POWER CONVERSION DEVICE AND FAILURE DETECTION METHOD OF POWER CONVERSION DEVICE

PROBLEM TO BE SOLVED: To provide a power conversion device which determines a device short circuit and a short circuit of an energy accumulating device to perform treatment without providing a short circuit device in a unit converter by using a semiconductor element to be a short circuit state at the time of failure.SOLUTION: A power conversion device includes: a unit converter 105 which has a series circuit in which switching elements 21H, 21L to be a short circuit state at the time of failure are connected in series, and a plurality of capacitors C1, C2 which are connected in parallel therewith, and outputs voltage relying on on/off of the switching elements 21H, 21L and relying on voltage of the capacitors C1, C2 or zero voltage; and a plurality of arms which connect the plurality of unit converters 105 in series. The unit converter 105 includes a current sensor CT which detects a current flowing between the switching elements 21H, 21L and the capacitors C1, C2, a voltage sensor 5 which detects voltage of the capacitors C1, C2, and a self controller 4 which determines an own failure part from the current detection value and the voltage detection value to perform treatment. 【課題】故障時に短絡状態となる半導体素子を使用し、単位変換器に短絡装置を設けることなくデバイス短絡とエネルギ蓄積器の短絡とを判断して処置する。【解決手段】電力変換装置は、故障時に短絡状態となるスイッチング素子２１Ｈ，２１Ｌを直列に接続した直列回路と、これに並列接続される複数のコンデンサＣ１，Ｃ２とを備え、スイッチング素子２１Ｈ，２１Ｌのオン・オフに依存してコンデンサＣ１，Ｃ２の電圧に依存する電圧または零電圧を出力する単位変換器１０５と、これらを複数直列に接続したアームを複数備える。単位変換器１０５は、スイッチング素子２１Ｈ，２１ＬとコンデンサＣ１，Ｃ２との間に流れる電流を検出する電流センサＣＴと、コンデンサＣ１，Ｃ２の電圧を検出する電圧センサ５と、電流検出値および電圧検出値から自身の故障個所を判断して処置するセルコントローラ４とを備える。【選択図】図２