An electric vehicle power battery heating control system, method and vehicle

Abstract

The application discloses a kind of electric vehicle power battery heating control system, method and vehicle, belong to electric vehicle thermal management technical field, the system includes power battery, motor controller and motor body, and power battery is heated by motor controller control motor body charge-discharge;It also includes noise sensor, thermal management system, vehicle controller, motor controller is used to according to the fast charging or pulse heating mode instruction issued, according to three-phase common mode current injection time sequence control upper and lower bridge arms of three-phase full-bridge circuit respectively switch synchronous conduction and open, so that high-frequency charge-discharge loop is formed between power battery and three-phase winding, power battery is heated, while adjusting pulse heating frequency according to noise signal;According to the issued locked-rotor heating mode instruction, control three-phase winding continues to be electrified and generates heat, and heat is conducted to power battery by thermal management system to heat.The application can realize the self-adaptive suppression of heating noise, realize the continuous efficient heating of full temperature section.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle power battery thermal management technology, and particularly relates to an electric vehicle power battery heating control system, method and vehicle. Background Technology

[0002] In low-temperature environments, the discharge capacity and capacity decay of electric vehicle power batteries (such as lithium iron phosphate batteries) decrease due to their inherent chemical characteristics, severely impacting the power and range of electric vehicles, affecting user experience and hindering the promotion of electric vehicles. Therefore, it is necessary to heat the power battery when the vehicle is in a low-temperature environment to ensure the electric vehicle's power performance. To improve heating efficiency, existing technologies propose using pulse heating for low-temperature heating of the power battery. However, in existing pulse heating methods, the pulse heating frequency is fixed, and the motor windings generate significant noise under high-frequency on / off excitation, affecting the user experience. Moreover, as the cell temperature gradually increases, the internal resistance of the power battery continuously decreases, resulting in less heat generated under the same pulse current, a significant decrease in heating rate, and a prolonged heating time. Summary of the Invention

[0003] This invention provides a heating control system, method, and vehicle for electric vehicle power batteries. By introducing a noise sensor to construct a closed-loop frequency modulation control circuit, and designing a dual-mode adaptive switching mechanism for pulse heating and stall heating (i.e., VIPTC heating), it solves the problems of high motor noise caused by fixed frequency operation in existing pulse heating schemes and the decrease in heating efficiency of a single heating mode as the internal resistance decreases with the increase of battery temperature.

[0004] In a first aspect, the present invention provides a heating control system for electric vehicle power batteries.

[0005] An electric vehicle power battery heating control system includes a power battery, a motor controller, and a motor body. The motor controller has a three-phase full-bridge circuit. The DC side of the three-phase full-bridge circuit is electrically connected to the power battery to form a high-voltage circuit, and the AC side is electrically connected to the three-phase windings of the motor body. The system also includes: A noise sensor, mounted on the housing of the motor body, is used to collect noise signals and send them to the motor controller; Thermal management system, connecting the cooling circuit of the motor body with the cooling circuit of the power battery; The vehicle controller communicates with the motor controller, thermal management system, and control terminal to issue heating mode commands. The motor controller is used to: according to the fast charging or pulse heating mode command, control the upper and lower bridge arms of the three-phase full-bridge circuit to switch synchronously on and off according to the three-phase common-mode current injection timing, so that a high-frequency charging and discharging circuit is formed between the power battery and the three-phase winding to heat the power battery, and at the same time adjust the pulse heating frequency according to the noise signal; according to the stall heating mode command, control the three-phase winding to continuously generate heat, and the heat is conducted to the power battery through the thermal management system for heating.

[0006] By multiplexing the three-phase windings of the motor body as energy storage inductors, and utilizing the high internal resistance of the power battery at low temperatures, a large amount of Joule heat is generated during high-frequency charge-discharge cycles, achieving rapid temperature rise. A noise sensor is installed on the motor body, enabling the system to perceive motor noise in real time during the heating process. The motor controller then dynamically adjusts the pulse heating frequency accordingly, forming a closed-loop control to reduce motor noise. Simultaneously, multiple different heating modes are designed and adaptively switched to avoid the problem of reduced heating rate under a single pulse heating mode, which fails to meet the high-efficiency heating requirements of the battery throughout the entire process from low temperature to the target temperature.

[0007] A further technical solution is that the motor controller is used to adjust the pulse heating frequency according to the noise signal, including: The noise signal is compared with a preset noise threshold. When the noise signal exceeds the noise threshold, the pulse heating frequency is adjusted upward by a preset step value until the noise signal does not exceed the noise threshold. When the noise signal does not exceed the noise threshold and the current pulse heating frequency remains stable for a preset time, the current pulse heating frequency is stored as the user-preferred frequency in the non-volatile storage area; when the subsequent heating process is started, the user-preferred frequency is given priority as the initial frequency of pulse heating.

[0008] By setting a noise threshold as the frequency modulation criterion, adaptive closed-loop adjustment of the pulse heating frequency is achieved, ensuring heating efficiency while keeping motor noise within an acceptable range for users.

[0009] In a further technical solution, the non-volatile storage area stores corresponding user-preferred frequencies in segments according to battery temperature ranges; the motor controller is also used to automatically match the user-preferred frequency of the corresponding temperature range as the initial frequency when starting pulse heating.

[0010] By introducing a user preference frequency memory function, the frequency search time can be reduced each time heating is started, improving the consistency and convenience of the user experience.

[0011] In a further technical solution, the system also includes a battery management system; the battery management system is communicatively connected to the vehicle controller and is used to detect the battery temperature and charging power during the charging process, and generate a corresponding heating request based on the detection results, including: when the battery temperature is lower than a first temperature threshold and the charging power is lower than a preset ratio of the rated charging power, sending a stall heating request to the vehicle controller; The vehicle controller is used to send a stall heating command to the motor controller according to the stall heating request; The motor controller is used to control the three-phase winding to inject a continuous DC bias current in the d-axis direction according to the stall heating command, and the high-voltage circuit of the power battery remains connected during the stall heating process.

[0012] By designing a stall-rotor heating mode, the motor windings are continuously energized and heated. The heat is then circulated and transferred to the power battery through the coolant in the thermal management system. Even after the pulse heating efficiency decreases, an effective heating rate can still be maintained, which makes up for the deficiency of insufficient heating capacity in the high-temperature range of the single pulse heating mode.

[0013] In a further technical solution, the motor controller performs three joint access checks before executing the heating mode command. The three joint access checks include: battery temperature check, battery state of charge check, and auxiliary battery voltage check. Each check has a start threshold and an exit threshold, and there is a hysteresis interval between the start threshold and the exit threshold. The exit state transition can only be executed after the battery temperature signal meets the exit threshold condition for a preset delay.

[0014] By designing pulse heating access conditions—that the battery temperature is below the preset upper temperature threshold, the battery state of charge is not below the first state of charge threshold, and the auxiliary battery voltage is not below the lower voltage threshold—the joint verification of these three conditions ensures that pulse heating can only be initiated when the battery temperature, state of charge, and auxiliary battery voltage all meet the requirements, thus preventing safety risks caused by initiating heating under unsuitable conditions.

[0015] In a further technical solution, the system also includes an in-vehicle communication unit, which is communicatively connected to the vehicle controller and the control terminal. The control terminal includes at least one of a mobile application terminal, a cockpit display screen, and a voice control system. The in-vehicle communication unit is used to receive heating requests sent by the control terminal and transmit them to the vehicle controller, while simultaneously waking up the vehicle controller and the battery management system to execute the high-voltage power-on process.

[0016] By introducing an onboard communication unit, the system can support remote wake-up and heating start-up, allowing users to start battery heating in advance without entering the vehicle, improving the convenience of using the vehicle in low-temperature environments; by setting up multiple control entry points, it can meet the operation needs of different usage scenarios and improve the flexibility of human-machine interaction of the system.

[0017] In a further technical solution, the vehicle controller generates a heating mode command based on the received heating request and sends the heating mode command to the motor controller via the vehicle communication bus; the heating request includes a fast charging heating request, a battery heating request, and a stall heating request; the heating mode includes a fast charging heating mode, a pulse heating mode, and a stall heating mode; when the motor controller switches between heating modes, it first switches the heating mode command to a state with no heating request, and then switches to the target mode heating command.

[0018] In a further technical solution, a main positive relay K1 and a main negative relay K2 are connected in series in the high-voltage circuit of the power battery. The main positive relay K1 is connected in parallel with a pre-charge branch, which includes a pre-charge relay K3 and a pre-charge resistor connected in series. When the system is powered on, the main negative relay K2 and the pre-charge relay K3 are closed first. After the difference between the bus voltage and the power battery terminal voltage is lower than a preset value, the main positive relay K1 is closed and the pre-charge relay K3 is opened, and the system enters the high-voltage ready state. A bus support capacitor is connected in parallel to the DC bus of the three-phase full-bridge circuit; during pulse heating, the bus support capacitor is used to absorb the bus overvoltage caused by the induced electromotive force of the three-phase winding.

[0019] By designing a pre-charge branch, a pre-charge resistor is introduced into the branch to limit the inrush current at the moment of power-on, protect the main positive relay K1 contact and the internal support capacitor of the motor controller, and ensure the safety and reliability of the high-voltage power-on process.

[0020] Secondly, the present invention provides a method for controlling the heating of a power battery for electric vehicles.

[0021] A heating control method for an electric vehicle power battery, applied to the aforementioned electric vehicle power battery heating control system, wherein the battery heating is achieved by the charging and discharging of the three-phase windings of the motor body controlled by the motor controller, and the control method includes: Based on the received heating mode command, the battery temperature, battery state of charge and auxiliary battery voltage are first subjected to a three-item joint access verification. After the verification is passed, the pulse heating mode is entered. In pulse heating mode, the upper and lower bridge arms of the three-phase full-bridge circuit are switched on and off synchronously according to the three-phase common-mode current injection timing, so that a high-frequency charging and discharging circuit is formed between the power battery and the three-phase windings to heat the power battery; at the same time, the pulse heating frequency is adjusted according to the noise signal collected in real time. The system detects exit conditions in real time. When the exit conditions are met, it exits the pulse heating mode and provides feedback on the heating status.

[0022] A further technical solution involves adjusting the pulse heating frequency based on the noise signal, including: The noise signal is compared with a preset noise threshold. When the noise signal exceeds the noise threshold, the pulse heating frequency is adjusted upwards by a preset step value. After each step, the comparison is repeated after a preset judgment period until the noise signal does not exceed the noise threshold. When the noise signal does not exceed the noise threshold and the current pulse heating frequency remains stable for a preset time, the current pulse heating frequency is written as the user-preferred frequency to the non-volatile storage area. When the subsequent heating process starts, the user-preferred frequency is read as the initial frequency of pulse heating.

[0023] A further technical solution is to respond to the user-triggered heating request, wake up the various controllers of the system, generate a high-voltage power-on command, and control the system to execute the high-voltage power-on process. After the system enters the high-voltage ready state, the vehicle controller sends the corresponding heating mode command to the motor controller. The system defaults to a no-heating-request state; when a non-rechargeable battery heating request is received, it jumps to the battery heating request state; when a fast-charging heating request is received, it jumps to the fast-charging heating request state; when a stalled heating request is received during charging, it jumps to the stalled heating request state; when any heating mode exits, the heating mode command first jumps to the no-heating-request state before executing subsequent actions.

[0024] A further technical solution involves controlling the fast-charging heating process as follows: When the battery management system detects that the battery temperature is lower than the charging access temperature, it sends a fast charging heating request to the vehicle controller. The vehicle controller then sends a fast charging heating command to the motor controller based on the fast charging heating request. The motor controller then enters the pulse heating mode to heat the power battery. When the battery management system detects that the battery temperature has reached the charging entry temperature, the motor controller exits the pulse heating mode and waits for a preset delay before the system enters the charging state. The high-voltage circuit of the power battery remains connected during the transition from exiting pulse heating to starting charging.

[0025] The above-mentioned fast charging heating design enables automatic preheating before charging, solving the problem that the power battery cannot be fast charged due to insufficient temperature in low-temperature environments.

[0026] A further technical solution involves controlling the stall heating process during charging as follows: During the charging process, when the battery management system detects that the battery temperature is lower than the first temperature threshold and the charging power is lower than the preset ratio of the rated charging power, it sends a stall heating request to the vehicle controller. The vehicle controller then sends a stall heating command to the motor controller. The motor controller controls the three-phase winding to inject a continuous DC bias current in the d-axis direction. The heat generated by the three-phase winding is conducted to the power battery through the thermal management system. The high-voltage circuit of the power battery remains connected during the stall heating process.

[0027] By monitoring in real time during charging and switching to stall heating mode, the continuous power supply and heat generation capacity of the motor windings can be fully utilized to achieve the function of charging and heat preservation at the same time, ensuring that the battery temperature is maintained within a suitable range throughout the charging process.

[0028] A further technical solution is that the three joint access verifications include: The battery temperature start threshold is a calibrable value within the range of -30℃ to -10℃, and the exit threshold is 0℃. The exit state transition can only be executed after the battery temperature signal meets the exit threshold condition continuously for 3 seconds. The battery state of charge (SOC) threshold for starting up is no less than 30%, and the SOC threshold for stopping up is no more than 20%. The auxiliary battery voltage start-up threshold is not lower than 12.2V, and the stop-loss threshold is not higher than 11.8V.

[0029] Thirdly, the present invention provides a vehicle.

[0030] A vehicle includes the above-described electric vehicle power battery heating control system, or a method for implementing the above-described electric vehicle power battery heating control.

[0031] The above one or more technical solutions have the following beneficial effects: This invention provides a heating control system, method, and vehicle for an electric vehicle's power battery. It employs pulse heating to heat the power battery, utilizing the winding coils of the drive motor as inductive energy storage. By periodically switching the full-bridge IGBT arm switches of the motor controller on and off, a high-frequency charge-discharge circuit is formed between the power battery and the three-phase windings. Through repeated high-frequency charge-discharge cycles, combined with the high internal resistance of lithium iron phosphate batteries at low temperatures, the Joule heat generated by the battery's internal resistance achieves rapid temperature rise. Furthermore, a noise sensor is installed on the motor housing, and the motor controller compares the real-time collected noise signal with a noise threshold to dynamically adjust the pulse heating frequency, constructing a closed-loop noise control circuit to fundamentally address the issue. This invention solves the technical problem of existing pulse heating solutions, which suffer from high motor noise due to fixed-frequency operation and lack of adaptive adjustment. It achieves adaptive suppression of motor heating noise within an acceptable range under closed-loop frequency control, significantly improving the user experience. Simultaneously, by introducing pulse heating, stall heating, and other modes and their adaptive switching mechanisms, it utilizes the high internal resistance characteristics of the battery for efficient pulse heating in the low-temperature range. When the internal resistance decreases and the pulse heating efficiency drops as the temperature rises, it automatically switches to stall heating mode. The heat generated by the continuous energization of the motor windings is transferred to the power battery through the thermal management system. This overcomes the defect of a significant decrease in heating rate in the high-temperature range of a single pulse heating mode, achieving continuous and efficient heating across the entire temperature range.

[0032] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0034] Figure 1 This is a structural block diagram of the electric vehicle power battery heating control system in an embodiment of the present invention; Figure 2 This is a flowchart of the electric vehicle power battery heating control method in an embodiment of the present invention.

[0035] The components include: 1. Power battery; 2. Motor controller; 3. Motor body; 4. Noise sensor; 5. Control terminal; 6. Vehicle communication unit; 7. Voice control system; 8. Cockpit display screen; 9. Vehicle controller; 10. Thermal management system; 11. Battery management system; and 12. Mobile application terminal. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are exemplary and are intended only to describe specific embodiments and to provide further explanation of the invention, and are not intended to limit the scope of exemplary embodiments of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0037] Terminology Explanation Pulse heating: This method uses the three-phase winding of the motor as an energy storage inductor. By controlling the periodic on and off of the motor controller bridge arm switch, a high-frequency charging and discharging circuit is formed between the power battery and the three-phase winding. The battery temperature is achieved by generating Joule heat through the internal resistance of the battery. High Voltage Ready (HV Ready): The electric vehicle's high voltage system has completed the power-on pre-charging process, both the main positive and main negative relays are closed, the DC bus voltage has been established, and the system is ready to perform high voltage functions.

[0038] As noted in the background section, current electric vehicles can use pulse heating to heat the power battery in low-temperature environments. However, this method uses a fixed pulse heating frequency, which generates significant noise in the motor windings under high-frequency switching excitation, resulting in a poor user experience. Furthermore, as the cell temperature gradually increases, the battery's internal resistance continuously decreases, leading to less Joule heat generated under the same pulse current and a significant drop in heating rate. A single pulse heating mode is insufficient to meet the heating requirements of the battery throughout the entire process from low temperature to the target temperature. Therefore, this invention proposes an electric vehicle power battery heating control scheme that integrates noise closed-loop frequency modulation and adaptive switching between multiple modes, including pulse heating and stall heating, to address the aforementioned technical shortcomings.

[0039] Specifically, to address the aforementioned technical issues, this invention, at the system level, adds a noise sensor to the existing pulse heating circuit to construct a closed-loop noise feedback path. It also introduces a stall-rotor heating mode, using a thermal management system to transfer heat generated by the motor windings to the power battery, achieving multi-mode complementary heating. At the control level, the motor controller collects the noise signal output from the noise sensor in real time and compares it with a preset noise threshold. When the noise exceeds the threshold, it searches upwards by a preset step value to adjust the pulse frequency until the noise drops below the threshold. Simultaneously, it records and stores the user's preferred frequency for priority use during subsequent startups, reducing search time. At the scenario level, it supports three application scenarios: preheating before driving (not charging), low-temperature preheating before fast charging, and continuous heat preservation during charging. The vehicle controller assists in coordinating the safe switching between these scenarios through a heating enable command state machine. Through these designs, this invention can achieve continuous and efficient heating across the entire temperature range while keeping noise levels within an acceptable range for the user.

[0040] Example 1 This embodiment proposes a heating control system for an electric vehicle power battery, the overall structure of which is as follows: Figure 1 As shown, the system includes a power battery 1, a motor controller 2, a motor body 3, a noise sensor 4, a control terminal 5, an on-board communication unit 6, a voice control system 7, a cockpit display screen 8, a vehicle controller 9, a thermal management system 10, and a battery management system 11. Each component is designed as follows: 1) The power battery 1 is the high-voltage power source of the system. Its positive terminal is connected to the positive terminal of the DC bus of the motor controller 2 via the main positive relay K1, and its negative terminal is connected to the negative terminal of the DC bus via the main negative relay K2. The main positive relay K1 is connected in parallel with a pre-charge branch, which is composed of the pre-charge relay K3 and the pre-charge resistor connected in series.

[0041] 2) The motor controller 2 internally contains a three-phase full-bridge circuit consisting of the first bridge arm switch S1 to the sixth bridge arm switch S6. The DC side of the three-phase full-bridge circuit is electrically connected to the power battery 1 to form a high-voltage circuit, and the AC side is electrically connected to the A-phase, B-phase, and C-phase windings of the motor body 3, respectively. In addition, a bus support capacitor is connected in parallel on the DC bus. This capacitor is a film capacitor with a capacitance range of 500μF to 2000μF, used to absorb the bus overvoltage caused by the induced electromotive force of the three-phase windings during pulse heating, thus protecting the bridge arm switching devices.

[0042] 3) The noise sensor 4 is installed on the outer surface of the housing of the motor body 3. It is used to collect the structural vibration noise generated by the high-frequency switching excitation of the winding during the pulse heating process of the motor in real time, and transmit the collected noise signal to the motor controller 2.

[0043] 4) The coolant pipeline of the thermal management system 10 (TMS) is connected to both the cooling circuit of the motor body 3 and the cooling circuit of the power battery 1, so that the heat generated by the motor windings can be transferred to the power battery 1 through the coolant circulation.

[0044] 5) The vehicle control unit (VCU) 9 is connected to the motor controller 2, the thermal management system 10, and the control terminal 5 via the vehicle communication bus. It is responsible for receiving heating requests, generating heating mode instructions, and sending them to the motor controller 2.

[0045] 6) The vehicle communication unit 6 is connected to the vehicle controller 9 and the control terminal 5 respectively. The control terminal 5 includes at least one of the mobile application terminal 12, the cockpit display screen 8 and the voice control system 7, and is used to receive heating requests from users and wake up the vehicle controller 9 and the battery management system 11 to perform the high voltage power-on process when the system is in a dormant state.

[0046] 7) The Battery Management System (BMS) 11 communicates with the vehicle controller 9 and is responsible for real-time detection of battery temperature, state of charge and charging power, and sends corresponding heating requests to the vehicle controller 9 based on the detection results.

[0047] The aforementioned control units communicate and interact via the vehicle's CAN bus, ensuring the real-time and reliable transmission of commands and status information. It should be understood that the above example environment is described for illustrative purposes only and does not imply any limitation on the scope of protection of this application. For example, in some embodiments, this application can also be applied to other electrified equipment scenarios such as new energy commercial vehicles and electric construction machinery, and other components such as sensors, relays, or communication modules (not shown) may also exist in the example environment.

[0048] Based on the above structural design, the core structure and working principle of the electric vehicle power battery heating control system are explained in detail.

[0049] like Figure 1 In the power battery section shown, the high-voltage circuit of power battery 1 has a main positive relay K1 and a main negative relay K2 connected in series. The main positive relay K1 is connected in parallel to a pre-charge branch, which is formed by a pre-charge relay K3 connected in series with a pre-charge resistor. When the system is powered on, the vehicle controller 9 first controls the main negative relay K2 and the pre-charge relay K3 to close. The current from power battery 1 then charges the DC bus support capacitor inside the motor controller 2 through the pre-charge resistor. During the pre-charge process, the motor controller 2 monitors the bus voltage in real time. When the difference between the bus voltage and the voltage at the power battery 1 terminal is lower than a preset value (5V in the engineering implementation), the pre-charge is considered complete. At this time, the vehicle controller 9 controls the main positive relay K1 to close, and then opens the pre-charge relay K3, and the system enters the high-voltage ready state. Thus, the pre-charge branch, through the pre-charge resistor, limits the instantaneous surge current within a safe range, preventing large current surges from damaging the contacts of the main positive relay K1 and the bus support capacitor, ensuring the safety and reliability of the high-voltage power-on process.

[0050] like Figure 1 The motor controller section shown, including the three-phase full-bridge circuit and pulse heating circuit, operates as follows: The three-phase full-bridge circuit consists of six bridge arm switches S1 to S6, where S1, S3, and S5 are the upper bridge arm switches, and S2, S4, and S6 are the lower bridge arm switches. S1 and S2 form phase A, S3 and S4 form phase B, and S5 and S6 form phase C. In pulse heating mode, the motor controller 2 controls the on / off state of the bridge arm switches according to the three-phase common-mode current injection timing sequence. When the three-phase upper bridge arm switches S1, S3, and S5 are simultaneously turned on, the three-phase windings form a circuit with the positive terminal of power battery 1, power battery 1 discharges to the three-phase windings, the winding current increases linearly, and the energy stored in the windings increases. After a preset conduction time, control S1, S3, and S5 are simultaneously disconnected, while control the three-phase lower bridge arm switches S2, S4, and S6 are simultaneously turned on. The electrical energy stored in the winding is freewheeled through the lower bridge arm and charges the power battery 1, and the winding current decreases linearly. After a preset disconnection time, S1, S3, and S5 are controlled to be synchronously turned on again, and this cycle repeats, so that a high-frequency charging and discharging circuit is formed between the power battery 1 and the three-phase winding.

[0051] Because the three-phase common-mode current injection sequence makes the direction and magnitude of the current in the three-phase windings completely symmetrical, the combined magnetomotive force generated by the three-phase windings cancels each other out in space. The net torque on the rotor is zero, the motor remains stationary, and no mechanical output is generated. All electrical energy is used for high-frequency charging and discharging between power battery 1 and the windings. Based on this, according to Joule's law, the internal resistance of power battery 1... The generated heat power is Where I is the charging and discharging current, This represents the internal resistance at the current battery temperature. At low temperatures, lithium iron phosphate batteries have a higher internal resistance, resulting in higher heat output and a faster heating rate for the same current.

[0052] In addition, the bus support capacitor connected in parallel on the DC bus absorbs the bus overvoltage caused by the winding induced electromotive force during the freewheeling phase of the lower bridge arm, which can prevent the bus voltage spike from exceeding the withstand voltage limit of the bridge arm switching device.

[0053] In this embodiment, the vehicle communication unit 6 is communicatively connected to the vehicle controller 9 and the control terminal 5, respectively. The control terminal 5 includes at least one of a mobile application terminal 12, a cockpit display screen 8, and a voice control system 7. Users can issue heating requests through any of the above control terminals. In response to receiving a heating request, the vehicle communication unit 6 first wakes up the vehicle controller 9 and the battery management system 11. After each controller exits its sleep state, it executes the high-voltage power-on process: the vehicle controller 9 generates a high-voltage power-on command, controlling the main negative relay K2 and the pre-charge relay K3 to close first, starting the pre-charge process; after the difference between the bus voltage and the voltage at the power battery 1 terminal is less than 5V, the main positive relay K1 closes, the pre-charge relay K3 opens, and the system enters the high-voltage ready state; subsequently, the vehicle controller 9 generates a corresponding auxiliary heating enable command according to the type of heating request received, and sends a heating mode command to the motor controller 2 through the vehicle communication bus. Thus, users can start battery heating in advance without entering the vehicle, improving the convenience of using the vehicle in low-temperature environments.

[0054] The vehicle controller 9 coordinates the switching of various heating modes through auxiliary heating enable commands (i.e., heating mode commands). These commands use status bit encoding and define four states: 1) Status bit 00 indicates that there is no heating request, the system is in normal standby state, and the motor controller 2 does not perform any heating action; 2) Status bit 01 indicates a fast charging heating request, corresponding to the fast charging heating mode; 3) Status bit 02 indicates a battery heating request, corresponding to the pulse heating mode in non-charging scenarios; 4) Status bit 03 indicates a stall heating request, which corresponds to the stall heating mode during the charging process.

[0055] In this embodiment, the system defaults to state 00. When a non-rechargeable battery heating request is received, the auxiliary heating enable command jumps to state 02; when a fast charging heating request is received, it jumps to state 01; and when a stalled heating request is received during charging, it jumps to state 03. When exiting any heating mode, the auxiliary heating enable command must first jump to state 00 before executing subsequent actions; direct jumps between heating states are not allowed. This ensures the safety of high-voltage circuit switching and prevents concurrent conflicts in multiple scenarios.

[0056] Furthermore, after the system is powered on, the motor controller 2 receives the heating mode command from the VCU and performs a three-step joint access check before executing any heating mode command. Heating can only be started when all three conditions are met simultaneously. Specifically, the three-step joint access check includes: The first item is battery temperature verification. Motor controller 2 reads the current battery temperature reported by battery management system 11. With respect to battery temperature start-up threshold Comparison. Among them, For calibrable parameters, the calibration range is -30℃ to -10℃. During engineering implementation, the appropriate temperature range will be selected based on the vehicle's low-temperature operating requirements. Below At that time, the battery temperature verification passed. Additionally, an exit threshold was set. The temperature is fixed at 0℃, meaning that the exit condition is met when the battery temperature rises above 0℃.

[0057] In some embodiments, to prevent frequent fluctuations in the battery temperature signal near the exit threshold caused by sensor noise, which could lead to repeated switching of the heating state, an anti-jitter delay mechanism is designed: the battery temperature signal must continuously meet the exit threshold condition for more than 3 seconds before the motor controller 2 can execute the exit state transition. Therefore, and A hysteresis range is formed between these ranges to prevent the system from repeatedly starting and stopping near the critical temperature.

[0058] The second step is battery state of charge (SOC) verification. The motor controller 2 reads the current SOC reported by the battery management system 11 and compares it with the SOC activation threshold. The activation threshold is set to be no less than 30% to ensure the battery has sufficient usable charge when starting pulse heating, preventing deep battery depletion due to continuous discharge during heating. The deactivation threshold is set to be no more than 20%. When the SOC drops below 20%, the deactivation condition is met, and the heating mode is immediately deactivated, preserving necessary remaining charge for driving. Thus, a 10% hysteresis band is formed between the activation threshold of 30% and the deactivation threshold of 20%, preventing frequent switching of heating states caused by SOC oscillations near the critical value.

[0059] The third item is the auxiliary battery voltage verification. Motor controller 2 reads the current voltage of the auxiliary battery (12V small battery). This is compared with the voltage start-up threshold. The start-up threshold is set to no less than 12.2V to ensure the auxiliary battery has sufficient power supply capacity and to guarantee the normal operation of each controller. The exit threshold is set to no more than 11.8V. The exit condition is met when the voltage drops below 11.8V. Thus, a 0.4V hysteresis band is formed between the start-up threshold of 12.2V and the exit threshold of 11.8V, preventing the auxiliary battery voltage from fluctuating frequently near the critical value due to load fluctuations, which would cause repeated switching of the heating state.

[0060] It should be noted that, considering that simple threshold comparison can cause repeated state transitions and system oscillations when the detected signal is near the threshold, even small signal fluctuations can lead to system oscillations. Therefore, the three joint admission checks designed in this embodiment all adopt a hysteresis design. By setting the start threshold higher than the exit threshold, the start condition is more stringent than the exit condition. Once the system enters the heating state, the detected quantity needs to change further beyond the hysteresis band before exiting, thereby eliminating critical oscillations and improving system stability and reliability.

[0061] After the above verification is passed, the motor controller, according to the fast charging or pulse heating mode command, controls the upper and lower bridge arms of the three-phase full-bridge circuit to switch synchronously on and off according to the three-phase common-mode current injection timing, thereby forming a high-frequency charging and discharging circuit between the power battery and the three-phase windings to heat the power battery. Simultaneously, the pulse heating frequency is adjusted based on the noise signal. That is, this embodiment proposes a closed-loop frequency modulation mechanism using a noise sensor to solve the problem of high motor noise and the inability to adaptively adjust it.

[0062] Specifically, noise sensor 4 is mounted on the housing of motor body 3, continuously collecting noise signals generated by the motor during pulse heating with a sampling period of 100ms, and transmitting the noise signals to motor controller 2 in real time. Motor controller 2 has a preset noise threshold. (The recommended default value for this threshold is 55dB). Users can calibrate and modify this threshold through the cockpit display screen 8 to suit different users' noise tolerance levels.

[0063] When pulse heating starts, motor controller 2 initializes the pulse heating frequency to the default initial frequency of 500Hz, and then operates according to the following closed-loop frequency modulation logic: motor controller 2 reads the noise signal output by noise sensor 4 at a period of 100ms, and compares the current noise value with the noise threshold. Comparison: If the current noise value exceeds The pulse heating frequency is then adjusted upwards by a preset step value Δf = 100Hz. After waiting 300ms (equivalent to 3 sampling periods), the noise signal is collected again and compared. If the noise still exceeds... Then continue searching upwards, increasing the frequency by 100Hz each step, until the noise signal does not exceed [the specified value]. Preferably, the adjustment range of the pulse heating frequency is limited to between 100Hz and 2000Hz. In this embodiment, the principle of upward search frequency modulation is as follows: at higher pulse frequencies, the amplitude of the winding current ripple decreases, the rate of change of the winding magnetic field decreases, and the resulting structural vibration excitation weakens, thus reducing motor noise; at the same time, as the frequency increases, the peak value of the charging and discharging current in each pulse cycle decreases, but the number of charging and discharging cycles increases, and the overall heating power remains at a reasonable level. Therefore, the system can automatically find the operating frequency point that meets the noise constraints under different temperatures and operating conditions, taking into account both heating efficiency and noise control, and solving the problem that existing solutions cannot adaptively adjust noise due to fixed frequency operation.

[0064] When the noise signal does not exceed Furthermore, when the current pulse heating frequency remains unchanged within a preset stable time, the motor controller 2 writes the current pulse heating frequency as the user-preferred frequency into the non-volatile storage area. Therefore, when the subsequent heating process starts, the motor controller 2 prioritizes reading this frequency as the initial frequency, skipping the search process starting from 500Hz, shortening the time required to reach the low-noise operating point, and improving the consistency of the user experience.

[0065] As a further implementation, this embodiment also designs a segmented storage mechanism for user-preferred frequencies. Specifically, considering the significant differences in internal resistance of the power battery 1 at different temperature ranges, the amplitudes of the charging and discharging currents generated at the same pulse frequency differ, thus affecting the vibration excitation characteristics of the motor windings and resulting in differences in the optimal low-noise frequency at different temperature ranges. Therefore, the non-volatile storage area of ​​the motor controller 2 stores the corresponding user-preferred frequencies in segments according to the battery temperature range, specifically divided into three temperature ranges: the first temperature range is -30℃ to -20℃, the second temperature range is -20℃ to -10℃, and the third temperature range is -10℃ to 0℃. During each heating process, once the preferred frequency within a certain temperature range is stably confirmed, it is written into the storage register corresponding to that range. When pulse heating is subsequently started, the motor controller 2 first reads the current battery temperature, automatically matches the corresponding temperature range based on the temperature value, and retrieves the user-preferred frequency stored in that range as the initial frequency; if a temperature range has not yet stored a preferred frequency, it starts with the default initial frequency of 500Hz, and completes the learning and writing of the preferred frequency for that range during this heating process. Therefore, the segmented storage mechanism enables the system to optimize the heating frequency for battery characteristics under different temperature conditions, further improving the accuracy and consistency of noise control.

[0066] Furthermore, this embodiment also introduces a stall-rotor heating (VIPTC heating) mode during charging. The motor controller controls the three-phase windings to continuously generate heat according to the issued stall-rotor heating mode command. The heat is conducted to the power battery through the thermal management system for heating.

[0067] Specifically, during the charging process, the battery management system 11 continuously monitors the battery temperature and charging power of the power battery 1. When the battery temperature falls below a first temperature threshold... When the charging power is lower than the preset percentage of the rated charging power (default value is 5℃) and the charging efficiency is insufficient (default value is 50% of the rated fast charging power), the battery management system 11 determines that the current charging efficiency is insufficient and the battery still needs to be kept warm, and sends a stall heating request to the vehicle controller 9. After receiving the stall heating request, the vehicle controller 9 switches the auxiliary heating enable command to status 03 (stall heating) and sends a stall heating command to the motor controller 2 through the vehicle communication bus. After receiving the stall heating command, the motor controller 2 controls the three-phase full-bridge circuit to inject a continuous DC bias current in the d-axis direction into the three-phase windings.

[0068] The control principle of the above-mentioned d-axis current injection is as follows: the current command is decomposed to the d-axis through vector control, so that the current flowing through the three-phase winding generates a magnetomotive force in a fixed direction in space. Under the action of this magnetomotive force, the rotor aligns to the d-axis direction and remains stationary (locked rotor). The winding is continuously supplied with DC bias current, and according to Joule's law, continuous heat is generated on the winding resistance. The heat is circulated and conducted to the power battery 1 through the coolant of the thermal management system 10, so as to achieve continuous heating and heat preservation of the power battery 1.

[0069] Meanwhile, during the stall heating process, the high-voltage circuit of the power battery 1 remains connected, and the main positive relay K1 and the main negative relay K2 remain open throughout the process to ensure that the charging process is uninterrupted and to achieve the function of charging and heating at the same time.

[0070] When the battery management system 11 detects that the battery temperature has reached the stall heating exit temperature... (This temperature is a calibrable parameter, with a default value of 25℃) or when a heating shutdown request is received, the vehicle controller 9 will switch the auxiliary heating enable command to status 00 (no heating request), and the motor controller 2 will exit the stall heating mode and resume normal charging.

[0071] Therefore, the stall heating mode compensates for the decrease in pulse heating efficiency as the temperature rises and the battery internal resistance decreases, forming a full-temperature range complement to the pulse heating mode and ensuring that the battery temperature is maintained within a suitable range throughout the charging process.

[0072] In summary, the system design proposed in this embodiment represents a creative improvement at both the structural and control levels: At the system topology level, the system proposed in this embodiment is suitable for single-motor architectures. It eliminates the need for any high-voltage current transmission lines or high-voltage switching switches outside the vehicle. It fully reuses the inherent three-phase full-bridge circuit and three-phase windings of the single motor. The motor controller 2 only controls the bridge arm switches of the single-motor three-phase full-bridge circuit, synchronously turning on / off the upper bridge arm switches S1, S3, and S5, and the lower bridge arm switches S2, S4, and S6, according to the three-phase common-mode current injection sequence. This allows for the autonomous construction of a high-frequency charging and discharging circuit between the three-phase windings and the power battery 1, achieving pulse heating. Because the three-phase common-mode current injection sequence makes the current direction and magnitude in the three-phase windings completely symmetrical, the resulting magnetomotive forces cancel each other out, the net torque on the rotor is zero, the motor remains stationary, and no mechanical output is generated. No additional switching devices are needed to achieve zero torque. This extremely simplified topology design allows this embodiment to seamlessly integrate with single-motor (front-wheel drive or rear-wheel drive) and dual-motor vehicles, exhibiting extremely high platform versatility without adding any additional high-voltage hardware costs.

[0073] In terms of noise control, this embodiment introduces a noise sensor to form a closed-loop frequency modulation control loop: the motor controller continuously reads the noise signal output by the noise sensor with a sampling period of 100ms and compares it with a preset noise threshold. (Default 55dB) is compared. When the noise exceeds the standard, the pulse heating frequency is searched and adjusted upwards in steps Δf=100Hz until the noise drops below the threshold. At the same time, the temperature segment register is used to remember the user's preferred frequency in each temperature range (-30℃ to -20℃, -20℃ to -10℃, -10℃ to 0℃), and it is called first during subsequent startup. This fundamentally suppresses the pulse heating noise and solves the technical defect of the comparison scheme that the noise cannot be adaptively adjusted due to the fixed frequency operation.

[0074] At the heating mode level, compared to the traditional single oscillation heating mode which is difficult to adapt to the efficient heating requirements of the battery throughout the entire process from low temperature to target temperature, this embodiment designs a dual-mode adaptive switching mechanism of pulse heating and VIPTC stall heating: in the low temperature range, efficient pulse heating is performed by utilizing the high internal resistance of the power battery 1; when the battery temperature is lower than the first temperature threshold during charging... (Default 5℃) When the charging power is less than 50% of the rated charging power, the battery management system 11 triggers a stall heating request. The vehicle controller 9 switches the auxiliary heating enable command to state 03 (stall heating). The motor controller 2 controls the three-phase winding to inject a continuous DC bias current in the d-axis direction, causing the motor to enter a stall condition and continuously generate heat. The heat is circulated and conducted to the power battery 1 through the coolant of the thermal management system 10. When the battery temperature reaches the stall heating exit temperature... (Default 25℃, calibrable) Exits stall heating mode. Thus, pulse heating and stall heating complement each other across the entire temperature range, ensuring that the power battery 1 can maintain an effective heating rate at all temperature stages, overcoming the inherent defect of reduced heating efficiency in the high-temperature range of a single oscillation heating mode.

[0075] Example 2 like Figure 2 As shown, this embodiment proposes a heating control method for an electric vehicle power battery, applied to the aforementioned electric vehicle power battery heating control system. This method can be collaboratively executed by control units such as the motor controller 2, vehicle controller 9, and battery management system 11 within the system. It should be understood that this method may also include additional actions not shown, and the scope of this application is not limited in this respect.

[0076] The electric vehicle power battery heating control method proposed in this embodiment specifically includes the following steps: Step S101: Receive heating request, wake up the system, and execute the system high-voltage power-on process.

[0077] Specifically, the user issues a heating request via control terminal 5 (mobile application terminal, cockpit display 8, or voice control system 7), or the battery management system 11 automatically issues a fast charging heating request after detecting that the battery temperature is lower than the charging access temperature when the charging gun is connected. In response to receiving the heating request, the vehicle communication unit 6 wakes up the vehicle controller 9 and the battery management system 11, and the vehicle controller 9 generates a high-voltage power-on command. The control system then executes the high-voltage power-on process, i.e.: The main negative relay K2 and the pre-charge relay K3 are closed first, and the power battery 1 performs current-limited charging on the DC bus support capacitor through the pre-charge resistor; the motor controller 2 monitors the bus voltage in real time. When the difference between the bus voltage and the voltage at the power battery 1 terminal is less than 5V, it is determined that the pre-charge is completed, the main positive relay K1 is closed, the pre-charge relay K3 is opened, and the system enters the high-voltage ready state.

[0078] After the high-voltage ready state is established, the vehicle controller 9 sets the auxiliary heating enable command to the corresponding status bit according to the heating request type, and sends a heating mode command to the motor controller 2 through the vehicle communication bus. This step ensures that the system has completed a safe high-voltage establishment process before entering the heating mode, preventing damage to components from the inrush current.

[0079] As one implementation method, this embodiment designs a multi-channel method for triggering heating requests. Specifically, this embodiment supports at least three heating request triggering methods: The first method is real-time triggering, where the user sends a heating request in real time through a mobile application terminal, cockpit display screen 8 or voice control system 7. After receiving the request, the vehicle communication unit 6 immediately wakes up the system to execute the heating process. The second method is a scheduled triggering method. The user sets the scheduled start time through the control terminal 5. The vehicle communication unit 6 automatically wakes up the vehicle controller 9 and battery management system 11 at the preset time point. The battery can be heated in advance without the user's presence, which is suitable for preheating scenarios before travel. The third method is automatic triggering when the charging gun is connected. After the charging gun is inserted into the charging port, the battery management system 11 automatically detects the battery temperature. If it is lower than the charging threshold temperature, it will automatically issue a fast charging heating request. No manual operation by the user is required, thus realizing automatic linkage between charging and heating.

[0080] In another optional extended implementation, the system can also be linked with the vehicle navigation system to calculate the heating start time in advance based on the navigation destination and expected departure time set by the user, and automatically trigger the heating process before departure so that the battery has reached the optimal operating temperature when departing, thus achieving intelligent preheating.

[0081] It should be understood that the above triggering method is only an example and does not imply any limitation on the scope of protection of this application. Other methods that can send heating requests to the vehicle controller 9 through the vehicle communication unit 6 are also applicable. Thus, the multi-channel triggering method meets the control requirements in different usage scenarios, improves the flexibility of human-machine interaction of the system and the convenience of vehicle use in low-temperature environments.

[0082] By connecting the vehicle communication unit to a multi-channel remote control terminal that includes a mobile application terminal, a cockpit display screen, and a voice control system, as described above, users can remotely trigger battery heating from outside the vehicle in various ways. After the vehicle communication unit wakes up the vehicle controller and battery management system and completes high-voltage power-on, it automatically enters the heating process, improving the convenience of vehicle use in low-temperature environments. At the same time, the safety of remote start is ensured by jointly verifying the three access conditions: battery temperature, state of charge, and auxiliary battery voltage.

[0083] Step S102: Perform a three-item joint access verification on battery temperature, battery state of charge and auxiliary battery voltage. After the verification is passed, enter the pulse heating mode.

[0084] Specifically, after receiving the heating mode command (i.e., auxiliary heating enable command, with status bit 01 or 02) from the vehicle controller 9, the motor controller 2 performs a three-item joint access check on the battery temperature, battery state of charge, and auxiliary battery voltage. The specific check logic is as follows: Motor controller 2 reads the current battery temperature reported by battery management system 11. ,judge Is the battery temperature below the start-up threshold? ( (The values ​​are calibrable, ranging from -30℃ to -10℃); Simultaneously read the current SOC and determine whether the SOC is not lower than 30%; Simultaneously read the auxiliary battery voltage ,judge Is it not lower than 12.2V?

[0085] All three conditions must be met simultaneously for the verification to pass; if any condition is not met, the motor controller 2 will report the failure of the access verification to the vehicle controller 9, and will not start heating, waiting for the conditions to be met before re-verifying.

[0086] After the above three joint access verifications are passed, the motor controller 2 enters the pulse heating mode and feeds back the current heating status to the vehicle controller 9.

[0087] Step S103: In pulse heating mode, the upper and lower bridge arms of the three-phase full-bridge circuit are switched on and off synchronously according to the three-phase common-mode current injection timing control, so that a high-frequency charging and discharging circuit is formed between the power battery and the three-phase winding to heat the power battery; at the same time, the pulse heating frequency is adjusted according to the real-time noise signal.

[0088] Specifically, after entering the pulse heating mode, the motor controller 2 periodically controls the bridge arm switches of the three-phase full-bridge circuit according to the three-phase common-mode current injection timing. The control process is as follows: In the first stage, the three-phase upper bridge arm switches S1, S3, and S5 are turned on synchronously, and the three-phase lower bridge arm switches S2, S4, and S6 are turned off. The positive terminal of power battery 1 discharges to the three-phase windings through S1, S3, and S5. The winding current rises linearly from zero, and the windings store energy in the form of inductance. In the second stage, control S1, S3, and S5 are simultaneously disconnected, while S2, S4, and S6 are simultaneously turned on. The electrical energy stored in the winding is freewheeled through S2, S4, and S6 and charged to power battery 1, and the winding current decreases linearly. The first and second stages alternate in a cycle, forming a high-frequency charging and discharging circuit.

[0089] In the above process, the charging and discharging frequency is the same as the pulse heating frequency, and in this embodiment, its initial value is set to 500Hz. Through the above-described cyclic charging and discharging, the internal resistance of power battery 1... Continuous generation of Joule heat, thermal power Where I is the effective value of the charging and discharging current. This represents the internal resistance value at the current battery temperature. The three-phase common-mode current injection timing causes the combined magnetomotive forces of the three-phase windings to cancel each other out, keeping the rotor stationary. All electrical energy is used for battery heating, and no mechanical output is generated. Additionally, the DC bus support capacitor continuously absorbs the bus overvoltage caused by the induced electromotive force of the windings, protecting the bridge arm switching devices for safe operation.

[0090] Meanwhile, during the aforementioned pulse heating process, noise signals are collected in real time, and the pulse heating frequency is adjusted based on the noise signals to achieve closed-loop noise control. Specifically, during pulse heating mode operation, motor controller 2 continuously reads the noise signals collected by noise sensor 4 with a sampling period of 100ms and executes the following closed-loop frequency modulation logic: Compare the current noise value with the preset noise threshold (Default 55dB) Compare; if the current noise value exceeds... Then, the pulse heating frequency is adjusted upwards by a step value Δf = 100Hz. After waiting 300ms, the noise signal is collected again and compared. If the noise still exceeds... Then continue to increase the frequency by 100Hz each time, until the noise signal does not exceed [the specified frequency]. Up to this point; the pulse heating frequency adjustment range is limited to between 100Hz and 2000Hz. If the noise still exceeds the limit when searching upwards to 2000Hz, then maintain operation at 2000Hz and continue monitoring. Furthermore, when the noise signal does not exceed... After the current pulse heating frequency has remained stable for a preset time, the motor controller 2 writes the current pulse heating frequency as the user-preferred frequency into the register corresponding to the current battery temperature range in the non-volatile storage area (the three ranges of -30℃ to -20℃, -20℃ to -10℃, and -10℃ to 0℃ are stored independently). When the subsequent heating process starts, the motor controller 2 reads the current battery temperature, matches the corresponding temperature range, and prioritizes reading the user-preferred frequency stored in that range as the initial frequency, skipping the search process starting from 500Hz, and quickly entering a low-noise operating state.

[0091] As one implementation method, based on the above-mentioned pulse heating mode, this embodiment also designs a fast charging heating mode, the control flow of which is as follows: When the user connects the charging gun to the electric vehicle's charging port, the battery management system 11 automatically detects the current battery temperature. If the battery temperature is lower than the charging access temperature (i.e., the minimum temperature at which the battery is allowed to fast charge), the battery management system 11 sends a fast charging heating request to the vehicle controller 9. After receiving the fast charging heating request, the vehicle controller 9 sets the auxiliary heating enable command to status bit 01 and sends a fast charging heating command to the motor controller 2 via the vehicle communication bus. After receiving the fast charging heating command, the motor controller 2 performs the three-item joint access verification in step S102. After the verification is passed, it enters the pulse heating mode and heats the power battery 1 according to the process proposed in step S103, while simultaneously performing noise closed-loop frequency modulation.

[0092] During the heating process described above, the battery management system 11 continuously monitors the battery temperature. When the battery temperature reaches the charging access temperature, the battery management system 11 shuts down the fast charging heating request, the vehicle controller 9 switches the auxiliary heating enable command to state position 00, the motor controller 2 exits the pulse heating mode, stops the bridge arm switch action, and waits for a preset delay before the system enters the charging state and begins to fast charge the power battery 1.

[0093] In addition, during the transition from pulse heating to charging start, the high-voltage circuit of power battery 1 remains connected, and the main positive relay K1 and the main negative relay K2 remain open throughout the entire process.

[0094] Therefore, this embodiment can avoid frequent opening and closing of the relay, ensure seamless charging, and prevent the time delay caused by recharging after high voltage interruption, thus solving the problem that lithium iron phosphate batteries cannot be fast charged at low temperatures.

[0095] As a further implementation method, this embodiment also introduces a stall heating mode during the charging process, the complete control flow of which is as follows: During charging, the battery management system 11 continuously monitors the battery temperature and charging power of the power battery 1. When the battery temperature falls below a first temperature threshold... When the charging power is less than 50% of the rated charging power (default 5℃), the battery management system 11 determines that the current charging efficiency is insufficient and the battery needs continuous heat preservation, and sends a stall heating request to the vehicle controller 9. After receiving the stall heating request, the vehicle controller 9 sets the auxiliary heating enable command to status bit 03 and sends a stall heating command to the motor controller 2 through the vehicle communication bus. After receiving the stall heating command, the motor controller 2 waits 50ms to ensure that there is no residual current in the winding, and then controls the three-phase full-bridge circuit to inject a continuous DC bias current in the d-axis direction into the three-phase winding, so that the motor enters the stall condition. The three-phase winding is continuously supplied with DC bias current, generating continuous heat on the winding resistance. The circulation pump of the thermal management system 10 drives the coolant to circulate between the cooling water channels of the motor body 3 and the cooling water channels of the power battery 1, continuously conducting the heat generated by the winding to the power battery 1, realizing the heating and heat preservation of the power battery 1. The high-voltage circuit of the power battery 1 remains connected during the stall heating process, and the charging process is not interrupted, realizing simultaneous charging and heating and heat preservation. When the battery management system 11 detects that the battery temperature has reached (Default 25℃, calibrable) or upon receiving a request to turn off heating, the vehicle controller 9 switches the auxiliary heating enable command to state 00, and the motor controller 2 exits stall heating and resumes normal charging. Thus, the stall heating mode continues to provide effective heating and heat preservation capabilities even after the pulse heating efficiency decreases due to the reduction in battery internal resistance, achieving continuous and efficient heating across the entire temperature range.

[0096] Step S104: Real-time detection of exit conditions; when the exit conditions are met, exit the pulse heating mode and provide feedback on the heating status.

[0097] Specifically, during pulse heating mode operation, motor controller 2 simultaneously detects the following exit conditions in real time: 1) The battery temperature exceeds the exit threshold of 0°C for 3 consecutive seconds; 2) The battery state of charge drops below the exit threshold of 20%; 3) The auxiliary battery voltage drops below the exit threshold of 11.8V; 4) Received the auxiliary heating enable command status bit 00 (i.e. heating off command) issued by the vehicle controller 9.

[0098] When any of the above exit conditions are met, the motor controller 2 immediately stops pulse heating, controls all bridge arm switches to open, waits for the residual current in the winding to decay naturally, and then sends the current heating status feedback to the vehicle controller 9. The auxiliary heating enable command jumps to status position 00, and the system returns to the high voltage ready state.

[0099] In some embodiments, the battery temperature exit condition is provided with a 3-second anti-shake delay to prevent false exits caused by sensor noise; the SOC exit threshold (20%) is lower than the start-up threshold (30%), forming a 10% hysteresis band; the auxiliary battery voltage exit threshold (11.8V) is lower than the start-up threshold (12.2V), forming a 0.4V hysteresis band. Therefore, the above hysteresis design effectively prevents frequent switching of the heating state near the critical value, improving system operational stability.

[0100] Example 3 This embodiment provides a vehicle, which is an electric vehicle, including the above-described electric vehicle power battery heating control system, or a method for implementing the above-described electric vehicle power battery heating control method.

[0101] The steps involved in Examples 2 and 3 above correspond to those in Example 1. For specific implementation details, please refer to the relevant description section of Example 1.

[0102] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0103] The above description is only a preferred embodiment of the present invention. Although the specific embodiments of the present invention have been described in conjunction with the accompanying drawings, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A heating control system for a power battery of an electric vehicle, comprising a power battery, a motor controller, and a motor body, wherein the motor controller has a three-phase full-bridge circuit, the DC side of the three-phase full-bridge circuit is electrically connected to the power battery to form a high-voltage circuit, and the AC side is electrically connected to the three-phase windings of the motor body, characterized in that, Also includes: A noise sensor, mounted on the housing of the motor body, is used to collect noise signals and send them to the motor controller; Thermal management system, which connects the cooling circuit of the motor body with the cooling circuit of the power battery; The vehicle controller communicates with the motor controller, thermal management system, and control terminal to issue heating mode commands. The motor controller is used to: according to the fast charging or pulse heating mode command, control the upper and lower bridge arms of the three-phase full-bridge circuit to switch synchronously on and off according to the three-phase common-mode current injection timing, so that a high-frequency charging and discharging circuit is formed between the power battery and the three-phase winding to heat the power battery, and at the same time adjust the pulse heating frequency according to the noise signal; according to the stall heating mode command, control the three-phase winding to continuously generate heat, and the heat is conducted to the power battery through the thermal management system for heating.

2. The electric vehicle power battery heating control system according to claim 1, characterized in that, The motor controller is used to adjust the pulse heating frequency according to the noise signal, including: The noise signal is compared with a preset noise threshold. When the noise signal exceeds the noise threshold, the pulse heating frequency is adjusted upward by a preset step value until the noise signal does not exceed the noise threshold. When the noise signal does not exceed the noise threshold and the current pulse heating frequency remains stable for a preset time, the current pulse heating frequency is stored as the user-preferred frequency in the non-volatile storage area. When the subsequent heating process is started, the user-preferred frequency is preferentially used as the initial frequency of pulse heating.

3. The electric vehicle power battery heating control system according to claim 2, characterized in that, The non-volatile storage area stores the corresponding user preference frequencies in segments according to the battery temperature range; the motor controller is also used to automatically match the user preference frequency of the corresponding temperature range as the initial frequency when starting pulse heating.

4. The electric vehicle power battery heating control system according to claim 1, characterized in that, The system also includes a battery management system; the battery management system is communicatively connected to the vehicle controller and is used to detect battery temperature and charging power during charging, and generate corresponding heating requests based on the detection results, including: when the battery temperature is lower than a first temperature threshold and the charging power is lower than a preset ratio of the rated charging power, sending a stall heating request to the vehicle controller; The vehicle controller is used to send a stall heating command to the motor controller according to the stall heating request; The motor controller is used to control the three-phase winding to inject a continuous DC bias current in the d-axis direction according to the stall heating command, and the high-voltage circuit of the power battery remains connected during the stall heating process.

5. The electric vehicle power battery heating control system according to claim 1, characterized in that, Before executing the heating mode command, the motor controller performs three joint access checks. The three joint access checks include: battery temperature check, battery state of charge check, and auxiliary battery voltage check. Each check has a start threshold and an exit threshold, and there is a hysteresis interval between the start threshold and the exit threshold. The exit state transition can only be executed after the battery temperature signal meets the exit threshold condition for a preset delay.

6. The electric vehicle power battery heating control system according to claim 1, characterized in that, The system also includes an in-vehicle communication unit, which is communicatively connected to the vehicle controller and the control terminal. The control terminal includes at least one of a mobile application terminal, a cockpit display screen, and a voice control system. The in-vehicle communication unit is used to receive heating requests sent by the control terminal and transmit them to the vehicle controller, while simultaneously waking up the vehicle controller and the battery management system to execute the high-voltage power-on process.

7. The electric vehicle power battery heating control system according to claim 6, characterized in that, The vehicle controller is used to generate a heating mode command based on the received heating request, and send the heating mode command to the motor controller through the vehicle communication bus; the heating request includes fast charging heating request, battery heating request, and stall heating request, and the heating mode includes fast charging heating mode, pulse heating mode, and stall heating mode; when the motor controller switches between heating modes, it first switches the heating mode command to a state with no heating request, and then switches to the target mode heating command.

8. The electric vehicle power battery heating control system according to claim 1, characterized in that, The high-voltage circuit of the power battery has a main positive relay K1 and a main negative relay K2 connected in series. The main positive relay K1 is connected in parallel with a pre-charge branch, which includes a pre-charge relay K3 and a pre-charge resistor connected in series. When the system is powered on, the main negative relay K2 and the pre-charge relay K3 are closed first. After the difference between the bus voltage and the power battery terminal voltage is lower than a preset value, the main positive relay K1 is closed and the pre-charge relay K3 is opened, and the system enters the high-voltage ready state. A bus support capacitor is connected in parallel to the DC bus of the three-phase full-bridge circuit; during pulse heating, the bus support capacitor is used to absorb the bus overvoltage caused by the induced electromotive force of the three-phase winding.

9. A method for controlling the heating of a power battery in an electric vehicle, applied to the power battery heating control system of any one of claims 1 to 8, characterized in that, The battery is heated by charging and discharging the three-phase windings of the motor body under the control of the motor controller. This control method includes: Based on the received heating mode command, the battery temperature, battery state of charge and auxiliary battery voltage are first subjected to a three-item joint access verification. After the verification is passed, the pulse heating mode is entered. In pulse heating mode, the upper and lower bridge arms of the three-phase full-bridge circuit are switched on and off synchronously according to the three-phase common-mode current injection timing, so that a high-frequency charging and discharging circuit is formed between the power battery and the three-phase windings to heat the power battery; at the same time, the pulse heating frequency is adjusted according to the noise signal collected in real time. The system detects exit conditions in real time. When the exit conditions are met, it exits the pulse heating mode and provides feedback on the heating status.

10. The electric vehicle power battery heating control method according to claim 9, characterized in that, Adjusting the pulse heating frequency based on the noise signal includes: The noise signal is compared with a preset noise threshold. When the noise signal exceeds the noise threshold, the pulse heating frequency is adjusted upwards by a preset step value. After each step, the comparison is repeated after a preset judgment period until the noise signal does not exceed the noise threshold. When the noise signal does not exceed the noise threshold and the current pulse heating frequency remains stable for a preset time, the current pulse heating frequency is written as the user-preferred frequency to the non-volatile storage area. When the subsequent heating process starts, the user-preferred frequency is read as the initial frequency of pulse heating.

11. The electric vehicle power battery heating control method according to claim 9, characterized in that, In response to a user-triggered heating request, the system controllers are activated. The vehicle controller generates a high-voltage power-on command, and the control system executes the high-voltage power-on process. After the system enters the high-voltage ready state, the vehicle controller sends the corresponding heating mode command to the motor controller. The system defaults to a no-heating-request state; when a non-rechargeable battery heating request is received, it switches to the battery heating request state; when a fast-charging heating request is received, it switches to the fast-charging heating request state; when a stalled heating request is received during charging, it switches to the stalled heating request state. When exiting any heating mode, the heating mode command first jumps to a state with no heating request, and then executes subsequent actions.

12. The electric vehicle power battery heating control method according to claim 9, characterized in that, The control process for fast charging heating is as follows: When the battery management system detects that the battery temperature is lower than the charging access temperature, it sends a fast charging heating request to the vehicle controller. The vehicle controller then sends a fast charging heating command to the motor controller based on the fast charging heating request. The motor controller then enters the pulse heating mode to heat the power battery. When the battery management system detects that the battery temperature has reached the charging entry temperature, the motor controller exits the pulse heating mode and waits for a preset delay before the system enters the charging state. The high-voltage circuit of the power battery remains connected during the transition from exiting pulse heating to starting charging.

13. The electric vehicle power battery heating control method according to claim 12, characterized in that, The control process for stall heating during charging is as follows: During the charging process, when the battery management system detects that the battery temperature is lower than the first temperature threshold and the charging power is lower than the preset ratio of the rated charging power, it sends a stall heating request to the vehicle controller. The vehicle controller then sends a stall heating command to the motor controller. The motor controller controls the three-phase winding to inject a continuous DC bias current in the d-axis direction. The heat generated by the three-phase winding is conducted to the power battery through the thermal management system. The high-voltage circuit of the power battery remains connected during the stall heating process.

14. The electric vehicle power battery heating control method according to claim 9, characterized in that, The three joint access verifications include: The battery temperature start threshold is a calibrable value within the range of -30℃ to -10℃, and the exit threshold is 0℃. The exit state transition can only be executed after the battery temperature signal meets the exit threshold condition continuously for 3 seconds. The battery state of charge (SOC) threshold for starting up is no less than 30%, and the SOC threshold for stopping up is no more than 20%. The auxiliary battery voltage start-up threshold is not lower than 12.2V, and the stop-loss threshold is not higher than 11.8V.

15. A vehicle, characterized in that, The electric vehicle power battery heating control system includes any one of claims 1 to 8, or is used to implement any one of claims 9 to 14.

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