Patent ID: 8896282

Claim:
A controller of a soft switching converter which controls an output voltage of a fuel cell and which includes a main voltage raising circuit and an auxiliary circuit, the auxiliary circuit including: an auxiliary switch, and a first series connecting member in which a clamp diode and a snubber capacitor are connected in series, the clamp diode and the snubber capacitor being connected in parallel with a main switch constituting the main voltage raising circuit and connected to a high potential side terminal and a low potential side terminal of the fuel cell; the converter controller comprising: a detecting device that detects a voltage between both the ends of the snubber capacitor clamped by the clamp diode in a case where the main switch is turned off, and a judging device that compares the voltage between both the ends of the snubber capacitor with a set normal voltage threshold value to judge that an abnormality occurs in the auxiliary circuit in a case where the voltage between both ends exceeds the normal voltage threshold value, wherein, when the judging device judges that an abnormality has occurred in the auxiliary circuit, the judging device switches from a first phase of the converter, in which the auxiliary circuit has the abnormality, to a second phase of the converter.