value Tfrt (S370), and the front wheel side rate value Tfrt is requested from the previous front wheel side execution torque (previous Tf *). The smaller one of the torque changed toward the torque Tfreq and the front wheel side required torque Tfreq is set as the current front wheel side execution torque Tf * (step S390). Then, it is determined whether or not the previous rear wheel side execution torque (previous Tr *) is the lower limit torque Trmin, that is, whether or not the rear wheel side execution torque Tr * is under the lower limit guard by the driving force offset control ( Step S400). If it is determined that the previous rear wheel side execution torque (previous Tr *) is the lower limit torque Trmin, it is determined whether or not the timer counter C is equal to or greater than a predetermined value Cref (step S410). The timer counter C is set to a value 0 as an initial value, and starts counting at a timing described later. If it is determined that the timer counter C is not greater than or equal to the predetermined value Cref, the rear wheel side execution torque Tr * is held at the lower limit torque Trmin (step S420). When the front wheel side execution torque Tf * and the rear wheel side execution torque Tr * are thus set, the torque command Tm1 * of the motor MG1 is set to 0, and the front wheel side execution torque Tf * is set to the torque command Tm2 * of the motor MG2. Then, the rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3 (step S440). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S450), and this routine is finished.

  In steps S330 and S340, the previous front-wheel-side execution torque (previous Tf *) is not less than the negative predetermined torque (−Tref) and less than the positive predetermined torque Tref, that is, within a predetermined torque range including the value 0. If it is determined that the vehicle is in the range, the front wheel side execution torque Tf * is changed by the gradual change process. That is, the second rate value Tfrt2 smaller than the first rate value Tfrt1 is set as the front wheel side rate value Tfrt (step S380), and the front wheel side rate value Tfrt is requested from the previous front wheel side execution torque (previous Tf *). The smaller one of the torque changed toward the torque Tfreq and the front wheel side required torque Tfreq is set as the current front wheel side execution torque Tf * (step S390). Thus, by changing the front wheel side execution torque Tf * by the gradual change process, the differential gear 37F is changed when the sign of the front wheel side execution torque Tf * changes, that is, when the deceleration torque changes to the acceleration torque. Torque shock that can be caused by the backlash of the gear can be suppressed. While the front wheel side execution torque Tf * is being changed by the slow change process, the timer counter C does not start counting. Therefore, the timer counter C is determined to be less than the predetermined value Cref, and the rear wheel side execution torque Tr * is held at the lower limit torque Trmin (steps S400 to S420). Subsequently, a value 0 is set in the torque command Tm1 * of the motor MG1, a front wheel side execution torque Tf * is set in the torque command Tm2 * of the motor MG2, and a rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3. Is set (step S440). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S450), and this routine is finished.

In step S340, the previous front-wheel-side execution torque (previous Tf *) is equal to or greater than the positive predetermined torque Tref, that is, the negative torque is changed to a positive torque through a predetermined torque range including the value 0. If it is determined that the timer has changed, it is determined whether or not the timer counter C is the initial value (value 0) (step S350). If the timer counter C is the initial value, the timer counter C starts counting (step S360). If the timer counter C is not the initial value, the counting is already started, and step S360 is skipped. Subsequently, a first rate value Tfrt1 that is normally used is set as the front wheel side rate value Tfrt (step S370), and the torque and front wheel side changed from the previous Tf * by the front wheel side rate value Tfrt toward the front wheel side required torque Tfreq. The smaller of the required torque Tfreq is set as the current front wheel side execution torque Tf * (step S390). If it is determined in steps S400 and S410 that the previous rear wheel side execution torque (previous Tr *) is the lower limit torque Trmin and the timer counter C is less than the predetermined value Cref, the current rear wheel side execution torque Tr * is set to the lower limit torque Trmin. (Step S420). Subsequently, a value 0 is set in the torque command Tm1 * of the motor MG1, a front wheel side execution torque Tf * is set in the torque command Tm2 * of the motor MG2, and a rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3. Is set (step S440). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S450), and this routine is finished. Thus, the timing at which the front wheel side execution torque Tf * changes from a negative value torque (deceleration torque) to a positive value torque (acceleration torque) after passing through a predetermined torque range including the value 0. Thus, the timer counter C starts counting. Until the timer counter C becomes equal to or greater than the predetermined value Cref, the front wheel side execution torque Tf * is increased toward the front wheel side required torque Tfreq at the relatively large first rate value Tfrt1 used during normal time, The execution torque Tr * is held at the lower limit torque Trmin.

  If the timer counter C is determined to be greater than or equal to the predetermined value Cref in step S410, the relatively high rear wheel side rate value Trrt used in normal time is changed from the previous rear wheel side execution torque (previous Tr *) toward the rear wheel side required torque Trreq. The smaller one of the changed torque and the rear wheel side required torque Trreq is set as the rear wheel side execution torque Tr * (step S430). Subsequently, a value 0 is set in the torque command Tm1 * of the motor MG1, a front wheel side execution torque Tf * is set in the torque command Tm2 * of the motor MG2, and a rear wheel side execution torque Tr * is set in the torque command Tm3 * of the motor MG3. Is set (step S440). Then, torque commands Tm1 *, Tm2 *, Tm3 * are transmitted to the motor ECU 40 (step S450), and this routine is finished. Thus, the rear wheel side execution torque Tr * passes through a predetermined torque range including the value 0 from the torque (deceleration torque) in which the front wheel side execution torque Tf * is a negative value, and is a positive value (acceleration torque). At the timing when the predetermined time has elapsed (the timing when the timer counter C becomes equal to or greater than the predetermined value Cref), the increase in the rear-wheel-side execution torque Tr * is started toward the rear-wheel-side required torque Trreq. . The predetermined value Cref is a time corresponding to a half cycle of vibration (Ff vibration) transmitted to the vehicle body due to an increase in the front wheel side execution torque Tf *, and a value obtained in advance through experiments or the like is determined. For this reason, the vibration (Fr vibration) transmitted from the drive shaft 36R to the vehicle body due to the increase in the rear wheel side execution torque Tr * has an opposite phase to the Ff vibration. Thereby, since the Ff vibration and the Fr vibration cancel each other, the occurrence of the acceleration shock can be suppressed.

  FIG. 7 is a time chart showing an example of the time change of the accelerator opening Acc, the total driving force, the motor MG2 torque Tm2, the motor MG3 torque Tm3, and the timer counter C. In the figure, the solid line shows a time chart of an embodiment in which the vehicle travels at a reduced speed using the driving force offset control and then performs an accelerated travel.In the figure, the dashed line travels at a reduced speed without using the driving force offset control, Then, the time chart of the comparative example which performs acceleration driving | running | working is shown. In the embodiment, when the accelerator pedal 83 is depressed at time t1 during traveling in the CD mode and a negative torque (decelerated traveling) is requested as the required torque Td *, the torque of the motor MG3 is set to a value greater than 0. The lower limit is guarded with a slightly larger lower limit torque Trmin, and control is performed so that all of the required torque Td * is output by the motor MG2 (driving force offset control). Thereafter, when the accelerator pedal 83 is depressed at time t2 to request a positive torque (accelerated running) as the required torque Td *, while the torque of the motor MG2 is within a predetermined torque range including the value 0 (time During the period from t3 to t4), the torque of the motor MG2 is changed by the slow change process. On the other hand, the torque of the motor MG3 is guarded by a lower limit torque Trmin having a positive value slightly larger than 0 and no sign change occurs, so that a slow change process is unnecessary and the torque can be quickly started up. Thus, the acceleration response can be further improved.

  On the other hand, in the comparative example, torque is output from the motors MG2 and MG3 so that the required torque Td * is always output to the drive shafts 36F and 36R at the drive force distribution ratio k. For this reason, when acceleration traveling is requested after deceleration traveling is requested, the sign changes in each of the torque of the motor MG2 and the torque of the motor MG3. In particular, in the electric vehicle 20 of the embodiment, the engine 22 and the motor MG1 are connected to the drive shaft 36F connected to the front wheels 38a and 38b via the planetary gear 30, and the drive shaft 36R to which the engine 22 and the like are not connected. Are often used that have a lower rigidity than the drive shaft 36F. For this reason, in order to suppress a torque shock that may occur due to gear backlash of the differential gear 37R, it is necessary to make the rate value for changing the torque of the motor MG3 smaller than the motor MG2 within a predetermined torque range including the value 0. There is. As a result, even if the torque of the motor MG2 passes through a predetermined torque range and turns to a positive value torque, it takes a long time to pass through the predetermined torque range of the motor MG3 torque and turn to a positive value torque. However, the rise of torque is greatly delayed.

  In the electric vehicle 20 of the embodiment, the timer counter C is set to be equal to or greater than the predetermined value Cref at time t5 until a predetermined time elapses after the torque of the motor MG2 passes the predetermined torque range and turns to a positive torque. Until the torque of the motor MG3 is maintained at the lower limit torque Trmin. Then, when a predetermined time elapses after the torque of the motor MG2 turns to a positive torque, the torque of the motor MG3 starts to increase. The predetermined value Cref is set to a time corresponding to a half cycle of vibration (Ff vibration) transmitted from the drive shaft 36F to the vehicle body due to an increase in the torque of the motor MG2, and therefore from the drive shaft 36R due to an increase in the torque of the motor MG3. The vibration (Fr vibration) transmitted to the vehicle body has an opposite phase to the Ff vibration. As a result, the Ff vibration and the Fr vibration cancel each other, and the acceleration shock is suppressed.

  In the electric vehicle 20 according to the embodiment described above, when a negative torque is requested as the required torque Td *, the drive for controlling the motor MG3 so that a torque having a positive lower limit torque Trmin as a lower limit is output. Force offset control is executed. As a result, the torque of the motor MG3 does not require a gradual change process for suppressing a torque shock that may occur due to the gear backlash of the differential gear 37R, and the torque output from the motor MG3 can be quickly raised. As a result, acceleration response to accelerator operation can be improved. Of course, the negative torque (braking force) output from the motor MG2 can correspond to the negative required torque Td *.

  In addition, in the electric vehicle 20 of the embodiment, when acceleration traveling is requested during deceleration traveling by the driving force offset control, vibration that may be caused by an increase in the torque of the motor MG2 and vibration that may be caused by an increase in the torque of the motor MG3. The motor MG3 is output at a timing when a predetermined time has elapsed since the torque output from the motor MG2 has changed from a negative torque to a positive torque through a predetermined torque range including the value 0 so that the phases are opposite to each other. Start increasing torque. Thereby, the vibration that can be caused by the increase in torque from the motor MG2 can be canceled by the vibration that can be caused by the increase in torque from the motor MG3, and acceleration shock can be suppressed.

  In the electric vehicle 20 of the embodiment, when the acceleration traveling is requested during the deceleration traveling by the driving force offset control, the front wheel side execution torque Tf * passes through a predetermined torque range from a negative value to a positive value. Until the predetermined time (predetermined value Cref) elapses after turning to the torque of the value, the rear wheel side execution torque Tr * is held at the positive lower limit torque Trmin, and at the timing when the predetermined time has elapsed, the rear wheel side The increase in execution torque Tr * was started. However, at the timing when the front wheel side execution torque Tf * changes from a negative value torque to a positive value after passing through the predetermined torque range, the rear wheel side execution torque Tr * starts to increase and the front wheel side execution torque Tf. * May be held at the upper limit torque of the predetermined torque range, and the increase in the front wheel side execution torque Tf * may be started at a timing when a predetermined time (predetermined value Cref) has elapsed. Further, if acceleration traveling is requested during deceleration traveling by driving force offset control, the increase in the front wheel side execution torque Tf * and the rear wheel side execution torque Tr * may be started immediately. In this case, since the sign of the front wheel side execution torque Tf * is changed, the front wheel side execution torque Tr * is changed by the gradual change process while it is within the predetermined torque range including the value 0. Since no change occurs, the torque can be increased immediately without performing a gradual change process. Thereby, although a slight acceleration shock occurs, the driving force can be quickly raised toward the required torque Td *, and the acceleration response can be further improved.

In the electric vehicle 20 of the embodiment, the system is normal, the traveling mode M is the CD mode, the shift position SP is the D position, and the vehicle speed V is the predetermined vehicle speed Vref.
When the following conditions are satisfied: the input limit Win is less than the predetermined power Wref, the motor temperature tm3 is less than the predetermined temperature tref, and the required torque Td * is greater than the motor lower limit torque Tm2min. The execution of the driving force offset control was permitted. However, some of the conditions described above may be omitted, or new conditions different from the conditions described above may be added.

  The electric vehicle 20 according to the embodiment includes the charger 60 that charges the battery 50 by connecting the power plug 61 to the external power source 69. However, the battery 50 is received by receiving power from the external power source 69 in a non-contact manner. It is good also as a thing provided with the charger which charges. Moreover, the electric vehicle (hybrid vehicle) which is not provided with the charger charged with such an external power supply may be sufficient.

  In the electric vehicle 20 according to the embodiment, the engine 22, the motor MG1, and the motor MG2 are connected to the drive shaft 36F connected to the front wheels 38a and 38b, and the motor MG3 is connected to the drive shaft 36R connected to the rear wheels 38c and 38d. It was set as the structure to do. However, the engine 22, the motor MG1, and the motor MG2 may be connected to the drive shaft connected to the rear wheel, and the motor MG3 may be connected to the drive shaft connected to the front wheel. In this case, in the deceleration control routine of FIG. 2 and the acceleration control routine of FIG. 6, the torque command Tm3 * of the motor MG3 is set to the front wheel side execution torque Tf *, and the torque command Tm2 * of the motor MG2 is set to the rear wheel side execution torque Tr. Set to *. In the driving force offset control, the front wheel side execution torque Tf * may be guarded with a lower limit torque having a positive value slightly larger than 0 with respect to the front wheel side required torque Tfreq.

  In the electric vehicle 20 of the embodiment, the engine 22, the motor MG1, and the drive shaft 36F connected to the front wheels 38a and 38b are connected to the planetary gear 30, and the motor MG2 is connected to the drive shaft 36F, and the rear wheels 38c and 38d are connected. The motor MG3 is connected to the coupled drive shaft 36R. As illustrated in the electric vehicle 120 of the modified example of FIG. 8, a motor MGF is connected to a drive shaft 36F connected to the front wheels 38a and 38b via a transmission 130 and a rotation shaft of the motor MGF is connected to a rotation shaft of the motor MGF via a clutch 129. The engine 22 may be connected, and the motor MGR may be connected to the drive shaft 36R connected to the rear wheels 38c and 38d. Further, as illustrated in the electric vehicle 220 of the modified example of FIG. 9, the motor MGF is connected to the drive shaft 36F connected to the front wheels 38a and 38b, and the motor MGR is connected to the drive shaft 36R connected to the rear wheels 38c and 38d. It is good also as a structure of the electric vehicle which connects these.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor MG2 corresponds to a “first motor”, the motor MG3 corresponds to a “second motor”, the battery 50 corresponds to a “power storage device”, and the HVECU 70, the engine ECU 24, and the motor ECU 40 perform “control”. It corresponds to "apparatus".

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. In other words, the interpretation of the invention described in the column of means for solving the problem should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problem. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of electric vehicles.

  20, 120, 220 Electric vehicle, 22 engine, 23 crank position sensor, 24 engine electronic control unit (engine ECU), 26 crankshaft, 28 damper, 30 planetary gear, 36F, 36R drive shaft, 37F, 37R differential gear, 38a , 38b Front wheel, 38c, 38d Rear wheel, 40 Motor electronic control unit (motor ECU), 41, 42, 43 Inverter, 44, 45, 46 Rotation position detection sensor, 47 Temperature sensor, 50 Battery, 51a Voltage sensor, 51b Current sensor, 51c Temperature sensor, 52 Battery electronic control unit (battery ECU), 54 Power line, 60 charger, 61 Power plug, 62 Connection switch, 69 External power supply, 70 Hybrid electronic control unit ( HVECU), 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, 92 mode selector switch, 129 clutch, 130 shift Machine, MG1, MG2, MG3, MGF, MGR motor.

Claims (5)

A first motor capable of outputting a driving force to one of the front wheels and the rear wheels;
A second motor capable of outputting a driving force to the other wheel of the front wheel and the rear wheel;
A power storage device capable of exchanging electric power with the first motor and the second motor;
A control device for controlling the first motor and the second motor to travel with a required driving force required for traveling;
An electric vehicle comprising:
When a negative driving force is required as the required driving force, the control device controls the second motor with a predetermined positive driving force as a lower limit, and controls the first motor to travel with the required driving force. Execute driving force offset control to control,
Electric vehicle. The electric vehicle according to claim 1,
The controller does not execute the driving force offset control when an abnormality occurs in the system.
Electric vehicle. The electric vehicle according to claim 1 or 2,
The vehicle has an engine capable of outputting power to the one wheel, and travels by switching between a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode as a travel mode.
The control device does not execute the driving force offset control in the CS mode;
Electric vehicle. The electric vehicle according to any one of claims 1 to 3,
When the maximum charge power that can be charged by the power storage device is less than a predetermined power, when the temperature of the second motor is equal to or higher than a predetermined temperature, or when the vehicle speed is less than a predetermined vehicle speed, the driving force offset control is not executed.
Electric vehicle. The electric vehicle according to any one of claims 1 to 4,
When acceleration traveling is requested during deceleration traveling by the driving force offset control, the vibration that can be caused by the increase in the driving force of the first motor and the vibration that can be caused by the increase in the driving force of the second motor are in opposite phases. And controlling the first motor and the second motor to start increasing the driving force at different timings,
Electric vehicle.

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