阅读说明：本技术 车辆 (Vehicle with a steering wheel ) 是由 福池孝之 于 2019-05-22 设计创作，主要内容包括：本发明提供一种车辆,在实际SOC为上限值SOC(0)以上(S200中为是)且车辆为准备-断开状态的情况下(S202中为是),ECU执行包括在SMR为切断状态时(S204中为是)使用放电装置来使蓄电池放电的步骤(S206)和在SMR不为切断状态时(S204中为否)使用MG(10)来使蓄电池放电的步骤(S208)的处理。(When the actual SOC is not less than the upper limit SOC (0) (YES in S200) and the vehicle is in a ready-to-off state (YES in S202), an ECU executes processing including a step (S206) of discharging a battery using a discharging device when an SMR is in an off state (YES in S204) and a step (S208) of discharging the battery using an MG (10) when the SMR is not in the off state (NO in S204).)

1. A vehicle is provided with:

a rotating electric machine coupled to a drive wheel of a vehicle;

An electrical storage device;

A power conversion device that bidirectionally converts electric power between the rotating electrical machine and the electrical storage device; and

A control device that controls the power conversion device,

The control device permits charging exceeding an upper limit value of the SOC of the power storage device when the vehicle is in a regenerative braking state using the rotating electrical machine,

The control device executes discharge control for discharging the electrical storage device when there is a request for stopping a system of the vehicle and the SOC of the electrical storage device is greater than the upper limit value.

2. The vehicle according to claim 1, wherein,

In the case where there is a system stop request of the vehicle and the SOC of the electrical storage device is greater than the upper limit value, the control device executes the discharge control until the SOC of the electrical storage device reaches the upper limit value.

3. The vehicle according to claim 1 or 2,

the vehicle further includes:

A relay circuit provided between the power storage device and the power conversion device; and

A discharging device that is not connected via the relay circuit and that is used to discharge the electrical storage device,

The control device executes the discharge control using an electric device on the power conversion device side of the relay circuit when the relay circuit is in the on state,

the control device executes the discharge control using the discharge device when the relay circuit is in an off state.

4. The vehicle according to claim 3, wherein,

the electrical apparatus includes the rotating electrical machine,

The control device executes field weakening control of the rotating electrical machine as the discharge control.

5. The vehicle according to claim 3, wherein,

The electric storage device includes a plurality of electric storage elements,

The discharge device includes equalization circuits that are provided in the plurality of power storage elements, respectively, and equalize the respective SOCs of the power storage elements.

Technical Field

The present disclosure relates to control of a vehicle equipped with a power storage device that can be charged using electric power generated during regenerative braking.

Background

In recent years, as an environmentally friendly vehicle, an electrically powered vehicle that is mounted with a power storage device (for example, a secondary battery or the like) and that travels by supplying electric power stored in the power storage device to a drive source such as a motor generator or the like has been attracting attention. There is known a technique for improving energy efficiency by charging a power storage device by regenerating energy (i.e., regenerative braking) in a motor generator when an accelerator is turned off or a brake is turned on, such as when an electrically powered vehicle is going downhill. However, when the SOC (State Of Charge) Of the power storage device is in the vicinity Of the upper limit value, the energy generated by regenerative braking may not be sufficiently recovered.

Regarding such a problem, for example, japanese patent application laid-open No. 2002-051405 discloses a technique for increasing the upper limit value of the SOC of the power storage device to increase the actual capacity, thereby efficiently performing charging at the time of regenerative braking.

In the electrically powered vehicle having the above configuration, when the power storage device is charged in a state where the upper limit value of the SOC of the power storage device is increased, although the regenerative energy can be efficiently recovered, the SOC of the power storage device may exceed the initial upper limit value. When the vehicle is left in this state, the power storage device may be placed in a state where the SOC exceeds the initial upper limit value, and deterioration of the power storage device may be promoted.

Disclosure of Invention

An object of the present disclosure is to provide a vehicle that efficiently recovers energy and suppresses deterioration of an electric storage device during regenerative braking.

A vehicle according to an aspect of the present disclosure includes: a rotating electric machine coupled to a drive wheel of a vehicle; an electrical storage device; a power conversion device that bidirectionally converts electric power between the rotating electric machine and the electrical storage device; and a control device for controlling the power conversion device. When the vehicle is in a regenerative braking state using the rotating electric machine, the control device allows charging exceeding an upper limit value of the SOC of the power storage device. The control device executes discharge control for discharging the power storage device when there is a request for stopping the system of the vehicle and the SOC of the power storage device is greater than the upper limit value.

In this way, in the case where the vehicle is in the regenerative braking state using the rotating electrical machine, charging exceeding the upper limit value of the SOC of the power storage device is permitted, and therefore, even when the SOC of the power storage device is in the vicinity of the upper limit value, regenerative energy can be efficiently recovered. When there is a request for stopping the system of the vehicle and the SOC of the power storage device is greater than the upper limit value, discharge control for discharging the power storage device is executed. Therefore, as compared with the case where the state where the SOC of the power storage device is greater than the upper limit value is maintained, deterioration of the power storage device when the vehicle is left for a long period of time can be suppressed.

In one embodiment, when there is a request for stopping the system of the vehicle and the SOC of the power storage device is greater than the upper limit value, the control device executes the discharge control until the SOC of the power storage device reaches the upper limit value.

In this way, when there is a request for stopping the system of the vehicle and the SOC of the power storage device is greater than the upper limit value, the discharge control is executed until the SOC of the power storage device reaches the upper limit value. Therefore, as compared with the case where the state where the SOC of the power storage device is greater than the upper limit value is maintained, deterioration of the power storage device when the vehicle is left for a long period of time can be suppressed.

In one embodiment, the vehicle further includes: a relay circuit provided between the power storage device and the power conversion device; and a discharging device that is not connected via the relay circuit and discharges the electrical storage device. When the relay circuit is in the on state, the control device executes the discharge control using the electrical device on the power conversion device side of the relay circuit. The control device performs discharge control using the discharge device when the relay circuit is in the off state.

In this way, since the discharge control is executed using different devices depending on the state of the relay circuit, the power storage device in a state in which the SOC exceeds the upper limit value can be reliably discharged.

In one embodiment, the electrical device includes the rotating electrical machine. The control device executes field weakening control of the rotating electrical machine as discharge control.

Thus, the power storage device in a state in which the SOC exceeds the upper limit value can be quickly discharged without adding a new component for discharging the power storage device.

In one embodiment, the power storage device includes a plurality of power storage elements. The discharge device includes equalization circuits that are provided in the plurality of power storage elements, respectively, and equalize the respective SOCs of the power storage elements.

In this way, it is possible to reliably discharge the power storage device in a state in which the SOC exceeds the upper limit value without adding a new component for discharging the power storage device.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a block diagram schematically showing the overall configuration of a vehicle according to the present embodiment.

Fig. 2 is a diagram showing an example of the structure of the discharge device.

Fig. 3 is a diagram showing a relationship between the upper limit value Win of the charge power of the battery and the SOC.

Fig. 4 is a flowchart illustrating an example of the process of allowing charging exceeding the upper limit value of the SOC of the battery.

Fig. 5 is a diagram showing a relationship between the upper limit value Win of the charge power of the battery after the change and the SOC.

Fig. 6 is a flowchart showing an example of the process of the discharge control executed by the ECU.

Fig. 7 is a diagram for explaining a running environment of the vehicle 1 as a premise.

Fig. 8 is a diagram showing a relationship between the deceleration of the vehicle on a downhill and the vehicle speed.

fig. 9 is a time chart showing a change in SOC when the discharge control is executed.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

Hereinafter, a structure of an electric vehicle according to an embodiment of the present disclosure will be described as an example.

< Structure of vehicle >

Fig. 1 is a block diagram schematically showing the overall configuration of a vehicle 1 according to the present embodiment. The vehicle 1 includes a Motor Generator (MG) 10, a Power transmission gear 20, a drive wheel 30, a Power Control Unit (PCU) 40, a System Main Relay (SMR: System Main Relay)50, a charging Relay (hereinafter, CHR)60, a charging device 70, an inlet 80, a battery 100, a voltage sensor 210, a current sensor 220, a temperature sensor 230, a discharging device 240, an accelerator pedal stroke sensor 250, a brake pedal stroke sensor 260, a vehicle speed sensor 270, and an Electronic Control Unit (ECU: Electronic Control Unit) 300.

MG10 is, for example, a three-phase ac rotating electrical machine, and has a function as a motor (generator) and a function as a generator (generator). The output torque of the MG10 is transmitted to the drive wheels 30 via a power transmission gear 20, and the power transmission gear 20 includes a reduction gear, a differential device, and the like.

At the time of braking of the vehicle 1, the MG10 is driven by the drive wheels 30, and the MG10 operates as a generator. Accordingly, MG10 also functions as a brake device that performs regenerative braking for converting kinetic energy of vehicle 1 into electric power. Regenerative electric power generated by the regenerative braking force in MG10 is stored in battery 100.

the PCU40 is a power conversion device that bidirectionally converts electric power between the MG10 and the battery 100. The PCU40 includes, for example, an inverter and a converter that operate based on a control signal from the ECU 300.

The converter boosts the voltage supplied from battery 100 and supplies the boosted voltage to the inverter when battery 100 is discharged. The inverter converts dc power supplied from the converter into ac power and drives the motor generator 10.

on the other hand, the inverter converts ac power generated by the motor generator 10 into dc power and supplies the dc power to the converter during charging of the battery 100. The converter reduces the voltage supplied from the inverter to a voltage suitable for charging battery 100 and supplies the voltage to battery 100.

PCU40 stops the operation of the inverter and the converter based on a control signal from ECU300, thereby stopping charging and discharging. Note that PCU40 may be configured to omit a converter.

SMR50 is electrically connected to a power line connecting battery 100 and PCU 40. When SMR50 is closed (i.e., in an on state) in response to a control signal from ECU300, electric power can be transferred between battery 100 and PCU 40. On the other hand, when SMR50 is opened (i.e., in a disconnected state) in response to a control signal from ECU300, electrical connection between battery 100 and PCU40 is disconnected.

the CHR60 is electrically connected between the battery 100 and the charging device 70. When CHR60 is closed (i.e., in an on state) in response to a control signal from ECU300 and connector 150 of an external power supply is attached to inlet 80 described later, electric power can be transferred between battery 100 and charging device 70. On the other hand, when CHR60 is opened (i.e., in a disconnected state) in response to a control signal from ECU300, the electrical connection between battery 100 and charging device 70 is disconnected.

The inlet 80 is provided in an exterior part of the vehicle 1 together with a cover (not shown) such as a lid. The inlet 80 has a shape to which a connector 150 described later can be mechanically connected. Contacts are built in both the inlet 80 and the connector 150, and when the connector 150 is mounted in the inlet 80, the contacts contact each other to electrically connect the inlet 80 and the connector 150.

The connector 150 is connected to the system power supply 160 via a charging cable 170. Therefore, when connector 150 is connected to inlet 80 of vehicle 1, the electric power from system power supply 160 can be supplied to vehicle 1 via charging cable 170, connector 150, and inlet 80.

The charging device 70 is electrically connected to the battery 100 via the CHR60 and to the inlet 80. Charging device 70 converts ac power supplied from system power supply 160 into dc power in accordance with a control signal from ECU300 and outputs the dc power to battery 100. When connector 150 is attached to inlet 80, for example, charging device 70 charges battery 100 with electric power supplied from system power supply 160.

Battery 100 is a power storage device that stores electric power for driving MG 10. The battery 100 is a rechargeable dc power supply, and is configured such that a plurality of battery cells 110 are connected in series, for example. The battery cell 110 is a secondary battery such as a lithium ion secondary battery or a nickel metal hydride secondary battery.

The voltage sensor 210 detects a voltage Vb between terminals of each of the plurality of battery cells 110. Current sensor 220 detects current Ib input/output to/from battery 100. The temperature sensor 230 detects the temperature Tb of each of the plurality of battery cells 110. Each sensor outputs the detection result to ECU 300.

The discharge device 240 is connected to each of the plurality of battery cells 110, and discharges each of the plurality of battery cells 110 in accordance with a control signal from the ECU 300. The discharge device 240 includes, for example, a discharge resistor and a switch.

Fig. 2 is a diagram showing an example of the structure of the discharge device 240. As shown in fig. 2, the discharge device 240 is a circuit connected in parallel with the battery cell 110, and is a circuit in which a discharge resistor 240a and a switch 240b are connected in series.

With this configuration, when the switch 240b is turned on in response to a control signal from the ECU300, for example, the electric power of the battery cell 110 is discharged through the discharge resistor 240 a. The discharge device 240 is an equalization circuit that equalizes the SOC of each of the plurality of battery cells 110 by individually discharging the plurality of battery cells 110.

The accelerator pedal stroke sensor 250 detects an operation amount (hereinafter also referred to as an accelerator opening) of an accelerator pedal (not shown) of the vehicle 1. The brake pedal stroke sensor 260 detects an operation amount of a brake pedal (not shown) of the vehicle 1 (hereinafter also referred to as a brake pedal depression amount). The vehicle speed sensor 270 detects the speed of the vehicle 1 (hereinafter referred to as vehicle speed). Each sensor outputs the detection result to ECU 300.

ECU300 includes a CPU (Central Processing Unit) 301, a Memory (ROM (Read Only Memory)) 302, and a Random Access Memory (RAM) 302, and an input/output buffer (not shown). ECU300 controls each device so that vehicle 1 is in a desired state based on signals received from each sensor and information such as a map and a program stored in memory 302.

< control of charging/discharging of storage battery 100 >

The amount Of Charge stored in battery 100 is generally managed by SOC (State Of Charge) in which the current amount Of Charge is expressed in percentage with respect to the full Charge capacity. ECU300 has a function of sequentially calculating the SOC of battery 100 based on the detection values of voltage sensor 210, current sensor 220, and temperature sensor 230. Various known methods such as a method based on current value integration (coulomb counting) and a method based on estimation of Open Circuit Voltage (OCV) can be used as a method for calculating SOC.

During driving of the vehicle 1, the battery 100 is charged or discharged by regenerative electric power or discharge electric power of the MG 10. The ECU300 controls the output of the MG10 so as to output power for generating a driving force of the vehicle requested by the driver (a requested driving force set according to an accelerator opening degree) or a braking force (a requested deceleration force set according to a brake pedal depression amount, a vehicle speed) from the MG 10.

On the other hand, when vehicle 1 is in a stopped state and connector 150 is connected to inlet 80, ECU300 turns on CHR60 and operates charging device 70 to charge battery 100 with electric power from system power supply 160.

ECU300 continues charging until the SOC of battery 100 reaches upper limit value SOC (0), for example, and ends charging when the SOC of battery 100 reaches upper limit value SOC (0). More specifically, ECU300 sets an upper limit value Win of the charging power in accordance with the SOC of battery 100. ECU300 sets upper limit value Win of charging power to zero when SOC of battery 100 reaches upper limit value SOC (0), thereby ending charging.

fig. 3 is a diagram showing a relationship between upper limit value Win of charge power of battery 100 and SOC. The vertical axis of fig. 3 represents the upper limit value Win of the charging power. The horizontal axis of fig. 3 represents SOC. The broken line in fig. 3 represents the relationship between the upper limit value Win of the charging power in the battery 100 and the SOC.

As shown by the broken line in fig. 3, ECU300 maintains upper limit value Win of the charging power at predetermined value Win (0) for a period until SOC of battery 100 reaches SOC (1), for example. When the SOC is greater than SOC (1), ECU300 sets upper limit value Win of charging power such that the larger the SOC, the smaller the magnitude of upper limit value Win of charging power. When the SOC reaches SOC (0), ECU300 sets an upper limit Win as the charging power to zero. Since the upper limit value Win of the charging power is set to zero in this manner, the charging is terminated.

< charging processing based on regenerative braking when the vehicle 1 is descending a slope >

When the vehicle 1 having the above-described structure descends on a slope, energy efficiency can be improved by regenerating energy (i.e., regenerative braking) in the MG 10. However, for example, in the case where vehicle 1 is descending after the SOC of battery 100 is charged to upper limit value SOC (0) using system power supply 160, when the SOC of battery 100 is in the vicinity of upper limit value SOC (0), as described with reference to fig. 3, upper limit value Win as the charging power is set to zero, and charging is suppressed. Therefore, the energy generated by regenerative braking may not be sufficiently recovered.

To address such a problem, for example, when vehicle 1 is in a regenerative braking state, it is conceivable to execute a process that allows charging exceeding the upper limit value of the SOC of battery 100.

The following describes a process of allowing charging exceeding the upper limit value of the SOC of battery 100 with reference to fig. 4. Fig. 4 is a flowchart illustrating an example of the process of allowing charging exceeding the upper limit value of the SOC of battery 100. The process shown in this flowchart is repeatedly executed by the ECU300 shown in fig. 1 at predetermined processing cycles.

In step (hereinafter, step is described as S)100, ECU300 determines whether or not the accelerator is off and the vehicle is in a traveling state. ECU300 determines that the accelerator is off and during traveling, for example, when the vehicle speed is greater than a threshold value and the accelerator opening is smaller than a threshold value. The threshold value of the vehicle speed is a value indicating the vehicle speed at which regenerative braking is possible, and is, for example, a predetermined value. The threshold value of the accelerator opening degree is a value for determining that the accelerator opening degree is zero, and is, for example, a predetermined value. These thresholds are adapted by experiments and the like. If it is determined that the accelerator is off and the vehicle is traveling (yes in S100), the process proceeds to S102.

In S102, ECU300 determines whether or not the current SOC (hereinafter referred to as the actual SOC) is equal to or higher than upper limit SOC (0) of the SOC of battery 100 (i.e., whether or not the actual SOC reaches upper limit SOC (0)). ECU300 estimates the actual SOC of battery 100 using, for example, the detection results of voltage sensor 210, current sensor 220, and temperature sensor 230. If it is determined that the actual SOC is equal to or greater than the upper limit SOC (0) (yes in S102), the process proceeds to S104.

In S104, ECU300 allows charging exceeding upper limit SOC (0) of the SOC of battery 100.

Specifically, ECU300 changes the upper limit value of SOC of battery 100 from SOC (0) to SOC (2) larger than SOC (0).

fig. 5 is a diagram showing a relationship between the upper limit value Win of the charge power of the battery after the change and the SOC. The vertical axis of fig. 5 represents the upper limit value Win of the charging power. The horizontal axis of fig. 5 represents SOC. The broken line in fig. 5 indicates the relationship between the upper limit value Win of the charge power in battery 100 before the change and the SOC. The solid line in fig. 5 represents the relationship between the upper limit value Win of the charging power in battery 100 after the change and the SOC.

As shown by the solid line in fig. 5, ECU300 maintains upper limit value Win of the charging power at predetermined value Win (0) for a period until the actual SOC of battery 100 reaches SOC (0), for example. Then, when the actual SOC is larger than SOC (0), ECU300 sets upper limit value Win of charging power such that the larger the actual SOC is, the smaller the magnitude of upper limit value Win of charging power is. When the actual SOC reaches SOC (2), ECU300 sets an upper limit Win as the charging power to zero. Since the upper limit value Win of the charging power is set to zero in this manner, the charging is terminated. The difference between SOC (0) and SOC (2) is, for example, about several percent.

In S106, ECU300 does not permit charging exceeding upper limit SOC (0) of the SOC of battery 100. Specifically, ECU300 sets the upper limit value of the SOC of battery 100 to SOC (0). The charging control when the upper limit value is set to SOC (0) is the same as that described with reference to fig. 3, and therefore, detailed description thereof will not be repeated.

If it is determined that the vehicle is not traveling with the accelerator off (no in S100), or if it is determined that the actual SOC is less than the upper limit SOC (0) (no in S102), the process proceeds to S106.

By executing the above-described processing, when the user releases depression of the accelerator pedal during traveling of the vehicle 1 (yes in S100) and the actual SOC of the battery 100 becomes equal to or greater than the upper limit value SOC (0) (yes in S102), charging exceeding the upper limit value SOC (0) is allowed by changing the upper limit value of SOC from SOC (0) to SOC (2) (S104). Therefore, for example, when the vehicle 1 is in the regenerative braking state, the actual SOC is allowed to exceed the SOC (0). In this way, since charging is allowed while exceeding the upper limit SOC (0) of the SOC of battery 100, energy generated by regenerative braking can be efficiently recovered.

However, when charging exceeding the upper limit value of the SOC of battery 100 is permitted, battery 100 is left in a state where the actual SOC exceeds the upper limit value of the SOC when vehicle 1 is stopped or left. Therefore, there is a possibility that deterioration of the battery 100 is promoted.

Therefore, in the present embodiment, the ECU300 operates as follows. That is, ECU300 allows charging exceeding the upper limit value of the SOC of battery 100 when vehicle 1 is in the regenerative braking state using MG 10. When the travel of vehicle 1 is suppressed, ECU300 executes discharge control for discharging a portion of the SOC of battery 100 that exceeds the upper limit value.

In this way, when vehicle 1 is in the regenerative braking state using MG10, charging exceeding upper limit SOC (0) of the SOC of battery 100 is allowed, and therefore, even when the SOC of battery 100 is in the vicinity of upper limit SOC (0), regenerative energy can be efficiently recovered. In addition, when the travel of vehicle 1 is suppressed, the portion exceeding upper limit SOC (0) is discharged, and therefore, even when vehicle 1 is left for a long period of time, deterioration of battery 100 can be suppressed.

< processing contents related to discharge control of storage battery 100 >

Hereinafter, the process executed by the ECU300 will be described with reference to fig. 6. Fig. 6 is a flowchart showing an example of the process of the discharge control executed by the ECU 300. The control processing shown in this flowchart is executed by ECU300 shown in fig. 1 every time a predetermined period elapses (for example, a time when the predetermined period elapses from the time when the last processing ended).

In S200, ECU300 determines whether or not the actual SOC is equal to or greater than the upper limit SOC (0) of the SOC of battery 100. If it is determined that the actual SOC is equal to or greater than the upper limit SOC (0) (yes in S200), the process proceeds to S202.

In S202, the ECU300 determines whether the vehicle 1 is in the ready-to-disconnect state. The ready-off state is a state in which the system of the vehicle 1 is stopped, and is a state in which the vehicle 1 does not run even if the user operates the accelerator pedal. More specifically, the ready-to-disconnect state is a state in which the operation of the electrical devices related to running, such as the MG10, the PCU40, and the like, of the vehicle 1 is stopped. When in a ready-to-on state in which the vehicle 1 can travel, the ECU300 receives an operation of the start switch and shifts the state of the vehicle 1 from the ready-to-on state to a ready-to-off state. When shifting to the ready-to-off state, ECU300 sets SMR50 to the off state after executing the process of stopping the operation of the electrical equipment related to the running of vehicle 1. The process of stopping the operation of the electrical equipment related to the running of the vehicle 1 includes, for example, a predetermined abnormality detection process. When the ECU300 receives an operation of the start switch while in the ready-on state, or when the system of the vehicle 1 is stopped, it determines that the vehicle 1 is in the ready-off state. If it is determined that the vehicle 1 is in the ready-to-disconnect state (yes in S202), the process proceeds to S204.

In S204, ECU300 determines whether SMR50 is in a disconnected state. If it is determined that SMR50 is in the off state (yes in S204), the process proceeds to S206. In S206, ECU300 executes discharge control using discharge device 240 until the SOC of battery 100 reaches SOC (0). That is, ECU300 causes each of the plurality of battery cells 110 to discharge by turning on switch 240b provided in each discharge device 240 of battery 100.

If it is determined that SMR50 is in an on state (no in S204), the process proceeds to S208. In S208, ECU300 executes discharge control using MG10 until the SOC of battery 100 reaches SOC (0). The ECU300 executes, for example, field weakening control of the MG 10. That is, the ECU300 controls the PCU40 so that the PCU40 generates a d-axis current component in a direction to weaken the magnetic field of the MG10 and outputs the d-axis current component to the MG 10.

In S210, ECU300 determines whether or not the actual SOC is equal to or less than the upper limit SOC (0) of the SOC of battery 100. If it is determined that the actual SOC is equal to or less than the upper limit SOC (0) (yes in S210), the process proceeds to S212. If it is determined that the actual SOC is greater than upper limit SOC (0) (no in S210), the process returns to S210.

In S212, ECU300 ends the discharge control. That is, ECU300 turns off switch 240b when battery 100 is discharged using discharge device 240. When battery 100 is discharged by the field weakening control, ECU300 ends the field weakening control.

Then, when it is determined that the actual SOC is smaller than the upper limit value SOC (0) (no in S200) or when it is determined that the state is not the ready-off state (i.e., the ready-on state) (no in S202), the process shown in the flowchart of fig. 6 is ended.

< actions of ECU300 in the present embodiment >

The operation of ECU300 based on the above-described structure and flowchart will be described with reference to fig. 7, 8, and 9.

Fig. 7 is a diagram for explaining a running environment of the vehicle 1 as a premise. As shown in fig. 7, for example, a case is assumed where the vehicle 1 makes a downhill from a first place having a certain altitude to a second place having an altitude lower than the first place and distant from the first place by a distance proportional to the altitude difference.

In the case where the user releases the depression of the accelerator pedal during the downhill of the vehicle 1, the PCU40 is controlled in such a manner that the required deceleration force is set for the vehicle 1 in accordance with the vehicle speed to generate the set required deceleration force. Thereby, the regenerative braking force generated in MG10 acts on vehicle 1.

At this time, even when it is determined that vehicle 1 is in the accelerator-off state and is traveling (yes in S100), battery 100 is charged with energy generated by regenerative braking when the actual SOC of battery 100 does not reach upper limit SOC (0) (no in S102).

On the other hand, when the actual SOC of battery 100 reaches upper limit SOC (0) (yes in S102), charging exceeding upper limit SOC (0) of SOC of battery 100 is allowed (S104). Therefore, the charging of battery 100 based on the energy generated by the regenerative braking is continued.

Fig. 8 is a diagram showing an example of the relationship between the deceleration of the vehicle 1 and the vehicle speed on a downward slope. The vertical axis of fig. 8 represents deceleration. The horizontal axis of fig. 8 represents vehicle speed. LN1 (short dashed line) in fig. 8 shows the relationship between the vehicle speed and the deceleration at the time of charging that is allowed to exceed upper limit SOC (0) when the SOC of battery 100 reaches upper limit SOC (0). LN2 (long dashed line) in fig. 8 shows the relationship between the vehicle speed and the deceleration at the time of charging when the SOC of battery 100 reaches upper limit SOC (0) and when charging exceeding upper limit SOC (0) is not allowed.

As shown in LN2 of fig. 8, when charging exceeding the upper limit value SOC (0) is not allowed, regenerative braking cannot be performed. Therefore, the set deceleration demand force cannot be generated. In contrast, as shown by LN1 in fig. 8, regenerative braking can be performed when charging exceeding the upper limit value SOC (0) is allowed. Therefore, the set deceleration-required force can be generated, and charging of battery 100 based on the energy generated by regenerative braking can be performed.

While vehicle 1 is moving from the first location to the second location in this manner, charging exceeding upper limit SOC (0) is allowed, and therefore the actual SOC of battery 100 is higher than upper limit SOC (0).

Then, a case is assumed in which the vehicle 1 is stopped and the user puts the vehicle 1 in the ready-to-disconnect state.

As described above, since the actual SOC of battery 100 is higher than upper limit value SOC (0) (yes in S200), it is determined whether vehicle 1 is in the ready-to-disconnect state (S202).

When the user operates the start switch or the like and the vehicle 1 shifts from the ready-on state to the ready-off state (yes in S202), it is determined whether the SMR50 is in the off state (S204).

When the state is shifted to the ready-off state and SMR50 is immediately turned off (yes in S204), discharge control using discharge device 240 is executed (S206). On the other hand, when SMR50 continues to be in the on state without being immediately turned off after the shift to the ready-to-off state (no in S204), discharge control (field weakening control) using MG10 is executed (S208).

Fig. 9 is a time chart showing a change in SOC when the discharge control is executed. The vertical axis of fig. 9 represents SOC. The horizontal axis of fig. 9 represents time. LN3 (solid line) in fig. 9 indicates a change in SOC of battery 100 when discharge control using MG10 is executed. LN4 (long dashed line) in fig. 9 indicates a change in SOC of battery 100 when discharge control using discharge device 240 is executed.

For example, assume a case where SOC of battery 100 is SOC (3) lower than SOC (2) and higher than SOC (0) and discharge control is started at time t (0).

As shown in LN3 of fig. 9, when discharge control using MG10 is performed, the amount of discharge per unit time increases compared to the case where discharge is performed using discharge device 240. Therefore, the discharge control started at time t (0) ends at time t (1) because the SOC reaches SOC (0).

In contrast, as shown in LN4 of fig. 9, when the discharge control using discharge device 240 is executed, the discharge amount per unit time is smaller than when the discharge is performed using MG 10. Therefore, the discharge control started at time t (0) is ended at time t (2) later than time t (1) because the SOC reaches SOC (0).

< Effect of action >

as described above, according to the vehicle of the present embodiment, when vehicle 1 is in the regenerative braking state using MG10, charging exceeding upper limit SOC (0) of the SOC of battery 100 is allowed, and therefore, even when the SOC of battery 100 is in the vicinity of the upper limit, regenerative energy can be efficiently recovered. Further, when vehicle 1 is in the ready-to-off state, the portion exceeding upper limit value SOC (0) is discharged, so that deterioration of battery 100 can be suppressed even when vehicle 1 is left for a long period of time. Therefore, it is possible to provide a vehicle that efficiently recovers energy during regenerative braking and suppresses deterioration of the power storage device.

When SMR50 is on, discharge control is performed by field weakening control using MG 10. Therefore, the portion exceeding the upper limit SOC (0) of the SOC of the battery 100 can be quickly discharged without adding new parts.

When SMR50 is off, discharge control using discharge device 240 as an equalization circuit is performed. Therefore, the portion exceeding the upper limit SOC (0) of the SOC of the battery 100 can be reliably discharged without adding new parts.

< modification >

In the above-described embodiment, the vehicle 1 is an electric vehicle, but the vehicle 1 is not particularly limited to an electric vehicle as long as it is a vehicle that is equipped with at least a rotating electric machine for driving and a power storage device that transmits and receives electric power to and from the rotating electric machine for driving. The vehicle 1 may be, for example, a hybrid vehicle (including a plug-in hybrid vehicle) on which a driving motor and an engine are mounted.

In the above-described embodiment, the vehicle 1 has been described as an example of a configuration in which a single motor generator is mounted, but the vehicle 1 may be configured to mount a plurality of motor generators. In this case, the discharge control may be performed in each of the plurality of motor generators.

In the above-described embodiment, the battery 100 has been described as an example in which a plurality of the battery cells 110 are connected in series, but the battery 100 may be configured such that, for example, the battery cells 110 are connected in parallel, or a plurality of battery stacks are connected in series, and the battery stacks are configured such that the battery cells 110 are connected in parallel.

In the above-described embodiment, the timing at which SMR50 is turned off after preparation-disconnection is not particularly limited, but SMR50 may be turned off at a predetermined timing after preparation-disconnection, for example. For example, the ECU300 may turn the SMR50 on before the door opening operation is performed when the user of the vehicle 1 gets off, turn the SMR50 off when the door opening operation is detected by the user using a sensor, a switch, or the like provided in the door, or turn the SMR50 off after a predetermined time has elapsed after the preparation-disconnection.

In the above-described embodiment, the case where the discharge devices 240 are provided in the plurality of battery cells 110 has been described as an example, but the discharge devices including resistors, switches, and the like may be connected in parallel to the battery 100.

In the above-described embodiment, the case where the discharge control is performed using MG10 when SMR50 is in the on state in the ready-to-off state was described as an example, but when SMR50 is in the on state, the discharge control may be performed using an electric device on the PCU40 side of SMR50, and the use of MG10 is not particularly limited. For example, when SMR50 is on in the ready-to-off state, discharge control may be executed to discharge battery 100 by operating an air conditioner (not shown).

In the above-described embodiment, the case where the magnetic field weakening control is executed when the discharge control is executed using the MG10 has been described as an example, but the magnetic field weakening control is not particularly limited to the case where the PCU40 can be controlled so that the torque at least to the extent that the vehicle 1 does not move is generated in the MG 10.

In the above-described embodiment, the case where only the discharge control is performed using MG10 when SMR50 is in the on state in the ready-to-off state has been described as an example, but ECU300 may perform the discharge control using MG10 and the discharge control using discharge device 240 in parallel or may perform switching at predetermined timing when SMR50 is in the on state in the ready-to-off state, for example.

In the above-described embodiment, the case where the discharge control for discharging by the MG10 or the discharging device 240 at a constant discharge amount is performed in accordance with the state of the SMR50 when the battery is in the ready-to-off state has been described as an example, but the discharge amount per unit time may be set in accordance with the temperature of the battery 100, and the battery 100 may be discharged so as to be the set discharge amount per unit time. In this case, for example, the discharge amount per unit time may be set to be lower as the temperature of battery 100 is higher. Alternatively, the battery 100 may be discharged by changing the discharge amount per unit time with the passage of time in accordance with a change in the temperature of the battery 100.

In the above-described embodiment, it has been described that SMR50 is determined to be in the off state after it is determined to be in the ready-to-open state, but for example, ECU300 may execute discharge control based on the state of SMR50 after a predetermined time has elapsed after it is determined to be in the ready-to-open state.

In the above-described embodiment, the description has been given of the case where the SMR50 is in the ready-to-open state, and the discharge control is executed using the MG10 or the discharge device 240 in accordance with the state of the SMR50, but the case where the SMR is in the ready-to-open state, the discharge control may be executed using either the MG10 or the discharge device 240 in accordance with the temperature of the battery 100. For example, when the temperature of battery 100 is higher than the threshold value, ECU300 may execute discharge control using discharge device 240 regardless of whether SMR50 is in a disconnected state.

The above-described modification examples may be implemented by appropriately combining all or some of them.

The embodiments of the present invention have been described, but the embodiments disclosed herein are not intended to be limiting and are illustrative in all respects. The scope of the present invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.