A method and apparatus for calibrating the current of a three-phase motor

Abstract

This application discloses a current calibration method and device for a three-phase motor, which has the following advantages: (1) High-precision calibration: By calibrating the three-phase current and bus current in stages, the sensor and line errors are fully compensated, and the current control accuracy is improved by 30%-50%; (2) Strong anti-interference ability: The calibration coefficient is processed by an encryption algorithm, which can effectively resist external interference and parameter drift, thereby improving the calibration stability by more than 25%; (3) Adaptable adjustment: The method supports online calibration and can dynamically adjust the calibration parameters according to the working state of the motor, which can adapt to various complex working conditions; (4) High safety and reliability: The method can ensure that the motor can maintain high precision under different load conditions through a dual working point calibration mechanism, thereby reducing the risk of motor failure; When the specific coefficient setting instruction or storage location is known but the coefficient writing encryption strategy is unknown, the coefficient cannot be maliciously modified, thereby protecting the controller.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, specifically to a current calibration method and apparatus for a three-phase motor. Background Technology

[0002] Three-phase motors are widely used in industrial production, electric vehicles, and other fields, and their current control accuracy directly affects the motor's performance and stability. However, due to factors such as sensor errors, changes in line impedance, and temperature drift, the actual motor current deviates from the control command, leading to decreased motor efficiency, increased heat generation, and even malfunctions. Traditional current calibration methods typically only calibrate for a single operating condition or a single current type (such as three-phase current or bus current), failing to comprehensively compensate for system errors. Furthermore, existing technologies lack effective encryption mechanisms, making calibration parameters susceptible to interference or tampering, affecting calibration accuracy and system security.

[0003] Therefore, how to design a high-precision and high-safety motor current control method is a technical problem to be solved. Summary of the Invention

[0004] Therefore, it is necessary to provide a current calibration method and device for a three-phase motor to address the problems of the existing technology.

[0005] In a first aspect, embodiments of this application provide a current calibration method for a three-phase motor, comprising the following steps:

[0006] S1: Receive current calibration command and switch the motor controller to the first state where the output current amplitude can be set;

[0007] S2: Make the motor work at the first operating point, which is the operating point that enables the motor's output current to reach the first preset requirement;

[0008] S3: Use the three-phase current at the first operating point as the first calibration current;

[0009] S4: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual three-phase current of the motor is obtained.

[0010] S5: Based on the first calibration current and the actual three-phase current, obtain the three-phase current calibration coefficient;

[0011] S6: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero;

[0012] S7: Make the motor work at the second operating point, which is the operating point that enables the motor's output current to reach the second preset requirement;

[0013] S8: Use the bus current at the second operating point as the second calibration current;

[0014] S9: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual bus current of the motor is obtained.

[0015] S10: Based on the second calibration current and the actual bus current, obtain the bus current calibration coefficient;

[0016] S11: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero;

[0017] S12: The current bus current of the motor is calibrated based on the bus current calibration coefficient, and the current three-phase current of the motor is calibrated based on the three-phase current calibration coefficient.

[0018] Preferably, the first preset requirement is that the three-phase current reaches 70%-100% of the peak current, and the three-phase current balance error is less than 5%.

[0019] Preferably, the second preset requirement is that the bus current reaches 70%-100% of the maximum bus current, and the duration is not less than 10 seconds.

[0020] Preferably, step S5 includes:

[0021] The first calibration current and the actual three-phase current are processed using a first encryption method to obtain the three-phase current calibration coefficient.

[0022] Preferably, the three-phase current calibration coefficient is expressed by the following formula:

[0023] (1);

[0024] (2);

[0025] (3);

[0026] in, For the U-phase current calibration coefficient, This is the calibration coefficient for the V-phase current. For the W-phase current calibration coefficient, This represents the actual U-phase current of the actual three-phase current. The actual current of phase V is the actual three-phase current. The actual current of phase W is the actual three-phase current. The U-phase calibration current is the first calibration current. The V-phase calibration current is the first calibration current. The W-phase calibration current is the first calibration current. For encryption coefficients, This is the encrypted offset value.

[0027] Preferably, step S10 includes:

[0028] The second calibration current and the actual bus current are processed using a second encryption method to obtain the bus current calibration coefficient.

[0029] Preferably, the bus current calibration coefficient is expressed by the following formula:

[0030] (4);

[0031] in, This is the bus current calibration coefficient. This represents the actual current at the busbar. For the second calibration current, For encryption coefficients, This is the encrypted offset value.

[0032] Preferably, step S12 includes:

[0033] The current is calibrated according to the following formula:

[0034] (5);

[0035] (6);

[0036] (7);

[0037] (8);

[0038] in, This is the U-phase current of the current three-phase current. This is the V-phase current of the current three-phase current. The current of phase W is the current of the current three phases. This is the current bus current. The U-phase current is the calibrated three-phase current. The V-phase current is the calibrated three-phase current. The W-phase current is the calibrated three-phase current. This is the calibrated bus current.

[0039] Preferably, the current in steps S4 and S9 is controlled to reach a stable state using the FOC algorithm.

[0040] Secondly, embodiments of this application provide a current calibration device for a three-phase motor, comprising:

[0041] The first instruction receiving unit is used to receive the current calibration instruction and switch the motor controller to the first state where the output current amplitude can be set.

[0042] The first operating condition execution unit is used to make the motor work at a first operating condition point, which is the operating point that enables the output current of the motor to reach a first preset requirement.

[0043] The first calibration current acquisition unit is used to take the three-phase current under the first operating condition as the first calibration current.

[0044] The actual three-phase current acquisition unit is used to acquire the actual three-phase current of the motor when the motor starts to work and continuously outputs current, and when the output current reaches a stable state.

[0045] The three-phase current calibration coefficient calculation unit is used to obtain the three-phase current calibration coefficient based on the first calibration current and the actual three-phase current.

[0046] The second instruction receiving unit is used to receive the instruction to restore normal mode, so that the motor's output current is cleared to zero.

[0047] The second operating condition execution unit is used to make the motor work at a second operating condition point, which is the operating point that enables the motor's output current to reach a second preset requirement.

[0048] The second calibration current acquisition unit uses the bus current at the second operating point as the second calibration current.

[0049] The actual bus current acquisition unit is used to acquire the actual bus current of the motor when the motor starts working and continuously outputs current and the output current reaches a stable state.

[0050] The bus current calibration coefficient calculation unit is used to obtain the bus current calibration coefficient based on the second calibration current and the actual bus current.

[0051] The third instruction receiving unit is used to receive the instruction to restore normal mode, so that the motor's output current is cleared to zero.

[0052] The output current calibration unit is used to calibrate the motor's bus current based on the bus current calibration coefficient and to calibrate the motor's three-phase current based on the three-phase current calibration coefficient.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) High-precision calibration: By calibrating the three-phase current and bus current in stages, the errors of sensors and lines are fully compensated, and the current control accuracy is improved by 30%-50%;

[0055] (2) Strong anti-interference ability: The calibration coefficient is processed by an encryption algorithm, which can effectively resist external interference and parameter drift, thereby improving the calibration stability by more than 25%;

[0056] (3) Adaptive adjustment: The method supports online calibration and can dynamically adjust calibration parameters according to the working status of the motor, which can adapt to various complex working conditions;

[0057] (4) High safety and reliability: The method can ensure that the motor can maintain high precision under different load conditions through the dual working point calibration mechanism, thereby reducing the risk of motor failure; even if the specific coefficient setting instructions or storage location are known, the coefficients cannot be maliciously modified when the coefficient writing encryption strategy is unknown, thereby protecting the controller. Attached Figure Description

[0058] Exemplary embodiments of the present invention can be more fully understood by referring to the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain the present invention and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0059] Figure 1 A flowchart illustrating a current calibration method for a three-phase motor provided as an exemplary embodiment of this application;

[0060] Figure 2 This is a schematic diagram of a current calibration device for a three-phase motor provided as an exemplary embodiment of this application. Detailed Implementation

[0061] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0062] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0064] Example 1

[0065] Reference Figure 1 This embodiment discloses a current calibration method for a three-phase motor, including the following steps:

[0066] S1: Receive current calibration command and switch the motor controller to the first state where the output current amplitude can be set;

[0067] Specifically, upon receiving the calibration command, the controller reconfigures the PWM generator register via the CAN communication protocol, switching the current loop control mode from closed-loop feedback to open-loop amplitude-adjustable mode. At this point, the current command resolution is increased to 1mA, meeting the requirements for high-precision calibration. This setting avoids interference from closed-loop feedback on the calibration current, ensuring that the consistency error between the calibration current and the command value is <0.5%. Specifically, this step changes the controller's current output mode, switching it from automatic output mode to a mode where the output current needs to be controlled by a command. In this mode, the current output becomes controllable, and subsequent current settings must be performed while the controller is in this mode.

[0068] S2: Enables the motor to operate at the first operating point, which is the operating point that enables the motor's output current to reach the first preset requirement.

[0069] Specifically, the operating conditions for the phase current and bus current output ramp-up differ, requiring separate calibration for each. The calibration target for the first preset point is the phase current. At this point, the operating condition must ensure the phase current output reaches the preset requirement value, i.e., the first operating point. The motor operates at this first operating point, ensuring the motor's output current meets the first preset requirement. This first operating point is a pre-selected point that ensures the current output meets the first preset requirement. Specifically, the first preset requirement is that the three-phase current reaches 70%-100% of the peak current, and the three-phase current balance error is less than 5%. This process can be controlled by adjusting the dq-axis current components using the FOC algorithm, allowing the motor to operate in a constant torque region (speed 1000-1500 rpm, load torque 150-200 Nm). This setting ensures the motor operates in a stable and representative operating range during calibration. Compared to the traditional 50% peak current calibration point, the three-phase current imbalance is reduced by 40% after calibration.

[0070] S3: Use the three-phase current at the first operating point as the first calibration current;

[0071] Specifically, the three-phase current at the first operating point is taken as the first calibration current, denoted as... , and , representing the calibration current values ​​for phase U, phase V, and phase W, respectively.

[0072] S4: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual three-phase current of the motor is obtained.

[0073] Specifically, the motor continuously outputs current, and when the current reaches a stable state, the actual three-phase current of the motor is collected and recorded as follows. , and This process can use the FOC algorithm to adaptively adjust the PI parameters of the inner current loop (proportional coefficient Kp dynamic range 0.8-1.2, integral coefficient Ki dynamic range 0.05-0.1), combined with sliding window filtering (window size 100ms). When the current fluctuation amplitude is <±2% for 500ms, it is considered stable.

[0074] Specifically, FOC (Field-Oriented Control), also known as Vector Control (VC), is one of the optimal methods for efficient control of brushless DC motors (BLDC) and permanent magnet synchronous motors (PMSM). FOC aims to achieve smooth torque, low noise, high efficiency, and high-speed dynamic response by precisely controlling the magnitude and direction of the magnetic field. Essentially, FOC is about "decoupling," decomposing the motor's three-phase current into two components: parallel (d-axis) and perpendicular (q-axis) to the rotor magnetic field. By controlling these two components, the motor's magnetic field and torque are precisely controlled. FOC controllers typically employ closed-loop control strategies, including current loop, speed loop, and position loop.

[0075] Current Loop: The three-phase current of the motor is detected by ADC sampling. The three-phase current is then converted into two-phase current through Clarke and Parker transformations. The converted two-phase current is then compared with a set current, and the output is adjusted by a PID controller to reduce error. The output of the PID controller is converted into a voltage signal acting on the motor, thereby controlling the magnitude and direction of the current to achieve precise magnetic field and torque control.

[0076] Speed ​​Loop: The speed loop is the intermediate loop in FOC control, located outside the current loop, forming a double closed-loop control system together. The main function of the speed loop is to compare the target speed with the actual speed. It obtains the actual motor speed through encoders, Hall effect sensors, etc., compares the actual speed with the target speed, and adjusts the output of the PID controller (adjusting the torque current (Iq) to reduce or eliminate this difference). This output directly serves as the setpoint for the current loop, which adjusts according to the speed loop's setpoint to control the motor speed.

[0077] S5: Based on the first calibration current and the actual three-phase current, obtain the three-phase current calibration coefficient;

[0078] Specifically, the first calibration current and the actual three-phase current are processed using a first encryption method to obtain the three-phase current calibration coefficients. The purpose is to improve the anti-interference capability of the calibration coefficients through normalization and parameter encryption. That is, to prevent malicious modification of the coefficients by others through certain means, which could cause abnormal current output from the controller, the program verifies the written coefficients; only those that pass the verification are saved and made available for subsequent use.

[0079] The formula for obtaining the three-phase current calibration coefficient using the first encryption method is as follows:

[0080] (1);

[0081] (2);

[0082] (3);

[0083] in, This is the encryption factor, and its value can range from 0.95 to 1.05. The encryption offset value can range from -0.05 to 0.05. This nonlinear transformation reduces the sensitivity of the calibration coefficient to sensor bias error by 50%. For example, when the sensor has a 5% bias, the calibration error using traditional methods is 5%, while the error using this invention is only 2.3%. Specifically, the purpose of encryption is to prevent external malicious modification of the coefficients through other means, which could lead to abnormal current output and thus affect the lifespan of the controller or even damage it. It is not directly related to the actual current output. Therefore, the encryption coefficient and encryption offset value do not have a specific range; both values ​​can be flexibly determined according to the difficulty of software calculation.

[0084] S6: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero;

[0085] Specifically, it receives a command to return to normal mode (i.e., a reset command), during which the motor's output current is cleared to zero to prepare for the next stage of calibration (i.e., the second stage of calibration).

[0086] S7: Enables the motor to operate at the second operating point, which is the operating point that allows the motor's output current to reach the second preset requirement;

[0087] Specifically, the calibration target for the second preset point is the bus current. The operating point at this time needs to ensure that the bus current output reaches the preset requirement value, i.e., the second operating point. The motor is then operated at this second operating point, where the motor's output current meets the second preset requirement. Specifically, the second preset requirement is that the bus current reaches 70%-100% of the maximum bus current, and the duration is no less than 10 seconds. This setting fully exposes the error characteristics of the bus current under high load. Under high bus current conditions, the current ripple (peak-to-peak value can reach 5-10A) caused by the bus parasitic inductance (approximately 10-20nH) and capacitance (approximately 100-220μF) can be fully exposed, improving the accuracy of the calibration.

[0088] S8: Use the bus current at the second operating point as the second calibration current;

[0089] Specifically, the bus current at the second operating point is taken as the second calibration current, denoted as... .

[0090] S9: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual bus current of the motor is obtained.

[0091] Specifically, the motor continuously outputs current until the current stabilizes (this stable state can be controlled by the FOC algorithm to keep the bus current fluctuation less than ±3%). In this stable state, the actual bus current is collected and recorded as follows: .

[0092] S10: Obtain the bus current calibration coefficient based on the second calibration current and the actual bus current;

[0093] Specifically, the second calibration current and the actual bus current are processed using a second encryption method to obtain the bus current calibration coefficient.

[0094] The formula for obtaining the bus current calibration coefficient using the second encryption method is as follows:

[0095] (4);

[0096] in, This is the bus current calibration coefficient. This represents the actual current at the busbar. For the second calibration current, For encryption coefficients, This is for encryption offset values. Specifically, the purpose of encryption is to prevent external malicious modification of the coefficients through other means, which could lead to abnormal current output and thus affect the lifespan or even damage the controller. It has no direct relationship with the actual current output. Therefore, there is no specific range for the encryption coefficient and encryption offset value. The two values ​​can be flexibly determined according to the difficulty of software calculation.

[0097] S11: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero;

[0098] Upon receiving the command to return to normal mode, the motor's output current is reset to zero, preparing for the final current calibration.

[0099] S12: The motor controller calibrates the current bus current of the motor based on the bus current calibration coefficient and calibrates the current three-phase current of the motor based on the three-phase current calibration coefficient.

[0100] Specifically, the motor controller calibrates the current according to the following formula:

[0101] (5);

[0102] (6);

[0103] (7);

[0104] (8);

[0105] in, This is the U-phase current of the current three-phase current. This is the V-phase current of the current three-phase current. The current of phase W is the current of the current three phases. This is the current bus current. The U-phase current is the calibrated three-phase current. The V-phase current is the calibrated three-phase current. The W-phase current is the calibrated three-phase current. This is the calibrated bus current.

[0106] Compared with the prior art, the present invention has the following beneficial effects:

[0107] (1) High-precision calibration: By calibrating the three-phase current and bus current in stages, the errors of sensors and lines are fully compensated, and the current control accuracy is improved by 30%-50%;

[0108] (2) Strong anti-interference ability: The calibration coefficient is processed by an encryption algorithm, which can effectively resist external interference and parameter drift, thereby improving the calibration stability by more than 25%;

[0109] (3) Adaptive adjustment: The method supports online calibration and can dynamically adjust calibration parameters according to the working status of the motor, which can adapt to various complex working conditions;

[0110] (4) High safety and reliability: The method can ensure that the motor can maintain high precision under different load conditions through a dual working point calibration mechanism, thereby reducing the risk of motor failure.

[0111] Example 2

[0112] Based on the same inventive concept, this application also provides an apparatus for implementing the aforementioned method for calibrating the current of a three-phase motor. The solution provided by this apparatus is similar to the solution described in the above method. Therefore, the specific limitations in the following embodiments of the three-phase motor current calibration apparatus can be found in the limitations of the three-phase motor current calibration method described above, and will not be repeated here.

[0113] Reference Figure 2 This application discloses a current calibration device 20 for a three-phase motor, comprising:

[0114] The first instruction receiving unit 201 is used to receive a current calibration instruction and switch the motor controller to a first state in which the output current amplitude can be set.

[0115] The first operating condition execution unit 202 is used to make the motor work at a first operating condition point, which is the operating point that enables the output current of the motor to reach a first preset requirement.

[0116] The first calibration current acquisition unit 203 is used to take the three-phase current under the first operating condition as the first calibration current.

[0117] The actual three-phase current acquisition unit 204 is used to acquire the actual three-phase current of the motor when the motor starts to work and continuously outputs current and the output current reaches a stable state.

[0118] The three-phase current calibration coefficient calculation unit 205 is used to obtain the three-phase current calibration coefficient based on the first calibration current and the actual three-phase current.

[0119] The second instruction receiving unit 206 is used to receive the instruction to restore normal mode, so that the output current of the motor is cleared to zero.

[0120] The second operating condition execution unit 207 is used to make the motor work at a second operating condition point, which is the operating point that enables the motor's output current to reach a second preset requirement.

[0121] The second calibration current acquisition unit 208 uses the bus current at the second operating point as the second calibration current.

[0122] The actual bus current acquisition unit 209 is used to acquire the actual bus current of the motor when the motor starts to work and continuously outputs current and the output current reaches a stable state.

[0123] The bus current calibration coefficient calculation unit 210 is used to obtain the bus current calibration coefficient based on the second calibration current and the actual bus current.

[0124] The third instruction receiving unit 211 is used to receive the instruction to restore normal mode, so that the output current of the motor is cleared to zero.

[0125] The output current calibration unit 212 is used by the motor controller to calibrate the motor bus current based on the bus current calibration coefficient and to calibrate the motor three-phase current based on the three-phase current calibration coefficient.

[0126] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0127] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0128] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0129] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0130] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0131] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application.

Claims

1. A current calibration method for a three-phase motor, characterized in that, Includes the following steps: S1: Receive current calibration command and switch the motor controller to the first state where the output current amplitude can be set; S2: Make the motor work at the first operating point, which is the operating point that enables the motor's output current to reach the first preset requirement; S3: Use the three-phase current at the first operating point as the first calibration current; S4: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual three-phase current of the motor is obtained. S5: Based on the first calibration current and the actual three-phase current, obtain the three-phase current calibration coefficient; S6: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero; S7: Make the motor work at the second operating point, which is the operating point that enables the motor's output current to reach the second preset requirement; S8: Use the bus current at the second operating point as the second calibration current; S9: The motor starts working and continuously outputs current. When the output current reaches a stable state, the actual bus current of the motor is obtained. S10: Based on the second calibration current and the actual bus current, obtain the bus current calibration coefficient; S11: Receives the command to restore normal mode, causing the motor's output current to be cleared to zero; S12: The current bus current of the motor is calibrated based on the bus current calibration coefficient, and the current three-phase current of the motor is calibrated based on the three-phase current calibration coefficient. The first preset requirement is that the three-phase current reaches 70%-100% of the peak current and the three-phase current balance error is less than 5%; the second preset requirement is that the bus current reaches 70%-100% of the maximum bus current and the duration is not less than 10 seconds.

2. The method according to claim 1, characterized in that, Step S5 includes: The first calibration current and the actual three-phase current are processed using a first encryption method to obtain the three-phase current calibration coefficient.

3. The method according to claim 2, characterized in that, The three-phase current calibration coefficient is expressed by the following formula: （1）； （2）； （3）； in, For the U-phase current calibration coefficient, This is the calibration coefficient for the V-phase current. For the W-phase current calibration coefficient, This represents the actual U-phase current of the actual three-phase current. The actual current of phase V is the actual three-phase current. The actual current of phase W is the actual three-phase current. The U-phase calibration current is the first calibration current. The V-phase calibration current is the first calibration current. The W-phase calibration current is the first calibration current. For encryption coefficients, This is the encrypted offset value.

4. The method according to claim 3, characterized in that, Step S10 includes: The second calibration current and the actual bus current are processed using a second encryption method to obtain the bus current calibration coefficient.

5. The method according to claim 4, characterized in that, The bus current calibration coefficient is expressed by the following formula: （4）； in, This is the bus current calibration coefficient. This represents the actual current at the busbar. For the second calibration current, For encryption coefficients, This is the encrypted offset value.

6. The method according to claim 5, characterized in that, Step S12 includes: The current is calibrated according to the following formula: （5）； （6）； （7）； （8）； in, This is the U-phase current of the current three-phase current. This is the V-phase current of the current three-phase current. The current of phase W is the current of the current three phases. This is the current bus current. The U-phase current is the calibrated three-phase current. The V-phase current is the calibrated three-phase current. The W-phase current is the calibrated three-phase current. This is the calibrated bus current.

7. The method according to claim 1, characterized in that, The FOC algorithm controls the current in steps S4 and S9 to reach a stable state.

8. A current calibration device for a three-phase motor, characterized in that, include: The first instruction receiving unit is used to receive the current calibration instruction and switch the motor controller to the first state where the output current amplitude can be set. The first operating condition execution unit is used to make the motor work at a first operating condition point, which is the operating point that enables the output current of the motor to reach a first preset requirement. The first calibration current acquisition unit is used to take the three-phase current under the first operating condition as the first calibration current. The actual three-phase current acquisition unit is used to acquire the actual three-phase current of the motor when the motor starts to work and continuously outputs current, and when the output current reaches a stable state. The three-phase current calibration coefficient calculation unit is used to obtain the three-phase current calibration coefficient based on the first calibration current and the actual three-phase current. The second instruction receiving unit is used to receive the instruction to restore normal mode, so that the motor's output current is cleared to zero. The second operating condition execution unit is used to make the motor work at a second operating condition point, which is the operating point that enables the motor's output current to reach a second preset requirement. The second calibration current acquisition unit uses the bus current at the second operating point as the second calibration current. The actual bus current acquisition unit is used to acquire the actual bus current of the motor when the motor starts working and continuously outputs current and the output current reaches a stable state. The bus current calibration coefficient calculation unit is used to obtain the bus current calibration coefficient based on the second calibration current and the actual bus current. The third instruction receiving unit is used to receive the instruction to restore normal mode, so that the motor's output current is cleared to zero. The output current calibration unit is used to calibrate the motor's bus current based on the bus current calibration coefficient and to calibrate the motor's three-phase current based on the three-phase current calibration coefficient. The first preset requirement is that the three-phase current reaches 70%-100% of the peak current and the three-phase current balance error is less than 5%; the second preset requirement is that the bus current reaches 70%-100% of the maximum bus current and the duration is not less than 10 seconds.

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