JP6485292B2 - Electric vehicle power control method and power control apparatus - Google Patents

Description

  The present invention relates to a power control method and a power control apparatus for an electric vehicle, and more particularly to a technique for suppressing overdischarge of a power source.

2. Description of the Related Art Conventionally, a power control device for an electric vehicle that sets a lower limit voltage allowed for a power source is known (see, for example, Patent Document 1).
This conventional technique includes a discharge allowable power calculation unit that sets a first voltage as a lower limit voltage allowed for a power supply and derives a discharge allowable power of the power supply so that the voltage of the power supply does not fall below the first voltage.
In the prior art, when a driving condition in which excessive electric power is expected to be taken out from the battery is satisfied, the battery lowers the voltage in advance to the second voltage to limit the output of the battery. It is possible to suppress the occurrence of overdischarge in the battery.

JP 2009-166513 A

However, in the above-described prior art, the lower limit voltage is set only paying attention to prevention of overdischarge of the battery as the power source, and the maximum output value of the motor is defined by this lower limit voltage.
For this reason, the maximum output of the motor may be limited to a value lower than the maximum output that can actually be output depending on the battery state. In this case, the driver required torque cannot be obtained, and the driver feels uncomfortable. There is a risk of giving.

  The present invention has been made paying attention to the above problem, and an object thereof is to provide a power control method and a power control apparatus for an electric vehicle capable of obtaining a larger motor output while suppressing overdischarge of the battery. And

In order to achieve the above object, an electric vehicle power control method according to the present invention includes:
A motor that is a driving source of the vehicle, a battery that supplies electric power to the motor, and a detection device that detects a vehicle state including a battery state, and based on detection of the detection device, at the time of a request for raising the system lower limit voltage This is a power control method for an electric vehicle in which the system lower limit voltage is increased from the normal value.
The power control method for an electric vehicle according to the present invention obtains a battery output power characteristic that changes according to the battery state detected by the detection device when the system lower limit voltage is increased, and at the same time, obtains a motor output characteristic according to the number of rotations of the motor And the system lower limit voltage is set according to the battery output power characteristic and the motor output characteristic.

In the present invention, when the system lower limit voltage is increased, the system lower limit voltage is set according to the motor output characteristic in addition to the battery output power characteristic, so that the motor output characteristic is compared with the setting based only on the battery output power characteristic. Accordingly, the maximum motor output can be increased.
As a result, setting the system lower limit voltage makes it possible to obtain a larger motor output while suppressing overdischarge of the battery, and to prevent the driver from feeling uncomfortable because the driver required torque cannot be obtained. .

It is a power train system block diagram which shows the power train system of the power control apparatus of the hybrid vehicle of Embodiment 1 which implements the power control method of the hybrid vehicle of this invention. FIG. 3 is a control block diagram illustrating arithmetic processing executed by an integrated controller of the power control apparatus for a hybrid vehicle according to the first embodiment. It is a figure which shows the EV-HEV selection map used when performing the mode selection process in the said integrated controller. It is a map figure used with the said integrated controller, Comprising: (a) shows a target steady drive torque map, (b) shows an MG assist torque map. FIG. 3 is a map diagram showing an engine start / stop line map used in the power control apparatus for a hybrid vehicle in the first embodiment. It is a characteristic view which shows the request | requirement power generation output during driving | running | working with respect to the battery SOC used with the electric power control apparatus of the hybrid vehicle of Embodiment 1. FIG. 3 is a characteristic diagram showing a best fuel consumption line of an engine used in the power control apparatus for a hybrid vehicle in the first embodiment. FIG. 3 is a shift map diagram showing an example of shift lines in the automatic transmission used in the power control apparatus for a hybrid vehicle in the first embodiment. 4 is a flowchart showing a process flow of system lower limit voltage increase control in the electric power control apparatus for an electric vehicle according to the first embodiment. FIG. 3 is a power characteristic diagram showing a relationship between a battery output possible power line, an MG / INV maximum use power line, and an intersection with respect to a system lower limit voltage in the power control apparatus for an electric vehicle according to the first embodiment. FIG. 3 is a torque curve characteristic diagram showing a motor maximum torque curve determined by a system lower limit voltage in the electric power control apparatus for an electric vehicle according to the first embodiment. It is explanatory drawing for demonstrating an effect | action with the electric power control apparatus of the electric vehicle of Embodiment 1, and a comparative example.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for realizing a power control method and a power control apparatus for an electric vehicle according to the present invention will be described based on the embodiments shown in the drawings.

(Embodiment 1)
First, the configuration of the power control apparatus for a hybrid vehicle according to the first embodiment for carrying out the power control method for an electric vehicle according to the present invention will be described.
In the description of this configuration, the configuration of the power control apparatus for the hybrid vehicle of the first embodiment is changed to “power train system configuration”, “control system configuration”, “integrated controller configuration”, and “system lower limit voltage setting processing configuration”. Separately described.

[Powertrain configuration]
First, the power train system configuration of the hybrid vehicle of the first embodiment will be described.
FIG. 1 is an overall system diagram showing a hybrid vehicle by rear wheel drive to which a drive torque control device for a hybrid vehicle of Embodiment 1 is applied.

  As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine Eng, a first clutch CL1, a motor generator MG, a second clutch CL2, an automatic transmission AT, drive wheels RL, RR.

  The engine Eng is a gasoline engine or a diesel engine, and performs engine start control, engine stop control, and throttle valve opening control based on an engine control command from the engine controller 1. The engine output shaft is provided with a flywheel FW.

  The first clutch CL1 is a clutch interposed between the engine Eng and the motor generator MG. The first clutch CL1 is controlled to be engaged and disengaged including a half-clutch state by the first clutch control hydraulic pressure generated by the first clutch hydraulic unit 6 based on the first clutch control command from the first clutch controller 5. Is done. Further, as the first clutch CL1, for example, a dry single-plate clutch whose fastening / release is controlled by a hydraulic actuator 14 having a piston 14a is used.

  Motor generator MG is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. The motor generator MG is controlled by applying a plurality of alternating currents such as a three-phase alternating current generated by the inverter 3 based on a control command from the motor controller 2. In addition, motor generator MG operates as an electric motor that is driven to rotate by receiving power supplied from battery 4. Furthermore, when the rotor receives rotational energy from the engine Eng or driving wheels, the motor generator MG functions as a generator that generates electromotive force at both ends of the stator coil, and can also charge the battery 4. The rotor of motor generator MG is connected to the transmission input shaft of automatic transmission AT via a damper.

  The second clutch CL2 is a clutch interposed between the motor generator MG and the drive wheels RL and RR. The second clutch CL <b> 2 is controlled to be engaged and disengaged including slip engagement and slip release by the control hydraulic pressure generated by the second clutch hydraulic unit 8 based on the second clutch control command from the AT controller 7. As the second clutch CL2, for example, a wet multi-plate clutch or a wet multi-plate brake capable of continuously controlling the oil flow rate and hydraulic pressure with a proportional solenoid is used.

  The automatic transmission AT is a stepped transmission that automatically switches stepped gears such as five forward speeds and one reverse speed according to the vehicle speed, the accelerator opening degree, and the like. Therefore, the second clutch CL2 is not newly added as a dedicated clutch, but is an optimum clutch arranged in the torque transmission path among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT. Or choose a brake. Note that the second clutch CL2 does not use the frictional engagement element of the automatic transmission AT, and a dedicated clutch is provided between the motor generator MG and the automatic transmission AT, as indicated by a two-dot chain line in the drawing, or It may be interposed between the automatic transmission AT and the drive wheels RL and RR.

  Further, the output shaft of the automatic transmission AT is connected to the drive wheels RL and RR via a propeller shaft PS, a differential DF, a left drive shaft DSL, and a right drive shaft DSR.

[Control system configuration]
Next, the control system of the hybrid vehicle will be described.
The hybrid vehicle control system according to the first embodiment includes an engine controller 1, a motor controller 2, an inverter 3, a battery 4, a first clutch controller 5, a first clutch hydraulic unit 6, an AT controller 7, A second clutch hydraulic unit 8, a brake controller 9, and an integrated controller 10 are included. The engine controller 1, the motor controller 2, the first clutch controller 5, the AT controller 7, the brake controller 9, and the integrated controller 10 are connected via a CAN communication line 11 that can mutually exchange information. ing.

  The engine controller 1 inputs the engine speed information from the engine speed sensor 12, the target engine torque command from the integrated controller 10, and other necessary information. Then, a command for controlling the engine operating point (Ne, Te) is output to the throttle valve actuator of the engine Eng.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor generator MG, a target MG torque command and a target MG rotational speed command from the integrated controller 10, and other necessary information. Then, a command for controlling the motor operating point (Nm, Tm) of motor generator MG is output to inverter 3. The motor controller 2 monitors the battery SOC representing the charging capacity of the battery 4, and the battery SOC information is used as control information for the motor generator MG and is also connected to the integrated controller 10 via the CAN communication line 11. Supplied to.

  The first clutch controller 5 inputs sensor information from the first clutch stroke sensor 15 that detects the stroke position of the piston 14a of the hydraulic actuator 14, the target CL1 torque command from the integrated controller 10, and other necessary information. Then, a command for controlling engagement / release of the first clutch CL <b> 1 is output to the first clutch hydraulic unit 6.

The AT controller 7 inputs information from an accelerator opening sensor 16, a vehicle speed sensor 17, and other sensors 18 (transmission input rotation speed sensor, inhibitor switch, etc.). Then, when traveling with the D range selected, a control command for retrieving the optimum gear position by searching for the position where the operating point determined by the accelerator opening APO and the vehicle speed VSP exists on the shift map is obtained. Output to AT hydraulic control valve unit CVU. Further, in addition to the automatic shift control, the AT controller 7 gives a command for controlling the engagement / release of the second clutch CL2 in the AT hydraulic control valve unit CVU when the target CL2 torque command is input from the integrated controller 10. Second clutch control to be output to the two-clutch hydraulic unit 8 is performed.
The shift map is a map in which an upshift line and a downshift line are written according to the accelerator opening APO and the vehicle speed VSP, and an example is shown in FIG.

  The brake controller 9 inputs a wheel speed sensor 19 that detects the wheel speeds of the four wheels, sensor information from the brake stroke sensor 20, a regenerative cooperative control command from the integrated controller 10, and other necessary information. For example, when the brake is depressed, if the regenerative braking force is insufficient with respect to the required braking force obtained from the brake stroke, the regenerative braking force is compensated by mechanical braking force (hydraulic braking force or motor braking force). Perform cooperative brake control.

  The integrated controller 10 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. From the motor rotation speed sensor 21 that detects the motor rotation speed Nm and other sensors and switches 22. Necessary information and information are input via the CAN communication line 11. Then, the target engine torque command to the engine controller 1, the target MG torque command and the target MG rotational speed command to the motor controller 2, the target CL1 torque command to the first clutch controller 5, the target CL2 torque command to the AT controller 7, and the brake controller 9 Regenerative cooperative control command is output.

  FIG. 2 is a control block diagram illustrating arithmetic processing executed by the hybrid vehicle integrated controller 10 to which the hybrid vehicle control device of the first embodiment is applied. FIG. 3 is a diagram showing an EV-HEV selection map used when mode selection processing is performed by the integrated controller 10 of the hybrid vehicle. Hereinafter, based on FIG.2 and FIG.3, the arithmetic processing performed in the integrated controller 10 of Embodiment 1 is demonstrated.

[Configuration of integrated controller]
As shown in FIG. 2, the integrated controller 10 includes a target drive torque calculation unit 100, a mode selection unit 200, a target charge / discharge calculation unit 300, and an operating point command unit 400.
The target drive torque calculation unit 100 uses the target steady drive torque map shown in FIG. 4 (a) and the MG assist torque map shown in FIG. 4 (b) to input the transmission according to the accelerator opening APO and the vehicle speed VSP. A target steady driving torque and an MG assist torque are calculated from the rotation speed.

  The mode selection unit 200 uses the engine start / stop line map set by the accelerator opening APO set for each vehicle speed shown in FIG. 5 as the target travel mode for “EV travel mode” or “HEV travel mode”. select. Note that the engine start line and the engine stop line decrease in a direction in which the accelerator opening decreases as the battery SOC decreases.

  The target charge / discharge calculation unit 300 calculates a target power generation output based on the battery SOC using the traveling power generation request output map shown in FIG. Further, the target charge / discharge calculation unit 300 calculates an output necessary for increasing the engine torque from the current operating point to the best fuel consumption line indicated by a bold line in FIG. 7, and requests a smaller output than the target power generation output. As an output, it is added to the engine output.

  The operating point command unit 400 inputs the accelerator opening APO, the target drive torque tFoO, the MG assist torque, the target mode, the vehicle speed VSP, and the target charge / discharge power (required power generation output) tP. Then, from these input information, the transitional target engine torque, the target MG torque, the target MG rotation speed, the target CL1 torque, the target CL2 torque, and the target gear ratio are calculated using these as the operating point reaching targets. These calculation results are output to the controllers 1, 2, 5, and 7 via the CAN communication line 11.

Further, the operating point command unit 400 executes an engine start process.
That is, in the mode selection unit 200, when the operating point determined by the combination of the accelerator opening APO and the vehicle speed VSP exceeds the EV → HEV switching line and enters the HEV region during EV traveling, the HEV traveling with the engine starting from the EV traveling mode is performed. Switch mode to mode. The mode selection unit 200 switches the driving mode from the HEV driving mode to the EV driving mode with engine stop and engine disconnection when the operating point exceeds the HEV → EV switching line and enters the EV region during HEV driving. .

  In response to this traveling mode switching, the operating point command unit 400 performs a starting process when the accelerator opening APO exceeds the engine starting line shown in FIG. 5 in the EV traveling mode. In this starting process, the torque capacity is controlled to cause the second clutch CL2 to slip into a half-clutch state, and after it is determined that the second clutch CL2 has started slipping, the first clutch CL1 starts to be engaged and the engine rotation is started. Raise. When the engine speed reaches a speed at which the initial explosion is possible, the engine Eng is operated to close the first clutch CL1 when the motor speed and the engine speed are close to each other, and then the second clutch CL2 is turned on. Lock up and make transition to HEV driving mode.

The shift control unit 500 drives and controls a solenoid valve in the automatic transmission AT so as to achieve these from the target CL2 torque capacity and the target gear ratio.
FIG. 8 shows the shift line. That is, the shift control unit 500 determines the next shift stage from the current shift stage based on the vehicle speed VSP and the accelerator opening APO, and if there is a shift request, controls the shift clutch to change the speed.

The integrated controller 10 having the above configuration sets the WSC mode in the transitional transition period between these travel modes in addition to the EV mode and the HEV mode as the travel modes.
EV mode is a mode in which the vehicle travels only with the power of motor generator MG. In this EV mode, the engine Eng is kept stopped, the first clutch CL1 is released, and only the output rotation from the motor generator MG is changed to the left and right via the automatic transmission AT by the engagement or slip engagement of the second clutch CL2. To the driving wheels RL and RR.
The HEV mode is a mode in which the engine Eng and the motor generator MG drive, and the second clutch CL2 and the first clutch CL1 are engaged to automatically change the output rotation from the engine Eng and the output rotation from the motor generator MG. It is transmitted to the drive wheels RL and RR via the machine AT.

  The WSC mode is a mode in which the vehicle starts while controlling the clutch torque capacity when the P, N → D select starts from the “HEV mode” or when the D range starts from the “EV mode” or “HEV mode”. In this case, the slip engagement state of the second clutch CL2 is maintained by controlling the rotational speed of the motor generator MG, and the clutch transmission torque that passes through the second clutch CL2 becomes a required driving torque that is determined according to the vehicle state and driver operation. Start while controlling. At this time, since the second clutch CL2 is in the slip engagement state, it is possible to absorb the mode switching shock and take a countermeasure against the shock. “WSC” is an abbreviation for “Wet Start Clutch”.

  The first embodiment is characterized in that in the control system configuration described above, there is no boost converter as described in the publication of Patent Document 1 between the inverter 3 and the battery 4. .

[System lower limit voltage setting processing configuration]
The integrated controller 10 sets the system lower limit voltage.
The setting of the system lower limit voltage is different between the normal time when the power is taken out from the battery 4 within a predetermined range and the predetermined high-power running when the excessive power is expected to be taken out from the battery 4.

  In the normal time, the system lower limit voltage is set to a normal value set in advance based on the charge / discharge characteristics of the battery 4 so that the battery SOC does not become an overdischarge outside the proper range.

  On the other hand, when the system lower limit voltage increase request determination is made, the system lower limit voltage is determined based on the battery output possible power line (battery output power characteristics) and the MG / INV maximum use power line (motor output characteristics). It is raised and is variably set.

The system lower limit voltage increase request determination is made, for example, during high-power traveling. The high output traveling includes, for example, a case where the driver performs a sudden acceleration operation while traveling in the EV traveling mode. In this case, the accelerator opening and the vehicle speed as the vehicle state cross the engine start line, the engine start control is started, and the rapid acceleration operation is maintained for a predetermined period after the engine start control is started. In this case, the motor generator is required to have a high output.
In addition, sudden acceleration operation and high-power running are detected when the accelerator opening APO is larger than a predetermined value or when the driver's requested driving force exceeds a predetermined value based on the output of various sensors. This can be used for the ascent request determination.

In the following, the flow of processing when raising request determination is made to raise the system lower limit voltage will be described based on the flowchart of FIG.
First, in step S1, a battery state is read to obtain a battery output possible power line (VP line in FIG. 10) as a battery output power characteristic with respect to the system lower limit voltage. As shown in FIG. 10, the battery output possible power line has a slope that increases as the system lower limit voltage decreases and decreases as the system lower limit voltage increases.

As the battery state, the battery temperature, the battery SOC, the internal resistance value (degradation degree) of the battery 4 and the output duration time are read. And the battery output possible electric power line VP is determined based on the battery state which these show.
The relationship between the battery output possible power line VP with respect to the system lower limit voltage, the battery SOC, the battery temperature, the internal resistance value, and the output duration time is as follows.
The battery output possible power line is shifted in the direction of increasing the system lower limit voltage as the battery SOC is higher. That is, in the figure, among the three battery output possible power lines VP (1) to VP (3), VP (1) shows the case where the battery SOC is the highest, and VP (3) shows the case where the battery SOC is the lowest. Show. Thus, when raising a system lower limit voltage, a battery output possible electric power line is moved to the upper right direction in the figure.

The battery output possible power line VP is shifted in the direction of increasing the system lower limit voltage (upper right direction in the figure) as the battery temperature is higher.
The battery output possible power line VP is shifted in the direction of increasing the system lower limit voltage (upper right direction in the figure) as the internal resistance value (battery deterioration degree) is smaller.
The battery output possible power line VP is shifted in the direction of increasing the system lower limit voltage (upper right direction in the figure) as the output duration time is longer.

Returning to FIG. 9, in step S <b> 2 following step S <b> 1, an MG / INV maximum used power line (hereinafter simply referred to as an MG maximum used power line) MP as a motor output characteristic with respect to the system lower limit voltage is obtained.
This MG maximum power usage line MP continuously represents the maximum power usage for each system lower limit voltage at the maximum motor speed that can be obtained by the subsequent power usage function.

As shown in FIG. 10, the MG maximum use power line MP has a lower value as the system lower limit voltage is lower, and conversely, the MG maximum used power line MP has a lower slope that becomes higher as the system lower limit voltage is higher.
The MG maximum power line MP is determined for each motor rotation speed, and basically shifts in the direction of increasing the battery lower limit voltage as the rotation speed decreases. That is, of the five MG maximum power lines MP (1) to MP (5) shown in FIG. 10, MP (1) is a characteristic when the motor rotation speed is the lowest, and MP (5) Is the characteristic at the highest rotation.
In this case, the MG maximum use power line MP is determined in consideration of various battery power losses such as driving of auxiliary machines.

Returning to FIG. 9, in step S <b> 3 following step S <b> 2, “system lower limit voltage” and “battery maximum output possible value” are obtained from battery output possible power line VP and MG maximum use power line MP.
That is, the intersection (XP in FIG. 10) between battery output possible power line VP and MG maximum use power line MP is the maximum output point of each of battery 4 and motor generator MG. Therefore, the “system lower limit voltage” and the “battery maximum output possible value” are determined by the intersection XP.

Returning to FIG. 9, in step S4 following step S3, a maximum motor generator torque (hereinafter referred to as maximum MG torque) MTmax that can be output at that time is determined.
This maximum MG torque MTmax is calculated from the “system lower limit voltage” determined in step S3, the current “motor speed”, and the maximum MG torque characteristics (see FIG. 11) for each system lower limit voltage prepared separately. The maximum MG torque that can be output at the time is determined. In FIG. 11, the maximum MG torque MTmax2 indicates a torque curve when the system lower limit voltage is relatively lower than the maximum MG torque MTmax1.

Returning to FIG. 9, steps S5a to S5c following step S4 are processes for gradually returning the “system lower limit voltage” to the normal value based on the establishment of a predetermined return condition.
This return condition is when the difference between the “battery voltage” and the “system lower limit voltage” is equal to or less than a preset threshold value Vlim, or when the battery output equal to or greater than a predetermined value continues for a threshold value tlim or more.
Therefore, in step S5a, it is determined whether or not the difference between the “battery voltage” and the “system lower limit voltage” is equal to or smaller than the threshold value Vlim. If the difference is equal to or smaller than the threshold value Vlim, the process proceeds to step S5c. Proceed to

In step S5b, which proceeds when the difference is less than the threshold value Vlim in step S5a, it is determined whether or not the battery output has continued for a threshold value tlim or more in a state of a predetermined value or more. If this output state continues for the threshold value tlim or more, the process proceeds to step S5c. If the output state does not satisfy the threshold value tlim, the process returns to step S5a.
Note that the output equal to or higher than the predetermined value is set in accordance with the output accompanying the high-output travel in which the ascent request determination is made, and is an output that is assumed that the battery voltage approaches the system lower limit voltage as the threshold tlim continues.
The threshold tlim is a time assumed to increase the system lower limit voltage, and is set based on the assumed high output travel time, and is set to a time of about several seconds.
Then, in step S5c, which proceeds in the case of Yes determination in either step S5a or step S5b, the “system lower limit voltage” is gradually returned to the normal value.
Here, when the system lower limit voltage is gradually returned to the normal value, the system lower limit voltage can be returned with a constant gradient, or can be returned with a constant time according to the deviation width between the battery voltage and the system lower chord voltage.

(Operation of Embodiment 1)
Hereinafter, the operation of the first embodiment will be described. Prior to the description, a comparative example in which the system lower limit value is a fixed value will be briefly described.

<Comparative example>
When the system lower limit voltage increase request determination is made, the system lower limit voltage is increased from the normal value.
In this comparative example, as in the first embodiment, in a configuration in which no boost converter is provided between the battery and the inverter, the system lower limit value at the time of rising is set to a predetermined value based only on the battery state. It is.

  For example, as shown in FIG. 12, when the system lower limit voltage VA is set only by the battery state, generally, the maximum MG torque at the system lower limit voltage is set as the system maximum output value.

  Here, if the maximum MG torque is set according to the lowest value of the battery SOC (this is referred to as MTa), there is a possibility that the battery SOC and the actual MG output may have a surplus power. Cannot be realized.

On the other hand, when the maximum MG torque is set according to a high value of the battery SOC (this is referred to as MTb), when an output command is given to the motor generator MG by the maximum battery output, as shown by the dotted line MPW in the figure, the voltage decreases. The actual maximum MG torque decreases. In this case, the driver's operation (required driving force) and the actual torque may deviate, which may give the driver a feeling of strangeness.
Therefore, in order to prevent this uncomfortable feeling, it is necessary to set the maximum MG torque according to the case where the battery SOC is low as described above. In this case, an efficient output is realized as described above. It may not be possible.

<Embodiment 1>
In the first embodiment, when the system lower limit voltage is increased from the normal value, first, a current battery output possible power line VP (battery output power characteristic) with respect to the system lower limit voltage corresponding to the battery state is obtained (step S1). .

  The battery output possible power line VP is set based on the battery temperature, the battery SOC, the internal resistance value (degradation degree), and the output duration, and as shown in FIG. It is a characteristic. Also, the battery output possible power line VP (battery output power characteristic) has a width in the direction of the vertical axis (battery required power) according to the battery SOC, and the value of the battery required power decreases as the battery SOC decreases. .

Next, the MG maximum use power line MP (MG output characteristics) with respect to the system lower limit voltage is obtained (step S2).
As shown in FIG. 10, the MG maximum use power line MP rises to the right with respect to the system lower limit voltage.
The MG maximum power usage line MP has a width in the direction of the vertical axis (required battery power) according to the motor speed.

Next, as shown in FIG. 10, from the intersection XP of the obtained battery output possible power line VP (battery output power characteristic) and the MG maximum use power line MP (MG output characteristic), “system lower limit voltage” and “battery maximum output” Determine possible values.
That is, the intersection point XP shown in FIG. 10 is the maximum potential point as a system, and the output value can be guaranteed after the output is started.

Therefore, unlike the case where the maximum MG torque of the comparative example is set according to the lowest value of the battery SOC (MTa), the battery output and the maximum output of MG are not set to have sufficient power. .
Further, the maximum MG torque of the comparative example may decrease with the voltage drop, and the driver may feel uncomfortable, as in the case where the maximum SOC value of the battery SOC is set according to the highest value (MTb). Nor.

Further, the control for increasing the system lower limit voltage above the normal value returns to the normal value when a predetermined end condition is satisfied.
If the system lower limit voltage is increased, the maximum battery output performance is limited. Therefore, the battery maximum output performance can be ensured by returning the system lower limit voltage to the normal value under a predetermined termination condition.

One of the termination conditions is when the difference between the voltage of the battery 4 and the system lower limit voltage becomes equal to or less than the threshold Vlim after the system lower limit voltage is increased.
That is, when the battery voltage approaches the system lower limit voltage shown on the left, the battery actual value is close to the output limit value when the system lower limit voltage is assumed. For this reason, battery output power can be improved by lowering the system lower limit voltage to a normal value.

Another termination condition is a case where the output time of the battery 4 or more continues for the threshold tlim or more after the system lower limit voltage increases.
That is, the process for increasing the system lower limit voltage is set assuming a certain duration of battery output. For this reason, when the output exceeding the predetermined value of the battery 4 continues beyond the threshold tlim, the battery voltage may drop to near the system lower limit voltage.
Therefore, when the output of the battery 4 exceeds a predetermined value exceeds the threshold tlim, the maximum MG torque is lowered and the battery output power is improved by lowering the system lower limit voltage to the normal value. Can do.

  Further, when the system lower limit voltage is lowered toward the normal value, it is gradually lowered. In this way, by gradually and slowly lowering the system lower limit voltage, it is possible to suppress a change during the maximum MG torque output determined by the system lower limit voltage.

(Effect of Embodiment 1)
The effects of the first embodiment are listed below.
1) The electric power control method for the electric vehicle according to the first embodiment is as follows:
A motor generator MG serving as a drive source of the vehicle;
A battery 4 for supplying power to the motor generator MG;
A detection device (each sensor and switch) for detecting a vehicle state including a battery state;
With
An electric vehicle power control method for increasing the system lower limit voltage from a normal value based on detection by a detection device, when determining an increase request for the system lower limit voltage,
When the system lower limit voltage increases, a battery output power characteristic (battery output possible power line VP) that changes according to the battery state detected by the detection device is obtained (step S1), and a motor output characteristic (MG maximum) corresponding to the motor rotation speed is obtained. Obtaining the power line MP) used (step S2),
A system lower limit voltage is set according to the battery output power characteristic and the motor output characteristic (step S3).
Therefore, when determining an increase request, the maximum output of motor generator MG can be increased by increasing the system lower limit voltage.
Furthermore, since the system lower limit voltage is set according to the motor output characteristics in addition to the battery output power characteristics, the maximum voltage is higher than when setting only based on the battery output power characteristics without using an expensive configuration such as a boost converter. The MG torque can be increased.
As a result, setting the system lower limit voltage makes it possible to obtain a large motor output without using an expensive step-up converter while suppressing overdischarge of the battery. Can be suppressed.

2) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The system lower limit voltage is set based on an intersection point XP between a battery output possible power line VP as a battery output power characteristic with respect to the system lower limit voltage and an MG maximum use power line MP as a motor output characteristic with respect to the system lower limit voltage. .
Therefore, by setting the system lower limit voltage according to the MG maximum use power line MP in addition to the battery output possible power line VP, the maximum MG torque can be increased more reliably.
In addition, the maximum battery output is lower than when the system lower limit voltage is set according to the case where the battery SOC is the highest (MTb in FIG. 12). However, when the maximum MG torque is output, the maximum MG torque decreases with the voltage decrease. Deteriorating defects do not occur.
Moreover, in the first embodiment, since the MG maximum use power line MP considers various power losses, there is no possibility that the maximum MG torque is reduced due to this loss.

3) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The battery output possible power line VP is set to a side where the system lower limit voltage is increased as the temperature of the battery 4 is higher.
The higher the battery temperature, the smaller the battery internal resistance value, and the higher the power value that can be secured even if the system lower limit voltage is raised. Therefore, it becomes possible to secure the maximum MG output torque that is improved by increasing the system lower limit voltage.

4) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The battery output possible power line VP is set such that the higher the charging power amount (battery SOC) of the battery 4 is, the higher the system lower limit voltage is increased.
The higher the battery SOC, the smaller the battery internal resistance value, and the higher the power value that can be secured even when the system lower limit voltage is raised. Therefore, it is possible to further secure the maximum MG torque that is improved by increasing the system lower limit voltage.

5) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The battery output possible power line VP is set to the side where the system lower limit voltage is increased as the degree of deterioration of the battery 4 is smaller.
The smaller the battery deterioration level, the smaller the battery internal resistance value, and the higher the power value that can be secured even when the system lower limit voltage is raised. Therefore, it is possible to further secure the maximum MG torque that is improved by increasing the system lower limit voltage.

6) The electric power control method for the electric vehicle according to the first embodiment is as follows:
When the predetermined termination condition is satisfied, the raised system lower limit voltage is returned to the normal value regardless of the battery state.
Since the maximum battery output performance is limited when the system lower limit voltage is raised, ensure the maximum battery output performance by returning the system lower limit voltage to the normal value under the specified termination conditions. Can do.

7) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The predetermined termination condition includes a case where a difference between the voltage of the battery 4 and the system lower limit voltage becomes equal to or less than a threshold value Vlim after the system lower limit voltage is increased.
When the battery voltage approaches the system lower limit voltage shown on the left, the battery actual value is close to the output limit value when the system lower limit voltage is assumed. For this reason, battery output power can be improved by lowering the system lower limit voltage to a normal value.

8) The electric power control method for the electric vehicle according to the first embodiment is as follows:
The predetermined termination condition includes a case where the output time of the battery 4 or more continues for a threshold value tlim or more after the system lower limit voltage increases.
The process of increasing the system lower limit voltage is set assuming a certain duration of battery output. For this reason, when the output exceeding the predetermined value of the battery 4 continues beyond the threshold tlim corresponding to the assumed duration, the battery voltage may fall below the system lower limit voltage.
Therefore, when the output of the battery 4 exceeds a predetermined value exceeds the threshold tlim, the maximum MG torque is lowered and the battery output power is improved by lowering the system lower limit voltage to the normal value. Can do.

9) The electric power control method for the electric vehicle according to the first embodiment is as follows:
When the system lower limit voltage is returned to the normal value when a predetermined termination condition is satisfied, the system lower limit voltage is gradually decreased.
Therefore, it is possible to suppress a change when the system lower limit voltage is lowered in a state where the maximum MG torque is output, and to suppress the driver from feeling uncomfortable.

10) The electric power control apparatus for an electric vehicle according to the first embodiment
A motor generator MG serving as a drive source of the vehicle;
A battery 4 for supplying power to the motor generator MG;
A detection device (each sensor and switch) for detecting a vehicle state including a battery state;
An integrated controller 10 as a power controller that raises the system lower limit voltage above the normal value at the time of a request to increase the system lower limit voltage based on detection by the detection device;
An electric vehicle power control apparatus comprising:
When the system lower limit voltage increases, the integrated controller 10 obtains the battery state detected by the detection device, further obtains the battery output power characteristic that changes according to the battery state, and obtains the motor output characteristic according to the motor rotation speed. The system lower limit voltage is set according to the battery output power characteristic and the motor output characteristic.
Therefore, the same effect as in 1) above is achieved.
That is, by setting the system lower limit voltage in accordance with the motor output characteristics in addition to the battery output power characteristics, it becomes possible to increase the maximum MG torque compared to the case where the system lower limit voltage is set only based on the battery output power characteristics. .
As a result, it is possible to obtain a larger motor output while suppressing overdischarge of the battery by setting the system lower limit voltage, and it is possible to prevent the driver from feeling uncomfortable because the driver required torque cannot be obtained. .
In particular, it is more effective to increase the maximum MG torque in an inexpensive system that does not have a boost converter as in the first embodiment.

  As mentioned above, although the electric power control method supplement and electric power control apparatus of the electric vehicle of this invention were demonstrated based on embodiment, a concrete structure is not restricted to this embodiment, Each of Claims Design changes and additions are permitted without departing from the scope of the claimed invention.

For example, in the embodiment, a hybrid vehicle including an engine and a motor as drive sources is shown as the electric vehicle. However, the present invention can also be applied to an electric vehicle including only a motor as a drive source.
In the first embodiment, the system lower limit voltage is set to the system lower limit voltage and the maximum output value based on the lower limit voltage according to the battery output power characteristic and the motor output characteristic. It is not limited. For example, a certain margin may be secured from the intersection and the system lower limit voltage may be set below the intersection. Or, conversely, the system lower limit voltage may be set above the intersection so that the discomfort does not occur even when the maximum output is lower than the output by the system lower limit voltage.
In the first embodiment, the battery output power characteristic is set by referring to the battery temperature, the battery SOC, the battery deterioration degree, and the output duration time. However, the present invention is not limited to this. Any one of these conditions may be set, or conditions other than these conditions may be added.
In the first embodiment, an example of gradually decreasing the increased system lower limit voltage to the normal value due to establishment of a predetermined termination condition has been described. However, the present invention is not limited to this. The normal value may be restored.

1 Engine Controller 2 Motor Controller 3 Inverter 4 Battery 10 Integrated Controller (Power Controller)
AT automatic transmission CL1 first clutch CL2 second clutch MG motor generator MP MG maximum power line (motor output characteristics)
MTmax Maximum MG torque Nm Motor rotation speed tlim Threshold Vlim Threshold VP Battery output possible power line (battery output power characteristics)
XP intersection

Claims (10)

A motor as a drive source of the vehicle;
A battery for supplying power to the motor;
A detection device for detecting a vehicle state including the battery state;
As a system for driving the motor, an inverter connected to the battery and the motor, and applying a multi-phase alternating current to the motor by electric power supplied from the battery,
Based on the detection of the detecting device, the high output power required of the motor by the driver taking out power increases from the battery, increase request determining when the system minimum voltage is usable lower limit voltage of the battery As an electric vehicle power control method for raising the system lower limit voltage from the normal value,
When the system lower limit voltage is increased, a battery output power characteristic that changes in accordance with a battery state detected by the detection device is determined, and a motor output characteristic that corresponds to the rotational speed of the motor is determined.
An electric vehicle power control method, wherein the system lower limit voltage is set based on a voltage at which a maximum output is obtained in each of the battery output power characteristic and the motor output characteristic. In the electric power control method of the electric vehicle according to claim 1,
The electric power control method for an electric vehicle, wherein the system lower limit voltage is set based on an intersection of the battery output power characteristic with respect to the system lower limit voltage and the motor output characteristic with respect to the system lower limit voltage. In the electric power control method of the electric vehicle according to claim 1 or 2,
The electric power control method for an electric vehicle, wherein the battery output power characteristic is set to increase the system lower limit voltage as the temperature of the battery is higher. In the electric power control method of the electric vehicle according to any one of claims 1 to 3,
The electric power control method for an electric vehicle, wherein the battery output power characteristic is set to increase the system lower limit voltage as the charge power amount of the battery is higher. In the electric power control method of the electric vehicle according to any one of claims 1 to 4,
The electric power control method for an electric vehicle, wherein the battery output power characteristic is set to increase the system lower limit voltage as the degree of deterioration of the battery is smaller. In the electric power control method of the electric vehicle according to any one of claims 1 to 5,
An electric vehicle power control method characterized in that, when a predetermined termination condition is satisfied, the raised system lower limit voltage is returned to a normal value regardless of the battery state. In the electric vehicle power control method according to claim 6,
The electric power control method for an electric vehicle, wherein the predetermined termination condition includes a case where a difference between the battery voltage and the system lower limit voltage becomes equal to or less than a threshold value after the system lower limit voltage is increased. In the electric power control method of the electric vehicle according to claim 6 or 7,
The electric power control method for an electric vehicle characterized in that the predetermined end condition includes a case where an output time of a predetermined value or more of the battery continues for a threshold value or more after the system lower limit voltage is increased. In the electric power control method of the electric vehicle according to any one of claims 6 to 8,
An electric vehicle power control method characterized by gradually reducing the system lower limit voltage when returning the system lower limit voltage to a normal value due to establishment of the predetermined termination condition. A motor as a drive source of the vehicle;
A battery for supplying power to the motor;
A detection device for detecting a vehicle state including the battery state;
As a system for driving the motor, an inverter connected to the battery and the motor, and applying a multi-phase alternating current to the motor by electric power supplied from the battery,
Based on the detection of the detecting device, the high output power required of the motor by the driver taking out power increases from the battery, increase request determining when the system minimum voltage is usable lower limit voltage of the battery as a power controller that increases than the value of the normal of the system lower limit voltage,
An electric vehicle power control apparatus comprising:
The power controller obtains a battery state detected by the detection device when the system lower limit voltage increases, further obtains a battery output power characteristic that changes in accordance with the battery state, and responds to the rotation speed of the motor. An electric power control apparatus for an electric vehicle, wherein a motor output characteristic is obtained, and the system lower limit voltage is set based on a voltage at which a maximum output is obtained in each of the battery output power characteristic and the motor output characteristic.