Electric vehicle thermal management method and electric vehicle thermal management system

Abstract

The present invention comprises: a first coolant circuit which is provided with a first pump that circulates a coolant for cooling a drive system for driving an electric vehicle; a second coolant circuit which is provided with a series circuit and which is provided with a battery that supplies the drive system with power and a second pump that circulates a coolant for cooling the battery; two branch circuits which branch at respective positions that correspond to both ends of the series circuit of the second coolant circuit and which each merge with the first coolant circuit; and a first flow passage changing means via which switching is possible between a first state where the coolant flowing through the series circuit circulates in the second coolant circuit without passing the branch circuits or the first coolant circuit and a second state where the coolant flowing through the series circuit recirculates to the series circuit via the branch circuits and the first coolant circuit, wherein when normal charging is performed on the battery using a charger that is disposed in the first coolant circuit, the first pump is activated, and when the temperature of the battery is lower than the temperature of the coolant circulating in the first coolant circuit by a temperature equal to or higher than a prescribed temperature, the first flow passage changing means is set to the second state and the second pump is activated.

Description

Thermal management method for electric vehicles, and thermal management system for electric vehicles

[0001] This invention relates to a thermal management method for electric vehicles and a thermal management system for electric vehicles.

[0002] JP7222321B discloses a technology that controls the electric pump and the flow control means to increase the flow rate of the coolant circulating through the battery on the battery side compared to the flow rate of the coolant circulating through the first circuit on the battery side when the battery is being charged with power from an external power source.

[0003] However, in JP7222321B, only the battery is cooled during charging, and there is no mention of the power control unit circuit, which generates heat during normal charging. When the circulation of the cooling water in the first circuit resumes after charging is complete, the power control unit circuit is not sufficiently cooled. If driving is started in this state, the electric pump and radiator will immediately start to cool the power control unit circuit, worsening the fuel efficiency.

[0004] Therefore, the present invention aims to provide a thermal management method for electric vehicles and a thermal management system for electric vehicles that suppress the temperature rise of the refrigerant circulating in the power control unit (inverter) during normal power generation and reduce the power required for the circulation of the refrigerant.

[0005] According to one aspect of the present invention, there is a thermal management method for an electric vehicle, comprising: a first refrigerant circuit including a drive system for driving an electric vehicle and a first pump for circulating a refrigerant to cool the drive system; a second refrigerant circuit including a series circuit including a battery for supplying power to the drive system and a second pump for circulating a refrigerant to cool the battery; two branch circuits that branch off from positions at both ends of the series circuit of the second refrigerant circuit and merge into the first refrigerant circuit, respectively; and a first flow path changing means that can switch between a first state in which the refrigerant flowing through the series circuit circulates through the second refrigerant circuit without passing through the branch circuits or the first refrigerant circuit, and a second state in which the refrigerant flowing through the series circuit returns to the series circuit via the branch circuits and the first refrigerant circuit, wherein a charger for normal charging of the battery is located in the first refrigerant circuit and the first pump is started when normal charging is performed. In this method, when the temperature of the battery is lower than the temperature of the refrigerant circulating in the first refrigerant circuit by a predetermined temperature or more, the first flow path changing means is set to the second state and the second pump is started.

[0006] Figure 1 is a schematic diagram of the thermal management system of the electric vehicle according to this embodiment. Figure 2 is a schematic diagram showing the first operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 3 is a schematic diagram showing the second operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 4 is a schematic diagram showing the third operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 5 is a schematic diagram showing the fourth operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 6 is a diagram showing the region where the first operating state is selected during normal charging and the region where the second operating state is selected during normal charging, in a coordinate space with the battery temperature (Tb) and the refrigerant temperature (Tc) of the first refrigerant circuit as axes. Figure 7 is a flowchart for selecting the first operating state or the second operating state during normal charging in this embodiment. Figure 8 is a diagram showing the relationship between the refrigerant temperature of the first refrigerant circuit and the power consumption of the first pump. Figure 9 is a diagram showing the relationship between the charging time and the total power consumption of the first pump when the first operating state is selected during normal charging. Figure 10 shows the relationship between the charging time when the second operating state is selected during normal charging and the total power consumption, which is the sum of the total power consumption of the first pump and the total power consumption of the second pump. Figure 11 is a diagram for comparing the total power consumption when the first operating state is selected during normal charging and the total power consumption when the second operating state is selected during normal charging. Figure 12 shows the changes in the refrigerant temperature of the first refrigerant circuit and the battery temperature when normal charging is continued in the first operating state. Figure 13 shows the changes in the refrigerant temperature of the first refrigerant circuit and the battery temperature when normal charging is continued in the second operating state.

[0007] Embodiments of the present invention will be described below with reference to the drawings.

[0008] Figure 1 is a schematic diagram of the thermal management system for an electric vehicle according to this embodiment. This thermal management system (TM) is installed, for example, in an electric vehicle. Note that the term "electric vehicle" here includes not only BEVs (Battery Electric Vehicles) but also HEVs (Hybrid Electric Vehicles).

[0009] The thermal management system (TM) includes a first refrigerant circuit 1, a second refrigerant circuit 2, a third refrigerant circuit 3, a first branch circuit 4, a second branch circuit 5, a third branch circuit 6, and a control unit 7.

[0010] The first refrigerant circuit 1 includes a first pump 101, an inverter 102, a drive motor 103, a DC / DC converter 104, a charger 105, a first temperature sensor 106, a first valve 107, a first connection part 108, a radiator 109, a first reservoir tank 110, and a second connection part 111, and is arranged in the first refrigerant circuit 1 so that the refrigerant circulates in the order described above.

[0011] The first pump 101 supplies refrigerant (water) circulating in the first refrigerant circuit 1 to the inverter 102.

[0012] The inverter 102 converts the DC voltage of the battery 202 located in the second refrigerant circuit 2 into a three-phase AC voltage based on a PWM signal input from the control unit 7, for example, and supplies it to the drive motor 103.

[0013] The drive motor 103 is driven by a three-phase AC voltage supplied from the inverter 102, thereby propelling the electric vehicle. Furthermore, when regenerative power is generated, the drive motor 103 charges the battery 202 via the inverter 102.

[0014] The DC / DC converter 104, for example, steps down the output voltage of the battery 202 and supplies it to auxiliary equipment.

[0015] The charger 105 is connected to an external source (charging station) and converts the AC voltage supplied from the external source into a DC voltage to charge the battery 202 (normal charging). The charger 105 has a socket (not shown) that engages with an external connector, and outputs a detection signal to the control unit 7 when the external connector engages with the socket (not shown).

[0016] Furthermore, electric vehicles are also equipped with a rapid charger for rapidly charging the battery 202, and it is possible to charge the battery 202 by directly supplying an externally supplied DC voltage (the rated voltage of the battery 202) to the battery 202.

[0017] The first temperature sensor 106 detects the temperature of the refrigerant immediately after it has passed through the charger 105. During normal charging, the charger 105 generates heat when it is in operation, but the inverter 102, drive motor 103, and DC / DC converter 104 are normally stopped. Therefore, when normal charging is performed for a long period of time, the temperature of the refrigerant in the first refrigerant circuit 1 is highest immediately after it has passed through the charger 105.

[0018] The first valve 107 has its refrigerant input side (IN) connected to the charger 105, its first refrigerant output side (OUT1) connected to the first connection part 108, and its second refrigerant output side (OUT2) connected to the third branch circuit 6.

[0019] The first valve 107 is a three-way valve that can be switched between two connection states (third state) where the input side (IN) and the first output side (OUT1) are connected and the input side (IN) and the second output side (OUT2) are blocked, and a connection state (fourth state) where the input side (IN) and the first output side (OUT1) are blocked and the input side (IN) and the second output side (OUT2) are connected, under control from the control unit 7.

[0020] The first connection section 108 connects the first refrigerant circuit 1 and the second branch circuit 5 to form a three-way intersection for the refrigerant.

[0021] The radiator 109 cools the refrigerant by exchanging heat with the outside air. The radiator 109 is positioned opposite the grill shutter 113 located at the bottom of the front bumper of the electric vehicle. The rear side of the radiator 109 is positioned between the fans 112, and the fans 112 rotate to draw in air from the grill shutter 113 and supply it to the radiator 109. When the radiator 109 is cooling the refrigerant, the grill shutter 113 is opened and the fans 112 are activated.

[0022] The first reservoir tank 110 temporarily stores the refrigerant discharged from the radiator 109, and when the first pump 101 is activated, it supplies the stored refrigerant to the first pump 101.

[0023] The second connection section 111 connects the first refrigerant circuit 1 and the first branch circuit 4 to form a three-way intersection for the refrigerant.

[0024] The second refrigerant circuit 2 includes a second pump 201, a battery 202, a second temperature sensor 203, a second valve 204, a third connection 205, a third valve 206, a chiller 207, a fourth connection 208, and a second reservoir tank 209, and the components are arranged in the second refrigerant circuit 2 so that the refrigerant circulates in the order described above. Furthermore, for convenience, in the second refrigerant circuit 2, the portion from the fourth connection 208 through the second pump 201, battery 202, etc. to the third connection 205 or the third valve 206 is referred to as the series circuit 21, and the portion from the third valve 206 through the chiller 207 to the fourth connection 208 is referred to as the return circuit 22.

[0025] The second pump 201 supplies refrigerant (water) circulating in the second refrigerant circuit 2 to the battery 202. The second pump 201 is activated when the control unit 7 executes the second operating state described later, but it is also activated when the temperature of the battery 202 exceeds a predetermined temperature (Tbpd, Figure 6).

[0026] The battery 202 is cooled (or heated) by a refrigerant so that its temperature is within an appropriate temperature range. A heater 210 (e.g., a PTC heater) is also attached to the battery 202, and is activated by the control unit 7 to heat the battery 202 when heating by the refrigerant is difficult.

[0027] The battery 202 outputs information about its state of charge (SOC) to the control unit 7.

[0028] The second temperature sensor 203 directly detects the cell temperature of the battery 202. Alternatively, the second temperature sensor 203 detects the temperature of the refrigerant circulating in the second refrigerant circuit 2, specifically the temperature of the refrigerant immediately after it has flowed through the battery 202. Therefore, the second temperature sensor 203 effectively detects the temperature of the battery 202.

[0029] The second valve 204 is normally open, but closes during the fourth operating state, which will be described later.

[0030] The third connection section 205 connects the second refrigerant circuit 2 and the third branch circuit 6 to form a three-way intersection for the refrigerant.

[0031] The third valve 206 has its refrigerant input side (IN) connected to the third connection part 205 side, its first refrigerant output side (OUT1) connected to the chiller 207 side, and its second refrigerant output side (OUT2) connected to the second branch circuit 5.

[0032] The third valve 206 is a three-way valve that can be mutually switched between a connection state (first state) in which the input side (IN) and the first output side (OUT1) communicate with each other and the input (IN) side and the second output side (OUT2) are blocked, and a connection state (second state) in which the input side (IN) and the first output side (OUT1) are blocked and the input (IN) side and the second output side (OUT2) communicate with each other, under the control from the control unit 7.

[0033] The chiller 207 performs heat exchange between the refrigerant circulating in the second refrigerant circuit 2 and the refrigerant circulating in the third refrigerant circuit 3.

[0034] The fourth connection part 208 connects the second refrigerant circuit 2 and the first branch circuit 4 to form a three-way junction of the refrigerant.

[0035] The second reservoir tank 209 temporarily stores the refrigerant flowing through the fourth connection part 208 and supplies the stored refrigerant to the second pump 201 when the second pump 201 is started.

[0036] The third refrigerant circuit 3 includes a compressor 31, a condenser 32, an expansion valve 33, and a chiller 207, and is arranged in the third refrigerant circuit 3 such that the refrigerant circulates in the order described above.

[0037] The compressor 31 compresses (heats) the refrigerant (for example, an alternative refrigerant such as HFC134a) circulating in the third refrigerant circuit 3 and supplies it to the condenser 32.

[0038] The condenser 32 is arranged, for example, in a path for supplying heating air indoors, and heats the air by performing heat exchange between the air supplied from the outside and the refrigerant. The heated air is supplied into the vehicle interior.

[0039] The expansion valve 33 expands (cools) the refrigerant and supplies it to the chiller 207.

[0040] The control unit 7 controls the first pump 101, inverter 102, first valve 107, fan 112, grill shutter 113, second pump 201, second valve 204, third valve 206, and compressor 31.

[0041] The control unit 7 receives information on the refrigerant temperature detected by the first temperature sensor 106, the battery temperature detected by the second temperature sensor 203, and the state of charge (SOC) of the battery 202, and receives a detection signal from the charger 105.

[0042] The control unit 7 is equipped with a program for executing the thermal management system of this embodiment, and when the battery 202 is being normally charged using the charger 105, it performs the first to fourth operating states described later.

[0043] The control unit 7 functions, for example, as a vehicle controller that controls the entire vehicle. Based on the driver's accelerator operation, the control unit 7 generates a PWM signal and outputs it to the inverter 102, thereby converting the DC voltage of the battery 202 into a three-phase AC voltage and supplying power to the drive motor 103.

[0044] The third refrigerant circuit 3 is configured to switch between a path (first path) that supplies refrigerant to the condenser 32 and a path (second path) that supplies refrigerant to an external condenser (not shown). The external condenser (not shown) is, for example, located adjacent to the radiator 109, and when the fan 112 and grill shutter 113 are activated, heat exchange occurs between the refrigerant circulating in the third refrigerant circuit 3 and the outside air.

[0045] When the temperature of the battery 202 rises above a predetermined temperature (Tbpd), the control unit 7 starts the second pump 201, selects the second path (or the first path when the driver requests heating) for the third refrigerant circuit 3, and starts the compressor 31.

[0046] [Operating State of Thermal Management System] Figure 2 is a schematic diagram showing the first operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 3 is a schematic diagram showing the second operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 4 is a schematic diagram showing the third operating state of the thermal management system of the electric vehicle according to this embodiment. Figure 5 is a schematic diagram showing the fourth operating state of the thermal management system of the electric vehicle according to this embodiment.

[0047] The first and second operating states in this embodiment assume the operating state when the battery 202 is being charged under normal conditions. Therefore, at this time, the electric vehicle is stopped, and the inverter 102 and the drive motor 103 are also stopped.

[0048] As shown in Figure 2, in the first operating state, the control unit 7 starts the first pump 101, opens the first output side (OUT1) of the first valve 107 and closes the second output side (OUT2). The control unit 7 also starts the second pump 201, opens the second valve 204, opens the first output side (OUT1) of the third valve 206 and closes the second output side (OUT2). Therefore, the refrigerants in the first refrigerant circuit 1 and the second refrigerant circuit 2 do not mix with each other.

[0049] In electric vehicles, if the first operating state is performed for a long period of time, or if the first operating state is performed immediately after an electric vehicle has been stopped, the temperature of the refrigerant circulating in the first refrigerant circuit 1 may exceed a predetermined upper limit temperature. In this case, the fan 112 and the grill shutter 113 are activated, and heat exchange between the refrigerant and the outside air takes place in the radiator 109, cooling the refrigerant.

[0050] Furthermore, if there is no need to cool the battery 202, or if the compressor 31 is not started (air conditioning is not used), the second pump 201 will not start.

[0051] As shown in Figure 3, in the second operating state, the control unit 7 starts the first pump 101, opens the first output side (OUT1) of the first valve 107 and closes the second output side (OUT2). The control unit 7 also starts the second pump 201, opens the second valve 204, closes the first output side (OUT1) of the third valve 206 and opens the second output side (OUT2).

[0052] In the second operating state, the refrigerant that has flowed through the third valve 206 is introduced into the second branch circuit 5, where it merges with the refrigerant circulating in the first refrigerant circuit 1 at the first connection 108. At the second connection 111, it branches off from the refrigerant circulating in the first refrigerant circuit 1 and is introduced into the first branch circuit 4, and at the fourth connection 208, it returns to the second refrigerant circuit 2, thus creating a circulating path.

[0053] Therefore, the refrigerant circulating in the first refrigerant circuit 1 exchanges heat with the refrigerant flowing in from the second refrigerant circuit 2 in the region between the first connection part 108 and the second connection part 111. Thus, when the charger 105 generates heat, the temperature rise of the refrigerant circulating in the first refrigerant is suppressed more effectively in the second operating state than in the first operating state.

[0054] In the second operating state, the flow rate of refrigerant into the chiller 207 becomes zero, and the compressor 31 is also stopped. The second operating state is executed in electric vehicles where the refrigerant temperature has dropped to approximately ambient temperature due to prolonged shutdown.

[0055] As shown in Figure 4, in the third operating state, the control unit 7 starts the first pump 101, closes the first output side (OUT1) and opens the second output side (OUT2) of the first valve 107. The control unit 7 also starts the second pump 201, opens the second valve 204, opens the first output side (OUT1) and closes the second output side (OUT2) of the third valve 206. Furthermore, in the third operating state, the control unit 7 starts the compressor 31.

[0056] The third operating state is a state in which exhaust heat from the inverter 102, drive motor 103, DC / DC converter 104, charger 105, and battery 202 is supplied to the third refrigerant circuit 3 via the chiller 207, and the operation (thermal recovery) is performed to release the heat originating from said exhaust heat from the capacitor 32 or an external capacitor (illustrated). The third operating state is executed when the temperature of the refrigerant circulating in the first refrigerant circuit 1 becomes relatively high.

[0057] As shown in Figure 5, in the fourth operating state, the control unit 7 performs control similar to that in the third operating state, but stops the second pump 201 and closes the second valve 204. The fourth operating state is applied, for example, when the temperature of the battery 202 is near the lower limit of the temperature range in which the battery 202 can output at its rated output, and supplying refrigerant cooled by the chiller 207 to the battery 202 in this state may cause the temperature of the battery 202 to drop further, making it impossible to secure the output of the battery 202. The fourth operating state is also applied, for example, when the temperature of the refrigerant supplied from the first refrigerant circuit 1 when the third operating state is selected exceeds the upper limit temperature (a temperature higher than the predetermined temperature (Tbpd)) set to suppress thermal runaway of the battery 202, and there is a risk that thermal runaway of the battery 202 may occur when the refrigerant is supplied to the battery 202.

[0058] [First Operating State and Second Operating State] Figure 6 shows the region in which the first operating state is selected during normal charging and the region in which the second operating state is selected during normal charging, in a coordinate space with the temperature of the battery 202 (Tb) and the refrigerant temperature of the first refrigerant circuit 1 (Tc) as axes.

[0059] When the electric vehicle has been stopped for a long time and the battery 202 is being charged normally by the charger 105, and there is no request for heating, the control unit 7 executes either the first operating state or the second operating state. The control unit 7 selects the state that results in lower power consumption based on the relationship between the temperature (Tc) of the refrigerant circulating in the first refrigerant circuit 1 and the temperature (Tb) of the battery 202.

[0060] The control unit 7 selects a first operating state when the temperature (Tb) of the battery 202 exceeds a predetermined temperature (Tbpd (for example, 35°C)). When the temperature (Tb) of the battery 202 exceeds the predetermined temperature (Tbpd), the compressor 31 will start up to cool the battery 202. Therefore, the above selection is made in order to avoid the consumption of the compressor 31.

[0061] The control unit 7 selects a second operating state when the temperature of the battery 202 (Tb) is below a predetermined temperature (Tbpd) and the difference (ΔT) obtained by subtracting the temperature of the battery 202 (Tb = Tbk) from the temperature of the refrigerant circulating in the first refrigerant circuit 1 (Tc = Tbk + ΔT) is greater than or equal to a predetermined threshold (Tth) (for example, 5 [°C]), and selects a first operating state when it is lower than the predetermined value.

[0062] This allows for efficient suppression of the temperature rise of the refrigerant circulating in the first refrigerant circuit 1 (charger 105). However, if the difference (ΔT) is lower than the threshold (Tth), or even negative, the temperature rise of the refrigerant circulating in the first refrigerant circuit 1 (charger 105) cannot be efficiently suppressed, and the power consumption of the second pump 201, which is activated in the second operating state, is wasted.

[0063] Based on the above, the second operating state is selected when the temperature (Tc) of the battery 202 is below a predetermined temperature (Tc), and the difference (Tth) obtained by subtracting the temperature of the battery 202 (Tb = Tbk (≤ Tbpd)) from the temperature of the refrigerant circulating in the first refrigerant circuit 1 (Tc = Tbk + Tth) is greater than or equal to a predetermined value (for example, 5 [°C]) (the area shown by hatching in Figure 6). Otherwise, the first operating state is selected.

[0064] As described later, the control unit 7 can calculate the charging duration from the start of normal charging of the battery 202 until the battery 202 reaches the charge level of a full charge (for example, 80%). Then, as described later, the control unit 7 can compare the total power consumption when the battery 202 is charged by the charging duration while continuing the first operating state with the total power consumption when the battery 202 is charged by the charging duration while continuing the second operating state, and select the operating state with the lower total power consumption.

[0065] [Control Flow] Figure 7 is a flow diagram for selecting the first or second operating state during normal charging in this embodiment. Figure 8 is a diagram showing the relationship between the temperature of the refrigerant in the first refrigerant circuit 1 and the power consumption of the first pump 101. Figure 9 is a diagram showing the relationship between the charging time (t) and the total power consumption (W1) of the first pump 101 when the first operating state is selected during normal charging. Figure 10 is a diagram showing the relationship between the charging time (t) and the total power consumption (W2), which is the sum of the total power consumption of the first pump 101 and the total power consumption of the second pump 201, when the second operating state is selected during normal charging. Figure 11 is a diagram for comparing the total power consumption (W1) when the first operating state is selected during normal charging and the total power consumption (W2) when the second operating state is selected during normal charging.

[0066] In step S701, the control unit 7 determines whether or not normal charging is in progress. If the answer is YES, it proceeds to step S702; otherwise, it proceeds to END. The control unit 7 determines that normal charging is in progress if a detection signal is input from the charger 105, and determines that normal charging is not in progress if no detection signal is input from the charger 105.

[0067] In step S702, the control unit 7 determines whether or not thermal recovery is in progress (whether the third or fourth operating state has already been selected). If the answer is YES, the unit proceeds to step S703; otherwise, the unit proceeds to END.

[0068] In step S703, the control unit 7 refers to the temperature information detected by the second temperature sensor 203 and determines whether the temperature (Tb) of the battery 202 is below a predetermined temperature (Tbpd). If the answer is YES, the unit proceeds to step S704; otherwise, the unit proceeds to step S708.

[0069] In step S704, the control unit 7 refers to the temperature information detected by the first temperature sensor 106 and the temperature information detected by the second temperature sensor 203, and determines whether the difference (ΔT) obtained by subtracting the temperature of the battery 202 (Tb) from the temperature of the refrigerant circulating in the first refrigerant circuit 1 (Tc) is greater than or equal to a predetermined threshold (Tth). If the answer is YES, the unit proceeds to step S705; otherwise, the unit proceeds to step S708.

[0070] In step S705, the control unit 7 determines the charging duration (t) until the battery 202 reaches the charge level of full charge, based on the charge level of the battery 202 at the start of charging (SOC1), the charge level of the battery 202 at full charge (SOC2) (fixed value), the current value flowing to the battery 202 during normal charging (fixed value (I)), and the capacity of the battery 202 (fixed value (C)). ｃｈｇ Calculate = A・C(SOC2-SOC1) / I (where A is a constant).

[0071] In step S706, the control unit 7 calculates the charging duration (t ｃｈｇ The total power consumption (W1) when the first operating state is maintained and the total power consumption (W2) when the second operating state is maintained are predicted.

[0072] As shown in Figure 8, the control unit 7 efficiently cools the heat-generating parts with refrigerant by setting the power consumption (output) of the first pump 101 (and the second pump 201) to increase linearly as the temperature of the refrigerant rises.

[0073] Therefore, as shown in Figure 9, when the control unit 7 continues the first operating state (the first pump 101 is operating and the second pump 201 is stopped), the total power consumption (W1) has a quadratic shape obtained by integrating the curve (linear function) shown in Figure 8 with respect to the charging time (t). Furthermore, the curve representing the total power consumption (W1) shifts to the left as the temperature of the refrigerant at the start of charging increases, and conversely, the curve shifts to the right as the temperature of the refrigerant at the start of charging decreases.

[0074] Further, as shown in FIG. 10, the total power consumption (W2) when the control unit 7 continues the second operation state (the first pump 101 and the second pump 201 are operating) also becomes a curve similar to the curve shown in FIG. 9. Then, as the temperature of the refrigerant at the start of charging becomes higher, the curve representing the total power consumption (W2) shifts to the left, and conversely, as the temperature of the refrigerant at the start of charging becomes lower, the curve shifts to the right. Note that the curves in FIGS. 9 and 10 are prepared in advance as maps through experiments or the like, and the total power consumption (W1) and the total power consumption (W2) may be calculated by inputting the temperature of the refrigerant at the start of normal charging and the charging duration (t ｃｈｇ ).

[0075] For example, when the temperature of the refrigerant in the first operation state is the same as the temperature of the refrigerant in the second operation state, in the second operation state, since the first pump 101 and the second pump 201 are operating, the power consumption (W / h) is larger than the power consumption (W / h) in the first operation state where only the first pump 101 is operating.

[0076] On the other hand, in the case of the second operation state, since the volume of the refrigerant receiving heat from the charger 105 is larger than that in the first operation state, the heat capacity of the entire refrigerant is higher than that in the first operation state, and accordingly, the increase amount (the slope of the curve) of the total power consumption (W2) with respect to the time change is lower than that of the total power consumption (W1) (see FIG. 10).

[0077] Therefore, the magnitude relationship between the total power consumption (W1) and the total power consumption (W2) changes depending on the magnitude of the charging duration (t ｃｈｇ ).

[0078] As shown in FIG. 11, when the total power consumption (Wa) and the total power consumption (Wb) are shown simultaneously, when the charging time (t) is shorter than a predetermined time (t ｐｄ ), the total power consumption (W2) is greater than or equal to the total power consumption (W1). However, when the charging time (t) is longer than the predetermined time (t ｐｄ ), the total power consumption (W1) is greater than the total power consumption (W2). Therefore, by calculating the charging duration (t ｃｈｇ ) and calculating the total power consumption (W1) and the total power consumption (W1) as functions of the charging time (t), the predetermined time (t ｐｄ ) is calculated, and the charging duration (t ｃｈｇ ) and the predetermined time (tｐｄ The system selects either the first operating state (total power consumption (W1)) or the second operating state (total power consumption (W2)) by comparing its magnitude with the other values.

[0079] Furthermore, if the temperature of the refrigerant in the first refrigerant circuit 1 and the temperature of the battery 202 are approximately constant at the start of normal charging, a predetermined time (t ｐｄ ) can be kept constant. In this case, the charging duration (t ｃｈｇ ) calculate the charging duration (t ｃｈｇ ) and a predetermined time (t ｐｄ By comparing the relative magnitudes of the two values, it is also possible to select either the first operating state (total power consumption (W1)) or the second operating state (total power consumption (W2)).

[0080] Returning to Figure 7, in step S707, the control unit 7 determines whether the total power consumption (Wb) is lower than the total power consumption (W1). If the answer is YES, the unit proceeds to step S708; otherwise, it proceeds to step S709.

[0081] In step S708, the control unit 7 selects a second operating state.

[0082] In step S709, the control unit 7 selects a first operating state.

[0083] [Time Chart] Figure 12 shows the changes in the temperature of the refrigerant in the first refrigerant circuit 1 and the temperature of the battery 202 when normal charging is continued in the first operating state. Figure 13 shows the changes in the temperature of the refrigerant in the first refrigerant circuit 1 and the temperature of the battery 202 when normal charging is continued in the second operating state.

[0084] Figures 12 and 13 show the case where normal charging of the battery 202 using the charger 105 is started at time t0 and normal charging is continued until time t1. It is also assumed that the temperature of the refrigerant in the first refrigerant circuit 1 is Tc0 and the temperature of the battery 202 is Tb0 (< Tc0) at time t0.

[0085] As shown in Figure 12, when the first operating state is selected and normal charging of the battery 202 is started, the charger 105 generates heat after time t0, causing the temperature (Tc) of the refrigerant circulating in the first refrigerant circuit 1 to rise and reach Tc1 at time t1. On the other hand, since the battery 202 is charged by normal charging, the amount of heat generated is low, and the temperature (Tb) of the battery 202 remains at a temperature (Tb1) that is slightly higher than the temperature (Tb0) at time t0, even at time t1.

[0086] After time t1, when the electric vehicle (drive system including inverter 102 and drive motor 103) is driven, the temperature of the refrigerant circulating in the first refrigerant circuit 1 quickly reaches the upper limit temperature required to protect the drive system, and the radiator 109 (fan 112, grill shutter 113) begins to cool the refrigerant. As a result, the radiator 109 (fan 112, grill shutter 113) consumes extra power.

[0087] As shown in Figure 13, when the second operating state is selected and normal charging of the battery 202 is started, in the second operating state, the first refrigerant circuit 1 and the second refrigerant circuit 2 (the range from the fourth connection part 208 to the third valve 206 via the battery 202) are connected to each other by the first branch circuit 4 and the second branch circuit 5, and refrigerants with different temperatures mix with each other, resulting in an uneven temperature distribution of the refrigerant. Therefore, even if charging by the charger 105 starts at time t0 and the charger 105 starts to generate heat, the temperature of the refrigerant circulating in the first refrigerant circuit 1 and the temperature of the battery 202 exhibit unstable behavior (oscillation with a predetermined amplitude) until, for example, time t0'.

[0088] After time t0', when the temperature distribution of the refrigerant becomes relatively uniform, the temperature of the refrigerant circulating by the first pump 101 and the second pump 201 gradually rises, and the battery 202 also gradually rises due to the heat from the refrigerant.

[0089] At time t1, the refrigerant temperature (Tc) becomes, for example, Tc2, and the battery temperature (Tb) becomes Tb2, both of which are lower than Tc1. As a result, even when the electric vehicle is driven afterward, the power consumption related to the radiator 109 (fan 112, grill shutter 113) can be reduced. Furthermore, the compressor 31 will not start unless the battery temperature (Tb = Tb2) exceeds a predetermined temperature (Tbpd), and if it exceeds the predetermined temperature (Tbpd), it switches to the first operating state, thereby reducing the supply of heat to the battery 202 via the refrigerant and allowing the compressor 31 to stop earlier, thus reducing power consumption.

[0090] [Effects of this embodiment] The heat management method for an electric vehicle of this embodiment includes: a first refrigerant circuit 1 including a drive system (inverter 102, drive motor 103) that drives the electric vehicle and a first pump 101 that circulates a refrigerant to cool the drive system (inverter 102, drive motor 103); a second refrigerant circuit 2 including a series circuit 21 including a battery 202 that supplies power to the drive system (inverter 102, drive motor 103) and a second pump 201 that circulates a refrigerant to cool the battery 202; two branch circuits (first branch circuit 4, second branch circuit 5) that branch off from positions at both ends of the series circuit 21 of the second refrigerant circuit 2 and merge into the first refrigerant circuit 1, respectively; and the refrigerant flowing through the series circuit 21 entering the branch circuits (first branch circuit 4, second branch circuit 5) or the first refrigerant circuit 1. A thermal management method for an electric vehicle includes a first flow path changing means (third valve 206) that can switch between a first state in which the refrigerant circulates through the second refrigerant circuit 2 (series circuit 21, return circuit 22) without passing through the first refrigerant circuit 1, and a second state in which the refrigerant circulating through the series circuit 21 returns to the series circuit 21 via the branch circuits (first branch circuit 4, second branch circuit 5) and the first refrigerant circuit 1, wherein a charger 105 for normal charging of the battery 202 is located in the first refrigerant circuit 1, and a first pump 101 is started when normal charging is performed, wherein the first flow path changing means (third valve 206) is set to the second state and the second pump 201 is started (the second operating state is selected) when the temperature of the battery 202 is lower than the temperature of the refrigerant circulating through the first refrigerant circuit 1 by a predetermined temperature (threshold (Tch)).

[0091] By selecting the second operating state using the method described above, the heat generated in the charger 105 can be diffused to the refrigerant flowing through the first refrigerant circuit 1, the branch circuits (first branch circuit 4, second branch circuit 5), and the second refrigerant circuit 2 (series circuit 21). This results in a greater heat capacity of the refrigerant compared to circulating the refrigerant within the first refrigerant circuit 1 (selecting the first operating state). Furthermore, during normal power generation, the current input to the battery 202 is small, thus suppressing the amount of heat generated by the battery 202. Consequently, the temperature rise of the refrigerant flowing through the first refrigerant circuit 1 can be suppressed. Even after the battery 202 is charged and the electric vehicle starts running (even when the drive motor 103, inverter 102, etc. are driven), cooling of the first refrigerant circuit 1 is not immediately necessary, thereby reducing power consumption.

[0092] The thermal management method for the electric vehicle of this embodiment includes: a first refrigerant circuit 1 including a drive system (inverter 102, drive motor 103) that drives the electric vehicle and a first pump 101 that circulates a refrigerant to cool the drive system (inverter 102, drive motor 103); a series circuit 21 including a battery 202 that supplies power to the drive system (inverter 102, drive motor 103) and a second pump 201 that circulates a refrigerant to cool the battery 202; a second refrigerant circuit 2 including a feedback circuit 22 that connects both ends of the series circuit 21; a first branch circuit 4 that branches off from the first refrigerant circuit 1 and joins the upstream side of the series circuit 21; and a second branch circuit that branches off from the downstream side of the series circuit 21 of the second refrigerant circuit 2 and joins the first refrigerant circuit 1 at a position different from the connection position between the first refrigerant circuit 1 and the first branch circuit 4. A thermal management method for an electric vehicle, comprising: circuit 5; a first flow path changing means (third valve 206) positioned at the connection point between the second refrigerant circuit 2 and the second branch circuit 5, which is mutually switchable between a first state in which the series circuit 21 is connected to the feedback circuit 22 and the series circuit 21 is disconnected from the second branch circuit 5; and a second state in which the series circuit 21 is disconnected from the feedback circuit 22 and the series circuit 21 is connected to the second branch circuit 5; a charger 105 for normal charging of the battery 202 is positioned in the first refrigerant circuit 1, and a first pump 101 is started when normal charging is performed, wherein the first flow path changing means (third valve 206) is set to the second state and the second pump 201 is started (selecting the second operating state) when the temperature of the battery 202 is lower than the temperature of the refrigerant circulating in the first refrigerant circuit 1 by a predetermined temperature (threshold (Tth));

[0093] By selecting the second operating state using the method described above, the heat generated by the charger 105 can be diffused to the refrigerant flowing through the first refrigerant circuit 1, the branch circuits (first branch circuit 4, second branch circuit 5), and the second refrigerant circuit 2 (series circuit 21). This results in a larger heat capacity for the refrigerant compared to circulating the refrigerant within the first refrigerant circuit 1 (selecting the first operating state). Furthermore, during normal power generation, the current input to the battery 202 is small, thus suppressing the amount of heat generated by the battery 202. Consequently, the temperature rise of the refrigerant flowing through the first refrigerant circuit 1 can be suppressed. After charging the battery 202, even when the electric vehicle starts running (even when the drive motor 103, inverter 102, etc. are driven), cooling of the first refrigerant circuit 1 is not immediately necessary, thereby reducing power consumption. Additionally, by placing the first flow path changing means (third valve 206) at the connection point between the second refrigerant circuit 2 and the second branch circuit 5, it becomes possible to switch between the first and second states with a simple configuration.

[0094] In this embodiment, when the temperature (Tb) of the battery 202 is below a predetermined temperature (Tbpd), the first flow path changing means (third valve 206) is set to the second state and the second pump 201 is started. When the temperature of the battery 202 exceeds the predetermined temperature (Tbpd), the first flow path changing means (third valve 206) is set to the first state (selecting the first operating state).

[0095] With the above method, the cooling equipment (compressor 31) for the battery 202 will not start unless the temperature (Tb) of the battery 202 exceeds a predetermined temperature (Tbpd). If the temperature exceeds the predetermined temperature (Tbpd), the system switches to the first operating state. This reduces the supply of heat to the battery 202 via the refrigerant, and allows the cooling equipment (compressor 31) for the battery 202 to stop earlier, thereby reducing power consumption.

[0096] In this embodiment, when the second pump 201 is stopped when normal charging is performed, the charging duration of normal charging (t) is calculated from the difference between the charge rate of the battery 202 when the battery 202 is fully charged and the charge rate of the battery 202 at the start of normal charging. ｃｈｇ ) calculate the charging duration (t ｃｈｇ ) for a predetermined time (t ｐｄ) If the above conditions are met, the first flow path changing means (third valve 206) is set to the second state and the second pump 201 is started (selecting the second operating state), and the charging duration (t ｃｈｇ ) for a predetermined time (t ｐｄ If the length is shorter than the specified length, the first flow path changing means (third valve 206) is set to the first state (selects the first operating state).

[0097] According to the above method, when the temperature of the refrigerant in the first refrigerant circuit 1 and the temperature of the battery 202 are approximately constant at the start of normal charging, the total power consumption (W1) consumed when the first operating state is continued and the total power consumption (W2) consumed when the second operating state is continued are equal for a predetermined time (t ｐｄ ) can be kept constant. In this case, the charging duration (t ｃｈｇ ) calculate the charging duration (t ｃｈｇ ) and a predetermined time (t ｐｄ By comparing the relative magnitudes of the two operating states, power consumption can be reduced by selecting the one with the lower total power consumption (either the first operating state (total power consumption (W1)) or the second operating state (total power consumption (W2)) and performing normal charging.

[0098] In this embodiment, when the second pump 201 is stopped when normal charging is performed, the charging duration of normal charging (t) is calculated from the difference between the charge rate of the battery 202 when the battery 202 is fully charged and the charge rate of the battery 202 at the start of normal charging. ｃｈｇ The charging duration (t) is calculated, and the first pump 101 and the second pump 201 are started and the first flow path changing means (third valve 206) is set to the second state. ｃｈｇ The first total power consumption (W2) consumed by the first pump 101 and the second pump 201 during ) and the charging duration (t) when the first pump 101 is started but the second pump 201 is not started and the first flow path changing means (third valve 206) is set to the first state. ｃｈｇThe system predicts the second total power consumption (W1) consumed by the first pump 101 and the second total power consumption (W2). If the first total power consumption (W2) is lower than the second total power consumption (W1), the first flow path changing means (third valve 206) is set to the second state and the second pump 201 is started (the second operating state is selected). If the first total power consumption (W2) is equal to or greater than the second total power consumption (W1), the first flow path changing means (third valve 206) is set to the first state (the first operating state is selected).

[0099] By using the method described above, power consumption can be reduced by selecting the first operating state (total power consumption (W1)) or the second operating state (total power consumption (W2)) with the lower total power consumption and performing normal charging.

[0100] In this embodiment, a chiller 207 is located in the second refrigerant circuit 2. When normal charging is performed, if the chiller 207 is not absorbing heat from the refrigerant flowing through the second refrigerant circuit 2, the setting of the first flow path changing means (third valve 206) to the second state (selection of the second operating state) is permitted. When normal charging is performed, if the chiller 207 is absorbing heat from the refrigerant flowing through the second refrigerant circuit 2, the setting of the first flow path changing means (third valve 206) to the second state (selection of the second operating state) is prohibited.

[0101] By the method described above, when the chiller 207 is performing an endothermic operation, the chiller 207 can efficiently cool the chiller 207 that flows through the first chiller circuit 1 during normal charging.

[0102] In this embodiment, a radiator 109 is positioned downstream of the charger 105 of the first refrigerant circuit 1; a third branch circuit 6 branches off from a position upstream of the radiator 109 of the first refrigerant circuit 1 and downstream of the charger 105, and merges with the second refrigerant circuit 2; a second flow path changing means (first valve 107) is positioned at the connection point between the first refrigerant circuit 1 and the third branch circuit 6, and is mutually switchable between a third state in which the charger 105 side of the first refrigerant circuit 1 and the radiator 109 side of the first refrigerant circuit 1 are connected and the charger 105 side of the first refrigerant circuit 1 is blocked from the third branch circuit 6; and a fourth state in which the charger 105 side of the first refrigerant circuit 1 and the radiator 109 side of the first refrigerant circuit 1 are blocked and the charger 105 side of the first refrigerant circuit 1 is connected to the third branch circuit 6; and a third flow path changing means (first valve 107) is positioned downstream of the charger 105 side of the first refrigerant circuit 1 and the radiator 109 side of the first refrigerant circuit 1 is blocked and the charger 105 side of the first refrigerant circuit 1 is connected to the third branch circuit 6; and a third refrigerant circuit changing means (first valve 107) is positioned downstream of the charger 105 side of the first refrigerant circuit 1 and the third branch circuit 6. The system includes a medium circuit 3, a chiller 207 located in the second refrigerant circuit 2 and the third refrigerant circuit 3 which performs heat exchange between the heating refrigerant and the refrigerant circulating in the second refrigerant circuit 2, a condenser 32 located in the third refrigerant circuit 3 which releases the heat of the heating refrigerant to the outside as heating heat, and a compressor 31 located in the third refrigerant circuit 3 which pressurizes the heating refrigerant to the condenser 32. When normal charging is performed, the compressor 31 is stopped and the second flow path changing means (first valve 107) is set to the third state, allowing the first flow path changing means (third valve 206) to be set to the second state (selection of the second operating state). When normal charging is performed, the compressor 31 is started and the second flow path changing means (first valve 107) is set to the fourth state, prohibiting the first flow path changing means (third valve 206) to be set to the second state (selection of the second operating state).

[0103] By the above method, if thermal recovery (third operating state), which supplies heat from the drive system (drive motor 103, inverter 102, DC / DC converter 104) and the battery 202 to the capacitor 32 when performing normal charging, the power consumption when restarting operation of the electric vehicle can be reduced by efficiently cooling the refrigerant flowing through the first refrigerant circuit 1 with the chiller 207.

[0104] The thermal management system for the electric vehicle of this embodiment includes: a first refrigerant circuit 1 including a drive motor 103 and a first pump 101 that circulates a refrigerant to cool the drive motor 103; a second refrigerant circuit 2 including a series circuit 21 that includes a battery 202 capable of supplying power to the drive motor 103 and a second pump 201 that circulates a refrigerant to cool the battery 202; two branch circuits (first branch circuit 4, second branch circuit 5) that branch off from positions at both ends of the series circuit 21 of the second refrigerant circuit 2 and rejoin the first refrigerant circuit 1, respectively; and a first state in which the refrigerant flowing through the series circuit 21 circulates through the second refrigerant circuit 2 (series circuit 21, return circuit 22) without passing through the branch circuits (first branch circuit 4, second branch circuit 5) or the first refrigerant circuit 1. A thermal management system for an electric vehicle, comprising: a first flow path changing means (third valve 206) that can be switched between a second state in which the refrigerant flowing through the series circuit 21 flows back into the series circuit 21 via branch circuits (first branch circuit 4, second branch circuit 5) and the first refrigerant circuit 1; a charger 105 arranged in the first refrigerant circuit 1 to perform normal charging of the battery 202; and a control unit 7 that starts the first pump 101 when performing normal charging, wherein the control unit 7 sets the first flow path changing means (third valve 206) to the second state and starts the second pump 201 (selects the second operating state) when the temperature (Tb) of the battery 202 is lower than the temperature (Tc) of the refrigerant circulating in the first refrigerant circuit 1 by a predetermined temperature (threshold (Tch)).

[0105] With the above configuration, by selecting the second operating state, the heat generated in the charger 105 can be diffused to the refrigerant flowing through the first refrigerant circuit 1, the branch circuits (first branch circuit 4, second branch circuit 5), and the second refrigerant circuit 2 (series circuit 21). As a result, the heat capacity of the refrigerant is greater than when the refrigerant is circulated within the first refrigerant circuit 1 (selecting the first operating state). In addition, during normal power generation, the current input to the battery 202 is small, and therefore the amount of heat generated by the battery 202 is also suppressed. Consequently, the temperature rise of the refrigerant flowing through the first refrigerant circuit 1 can be suppressed, and even after the electric vehicle starts running after the battery 202 has been charged (even when the drive motor 103, inverter 102, etc. are driven), cooling of the first refrigerant circuit 1 is not immediately necessary, and power consumption can be reduced accordingly.

[0106] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Claims

1. A thermal management method for an electric vehicle, comprising: a first refrigerant circuit including a drive system for driving an electric vehicle and a first pump for circulating a refrigerant for cooling the drive system; a second refrigerant circuit including a series circuit including a battery for supplying power to the drive system and a second pump for circulating a refrigerant for cooling the battery; two branch circuits branching off from positions at both ends of the series circuit of the second refrigerant circuit and joining the first refrigerant circuit, respectively; a first flow path changing means that can switch between a first state in which the refrigerant flowing through the series circuit circulates through the second refrigerant circuit without passing through the branch circuits or the first refrigerant circuit, and a second state in which the refrigerant flowing through the series circuit returns to the series circuit via the branch circuits and the first refrigerant circuit; wherein a charger for normal charging the battery is located in the first refrigerant circuit, and the first pump is started when normal charging is performed. A thermal management method for an electric vehicle, wherein the first flow path changing means is set to the second state and the second pump is started when the temperature of the battery is lower than or equal to a predetermined temperature than the temperature of the refrigerant circulating in the first refrigerant circuit.

2. A drive system for driving an electric vehicle; a first refrigerant circuit including a first pump for circulating a refrigerant to cool the drive system; a second refrigerant circuit including a series circuit including a battery for supplying power to the drive system and a second pump for circulating a refrigerant to cool the battery, and a feedback circuit connecting both ends of the series circuit; a first branch circuit branching off from the first refrigerant circuit and joining the upstream side of the series circuit; a second branch circuit branching off from the downstream side of the series circuit in the second refrigerant circuit and joining the first refrigerant circuit at a position different from the connection position between the first refrigerant circuit and the first branch circuit; and a first flow path changing means positioned at the connection position between the second refrigerant circuit and the second branch circuit, which can switch between a first state in which the series circuit is connected to the feedback circuit and the series circuit is disconnected from the second branch circuit, and a second state in which the series circuit is disconnected from the feedback circuit and the series circuit is connected to the second branch circuit. A thermal management method for an electric vehicle, wherein a charger for normal charging of the battery is placed in the first refrigerant circuit, and the first pump is started when the normal charging is performed, wherein the first flow path changing means is set to the second state and the second pump is started when the temperature of the battery is lower than or equal to a predetermined temperature than the temperature of the refrigerant circulating in the first refrigerant circuit.

3. A thermal management method for an electric vehicle according to claim 1 or 2, wherein the first flow path changing means is set to the second state and the second pump is started when the temperature of the battery is below a predetermined temperature, and the first flow path changing means is set to the first state when the temperature of the battery exceeds the predetermined temperature.

4. When the second pump is stopped while performing the normal charging, the charging duration of the normal charging is calculated from the difference between the battery's charge rate when the battery is fully charged and the battery's charge rate at the start of the normal charging; if the charging duration is equal to or greater than a predetermined time, the first flow path changing means is set to the second state and the second pump is started; and if the charging duration is shorter than the predetermined time, the first flow path changing means is set to the first state. This is the thermal management method for an electric vehicle according to claim 1 or 2.

5. When the second pump is stopped while performing the normal charging, the charging duration of the normal charging is calculated from the difference between the battery's charge rate when the battery is fully charged and the battery's charge rate at the start of the normal charging; the first total power consumption consumed by the first pump and the second pump during the charging duration with the first pump and the second pump started and the first flow path changing means set to the second state; and the second total power consumption consumed by the first pump during the charging duration with the first pump started but the second pump not started and the first flow path changing means set to the first state; the first total power consumption is set to the second state and the second pump is started if the first total power consumption is lower than the second total power consumption; and the first flow path changing means is set to the first state if the first total power consumption is equal to or greater than the second total power consumption.

6. A thermal management method for an electric vehicle according to claim 1 or 2, wherein a chiller is provided in the second refrigerant circuit, and when normal charging is performed, the first flow path changing means is allowed to be set to the second state when the chiller is not performing an operation to absorb heat from the refrigerant flowing through the second refrigerant circuit, and the first flow path changing means is prohibited from being set to the second state when normal charging is performed when the chiller is performing an operation to absorb heat from the refrigerant flowing through the second refrigerant circuit.

7. A radiator positioned downstream of the charger in the first refrigerant circuit; a third branch circuit branching off from a position upstream of the radiator in the first refrigerant circuit and downstream of the charger, and joining the second refrigerant circuit; a second flow path changing means positioned at the connection point between the first refrigerant circuit and the third branch circuit, which can switch between a third state in which the charger side of the first refrigerant circuit and the radiator side of the first refrigerant circuit are connected and the charger side of the first refrigerant circuit is blocked from the third branch circuit; and a fourth state in which the charger side of the first refrigerant circuit and the radiator side of the first refrigerant circuit are blocked and the charger side of the first refrigerant circuit is connected to the third branch circuit; a third refrigerant circuit for circulating heating refrigerant for heating the vehicle; and chillers positioned in the second and third refrigerant circuits for heat exchange between the heating refrigerant and the refrigerant circulating in the second refrigerant circuit. A thermal management method for an electric vehicle according to claim 1 or 2, comprising: a condenser disposed in the third refrigerant circuit for releasing the heat of the heating refrigerant to the outside as heating heat; and a compressor disposed in the third refrigerant circuit for pressurizing the heating refrigerant to the condenser, wherein when the compressor is stopped and the second flow path changing means is set to the third state during normal charging, the setting of the first flow path changing means to the second state is permitted; and when the compressor is started and the second flow path changing means is set to the fourth state during normal charging, the setting of the first flow path changing means to the second state is prohibited.

8. A thermal management system for an electric vehicle, comprising: a first refrigerant circuit including a drive system for driving an electric vehicle and a first pump for circulating a refrigerant for cooling the drive system; a second refrigerant circuit including a series circuit including a battery for supplying power to the drive system and a second pump for circulating a refrigerant for cooling the battery; two branch circuits branching off from positions at both ends of the series circuit of the second refrigerant circuit and joining the first refrigerant circuit, respectively; a first flow path changing means that can switch between a first state in which the refrigerant flowing through the series circuit circulates through the second refrigerant circuit without passing through the branch circuits or the first refrigerant circuit, and a second state in which the refrigerant flowing through the series circuit returns to the series circuit via the branch circuits and the first refrigerant circuit; a charger disposed in the first refrigerant circuit for normal charging the battery; and a control unit that starts the first pump when performing the normal charging, wherein the control unit is A thermal management system for an electric vehicle that sets the first flow path changing means to the second state and starts the second pump when the temperature of the battery is lower than or equal to a predetermined temperature than the temperature of the refrigerant circulating in the first refrigerant circuit.

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