Electric power conversion device

An electric power conversion device in which semiconductor element groups constituting an electric power conversion part are formed as one unit;

• a main circuit of the electric power conversion part is such that four semiconductor elements of a first semiconductor element to a fourth semiconductor element are connected in series between a dc positive terminal and a dc negative terminal, and a first diode and a second diode are connected in series;
• an ac terminal is connected to a connection point of a second semiconductor element and a third semiconductor element and a neutral terminal is connected to a connection point of the first diode and the second diode;
• the first diode is connected to a connection point of the first semiconductor element and the second semiconductor element and the second diode is connected to a connection point of the third semiconductor element and the fourth semiconductor element;
• and the semiconductor element groups constituting the one unit are mounted on a cooler heat receiving part on the same plane and are adapted to radiate heat by self-cooling or forced cooling by wind,
• wherein the first semiconductor element and the fourth semiconductor element are arranged on the windward side of the cooler heat receiving part, the second semiconductor element and the third semiconductor element are arranged in the middle of the cooling wind direction of the cooler heat receiving part, the first diode and the second diode are arranged on the leeward side of the cooler heat receiving part, the first semiconductor element and the second semiconductor element, as well as the third semiconductor element and the fourth semiconductor element are each arranged in positions opposite to each other in a horizontal direction with respect to a centerline of the cooler heat receiving part in the cooling wind direction, the first diode is arranged on the same side as the second semiconductor element in a horizontal direction with respect to the centerline, and the second diode is arranged on the same side as the third semiconductor element in a horizontal direction with respect to the centerline.