IGBT Thermal Capacity-Based Locked-Rotor Protection Method for Electric Drive System

Abstract

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

Description

Technical Field

[0001] This application belongs to the technical field of locked-rotor protection, and particularly relates to a locked-rotor protection method for an electric drive system based on the heat capacity of an IGBT. Background Art

[0002] The driving power of new energy vehicles comes from the electric control controller controlling the driving motor. When the motor is in the starting process, it may be in a locked-rotor state due to reasons such as the on-site environment or mechanical failures. When the motor is in a locked-rotor state, the starting current increases, resulting in a sharp rise in the temperature of the motor controller and the motor. If no protection intervention is carried out, it may cause damage to the controller or the motor.

[0003] Currently, most protection strategies for electric drive systems are based on locked-rotor time protection. This protection method mostly uses the locked-rotor time at peak torque as the protection time. Using the locked-rotor time at peak torque as the protection time will result in the inability to exert the maximum locked-rotor capacity of the system at other torque points. In some working conditions that do not require peak torque but require small torque and long-time locked-rotor, such as the anti-rollback working state, this protection strategy will have drawbacks and affect vehicle performance.

[0004] If the temperature of the IGBT in the motor controller is already in a high-temperature state before locked-rotor occurs, a long-time locked-rotor at this time may cause damage to the controller. Second, the calibration method of this protection uses a multi-angle test method. This method has a cumbersome test process. Multi-angles mean that multiple repeated tests are required. The accuracy of this multi-angle test is not high. The magnitude of the current generated by locked-rotor is related to the position of the motor. This test method may not be able to measure the maximum locked-rotor current, resulting in an overly long locked-rotor time at peak torque measured, leading to insufficient protection during locked-rotor at peak torque, and phenomena such as damage to the motor controller or the motor occurring. Summary of the Invention

[0005] The purpose of this application is to provide a locked-rotor protection method for an electric drive system based on the heat capacity of an IGBT. By real-time monitoring the temperature and current of the IGBT module, and calculating the locked-rotor protection time according to preset protection parameters and a data comparison table, overheating of the electric drive system during locked-rotor can be prevented.

[0006] To achieve the above purpose, an embodiment of this application provides a locked-rotor protection method for an electric drive system based on the heat capacity of an IGBT, including:

[0007] Setting a current And the data comparison table of the temperature rise slope of the IGBT module The current Is an equal value of the maximum current of the electric drive system, and the temperature rise slope of the IGBT module Is the fastest temperature rise slope of the IGBT module at this current calibrated and tested;

[0008] Set the maximum protection temperature allowed for stalling according to the characteristics of the IGBT module and the maximum residual heat capacity ;

[0009] Get real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity ;

[0010] According to the actual heat capacity value and the maximum heat capacity remaining value , compared with the calculated heat capacity residual value ;

[0011] 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 ;

[0012] 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:

[0013]

[0014] in, Indicates the stall protection time.

[0015] According to the above method of the embodiment of the present application, the following additional technical features may also be provided:

[0016] Further, get the real-time IGBT temperature , according to the maximum protection temperature Calculate the actual heat capacity , the formula is as follows:

[0017]

[0018] in, Indicates the actual heat capacity value, Indicates the maximum protection temperature, Indicates the real-time IGBT temperature.

[0019] Furthermore, according to the actual heat capacity and the maximum residual heat capacity , compared with the calculated heat capacity residual value ,include:

[0020] like ,but ; If , then .

[0021] Furthermore, set a data comparison table of the current and the temperature rise slope of the IGBT module , including:

[0022] Obtain the maximum current value of the electric drive system and divide it equally to obtain the equal division value of the maximum current of the electric drive system;

[0023] Obtain the rated voltage of the electric drive system, set the input voltage of the electric drive system to one-third of the rated voltage, and control the output current of the three phases respectively by controlling the duty cycle, and test the fastest temperature rise slope at different currents;

[0024] Multiply the fastest temperature rise slope at different currents by 1.5 times, and according to the equal division value of the maximum current of the electric drive system, obtain the data comparison table of the current and the temperature rise slope of the IGBT module .

[0025] Furthermore, if the output currents of the three phases are the same, take the maximum temperature rise slope at the same current of the three phases as the fastest temperature rise slope, multiply the maximum temperature rise slope at the same current of the three phases by 1.5 times, and according to the equal division value of the maximum current of the electric drive system, obtain the data comparison table of the current and the temperature rise slope of the IGBT module .

[0026] Adopting the electric drive system stall protection method based on the IGBT heat capacity provided by the embodiments of the present application, compared with the prior art, has the following beneficial technical effects:

[0027] In the embodiments of the present application, by real-time monitoring the temperature and current of the IGBT module and calculating the stall protection time according to the preset protection parameters and data comparison table, measures can be taken in time when the electric drive system is about to stall, avoiding overheating and damage, thereby significantly improving the safety of the electric drive system; since the embodiments of the present application can prevent the overheating of the electric drive system during stall in time, the thermal stress and mechanical stress of the IGBT module and other related components can be effectively reduced, thereby prolonging the service life of the electric drive system.

[0028] In the embodiments of the present application, by precisely controlling the stall protection time, it can ensure that the electric drive system can maintain stable performance output under various working conditions, avoiding performance degradation or failure caused by stall; since the embodiments of the present application can prevent the overheating and damage of the electric drive system, the downtime and maintenance cost caused by faults can be significantly reduced, thereby reducing the overall maintenance cost of the electric drive system. Description of the Drawings

[0029] Figure 1 The flowchart of the electric drive system stall protection method based on the IGBT heat capacity according to the embodiment of the present application is shown. Detailed implementation manners

[0030] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application 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 convenience of description, only the parts related to the present application rather than all the structures are shown in the drawings. 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.

[0031] The terms "including" and "having" and any variations thereof in the present 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 may alternatively include steps or units not listed, or may alternatively include other steps or units inherent to these processes, methods, products, or devices.

[0032] Referring to "embodiments" in the present application means that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in 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 the present application may be combined with other embodiments.

[0033] As Figure 1 shown, the embodiment of the present application provides an electric drive system stall protection method based on the IGBT heat capacity, including the following steps:

[0034] Step 101: Set a data comparison table of current and the IGBT module temperature rise slope. The current is an equal 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 at this current obtained by calibration testing.

[0035] In an electric drive system, the IGBT module is a key power conversion component. When the electric drive system stalls, the current will increase sharply, causing the temperature of the IGBT module to rise rapidly. To protect the IGBT module from overheating damage, an effective stall protection method needs to be set. The core of this method lies in real-time monitoring of the temperature and current of the IGBT module, and calculating the stall protection time according to the preset protection parameters. And the current and the IGBT module temperature rise slope The data comparison table is an indispensable part of this protection method.

[0036] Current For the setting of current, first, the maximum current value of the electric drive system needs to be obtained. This value is usually the maximum current that the system can withstand during normal operation. Then, this maximum current value is equally divided to obtain a series of equally divided current values. These equal values will be used as the current in the data comparison table. .

[0037] Next, it is necessary to test the temperature rise slope of the IGBT module at 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 respectively by controlling the duty cycle. This can simulate the working conditions of the electric drive system under different loads.

[0038] For each equally divided current value, it is necessary to test the temperature at different time points and calculate the corresponding temperature rise slope. This slope represents the rate of change of the temperature of the IGBT module with time at this current.

[0039] After obtaining the temperature rise slopes corresponding to all equally divided current values and multiplying them by 1.5, these data need to be sorted into a data comparison table as shown in the following table:

[0040] Table 1

[0041] I <![CDATA[I 1 > <![CDATA[I 2 > <![CDATA[I 3 > <![CDATA[I 4 > Δ℃ <![CDATA[Δ 1 ℃]]> <![CDATA[Δ 2 ℃]]> <![CDATA[Δ 3 °C]]> <![CDATA[Δ 4 °C]]>

[0042] It should be noted that if the output currents of the three phases are the same, the maximum temperature rise slope under the same current of the three phases should be taken as the fastest temperature rise slope at this current value. This is because in practical applications, the temperature rise of the IGBT module may be affected by various factors, and taking the maximum value can ensure the effectiveness of the protection method.

[0043] Specifically, as shown in the following table:

[0044] Table 2

[0045]

[0046] In addition, to increase the reliability of the protection method, the embodiment of this application also multiplies the maximum temperature rise slope under the same current of the three phases by 1.5 and then records it in the data comparison table. This can leave a certain safety margin to cope with possible abnormal situations.

[0047] 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 among the three-phase currents of the electric drive system Then, look up the corresponding IGBT module temperature rise slope according to the data comparison table Next, according to the preset maximum protection temperature allowing blocked rotation and the real-time IGBT temperature calculate the actual heat capacity value Then, compare the actual heat capacity value with the preset maximum remaining heat capacity value and take the smaller value as the remaining heat capacity value Finally, use the formula to calculate the blocked rotation protection time, and execute the blocked rotation protection measure when reaching or exceeding this protection time.

[0048] In summary, step 101 can provide strong support for the implementation of the blocked rotation protection method by accurately calibrating and testing the temperature rise slope of the IGBT module under different currents and making a data comparison table.

[0049] Step 102, set the maximum protection temperature allowing blocked rotation and the maximum remaining heat capacity value according to the IGBT module characteristics.

[0050] The IGBT module generates heat during operation. If the temperature is too high, it may cause module damage or performance degradation. Therefore, it is necessary to set a permitted maximum operating temperature, that is, the maximum protection temperature, according to the specific characteristics of the IGBT module, including its heat tolerance, heat dissipation conditions, etc. .

[0051] When the temperature of the IGBT module reaches or exceeds , the blocked rotation protection mechanism will be activated to prevent further temperature rise and possible damage.

[0052] Heat capacity refers to the ability of an object to absorb heat without significantly changing its temperature. In an electric drive system, the heat capacity of the IGBT module is related to factors such as its material, structure, and size. In the blocked rotation protection method, the maximum remaining heat capacity value represents how much heat the IGBT module can still absorb without triggering the protection mechanism at the permitted maximum protection temperature . The setting of this value needs to consider factors such as the heat dissipation ability of the IGBT module, the working environment temperature, and the expected load conditions.

[0053] When the actual heat capacity value (calculated from the real-time IGBT temperature and the maximum protection temperature ) exceeds the maximum remaining heat capacity value , the system will take blocked rotation protection measures, such as reducing the current, shutting down, etc., to prevent the IGBT module from overheating.

[0054] In summary, step 102 involves an in-depth understanding of the IGBT module characteristics, precise parameter measurement, and formulation of a reasonable protection strategy.

[0055] In step 103, obtain the real-time IGBT temperature and calculate the actual heat capacity value based on the maximum protection temperature.

[0056] The purpose of step 103 is to evaluate the current thermal state of the IGBT module for subsequent locked-rotor protection decisions.

[0057] Real-time IGBT temperature Refers to the actual temperature of the IGBT module at the current moment, and this temperature value needs to be measured in real time through a certain method (such as a temperature sensor).

[0058] Maximum protection temperature Is a safety temperature upper 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 lead to a decline in its performance.

[0059] Actual heat capacity value Is a parameter representing the current thermal state of the IGBT module. It reflects how much heat the IGBT module can still absorb without exceeding the safety limit from the current temperature to the maximum protection temperature between them. The larger this difference is, the more space the IGBT module has from the safety temperature upper limit, that is, it can absorb more heat.

[0060] Next, calculate the actual heat capacity value through the formula This formula is very simple and clear. It means that the actual heat capacity value is the difference between the maximum protection temperature and the real-time IGBT temperature The larger this difference is, the more space the IGBT module has from the safety temperature upper limit, that is, it can absorb more heat.

[0061] In practical applications, this step is very important. Because by monitoring the temperature of the IGBT module in real time and calculating the actual heat capacity value based on the set maximum protection temperature, the thermal state of the IGBT module can be understood in a timely manner. Once the actual heat capacity value approaches or reaches a certain critical value, we can trigger the locked-rotor protection mechanism to avoid overheating and damage of the IGBT module.

[0062] In addition, this step also reflects the refinement and intelligence of the IGBT module thermal management. Through real-time monitoring and calculation, the thermal state of the IGBT module can be grasped more accurately, thus making more reasonable protection decisions. This is of great significance for improving the reliability and safety of the electric drive system.

[0063] In summary, through the real-time monitoring and calculation of the thermal state of the IGBT module, step 103 provides an important basis for subsequent locked-rotor protection decisions.

[0064] Step 104: Calculate the remaining heat capacity value by comparing the actual heat capacity value and the maximum remaining heat capacity value.

[0065] Step 104 determines how much additional heat the IGBT module can withstand under a given thermal state, thus further determining the calculation of the locked-rotor protection time.

[0066] Actual heat capacity value is calculated based on the real-time IGBT temperature and the maximum protection temperature and represents the amount of heat that the IGBT module can still absorb from the current temperature to the maximum protection temperature.

[0067] Maximum remaining heat capacity value is set according to the characteristics of the IGBT module and represents the maximum additional heat that the IGBT module can withstand before reaching the maximum protection temperature.

[0068] Next, calculate the remaining heat capacity value based on these two parameters , if the actual heat capacity value is greater than the maximum remaining heat capacity value , then the remaining heat capacity value will take 's value. This means that although the IGBT module can still absorb more heat in the current state , for the purpose of protecting the IGBT module, we limit its remaining heat capacity value within .

[0069] If the actual heat capacity value is less than or equal to the maximum remaining heat capacity value , then the remaining heat capacity value will take 's value. This indicates that the amount of heat that the IGBT module can still absorb in the current state does not exceed its maximum tolerance , so the remaining heat capacity value is the actual heat capacity value .

[0070] The purpose of calculating the remaining heat capacity value is to evaluate the safety margin of the IGBT module under a given thermal state. By comparing the actual heat capacity value and the maximum remaining heat capacity value , it is possible to determine how much additional heat the IGBT module can withstand before reaching the maximum protection temperature. This is crucial for formulating a reasonable stall protection strategy, as it helps us maximize the use of its heat capacity while ensuring the safety of the IGBT module.

[0071] 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. This helps ensure the reliability and safety of the electric drive system while increasing the service life of the IGBT module.

[0072] Step 105, obtain the maximum current value among the three-phase currents of the electric drive system, and according to the data comparison table, find the IGBT module temperature rise slope corresponding to the maximum current value.

[0073] The electric drive system is usually driven by a three-phase motor, so there are three-phase currents. During real-time monitoring, it is necessary to obtain the values of these three-phase currents separately and compare their magnitudes to determine the maximum current value. . This maximum current value reflects the load condition of the electric drive system under the current working condition.

[0074] Before implementing the protection method, a data comparison table of current and the IGBT module temperature rise slope has been established through calibration tests. This data comparison table records the fastest temperature rise slopes of the IGBT module at different current values. When the maximum current value is obtained, the corresponding IGBT module temperature rise slope can be found in the data comparison table.

[0075] The establishment of the data comparison table is the premise and foundation of this step. When establishing the 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 IGBT module temperature rise slopes at different currents. 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.

[0076] Finally, organize the test data into a table form to form a data comparison table of current and the IGBT module temperature rise slope , and obtain the IGBT module temperature rise slope corresponding to the maximum current value .

[0077] Step 106, calculate the stall protection time for stall protection according to the remaining heat capacity value and the IGBT module temperature rise slope corresponding to the maximum current value.

[0078] The formula is as follows:

[0079]

[0080] Among them, represents the locked-rotor protection time, that is, when the electric drive system experiences a locked rotor, how long it needs to wait before triggering the protection mechanism; represents the remaining heat capacity value, which is the actual heat capacity value compared with the maximum remaining heat capacity value The result after comparison calculation. It reflects the ability of the IGBT module to withstand how much heat in the current state; represents the IGBT module temperature rise slope, which is the relationship between the current and the IGBT module temperature rise. This slope is obtained through calibration tests and is used to describe the temperature rise speed of the IGBT module under different currents.

[0081] In the electric drive system, the IGBT module is a key component, and its thermal management is crucial. When the system experiences a locked rotor, the current will increase sharply, causing the temperature of the IGBT module to rise rapidly. To protect the IGBT module from damage, it is necessary to monitor its temperature in real time and calculate the remaining heat capacity value based on the temperature . At the same time, it is also necessary to know the IGBT module temperature rise slope under different currents in order to accurately calculate the locked-rotor protection time

[0082] Specifically, in the embodiment of the present application, the temperature of the IGBT module is monitored in real time through a temperature sensor to obtain the real-time IGBT temperature ; according to the real-time temperature and the set maximum protection temperature , using the formula to calculate the actual heat capacity value ; comparing the actual heat capacity value with the set maximum remaining heat capacity value to determine the value according to the comparison result; monitoring the three-phase current of the electric drive system in real time and taking the maximum value among them as ; according to and the data comparison table, looking up the corresponding IGBT module temperature rise slope ; using the formula to calculate the locked-rotor protection time .

[0083] In practical applications, this formula and these steps are embedded in the control algorithm of the electric drive system. When the system detects a stall situation, it will automatically execute these steps to calculate the stall protection time, and trigger a protection mechanism such as cutting off the power supply or reducing the current after reaching the protection time, so as to prevent the IGBT module from overheating and being damaged.

[0084] 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 these steps reflects the refinement and intelligence of the thermal management of the IGBT module, and is of great significance for improving the reliability and safety of the electric drive system.

[0085] It should be noted that in this application, the terms "including", "comprising" or any other variants 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 another identical element 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 this 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 a different order than described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0086] The embodiments of this application have been described above in conjunction with the accompanying drawings. However, this application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of this application, those of ordinary skill in the art can also make many forms without departing from the purpose of this application and the scope protected by the claims, and all of them fall within the protection scope of this application.

Claims

1. A method for electric drive system stall protection based on IGBT thermal capacity, characterized in that: The protection method comprises: The maximum current value of the electric drive system is obtained and divided equally to obtain the equal-divided value of the maximum current of the electric drive system; the rated voltage of the electric drive system is obtained, the input voltage of the electric drive system is set to one third of the rated voltage, the output current of the three phases is controlled respectively by controlling the size of the duty cycle, and the fastest temperature rise slope under different currents is tested; the fastest temperature rise slope under different currents is expanded by 1.5 times, and the current is obtained according to the equal-divided value of the maximum current of the electric drive system. IGBT module temperature rise slope Data comparison table; wherein 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: 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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