A battery thermal management system and method for a hybrid vehicle

Abstract

This invention discloses a battery thermal management system and method for hybrid vehicles. The system includes a lithium battery pack, a hydrogen fuel cell pack, a lithium battery pack water pump, a hydrogen fuel cell pack water pump, a plate heat exchanger, an electronic three-way valve, a thermostat, a battery management system (BMS), a controller, and dual-tank cooling fans. The electronic three-way valve is connected to the coolant outlet of the lithium battery pack, the low-temperature side of the plate heat exchanger, and the dual-tank cooling fans. The thermostat is connected to the coolant outlet of the hydrogen fuel cell pack, the high-temperature side of the plate heat exchanger, and the dual-tank cooling fans. The outlet of the lithium battery pack water pump is connected to the coolant inlet of the lithium battery pack, and the outlet of the hydrogen fuel cell pack water pump is connected to the coolant inlet of the hydrogen fuel cell pack. The BMS and controller are used to adjust the thermostat opening. This invention can fully realize the complementary advantages of lithium batteries and hydrogen fuel cells, overcoming the low-temperature operation limitations of hybrid vehicle systems.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicles and relates to battery thermal management technology for hybrid vehicles, specifically to a battery thermal management system and method for hybrid vehicles. Background Technology

[0002] With the rapid development of new energy vehicles, lithium batteries and hydrogen fuel cells, as two major power sources, each have their unique advantages. Lithium batteries have high energy density and fast charge / discharge capabilities, but their charge / discharge performance deteriorates significantly under extremely cold conditions. Hydrogen fuel cells, on the other hand, have strong low-temperature start-up capabilities and relatively stable performance in low-temperature environments, and can generate a large amount of waste heat during operation.

[0003] Existing hybrid power systems typically employ independent temperature control systems to manage both lithium-ion batteries and hydrogen fuel cells, lacking thermal coupling and coordinated control between the two. This prevents them from fully leveraging the advantages of each, resulting in complex systems with low energy efficiency. Particularly in extremely cold conditions, the heating problem of lithium-ion batteries remains unresolved, impacting overall vehicle performance. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the prior art, a battery thermal management system and method for hybrid vehicles is provided, which can fully realize the complementary advantages of lithium batteries and hydrogen fuel cells and overcome the low-temperature operation limitations of hybrid vehicle systems.

[0005] Technical Solution: To achieve the above objectives, this invention provides a battery thermal management system for a hybrid vehicle, comprising a lithium battery pack, a hydrogen fuel cell pack, a lithium battery pack water pump, a hydrogen fuel cell pack water pump, a plate heat exchanger, an electronic three-way valve, a thermostat, a battery management system (BMS), a controller, and a dual-tank cooling fan. The electronic three-way valve is connected to the coolant outlet of the lithium battery pack, the low-temperature side of the plate heat exchanger, and the dual-tank cooling fan. The thermostat is connected to the coolant outlet of the hydrogen fuel cell pack, the high-temperature side of the plate heat exchanger, and the dual-tank cooling fan. The low-temperature side of the plate heat exchanger and the dual-tank cooling fan are connected in parallel to the inlet of the lithium battery pack water pump. The outlet of the lithium battery pack water pump is connected to the coolant inlet of the lithium battery pack. The high-temperature side of the plate heat exchanger and the dual-tank cooling fan are connected in parallel to the inlet of the hydrogen fuel cell pack water pump. The outlet of the hydrogen fuel cell pack water pump is connected to the coolant inlet of the hydrogen fuel cell pack. The battery management system (BMS) and the controller are used to adjust the thermostat opening to achieve battery thermal management control.

[0006] Furthermore, a first temperature sensor is installed at the coolant outlet of the lithium battery pack, a second temperature sensor and a third temperature sensor are installed at the coolant inlet and coolant outlet of the hydrogen fuel cell pack, respectively, and an ambient temperature sensor is installed at the air inlet of the dual-tank cooling fan.

[0007] Furthermore, the dual-tank cooling fan includes two cooling tanks and a set of cooling fans, with the outlets of the two cooling tanks connected to the inlet ends of the lithium battery pack water pump and the hydrogen fuel cell pack water pump, respectively.

[0008] This invention provides a control method for a battery thermal management system of a hybrid vehicle, comprising the following steps:

[0009] S1: Determine whether it is a low-temperature start-up based on the temperature. If yes, proceed to step S2; otherwise, proceed to step S3.

[0010] S2: Start the hydrogen fuel cell stack to reach the operating temperature in self-heating mode, then control the opening of the thermostat to allow the high-temperature coolant of the hydrogen fuel cell stack to flow into the plate heat exchanger, and simultaneously start the lithium battery pack water pump, and adjust the electronic three-way valve to allow the coolant of the lithium battery pack to enter the plate heat exchanger.

[0011] The temperature of the coolant in the lithium battery pack is increased by heat exchange through a plate heat exchanger, so that the lithium battery pack reaches the operating temperature and then proceeds to step S4.

[0012] S3: Determine whether the current mode is pure electric mode. If not, proceed directly to step S4.

[0013] If so, when the temperature of the hydrogen fuel cell stack is lower than the target operating temperature of the lithium battery stack, the heat of the lithium battery stack is transferred to the hydrogen fuel cell stack through the plate heat exchanger, and the temperature of the hydrogen fuel cell stack is raised to the target operating temperature of the lithium battery stack by controlling the electronic three-way valve and the thermostat, and the lithium battery stack is cooled by the dual water tank cooling fan.

[0014] S4: In hybrid mode, the coolant is directed to the dual-tank cooling fan via the electronic three-way valve and thermostat, which then cools the lithium battery pack and hydrogen fuel cell pack.

[0015] Furthermore, the thermostat opening control in step S2 includes:

[0016] when hour, , This refers to the inlet temperature of the coolant in the hydrogen fuel cell stack. The system's target operating temperature, For the first difference redundancy, This represents the opening degree of the thermostat; 0 indicates that the entire circuit flows through the heat exchanger loop.

[0017] when At that time, the closed-loop internal model algorithm is activated for opening control. This is the maximum permissible temperature for the coolant inlet of the hydrogen fuel cell stack.

[0018] Furthermore, in step S2, a closed-loop internal model algorithm is used for thermostat control, including:

[0019] A1: Establish a reference dynamic model of the controlled process: Build a thermal management subsystem using first-order elements. Approximate dynamic model This is used to represent the process characteristics of the thermal management system:

[0020]

[0021] in, The system gain coefficient. The system time constant, It is a complex rate variable;

[0022] A2: Determine the controller structure: Based on the system requirements and performance indicators, the controller parameters and structural form are as follows:

[0023]

[0024] in, The time constant of the first-order element designed within the controller;

[0025] A3: Implementing a feedback loop: Connecting the controller output with the actual output of the controlled process to form a closed-loop system;

[0026] A4: Conduct system analysis: After implementing the controller and feedback loop, the system needs to be analyzed to determine whether the controller's performance indicators meet the requirements, and to adjust and optimize the controller.

[0027] Furthermore, the control of the electronic three-way valve in step S2 includes:

[0028] when hour, ,in, This refers to the temperature of the cells within the lithium battery pack. Indicates the minimum allowable operating temperature of the battery cell. For the second differential redundancy, This is the opening value of the electronic three-way valve; 0 represents that the entire flow goes through the heat exchanger loop.

[0029] when At that time, the opening value of the electronic three-way valve Set it to the middle position, which is 50;

[0030] when At that time, the opening value of the electronic three-way valve Set to 100, where, This indicates the maximum allowable operating temperature of the battery cell; 100 means that all components are connected to the fan circuit.

[0031] Furthermore, the heat dissipation control of the lithium battery pack and hydrogen fuel cell pack via the dual-tank cooling fan in step S4 includes:

[0032] Set the lithium battery pack temperature to Hydrogen fuel cell stack set temperature The ambient temperature at the fan inlet is The fan's rated speed is The fan speed of the lithium battery pack is The fan speed of the hydrogen fuel cell stack is ;

[0033] like ,but ;

[0034] like ,but:

[0035]

[0036] in, Represents the current of the battery pack. This represents the rated current of the battery pack. This represents the design temperature difference between the battery pack's maximum operating temperature and the maximum ambient temperature when designing the fan assembly.

[0037] like ,but ;

[0038] like ,but:

[0039]

[0040] in, Represents the current power of the fuel cell stack. Represents rated power. This represents the design temperature difference between the highest operating temperature of the fuel cell stack and the highest ambient temperature when designing the fan assembly.

[0041] The final speed of the fan assembly according to and Speed ​​control is performed at a higher value:

[0042] .

[0043] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0044] 1. Lithium-ion battery packs utilize waste heat from hydrogen fuel cell stacks for heating: By transferring waste heat generated by the hydrogen fuel cell system to the lithium-ion battery pack through a thermal management system, its charging and discharging capabilities are rapidly restored. This method solves the performance degradation problem of lithium-ion batteries in low-temperature environments and also improves the energy utilization rate of the hydrogen fuel cell stack.

[0045] 2. Heat exchange is conducted between the lithium battery pack and the hydrogen fuel cell pack via a plate heat exchanger. A coolant inlet temperature sensor is installed, and the opening of the thermostat is controlled using an internal model algorithm (IMC) to achieve precise adjustment of the coolant outlet temperature, ensuring that the lithium battery pack and the hydrogen fuel cell pack operate within the optimal temperature range. Attached Figure Description

[0046] Figure 1 This is an architecture diagram of the battery thermal management system;

[0047] Figure 2 The flowchart shows the control method of the battery thermal management system.

[0048] Figure 3 This is a schematic diagram of the internal mold structure. Detailed Implementation

[0049] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0050] Example 1:

[0051] like Figure 1As shown, this embodiment provides a battery thermal management system for a hybrid vehicle, including a lithium battery pack, a hydrogen fuel cell pack, a lithium battery pack water pump, a hydrogen fuel cell pack water pump, a plate heat exchanger, an electronic three-way valve, a thermostat, a battery management system (BMS), a controller, and dual-tank cooling fans. The electronic three-way valve is connected to the coolant outlet of the lithium battery pack, the low-temperature side of the plate heat exchanger, and the dual-tank cooling fans. The thermostat is connected to the coolant outlet of the hydrogen fuel cell pack, the high-temperature side of the plate heat exchanger, and the dual-tank cooling fans. The low-temperature side of the plate heat exchanger and the dual-tank cooling fans are connected in parallel to the inlet of the lithium battery pack water pump. The outlet of the lithium battery pack water pump is connected to the coolant inlet of the lithium battery pack. The high-temperature side of the plate heat exchanger and the dual-tank cooling fans are connected in parallel to the inlet of the hydrogen fuel cell pack water pump. The outlet of the hydrogen fuel cell pack water pump is connected to the coolant inlet of the hydrogen fuel cell pack. The battery management system (BMS) and the controller are used to adjust the thermostat opening to achieve battery thermal management control.

[0052] A first temperature sensor is installed at the coolant outlet of the lithium battery pack, a second temperature sensor and a third temperature sensor are installed at the coolant inlet and coolant outlet of the hydrogen fuel cell pack, respectively, and an ambient temperature sensor is installed at the air inlet of the dual-tank cooling fan.

[0053] The dual-tank cooling fan consists of two cooling tanks and a set of cooling fans. The outlets of the two cooling tanks are connected to the inlet of the lithium battery pack water pump and the hydrogen fuel cell pack water pump, respectively.

[0054] Example 2:

[0055] like Figure 2 As shown, this embodiment provides a control method for a battery thermal management system of a hybrid vehicle, including the following steps:

[0056] S1: Determine whether it is a low-temperature start-up based on the temperature. If yes, proceed to step S2; otherwise, proceed to step S3.

[0057] S2: Start the hydrogen fuel cell stack and reach the operating temperature in self-heating mode (obtained through the third temperature sensor). Then control the opening of the thermostat to allow the high-temperature coolant of the hydrogen fuel cell stack to flow into the plate heat exchanger. Simultaneously start the lithium battery pack water pump and adjust the electronic three-way valve to allow the coolant of the lithium battery pack to enter the plate heat exchanger.

[0058] The temperature of the coolant in the lithium battery pack is increased by heat exchange through a plate heat exchanger, so that the lithium battery pack reaches the operating temperature and then proceeds to step S4.

[0059] S3: Determine whether the current mode is pure electric mode. If not, proceed directly to step S4.

[0060] If so, when the temperature of the hydrogen fuel cell stack is lower than the target operating temperature of the lithium battery stack, the heat of the lithium battery stack is transferred to the hydrogen fuel cell stack through the plate heat exchanger, and the temperature of the hydrogen fuel cell stack is raised to the target operating temperature of the lithium battery stack by controlling the electronic three-way valve and the thermostat, and the lithium battery stack is cooled by the dual water tank cooling fan.

[0061] S4: In hybrid mode, the coolant is directed to the dual-tank cooling fan via the electronic three-way valve and thermostat, which then cools the lithium battery pack and hydrogen fuel cell pack.

[0062] In steps S2~S4:

[0063] Thermostat opening control includes:

[0064] when hour, , The inlet temperature of the hydrogen fuel cell stack coolant (obtained via a second temperature sensor). The system's target operating temperature, This serves as the first redundancy, ensuring a certain margin. This represents the opening degree of the thermostat; 0 indicates that the entire circuit flows through the heat exchanger loop.

[0065] when At that time, the closed-loop internal model algorithm is activated for opening control. This is the maximum permissible temperature for the coolant inlet of the hydrogen fuel cell stack.

[0066] like Figure 3 As shown, a closed-loop internal model algorithm is used for thermostat control, specifically including:

[0067] A1: Establish a reference dynamic model of the controlled process: Build a thermal management subsystem using first-order elements. Approximate dynamic model This is used to represent the process characteristics of the thermal management system:

[0068]

[0069] in, The system gain coefficient. The system time constant, It is a complex rate variable;

[0070] A2: Determine the controller structure: Based on the system requirements and performance indicators, the controller parameters and structural form are as follows:

[0071]

[0072] in, The time constant of the first-order element designed within the controller;

[0073] A3: Implementing a feedback loop: Connecting the controller output with the actual output of the controlled process to form a closed-loop system;

[0074] A4: Conduct system analysis: After implementing the controller and feedback loop, the system needs to be analyzed to determine whether the controller's performance indicators meet the requirements, and to adjust and optimize the controller.

[0075] The control of the electronic three-way valve includes:

[0076] when hour, ,in, The temperature of the cells inside the lithium battery pack (obtained via the first temperature sensor). Indicates the minimum allowable operating temperature of the battery cell. This serves as a second redundancy, ensuring a certain margin. This is the opening value of the electronic three-way valve; 0 represents that the entire flow goes through the heat exchanger loop.

[0077] when At that time, the opening value of the electronic three-way valve Set it to the middle position, which is 50;

[0078] when At that time, the opening value of the electronic three-way valve Set to 100, where, This indicates the maximum allowable operating temperature of the battery cell; 100 means that all components are connected to the fan circuit.

[0079] The control expression of an electronic three-way valve is as follows:

[0080]

[0081] Step S4, which controls the cooling of the lithium battery pack and hydrogen fuel cell pack using a dual-tank cooling fan, includes:

[0082] Set the lithium battery pack temperature to Hydrogen fuel cell stack set temperature The ambient temperature at the fan inlet is (Obtained via ambient temperature sensor), fan rated speed is The fan speed of the lithium battery pack is The fan speed of the hydrogen fuel cell stack is ;

[0083] like ,but ;

[0084] like ,but:

[0085]

[0086] in, Represents the current of the battery pack. This represents the rated current of the battery pack. This represents the design temperature difference between the battery pack's maximum operating temperature and the maximum ambient temperature when designing the fan assembly.

[0087] like ,but ;

[0088] like ,but:

[0089]

[0090] in, Represents the current power of the fuel cell stack. Represents rated power. This represents the design temperature difference between the highest operating temperature of the fuel cell stack and the highest ambient temperature when designing the fan assembly.

[0091] The final speed of the fan assembly according to and Speed ​​control is performed at a higher value:

[0092] .

[0093] Through the above control method, this embodiment achieves the following effects:

[0094] 1. Lithium-ion batteries are heated using waste heat from the hydrogen fuel cell system: Under extremely cold conditions, waste heat generated by the hydrogen fuel cell system is transferred to the lithium-ion batteries through a thermal management system to heat them and rapidly restore their charge and discharge capabilities. This method not only solves the performance degradation problem of lithium-ion batteries in low-temperature environments but also improves the energy utilization rate of the hydrogen fuel cell system.

[0095] 2. High-efficiency heat exchange and temperature control between lithium batteries and hydrogen fuel cells: Heat exchange occurs between the lithium battery pack and the hydrogen fuel cell pack via a plate heat exchanger. A coolant inlet temperature sensor is installed, and an internal model algorithm (IMC) is used to control the thermostat opening, achieving precise adjustment of the coolant outlet temperature. The IMC algorithm features fast response speed and strong anti-interference capability, effectively handling dynamic changes in the system and ensuring that the lithium battery and hydrogen fuel cell operate within their optimal temperature range.

Claims

1. A control method of a battery thermal management system of a hybrid vehicle, characterized by, The battery thermal management system comprises a lithium battery pack, a hydrogen fuel cell pack, a lithium battery pack water pump, a hydrogen fuel cell pack water pump, a plate heat exchanger, an electronic three-way valve, a thermostat, a battery management system (BMS), a controller and a double-tank cooling fan, the electronic three-way valve is connected with the cooling liquid outlet of the lithium battery pack, the low-temperature side of the plate heat exchanger and the double-tank cooling fan respectively, the thermostat is connected with the cooling liquid outlet of the hydrogen fuel cell pack, the high-temperature side of the plate heat exchanger and the double-tank cooling fan respectively, the low-temperature side of the plate heat exchanger and the double-tank cooling fan are connected with the inlet end of the lithium battery pack water pump in parallel, the outlet end of the lithium battery pack water pump is connected with the cooling liquid inlet of the lithium battery pack, the high-temperature side of the plate heat exchanger and the double-tank cooling fan are connected with the inlet end of the hydrogen fuel cell pack water pump in parallel, and the outlet end of the hydrogen fuel cell pack water pump is connected with the cooling liquid inlet of the hydrogen fuel cell pack; the BMS and the controller are used for adjusting the opening degree of the thermostat to realize battery thermal management control. The control method comprises the following steps: S1: judging whether it belongs to low-temperature starting according to the temperature condition, if yes, entering step S2, otherwise entering step S3; S2: starting the hydrogen fuel cell pack to reach the working temperature in the self-heating mode, then controlling the opening degree of the thermostat to make the high-temperature cooling liquid of the hydrogen fuel cell pack flow into the plate heat exchanger, synchronously starting the lithium battery pack water pump, and adjusting the electronic three-way valve to make the cooling liquid of the lithium battery pack enter the plate heat exchanger; The temperature of the cooling liquid of the lithium battery pack is raised through the heat exchange of the plate heat exchanger, so that the lithium battery pack reaches the working temperature and enters step S4; S3: judging whether the current mode is the pure electric mode, if not, directly entering step S4; if yes, when the temperature of the hydrogen fuel cell pack is lower than the target working temperature of the lithium battery pack, the heat of the lithium battery pack is transferred to the hydrogen fuel cell pack through the plate heat exchanger, and the temperature of the hydrogen fuel cell pack is raised to the target working temperature of the lithium battery pack through the control of the electronic three-way valve and the thermostat, and the lithium battery pack is cooled through the double-tank cooling fan; S4: running the hybrid mode, making the cooling liquid flow to the double-tank cooling fan through the adjustment of the electronic three-way valve and the thermostat, and cooling the lithium battery pack and the hydrogen fuel cell pack through the double-tank cooling fan; The control of the electronic three-way valve in step S2 comprises: When Time, Where, is the temperature of the cell within the lithium battery pack, represents the minimum allowable operating temperature of the cell, is the second difference redundancy, is the electronic three-way valve opening value, 0 represents all the heat exchanger circuit; When the electronic three-way valve opening value is set to the intermediate position, i.e. 50; When electronic three-way valve opening value is set to 100, wherein, represents the maximum allowable operating temperature of the battery cell, and 100 represents that all the fan circuits are running. The opening degree control of the thermostat in step S2 comprises: When , , is the hydrogen fuel cell pack coolant inlet temperature, is the system target operating temperature, is the first difference redundancy, is the opening of the thermostat, 0 represents all the way to the heat exchanger circuit; When the closed loop internal model algorithm is initiated for opening control, Tmax is the maximum allowable temperature for the hydrogen fuel cell stack coolant inlet; The control of the lithium battery pack and the hydrogen fuel cell pack through the double-tank cooling fan in step S4 comprises: The lithium battery pack set temperature is set as , the hydrogen fuel cell pack set temperature , the fan inlet ambient temperature is set as , the fan rated rotation speed is set as , the lithium battery pack fan rotation speed is set as , the hydrogen fuel cell pack fan rotation speed is set as ; If then ; If then: ； wherein, represents the current battery pack current, represents the rated battery pack current, represents the design temperature difference between the maximum operating temperature of the battery pack and the maximum ambient temperature; If then ; If then: ； wherein, represents the current power of the fuel cell stack, represents the rated power, represents the design temperature difference between the maximum operating temperature of the fuel cell stack and the maximum ambient temperature; Final rotation speed of the fan group According to With The higher value of the rotation speed control: 。 2. The control method according to claim 1, characterized by, A first temperature sensor is arranged at the cooling liquid outlet of the lithium battery pack, a second temperature sensor and a third temperature sensor are arranged at the cooling liquid inlet and the cooling liquid outlet of the hydrogen fuel cell pack respectively, and an environment temperature sensor is arranged at the air inlet of the double-tank cooling fan.

3. The control method according to claim 1, characterized by, The double-tank cooling fan comprises two cooling water tanks and a set of cooling fans, and the outlet ends of the two cooling water tanks are connected with the inlet ends of the lithium battery pack water pump and the hydrogen fuel cell pack water pump respectively.

Images