Converter controller

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.