Control methods, devices, power systems and electric vehicles

Abstract

This application provides a control method, device, power system, and electric vehicle. The method is applied to a motor controller in the power system, which also includes a power battery, a motor, and an inverter. The method includes: when the cell temperature of the power battery meets a preset power battery heating condition, sending a first control signal to the inverter; wherein the first control signal is used to control the inverter to convert the electricity provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power the motor.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202011554389.6, filed on December 24, 2020, entitled “Control Method, Apparatus, Power System and Electric Vehicle”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a control method, device, power system and electric vehicle. Background Technology

[0004] Due to the limitations of the materials used in power batteries, they can only achieve optimal performance at rated ambient temperature. Therefore, when using electric vehicles in areas with low ambient temperatures, the power battery needs to be heated to the rated ambient temperature.

[0005] Technicians typically heat the power battery directly using a motor. Specifically, a closed loop is formed between the power battery and the stator winding of the motor, and electrical energy is stored in the stator winding. The stator winding of the motor applies alternating current to the power battery, causing the power battery to heat itself using its internal resistance. Since the internal resistance of the power battery is usually large in low-temperature environments, it can be heated to the rated ambient temperature quickly.

[0006] However, the noise level is often too high when using an electric motor to heat the power battery. Summary of the Invention

[0007] This application provides a control method applied to a motor controller in a power system. The power system also includes a power battery, a motor, and an inverter. The method includes: when the cell temperature of the power battery meets a preset power battery heating condition, sending a first control signal to the inverter; wherein the first control signal is used to control the inverter to convert the electricity provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power the motor.

[0008] In some embodiments, before sending the first control signal, the method further includes: randomly generating a plurality of set frequencies and determining the duration of each set frequency according to each set frequency; determining a reference value sequence for the d-axis component according to the set frequencies and the duration of each set frequency, and setting the reference signal sequence for the q-axis component to a zero sequence; and generating the first control signal according to the reference value sequence for the d-axis component, the reference value sequence for the q-axis component, and the motor parameters of the motor.

[0009] In the above embodiments, multiple set frequencies are randomly generated, and the duration of each set frequency is determined according to each set frequency. Then, a first control signal is generated according to the set frequency and the duration of the set frequency to control the inverter to convert the current of the power battery into alternating current with randomly changing frequency. By introducing new frequency components, the previously concentrated radial electromagnetic force is evenly distributed to the entire stator, reducing the vibration noise during the power battery heating process.

[0010] In some embodiments, determining the duration of each set frequency based on each set frequency includes: using the entire cycle duration corresponding to the set frequency as the duration of the set frequency; or, using half a cycle duration corresponding to the set frequency as the duration of the set frequency.

[0011] In the above embodiments, the duration of the set frequency is set to half a cycle or the entire cycle length corresponding to the set frequency, which facilitates the detection of the AC power used to drive the motor, real-time adjustment of the control signal, and ensures noise suppression effect.

[0012] In some embodiments, the method further includes: when the cell temperature of the power battery meets the preset power battery heating conditions, sending a second control signal to the inverter; wherein the second control signal is used to control the inverter to convert the electricity provided by the power battery into alternating current with a periodic amplitude variation, and the alternating current with a periodic amplitude variation is used to power the motor.

[0013] In the above embodiments, when the cell temperature of the power battery meets the power battery heating conditions, a first control signal and a second control signal are sent to the inverter to control the inverter to convert the current of the power battery into alternating current with randomly changing frequency and periodically changing amplitude, introducing new frequency components and further reducing the vibration noise of the power battery during the heating process.

[0014] In some embodiments, before sending the second control signal, the method further includes: determining a plurality of set amplitudes and the duration of each set amplitude based on the heating parameters of the power battery and the maximum noise threshold; determining a reference value sequence of the d-axis component based on the set amplitudes and the duration of each set amplitude, and setting the reference value sequence of the q-axis component to a zero sequence; and generating the second control signal based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the motor.

[0015] In the above embodiments, when the cell temperature of the power battery meets the battery self-heating conditions, multiple set amplitudes and the duration of each set amplitude are determined according to the heating parameters of the power battery and the maximum noise threshold. A second control signal is generated according to the set amplitude and duration. Under the joint control of the first control signal and the second control signal, the inverter converts the current provided by the power battery into alternating current with randomly changing frequency and periodically changing amplitude. By introducing more frequency components, the originally concentrated radial electromagnetic force is evenly distributed to the entire stator, which greatly reduces the vibration noise during the power battery heating process.

[0016] In some embodiments, the heating parameters include heating rate and heating duration.

[0017] In some embodiments, the amplitude reference values ​​in the reference value sequence of the d-axis component periodically increase or decrease.

[0018] In some embodiments, when the cell temperature of the power battery meets the preset power battery heating conditions, sending a first control signal to the inverter includes: when the cell temperature of the power battery is lower than the minimum operating temperature of the power battery and the motor is in a non-driving operation state, sending a first control signal to the inverter.

[0019] In the above embodiment, the motor controller specifically sends a first control signal to the inverter when the cell temperature of the power battery is lower than the minimum operating temperature of the power battery and the output torque of the motor is approximately 0, that is, when heating is required to make the power battery work normally and the motor is not rotating. This can avoid affecting the normal operation of the motor and thus effectively improve the safety of motor operation.

[0020] Secondly, this application provides a control device for sending a first control signal to an inverter when the cell temperature of a power battery meets a preset power battery heating condition; wherein the first control signal is used to control the inverter to convert the electricity provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power a motor.

[0021] Thirdly, this application provides a power system, including: a power battery, an inverter, a motor, and a motor controller, wherein the motor controller is used to execute the control methods involved in the first aspect and the alternative solutions.

[0022] Fourthly, this application provides an electric vehicle, including a power system, which includes a power battery, an inverter, a motor, and a motor controller, the motor controller being used to execute the control methods involved in the first aspect and the optional scheme.

[0023] This application provides a control method, device, power system, and electric vehicle. When the cell temperature of the power battery meets the heating conditions, a first control signal is sent to the inverter. This first control signal controls the inverter to convert the current from the power battery into alternating current with randomly varying frequency. This randomly varying frequency alternating current supplies power to the motor. By introducing a new frequency component, the previously concentrated radial electromagnetic force is evenly distributed across the entire stator, reducing vibration noise during the power battery heating process. Additionally, a first control signal and a second control signal are sent to the inverter to control it to convert the current from the power battery into alternating current with randomly varying frequency and periodically varying amplitude, introducing a new frequency component to further reduce vibration noise during the power battery heating process. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the power system provided in an embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the structure of the power battery provided in the embodiments of this application;

[0027] Figure 3 This is a flowchart illustrating the control method provided in an embodiment of this application;

[0028] Figure 4 This is a schematic flowchart of the vector control process for a permanent magnet motor provided in an embodiment of this application;

[0029] Figure 5 This is a schematic diagram of the alternating current used to drive the motor provided in an embodiment of this application;

[0030] Figure 6 This is a schematic diagram of one working state of the power system provided in the embodiments of this application;

[0031] Figure 7 This is a schematic diagram of another working state of the power system provided in the embodiments of this application;

[0032] Figure 8 This is a schematic diagram of the alternating current used to drive the motor provided in an embodiment of this application;

[0033] Figure 9 This is a schematic diagram of the control device provided in the embodiments of this application.

[0034] The accompanying drawings are not drawn to scale. Detailed Implementation

[0035] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0036] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0037] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] Electric vehicles are vehicles powered by batteries. For example... Figure 1 As shown, the power system 100 of an electric vehicle includes a power battery 10, an inverter 20, a motor 30, and a motor controller unit (MCU) 40. The motor 30 can be a permanent magnet motor. The positive and negative terminals of the power battery 10 are connected to the DC side of the inverter 20, and the AC side of the inverter 20 is connected to the stator winding of the motor 30. The power battery 10 supplies power to the motor through the inverter 20. The MCU 40 has multiple input terminals for receiving motor operating status data and sending motor control signals. Based on the motor control signals, motor operating status data, and power battery operating status data, the MCU 40 generates a pulse width modulation (PWM) signal to control the voltage and current supplied by the inverter 20 to the motor 30, thereby controlling the speed of the motor 30 and achieving vehicle speed control.

[0039] like Figure 2 As shown, the power battery 10 includes a battery module 101, a battery management system (BMS) 102, and an auxiliary structure 103. The battery module 101 is composed of multiple power cells connected in series and parallel. The battery cells are the core components of the power battery and the source of its electrical energy. The main functions of the battery management system 102 are charge / discharge management, high-voltage control, battery status assessment, battery data acquisition, battery protection, and battery thermal management. The auxiliary structure 103 typically includes an external frame, electrical connection devices, and insulating components. The external frame protects and supports the battery module, the electrical connection devices connect to other electrical equipment, such as an inverter, and the insulating components provide insulation protection.

[0040] The thermal management function in the battery management system 102 is used to ensure that the power battery operates within a suitable temperature range. The thermal management function mainly achieves accurate measurement and monitoring of battery temperature, effective heat dissipation when the battery pack temperature is too high, rapid heating under low-temperature conditions, and ensuring a uniform temperature distribution within the battery pack. Rapid heating under low-temperature conditions refers to heating the power battery to its rated cell temperature when used in areas with low cell temperatures, so that the power battery can stably perform at its optimal level.

[0041] Existing power battery heating methods can be divided into indirect heating and direct heating. Indirect heating refers to heating the power battery by placing a heat source outside the battery. Indirect heating methods can include air heating, liquid heating, and heating film heating, etc. The heating rate of the battery will vary depending on the heat source. Since the battery is heated by an external heat source, heat loss will occur in the heat transfer medium; therefore, the efficiency of indirect heating is not high.

[0042] Direct heating refers to heating the power battery internally. A common direct heating method is heating through internal resistance. Specifically: a fixed motor rotor is connected to a PWM signal input to the inverter's control terminal, forming a closed loop between the power battery and the stator windings. The stator windings store electrical energy. Due to the inductive characteristics of the stator windings, they provide alternating current to the battery, which is then heated by the alternating current flowing through its own internal resistance. Because the internal resistance of the power battery is relatively high at low temperatures, its heating efficiency is high.

[0043] However, existing methods of heating via the internal resistance of the power battery involve the motor supplying heating current to the battery, using the stator windings as energy storage elements to achieve alternating bus current. This alters the magnetic field distribution during normal motor operation, causing an imbalance in internal forces and easily leading to vibration and noise. Consequently, the NVH (Noise, Vibration, and Harshness) three-phase performance of electric vehicles fails to meet standards. NVH is an abbreviation for Noise, Vibration, and Harshness, representing noise, vibration, and acoustic roughness, respectively, and is an important indicator for measuring vehicle comfort.

[0044] To address the aforementioned technical problems, this application provides a control method, device, power system, and electric vehicle. The inventive concept of this application is to control the q-axis current or q-axis voltage to zero, applying all voltage or current to the d-axis, resulting in zero motor output torque, and utilizing the motor's inductance for energy storage to achieve the battery's self-heating function. Based on controlling the motor's d-axis voltage or current to be a sine wave, additional current harmonic components are introduced by randomly varying the frequency of the d-axis voltage or current. This allows the radial electromagnetic force of the motor to be more evenly distributed on the stator during battery self-heating, thereby reducing motor noise during self-heating. Furthermore, by randomly varying the frequency of the d-axis voltage or current and periodically varying its amplitude, more current harmonic components can be introduced, further distributing the radial electromagnetic force evenly across the entire stator, significantly reducing vibration noise during the power battery heating process.

[0045] One embodiment of this application provides a control method, which is applied to... Figure 1 The motor controller MCU in the power system shown has a control method that includes: when the cell temperature of the power battery meets the preset power battery heating conditions, the MCU sends a first control signal to the inverter, wherein the first control signal is used to control the inverter to convert the electricity provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power the motor.

[0046] like Figure 3 As shown, one embodiment of this application provides a control method, which is applied to... Figure 1 The control method for the power system shown includes the following steps:

[0047] S201 and BMS obtain the cell temperature of the power battery.

[0048] Among them, a temperature sensor is deployed inside the power battery to monitor the cell temperature of the power battery in real time. The temperature sensor will transmit the detected cell temperature to the BMS.

[0049] S202. When the vehicle control unit (VCU) determines that the cell temperature meets the heating conditions of the power battery, it sends a heating command to the MCU, so that the MCU can send a first control signal to the inverter after receiving the heating command.

[0050] The heating condition for a power battery refers to the battery cell temperature being lower than the minimum operating temperature. If the battery cell temperature is lower than the minimum operating temperature, it means the battery cell temperature meets the heating condition. If the battery cell temperature is higher than or equal to the minimum operating temperature, it means the battery cell temperature does not meet the heating condition.

[0051] In some embodiments, the VCU sends a heating command to the MCU when it determines that the cell temperature meets the power battery heating conditions and the motor is in a non-drive operating state; or, the VCU sends a heating command to the MCU when it determines that the cell temperature is below the minimum operating temperature and the motor is in a non-drive operating state.

[0052] The first control signal is used to control the inverter to convert the current supplied by the power battery into AC power with a randomly varying frequency. The randomly varying frequency AC power is used to power the permanent magnet motor so that the power battery can use its own resistance to self-heat.

[0053] In the control method provided in this application embodiment, when the cell temperature of the power battery meets the battery self-heating condition, a first control signal is generated so that the inverter converts the current provided by the power battery into alternating current with randomly changing frequency. By introducing a new frequency component, the previously concentrated radial electromagnetic force is evenly distributed to the entire stator, thereby reducing the vibration noise during the power battery heating process.

[0054] Another embodiment of this application provides a control method, which is applied to... Figure 1 The control method for the power system shown includes the following steps:

[0055] S301 and BMS obtain the cell temperature of the power battery.

[0056] Among them, a temperature sensor is deployed inside the power battery to monitor the cell temperature of the power battery in real time. The temperature sensor will transmit the detected cell temperature to the BMS.

[0057] When S302 and VCU determine that the cell temperature meets the power battery heating conditions, they send a heating command to the MCU. After receiving the heating command, the MCU randomly generates multiple set frequencies and determines the duration of each set frequency.

[0058] When the cell temperature is lower than the minimum operating temperature of the power battery, multiple preset frequencies are randomly generated. This preset frequency is the frequency at which the current flows through the motor, meaning that the AC power of this preset frequency is used to power the motor.

[0059] One specific method for determining the duration of each set frequency is to use the entire cycle length corresponding to the set frequency as the duration of the set frequency. If the set frequency is f, then the entire cycle length corresponding to the set frequency is 1 / f, meaning that each set frequency lasts for one cycle length.

[0060] As another specific way to determine the duration of each set frequency, the duration of half a cycle corresponding to the set frequency is taken as the duration of the set frequency. If the set frequency is f, then the duration of half a cycle corresponding to the set frequency is 1 / 2f, that is, each set frequency lasts for half a cycle.

[0061] S303, the MCU determines the reference value sequence of the d-axis component based on the set frequency and the duration of each set frequency, and sets the reference signal sequence of the q-axis component to a zero sequence.

[0062] Wherein, the randomly generated set frequencies are f1, f2, ..., fn. The duration corresponding to the set frequency f1 is t11, the duration corresponding to the set frequency f2 is t12, ..., the duration corresponding to the set frequency fn is t1n.

[0063] The reference value sequence for the d-axis component contains multiple reference values, each of which includes an amplitude reference value component, a frequency reference value component, and a duration reference value component. The amplitude reference value component can also be any value I1, the frequency reference value component is a set frequency, and the duration reference value component is the duration corresponding to the set frequency. That is, the reference value sequence for the d-axis component is {(I1, f1, t11), (I1, f2, t12), ..., (I1, f1, t1n)}.

[0064] The reference value sequence for the q-axis component contains multiple reference values, each of which includes an amplitude reference value component, a frequency reference value component, and a duration reference value component. The amplitude, frequency, and duration reference value components are all zero. That is, the reference value sequence for the q-axis component is {0, 0, 0), (0, 0, 0), ..., (0, 0, 0)}.

[0065] S304, the MCU generates the first control signal based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the permanent magnet motor.

[0066] Among them, such as Figure 4As shown, the motor parameters of a permanent magnet motor include the motor's acceleration, speed, position, and stator current.

[0067] The MCU performs coordinate transformation on the stator current based on the motor's speed and position to obtain the real-time d-axis component and q-axis component of the stator current of the permanent magnet motor.

[0068] The MCU then generates the input values ​​for the first proportional-integral controller based on the real-time d-axis component of the stator current, the acceleration of the permanent magnet motor, and the reference value of the d-axis component of the stator current. The first proportional-integral controller outputs the d-axis reference value of the stator voltage.

[0069] The MCU then generates the input values ​​for the second proportional-integral controller based on the real-time q-axis component of the stator current and the reference value of the q-axis component. The second proportional-integral controller outputs the q-axis reference value of the stator voltage.

[0070] The MCU then performs coordinate transformation on the d-axis reference value of the stator voltage, the q-axis reference value of the stator voltage, the motor speed and position to obtain the reference value of the stator voltage, and generates the first control signal based on the reference value of the stator voltage. The first control signal is a space vector pulse width modulation signal (SVPWM).

[0071] When S305 and VCU determine that the cell temperature meets the power battery heating conditions, they send a heating command to the MCU, so that the MCU can send a first control signal to the inverter after receiving the heating command.

[0072] The first control signal is used to control the inverter to convert the current supplied by the power battery into alternating current with a randomly varying frequency. For example... Figure 5 As shown, the frequencies of the alternating current are f1, f2, ..., fn, respectively. The duration corresponding to frequency f1 is t11, the duration corresponding to frequency f2 is t12, ..., the duration corresponding to frequency fn is t1n, and the amplitude of the alternating current is I1.

[0073] Randomly varying alternating current is used to power the permanent magnet motor, enabling the battery to self-heat using its own resistance. The following describes the process of controlling the inverter to heat the battery:

[0074] like Figure 6As shown, the first control signal controls the inverter, and the MCU drives the closed power switching devices Sa on phase A arm, Sb' on phase B arm, and Sc' on phase C arm to form two discharge circuits. One discharge circuit is: power battery → Sa → stator winding U → stator winding V → Sb' → power battery; the other discharge circuit is: power battery → Sa → stator winding U → stator winding W → Sc' → power battery. The power battery discharges and converts electrical energy into electromagnetic energy on the three-phase stator windings. The electronic rotor remains stationary, the stator windings store energy, and the alternating bus current across the power battery terminals heats the battery.

[0075] At the next time interval, simultaneously disconnect the power switching device Sa on phase A arm, the power switching device Sb' on phase B arm, and the power switching device Sc' on phase C arm. Due to the characteristic that the current in the stator winding cannot change abruptly, the backflush current loop is as shown in the attached diagram. Figure 7 As shown, the two return current loops are: power battery → diode D2 → stator winding U → stator winding V → diode D3 → power battery, and power battery → diode D2 → stator winding U → stator winding W → diode D5 → power battery. During the discharge and charging processes of the stator windings in the motor, current flows through the power battery, thereby heating the battery pack.

[0076] The magnitude of the heating current in the discharge circuit is determined by the closing time of the power switch, which is the frequency f and duty cycle D of the control signal used to control the power switching device.

[0077] In the control method provided in this application embodiment, when the cell temperature of the power battery meets the battery self-heating condition, a set frequency is randomly generated, and the duration corresponding to each set frequency is determined according to the set frequency. A first control signal is generated according to the set frequency and duration so that the inverter converts the current supplied by the power battery into alternating current with the set frequency. By introducing a new frequency component, the previously concentrated radial electromagnetic force is evenly distributed to the entire stator, reducing the vibration noise during the power battery heating process.

[0078] Another embodiment of this application provides a control method, which is applied to... Figure 1 The control method for the power system shown includes the following steps:

[0079] S401 and BMS obtain the cell temperature of the power battery.

[0080] Among them, a temperature sensor is deployed inside the power battery to monitor the cell temperature of the power battery in real time. The temperature sensor will transmit the detected cell temperature to the BMS.

[0081] When S402 and VCU determine that the cell temperature meets the power battery heating conditions, they send a heating command to the MCU, so that the MCU can send a first control signal to the inverter after receiving the heating command.

[0082] Specifically, when the cell temperature is below the minimum operating temperature, a first control signal is sent to the inverter. This first control signal controls the inverter to convert the current supplied by the power battery into alternating current with a randomly varying frequency, which is then used to power the permanent magnet motor.

[0083] When the ambient temperature meets the preset power battery heating conditions, the S403 and MCU send a second control signal to the inverter.

[0084] Specifically, when the cell temperature is below the minimum operating temperature, a second control signal is also sent to the inverter. This second control signal controls the inverter to convert the current supplied by the power battery into alternating current with varying amplitude and periodicity, which is then used to power the permanent magnet motor.

[0085] like Figure 8 As shown, under the control of the first control signal and the second control signal, the inverter converts the current supplied by the power battery into alternating current with periodically varying amplitude and randomly varying frequency, so that the power battery can use its own resistance to self-heat.

[0086] In the control method provided in this application embodiment, when the cell temperature of the power battery meets the battery self-heating condition, a first control signal and a second control signal are generated so that the inverter converts the current provided by the power battery into alternating current with randomly changing frequency and periodically changing amplitude. By introducing more frequency components, the originally concentrated radial electromagnetic force is evenly distributed to the entire stator, which greatly reduces the vibration noise during the power battery heating process.

[0087] Another embodiment of this application provides a control method, which is applied to... Figure 1 The control method for the power system shown includes the following steps:

[0088] The S501 and BMS obtain the cell temperature of the power battery.

[0089] When S502 and VCU determine that the cell temperature meets the power battery heating conditions, they send a heating command to the MCU. After receiving the heating command, the MCU randomly generates multiple set frequencies and determines the duration of each set frequency.

[0090] S503: The MCU determines the reference value sequence of the d-axis component based on the set frequency and the duration of each set frequency, and sets the reference signal sequence of the q-axis component to a zero sequence.

[0091] S504: The MCU generates the first control signal based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the permanent magnet motor.

[0092] S505 and MCU send the first control signal to the inverter.

[0093] S501 to S505 have been described in detail in the above embodiments and will not be repeated here.

[0094] S506, the MCU determines multiple set amplitudes and the duration of each set amplitude based on the heating parameters of the power battery and the maximum noise threshold.

[0095] The heating parameters include heating rate and heating duration, while the maximum noise threshold refers to the vibration noise threshold of the motor. A larger amplitude setting results in a longer heating duration, a higher heating rate, and a shorter heating time.

[0096] When determining the set amplitude, the current amplitude Id0 corresponding to the heating rate required under constant amplitude and constant frequency conditions can be obtained. Multiple set amplitudes are generated using Id0 as the average value of the variable amplitude. The number of set amplitudes is not limited here.

[0097] S507, the MCU determines the reference value sequence of the d-axis component based on the set amplitude and the duration of each set amplitude, and sets the reference value sequence of the q-axis component to a zero sequence.

[0098] Wherein, if the amplitude is set to I1, I2, ..., In, the duration corresponding to the frequency I1 is set to t21, the duration corresponding to the frequency I2 is set to t22, ..., and the duration corresponding to the frequency In is set to t2n.

[0099] The reference value sequence for the d-axis component contains multiple reference values, each of which includes an amplitude reference value component, a frequency reference value component, and a duration reference value component. The frequency reference value component can also be any value f1, the amplitude reference value component is a set amplitude, and the duration reference value component is the duration corresponding to the set amplitude. That is, the reference value sequence for the d-axis component is {(I1, f1, t21), (I2, f1, t22), ..., (In, f1, t2n), (I1, f1, t21), (I2, f1, t22), ..., (In, f1, t2n), ...}.

[0100] The reference value sequence for the q-axis component contains multiple reference values, each of which includes an amplitude reference value component, a frequency reference value component, and a duration reference value component. The amplitude, frequency, and duration reference value components are all zero. That is, the reference value sequence for the q-axis component is {0, 0, 0), (0, 0, 0), ..., (0, 0, 0)}.

[0101] In one embodiment, the amplitude reference values ​​in the reference value sequence of the d-axis component increase or decrease sequentially, that is, I1≤I2…≤In, or I1≥I2…≥In. By using AC power with periodically increasing or decreasing amplitude to power the motor, more frequency components can be introduced, and the originally concentrated radial electromagnetic force can be evenly distributed to the entire stator, which greatly reduces the vibration noise during the power battery heating process.

[0102] S508 and MCU generate a second control signal based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the permanent magnet motor.

[0103] The permanent magnet motor's parameters include the motor's position, speed, acceleration, and stator current. The method for generating the second control signal is similar to... Figure 4 The description method is the same, so it will not be repeated here.

[0104] When the ambient temperature meets the preset power battery heating conditions, the S509 and MCU send a second control signal to the inverter.

[0105] Specifically, when the cell temperature is below the minimum operating temperature, a second control signal is also sent to the inverter. This second control signal controls the inverter to convert the current supplied by the power battery into alternating current with varying amplitude and periodicity, which is then used to power the permanent magnet motor.

[0106] The period of amplitude variation of alternating current is: .

[0107] In the control method provided in this application embodiment, when the cell temperature of the power battery meets the battery self-heating condition, a set frequency is randomly generated, and the duration corresponding to each set frequency is determined according to the set frequency. A first control signal is generated according to the set frequency and duration. Multiple set amplitudes and the duration of each set amplitude are determined according to the heating parameters of the power battery and the maximum noise threshold. A second control signal is generated according to the set amplitude and duration. Under the joint control of the first control signal and the second control signal, the inverter converts the current provided by the power battery into alternating current with randomly changing frequency and periodically changing amplitude. By introducing more frequency components, the originally concentrated radial electromagnetic force is evenly distributed to the entire stator, which greatly reduces the vibration noise during the power battery heating process.

[0108] like Figure 9As shown, this application provides a control device 600, which is used to send a first control signal to an inverter when the cell temperature of the power battery meets the preset power battery heating conditions; wherein, the first control signal is used to control the inverter to convert the electricity provided by the power battery into AC power with a randomly varying frequency, and the AC power with a randomly varying frequency is used to power the motor.

[0109] In one embodiment, the control device 600 includes:

[0110] The acquisition module 601 is used to acquire the cell temperature of the power battery.

[0111] The sending module 602 is used to send a heating command to the control module 603 when the cell temperature meets the preset power battery heating conditions.

[0112] The control module 603 is used to send a first control signal to the inverter after receiving a heating command. The first control signal is used to control the inverter to convert the current provided by the power battery into AC power with a randomly changing frequency. The AC power with a randomly changing frequency is used to power the permanent magnet motor.

[0113] In some embodiments, the control module 603 is further configured to: randomly generate a plurality of set frequencies, and determine the duration of each set frequency according to each set frequency; determine a reference value sequence of the d-axis component according to the set frequency and the duration of each set frequency, and set the reference signal sequence of the q-axis component to a zero sequence; and generate a first control signal according to the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the permanent magnet motor.

[0114] In some embodiments, the control module 603 is specifically configured to: use the entire cycle duration corresponding to the set frequency as the duration of the set frequency; or, use half a cycle duration corresponding to the set frequency as the duration of the set frequency.

[0115] In some embodiments, the sending module 602 is further configured to: when the cell temperature meets the preset power battery heating conditions, send a second control signal to the inverter, the second control signal being used to control the inverter to convert the current provided by the power battery into alternating current with varying amplitude and period, the alternating current with varying amplitude and period being used to power the permanent magnet motor.

[0116] In some embodiments, the control module 603 is further configured to: determine a plurality of set amplitudes and the duration of each set amplitude based on the heating parameters of the power battery and the maximum noise threshold; determine a reference value sequence of the d-axis component based on the set amplitudes and the duration of each set amplitude, and set the reference value sequence of the q-axis component to a zero sequence; and generate a second control signal based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the permanent magnet motor.

[0117] In some embodiments, the heating parameters include heating rate and heating duration.

[0118] In some embodiments, the amplitude reference values ​​in the reference value sequence of the d-axis component periodically increase or decrease.

[0119] In some embodiments, the control module 603 is further configured to: determine whether the cell temperature is lower than the minimum operating temperature of the power battery.

[0120] This application provides a power system including a power battery, an inverter, a motor, and a motor controller. The motor controller is used to execute the steps in the control method described in the above embodiments. However, frequency changes can induce a large amount of eddy current losses in the motor stator, rotor core, and permanent magnets, resulting in high motor heat generation. A heat dissipation device can be added to the motor to prevent it from burning out.

[0121] This application provides an electric vehicle, including a power system. The power system includes a power battery, an inverter, a motor, and a motor controller. The motor controller is used to execute the steps in the control method described in the above embodiments.

[0122] Although this application has been described with reference to some embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method applied to a motor controller in a power system, the power system further comprising a power battery, a motor, and an inverter, the method comprising: The cell temperature of the power battery is obtained. When the cell temperature of the power battery is lower than the minimum operating temperature of the power battery, multiple set frequencies are randomly generated, and the duration of each set frequency is determined according to each set frequency. The reference value sequence of the d-axis component is determined based on the set frequency and the duration of each set frequency, and the reference value sequence of the q-axis component is set to a zero sequence. A first control signal is generated based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the motor. When the cell temperature of the power battery meets the preset power battery heating conditions, the first control signal is sent to the inverter. The first control signal is used to control the inverter to convert the current provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power the motor.

2. The method according to claim 1, wherein, The step of determining the duration of each set frequency based on each set frequency includes: The duration of the set frequency is the entire cycle length corresponding to the set frequency; or, the duration of half a cycle length corresponding to the set frequency is the duration of the set frequency.

3. The method according to claim 1 or 2, wherein, The method further includes: When the cell temperature of the power battery meets the preset power battery heating conditions, a second control signal is sent to the inverter. The second control signal is used to control the inverter to convert the current provided by the power battery into alternating current with varying amplitude and periodicity, which is used to power the motor.

4. The method according to claim 3, wherein, Before sending the second control signal, the method further includes: Multiple set amplitudes and the duration of each set amplitude are determined based on the heating parameters and maximum noise threshold of the power battery. The reference value sequence of the d-axis component is determined based on the set amplitude and the duration of each set amplitude, and the reference value sequence of the q-axis component is set to a zero sequence. The second control signal is generated based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the motor.

5. The method according to claim 4, wherein, The heating parameters include heating rate and heating duration.

6. The method according to claim 4, wherein, The amplitude reference values ​​in the reference value sequence of the d-axis component periodically increase or decrease.

7. The method according to claim 1 or 2, wherein, When the cell temperature of the power battery meets the preset power battery heating conditions, sending a first control signal to the inverter includes: When the cell temperature of the power battery is lower than the minimum operating temperature of the power battery and the motor is in a non-driving operation state, the first control signal is sent to the inverter.

8. A control device for sending a first control signal to an inverter when the cell temperature of a power battery meets a preset power battery heating condition; wherein, The control device randomly generates multiple preset frequencies and determines the duration of each preset frequency based on each preset frequency; The reference value sequence of the d-axis component is determined based on the set frequency and the duration of each set frequency, and the reference value sequence of the q-axis component is set to a zero sequence. The first control signal is generated based on the reference value sequence of the d-axis component, the reference value sequence of the q-axis component, and the motor parameters of the motor. The first control signal is used to control the inverter to convert the current provided by the power battery into AC power with a randomly varying frequency, and the randomly varying frequency AC power is used to power the motor.

9. A power system, comprising: A power battery, an inverter, a motor, and a motor controller, wherein the motor controller is used to perform the control method as described in any one of claims 1 to 7.

10. An electric vehicle, comprising a power system including a power battery, an inverter, a motor, and a motor controller, the motor controller being configured to perform the control method as described in any one of claims 1 to 7.

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