Fault Diagnosis Method for Driver Power Transistor Based on Processing of Interphase Voltage Signals of Motor

Abstract

A method for diagnosing faults in the power transistors of a driver based on the processing of the inter-phase voltage signals of a motor. First, the inter-phase voltage signals are collected in real time through voltage sensors, and then the mean value of the inter-phase voltage signals is processed, that is, the average value of the inter-phase voltage signals is calculated within an operating window of a specified fundamental frequency. Secondly, the obtained average value signal is processed by taking the maximum value and rounding. The obtained integer values correspond one-to-one with the inter-phase voltages. Finally, all the integer values are successively substituted into a multivariate function formula with determined coefficients, and thus a fault value table is obtained, and each function value in the function value table corresponds to a unique operating condition of the power transistor. Therefore, by the above processing, the real-time function value is obtained, and then the fault value table is checked to determine whether a fault occurs and the type and location of the fault. The present invention can quickly diagnose the fault location and type, and has the advantages of simple structure and fast calculation speed compared with other model-based and adaptive fault diagnosis methods.

Description

Technical Field

[0001] The present invention relates to the technical field of motor drive control, and more particularly to the field of power converter fault diagnosis. Background Art

[0002] In a motor drive system, in order to improve system reliability, the first thing to do is to implement fault diagnosis, that is, to detect faults and identify the types and locations of faults. In actual engineering, in order to diagnose faults, it is generally common to monitor the current of each phase winding and perform fault diagnosis by judging whether the current is abnormal. This method is very simple, low-cost, and does not affect the operation speed of the control algorithm. However, the false alarm rate of this method is relatively high and it is easy to cause misjudgment. In order to overcome the shortcomings of this method, many model-based, neural network-based, and adaptive fault diagnosis methods have emerged. Their advantages are relatively high fault diagnosis accuracy, but the resulting problems are slow algorithm operation speed, algorithm complexity, slow system response, etc., and they are not very suitable for real-time control systems. Summary of the Invention

[0003] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide a method for diagnosing faults of a driver power tube based on the processing of motor phase-interphase voltage signals, which not only has a simple algorithm, fast operation speed, wide application range, but also can simultaneously diagnose the fault location and type, and can reduce the false alarm rate of fault diagnosis.

[0004] The technical solution of the present invention is as follows: A method for diagnosing faults of a driver power tube based on the processing of motor phase-interphase voltage signals, the steps are as follows:

[0005] 1) A voltage sensor collects the motor phase-interphase voltage in real time and calculates the average value of the phase-interphase voltage signal within a running window of a specified fundamental frequency, where the fundamental frequency needs to be more than twice the frequency of the phase-interphase voltage signal, and the running window is a preset fixed time length, and the average value is obtained by sampling at the fundamental frequency within this time length;

[0006] 2) Take the maximum value and round the average value signal of the phase-interphase voltage under various working conditions, and finally substitute it into a designed multi-variable function criterion formula to calculate the unique function value corresponding to each working condition, and thus make a fault value table;

[0007] 3) Take the maximum value and round the average value signal in step 1), then substitute it into the originally designed multi-variable function formula to find the function value, and finally perform a look-up operation according to the fault value table in step 2). Furthermore, the fault type and the location where the fault occurs are judged to achieve fault identification.

[0008] The calculation formula for the average value of the motor phase-interphase voltage signal within a running window of a specified fundamental frequency in step 1) is:

[0009]

[0010] The specific method for determining the fault type and occurrence location according to the final function value in step 3) is as follows: perform a maximum value processing on the obtained average value signal:

[0011]

[0012] Then perform a rounding operation on the maximum value, q = 1, and this is the rounding mode based on proximity:

[0013]

[0014] Finally, substitute the obtained X 1,2 , X 2,3 , X 3,4 , X 4,5 , …, X n-1,n , X n,1 , into the following designed multivariate function formula, where m n,* = 2n + 1, and calculate the function value:

[0015] W = m 1,2 * X 1,2 + m 2,3 * X 2,3 + m 3,4 * X 3,4 + m 4,5 * X 4,5 + … + m n-1,n * X n-1,n + m n,1 * X n,1

[0016] The advantages of the present invention compared with the prior art are as follows: The fault diagnosis method for the driver power tube based on the processing of the motor phase voltage signal of the present invention can simultaneously realize the functions of fault detection, type identification, and location determination. Compared with the fault diagnosis method that only detects the current of each phase and the voltage of the lower tube, it can reduce the false alarm rate and improve the robustness of fault diagnosis. Compared with other model-based, neural network-based, and adaptive fault diagnosis methods, it has the advantages of simple structure and fast calculation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The flowchart of the fault diagnosis method of the present invention is shown in the appendix Figure 1 , and the specific steps are as follows:

[0019] 1) The voltage sensor collects the phase-to-phase voltages of the motor in real time and calculates the average value of the phase-to-phase voltage signals within a running window at a specified fundamental frequency, where the fundamental frequency should be more than twice the frequency of the phase-to-phase voltage signals. The running window is a preset fixed time length, and within this time length, samples are taken at the fundamental frequency to calculate the average value.

[0020] 2) Take the maximum value and perform rounding on the average value signals of the phase-to-phase voltages under various working conditions, and finally substitute them into a designed multi-variable function criterion formula to calculate the unique function value corresponding to each working condition, thereby creating a fault value table.

[0021] 3) Take the maximum value and perform rounding on the average value signal in step 1), then substitute it into the previously designed multi-variable function formula to find the function value. Finally, perform a look-up operation based on the fault value table in step 2). Furthermore, determine the fault type and the location where the fault occurs to achieve fault identification.

[0022] The formula for calculating the average value of the motor phase-to-phase voltage signals within a running window at a specified fundamental frequency in step 1) is:

[0023]

[0024] The specific method for determining the fault type and the location where the fault occurs based on the final function value in step 3) is: Take the maximum value of the calculated average value signal:

[0025]

[0026] Then perform rounding on the maximum value. When q = 1, this is the rounding mode of rounding to the nearest integer:

[0027]

[0028] Finally, substitute the obtained X 1,2 、X 2,3 、X 3,4 、X 4,5 、…、X n-1,n 、X n,1 into the following designed multi-variable function formula, where m n,* = 2n + 1, and find the function value:

[0029] W = m 1,2 * X 1,2 + m 2,3 * X 2,3 + m 3,4 * X 3,4 + m 4,5 * X 4,5 + … + m n-1,n * X n-1,n + m n,1 * Xn,1

[0030] Taking three - phase as an example, when the main voltage is 24V, at this time m 1,2 = 3, m 2,3 = 5, m 3,1 = 7, then the faults corresponding to each function value are shown in the following table:

[0031]

[0032] The specific implementation manners described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for diagnosing faults of the driver power transistors based on the processing of the inter-phase voltage signals of the motor It is characterized by the following steps: 1) The voltage sensor collects the phase-to-phase voltage of the motor in real time and calculates the average value of the phase-to-phase voltage signal within an operating window of a specified fundamental frequency, where the fundamental frequency is required to be more than twice the frequency of the phase-to-phase voltage signal. The operating window is a preset fixed time length, and within this time length, sampling is performed at the fundamental frequency to obtain the average value. The average value calculation formula is: 2) Take the maximum value and perform rounding processing on the average value signal of the phase-to-phase voltage under various working conditions, and finally substitute it into a designed multi-variable function criterion formula to calculate the unique function value corresponding to each working condition, thereby creating a fault value table; 3) Take the maximum value and perform rounding processing on the average value signal in step 1), then substitute it into the previously designed multi-variable function formula to obtain the function value. Finally, perform a look-up operation according to the fault value table in step 2), and then judge the fault type and the location where the fault occurs to achieve fault identification. The specific method for judging the fault type and the occurrence location based on the final function value is: Take the maximum value of the obtained average value signal: Then perform rounding processing on the maximum value, q = 1: Finally, substitute the obtained X 1,2 , X 2,3 , X 3,4 , X 4,5 , …, X n-1,n , X n,1 into the following designed multivariate function formula, where m n,* = 2n + 1, and calculate the function value: W = m 1,2 * X 1,2 + m 2,3 * X 2,3 + m 3,4 * X 3,4 + m 4,5 * X 4,5 +…+ m n-1,n * X n-1,n + m n,1 * X n,1 。

Images