High-frequency power supply device and control method of the same

A high-frequency power supply device, comprising:

• a class E inverter, having a first switching element, to convert a direct-current (DC) power into an alternating-current power by an on/off operation of the first switching element;
• a second switching element to switch whether or not the DC power is input to the class E inverter;
• a rectifier element to allow a current to flow from a ground to the class E inverter when the second switching element is off;
• and
• a control circuit to control on/off of the first switching element and the second switching element, wherein
• in an operation period of the class E inverter, the control circuit causes the first switching element to periodically perform the on/off operation and maintains the second switching element in an ON state,
• in a stop period of the class E inverter, the control circuit maintains the first switching element and the second switching element in an OFF state, and
• in a transition period, during the operation period, which is immediately prior to the stop period, the control circuit causes the first switching element to periodically perform the on/off operation and maintains the second switching element in the OFF state.