A Simple Capacitance Estimation System for Failure Diagnosis of DC Link Electrolytic Capacitor in Power Converters

摘要

DC converting AC to inverter and DC / DC converters, such as the power converter in the DC link section on the use which is mainly used for the capacitor voltage of the DC energy associated (link) and the smoothed voltage of the charging and discharging energy and a buffer (buffer). DC link capacitor is large and the capacity thereof, while inexpensive, is the most aluminum electrolytic capacitors because of the relatively rapid charge / discharge characteristics are used. However, the increasing use of such electrolytic capacitors, etc., due to the deterioration and the temperature rise reaches a critical problem that could lead to accidents such as steam eruption (vaporization) of the electrolyte (electrolyte). Such thinking is needed to replace worn parts such as accident prevention measures in advance according to the internal parameters of the installation or pre-detection of power through the power converter circuit, leading to a short-circuit failure can be a very dangerous situation for this fault diagnosis system. Therefore, the replacement time of the internal parameter estimation based on a part of the capacitor to the efficient maintenance of the direct current link capacitor is used in various kinds of power converters, it is necessary to determine. The method of using the capacity thereof estimator decrease of the capacitance according to the increase of use time and the equivalent series resistance; the diagnostic technique using the estimated increase in the (equivalent series resistor hereinafter ''ESR'' quot;) is mainly used. Much of the diagnosis was a simple measuring device with respect to the invention-amount estimation device for the capacitance to the performance of the diagnostic system, the expansion techniques are broken up, but the present invention determined by the estimate of the ESR. Sonjingeun amount estimation with respect to the electrolytic capacitor, such as a frequency presented Copyright Policy | Privacy Policy, and ESR of the capacitor capacitance measurement technique according to the method of analysis, but their method is difficult to detect the signal of the pulse wave of the driving voltage and current of the capacitor, and band-pass filter The configuration and FFT signal analysis techniques have the disadvantage of difficult. In addition, the proposed method with the conventional method has a capacity estimated by the constant current discharge, but which present the disadvantage of the configuration of the constant current control circuit difficult, but also the frequency injection method to construct a separate AC converter. Therefore, in the present invention, the capacitor-amount estimation device for a power converter, if the price does not require any configuration, without the use value of the LCR meter instrument complex addition circuit cheap way while still offer. Their method is composed of the oscilloscope to also estimate a simple manner by using a charging and discharging circuit of the power converter to a DC link capacitor diagnosis. This has the advantage that when the product manufactured in a manner using the sampling techniques of the power accumulated average energy within a predetermined discharge time (T) of the capacitor it is possible to estimate the capacity of a simple component that can be inexpensive and portable. Its simulation results to verify the proposed method was estimated satisfactorily displayed, its result is compared to the next electrolytic capacitor capacity estimation value of the steady state value of about 25 [%] to the beginning of the failure diagnostic system for determining the end of life or less Try to use the application shall be considered by. Accordingly, the present invention proposes a power converter in which case a separate instrument of the LCR meter price of cheap method that does not require complex configuration without using a separate circuit capacitor capacity estimation technique during a stop. Their method is composed of the oscilloscope to also estimate a simple manner by using a charging and discharging circuit of the power converter to a DC link capacitor diagnosis. This is a method using the sampling techniques of the power accumulated average energy within a predetermined discharge time (T) of the capacitor. Ensure its validity and the accuracy of the text to look at the estimated capacitance measurement period T, RC time constant (), the results for the relationship between the sampling number n comprehensively analyzes saw. A result of this, in order to improve the estimation accuracy of the capacitance measurement period T, and is sufficiently less than the RC time constant, RC Was found that to increase the accuracy of the estimation by increasing the capacitance of the sampling number n in the case of satisfying the T. Overall, a result of the proposed simulation of the method is preferably further shown, compared to the electrolytic capacitor capacity estimation value of the steady state value of about 25 [%] Element enemy application and fault diagnosis system, to determine the start of the end of life or less This feed will be available. The invention is expected to be applied to on-demand power unit is now widely used, particularly electrolytic capacitor failure prediction of the electric vehicle, which is not possible by using expensive film capacitor, wind power, solar power delivered to the system that can be applied to the capacitor is expected to provide electricity.