Battery heat management mode switching method based on hot gas bypass heat pump system

Abstract

The invention relates to the technical field of heat management, and belongs to a battery heat management mode switching method based on a hot gas bypass heat pump system, which focuses on the coordination of multi-stage heat sources such as electric drive waste heat recovery, electric drive active locked-rotor heating, a common heat pump, a hot gas bypass heat pump and the like and the real-time arbitration of the use of each heat source in combination with environment and whole vehicle parameters. And under the condition that the battery is actively or passively heated, the temperature of the battery can be always kept in a proper interval. Meanwhile, multiple thermal management modes such as active refrigeration, passive refrigeration and self-circulation of the battery are mixed, the state machine design meets the all-around thermal management requirement of the battery, and it is guaranteed that the temperature of the battery is always kept within a proper interval.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal management, and belongs to a battery thermal management mode switching method based on a hot gas bypass heat pump system. BACKGROUND

[0002] With the iteration of battery technology, electric vehicles are accelerating popularization, and the sales proportion has broken through year after year. The increase in the penetration rate is due to policy incentives and the improvement of charging infrastructure, and also cannot be separated from the continuous optimization of battery thermal management technology. The power battery is extremely sensitive to temperature: high temperature in summer easily causes electrolyte decomposition, SEI film thickening and even thermal runaway, and the industry generally adopts a compressor refrigeration system integrated with an electric drive heat dissipation system to realize efficient cooling through a low-temperature radiator; while low temperature in winter leads to a decrease in lithium ion activity and an increase in internal resistance, resulting in more than 30% attenuation of battery capacity and a sharp reduction in range, and low-temperature charging easily induces lithium dendrite risk, so the battery needs to be controlled at a constant temperature in the range of 15-25℃.

[0003] For low-temperature heating, the existing schemes each have shortcomings - the water PTC scheme has high heating energy consumption (power 5-8kW) and low energy efficiency ratio, which further exacerbates the range attenuation of the whole vehicle; the heating film scheme responds quickly but easily causes uneven battery cell temperature; the refrigerant direct heating scheme relies on a compressor, and the heating attenuation is extreme in extremely low temperature, and the existence of high-pressure refrigerant potentially threatens the safety of the cockpit; the battery high-frequency pulse self-heating has no external equipment, but it may accelerate battery aging. The current technology has not yet broken through the balance dilemma of energy efficiency, safety and cost. SUMMARY

[0004] In view of the above technical problems, the present application provides a battery thermal management mode switching method based on a hot gas bypass heat pump system.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: The present application provides a battery thermal management mode switching method based on a hot gas bypass heat pump system, according to system requirements and environmental modes, the battery thermal management mode includes: a battery thermal management off mode, a battery cooling mode, a battery self-circulation mode, a battery active heating mode and a battery passive heating mode, and an intermediate transition mode; The specific switching logic is as follows: The system is powered on by default, and enters the battery thermal management off mode; After the battery thermal management sends a switching request, the system enters the intermediate transition mode, waits for the request judgment of other modes, and then enters the corresponding mode, and further judges the conditions according to the environmental temperature, the battery pump flow request and the battery mode, and switches the thermal management mode in real time, which specifically includes: When the battery management system sends a refrigeration request, the battery cooling mode is entered; When the battery management system sends a non-thermal management request and the battery water pump flow request is not 0, the battery enters a battery self-circulation mode; When the battery management system sends a heating request, the battery enters an active battery heating mode, and the Heat sub-mode machine is activated; When the battery management system sends a non-thermal management request and the battery water pump flow request is 0, the battery enters a passive battery heating mode or a closed mode.

[0006] As a preferred, the battery cooling mode includes a battery LTR cooling mode and a battery Chiller cooling mode; when the battery management system sends a refrigeration request, the battery LTR cooling mode is preferentially determined, and if it is not satisfied, the battery Chiller cooling mode is entered.

[0007] As a preferred, the battery active heating mode includes an electric drive heating mode, a normal heat pump heating mode, and a hot gas bypass heating mode. When the battery management system sends a heating request, the active heating mode Heat sub-mode machine is entered, and the entering conditions of the electric drive heating mode, the normal heat pump heating mode, and the hot gas bypass heating mode are determined, and if they are satisfied, the corresponding mode is entered.

[0008] As a preferred, the electric drive heating mode includes two sub-modes of an active waste heat heating mode and an active locked-rotor heating mode.

[0009] As a preferred, when the battery management system sends a heating request and the ambient temperature is less than -10°C, the mode switching logic is as follows: In the order of the active locked-rotor heating mode, the hot gas bypass heating mode, and the active waste heat heating mode, whether the entering conditions are satisfied is determined in turn. When the battery is in the active locked-rotor heating mode and the hot gas bypass heating mode, the Heat sub-mode machine continuously sends an electric drive locked-rotor priority request, and whether the active locked-rotor heating mode can maintain the battery temperature is determined in real time, and if it cannot be maintained, the hot gas bypass heating mode is entered, and if it can be maintained, the active locked-rotor heating mode is entered; when both conditions are not satisfied, the entering condition of the active waste heat heating mode is determined, and if it is satisfied, the mode is entered.

[0010] As a preferred, in the hot gas bypass heating mode, the entering conditions of the active waste heat heating mode and the active locked-rotor heating mode are determined in turn, and if they are satisfied, the corresponding mode is entered.

[0011] As a preferred, in the active waste heat heating mode, the entering conditions of the active locked-rotor heating mode and the hot gas bypass heating mode are determined in turn, and if they are satisfied, the corresponding mode is entered.

[0012] As a preferred, when the battery management system sends a heating request, and the ambient temperature is greater than or equal to -10°C and the battery is fast-charged, the mode switching logic is as follows: In the order of priority of the active locked-rotor heating mode, the ordinary heat pump heating mode and the active waste heat heating mode, whether the entering condition is satisfied is judged in turn. When the active locked-rotor heating mode and the ordinary heat pump heating mode are in the two modes, the Heat sub-mode machine continuously sends an electric drive locked-rotor priority request, and whether the active locked-rotor heating mode can maintain the battery temperature is judged in real time, and if not, the ordinary heat pump heating mode is entered, and if yes, the active locked-rotor heating mode is entered. When both conditions are not met, the entering condition of the active waste heat heating mode is judged, and if met, the mode is entered.

[0013] As preferred, in the ordinary heat pump heating mode, the entering conditions of the active waste heat heating mode and the active locked-rotor heating are judged in turn, and if met, the corresponding mode is entered.

[0014] As preferred, in the active waste heat heating mode, the entering conditions of the active locked-rotor heating and the ordinary heat pump heating mode are judged in turn, and if met, the corresponding mode is entered.

[0015] As preferred, the battery management system sends a heating request, and when the ambient temperature is greater than or equal to -10℃ and the battery is not fast-charged, the mode switching logic is as follows: In the order of priority of the active waste heat heating mode, the ordinary heat pump heating mode and the active locked-rotor heating mode, whether the entering condition is satisfied is judged in turn.

[0016] As preferred, in the active waste heat heating mode, the entering conditions of the ordinary heat pump heating mode and the active locked-rotor heating mode are judged in turn, and if met, the corresponding mode is entered.

[0017] As preferred, in the ordinary heat pump heating mode, the entering conditions of the active waste heat heating mode and the active locked-rotor heating mode are judged in turn, and if met, the corresponding mode is entered.

[0018] As preferred, in the active locked-rotor heating mode, the entering conditions of the active waste heat heating mode and the active locked-rotor heating mode are judged in turn, and if met, the corresponding mode is entered.

[0019] As preferred, the battery passive heating mode includes a waste heat storage mode and a waste heat release mode; when there is no heating request and the battery water pump flow request is 0, in the order of priority of the waste heat storage mode and the waste heat release mode, whether the entering condition is satisfied is judged in turn, and if met, the corresponding mode is entered, and in each mode, whether the entering condition of another mode is satisfied is continuously judged, and if not, the closed mode is entered.

[0020] Compared with the prior art, the application provides a battery thermal management mode switching method based on a hot gas bypass heat pump system, which has the following beneficial effects: The application focuses on the cooperation of multiple heat sources such as electric drive waste heat recovery (on-the-go motor / inverter waste heat utilization), electric drive active locked rotor heating (parking directional excitation motor loss heat production), ordinary heat pump and heat gas bypass heat pump (improve heating efficiency at extremely low temperature), and real-time arbitration of the use of each heat source combined with the environment and vehicle parameters. In the case of active or passive heating of the battery, the battery temperature can always be kept in the appropriate range. This scheme cancels the traditional water PTC heater, and only needs to upgrade the water pump system water topology - through the water-cooled condenser (LCC) to indirectly introduce high-pressure refrigerant heat into the battery liquid cooling plate, which not only avoids the high-pressure pipe leakage risk of the direct heating scheme, but also eliminates the local overheating defect of the heating film scheme by using the inherent temperature equalization characteristics of water circulation, realizing the reduction of vehicle energy consumption and hardware cost. At the same time, the battery active refrigeration, passive refrigeration and self-circulation and other heat management modes are combined, and the battery all-around heat management demand is met, so that the battery temperature can be stabilized in the appropriate range.

[0021] The features and advantages of the present application will be described in detail with reference to the embodiments combined with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The battery heat management mode switching mode machine of the present application is shown in the figure; Figure 2 is a battery heat management mode switching Heat sub-mode machine schematic diagram (environmental temperature < -10℃) of the present application; Figure 3 is a battery heat management mode switching Heat sub-mode machine schematic diagram (environmental temperature ≥ -10℃ and battery in fast charging mode) of the present application; Figure 4 is a battery heat management mode switching Heat sub-mode machine schematic diagram (environmental temperature ≥ -10℃ and battery not in fast charging mode) of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application will be further described in detail by means of drawings and examples. However, it should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0024] Referring to Figures 1-4 A battery heat management mode switching method based on a heat gas bypass heat pump system, according to system requirements and environmental modes, the battery heat management mode includes: battery heat management off mode, battery cooling mode, battery self-circulation mode, battery active heating mode and battery passive heating mode, and intermediate transition mode; The specific switching logic is as follows: The system is powered on by default, and enters the battery heat management off mode; After the battery thermal management sends the switching request, the system enters an intermediate transition mode, waits for the request judgment of other modes, and then enters the corresponding mode. Further, the system makes a conditional judgment according to the environmental temperature, the battery water pump flow request and the battery mode, and switches the thermal management mode in real time. Specifically, the following steps are included: When the battery management system sends a refrigeration request, the battery cooling mode is entered; When the battery management system sends a no-thermal management request and the battery water pump flow request is not 0, the battery self-circulation mode is entered; When the battery management system sends a heating request, the battery active heating mode is entered, and the Heat sub-mode machine is activated; When the battery management system sends a no-thermal management request and the battery water pump flow request is 0, the battery passive heating mode or the closed mode is entered.

[0025] In a specific embodiment, the present application defines the following battery thermal management mode BtmSysMd according to the system requirements and the different environmental modes, so as to drive the corresponding actuators to perform different actions and achieve the correct battery thermal management mode. The battery thermal management mode BtmSysMd is as follows: BtmSysMd = 0 (Md0_Off), representing the battery thermal management closed mode, that is, the battery management system (BMS) sends a no-battery thermal management request (BMS_ThermMngReq = No Request) and the battery water pump flow request is 0; BtmSysMd = 1 (Md1_ChlrCl), representing the battery Chiller cooling mode, that is, the cold quantity is transferred through the battery plate heat exchanger (Chiller) by using the compressor refrigeration to achieve the battery cooling; BtmSysMd = 2 (Md2_LtrCl), representing the battery LTR cooling mode, that is, the battery water circuit and the electric drive circuit are connected in series through the multi-way valve, and the battery cooling is achieved through the low-temperature radiator (LTR) of the front-end cooling module; BtmSysMd = 3 (Md3_SlfLp), representing the battery self-circulation mode, that is, the battery circuit is kept independent, and the uniformity of the battery temperature is maintained through the operation of the battery water pump; BtmSysMd = 4 (Md4_HpHt), representing the ordinary heat pump heating mode, that is, the ordinary heat pump system is used to achieve the battery active heating above-10℃; BtmSysMd = 5 (Md5_MotHt), representing the electric drive heating mode, that is, the battery active heating is achieved by using the waste heat or the locked-rotor heat of the electric drive system; BtmSysMd = 6 (Md6_HtRec), representing a waste heat heating mode, i.e., using the waste heat of the electric drive system to realize passive heating of the battery; BtmSysMd = 7 (Md7_HtRecStrg), representing a waste heat storage mode, i.e., in order to realize passive heating of the battery, the heat of the electric drive system is pre-collected and stored; BtmSysMd = 8 (Md8_ThermalRunaway), representing a battery thermal runaway mode, i.e., the BMS sends a battery thermal runaway, and the battery water pump works at the maximum speed to quickly reduce the heat of the battery; BtmSysMd = 9 (Md9_SVIHt), representing a hot gas bypass heating mode, i.e., using the hot gas bypass principle to realize active heating of the battery at an extremely low temperature below -10°C.

[0026] In particular, in order to facilitate the switching of each mode in the control algorithm, an intermediate transition mode ST is added, in which mode no battery thermal management mode is output, and only serves as an intermediate transition mode for switching between different battery thermal management modes.

[0027] Further explanation is that: for the off mode Md0_Off, when the vehicle is powered on, the battery thermal management system will enter the off mode Md0_Off by default, when the (ST→Md0_Off) condition is not met, the battery thermal management system will enter the ST mode, and then the battery thermal management mode is judged in real time according to the system demand and the environment mode, and the mode switching is carried out; when the (ST→Md0_Off) condition is met while in the ST mode, the battery thermal management system reenters the off mode Md0_Off.

[0028] Specifically, the battery cooling mode includes a battery LTR cooling mode and a battery Chiller cooling mode; when the battery management system sends a refrigeration request, the battery LTR cooling mode is preferentially judged, and if not met, the battery Chiller cooling mode is entered.

[0029] Further explanation is that: in the ST mode, if the BMS sends a battery thermal management request (BMS_ThermMngReq = No Request) and the battery water pump flow request is not equal to 0, i.e., the battery self-circulation condition (Cond_SlfLp) is met, the battery thermal management system will enter the battery self-circulation mode Md3_SlfLp.

[0030] In the battery self-circulation mode Md3_SlfLp, if the battery self-circulation condition (Cond_SlfLp) is not met, the battery thermal management system will enter the ST mode and enter the corresponding mode after waiting for the judgment of other modes.

[0031] Further, in the ST mode, if the BMS sends a battery cooling request (BMS_ThermMngReq = Cooling Request), the mode opportunity determines whether the battery LTR cooling condition (Cond_ECL) is met. If the condition is met, the battery thermal management system enters the battery LTR cooling mode Md2_LtrCl. If the condition is not met, the battery thermal management system enters the battery chiller cooling mode Md1_ChlrCl.

[0032] In the battery LTR cooling mode Md2_LtrCl, if the battery LTR cooling condition (Cond_ECL) is not met, the battery thermal management system enters the battery chiller cooling mode Md1_ChlrCl.

[0033] In the battery chiller cooling mode Md1_ChlrCl, if the battery LTR cooling condition (Cond_ECL) is met, the battery thermal management system enters the battery LTR cooling mode Md2_LtrCl.

[0034] In either the battery LTR cooling mode Md2_LtrCl or the battery chiller cooling mode Md1_ChlrCl, if the BMS does not send a battery cooling request (BMS_ThermMngReq ≠ Cooling Request), the battery thermal management system enters the ST mode and waits for the determination of other modes to enter the corresponding mode.

[0035] Specifically, the battery active heating mode includes a motor-driven heating mode Md5_MotHt, a normal heat pump heating mode Md4_HpHt, and a hot gas bypass heating mode Md9_SVIHt. When the battery management system sends a heating request, it enters the active heating mode Heat sub-mode machine, determines the entry conditions of the motor-driven heating mode Md5_MotHt, the normal heat pump heating mode Md4_HpHt, and the hot gas bypass heating mode Md9_SVIHt, and enters the corresponding mode if the conditions are met. In different ambient temperatures and charging modes, different mode switching logic is executed, i.e., the Heat sub-mode opportunity is divided into Figures 2-4 The three cases are shown, and the specific switching logic is described below.

[0036] Specifically, for the electric drive heating mode Md5_MotHt, in the Heat sub-mode machine, whether to send an electric drive stall priority request ReqMotSlfHt from inside the mode machine to the outside (i.e., send the request from the mode machine to the electric drive controller MCU, and when the request is 1, it means that the MCU needs to perform electric drive stall) is distinguished into two sub-modes: active waste heat heating Md5_MotHt_Rec and active stall heating Md5_MotHt_Slf.

[0037] Specifically, the battery management system sends a heating request, and when the ambient temperature is <-10°C, the mode switching logic is as follows: In the order of priority of the active stall heating mode Md5_MotHt_Slf, the hot gas bypass heating mode Md9_SVIHt, and the active waste heat heating Md5_MotHt_Rec, whether the entering conditions are met is determined in turn. Among them, when in the active stall heating mode Md5_MotHt_Slf and the hot gas bypass heating mode Md9_SVIHt, the Heat sub-mode machine continuously sends the electric drive stall priority request ReqMotSlfHt, and whether the active stall heating mode Md5_MotHt_Slf can maintain the battery temperature is determined in real time. If it cannot be maintained, it enters the hot gas bypass heating mode Md9_SVIHt, and if it can be maintained, it enters the active stall heating mode Md5_MotHt_Slf. When neither condition is met, the entering condition of the active waste heat heating Md5_MotHt_Rec is determined, and if it is met, it enters the mode.

[0038] Further, in the active mot heat slf mode Md5_MotHt_Slf, the mode machine continuously sends the mot slf ht request ReqMotSlfHt to the MCU controller, hoping that the MCU controller controls the motor to be stalled to achieve the purpose of maintaining the battery in the appropriate temperature range by using mot stall heat. However, the MCU may not be able to mobilize the motor to be stalled, at which time mot stall heat cannot be provided to the battery. Therefore, in this mode, the mode machine will first determine whether the condition for entering the hot gas bypass heating mode from the active mot heat slf mode (Md5_MotHt_Slf→Md9_SVIHt) is met, and if so, the battery thermal management system will enter the hot gas bypass heating mode Md9_SVIHt, in which the battery will be maintained in the appropriate temperature range by using the heat generated by the hot gas bypass heat pump. However, in this mode, the mode machine will still continuously send the mot slf ht request ReqMotSlfHt to the MCU controller, because the hot gas bypass heating mode is not as efficient as the active mot heat slf mode, and therefore the MCU is still expected to mobilize the motor to be stalled. When the motor is actually stalled, the mode machine will jump back to the active mot heat slf mode Md5_MotHt_Slf. If the condition for entering the hot gas bypass heating mode is not met, the mode machine will determine whether the condition for entering the active mot heat rec mode from the active mot heat slf mode (Md5_MotHt_Slf→Md5_MotHt_Rec) is met, and if so, the battery thermal management system will enter the active mot heat rec mode Md5_MotHt_Rec. However, in this mode, the mode machine will no longer send the mot slf ht request ReqMotSlfHt to the MCU controller, because the electric drive circuit already has enough heat to heat the battery, and the battery will be maintained in the appropriate temperature range by using the electric drive waste heat.

[0039] Specifically, in the hot gas bypass heating mode Md9_SVIHt, the entering conditions of the active mot heat rec mode Md5_MotHt_Rec and the active mot heat slf mode Md5_MotHt_Slf are sequentially determined, and if the entering condition of a corresponding mode is met, the battery thermal management system will enter the corresponding mode.

[0040] Specifically, in the active mot heat rec mode Md5_MotHt_Rec, the entering conditions of the active mot heat slf mode Md5_MotHt_Slf and the hot gas bypass heating mode Md9_SVIHt are sequentially determined, and if the entering condition of a corresponding mode is met, the battery thermal management system will enter the corresponding mode.

[0041] Specifically, the battery management system sends a heating request, and when the ambient temperature ≥ -10℃ and the battery is fast charging, the mode switching logic is as follows: In the order of priority of the active mot heat slf mode Md5_MotHt_Slf, the ordinary heat pump heating mode Md4_HpHt, and the active mot heat rec mode Md5_MotHt_Rec, the entering conditions are sequentially determined. When in the active mot heat self mode Md5_MotHt_Slf and the ordinary heat pump heating mode Md4_HpHt, the heat sub-mode machine continuously sends the electric drive mot heat self request ReqMotSlfHt, and the active mot heat self mode Md5_MotHt_Slf is determined in real time whether the battery temperature can be maintained, if not, the ordinary heat pump heating mode Md4_HpHt is entered, if yes, the active mot heat self mode Md5_MotHt_Slf is entered; when both conditions are not met, the entering condition of the active mot heat recycle Md5_MotHt_Rec is determined, if met, the mode is entered.

[0042] Further, in the active mot heat self mode Md5_MotHt_Slf, the mode machine continuously sends the electric drive mot heat self request ReqMotSlfHt to the MCU controller, and the battery will be maintained in the appropriate temperature range by using the electric drive mot heat. In this mode, the condition of entering the ordinary heat pump heating mode from the active mot heat self mode (Md5_MotHt_Slf→Md4_HpHt) is determined first, if met, the battery thermal management system enters the ordinary heat pump heating mode Md4_HpHt, and the mode machine continuously sends the electric drive mot heat self request ReqMotSlfHt to the MCU controller, and the battery will be maintained in the appropriate temperature range by using the heat generated by the ordinary heat pump; if not met, the condition of entering the active mot heat recycle mode from the active mot heat self mode (Md5_MotHt_Slf→Md5_MotHt_Rec) is determined, if met, the battery thermal management system enters the active mot heat recycle mode Md5_MotHt_Rec, but the mode machine no longer sends the electric drive mot heat self request ReqMotSlfHt to the MCU controller, and the battery will be maintained in the appropriate temperature range by using the electric drive mot heat.

[0043] Specifically, in the ordinary heat pump heating mode Md4_HpHt, the entering conditions of the active mot heat recycle mode Md5_MotHt_Rec and the active mot heat self mode Md5_MotHt_Slf are determined in turn, if met, the corresponding mode is entered.

[0044] Specifically, in the active mot heat recycle mode Md5_MotHt_Rec, the entering conditions of the active mot heat self mode Md5_MotHt_Slf and the ordinary heat pump heating mode Md4_HpHt are determined in turn, if met, the corresponding mode is entered.

[0045] Specifically, the battery management system sends a heating request, when the ambient temperature ≥ -10℃ and the battery is not fast charging, the mode switching logic is as follows: The priority order of the active residual heat heating mode Md5_MotHt_Rec, the ordinary heat pump heating mode Md4_HpHt, and the active locked-rotor heating mode Md5_MotHt_Slf is determined in sequence to determine whether the entering condition is met.

[0046] It is further explained that: after entering the active residual heat heating mode Md5_MotHt_Rec, the mode machine no longer sends the electric drive locked-rotor priority request ReqMotSlfHt to the MCU controller, at this time the battery will be maintained in the appropriate temperature interval by using the electric drive residual heat; if not, it is determined whether the entering condition of the ordinary heat pump heating mode (→Md4_HpHt) is met, if met, the battery thermal management system will enter the ordinary heat pump heating mode Md4_HpHt, but the mode machine no longer sends the electric drive locked-rotor priority request ReqMotSlfHt to the MCU controller, at this time the battery will be maintained in the appropriate temperature interval by using the heat generated by the ordinary heat pump; if not, the battery thermal management system will enter the active locked-rotor heating mode Md5_MotHt_Slf, and the mode machine will continue to send the electric drive locked-rotor priority request ReqMotSlfHt to the MCU controller, at this time the battery will be maintained in the appropriate temperature interval by using the electric drive locked-rotor heat generation.

[0047] Specifically, in the active residual heat heating mode Md5_MotHt_Rec, the entering conditions of the ordinary heat pump heating mode Md4_HpHt and the active locked-rotor heating mode Md5_MotHt_Slf are determined in sequence, and if met, the corresponding mode is entered.

[0048] Specifically, in the ordinary heat pump heating mode Md4_HpHt, the entering conditions of the active residual heat heating mode Md5_MotHt_Rec and the active locked-rotor heating mode Md5_MotHt_Slf are determined in sequence, and if met, the corresponding mode is entered.

[0049] Specifically, in the active locked-rotor heating mode Md5_MotHt_Slf, the entering conditions of the active residual heat heating mode Md5_MotHt_Rec and the active locked-rotor heating mode Md5_MotHt_Slf are determined in sequence, and if met, the corresponding mode is entered.

[0050] It needs to be further explained that: no matter in any mode in the Heat sub-mode machine, if the BMS does not send the battery heating request (BMS_ThermMngReq ≠ Heating Request), the battery thermal management system will enter the ST mode and enter the corresponding mode after the determination of other modes.

[0051] In particular, if the passenger cabin heating performance is high, the following logic can be added based on the above logic: when the air conditioner uses a normal heat pump or a supplementary air enthalpy heat pump to heat the passenger cabin, the battery thermal management is prohibited from entering the hot gas bypass heating mode Md9_SVIHt.

[0052] Specifically, when there is no heating request and the battery water pump flow request is 0, the priority order of the waste heat storage mode Md7_HtRecStrg and the waste heat release mode Md6_HtRecc is determined in sequence to determine whether the entering condition is met; and in each mode, it is continuously determined whether the entering another mode condition is met.

[0053] It should be further pointed out that when the battery management system sends a no-thermal management request and the battery water pump flow request is 0, the mode machine still comprehensively determines the satisfaction of the current system water temperature and other conditions, and still hopes to use the electric drive waste heat to keep the battery in a constant suitable temperature interval to improve the battery energy efficiency, because the electric drive waste heat is not wasted at this time, and if the battery does not use it, the electric drive system will also discharge this part of the heat to the atmosphere, causing energy waste. In the waste heat storage mode Md7_HtRecStrg, the electric drive system stores the generated waste heat. In the waste heat release mode Md6_HtRecc, the electric drive system discharges the stored electric drive waste heat to the battery to achieve passive heating of the battery.

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for switching battery thermal management modes based on a hot gas bypass heat pump system, characterized in that: Depending on system requirements and environmental conditions, battery thermal management modes include: battery thermal management off mode, battery cooling mode, battery self-circulation mode, battery active heating mode, battery passive heating mode, and intermediate transition mode. The specific switching logic is as follows: When the system is powered on, it enters battery thermal management off mode by default. After the battery thermal management system sends a switching request, it enters an intermediate transition mode, waiting for requests from other states to be processed before entering the corresponding state. Further, it performs conditional checks based on ambient temperature, battery water pump flow rate requests, and battery status to switch the thermal management mode in real time. Specifically, this includes: When the battery management system sends a cooling request, it enters battery cooling mode; When the battery management system sends a request for no thermal management and a request for battery water pump flow rate that is not zero, it enters the battery self-circulation state. When the battery management system sends a heating request, it enters the active battery heating mode and activates the Heat sub-state machine; When the battery management system sends a no-thermal-management request and a battery water pump flow request of 0, it enters the battery passive heating mode or the off mode.

2. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 1, characterized in that: The battery cooling modes include battery LTR cooling mode and battery Chiller cooling mode; When the battery management system sends a cooling request, it first determines the entry conditions for the battery LTR cooling mode. If the conditions are not met, it enters the battery Chiller cooling mode.

3. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 1, characterized in that: The active battery heating modes include electric drive heating mode, ordinary heat pump heating mode, and hot gas bypass heating mode. When the battery management system sends a heating request, it enters the active heating mode Heat sub-state machine to determine the entry conditions for electric drive heating mode, ordinary heat pump heating mode, and hot gas bypass heating mode. If the conditions are met, it enters the corresponding state.

4. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 3, characterized in that: The electric drive heating mode includes two sub-states: active waste heat heating mode and active stall heating mode.

5. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 4, characterized in that: The battery management system sends a heating request, and when the ambient temperature is < -10℃, the state switching logic is as follows: The entry conditions are determined sequentially based on the priority order of active stall heating mode, hot gas bypass heating mode, and active waste heat heating mode. When the device is in either the active stall heating mode or the hot gas bypass heating mode, the Heat sub-state machine continuously sends electric drive stall priority requests and determines in real time whether the active stall heating mode can maintain the battery temperature. If it cannot maintain the temperature, it enters the hot gas bypass heating mode; if it can maintain the temperature, it enters the active stall heating mode. When neither condition is met, it determines the entry condition for the active waste heat heating mode. If the condition is met, it enters that mode.

6. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 5, characterized in that: In the hot gas bypass heating state, the entry conditions for active waste heat heating mode and active stall heating mode are judged in sequence, and the corresponding state is entered if the conditions are met.

7. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 5, characterized in that: In active waste heat heating mode, the entry conditions for active stall heating mode and hot gas bypass heating state are judged in sequence, and the corresponding state is entered if the conditions are met.

8. A battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 4, characterized in that: The battery management system sends a heating request. When the ambient temperature is ≥ -10℃ and the battery is fast charging, the state switching logic is as follows: The entry conditions are determined sequentially based on the priority order of active stall heating mode, ordinary heat pump heating mode, and active waste heat heating mode. When in both active stall heating mode and normal heat pump heating mode, the Heat sub-state machine continuously sends electric drive stall priority requests and determines in real time whether the active stall heating mode can maintain the battery temperature. If it cannot, it enters the normal heat pump heating mode; if it can, it enters the active stall heating mode. When neither condition is met, it determines the entry condition for the active waste heat heating mode. If the condition is met, it enters that state.

9. A battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 8, characterized in that: In the normal heat pump heating mode, the entry conditions for active waste heat heating mode and active stall heating are judged in sequence, and the corresponding state is entered if the conditions are met.

10. A battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 8, characterized in that: In the active waste heat heating mode, the entry conditions for active stall heating and ordinary heat pump heating modes are judged in sequence, and the corresponding state is entered if the conditions are met.

11. A battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 4, characterized in that: When the battery management system sends a heating request, and the ambient temperature is ≥ -10℃ and the battery is not fast charging, the state switching logic is as follows: The entry conditions are determined sequentially based on the priority order of active waste heat heating mode, ordinary heat pump heating mode, and active stall heating mode.

12. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 11, characterized in that: In active waste heat heating mode, the entry conditions for ordinary heat pump heating mode and active stall heating mode are judged in turn. If the conditions are met, the corresponding state is entered.

13. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 11, characterized in that: In the normal heat pump heating mode, the entry conditions for active waste heat heating mode and active stall heating mode are judged in sequence, and the corresponding state is entered if the conditions are met.

14. The battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 11, characterized in that: In the active stall heating mode, the entry conditions for the active waste heat heating mode and the active stall heating mode are determined sequentially. If the conditions are met, the corresponding state is entered.

15. A battery thermal management mode switching method based on a hot gas bypass heat pump system as described in claim 1, characterized in that: The passive heating modes of the battery include waste heat storage mode and waste heat release mode; When there is no heating request and the battery water pump flow request is 0, The system prioritizes waste heat storage mode and waste heat release mode, and checks whether the entry conditions are met in turn. If the conditions are met, the system enters the corresponding mode. In each state, the system continuously checks whether the conditions for entering another state are met. If the conditions are not met, the system enters the shutdown mode.

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