| 摘要 |
PROBLEM TO BE SOLVED: To obtain a power converter which can prevent a switching element from thermal destruction even when a fluctuation such as a momentary voltage drop or voltage imbalance occurs in a connected grid and consequently a momentary AC current being output to the grid changes greatly, causing the switching frequency to increase.SOLUTION: In a hysteresis current control type power converter, each switching element of an upper and a lower arm are switched between on and off to change the polarity of an output voltage so that a deviation between an AC current directive which is a target current to be output to the grid and the detected momentary value of an output AC current fits within the width of upper and lower limit thresholds in reciprocal form, in which way the output AC current to the grid is controlled. The power converter includes means which, when the element temperatures of the switching elements and the working limit temperature are compared and the element temperatures are found to exceed the working limit temperature, stops the on/off control of the respective switching elements of the upper and lower arms. |
