Calibration method for temperature and temperature rise torque limit of permanent magnet synchronous motor and motor controller

Abstract

The invention discloses a temperature and temperature rise torque limit calibration method for a permanent magnet synchronous motor and a motor controller, and relates to the technical field of motor torque limit calibration. For a motor, the method comprises the following steps of: formulating a temperature limit torsion line by acquiring parameters such as sustainable working temperature and delay temperature, and adjusting a torsion limit coefficient by considering different water entry conditions. For a motor controller, the method comprises the following steps: operating to a peak torque at a set fixed rotating speed, calibrating the maximum temperature and the temperature limit twist line of an IGBT (Insulated Gate Bipolar Translator), and also considering different water entry conditions. The method ensures that the motor and the controller operate in an efficient and safe state, avoids overheating damage, improves the response speed and stability, prolongs the service life, reduces the maintenance cost, and improves the overall performance and the energy utilization rate.

Description

Technical Field

[0001] The present application belongs to the technical field of motor torque limit calibration, and in particular, relates to a method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor and a motor controller. Background Art

[0002] During the operation of the electric drive system for new energy vehicles, the motor and motor controller will generate heat. When the vehicle is running under long-term heavy load and high power, the motor and motor controller will overheat. Therefore, it is necessary to limit the torque of the electric drive system according to the temperature to ensure that the electric drive system will not be damaged due to excessive temperature.

[0003] At present, the existing technology can limit torque and fault protection according to the current temperature of the motor and motor controller. However, in actual use, the electric drive system of commercial vehicles is often overloaded, and the temperature rise of the motor is delayed due to the location of the motor temperature sensor and signal acquisition. Therefore, the temperature limit torque is often exceeded on the vehicle, resulting in insufficient power for climbing or insufficient torque limit, resulting in motor overheating. Summary of the invention

[0004] The purpose of this application is to provide a calibration method for the temperature and temperature-rise torque limit of a permanent magnet synchronous motor and a motor controller, which takes into account the temperature and temperature-rise characteristics of the motor and the motor controller under different working conditions, and ensures that the motor and the motor controller operate in an efficient and safe state through precise measurement and adjustment.

[0005] In order to achieve the above objectives, the solution of this application is: In a first aspect, an embodiment of the present application provides a method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor, comprising: Obtain the sustainable operating temperature t1 of the permanent magnet synchronous motor; Obtaining a first delay temperature t2 at which the permanent magnet synchronous motor decreases from a peak power to a rated power; Obtaining a second delay temperature t3 of the permanent magnet synchronous motor from the peak power dropping to 0; Subtract the sustainable working temperature t1 from the first delay temperature t2 to obtain the torque limit start temperature t4=t1-t2; The sustainable working temperature t1 is added to the first delay temperature t2 and the second delay temperature t3 to obtain the tube-off temperature t5=t1+t2+t3; The first temperature limit distortion curve is obtained according to the sustainable working temperature t1, the torque limit start temperature t4 and the tube shut-off temperature t5; Re-testing and calibrating the first temperature limit distortion curve to obtain a second temperature limit distortion curve; Under normal water entry conditions, the first motor temperature rise slope ta1 is obtained; under abnormal water entry conditions, the second motor temperature rise slope ta2 is obtained; under the condition that the motor water entry flow rate is 0, the third motor temperature rise slope ta3 is obtained according to the difference method; the motor water entry flow rate under abnormal water entry conditions is half of the motor water entry flow rate under normal water entry conditions; A first fixed speed is preset, and the first fixed speed is used as a step, from the first fixed speed to the maximum speed, the permanent magnet synchronous motor is operated to the corresponding peak torque at each speed, and the torque limit coefficient of the torque limit start temperature t4 and the sustainable working temperature t1 under the second motor temperature rise slope ta2 is adjusted, so that the equilibrium temperature of the permanent magnet synchronous motor reaches the sustainable working temperature t1, and the third temperature limit torsion curve under the second motor temperature rise slope ta2 is obtained; The fourth temperature limit distortion curve at the third motor temperature rise slope ta3 is obtained by the difference method.

[0006] According to the above method of the embodiment of the present application, the following additional technical features may also be provided: Furthermore, the sustainable operating temperature t1 of the permanent magnet synchronous motor is not greater than the demagnetization temperature of the permanent magnet of the motor.

[0007] Furthermore, under normal water entry conditions, obtaining the first motor temperature rise slope ta1 includes: Under normal water entry conditions, a first fixed speed is preset, and the permanent magnet synchronous motor is operated to the corresponding peak torque at each speed using the first fixed speed as a step, and the maximum value of the temperature rise of the permanent magnet synchronous motor is taken as the first motor temperature rise slope ta1.

[0008] Furthermore, under abnormal water entry conditions, obtaining the temperature rise slope ta2 of the second motor includes: Under abnormal water entry conditions, a first fixed speed is preset, and the permanent magnet synchronous motor is operated to the corresponding peak torque at each speed with the first fixed speed as a step, and the maximum value of the temperature rise slope of the permanent magnet synchronous motor is taken as the second motor temperature rise slope ta2; the motor water entry flow rate under abnormal water entry conditions is half of the motor water entry flow rate under normal water entry conditions.

[0009] In a second aspect, an embodiment of the present application provides a method for calibrating the temperature and temperature rise torque limit of a motor controller, comprising: A second fixed speed is preset, and the second fixed speed is used as a step, from the second fixed speed to the maximum speed, at each speed, the motor controller is operated to the corresponding peak torque and operated for a preset time, and the maximum temperature of the IGBT is taken as the torque limit start temperature t6 of the motor controller; The corresponding peak torque at each speed is increased by a preset percentage to obtain an overload operation peak torque, and the motor controller is operated to the corresponding overload operation peak torque and operated for a preset time at each speed from the second fixed speed to the maximum speed, taking the second fixed speed as a step, to obtain the maximum temperature t7 of the IGBT at the overload operation peak torque; the power is limited to the rated power at the maximum temperature t7 to obtain the IGBT temperature limit distortion curve; Under normal water entry conditions, the first IGBT temperature rise slope ta4 is obtained; under abnormal water entry conditions, the second IGBT temperature rise slope ta5 is obtained; under the condition that the IGBT water entry flow rate is 0, the third IGBT temperature rise slope ta6 is obtained according to the difference method; the IGBT water entry flow rate under abnormal water entry conditions is half of the IGBT water entry flow rate under normal water entry conditions; Taking the second fixed speed as the step, from the second fixed speed to the maximum speed, the torque is run to the corresponding peak torque at each speed, and the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 is adjusted to make the maximum temperature of the IGBT reach t7; the IGBT temperature limit distortion line corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5 are compared, and the temperature limit distortion line corresponding to the third IGBT temperature rise slope ta6 is obtained by the difference method.

[0010] According to the above method of the embodiment of the present application, the following additional technical features may also be provided: Furthermore, under normal water entry conditions, obtaining the first IGBT temperature rise slope ta4 includes: Under normal water entry conditions, with the second fixed speed as a step, from the second fixed speed to the maximum speed, the motor controller is operated to the corresponding peak torque at each speed to obtain the first IGBT temperature rise slope ta4.

[0011] Furthermore, under abnormal water entry conditions, obtaining the second IGBT temperature rise slope ta5 includes: Under abnormal water entry conditions, with the second fixed speed as a step, from the second fixed speed to the maximum speed, the motor controller is operated to the corresponding peak torque at each speed to obtain the second IGBT temperature rise slope ta5.

[0012] The method for calibrating the temperature and temperature rise torque limit of the permanent magnet synchronous motor and the motor controller provided in the embodiment of the present application has the following beneficial technical effects compared with the prior art: The embodiments of the present application can ensure that the motor operates in an efficient and safe state by accurately calibrating the sustainable operating temperature, torque limit start temperature and tube shut-off temperature of the motor, thereby avoiding performance degradation or damage caused by overheating; the embodiments of the present application adjust the torque limit coefficient and the temperature limit torque curve according to the motor temperature rise slope under different water entry conditions, thereby achieving precise control of the motor torque output and improving the response speed and stability of the motor; the embodiments of the present application take into account the motor temperature and temperature rise characteristics under various working conditions, including normal water entry, abnormal water entry and no water entry flow, so that the motor can adapt to a wider range of working environments; the embodiments of the present application can reduce the thermal load and mechanical stress of the motor through reasonable temperature control and torque limit strategies, thereby extending the service life of the motor and reducing maintenance costs.

[0013] The embodiment of the present application ensures that the motor controller operates in an efficient and stable state by calibrating the maximum temperature and temperature limit twist line of the IGBT, thereby improving the performance and reliability of the controller; the embodiment of the present application takes into account the temperature rise slope of the IGBT under different water entry conditions, and by adjusting the temperature limit twist line, it achieves effective management of the controller's thermal load and avoids performance degradation or failure caused by overheating; the embodiment of the present application optimizes the temperature and temperature rise torque limit calibration of the motor controller and the motor, so that the entire electric drive system operates in a more efficient state, improving energy utilization and overall performance; the embodiment of the present application reduces the system's thermal loss and mechanical wear through precise temperature control and torque limit strategies, thereby reducing the system's maintenance cost and replacement cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A flow chart showing a method for calibrating the temperature and temperature-rise torque limit of a permanent magnet synchronous motor according to an embodiment of the present application is shown; Figure 2 A flow chart of a method for calibrating the temperature and temperature-rise torque limit of a motor controller according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0016] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0017] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0018] like Figure 1 As shown, the embodiment of the present application provides a method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor and a motor controller, comprising the following steps: Step 101, obtaining the sustainable operating temperature t1 of the permanent magnet synchronous motor.

[0019] The purpose of step 101 is to determine the maximum operating temperature at which the motor will not be damaged during long-term operation, that is, the sustainable operating temperature t1 of the permanent magnet synchronous motor. In this embodiment, the sustainable operating temperature t1 of the permanent magnet synchronous motor is not greater than the demagnetization temperature of the permanent magnet of the motor, which is an important restriction condition for the sustainable operating temperature t1.

[0020] The permanent magnets in permanent magnet synchronous motors are one of their key components. They provide the magnetic field required for the motor to operate. However, permanent magnets may lose their magnetism at high temperatures. This process is called demagnetization. Once the permanent magnets are demagnetized, the performance of the motor will drop significantly, and it may even fail to work properly. Therefore, in order to ensure the long-term stable operation of the permanent magnet synchronous motor, its sustainable operating temperature t1 must be strictly controlled below the demagnetization temperature of the permanent magnet. This restriction is crucial in the design and calibration process of the motor. It ensures that when the motor reaches its performance limit, its key components can still maintain normal working conditions.

[0021] In practical applications, in order to determine the sustainable operating temperature t1 of the permanent magnet synchronous motor, a series of tests and calibrations are usually required. These tasks may include running the motor under different load and speed conditions and monitoring its temperature response. Through these tests, the sustainable operating temperature t1 of the permanent magnet synchronous motor can be accurately determined and ensure that it meets the above-mentioned constraints.

[0022] Specifically, in theory, the permanent magnet synchronous motor can operate continuously at rated power, so the temperature rise test is carried out within the operating speed range of the permanent magnet synchronous motor at the water entry temperature specified in the technical requirements. Take the rated operating speed of the permanent magnet synchronous motor as 1500rpm, the maximum operating speed as 3500rpm, and the rated power as 300kw as an example, and perform the rated power temperature rise test on 1500rpm-3500rpm in 500rpm steps to obtain the rated temperature rise temperature of the motor from 1500rpm to 3500rpm, and process the obtained rated temperature rise temperature of the motor to obtain the highest motor temperature, which is the sustainable operating temperature t1 of the permanent magnet synchronous motor.

[0023] Step 102 , obtaining a first delay temperature t2 at which the permanent magnet synchronous motor drops from a peak power to a rated power.

[0024] Step 102 involves accurate measurement and understanding of motor performance parameters. First, the definitions of peak power and rated power are explained, where peak power refers to the maximum power that the motor can output in a short period of time; rated power refers to the maximum power allowed by the motor under long-term stable operation.

[0025] The first delay temperature t2 indicates that when the motor starts to decrease from the peak power state until its output power stabilizes at the rated power, the temperature of the motor will have an obvious change in this process. The first delay temperature t2 is a parameter used to quantify this temperature change.

[0026] The first delay temperature t2 is one of the basic data for the subsequent calculation of the torque limit start temperature t4 and the tube shut-off temperature t5. It reflects the thermal response characteristics of the motor during the power change process and is of great significance for evaluating the thermal stability and durability of the motor.

[0027] In the fields of new energy vehicles and industrial automation, permanent magnet synchronous motors are widely used due to their high efficiency and high power density. Therefore, accurate calibration of the motor's temperature and temperature rise torque limit characteristics is crucial to ensure stable operation of the equipment and extend its service life.

[0028] Specifically, the motor over-temperature torque limit can be limited by looking up the table to limit the external characteristics of the motor. For example, according to the above method, the rated temperature rise of the permanent magnet synchronous motor is calculated to be 150°C, the rated power of the motor is 300kw, and the peak power of the motor is 450kw. When the motor is at 150°C, the corresponding external characteristic power limit coefficient should be 300 / 450=0.67.

[0029] Since the temperature rise of the motor has a delay, in order to better protect the permanent magnet synchronous motor from over-temperature fault and maintain good power during the motor temperature torque limiting process, the motor torque needs to be limited in advance.

[0030] As for how to limit the torque of the permanent magnet synchronous motor in advance so that the motor does not trigger an over-temperature fault, the embodiment of the present application tests the delay time of the motor temperature rise when the motor drops from peak power to rated power. For example, the operating speed corresponding to the peak power of the permanent magnet synchronous motor is 1500rpm, the maximum operating speed is 3500rpm, and the peak power is 450kw. The water inlet temperature is specified in the technical requirements, and the motor is operated to the peak power from 1500rpm-3500rpm in steps of 500rpm. When the motor temperature reaches the rated temperature rise motor temperature, the speed is kept unchanged and the power is reduced to the rated power. Record at each speed how many degrees Celsius the motor temperature continues to rise after the power drops to the rated power before it starts to drop. Compare the obtained several sets of temperatures, take the highest temperature, and obtain the first delay temperature t2 of the permanent magnet synchronous motor dropping from peak power to rated power.

[0031] Step 103 , obtaining a second delay temperature t3 at which the permanent magnet synchronous motor drops from a peak power to 0.

[0032] The calibration method of the embodiment of the present application is mainly to determine the performance of the permanent magnet synchronous motor under different temperatures and working conditions, and to set the torque limiting strategy accordingly to protect the motor. In this process, it involves the acquisition and calculation of multiple temperature parameters, including the sustainable working temperature t1, the first delay temperature t2, the second delay temperature t3, etc.

[0033] Specifically, step 103 is about obtaining the "second delay temperature t3". This temperature parameter is the temperature delay value corresponding to when the motor drops from peak power to 0 power. In simple terms, when the motor is working at peak power, if it needs to stop working and drop to 0 power for some reason (such as overheating), then in this process, the temperature of the motor will drop, and the "second delay temperature t3" is a key parameter to describe this process.

[0034] Specifically, continue with step 102, and then run the motor from 1500rpm-3500rpm in steps of 500rpm to the peak power. When the motor temperature reaches the rated temperature rise motor temperature, the motor is shut down. It is recorded at each speed how many degrees Celsius the motor temperature continues to rise after the motor is shut down and then starts to drop. The obtained several groups of temperatures are compared, and the highest temperature is taken as the second delay temperature t3 at which the permanent magnet synchronous motor drops from the peak power to 0.

[0035] Step 104 , subtract the sustainable working temperature t1 from the first delay temperature t2 to obtain the torque limit start temperature t4 = t1 − t2 .

[0036] In the embodiment of the present application, the sustainable working temperature t1 and the first delay temperature t2 are obtained through step 101 and step 102. By subtracting the sustainable working temperature t1 from the first delay temperature t2, the torque limit start temperature t4=t1-t2 can be obtained.

[0037] The torque limit start temperature t4 plays a vital role in the temperature management of the motor. When the actual operating temperature of the motor approaches or reaches t4, the control system needs to take corresponding measures, such as reducing the torque output, to ensure the safe and stable operation of the motor.

[0038] In the temperature and temperature rise torque limit calibration method of the permanent magnet synchronous motor, step 104 is the basis for determining the torque limit start temperature t4. This temperature value is not only related to the performance of the motor, but also directly affects the service life and safety of the motor. Therefore, when performing calibration, the sustainable operating temperature t1 and the first delay temperature t2 must be accurately measured and calculated to ensure that the torque limit start temperature t4 obtained is accurate and reliable.

[0039] Step 105 , adding the sustainable working temperature t1 to the first delay temperature t2 and the second delay temperature t3 to obtain the shut-off temperature t5 = t1 + t2 + t3.

[0040] The embodiment of the present application obtains the sustainable working temperature t1, the first delay temperature t2 and the second delay temperature t3 through steps 101 to 103. By adding these three temperatures, the shut-off temperature t5=t1+t2+t3 can be obtained, which is used as an important basis for determining whether the motor needs to be shut down or other protective measures need to be taken.

[0041] In the temperature and temperature rise torque limit calibration method of the permanent magnet synchronous motor, step 105 is the basis for determining the shut-off temperature t5. Accurate calculation of the shut-off temperature t5 is crucial for the temperature management of the motor. When the actual operating temperature of the motor approaches or reaches t5, the control system needs to take corresponding measures, such as shutting down the motor, to prevent the motor from being damaged due to overheating.

[0042] Step 106 , obtaining a first temperature limit distortion curve according to the sustainable working temperature t1 , the torque limit start temperature t4 , and the tube shut-off temperature t5 .

[0043] In the embodiment of the present application, the sustainable working temperature t1 is obtained through step 101, and the torque limit start temperature t4 and the tube shut-off temperature t5 are obtained through steps 104 and 105. The first temperature limit twist line can be obtained according to these three temperatures. The first temperature limit twist line is a curve drawn according to parameters such as the sustainable working temperature t1, the torque limit start temperature t4 and the tube shut-off temperature t5, which is used to guide the torque output limit of the motor at different temperatures. This curve ensures that the motor operates within a safe working range while maximizing its performance.

[0044] In the temperature and temperature rise torque limit calibration method of the permanent magnet synchronous motor, step 106 is a key step to connect the temperature parameter with the motor torque output limit. By drawing the first temperature limit torque line, the limitation of the motor torque output at different temperatures can be clearly seen, thereby providing a scientific basis for the temperature management and protection of the motor.

[0045] The corresponding first temperature limit distortion line table is shown in the following table: Table 1

[0046] Among them, the second line is the torque limit coefficient corresponding to each temperature.

[0047] Step 107, re-calibrate the first temperature limit distortion curve to obtain a second temperature limit distortion curve.

[0048] The core of step 107 is "re-calibration", that is, verifying and adjusting the first temperature limit distortion curve obtained initially to ensure its accuracy and reliability. Through re-calibration, a more accurate second temperature limit distortion curve can be obtained, providing strong support for subsequent motor temperature management.

[0049] The first temperature limit distortion curve obtained initially may have certain errors or deviations. Through recalibration, these errors can be corrected to improve the accuracy of the curve. The recalibration process usually includes multiple experiments and data analysis, which helps to enhance the reliability of the curve and make it more consistent with the actual working conditions of the motor. The second temperature limit distortion curve obtained through recalibration can more accurately control the temperature of the motor, thereby optimizing its performance and improving efficiency and durability.

[0050] Step 107 plays a connecting role in the permanent magnet synchronous motor temperature and temperature rise torque limit calibration method. It connects the first temperature limit torque line obtained initially and the second temperature limit torque line finally used for motor temperature management. Through re-calibration, it can be ensured that the obtained second temperature limit torque line is accurate and reliable, thereby providing a strong guarantee for the safe and stable operation of the motor.

[0051] After the basic torque limit relationship is obtained through step 106, the embodiment of the present application performs re-testing and calibration on the test bench. Specifically, the water inlet temperature is specified using the technical conditions, and the following working conditions are used for re-testing: Operating condition 1: low speed, peak torque; Operating condition 2: peak power, peak torque; Operating condition 3: maximum speed, peak power; Operating condition 4: rated speed, peak power.

[0052] Under each working condition, when the motor temperature changes within 1°C within 10 minutes, stop running, observe the maximum temperature and equilibrium temperature under each working condition, select the point with the highest maximum temperature and equilibrium temperature in the above working condition, and compare it with t1. If the maximum temperature and equilibrium temperature are greater than t1, t1-t2 can be reduced (the adjustment amount can refer to the equilibrium temperature minus t1); if the maximum temperature and equilibrium temperature are less than t1, t1-t2 can be increased (the adjustment amount can refer to t1- equilibrium temperature) to make the maximum temperature and equilibrium temperature of the motor close to t1 (the temperature difference can refer to 2°C).

[0053] After completing the above test, if the highest temperature and the equilibrium temperature in the above working condition test are close to t1 (the temperature difference can be referenced to 2°C), the temperature limit torque line in normal mode can be output at this time. In the actual vehicle use process, due to the unbalanced temperature of the vehicle water circuit, the special and complex working conditions and other factors, only based on the motor temperature limit torque cannot effectively protect the motor from overtemperature.

[0054] Therefore, the embodiment of the present application adopts a method combining motor temperature rise and temperature torque limit to limit torque. When the motor temperature is too high, the torque limit coefficient is adjusted twice according to the motor temperature rise rate. The adjusted motor temperature torque limit strategy is a three-dimensional curve table, with the x-axis being the motor temperature, the y-axis being the motor temperature rise rate, and the z-axis being the torque limit coefficient. As shown in the following table: Table 2

[0055] Step 108, under normal water entry conditions, obtain the temperature rise slope ta1 of the first motor; under abnormal water entry conditions, obtain the temperature rise slope ta2 of the second motor; under the condition that the motor water entry flow rate is 0, obtain the temperature rise slope ta3 of the third motor according to the difference method; the motor water entry flow rate under abnormal water entry conditions is half of the motor water entry flow rate under normal water entry conditions.

[0056] Step 108 involves obtaining the temperature rise slope of the permanent magnet synchronous motor under different water entry conditions, including normal water entry conditions, abnormal water entry conditions (the motor water entry flow is half of the normal water entry flow), and the condition where the motor water entry flow is zero.

[0057] Among them, the embodiment of the present application obtains the first motor temperature rise slope ta1 under normal water entry conditions. Under normal water entry conditions, a first fixed speed is first preset, and the speed is gradually increased with this first fixed speed as a step until the maximum speed is reached. At each speed, the permanent magnet synchronous motor is operated to the corresponding peak torque.

[0058] The temperature rise slope of the permanent magnet synchronous motor at each speed is recorded, and the maximum value is taken as the first motor temperature rise slope ta1. This process simulates the temperature rise characteristics of the motor under normal working conditions and provides basic data for subsequent torque limit calibration.

[0059] The embodiment of the present application obtains the second motor temperature rise slope ta2 under abnormal water entry conditions. Under abnormal water entry conditions (i.e., the motor water entry flow rate is half of the normal water entry flow rate), the first fixed speed is also preset, and the speed is gradually increased using this first fixed speed as a step until the maximum speed is reached.

[0060] At each speed, the permanent magnet synchronous motor is run to the corresponding peak torque, the temperature rise slope of the permanent magnet synchronous motor at each speed is recorded, and the maximum value is taken as the second motor temperature rise slope ta2. This process simulates the temperature rise characteristics of the motor in a relatively harsh working environment, which helps to evaluate the performance of the motor under different conditions.

[0061] In the embodiment of the present application, the temperature rise slope ta3 of the third motor is obtained by the difference method. When the water flow rate into the motor is 0, the temperature rise slope cannot be directly measured, so the difference method is used to obtain it.

[0062] The difference method is usually based on two or more known data points (such as ta1 under normal water entry conditions and ta2 under abnormal water entry conditions), and estimates unknown data points (such as ta3 under the condition of zero water entry flow) through interpolation or extrapolation. Specific difference methods include linear difference, quadratic difference, etc. The specific choice depends on the characteristics of the data and the required accuracy.

[0063] Specifically, under the specified technical requirements on water inlet temperature and flow rate, with 500 rpm as a step, the motor is directly increased to the corresponding peak torque from 500 rpm to the maximum speed. The maximum value of the motor temperature rise slope is tested under the specified technical requirements on water inlet temperature and flow rate as the first motor temperature rise slope ta1 in normal mode.

[0064] Reduce the motor water inlet flow rate to half of the specified water inlet flow rate, and use the same method to test the second motor temperature rise slope ta2 under abnormal motor water inlet conditions, and then calculate the third motor temperature rise slope ta3 when the motor water inlet flow rate is 0 according to the difference method.

[0065] Step 109, preset a first fixed speed, take the first fixed speed as a step, from the first fixed speed to the maximum speed, operate the permanent magnet synchronous motor to the corresponding peak torque at each speed, adjust the torque limit start temperature t4 and the torque limit coefficient of the sustainable working temperature t1 under the second motor temperature rise slope ta2, so that the equilibrium temperature of the permanent magnet synchronous motor reaches the sustainable working temperature t1, and obtain the third temperature limit torque curve under the second motor temperature rise slope ta2.

[0066] In step 109, the first fixed speed is first preset. This is the starting point of the calibration process. A fixed speed is selected as the starting point. This speed will be used as the basis for the subsequent gradual increase in speed. The first fixed speed is used as a step, from the first fixed speed to the maximum speed, which means starting from the preset first fixed speed, the speed is gradually increased until the maximum speed of the motor is reached. At each speed step, a series of operations and measurements will be performed.

[0067] Running the permanent magnet synchronous motor to peak torque at each speed means that at each speed step, the motor will be driven to its peak torque. Peak torque is the maximum torque that the motor can produce, which helps to evaluate the performance of the motor at different speeds.

[0068] Adjusting the torque limit coefficient of the torque limit start temperature t4 and the sustainable working temperature t1 under the second motor temperature rise slope ta2 is the core part of step 109. Under abnormal water entry conditions (that is, the motor water entry flow rate is half of the normal water entry flow rate), the second motor temperature rise slope ta2 has been obtained. Now, it is necessary to adjust the torque limit coefficient of the torque limit start temperature t4 and the sustainable working temperature t1 according to this temperature rise slope. The torque limit coefficient determines the degree of limitation of the motor torque at different temperatures. The purpose of adjusting these coefficients is to make the equilibrium temperature of the motor under abnormal water entry conditions reach the preset sustainable working temperature t1.

[0069] By adjusting the torque limit coefficient, it is possible to ensure that when the motor is running under abnormal water conditions, its equilibrium temperature can be maintained near the preset sustainable operating temperature t1. This helps protect the motor from overheating damage and ensures its long-term stable operation.

[0070] After completing the above adjustment, a new temperature limit distortion curve, namely the third temperature limit distortion curve, will be obtained. This curve reflects the torque limit of the motor at different temperatures under abnormal water entry conditions.

[0071] Specifically, the embodiment of the present application adopts a verification and debugging method for the torque limit coefficient under abnormal water entry conditions, adjusts the motor water entry flow rate to half of the specified water entry condition, takes 500 rpm as a step, from 500 rpm to the maximum speed, runs the motor to the corresponding peak torque at each speed, adjusts the torque limit coefficient corresponding to t1-t2 and t1 under the ta2 temperature rise rate, and makes the balance temperature of the motor reach t1. At this time, the temperature limit distortion line under the ta2 temperature rise slope can be obtained, that is, the third temperature limit distortion line.

[0072] Step 110: Obtain a fourth temperature limit distortion curve at a third motor temperature rise slope ta3 by using a difference method.

[0073] Step 110 is to further use the difference method to obtain the fourth temperature limit distortion curve under the condition of the third motor temperature rise slope ta3 based on the first motor temperature rise slope ta1, the second motor temperature rise slope ta2 and the third motor temperature rise slope ta3 obtained by the difference method.

[0074] The difference method is a mathematical method that is usually used to estimate unknown data points based on known data points. In this calibration method, the difference method is used to estimate the temperature limit distortion curve under the third motor temperature rise slope ta3 based on the known motor temperature rise slopes (ta1 and ta2) and their corresponding temperature limit distortion curves.

[0075] First, it is necessary to ensure that the three motor temperature rise slopes ta1, ta2 and ta3 have been accurately obtained. Among them, ta1 and ta2 are obtained by direct experimental measurement, while ta3 is calculated by the difference method based on ta1 and ta2 and the corresponding water inlet flow conditions. According to the characteristics of the data and the required accuracy, select a suitable difference method. Common difference methods include linear difference, quadratic difference, etc. In this calibration method, the specific choice of difference method may depend on the characteristics of the experimental data and the calibration requirements. Take the known temperature limit distortion lines corresponding to ta1 and ta2 as the benchmark, and use the difference method to estimate the temperature limit distortion line corresponding to ta3.

[0076] like Figure 2 As shown, the embodiment of the present application provides a method for calibrating the temperature and temperature rise torque limit of a motor controller, comprising the following steps: Step 201, preset a second fixed speed, take the second fixed speed as a step, from the second fixed speed to the maximum speed, run the motor controller to the corresponding peak torque and run for a preset time at each speed, and take the highest temperature of the IGBT as the torque limit start temperature t6 of the motor controller.

[0077] In step 201, first, a starting speed value, namely the second fixed speed, needs to be set. This speed value is determined based on the experimental requirements, the design specifications of the motor controller, and safety considerations. Next, starting from the second fixed speed, the speed is gradually increased until the maximum speed of the motor controller is reached. In this process, each speed point needs to be carried out as a stage of the experiment. At each speed stage, the motor controller needs to be run to its corresponding peak torque. This means that the motor controller needs to output enough power to drive the load to a predetermined torque value.

[0078] At each speed stage, when the motor controller runs to the corresponding peak torque, the maximum temperature of the IGBT (insulated gate bipolar transistor) needs to be recorded. IGBT is a key component in the motor controller, and its temperature has an important impact on the performance and life of the motor controller. In all speed stages, the maximum temperature of the IGBT is set to the torque limit start temperature t6 of the motor controller. This means that when the temperature of the IGBT reaches or exceeds this value, the motor controller needs to start limiting the torque output to prevent overheating and damage.

[0079] The purpose of this step is to determine the temperature performance of the motor controller at different speeds and torques, and to set a safe temperature limit (i.e. torque limit start temperature t6) accordingly. This is crucial for protecting the motor controller and improving the reliability and durability of the system.

[0080] Specifically, due to the different temperature change characteristics of IGBT and motor, the IGBT temperature rises without delay after the torque drops, and drops directly. Therefore, it is necessary to first confirm that the motor controller can meet the peak power operation time. Under the water entry conditions specified in the technical agreement, 500 rpm is used as a step, from 500 rpm to the maximum speed, and the torque is increased to the peak torque at each speed. The operation time specified in the operating technical conditions is recorded, and the highest IGBT temperature is recorded as the motor controller torque limit start temperature t6.

[0081] Step 202, the corresponding peak torque at each speed is increased by a preset percentage to obtain the overload operation peak torque, and the motor controller is operated to the corresponding overload operation peak torque and runs for a preset time at each speed from the second fixed speed to the maximum speed, taking the second fixed speed as a step, to obtain the maximum temperature t7 of the IGBT at the overload operation peak torque; at the maximum temperature t7, the power is limited to the rated power to obtain the IGBT temperature limit distortion curve.

[0082] In step 202, first, an initial peak torque needs to be determined, which is usually determined in the design or test phase of the electric drive system. Then, the initial peak torque is increased by a preset percentage to obtain a new peak torque value, namely, the overload operation peak torque. The preset percentage can be determined according to the actual application requirements and the performance of the motor controller.

[0083] Next, starting from the second fixed speed, the speed is gradually increased until the maximum speed is reached. At each speed, the motor controller is operated to overload peak torque. This process is to simulate the load conditions of the motor controller in actual work and observe the temperature changes of the IGBT at different speeds and torques.

[0084] At each speed, when the motor controller runs to the overload peak torque, the maximum temperature t7 of the IGBT is recorded. These temperature data will be used for subsequent analysis and calibration.

[0085] Finally, the power is limited to the rated power, and based on the previously acquired temperature data (including t7), the temperature limit distortion curve of the IGBT is drawn. This curve describes the torque that the motor controller needs to limit in order to maintain stable operation at different temperatures. It is an important part of the motor controller's temperature management and protection strategy.

[0086] Specifically, due to the deviation in the batch consistency of the motor, the embodiment of the present application increases the peak torque by 10%. On the test bench, the torque is increased to the overload operation peak torque from 500 rpm to the maximum speed at each speed, and the operation technical conditions stipulate the operation time. The maximum temperature t7 of the IGBT is recorded. At this time, it can be considered that the motor controller is working abnormally. At this time, the power can be limited to the rated working condition. At this time, the IGBT temperature limit twist line can be output, and its corresponding limit torque table is shown in the following table: Table 3

[0087] Among them, the second line is the torque limit coefficient corresponding to each temperature.

[0088] Step 203, under normal water entry conditions, obtain the first IGBT temperature rise slope ta4; under abnormal water entry conditions, obtain the second IGBT temperature rise slope ta5; under the condition that the IGBT water entry flow rate is 0, obtain the third IGBT temperature rise slope ta6 according to the difference method; the IGBT water entry flow rate under abnormal water entry conditions is half of the IGBT water entry flow rate under normal water entry conditions.

[0089] Step 203 describes the process of obtaining the IGBT temperature rise slope under three different IGBT water inflow flow conditions (normal water inflow, abnormal water inflow, and water inflow flow of 0).

[0090] Under normal water entry conditions, the embodiment of the present application uses a preset second fixed speed as a step, and gradually increases from this speed to the maximum speed. At each speed, the motor controller is operated to the corresponding peak torque, and the temperature change of the IGBT is recorded. By running the motor controller at different speeds and observing the temperature change of the IGBT, the temperature rise slope ta4 of the IGBT under normal water entry conditions can be calculated. This slope reflects the thermal response characteristics of the IGBT under normal heat dissipation conditions.

[0091] Under abnormal water entry conditions (i.e., the IGBT water entry flow is half of the normal water entry conditions), the second fixed speed is also used as a step to gradually increase from this speed to the maximum speed. At each speed, the motor controller is operated to the corresponding peak torque, and the temperature change of the IGBT is recorded. By simulating the situation where the heat dissipation conditions are limited, the temperature rise slope ta5 of the IGBT under abnormal water entry conditions can be calculated. This slope helps to evaluate the thermal response characteristics of the IGBT under poor heat dissipation conditions.

[0092] Under the condition that the water flow rate of the IGBT is 0 (that is, there is no heat dissipation at all), since direct experiments may cause overheating and damage to the IGBT, the temperature rise slope ta6 under this condition is usually estimated by the difference method. The difference method is based on the known temperature rise slopes under normal water entry conditions and abnormal water entry conditions, and estimates the temperature rise slope under no heat dissipation conditions by interpolation or extrapolation. Although it is impossible to directly obtain the temperature rise slope under no heat dissipation conditions through experiments, the slope under this condition can be estimated through the difference method, so as to have a more comprehensive understanding of the thermal response characteristics of the IGBT under different heat dissipation conditions.

[0093] Specifically, consistent with the motor temperature rise torque limiting strategy, due to various factors such as the unbalanced temperature of the vehicle water circuit and the special and complex working conditions, over-temperature protection of the IGBT cannot be effectively performed based on temperature torque limiting alone. Consistent with the motor temperature rise torque limiting strategy, adjust the water inlet flow rate to the water inlet flow rate specified in the technical conditions, from 500rpm to the maximum speed, with 500rpm as a step, increase the torque to the peak torque at each speed, compare the data, and obtain the first IGBT temperature rise slope ta4, adjust the water inlet flow rate to half of the water inlet flow rate specified in the technical conditions, from 500rpm to the maximum speed, with 500rpm as a step, increase the torque to the peak torque at each speed, compare the data, and obtain the second IGBT temperature rise slope ta5, calculate the difference between ta4 and ta5, and obtain the third IGBT temperature rise slope ta6 when the water inlet flow rate is 0.

[0094] Step 204, taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, the torque is run to the corresponding peak torque, and the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 is adjusted to make the maximum temperature of the IGBT reach t7; the IGBT temperature limit distortion line corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5 are compared, and the temperature limit distortion line corresponding to the third IGBT temperature rise slope ta6 is obtained by the difference method.

[0095] The main task of step 204 is to use the second fixed speed as a step to gradually increase the speed to the maximum speed under abnormal water entry conditions, operate the motor controller to the corresponding peak torque at each speed, and adjust the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 to ensure that the maximum temperature of the IGBT reaches the preset maximum temperature t7 under the overload operation peak torque. Afterwards, by comparing the temperature limit distortion line corresponding to the first IGBT temperature rise slope ta4 under normal water entry conditions and the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 under abnormal water entry conditions, the difference method is used to estimate the temperature limit distortion line corresponding to the third IGBT temperature rise slope ta6 under the condition of zero IGBT water flow (i.e., extreme heat dissipation conditions).

[0096] Under abnormal water entry conditions (i.e., the IGBT water entry flow is half of the normal water entry conditions), starting from the second fixed speed, the speed is gradually increased to the maximum speed. At each speed, the motor controller is operated to the corresponding peak torque, and the temperature change of the IGBT is recorded.

[0097] According to the temperature change of the IGBT under abnormal water entry conditions, the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 is adjusted. The goal of the adjustment is to make the maximum temperature of the IGBT reach the maximum temperature t7 under the preset overload operation peak torque to ensure that the motor controller can still operate stably when the heat dissipation conditions are limited.

[0098] Obtain the temperature limit distortion line corresponding to the first IGBT temperature rise slope ta4 under normal water inlet conditions. Compare the temperature limit distortion lines corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, and analyze the difference between the two. Using the difference method, based on the temperature limit distortion lines corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, estimate the temperature limit distortion line corresponding to the third IGBT temperature rise slope ta6 under the condition that the IGBT water inlet flow rate is 0 (i.e., extreme heat dissipation conditions).

[0099] The interpolation method is a mathematical method used to estimate unknown data points based on known data points. Here, it is used to estimate the temperature limit distortion line under extreme heat dissipation conditions based on the temperature limit distortion lines under normal and abnormal water entry conditions.

[0100] Step 204 can ensure that the motor controller can maintain stable performance under different heat dissipation conditions by adjusting and optimizing the temperature limit distortion curve of the IGBT. In particular, under limited or extreme heat dissipation conditions, a reasonable temperature limit distortion curve can effectively prevent the IGBT from overheating and damage, and improve the reliability and durability of the motor controller.

[0101] Specifically, the embodiment of the present application adjusts the water flow rate to half of the water flow rate specified in the technical conditions, from 500rpm to the maximum speed, with 500rpm as a step, the torque is increased to the peak torque at each speed, and the temperature limit distortion line corresponding to ta5 is adjusted to make the maximum temperature of the IGBT reach t7. Compare the IGBT temperature limit distortion lines corresponding to ta4 and ta5, and obtain the temperature limit distortion line corresponding to ta6 through difference calculation. At this time, the IGBT temperature limit distortion line calibration is completed, and its corresponding torque limit table is as follows: Table 4

[0102] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0103] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor, characterized in that: The calibration method comprises: Obtain the sustainable operating temperature t1 of the permanent magnet synchronous motor; Obtaining a first delay temperature t2 at which the permanent magnet synchronous motor decreases from a peak power to a rated power; Obtaining a second delay temperature t3 of the permanent magnet synchronous motor from the peak power dropping to 0; Subtract the sustainable working temperature t1 from the first delay temperature t2 to obtain the torque limiting start temperature t4=t1-t2; The sustainable working temperature t1 is added to the first delay temperature t2 and the second delay temperature t3 to obtain the tube-off temperature t5=t1+t2+t3; A first temperature limit distortion curve is obtained according to the sustainable working temperature t1, the torque limit start temperature t4 and the tube shut-off temperature t5; Re-testing and calibrating the first temperature limit distortion curve to obtain a second temperature limit distortion curve; Under normal water entry conditions, the first motor temperature rise slope ta1 is obtained; under abnormal water entry conditions, the second motor temperature rise slope ta2 is obtained; under the condition that the motor water entry flow is 0, the third motor temperature rise slope ta3 is obtained according to the difference method; the motor water entry flow under the abnormal water entry condition is half of the motor water entry flow under the normal water entry condition; A first fixed speed is preset, and the first fixed speed is used as a step, from the first fixed speed to the maximum speed, the permanent magnet synchronous motor is operated to the corresponding peak torque at each speed, and the torque limit start temperature t4 and the torque limit coefficient of the sustainable working temperature t1 under the temperature rise slope ta2 of the second motor are adjusted so that the equilibrium temperature of the permanent magnet synchronous motor reaches the sustainable working temperature t1, and a third temperature limit torsion curve under the temperature rise slope ta2 of the second motor is obtained; The fourth temperature limit distortion curve at the third motor temperature rise slope ta3 is obtained by the difference method.

2. The calibration method according to claim 1, characterized in that: The sustainable operating temperature t1 of the permanent magnet synchronous motor is not greater than the demagnetization temperature of the permanent magnet of the motor.

3. The calibration method according to claim 1, characterized in that: The step of obtaining the temperature rise slope ta1 of the first motor under normal water entry conditions includes: Under normal water entry conditions, a first fixed speed is preset, and the permanent magnet synchronous motor is operated to a corresponding peak torque at each speed using the first fixed speed as a step, and the maximum value of the temperature rise of the permanent magnet synchronous motor is taken as the first motor temperature rise slope ta1.

4. The calibration method according to claim 1, characterized in that: The step of obtaining the temperature rise slope ta2 of the second motor under the abnormal water entry condition includes: Under abnormal water entry conditions, a first fixed speed is preset, and the permanent magnet synchronous motor is operated to the corresponding peak torque at each speed using the first fixed speed as a step, and the maximum value of the temperature rise slope of the permanent magnet synchronous motor is taken as the second motor temperature rise slope ta2; the motor water entry flow rate under the abnormal water entry condition is half of the motor water entry flow rate under the normal water entry condition.

5. A method for calibrating the temperature and temperature rise torque limit of a motor controller, characterized in that: The method comprises: A second fixed speed is preset, and the second fixed speed is used as a step, from the second fixed speed to the maximum speed, at each speed, the motor controller is operated to a corresponding peak torque and operated for a preset time, and the maximum temperature of the IGBT is taken as the torque limit start temperature t6 of the motor controller; The corresponding peak torque at each speed is increased by a preset percentage to obtain an overload operation peak torque, and the motor controller is operated to the corresponding overload operation peak torque and operated for a preset time at each speed from the second fixed speed to the maximum speed, taking the second fixed speed as a step, to obtain the maximum temperature t7 of the IGBT at the overload operation peak torque; the power is limited to the rated power at the maximum temperature t7 to obtain the IGBT temperature limit distortion curve; Under normal water entry conditions, the first IGBT temperature rise slope ta4 is obtained; under abnormal water entry conditions, the second IGBT temperature rise slope ta5 is obtained; under the condition that the IGBT water entry flow rate is 0, the third IGBT temperature rise slope ta6 is obtained according to the difference method; the IGBT water entry flow rate under the abnormal water entry condition is half of the IGBT water entry flow rate under the normal water entry condition; Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, the torque is run to the corresponding peak torque, and the temperature limit distortion line corresponding to the second IGBT temperature rise slope ta5 is adjusted to make the maximum temperature of the IGBT reach t7; the IGBT temperature limit distortion line corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5 are compared, and the temperature limit distortion line corresponding to the third IGBT temperature rise slope ta6 is obtained by the difference method.

6. The calibration method according to claim 5, characterized in that: The step of obtaining the first IGBT temperature rise slope ta4 under normal water entry conditions includes: Under normal water entry conditions, the motor controller is operated to the corresponding peak torque at each speed from the second fixed speed to the maximum speed, taking the second fixed speed as a step to obtain the first IGBT temperature rise slope ta4.

7. The calibration method according to claim 5, characterized in that: The step of obtaining the second IGBT temperature rise slope ta5 under the abnormal water entry condition includes: Under abnormal water entry conditions, taking the second fixed speed as a step, from the second fixed speed to the maximum speed, the motor controller is operated to the corresponding peak torque at each speed to obtain the second IGBT temperature rise slope ta5.

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