Electric vehicles

Abstract

The charging and discharging of the energy storage device is controlled to adequately protect components in the current path from overheating while ensuring that the operating performance of the electric vehicle is not compromised. [Solution] The control device sets the allowable power for the power input and output to the energy storage device based on the temperature and amount of energy stored in the energy storage device, and controls the motor so that the power input and output to the energy storage device does not exceed the allowable power. The control device has an allowable maximum limit rate for the limit rate, which is the rate at which the allowable power decreases. The control device is configured to reduce the allowable power at the allowable maximum limit rate if the evaluation function F for the temperature of a component provided on the current path input and output to the energy storage device exceeds the limit start value Ftag. The limit start value Ftag is set to a value that, when the allowable power is reduced at the allowable maximum limit rate, can keep the evaluation function F below a threshold Fm determined from the heat resistance limit temperature of the component.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle, and more specifically, to charge and discharge control of a power storage device mounted on an electric vehicle.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2015-147472 (Patent Document 1) discloses a control device for a hybrid vehicle that executes overheat protection control for suppressing an increase or promoting a decrease in the temperature of an electric device including a rotating electric machine for driving and a cooling medium used for cooling the rotating electric machine when the temperature of the electric device is a predetermined value or higher. This overheat protection control includes control for reducing the power generation load (regenerative torque) during deceleration regenerative braking and control for reducing the torque assist amount with respect to the drive shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric vehicle that travels using the power stored in a power storage device, it is necessary to suppress overheating of components provided in the current path through which the current input to and output from the power storage device flows. As a protective measure against heat generation of components, a method of suppressing heat generation itself by limiting the current flowing through the components can be adopted without increasing the level of the heat resistance specification of the components.

[0005] However, in the method of limiting the current flowing through the above-described components, depending on the timing at which current limitation is started with respect to heat generation of the components, the magnitude of the current limitation, etc., the electric vehicle may not be able to secure the desired output, and there is a possibility of degrading the running performance of the electric vehicle.

[0006] This disclosure was made to solve these problems, and its purpose is to control the charging and discharging of the energy storage device in such a way as to adequately protect the components of the current path from overheating without impairing the driving performance of the electric vehicle. [Means for solving the problem]

[0007] An electric vehicle according to this disclosure comprises an electric motor that generates the driving force for the electric vehicle, a power storage device that inputs and outputs power to and from the electric motor, and a control device. The control device sets an allowable power for the power input and output to the power storage device based on the temperature and amount of power stored in the power storage device. The control device controls the electric motor so that the power input and output to the power storage device does not exceed the allowable power. The control device has an allowable maximum limit rate for the limit rate, which is the rate at which the allowable power decreases. The control device is configured to reduce the allowable power at the allowable maximum limit rate if the evaluation function for the temperature of a component located in the path of the current input and output to the power storage device exceeds a limit start value. The limit start value is set to a value that, when the allowable power is reduced at the allowable maximum limit rate, can keep the evaluation function below a threshold determined from the heat resistance limit temperature of the component.

[0008] According to the above configuration, by limiting the allowable power using the maximum allowable limiting rate, the starting limit value can be increased, and the time during which the allowable power limit is enforced can be shortened. This makes it possible to suppress heat generation in components while suppressing a decrease in the driving performance of electric vehicles.

[0009] Preferably, the starting limit value is higher than the value at which the evaluation function can be kept below a threshold when the allowable power is reduced in proportion to the deviation of the evaluation function from the starting limit value. Compared to a configuration in which the allowable power is reduced in proportion to the deviation of the evaluation function from the starting limit value, this allows the starting limit value to be higher and the time at which the limit rate is the maximum allowable limit rate to be longer, thereby shortening the time at which the allowable power limit is enforced.

[0010] Preferably, when the evaluation function exceeds the limit start value, the control device calculates a target value of the allowable power based on the evaluation function for each control cycle using a predetermined control map. The control device then determines the control command value of the allowable power for the current control cycle by decreasing the target value from the previous control cycle at the maximum allowable limit rate, within a range that does not fall below the target value for the current control cycle. With this configuration, the allowable power can be quickly reduced to the target value based on the evaluation function.

[0011] Preferably, the control map is a map that can identify a target value from the evaluation function, and in the region where the evaluation function is above the limiting starting value and below the threshold, the target value changes nonlinearly with respect to the evaluation function from a first power value determined from the temperature and amount of energy stored in the energy storage device to a second power value that can maintain the evaluation function at the threshold. With this configuration, when the evaluation function is above the limiting starting value, the allowable power can be reduced using the allowable maximum limiting rate.

[0012] Preferably, the control device has a maximum allowable relaxation rate for the relaxation rate, which is the relaxation speed of the allowable power. When the evaluation function falls below the limit start value, the control device calculates a target value for the current control cycle based on the temperature and amount of energy stored in the energy storage device. The control device determines the control command value for the allowable power in the current control cycle by increasing the target value from the previous control cycle by the maximum allowable relaxation rate, within a range that does not exceed the target value for the current control cycle. With this configuration, when the evaluation function falls below the limit start value in accordance with the above-mentioned limit on allowable power, the allowable power can be quickly increased to the allowable power determined from the temperature and amount of energy stored in the energy storage device. [Effects of the Invention]

[0013] According to this disclosure, it is possible to control the charging and discharging of the energy storage device in a way that does not impair the driving performance of the electric vehicle while adequately protecting the components of the current path from overheating. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows an example of the overall configuration of an electric vehicle according to this embodiment. [Figure 2] This figure shows an overview of the process for limiting the allowable output power of a battery using a comparative example. [Figure 3] This figure shows an example of the temporal change in the limiting rate of the output power allowable power in the limiting process shown in Figure 2. [Figure 4] This figure shows an overview of the battery output power limiting process according to this embodiment. [Figure 5] This figure shows an example of the temporal change in the limiting rate of the output power allowable power in the limiting process shown in Figure 4. [Figure 6] This is a flowchart illustrating the procedure for limiting the battery's output power according to this embodiment. [Modes for carrying out the invention]

[0015] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0016] <Overall configuration of electric vehicles> Figure 1 shows an example of the overall configuration of an electric vehicle 1 according to this embodiment. In this embodiment, the electric vehicle 1 is, for example, an electric vehicle. The electric vehicle 1 may also be a hybrid vehicle, a plug-in hybrid vehicle, or the like.

[0017] The electric vehicle 1 comprises a motor generator (MG) 10, a power transmission gear 20, drive wheels 30, a power control unit (PCU) 40, a system main relay (SMR) 50, a battery 80, a monitoring unit 90, and an electronic control unit (ECU) 100.

[0018] MG10 is an AC rotating electric machine, for example, a three-phase AC synchronous motor in which permanent magnets are embedded in the rotor. MG10 is driven by receiving power supply from the battery 80 via the PCU40. The driving force of MG10 is transmitted to the drive wheels 30 via a power transmission gear 20 configured to include a reduction gear, a differential device, and the like.

[0019] During braking of the electric vehicle 1 or when reducing acceleration on a downhill slope, MG10 is driven by the drive wheels 30, and MG10 operates as a generator to perform regenerative power generation. The power generated by MG10 is stored in the battery 80 via the PCU40.

[0020] PCU40 is a power conversion device that converts power bidirectionally between MG10 and the battery 80. PCU40 includes, for example, an inverter and a converter that operate based on a control signal from the ECU100.

[0021] The converter boosts the DC voltage supplied from the battery 80 during discharge of the battery 80 and supplies it to the inverter. The inverter converts the DC power supplied from the converter into AC power to drive MG10.

[0022] The inverter converts the AC power generated by MG10 into DC power during charging of the battery 80 and supplies it to the converter. The converter降压 the DC voltage supplied from the inverter to a voltage suitable for charging the battery 80 and supplies it to the battery 80.

[0023] SMR50 is electrically connected to a power line 45 connecting the battery 80 and the PCU40. When SMR50 is closed (ON) in response to a control signal from the ECU100, power can be exchanged between the battery 80 and the PCU40. On the other hand, when SMR50 is opened (OFF) in response to a control signal from the ECU100, the electrical connection between the battery 80 and the PCU40 is interrupted.

[0024] Battery 80 stores the power needed to drive the MG10. Battery 80 is a rechargeable DC power source (secondary battery) and is composed of multiple single cells 80a connected in series. The single cells 80a are, for example, lithium-ion batteries.

[0025] The monitoring unit 90 is a device for monitoring the status of the battery 80 and includes a voltage sensor 92, a current sensor 94, and a temperature sensor 96. The voltage sensor 92 detects the voltage VB of the battery 80. The current sensor 94 detects the current IB that is input to and output from the battery 80. The temperature sensor 96 detects the temperature TB of the battery 80. The monitoring unit 90 outputs the detection results from each sensor to the ECU 100.

[0026] The electric vehicle 1 is equipped with an inlet 60 and is configured to allow external charging of the battery 80 using an electric vehicle supply equipment (EVSE) 200. The inlet 60 is configured to accept a connector 220 provided at the end of the charging cable 210 of the EVSE 200. The inlet 60 is electrically connected to the power line 45 via a charging circuit 70. In this embodiment, when the SMR 50 is closed, the inlet 60 and the battery 80 are electrically connected, enabling external charging.

[0027] The ECU 100 includes a CPU (Central Processing Unit) 102, a memory 104 such as ROM (Read Only Memory) and RAM (Random Access Memory), and input / output ports (not shown) for inputting and outputting various signals. Based on signals received from each sensor of the monitoring unit 90, and programs and maps stored in the memory 104, the ECU 100 performs control related to vehicle operation and charging / discharging of the battery 80.

[0028] Furthermore, the ECU100 provides protection against overheating of components located in the current path through which current flows to and from the battery 80 by limiting the current flowing to the components based on their heat state.

[0029] ECU100 corresponds to one embodiment of the "control device". ECU100 may be divided into multiple ECUs for each function. It is also possible to construct and process at least a part of ECU100 using dedicated hardware (electronic circuits).

[0030] <Protection measures for parts> In the electric vehicle 1 according to this embodiment, current flows through components in the current path of the current input and output to the battery 80, generating heat in those components that is approximately proportional to the square of the current value. Therefore, protective measures against the heat generated by these components are necessary. The protective measures for components in the electric vehicle according to this embodiment are described below.

[0031] In this embodiment, as a measure to protect components, an evaluation function representing the heat generation state of a component is generated based on the current flowing through the component and the energizing time. Based on the output value of the evaluation function, the allowable power, which indicates the upper limit of the power input and output to the battery 80, is limited. In other words, the current flowing through the component is limited based on the heat generation state of the component.

[0032] Generally, it is known that the heat generated by a component is proportional to the square of the current flowing through it, and that the heat dissipation from a component can be approximated by a first-order lag system. If this function is expressed as an evaluation function F, it can be obtained, for example, as shown in equation (1). F(n+1) = {(K(n)-1} × F(n) + I(n) 2} / K(n) …(1) Here, n represents the number of control cycles from the start of control, i.e., the elapsed time. I(n) represents the current value flowing through the component at the number of control cycles n, and K(n) is a coefficient for performing a first-order lag approximation, i.e., a coefficient equivalent to the time constant. This coefficient K(n) has a different value for each component and is set by a map determined in advance through experiments, etc. Furthermore, the coefficient K(n) may have different values ​​depending on the current value.

[0033] By pre-determining the coefficient K of the evaluation function F through experiments for the component to be protected, the heat generation state of the component can be estimated based on the current flowing through the component and the energizing time. Then, by limiting the current so that the output value of the evaluation function F does not exceed a threshold determined by the heat resistance limit of the component, heat generation of the component can be suppressed.

[0034] (Regarding problems in protective measures) Figures 2 and 3 illustrate the protection measures for components and their problems in comparative examples. Figure 2 shows an overview of the limiting process for the output power Wout of the battery 80 in comparative examples. In Figure 2, the horizontal axis shows the output values ​​of the evaluation function F for components on the current path of the battery 80, and the vertical axis shows the output power Wout. The output power Wout is the upper limit control value of the power output from the battery 80.

[0035] When power is supplied to a component, its temperature gradually rises over time. In response to this rise in temperature, the output value of the component's evaluation function F also increases. The output value of the evaluation function F includes a limiting threshold Ftag, which initiates the limitation of the allowable output power (Wout). Furthermore, the output value of the evaluation function F includes a threshold Fm, based on the component's thermal tolerance limit temperature.

[0036] When the output value of the evaluation function F is less than the limit start value Ftag, the allowable output power Wout is set to the allowable output power SWout, which is determined based on the state of charge (SOC) and temperature of the battery 80.

[0037] If the output value of the evaluation function F exceeds the limit start value Ftag, the limit on the allowable output power Wout is initiated. Note that "limiting the allowable output power Wout" means reducing its magnitude (corresponding to its absolute value). The same applies to the limit on the allowable input power Win, which is the upper limit of the power input to battery 80.

[0038] As shown in Figure 2, the allowable output power Wout decreases linearly (first-orderly) with respect to the output value of the evaluation function F. The allowable output power MWout when the output value of the evaluation function F is at the threshold Fm is set based on the output power of the battery 80, where the heat generation and heat dissipation of the component are balanced, suppressing the rise in component temperature and keeping it below the heat resistance limit temperature.

[0039] If Ko is the slope of the linear function between the output value of the evaluation function F and the allowable output power Wout, then the relationship given by equation (2) holds between Swout, MWout, Ftag, and Fm. MWout=SWout-Ko×(Fm-Ftag) …(2) In the comparative example, the allowable output power Wout is limited according to the output value of the evaluation function F, based on the relationship between the output value of the evaluation function F and the allowable output power Wout shown in Figure 2. When the output value of the evaluation function F is greater than or equal to the limiting starting value Ftag, the allowable output power Wout can be calculated from the relationship in equation (2) as Wout = SWout - Ko × (F - Ftag). In other words, the allowable output power Wout can be calculated by performing a proportional control operation to reduce the deviation F-Ftag of the output value of the evaluation function F with respect to the limiting starting value Ftag. Ko corresponds to the proportional gain.

[0040] In Figure 2, the limiting starting value Ftag is set to a value that allows the output value of the evaluation function F to be kept below the threshold Fm when the allowable output power Wout is reduced in proportion to the deviation F-Ftag of the output value of the evaluation function F relative to the limiting starting value Ftag.

[0041] Figure 3 shows an example of the temporal change in the limiting rate of the output power allowable power Wout in the limiting process shown in Figure 2. The "limiting rate of output power allowable power Wout" is the rate of change over time (i.e., the rate of decrease) when reducing the output power allowable power Wout, and is expressed as dWout / dt [kW / sec]. The limiting rate is expressed as a negative value.

[0042] Furthermore, a maximum permissible limit rate is set for the output power allowable power Wout. The "maximum permissible limit rate" refers to the maximum permissible value of the rate at which the output power allowable power Wout decreases (corresponding to its absolute value). If the output power allowable power Wout is reduced too rapidly, it may degrade the driving performance of the electric vehicle 1 due to insufficient output power from the battery 80. Therefore, the maximum permissible limit rate is set in advance through experiments and other means to prevent a decrease in the driving performance of the electric vehicle 1.

[0043] In Figure 3, the output value of the evaluation function F between time t0 and time t1 is less than the limit start value Ftag. Therefore, the output power Wout is not limited, and the limit rate is 0 [kW / sec].

[0044] At time t1, if the output value of the evaluation function F exceeds the limit start value Ftag, the limit on the allowable output power Wout is initiated. As described above, the allowable output power Wout is determined by a proportional control operation to reduce the deviation F-Ftag of the output value of the evaluation function F relative to the limit start value Ftag. Immediately after time t1, the control variable Ko×(F-Ftag) increases in accordance with the deviation F-Ftag, so the magnitude (absolute value) of the limit rate also increases. However, the limit rate is adjusted so as not to exceed the allowable maximum limit rate. Then, as the deviation F-Ftag decreases, the magnitude (absolute value) of the limit rate also gradually decreases.

[0045] In this comparative example, the allowable output power Wout is reduced in proportion to the deviation F-Ftag of the output value of the evaluation function F relative to the limiting starting value Ftag. Since the output value of the evaluation function F decreases according to the square of the current flowing through the component, the limiting rate decreases based on the square of the current. Therefore, it is not possible to fully utilize the allowable maximum limiting rate.

[0046] Furthermore, in order to limit the allowable output power Wout so that the output value of the evaluation function F does not exceed the threshold Fm under a limiting rate lower than the maximum allowable limiting rate, the limiting start value Ftag must be set low. As a result, there is a concern that the required output of electric vehicle 1 cannot be met, potentially degrading the driving performance of electric vehicle 1.

[0047] (Protective measures according to this embodiment) In response to the problems described above, this embodiment proposes protective measures that allow for more effective use of the maximum permissible limit rate. Figures 4 and 5 illustrate the protective measures for components according to this embodiment.

[0048] Figure 4 shows an overview of the limiting process for the output power Wout of the battery 80 according to this embodiment. In Figure 4, the horizontal axis shows the output values ​​of the evaluation function F for the components on the current path of the battery 80, and the vertical axis shows the output power Wout. In Figure 4, the waveform of the output power Wout according to this embodiment is shown as a solid line, and the waveform of the output power Wout according to the comparative example shown in Figure 2 is shown as a dashed line.

[0049] In this embodiment as well, similar to the comparative example, the output value of the evaluation function F includes a limiting starting value Ftag for initiating the limitation of the allowable output power Wout, and a threshold Fm based on the heat resistance limit temperature of the component. However, the limiting starting value Ftag in this embodiment is higher than the limiting starting value Ftag in the comparative example.

[0050] In this embodiment, the limiting starting value Ftag is set to a value that allows the output value of the evaluation function F to remain below the threshold Fm when the allowable output power Wout is reduced at the allowable maximum limiting rate. Therefore, in contrast to the comparative example, the allowable output power Wout decreases non-linearly with respect to the output value of the evaluation function F.

[0051] Figure 5 shows an example of the temporal change in the limiting rate of the output power allowable power Wout in the limiting process shown in Figure 4. Similar to Figure 3, the limiting rate is represented by a negative value. In Figure 5, the limiting rate according to this embodiment is shown by a solid line, and the limiting rate according to the comparative example shown in Figure 3 is shown by a dashed line.

[0052] In Figure 5, the output value of the evaluation function F between time t0 and time t1 is less than the limit start value Ftag. Therefore, the output power Wout is not limited, and the limit rate is 0 [kW / sec].

[0053] If the output value of the evaluation function F exceeds the limit start value Ftag at time t1, the limit on the allowable output power Wout is initiated. The limit rate of the allowable output power Wout is set to the allowable maximum limit rate. That is, the allowable output power Wout decreases at the allowable maximum limit rate from time t1 onward.

[0054] As the allowable output power Wout decreases, the evaluation function F decreases in proportion to the square of the current flowing through the component. When the output value of the evaluation function F drops to the limit start value Ftag at time t2, the limit rate is set to 0 [kW / sec].

[0055] As can be seen from Figure 5, in this embodiment, the starting limit value Ftag is higher than in the comparative example, so the timing at which the limiting of the allowable output power Wout begins in response to the increase in the output value of the evaluation function F (time t1 in the figure) is delayed. Also, in this embodiment, the time during which the limiting rate reaches the allowable maximum limiting rate (time t1 to t2 in the figure) is longer than in the comparative example.

[0056] As a result, in this embodiment, the length of time during which the limiting rate is less than 0 [kW / sec], i.e., the length of time during which the limiting of the allowable output power Wout is enforced, is shorter in this embodiment than in the comparative example.

[0057] As described above, according to this embodiment, by limiting the allowable output power Wout using the maximum allowable limiting rate, the limiting starting value Ftag can be made higher than in the comparative example, and the time during which the limiting of the allowable output power Wout is performed can be shortened. This makes it possible to suppress heat generation in the components while also meeting the required output of the electric vehicle 1. In other words, it is possible to suppress the deterioration of the driving performance of the electric vehicle 1 due to protective measures for the components.

[0058] Figure 6 is a flowchart illustrating the procedure for limiting the output power Wout of the battery 80 according to this embodiment. The flowchart shown in Figure 6 is executed by the ECU 100 at predetermined control cycles. Hereinafter, steps will be abbreviated as S.

[0059] As shown in Figure 6, in S01, the ECU 100 obtains the detected voltage VB of the battery 80, the detected current IB supplied to and from the battery 80, and the detected temperature TB of the battery 80 from the monitoring unit 90.

[0060] In S02, the ECU100 calculates the output value of the evaluation function F of the protected component using equation (1) based on the current IB input and output to the battery 80. In S02, the coefficient K(n) in equation (1) is set for each component by a map determined in advance through experiments or other means.

[0061] In S03, ECU100 obtains the target power Wout*(n-1), which is the target value of the allowable output power Wout for the previous control cycle.

[0062] In S04, ECU100 compares the output value of the evaluation function F obtained in S02 with the limit start value Ftag.

[0063] If the output value of the evaluation function F is greater than or equal to the limit start value Ftag (when S04 is judged as YES), the ECU 100 calculates the target power Wout*(n) for the current control cycle based on the output value of the evaluation function F in S05. In S05, the ECU 100 has a control map in which the relationship between the output value of the evaluation function F and the allowable output power Wout, as shown in Figure 4, is defined. Using this control map, the ECU 100 calculates the allowable output power Wout corresponding to the output value of the evaluation function F as the target power Wout*(n).

[0064] In S06, ECU100 calculates the command power Wout(n), which is the control command value for the allowable output power Wout in the current control cycle. In S06, ECU100 finds the value obtained by decreasing the previous target power Wout*(n-1) according to the allowable maximum limit rate. If the magnitude (absolute value) of the allowable maximum limit rate is dWout_res / dt and the length of the control cycle is dt, then this value is expressed as Wout*(n-1)-dWout_res. ECU100 then sets the command power Wout(n) to be the larger of this value and the target power Wout*(n) in the current control cycle.

[0065] In other words, if the output value of the evaluation function F is greater than or equal to the limit start value Ftag, the ECU 100 reduces the command power Wout in each control cycle at the maximum allowable limit rate, within a range that does not fall below the target power Wout* in each control cycle.

[0066] On the other hand, if the output value of the evaluation function F is less than the limit start value Ftag (when NO is determined in S04), the ECU 100 calculates the target power Wout*(n) for the current control cycle based on the State of Charge (SOC) and temperature TB of the battery 80. In S07, the ECU 100 calculates the SOC of the battery 80. Known methods are used for calculating the SOC, such as methods using the SOC-OCV (Open Circuit Voltage) curve, methods using current integration, or combinations thereof. Then, the ECU 100 calculates the allowable output power SWout as the target power Wout*(n) based on the SOC and temperature TB of the battery 80.

[0067] In S08, ECU100 calculates the command power Wout(n) for the current control cycle. In S08, ECU100 increases the command power Wout for each control cycle at the maximum allowable relaxation rate, within the limits that it does not exceed the target power Wout* (=SWout) for each control cycle.

[0068] Specifically, a maximum allowable relaxation rate is set for the relaxation rate of the allowable output power Wout. The "relaxation rate of the allowable output power Wout" is the rate of change over time (i.e., the rate of increase) when increasing the allowable output power Wout, and is expressed as dWout / dt [kW / sec]. The limit rate is expressed as a positive value. The "maximum allowable relaxation rate" means the maximum allowable value of the magnitude (corresponding to the absolute value) of the rate of increase of the allowable output power Wout. If the allowable output power Wout is increased rapidly, the sudden change in the output power of the battery 80 may reduce the drivability of the electric vehicle 1. Therefore, the maximum allowable relaxation rate is set in advance through experiments, etc., to prevent a decrease in the drivability of the electric vehicle 1.

[0069] In S08, ECU100 calculates the value obtained by increasing the previous target power Wout*(n-1) according to the maximum allowable relaxation rate. If the magnitude (absolute value) of the maximum allowable relaxation rate is dWout_rel / dt and the length of the control cycle is dt, then this value is expressed as Wout*(n-1)+dWout_rel. ECU100 sets the command power Wout(n) for the current control cycle to be the smaller of this value and the target power Wout*(n) (=SWout) for the current control cycle.

[0070] As explained above, in the limiting process for the battery 80's output power Wout, the ECU 100 reduces the output power Wout at the maximum allowable limiting rate if the output value of the evaluation function F is greater than or equal to the limiting start value Ftag. Furthermore, if the output value of the evaluation function F is less than the limiting start value Ftag, the ECU 100 increases the output power Wout at the maximum allowable relaxation rate. In this way, the time during which the power input to and output from the battery 80 is limited is shortened, thereby suppressing the deterioration of the electric vehicle 1's driving performance due to component protection measures.

[0071] In the embodiment described above, the limiting process for the battery 80's output power Wout was explained, but the same method is also applied to the limiting process for the battery 80's input power Win.

[0072] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments described above, and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of symbols]

[0073] 1 electric vehicle, 10 MG, 20 power transmission gears, 30 drive wheels, 40 PCU, 45 power lines, 50 SMR, 60 inlets, 70 charging circuits, 80 batteries, 80a single cells, 90 monitoring units, 92 voltage sensors, 94 current sensors, 96 temperature sensors, 100 ECU, 102 CPUs, 104 memory, 200 EVSE, 210 charging cables, 220 connectors.

Claims

1. It is an electric vehicle, The electric motor that generates the driving force for the electric vehicle, A power storage device that inputs and outputs power to and from the aforementioned electric motor, The system includes a control device that sets an allowable power for the power input and output to the energy storage device based on the temperature and amount of energy stored in the energy storage device, and controls the motor so that the power input and output to the energy storage device does not exceed the allowable power, The control device has a maximum allowable limiting rate for the rate at which the allowable power decreases, and is configured to reduce the allowable power by the maximum allowable limiting rate when the evaluation function for the temperature of a component provided on the current path to and from the energy storage device exceeds the limiting start value. An electric vehicle wherein the starting limit value is set to a value that, when the allowable power is reduced by the allowable maximum limit rate, can maintain the evaluation function below a threshold determined from the heat resistance limit temperature of the component.

2. The electric vehicle according to claim 1, wherein the starting limit value is higher than the value at which the evaluation function can be kept below the threshold when the allowable power is reduced in proportion to the deviation of the evaluation function with respect to the starting limit value.

3. If the evaluation function exceeds the limit start value, the control device will Using a predetermined control map, the target value of the allowable power based on the evaluation function is calculated for each control cycle. The electric vehicle according to claim 1, wherein the control command value for the allowable power in the current control cycle is determined by reducing the target value in the previous control cycle by the allowable maximum limit rate, within a range that does not fall below the target value in the current control cycle.

4. The electric vehicle according to claim 3, wherein the control map is a map capable of identifying the target value from the evaluation function, and in the region where the evaluation function is greater than or equal to the limiting starting value and less than or equal to the threshold, the target value changes nonlinearly with respect to the evaluation function from a first power value determined from the temperature and amount of stored energy of the energy storage device to a second power value that can maintain the evaluation function at the threshold.

5. The control device has a maximum allowable relaxation rate, which is the relaxation rate of the allowable power. The control device, when the evaluation function falls below the limit start value, Based on the temperature and amount of stored energy in the aforementioned energy storage device, the target value for the current control cycle is calculated. The electric vehicle according to claim 3 or 4, wherein the control command value of the allowable power in the current control cycle is determined by increasing the target value in the previous control cycle by the allowable maximum relaxation rate, within a range that does not exceed the target value in the current control cycle.

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