JP2012019587A - Electric motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen the lifetime of a switching element by suppressing the excess of the thermal stress of the switching element configuring a power converter loaded on an electric motor vehicle.SOLUTION: The converter 15 and inverters 20 and 30 carry out power conversions among motor generators MG1 and MG2 for generating a vehicle driving force and a main battery B. The converter 15 contains the switching elements Q1 and Q2. The limiting values of the current and power of the main battery B are set so that the variations of the temperatures of the switching elements in load operations generating the charge and discharge of the main battery elevating the temperatures of the switching elements may not be excessive.

Description

  The present invention relates to an electric vehicle, and more specifically, for suppressing thermal stress of a power semiconductor switching element (hereinafter, also simply referred to as “switching element”) constituting a power converter mounted on the electric vehicle. Regarding technology.

  In recent years, electric vehicles equipped with an electric motor for generating vehicle driving force, such as hybrid vehicles, electric vehicles, and fuel cell vehicles, have attracted attention from the viewpoint of the environment.

  Japanese Unexamined Patent Application Publication No. 2009-219200 (Patent Document 1) discloses a vehicle for suppressing a temperature rise of a reactor that is a component part of a chopper type converter mounted on a hybrid vehicle that is one of such electric vehicles. Control is described.

  Similarly, Japanese Unexamined Patent Application Publication No. 2009-12702 (Patent Document 2) describes preventing the capacitor from overheating in order to suppress a decrease in output performance of an inverter mounted on a hybrid vehicle. In particular, Patent Document 2 describes that the temperature of the capacitor is accurately estimated, and control is performed to prevent overheating of the smoothing capacitor based on the estimated temperature of the capacitor.

  JP 2009-171766 (Patent Document 3) discloses that in a converter similar to Patent Document 1, when the cooling device is abnormal, the direct current component and the ripple component of the current flowing through the reactor are suppressed, thereby generating heat from the reactor. Techniques for suppression are described.

JP 2009-219200 A JP 2009-12702 A JP 2009-171766 A JP 2003-134606 A JP 2008-228429 A

  Patent Documents 1 to 3 describe that in a power supply system of an electric vehicle represented by a hybrid vehicle, it is possible to suppress the occurrence of a device failure due to an excessive temperature rise of a reactor or a capacitor that is a component thereof. . That is, when the temperature of these components becomes high, various controls are executed to suppress the passing current of the element.

  On the other hand, the switching element, which is the main component of the power supply system, has a small-area electrical junction, so that not only damage due to the high temperature itself but also thermal stress that is received by temperature changes in a short time It greatly affects the service life. Specifically, there is a possibility that disconnection or the like may occur due to the repeated action of stress generated by such expansion and contraction accompanying such a temperature change. Therefore, regarding protection of the switching element, it is necessary to consider not only the high and low element temperatures but also the amount of temperature change in a short time.

  In particular, in a power supply system mounted on an electric vehicle, there are many occasions when a large current is generated in a short time, for example, when a driver operates an accelerator pedal or when an engine is started. For this reason, depending on the usage environment such as the user's driving characteristics and the daily traveling path, the temperature change amount in the switching element in a short time may tend to increase. If such a tendency is left unattended, the life of the switching element may be shortened due to thermal stress. On the other hand, the techniques of Patent Documents 1 to 3 that perform control focusing on the element temperature itself may not sufficiently cope with the thermal stress of the switching element as described above.

  The present invention has been made to solve such problems, and an object of the present invention is that the thermal stress of the switching elements constituting the power converter mounted on the electric vehicle becomes excessive. This is to suppress the life of the switching element.

  According to the present invention, there is provided an electric vehicle equipped with an electric motor for generating vehicle driving force, the electric storage device for accumulating electric power input / output to / from the electric motor, and the electric motor and the electric motor by the on / off control of the switching element. A power converter configured to perform power conversion between power storage devices and a control device for controlling power conversion are provided. The control device includes a detection unit and a limit setting unit. The detection unit is configured to detect occurrence of a load operation that causes charging and discharging of the power storage device such that the temperature of the switching element increases. The limit setting unit is configured to set a limit value in power conversion for suppressing a passing current of the switching element according to a temperature change amount of the switching element in each load operation.

  Preferably, the control device includes a storage unit, a performance management unit, and a comparison unit. The storage unit is configured to store a predetermined reference distribution for the temperature change amount. The result management unit is configured to cumulatively store the results of the temperature change amount in the load operation every time the load operation is detected. The comparison unit is configured to compare the result distribution of the temperature change amount accumulated in the result management unit and the reference distribution stored in the storage unit. The limit setting unit sets a limit value based on the comparison result by the comparison unit.

  More preferably, the comparison unit is configured to calculate a parameter value that quantitatively indicates a degree of deviation of the actual distribution with respect to the reference distribution on the high temperature side in accordance with a comparison between the reference distribution and the actual distribution. The limit setting unit sets the limit value so as to decrease the limit value from the default value as the parameter value increases.

  More preferably, the limit setting unit returns the limit value to the default value when the parameter value decreases to a predetermined value while the limit value is decreased from the default value.

  Particularly in such a configuration, the limit value includes at least one of a current upper limit value of the power storage device and a limit value of the output power upper limit value of the power storage device.

  Preferably, the comparison unit compares the reference distribution and the actual distribution every time the electric vehicle travels a certain distance.

  Alternatively, preferably, the comparison unit compares the reference distribution and the actual distribution every time a predetermined fixed period elapses.

  Preferably, the limit setting unit sets a limit value in accordance with the temperature rise amount of the switching element from the start of the load operation when the load operation occurs.

  More preferably, the limit setting unit sets the limit value so as to decrease the limit value from the default value when the temperature increase amount is higher than the threshold value. The threshold value is higher than the average temperature in a predetermined reference distribution for the temperature change amount.

  Particularly in such a configuration, the limit value includes at least one of a current upper limit value of the power storage device and a charge / discharge limit time of the power storage device.

  Preferably, the limit setting unit sets a limit value according to current data corresponding to a passing current of the switching element when a load operation occurs.

  More preferably, the limit setting unit sets the limit value so as to decrease the limit value from the default value when the current data is higher than the threshold value. The threshold is set based on a predetermined reference distribution for the temperature change amount.

  Particularly in such a configuration, the limit value includes a switching frequency upper limit value of the switching element in the power converter.

  Preferably, the limit setting unit further reflects temperature data indicating the cooling capacity of the switching element, and sets the limit value so that the limit is relaxed when the cooling capacity is high than when the cooling capacity is low.

  According to this invention, it is possible to prevent the switching element constituting the power converter mounted on the electric vehicle from being excessively stressed and to extend the life of the switching element.

1 is a block diagram illustrating a configuration example of a hybrid vehicle shown as an example of an electric vehicle according to an embodiment of the present invention. It is a conceptual diagram for demonstrating the aspect of the temperature change of a switching element. It is a conceptual diagram for demonstrating the lifetime design corresponding to a thermal stress. FIG. 2 is a functional block diagram for explaining travel control of the hybrid vehicle shown in FIG. 1. 4 is a functional block diagram illustrating a configuration of a temperature change restriction unit according to Embodiment 1. FIG. 6 is a conceptual diagram schematically illustrating setting of limit values by a limit setting unit according to Embodiment 1. FIG. It is a flowchart for demonstrating suppression control of the temperature change amount of the switching element in the electric vehicle by Embodiment 1 of this invention. 6 is a functional block diagram illustrating a configuration of a temperature change restriction unit according to Embodiment 2. FIG. 10 is a conceptual diagram schematically illustrating setting of limit values by a limit setting unit according to Embodiment 2. FIG. It is a flowchart for demonstrating suppression control of the temperature change amount of the switching element in the electric vehicle by Embodiment 2 of this invention. FIG. 10 is a first conceptual diagram schematically illustrating setting of limit values by a limit setting unit according to a modification of the second embodiment. FIG. 12 is a second conceptual diagram schematically illustrating setting of limit values by a limit setting unit according to a modification of the second embodiment. It is a flowchart for demonstrating suppression control of the temperature variation of the switching element in the electric vehicle by the modification of Embodiment 2 of this invention.

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

[Embodiment 1]
FIG. 1 is a block diagram illustrating a configuration example of a hybrid vehicle 100 shown as an example of an electric vehicle according to an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 100 includes an engine 110, a power split mechanism 120, motor generators MG <b> 1 and MG <b> 2, a speed reducer 130, a drive shaft 140 and wheels (drive wheels) 150.

  Hybrid vehicle 100 further includes a main battery B, a converter 15, smoothing capacitors C0 and C1, inverters 20 and 30, which are representative examples of “power storage devices” for driving and controlling motor generators MG1 and MG2. And a control device 50.

  The engine 110 is constituted by, for example, an internal combustion engine such as a gasoline engine or a diesel engine. The engine 110 is provided with a cooling water temperature sensor 112 that detects the temperature of the cooling water. The output of the cooling water temperature sensor 112 is sent to the control device 50.

  Power split device 120 is configured to be able to split the power generated by engine 110 into a route to drive shaft 140 and a route to motor generator MG1. As the power split mechanism 120, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary gear, and a ring gear can be used.

  For example, engine 110 and motor generators MG1 and MG2 can be mechanically connected to power split mechanism 120 by making the rotor of motor generator MG1 hollow and passing the crankshaft of engine 110 through the center thereof. Specifically, the rotor of motor generator MG1 is connected to the sun gear, the output shaft of engine 110 is connected to the planetary gear, and output shaft 125 is connected to the ring gear. The output shaft 125 connected to the rotation shaft of the motor generator MG2 is connected to a drive shaft 140 for rotationally driving the wheel 150 via the speed reducer 130. A reduction gear for the rotation shaft of motor generator MG2 may be further incorporated.

  Motor generator MG <b> 1 operates as a generator driven by engine 110 and operates as an electric motor that starts engine 110, and is configured to have both functions of an electric motor and a generator. Similarly, motor generator MG2 is incorporated into hybrid vehicle 100 so that the output is transmitted to drive shaft 140 via output shaft 125 and reduction gear 130. Further, motor generator MG2 is configured to have a function for the electric motor and the generator so as to perform regenerative power generation by generating an output torque in a direction opposite to the rotation direction of wheel 150. That is, motor generators MG1 and MG2 correspond to “motors” for generating vehicle driving.

  Thus, motor generators MG 1, MG 2 and the output shaft of engine 110 are connected via power split mechanism 120. Thus, in hybrid vehicle 100, for example, the rotation speed of engine 110 is fixed in a fuel-efficient region, and in response to an acceleration request due to the driver's operation of accelerator pedal 70, torque increase (rotation speed) of motor generator MG2 is applied. Increase). Alternatively, during low speed travel where the engine travel is in the low fuel consumption region, it is possible to select a travel mode in which the engine 110 is stopped and travel is performed only by the output of the motor generator MG2.

  Next, a configuration for driving and controlling motor generators MG1 and MG2 will be described.

  As the main battery B, a secondary battery such as nickel hydride or lithium ion is applicable. In the present embodiment, a description will be given of a configuration in which the main battery B composed of secondary batteries is the “power storage device”. However, instead of the main battery B, a power storage device such as an electric double layer capacitor is applied. Is also possible.

  The battery voltage Vb output from the main battery B is detected by the voltage sensor 10, and the battery current Ib input / output to / from the main battery B is detected by the current sensor 11. Further, the main battery B is provided with a temperature sensor 12. Battery voltage Vb, battery current Ib, and battery temperature Tb detected by voltage sensor 10, current sensor 11, and temperature sensor 12 are output to control device 50.

  Main battery B and converter 15 are connected by ground line 5 and power supply line 6. Smoothing capacitor C <b> 1 is connected between ground line 5 and power supply line 6. In addition, between the positive terminal of the main battery B and the power line 6 and between the negative terminal of the main battery B and the ground line 5, the power system is turned on when the power system is turned on (during vehicle operation), and the power system is turned off. A system main relay (not shown) that is turned off at the time (when the vehicle is stopped) is provided.

  Converter 15 includes a reactor L and power semiconductor elements (hereinafter referred to as “switching elements”) Q1 and Q2 that are switching-controlled. Reactor L is connected between a connection node of switching elements Q 1 and Q 2 and power supply line 6.

  The smoothing capacitor C 0 is connected between the power supply line 7 and the ground line 5. The voltage sensor 13 detects a DC voltage VH between the power supply line 7 and the ground line 5.

  Power semiconductor switching elements Q 1 and Q 2 are connected in series between power supply line 7 and ground line 5. Switching elements Q1 and Q2 are turned on / off by switching control signal SCNV from control device 50. In the present embodiment, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used as the switching element. Anti-parallel diodes D1, D2 are arranged for switching elements Q1, Q2.

  The DC voltage side of inverters 20 and 30 is connected to converter 15 via common ground line 5 and power supply line 7. Since each of inverters 20 and 30 is a general three-phase inverter composed of a plurality of switching elements (not shown), description of the detailed configuration is omitted.

  Motor generator MG1 includes a U-phase coil winding U1, a V-phase coil winding V1 and a W-phase coil winding W1 provided on the stator, and a rotor (not shown). One end of U-phase coil winding U1, V-phase coil winding V1 and W-phase coil winding W1 are connected to each other at neutral point N1, and the other end is connected to each phase arm (not shown) of inverter 20, respectively. Connected. Inverter 20 performs bidirectional DC / AC power conversion by on / off control (switching control) of a switching element (not shown) in response to switching control signal SINV1 from control device 50.

  Motor generator MG2 is configured similarly to motor generator MG1, and includes a U-phase coil winding U2, a V-phase coil winding V2 and a W-phase coil winding W2 provided on the stator, and a rotor (not shown). . As with motor generator MG1, one end of U-phase coil winding U2, V-phase coil winding V2 and W-phase coil winding W2 are connected to each other at neutral point N2, and the other end is not shown in FIG. Connected to each phase arm.

  Inverter 30 performs bidirectional DC / AC power conversion in the same manner as inverter 20 by on / off control (switching control) of a switching element (not shown) in response to switching control signal SINV2 from control device 50.

  Each of motor generators MG1, MG2 is provided with a current sensor 27 and a rotation angle sensor (resolver) 28. Since the sum of instantaneous values of the three-phase currents iu, iv, and iw is zero, the current sensor 27 detects the motor current for two phases (for example, the V-phase current iv and the W-phase current iw) as shown in FIG. It is enough to arrange it to do. Rotation angle sensor 28 detects a rotation angle θ of a rotor (not shown) of motor generators MG 1, MG 2 and sends the detected rotation angle θ to control device 50. Control device 50 can calculate rotational speed Nmt (rotational angular velocity ω) of motor generators MG1 and MG2 based on rotational angle θ.

  The motor current MCRT (1) and the rotor rotation angle θ (1) of the motor generator MG1 and the motor current MCRT (2) and the rotor rotation angle θ (2) of the motor generator MG2 detected by these sensors are the control device. 50.

  1, the converter 15 and the inverter 20 are configured to perform power conversion between the motor generators MG1 and MG2 and the main battery B by on / off control of the switching elements. Corresponds to "

  A control device 50 including an electronic control unit (ECU) includes a microcomputer (not shown), a RAM (Random Access Memory) 51, and a ROM (Read Only Memory) 52. Control device 50 performs switching control signals SCNV, SINV1, for switching control of converter 15 and inverters 20, 30 such that motor generators MG1, MG2 operate according to motor commands in accordance with predetermined program processing stored in advance in ROM 52. SINV2 is generated. Alternatively, at least a part of the ECU 50 may be configured to execute predetermined numerical / logical operation processing by hardware such as an electronic circuit.

  Furthermore, information such as an input power upper limit value Win indicating the charge rate (SOC: State of Charge) and a charge / discharge limit, an output power upper limit value Wout, and the like regarding the main battery B are input to the control device 50. Thereby, control device 50 has a power management function for limiting power consumption and generated power (regenerative power) in motor generators MG1 and MG2 as necessary so that overcharge or overdischarge of main battery B does not occur. Have. Details of the power management will be described later in detail with reference to FIG.

  In the present embodiment, the mechanism for switching the switching frequency in the inverter control by the single control device (ECU) 50 has been described. However, the same control configuration is realized by the cooperative operation of the plurality of control devices (ECU). Is also possible.

  As is well known, acceleration and deceleration / stop commands for the hybrid vehicle 100 by the driver are input by operating the accelerator pedal 70 and the brake pedal 71. An operation (depression amount) of the accelerator pedal 70 and the brake pedal 71 by the driver is detected by an accelerator opening sensor 73 and a brake pedal depression amount sensor 74.

  The accelerator opening sensor 73 and the brake pedal depression amount sensor 74 output voltages corresponding to the depression amounts of the accelerator pedal 70 and the brake pedal 71 by the driver, respectively. Output signals ACC and BRK of the accelerator opening sensor 73 and the brake pedal depression amount sensor 74 are input to the control device 50.

  Next, operations of converter 15 and inverters 20 and 30 in drive control of motor generators MG1 and MG2 will be described.

  The converter 15 performs bidirectional DC voltage conversion between the DC voltage of the power supply line 6 and the DC voltage VH of the power supply line 7. More specifically, converter 15 controls DC voltage VH according to voltage command value VHref by performing on / off control of switching elements Q1, Q2 based on switching control signal SCNV from control device 50. Basically, converter 15 is controlled such that switching elements Q1 and Q2 are turned on and off in a complementary manner in each switching period.

  As is well known, the voltage conversion ratio (ie, VH / Vb) in converter 15 is determined by the duty ratio (ON period ratio) of IGBT elements Q1 and Q2 with respect to the switching period. If switching elements Q1 and Q2 are fixed to ON and OFF, respectively, VH = Vb (voltage conversion ratio = 1.0) can be obtained.

  Control device 50 appropriately sets the duty ratio of switching elements Q1, Q2 in accordance with the voltage ratio between battery voltage Vb and voltage command value VHref and / or the voltage difference of detected DC voltage VH with respect to voltage command value VHref. As described above, the switching control signal SCNV is generated.

  Control device 50 sets a command value VHref of DC voltage VH (hereinafter also simply referred to as voltage command value VHref) in accordance with the operating state of motor generators MG1 and MG2. Further, control device 50 determines that the output voltage of converter 15 is voltage command value VHref according to the voltage ratio between battery voltage Vb and voltage command value VHref and / or the voltage difference of detected DC voltage VH with respect to voltage command value VHref. The switching control signal SCNV is generated so as to be equal to.

  The smoothing capacitor C0 smoothes the DC voltage VH of the power supply line 6. The DC voltage smoothed by the smoothing capacitor C0 becomes the DC side voltage of the inverters 20 and 30.

  When the torque command value of corresponding motor generator MG2 is positive (Tqcom (2)> 0), inverter 30 performs an on / off operation of a switching element (not shown) in response to switching control signal SINV2 from control device 50. (Switching operation) drives the motor generator MG2 to convert the DC voltage VH from the smoothing capacitor C0 into a three-phase AC voltage and output a positive torque. Further, when the torque command value of motor generator MG2 is zero (Tqcom (2) = 0), inverter 30 converts DC voltage VH to output torque of motor generator MG2 through a switching operation in response to switching control signal SINV2. Is converted to a three-phase AC voltage such that becomes zero and supplied to motor generator MG2.

  Further, at the time of regenerative braking of hybrid vehicle 100, motor generator MG2 receives power from wheels 150 to generate power. During regenerative braking, the torque command value of motor generator MG2 is set negative (Tqcom (2) <0). In this case, inverter 30 converts the three-phase AC voltage generated by motor generator MG2 into a DC voltage by a switching operation in response to switching control signal SINV2, and converts the converted DC voltage through a smoothing capacitor C0. 15 is supplied. Converter 15 supplies the charging current of main battery B from power supply line 7 to power supply line 6 during the ON period of switching element Q1 according to the duty ratio control.

  Here, regenerative braking refers to braking with regenerative power generation when the driver driving the hybrid vehicle 100 performs a regenerative power generation or turning off the accelerator pedal while traveling without operating the foot brake. This includes decelerating (or stopping acceleration) the vehicle while generating regenerative power.

  Thus, inverter 30 performs power conversion so that motor generator MG2 operates according to the operation command (torque command value Tqcom (2)) by switching control according to switching control signal SINV2 from control device 50.

  Inverter 20, similarly to the operation of inverter 30 described above, motor generator MG1 operates according to an operation command (torque command value Tqcom (1)) by switching control according to switching control signal SINV1 from control device 50. Thus, power conversion is performed.

  Thus, control device 50 controls driving of motor generators MG1 and MG2 in accordance with torque command values Tqcom (1) and (2), so that hybrid vehicle 100 generates vehicle driving force due to power consumption in motor generator MG2. The generation of the charging power of the main battery B or the power consumption of the motor generator MG2 by the power generation by the motor generator MG1 and the generation of the charging power of the main battery B by the regenerative braking operation (power generation) by the motor generator MG2 It can be appropriately executed according to the state.

  As can be understood from FIG. 1, in hybrid vehicle 100, battery voltage Vb can be boosted by converter 15 and applied to motor generators MG1 and MG2. As a result, since the currents of motor generators MG1 and MG2 with respect to the same power output can be reduced, it is possible to reduce power loss and increase driving efficiency. On the other hand, when electric power is output from main battery B to ensure the output of motor generators MG1 and MG2, the temperature of switching elements Q1 and Q2 rises due to heat generated by the switching operation. The same applies when the charging current of the main battery B suddenly occurs during regenerative braking or the like. The change in temperature of the switching element at this time will be described with reference to FIG.

  Referring to FIG. 2, when accelerator opening ACC increases due to the accelerator operation of the driver, the output of motor generator MG2 increases in response to the acceleration request, so that electric power is output from main battery B. Along with this, in the switching elements Q1 and Q2, the element temperature Tsw rises due to the switching operation for power conversion. The element temperature Tsw comprehensively indicates the temperature of each of the switching elements Q1 and Q2.

  On the other hand, the switching element is provided with a cooling mechanism (not shown). For this reason, when the power output from the main battery B is stopped by returning the accelerator opening degree ACC, the element temperature Tsw decreases when the heat generation in the switching elements Q1 and Q2 stops. As a result, a temperature change occurs in a relatively short period when the accelerator pedal 70 is operated. Due to such a temperature change, the stress accompanying expansion / contraction acts on the conductor portions constituting the switching elements Q1, Q2 as thermal stress. The magnitude of this thermal stress depends on the temperature change amount ΔT.

  The temperature change amount ΔT is determined by the amount of heat generated during the temperature rise phase as described above. For this reason, the temperature change amount ΔT mainly depends on the current that the switching elements Q1 and Q2 switch, that is, the passing current of the switching elements Q1 and Q2 (hereinafter also referred to as “element current”).

  Although the thermal stress due to the temperature change ΔT in such a short time does not cause element destruction by a single stress, it is repeatedly generated when the hybrid vehicle 100 is actually used. For this reason, when the thermal stress which acts repeatedly is large, there exists a possibility of affecting an element lifetime.

  Referring to FIG. 3, when designing the lifetimes of switching elements Q1, Q2 corresponding to thermal stress, reference distribution 500 of temperature change amount ΔT is determined in advance. The size (thickness / width), material, and the like of the constituent elements of the switching elements Q1 and Q2 are determined by assuming thermal stress according to the reference distribution 500. For this reason, when the actual distribution 510 of the temperature change ΔT in actual use (hereinafter referred to as the actual distribution 510) is shifted to the high temperature side with respect to the reference distribution 500, the element lifetime becomes shorter than the assumed value. There is concern.

  For this reason, in consideration of the thermal stress caused by the temperature change of the switching element, it is understood that the temperature change amount ΔT needs to be managed in order to maintain the life of the switching element.

  As described above, the temperature rise phase in which the temperature change amount ΔT leading to thermal stress occurs is accompanied by charging / discharging of the main battery B such as an accelerator operation by the driver. Hereinafter, an operation that causes charging / discharging of the main battery B in which the temperature change amount ΔT is generated is referred to as a “load operation”.

  Even when engine 110 is started, electric power is output from main battery B in order to generate motoring torque by motor generator MG1. Moreover, the charging current of the main battery B also increases when the vehicle deceleration is large. That is, in addition to the acceleration traveling by the accelerator operation, the engine start and the generation of the regenerative braking force exceeding a predetermined level can be included in the load operation described above.

  The load operation can be detected based on, for example, a pedal operation (accelerator operation / brake operation) by a driver or a start command of the engine 110. Alternatively, it is possible to actually detect the load operation based on the battery current Ib. As shown in FIG. 3, in the present embodiment, it is assumed that the load flag FP is turned on when such a load operation is detected.

  In hybrid vehicle 100 according to the present embodiment, traveling control is performed in consideration of management control of temperature change amount ΔT as described below.

  FIG. 4 is a functional block diagram illustrating travel control of hybrid vehicle 100. The control configuration shown in FIG. 4 is provided as part of the function of the control device 50. Each functional block shown in the block diagram including FIG. 4 may be configured by a circuit (hardware) having a function corresponding to the block, or the ECU performs software processing according to a preset program. It may be realized by executing.

  Referring to FIG. 4, control device 50 includes a required power calculation unit 210, a total power control unit 220, a brake coordination control unit 250, and a temperature change restriction unit 400. The vehicle speed sensor 75 detects the vehicle speed Vs of the hybrid vehicle 100.

  The required power calculation unit 210 is based on the accelerator opening ACC and the vehicle speed Vs, and the vehicle required power Prq necessary for obtaining the driving force required for the vehicle operation requested by the driver (hereinafter also simply referred to as the required power Prq). Is calculated. The required power Prq calculated by the required power calculation unit 210 is input to the total power control unit 220.

  The total power control unit 220 further receives the SOC of the main battery B. Total power control unit 220 is the output power of the entire vehicle according to the following formula (1) according to the sum of charging power Pch required for charging main battery B calculated based on the SOC and required power Prq. The total power Pttl is calculated.

Pttl = Prq + Pch + Ploss (1)
In the equation (1), Ploss corresponds to the loss power in the travel of the hybrid vehicle 100. Regarding the loss power Ploss, it is preferable to create in advance a map for setting an appropriate value according to the vehicle running state (vehicle speed or the like). When the SOC is sufficiently high and charging of the main battery B is not necessary, Pch = 0 is set.

  Total power control unit 220 distributes total power Pttl calculated according to equation (1) to engine power Peg and motor powers Pmg1 and Pmg2. Motor power Pmg1 is the output power of motor generator MG1, and motor power Pmg2 is the output power of motor generator MG2. When power is generated by motor generators MG1 and MG2, Pmg2 and Pmg1 are set to negative values, respectively.

  Specifically, the total power control unit 220 determines the power distribution after determining whether or not the engine 110 is required to operate. Basically, operation of engine 110 is instructed when required power Prq cannot be secured only by the output power of motor generator MG2. When Pch> 0 is set to charge main battery B when the engine is stopped, engine 110 is started. The output power of motor generator MG2 is set within a range in which the output power of main battery B does not exceed output power upper limit value Wout.

  The total power control unit 220 sets the engine power Peg and the target engine speed Negr for obtaining the necessary engine torque based on the total power Pttl and the engine speed Neg when the engine is operated. That is, the charging power Pch added when charging the main battery B is reflected in the engine power Peg.

  Basically, the engine power Peg and the engine target rotation speed Negr are set so that the engine operating point defined by the combination of the engine torque and the rotation speed is within the highly efficient operation region. Therefore, basically, the acceleration request by the accelerator operation is responded by the output of motor generator MG2 from main battery B. For this reason, during acceleration traveling, heat is generated in the switching elements Q1, Q2 due to the discharge current from the main battery B.

  The engine ECU 280 is provided separately from the control device 50, and the fuel injection, ignition timing, and valve timing of the engine 110 are realized so that the engine power Peg and the engine target rotational speed Negr sent from the total power control unit 220 are realized. Control etc. Further, the motor powers Pmg1 and Pmg2 are set so that the total power Pttl is ensured. In this manner, power distribution between the engine power Peg and the motor powers Pmg1 and Pmg2 is executed with respect to the total power Pttl.

  In the power distribution, the motor powers Pmg1 and Pmg2 are set so that the input / output power for the main battery B is within the range of Win to Wout. That is, when the output power upper limit value Wout is low, the engine power Peg relatively increases.

  Motor power Pmg1 and Pmg2 are sent to MG1 control unit 301 and MG2 control unit 302. MG1 control unit 301 and MG2 control unit 302 set torque command values Tqcom (1) and Tqcom (2) of motor generators MG1 and MG2 so that motor generators MG1 and MG2 output motor powers Pmg1 and Pmg2, respectively. . Then, MG1 control unit 301 generates switching control signal SINV1 for inverter 20 so as to control the output torque of motor generator MG1 according to torque command value Tqcom (1). Similarly, MG2 control unit 302 generates switching control signal SINV2 for inverter 30 so as to control the output torque of motor generator MG2 in accordance with torque command value Tqcom (2).

  Motor power Pmg2 is set based on the output power required for driving and assisting driving force by motor generator MG2 by power distribution by total power control unit 220. At the time of regenerative braking, motor generator PMG2 is set to a negative value, so that motor generator MG2 generates power. Further, MG1 control unit 301 controls motor generator MG1 in accordance with motor power Pmg1, thereby controlling the power generated by motor generator MG1, that is, charging of main battery B.

  The brake cooperative control unit 250 calculates the total braking force required for the entire hybrid vehicle 100 based on the brake operation amount BRK and the vehicle speed Vs, and corresponds to the shared amount by the regenerative brake of the calculated total braking force. The regenerative brake request value Prbr is output. The regenerative brake request value Prbr is set in a range not exceeding the input upper limit power value Win of the main battery B.

  The total power control unit 220 sets the motor power Pmg2 reflecting the regenerative brake request value Prbr during regenerative braking. Further, total power control unit 220 calculates an actual regenerative brake value Prba based on the torque, rotation speed, etc. of motor generator MG2. The calculated regenerative brake value Prba is sent to the brake coordination control unit 250.

  The brake cooperative control unit 250 controls the braking force of a hydraulic brake (not shown) provided on each wheel of the hybrid vehicle 100 according to the shortage of the regenerative braking value Prba with respect to the total braking force. Thus, the necessary total control force is ensured by cooperatively controlling the regenerative brake by the motor generator MG2 and the hydraulic brake (not shown).

  Temperature sensor 78 detects the element temperature of switching elements Q1, Q2. For example, the temperature sensor 78 may be a temperature sensor built in the switching elements Q1, Q2 configured as an intelligent power module (IPM).

  The temperature change limiting unit 400 typically sets a limit value Plim for suppressing the temperature change amount ΔT of the switching element as needed based on the element temperature detected by the temperature sensor 78. When the limit value is set by the temperature change limiting unit 400, the total power control unit 220 adjusts the above-described power distribution so as to keep the limit value Plim.

  FIG. 5 is a functional block diagram illustrating the configuration of the temperature change restriction unit 400 according to the first embodiment.

  Referring to FIG. 5, temperature change restriction unit 400 includes a detection unit 405, a ΔT management unit 410, a reference distribution storage unit 420, a comparison unit 430, and a restriction setting unit 440.

The detection unit 405 turns on the load flag FP in response to the detection of the load operation. For example,
The detection unit 405 controls on / off of the load flag FP in response to an accelerator operation or a brake operation by the driver or an engine start command based on the power distribution control. Alternatively, the load operation may be detected based on the detected value of the battery current Ib.

  When the load flag FP is turned on by the detection unit 405, the ΔT management unit 410 obtains the temperature change amount ΔT in one load operation based on the element temperature Tsw from the temperature sensor 78 and for each load operation. The obtained temperature change amount ΔT is stored. As a result, the actual distribution 510 of the temperature change amount ΔT shown in FIG. 4 is accumulated in the ΔT management unit 410. On the other hand, the reference distribution storage unit 420 stores the reference distribution 500 shown in FIG.

  When the diagnosis instruction is input, the comparison unit 430 compares the reference distribution 500 stored in the reference distribution storage unit 420 with the actual distribution 510 based on the temperature change ΔT accumulated so far in the ΔT management unit 410. . The diagnosis instruction may be generated every N trips (N: natural number) of hybrid vehicle 100 or may be generated every predetermined travel distance. Alternatively, a diagnosis instruction may be generated for a certain period (every month, half a month, every year, etc.).

  The comparison unit 430 compares the performance distribution 510 and the reference distribution 500. Then, as shown in FIG. 4, the actual distribution 510 outputs an evaluation parameter PR that quantitatively indicates the degree of deviation from the reference distribution 500 toward the high temperature side. The evaluation parameter PR can be calculated, for example, corresponding to the area of the region 520 in FIG. Alternatively, the evaluation parameter PR may be calculated by presetting a relational expression for quantification based on the average value, standard deviation, maximum value, etc. of the performance distribution 510.

  Limit setting unit 440 sets limit value Plim to be sent to total power control unit 220 based on evaluation parameter PR calculated by comparison unit 430. For example, limit value Plim includes upper limit current Ib (lim) of battery current Ib and / or limit value Wout (lim) of output power upper limit value Wout. The upper limit current Ib (lim) limits the absolute value of the battery current Ib.

  When total power control unit 220 determines power output distribution within the range of limit value Plim, drive control of motor generators MG1 and MG2 by power input / output of main battery B, that is, main battery B and motor generators MG1 and MG2 Power conversion during is limited. In particular, the passing current of switching elements Q1, Q2 generated based on power conversion is limited. Under such a restriction, the temperature change ΔT caused by the switching operation in the switching elements Q1 and Q2 is also suppressed, so the actual distribution 510 shifted to the high temperature side is shifted to the low temperature side, and the reference distribution 500 Can approach.

  When the battery current Ib is limited by setting the upper limit current Ib (lim), the passing current of the switching elements Q1, Q2 is directly suppressed. As a result, the amount of heat generated during the load operation, that is, the temperature change amount ΔT can be suppressed.

  Further, when the output power upper limit value Wout is limited by the limit value Wout (lim), the battery current Ib is naturally suppressed accompanying the limitation of the output power. Furthermore, when the output power upper limit value Wout decreases, the power distribution is controlled in a direction in which traveling with the engine 110 stopped is difficult to apply. As a result, the engine 110 that has once been operated is unlikely to be stopped, so the frequency of engine start can be reduced. Since it is necessary to supply a relatively large current from the main battery B to the motor generator MG1 when starting the engine, the frequency of large temperature change ΔT is suppressed by reducing the frequency of starting the engine. Can be expected.

  FIG. 6 is a conceptual diagram schematically illustrating setting of the limit value Plim by the limit setting unit 440. The horizontal axis in FIG. 6 is the evaluation parameter PR calculated by the comparison unit 430, and the vertical axis in FIG. 6 indicates the limit value Plim.

  Referring to FIG. 6, when evaluation parameter PR is lower than threshold value P1, limit value Plim is set to level L1. This L1 indicates that the battery current Ib, the output power upper limit value Wout, and the like are not restricted from the management aspect of the temperature change amount ΔT. That is, at the level L1, these limit values are set to default values.

  When evaluation parameter PR becomes higher than threshold value P1, limit value Plim for limiting battery current Ib, output power upper limit value Wout, or the like is set so as to limit power conversion. In particular, it is preferable to set the limit value Plim so that the degree of limit increases as the evaluation parameter PR increases. In the example of FIG. 6, Ib (lim) and / or Wout (lim) are set to a value smaller than level L2 at level L3. A similar limit value Win (lim) can be set for the input power upper limit value Win that limits the charging of the main battery B.

  FIG. 7 is a flowchart illustrating temperature change suppression control in the electric vehicle according to the first embodiment of the present invention. The control device 50 repeatedly executes the control process according to the flowchart shown in FIG. 7 at predetermined intervals.

  Referring to FIG. 7, control device 50 determines whether or not a diagnosis instruction is generated in step S100. When no diagnostic instruction is generated (NO determination in S100), the control device 50 detects the temperature change ΔT of the element temperature Tsw in the load operation every time the load operation is detected in steps S105 and S110. And accumulate.

  When a diagnostic instruction is generated (when YES is determined in S100), control device 50 calculates the distribution of temperature variation ΔT accumulated so far in step S110. Thereby, the result distribution 510 shown in FIG. 4 is obtained.

  The control device 50 reads the reference distribution 500 in step S120, and compares the actual distribution 510 and the reference distribution 500 with respect to the temperature change ΔT in step S130. In step S130, as described above, the evaluation parameter PR is calculated based on the comparison of distributions. In step S140, the control device 50 sets the limit value Plim in power conversion based on the evaluation parameter PR calculated in step S130 as described in FIG.

  The limit value Plim set in step S140 is maintained until the next diagnosis instruction is issued, and is reflected in the subsequent vehicle travel. Thereby, drive control of motor generators MG1, MG2 by the power of main battery B is limited in a direction to suppress the temperature change amount ΔT by suppressing the passing current of the switching element.

  As can be understood from the flowchart of FIG. 7, the results of the temperature change amount ΔT after the limit value Plim is set are further accumulated in steps S105 and S110. When the next diagnosis instruction is issued, the results distribution of the temperature change amount ΔT is obtained again in steps S110 to S130 and compared with the reference distribution 500. The limit value Plim is updated according to the new comparison result. That is, the limit value Plim can be relaxed or strengthened according to the degree of improvement from the previous performance distribution. Alternatively, after the limit value Plim is provided, when the evaluation parameter PR returns to a value smaller than the threshold value P1, the limit value Plim can be returned to the default value.

  As described above, according to the power supply system for an electric vehicle according to the embodiment of the present invention, the performance distribution of the temperature change amount ΔT of the switching element in a relatively short time accompanying the load operation is periodically managed, It can be compared with the reference distribution used in the life design. When the actual distribution is shifted to the high temperature side as compared with the reference distribution, the actual distribution is brought closer to the reference distribution by setting the power conversion limit value Plim in a direction to suppress the passing current of the switching element. be able to. Thereby, it is possible to prevent the life of the switching element from being shortened due to excessive thermal stress acting on the switching element due to generation of the temperature change amount ΔT.

[Embodiment 2]
In the first embodiment, the limit value Plim for suppressing thermal stress is set by detecting the tendency that the actual distribution of the temperature variation ΔT deviates from the reference distribution to the higher temperature side. In the second embodiment, setting of a limit value Plim for preventing the actual distribution of the temperature change amount ΔT from deviating to the high temperature side will be described. As will be apparent from the following description, the control according to the second embodiment and its modification can be applied in combination with the control according to the first embodiment.

  FIG. 8 is a functional block diagram illustrating the configuration of the temperature change restriction unit 400 in the second embodiment. In the second embodiment, the configuration of the parts other than temperature change limiting unit 400 for setting limit value Plim is the same as that of the first embodiment, and therefore the description of the other parts will not be repeated.

  Referring to FIG. 8, temperature change restriction unit 400 according to the second embodiment includes a detection unit 405 and a restriction setting unit 450.

  The detection unit 405 is the same as that shown in FIG. 5 and turns on the load flag FP when a load operation is detected.

  When the load flag FP is turned on, the limit setting unit 450 sets the limit value Plim based on the temperature increase amount Tup of the switching elements Q1 and Q2 that are the load operation. For example, using the element temperature Tsw when the load flag FP is turned on as an initial value, the temperature increase amount Tup from the initial value can be obtained.

  Furthermore, the restriction setting unit 450 receives the cooling water temperature Twt and / or the ambient temperature Tar, which are state quantities related to the cooling capacity of the switching elements Q1, Q2. The cooling water temperature Twt indicates the refrigerant temperature in a cooling mechanism (not shown) for cooling the switching elements Q1, Q2. The ambient temperature Tar is the ambient temperature of the space where the switching elements Q1 and Q2 are disposed or a temperature measurement value related thereto. Therefore, when the cooling water temperature Twt and / or the ambient temperature Tar is low, the cooling capacity of the switching element is increased, so that the temperature change amount ΔT can be expected to be relatively suppressed with respect to the same passing current. .

  FIG. 9 is a diagram for explaining setting of limit values by the limit setting unit 450 according to the second embodiment. The horizontal axis Tup in FIG. 9 indicates the temperature rise amount Tup of the element temperature Tsw when the load operation is detected. The vertical axis represents the limit value Plim. Limit value Plim includes upper limit current Ib (lim) similar to that in the first embodiment and chargeable / dischargeable time T (lim) of main battery B. When chargeable / dischargeable time T (lim) has elapsed since the start of the load operation, power input / output to / from main battery B is prohibited. The chargeable / dischargeable time T (lim) can also be included in the limit value Plim in the first embodiment.

  Referring to FIG. 9, limit value Plim is set to level L1 while temperature rise amount Tup is up to threshold value T1. That is, the limit value is set to a default value, and the power conversion limit is not set in terms of the temperature rise amount Tup.

  On the other hand, when the temperature rise amount Tup exceeds the threshold value T1, the limit value is set, thereby limiting the battery current Ib or the chargeable / dischargeable time. The threshold value T1 is set corresponding to the reference distribution 500 shown in FIG. For example, the threshold T1 is set to a temperature higher than the average temperature Ta in the reference distribution 500.

  In the region where the temperature increase amount Tup> T1, the restriction on power conversion is strengthened as the temperature increase amount Tup increases. Specifically, the upper limit current Ib (lim) and the chargeable / dischargeable time T (lim) are set gradually smaller toward zero. When temperature increase amount Tup reaches upper limit temperature Tmax, Ib (lim) = 0 and / or T (lim) = 0, and charging / discharging of main battery B is prohibited. The upper limit temperature Tmax can be set corresponding to the upper limit temperature Tmax assumed in the reference distribution 500 shown in FIG.

  The limit value Plim may be changed according to the cooling capacity of the switching element. Specifically, when the cooling capacity is high, the threshold value T1 is preferably shifted to the high temperature side, whereas when the cooling capacity is low, the threshold value T1 is preferably shifted to the low temperature side.

  FIG. 10 is a flowchart illustrating suppression control of the temperature change amount in the electric vehicle according to the second embodiment of the present invention. The control device 50 repeatedly executes the control process according to the flowchart shown in FIG. 10 at predetermined intervals.

  Referring to FIG. 10, control device 50 determines whether or not a load operation is detected in step S200. The determination in step S200 can be executed based on the load flag FP.

  During detection of the load operation (when NO is determined in S200), control device 50 calculates temperature rise amount Tup in the load operation in step S210. In step S220, the control device 50 checks the cooling capacity of the switching element based on the cooling water temperature Twt and / or the ambient temperature Tar.

  In step S230, the control device 50 sets the limit value Plim for power conversion based on the temperature increase amount Tup calculated in step S210, as described in FIG. At this time, it is preferable to set the limit value Plim in consideration of the cooling capacity of the switching element obtained in step S220.

  Thereby, when the temperature increase amount Tup becomes large at the time of detecting the load operation, the current passing through the switching elements Q1, Q2 can be limited by suppressing the battery current Ib or by prohibiting charging / discharging. As a result, the temperature change amount ΔT caused by the heat generation of the switching elements Q1, Q2 can be suppressed.

  As described above, in the second embodiment, the limit value for power conversion can be set in association with the reference distribution 500 in accordance with the temperature increase amount Tup from the start of the load operation. As a result, the temperature change amount ΔT in the load operation can be managed so as to prevent the deviation from the reference distribution 500.

(Modification)
Referring to FIG. 8 again, according to the modification of the second embodiment, limit setting unit 450 predicts a temperature increase amount in the load operation when load flag FP is turned on. Based on the above, the limit value Plim is set. For example, limit setting unit 450 sets limit value Plim based on passing current Isw (hereinafter referred to as element current) of the switching element and battery current Ib.

  11 and 12 are diagrams for explaining setting of limit values by the limit setting unit 450 according to a modification of the second embodiment. The horizontal axis in FIG. 11 represents the passing current Isw or the battery current Ib.

  The vertical axis in FIG. 11 is the upper limit value fsw (lim) of the switching frequency in the converter 15 shown as one of the limit values Plim, and the vertical axis in FIG. 11 is the output power upper limit similar to that of the first embodiment. This is the limit value Wout (lim) of the value Wout.

  Referring to FIG. 11, in general, the power loss in the switching element increases as the switching frequency fsw increases, and as a result, the increase in the element temperature also increases. On the other hand, when the switching frequency fsw is lowered, the ripple current in the converter 15 increases. Therefore, the default value of the switching frequency fsw is set to an appropriate value that balances the limit of the ripple current and the loss of the switching element.

  On the other hand, at the time of detecting the load operation, if the element current Isw or the battery current Ib is larger than the threshold value I1, fsw (lim) is lower than the default value (level L1) so that the switching frequency of the converter 15 is lowered. Is lowered. Then, as the element current Isw or the battery current Ib increases, fsw (lim) further decreases.

  On the other hand, when the element current Isw or the battery current Ib is smaller than the threshold value I1, fsw (lim) is set to a default value. This threshold value I1 is set corresponding to the reference distribution 500 shown in FIG. For example, the threshold value I1 is set to a current value that causes a temperature rise corresponding to the threshold value T1 in FIG.

  Alternatively, as shown in FIG. 11, a limit value Wout (lim) of the output power upper limit value Wout may be set according to the element current Isw or the battery current Ib.

  Referring to FIG. 11, when load operation is detected, if element current Isw or battery current Ib is larger than threshold value I1, limit value Wout (lim) is lowered from the default value (level L1). Further, the limit value Wout (lim) is further lowered as the element current Isw or the battery current Ib increases.

  When element current Isw or battery current Ib reaches upper limit current Imax, limit value Wout (lim) = 0 and discharge of main battery B is prohibited. Note that the input power upper limit value Win can also be limited by a similar limit value Win (lim).

  In FIG. 12, the threshold value I1 can be set as in FIG. The upper limit current Imax is preferably set in consideration of the upper limit temperature Tmax in the reference distribution 500.

  11 and 12 can also be adjusted according to the cooling capacity of the switching element ascertained from the cooling water temperature Twt and / or the ambient temperature Tar, as in FIG.

  FIG. 13 is a flowchart illustrating suppression control of the temperature change amount in the electric vehicle according to the second embodiment of the present invention. The control device 50 repeatedly executes the control process according to the flowchart shown in FIG. 13 at predetermined intervals.

  Referring to FIG. 13, control device 50 determines whether or not a load operation is detected in step S <b> 200 similar to FIG. 10.

  During the detection of the load operation (when NO is determined in S200), control device 50 obtains a state quantity (data) for estimating the temperature increase amount in the load operation in step S215. In step S215, for example, the element current Isw and / or the battery current Ib are acquired.

  In step S220, the control device 50 checks the cooling capacity of the switching element based on the cooling water temperature Twt and / or the ambient temperature Tar.

  In step S235, the control device 50 sets the limit value Plim in power conversion based on the state quantity (data) acquired in step S215, as described in FIG. 11 and FIG. At this time, it is preferable to set the limit value Plim in consideration of the cooling capacity of the switching element obtained in step S220. As described above, limit value Plim set in step S235 includes upper limit value fsw (lim) of switching frequency in converter 15 and / or limit value Wout (lim) of output power upper limit value Wout.

  Accordingly, when the temperature increase amount Tup is estimated to be large when the load operation is detected, the temperature change amount ΔT caused by the heat generation of the switching elements Q1 and Q2 can be suppressed in advance by setting the limit value. I can expect.

  As described above, in the modification of the second embodiment, during the load operation, the power conversion limit value Plim can be set based on the state quantity (current data) that greatly affects the temperature rise. As a result, the temperature change amount ΔT in the load operation can be managed so as to prevent the deviation from the reference distribution 500.

  In the above-described first and second embodiments and the modifications thereof, limit value Plim is exemplified as appropriate. However, for this limit value, motor generator MG1, which uses electric power from main battery B in a direction to suppress heat generation in the switching element. As long as the driving control of MG2 can be limited, the setting of limiting value Plim in the first or second embodiment or its modification can be applied.

  Moreover, the adjustment of the limit value according to the cooling capacity of the switching element described in the second embodiment can be applied to the first embodiment. For example, in the first embodiment, the limit value Plim set in response to the diagnosis instruction is relaxed (cooling) according to the cooling capacity of the switching element ascertained from the cooling water temperature Twt and / or the ambient temperature Tar. It is also possible to use it for vehicle control after adjusting it so that the restriction is strengthened (when the capacity is high) or the restriction is strengthened (when the cooling capacity is low).

  Furthermore, in the first and second embodiments and the modifications thereof, the control for suppressing the temperature change amount ΔT in switching elements Q1 and Q2 constituting converter 15 has been described, but not shown constituting inverters 20 and 30. It is also possible to apply the control according to the present embodiment so as to suppress the temperature change amount of the switching element. Furthermore, for a switching element that constitutes a power converter that performs power conversion between a power storage device represented by main battery B and a traveling motor represented by motor generators MG1 and MG2, a switching element for load operation It is possible to apply the control according to the present embodiment to suppress the temperature change amount.

  It should be noted that the configuration of the drive system of the hybrid vehicle 100 is not limited to the illustration of FIG. Furthermore, in the present embodiment, a hybrid vehicle is exemplified as a representative example of an electric vehicle. However, the present invention can be applied to an electric vehicle not equipped with an engine or a fuel cell vehicle equipped with a fuel cell.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to protection control of a switching element in a power supply system of an electric vehicle.

  5 Ground line, 6, 7 Power line, 10, 13 Voltage sensor, 11, 27 Current sensor, 12, 78 Temperature sensor, 15 Converter, 20, 30 Inverter, 28 Rotation angle sensor, 50 Control unit (ECU), 52 ROM , 70 Accelerator pedal, 71 Brake pedal, 73 Accelerator opening sensor, 74 Brake pedal depression sensor, 75 Vehicle speed sensor, 100 Hybrid vehicle, 110 Engine, 112 Coolant temperature sensor, 120 Power split mechanism, 125 Output shaft, 130 Reducer 140 drive shaft, 150 wheels, 210 required power calculation unit, 220 total power control unit, 250 brake coordination control unit, 280 engine ECU, 301 MG1 control unit, 302 MG2 control unit, 400 temperature change limiting unit, 405 detection unit, 410 Δ Management unit, 420 Reference distribution storage unit, 430 Comparison unit, 440,450 Limit setting unit, 500 Reference distribution (ΔT), 510 Actual distribution (ΔT), ACC accelerator opening, B main battery, BRK brake operation amount, C0, C1 smoothing capacitor, D1, D2 antiparallel diode, FP load flag, I1, P1, T1 threshold, Ib battery current, Ib (lim) upper limit current (battery current), Imax upper limit current, Isw element current, L reactor, MCRT ( 1), MCRT (2) Motor current, MG1, MG2 Motor generator, N1, N2 Neutral point, Neg engine speed, Negr engine target speed, Nmt speed, PR evaluation parameter, Peg engine power, Plim limit value, Pmg1, Pmg1 Motor power, Prb Regenerative brake value, Prbr Regenerative brake required value, Prq Vehicle required power, Q1, Q2 Power semiconductor switching element, SCNV, SINV1, SINV2 Switching control signal, T (lim) Charging / discharging time, Ta average temperature (reference distribution), Tar Atmospheric temperature (switching element), Tb battery temperature, Tmax upper limit temperature, Tqcom torque command value, Tsw element temperature, Tup horizontal axis, Tup temperature rise, Twt cooling water temperature, U1, U2, V1, V2, W1, W2 Coil winding, VH DC voltage, Vb battery voltage, Vs vehicle speed, Win input power upper limit value, Win (lim) limit value (input power upper limit value), Wout output power upper limit value, Wout (lim) limit value (output power upper limit value) Value), fsw (lim) on switching frequency Value.

Claims (14)

An electric vehicle equipped with an electric motor for generating vehicle driving force,
A power storage device for storing electric power input / output to / from the electric motor;
A power converter configured to perform power conversion between the electric motor and the power storage device by on / off control of a switching element;
A control device for controlling the power conversion,
The controller is
A detection unit for detecting occurrence of a load operation that causes charging and discharging of the power storage device such that the temperature of the switching element rises;
An electric vehicle comprising: a limit setting unit for setting a limit value in the power conversion for suppressing a passing current of the switching element according to a temperature change amount of the switching element in each load operation. The controller is
A storage unit for storing a predetermined reference distribution for the temperature change amount;
Each time the load operation is detected, a result management unit for cumulatively storing the results of the temperature change amount in the load operation;
A comparison unit for comparing the actual distribution of the temperature change amount accumulated in the actual management unit and the reference distribution stored in the storage unit;
The electric vehicle according to claim 1, wherein the limit setting unit sets the limit value based on a comparison result by the comparison unit. The comparison unit calculates a parameter value that quantitatively indicates a degree of deviation of the actual distribution with respect to the reference distribution on the high temperature side according to the comparison of the reference distribution and the actual distribution,
The electric vehicle according to claim 2, wherein the limit setting unit sets the limit value so as to decrease the limit value from a default value in accordance with an increase in the parameter value.   The electric vehicle according to claim 3, wherein the limit setting unit returns the limit value to the default value when the parameter value decreases to a predetermined value when the limit value is decreased from the default value.   The electric vehicle according to any one of claims 2 to 4, wherein the limit value includes at least one of a current upper limit value of the power storage device and a limit value of an output power upper limit value of the power storage device.   The electric vehicle according to any one of claims 2 to 4, wherein the comparison unit compares the reference distribution and the actual distribution every time the electric vehicle travels a certain distance.   The electric vehicle according to any one of claims 2 to 4, wherein the comparison unit compares the reference distribution and the performance distribution every time a predetermined period of time elapses.   The electric vehicle according to claim 1, wherein the limit setting unit sets the limit value in accordance with a temperature increase amount of the switching element from the start of the load operation when the load operation occurs. The limit setting unit sets the limit value to decrease the limit value from a default value when the temperature increase amount is higher than a threshold value,
The electric vehicle according to claim 8, wherein the threshold value is higher than an average temperature in a predetermined reference distribution for the temperature change amount.   The electric vehicle according to claim 8 or 9, wherein the limit value includes at least one of a current upper limit value of the power storage device and a charge / discharge limit time of the power storage device.   The electric vehicle according to claim 1, wherein the limit setting unit sets the limit value according to current data corresponding to a passing current of the switching element when the load operation occurs. The limit setting unit sets the limit value to lower the limit value from a default value when the current data is higher than a threshold value,
The electric vehicle according to claim 11, wherein the threshold is set based on a predetermined reference distribution for the temperature change amount.   The electric vehicle according to claim 11 or 12, wherein the limit value includes a switching frequency upper limit value of the switching element in the power converter.   The limit setting unit further reflects the temperature data indicating the cooling capacity of the switching element, and sets the limit value so that the limit is relaxed when the cooling capacity is high than when the cooling capacity is low. The electric vehicle according to any one of claims 1 to 13.

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