A method for verifying the loss of IGBT modules based on the whole-machine test waveform

Abstract

The present invention discloses a method for verifying the loss of an IGBT module based on the whole-machine test waveform, which includes step S1: calculating the loss of the upper-bridge IGBT. The specific implementation is as follows: Step S1.1: When the whole machine is running, collect the voltage, current and corresponding junction temperature data of a certain-phase upper-bridge IGBT through an oscilloscope and a temperature acquisition device, and intercept a part of the data, requiring that the intercepted data contains and only contains a complete positive half-cycle of the current. The method for verifying the loss of an IGBT module based on the whole-machine test waveform disclosed by the present invention can calculate the loss of the IGBT module according to the voltage and current waveforms and junction temperature data collected during the operation of the whole machine, thereby solving the problems of large calculation errors and difficult loss verification when the modules are in parallel or single transistors are in parallel, and when the current distortion is large, making the verification of the IGBT module loss more accurate and convenient.

Description

Technical Field

[0001] The present invention belongs to the technical field of IGBT module loss calculation, and particularly relates to a method for verifying IGBT module loss based on the whole-machine test waveform. Background Art

[0002] In existing automotive electric drive systems, IGBT modules are widely used. The loss of the IGBT module affects both the junction temperature estimation of the IGBT module and the efficiency analysis of the inverter. The traditional method for calculating the loss of the IGBT module is to calibrate the switching loss of the module in advance through double-pulse testing, and to calibrate the voltage-current curve when the module is conducting in advance through a static parameter tester. Finally, the closed-loop of loss calculation is realized through the junction temperature estimation method. However, in some cases, the loss calculated by this method has a large error and is difficult to verify. For example:

[0003] ① The power components in the whole machine adopt the method of module parallel connection or single transistor parallel connection. Due to uneven current sharing, the losses of different modules or single transistors are inconsistent. The inconsistent losses will cause different junction temperatures of different modules or single transistors, and the different junction temperatures will further affect the losses of the modules or single transistors. Eventually, a dynamic balance of losses and junction temperatures will be reached. It is difficult to accurately simulate this dynamic process only relying on junction temperature estimation, resulting in deviations in the calculated losses or junction temperatures.

[0004] ② When calibrating the efficiency map, it is necessary to calibrate the loss of the IGBT module in the high-speed region. Compared with the medium and low-speed regions, the carrier ratio in the high-speed region is relatively low, and overmodulation may occur, which will result in relatively poor sinusoidality of the current, and the loss error calculated by the traditional method will also be larger.

[0005] Therefore, in view of the above problems, further improvements are made. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for verifying IGBT module loss based on the whole-machine test waveform. According to the voltage-current waveform and junction temperature data collected during the operation of the whole machine, the loss of the IGBT module can be calculated, thus solving the problems of large loss calculation errors and difficult loss verification when module parallel connection or single transistor parallel connection is used, as well as when the current distortion is large, making the verification of IGBT module loss more accurate and convenient.

[0007] To achieve the above object, the present invention provides a method for verifying IGBT module loss based on the whole-machine test waveform, including the following steps:

[0008] Step S1: Calculate the loss of the upper-bridge IGBT. The specific implementation is as follows:

[0009] Step S1.1: When the whole machine is running, collect the voltage, current, and corresponding junction temperature data of the IGBT in the upper bridge of a certain phase through an oscilloscope and a temperature acquisition device, and intercept a part of the data. It is required that the intercepted data contains and only contains a complete positive half-cycle of the current, and the total length of the intercepted current data is less than a complete current fundamental period T. Let the sampling data time interval of the oscilloscope be Δt, and the intercepted current, voltage, and corresponding junction temperature data of the upper bridge IGBT be i k , v k and T jk , k = 1, 2, …, n;

[0010] Step S1.2: Accurate extraction of positive half-cycle current data: Let the bus voltage be V bus , the zero offsets of the current i k and the voltage v k be I Dev , V Dev , then there are:

[0011]

[0012] After zero-offset calibration, the new current i k_Dev and voltage v k_Dev are:

[0013]

[0014] Let i c_Sum be the cumulative integral of i k_Dev , then:

[0015]

[0016] Among them, the minimum value of i c_Sum is i c_Sum_min , and the corresponding c = a; the maximum value of i c_Sum is i c_Sum_max , and the corresponding c = b, where a and b satisfy 1 < a < b < n; if there are multiple minimum or maximum points, then a takes the first point and b takes the last point (for example, in the sequence c = 1, 2, …, a1, a2, a3, a4, …, b1, b2, b3, b4, …, n, i a2_Sum = i a3_Sum = i c_Sum_min , i b2_Sum = i b3_Sum = i c_Sum_max , then a = a2, b = b3);

[0017] The upper bridge IGBT only works when the output current is in the positive half-cycle. Then, the current, voltage, and junction temperature of the upper bridge IGBT corresponding to the extracted positive half-cycle of the current are i m_Dev , vm_Dev and T jm , m = a, a + 1, …, b - 1, b;

[0018] Step S1.3: Determination of loss calculation interval: A normally operating IGBT has three states: conduction state, switching state, and cut-off state; when the IGBT is in the conduction state, conduction loss will occur; when the IGBT is in the switching state, switching loss will occur; when the IGBT is in the cut-off state (due to its very small leakage current), the loss in the cut-off state can be ignored, where:

[0019] Let i m_Dev The maximum value of is i m_Dev_max , I c_Low is the threshold current for determining the cut-off state of the IGBT. When i m_Dev < I c_Low , the IGBT is in the cut-off state (usually I c_Low = 0.02i m_Dev_max ); Let V ce_Low be the threshold voltage for determining the non-conduction state of the IGBT. When v m_Dev ≥ V ce_Low , the IGBT is in the non-conduction state (usually V ce_Low = 0.06V bus ), then the IGBT conduction state satisfies:

[0020]

[0021] The IGBT switching state satisfies:

[0022]

[0023] Find all the points in the current i m_Dev and voltage v m_Dev that satisfy the formula in the IGBT conduction state, reorder these points, and let the corresponding current and junction temperature be i cond_Cal and T jcond_Cal , cond_Cal = 1, 2…, n cond , where, n cond < (b - a), then i cond_Cal and T jcond_Cal are the intervals for calculating the conduction loss;

[0024] Similarly, find all the points in the current i m_Dev and voltage v m_Dev that satisfy the formula in the IGBT switching state, reorder these points, and let the corresponding current and voltage be i sw_Cal , v sw_Cal , sw_Cal = 1, 2…, n sw, where n sw <(b - a), then i sw_Cal and v sw_Cal is the interval for calculating the switching loss;

[0025] Step S1.4: Loss calculation: Assume that the Vce / Ic curves of the upper - bridge IGBT at different Tj have been calibrated. Then, by means of look - up table interpolation or formula fitting, obtain the on - state voltage drop of the IGBT at current i cond_Cal and junction temperature T jcond_Cal as follows:

[0026]

[0027] The on - state loss of the IGBT is:

[0028]

[0029] The switching loss of the IGBT is:

[0030]

[0031] The total loss of the IGBT is:

[0032] P IGBT = P cond + P sw ;

[0033] Step S2: Calculate the loss of the lower - bridge IGBT;

[0034] Step S3: Calculate the loss of the upper - bridge Diode;

[0035] Step S4: Calculate the loss of the lower - bridge Diode (Steps S1 - S4 do not have a strict sequence).

[0036] As a further preferred technical solution of the above - mentioned technical solution, in Step S2, use an oscilloscope and a temperature acquisition device to collect the corresponding lower - bridge voltage and current and the lower - bridge IGBT junction temperature data when intercepting the negative half - cycle of the output current (the calculation principle and method are the same as those of the sub - steps of Step S1).

[0037] As a further preferred technical solution of the above - mentioned technical solution, in Step S3, use an oscilloscope and a temperature acquisition device to collect the corresponding upper - bridge voltage and current and the upper - bridge Diode junction temperature data when intercepting the negative half - cycle of the output current.

[0038] As a further preferred technical solution of the above technical solution, in step S4, an oscilloscope and a temperature acquisition device are used to collect the lower-bridge voltage and current and the lower-bridge Diode junction temperature data corresponding to the positive half-cycle of the intercepted output current (in the calculation of the losses of the upper and lower-bridge Diodes, the calculation of the forward conduction loss of the Diode can refer to the conduction loss calculation method of the upper-bridge IGBT, and the reverse recovery loss of the Diode can refer to the switching loss calculation method of the upper-bridge IGBT).

[0039] To achieve the above object, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for verifying the IGBT module loss based on the whole-machine test waveform are implemented.

[0040] To achieve the above object, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for verifying the IGBT module loss based on the whole-machine test waveform are implemented.

[0041] The beneficial effects of the present invention are as follows:

[0042] The present invention provides a method for verifying the IGBT module loss based on the whole-machine test waveform. The traditional method for testing the IGBT module loss is to calibrate the parameters related to the module loss in advance through double-pulse testing and static parameter testing, and calculate the loss through junction temperature estimation. This method has a large calculation error for power components using module parallel connection or single-tube parallel connection, or when the current distortion is large, and the loss is difficult to verify. According to the voltage and current waveforms and junction temperature data collected during the whole-machine operation, the present invention can calculate the loss of the IGBT module, thus solving the problems of large calculation errors and difficult loss verification when module parallel connection or single-tube parallel connection is used, and when the current distortion is large, making the loss verification of the IGBT module more accurate and convenient. Description of the Drawings

[0043] Figure 1 It is a schematic diagram of a method for verifying the IGBT module loss based on the whole-machine test waveform of the present invention. Detailed Embodiments

[0044] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description can be applied to other embodiments, variations, improvements, equivalent embodiments, and other technical solutions without departing from the spirit and scope of the present invention.

[0045] In a preferred embodiment of the present invention, those skilled in the art should note that the IGBT modules and the like involved in the present invention can be regarded as the prior art.

[0046] Preferred embodiment.

[0047] The present invention discloses a method for verifying the loss of an IGBT module based on the whole-machine test waveform, including the following steps:

[0048] Step S1: Calculate the loss of the upper-bridge IGBT. The specific implementation is as follows:

[0049] Step S1.1: When the whole machine is running, collect the voltage, current, and corresponding junction temperature data of a certain-phase upper-bridge IGBT through an oscilloscope and a temperature acquisition device, and intercept a part of the data. It is required that the intercepted data contains and only contains a complete positive half-cycle of the current, and the total length of the intercepted current data is less than a complete current fundamental period T. Let the sampling data time interval of the oscilloscope be Δt, and the intercepted current, voltage, and corresponding junction temperature data of the upper-bridge IGBT be i k , v k and T jk , k = 1, 2,..., n;

[0050] It should be noted that: 1) If it is module parallel connection or single-device parallel connection, the collected data should be the data of one of the modules or single devices.

[0051] 2) It is required that the sampling rate of the oscilloscope be set as high as possible, that is, Δt is as small as possible, to ensure the accuracy of subsequent loss calculation.

[0052] 3) If the sampling rate of the temperature acquisition device is different from that of the oscilloscope, the sampling rate of the temperature acquisition device can be adjusted to be the same as that of the oscilloscope by means of linear interpolation.

[0053] Step S1.2: Accurately extract the positive half-cycle data of the current: Let the bus voltage be V bus , the zero offsets of the current i k and the voltage v k be I Dev , V Dev , then there is:

[0054]

[0055] After zero-offset calibration, the new current i k_Dev and voltage v k_Dev are:

[0056]

[0057] Let i c_Sum be the cumulative integral of i k_Dev , then:

[0058]

[0059] Among them, i c_Sum The minimum value of is i c_Sum_min , and the corresponding c = a; i c_Sum The maximum value of is i c_Sum_max , and the corresponding c = b, where 1 < a < v < n; if there are multiple minimum or maximum points, then a takes the first point and b takes the last point (for example, in the sequence c = 1, 2,..., a1, a2, a3, a4,..., b1, b2, b3, b4,..., n, i a2_Sum = i a3_Sum = i c_Sum_min , i b2_Sum = i b3_Sum = i c_Sum_max , then a = a2 and b = b3);

[0060] The upper-bridge IGBT only works during the positive half-cycle of the output current. Then, the current, voltage, and junction temperature of the upper-bridge IGBT corresponding to the positive half-cycle of the extracted current are i m_Dev , v m_Dev and T jm , where m = a, a + 1,..., b - 1, b;

[0061] Step S1.3: Determination of the loss calculation interval: A normally operating IGBT has three states: conduction state, switching state, and cut-off state; when the IGBT is in the conduction state, conduction loss is generated; when the IGBT is in the switching state, switching loss is generated; when the IGBT is in the cut-off state (due to its very small leakage current), the loss in the cut-off state (can) be ignored, where:

[0062] Let the maximum value of i m_Dev be i m_Dev_max , I c_Low be the threshold current for determining the cut-off state of the IGBT. When i m_Dev < I c_low , the IGBT is in the cut-off state (usually, I c_Low = 0.02i m_Dev_max ); Let V ce_Low be the threshold voltage for determining the non-conduction state of the IGBT. When v m_Dev ≥ V ce_Low , the IGBT is in the non-conduction state (usually, V ce_Low = 0.06V bus ), then the IGBT in the conduction state satisfies:

[0063]

[0064] Under the IGBT switching state, the following conditions are satisfied:

[0065]

[0066] Find the current i m_Dev and voltage v m_Dev All the points that satisfy the formula under the IGBT conduction state in are reordered. Let the corresponding current and junction temperature be i cond_Cal and T jcond_Cal , cond_Cal = 1, 2…, n cond , where n cond <(b - a), then i cond_Cal and T jcond_Cal are the intervals used to calculate the conduction loss;

[0067] Similarly, find the current i m_Dev and voltage v m_Dev All the points that satisfy the formula under the IGBT switching state in are reordered. Let the corresponding current and voltage be i sw_Cal , v sw_Cal , sw_Cal = 1, 2…, n sw , where n sw <(b - a), then i sw_Cal and v sw_Cal are the intervals used to calculate the switching loss;

[0068] Step S1.4: Loss calculation: Assume that the Vce / Ic curve of the upper-bridge IGBT at different Tj (junction temperature of the chip) has been calibrated. Then, through the method of table lookup interpolation or formula fitting, obtain the on-voltage drop of the IGBT at the current i cond_Cal and junction temperature T jcond_Cal as follows:

[0069]

[0070] The conduction loss of the IGBT is:

[0071]

[0072] The switching loss of the IGBT is:<(b - a), then i

[0073]

[0074] The total loss of the IGBT is:

[0075] IGBT = P cond + P sw ;

[0076] Step S2: Calculate the loss of the lower-bridge IGBT;

[0077] Step S3: Calculate the loss of the upper-bridge Diode;

[0078] Step S4: Calculate the loss of the lower-bridge Diode (Steps S1 - S4 do not have a strict sequence).

[0079] Specifically, in Step S2, the lower-bridge voltage and current corresponding to the negative half-cycle of the intercepted output current and the lower-bridge IGBT junction temperature data are collected through an oscilloscope and a temperature acquisition device (the calculation principle and method are the same as those of the sub-steps of Step S1).

[0080] More specifically, in Step S3, the upper-bridge voltage and current corresponding to the negative half-cycle of the intercepted output current and the upper-bridge Diode junction temperature data are collected through an oscilloscope and a temperature acquisition device (the calculation principle and method are the same as those of the sub-steps of Step S1).

[0081] Furthermore, in Step S4, the lower-bridge voltage and current corresponding to the positive half-cycle of the intercepted output current and the lower-bridge Diode junction temperature data are collected through an oscilloscope and a temperature acquisition device (in the loss calculation of the upper and lower-bridge Diodes, the forward conduction loss calculation of the Diode can refer to the conduction loss calculation method of the upper-bridge IGBT, and the reverse recovery loss of the Diode can refer to the switching loss calculation method of the upper-bridge IGBT).

[0082] The present invention also discloses an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for verifying the IGBT module loss based on the whole-machine test waveform are performed.

[0083] The present invention also discloses a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for verifying the IGBT module loss based on the whole-machine test waveform are implemented.

[0084] Attached Figure 1 is a schematic diagram of the method for verifying the IGBT module loss based on the whole-machine test waveform. Assume that when the output current is positive, the current direction flowing through the upper-bridge IGBT is the same as the output current direction. Then, the relationship between the output current direction and the upper and lower-bridge IGBTs and Diodes is shown in Table 1.

[0085] Table 1 Relationship between output current direction and upper and lower-bridge IGBTs and Diodes

[0086] Output current direction <![CDATA[Output current positive half-cycle i o >0]]> <![CDATA[Output current negative half-cycle i o <0]]> Upper bridge Upper-bridge IGBT conducts Upper-bridge Diode freewheels Lower bridge Lower-bridge Diode freewheels Lower-bridge IGBT conducts

[0087] As can be seen from Table 1, the upper-bridge IGBT operates during the positive half-cycle of the output current, and the upper-bridge Diode operates during the negative half-cycle of the output current. Here, only the upper-bridge IGBT is taken as an example to illustrate its loss calculation method. The loss calculation methods of the upper-bridge Diode, as well as the IGBT and Diode of the lower bridge, can refer to the loss calculation method of the upper-bridge IGBT in the same way.

[0088] It is worth mentioning that the technical features such as the IGBT module involved in this invention patent application should be regarded as the prior art. The specific structures, working principles, and possible control methods and spatial arrangement methods of these technical features can be selected conventionally in the art, and should not be regarded as the invention points of this invention patent. This invention patent will not be further elaborated specifically.

[0089] For those skilled in the art, it is still possible to modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for verifying the loss of an IGBT module based on the overall machine test waveform, characterized in that, Including the following steps: Step S1: Calculate the losses of the upper-bridge IGBT. The specific implementation is as follows: Step S1.1: When the whole machine is running, collect the voltage, current and corresponding junction temperature data of the IGBT of a certain phase upper bridge through an oscilloscope and a temperature acquisition device, and intercept a part of the data. It is required that the intercepted data contains and only contains a complete positive half-cycle of the current, and the total length of the intercepted current data is less than a complete current fundamental wave period T. Let the sampling data time interval of the oscilloscope be Δt. The current, voltage and corresponding junction temperature data of the intercepted upper bridge IGBT are respectively i k , v k and T jk , k = 1, 2, …, n; Step S1.2: Accurate extraction of positive half-cycle data of current: Assume the bus voltage is V bus , the current is i k and the zero biases of the voltage v k are I Dev , V Dev respectively, then we have: After zero-bias calibration, a new current i is obtained k_Dev and voltage v k_Dev as follows: Let i c_Sum be the cumulative score of i k_Dev , then: where i c_Sum has a minimum value of i c_Sum_min , and the corresponding c = a; i c_Sum has a maximum value of i c_Sum_max , and the corresponding c = b, where 1 < a < b < n; if there are multiple minimum or maximum points, then a takes the first point and b takes the last point; The upper-bridge IGBT only operates during the positive half-cycle of the output current. Thus, the current, voltage, and junction temperature of the upper-bridge IGBT corresponding to the positive half-cycle of the current are respectively i m_Dev , v m_Dev and T jm , where m = a, a + 1, …, b - 1, b; Step S1.3: Determine the loss calculation interval: There are three states for a normally operating IGBT: conduction state, switching state, and cut-off state; when the IGBT is in the conduction state, conduction losses will occur; when the IGBT is in the switching state, switching losses will occur; when the IGBT is in the cut-off state, the losses in the cut-off state are ignored, where: Let i m_Dev The maximum value of which is i m_Dev_max , I c_Low is the threshold current for determining the cut-off state of the IGBT. When i m_Dev < I c_Low , the IGBT is in the cut-off state; Let V ce_Low be the threshold voltage for determining the non-conduction state of the IGBT. When v m_Dev ≥ V ce_Low , the IGBT is in the non-conduction state. Then, under the conduction state of the IGBT, it satisfies: Under the switching state of the IGBT: Find the current i m_Dev and the voltage v m_Dev All the points that satisfy the formula under the IGBT conduction state in, reorder these points, and let the corresponding current and junction temperature be i cond_Cal and T jcond_Cal , cond_Cal = 1, 2…, n cond , where, n cond <(b - a), then i cond_Cal and T jcond_Cal are the intervals used to calculate the conduction loss; Similarly, find the current i m_Dev and the voltage v m_Dev for all points that satisfy the formula under the IGBT switching state in i and v, reorder these points, and let the corresponding current and voltage be i sw_Cal , v sw_Cal , sw_Cal = 1, 2…, n sw , where n sw <(b - a), then i sw_Cal and v sw_Cal are the intervals used to calculate the switching loss; Step S1.4: Loss calculation: Assume that the Vce / Ic curves of the upper-bridge IGBT at different Tj have been calibrated. Then, through the method of look-up table interpolation or formula fitting, the conduction voltage drop of the IGBT at current i cond_Cal and junction temperature T jcond_Cal is obtained as follows: The conduction loss of the IGBT is: The switching loss of the IGBT is: The total loss of the IGBT is: P IGBT = P cond + P sw ; Step S2: Calculate the losses of the lower-bridge IGBT; Step S3: Calculate the losses of the upper-bridge Diode; Step S4: Calculate the losses of the lower-bridge Diode.

2. The method for verifying the loss of the IGBT module based on the whole machine test waveform according to claim 1, characterized in that In Step S2, the lower-bridge voltage and current and the lower-bridge IGBT junction temperature data corresponding to the negative half-cycle of the output current are collected by an oscilloscope and a temperature acquisition device.

3. A method for verifying the loss of an IGBT module based on the overall machine test waveform according to claim 2, characterized in that In Step S3, the upper-bridge voltage and current and the upper-bridge Diode junction temperature data corresponding to the negative half-cycle of the output current are collected by an oscilloscope and a temperature acquisition device.

4. A method for verifying the loss of an IGBT module based on the whole machine test waveform according to claim 3, characterized in that In Step S4, the lower-bridge voltage and current and the lower-bridge Diode junction temperature data corresponding to the positive half-cycle of the output current are collected by an oscilloscope and a temperature acquisition device.

5. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for verifying the IGBT module losses based on the whole-machine test waveform as described in any one of claims 1 to 4.

6. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for verifying the IGBT module losses based on the whole-machine test waveform as described in any one of claims 1 to 4.

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