JP2024111700A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable abrupt change of acceleration and deceleration of a vehicle caused by ON/OFF of auxiliary equipment operated by power from a battery to be suppressed in a scene where input/output limits of the battery is severe.

SOLUTION: A vehicle control device is provided with an electronic control unit controlling power consumption of auxiliary equipment. The electronic control unit executes at least one of: a first slow-change processing for slowly reducing the power consumption of the auxiliary equipment toward 0 when stopping the operation of the auxiliary equipment at the time when a first condition that an absolute value of the input limit as an allowable maximum charging power of the battery becomes a first threshold value or lower is established during regenerative running; and a second slow-change processing for slowly increasing the power consumption of the auxiliary equipment toward a prescribed electric power value when starting the operation of the auxiliary equipment at the time when a second condition that an absolute value of the output limit as an allowable maximum discharge power of the battery becomes a second threshold value or smaller is established during power running.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

This disclosure relates to a vehicle control device.

Patent Document 1 discloses a vehicle control device. When the battery is fully charged, the control device controls the vehicle's air conditioner so that the compressor of the air conditioner is operated with power generated by regenerative braking to compress and liquefy the air conditioner's refrigerant.

JP 2020-137335 A

In a vehicle in which the regenerative power/driving power of the electric motor is controlled while limiting the charging/discharging power of the battery so as not to exceed the input/output limits of the battery, it is necessary to suppress sudden changes in the acceleration/deceleration of the vehicle caused by turning on/off the auxiliary equipment that runs on power from the battery.

This disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle control device that can suppress sudden changes in the acceleration and deceleration of the vehicle caused by turning on/off auxiliary equipment that runs on power from the battery in situations where there are strict input/output restrictions on the battery.

The vehicle control device according to the present disclosure controls a vehicle having a battery, a powertrain, and an auxiliary device. The powertrain includes an electric motor that is operated by electric power from the battery, and is configured to be able to perform regenerative running using the electric motor as a generator and power running using the electric motor. The auxiliary device operates by electric power from the battery. The control device includes an electronic control unit that controls the power consumption of the auxiliary device. The electronic control unit executes at least one of a first gradual change process that gradually reduces the power consumption of the auxiliary device toward zero when the operation of the auxiliary device is stopped when a first condition is satisfied during regenerative running, in which the absolute value of the input limit as the maximum allowable charging power of the battery is equal to or less than a first threshold value, and a second gradual change process that gradually increases the power consumption of the auxiliary device toward a predetermined power value when the operation of the auxiliary device is started when a second condition is satisfied during power running, in which the absolute value of the output limit as the maximum allowable discharging power of the battery is equal to or less than a second threshold value.

According to the present disclosure, in situations where there are strict input/output restrictions on the battery, it becomes possible to suppress sudden changes in the acceleration/deceleration of the vehicle caused by turning on/off auxiliary equipment that runs on power from the battery.

1A is a diagram showing a schematic configuration of a vehicle according to an embodiment, and FIG. 1B is a flowchart showing a process for slowly changing the power consumption of an auxiliary device according to the embodiment. 11A to 11C are diagrams for explaining the "first slow-changing process" according to the embodiment in comparison with a comparative example. 11A to 11C are diagrams for explaining the "second slow-changing process" according to the embodiment in comparison with a comparative example.

The embodiments of the present disclosure will be described with reference to the attached drawings.

1. Example of Vehicle Configuration Fig. 1(A) is a diagram showing a schematic configuration of a vehicle 1 according to an embodiment. The vehicle 1 includes a power train 10, a battery 12, a battery temperature regulator 18, an electronic control unit (ECU) 20, various sensors 30, and auxiliary equipment 40.

The power train 10 includes an electric motor 14 and a power control unit (PCU) 16. The electric motor 14 is operated by power from the battery 12. The PCU 16 is a power conversion device including an inverter for driving the electric motor 14. The PCU 16 controls the electric motor 14 by using the power of the battery 12 based on a command from the ECU 20. More specifically, under the control of the PCU 16, the electric motor 14 generates a powering torque Tmd. Also, under the control of the PCU 16, the electric motor 14 also functions as a generator that generates a regenerative torque (negative torque) Tmr by being driven by the rotation of the wheels during deceleration of the vehicle. The battery temperature regulator 18 is controlled by the ECU 20 to regulate the temperature (thermal management) of the battery 12 by using the power supplied from the battery 12.

The above-described powertrain 10 allows electric running (EV running) using the electric motor 14. More specifically, when the vehicle decelerates, regenerative running can be performed using the electric motor 14 as a generator. In addition, when the vehicle accelerates, power running can be performed using the electric motor 14. The vehicle 1 is an electric vehicle, for example, a battery electric vehicle (BEV).

The ECU 20 is a computer that controls the vehicle 1, and corresponds to an example of a "vehicle control device" according to the present disclosure. The ECU 20 includes a processor 22 and a storage device 24. The processor 22 executes various processes. The various processes include processes related to the control of the power (motor power) Pm of the electric motor 14, as well as processes related to the control of power consumption of the auxiliary device 40, which will be described later. The storage device 24 stores various information necessary for the processes performed by the processor 22. The various processes performed by the ECU 20 are realized by the processor 22 executing computer programs stored in the storage device.

The various sensors 30 include, for example, a temperature sensor that detects the temperature of the battery 12, a current sensor that detects the charge/discharge current of the battery 12, a vehicle speed sensor that detects the speed of the vehicle 1, a rotation angle sensor that detects the rotation angle of the electric motor 14, an accelerator pedal sensor, and a brake pedal sensor. The ECU 20 calculates the state of charge (SOC) of the battery 12 based on the charge/discharge current detected by the current sensors.

The auxiliary equipment 40 operates using power from the battery 12. The auxiliary equipment 40 is, for example, an air conditioner. The air conditioner provides air conditioning (for example, cooling and heating) for the interior of the vehicle 1. Instead of an air conditioner, the "auxiliary equipment" according to the present disclosure may be, for example, a DC/DC converter that reduces the voltage of the battery 12 to supply power to devices such as the ECU 20. Alternatively, the auxiliary equipment may be, for example, an alternating current (AC) power supply device that uses power from the battery 12 to supply power to devices such as home appliances.

2. Control of Auxiliary Power Consumption (Auxiliary Power) First, basic operations during electric running including regenerative running and power running will be described. The ECU 20 calculates a required torque Treq, which is the torque (motor torque) of the electric motor 14 requested by the driver of the vehicle 1. The required torque Treq is calculated based on, for example, the depression amount of the accelerator pedal and the brake pedal and the vehicle speed. During electric running, the motor torque Tm corresponding to the required torque Treq calculated in this way is not necessarily always output as is. That is, the motor torque Tm (regenerative torque Tmr or power running torque Tmd) can be limited as follows.

The power allowed for charging the battery 12 during regenerative running has an upper limit (i.e., the maximum allowable charging power) based on, for example, the temperature and SOC of the battery 12. Hereinafter, this upper limit is referred to as the "input limit Win". Similarly, the power allowed for discharging the battery 12 during power running has an upper limit (i.e., the maximum allowable discharge power) based on, for example, the temperature and SOC of the battery 12. Hereinafter, this upper limit is referred to as the "output limit Wout". Note that in this specification, the sign of the power is positive when the battery 12 is discharging and negative when it is charging. For this reason, the input limit Win is a negative value and the output limit Wout is a positive value.

The required torque Treq is basically limited based on the input/output limits Win and Wout as follows. That is, when the motor power Pm corresponding to the product of the required torque Treq and the rotation speed (motor rotation speed) of the electric motor 14 is within the range of the input/output limits Win or Wout, the ECU 20 controls the PCU 16 so that the motor torque Tm corresponding to the required torque Treq is output from the electric motor 14. On the other hand, when the motor power Pm corresponding to the required torque Treq exceeds the input/output limits Win or Wout, the ECU 20 controls the PCU 16 so that the motor torque Tm corresponding to the motor power Pm limited so as not to exceed the input/output limits Win or Wout is output from the electric motor 14.

Here, during regenerative/powered running, the input limit Win/output limit Wout may become strict, for example, as in the deceleration/acceleration scenes described below with reference to Figures 2(A) and 3(A). In such a scene where the input/output limit Win or Wout is strict, it is necessary to suppress a sudden change in the acceleration/deceleration of the vehicle 1 caused by turning on/off the auxiliary equipment 40 that operates with power from the battery 12.

FIG. 1(B) is a flowchart relating to the gradual change processing of the power consumption Pa of the auxiliary device 40 according to the embodiment. In view of the above problem, in this embodiment, the ECU 20 executes the processing of the flowchart shown in FIG. 1(B). The processing of this flowchart is executed while the vehicle 1 is running in regenerative mode or powered mode. In the following description, the power consumption Pa of the auxiliary device 40 is also simply referred to as auxiliary power Pa.

In step S100, the ECU 20 (processor 22) determines whether a first condition is satisfied, that is, the input limit Win, which is a negative value, is equal to or greater than a predetermined negative threshold value TH1, or a second condition is satisfied, that is, the output limit Wout, which is a positive value, is equal to or less than a predetermined positive threshold value TH2 (second threshold value). The satisfaction of the first condition means that a scene in which the input limit Win is strict has arrived. Similarly, the satisfaction of the second condition means that a scene in which the output limit Wout is strict has arrived. If the first condition or the second condition is satisfied (step S100; Yes), the process proceeds to step S102. On the other hand, if neither the first nor the second condition is satisfied (step S100; No), the process proceeds to return. The absolute value of the negative threshold value TH1 corresponds to an example of the "first threshold value" according to the present disclosure.

In step S102, the ECU 20 executes a "slow-change process" for the auxiliary power Pa. Specifically, when the first condition (Win≧TH1) is satisfied during regenerative driving, i.e., when the input limit Win is strict, the ECU 20 executes the "first slow-change process" as described in detail later in Section 2-1. On the other hand, when the second condition (Wout≦TH2) is satisfied during power driving, i.e., when the output limit Wout is strict, the ECU 20 executes the "second slow-change process" as described in detail later in Section 2-2. The process then proceeds to step S104.

The "vehicle control device" according to the present disclosure may be configured to execute only one of the first gentle change processing during regenerative driving and the second gentle change processing during power driving.

In step S104, the ECU 20 controls the thermal management of the battery 12. This process of step S104 is executed when the first condition is satisfied. The thermal management control here is executed so that the surplus power caused by the gradual decrease in the auxiliary power Pa by the first gradual change process is consumed by utilizing the thermal management of the battery 12. More specifically, the ECU 20 controls the supply of electricity to the battery temperature regulator 18 to consume the surplus power.

2-1. First gradual change process during regenerative driving (gradual decrease)
2A is a time chart for explaining the operation of a comparative example that does not include the "first gentle change processing" according to the embodiment. Fig. 2A shows a deceleration scene in which the auxiliary device 40 is stopped when a first condition indicating that the input limit Win is strict is satisfied during regenerative running.

In the vehicle 1, the regenerative power Pmr generated during regenerative driving is used to charge the battery 12 and operate the auxiliary device 40. More specifically, the regenerative power Pmr is supplied to the battery 12. When the auxiliary device 40 is operated, the regenerative power Pmr is supplied not only to the battery 12 but also to the auxiliary device 40. Therefore, the maximum regenerative power Pmrmax (negative value) that can be generated when the auxiliary device 40 is operating (auxiliary device on) has an absolute value equal to the sum of the absolute value of the input limit Win and the auxiliary device power value Pa1. On the other hand, the maximum regenerative power Pmrmax when the auxiliary device 40 is not operating (auxiliary device off) and the auxiliary device power Pa is 0 has an absolute value equal to the absolute value of the input limit Win. Therefore, when the auxiliary device 40 is switched from on to off while the regenerative power Pmr has reached the maximum regenerative power Pmrmax during regenerative driving, the maximum regenerative power Pmrmax is reduced by the auxiliary device power value Pa1. In other words, the regenerative power Pmr that can actually be generated is limited to a small value.

In FIG. 2(A), at time t11, the driver releases the accelerator pedal. As a result, deceleration begins. That is, the vehicle deceleration occurs and the vehicle speed decreases. Note that in FIG. 2(A) (and FIG. 2(B) described below), the decrease in vehicle speed is simply represented by a straight line. Furthermore, the auxiliary device 40 is, for example, an air conditioning device, and the auxiliary device power value Pa1 is, for example, 7 kW. In the scene shown in FIG. 2(A), the input limit Win is -7.5 kW for an example of the auxiliary device power value Pa1 of 7 kW. That is, FIG. 2(A) illustrates a deceleration scene in which the input limit Win is strict. Furthermore, deceleration begins with the auxiliary device 40 in an on state.

The required torque Treq is a negative value in response to a deceleration request from the driver. As an example, the required torque Treq is set to decrease over time toward the negative value Treq1. The electric motor 14 is basically controlled to generate a regenerative torque Tmr as the motor torque Tm corresponding to the required torque Treq.

Time t12 corresponds to the time when the absolute value of the regenerative power Pmr, which corresponds to the product of the generated regenerative torque Tmr and the motor rotation speed, reaches the sum of the absolute value of the input limit Win and the auxiliary power value Pa1 (i.e., the absolute value of the maximum regenerative power Pmrmax). As time t12 passes, the regenerative power Pmr is limited so that it does not exceed the maximum regenerative power Pmrmax. As a result, the regenerative torque Tmr is limited with respect to the required torque Treq, as shown in FIG. 2(A). Accordingly, the vehicle deceleration becomes constant.

Time t13 corresponds to the time when the auxiliary device 40 changes from on to off under the condition that the regenerative torque Tmr is restricted. At time t13, the auxiliary device power Pa becomes zero, and the input limit Win (maximum regenerative power Pmrmax) suddenly decreases. Then, in response to this sudden decrease in the input limit Win, the limit amount of the regenerative power Pmr increases sharply, and as a result, the regenerative torque Tmr suddenly decreases as shown in FIG. 2(A). As a result, a sudden drop (dropout) in the vehicle deceleration occurs due to the auxiliary device 40 being turned on and off.

On the other hand, FIG. 2(B) is a time chart for explaining the operation involving the "first slow change processing" according to the embodiment. The operation shown in FIG. 2(B) is illustrated for the same deceleration scene as FIG. 2(A). The first slow change processing is to slowly reduce the auxiliary power Pa from the auxiliary power value Pa1 to 0 when the operation of the auxiliary 40 is stopped while the first condition (Win≧TH1) is satisfied during regenerative driving, as in the deceleration scene shown in FIG. 2(B).

Specifically, in FIG. 2B, when the auxiliary device 40 is stopped at time t13, the ECU 20 controls the power supply to the auxiliary device 40 so that the auxiliary device power Pa decreases gently (gradually) rather than decreasing the auxiliary device power Pa in a stepped manner from the auxiliary device power value Pa1 to 0. More specifically, the ECU 20 gradually decreases the auxiliary device power Pa at as high a rate of decrease as possible while making it difficult for the driver to feel uncomfortable due to a change in vehicle deceleration accompanying the stopping of the auxiliary device 40 (in other words, while being acceptable in terms of drivability). In an example in which the auxiliary device 40 is an air conditioning device, the rate of decrease is, for example, -5 kW/sec.

Time t14 corresponds to the time when the auxiliary power Pa, which has been gradually decreased as described above, reaches 0. In addition, the surplus power resulting from the gradual decrease in the auxiliary power Pa is consumed by utilizing the thermal management of the battery 12, as already described.

Furthermore, the reduction (reduction in absolute value) of the input limit Win associated with the stopping of the auxiliary device 40 is also performed slowly in response to the slowly decreasing auxiliary device power Pa, as shown in FIG. 2(B). As a result, the regenerative torque Tmr also slowly decreases in response to the slowly decreasing input limit Win. This makes it possible to make the change (decrease) in the vehicle deceleration caused by turning the auxiliary device 40 on and off more gradual.

2-2. Second slow change process during powered running (slow increase)
3A is a time chart for explaining the operation of a comparative example that does not include the "second gentle change process" according to the embodiment. Fig. 3A shows an acceleration scene in which the auxiliary device 40 is started when the second condition indicating that the output limit Wout is strict is satisfied during power running.

In the vehicle 1, the electric power charged in the battery 12 is output (discharged) during power running to drive the electric motor 14 and operate the auxiliary equipment 40. Therefore, the output limit Wout when the auxiliary equipment 40 is started (auxiliary equipment on) is the sum of the maximum power running power Pmdmax that can be output and the auxiliary equipment power value Pa1. On the other hand, when the auxiliary equipment 40 is not operating (auxiliary equipment off), the entire output limit Wout can be allocated to the power running power Pmd. In other words, the output limit Wout is equal to the maximum power running power Pmdmax. Therefore, if the auxiliary equipment 40 is switched from off to on when the power running power Pmd has reached the maximum power running power Pmdmax during power running, the output limit Wout (maximum power running power Pmdmax) is reduced by the auxiliary equipment power value Pa1. In other words, the power running power Pmd that can actually be generated is limited to a small value.

Figure 3 (A) shows a scene in which the vehicle 1 is accelerating with the driver's accelerator pedal depression amount constant. In this example, the output limit Wout is 7.5 kW for an example of an auxiliary power value Pa1 of 7 kW. That is, Figure 3 (A) shows an example of an acceleration scene in which the output limit Wout is strict. Also, acceleration is started with the auxiliary 40 turned off.

The required torque Treq is a positive value in response to an acceleration request from the driver. As an example, the required torque Treq is constant in response to a constant accelerator pedal depression. The electric motor 14 is basically controlled to generate a powering torque Tmd as a motor torque Tm in response to the required torque Treq.

First, the period before time t21 will be described. During this period, the power Pmd, which corresponds to the product of the power torque Tmd and the motor speed, is limited so as not to exceed the output limit Wout (i.e., the maximum power Pmdmax). As a result, the power torque Tmd is limited relative to the required torque Treq.

Time t21 corresponds to the time when the auxiliary 40 goes from off to on under the condition that the traction torque Tmd is limited. After time t21, the auxiliary power Pa increases rapidly from 0 to the auxiliary power value Pa1. More specifically, the rate of increase of the auxiliary power Pa corresponds to the responsiveness (in other words, the responsiveness of the course of events) according to the specifications of the auxiliary 40 (air conditioner). In response to this sudden increase in the auxiliary power Pa, the output limit Wout (maximum traction power Pmdmax) is suddenly reduced as shown in FIG. 3(A). Then, as a result of the sudden decrease in the output limit Wout causing a sudden increase in the limit amount of the traction power Pmd, the traction torque Tmd is suddenly reduced as shown in FIG. 3(A). As a result, a sudden drop (dropout) in the vehicle acceleration due to the on/off of the auxiliary 40 occurs. In the example shown in FIG. 3(A), the power torque Tmd after time t21 remains constant at the value Tmd1 after the sudden decrease.

On the other hand, FIG. 3(B) is a time chart for explaining the operation involving the "second gentle change processing" according to the embodiment. The operation shown in FIG. 3(B) is illustrated for the same acceleration scene as FIG. 3(A). The second gentle change processing is to gently increase the auxiliary power Pa from 0 to the auxiliary power value Pa1 (predetermined power value) when the operation of the auxiliary 40 is started when the second condition (Wout≦TH2) is satisfied during powered running, as in the acceleration scene shown in FIG. 3(B).

Specifically, in FIG. 3B, when the auxiliary device 40 is started at time t21, the ECU 20 does not increase the auxiliary power Pa with the above-mentioned "natural responsiveness (dashed line in FIG. 3B)," but controls the power supply to the auxiliary device 40 so that the auxiliary power Pa increases gently (gradually) compared to the natural responsiveness. More specifically, the ECU 20 gently increases the auxiliary power Pa at as high an increase rate as possible while making it difficult for the driver to feel uncomfortable due to changes in vehicle acceleration accompanying the start of the auxiliary device 40 (in other words, while being acceptable in terms of drivability). In an example in which the auxiliary device 40 is an air conditioning device, the increase rate is, for example, 5 kW/sec.

Time t22 corresponds to the time when the auxiliary power Pa, which has increased slowly as described above, reaches the auxiliary power value Pa1. In addition, the output limit Wout associated with the start of the auxiliary 40 is also gradually reduced in accordance with the slowly increasing auxiliary power Pa, as shown in FIG. 3(B). As a result, the powering torque Tmd also decreases slowly in accordance with the slowly increasing output limit Wout. This makes it possible to make the change (decrease) in vehicle acceleration caused by turning the auxiliary 40 on and off gentler.

3. Effects As described above, the "vehicle control device" according to this embodiment has a function of gradually decreasing/increasing the power consumption Pa of the auxiliary device 40 when stopping/starting the auxiliary device 40. Therefore, in a deceleration/acceleration scene where the input limit Win/output limit Wout of the battery 12 is severe, it is possible to suppress a sudden change in the acceleration/deceleration rate of the vehicle 1 caused by turning on/off the auxiliary device 40 that operates with power from the battery 12, compared to a case where the auxiliary power Pa is suddenly decreased/increased.

1 Vehicle, 10 Power train, 12 Battery, 14 Electric motor, 20 Electronic control unit (ECU), 30 Sensor, 40 Auxiliary equipment

Claims (1)

Batteries and
a power train including an electric motor operated by electric power from the battery, the power train being capable of performing regenerative running using the electric motor as a generator and power running using the electric motor;
An auxiliary device that operates using power from the battery;
A control device for controlling a vehicle comprising:
an electronic control unit for controlling the power consumption of the auxiliary device;
The electronic control unit includes:
a first gradual change process for gradually decreasing the power consumption of the auxiliary equipment toward zero when the operation of the auxiliary equipment is stopped while a first condition is satisfied during the regenerative running, the first gradual change process being a first condition that an absolute value of an input limit as a maximum allowable charging power of the battery is equal to or less than a first threshold value;
a second gradual change process for gradually increasing the power consumption of the auxiliary equipment toward a predetermined power value when the auxiliary equipment starts to operate when a second condition is satisfied during the power running, the second condition being that an absolute value of an output limit as a maximum allowable discharge power of the battery is equal to or less than a second threshold value;
A vehicle control device that executes at least one of the above.

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