Heating method and heating system for vehicle battery

Abstract

The invention provides a heating method and system for a vehicle battery. The heating method comprises the steps that a vehicle control unit determines whether the battery meets a preset heating condition or not; if the vehicle control unit determines that the battery meets the preset heating condition, a heating on-off request of a switch in a switching circuit of the inverter is generated, and a heating strategy of the battery is generated based on the state parameters of the battery; the BMS responds to the heating on-off request and controls on-off of a switch in a switching circuit; and the inverter controller controls on and off of an MOS tube in a three-phase full-bridge inverter circuit of the inverter based on a heating strategy, so that a motor winding circuit of the driving motor releases energy to heat a battery. By adopting the technical scheme provided by the invention, the heating efficiency of the battery is enhanced, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a heating method and a heating system for a vehicle battery. BACKGROUND

[0002] With the wide application of lithium ion batteries in various fields, people have higher requirements for their energy density and safety. All-solid-state batteries have high safety and high weight / volume energy density, and are an important direction for the development of power batteries. However, the performance of all-solid-state batteries in low-temperature environments is still a key bottleneck restricting their in-depth development and wide application. Current battery heating technologies mainly include external heating and internal heating. External heating adopts conduction heating (such as heating film, phase change material, PTC heating, etc.) and convection heating (such as air heating and liquid heating, etc.) methods; internal heating is to realize self-heating by using Joule effect through the flow of current in the battery.

[0003] However, the external heating method has certain heat loss in the heat transfer process, resulting in low heating efficiency, which is difficult to meet the demand for rapid heating of the battery; at the same time, the external heating also needs to install additional heating elements, which not only occupies the space of the battery, but also reduces the cruising range of the vehicle, increases the production cost. The internal heating method does not need additional heating elements, but due to the poor electrical performance of the battery at low temperature, the current is small, resulting in low heating efficiency; at the same time, as a new technology, the internal performance of the all-solid-state battery is significantly different from that of the traditional liquid battery, and the existing internal heating technology is not mature, which is difficult to be directly applied to the all-solid-state battery. SUMMARY

[0004] Therefore, the embodiments of the present application provide a heating method and a heating system for a vehicle battery, which optimize the inverter circuit, increase the pulse frequency output by the driving motor, enhance the heating efficiency of the battery, and reduce the cost.

[0005] The present application mainly includes the following aspects: In a first aspect, the embodiments of the present application provide a heating method for a vehicle battery, which is applied to a heating system for a vehicle battery; the heating system comprises a vehicle controller, a BMS, an inverter controller, an inverter and a driving motor; the heating method comprises: The vehicle controller determines whether the battery meets a preset heating condition; if the vehicle controller determines that the battery meets the preset heating condition, it generates a heating on-off request for the switch in the switching circuit of the inverter, and generates a heating strategy for the battery based on the state parameters of the battery; The BMS controls the switch in the switching circuit to be on or off in response to the heating on-off request; The inverter controller controls the on-off of the MOS tubes in the three-phase full-bridge inverter circuit of the inverter based on the heating strategy, so that the motor winding circuit of the driving motor releases energy to heat the battery.

[0006] Preferably, the switching circuit comprises a first switch, a second switch and a third switch; the BMS controls the on-off of the switches in the switching circuit in response to the heating on-off request, comprising: The BMS controls the closing of the first switch and the third switch and the opening of the second switch in response to the heating on-off request.

[0007] Preferably, the heating method further comprises: The vehicle controller generates a non-heating on-off request of the switches in the switching circuit if it is determined that the battery does not meet the preset heating condition; The BMS controls the opening of the first switch and the third switch and the closing of the second switch in response to the non-heating on-off request.

[0008] Preferably, the circuit of the inverter further comprises a direct current side filtering circuit and a protection circuit; the three-phase full-bridge inverter circuit comprises upper bridge arm MOS tubes and lower bridge arm MOS tubes; Wherein, one end of the motor winding circuit is connected with the source level of the upper bridge arm MOS tube and the drain of the lower bridge arm MOS tube respectively, the other end of the motor winding circuit is connected with one end of the first switch, the other end of the first switch is connected with one end of the second switch and one end of the protection circuit respectively, the other end of the protection circuit is connected with the positive electrode of the battery, the negative electrode of the battery is connected with one end of the third switch, the other end of the third switch is connected with the source level of the lower bridge arm MOS tube and one end of the direct current side filtering circuit respectively, the other end of the second switch is connected with the drain of the upper bridge arm MOS tube and the other end of the direct current side filtering circuit respectively; The inverter controller controls the on-off of the MOS tubes in the three-phase full-bridge inverter circuit of the inverter based on the heating strategy, so that the motor winding circuit of the driving motor releases energy to heat the battery, comprising: (A) The inverter controller generates the bridge arm driving signal corresponding to the three-phase full-bridge inverter circuit based on the heating strategy; (B) Based on the bridge arm driving signal, the upper bridge arm MOS tube and the lower bridge arm MOS tube are controlled to be alternately turned on, so that the motor winding circuit and the direct current side filtering circuit form a resonance loop to discharge to heat the battery.

[0009] Preferably, the inverter controller controls the upper bridge arm MOS tube and the lower bridge arm MOS tube to be turned on alternately based on the bridge arm drive signal, so that the motor winding circuit and the DC side filter circuit form a resonance loop to discharge to heat the battery, comprising: (a) The inverter controller controls the lower bridge arm MOS tube to be turned on continuously and the upper bridge arm MOS tube to be turned off continuously within a first preset time based on the bridge arm drive signal, so that the battery current flows through the motor winding circuit to charge; (b) The inverter controller controls the lower bridge arm MOS tube to be turned off continuously and the upper bridge arm MOS tube to be turned on continuously within a second preset time, so that the motor winding circuit and the DC side filter circuit form a resonance loop to discharge to heat the battery; (c) The inverter controller controls the battery output to be reversed, and controls the lower bridge arm MOS tube to be turned off continuously and the upper bridge arm MOS tube to be turned on continuously within a third preset time, so that the battery reversed current flows through the motor winding circuit to charge again; (d) The inverter controller controls the lower bridge arm MOS tube to be turned on continuously and the upper bridge arm MOS tube to be turned off continuously within a fourth preset time, so that the remaining energy in the motor winding circuit is recovered to the battery; (e) Determine whether the battery temperature reaches the target temperature interval; (f) If the battery temperature reaches the target temperature interval, stop heating the battery; (g) If the battery temperature does not reach the target temperature interval and the current pulse current amplitude of the battery is greater than the pulse current amplitude in the heating strategy, update the bridge arm drive signal based on the current pulse current amplitude of the battery, and return to step (a).

[0010] Preferably, the heating method of the vehicle battery further comprises: The vehicle controller re-generates the heating strategy when it is determined that the battery meets the strategy adjustment condition during the battery heating process, and returns to step (A).

[0011] Preferably, the motor winding circuit comprises a first inductor, a second inductor and a third inductor; the upper bridge arm MOS tube comprises a first MOS tube, a second MOS tube and a third MOS tube; the upper bridge arm comprises a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; Wherein, one end of the first inductor is connected with the source of the first MOS tube and the drain of the fourth MOS tube respectively, one end of the second inductor is connected with the source of the second MOS tube and the drain of the fifth MOS tube respectively, and one end of the third inductor is connected with the source of the third MOS tube and the drain of the sixth MOS tube respectively.

[0012] Preferably, one end of the first switch is connected to the other end of the first inductor, the other end of the second inductor and the other end of the third inductor, respectively.

[0013] In a second aspect, the embodiments of the present application further provide a heating system for a vehicle battery, comprising: a vehicle controller, a BMS, an inverter controller, an inverter and a drive motor. The vehicle controller determines whether the battery meets a preset heating condition; if the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request for a switch in a switch circuit of the inverter, and generates a heating strategy for the battery based on a state parameter of the battery. The BMS controls the switch in the switch circuit to be on or off in response to the heating on-off request. The inverter controller controls MOS tubes in a three-phase full-bridge inverter circuit of the inverter to be on or off based on the heating strategy, so that the motor winding circuit of the drive motor releases energy to heat the battery.

[0014] Preferably, the switch circuit comprises: a first switch, a second switch and a third switch. The BMS controls the first switch and the third switch to be closed and controls the second switch to be opened in response to the heating on-off request.

[0015] The embodiments of the present application provide a heating method and a heating system for a vehicle battery. The vehicle controller determines whether the battery meets a preset heating condition; if the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request for a switch in a switch circuit of the inverter, and generates a heating strategy for the battery based on a state parameter of the battery. The BMS controls the switch in the switch circuit to be on or off in response to the heating on-off request. The inverter controller controls MOS tubes in a three-phase full-bridge inverter circuit of the inverter to be on or off based on the heating strategy, so that the motor winding circuit of the drive motor releases energy to heat the battery.

[0016] In this way, the heating efficiency of the battery is enhanced, and the cost is reduced.

[0017] In order to make the above objectives, features and advantages of the present application more apparent, clear and easy to understand, the following will specifically describe the preferred embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. Other related drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 A flow chart of a method for heating a vehicle battery is shown according to an embodiment of the present application. Figure 2 A schematic diagram of a heating system for a vehicle battery is shown according to an embodiment of the present application. Figure 3 A circuit schematic diagram of an inverter and a driving motor is shown according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of description and illustration, and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn according to the actual proportions. The flow charts show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flow charts can not be implemented in sequence, and the steps without logical context relationship can be reversed in sequence or implemented simultaneously. In addition, one or more other operations can be added to the flow charts or one or more operations can be removed from the flow charts under the guidance of the content of the present application by those skilled in the art.

[0021] In addition, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] The method, device, electronic equipment or computer readable storage medium according to the embodiments of the present application can be applied to any scene requiring heating of a vehicle battery, and the embodiments of the present application do not limit the specific application scene. Any solution using the vehicle battery heating method and device provided by the embodiments of the present application is within the scope of protection of the present application.

[0023] It is worth noting that as lithium-ion batteries are widely used in various fields, higher requirements for their energy density and safety are put forward. All-solid-state batteries have high safety and high weight / volume energy density, and are an important direction for the development of power batteries. However, the performance of all-solid-state batteries in low-temperature environments is still a key bottleneck restricting their in-depth development and wide application. Current battery heating technologies mainly include external heating and internal heating. External heating adopts conduction heating (such as heating film, phase change material, PTC heating, etc.) and convection heating (such as air heating and liquid heating, etc.) methods; internal heating is to realize self-heating by using Joule effect through the flow of current in the battery. However, the external heating method has certain heat loss in the heat transfer process, resulting in low heating efficiency, which is difficult to meet the demand of fast heating of the battery; at the same time, external heating also needs to install additional heating elements, which not only occupies the space of the battery, but also reduces the cruising range of the vehicle, increases the production cost. The internal heating method does not need additional heating elements, but due to the poor electrical performance of the battery at low temperature, the current is small, resulting in low heating efficiency; at the same time, as an emerging technology, the internal performance of all-solid-state batteries is significantly different from that of traditional liquid batteries, and the existing internal heating technology is not mature, which is difficult to be directly applied to all-solid-state batteries.

[0024] In view of the above problems, the embodiment of the present application provides a heating method and a heating system for a vehicle battery. By optimizing the inverter circuit, the pulse frequency output by the driving motor is improved, the heating efficiency of the battery is enhanced, and the cost is reduced.

[0025] In order to facilitate the understanding of the present application, the technical solutions provided by the present application will be described in detail below in combination with specific embodiments.

[0026] Please refer to Figure 1 , Figure 1 The heating method for a vehicle battery provided by the embodiment of the present application is shown in the flow chart.

[0027] As shown in Figure 1 The heating method for a vehicle battery provided by the embodiment of the present application is shown in the flow chart. Figure 2 The heating method for a vehicle battery provided by the embodiment of the present application is shown in the flow chart. Step S101, the vehicle controller determines whether the battery meets the preset heating condition.

[0028] Here, the preset heating condition of the battery is used to determine whether the battery can be heated. As an example, the preset heating condition can be that the battery temperature is greater than the heating threshold and / or the battery state of charge (SOC) is in a safe range, etc.

[0029] Here, the heating system can further include a human-machine interaction system. The vehicle controller receives a start instruction for triggering the battery pulse heating mode from the human-machine interaction system, and generates a battery state request for obtaining battery state parameters in response to the start instruction. The BMS obtains the battery state parameters in response to the battery state request and sends the battery state parameters to the vehicle controller. The vehicle controller determines whether the battery meets the preset heating condition. The start instruction includes heating parameters such as heating duration and target temperature range. The human-machine interaction system generates the start instruction in response to the heating instruction input by the user, and sends the start instruction to the vehicle controller in the vehicle control system to trigger the heating system of the vehicle battery to start the pulse heating working mode. Through the human-machine interaction interface, the heating parameters of the battery can be transmitted in real time, so as to realize accurate control of the battery temperature.

[0030] In step S102, if the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request of the switch in the switching circuit of the inverter, and generates a heating strategy of the battery based on the state parameters of the battery.

[0031] Here, the battery state parameters include battery temperature, SOC, and battery maximum allowable current (Imax).

[0032] In the embodiments of the present application, the heating strategy includes three pulse control parameters: pulse frequency, pulse duty cycle, and pulse current amplitude. The pulse frequency is the number of pulse cycles per unit time, which affects the uniformity of battery heating and device switching loss. The pulse duty cycle is the ratio of MOS tube conduction time in a cycle, which affects the average heating power and temperature rise rate of the battery. The pulse current amplitude is the peak value of the pulse, which affects the instantaneous current of the battery. The vehicle controller has a built-in heating strategy mapping table or a pre-trained heating model. The battery state parameters are mapped to the corresponding heating strategy through the heating strategy mapping table, or input to the heating model to obtain the heating strategy output by the heating model, so as to obtain the optimal pulse control parameters. As an example, in the case of obtaining battery parameters of battery temperature-5℃, SOC 25%, and Imax reduced to 60A due to low temperature, the strategy is adopted to cope with the extremely low temperature and low power state. The priority is to heat quickly and safely, while considering the limitation of low SOC and Imax upper limit. Therefore, a medium frequency of 1KHz is selected for uniform heating, and a medium pulse duty cycle of 50% is set to provide higher average power without exceeding the Imax limit of 60A. At the same time, the pulse current amplitude is set to 50A to ensure that it is close to but does not exceed the maximum current limit within the safe range. Based on these settings, the heating strategy is generated: the pulse frequency is 1KHz, the pulse duty cycle is 50%, and the pulse current amplitude is 50A.

[0033] In step S103, the BMS responds to the heating on / off request by controlling the switch in the switching circuit to turn on or off.

[0034] In this embodiment, if the vehicle controller determines that the battery meets the preset heating conditions, it generates a heating on / off request for the switches in the inverter's switching circuit. In response to the heating on / off request, the BMS controls the first switch K1 and the third switch K3 to close, and controls the second switch K2 to open. If the vehicle controller determines that the battery does not meet the preset heating conditions, it generates a non-heating on / off request for the switches in the switching circuit. In response to the non-heating on / off request, the BMS controls the first switch K1 and the third switch K3 to open, and controls the second switch K2 to close, and the heating system stops the battery heating process.

[0035] In step S104, the inverter controller controls the MOS transistors in the three-phase full-bridge inverter circuit of the inverter to switch on and off based on the heating strategy, so that the motor winding circuit of the drive motor releases energy to heat the battery.

[0036] like Figure 3 In the diagram, E represents the battery. The switching circuit includes: a first switch K1, a second switch K2, and a third switch K3. The inverter circuit also includes: a DC-side filter circuit and a protection circuit. The DC-side filter circuit includes: a capacitor C, which is the DC bus capacitor and has filtering and energy storage functions. By suppressing DC-side voltage fluctuations, it provides a stable DC voltage for the circuit. Here, the voltage of the bus capacitor C can be regulated by adjusting the pulse duty cycle. The protection circuit includes: a resistor R, which is used for current-limiting protection. The three-phase full-bridge inverter circuit includes: upper bridge arm MOSFETs and lower bridge arm MOSFETs. The upper bridge arm MOSFETs include: a first MOSFET Q1, a second MOSFET Q2, and a third MOSFET Q3; the lower bridge arm includes: a fourth MOSFET Q4, a fifth MOSFET Q5, and a sixth MOSFET Q6. Each MOSFET is connected in parallel with a diode. By controlling the on / off state of the six MOSFETs, the DC power output from the battery can be converted into three-phase AC power to drive the motor. The motor winding circuit of the drive motor includes: a first inductor L1, a second inductor L2 and a third inductor L3; the motor winding circuit receives the three-phase AC power output from the inverter circuit, generates a rotating magnetic field to drive the motor to run, and can drive the vehicle to move, or perform power generation.

[0037] The one end of the motor winding circuit is connected with the source level of the upper bridge arm MOS tube and the drain of the lower bridge arm MOS tube respectively, the other end of the motor winding circuit is connected with the one end of the first switch K1, the other end of the first switch K1 is connected with the one end of the second switch K2 and the one end of the protection circuit respectively, the other end of the protection circuit is connected with the positive pole of the battery, the negative pole of the battery is connected with the one end of the third switch K3, the other end of the third switch K3 is connected with the source level of the lower bridge arm MOS tube and the one end of the DC side filter circuit respectively, the other end of the second switch K2 is connected with the drain of the upper bridge arm MOS tube and the other end of the DC side filter circuit respectively. Specifically, the one end of the first inductor L1 is connected with the source of the first MOS tube Q1 and the drain of the fourth MOS tube Q4 respectively, the one end of the second inductor L2 is connected with the source of the second MOS tube Q2 and the drain of the fifth MOS tube Q5 respectively, the one end of the third inductor L3 is connected with the source of the third MOS tube Q3 and the drain of the sixth MOS tube Q6 respectively; the one end of the first switch K1 is connected with the other end of the first inductor L1, the other end of the second inductor L2 and the other end of the third inductor L3, that is, the one end of the first switch K1 is connected with the neutral point of the motor winding circuit.

[0038] In the embodiment of the present application, since the current flowing into the motor winding circuit is consistent in direction and is led out through the neutral point, the vibration amplitude of the motor is reduced, thereby reducing the noise generation in the pulse heating process. At the same time, by adjusting the switching frequency of the upper bridge arm MOS tube and the lower bridge arm MOS tube, the size of the pulse current can be controlled, not only the heating power and the temperature rise rate are improved, but also the flexibility of current regulation is ensured.

[0039] As to step S104, in the specific implementation, as an example, the following steps can be included: Step S41, the inverter controller generates the bridge arm drive signal corresponding to the three-phase full-bridge inverter circuit based on the heating strategy.

[0040] Step S42, based on the bridge arm drive signal, the upper bridge arm MOS tube and the lower bridge arm MOS tube are controlled to be alternately turned on, so that the motor winding circuit and the DC side filter circuit form a resonance circuit to discharge to heat the battery.

[0041] Here, the upper bridge arm MOS tube and the lower bridge arm MOS tube are MOS tubes with opposite polarities, that is, when the upper bridge arm MOS tube is a PMOS tube, the lower bridge arm MOS tube is an NMOS tube; when the upper bridge arm MOS tube is an NMOS tube, the lower bridge arm MOS tube is a PMOS tube. The design of the three-phase full-bridge inverter circuit utilizes the fast switching characteristics of PMOS tubes and NMOS tubes, the bridge arm drive signal is converted into two different drive signals transmitted to PMOS tubes and NMOS tubes, thereby realizing the IGBT high-frequency driving function.

[0042] As to step S42, in a specific implementation, as an example, the following steps can be included: Step S1041, the inverter controller controls the lower bridge arm MOS tube to be continuously turned on and the upper bridge arm MOS tube to be continuously turned off in the first preset time based on the bridge arm drive signal, so that the battery current flows through the motor winding circuit to charge.

[0043] Here, the motor winding circuit stores energy.

[0044] Step S1042, control the lower bridge arm MOS tube to be continuously turned off and the upper bridge arm MOS tube to be continuously turned on in the second preset time, so that the motor winding circuit forms a resonant circuit with the DC side filter circuit to discharge to heat the battery.

[0045] Here, the motor winding circuit stores energy. The motor winding circuit releases stored energy, combines with the bus capacitor discharge to generate high-frequency pulse current, and uses the Joule heating effect of the battery at low temperature To stimulate the internal resistance of the battery to generate heat and raise the temperature of the battery itself. Wherein Q is the heat generated, I is the current of the battery, R is the internal resistance of the battery, and t is the duration of the current passing through the resistance.

[0046] Step S1043, control the battery to output a reverse current, and control the lower bridge arm MOS tube to be continuously turned off and the upper bridge arm MOS tube to be continuously turned on in the third preset time, so that the battery reverse current flows through the motor winding circuit to be charged again.

[0047] Step S1044, control the lower bridge arm MOS tube to be continuously turned on and the upper bridge arm MOS tube to be continuously turned off in the fourth preset time, so that the remaining energy in the motor winding circuit is recovered to the battery.

[0048] Step S1044, determine whether the battery temperature reaches the target temperature interval.

[0049] Steps S1041-S1044 are cycled to achieve periodic switching. The battery, capacitor C and motor winding circuit cooperate to generate high-frequency pulse current on the battery internal resistance to achieve rapid heating.

[0050] Step S1045, if the battery temperature reaches the target temperature interval, stop heating the battery.

[0051] Step S1046, if the battery temperature does not reach the target temperature interval and the current pulse current amplitude of the battery is greater than the pulse current amplitude in the heating strategy, update the bridge arm drive signal based on the current pulse current amplitude of the battery, and return to execute step S1041.

[0052] Here, if the inverter controller determines that the cycle period corresponding to the bridge arm drive signal has not ended, the inverter controller can dynamically adjust the pulse control parameter of the duty cycle according to the battery state parameter fed back by the BMS in real time, regenerate the bridge arm drive signal, and realize the regulation and control of the heating process. Specifically, the inverter controller compares the current pulse current amplitude fed back by the BMS. If the current pulse current amplitude is less than the pulse current amplitude in the heating strategy, the pulse duty cycle is increased, so that the current rises faster and the peak value is higher. If the current pulse current amplitude is greater than the pulse current amplitude in the heating strategy, the pulse duty cycle is reduced to prevent overcurrent. If the current pulse current amplitude is equal to the pulse current amplitude in the heating strategy, the pulse duty cycle is not adjusted.

[0053] In a possible implementation, the heating method of the vehicle battery further includes: the vehicle controller generates a heating strategy again and returns to step S41 when it is determined that the battery meets a strategy adjustment condition during the battery heating process.

[0054] Here, the BMS feeds back the battery state parameter to the vehicle controller, and the vehicle controller compares. Specifically, when the vehicle controller determines that the battery temperature rising rate is lower than the expected temperature rising rate, the vehicle controller increases the pulse duty cycle or the pulse current amplitude within the allowed range according to the SOC and the Imax safety boundary condition. When the vehicle controller determines that the battery temperature rising rate is greater than the expected temperature rising rate, the vehicle controller reduces the pulse duty cycle or the pulse current amplitude within the allowed range until the battery temperature rising rate reaches the expected temperature rising rate. When the vehicle controller determines that the single cell temperature exceeds the safety threshold or the temperature rising slope is abnormal, the vehicle controller reduces the pulse duty cycle or the pulse current amplitude to prevent thermal runaway.

[0055] In the embodiment of the present application, the electric energy of the battery forms a pulse current in the motor winding circuit through the three-phase full-bridge inverter circuit, and heat is generated by utilizing the Joule effect of the motor winding circuit and the internal resistance of the battery to heat the battery. The following is explained in combination with a specific example: the vehicle controller obtains an initial heating strategy according to the battery state parameters provided by the BMS: the pulse frequency is 2.5KHz, the pulse duty cycle is 50%, and the pulse current amplitude is 80A. After the inverter controller receives these parameters, the PWM module is configured and the corresponding bridge arm driving signal is generated to control the high-speed switching operation of the upper and lower bridge arms of the inverter. In the closed-loop regulation process, in the current loop, the inverter controller obtains the current pulse current amplitude 75A of the battery through the BMS feedback, which is lower than the target value 80A, so the pulse duty cycle is adjusted from 50% to 52% to increase the current. In the temperature loop, the vehicle controller adjusts the pulse current amplitude to 85A according to the battery temperature rising rate 3.5℃ / min fed back by the BMS, which is lower than the expected value 6℃ / min, and adjusts the duty cycle to stabilize the actual current at 85A, so that the battery temperature rising rate reaches 6℃ / min.

[0056] It should be noted that the ultra-high frequency pulse helps to further reduce the internal resistance of the solid-state battery. By applying an AC voltage of MHz level (such as ±1V sine wave), a strong capacitive effect can be excited at the electrode and electrolyte interface, so that the current mainly passes through the interface double layer in the capacitive component, rather than the component driving the redox reaction, thereby efficiently generating Joule heat inside the solid-state electrolyte. This internal heat generation method is non-invasive and does not require modification of the battery structure, and the high-frequency characteristic can effectively avoid the risk of lithium precipitation caused by low-frequency current. The implementation of this technology relies on precise frequency selection. When the frequency is increased to the MHz range, the capacitive reactance of the interface capacitance is significantly reduced, allowing more current to pass and enhancing the Joule heat effect; at the same time, the skin effect of high-frequency current is weakened, and the heat is uniformly distributed in the electrolyte body phase, thereby effectively solving the problem of increased internal impedance caused by the sharp decrease in ionic conductivity of the solid-state electrolyte at low temperature or room temperature, and achieving the effect of efficient heat generation without damaging the battery structure.

[0057] The technical scheme provided in the present application can quickly increase the temperature of the battery under low temperature conditions, solve the problem of insufficient battery performance, and ensure that the electric vehicle can be started smoothly in extremely cold environments.

[0058] The heating method for a vehicle battery provided in the embodiment of the present application enhances the heating efficiency of the battery and reduces the cost.

[0059] Based on the same application concept, the application embodiment also provides a vehicle battery heating system corresponding to the vehicle battery heating method provided by the above-mentioned embodiment. Since the system in the application embodiment has a similar problem solving principle as the vehicle battery heating method in the above-mentioned embodiment of the application, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described here.

[0060] As shown in Figure 2 The application embodiment provides a vehicle battery heating system, which comprises a vehicle controller, a BMS, an inverter controller, an inverter and a drive motor. The vehicle controller determines whether the battery meets the preset heating condition. If the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request of a switch in the switching circuit of the inverter, and generates a heating strategy of the battery based on the state parameters of the battery. The BMS controls the switch in the switching circuit to be on or off in response to the heating on-off request. The inverter controller controls the MOS tube in the three-phase full-bridge inverter circuit of the inverter to be on or off based on the heating strategy, so that the motor winding circuit of the drive motor releases energy to heat the battery.

[0061] Further, the switching circuit comprises a first switch, a second switch and a third switch. The BMS controls the first switch and the third switch to be closed and controls the second switch to be opened in response to the heating on-off request.

[0062] The application embodiment provides a vehicle battery heating system, which enhances the heating efficiency of the battery and reduces the cost.

[0063] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-mentioned system and device can refer to the corresponding process in the foregoing method embodiment, which will not be described here. In the several embodiments provided by the application, it should be understood that the disclosed system, device and method can be implemented by other ways. The device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there can be another division manner in actual implementation, and for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some communication interfaces, devices or units, and can be electrical, mechanical or other forms.

[0064] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0065] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present alone, or two or more units can be integrated in one unit.

[0066] If the functions are realized in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the present application or the parts of the present application that essentially contribute to the prior art or the parts of the technical solutions can be embodied in the form of software products. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The foregoing storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk, and various program code storage media.

[0067] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of heating a vehicle battery, characterized by, The heating method is applied to a heating system of a vehicle battery; The heating system comprises a vehicle controller, a BMS, an inverter controller, an inverter and a driving motor; the heating method comprises: The vehicle controller determines whether the battery meets a preset heating condition; if the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request of a switch in a switching circuit of the inverter, and generates a heating strategy of the battery based on a state parameter of the battery; The BMS controls the switch in the switching circuit to be on or off in response to the heating on-off request; The inverter controller controls MOS transistors in a three-phase full-bridge inverter circuit of the inverter to be on or off based on the heating strategy, so that a motor winding circuit of the driving motor releases energy to heat the battery.

2. The method of heating a vehicle battery according to claim 1, wherein The switching circuit comprises a first switch, a second switch and a third switch; the BMS controls the switch in the switching circuit to be on or off in response to the heating on-off request, which comprises: The BMS controls the first switch and the third switch to be on and controls the second switch to be off in response to the heating on-off request.

3. The method of heating a vehicle battery according to claim 2, wherein, The heating method further comprises: If the vehicle controller determines that the battery does not meet the preset heating condition, the vehicle controller generates a non-heating on-off request of the switch in the switching circuit; The BMS controls the first switch and the third switch to be off and controls the second switch to be on in response to the non-heating on-off request.

4. The method of heating a vehicle battery of claim 2, wherein, The circuit of the inverter further comprises a direct current side filter circuit and a protection circuit; the three-phase full-bridge inverter circuit comprises upper bridge arm MOS transistors and lower bridge arm MOS transistors; One end of the motor winding circuit is connected to the source level of the upper bridge arm MOS transistors and the drain of the lower bridge arm MOS transistors, respectively; the other end of the motor winding circuit is connected to one end of the first switch; the other end of the first switch is connected to one end of the second switch and one end of the protection circuit, respectively; the other end of the protection circuit is connected to the positive electrode of the battery; the negative electrode of the battery is connected to one end of the third switch; the other end of the third switch is connected to the source level of the lower bridge arm MOS transistors and one end of the direct current side filter circuit, respectively; the other end of the second switch is connected to the drain of the upper bridge arm MOS transistors and the other end of the direct current side filter circuit, respectively; The inverter controller controls the MOS transistors in the three-phase full-bridge inverter circuit of the inverter to be on or off based on the heating strategy, so that the motor winding circuit of the driving motor releases energy to heat the battery, which comprises: (A) The inverter controller generates bridge arm driving signals corresponding to the three-phase full-bridge inverter circuit based on the heating strategy; (B) The upper bridge arm MOS transistors and the lower bridge arm MOS transistors are controlled to be alternately turned on based on the bridge arm driving signals, so that the motor winding circuit and the direct current side filter circuit form a resonance loop to discharge to heat the battery.

5. The method of heating a vehicle battery according to claim 4, wherein The inverter controller controls the upper bridge arm MOS tube and the lower bridge arm MOS tube to be alternately turned on based on the bridge arm drive signal, so that the motor winding circuit and the DC side filter circuit form a resonance loop to discharge to heat the battery, including: (a) The inverter controller controls the lower bridge arm MOS tube to be continuously turned on and the upper bridge arm MOS tube to be continuously turned off within a first preset time based on the bridge arm drive signal, so that the battery current flows through the motor winding circuit to charge; (b) The lower bridge arm MOS tube is controlled to be continuously turned off and the upper bridge arm MOS tube is controlled to be continuously turned on within a second preset time, so that the motor winding circuit and the DC side filter circuit form a resonance loop to discharge to heat the battery; (c) The battery output reverse current is controlled, and the lower bridge arm MOS tube is controlled to be continuously turned off and the upper bridge arm MOS tube is controlled to be continuously turned on within a third preset time, so that the battery reverse current flows through the motor winding circuit to charge again; (d) The lower bridge arm MOS tube is controlled to be continuously turned on and the upper bridge arm MOS tube is controlled to be continuously turned off within a fourth preset time, so that the remaining energy in the motor winding circuit is recovered to the battery; (e) It is determined whether the battery temperature reaches a target temperature interval; (f) If the battery temperature reaches the target temperature interval, the heating of the battery is stopped; (g) If the battery temperature does not reach the target temperature interval and the current pulse current amplitude of the battery is greater than the pulse current amplitude in the heating strategy, the bridge arm drive signal is updated based on the current pulse current amplitude of the battery, and step (a) is returned to be executed.

6. The method of heating a vehicle battery of claim 4, wherein, The heating method of the vehicle battery further includes: The vehicle controller re-generates the heating strategy when it is determined that the battery meets the strategy adjustment condition during the battery heating process, and returns to execute step (A).

7. The method of heating a vehicle battery of claim 4, wherein, The motor winding circuit includes a first inductor, a second inductor and a third inductor; the upper bridge arm MOS tube includes a first MOS tube, a second MOS tube and a third MOS tube; the upper bridge arm includes a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; Wherein, one end of the first inductor is connected with the source of the first MOS tube and the drain of the fourth MOS tube respectively, one end of the second inductor is connected with the source of the second MOS tube and the drain of the fifth MOS tube respectively, and one end of the third inductor is connected with the source of the third MOS tube and the drain of the sixth MOS tube respectively.

8. The method of heating a vehicle battery according to claim 7, wherein, One end of the first switch is connected with the other end of the first inductor, the other end of the second inductor and the other end of the third inductor respectively.

9. A heating system for a vehicle battery, characterized by The heating system includes a vehicle controller, a BMS, an inverter controller, an inverter and a driving motor; The vehicle controller determines whether the battery meets a preset heating condition; if the vehicle controller determines that the battery meets the preset heating condition, the vehicle controller generates a heating on-off request of the switch in the switch circuit of the inverter, and generates a heating strategy of the battery based on the state parameters of the battery; The BMS controls the switch in the switch circuit to be turned on or turned off in response to the heating on-off request. The inverter controller controls on-off of MOS tubes in a three-phase full-bridge inverter circuit of the inverter based on the heating strategy, so that the motor winding circuit of the driving motor releases energy to heat the battery.

10. The heating system of a vehicle battery according to claim 9, characterized by, The switching circuit comprises a first switch, a second switch and a third switch. The BMS controls the first switch and the third switch to be closed and controls the second switch to be opened in response to the heating on-off request.

Images