Calibration method for ampere meter of vehicle motor controller

Abstract

The invention belongs to the technical field of vehicle motor controllers, and particularly relates to a calibration method of a vehicle motor controller ampere meter, which comprises the following steps: S1, carrying out Id-Iq current combination traversal scanning at a rotating speed lower than a reference rotating speed to obtain torques and voltage utilization rates corresponding to various current combinations at each rotating speed lower than the reference rotating speed; s2, dividing the current combinations with the same torque into one group and performing fitting to obtain an equal-torque curve; s3, traversing the equal-torque curve of each torque at each rotating speed according to a preset traversing process, and obtaining a current combination capable of enabling the actual output current Is to be minimum or the voltage utilization rate to be maximum on each equal-torque curve; and S4, summarizing the obtained current combination of the equal torque curve of each torque at each rotating speed, and taking the current combination as a final obtained ampere meter. The method can improve the automation degree and accuracy of calibration of the ampere meter of the vehicle-mounted motor controller, reduces errors caused by manual operation, and ensures that the performance of the ampere meter is recovered to the optimal state.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle motor controllers, and in particular relates to a calibration method for an ammeter of a vehicle motor controller. Background Art

[0002] With the development of the new energy electric vehicle industry, the development cycle of motor controllers has gradually shortened, and the human resource pressure and project delivery pressure of R&D personnel have also gradually increased, which has put higher requirements on the calibration efficiency of motor controllers.

[0003] At present, the calibration of the ammeter of the on-board motor controller in the industry mostly adopts the Id-Iq table scan and then fits the voltage torque formula, and then verifies and repairs the meter after obtaining the ammeter once. By checking the accuracy and reliability of the ammeter during the calibration process, the ammeter is adjusted or repaired according to the verification results to eliminate its error and restore its accuracy. The process usually includes: determining the cause of the ammeter error; adjusting or calibrating the ammeter to eliminate the error and restore its accuracy; after the adjustment or repair is completed, the verification step is performed again to ensure that the ammeter now meets the expected accuracy requirements. At present, the calibration of the ammeter of the on-board motor controller in the industry involves multiple complex steps and judgments, which requires R&D personnel to have corresponding professional knowledge and experience. Through the investment of human resources, the accuracy and reliability of the ammeter calibration can be ensured, thereby improving the performance and efficiency of the motor controller. Therefore, the existing methods need to occupy human resources, and the efficiency performance of the table after manual modification cannot reach the extreme of the motor. The problems are mainly manifested in the following aspects.

[0004] First, human error may be introduced during the process. Whether it is a slight mistake in the calibration process or an inaccurate installation when replacing a component, it may affect the performance of the ammeter. This error is often difficult to completely avoid, especially without the support of high-precision automation equipment.

[0005] Second, the technical level and experience of the technicians are crucial to the restoration of the ammeter's performance. If the technicians lack the necessary professional skills or are inexperienced, they may not be able to accurately identify and solve the problem of the ammeter, resulting in poor performance of the repaired ammeter.

[0006] Third, during the process, high-precision calibration equipment is the key to ensuring the performance of the ammeter is restored. Without these equipment, technicians may not be able to accurately evaluate the performance of the ammeter, nor can they perform effective calibration and adjustments.

[0007] Therefore, the existing methods not only consume valuable human resources, but also the efficiency performance of the manually modified ammeter often fails to reach the optimal performance state of the motor. This means that despite adjustments and repairs, the accuracy and response speed of the ammeter are still far from the ideal state.

[0008] In summary, how to improve the automation and accuracy of the ammeter calibration of the vehicle motor controller, reduce the errors caused by human operation, ensure that the ammeter performance is restored to the best state, and improve the overall efficiency and performance of the motor controller has become a problem that needs to be solved urgently. Summary of the invention

[0009] In view of the above-mentioned deficiencies in the prior art, the present invention provides a calibration method for an ammeter of a vehicle motor controller, which can improve the degree of automation and accuracy of the calibration of the ammeter of the vehicle motor controller, reduce the errors caused by human operation, ensure that the performance of the ammeter is restored to the optimal state, and improve the overall efficiency and performance of the motor controller.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A method for calibrating an ammeter of a vehicle motor controller comprises the following steps:

[0012] S1. Perform an Id-Iq current combination traversal sweep at a speed lower than the reference speed to obtain the torque and voltage utilization rate corresponding to various current combinations at each speed lower than the reference speed;

[0013] S2, grouping current combinations with equal torque into one group, and fitting each current combination to obtain the corresponding equal torque curve;

[0014] S3. According to the preset traversal process, the equal torque curves of each torque at each speed are traversed to obtain the current combination on each equal torque curve that can minimize the actual output current Is or maximize the voltage utilization rate, so that the voltage utilization rate reaches the limit;

[0015] S4. Summarize the current combinations of the equal torque curves at various speeds and torques, and use them as the final current table for the current control strategy of the motor controller.

[0016] Glossary:

[0017] Reference speed: id=0, iq=is. When the maximum value (maximum peak current) is reached, the voltage utilization rate just does not exceed the upper threshold.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Compared with traditional methods, this method does not need to consider the problem of inaccurate torque accuracy due to fitting and inaccurate voltage utilization calculation leading to low efficiency or voltage saturation. By directly traversing the actual measured Id-Iq current combination and obtaining the corresponding torque and voltage utilization, this method avoids the complex mathematical model fitting process, thereby reducing the inaccurate torque accuracy and voltage utilization calculation deviation caused by fitting errors. This method ensures the accuracy and reliability of the data, avoids the risk of low efficiency or voltage saturation, and provides a solid foundation for the current control strategy of the motor controller.

[0020] 2. In this method, for each speed point in the equal power zone, the Id-Iq current combination under the corresponding torque value is the highest efficiency point obtained through actual measurement, and the accuracy of the torque has been ensured in this process. Therefore, there is no need to use the voltage-torque formula for subsequent fitting or calculation, which not only simplifies the operation process, but also ensures the accuracy and practicality of the data. Compared with the traditional calibration method, this method simplifies the calibration process and reduces the complexity and time cost of the calibration work by direct traversal and measurement. This helps to speed up the development and production progress of the motor controller and improve production efficiency. In addition, this method can greatly reduce the professional requirements for the bench operator. In the past, the operator may need to have deep professional knowledge and rich experience to manually adjust the current combination and accurately measure the torque. Now, through the set program running, the entire scanning, fitting and traversal process can be completed automatically, which greatly simplifies the operation process and reduces the dependence on the skill level of the personnel.

[0021] 3. This method is more accurate and efficient in dealing with the relationship between current combinations and torque. It uses fitting technology to group current combinations with equal torque into a group and generate corresponding equal torque curves. In this way, in the subsequent traversal process, the current combination that meets the requirements can be directly obtained on the equal torque curve without tedious experiments and adjustments. This step not only improves work efficiency, but also ensures the accuracy of torque measurement. Traditional fitting methods may cause the generated equal torque curve to deviate from the actual torque value due to data errors, improper fitting algorithms, etc. This method can ensure the accuracy of the fitting results, thereby improving the accuracy of torque measurement.

[0022] 4. This method can optimize motor performance. By traversing the Id-Iq current combination and measuring the corresponding torque and voltage utilization, the technical solution can find the current combination that maximizes the voltage utilization at different speeds and torques. This helps the motor controller to use electrical energy more efficiently in actual operation, thereby improving the overall performance and efficiency of the motor. Voltage utilization is one of the important indicators for measuring motor efficiency. This method maximizes the voltage utilization so that the motor consumes less electrical energy at the same torque output, thereby improving the energy efficiency ratio and extending the range of electric vehicles. The current combination with equal torque is fitted to obtain the equal torque curve, so that the motor controller can directly find the corresponding current combination from the equal torque curve when a specific torque output is required. This greatly improves the control accuracy and response speed, allowing the motor to track the desired torque output more accurately.

[0023] 5. By accurately calibrating the ammeter, the motor controller can select the most appropriate current combination when facing different working conditions, thereby avoiding potential problems such as overcurrent and overheating, and enhancing the stability and reliability of the system. Once the ammeter is accurately calibrated, the motor controller can formulate a control strategy based on this lookup table without complex real-time calculations. This simplifies the design and implementation of the control strategy and reduces the complexity and cost of the system.

[0024] In summary, this method can improve the automation and accuracy of the ammeter calibration of the vehicle motor controller, reduce the errors caused by human operation, ensure that the ammeter performance is restored to the optimal state, and improve the overall efficiency and performance of the motor controller.

[0025] Preferably, in S3, the preset traversal process includes: starting from the lowest speed and gradually increasing according to the preset speed increment step until all speeds are traversed;

[0026] During a speed traversal, all current combinations under all torques are tried according to the preset torque step starting from 0 Nm;

[0027] When a torque is traversed at a speed, the combination with the largest Id current value in the corresponding equal torque curve is taken as the starting point, and the current combinations are traversed and screened in sequence along the direction in which Id gradually decreases to find the optimal combination that can maximize the voltage utilization.

[0028] This setup ensures that 1. all speeds are explored in detail over the entire speed range by traversing all speeds at a certain speed step size. At the same time, for each speed point, all current combinations under torque are tried at a preset torque step size starting from 0 Nm, ensuring full coverage in the torque dimension. This comprehensive coverage enables us to obtain the complete performance of the motor at different speeds and torques.

[0029] 2. For each torque value at a speed, traverse from the combination with the largest Id in the corresponding equal torque curve, and then proceed in the direction of gradually decreasing Id. This strategy greatly improves the efficiency of traversal. Because in practical applications, current combinations with larger Id often correspond to conservative torque output and stable and safe voltage utilization. Starting from the combination with the largest Id can ensure the stability of the system during operation and ensure that no current combination on the voltage limit circle is missed.

[0030] 3. Through the traversal process, the optimal current combination corresponding to each speed and torque (that is, the optimal solution of Id and Iq) can be obtained. These optimal current combinations can enable the motor to achieve the best performance under specific working conditions, such as the highest efficiency, the lowest loss or the maximum torque output. This is of great significance for the design and optimization of the motor. In addition, through comprehensive exploration and experimentation, the reliability and stability of the entire motor control system have been improved. Because in actual applications, the motor may face various complex working conditions and load changes. Through the traversal process, we can better understand the performance of the motor under different conditions, so as to provide it with more reliable control strategies and protection measures.

[0031] Preferably, in S3, when traversing an equal torque curve, if a minimum point of the actual output current Is is encountered, the current combination corresponding to the minimum Is is selected and the traversal is terminated; if a current combination whose voltage utilization just reaches the set upper limit threshold is encountered, the current combination is selected and the traversal is terminated; otherwise, the traversed current combination with the minimum Is is selected.

[0032] Such a setting, 1. By setting the upper threshold of voltage utilization and monitoring the voltage utilization in real time during the traversal process, when the threshold is reached, the current combination that just reaches the upper limit is selected, which can ensure that the motor runs efficiently while avoiding voltage saturation and overvoltage. This helps to protect the motor and extend its service life, while improving the stability and reliability of the entire motor control system.

[0033] 2. It can improve the current efficiency. When the Is minimum value point is encountered, selecting this current combination can ensure that the motor consumes the minimum current when outputting the same torque, thereby improving the efficiency of the motor. This is of great significance for reducing energy consumption and operating costs.

[0034] 3. If neither the upper limit of voltage utilization nor the Is minimum point is reached during the traversal process, the Is minimum current combination traversed is selected. This strategy ensures the integrity and flexibility of the traversal process and avoids the problem of traversal interruption or inability to select a suitable current combination due to special circumstances.

[0035] Preferably, the actual output current Is is calculated as follows:

[0036]

[0037] Where Id represents the axial current perpendicular to the rotor magnetic field in the synchronous motor, and Iq represents the axial current parallel to the rotor magnetic field in the synchronous motor.

[0038] Such a setting, by providing a calculation method for Is current, that is, the relationship between Is, Id and Iq, enables accurate calculation and comparison of Is values ​​under different current combinations during the traversal process, thereby selecting the optimal current combination according to preset requirements.

[0039] Preferably, in S3, when traversing the equal torque curve of a torque at a speed, if the voltage utilization rate corresponding to the current combination with the largest Id in the equal torque curve exceeds the set upper limit threshold, it is determined that the external characteristics of the motor at the current speed cannot reach the torque, and the traversal of the torque and above at the current speed is abandoned, and the traversal is entered into the next speed.

[0040] With this setting, when the current combination with the largest Id in the equal torque curve causes the voltage utilization to exceed the set threshold, it means that the motor may be subjected to excessive voltage when running at this speed and torque, thereby increasing the risk of motor damage. By determining that the motor's external characteristics at the current speed cannot reach this torque, and discarding this torque and above at the current speed, the motor can be prevented from operating under conditions that exceed its tolerance, thereby protecting the motor from damage.

[0041] By promptly abandoning the torque point that exceeds the voltage utilization threshold, the motor can be protected from damage, the stability of the motor control system can be improved, the motor performance can be optimized, and the traversal efficiency can be improved. This is of great significance for ensuring that the motor operates under safe, stable and efficient conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0043] Figure 1 A flowchart of the method is shown in FIG.

[0044] Figure 2 It is a schematic diagram of the traversal process of the equal torque curves of each torque at each speed in the embodiment;

[0045] Figure 3 A comparison curve diagram of the motor speed-torque relationship after calibration using the prior art method and the present method in the embodiment;

[0046] Figure 4The torque-current relationship comparison curve of the motor at a speed of 10000 rpm after calibration using the prior art and the present method in the embodiment. DETAILED DESCRIPTION

[0047] The following is a further detailed description through specific implementation methods:

[0048] Example:

[0049] like Figure 1 As shown, this embodiment discloses a method for calibrating an ammeter of a vehicle motor controller, comprising the following steps:

[0050] S1. Perform an Id-Iq current combination traversal sweep at a speed lower than the reference speed to obtain the torque and voltage utilization rate corresponding to various current combinations at each speed lower than the reference speed;

[0051] At the reference speed, that is, id=0, iq=is maximum value (maximum peak current), the voltage utilization rate just does not exceed the upper limit threshold.

[0052] S2, grouping the current combinations with equal torque at the same speed into one group, and fitting each current combination to obtain the corresponding equal torque curve;

[0053] S3. According to the preset traversal process, the equal torque curves of each torque at each speed are traversed to obtain the current combination on each equal torque curve that can minimize the actual output current Is or maximize the voltage utilization rate, so that the voltage utilization rate reaches the limit.

[0054] like Figure 2 As shown, the preset traversal process includes: starting from the lowest speed and gradually increasing according to the preset speed increment step until all speeds are traversed;

[0055] During a speed traversal, all current combinations under all torques are tried according to the preset torque step starting from 0 Nm;

[0056] When a torque is traversed at a speed, the combination with the largest Id current value in the corresponding equal torque curve is taken as the starting point, and the current combinations are traversed and screened in sequence along the direction in which Id gradually decreases to find the optimal combination that can maximize the voltage utilization.

[0057] Voltage utilization rate = actual voltage value / rated voltage value.

[0058] In this way, by traversing all speeds at a certain speed step, it is ensured that a detailed exploration can be carried out in the entire speed range. At the same time, for each speed point, starting from 0 Nm, all current combinations under torque are tried according to the preset torque step, ensuring comprehensive coverage in the torque dimension. Such comprehensive coverage enables us to obtain the complete performance of the motor at different speeds and torques. In addition, for each torque value at a speed, the traversal starts from the combination with the largest Id in the corresponding equal torque curve, and then proceeds in the direction of gradually decreasing Id. This strategy greatly improves the efficiency of the traversal. Because in practical applications, the current combination with a larger Id often corresponds to conservative torque output and stable and safe voltage utilization. Starting from the combination with the largest Id can ensure the stability of the system during operation and ensure that the current combination on the voltage limit circle will not be missed. In addition, through the traversal process, the optimal current combination corresponding to each speed and torque (i.e., the optimal solution of Id and Iq) can be obtained. These optimal current combinations can enable the motor to achieve the best performance under specific working conditions, such as the highest efficiency, the lowest loss or the maximum torque output. This is of great significance for the design and optimization of the motor. In addition, through comprehensive exploration and experimentation, the reliability and stability of the entire motor control system have been improved. Because in actual applications, motors may face various complex working conditions and load changes. Through the traversal process, we can better understand the performance of motors under different conditions, thereby providing more reliable control strategies and protection measures.

[0059] In specific implementation, when traversing an equal torque curve, if the minimum value point of the actual output current Is is encountered, the current combination corresponding to the minimum value of Is is selected and the traversal is terminated; if the current combination whose voltage utilization rate just reaches the set upper limit threshold is encountered, the current combination is selected and the traversal is terminated; otherwise, the traversed current combination with the minimum value of Is is selected.

[0060] In this way, by setting the upper threshold of the voltage utilization rate and monitoring the voltage utilization rate in real time during the traversal process, when the threshold is reached, the current combination that just reaches the upper limit is selected, which can ensure that the motor can run efficiently while avoiding voltage saturation and overvoltage. This helps to protect the motor and extend its service life, while improving the stability and reliability of the entire motor control system. It can also improve the current efficiency. When the Is minimum point is encountered, the current combination is selected to ensure that the motor consumes the least current when the motor outputs the same torque, thereby improving the efficiency of the motor. This is of great significance for reducing energy consumption and reducing operating costs. In addition, if neither the upper limit of the voltage utilization rate nor the Is minimum point is encountered during the traversal process, the Is minimum current combination of the traversal is selected. This strategy ensures the integrity and flexibility of the traversal process and avoids the problem of traversal interruption or inability to select a suitable current combination due to special circumstances.

[0061] Among them, the calculation method of the actual output current Is is:

[0062]

[0063] Where Id represents the axial current perpendicular to the rotor magnetic field in the synchronous motor, and Iq represents the axial current parallel to the rotor magnetic field in the synchronous motor.

[0064] In this way, by providing a calculation method for Is current, that is, the relationship between Is, Id and Iq, the Is values ​​under different current combinations can be accurately calculated and compared during the traversal process, so as to select the optimal current combination according to the preset requirements.

[0065] In specific implementation, when traversing an equal torque curve, when traversing an equal torque curve of a torque at a speed, if the voltage utilization rate corresponding to the current combination with the largest Id in the equal torque curve exceeds the set upper limit threshold, it is determined that the external characteristics of the motor at the current speed cannot reach the torque, and the traversal of the torque and above at the current speed is abandoned, and the traversal is entered at the next speed.

[0066] In this way, when the current combination with the largest Id in the equal torque curve causes the voltage utilization to exceed the set threshold, this means that the motor may be subjected to excessive voltage when running at this speed and torque, thereby increasing the risk of motor damage. By judging that the external characteristics of the motor at the current speed cannot reach this torque, and discarding this torque and above torque points at the current speed, it is possible to avoid the motor from operating under conditions that exceed its tolerance, thereby protecting the motor from damage. By promptly discarding torque points that exceed the voltage utilization threshold, the motor can be protected from damage, the stability of the motor control system can be improved, the motor performance can be optimized, and the traversal efficiency can be improved. This is of great significance for ensuring that the motor operates under safe, stable, and efficient conditions.

[0067] S4. Summarize the current combinations of the equal torque curves at various speeds and torques, and use them as the final current table for the current control strategy of the motor controller.

[0068] Compared with the traditional method, this method does not need to consider the problem of inaccurate torque accuracy caused by fitting and inaccurate voltage utilization calculation leading to low efficiency or voltage saturation. By directly traversing and scanning the actual measured Id-Iq current combination and obtaining the corresponding torque and voltage utilization, this method avoids the complex mathematical model fitting process, thereby reducing the inaccurate torque accuracy and voltage utilization calculation deviation caused by fitting errors. This method ensures the accuracy and reliability of the data, avoids the risk of low efficiency or voltage saturation, and provides a solid foundation for the current control strategy of the motor controller. In this method, for each speed point in the equal power zone, the Id-Iq current combination under the corresponding torque value is the highest efficiency point obtained by actual measurement, and the accuracy of the torque has been ensured in this process. Therefore, there is no need to use the voltage-torque formula for subsequent fitting or calculation, which not only simplifies the operation process, but also ensures the accuracy and practicality of the data. Compared with the traditional calibration method, this method simplifies the calibration process by directly traversing and measuring, reducing the complexity and time cost of the calibration work. This helps to speed up the research and development and production progress of the motor controller and improve production efficiency. In addition, this method can greatly reduce the professional requirements for the bench operator. In the past, the operator may need to have deep professional knowledge and rich experience to manually adjust the current combination and accurately measure the torque. Now, through the set program running, the entire scanning, fitting and traversal process can be completed automatically, which greatly simplifies the operation process and reduces the dependence on the skill level of the operator.

[0069] This method is more accurate and efficient in dealing with the relationship between current combination and torque. It uses fitting technology to group current combinations with equal torque into a group and generate corresponding equal torque curves. In this way, in the subsequent traversal process, the current combination that meets the requirements can be directly obtained on the equal torque curve without tedious experiments and adjustments. This step not only improves work efficiency, but also ensures the accuracy of torque measurement. Traditional fitting methods may cause the generated equal torque curve to deviate from the actual torque value due to data errors, improper fitting algorithms, etc. This method can ensure the accuracy of the fitting results, thereby improving the accuracy of torque measurement. In addition, by accurately calibrating the ammeter, the motor controller can select the most appropriate current combination when facing different working conditions, thereby avoiding potential problems such as overcurrent and overheating, and enhancing the stability and reliability of the system. Once the ammeter is accurately calibrated, the motor controller can formulate a control strategy based on this lookup table without complex real-time calculations. This simplifies the design and implementation of the control strategy and reduces the complexity and cost of the system. In addition, this method can optimize the performance of the motor. By traversing the Id-Iq current combination and measuring the corresponding torque and voltage utilization, the technical solution can find the current combination that maximizes the voltage utilization at different speeds and torques. This helps the motor controller to use electrical energy more efficiently in actual operation, thereby improving the overall performance and efficiency of the motor. Voltage utilization is one of the important indicators for measuring motor efficiency. This method maximizes the voltage utilization so that the motor consumes less electrical energy at the same torque output, thereby improving the energy efficiency ratio and extending the range of electric vehicles. The current combination with equal torque is fitted to obtain the equal torque curve, so that the motor controller can directly find the corresponding current combination from the equal torque curve when a specific torque output is required. This greatly improves the control accuracy and response speed, allowing the motor to track the desired torque output more accurately.

[0070] This method can improve the automation and accuracy of the ammeter calibration of the vehicle-mounted motor controller, reduce the errors caused by human operation, ensure that the ammeter performance is restored to the optimal state, and improve the overall efficiency and performance of the motor controller.

[0071] Figure 3 The figure shows the comparison curve of the motor speed-torque relationship after calibration using the prior art method and the present method. Figure 3 In the figure, the horizontal axis represents the rotation speed and the vertical axis represents the torque; Figure 4 The torque-current relationship comparison curve of the motor at a speed of 10000 rpm after calibration using the prior art and this method is shown in FIG. Figure 4 In the figure, the horizontal axis represents torque and the vertical axis represents current. Figure 3 and Figure 4It can be seen that compared with the traditional method, the new calibration method described in the present invention can use a relatively lower current to obtain a more extreme torque, and this method can ensure that a more extreme current combination (closer to the voltage limit circle) is obtained within the controller modulation capability range in the MTPV interval, while the traditional fitting method will choose to shift into the voltage limit circle in order to avoid the current combination exceeding the controller modulation capability range, otherwise the stability of the ammeter cannot be guaranteed. Compared with the prior art, this method can maximize the voltage utilization. Since all current combinations and voltage utilization rates of this method are verified by actual measurements, more extreme current combinations can be obtained while ensuring that the controller modulation capability is not exceeded, fully exploring the performance of the electric drive hardware and improving the overall operating efficiency.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for calibrating an ammeter of a vehicle motor controller, characterized in that: The following steps are involved: S1. Perform an Id-Iq current combination traversal sweep at a speed lower than the reference speed to obtain the torque and voltage utilization rate corresponding to various current combinations at each speed lower than the reference speed; S2, grouping current combinations with equal torque into one group, and fitting each current combination to obtain the corresponding equal torque curve; S3. According to the preset traversal process, the equal torque curves of each torque at each speed are traversed to obtain the current combination on each equal torque curve that can minimize the actual output current Is or maximize the voltage utilization rate, so that the voltage utilization rate reaches the limit; S4. Summarize the current combinations of the equal torque curves at various speeds and torques, and use them as the final current table for the current control strategy of the motor controller.

2. The method for calibrating an ammeter of a motor controller for a vehicle as claimed in claim 1, characterized in that: In S3, the preset traversal process includes: starting from the lowest speed and gradually increasing according to the preset speed increment step until all speeds are traversed; During a speed traversal, all current combinations under all torques are tried according to the preset torque step starting from 0 Nm; When a torque is traversed at a speed, the combination with the largest Id current value in the corresponding equal torque curve is taken as the starting point, and the current combinations are traversed and screened in sequence along the direction in which Id gradually decreases to find the optimal combination that can maximize the voltage utilization.

3. The method for calibrating an ammeter of a motor controller for a vehicle as claimed in claim 2, characterized in that: In S3, when traversing an equal torque curve, if the minimum value point of the actual output current Is is encountered, the current combination corresponding to the minimum value of Is is selected and the traversal is terminated; if the current combination whose voltage utilization rate just reaches the set upper limit threshold is encountered, the current combination is selected and the traversal is terminated; otherwise, the traversed current combination with the minimum value of Is is selected.

4. The method for calibrating an ammeter of a motor controller for a vehicle as claimed in claim 3, characterized in that: The actual output current Is is calculated as: Where Id represents the axial current perpendicular to the rotor magnetic field in the synchronous motor, and Iq represents the axial current parallel to the rotor magnetic field in the synchronous motor.

5. The method for calibrating an ammeter of a motor controller for a vehicle as claimed in claim 2, characterized in that: In S3, when traversing the equal torque curve of a torque at a speed, if the voltage utilization rate corresponding to the current combination with the largest Id in the equal torque curve exceeds the set upper limit threshold, it is determined that the external characteristics of the motor at the current speed cannot reach the torque, and the traversal of the torque and above at the current speed is abandoned, and the traversal is entered into the next speed.

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