Calibration Method for Temperature and Temperature Rise Torque Limiting of Permanent Magnet Synchronous Motor and Motor Controller

Abstract

The present application discloses a calibration method for temperature and temperature rise torque limitation of a permanent magnet synchronous motor and a motor controller, which relates to the technical field of motor torque limitation calibration. For the motor, the method includes formulating a temperature torque limitation curve by obtaining parameters such as the sustainable operating temperature and the delay temperature, and adjusting the torque limitation coefficient considering different water inlet conditions. For the motor controller, the method includes calibrating the highest temperature of the IGBT and the temperature torque limitation curve by running at a fixed speed until the peak torque, and also considering different water inlet conditions. This method ensures that the motor and the controller operate in an efficient and safe state, avoids overheating damage, improves the response speed and stability, extends the service life, reduces the maintenance cost, and enhances the overall performance and energy utilization rate.

Description

Technical Field

[0001] This application belongs to the technical field of motor torque limit calibration, and particularly relates to a calibration method for 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 of new energy vehicles, the motor and the motor controller will generate heat. When the vehicle operates under long-term heavy load and high power, the motor and the motor controller will experience over-temperature phenomena. Therefore, it is necessary to perform temperature torque limit on the electric drive system according to the temperature to ensure that the electric drive system will not be damaged due to excessive temperature.

[0003] Currently, the existing technology can perform torque limit and fault protection according to the current temperature of the motor and the motor controller. However, in actual use, due to the operating environment of the commercial vehicle electric drive system often being overloaded, and currently, due to problems such as the location of the motor temperature sensor and signal acquisition, the temperature rise of the motor has a delay. Therefore, on the vehicle, there are often phenomena such as excessive temperature torque limit resulting in insufficient climbing power of the vehicle or insufficient torque limit resulting in over-temperature of the motor. Summary of the Invention

[0004] The purpose of this application is to provide a calibration method for 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 through precise measurement and adjustment, ensures the motor and the motor controller operate in an efficient and safe state.

[0005] To achieve the above objective, an embodiment of this application provides a calibration method for temperature and temperature rise torque limit of a motor controller, including:

[0006] Preset a second fixed speed. Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding peak torque and run for a preset time, and take the highest temperature of the IGBT as the torque limit start temperature t6 of the motor controller;

[0007] Increase the corresponding peak torque at each speed by a preset percentage to obtain the overload operation peak torque. Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding overload operation peak torque and run for a preset time, and obtain the highest temperature t7 of the IGBT under the overload operation peak torque; Limit the power to the rated power at the highest temperature t7 to obtain the IGBT temperature torque limit curve;

[0008] Under normal water inlet conditions, obtain the first IGBT temperature rise slope ta4; under abnormal water inlet conditions, obtain the second IGBT temperature rise slope ta5; under the condition that the IGBT water inlet flow rate is 0, obtain the third IGBT temperature rise slope ta6 according to the difference method; the IGBT water inlet flow rate under abnormal water inlet conditions is half of the IGBT water inlet flow rate under normal water inlet conditions.

[0009] Taking the second fixed speed as a step, from the second fixed speed to the highest speed, at each speed, run the torque to the corresponding peak torque, and adjust the temperature limit torque curve corresponding to the second IGBT temperature rise slope ta5 so that the highest temperature of the IGBT reaches t7; compare the IGBT temperature limit torque curves corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, and obtain the temperature limit torque curve corresponding to the third IGBT temperature rise slope ta6 through the difference method.

[0010] According to the above method of the embodiment of the present application, the following additional technical features may also be included:

[0011] Further, under normal water inlet conditions, obtaining the first IGBT temperature rise slope ta4 includes:

[0012] Under normal water inlet conditions, taking the second fixed speed as a step, from the second fixed speed to the highest speed, at each speed, run the motor controller to the corresponding peak torque, and obtain the first IGBT temperature rise slope ta4.

[0013] Further, under abnormal water inlet conditions, obtaining the second IGBT temperature rise slope ta5 includes:

[0014] Under abnormal water inlet conditions, taking the second fixed speed as a step, from the second fixed speed to the highest speed, at each speed, run the motor controller to the corresponding peak torque, and obtain the second IGBT temperature rise slope ta5.

[0015] Adopting the calibration method for the temperature and temperature rise limit torque of the permanent magnet synchronous motor and the motor controller provided by the embodiment of the present application, compared with the prior art, it has the following beneficial technical effects:

[0016] In the embodiments of the present application, by accurately calibrating the sustainable working temperature, torque limit start temperature, and switch-off temperature of the motor, it can ensure that the motor operates in an efficient and safe state, avoiding performance degradation or damage caused by overheating; according to the motor temperature rise slope under different water inlet conditions, the embodiments of the present application adjust the torque limit coefficient and temperature torque limit curve, achieving precise control of the motor torque output, and improving the response speed and stability of the motor; the embodiments of the present application consider the motor temperature and temperature rise characteristics under various working conditions, including normal water inlet, abnormal water inlet, and no water flow, etc., enabling the motor to adapt to a wider working environment; through reasonable temperature control and torque limit strategies, the embodiments of the present application can reduce the thermal load and mechanical stress of the motor, thereby extending the service life of the motor and reducing the maintenance cost.

[0017] In the embodiments of the present application, by calibrating the maximum temperature and temperature torque limit curve of the IGBT, it ensures that the motor controller works in an efficient and stable state, improving the performance and reliability of the controller; considering the IGBT temperature rise slope under different water inlet conditions, the embodiments of the present application adjust the temperature torque limit curve to effectively manage the thermal load of the controller, avoiding performance degradation or faults caused by overheating; by optimizing the temperature and temperature rise torque limit calibration of the motor controller and the motor, the embodiments of the present application enable the entire electric drive system to operate in a more efficient state, improving energy utilization efficiency and overall performance; through precise temperature control and torque limit strategies, the embodiments of the present application reduce the heat loss and mechanical wear of the system, thereby reducing the maintenance cost and replacement cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It shows a schematic flow chart of 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;

[0019] Figure 2 It shows a schematic 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. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the above objects, features, and advantages of the present application more obvious and understandable, the following detailed description of the specific embodiments of the present application will be given in conjunction with the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the sake of description, only the parts related to the present application are shown in the drawings rather than all the structures. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0021] The term "comprising" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0022] Referring to "embodiment" in this application means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of this application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0023] As Figure 1 shown, the embodiment of this application provides a calibration method for the temperature and temperature rise torque limit of a permanent magnet synchronous motor, including the following steps:

[0024] Step 101, obtain the sustainable operating temperature t1 of the permanent magnet synchronous motor.

[0025] The purpose of step 101 is to determine the highest 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 motor permanent magnet, which is an important limiting condition for the sustainable operating temperature t1.

[0026] The permanent magnets in a permanent magnet synchronous motor are one of its 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 not be able to operate normally. 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 magnets. This limiting condition is crucial in the design and calibration process of the motor, ensuring that when the motor reaches its performance limit, its key components can still maintain normal operating conditions.

[0027] In practical applications, in order to determine the sustainable operating temperature t1 of the permanent magnet synchronous motor, a series of tests and calibration work usually need to be carried out. These works may include operating 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 ensured to meet the above limiting conditions.

[0028] Specifically, theoretically, a permanent magnet synchronous motor can operate continuously at its rated power. Therefore, under the specified inlet water temperature in the technical requirements, a temperature rise test is conducted within the operating speed range of the permanent magnet synchronous motor. Taking a permanent magnet synchronous motor with a rated operating speed of 1500 rpm, a maximum operating speed of 3500 rpm, and a rated power of 300 kw as an example, a rated power temperature rise test is carried out on 1500 rpm - 3500 rpm at 500 rpm steps respectively to obtain the rated temperature rise of the motor from 1500 rpm to 3500 rpm. Data processing is performed on the obtained rated temperature rise of the motor, and the highest motor temperature obtained is the sustainable operating temperature t1 of the permanent magnet synchronous motor.

[0029] Step 102: Obtain the first delay temperature t2 when the permanent magnet synchronous motor drops from peak power to rated power.

[0030] Step 102 involves the accurate measurement and understanding of the motor performance parameters. First, the definitions of peak power and rated power are explained. Among them, peak power refers to the maximum power that the motor can output in a short time; rated power refers to the maximum power allowed for the motor during long-term stable operation.

[0031] The first delay temperature t2 indicates that when the motor starts to drop from the peak power state until its output power stabilizes at the rated power, there will be an obvious change in the motor temperature during this process. The first delay temperature t2 is a parameter used to quantify this temperature change.

[0032] The first delay temperature t2 is one of the basic data for calculating the subsequent torque limit start temperature t4 and the switch-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.

[0033] In the fields of new energy vehicles, industrial automation, etc., permanent magnet synchronous motors are widely used due to their advantages such as high efficiency and high power density. Therefore, accurately calibrating the temperature and temperature rise torque limit characteristics of the motor is crucial for ensuring the stable operation of the equipment and extending its service life.

[0034] Specifically, for motor overtemperature torque limit, the external characteristics of the motor can be limited by looking up a table. For example, if the rated temperature rise of the permanent magnet synchronous motor is calculated to be 150 °C according to the above method, the rated power of the motor is 300 kw, and the peak power of the motor is 450 kw, then when the motor is at 150 °C, the corresponding external characteristic power limit coefficient should be 300 / 450 = 0.67.

[0035] Since the rise of the motor temperature has a delay, in order to better protect the permanent magnet synchronous motor from triggering an overtemperature fault and maintain good power performance during the motor temperature torque limit process, it is necessary to limit the torque of the motor in advance.

[0036] Regarding how to perform early torque limitation on a permanent magnet synchronous motor so that the motor does not trigger an over-temperature fault, the embodiment of the present application measures the delay time of the motor temperature rise when the motor reduces from the peak power to the rated power. For example, the operating speed corresponding to the peak power of the permanent magnet synchronous motor is 1500 rpm, the maximum operating speed is 3500 rpm, and the peak power is 450 kw. The technical requirements specify the inlet water temperature. The motor is operated from 1500 rpm to 3500 rpm in steps of 500 rpm until the peak power is reached. When the motor temperature reaches the rated temperature rise, the speed is kept constant, 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 decrease. Compare the several sets of temperatures obtained and take the highest temperature, which is the first delay temperature t2 of the permanent magnet synchronous motor when the power drops from the peak power to the rated power.

[0037] Step 103: Obtain the second delay temperature t3 when the permanent magnet synchronous motor reduces from the peak power to 0.

[0038] 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 accordingly set a torque limitation strategy to protect the motor. In this process, the acquisition and calculation of multiple temperature parameters are involved, including the sustainable working temperature t1, the first delay temperature t2, the second delay temperature t3, etc.

[0039] Specifically for step 103, it is about the acquisition of the "second delay temperature t3". This temperature parameter is the temperature delay value corresponding to the motor when it reduces from the peak power to 0 power. Simply put, when the motor is working at the peak power, if it needs to stop working and reduce to 0 power due to some reason (such as overheating), then during this process, the motor temperature will have a decreasing process, and the "second delay temperature t3" is a key parameter describing this process.

[0040] Specifically, continuing step 102, the motor is again operated from 1500 rpm to 3500 rpm in steps of 500 rpm until the peak power is reached. When the motor temperature reaches the rated temperature rise, the motor is shut down. Record at each speed how many degrees Celsius the motor temperature continues to rise after the motor is shut down before it starts to decrease. Compare the several sets of temperatures obtained and take the highest temperature as the second delay temperature t3 when the permanent magnet synchronous motor reduces from the peak power to 0.

[0041] Step 104: Subtract the first delay temperature t2 from the sustainable working temperature t1 to obtain the torque limitation start temperature t4 = t1 - t2.

[0042] In the embodiment of the present application, through step 101 and step 102, the sustainable working temperature t1 and the first delay temperature t2 are obtained. By subtracting the first delay temperature t2 from the sustainable working temperature t1, the torque limit start temperature t4 = t1 - t2 can be obtained.

[0043] The torque limit start temperature t4 plays a crucial role in the temperature management of the motor. When the actual working 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.

[0044] In the method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor, step 104 is the basis for determining the torque limit start temperature t4. This temperature value not only relates to the performance of the motor but also directly affects the service life and safety of the motor. Therefore, during calibration, the sustainable working temperature t1 and the first delay temperature t2 must be accurately measured and calculated to ensure that the obtained torque limit start temperature t4 is accurate and reliable.

[0045] Step 105: Add the sustainable working temperature t1, the first delay temperature t2, and the second delay temperature t3 to obtain the switch-off temperature t5 = t1 + t2 + t3.

[0046] In the embodiment of the present application, through step 101 to step 103, the sustainable working temperature t1, the first delay temperature t2, and the second delay temperature t3 are obtained. By adding these three temperatures, the switch-off temperature t5 = t1 + t2 + t3 can be obtained, which is used as an important basis for determining whether the motor needs to be switched off or other protection measures need to be taken.

[0047] In the method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor, step 105 is the basis for determining the switch-off temperature t5. The accurate calculation of the switch-off temperature t5 is crucial for the temperature management of the motor. When the actual working temperature of the motor approaches or reaches t5, the control system needs to take corresponding measures, such as switching off the motor, to prevent the motor from being damaged due to overheating.

[0048] Step 106: Obtain the first temperature torque limit curve based on the sustainable working temperature t1, the torque limit start temperature t4, and the switch-off temperature t5.

[0049] In the embodiment of the present application, the sustainable working temperature t1 is obtained through step 101, the torque limit start temperature t4 and the switch-off temperature t5 are obtained through step 104 and step 105. Based on these three temperatures, the first temperature torque limit curve can be obtained. The first temperature torque limit curve is a curve drawn according to parameters such as the sustainable working temperature t1, the torque limit start temperature t4, and the switch-off temperature t5, and 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.

[0050] In the method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor, step 106 is the key step connecting the temperature parameters and the motor torque output limit. By plotting the first temperature torque limit curve, it can be clearly seen the torque output limit of the motor at different temperatures, thus providing a scientific basis for the temperature management and protection of the motor.

[0051] The corresponding table of the first temperature torque limit curve is shown in the following table:

[0052] Table 1

[0053]

[0054] Among them, the second row is the torque limit coefficient corresponding to each temperature.

[0055] Step 107, conduct a re-inspection and calibration on the first temperature torque limit curve to obtain the second temperature torque limit curve.

[0056] The core of step 107 lies in "re-inspection and calibration", that is, verifying and adjusting the initially obtained first temperature torque limit curve to ensure its accuracy and reliability. Through re-inspection and calibration, a more accurate second temperature torque limit curve can be obtained, providing strong support for subsequent motor temperature management.

[0057] There may be certain errors or deviations in the initially obtained first temperature torque limit curve. Through re-inspection and calibration, these errors can be corrected to improve the accuracy of the curve. The re-inspection and calibration process usually includes multiple experiments and data analysis, which helps to enhance the reliability of the curve and make it more in line with the actual working conditions of the motor. The second temperature torque limit curve obtained through re-inspection and calibration can more accurately control the temperature of the motor, thereby optimizing its performance, improving efficiency and durability.

[0058] Step 107 plays a connecting role in the method for calibrating the temperature and temperature rise torque limit of a permanent magnet synchronous motor. It connects the initially obtained first temperature torque limit curve and the second temperature torque limit curve finally used for motor temperature management. Through re-inspection and calibration, it can be ensured that the obtained second temperature torque limit curve is accurate and reliable, thus providing strong guarantee for the safe and stable operation of the motor.

[0059] After obtaining the basic torque limit relationship through step 106, the embodiment of the present application conducts a re-inspection and calibration on it on the test bench. Specifically, using the water inlet temperature specified in the technical conditions, the following working conditions are used for test re-inspection respectively:

[0060] Working condition 1: low speed, peak torque; Working condition 2: peak power, peak torque; Working condition 3: maximum speed, peak power; Working condition 4: rated speed, peak power.

[0061] Under each working condition, when the temperature change of the motor is within 1°C within 10 minutes, stop the operation, observe the highest temperature and the equilibrium temperature under each working condition, select the point with the highest highest temperature and equilibrium temperature among the above working conditions, and compare it with t1. If the highest temperature and the equilibrium temperature are greater than t1, t1 - t2 can be reduced (the adjustment amount can refer to the equilibrium temperature minus t1); if the highest temperature and the equilibrium temperature are less than t1, t1 - t2 can be increased (the adjustment amount can refer to t1 - the equilibrium temperature), so that the highest temperature and the equilibrium temperature of the motor are close to t1 (the temperature difference can refer to 2°C).

[0062] After completing the above tests, if the highest temperature and the equilibrium temperature in the above working condition tests are close to t1 (the temperature difference can refer to 2°C), the temperature limit torque curve in the normal mode can be output at this time. During the actual vehicle use process, due to various factors such as the imbalance of the whole vehicle waterway temperature and the special and complex working conditions, only relying on the motor temperature limit torque cannot effectively protect the motor from overheating.

[0063] Therefore, the embodiment of the present application adopts a method of combining the motor temperature rise and the temperature limit torque to perform torque limit. 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 limit torque 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:

[0064] Table 2

[0065]

[0066] Step 108, under normal water inlet conditions, obtain the first motor temperature rise slope ta1; under abnormal water inlet conditions, obtain the second motor temperature rise slope ta2; under the condition that the motor water inlet flow rate is 0, obtain the third motor temperature rise slope ta3 according to the difference method; the motor water inlet flow rate under abnormal water inlet conditions is half of the motor water inlet flow rate under normal water inlet conditions.

[0067] Step 108 involves obtaining the temperature rise slope of the permanent magnet synchronous motor under different water inlet conditions. These conditions include normal water inlet conditions, abnormal water inlet conditions (the motor water inlet flow rate is half of the normal water inlet flow rate), and the condition that the motor water inlet flow rate is 0.

[0068] Among them, in the embodiment of the present application, the first motor temperature rise slope ta1 is obtained under normal water inlet conditions. Under normal water inlet conditions, first preset a first fixed speed, and take this first fixed speed as a step, gradually increase the speed until the highest speed is reached. At each speed, run the permanent magnet synchronous motor to the corresponding peak torque.

[0069] Record the temperature rise slope of the permanent magnet synchronous motor at each rotational speed, and take the maximum value among them 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.

[0070] In the embodiment of the present application, the second motor temperature rise slope ta2 is obtained 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), a first fixed rotational speed is also preset. Taking this first fixed rotational speed as a step, the rotational speed is gradually increased until the maximum rotational speed is reached.

[0071] At each rotational speed, run the permanent magnet synchronous motor to the corresponding peak torque, record the temperature rise slope of the permanent magnet synchronous motor at each rotational speed, and take the maximum value among them as the second motor temperature rise slope ta2. This process simulates the temperature rise characteristics of the motor under relatively harsh working conditions and helps to evaluate the performance of the motor under different conditions.

[0072] In the embodiment of the present application, the third motor temperature rise slope ta3 is obtained by the difference method. Under the condition that the motor water entry flow rate is 0, since the temperature rise slope cannot be directly measured, the difference method is used to obtain it.

[0073] The difference method usually estimates unknown data points (such as ta3 under the condition of 0 water entry flow rate) based on two or more known data points (such as ta1 under normal water entry conditions and ta2 under abnormal water entry conditions) through interpolation or extrapolation. Specific difference methods include linear difference, quadratic difference, etc., and the specific selection depends on the characteristics of the data and the required accuracy.

[0074] Specifically, under the specified technical requirement of water entry temperature and flow rate, taking 500 rpm as a step, from 500 rpm to the maximum rotational speed, directly increase the motor to the corresponding peak torque, and test the maximum value of the motor temperature rise slope under the specified technical requirement of water entry temperature and flow rate as the first motor temperature rise slope ta1 in the normal mode.

[0075] Reduce the motor water entry flow rate to half of the specified water entry flow rate, and use the same method to test the second motor temperature rise slope ta2 under abnormal water entry conditions of the motor, and then calculate the third motor temperature rise slope ta3 when the motor water entry flow rate is 0 according to the difference method.

[0076] Step 109, preset a first fixed rotational speed. Taking the first fixed rotational speed as a step, from the first fixed rotational speed to the maximum rotational speed, at each rotational speed, run the permanent magnet synchronous motor to the corresponding peak torque, and adjust the torque limit coefficients of the torque limit start temperature t4 and the sustainable working temperature t1 under the second motor temperature rise slope ta2 to make the equilibrium temperature of the permanent magnet synchronous motor reach the sustainable working temperature t1, so as to obtain the third temperature torque limit curve under the second motor temperature rise slope ta2.

[0077] In step 109, first, a first fixed rotational speed is preset. This is the starting point of the calibration process. A fixed rotational speed is selected as the starting point, and this rotational speed will serve as the basis for gradually increasing the rotational speed subsequently. Taking the first fixed rotational speed as a step, from the first fixed rotational speed to the maximum rotational speed, this means starting from the preset first fixed rotational speed and gradually increasing the rotational speed until the maximum rotational speed of the motor is reached. At each rotational speed step, a series of operations and measurements will be carried out.

[0078] At each rotational speed, the permanent magnet synchronous motor is run to the peak torque, which means that at each rotational speed step, the motor will be driven to its peak torque. The peak torque is the maximum torque that the motor can generate, which helps to evaluate the performance of the motor at different rotational speeds.

[0079] Adjusting the torque limit coefficients of the torque limit start temperature t4 and the sustainable operating temperature t1 under the second motor temperature rise slope ta2 is the core part of step 109. Under abnormal water inlet conditions (i.e., the motor water inlet flow rate is half of the normal water inlet flow rate), the second motor temperature rise slope ta2 has been obtained. Now, it is necessary to adjust the torque limit coefficients of the torque limit start temperature t4 and the sustainable operating temperature t1 according to this temperature rise slope. The torque limit coefficient determines the degree of torque limitation of the motor at different temperatures. The purpose of adjusting these coefficients is to make the equilibrium temperature of the motor under abnormal water inlet conditions reach the preset sustainable operating temperature t1.

[0080] By adjusting the torque limit coefficients, it can be ensured that when the motor operates under abnormal water inlet conditions, its equilibrium temperature can be maintained near the preset sustainable operating temperature t1. This helps to protect the motor from overheating damage and ensure its long-term stable operation.

[0081] After completing the above adjustments, a new temperature torque limit curve, that is, the third temperature torque limit curve, will be obtained. This curve reflects the torque limitation of the motor at different temperatures under abnormal water inlet conditions.

[0082] Specifically, the embodiment of the present application adopts a verification and debugging method for the torque limit coefficients under abnormal water inlet conditions. The motor water inlet flow rate is adjusted to half of the specified water inlet conditions. Taking 500 rpm as a step, from 500 rpm to the maximum rotational speed, at each rotational speed, the motor is run to the corresponding peak torque. Under the ta2 temperature rise rate, the torque limit coefficients of t1 - t2 and t1 are adjusted so that the equilibrium temperature of the motor reaches t1. At this time, the temperature torque limit curve under the ta2 temperature rise slope, that is, the third temperature torque limit curve, can be obtained.

[0083] Step 110, obtain the fourth temperature torque limit curve under the third motor temperature rise slope ta3 through the difference method.

[0084] Step 110 is based on the acquisition of 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. Further, the difference method is used to obtain the fourth temperature torque limit curve under the condition of the third motor temperature rise slope ta3.

[0085] The difference method is a mathematical method commonly used to estimate unknown data points based on known data points. In this calibration method, the difference method is used to estimate the temperature torque limit curve at the third motor temperature rise slope ta3 based on the known motor temperature rise slopes (ta1 and ta2) and their corresponding temperature torque limit curves.

[0086] 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 directly measured through experiments, while ta3 is calculated by the difference method based on ta1, ta2, and the corresponding water inlet flow conditions. According to the characteristics of the data and the required accuracy, select an appropriate difference method. Commonly used difference methods include linear difference, quadratic difference, etc. In this calibration method, the specific choice of the difference method may depend on the characteristics of the experimental data and the calibration requirements. Taking the temperature torque limit curves corresponding to the known ta1 and ta2 as the reference, the difference method is used to estimate the temperature torque limit curve corresponding to ta3.

[0087] As Figure 2 shown, the embodiment of the present application provides a calibration method for the temperature and temperature rise torque limit of a motor controller, including the following steps:

[0088] Step 201, preset a second fixed speed. Taking the second fixed speed as a step, from the second fixed speed to the highest speed, at each speed, run the motor controller to the corresponding peak torque and run for a preset time, and take the highest temperature of the IGBT as the torque limit start temperature t6 of the motor controller.

[0089] In step 201, first, it is necessary to set a starting speed value, that is, the second fixed speed. This speed value is determined according to experimental requirements, the design specifications of the motor controller, and safety considerations. Next, starting from the second fixed speed, gradually increase the speed until the highest speed of the motor controller is reached. In this process, each speed point needs to be used 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 sufficient power to drive the load to reach the predetermined torque value.

[0090] At each speed stage, when the motor controller operates at the corresponding peak torque, it is necessary to record the highest temperature of the IGBT (Insulated Gate Bipolar Transistor). The IGBT is a key component in the motor controller, and its temperature has an important impact on the performance and lifespan of the motor controller. Among all speed stages, the highest temperature of the IGBT is set as 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.

[0091] The purpose of this step is to determine the temperature performance of the motor controller at different speeds and torques, and accordingly set a safe temperature limit (i.e., the torque limit start temperature t6). This is crucial for protecting the motor controller and improving the reliability and durability of the system.

[0092] Specifically, due to the different temperature change characteristics of the IGBT and the motor, after the torque drops, the temperature of the IGBT rises without delay and then directly drops. Therefore, first, it is necessary to confirm that the motor controller can meet the peak power operation time. Under the water inlet conditions specified in the technical agreement, taking 500 rpm as a step, from 500 rpm to the maximum speed, at each speed, increase the torque to the peak torque, operate for the operation time specified in the technical conditions, and record the highest temperature of the IGBT as the torque limit start temperature t6 of the motor controller.

[0093] Step 202: Increase the corresponding peak torque at each speed by a preset percentage to obtain the peak torque for overload operation. Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, operate the motor controller at the corresponding peak torque for overload operation and operate for a preset time to obtain the highest temperature t7 of the IGBT at the peak torque for overload operation; limit the power to the rated power at the highest temperature t7 to obtain the IGBT temperature torque limit curve.

[0094] In step 202, first, it is necessary to determine an initial peak torque, which is usually determined during the design or testing stage of the electric drive system. Then, increase this initial peak torque by a preset percentage to obtain a new peak torque value, that is, the peak torque for overload operation. This preset percentage can be determined according to the actual application requirements and the performance of the motor controller.

[0095] Next, starting from the second fixed speed, gradually increase the speed until the maximum speed is reached. At each speed, operate the motor controller at the peak torque for overload operation. This process is to simulate the load conditions of the motor controller during actual operation and observe the temperature change of the IGBT at different speeds and torques.

[0096] At each rotational speed, when the motor controller operates at the peak torque of overload operation, record the highest temperature t7 of the IGBT. These temperature data will be used for subsequent analysis and calibration.

[0097] Finally, limit the power to the rated power, and based on the previously obtained temperature data (including t7), plot the temperature-torque limit curve of the IGBT. This curve describes the torque magnitude that the motor controller needs to limit in order to maintain stable operation at different temperatures. It is an important part of the temperature management and protection strategy of the motor controller.

[0098] Specifically, due to the deviation in batch consistency of the motors, in the embodiments of this application, the peak torque is increased by 10%. Taking 500 rpm as a step on the test bench, from 500 rpm to the highest rotational speed, at each rotational speed, increase the torque to the peak torque of overload operation, operate for the operation time specified by the operating technical conditions, record the highest temperature t7 of the IGBT. At this time, it can be considered that the motor controller is operating abnormally. At this time, the power can be limited to the rated operating condition, and at this time, the temperature-torque limit curve of the IGBT can be output. The corresponding torque limit table is shown in the following table:

[0099] Table 3

[0100]

[0101] Among them, the second row is the torque limit coefficient corresponding to each temperature.

[0102] Step 203: Under normal water inlet conditions, obtain the first IGBT temperature rise slope ta4; under abnormal water inlet conditions, obtain the second IGBT temperature rise slope ta5; under the condition that the IGBT water inlet flow rate is 0, obtain the third IGBT temperature rise slope ta6 according to the difference method; the IGBT water inlet flow rate under abnormal water inlet conditions is half of the IGBT water inlet flow rate under normal water inlet conditions.

[0103] Step 203 describes the process of obtaining the IGBT temperature rise slope under three different IGBT water inlet flow rate conditions (normal water inlet, abnormal water inlet, water inlet flow rate is 0).

[0104] Under normal water inlet conditions, in the embodiments of this application, taking a preset second fixed rotational speed as a step, gradually increase from this rotational speed to the highest rotational speed. At each rotational speed, operate the motor controller to the corresponding peak torque and record the temperature change of the IGBT. By operating the motor controller at different rotational speeds and observing the temperature change of the IGBT, the temperature rise slope ta4 of the IGBT under normal water inlet conditions can be calculated. This slope reflects the thermal response characteristics of the IGBT under normal heat dissipation conditions.

[0105] Under abnormal water inlet conditions (i.e., the IGBT water inlet flow rate is half of that under normal water inlet conditions), also taking the second fixed speed as a step, gradually increase from this speed to the maximum speed. At each speed, run the motor controller to the corresponding peak torque and record the temperature change of the IGBT. By simulating the situation where the heat dissipation conditions are limited, the temperature rise slope ta5 of the IGBT under abnormal water inlet conditions can be calculated. This slope helps to evaluate the thermal response characteristics of the IGBT when the heat dissipation conditions are poor.

[0106] Under the condition that the IGBT water inlet flow rate is 0 (i.e., there is no heat dissipation at all), since direct experiments may cause the IGBT to overheat and be damaged, 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 inlet conditions and abnormal water inlet conditions, and estimates the temperature rise slope under the no-heat-dissipation condition through interpolation or extrapolation. Although the temperature rise slope under the no-heat-dissipation condition cannot be directly obtained through experiments, the slope under this condition can be estimated by the difference method, so as to more comprehensively understand the thermal response characteristics of the IGBT under different heat dissipation conditions.

[0107] Specifically, consistent with the motor temperature rise torque limit strategy, due to various factors such as the imbalance of the vehicle waterway temperature and the special and complex working conditions, only relying on temperature torque limit cannot effectively protect the IGBT from overheating. Consistent with the motor temperature rise torque limit strategy, adjust the water inlet flow rate to the water inlet flow rate specified in the technical conditions. From 500 rpm to the maximum speed, taking 500 rpm as a step, increase the torque to the peak torque at each speed, compare the data to 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 500 rpm to the maximum speed, taking 500 rpm as a step, increase the torque to the peak torque at each speed, compare the data to obtain the second IGBT temperature rise slope ta5, and perform a difference calculation on ta4 and ta5 to obtain the third IGBT temperature rise slope ta6 when the water inlet flow rate is 0.

[0108] Step 204, taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the torque to the corresponding peak torque, adjust the temperature torque limit curve corresponding to the second IGBT temperature rise slope ta5 to make the highest temperature of the IGBT reach t7; compare the IGBT temperature torque limit curves corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, and obtain the temperature torque limit curve corresponding to the third IGBT temperature rise slope ta6 through the difference method.

[0109] The main task of step 204 is, under abnormal water inlet conditions, starting from the second fixed speed as a step, gradually increasing the speed to the maximum speed. At each speed, run the motor controller to the corresponding peak torque, and adjust the temperature limit torque curve corresponding to the second IGBT temperature rise slope ta5 to ensure that the highest temperature of the IGBT reaches the highest temperature t7 under the preset peak torque of overload operation. Then, by comparing the temperature limit torque curve corresponding to the first IGBT temperature rise slope ta4 under normal water inlet conditions and the temperature limit torque curve corresponding to the second IGBT temperature rise slope ta5 under abnormal water inlet conditions, use the difference method to estimate the temperature limit torque curve corresponding to the third IGBT temperature rise slope ta6 under the condition of zero IGBT water inlet flow (i.e., extreme heat dissipation conditions).

[0110] Under abnormal water inlet conditions (i.e., the IGBT water inlet flow is half of that under normal water inlet conditions), starting from the second fixed speed, gradually increase the speed to the maximum speed. At each speed, run the motor controller to the corresponding peak torque and record the temperature change of the IGBT.

[0111] According to the temperature change of the IGBT under abnormal water inlet conditions, adjust the temperature limit torque curve corresponding to the second IGBT temperature rise slope ta5. The adjustment target is to make the highest temperature of the IGBT reach the highest temperature t7 under the preset peak torque of overload operation to ensure the stable operation of the motor controller when the heat dissipation condition is limited.

[0112] Obtain the temperature limit torque curve corresponding to the first IGBT temperature rise slope ta4 under normal water inlet conditions. Compare the temperature limit torque curves corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, and analyze the differences between them. Use the difference method to estimate the temperature limit torque curve corresponding to the third IGBT temperature rise slope ta6 under the condition of zero IGBT water inlet flow (i.e., extreme heat dissipation conditions) based on the temperature limit torque curves corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5.

[0113] The difference 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 torque curve under extreme heat dissipation conditions based on the temperature limit torque curves under normal and abnormal water inlet conditions.

[0114] By adjusting and optimizing the temperature limit torque curve of the IGBT in step 204, it can ensure that the motor controller maintains stable performance under different heat dissipation conditions. Especially under limited or extreme heat dissipation conditions, a reasonable temperature limit torque curve can effectively prevent the IGBT from overheating and damage, and improve the reliability and durability of the motor controller.

[0115] Specifically, in the embodiments of the present application, the water inlet flow rate is adjusted to half of the water inlet flow rate specified in the technical conditions. From 500 rpm to the maximum speed, with a step of 500 rpm, the torque is increased to the peak torque at each speed, and the temperature limit torque curve corresponding to ta5 is adjusted so that the maximum temperature of the IGBT reaches t7. By comparing the IGBT temperature limit torque curves corresponding to ta4 and ta5, the temperature limit torque curve corresponding to ta6 is obtained through difference calculation. At this time, the calibration of the IGBT temperature limit torque curve is completed, and the corresponding torque limit table is shown as follows:

[0116] Table 4

[0117]

[0118] It should be noted that in the present application, the terms "including", "comprising" 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 not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments 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 the reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0119] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them fall within the protection scope of the present application.

Claims

1. A calibration method for the temperature and temperature rise torque limit of a motor controller, characterized in that, The method includes: Preset a second fixed speed. Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding peak torque and run for a preset time, and take the highest temperature of the IGBT as the starting temperature t6 of torque limitation for the motor controller; Increase the corresponding peak torque at each speed by a preset percentage to obtain the peak torque during overload operation. Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding peak torque during overload operation and run for a preset time, and obtain the highest temperature t7 of the IGBT under the peak torque during overload operation; Limit the power to the rated power at the highest temperature t7 to obtain the IGBT temperature torque limitation curve; Under normal water inlet conditions, obtain the first IGBT temperature rise slope ta4; under abnormal water inlet conditions, obtain the second IGBT temperature rise slope ta5; under the condition that the IGBT water inlet flow rate is 0, obtain the third IGBT temperature rise slope ta6 according to the difference method; the IGBT water inlet flow rate under the abnormal water inlet conditions is half of the IGBT water inlet flow rate under the normal water inlet conditions; Taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the torque to the corresponding peak torque, adjust the temperature torque limitation curve corresponding to the second IGBT temperature rise slope ta5 to make the highest temperature of the IGBT reach t7; Compare the IGBT temperature torque limitation curves corresponding to the first IGBT temperature rise slope ta4 and the second IGBT temperature rise slope ta5, and obtain the temperature torque limitation curve corresponding to the third IGBT temperature rise slope ta6 through the difference method.

2. The calibration method according to claim 1, wherein The step of obtaining the first IGBT temperature rise slope ta4 under normal water inlet conditions includes: Under normal water inlet conditions, taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding peak torque to obtain the first IGBT temperature rise slope ta4.

3. The calibration method according to claim 1, wherein The step of obtaining the second IGBT temperature rise slope ta5 under abnormal water inlet conditions includes: Under abnormal water inlet conditions, taking the second fixed speed as a step, from the second fixed speed to the maximum speed, at each speed, run the motor controller to the corresponding peak torque to obtain the second IGBT temperature rise slope ta5.

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