Electric vehicle heat management method and electric vehicle heat management system

Abstract

The present invention includes: a first refrigerant circuit that circulates a refrigerant through a drive system and a radiator; a second refrigerant circuit that circulates a refrigerant through a battery and a chiller; and a branch circuit that communicates the first refrigerant circuit and the second refrigerant circuit and forms a circulation path through which the refrigerant discharged from the drive system bypasses the radiator, is supplied to the chiller, and is recirculated to the drive system. When the temperature of the refrigerant introduced to the drive system is lower than a first threshold temperature, a first mode is set in which the refrigerant discharged from the drive system does not circulate through the first refrigerant circuit and instead circulates through the circulation path. When the temperature of the refrigerant introduced to the drive system is greater than or equal to the first threshold temperature, a second mode is set in which the first refrigerant circuit and the second refrigerant circuit circulate the refrigerant independently of each other, and in such case, an intermediate mode is set in which the refrigerant circulating in the circulation path is gradually supplied to the radiator and recirculated to the circulation path when the temperature of the refrigerant introduced into the drive system rises to be greater than or equal to a second threshold temperature lower than the first threshold temperature.

Description

Method for Thermal Management of Electric Vehicle and Thermal Management System of Electric Vehicle

[0001] The present invention relates to a method for thermal management of an electric vehicle and a thermal management system of an electric vehicle.

[0002] JP6781744B discloses setting a first mode in which a refrigerant that has received waste heat from a drive system of an electric vehicle is circulated in a form that bypasses a radiator and is supplied to a chiller when the temperature of the drive system is lower than a predetermined temperature, and setting a second mode in which the refrigerant that has received waste heat from the drive system is circulated in a form that is supplied to the radiator when the temperature of the drive system reaches the predetermined temperature.

[0003] However, when switching from the first mode to the second mode as in JP6781744B, there is a possibility that a phenomenon (mode hunting) in which the temperature of the drive system fluctuates due to the refrigerant cooled by the radiator flowing into the drive system and the first mode and the second mode frequently switch may occur.

[0004] Therefore, an object of the present invention is to provide a method for thermal management of an electric vehicle and a thermal management system of an electric vehicle that reduce mode hunting when switching from the first mode to the second mode.

[0005] According to one aspect of the present invention, there is a thermal management method for an electric vehicle that includes: a first refrigerant circuit through which a refrigerant for cooling a drive system that drives an electric vehicle circulates; a radiator that performs heat exchange between the refrigerant circulating in the first refrigerant circuit and the outside air; a battery capable of supplying power to the drive system; a second refrigerant circuit through which a refrigerant for cooling the battery circulates; a chiller that performs heat exchange between the refrigerant circulating in the second refrigerant circuit and a refrigerant circulating for heating means; and a branch circuit that connects the first refrigerant circuit and the second refrigerant circuit, forming a circulation path through which the refrigerant discharged from the drive system bypasses the radiator and is supplied to the chiller and returned to the drive system. The method is set to a first mode in which, when the temperature of the refrigerant introduced into the drive system is lower than a first threshold temperature, the refrigerant discharged from the drive system does not circulate in the first refrigerant circuit but circulates in the circulation path; and a second mode in which, when the temperature of the refrigerant introduced into the drive system is equal to or greater than the first threshold temperature, the first refrigerant circuit and the second refrigerant circuit circulate the refrigerant independently of each other. In this method, when the temperature of the refrigerant introduced into the drive system rises to a second threshold temperature that is lower than the first threshold temperature, the system is set to an intermediate mode in which the refrigerant circulating in the circulation path is gradually supplied to the radiator and returned to the circulation path.

[0006] Figure 1 is a schematic diagram of the thermal management system of the electric vehicle according to this embodiment. Figure 2 is a diagram showing the relationship between the temperature of the refrigerant introduced into the drive system, the battery temperature, and the refrigerant circulation mode of the thermal management system. Figure 3 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to one of the first, second, or fourth modes in the thermal management system of the electric vehicle according to this embodiment. Figure 4 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the third mode in the thermal management system of the electric vehicle according to this embodiment. Figure 5 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the first intermediate mode in the thermal management system of the electric vehicle according to this embodiment. Figure 6 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the fifth mode in the thermal management system of the electric vehicle according to this embodiment. Figure 7 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the sixth or seventh mode in the thermal management system of the electric vehicle according to this embodiment. Figure 8 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the second intermediate mode in the thermal management system of the electric vehicle according to this embodiment. Figure 9 shows the circulation of the refrigerant when the refrigerant circulation mode is set to the eighth mode in the thermal management system of the electric vehicle of this embodiment. Figure 11 shows the control flow of the thermal management system of the electric vehicle of this embodiment. Figure 11 is a time chart of the refrigerant temperature when the refrigerant circulation mode is transitioned from the third mode to the fourth mode without going through the first intermediate mode in the thermal management system of the comparative example electric vehicle. Figure 12 is a time chart of the refrigerant temperature when the refrigerant circulation mode is transitioned from the third mode to the first intermediate mode in the thermal management system of the electric vehicle of this embodiment.

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

[0008] Figure 1 is a schematic diagram of a thermal management system for an electric vehicle according to the present embodiment. This thermal management system (TM) is mounted on, for example, an electric vehicle. Here, the electric vehicle includes not only a BEV (Battery Electric Vehicle) but also a HEV (Hybrid Electric Vehicle).

[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, a first temperature sensor 106, an inverter 102, a drive motor 103, a DC / DC converter 104, a charger 105, a first valve 107, a first connection portion 108, a radiator 109, a first reservoir tank 110, and a second connection portion 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 the refrigerant (water) circulating in the first refrigerant circuit 1 toward the inverter 102.

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

[0013] The drive motor 103 is driven by being supplied with a three-phase AC voltage from the inverter 102 to run the electric vehicle. When regenerative power is generated, the drive motor 103 charges the battery 202 via the inverter 102.

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

[0015] The charger 105 is connected to the outside (charging station), converts the AC voltage supplied from the outside into a DC voltage, and charges the battery 202 (normal charging).

[0016] Furthermore, the electric vehicle is 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. In this embodiment, the inverter 102, drive motor 103, DC / DC converter 104, charger 105, and rapid charger (not shown) can be treated as an integrated drive system (e-PT).

[0017] The first temperature sensor 106 detects the temperature of the refrigerant just before it is introduced into the inverter 102.

[0018] The first valve 107 is a three-way valve in which the refrigerant input side (IN) is connected to the charger 105, the first output side of the refrigerant (OUT1) is connected to the first connection part 108, and the second output side of the refrigerant (OUT2) is connected to the second branch circuit 5.

[0019] The first valve 107 can be controlled by the control unit 7 to adjust the ratio (%) of the flow rate (first flow rate) of refrigerant flowing from the input side (IN) to the first output side (OUT1) and the ratio (%) of the flow rate (second flow rate) of refrigerant flowing from the input side (IN) to the second output side (OUT2).

[0020] The first connection section 108 connects the first refrigerant circuit 1 and the third branch circuit 6 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 these components are arranged in the second refrigerant circuit 2 so that the refrigerant circulates in the order described above.

[0025] The second pump 201 supplies refrigerant (water) circulating in the second refrigerant circuit 2 to the battery 202.

[0026] The battery 202 is cooled (or heated) by a refrigerant so that its temperature is within an appropriate temperature range. The battery 202 can raise its temperature by generating heat on its own when supplying power to, for example, the inverter 102. A heater 210 (for example, a PTC heater) is also attached to the battery 202, and is activated by the control unit 7 to heat the battery 202 when it is difficult to heat the battery 202.

[0027] 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.

[0028] The second valve 204 is normally open, but closes when the third mode or the first intermediate mode is selected as the refrigerant circulation mode of the thermal management system, which will be described later.

[0029] The third connection section 205 connects the second refrigerant circuit 2 and the second branch circuit 5 to form a three-way intersection for the refrigerant.

[0030] The third valve 206 has its refrigerant input side (IN) connected to the third connection part 205, its first refrigerant output side (OUT1) connected to the chiller 207, and its second refrigerant output side (OUT2) connected to the third branch circuit 6.

[0031] The third valve 206 is a three-way valve that can be switched between two connection states, controlled by the control unit 7: one in which the input side (IN) and the first output side (OUT1) are connected and the input side (IN) and the second output side (OUT2) are disconnected, and another in which the input side (IN) and the first output side (OUT1) are disconnected and the input side (IN) and the second output side (OUT2) are connected.

[0032] 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.

[0033] The fourth connection section 208 connects the second refrigerant circuit 2 and the first branch circuit 4 to form a three-way intersection for the refrigerant.

[0034] The second reservoir tank 209 temporarily stores the refrigerant that has flowed through the fourth connection section 208, and when the second pump 201 is activated, it supplies the stored refrigerant to the second pump 201.

[0035] The third refrigerant circuit 3 includes a compressor 31, a condenser 32, an expansion valve 33, and a chiller 207, and these are arranged in the third refrigerant circuit 3 so that the refrigerant circulates in the order described above.

[0036] The compressor 31 compresses (heats) the refrigerant (for example, an alternative fluorocarbon such as HFC134a) circulating in the third refrigerant circuit 3 and supplies it to the condenser 32.

[0037] The condenser 32 is, for example, placed in a path that supplies heating air to the interior of a vehicle, and heats the air supplied from the outside by exchanging heat with a refrigerant. The heated air is then supplied to the interior of the vehicle.

[0038] The expansion valve 33 expands (cools) the refrigerant and supplies it to the chiller 207.

[0039] Although not shown in the diagram, a heat exchange circuit (not shown) is located in the third refrigerant circuit 3, which exchanges heat between the outside air and the refrigerant, and in particular takes in heat from the outside air and supplies it to the compressor 31.

[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 temperature of the refrigerant detected by the first temperature sensor 106 and information on the temperature of the battery 202 detected by the second temperature sensor 203.

[0042] The control unit 7 is equipped with a program for executing the thermal management system of this embodiment, and sets the refrigerant circulation mode (first to eighth modes, first intermediate mode, second intermediate mode) based on the temperature of the refrigerant introduced into the inverter 102 and the temperature of the battery 202 (see Figure 2).

[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] [Refrigerant Circulation Modes of the Thermal Management System] Figure 2 is a diagram showing the relationship between the temperature of the refrigerant introduced into the drive system (e-PT), the temperature of the battery 202, and the refrigerant circulation mode of the thermal management system. Figure 3 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to one of the first mode, second mode, or fourth mode in the thermal management system of the electric vehicle of this embodiment. Figure 4 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the third mode in the thermal management system of the electric vehicle of this embodiment. Figure 5 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the first intermediate mode in the thermal management system of the electric vehicle of this embodiment. Figure 6 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the fifth mode in the thermal management system of the electric vehicle of this embodiment. Figure 7 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the sixth mode or seventh mode in the thermal management system of the electric vehicle of this embodiment. Figure 8 is a diagram showing the circulation of the refrigerant when the refrigerant circulation mode is set to the second intermediate mode in the thermal management system of the electric vehicle of this embodiment. Figure 9 shows the circulation of the refrigerant when the refrigerant circulation mode is set to mode 8 in the thermal management system of the electric vehicle of this embodiment.

[0045] Figure 2 shows a coordinate space with the temperature of the refrigerant (Tc) introduced into the drive system (e-PT) (hereinafter referred to as "refrigerant temperature") and the temperature of the battery 202 (Tb) as axes, and a threshold set for the temperature of the refrigerant (Tc) and a threshold set for the temperature of the battery 202 (Tb) (first threshold temperature (Tc ｔｈ１ Multiple refrigerant circulation modes are set by dividing the system into sections.

[0046] In the vertical axis of Figure 2, the first refrigerant threshold temperature (Tc ｔｈ１ ) is the second refrigerant threshold temperature (Tc ｔｈ２ The temperature is set higher than (for example, 2°C).

[0047] In the horizontal axis of Figure 2, the first battery threshold temperature (Tb) ｔｈ１ ), second battery threshold temperature (Tb ｔｈ２ ), third battery threshold temperature (Tbｔｈ３ ), the fourth battery threshold temperature (Tb ｔｈ４ ) is at the temperature (Tb) of the battery 202 where Tb ｔｈ１ < Tb ｔｈ２ < Tb ｔｈ３ < Tb ｔｈ４ has the relationship of.

[0048] Also, the first battery threshold temperature (Tb ｔｈ１ ), the second battery threshold temperature (Tb ｔｈ２ ), the third battery threshold temperature (Tb ｔｈ３ ), and the fourth battery threshold temperature (Tb ｔｈ４ ) each have a hysteresis width (for example, 2 [°C]) set, such that the battery threshold temperature when transitioning from the refrigerant circulation mode on the low-temperature side to the refrigerant circulation mode on the high-temperature side is higher by the hysteresis width than the battery threshold temperature when transitioning from the refrigerant circulation mode on the high-temperature side to the refrigerant circulation mode on the low-temperature side.

[0049] As shown in FIG. 2, the first mode is a region where the temperature of the refrigerant (Tc) is lower than the first refrigerant threshold temperature (Tcth1) and the temperature of the battery 202 (Tb) is lower than the first battery threshold temperature (Tb ｔｈ１ ).

[0050] As an operating state of the first mode, the battery 202 is warmed up by the heater 210. The drive system (e-PT) is cooled by the radiator 109. The in-vehicle heating is performed by a heat pump (HP) using the third refrigerant circuit 3 or a heater that heats the air taken into the vehicle interior. The grill shutter 113 (GS) (and the fan 112) is set to "OPEN" or "CLOSE".

[0051] As shown in Figure 3, in the first mode of refrigerant circulation, the refrigerant in the first refrigerant circuit 1 circulates, and the circulation of the refrigerant in the second refrigerant circuit 2 is stopped (the second pump 201 is stopped). At this time, the flow rate of the first output side (OUT1) of the first valve 107 is set to 100%, and the flow rate of the second output side (OUT2) is set to 0%. When the grill shutter 113 (and fan 112) is "OPEN", it operates and supplies outside air to the radiator 109. When the grill shutter 113 (and fan 112) is "CLOSE", it does not operate, but the radiator 109 is still able to exchange heat between the surrounding air and the refrigerant. In addition, the refrigerant circulating in the first refrigerant circuit 1 is heated by the drive system (e-PT) while being cooled by the radiator 109.

[0052] As shown in Figure 2, the second mode is when the refrigerant temperature (Tc) is above the first refrigerant threshold temperature (Tcth1), and the temperature of the battery 202 is above the first battery threshold temperature (Tb ｔｈ１ This is a lower region than ).

[0053] The operating state of the second mode is the same as that of the first mode, but the grill shutter 113 (GS) (and fan 112) is set to "OPEN".

[0054] The refrigerant circulation state in the second mode is the same as that of the first mode shown in Figure 3.

[0055] Furthermore, when transitioning from the first mode to the second mode, the refrigerant temperature (Tc) reaches the first refrigerant threshold (Tc ｔｈ１ When the temperature of the refrigerant (Tc) exceeds the first refrigerant threshold (Tc), the system transitions from the first mode to the second mode. On the other hand, when transitioning from the second mode to the first mode, the temperature of the refrigerant (Tc) exceeds the first refrigerant threshold (Tc). ｔｈ１ ) is lower than the second refrigerant threshold temperature (Tc ｔｈ２ When the value falls below this level, it transitions from the second mode to the first mode.

[0056] As shown in Figure 2, the third mode is when the refrigerant temperature (Tc) is lower than the first refrigerant threshold temperature (Tcth1) and the temperature of the battery 202 is lower than the first battery threshold temperature (Tb ｔｈ１ ) or higher and the second battery threshold temperature (Tb ｔｈ２ This is a lower region than ).

[0057] In the third mode of operation, the heater 210 is stopped from warming the battery 202, but the battery 202 is warmed up by self-heating due to the power supply to the drive system (e-PT). The waste heat from the drive system (e-PT) is supplied to the chiller 207. Interior heating is performed by a heat pump (HP+H / R) using the third refrigerant circuit 3 (using the chiller 207 and a heat exchanger (not shown)). The grill shutter 113 (GS) (and fan 112) is set to "OPEN" or "CLOSE". The third mode is a thermal recovery mode in which the waste heat from the drive system (e-PT) is supplied to the chiller 207 and used for heating, thereby cooling the drive system (e-PT).

[0058] As shown in Figure 4, in the third mode of refrigerant circulation, the refrigerant discharged from the first pump 101 is introduced into the second branch circuit 5 via the drive system (e-PT) and the first valve 107, then into the second refrigerant circuit 2 at the third connection 205, then into the first branch circuit 4 via the third valve 206, chiller 207, and fourth connection 208, and finally into the first refrigerant circuit 1 at the second connection 111, forming a circulation path 8 that returns to the first pump 101. At this time, the flow rate on the first output side (OUT1) of the first valve 107 is set to 0%, and the flow rate on the second output side (OUT2) is set to 100%. The second pump 201 is stopped, and the second valve 204 is closed to prevent backflow.

[0059] In the third mode, the refrigerant discharged from the first pump 101 bypasses the radiator 109, so it is not necessary to operate the radiator 109 (grille shutter 113, fan 112). However, it may be operated in advance in anticipation of transitioning to the fourth mode, which will be described later.

[0060] As shown in Figure 2, the fourth mode is when the refrigerant temperature (Tc) is above the first refrigerant threshold temperature (Tcth1), and the temperature of the battery 202 is above the first battery threshold temperature (Tb ｔｈ１ ) or higher and the second battery threshold temperature (Tb ｔｈ２ This is a lower region than ).

[0061] In the fourth mode of operation, the battery 202 is warmed up by self-heating as described above. The drive system (e-PT) is cooled by the radiator 109. Interior heating is performed by a heat pump (HP) using the third refrigerant circuit 3 or by a heater that heats the air taken into the cabin. The grill shutter 113 (GS) (and fan 112) is set to "OPEN". The fourth mode is a refrigerant circulation mode in which the drive system (e-PT) is cooled by releasing the exhaust heat from the drive system (e-PT) through the radiator 109.

[0062] The refrigerant circulation state in the fourth mode is the same as that of the first and second modes shown in Figure 2.

[0063] As shown in Figure 2, the first intermediate mode is the region between the third and fourth modes, and the refrigerant temperature (Tc) is the first refrigerant threshold temperature (Tc ｔｈ１ ) is lower than the second refrigerant threshold temperature (Tc ｔｈ２ ) or higher, and the temperature of the battery 202 is above the first battery threshold temperature (Tb ｔｈ１ ) or higher and the second battery threshold temperature (Tb ｔｈ２ This is a lower region than ).

[0064] The operating state of the first intermediate mode is the same as that of the third mode.

[0065] As shown in Figure 5, the refrigerant circulation state in the first intermediate mode is similar to the refrigerant circulation state in the third mode shown in Figure 4, but the first valve 107 is set so that the flow rate on the first output side (OUT1) is set to x [%] and the flow rate on the second output side (OUT2) is set to (100 - x) [%]. Here, "x" is set to a value from 1 to 50 [%] depending on the vehicle model.

[0066] As shown in Figure 5, in the first intermediate mode, the first valve 107 supplies refrigerant at a flow rate of x [%] to the radiator 109, and the refrigerant discharged from the radiator 109 merges with the refrigerant introduced from the first branch circuit 4 at the second connection part 111 and is returned to the first pump 101.

[0067] Furthermore, when transitioning from the fourth mode to the third mode, the refrigerant temperature (Tc) reaches the second refrigerant threshold temperature (Tc) without passing through the first intermediate mode.ｔｈ２ When the temperature of the refrigerant (Tc) falls below the second refrigerant temperature (Tc), the system transitions from the fourth mode to the third mode. On the other hand, when the third mode is set, the refrigerant temperature (Tc) falls below the second refrigerant temperature (Tc). ｔｈ２ When the temperature exceeds 100°C, the system transitions to the first intermediate mode, but the first intermediate mode is executed for only a predetermined time (for example, 2 minutes). After the execution of the first intermediate mode, when the refrigerant temperature (Tc) reaches the first threshold temperature (Tc ｔｈ１ If the temperature of the refrigerant (Tc) is above the first threshold temperature (Tc), the system transitions to the fourth mode, and the refrigerant temperature (Tc) is above the first threshold temperature (Tc ｔｈ１ The system transitions to the third mode if the value is lower than ).

[0068] As shown in Figure 2, in the fifth mode, the refrigerant temperature (Tc) is lower than the first refrigerant threshold temperature (Tcth1), and the temperature of the battery 202 is lower than the second battery threshold temperature (Tb ｔｈ２ ) or higher and the third battery threshold temperature (Tb ｔｈ３ This is a lower region than ).

[0069] In the fifth mode of operation, the waste heat from the battery 202 and the waste heat from the drive system (e-PT) are supplied to the chiller 207. Interior heating is performed by a heat pump (HP + H / R) using the third refrigerant circuit 3 (using the chiller 207 and a heat exchange circuit (not shown)). The grill shutter 113 (GS) (and fan 112) are set to "OPEN" or "CLOSE". The fifth mode is a thermal recovery mode in which the waste heat from the drive system (e-PT) (and the waste heat from the battery 202) is supplied to the chiller 207 and used for heating, thereby cooling the drive system (e-PT) (and battery 202).

[0070] As shown in Figure 6, in the fifth mode of refrigerant circulation, the refrigerant discharged from the first pump 101 is introduced into the second branch circuit 5 via the drive system (e-PT) and the first valve 107, then into the second refrigerant circuit 2 at the third connection 205, then into the first branch circuit 4 via the third valve 206, chiller 207, and fourth connection 208, and finally into the first refrigerant circuit 1 at the second connection 111, forming a circulation path 8 that returns to the first pump 101. At this time, the flow rate on the first output side (OUT1) of the first valve 107 is set to 0 [%], and the flow rate on the second output side (OUT2) is set to 100 [%].

[0071] Furthermore, the second pump 201 is activated and the second valve 204 is opened, so the refrigerant circulates through the second refrigerant circuit 2. Therefore, in the region of the second refrigerant circuit 2 from the third valve 206 through the chiller 207 to the fourth connection part 208, refrigerant that has received exhaust heat from the drive system (e-PT) and refrigerant that has received exhaust heat from the battery 202 flows, and the chiller 207 takes in exhaust heat from the refrigerant.

[0072] Even in the fifth mode, the refrigerant discharged from the first pump 101 bypasses the radiator 109, so it is not necessary to operate the radiator 109 (grille shutter 113, fan 112). However, it may be operated in advance in anticipation of transitioning to the sixth mode, which will be described later.

[0073] As shown in Figure 2, the sixth mode is when the refrigerant temperature (Tc) is above the first refrigerant threshold temperature (Tcth1) and the temperature of the battery 202 is above the second battery threshold temperature (Tb ｔｈ２ ) or higher and the fourth battery threshold temperature (Tb ｔｈ４ This is a lower region than ).

[0074] In the sixth mode of operation, the waste heat from the battery 202 is supplied to the chiller 207. The drive system (e-PT) is cooled by the radiator 109. Interior heating is performed by a heat pump (HP + H / R) using the third refrigerant circuit 3 (using the chiller 207 and a heat exchanger (not shown)). The grill shutter 113 (GS) (and fan 112) are set to "OPEN". The sixth mode is a refrigerant circulation mode in which the drive system (e-PT) is cooled by releasing the waste heat from the drive system (e-PT) through the radiator 109.

[0075] As shown in Figure 7, in the sixth mode of refrigerant circulation, the first refrigerant circuit 1 and the second refrigerant circuit 2 circulate refrigerant independently of each other, and the refrigerant circulating in the first refrigerant circuit 1 and the refrigerant circulating in the second refrigerant circuit 2 do not mix with each other. In this state, the second pump 201 is operating and the second valve 204 is also open.

[0076] As shown in Figure 2, the second intermediate mode is the region between the fifth and sixth modes, and the refrigerant temperature (Tc) is equal to the first refrigerant threshold temperature (Tcｔｈ１ ) is lower than the second refrigerant threshold temperature (Tc ｔｈ２ ) or higher, and the temperature of the battery 202 is above the second battery threshold temperature (Tb ｔｈ２ ) or higher and the third battery threshold temperature (Tb ｔｈ３ This is a lower region than ).

[0077] The operating state of the second intermediate mode is the same as that of the fifth mode.

[0078] As shown in Figure 8, the refrigerant circulation state in the second intermediate mode is similar to the refrigerant circulation state in the fifth mode shown in Figure 6, but the flow rate of the first output side (OUT1) of the first valve 107 is set to x [%] as described above, and the flow rate of the second output side (OUT2) is set to (100 - x) [%].

[0079] As shown in Figure 8, in the second intermediate mode, the first valve 107 supplies refrigerant at a flow rate of x [%] to the radiator 109, and the refrigerant discharged from the radiator 109 merges with the refrigerant introduced from the first branch circuit 4 at the second connection part 111 and is returned to the first pump 101.

[0080] Furthermore, when transitioning from the sixth mode to the fifth mode, the refrigerant temperature (Tc) reaches the second refrigerant threshold temperature (Tc) without passing through the second intermediate mode. ｔｈ２ When the temperature drops below ), the system transitions from mode 6 to mode 5. On the other hand, when mode 5 is set, the refrigerant temperature (Tc) drops below the second refrigerant temperature (Tc ｔｈ２ When the temperature exceeds the first threshold temperature (Tc), the system transitions to the second intermediate mode, but the second intermediate mode is executed for only a predetermined time (for example, 2 minutes), just like the first intermediate mode. After the execution of the second intermediate mode, when the refrigerant temperature (Tc) exceeds the first threshold temperature (Tc ｔｈ１ If the temperature of the refrigerant (Tc) is above the first threshold temperature (Tc ｔｈ１ The system transitions to the fifth mode if the value is lower than ).

[0081] As shown in Figure 2, in the seventh mode, the refrigerant temperature (Tc) is lower than the first refrigerant threshold temperature (Tcth1), and the temperature of the battery 202 is lower than the third battery threshold temperature (Tb ｔｈ３ ) or higher and the fourth battery threshold temperature (Tb ｔｈ４ This is a lower region than ).

[0082] In the seventh mode of operation, the waste heat from the battery 202 is supplied to the chiller 207. The drive system (e-PT) is cooled by the radiator 109. Interior heating is performed by a heat pump (HP + H / R) using the third refrigerant circuit 3 (using the chiller 207 and a heat exchange circuit (not shown)). The grill shutter 113 (GS) (and fan 112) is set to "OPEN" or "CLOSE".

[0083] As shown in Figure 7, the refrigerant circulation state in the seventh mode is the same as that in the sixth mode.

[0084] As shown in Figure 2, the eighth mode is when the temperature of the battery 202 reaches the fourth battery threshold temperature (Tb) regardless of the refrigerant temperature (Tc). ｔｈ４ This is the region that exceeds the limit.

[0085] In the eighth mode of operation, the battery 202 and the drive system (e-PT) are cooled by the radiator 109. Interior heating is performed by a heat pump (HP) using a third refrigerant circuit 3 (using a heat exchange circuit (not shown)). The grill shutter 113 (GS) (and fan 112) are set to "OPEN".

[0086] As shown in Figure 9, in the eighth mode of refrigerant circulation, there are two states that coexist: one in which the refrigerant discharged from the first pump 101 circulates in the first refrigerant circuit 1, and another in which the refrigerant discharged from the second pump 201 in the second refrigerant circuit 2 is introduced into the third branch circuit 6 via the battery 202, second valve 204, and third valve 206, the refrigerant flowing into the third branch circuit 6 merges with the first refrigerant circuit 1 at the first connection 108, passes through the radiator 109, is introduced into the first branch circuit 4 at the second connection 111, merges with the second refrigerant circuit 2 at the fourth connection 208, and returns to the second pump 201, forming a circulation path 9.

[0087] Therefore, both the refrigerant discharged from the drive path (e-PT) and the refrigerant discharged from the battery 202 are cooled in the radiator 109.

[0088] [Control Flow] Figure 11 shows the control flow of the thermal management system of the electric vehicle according to this embodiment. Here, we will explain the case where the system transitions to the third mode or the fourth mode via the third mode or the first intermediate mode. The same applies when the system transitions from the fifth mode to the fifth mode or the sixth mode via the second intermediate mode.

[0089] As an initial state, the refrigerant temperature (Tc) is at the second refrigerant threshold temperature (Tc ｔｈ２ The temperature of battery 202 (Tb) is lower than the first battery threshold temperature (Tb ｔｈ１ The temperature shall be above ) and below the second battery threshold temperature. Furthermore, it shall be assumed that the electric vehicle is running and power is being supplied from the battery 202 to the drive system (e-PT).

[0090] In step S101, the control unit 7 selects the third mode as the refrigerant circulation mode.

[0091] In step S102, the control unit 7 determines that the refrigerant temperature (Tc) is equal to the second refrigerant threshold temperature (Tc ｔｈ２ Determine whether the value is greater than or equal to ) and proceed to step S103 if YES, or to step S101 if NO.

[0092] In step S103, the control unit 7 selects the first intermediate mode as the refrigerant circulation mode.

[0093] In step S104, the control unit 7 determines whether a predetermined time (for example, 2 minutes) has elapsed since setting the first intermediate mode. If the answer is YES, it proceeds to step S105; otherwise, it proceeds to step S103.

[0094] In step S105, the control unit 7 determines that the temperature of the refrigerant is the first refrigerant threshold temperature (Tc ｔｈ１ Determine whether the value is greater than or equal to ) and proceed to step S106 if YES, or to step S101 if NO.

[0095] In step S106, the control unit 7 selects the fourth mode as the refrigerant circulation mode.

[0096] [Time Chart] Figure 11 is a time chart of the refrigerant temperature when the refrigerant circulation mode is transitioned from the third mode to the fourth mode without passing through the first intermediate mode in the thermal management system of the comparative example electric vehicle. Figure 12 is a time chart of the refrigerant temperature when the refrigerant circulation mode is transitioned from the third mode to the first intermediate mode in the thermal management system of the electric vehicle of this embodiment.

[0097] In the comparative example and this embodiment, the third mode is selected as the refrigerant circulation mode in the initial state.

[0098] In the comparative example shown in Figure 11, at time t1 the refrigerant temperature (Tc) is the first refrigerant threshold temperature (Tc ｔｈ１ When it reaches the second refrigerant threshold temperature (Tc), the refrigerant circulation mode switches from the third mode to the fourth mode. Then, the refrigerant heated by circulating through the circulation path 8 enters the radiator 109, and the refrigerant that has already been cooled in the radiator 109 is pushed out of the radiator 109 and flows into the drive system (e-PT) (first temperature sensor 106). As a result, the refrigerant temperature (Tc) (minimum value) reaches the second refrigerant threshold temperature (Tc ｔｈ２ ) a temperature lower than (second refrigerant threshold temperature (Tc ｔｈ２ The temperature becomes 20°C lower than the previous mode, causing mode hunting, in which the refrigerant circulation mode immediately returns to the third mode.

[0099] Subsequently, at time t2, the refrigerant temperature (Tc) reaches the first refrigerant threshold temperature (Tc ｔｈ１ When it reaches ), the refrigerant circulation mode switches again from the third mode to the fourth mode, and mode hunting occurs as described above. However, in the fourth mode at time t1, the refrigerant heated in the circulation path 8 enters the radiator 109 to some extent, and the refrigerant that has been warmed to some extent flows into the drive system (e-PT) (first temperature sensor 106), so the refrigerant temperature (minimum value) becomes higher than the first refrigerant temperature (Tc) (minimum value).

[0100] Subsequently, at times t3, t4, and t5, mode hunting occurs in which the refrigerant circulation mode rapidly switches from the third mode to the fourth mode and then back to the third mode. However, for the reasons mentioned above, the refrigerant temperature (Tc) (minimum value) increases each time mode hunting is repeated.

[0101] At time t6, the refrigerant temperature reaches the first refrigerant threshold temperature (Tc ｔｈ１ When the refrigerant temperature (Tc) (minimum value) reaches the second refrigerant threshold temperature (Tc ｔｈ２ Since the temperature will be higher than ), the fourth mode will be maintained from time t6 onwards.

[0102] Subsequently, for example, at time t7, the refrigerant temperature reaches the second refrigerant threshold temperature (Tc ｔｈ２ When the temperature drops below this level, the refrigerant circulation mode switches from mode 4 to mode 3.

[0103] In this embodiment shown in Figure 12, at time t1 the refrigerant temperature (Tc) is the second refrigerant threshold temperature (Tc ｔｈ２ When it reaches this point, the refrigerant circulation mode switches from the third mode to the first intermediate mode.

[0104] As a result, the refrigerant heated by circulating through the circulation path 8 gradually enters the radiator 109, and the refrigerant already cooled in the radiator 109 is gradually pushed out and flows into the drive system (e-PT) (first temperature sensor 106).

[0105] Therefore, the flow rate of cooled refrigerant from the radiator 109 flowing into the drive system (e-PT) is suppressed, which in turn suppresses rapid temperature fluctuations of the refrigerant circulating through the drive system (e-PT) (first temperature sensor 106).

[0106] Furthermore, the refrigerant temperature (Tc) is the second refrigerant threshold temperature (Tc ｔｈ２ Although the value will be lower than ), mode switching is prohibited for a predetermined time (ΔT) after setting the first intermediate mode, and the first intermediate mode is maintained.

[0107] At time (t1 + ΔT), the first intermediate mode is deactivated. At this time, the refrigerant temperature (Tc) is equal to the first refrigerant threshold temperature (Tc ｔｈ１If the refrigerant temperature (Tc) is above the first refrigerant threshold temperature (Tc ｔｈ１ If the value is lower than ), the third mode is selected as the refrigerant circulation mode.

[0108] In Figure 12, "A" indicates that the heat generated by the drive system (e-PT) is low, and the refrigerant temperature (Tc) after a predetermined time (ΔT) has elapsed since setting the first intermediate mode is the first refrigerant threshold temperature (Tc ｔｈ１ This indicates a case where the temperature is lower than the first refrigerant threshold temperature (Tc). Also, "B" indicates that the heat generated by the drive system (e-PT) is large, and the refrigerant temperature (Tc) after a predetermined time (ΔT) has elapsed since setting the first intermediate mode is lower than the first refrigerant threshold temperature (Tc). ｔｈ１ This indicates cases where the result is greater than or equal to ).

[0109] [Effects of this embodiment] The thermal management method for the electric vehicle of this embodiment includes a first refrigerant circuit 1 through which a refrigerant that cools the drive system (e-PT) that drives the electric vehicle circulates, a radiator 109 that performs heat exchange between the refrigerant circulating in the first refrigerant circuit 1 and the outside air, a battery 202 capable of supplying power to the drive system (e-PT), a second refrigerant circuit 2 through which a refrigerant that cools the battery 202 circulates, a chiller 207 that performs heat exchange between the refrigerant circulating in the second refrigerant circuit 2 and the refrigerant circulating in the heating means (condenser 32), and branch circuits (first branch circuit 4, second branch circuit 5) that connect the first refrigerant circuit 1 and the second refrigerant circuit 2 and form a circulation path 8 through which the refrigerant discharged from the drive system (e-PT) bypasses the radiator 109 and is supplied to the chiller 207 and returned to the drive system (e-PT), wherein the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) is set to a first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ When the temperature (Tc) of the refrigerant discharged from the drive system (e-PT) is lower than the first threshold temperature (Tc), the system is set to a first mode (third mode, fifth mode) in which the refrigerant discharged from the drive system (e-PT) does not circulate through the first refrigerant circuit 1 but circulates through the circulation path 8, and the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) is lower than the first threshold temperature (Tc ｔｈ１A thermal management method for an electric vehicle, wherein when the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) rises to a first threshold temperature (first refrigerant threshold temperature (Tc) ｔｈ１ A second threshold temperature (second refrigerant threshold temperature (Tc)) lower than the second threshold temperature (Tc) ｔｈ２ When the temperature exceeds a certain level, the system is set to an intermediate mode (first intermediate mode, second intermediate mode) in which the refrigerant circulating in the circulation path 8 is gradually supplied to the radiator 109 and returned to the circulation path 8.

[0110] The above method suppresses rapid temperature fluctuations in the refrigerants that occur when refrigerants with different temperatures are mixed, thereby reducing mode hunting between the first mode (third mode, fifth mode) and the second mode (fourth mode, sixth mode).

[0111] The thermal management method for the electric vehicle of this embodiment includes a first refrigerant circuit 1 that circulates a refrigerant to cool the drive system (e-PT) that drives the electric vehicle, a radiator 109 that performs heat exchange between the refrigerant circulating in the first refrigerant circuit 1 and the outside air, a second refrigerant circuit 2 that circulates a refrigerant to cool a battery 202 that can supply power to the drive system (e-PT), a chiller 207 that performs heat exchange between the refrigerant circulating in the second refrigerant circuit 2 and the refrigerant circulating in the heating means (condenser 32), a first branch circuit 4 that branches off from a position between the refrigerant introduction side of the drive system (e-PT) of the first refrigerant circuit 1 and the refrigerant discharge side of the radiator 109 and merges with the second refrigerant circuit 2 at a position that is the refrigerant discharge side of the chiller 207 of the second refrigerant circuit 2, and the first refrigerant The system includes a second branch circuit 5 that branches off from a position between the refrigerant output side of the drive system (e-PT) of the medium circuit 1 and the refrigerant inlet side of the radiator 109, and merges with the second refrigerant circuit 2 at a position that is the refrigerant inlet side of the chiller 207 of the second refrigerant circuit 2, and a refrigerant distribution means (first valve 107) positioned at the connection point between the first refrigerant circuit 1 and the second branch circuit 5, which distributes the refrigerant flowing in from the refrigerant discharge side of the drive system (e-PT) to the second branch circuit 5 and the refrigerant inlet side of the radiator 109, and which can change the distribution ratio of the first flow rate of refrigerant flowing through the second branch circuit 5 and the second flow rate of refrigerant flowing through the refrigerant inlet side of the radiator 109, wherein the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) is set to a first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ The system is set to the first mode (third mode, fifth mode) in which the second flow rate becomes zero when the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) is lower than the first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ A thermal management method for an electric vehicle, wherein the system is set to a second mode (fourth mode, sixth mode) in which the first flow rate becomes zero when the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) rises to a first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ A second threshold temperature (second refrigerant threshold temperature (Tc)) lower than the second threshold temperature (Tc) ｔｈ２ If the value exceeds this, the distribution ratio is set to an intermediate mode (first intermediate mode, second intermediate mode) where the first and second flow rates are not zero.

[0112] The above method suppresses rapid temperature fluctuations in the refrigerants that occur when refrigerants with different temperatures are mixed, and reduces mode hunting between the first mode (third mode, fifth mode) and the second mode (fourth mode, sixth mode) with a simple configuration.

[0113] In this embodiment, the temperature of the refrigerant (Tc) is the first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ )) From temperatures above the second threshold temperature (second refrigerant threshold temperature (Tc ｔｈ２ When the temperature drops below )), it switches from the second mode (fourth mode, sixth mode) to the first mode (fourth mode, sixth mode).

[0114] The above method makes it possible to prevent chattering between the first mode (third mode, fifth mode) and the second mode (fourth mode, sixth mode) after passing through the intermediate modes (first intermediate mode, second intermediate mode).

[0115] In this embodiment, intermediate modes (first intermediate mode, second intermediate mode) are executed for a predetermined time (ΔT), and the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) after the execution of the predetermined time (ΔT) is set to the first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ When the temperature of the refrigerant (Tc) introduced into the drive system (e-PT) after the predetermined time (ΔT) is lower than the first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ )) When the above conditions are met, set to the second mode (fourth mode, sixth mode).

[0116] By using the above method, the temperature fluctuations of the refrigerant can be stabilized while the intermediate mode (first intermediate mode, second intermediate mode) is in operation, so that the selection of the refrigerant circulation mode after the intermediate mode (first intermediate mode, second intermediate mode) ends can be performed stably. In addition, while the system is set to an intermediate mode (first intermediate mode, second intermediate mode), the circulation path 8 in the first mode (third mode, fifth mode) is maintained, and thermal recovery can be continued by supplying the waste heat from the drive system (e-PT) to the chiller 207 to be used as the output of the heating means (condenser 32). For example, power consumption can be reduced compared to directly transitioning from the first mode (third mode, fifth mode) to the second mode (fourth mode, sixth mode) and directly heating the air used for heating in the second mode (fourth mode, sixth mode) with a heater or the like.

[0117] The thermal management system for the electric vehicle of this embodiment includes a first refrigerant circuit 1 through which a refrigerant that cools the drive system (e-PT) that drives the electric vehicle circulates, a radiator 109 that performs heat exchange between the refrigerant circulating in the first refrigerant circuit 1 and the outside air, a battery 202 capable of supplying power to the drive system (e-PT), a second refrigerant circuit 2 through which a refrigerant that cools the battery 202 circulates, a chiller 207 that performs heat exchange between the refrigerant circulating in the second refrigerant circuit 2 and the refrigerant circulating in the heating means (condenser 32), and a connection between the first refrigerant circuit 1 and the second refrigerant circuit 2, through which the refrigerant discharged from the drive system (e-PT) flows to the radiator 109. A branch circuit (first branch circuit 4, second branch circuit 5) that bypasses the first refrigerant circuit 1 and supplies refrigerant to the chiller 207, forming a circulation path 8 that returns to the drive system (e-PT); a mode setting unit (first valve 107) that can mutually switch between a first mode (third mode, fifth mode) in which the refrigerant discharged from the drive system (e-PT) does not circulate through the first refrigerant circuit 1 but circulates through the circulation path 8, and a second mode (fourth mode, sixth mode) in which the first refrigerant circuit 1 and the second refrigerant circuit 2 circulate refrigerant independently of each other; and a setting unit (first valve 107) that sets the temperature (Tc) of the refrigerant introduced into the drive system (e-PT) to a first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１ When the temperature of the refrigerant (Tc) introduced into the drive system (e-PT) is lower than the first threshold temperature (first refrigerant threshold temperature (Tc ｔｈ１A thermal management system for an electric vehicle, comprising: a control unit 7 that selects a second mode (fourth mode, sixth mode) when the temperature (Tc) of the refrigerant circulating in the circulation path 8 rises above a first threshold temperature (first refrigerant threshold temperature (Tc) ｔｈ１ A second threshold temperature (second refrigerant threshold temperature (Tc)) lower than the second threshold temperature (Tc) ｔｈ２ When the value exceeds this, the mode selection unit (first valve 107) is set to the intermediate mode (first intermediate mode, second intermediate mode).

[0118] With the above configuration, sudden temperature fluctuations in the refrigerants caused by mixing refrigerants with different temperatures can be suppressed, and mode hunting between the first mode (third mode, fifth mode) and the second mode (fourth mode, sixth mode) can be reduced. In addition, while set to the intermediate mode (first intermediate mode, second intermediate mode), the circulation path 8 in the first mode (third mode, fifth mode) is maintained, and thermal recovery can be continued by supplying the waste heat from the drive system (e-PT) to the chiller 207 to be used as the output of the heating means (condenser 32). For example, power consumption can be reduced compared to directly transitioning from the first mode (third mode, fifth mode) to the second mode (fourth mode, sixth mode) and directly heating the air used for heating in the second mode (fourth mode, sixth mode) with a heater or the like.

Claims

1. A thermal management method for an electric vehicle, comprising: a first refrigerant circuit through which a refrigerant for cooling a drive system that drives an electric vehicle circulates; a radiator that performs heat exchange between the refrigerant circulating in the first refrigerant circuit and the outside air; a battery capable of supplying power to the drive system; a second refrigerant circuit through which a refrigerant for cooling the battery circulates; a chiller that performs heat exchange between the refrigerant circulating in the second refrigerant circuit and a refrigerant circulating for heating means; and a branch circuit that connects the first refrigerant circuit and the second refrigerant circuit, forming a circulation path through which the refrigerant discharged from the drive system bypasses the radiator and is supplied to the chiller and returned to the drive system, wherein the method is set to a first mode in which, when the temperature of the refrigerant introduced into the drive system is lower than a first threshold temperature, the refrigerant discharged from the drive system does not circulate in the first refrigerant circuit but circulates in the circulation path, and the method is set to a second mode in which, when the temperature of the refrigerant introduced into the drive system is equal to or greater than the first threshold temperature, the first refrigerant circuit and the second refrigerant circuit circulate the refrigerant independently of each other. A thermal management method for an electric vehicle, wherein when the temperature of the refrigerant introduced into the drive system rises to a second threshold temperature lower than the first threshold temperature, the system sets the system to an intermediate mode in which the refrigerant circulating in the circulation path is gradually supplied to the radiator and returned to the circulation path.

2. A first refrigerant circuit that circulates a refrigerant to cool a drive system that drives an electric vehicle; a radiator that performs heat exchange between the refrigerant circulating in the first refrigerant circuit and the outside air; a second refrigerant circuit that circulates a refrigerant to cool a battery capable of supplying power to the drive system; a chiller that performs heat exchange between the refrigerant circulating in the second refrigerant circuit and a refrigerant circulating in a heating means; a first branch circuit that branches off from a position between the refrigerant inlet side of the drive system in the first refrigerant circuit and the refrigerant outlet side of the radiator, and merges with the second refrigerant circuit at a position that is the refrigerant outlet side of the chiller in the second refrigerant circuit; a second branch circuit that branches off from a position between the refrigerant output side of the drive system in the first refrigerant circuit and the refrigerant inlet side of the radiator, and merges with the second refrigerant circuit at a position that is the refrigerant inlet side of the chiller in the second refrigerant circuit; A thermal management method for an electric vehicle, comprising: a refrigerant distribution means positioned at the connection point between the first refrigerant circuit and the second branch circuit, which distributes refrigerant flowing in from the refrigerant discharge side of the drive system to the second branch circuit and the refrigerant inlet side of the radiator, and which can change the distribution ratio of a first flow rate of refrigerant flowing through the second branch circuit and a second flow rate of refrigerant flowing through the refrigerant inlet side of the radiator; a first mode in which the second flow rate becomes zero when the temperature of the refrigerant introduced into the drive system is lower than a first threshold temperature; a second mode in which the first flow rate becomes zero when the temperature of the refrigerant introduced into the drive system is equal to or greater than the first threshold temperature; and an intermediate mode in which the distribution ratio is set to a non-zero first flow rate when the temperature of the refrigerant introduced into the drive system rises to a second threshold temperature lower than the first threshold temperature.

3. A thermal management method for an electric vehicle according to claim 1 or 2, wherein the method switches from the second mode to the first mode when the temperature of the refrigerant falls from a temperature above the first threshold temperature to a temperature below the second threshold temperature.

4. A thermal management method for an electric vehicle according to claim 1 or 2, wherein the intermediate mode is executed for a predetermined time, the system is set to the first mode when the temperature of the refrigerant introduced into the drive system after the predetermined time is lower than the first threshold temperature, and the system is set to the second mode when the temperature of the refrigerant introduced into the drive system after the predetermined time is equal to or greater than the first threshold temperature.

5. A first refrigerant circuit through which a refrigerant for cooling the drive system that drives the electric vehicle circulates; a radiator that performs heat exchange between the refrigerant circulating in the first refrigerant circuit and the outside air; a battery capable of supplying power to the drive system; a second refrigerant circuit through which a refrigerant for cooling the battery circulates; a chiller that performs heat exchange between the refrigerant circulating in the second refrigerant circuit and the refrigerant circulating in the heating means; a branch circuit that connects the first refrigerant circuit and the second refrigerant circuit, forming a circulation path through which the refrigerant discharged from the drive system bypasses the radiator and is supplied to the chiller and returned to the drive system; a mode setting unit that can mutually switch between a first mode in which the refrigerant discharged from the drive system does not circulate in the first refrigerant circuit but circulates in the circulation path, and a second mode in which the first refrigerant circuit and the second refrigerant circuit circulate refrigerant independently of each other. A thermal management system for an electric vehicle, comprising: a control unit that selects the first mode when the temperature of the refrigerant introduced into the drive system is lower than a first threshold temperature, and selects the second mode when the temperature of the refrigerant introduced into the drive system is equal to or greater than the first threshold temperature, wherein the mode setting unit includes an intermediate mode in which the refrigerant circulating in the circulation path is gradually supplied to the radiator and returned to the circulation path, and the control unit sets the mode setting unit to the intermediate mode when the temperature of the refrigerant introduced into the drive system rises to a second threshold temperature lower than the first threshold temperature.

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