Current calibration method and device for three-phase motor

Abstract

The invention discloses a current calibration method and device for a three-phase motor, and the method and device have the following beneficial effects: (1) high-precision calibration: three-phase current and bus current are calibrated in stages, sensor and line errors are comprehensively compensated, and the current control precision is improved by 30%-50%; (2) the anti-interference capability is strong: the calibration coefficient is processed by adopting an encryption algorithm, so that external interference and parameter drift can be effectively resisted, and the calibration stability is improved by more than 25%; (3) self-adaptive adjustment: the method supports online calibration, can dynamically adjust calibration parameters according to the working state of the motor, and can adapt to various complex working conditions; (4) the safety and the reliability are high: the method can ensure that the motor can keep high precision under different load conditions through a double-working-condition point calibration mechanism, so that the fault risk of the motor is reduced; when a specific coefficient setting instruction or a storage position is known, but a coefficient writing encryption strategy is not known, the coefficient cannot be maliciously modified, so that a controller is protected.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a current calibration method and device for a three-phase motor. Background Art

[0002] Three-phase motors are widely used in industrial production, electric vehicles, and other fields. The accuracy of their current control directly impacts the motor's performance and stability. However, due to factors such as sensor errors, line impedance variations, and temperature drift, the actual motor current can deviate from the control command, leading to reduced motor efficiency, increased heat generation, and even failure. Traditional current calibration methods typically only calibrate for a single operating condition or current type (such as three-phase current or bus current), failing to fully compensate for system errors. Furthermore, existing technologies lack effective encryption mechanisms, making calibration parameters susceptible to interference or tampering, compromising 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] Based on this, it is necessary to provide a current calibration method and device for a three-phase motor to address the problems of the prior art.

[0005] In a first aspect, an embodiment of the present application provides a current calibration method for a three-phase motor, comprising the following steps: S1: Receive a current calibration command and switch the motor controller to a first state where the output current amplitude can be set; S2: The motor is operated at a first operating point, where the first operating point is an operating point at which the output current of the motor reaches a first preset requirement; S3: Using the three-phase current at the first operating point as a first calibration current; S4: The motor starts to work and continuously outputs current, and when the output current reaches a stable state, the actual three-phase current of the motor is obtained; S5: Obtaining a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; S6: receiving the instruction to restore the normal mode, so that the output current of the motor is reset to zero; S7: operating the motor at a second operating point, where the second operating point is an operating point at which the output current of the motor reaches a second preset requirement; S8: Using the bus current at the second operating point as a second calibration current; S9: The motor starts to work and continuously outputs current, and when the output current reaches a stable state, the actual bus current of the motor is obtained; S10: Obtaining a bus current calibration coefficient based on the second calibration current and the actual bus current; S11: receiving a command to restore the normal mode, so that the output current of the motor is reset to zero; S12: Calibrate the current bus current of the motor based on the bus current calibration coefficient and calibrate the current three-phase current of the motor based on the three-phase current calibration coefficient.

[0006] 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%.

[0007] Preferably, the second preset requirement is that the bus current reaches 70%-100% of the maximum bus current and lasts for no less than 10 seconds.

[0008] Preferably, step S5 includes: The first calibration current and the actual three-phase current are processed in a first encryption manner to obtain a three-phase current calibration coefficient.

[0009] Preferably, the three-phase current calibration coefficient is expressed by the following formula: (1); (2); (3); in, is the U-phase current calibration coefficient, is the V-phase current calibration coefficient, is the W phase current calibration coefficient, is the actual current of phase U of the actual three-phase current, is the actual current of phase V of the actual three-phase current, is the actual current of phase W of the actual three-phase current, is the U-phase calibration current of the first calibration current, is the V-phase calibration current of the first calibration current, is the W-phase calibration current of the first calibration current, is the encryption coefficient, The encryption offset value.

[0010] Preferably, step S10 includes: The second calibration current and the actual bus current are processed by a second encryption method to obtain a bus current calibration coefficient.

[0011] Preferably, the bus current calibration coefficient is expressed by the following formula: (4); in, is the bus current calibration coefficient, is the actual bus current, is the second calibration current, is the encryption coefficient, The encryption offset value.

[0012] Preferably, step S12 includes: The current is calibrated according to the following formula: (5); (6); (7); (8); in, is the U-phase current of the current three-phase current, is the V phase current of the current three-phase current, is the W phase current of the current three-phase current, is the current bus current, is the U-phase current of the calibrated three-phase current, is the V-phase current of the calibrated three-phase current, is the W-phase current of the calibrated three-phase current, is the calibrated bus current.

[0013] Preferably, the current in steps S4 and S9 is controlled to reach a stable state by using a FOC algorithm.

[0014] In a second aspect, an embodiment of the present application provides a current calibration device for a three-phase motor, comprising: a first instruction receiving unit, configured to receive a current calibration instruction and switch the motor controller to a first state in which the output current amplitude can be set; a first operating condition execution unit, configured to enable the motor to operate at a first operating condition point, wherein the first operating condition point is an operating point at which the output current of the motor can reach a first preset requirement; a first calibration current acquiring unit, configured to use the three-phase current at the first operating point as a first calibration current; an actual three-phase current acquisition unit, configured 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; a three-phase current calibration coefficient calculation unit, configured to obtain a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; a second instruction receiving unit, configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; a second operating condition execution unit, configured to cause the motor to operate at a second operating condition point, wherein the second operating condition point is an operating point at which the output current of the motor can reach a second preset requirement; a second calibration current acquiring unit, which uses the bus current at the second operating point as the second calibration current; an actual bus current acquisition unit, configured to acquire the actual bus current of the motor when the motor starts to work and continuously outputs current, and when the output current reaches a stable state; a bus current calibration coefficient calculation unit, configured to obtain a bus current calibration coefficient based on the second calibration current and the actual bus current; a third instruction receiving unit, configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; An output current calibration unit is used to calibrate the bus current of the motor based on the bus current calibration coefficient and to calibrate the three-phase current of the motor based on the three-phase current calibration coefficient.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) High-precision calibration: By calibrating the three-phase current and bus current in stages, sensor and line errors are fully compensated, and current control accuracy is improved by 30%-50%; (2) Strong anti-interference ability: The calibration coefficient is processed using an encryption algorithm, which can effectively resist external interference and parameter drift, and improve the calibration stability by more than 25%; (3) Adaptive adjustment: The method supports online calibration and can dynamically adjust the calibration parameters according to the working status of the motor, which can adapt to various complex working conditions; (4) High security and reliability: The method uses a dual-operating point calibration mechanism to ensure that the motor can maintain high precision under different load conditions, thereby reducing the risk of motor failure; even if the specific coefficient setting instructions or storage location are known, the coefficient cannot be maliciously modified without knowing the coefficient write encryption strategy, thereby protecting the controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A more complete understanding of the exemplary embodiments of the present invention can be obtained by referring to the following drawings. The drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present invention and do not constitute a limitation of the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0017] Figure 1 A flow chart of a current calibration method for a three-phase motor provided by an exemplary embodiment of the present application; Figure 2 A schematic diagram of a current calibration device for a three-phase motor provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0018] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0019] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present 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.

[0020] In addition, 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.

[0021] Example 1 Reference Figure 1 This embodiment discloses a current calibration method for a three-phase motor, comprising the following steps: S1: Receive a current calibration command and switch the motor controller to a first state where the output current amplitude can be set; Specifically, after 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 of high-precision calibration. This setting avoids interference from closed-loop feedback on the calibration current and ensures that the consistency error between the calibration current and the command value is less than 0.5%. Specifically, the purpose of this step is to change the controller's current output mode, switching the current from automatic output mode to a mode in which the output current needs to be controlled by a command. In this mode, the current output becomes controllable, and subsequent current settings need to be performed in this mode.

[0022] S2: The motor is operated at a first operating point, where the first operating point is an operating point at which the output current of the motor reaches a first preset requirement; Specifically, the operating conditions under which phase current and bus current output ramp up differ, requiring separate calibration. The first preset calibration point targets the phase current. This operating point must meet the preset phase current output requirement, known as the first operating point. The motor is operated at this first operating point, which ensures the motor's output current meets the first preset requirement. This first operating point is selected through pre-testing to ensure that the current output meets the first preset requirement. Specifically, the first preset requirement requires that the three-phase currents reach 70%-100% of the peak current, with a three-phase current balance error of less than 5%. This process can be controlled by adjusting the dq-axis current components using the Field-Oriented Control (FOC) algorithm to maintain the motor's constant torque range (speed 1000-1500 rpm, load torque 150-200 Nm). This setup ensures that the motor operates within 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.

[0023] S3: taking the three-phase current at the first operating point as the first calibration current; Specifically, the three-phase current at the first operating point is taken as the first calibration current, which is recorded as 、 and , representing the calibration current values ​​of U phase, V phase and W phase respectively.

[0024] S4: The motor starts to work and continuously outputs current. When the output current reaches a stable state, the actual three-phase current of the motor is obtained; Specifically, the motor is made to continuously output current. When the current reaches a stable state, the actual three-phase power of the motor is collected and recorded as 、 and This process can be achieved by adaptively adjusting the current inner loop PI parameters of the FOC algorithm (dynamic range of the proportional coefficient Kp is 0.8-1.2, and the dynamic range of the integral coefficient Ki is 0.05-0.1), combined with sliding window filtering (window size 100ms). When the current fluctuation amplitude is less than ±2% for 500ms, it is determined to be stable.

[0025] Specifically, Field-Oriented Control (FOC), also known as vector control (VC), is currently one of the most optimized methods for efficient control of brushless DC motors (BLDC) and permanent magnet synchronous motors (PMSM). FOC aims to precisely control the magnitude and direction of the magnetic field, resulting in smooth motor torque, low noise, high efficiency, and fast dynamic response. Essentially, FOC is a form of decoupling. Based on the principle of field-oriented control, it decomposes 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 can be precisely controlled. FOC controllers typically employ a closed-loop control strategy, comprising a current loop, a velocity loop, and a position loop.

[0026] Current loop: The three-phase motor current is sampled using an ADC and converted to two-phase current using Clarke and Park transforms. The converted two-phase current is then compared with the set current, and the PID controller adjusts the output to minimize errors. The PID controller's output is converted into a voltage signal that applies to the motor, controlling the current magnitude and direction for precise magnetic field and torque control.

[0027] Speed ​​Loop: The speed loop is the middle loop in FOC control, located outside the current loop, forming a dual closed-loop control system with the current loop. The speed loop's main function is to compare the difference between the target speed and the actual speed. It obtains the motor's actual speed through encoders, Hall sensors, and other sensors, compares the actual speed with the target speed, and adjusts the output (adjusting the torque current (Iq) to reduce or eliminate this difference) through a PID controller. This output directly serves as the setpoint for the current loop, which then adjusts based on the speed loop's setpoint to control the motor's speed.

[0028] S5: Obtaining a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; 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. This is done by normalizing and encrypting the parameters to improve the calibration coefficients' resistance to interference. Specifically, to prevent malicious modification of the coefficients through certain means, which could cause abnormal controller current output, the program verifies the written coefficients and only saves them for subsequent use if they pass verification.

[0029] The formula for obtaining the three-phase current calibration coefficient using the first encryption method is as follows: (1); (2); (3); in, is the encryption coefficient, and its value range can be 0.95-1.05. The encrypted 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 of the traditional method is 5%, while the error of the present invention is only 2.3%. Specifically, the purpose of encryption is to prevent external malicious modification of the coefficient through other means, resulting in abnormal current output, which in turn affects the service life of the controller or even damages it. It has no direct relationship with the actual current output. Therefore, there is no specific range of values ​​for the encrypted coefficient and the encrypted offset value. The two values ​​can be flexibly formulated according to the difficulty of the software solution.

[0030] S6: receiving the instruction to restore the normal mode, so that the output current of the motor is reset to zero; Specifically, a command to restore the normal mode (ie, a reset command) is received, during which the output current of the motor is reset to zero, in preparation for the next stage of calibration (ie, the second stage of calibration).

[0031] S7: operating the motor at a second operating point, where the second operating point is an operating point at which the output current of the motor reaches a second preset requirement; Specifically, the calibration target of the second preset point is the bus current. The operating point at this time needs to satisfy the bus current output to reach the preset requirement value, that is, the second operating point; the motor is operated at the second operating point, which can make the output current of the motor reach 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 not less than 10 seconds. Such a setting can fully expose 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 bus parasitic inductance (about 10-20nH) and capacitance (about 100-220μF) can be fully exposed, improving the targeted calibration.

[0032] S8: Using the bus current at the second operating point as the second calibration current; Specifically, the bus current at the second operating point is used as the second calibration current, which is recorded as .

[0033] S9: The motor starts to work and continuously outputs current. When the output current reaches a stable state, the actual bus current of the motor is obtained; Specifically, the motor is made to continuously output current. After the current stabilizes (the bus current fluctuation can be controlled by the FOC algorithm to be less than ±3% in this stable state), the actual bus current is collected in this stable state and recorded as .

[0034] S10: Obtaining a bus current calibration coefficient based on the second calibration current and the actual bus current; Specifically, the second calibration current and the actual bus current are processed by a second encryption method to obtain a bus current calibration coefficient.

[0035] The formula for obtaining the bus current calibration coefficient using the second encryption method is as follows: (4); in, is the bus current calibration coefficient, is the actual bus current, is the second calibration current, is the encryption coefficient, This is the encryption offset value. Specifically, encryption is intended to prevent malicious external modification of the coefficients through other means, which could lead to abnormal current output and potentially affect the lifespan or even damage the controller. It has no direct relationship to the actual current output. Therefore, there is no specific range for the encryption coefficient and encryption offset value; both values ​​can be flexibly set to suit the difficulty of the software solution.

[0036] S11: receiving a command to restore the normal mode, so that the output current of the motor is reset to zero; Receive the command to resume normal mode again, reset the output current of the motor to zero, and prepare for the final current calibration.

[0037] 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.

[0038] Specifically, the motor controller calibrates the current according to the following formula: (5); (6); (7); (8); in, is the U-phase current of the current three-phase current, is the V phase current of the current three-phase current, is the W phase current of the current three-phase current, is the current bus current, is the U-phase current of the calibrated three-phase current, is the V-phase current of the calibrated three-phase current, is the W-phase current of the calibrated three-phase current, is the calibrated bus current.

[0039] Compared with the prior art, the present invention has the following beneficial effects: (1) High-precision calibration: By calibrating the three-phase current and bus current in stages, sensor and line errors are fully compensated, and current control accuracy is improved by 30%-50%; (2) Strong anti-interference ability: The calibration coefficient is processed using an encryption algorithm, which can effectively resist external interference and parameter drift, and improve the calibration stability by more than 25%; (3) Adaptive adjustment: The method supports online calibration and can dynamically adjust the calibration parameters according to the working status of the motor, which can adapt to various complex working conditions; (4) High safety and reliability: The method uses a dual operating point calibration mechanism to ensure that the motor can maintain high precision under different load conditions, thereby reducing the risk of motor failure.

[0040] Example 2 Based on the same inventive concept, an embodiment of the present application further provides a device for implementing the aforementioned method for calibrating a current of a three-phase motor. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of the following embodiment of the device for calibrating a current of a three-phase motor can be found in the aforementioned definition of the method for calibrating a current of a three-phase motor, and will not be further elaborated here.

[0041] Reference Figure 2 The embodiment of the present application discloses a current calibration device 20 for a three-phase motor, comprising: A first instruction receiving unit 201 is configured to receive a current calibration instruction and switch the motor controller to a first state in which the output current amplitude can be set; A first operating condition execution unit 202 is configured to enable the motor to operate at a first operating condition point, where the first operating condition point is an operating point at which the output current of the motor reaches a first preset requirement; A first calibration current acquisition unit 203 is configured to use the three-phase current at the first operating point as a first calibration current; 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 when the output current reaches a stable state; a three-phase current calibration coefficient calculation unit 205, configured to obtain a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; The second instruction receiving unit 206 is configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; A second operating condition execution unit 207 is configured to enable the motor to operate at a second operating condition point, where the second operating condition point is an operating point at which the output current of the motor can reach a second preset requirement; A second calibration current acquiring unit 208 uses the bus current at the second operating point as a second calibration current; 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 when the output current reaches a stable state; a bus current calibration coefficient calculation unit 210, configured to obtain a bus current calibration coefficient based on the second calibration current and the actual bus current; The third instruction receiving unit 211 is configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; The output current calibration unit 212 is used for the motor controller to calibrate the bus current of the motor based on the bus current calibration coefficient and to calibrate the three-phase current of the motor based on the three-phase current calibration coefficient.

[0042] It should be noted that the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of code, and the module, program segment or part of code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of the boxes in the block diagram and / or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0043] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0044] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interface, the indirect coupling or communication connection of the device or unit can be electrical, mechanical or other forms.

[0045] The units described as separate components may or may not be physically separate, and 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 these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0046] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0047] If the functions are implemented in the form of 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 the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program code.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and description of the present application.

Claims

1. A current calibration method for a three-phase motor, characterized in that: The steps include: S1: Receive a current calibration command and switch the motor controller to a first state where the output current amplitude can be set; S2: The motor is operated at a first operating point, where the first operating point is an operating point at which the output current of the motor reaches a first preset requirement; S3: Using the three-phase current at the first operating point as a first calibration current; S4: The motor starts to work and continuously outputs current, and when the output current reaches a stable state, the actual three-phase current of the motor is obtained; S5: Obtaining a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; S6: receiving the instruction to restore the normal mode, so that the output current of the motor is reset to zero; S7: operating the motor at a second operating point, where the second operating point is an operating point at which the output current of the motor reaches a second preset requirement; S8: Using the bus current at the second operating point as a second calibration current; S9: The motor starts to work and continuously outputs current, and when the output current reaches a stable state, the actual bus current of the motor is obtained; S10: Obtaining a bus current calibration coefficient based on the second calibration current and the actual bus current; S11: receiving a command to restore the normal mode, so that the output current of the motor is reset to zero; S12: Calibrate the current bus current of the motor based on the bus current calibration coefficient and calibrate the current three-phase current of the motor based on the three-phase current calibration coefficient.

2. The method according to claim 1, characterized in that 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%.

3. The method according to claim 2, characterized in that The second preset requirement is that the bus current reaches 70%-100% of the maximum bus current and lasts for no less than 10 seconds.

4. The method according to claim 3, characterized in that Step S5 includes: The first calibration current and the actual three-phase current are processed in a first encryption manner to obtain a three-phase current calibration coefficient.

5. The method according to claim 4, characterized in that The three-phase current calibration coefficient is expressed by the following formula: （1）； （2）； （3）； in, is the U-phase current calibration coefficient, is the V-phase current calibration coefficient, is the W phase current calibration coefficient, is the actual current of phase U of the actual three-phase current, is the actual current of phase V of the actual three-phase current, is the actual current of phase W of the actual three-phase current, is the U-phase calibration current of the first calibration current, is the V-phase calibration current of the first calibration current, is the W-phase calibration current of the first calibration current, is the encryption coefficient, The encryption offset value.

6. The method according to claim 5, characterized in that Step S10 includes: The second calibration current and the actual bus current are processed by a second encryption method to obtain a bus current calibration coefficient.

7. The method according to claim 6, characterized in that The bus current calibration coefficient is expressed by the following formula: （4）； in, is the bus current calibration coefficient, is the actual bus current, is the second calibration current, is the encryption coefficient, The encryption offset value.

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

9. The method according to claim 1, characterized in that The current in steps S4 and S9 is controlled by the FOC algorithm to reach a stable state.

10. A current calibration device for a three-phase motor, characterized in that: include: a first instruction receiving unit, configured to receive a current calibration instruction and switch the motor controller to a first state in which the output current amplitude can be set; a first operating condition execution unit, configured to enable the motor to operate at a first operating condition point, wherein the first operating condition point is an operating point at which the output current of the motor can reach a first preset requirement; a first calibration current acquiring unit, configured to use the three-phase current at the first operating point as a first calibration current; an actual three-phase current acquisition unit, configured 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; a three-phase current calibration coefficient calculation unit, configured to obtain a three-phase current calibration coefficient based on the first calibration current and the actual three-phase current; a second instruction receiving unit, configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; a second operating condition execution unit, configured to cause the motor to operate at a second operating condition point, wherein the second operating condition point is an operating point at which the output current of the motor can reach a second preset requirement; a second calibration current acquiring unit, which uses the bus current at the second operating point as the second calibration current; an actual bus current acquisition unit, configured to acquire the actual bus current of the motor when the motor starts to work and continuously outputs current, and when the output current reaches a stable state; a bus current calibration coefficient calculation unit, configured to obtain a bus current calibration coefficient based on the second calibration current and the actual bus current; a third instruction receiving unit, configured to receive an instruction to restore the normal mode so that the output current of the motor is reset to zero; An output current calibration unit is used to calibrate the bus current of the motor based on the bus current calibration coefficient and to calibrate the three-phase current of the motor based on the three-phase current calibration coefficient.

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