A boost control section for controlling a converter includes a PI control section and a resonance suppression section. The PI control section calculates a basic command value based on a deviation between a drive voltage generated by the converter and a target voltage to equalize the drive voltage and the target voltage. The resonance suppression section calculates, based on the state of variation of the drive voltage, a correction value for correcting the basic command value to suppress the variation. The basic command value is corrected by adding the correction value. First and second drive pulses corresponding to the corrected command value are outputted to the converter.