KR20040060227A - Real-Time Deterioration Diagnosis Apparatus And Real-Time On-line Deterioration Diagnosis System of Power Converter - Google Patents

Abstract

PURPOSE: A real-time deterioration diagnosis device of a power conversion unit and a real-time online remote deterioration diagnosis device of a power conversion unit are provided to monitor remotely deterioration diagnosis data by using a communication network. CONSTITUTION: A real-time deterioration diagnosis device of a power conversion unit includes a calculation unit, a measurement unit, an identification unit, and a decision unit. The calculation unit calculates a transfer function by analyzing a mathematical model of a DC/DC converter. The measurement unit measures the transfer function of the DC/DC converter. The identification unit identifies states of parameters by comparing coefficients of the transfer function of the calculation unit and the measurement unit to each other. The decision unit decides the deterioration by referring to the states of the parameters.

Description

Real-Time Deterioration Diagnosis System of Power Converter and Real-Time Deterioration Diagnosis Apparatus And Real-Time On-line Deterioration Diagnosis System of Power Converter

The present invention relates to a real-time degradation diagnosis system of a power converter and a real-time on-line remote degradation diagnosis system of the power converter, and more particularly, to analyze the state of the entire system rather than diagnosing the state of individual components of the power converter. And a real-time deterioration diagnosis system of a power converter for diagnosing deterioration, and a real-time online remote deterioration diagnosis system of a power converter that enables the operator to obtain diagnostic information in real time even in a place away from the communication network. .

In general, a power change device using a semiconductor device for power has been widely used in all devices that require a power source, such as industrial devices, home appliances, and communication device power supply devices, and many technological advances have been made through the development of various control methods and devices. lost. Examples of representative power converters include subway drives, rolling mill drives, cooling pump drives, large-capacity fan drives, elevator drives, high-speed train drives, communication rectifiers, plating rectifiers, UPS, general SMPS, large capacity There are rectifiers, home appliance power supplies, server rectifiers, and motor control inverters.To date, many researches have been conducted to improve performance and functions such as high efficiency, soft switching, high power factor, high density, miniaturization, cost reduction, and reliability improvement. Technological advances have been made.

Power converters supply very basic power to industrial sites, homes, and information / communication fields.In the event of power converter accidents, the effects of loss of life, loss of operation, communication failure, and the cost of handling accidents are great. There is a need for a device to prevent accidents.

In order to prevent direct accidents in emergency situations such as overvoltage, overcurrent, temperature rise, phase loss, grounding, and abnormal control, the power converter is equipped with a protection circuit to cut off the power supply in advance during abnormal operation of the device. Although it does not occur, studies on a diagnostic system that can prevent an accident of a device due to deterioration of a semiconductor device, an inductor, a capacitor, a driving circuit and a control circuit have not been actively conducted. Degradation or aging diagnosis can prevent the power supply accident in advance by diagnosing the status of the power supply, and determine the timing of replacement and maintenance, thereby ensuring stable operation of the power supply.

As the method of diagnosing the deterioration of each component, it is easiest to diagnose the deterioration of the component by measuring the state of voltage and current for each individual component, but this requires many sensors for each component, which complicates the system. This increases the price of the system. It may be most desirable to determine the deterioration by diagnosing the state of individual components, but the power converter is composed of many components, each of which has a different lifespan according to operating conditions, It may not be a proper method because system malfunction may occur due to interference.

The most sensitive component to deterioration is a DC smoothing electrolytic capacitor, which is the most important factor in determining the lifespan of a power supply, and the frequency of accidents in order of switches such as MOSFETs, diodes, coils of inductors, and filters. Due to the increase in diagnostic components and the difficulty of diagnosis, many articles have been published to study the life span of electrolytic capacitors. As electrolytic capacitors have a characteristic that the capacitance value decreases as the service life increases, the internal equivalent resistance increases, and the capacitor deterioration becomes faster due to the increase in the voltage pulsation. Deterioration can be judged by doing this.

As described above, the diagnosis of the individual parts has a problem in that the diagnostic parameters increase and the diagnosis of each state increases the complexity of the system.

Conventional deterioration diagnosis system is a power conversion device, almost no research in the case of DC / DC converter, the mainstream is to diagnose the deterioration state of the capacitor, and when the input power is three-phase power supply, the state of the inverter and the converter is grasped Diagnostic methods have been studied.

Therefore, most of the diagnosis is performed by directly turning off the power and deteriorating diagnosis at the production site. Therefore, each part must be individually diagnosed while the operation is stopped. Therefore, the work efficiency is reduced and a lot of manpower is required to diagnose the degradation. In addition, since the deterioration state is determined by the experience of a technician, there are many difficulties in determining the accurate deterioration state of the system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the power conversion system diagnoses the degradation state of the entire system in real time through the analysis of the entire system, rather than the diagnosis method by the individual components. The purpose is to provide a real-time degradation diagnosis system of the device.

In addition, another object of the present invention is not a method in which a technician directly diagnoses and judges the degradation of a system in the offline diagnosis of the power converter, but performs the degradation state of the entire system in real time through the analysis of the entire system. The operator can determine the deterioration status of the power converter directly from a long distance through the communication network in real time online, and record the deterioration status of the power converter by recording data on various deterioration statuses to accurately replace and repair The present invention aims to provide a real-time online remote degradation diagnosis system of a power converter that can determine the power consumption.

In order to achieve the above object, a degradation diagnosis system of a DC / DC converter according to a preferred embodiment of the present invention, in the degradation diagnosis system of a DC / DC converter, analyzes and transfers a mathematical model of the DC / DC converter. Means for mathematically calculating; Means for experimentally measuring the transfer function of the DC / DC converter; Means for checking the state of each parameter of the converter by comparing each coefficient of the transfer function measured by the mathematical model and the experiment; And means for determining deterioration by checking the state of each parameter.

Here, the system for diagnosing degradation of a DC / DC converter includes: means for graphing each coefficient of the measured transfer function according to load variation; And means for determining a diagnosis of degradation using a change in the measurement data for the reference graph.

In addition, the degradation diagnosis system of the DC / DC converter according to the present invention, in the degradation diagnosis system of the DC / DC converter, generates a pulse signal from a triangular wave according to a control signal and applies the pulse width modulator to the DC / DC converter. ; Signal detecting means for detecting an output voltage of the DC / DC converter which changes according to the application of the pulse signal and converting the converted voltage into a digital signal; Degradation diagnosis means for diagnosing degradation of the DC / DC converter by analyzing a digital signal applied from the signal detection means; And a control signal generating means for generating a digital control signal by adding a predetermined voltage and a voltage sweeping each frequency noise, converting it into the analog control signal, and outputting the converted control signal to the pulse width modulator.

In addition, the real-time on-line remote degradation diagnosis system of the power converter according to the present invention is a system for diagnosing the degradation due to aging change of the DC / DC converter, the pulse for detecting the degradation of the DC / DC converter. Means for applying a signal and detecting an output signal of a DC / DC converter which changes in response to the pulse signal, and transmitting the detected output signal to a main computer below through a network and transmitting a control signal transmitted from the main computer. At least one system comprising means for receiving and generating said pulse signal, comprising: a DC / DC converter; Network means for enabling communication between the at least one system and the main computer; And a main computer for analyzing a signal transmitted from the at least one system and diagnosing the deterioration of the DC / DC converter of the corresponding system.

The main computer may include: means for measuring a transfer function in real time by measuring a control voltage and an output voltage specified during operation of each system by analyzing numerical data transmitted through a network; The internal resistance of the DC / DC converter is calculated by comparing the coefficients of the transfer function of the mathematical equivalent model of each DC / DC converter with the coefficients of the transfer function measured by the experiment. And means for comparing / analyzing the degradation.

1 is a configuration diagram of a real-time degradation diagnosis system of an open-loop DC / DC converter as a first embodiment of a degradation diagnosis system of a power conversion field according to the present invention.

2 is a configuration diagram of a real-time degradation diagnosis system of a closed-loop DC / DC converter as a first embodiment of a degradation diagnosis system of a power conversion field according to the present invention.

Figure 3 is a reference embodiment for the degradation diagnosis of the DC / DC converter as a degradation diagnosis system of the power conversion field according to the present invention.

4 is another embodiment of a method for diagnosing degradation of a DC / DC converter as a degradation diagnosis system of a power conversion field according to the present invention;

5 is a block diagram of a real-time online remote degradation diagnostic system of the power conversion apparatus according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: DC / DC converter 30: computer

40: pulse width modulator 50: proportional integral controller

Hereinafter, a real time degradation diagnosis system of a power converter according to an embodiment of the present invention and a real time online remote degradation diagnosis system of the power converter will be described with reference to the accompanying drawings.

1 is a configuration diagram of a real-time degradation diagnosis system of an open-loop DC / DC converter as a first embodiment of a degradation diagnosis system of a power conversion field according to the present invention.

As shown in FIG. 1, the real-time degradation diagnosis system of the present embodiment includes a DC / DC converter 10, a DAQ card 20, and a matlab program (Matlab Program) in order to apply a degradation diagnosis algorithm. A general purpose package program for engineering purposes, comprising a computer 30 equipped with real-time control, digital signal processing, simulation, signal processing, and image processing), a pulse width modulator (PWM) 40, and a load. (R).

The basic operating principle of the open-loop DC / DC converter 10 is as follows. In the pulse width modulator 40, as the control signal Vc is applied, the pulse signal V _pulse is generated by the control signal Vc and the triangular wave Vramp and applied to the DC / DC converter 10. For example, the pulse signal V _pulse forms a high level in a period in which the triangular wave Vramp is greater than the control signal Vc and a low level in a period in which the triangular wave Vramp is lower than the control signal Vc. The pulse signal V _pulse drives a switch (e.g., a FET shown in Figs. 3A to 3C). The output voltage (Vo) of a DC / DC converter 10 is determined by the relation of the input voltage (Vin) and the pulse signal (V _pulse), the duty ratio (duty ratio) of the pulse signal (V _pulse) changes, the output voltage The size of Vo also changes.

In order to obtain the control-to-output of the DC / DC converter 10, a noise component of each frequency is applied to the control voltage Vc to analyze the components appearing in the output voltage Vo and the control voltage Vc. The variation in output voltage (Vo) with respect to To this end, the control signal Vc is generated by adding a constant voltage Vconst and a voltage Vsweep sweeping each frequency noise using the matlab program 30A. Since the voltage generated by the computer 30 is a digital signal, it is converted into an analog signal using a digital / analog converter (here, the DAQ Card 20). The control signal Vc has a ripple of each frequency when each frequency noise is swept, and disturbs the duty ratio of the pulse signal voltage (V _pulse ) generated by comparing with the voltage of the triangle wave (Vramp). It will play the same role as giving. This also affects the output voltage Vo, resulting in noise components of each frequency that do not appear in the normal state, and senses the output voltage Vo to sense the output voltage Vo and, in this case, the computer 30 through an analog / digital converter (DAQ Card 20). Send a signal to The computer 30 calculates the gain and phase at each frequency by calculating the ratio of the control voltage Vc signal and the output voltage Vo signal using the matlab program 30A. This is referred to as the Bode Plot. This transfer function consists of a combination of poles and zeros, and the poles and zeros can be found by the Matlab program.

2 is a configuration diagram of a real-time degradation diagnosis system of a closed-loop DC / DC converter as a second embodiment of a degradation diagnosis system of a power conversion field according to the present invention.

As shown in FIG. 2, the real-time degradation diagnosis system of the present embodiment is an open loop DC / DC converter 10A except that the output voltage Vo is controlled using a proportional integral controller 50 (PI controller). Is the same as the deterioration diagnostic system. This is applicable to a practical system because a normal system operates by controlling the output voltage.

The basic operation principle of the closed loop DC / DC converter 10A is as follows. The output voltage Vo is sensed to generate a desired output voltage Vo and compared with the reference voltage Vref to generate a control signal Vc. The generated control signal Vc generates a pulse signal V _{pulse in} comparison with the triangular wave Vramp to generate a gate signal of the switch (for example, the FET shown in FIGS. 3A to 3C) of the DC / DC converter 10A. Is approved. In order to ensure the response characteristics and the stability of the DC / DC converter 10A before generating the control signal Vc, the proportional integral controller 50 (PI Controller) is configured for the system.

In order to obtain the loop-gain of the DC / DC converter 10A, the output voltage Vo is sensed and analog-to-digital-converted by the DAQ card 20 and transmitted to the computer 30. A control signal is generated through a proportional integral controller 50 (PI controller) by generating a digital control signal by adding a sweep voltage Vsweep that sweeps each frequency noise to the output voltage Vo and comparing it with a reference voltage Vref. Produces (Vc). This results in the same role as giving disturbance to the control signal Vc, and measuring the variation of Vo with respect to Vx results in the transfer function of the loop-gain of the DC / DC converter 10A. The transfer function of the loop-gain includes the transfer function of the proportional integral controller 50 (PI controller), and according to the combination of the proportional integral controller 50, the loop-gain is obtained. Will be different.

3 is a view for explaining three reference embodiments of the degradation diagnosis of the DC / DC converter as a degradation diagnosis system of the power conversion field according to the present invention.

In Fig. 3, each DC / DC converter is analyzed and a transfer function is expressed as a formula. The method of interpreting the transfer function has been published in many papers and is an experimentally validated method. Looking briefly at the analytical model of each DC / DC converter, the transfer function G (s) consists of the direct current gain, the zero term of the numerator, and the pole term of the denominator. It is expressed as Each coefficient consists of a combination of a capacitor, an inductor, a duty ratio, a load resistance, and an internal resistance of each device.

Here, the DC / DC converter may include a buck converter, a boost converter, a buck-boost converter, a flyback converter, a half-bridge converter, and a full-bridge. bridge converter, push-pull converter, Zero-Voltage Switching (ZVS) converter, Zero-Current Switching (ZCS) converter, and the like. In FIG. 3, a buck converter and a boost An equivalent circuit for a converter and a buck-boost converter is shown by way of example.

The transfer function G (s) of a general DC / DC converter is expressed as follows.

3A is an equivalent circuit of a buck converter. The analytic model of this buck converter can be expressed as

3B is an equivalent circuit of the boost converter. The analytical model of this boost converter can be expressed as

3C is an equivalent circuit of a buck-boost converter. The analytic model of this buck-boost converter can be expressed as

The transfer function measured in FIG. 1 and FIG. 2 has the same result as the mathematical model of the transfer function obtained in FIGS. 3A to 3C. The transfer function of the calculated transfer function and the calculated equation are compared with the respective coefficients, zero points, and poles. We can get the information about, and develop the formula obtained by comparing the coefficients, we can also get the value for each parameter.

As the DC / DC converter deteriorates, the values of the parameters of the DC / DC converter change, and the degree of change varies according to each device. For example, if the deterioration continues for a long time, the output capacitor value decreases and the output The internal resistance (ESR) of the capacitor will increase rapidly. And, since most of the internal resistors will rise in value, The values change, and by determining this, it is possible to measure the deterioration state of the DC / DC converter.

4A to 4E are views for explaining another embodiment of a method for diagnosing degradation of a DC / DC converter as a system for diagnosing degradation of a power conversion field according to the present invention.

FIG. 4A illustrates the change characteristic of the duty of the pulse signal V _pulse according to the load variation, and the steady state is indicated by a solid line and the deteriorated state is indicated by a dotted line. 4b is a coefficient of the transfer function G (s) according to the load variation The change characteristics of are shown in the normal state by the solid line and the deteriorated state by the dotted line. FIG. 4C shows the change characteristic of the coefficient a ₁ of the transfer function G (s) according to the load variation. The steady state is indicated by a solid line and the deteriorated state is indicated by a dotted line. FIG. 4D shows the change characteristic of the coefficient a ₂ of the transfer function G (s) according to the load variation. The steady state is indicated by a solid line and the deteriorated state is indicated by a dotted line. Figure 4e shows the change characteristics of the coefficient c _z of the transfer function G (s) according to the load change, the steady state is shown by the solid line and the deterioration state is shown by the dotted line.

In addition to the analysis method of FIG. 3, as shown in FIG. 4, when the duty of the pulse signal (V _pulse ) and the coefficients of the transfer function are represented graphically, the power converter of the system constantly changes the load so that the load fluctuates. Poor deterioration can be easily judged. The difference between the graph in the steady state and the graph after deterioration is generated, and the difference can be used to determine the deterioration.

5 is a block diagram of a real-time online remote degradation diagnostic system of the power conversion apparatus according to the present invention. The figure illustrates a DC / DC converter as a power converter.

The real-time online remote degradation diagnosis system of the power conversion apparatus of the present invention includes a plurality of power conversion system (100_1 ~ 100_n), the network device 200 and the main computer 300.

The power converter system 100_1 to 100_n converts the DC / DC converter 110 and the control signal applied to the converter 110 into digital / analog conversion and converts the detected signal detected by the converter 110 into analog / digital signals. The converted signal converter 120 and the detected detection signal are digitally processed and temporarily stored in a memory (SRAM) and outputted to a connection point manager (CPM) to be connected to the main computer (network device 200). And a control signal from the main computer 300 is inputted from a connection point manager (CPM) via the network device 200, and then digitally processed and received through the signal converter 120. It is composed of a communication device 130 for transmitting to the converter (110). Here, in the communication device 130, a subscriber matching device (SIU) for transmitting the detection signal data in real time or periodically to the main computer 300 with a unique identification code assigned to each power conversion device system. It may be configured to include an Interface Unit, and may further include a nonvolatile memory (EPROM) and an embedded programmable logic device (EPLD) chip.

The network device 200 provides a communication path between a plurality of power converter system 100_1 ˜ 100_n and the main computer 300, and includes a network processor and a network switch.

The main computer 300 identifies and classifies sensing signals input from the power converter systems 100_1 to 100_n and uses DC / DC converters 110 of the respective power converter systems from the classified sensing signals using a matlab program. The transfer function of and the coefficient of the transfer function can be extracted, and the deterioration state of the system can be diagnosed from this extracted value.

In the real-time online remote degradation diagnostic system of the power converter shown in FIG. 5, a DC / DC converter is constructed using a digital signal processor based on the results of FIGS. 1 to 4, and the measured data is online on the main computer. In the main computer, the MATLAB program is used to measure the transfer function and the coefficients of the transfer function of the DC / DC converter, extract the degradation parameter values, and determine the change of the DC / DC converter to diagnose the degradation. Can be. This has the advantage of diagnosing the deterioration state of the system in real time and monitoring the characteristics of the system from a long distance through the Internet, thereby continuously identifying the deterioration state of the system.

Meanwhile, in the above specific embodiments, the DC / DC converter is illustrated as a power converter, but the present invention is not limited thereto, and the present invention may be applied to other power converters such as a DC / AC converter and an AC / DC converter. to be.

On the other hand, the present invention is not limited to the above-described typical preferred embodiments, but can be carried out in various ways without departing from the gist of the present invention, various modifications, alterations, substitutions or additions are common in the art Those who have knowledge will easily understand. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

As described in detail above, the present invention has the following effects.

First, the degradation diagnosis can be enabled while the power converter is operating, and the degradation diagnosis data can be monitored remotely through a communication network.

Second, the deterioration state can be diagnosed through the analysis of the entire system, not the diagnostic method for the individual components of the power converter.

Third, since the degradation diagnosis is performed during operation, it does not interfere with the operation of the site, the deterioration diagnosis manpower is reduced, and periodic and systematic degradation diagnosis is possible.

Fourth, management of deterioration diagnostic data becomes easy, and reliability is improved and efficient prevention is possible.

Fifth, in addition to diagnosing deterioration by measuring the transfer function of the transducer, when measuring the loop function, the gain and phase margin of the system can be measured. Evaluate system stability.

Claims (8)

In the deterioration diagnosis system of the DC / DC converter, Means for mathematically calculating a transfer function by analyzing a mathematical model of the DC / DC converter; Means for experimentally measuring the transfer function of the DC / DC converter; Means for checking the state of each parameter of the converter by comparing each coefficient of the transfer function measured by the mathematical model and the experiment; And a means for judging deterioration by checking the state of each parameter. The method of claim 1, Means for graphing each coefficient of the measured transfer function in accordance with load variation; And a means for determining the degradation diagnosis using the change in the measurement data with respect to the reference graph. In the degradation diagnosis system of the DC / DC converter, A pulse width modulator for generating a pulse signal from a triangular wave according to a control signal and applying the pulse signal to the DC / DC converter; Signal detecting means for detecting an output voltage of the DC / DC converter which changes according to the application of the pulse signal and converting the converted voltage into a digital signal; Degradation diagnosis means for diagnosing degradation of the DC / DC converter by analyzing a digital signal applied from the signal detection means; And a control signal generating means for generating a digital control signal by adding a predetermined voltage and a voltage sweeping each frequency noise, converting it into the analog control signal, and outputting the control signal to the pulse width modulator. Deterioration diagnosis system of DC / DC converter. The method of claim 3, wherein The DC / DC converter is an open-loop DC / DC converter. The method of claim 3, wherein And the control signal generating means converts the generated digital control signal into an analog and then proportionally integrates the control signal to generate the control signal and output the control signal to the pulse width modulator. The method of claim 5, The DC / DC converter is a closed-loop DC / DC converter. In a system for diagnosing deterioration due to aging change of a DC / DC converter, Means for applying a pulse signal for detecting the deterioration of the DC / DC converter and detecting an output signal of the DC / DC converter which changes in response to the pulse signal, and transmitting the detected output signal to the following main computer via a network; Means for transmitting and receiving the control signal transmitted from the main computer to generate the pulse signal, comprising: at least one system using a DC / DC converter; Network means for enabling communication between the at least one system and the main computer; And a main computer for analyzing the signal transmitted from the at least one system to diagnose the deterioration of the DC / DC converter of the corresponding system. The method of claim 7, wherein The main computer may include means for measuring a transfer function in real time by measuring numerical control of data transmitted through a network by measuring a control voltage and an output voltage specified during operation of the DC / DC converter of each system; The internal resistance of the DC / DC converter is calculated by comparing the coefficients of the transfer function of the mathematical equivalent model of each DC / DC converter with the coefficients of the transfer function measured by the experiment. A real-time on-line remote degradation diagnosis system of a power converter, characterized in that it comprises a means for determining the degradation by comparing / analyzing.