Electric power conversion apparatus

A power conversion device comprising a circuit in which a chopper circuit is integrated with a converter circuit including an LLC circuit, wherein

• the converter circuit includes:
• a transformer having a primary coil and a secondary coil;
• a positive-side half-bridge circuit and a negative-side half-bridge circuit, each having two power devices connected in series, each of the power devices including a switching element and a freewheeling diode connected in antiparallel with the switching element;
• an upper intermediate wiring connecting an end of the primary coil on a positive side and a portion between the two power devices of the positive-side half-bridge circuit;
• a lower intermediate wiring connecting an end of the primary coil on a negative side and a portion between the two power devices of the negative-side half-bridge circuit;
• a resonant capacitor arranged on the upper intermediate wiring;
• a positive main line connected to positive sides of the positive-side half-bridge circuit and the negative-side half-bridge circuit;
• a negative main line connected to negative sides of the positive-side half-bridge circuit and the negative-side half-bridge circuit;
• and
• a second capacitor connected between the positive main line and the negative main line, while being in parallel with the positive-side half-bridge circuit and the negative-side half-bridge circuit;
• and
• the chopper circuit includes:
• a positive line connected to a positive-side input terminal;
• a negative line connected to a negative-side input terminal;
• a first capacitor connected between the positive line and the negative line;
• a bridge circuit connected between the positive line and the negative line, the bridge circuit including a first device constituted by the power device and a diode, the first device and the diode being arranged in series;
• a connecting wire connecting a portion between the first device and the diode of the bridge circuit and a portion between the two power devices of the positive-side half-bridge circuit;
• and
• a reactor arranged on the connecting wire,
• the power conversion device further comprises a controller configured to perform switching control of each of the switching elements, and
• the controller performs both step-up and step-down operations by switching, in different patterns, a first switching element that is the switching element of the first device.