A fault detection system for inverter circuit of series multi-level inverter

Abstract

The present invention provides a series multi-level inverter inverter circuit fault detection system based on output signal acquisition, the fault detection system includes a voltage signal acquisition unit, a current signal acquisition unit, a voltage division unit, a voltage reduction unit, a current / voltage conversion unit, a signal conditioning unit, an A / D conversion unit, a signal analysis and processing unit, a storage unit, a display unit, an alarm unit, a communication unit and a key input unit; the voltage signal acquisition unit and the current signal acquisition unit respectively acquire the output signal of the inverter, and after voltage division and voltage reduction processing and current / voltage conversion, they are input into the signal conditioning unit, and then after processing, they are input into the A / D conversion unit for conversion, and then analyzed and calculated by the signal analysis and processing unit, so as to judge the working state of the inverter circuit of the inverter. The present invention provides a series multi-level inverter inverter circuit fault detection system based on output signal acquisition, which effectively detects the working condition of the inverter, and thus improves the working reliability.

Description

Technical Field

[0001] The invention belongs to the technical field of power detection, and in particular relates to a series multi-level inverter inverter circuit fault detection system based on output signal acquisition. Background Art

[0002] With the continuous development of science and technology, variable frequency speed regulation technology has also been widely used. Speed ​​regulation technology based on frequency converters has been applied to various industries and has become one of the most important means to save energy and reduce consumption, improve production efficiency and production quality. With the increasing application of frequency conversion technology, the economic losses caused by the failure of the frequency converter have also attracted the attention of relevant personnel. For the frequency converter, the main circuit is the inverter circuit, so the fault detection system group must detect whether the inverter circuit fails. It is difficult to realize intelligent fault detection by using Fourier transform to analyze the fault information of the frequency converter and then using the characteristics of the amplitude spectrum and phase spectrum to detect the fault information; how to effectively collect information on the frequency converter, and make accurate analysis and judgment, and then obtain fault information, and take necessary protection measures in time, which can not only improve the working efficiency of the frequency converter, but also extend its service life. Summary of the invention

[0003] The present invention provides a series multi-level inverter inverter circuit fault detection system based on output signal acquisition, which analyzes and judges the current and voltage signals output by the inverter to judge the working condition of the inverter circuit, thereby improving the working reliability of the inverter.

[0004] The present invention is specifically a series multi-level inverter inverter circuit fault detection system, the fault detection system includes a voltage signal acquisition unit, a current signal acquisition unit, a voltage dividing unit, a voltage step-down unit, a current / voltage conversion unit, a signal conditioning unit, an A / D conversion unit, a signal analysis and processing unit, a storage unit, a display unit, an alarm unit, a communication unit and a key input unit, the voltage signal acquisition unit, the voltage dividing unit, the voltage step-down unit, the signal conditioning unit, the A / D conversion unit and the signal analysis and processing unit are connected in sequence, the current signal acquisition unit, the current / voltage conversion unit and the signal conditioning unit are connected in sequence, the signal analysis and processing unit is also respectively connected to the storage unit, the display unit, the alarm unit The unit, the communication unit, and the key input unit are connected; the voltage signal acquisition unit acquires the output voltage signal of the inverter, and outputs a low-voltage signal to the signal conditioning unit through the voltage divider unit and the step-down unit; the current signal acquisition unit uses a current transformer to acquire the output current of the inverter, and outputs a low-voltage voltage signal to the signal conditioning unit through the current / voltage conversion unit; the signal conditioning unit filters and amplifies the input signal and then outputs it to the A / D conversion unit, and after A / D conversion, it is input to the signal analysis and processing unit for analysis and calculation, thereby judging whether the inverter circuit of the inverter works normally, and storing and displaying it through the storage unit and the display unit, and giving a fault alarm through the alarm unit.

[0005] The signal conditioning unit includes a filtering module and an amplifying module, which respectively filter and amplify the input voltage signal and output a signal suitable for the A / D conversion unit; the amplifying module includes a first operational amplifier and a second operational amplifier, the amplification factor of the first operational amplifier is 1, and the output signal has a polarity opposite to that of the input signal, and the second operational amplifier outputs signals of different proportions by adjusting the feedback resistor, and the output signal has a polarity opposite to that of the input signal, and the amplified signal with unchanged polarity is output after being amplified by the first operational amplifier and the second operational amplifier.

[0006] The key input unit combines with the storage unit and the display unit to set protection settings and alarm values ​​for the output voltage and current values ​​of the inverter. The signal analysis and processing unit combines with the protection settings and the alarm values ​​to analyze and judge the input signal, and further judge whether the inverter circuit of the inverter is operating normally.

[0007] The signal analysis processing unit performs the following steps to analyze the output voltage and current of the inverter:

[0008] Step 1: Use db3 wavelet function to perform three-layer wavelet decomposition: [C, L] = wavedec (S1, 3, 'db3'), the output decomposition structure includes the wavelet decomposition vector C and the corresponding record vector L, S1 is the return signal;

[0009] Step 2: Use the wrcoef function to reorganize the low-frequency information and high-frequency information of the signal after wavelet decomposition: wrcoef('type',C,L,'wname',N), where type indicates the mean part or the detail part, C is the array of coefficients of each component after wavelet decomposition, L is the length of each element in C, and N is the number of layers to start information reorganization;

[0010] Step three, using the appcoef function to extract coefficients from the low-frequency information, using the detcoef function to extract coefficients from the high-frequency information, and comparing the extracted coefficients with the comparison values ​​to determine whether the inverter circuit of the frequency converter fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The present invention is a structural schematic diagram of a series multi-level inverter circuit fault detection system. DETAILED DESCRIPTION

[0012] The specific implementation of a series multi-level inverter inverter circuit fault detection system of the present invention is described in detail below with reference to the accompanying drawings.

[0013] like Figure 1As shown, the fault detection system of the present invention includes a voltage signal acquisition unit, a current signal acquisition unit, a voltage dividing unit, a voltage reducing unit, a current / voltage conversion unit, a signal conditioning unit, an A / D conversion unit, a signal analysis and processing unit, a storage unit, a display unit, an alarm unit, a communication unit and a key input unit, wherein the voltage signal acquisition unit, the voltage dividing unit, the voltage reducing unit, the signal conditioning unit, the A / D conversion unit and the signal analysis and processing unit are connected in sequence, the current signal acquisition unit, the current / voltage conversion unit and the signal conditioning unit are connected in sequence, and the signal analysis and processing unit is also respectively connected to the storage unit, the display unit, the alarm unit, the communication unit, the The key input unit is connected; the voltage signal acquisition unit acquires the output voltage signal of the inverter, and outputs a low-voltage signal to the signal conditioning unit through the voltage divider unit and the voltage step-down unit; the current signal acquisition unit uses a current transformer to acquire the output current of the inverter, and outputs a low-voltage voltage signal to the signal conditioning unit through the current / voltage conversion unit; the signal conditioning unit filters and amplifies the input signal and then outputs it to the A / D conversion unit, and after A / D conversion, it is input to the signal analysis and processing unit for analysis and calculation, thereby judging whether the inverter circuit of the inverter is working normally, and storing and displaying it through the storage unit and the display unit, and giving a fault alarm through the alarm unit.

[0014] The signal conditioning unit includes a filtering module and an amplifying module, which respectively filter and amplify the input voltage signal and output a signal suitable for the A / D conversion unit; the amplifying module includes a first operational amplifier and a second operational amplifier, the amplification factor of the first operational amplifier is 1, and the output signal has a polarity opposite to that of the input signal, and the second operational amplifier outputs signals of different proportions by adjusting the feedback resistor, and the output signal has a polarity opposite to that of the input signal, and the amplified signal with unchanged polarity is output after being amplified by the first operational amplifier and the second operational amplifier.

[0015] The key input unit combines with the storage unit and the display unit to set protection settings and alarm values ​​for the output voltage and current values ​​of the inverter. The signal analysis and processing unit combines with the protection settings and the alarm values ​​to analyze and judge the input signal, and further judge whether the inverter circuit of the inverter is operating normally.

[0016] The signal analysis processing unit performs the following steps to analyze the output voltage and current of the inverter:

[0017] Step 1: Use db3 wavelet function to perform three-layer wavelet decomposition: [C, L] = wavedec (S1, 3, 'db3'), the output decomposition structure includes the wavelet decomposition vector C and the corresponding record vector L, S1 is the return signal;

[0018] Step 2: Use the wrcoef function to reorganize the low-frequency information and high-frequency information of the signal after wavelet decomposition: wrcoef('type',C,L,'wname',N), where type indicates the mean part or the detail part, C is the array of coefficients of each component after wavelet decomposition, L is the length of each element in C, and N is the number of layers to start information reorganization;

[0019] Step three, using the appcoef function to extract coefficients from the low-frequency information, using the detcoef function to extract coefficients from the high-frequency information, and comparing the extracted coefficients with the comparison values ​​to determine whether the inverter circuit of the frequency converter fails.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit the present invention. A person skilled in the art should understand that the specific implementation of the present invention can be modified or replaced by equivalents, but these modifications or changes are within the scope of protection of the pending claims.

Claims

1. A series multi-level inverter inverter circuit fault detection system, characterized in that: The fault detection system comprises a voltage signal acquisition unit, a current signal acquisition unit, a voltage dividing unit, a voltage reducing unit, a current / voltage conversion unit, a signal conditioning unit, an A / D conversion unit, a signal analysis and processing unit, a storage unit, a display unit, an alarm unit, a communication unit and a key input unit. The voltage signal acquisition unit, the voltage dividing unit, the voltage reducing unit, the signal conditioning unit, the A / D conversion unit and the signal analysis and processing unit are connected in sequence. The current signal acquisition unit, the current / voltage conversion unit and the signal conditioning unit are connected in sequence. The signal analysis and processing unit is also respectively connected to the storage unit, the display unit, the alarm unit, the communication unit, the key input unit. The input unit is connected; the voltage signal acquisition unit acquires the output voltage signal of the inverter, and outputs a low-voltage signal to the signal conditioning unit through the voltage divider unit and the voltage step-down unit; the current signal acquisition unit uses a current transformer to acquire the output current of the inverter, and outputs a low-voltage voltage signal to the signal conditioning unit through the current / voltage conversion unit; the signal conditioning unit filters and amplifies the input signal and then outputs it to the A / D conversion unit, and after A / D conversion, it is input to the signal analysis and processing unit for analysis and calculation, thereby judging whether the inverter circuit of the inverter is working normally, and storing and displaying it through the storage unit and the display unit, and giving a fault alarm through the alarm unit; The signal analysis processing unit performs the following steps to analyze the output voltage and current of the inverter: Step 1: Use db3 wavelet function to perform three-layer wavelet decomposition: [C, L] = wavedec (S1, 3, 'db3'), the output decomposition structure includes the wavelet decomposition vector C and the corresponding record vector L, S1 is the return signal; Step 2: Use the wrcoef function to reorganize the low-frequency information and high-frequency information of the signal after wavelet decomposition: wrcoef('type',C,L,'wname',N), where type indicates the mean part or the detail part, C is the array of coefficients of each component after wavelet decomposition, L is the length of each element in C, and N is the number of layers to start information reorganization; Step three, using the appcoef function to extract coefficients from the low-frequency information, using the detcoef function to extract coefficients from the high-frequency information, and comparing the extracted coefficients with the comparison values ​​to determine whether the inverter circuit of the frequency converter fails.

2. A series multi-level inverter inverter circuit fault detection system according to claim 1, characterized in that: The signal conditioning unit includes a filtering module and an amplifying module, which respectively filter and amplify the input voltage signal and output a signal suitable for the A / D conversion unit; the amplifying module includes a first operational amplifier and a second operational amplifier, the amplification factor of the first operational amplifier is 1, and the output signal has a polarity opposite to that of the input signal, and the second operational amplifier outputs signals of different proportions by adjusting the feedback resistor, and the output signal has a polarity opposite to that of the input signal, and the amplified signal with unchanged polarity is output after being amplified by the first operational amplifier and the second operational amplifier.

3. A series multi-level inverter inverter circuit fault detection system according to claim 2, characterized in that: The key input unit combines with the storage unit and the display unit to set protection settings and alarm values ​​for the output voltage and current values ​​of the inverter. The signal analysis and processing unit combines with the protection settings and the alarm values ​​to analyze and judge the input signal, and further judge whether the inverter circuit of the inverter is operating normally.

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