KR100550360B1 - Diagnosis device of power conversion device - Google Patents

Abstract

The apparatus for diagnosing a condition of a power converter according to the present invention includes: a first sensing circuit unit installed between an input terminal and an output terminal of a single-phase or three-phase power converter, and for detecting a change in capacitance and pulsation voltage of a DC terminal capacitor; A second sensing circuit unit installed between an input terminal and an output terminal of the single-phase or three-phase power conversion device, and configured to detect a state of a semiconductor device for power; It is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, a third detection circuit unit for detecting an abnormal operation of the general power conversion device or asymmetry of the three-phase output voltage; A sensing resistance signal sensing unit for sensing a signal from the sensing resistance of the first, second and third sensing circuit units; A filtering and amplifying unit for filtering and amplifying the sensed resistance signal sensed by the sensed resistance signal detector; An A/D conversion and digital operation unit that converts the analog signal through the filtering and amplification unit into a digital signal and performs digital operation; And a signal processing and status diagnosis unit for receiving the output signal of the A/D conversion and digital operation unit and finally performing signal processing while diagnosing the state of the power conversion device.

According to the present invention, the malfunction or damage of the power conversion device is monitored, and an abnormal condition due to aging or deterioration of the device can be monitored and diagnosed in advance.

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Description

Apparatus for diagnosing status of electric power converter

1 is a view schematically showing the configuration of a state diagnosis device of a power conversion device according to the present invention.

Figure 2 is a view showing a measurement result of the capacitance ratio according to the current ratio in a typical power conversion device.

<Explanation of reference numerals for main parts of drawings>

110...first sensing circuit 120...second sensing circuit

130...third sensing circuit 140...sensing resistance (Rs) signal detector

150...Filtering and amplification section 160...A/D conversion and digital calculation section

170...Signal processing and status diagnosis

The present invention relates to a condition diagnosis device of a power conversion device, in particular, by monitoring the signal change of the input and output terminals of the power conversion device and the change in capacitance and pulsation voltage of the filter capacitor to monitor malfunction or damage of the power conversion device. Of course, the present invention relates to an apparatus for diagnosing a condition of a power conversion device capable of monitoring and diagnosing an abnormal condition due to deterioration or deterioration of an apparatus.

Today, with the development of power electronic technology, power devices such as various rectifiers, inverters, and DC converters are widely used in various fields such as industry, home, transportation, medical care, and environment, and the most basic and core power supply in each field It plays a role as an integral component.

In particular, uninterruptible power supplies, medical equipment, and inverter power supplies for transportation are very likely to cause economic and social losses in an accident, and reliable operation is always required. Accordingly, recently, a diagnostic study of a power conversion device has been partially started and is introduced in the literature. That is, an example in which a method for estimating the abnormality of a converter and a device is introduced through signal processing of an input current or spectrum analysis of an operating frequency is described. However, the methods introduced in the literature focus on judging the situation after an abnormality in the device, and there is no research on how to detect abnormal signs due to aging or deterioration of the power converter. .

It is also very important to prepare for an accident situation of a power converter, but it is a future technology to protect the entire system by capturing abnormal signs in advance and replacing the power supply.

The current power conversion device maintenance method reduces the possibility of an accident by setting an arbitrary life span and replacing it regularly. This is because it is very difficult to determine the overall condition with a specific signal because the converter is a complex system composed of numerous parts. Therefore, the method of replacing at regular intervals is generally used, and this is a significant economic loss in the national view as compared to checking and replacing the correct operation state.

In the conventional power conversion device diagnostic technology, a signal is analyzed by extracting some of various variables for an abnormality of a semiconductor switch for power, an abnormality of a controller or filter capacitor, and an equipment of an output terminal, and displaying an abnormality result.

However, it can be said that such a conventional method is limited to a function of reporting an accident situation rather than a meaning of state monitoring.

The present invention was created in view of the above, and it analyzes the signal of the input and output terminals of the power converter and monitors the change in capacitance and pulsation voltage of the filter capacitor to monitor malfunction or damage of the power converter. , The object of the present invention is to provide a power conversion device state diagnosis device capable of monitoring and diagnosing an abnormal state due to aging or deterioration of a device.

In order to achieve the above object, the state diagnosis device of the power conversion device according to the present invention,

It is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, a first detection circuit unit for detecting the capacitance and pulsation voltage changes of the DC terminal capacitor;

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A second sensing circuit unit installed between an input terminal and an output terminal of the single-phase or three-phase power conversion device, and configured to detect a state of a semiconductor device for power;

It is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, a third detection circuit unit for detecting an abnormal operation of the general power conversion device or asymmetry of the three-phase output voltage;

A sensing resistance signal sensing unit for sensing a signal from the sensing resistance of the first, second and third sensing circuit units;

A filtering and amplifying unit for filtering and amplifying the sensed resistance signal sensed by the sensed resistance signal detector;

An A/D conversion and digital operation unit that converts the analog signal through the filtering and amplification unit into a digital signal and performs digital operation; And

The A/D conversion and the digital operation unit receives an output signal, and finally performs signal processing, and includes a signal processing and a status diagnosis unit for diagnosing the state of the power conversion device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the configuration of a state diagnosis device of a power conversion device according to the present invention.

Referring to FIG. 1, the state diagnosis device of the power conversion device according to the present invention includes a first sensing circuit unit 110, a second sensing circuit unit 120, a third sensing circuit unit 130, and a sensing resistance signal sensing unit 140. , Filtering and amplifying unit 150, A/D conversion and digital operation unit 160, signal processing and state diagnosis unit 170.

The first sensing circuit unit 110 is installed between an input terminal and an output terminal of a single-phase or three-phase power converter, and detects a change in capacitance and pulsation voltage of a DC terminal capacitor. The first sensing circuit unit 110 is composed of a series connection circuit of the sensing resistor (Rs) and the capacitor (C). Through the first sensing circuit unit 110, the capacitance ratio can be estimated by a measurement value through an output current distribution or an external shunt resistor between a capacitor to be measured and a capacitor for measurement. In addition, the pulsation voltage is measured by measuring the entire DC voltage including the measurement resistance.

That is, the change in the capacitor mounted on the power converter must be measured separately to know the change in value. It cannot be used to monitor the status of a working device. In the present invention, a filter capacitance of a power conversion device is measured by measuring a current flowing by connecting a capacitor in parallel to a DC terminal of a power conversion device having an external terminal. The capacitors connected in parallel and the filter capacitors in the power converter have a current ratio by exactly the capacitor ratio, and it is possible to estimate the change in the filter capacitor through the output current and the current ratio of the parallel connected capacitors.

2 is a view showing a result of measuring the capacitance ratio according to the current ratio.

Referring to Figure 2, by connecting a measuring capacitor of 940uF in parallel to a capacitor of 4700uF to test the current linearity between the two, it was found that it is possible to estimate the change of the entire capacitor by the auxiliary capacitor.

In the second method, to measure the change in the capacitor, the change in the capacitance can be measured by measuring the change in the pulsation voltage of the capacitor and calculating the pulsation voltage proportional to the output current. That is, since the change amount of the capacitor can be expressed as the following equation, it is possible to estimate the change in the capacitor.

Here, Ts is the measurement period, Vdc-max is the peak value of one cycle of the DC pulsation voltage, and Vdc-min is the minimum value of one cycle of the DC pulsation voltage. Although it is difficult to accurately calculate the actual capacitance through the method of the present invention, it is possible to estimate the capacitor change.

The second sensing circuit unit 120 is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, and detects the state of the semiconductor devices S1 to S6 for power. The second sensing circuit unit 120 includes a first sensing resistor Rs1 connected to a positive terminal of the input terminal of the power converter, a second sensing resistor Rs2 connected to a negative terminal of the input terminal, and a first, It is composed of a series and parallel combination circuit of the third sensing resistors Rs3 connected in parallel on the series connecting lines of the second sensing resistors Rs1 and Rs2. To determine the switch leakage current condition, measure the signal value of the auxiliary circuit at no load so that there is no influence by the load.

The first and second sensing resistors Rs1 and Rs2 connected to the input terminal are connected to the positive terminal and the negative terminal of the input terminal, and are much larger than the switch impedance when measuring the switch impedance. The third sense resistor Rs3 is determined by the voltage ratio of the divided voltage measurement.

For turn-on voltage measurements, it must be tested at a constant load in the same circuit structure.

The third sensing circuit unit 130 is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, and detects an abnormal operation of the general power conversion device or asymmetry of the three-phase output voltage. The third sensing circuit unit 130 connects three divided resistors R1, R2, and R3 respectively connected to the three-phase output terminals of the power converter, and three connecting the divided resistors R1, R2, R3 to each other. It consists of three sense resistors (Rs4, Rs5, Rs6).

Depending on the operation of the power converter, the output voltage is applied to the three-phase output terminals, and these waveforms are applied to each of the divided resistors (R1, R2, R3), each of the divided resistors (R1, R2, R3) and the sense resistor (Rs4, Rs5, Rs6) have a voltage depending on the resistance ratio. Depending on how the measurement signal is processed, it is also possible to connect the neutral point to the neutral point of the DC link capacitor through a measuring resistor, depending on how the measurement signal is processed.

If the output voltage has a three-phase symmetrical waveform with a constant phase difference, the voltages of the divided resistors R1, R2, and R3 appear as sinusoidal waves, so the sum voltage or total rectification voltage between each phase signal voltage has a constant shape. On the other hand, when the output voltage is unsymmetrical, a distorted waveform with an offset voltage added to the senspa type appears. Therefore, a malfunction between the controller of the power converter and the driving circuit can be determined through comparison of signal voltages based on the sum voltage or zero point of the measured signal voltages or the pulsation voltage of the rectified voltage. In addition, an abnormality may also be determined through harmonics generated by processing a distorted signal voltage by Fast Fourier Transform (FFT).

The sensing resistance signal sensing unit 140 detects signals from the sensing resistors Rs to Rs6 of the first, second, and third sensing circuit units 110, 120, and 130.

The filtering and amplifying unit 150 filters and amplifies the sensing resistance signal sensed by the sensing resistance signal sensing unit 140.

The A/D conversion and digital calculation unit 160 converts the analog signal that has been passed through the filtering and amplification unit 150 into a digital signal and performs digital calculation.

The signal processing and state diagnosis unit 170 receives the output signal of the A/D conversion and digital operation unit 160 to finally perform signal processing and diagnose the state of the power conversion device.

As described above, in the present invention, a voltage divider circuit capable of detecting a signal between the input DC power terminal and the output terminal is configured to detect the turn-on voltage and leakage current of the semiconductor device and the operating state of the power converter.

In addition, by connecting a parallel capacitor to the input DC power supply terminal and measuring the current flowing through it, the change in the filter capacitor of the power supply can be calculated using the correlation with the load current.

As the aging and deterioration of the electrolytic capacitor, three factors appear, which are capacitance, ESR (equivalent series resistance), and leakage current variation. The capacitance of the electrolytic capacitor gradually decreases due to aging and deterioration, so that the capacitance decreases and the ESR value increases. Among them, the capacitance can be seen as more than about 10% to 25%, and in the present invention, the capacitance change and the pulsation voltage change are used as diagnostic criteria.

As described above, the apparatus for diagnosing the condition of the power converter according to the present invention is a signal measured through a signal measuring circuit at the input and output terminals in place of the method for determining malfunction by input and output voltage and current signal analysis proposed in the conventional methods. By diagnosing abnormal signs by processing, it is possible to simplify signal analysis and obtain high reliability. In addition, measurement and monitoring of the state of the power conversion device, which were not possible in the conventional methods, can be achieved through capacitor monitoring and characteristic monitoring of switch elements. Therefore, there is an advantage of monitoring and diagnosing an abnormal condition due to aging or deterioration of the device, as well as monitoring malfunction or damage of the power converter.

Claims (5)

delete It is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, a first detection circuit unit for detecting the capacitance and pulsation voltage changes of the DC terminal capacitor; A second sensing circuit unit installed between an input terminal and an output terminal of the single-phase or three-phase power conversion device, and configured to detect a state of a semiconductor device for power; It is installed between the input terminal and the output terminal of the single-phase or three-phase power conversion device, a third detection circuit unit for detecting an abnormal operation of the general power conversion device or asymmetry of the three-phase output voltage; A sensing resistance signal sensing unit for sensing a signal from the sensing resistance of the first, second and third sensing circuit units; A filtering and amplifying unit for filtering and amplifying the sensed resistance signal sensed by the sensed resistance signal detector; An A/D conversion and digital operation unit that converts the analog signal through the filtering and amplification unit into a digital signal and performs digital operation; And The A/D conversion and the digital operation unit receives the output signal and finally performs signal processing, and also includes a signal processing and a status diagnosis unit for diagnosing the state of the power conversion device. . According to claim 2, The first sensing circuit unit is a state diagnosis device of a power conversion device, characterized in that consisting of a series connection circuit of the sensing resistor (Rs) and the capacitor (C). According to claim 2, The second sensing circuit unit includes a first sensing resistor Rs1 connected to the positive terminal of the input terminal of the power converter, a second sensing resistor Rs2 connected to the negative terminal of the input terminal, and first and second sensing terminals. A state diagnosis apparatus of a power conversion device, characterized in that it consists of a combination circuit of a series of three sense resistors (Rs3) connected in parallel on a series connection line of resistors (Rs1, Rs2). According to claim 2, The third sensing circuit unit is connected to three divided resistors R1, R2, and R3 respectively connected to the three-phase output terminals of the power converter, and connected to these divided resistors R1, R2, R3 to be connected by Δ or Y connection. It is composed of three detection resistors (Rs4, Rs5, Rs6) status diagnosis device of the power converter.

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