Power Converter

A power converter comprising:

• an inverter for converting DC power to AC power to be supplied to a motor;
• a contactor for connecting a battery to the inverter in order to supply DC power from the battery to the inverter and for disconnecting the battery from the inverter in order to stop an operation to supply DC power from the battery to the inverter;
• a smoothing capacitor connected in parallel to the battery through the contactor;
• a discharge circuit that is provided with a discharge resistor and a switching device connected in series to the discharge resistor and is connected in parallel to the smoothing capacitor to discharge electric charge from the smoothing capacitor;
• a voltage measurement circuit for measuring a voltage across terminals of the smoothing capacitor;
• a voltage-dividing circuit for dividing the voltage across the terminals of the smoothing capacitor to generate a partial voltage to be input to the voltage measurement circuit;
• and
• a control circuit for controlling an operation to turn on and off the switching device, wherein:
• before the control circuit turns on the switching device for a first predetermined period to discharge the smoothing capacitor until the voltage across the terminals of the smoothing capacitor decreases to a level equal to or lower than the first predetermined voltage, the control circuit turns on the switching device for a second predetermined period shorter than the first predetermined period to measure the voltage across the terminals of the smoothing capacitor before and after the second predetermined period;
• and
• a determination section determines whether the contactor is turned on or off according to the measured voltage across the terminals of the smoothing capacitor before and after the second predetermined period.