Stall protection method for electric drive system based on IGBT thermal capacity

Abstract

The present application discloses a stall protection method for an electric drive system based on IGBT thermal capacity, and relates to the field of stall protection technology. The method includes setting a data comparison table of current and IGBT module temperature rise slope, real-time monitoring of IGBT temperature and three-phase current of the electric drive system, and calculating the actual thermal capacity value and IGBT module temperature rise slope according to the preset maximum protection temperature, maximum thermal capacity residual value and data comparison table, thereby obtaining the stall protection time. The embodiment of the present application can timely detect the risk of stalling of the electric drive system, avoid overheating damage, improve safety, and extend service life; by accurately controlling the stall protection time, ensure the stability of system performance and avoid performance degradation caused by stalling; at the same time, reduce downtime and maintenance costs, and reduce overall maintenance costs.

Description

Technical Field

[0001] The present application belongs to the technical field of stall protection, and in particular, relates to a stall protection method for an electric drive system based on IGBT thermal capacity. Background Art

[0002] The driving power of new energy vehicles comes from the electronic controller controlling the drive motor. When the motor is starting, it may be in a stalled state due to reasons such as the on-site environment or mechanical failure. When the motor is in a stalled state, the starting current increases, causing the motor controller and motor temperature to rise sharply. If no protective intervention is taken, the controller or motor may be damaged.

[0003] Currently, most electric drive system protection strategies are based on stall time protection. This protection method mostly uses the peak torque stall time as the protection time. Using the peak torque stall time as the protection time will result in the system's maximum stall capacity being unable to be exerted at other torque points. In some working conditions that do not require peak torque but require a long-term stall with a small torque, such as anti-slope working conditions, this protection strategy will have disadvantages and affect vehicle performance.

[0004] If the temperature of the IGBT of the motor controller is at a high temperature before the stall occurs, a long stall may damage the controller. Secondly, the calibration method of this protection is a multi-angle test method. The test process of this method is cumbersome, and multiple angles mean that multiple repeated tests are required. This multi-angle test is not accurate. The current generated by the stall is related to the position of the motor. This test method may not be able to measure the maximum stall current, so that the peak torque stall time measured is too long, resulting in insufficient protection during the peak torque stall, and damage to the motor controller or motor. Summary of the invention

[0005] The purpose of this application is to provide an electric drive system stall protection method based on IGBT thermal capacity, which prevents the electric drive system from overheating when stalled by monitoring the temperature and current of the IGBT module in real time and calculating the stall protection time according to preset protection parameters and data comparison table.

[0006] In order to achieve the above-mentioned purpose, the embodiment of the present application provides an electric drive system stall protection method based on IGBT thermal capacity, comprising: Set current IGBT module temperature rise slope Data comparison table, current is the equal-divided value of the maximum current of the electric drive system, the temperature rise slope of the IGBT module To calibrate the fastest temperature rise slope of the IGBT module under the current tested; Set the maximum protection temperature allowed for stalling according to the characteristics of the IGBT module and the maximum residual heat capacity ; Get real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity ; According to the actual heat capacity value and the maximum heat capacity remaining value , compared with the calculated heat capacity residual value ; Get the maximum current value among the three-phase currents of the electric drive system , according to the data comparison table, find the maximum current value Corresponding IGBT module temperature rise slope ; According to the residual heat capacity and maximum current value Corresponding IGBT module temperature rise slope , calculate the stall protection time to perform stall protection, the formula is as follows:

[0007] in, Indicates the stall protection time.

[0008] According to the above method of the embodiment of the present application, the following additional technical features may also be provided: Further, get the real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity , the formula is as follows:

[0009] in, Indicates the actual heat capacity value, Indicates the maximum protection temperature, Indicates the real-time IGBT temperature.

[0010] Furthermore, according to the actual heat capacity and the maximum residual heat capacity , compared with the calculated heat capacity residual value ,include: like ,but ;like ,but .

[0011] Furthermore, setting the current IGBT module temperature rise slope The data comparison table includes: Obtaining a maximum current value of the electric drive system and dividing it equally to obtain equally divided values ​​of the maximum current of the electric drive system; Get the rated voltage of the electric drive system, set the input voltage of the electric drive system to one third of the rated voltage, control the output current of the three phases by controlling the duty cycle, and test the fastest temperature rise slope under different currents; The fastest temperature rise slope under different currents is enlarged by 1.5 times, and the current is obtained according to the equal division value of the maximum current of the electric drive system. IGBT module temperature rise slope Data comparison table.

[0012] Furthermore, if the output current of the three phases is the same, the maximum temperature rise slope under the same current of the three phases is taken as the fastest temperature rise slope, the maximum temperature rise slope under the same current of the three phases is expanded by 1.5 times, and the current is obtained according to the equal division value of the maximum current of the electric drive system. IGBT module temperature rise slope Data comparison table.

[0013] Compared with the prior art, the electric drive system stall protection method based on IGBT thermal capacity provided by the embodiment of the present application has the following beneficial technical effects: The embodiment of the present application monitors the temperature and current of the IGBT module in real time, and calculates the stall protection time according to preset protection parameters and a data comparison table. It can take timely measures when the electric drive system is about to stall to avoid overheating and damage, thereby significantly improving the safety of the electric drive system. Since the embodiment of the present application can timely prevent the electric drive system from overheating when it stalls, it can effectively reduce the thermal stress and mechanical stress of the IGBT module and other related components, thereby extending the service life of the electric drive system.

[0014] The embodiments of the present application can ensure that the electric drive system can maintain stable performance output under various operating conditions by accurately controlling the stall protection time, thereby avoiding performance degradation or failure due to stall; because the embodiments of the present application can prevent overheating and damage to the electric drive system, it can significantly reduce downtime and maintenance costs caused by faults, thereby reducing the overall maintenance cost of the electric drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic flow chart of a method for stall protection of an electric drive system based on IGBT thermal capacity according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0016] 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.

[0017] 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.

[0018] 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.

[0019] like Figure 1 As shown, the embodiment of the present application provides an electric drive system stall protection method based on IGBT thermal capacity, comprising the following steps: Step 101 , setting a data comparison table of current and IGBT module temperature rise slope, where the current is an equal-division value of the maximum current of the electric drive system, and the IGBT module temperature rise slope is the fastest temperature rise slope of the IGBT module under the current obtained through calibration testing.

[0020] In the electric drive system, the IGBT module is a key power conversion component. When the electric drive system is stalled, the current will increase sharply, causing the temperature of the IGBT module to rise rapidly. In order to protect the IGBT module from overheating damage, an effective stall protection method needs to be set. The core of this method is to monitor the temperature and current of the IGBT module in real time, and calculate the stall protection time according to the preset protection parameters. IGBT module temperature rise slope The data comparison table is an indispensable part of this protection method.

[0021] Current To set the current of the electric drive system, you first need to obtain the maximum current value of the electric drive system, which is usually the maximum current that the system can withstand when it is operating normally. Then, divide this maximum current value into equal parts to obtain a series of equal current values. These equal parts will be used as the current values ​​in the data comparison table. .

[0022] Next, it is necessary to test the temperature rise slope of the IGBT module under different currents. During the test, the input voltage of the electric drive system needs to be set to one-third of the rated voltage, and the output current of the three phases is controlled by controlling the duty cycle. This can simulate the working conditions of the electric drive system under different loads.

[0023] For each equally divided current value, it is necessary to test its temperature at different time points and calculate the corresponding temperature rise slope. This slope represents the rate of change of the IGBT module temperature over time at this current.

[0024] After obtaining the temperature rise slope corresponding to all equally divided current values, expand it by 1.5 times and organize these data into a data comparison table, as shown in the following table: Table 1 I <![CDATA[I1]]> <![CDATA[I2]]> <![CDATA[I3]]> <![CDATA[I4]]> Δ℃ <![CDATA[Δ1℃]]> <![CDATA[Δ2℃]]> <![CDATA[Δ3℃]]> <![CDATA[Δ4℃]]> It should be noted that if the output current of the three phases is the same, the maximum temperature rise slope under the same current of the three phases should be taken as the fastest temperature rise slope under the current value. This is because in actual applications, the temperature rise of the IGBT module may be affected by many factors, and taking the maximum value can ensure the effectiveness of the protection method.

[0025] Specifically, as shown in the following table: Table 2

[0026] In addition, in order to increase the reliability of the protection method, the embodiment of the present application also expands the maximum temperature rise slope under the same current of three phases by 1.5 times before recording it in the data comparison table. This can leave a certain safety margin to deal with possible abnormal situations.

[0027] In the electric drive system stall protection method, the data comparison table is mainly used to calculate the stall protection time. When the system detects that the temperature of the IGBT module rises abnormally, it will immediately obtain the real-time IGBT temperature. and the maximum current value of the three-phase current of the electric drive system Then, search according to the data comparison table Corresponding IGBT module temperature rise slope Then, according to the preset maximum protection temperature allowed for stalling and real-time IGBT temperature Calculate the actual heat capacity Then the actual heat capacity value The maximum thermal capacity remaining value Compare and take the smaller value as the residual heat capacity Finally, use the formula Calculate the stall protection time and execute the stall protection measures when it reaches or exceeds this protection time.

[0028] In summary, step 101 can provide strong support for the implementation of the stall protection method by accurately calibrating and testing the temperature rise slope of the IGBT module under different currents and making a data comparison table.

[0029] Step 102: setting the maximum protection temperature and the maximum thermal capacity remaining value allowed for stalling according to the characteristics of the IGBT module.

[0030] IGBT modules generate heat during operation. If the temperature is too high, it may cause module damage or performance degradation. Therefore, it is necessary to set a maximum allowable operating temperature, i.e., the maximum protection temperature, based on the specific characteristics of the IGBT module, including its heat tolerance and heat dissipation conditions. .

[0031] When the temperature of the IGBT module reaches or exceeds The stall protection mechanism will activate to prevent further temperature increase and possible damage.

[0032] Thermal capacity refers to the ability of an object to absorb heat without significantly changing its temperature. In electric drive systems, the thermal capacity of IGBT modules is related to factors such as its material, structure, and size. In the stall protection method, the maximum thermal capacity residual value Represents the maximum allowable protection temperature How much heat can the IGBT module absorb without triggering the protection mechanism under this condition? The setting of this value needs to take into account factors such as the heat dissipation capacity of the IGBT module, the operating environment temperature, and the expected load conditions.

[0033] When the actual heat capacity (Based on the real-time IGBT temperature and maximum protection temperature Calculated) exceeds the maximum thermal capacity remaining value When the IGBT module is overheated, the system will take stall protection measures, such as reducing current and shutting down, to prevent the IGBT module from overheating.

[0034] In summary, step 102 involves an in-depth understanding of the characteristics of the IGBT module, precise parameter measurement, and formulation of a reasonable protection strategy.

[0035] Step 103, obtaining the real-time IGBT temperature, and calculating the actual thermal capacity value according to the maximum protection temperature.

[0036] The purpose of step 103 is to evaluate the current thermal state of the IGBT module so as to make a subsequent stall protection decision.

[0037] Real-time IGBT temperature It refers to the actual temperature of the IGBT module at the current moment. This temperature value needs to be measured in real time by some means (such as a temperature sensor).

[0038] Maximum protection temperature It is a safe temperature limit set according to the characteristics of the IGBT module. When the temperature of the IGBT module exceeds this value, it may cause damage to it or cause its performance to deteriorate.

[0039] Actual heat capacity It is a parameter indicating the current thermal state of the IGBT module. It reflects the current temperature To the maximum protection temperature How much heat can the IGBT module absorb without exceeding the safety limit?

[0040] Next, through the formula To calculate the actual heat capacity, this formula is very simple and clear, it expresses the actual heat capacity Is the maximum protection temperature With real-time IGBT temperature The larger the difference, the greater the space the IGBT module has to reach the upper limit of the safe temperature, which means it can absorb more heat.

[0041] In practical applications, this step is very important. By monitoring the temperature of the IGBT module in real time and calculating the actual thermal capacity value based on the set maximum protection temperature, the thermal status of the IGBT module can be understood in time. Once the actual thermal capacity value approaches or reaches a certain critical value, we can trigger the stall protection mechanism to prevent the IGBT module from overheating and damage.

[0042] In addition, this step also reflects the refinement and intelligence of IGBT module thermal management. Through real-time monitoring and calculation, the thermal status of the IGBT module can be more accurately understood, so that more reasonable protection decisions can be made. This is of great significance to improving the reliability and safety of the electric drive system.

[0043] In summary, step 103 provides an important basis for subsequent stall protection decision-making through real-time monitoring and calculation of the thermal state of the IGBT module.

[0044] Step 104, comparing and calculating the heat capacity remaining value based on the actual heat capacity value and the maximum heat capacity remaining value.

[0045] Step 104 determines how much additional heat the IGBT module can withstand under a given thermal condition, thereby further determining the calculation of the stall protection time.

[0046] Actual heat capacity Based on the real-time IGBT temperature and maximum protection temperature The calculated value represents the amount of heat that the IGBT module can still absorb between the current temperature and the maximum protection temperature.

[0047] Maximum residual heat capacity It is set according to the characteristics of the IGBT module and indicates the maximum additional heat that the IGBT module can withstand before reaching the maximum protection temperature.

[0048] Next, the residual heat capacity is calculated based on these two parameters If the actual heat capacity Greater than the maximum residual heat capacity , then the residual heat capacity Will take This means that although the IGBT module can absorb more heat in the current state , but in order to protect the IGBT module, we limit its thermal capacity residual value to Within.

[0049] If the actual heat capacity Less than or equal to the maximum thermal capacity remaining value , then the residual heat capacity Will take This means that the heat that the IGBT module can still absorb under the current state does not exceed its maximum tolerance. , so the residual heat capacity is the actual heat capacity .

[0050] Calculate the residual heat capacity The purpose of this is to evaluate the safety margin of the IGBT module under a given thermal condition. and the maximum residual heat capacity , it is possible to determine how much additional heat the IGBT module can withstand before reaching the maximum protection temperature. This is crucial for developing a reasonable stall protection strategy because it can help us maximize the thermal capacity of the IGBT module while ensuring its safety.

[0051] In summary, step 104 can evaluate the safety margin of the IGBT module under a given thermal state and formulate a reasonable stall protection strategy accordingly, which helps to ensure the reliability and safety of the electric drive system and improve the service life of the IGBT module.

[0052] Step 105 , obtaining the maximum current value among the three-phase currents of the electric drive system, and searching the IGBT module temperature rise slope corresponding to the maximum current value according to the data comparison table.

[0053] The electric drive system is usually driven by a three-phase motor, so there is a three-phase current. In the real-time monitoring process, it is necessary to obtain the values ​​of these three-phase currents separately and compare their sizes to determine the maximum current value. This maximum current value It reflects the load condition of the electric drive system under the current working conditions.

[0054] Before implementing the protection method, the current has been established through calibration tests IGBT module temperature rise slope The data comparison table records the fastest temperature rise slope of the IGBT module under different current values. After that, you can find the corresponding IGBT module temperature rise slope in the data comparison table. .

[0055] The establishment of a data comparison table is the premise and basis of this step. When establishing a data comparison table, it is necessary to obtain the maximum current value of the electric drive system and divide it equally, and then test the temperature rise slope of the IGBT module under different currents. In order to ensure the accuracy and reliability of the data, parameters such as input voltage and duty cycle need to be controlled during the test to simulate different working conditions.

[0056] Finally, the test data is organized into a table to form a current IGBT module temperature rise slope Data comparison table, get the maximum current value Corresponding IGBT module temperature rise slope .

[0057] Step 106 , calculating the stall protection time and performing stall protection according to the thermal capacity residual value and the IGBT module temperature rise slope corresponding to the maximum current value.

[0058] The formula is as follows:

[0059] in, Indicates the stall protection time, that is, when the electric drive system is stalled, how long does it take to trigger the protection mechanism? Indicates the residual value of heat capacity, which is the actual heat capacity value and the maximum residual heat capacity Compare the calculated results. It reflects how much heat the IGBT module can withstand in the current state; Indicates the temperature rise slope of the IGBT module, which is the current The relationship between the temperature rise of the IGBT module and the current. This slope is obtained through calibration testing and is used to describe the temperature rise rate of the IGBT module at different currents.

[0060] In electric drive systems, IGBT modules are key components, and their thermal management is critical. When the system is stalled, the current will increase sharply, causing the temperature of the IGBT module to rise rapidly. In order to protect the IGBT module from damage, it is necessary to monitor its temperature in real time and calculate the residual thermal capacity based on the temperature. At the same time, it is also necessary to know the temperature rise slope of the IGBT module at different currents. , in order to accurately calculate the stall protection time .

[0061] Specifically, the embodiment of the present application monitors the temperature of the IGBT module in real time through a temperature sensor to obtain the real-time IGBT temperature ; According to the real-time temperature and set the maximum protection temperature , using the formula Calculate the actual heat capacity ; The actual heat capacity The maximum heat capacity remaining value Make a comparison and determine based on the comparison results The value of; real-time monitoring of the three-phase current of the electric drive system, taking the maximum value as ;according to Compare the data table to find the corresponding IGBT module temperature rise slope ; Use the formula Calculate the stall protection time .

[0062] In actual applications, this formula and steps are embedded in the control algorithm of the electric drive system. When the system detects a stall situation, these steps are automatically executed to calculate the stall protection time and trigger a protection mechanism after the protection time is reached, such as cutting off the power supply or reducing the current, to prevent the IGBT module from overheating and being damaged.

[0063] In summary, step 106 is used to calculate the stall protection time to protect the IGBT module from damage. The application of this formula and step reflects the refinement and intelligence of the thermal management of the IGBT module, which is of great significance for improving the reliability and safety of the electric drive system.

[0064] 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.

[0065] 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 electric drive system stall protection based on IGBT thermal capacity, characterized in that: The protection method comprises: Set current IGBT module temperature rise slope Data comparison table, the current is the equal-divided value of the maximum current of the electric drive system, and the temperature rise slope of the IGBT module To calibrate the fastest temperature rise slope of the IGBT module under the current tested; Set the maximum protection temperature allowed for stalling according to the characteristics of the IGBT module and the maximum residual heat capacity ; Get real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity ; According to the actual heat capacity and the maximum heat capacity remaining value , compared with the calculated heat capacity residual value ; Get the maximum current value among the three-phase currents of the electric drive system , according to the data comparison table, find the maximum current value Corresponding IGBT module temperature rise slope ; According to the residual heat capacity and the maximum current value Corresponding IGBT module temperature rise slope , calculate the stall protection time to perform stall protection, the formula is as follows: ； in, Indicates the stall protection time.

2. The protection method according to claim 1, characterized in that: Acquiring real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity , the formula is as follows: in, Indicates the actual heat capacity value, Indicates the maximum protection temperature, Indicates the real-time IGBT temperature.

3. The protection method according to claim 1, characterized in that: According to the actual heat capacity value and the maximum heat capacity remaining value , compared with the calculated heat capacity residual value ,include: like ,but ;like ,but .

4. The protection method according to claim 1, characterized in that: The set current IGBT module temperature rise slope The data comparison table includes: Obtaining a maximum current value of the electric drive system and dividing it equally to obtain equally divided values ​​of the maximum current of the electric drive system; Get the rated voltage of the electric drive system, set the input voltage of the electric drive system to one third of the rated voltage, control the output current of the three phases by controlling the duty cycle, and test the fastest temperature rise slope under different currents; The fastest temperature rise slope under different currents is enlarged by 1.5 times, and the current is obtained according to the equal division value of the maximum current of the electric drive system. IGBT module temperature rise slope Data comparison table.

5. The protection method according to claim 4, characterized in that: If the output current of the three phases is the same, the maximum temperature rise slope under the same current of the three phases is taken as the fastest temperature rise slope, the maximum temperature rise slope under the same current of the three phases is enlarged by 1.5 times, and the current is obtained according to the equal division value of the maximum current of the electric drive system. IGBT module temperature rise slope Data comparison table.

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