Vehicle control system

Abstract

To excellently suppress battery degradation and SOC reduction when the allowable charging power allowed for battery charging is limited.SOLUTION: A control device of a vehicle according to the present disclosure is the control device of the vehicle which includes an electric motor that can output regenerative braking torque to drive wheels and a battery that exchanges power with the electric motor. When a voltage control condition including such a condition that at least the actual charging power supplied for battery charging falls outside a range of the allowable charging power allowed for battery charging is established, the control device controls an output voltage of the electric motor so that the charging current of the battery reaches a target current based on at least the allowable charging power.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device for a vehicle including an electric motor capable of outputting regenerative braking torque to a driving wheel and a battery that exchanges power with the electric motor.

Background Art

[0002] Conventionally, an electric vehicle including a rechargeable battery and a motor driven by the discharge output of the battery has been known (see, for example, Patent Document 1). The control device of this electric vehicle determines a charging upper limit power (allowable charging power) according to the SOC and temperature of the battery, and obtains a regenerative torque upper limit value by dividing the charging upper limit power by the motor speed. Further, the control device obtains a regenerative torque target value by comparing the regenerative torque upper limit value with the motor rated power, and controls the motor to output a braking torque according to the regenerative torque target value. Thereby, when braking the electric vehicle, the regenerative torque can be set to the maximum value within a range that can prevent overcharging of the battery, and a large amount of regenerative energy can be recovered by the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional electric vehicle, the regenerative torque target value varies due to fluctuations in the motor speed, and accordingly, the actual charging power supplied to the battery also varies. Therefore, when the allowable charging power allowed for charging the battery is limited so that the absolute value becomes smaller according to the SOC and temperature of the battery, the battery may be charged with power outside the range of the allowable charging power and the battery may deteriorate, or conversely, the SOC of the battery may decrease due to the reduction of the regenerative torque target value.

[0005] Therefore, the primary objective of this disclosure is to effectively suppress battery degradation and SOC reduction when the permissible charging power for battery charging is limited. [Means for solving the problem]

[0006] The vehicle control device of the present disclosure is a vehicle control device including an electric motor capable of outputting regenerative braking torque to drive wheels and a battery that exchanges power with the electric motor, and controls the output voltage of the electric motor so that the charging current of the battery becomes a target current based on the allowable charging power when a voltage control condition is met which includes at least the actual charging power used to charge the battery is outside the range of the allowable charging power permitted for charging the battery.

[0007] The vehicle control device of this disclosure controls the output voltage of the motor so that the battery charging current becomes a target current based on the allowable charging power when a voltage control condition is met, which includes at least the actual charging power supplied to charge the battery being outside the range of the allowable charging power permitted for charging the battery. This makes it possible to bring the battery charging current closer to a target current based on the allowable charging power, without being affected by fluctuations in the motor speed, when the allowable charging power is limited, thereby effectively suppressing battery degradation and the decrease in SOC. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a vehicle including the control device of this disclosure. [Figure 2] This flowchart shows an example of a routine executed by the control device of this disclosure. [Figure 3] This is a flowchart illustrating the process in step S150 of Figure 2. [Modes for carrying out the invention]

[0009] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0010] Figure 1 is a schematic diagram showing a vehicle 1 including the control device of the present disclosure. The vehicle 1 shown in the figure is a hybrid vehicle including an engine 10, a power transmission device 20 that transmits power from the engine 10 to the drive wheels DW, and a motor generator MG. Furthermore, the vehicle 1 includes an inverter 30, a high-voltage battery 40, a low-voltage battery 50, a DC / DC converter (voltage converter) 55, an engine electronic control unit (hereinafter referred to as "engine ECU") 60, a transmission electronic control unit (hereinafter referred to as "transmission ECU") 70, a brake electronic control unit (hereinafter referred to as "brake ECU") 80, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 90 as the control device of the present disclosure.

[0011] Engine 10 is an internal combustion engine that generates power by the explosive combustion of a mixture of air and hydrocarbon fuels such as gasoline, diesel, or LPG. Engine 10 includes multiple cylinders (combustion chambers) (not shown), a crankshaft (output shaft) 11 connected to pistons (not shown) located in each cylinder, an electronically controlled throttle valve (not shown), multiple fuel injectors and spark plugs, a crank angle sensor 12 for detecting the rotational position (crank angle) of the crankshaft 11, and the like. Furthermore, engine 10 includes a starter 15 that outputs cranking torque to the crankshaft 11 to start the engine 10. The starter 15 includes a pinion gear that can mesh with a ring gear that rotates integrally with the crankshaft 11, a DC motor that rotationally drives the pinion gear, and an actuator that moves the pinion gear back and forth between a meshing position with the ring gear and a retracted position.

[0012] The power transmission device 20 includes a starting device connected to the crankshaft 11 of the engine 10, a transmission mechanism (automatic transmission) connected to the starting device, a hydraulic control device that supplies hydraulic pressure to the starting device and the transmission mechanism, etc. (all not shown). The starting device includes a torque converter (fluid transmission device) having a front cover, pump impeller, turbine runner and stator etc. connected to the crankshaft 11, a damper mechanism that dampens vibrations from the engine 10, a clutch (lock-up clutch) that can connect the front cover and the transmission mechanism via the damper mechanism, etc. The transmission mechanism is, for example, a 4-speed to 10-speed automatic transmission mechanism and includes an input shaft, an output shaft, at least one planetary gear mechanism, and multiple clutches and brakes (hydraulic engagement elements) each. The transmission mechanism transmits power from the starting device (damper mechanism) to the input shaft in multiple stages and outputs it to the output shaft. The power output from the output shaft of the transmission mechanism is transmitted to the drive wheels DW via the differential gear DF ​​and drive shaft DS. The transmission mechanism may be, for example, a belt-type continuously variable transmission (CVT) or a dual-clutch transmission.

[0013] The motor-generator MG is a synchronous generator-motor (three-phase AC motor) including a stator and rotor (not shown). The rotor of the motor-generator MG is irremovably connected via a transmission mechanism 17 to the end of the crankshaft 11 of the engine 10 opposite to the power transmission device 20. In this embodiment, the transmission mechanism 17 is a wrap-around transmission mechanism including a pulley fixed to the crankshaft 11, a pulley fixed to the rotor of the motor-generator MG, and a belt wrapped around both pulleys. The transmission mechanism 17 may also be a gear mechanism or a chain mechanism. Furthermore, the motor-generator MG may be a DC motor and may be positioned (directly connected) between the engine 10 and the power transmission device 20.

[0014] The inverter 30 drives the motor generator MG and includes, for example, six transistors and six diodes connected in parallel to each transistor in opposite directions. The high-voltage battery 40 is, for example, a lithium-ion secondary battery or nickel-metal hydride secondary battery having a rated output voltage of 40-50V. The high-voltage battery 40 is connected to the inverter 30 via a system main relay (not shown) and a high-voltage power line LH. As a result, the high-voltage battery 40 and the motor generator MG exchange power via the inverter 30. The low-voltage battery 50 is, for example, a secondary battery such as a lead-acid battery having a rated output voltage of 12-15V, and stores power supplied to various auxiliary equipment. The DC / DC converter 55 is connected to the high-voltage power line LH (system main relay) and also to various auxiliary equipment, including the low-voltage battery 50 and the starter 15 mentioned above, via a low-voltage power line LL and an output relay (not shown). The DC / DC converter 55 can step down power from the high-voltage power line LH, i.e., the motor generator MG or the high-voltage side battery 40, and supply it to the low-voltage power line LL, and can also step up power from the low-voltage side battery 50 and supply it to the high-voltage power line LH.

[0015] The engine ECU 60, transmission ECU 70, brake ECU 80, and HVECU 90 each include a microcomputer having a CPU, ROM, RAM, input / output devices, etc. (not shown), and exchange information with each other via a shared dedicated line and a dedicated communication line. The engine ECU 60 controls the engine 10 and related auxiliary equipment such as the starter 15 based on signals from various sensors such as the crank angle sensor 12 and the HVECU 90, etc. The transmission ECU 70 controls the hydraulic control device of the power transmission device 20 based on signals from various sensors and the HVECU 90, etc. The brake ECU 80 sets command values ​​to a hydraulic brake actuator (not shown) based on the brake pedal stroke (amount of brake pedal depression, not shown) detected by a brake pedal stroke sensor (not shown) and the detected value of a vehicle speed sensor (not shown) that detects the vehicle speed V of the vehicle 1, etc., and controls the hydraulic brake actuator based on said command values.

[0016] The HVECU90 acquires signals from a start switch to instruct the system to start and stop the vehicle 1, an accelerator pedal position sensor to detect the accelerator opening Acc, a brake switch, a shift position sensor, a vehicle speed sensor, etc. The HVECU90 also acquires signals from a voltage sensor to detect the terminal voltage Vb of the high-voltage side battery 40, a current sensor to detect the charge / discharge current Ib of the high-voltage side battery 40, and a temperature sensor to detect the temperature (battery temperature) Tb of the high-voltage side battery 40. Furthermore, the HVECU90 acquires signals from a voltage sensor to detect the voltage VH in the high-voltage power line LH (voltage output from the inverter 30 to the high-voltage side battery 40, or voltage applied from the high-voltage side battery 40 to the inverter 30), a current sensor to detect the current IH flowing through the high-voltage power line LH (current output from the inverter 30 to the high-voltage side battery 40, or current applied from the high-voltage side battery 40 to the inverter 30), a voltage sensor to detect the voltage VL in the low-voltage power line LL, a rotational position sensor to detect the rotational speed Nm of the motor generator MG, and a current sensor to detect the phase current applied to the motor generator MG, etc.

[0017] The HVECU90 derives the State of Charge (SOC) of the high-voltage battery 40, the charge / discharge power Pb* of the high-voltage battery 40, the allowable charge power Win for charging the high-voltage battery 40, and the allowable discharge power Wout for discharging the high-voltage battery 40, based on the terminal voltage Vb, charge / discharge current Ib, and battery temperature Tb. The HVECU90 then sets the target power and target rotational speed of the engine 10, the target torque (target regenerative braking torque or target assist torque) Tm* of the motor generator MG, etc., based on the accelerator opening Acc, the signal from the brake switch, the vehicle speed V, the SOC of the high-voltage battery 40, the charge / discharge power Pb*, the allowable charge power Win (negative value), the allowable discharge power Wout (positive value), etc. Furthermore, the HVECU90 switches the inverter 30 so that the motor generator MG outputs a torque corresponding to the target torque Tm*. Furthermore, the HVECU90 switches and controls the DC / DC converter 55 to step down the power from the motor generator MG or the high-voltage battery 40 and supply it to the low-voltage power line LL. Note that the vehicle 1 may also include an ECU that controls the motor generator MG (inverter 30) and an ECU that controls the DC / DC converter 55 instead of the HVECU90.

[0018] In the vehicle 1 configured as described above, the HVECU 90 controls the inverter 30 so that the engine 10 is started by cranking torque from the motor generator MG in response to the start switch being turned on by the driver. As a result, cranking torque is output from the motor generator MG to the crankshaft 11 via the transmission mechanism 17, and the engine 10 is started by the engine ECU 60 initiating fuel injection control and ignition control at a predetermined timing. Alternatively, the engine 10 may be started by cranking torque from the motor generator MG in response to the driver's request to start (e.g., releasing the brake pedal) after the start switch has been turned on by the driver.

[0019] Also, when the vehicle 1 is running, the engine ECU 60 executes intake air amount control, fuel injection control, ignition control, etc. of the engine 10 based on signals from various sensors so that power corresponding to the target power is output from the engine 10 based on the target power and target rotational speed set by the HV ECU 90. At this time, the HV ECU 90 performs switching control of the inverter 30 so that the motor generator MG outputs torque corresponding to the target torque Tm*. In the present embodiment, during the running of the vehicle 1, the motor generator MG mainly operates as a generator that generates electric power using a part of the power from the engine 10 that is under load operation, and is appropriately driven by the electric power from the high-voltage battery 40 to output assist torque (drive torque) to the crankshaft 11 of the engine 10. Further, when the vehicle 1 brakes, the motor generator MG outputs regenerative braking torque to each drive wheel DW via the power transmission device 20.

[0020] Subsequently, while referring to FIGS. 2 and 3, the control procedure of the motor generator MG, that is, the inverter 30 by the HV ECU 90 when the motor generator MG generates electric power using a part of the power from the engine 10 or outputs regenerative braking torque will be described.

[0021] FIG. 2 is a flowchart showing an example of a routine repeatedly executed by the HV ECU 90 at predetermined time intervals (micro time intervals) when the motor generator MG operates as a generator. When the execution timing of the routine shown in FIG. 2 arrives, the HV ECU 90 acquires control-required information such as the target torque Tm* of the motor generator MG set separately, the terminal voltage Vb of the high-voltage battery 40, the charge / discharge current Ib, the SOC, the charge / discharge required power Pb*, the allowable charge power Win, the allowable discharge power Wout, the voltage VH in the high-voltage power line LH (the voltage output from the inverter 30 to the high-voltage battery 40 side), the current IH flowing through the high-voltage power line LH (the current output from the inverter 30 to the high-voltage battery 40 side), and the rotational speed Nm of the motor generator MG (step S100).

[0022] Next, the HVECU90 calculates the actual charging power Pcb (=Vb × Ib, a negative value) of the high-voltage side battery 40 based on the terminal voltage Vb and charge / discharge current Ib acquired in step S100 (step S110), and determines whether the calculated actual charging power Pcb is less than the allowable charging power Win (a negative value) acquired in step S100 (step S120). If the actual charging power Pcb is greater than or equal to the allowable charging power Win and less than or equal to the allowable charging power Win as charging power (step S120: NO), the HVECU90 switches control the inverter 30 (torque control) so that the motor generator MG outputs the target torque Tm* acquired in step S100 (step S125), and terminates the routine shown in Figure 2. The target torque Tm* is calculated based on the charge / discharge request power Pb* of the high-voltage side battery 40 and the rotational speed Nm of the motor generator MG when the motor generator MG generates power using a portion of the power from the engine 10. Furthermore, when the motor generator MG outputs regenerative braking torque, the target torque Tm* is calculated based on the required regenerative braking force corresponding to the rotational speed Nm of the motor generator MG and the SOC of the high-voltage battery 40, and a predetermined conversion coefficient.

[0023] On the one hand, when the actual charging power Pcb is less than the allowable charging power Win and greater than the allowable charging power Win as the charging power (step S120: YES), the HVECU 90 determines whether the SOC of the high-voltage battery 40 obtained in step S100 is equal to or greater than a predetermined threshold value (lower limit value) Sref (for example, about 20 - 30%) (step S130). When the SOC of the high-voltage battery 40 is equal to or greater than the threshold value Sref (step S130: YES), the HVECU 90 determines whether the target torque Tm* obtained in step S100 is less than a predetermined torque threshold value Tref (negative value) (step S140). The torque threshold value Tref is pre-adapted as the maximum regenerative torque (lowest target output torque) that can be output to the motor generator MG by torque control based on the target torque Tm*. Also, when the SOC of the high-voltage battery 40 is less than the threshold value Sref (step S130: NO), the process of step S140 is skipped.

[0024] When the target torque Tm* is equal to or greater than the torque threshold value Tref (step S140: NO), the HVECU 90 re-sets the target torque Tm* based on the target torque Tm* obtained in step S100, the torque threshold value Tref, and a predetermined creep condition (rate value or creep time) so that the output torque of the motor generator MG gradually changes to the torque threshold value Tref over time (step S145). Further, in step S145, the HVECU 90 performs switching control on the inverter 30 so that the motor generator MG outputs the re-set target torque Tm*, and once terminates the routine shown in FIG. 2.

[0025] Furthermore, if the SOC of the high-voltage battery 40 is less than the threshold Sref (step S130: NO) or if the target torque Tm* is less than the torque threshold Tref (step S140: YES), the HVECU 90 sets the target current Ic*, which is the target value of the charging current of the high-voltage battery 40 (step S150). When setting the target current Ic*, the HVECU 90 first sets the allowable current Ia (=Win / VH, a negative value), which is the current allowed for charging the high-voltage battery 40, based on the allowable charging power Win obtained in step S100 and the voltage VH in the high-voltage power line LH corresponding to the output voltage of the motor generator MG (step S151).

[0026] Next, the HVECU90 determines whether the charge / discharge current Ib of the high-voltage battery 40, i.e., the actual charging current (negative value), obtained in step S100, is less than the allowable current Ia (step S153). If the charge / discharge current Ib is less than the allowable current Ia and is greater than the allowable current Ia as a charging current (step S153: YES), the HVECU90 determines whether the absolute value of the difference between the charge / discharge current Ib (actual charging current) and the allowable current Ia, |Ib-Ia|, is greater than or equal to a predetermined threshold α (positive value) (step S155). If the difference between the charge / discharge current Ib and the allowable current Ia is relatively large and the absolute value |Ib-Ia| is greater than or equal to the threshold α (step S155: YES), the HVECU90 resets the allowable current Ia to the sum of the charge / discharge current Ib (negative value) of the high-voltage battery 40 obtained in step S100 and a predetermined rate value ΔI (positive value) (step S157). Furthermore, if the charge / discharge current Ib (actual charging current) obtained in step S100 is greater than or equal to the allowable current Ia (step S153: NO), and if the absolute value of the difference between the charge / discharge current Ib and the allowable current Ia, |Ib-Ia|, is less than the threshold α, the process in step S157 is skipped.

[0027] Then, the HVECU90 sets the target current Ic* to the smaller of a predetermined constant current value Iref and the allowable current Ia set in step S151 or reset in step S157 (step S159). The current value Iref is pre-adjusted to cover the power consumption of the auxiliary equipment of vehicle 1 and to partially charge the high-voltage side battery 40. After setting the target current Ic* in step S150 (S151-S159), the HVECU90 sets a target voltage to make the charge / discharge current Ib of the high-voltage side battery 40 the target current Ic*, and switches control the inverter 30 so that the voltage VH in the high-voltage power line LH corresponding to the output voltage of the motor generator MG (the voltage output from the inverter 30 to the high-voltage side battery 40) becomes the target voltage (step S160), and then terminates the routine shown in Figure 2.

[0028] As described above, the HVECU90 as a control device of this disclosure controls the motor generator MG (inverter 30) based on a target torque Tm* when the voltage control condition, which includes at least the charge / discharge current Ib (actual charging power) used to charge the high-voltage side battery 40 being outside the range of the allowable charging power Win of the high-voltage side battery 40, is not met (S120:NO, S140:NO) (S125, S145). Furthermore, when the voltage control condition is met (S120:YES, S130:NO, S140:YES), instead of controlling the motor generator MG based on a target torque Tm*, the HVECU90 controls the voltage VH in the high-voltage power line LH corresponding to the output voltage of the motor generator MG (inverter 30) so that the charge / discharge current Ib of the high-voltage side battery 40 is at least a target current Ic* based on the allowable charging power Win (feedback control) (S150, S160).

[0029] As a result, when the allowable charging power Win allowed for charging the high-voltage battery 40 is limited so that its absolute value decreases according to the SOC and the battery temperature Tb, the charging and discharging current Ib (actual charging current) of the high-voltage battery 40 can be made to approach the target current Ic* based on the allowable charging power Win without being affected by fluctuations in the rotational speed Nm of the motor generator MG. As a result, in the vehicle 1, when the allowable charging power Win of the high-voltage battery 40 is limited as the charging power, it is possible to satisfactorily suppress deterioration of the high-voltage battery 40 due to overcharging and a decrease in the SOC due to priority protection of the high-voltage battery 40. Further, in the vehicle 1, since the motor generator MG is inseparably connected to the crankshaft 11 of the engine 10, by executing the processes of steps S150 and S160, the charging and discharging current Ib (actual charging current) of the high-voltage battery 40 can be made to approach the target current Ic* based on the allowable charging power Win without being affected by fluctuations in the rotational speed of the engine 10.

[0030] Also, in the vehicle 1, the voltage control condition is established when the actual charging power Pcb of the high-voltage battery 40 is outside the range of the allowable charging power Win (Pcb < Win), and the SOC of the high-voltage battery 40 is less than the threshold value Sref (S120: YES, S130: NO), or when the target torque Tm* of the motor generator MG is less than the torque threshold value Tref corresponding to the maximum regenerative torque that can be output to the motor generator MG by torque control based on the target torque Tm* (S120: YES, S130: NO, S140: YES). By defining the voltage control condition in this way, when the allowable charging power Win of the high-voltage battery 40 is limited as the charging power, it is possible to satisfactorily suppress a decrease in the SOC of the high-voltage battery 40.

[0031] Furthermore, the HVECU90 sets the target current Ic* based on the allowable current Ia obtained by dividing the allowable charging power Win by the voltage VH in the high-voltage power line LH corresponding to the output voltage of the motor generator MG (inverter 30) (steps S151-S159). That is, the HVECU90 sets the target current Ic* based on the allowable current Ia when the charge / discharge current Ib (actual charging current, negative value) of the high-voltage side battery 40 is greater than or equal to the allowable current (negative value) Ia (S153: NO), and when the charge / discharge current Ib is less than the allowable current Ia and the absolute value of the difference between the charge / discharge current Ib and the allowable current Ia |Ib-Ia| is less than the threshold (predetermined value) α (S153: YES, S155: NO). Furthermore, when the charge / discharge current Ib is less than the allowable current Ia, and the absolute value of the difference between the charge / discharge current Ib and the allowable current Ia |Ib-Ia| is greater than or equal to the threshold (predetermined value) α (S153; YES, S155: YES), the HVECU90 sets the target current Ic* based on a value obtained by gradually increasing the charge / discharge current Ib (actual charging current) (Ib + ΔI) (S157, S159). This ensures that the target current Ic* is set appropriately, and also suppresses sudden changes in the power generated by the motor generator MG (regenerative braking torque) when the charge / discharge current Ib is less than the allowable current Ia, and the absolute value of the difference between the charge / discharge current Ib and the allowable current Ia |Ib-Ia| is greater than or equal to the threshold α, thereby ensuring good drivability of the vehicle 1.

[0032] Although the above-mentioned vehicle 1 includes a relatively low-output motor generator MG, the vehicles to which the present invention applies are not limited to this. That is, the vehicles to which the present invention applies may be a one-motor hybrid vehicle including a motor generator with a higher output than the above-mentioned motor generator MG, or a two-motor hybrid vehicle. Furthermore, the vehicles to which the present invention applies are not limited to hybrid vehicles including an engine 10 and a motor generator MG, but may also be battery electric vehicles (BEVs) or fuel cell vehicles (FCEVs) including a motor generator capable of outputting regenerative braking torque. Moreover, in step S160 of Figure 2, the voltage VH may be slowly changed based on the target voltage of the voltage VH set by feedback control. Also, in step S150 of Figure 2, regardless of the magnitude of the charge / discharge current Ib (actual charging current), the smaller of the current value Iref and the allowable current Ia obtained by dividing the allowable charging power Win by the voltage VH may be set as the target current Ic*.

[0033] As described above, the vehicle control device of the present disclosure is a control device (90) for a vehicle (1) including an electric motor (MG) capable of outputting regenerative braking torque to the drive wheels (DW) and a battery (40) that exchanges power with the electric motor (MG), and controls the output voltage of the electric motor (MG) so that the charging current (Ib) of the battery (40) becomes a target current (Ic*) based on at least the allowable charging power (Win) when voltage control conditions (S120, S130, S140) are met, which include at least the actual charging power (Pcb) used to charge the battery (40) being outside the range of the allowable charging power (Win) that is permitted for charging the battery (40) (S150, S160).

[0034] The vehicle control device of this disclosure controls the output voltage of the motor so that the battery charging current becomes a target current based on the allowable charging power when a voltage control condition is met, which includes at least the actual charging power supplied to charge the battery being outside the range of the allowable charging power permitted for charging the battery. This makes it possible to bring the battery charging current closer to a target current based on the allowable charging power, without being affected by fluctuations in the motor speed, when the allowable charging power is limited, thereby effectively suppressing battery degradation and the decrease in SOC.

[0035] Furthermore, the control device (90) may set the target current (Ic*) based on the allowable current (Ia) obtained by dividing the allowable charging power (Win) by the voltage (VH) corresponding to the output voltage of the electric motor (MG) (S151-S159).

[0036] This makes it possible to set the target current appropriately.

[0037] Furthermore, the control device (90) may set the target current (Ic*) based on the allowable current (Ia) when the actual charging current (Ib) of the battery (40) is greater than or equal to the allowable current (Ia) (S153: NO), and when the actual charging current (Ib) is less than the allowable current (Ia) and the absolute value of the difference between the actual charging current (Ib) and the allowable current (Ia) is less than a predetermined value (α) (S153: YES, S155: NO) (S159), and when the actual charging current (Ib) is less than the allowable current (Ia) and the absolute value of the difference between the actual charging current (Ib) and the allowable current (Ia) is greater than or equal to the predetermined value (α) (S153: YES, S155: YES) (S157, S159).

[0038] This makes it possible to suppress sudden changes in the power generated by the electric motor (regenerative braking torque) when the actual charging current is less than the allowable current, and the absolute value of the difference between the actual charging current and the allowable current is greater than or equal to a predetermined value, thereby ensuring good vehicle drivability.

[0039] Furthermore, the voltage control condition may also be met when the actual charging power (Pcb) is outside the range of the allowable charging power (Win) and the state of charge (SOC) of the battery (40) is less than a predetermined threshold (Sref) (S120:YES, S130:NO), or when the target torque (Tm*) of the electric motor (MG) is less than the maximum regenerative torque (Tref) that can be output by the electric motor (MG) through torque control based on the target torque (Tm*) (S120, S130, S140:YES).

[0040] This makes it possible to effectively suppress the decrease in the battery's State of Charge (SOC) when the battery's allowable charging power is limited.

[0041] Furthermore, the vehicle (1) may include an internal combustion engine (10), and the electric motor (MG) may be irremovably connected to the output shaft (11) of the internal combustion engine (10), and may be controlled to output a torque corresponding to the target torque (Tm*) when the voltage control conditions are not met (S120:NO, S140:NO) (S125, S145).

[0042] By applying the control device of this disclosure to such a vehicle, when the battery's allowable charging power is limited, it becomes possible to bring the battery charging current closer to a target current based on the allowable charging power, without being affected by fluctuations in engine speed, thereby effectively suppressing battery degradation and a decrease in SOC.

[0043] The invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Furthermore, the embodiments described above are merely one specific form of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention. [Industrial applicability]

[0044] The invention disclosed herein is applicable to the vehicle manufacturing industry, which includes an electric motor capable of outputting regenerative braking torque to the drive wheels and a battery that exchanges power with the electric motor. [Explanation of symbols]

[0045] 1 vehicle, 10 engines, 30 inverters, 40 high-voltage batteries, 90 hybrid electronic control unit (HVECU), MG motor generator.

Claims

1. A vehicle control device comprising an electric motor capable of outputting regenerative braking torque to the drive wheels, and a battery that exchanges power with the electric motor, When a voltage control condition is met that includes at least the actual charging power used to charge the battery being outside the range of the permissible charging power allowed for charging the battery, the output voltage of the motor is controlled so that the charging current of the battery becomes at least a target current based on the permissible charging power. When the actual charging current of the battery is greater than or equal to the allowable current obtained by dividing the allowable charging power by the voltage corresponding to the output voltage of the electric motor, and when the actual charging current is less than the allowable current and the absolute value of the difference between the actual charging current and the allowable current is less than a predetermined value, the target current is set based on the allowable current; and when the actual charging current is less than the allowable current and the absolute value of the difference between the actual charging current and the allowable current is greater than or equal to the predetermined value, the target current is set based on a value obtained by gradually increasing the actual charging current. Vehicle control system.

2. In the vehicle control device according to claim 1, A vehicle control device that satisfies the voltage control conditions when the actual charging power is outside the range of the allowable charging power and the state of charge (SOC) of the battery is below a predetermined threshold, or when the target torque of the electric motor is below the maximum regenerative torque that can be output to the electric motor by torque control based on the target torque.

3. In the vehicle control device according to claim 2, The aforementioned vehicle is further equipped with an internal combustion engine, The electric motor is irremovably connected to the output shaft of the internal combustion engine, and is controlled to output a torque corresponding to the target torque when the voltage control condition is not met.

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