Thermal management system for vehicles

Abstract

The present invention provides a vehicle thermal management system. When the regenerative power is excessive relative to the power that can be charged to the main battery, compared with when the regenerative power is not excessive relative to the power that can be charged to the main battery, the control device supplies the regenerative power to increase the output of the low-voltage system air conditioning equipment. Therefore, it is possible to reduce the output (work amount and power per unit time) of the high-voltage system air conditioning equipment required to maintain the comfort of the vehicle occupants. Therefore, it is possible to improve the power economy while maintaining the comfort of the vehicle occupants.

Description

Technical Field

[0001] The present invention relates to a thermal management system for a vehicle equipped with a main battery and an auxiliary battery. Background Art

[0002] Japanese Patent Application Laid-Open No. 2004-254465 discloses a technique for increasing the power consumption of a plurality of electrical loads to consume excess regenerative power when the regenerative power is excessive.

[0003] However, in the case of an EV (Electric Vehicle) or a PHV (Plug-in Hybrid Vehicle), there is a need to improve power economy as much as possible. However, in the technique disclosed in the above publication, there is no disclosure of a technique for reducing the work amount of a high-voltage system air-conditioning device supplied with power from the main battery by using excess regenerative power. Therefore, there is room for improvement in terms of improving power economy. Summary of the Invention

[0004] An object of the present invention is to provide a vehicle thermal management system capable of improving power economy.

[0005] The present invention for achieving the above object is as follows.

[0006] (1) A vehicle thermal management system, comprising:

[0007] A high-voltage system air-conditioning device that receives power supply from a main battery;

[0008] A low-voltage system air-conditioning device that receives power supply from an auxiliary battery having an output voltage lower than that of the main battery; and

[0009] A control device having a travel control ECU and an air-conditioning ECU connected to be able to communicate with each other, and when the regenerative power is excessive with respect to the power that can be charged to the main battery, supplies the regenerative power to increase the output of the low-voltage system air-conditioning device as compared with when the regenerative power is not excessive with respect to the power that can be charged to the main battery.

[0010] (2) The vehicle thermal management system according to (1), wherein the control device changes the output of the high-voltage system air-conditioning device according to the output of the low-voltage system air-conditioning device.

[0011] (3) The vehicle thermal management system according to (2), wherein the control device reduces the output of the high-voltage system air-conditioning device when the output of the low-voltage system air-conditioning device is increased as compared with when the output of the low-voltage system air-conditioning device is not increased.

[0012] (4) The vehicle thermal management system according to any one of (1) to (3), wherein

[0013] the main battery can exchange power with the motor generator.

[0014] A DCDC converter for stepping down the voltage from the power path is provided between the power path between the main battery and the motor generator and the auxiliary battery.

[0015] When the regenerative power is excessive, the control device increases the voltage of the DCDC converter and thus increases the voltage of the auxiliary battery compared to when the regenerative power is not excessive with respect to the power that can be charged to the main battery, thereby increasing the output of the low-voltage system air conditioning device.

[0016] According to the vehicle thermal management system of the above (1), when the regenerative power is excessive with respect to the power that can be charged to the main battery, the control device supplies the regenerative power and increases the output of the low-voltage system air conditioning device compared to when the regenerative power is not excessive with respect to the power that can be charged to the main battery. Therefore, the output (work amount and power per unit time) of the high-voltage system air conditioning device required to maintain the comfort of the vehicle occupants can be reduced. Therefore, it is possible to improve the power economy while maintaining the comfort of the vehicle occupants.

[0017] According to the vehicle thermal management system of the above (2) or (3), the control device changes the output of the high-voltage system air conditioning device according to the output of the low-voltage system air conditioning device. Therefore, when the output of the low-voltage system air conditioning device is increased, the output of the high-voltage system air conditioning device can be reduced compared to when the output of the low-voltage system air conditioning device is not increased. Therefore, it is possible to improve the power economy while maintaining the comfort of the vehicle occupants.

[0018] According to the vehicle thermal management system of the above (4), the control device increases the voltage of the auxiliary battery by increasing the voltage of the DCDC converter, thereby increasing the output of the low-voltage system air conditioning device. Therefore, the output of the low-voltage system air conditioning device can be increased relatively simply. Description of the Drawings

[0019] Hereinafter, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present invention will be described with reference to the drawings, in which like reference numerals represent like components.

[0020] Figure 1 It is a schematic structural diagram of a vehicle when the vehicle equipped with the vehicle thermal management system of the embodiment of the present invention is a PHV.

[0021] Figure 2It is a control flowchart of a control device in a vehicle thermal management system according to an embodiment of the present invention.

[0022] Figure 3 It is a diagram showing the relationship between the output of a high-voltage system air-conditioning device and the output of a low-voltage system air-conditioning device in a vehicle thermal management system according to an embodiment of the present invention. Detailed Embodiments

[0023] Hereinafter, with reference to the drawings, a vehicle thermal management system (which may also be referred to as a vehicle air-conditioning device) 10 according to an embodiment of the present invention will be described.

[0024] Figure 1 An example of a vehicle 20 equipped with a vehicle thermal management system 10 (hereinafter, also simply referred to as the system) according to an embodiment of the present invention is shown. In addition, in Figure 1 it is shown that the vehicle 20 equipped with the system 10 is a PHV (Plug-in Hybrid Vehicle), but as long as the vehicle 20 has a main battery 22 and an auxiliary battery 32 described later, it may also be an EV (Electric Vehicle), an HV (Hybrid Vehicle), or an FCV (Fuel Cell Vehicle).

[0025] As Figure 1 shown, the vehicle 20 has a main battery 22, a PCU (Power Control Unit) 24, an engine 26, first and second motor / generators 28a, 28b housed in a drive axle 28, a rear motor / generator 30a housed in a rear transmission shaft 30, and an auxiliary battery 32.

[0026] The main battery 22 is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The output voltage V1 of the main battery 22 is higher than the output voltage V2 of the auxiliary battery 32.

[0027] The PCU 24 is electrically connected to the main battery 22 and each of the motor / generators 28a, 28b, 30a. The PCU 24 converts the power of the main battery 22 into power for driving each of the motor / generators 28a, 28b, 30a. The PCU 24 has a converter 24a and first to third inverters 24b, 24c, 24d.

[0028] The converter 24a boosts the DC power supplied from the main battery 22 and supplies the boosted DC power to the first to third inverters 24b, 24c, 24d. The converter 24a also steps down the DC power supplied from the first to third inverters 24b, 24c, 24d and supplies the stepped-down DC power to the main battery 22.

[0029] The first to third inverters 24b, 24c, and 24d convert the DC power supplied from the main battery 22 and boosted by the converter 24a into three-phase AC power, and supply the converted AC power to the first and second motor generators 28a, 28b and the rear motor generator 30a. The first to third inverters 24b, 24c, and 24d also convert the AC power supplied from the first and second motor generators 28a, 28b and the rear motor generator 30a into DC power, and supply the converted DC power to the converter 24a.

[0030] The first and second motor generators 28a, 28b and the rear motor generator 30a are composed of three-phase synchronous motors. The first motor generator 28a is electrically connected to the first inverter 24b. The first motor generator 28a can start the engine 26. The first motor generator 28a can generate electricity by transmitting the output of the engine 26. Therefore, the power generated by the first motor generator 28a can charge the main battery 22 via the PCU 24.

[0031] The second motor generator 28b is electrically connected to the second inverter 24c. Similar to the engine 26, the second motor generator 28b can transmit power to the front wheels (drive wheels) 34 of the vehicle. The second motor generator 28b is driven by the rotational force of the front wheels 34 during regenerative braking of the vehicle 20 and can generate electricity. The regenerative power generated by the second motor generator 28b can charge the main battery 22 via the PCU 24.

[0032] The rear motor generator 30a is electrically connected to the third inverter 24d. The rear motor generator 30a can transmit power to the rear wheels (drive wheels) 36 of the vehicle. The rear motor generator 30a can be driven by the rotational force of the rear wheels 36 and generate electricity during regenerative braking of the vehicle 20. The regenerative power generated by the rear motor generator 30a can charge the main battery 22 via the PCU 24.

[0033] The PCU 24 also has a DCDC converter 24e. That is, the PCU 24 has a structure integrated with the first to third inverters 24b, 24c, 24d, the converter 24a, and the DCDC converter 24e.

[0034] The DCDC converter 24e is disposed between the power path L between the main battery 22 and each of the motor generators 28a, 28b, 30a (more specifically, between the main battery 22 and the converter 24a) and the auxiliary battery 32. The DCDC converter 24e steps down the voltage V1 in the power path L (equivalent to the output voltage of the main battery 22) to the output voltage V2 of the auxiliary battery 32. The DCDC converter 24e steps down the power output from the main battery 22 and the regenerative power output from the second motor generator 28b and the rear motor generator 30a and stepped down to the output voltage V1 of the main battery 22 by the converter 24a to the output voltage V2 of the auxiliary battery 32 and supplies it to the auxiliary battery 32.

[0035] The auxiliary battery 32 is constituted by, for example, a lead storage battery. The auxiliary battery 32 is charged by the power output from the main battery 22 or the regenerative power and the power stepped down by the DCDC converter 24e.

[0036] Next, the vehicle thermal management system 10 of the embodiment of the present invention will be described. The system 10 includes a high-voltage system air-conditioning device 12 supplied with power from the main battery 22, a low-voltage system air-conditioning device 14 supplied with power from the auxiliary battery 32, and a control device 16.

[0037] The high-voltage system air-conditioning device 12 is a device that air-conditions the passenger compartment by being supplied with DC power of the output voltage V1 of the main battery 22. The high-voltage system air-conditioning device 12 is connected to the power path L between the main battery 22 and each of the motor generators 28a, 28b, 30a (more specifically, between the main battery 22 and the converter 24a).

[0038] The high-voltage system air-conditioning device 12 has, for example, a water heater (electric heater) 12a and / or an electric compressor 12b provided in the air-conditioning heat pump circuit. In addition, the water heater (electric heater) 12a is provided in the cooling water circuit and is a heater that heats the cooling water flowing in the cooling water circuit to heat the heating element and the heater core. The cooling water circuit is provided with a heating element constituted by the main battery 22 or the engine 26 and a heater core (not shown) that exchanges heat with the air for air-conditioning to heat the air for air-conditioning. In addition, the air-conditioning heat pump circuit is a circuit in which a cooling medium for air-conditioning circulates, and the electric compressor 12b compresses and discharges the cooling medium for air-conditioning.

[0039] The low-voltage system air-conditioning device 14 is separately provided from the high-voltage system air-conditioning device 12, and is an auxiliary air-conditioning device provided to further improve the comfort of the vehicle occupants compared to the case where only the high-voltage system air-conditioning device 12 is present. The low-voltage system air-conditioning device 14 operates by being supplied with DC power of the output voltage V2 of the auxiliary battery 32. The low-voltage system air-conditioning device 14 has, for example, at least one of a steering wheel heater 14a, an electric fan 14b, a seat heater 14c, a seat cooler 14d, and a seat ventilation system 14e. In addition, the steering wheel heater 14a is a device for heating a steering wheel (not shown). The electric fan 14b is a device for supplying cooling air to a condenser (heat exchanger, not shown) provided in an air-conditioning heat pump circuit. The seat heater 14c is a device for heating a seat. The seat cooler 14d is a device for cooling a seat. The seat ventilation system 14e is a device for improving the ventilation of the seat by operating a fan provided inside the seat and releasing the heat of the seat.

[0040] The control device 16 has a travel control ECU 17 and an air-conditioning ECU 18 that are communicably connected to each other.

[0041] The travel control ECU 17 controls the main battery 22 and the PCU 24. When the regenerative power is not excessive, the travel control ECU 17 performs control to supply the regenerative power to the main battery 22. On the other hand, when the regenerative power is excessive, the travel control ECU 17 performs control to prevent the regenerative power from being supplied to the main battery 22 so that the main battery 22 is not overcharged (regenerative prohibition control to the main battery 22).

[0042] It should be noted that the "case where the regenerative power is not excessive" means that when the regenerative power is not excessive compared to the power that can be charged to the main battery 22, it is the case where the regenerative power is less than the power that can be charged to the main battery 22. In addition, the "case where the regenerative power is excessive" means that when the regenerative power is excessive compared to the power that can be charged to the main battery 22, it is the case where the regenerative power is more than the power that can be charged to the main battery 22.

[0043] The travel control ECU 17 controls the DCDC converter 24e. Specifically, when the regenerative power is not excessive, the output voltage of the DCDC converter 24e remains V2, but when the regenerative power is excessive in the state where the high-voltage system air-conditioning device 12 is operating, control is performed to set the output voltage of the DCDC converter 24e to V2-High, which is higher than V2. In addition, the voltage V2-High is a voltage lower than the voltage V1.

[0044] In addition, when the high-voltage system air-conditioning device 12 is operating, and when there is excess regenerative power and the low-voltage system air-conditioning device 14 is operating, the driving control ECU 17 performs control to preferentially supply the excess regenerative power to the auxiliary battery 32 via the DCDC converter 24e whose set voltage is increased from V2 to V2-High. As a result, the voltage of the auxiliary battery 32 is increased from V2 to V2-High, and the output of the low-voltage system air-conditioning device 14 powered by the auxiliary battery 32 is increased.

[0045] The air-conditioning ECU 18 controls the high-voltage system air-conditioning device 12 and the low-voltage system air-conditioning device 14. When the high-voltage system air-conditioning device 12 is operating and there is excess regenerative power, the air-conditioning ECU 18 determines whether the low-voltage system air-conditioning device 14 is operating, and sends the determination result to the driving control ECU 17.

[0046] In addition, when the driving control ECU 17 supplies excess regenerative power to the auxiliary battery 32 via the DCDC converter 24e whose set voltage is increased from V2 to V2-High, the air-conditioning ECU 18 performs control to change the output of the high-voltage system air-conditioning device 12 according to the output (operating condition) of the low-voltage system air-conditioning device 14. Specifically, as Figure 3 shown, when increasing the output of the low-voltage system air-conditioning device 14, compared with when the output of the low-voltage system air-conditioning device 14 is not increased, control is performed to decrease the output of the high-voltage system air-conditioning device 12.

[0047] Figure 2 is a flowchart showing a control routine of the control device 16. Figure 2 The control routine shown is executed when regenerative power is generated while the high-voltage system air-conditioning device 12 is operating.

[0048] First, in step S1, it is determined whether there is excess regenerative power (whether the driving control ECU 17 has performed regeneration inhibition control on the main battery 22). If it is determined in step S1 that there is no excess regenerative power, the process proceeds to step S5, the voltage of the DCDC converter 24e is not increased from V2 to V2-High (the voltages of the DCDC converter 24e and the auxiliary battery 32 are not increased), and the process directly proceeds to the end step.

[0049] On the other hand, if it is determined in step S1 that there is excess regenerative power, the process proceeds to step S2, the driving control ECU 17 is used to increase the set voltage of the DCDC converter 24e from V2 to V2-High, and the process proceeds to step S3.

[0050] In step S3, the air conditioner ECU 18 determines whether the low-voltage system air-conditioning device 14 is operating. If it is determined in step S3 that the low-voltage system air-conditioning device 14 is not operating, the process proceeds to step S5, where the voltage of the DCDC converter 24e is returned from V2-High to V2 without increasing the voltage of the DCDC converter 24e and the auxiliary battery 32, and the process directly proceeds to the end step.

[0051] On the other hand, if it is determined in step S3 that the low-voltage system air-conditioning device 14 is operating, the process proceeds to step S4. Then, in step S4, (i) the driving control ECU 17 preferentially supplies the excess regenerative power to the auxiliary battery 32 via the DCDC converter 24e with increased voltage, thereby increasing the voltage of the auxiliary battery 32 from V2 to V2-High to increase the output of the low-voltage system air-conditioning device 14, and (ii) the air conditioner ECU 18 performs control to suppress the output of the high-voltage system air-conditioning device 12 based on the output of the low-voltage system air-conditioning device 14. Then, the process proceeds to the end step.

[0052] Next, the functions and effects of the embodiment of the present invention will be described.

[0053] (A) When the regenerative power is excessive compared to the power that can be charged to the main battery 22, the control device 16 supplies the regenerative power to increase the output of the low-voltage system air-conditioning device 14 compared to when the regenerative power is not excessive compared to the power that can be charged to the main battery 22. Therefore, it is possible to reduce the output (work amount and power per unit time) of the high-voltage system air-conditioning device required to maintain the comfort of the vehicle occupants. Therefore, it is possible to improve the power economy while maintaining the comfort of the vehicle occupants.

[0054] (B) The control device 16 changes the output of the high-voltage system air-conditioning device 12 according to the output of the low-voltage system air-conditioning device 14. Therefore, when increasing the output of the low-voltage system air-conditioning device 14, it is possible to reduce the output of the high-voltage system air-conditioning device 12 compared to when the output of the low-voltage system air-conditioning device 14 is not increased. Therefore, it is possible to improve the power economy while maintaining the comfort of the vehicle occupants.

[0055] (C) The control device 16 increases the voltage of the auxiliary battery 32 by increasing the voltage of the DCDC converter 24e, thereby increasing the output of the low-voltage system air-conditioning device 14. Therefore, it is possible to relatively simply increase the output of the low-voltage system air-conditioning device 14.

[0056] In addition, in the embodiment of the present invention, the case where the output of the low-voltage system air-conditioning device 14 is increased when the low-voltage system air-conditioning device 14 also operates under the condition that the high-voltage system air-conditioning device 12 operates has been described. However, when the high-voltage system air-conditioning device 12 operates and the low-voltage system air-conditioning device 14 does not operate, the low-voltage system air-conditioning device 14 may be forcibly (automatically) operated to increase the output of the low-voltage system air-conditioning device 14 with excess regenerative power.

Claims

1. A vehicle thermal management system having: A high-voltage system air conditioning device that receives power supply from a main battery, and the main battery can exchange power with an electric generator; A low-voltage system air conditioning device that receives power supply from an auxiliary battery with an output voltage lower than that of the main battery; A DCDC converter is provided between the power path between the main battery and the electric generator and the auxiliary battery, and steps down the voltage V1 from the power path to the output voltage V2 of the auxiliary battery, where V2 is less than V1; And A control device having a driving control ECU and an air conditioning ECU connected to be able to communicate with each other, and changes the output of the high-voltage system air conditioning device according to the output of the low-voltage system air conditioning device. When the regenerative power is excessive compared to the power that can be charged to the main battery, as compared with when the regenerative power is not excessive compared to the power that can be charged to the main battery, the output voltage of the DCDC converter is set to V2-High which is higher than V2, thereby increasing the output of the low-voltage system air conditioning device and reducing the output of the high-voltage system air conditioning device, where V2-High is less than V1.

Images