Controller for power converter

TL;DR: In this paper, the main circuit element of an inverter has been deteriorated due to thermal stress due to accumulated information on the state of operation of the inverter, such as the voltage, voltage, and state of gate start and stop.

Abstract: PROBLEM TO BE SOLVED: To provide a power converter that seldom produces trouble in a main circuit, wherein deterioration in a main circuit element, a smoothing capacitor, and a smoothing reactor due to thermal stress is determined from accumulated information on the state of inverter operation. SOLUTION: A device is for controlling the power converter 1 that drives an induction motor by an inverter having a main circuit element. This device includes means 14 for detecting the temperature of the main circuit element of the inverter; means 20 for computing a first coefficient normalized from a switching frequency; means 21 for computing a second coefficient normalized from an output voltage command; means 22 for multiplying the first coefficient, second coefficient, and detected temperature to compute an amount of thermal stress; means 23 for determining the states of gate start and stop of the inverter; means 25 for adding and storing the amounts of thermal stress during the operating time of the inverter; means 26 for accumulating added values to compute an accumulated value; and means 27 that, when the computed accumulated value becomes equal to or higher than a predetermined value, determines that the main circuit element has been deteriorated. COPYRIGHT: (C)2007,JPO&INPIT