A loop filter and amplifier is configured to generate a control voltage by applying low gain to a correction voltage in response to an input signal indicating that the VCO is to operate at low frequencies and applying high gain to the correction voltage in response to the input signal indicating that the VCO is to operate at high frequencies. The connector plug is adapted to fit into a mating receptacle that is attached to the electric vehicle. The monitoring module has a power monitoring unit, a first circuit switch, a second circuit switch, and a first processor. A variation is obtained on the basis of the position and orientation acquired in step S204 and those obtained in step S203.