Abstract: In an inverter comprising a converter circuit that converts an alternating current into a direct current and an inverter circuit that inverts the direct current into the alternating current, supply of energy from a voltage smoothing capacitor to a load or recovery of energy from the load is facilitated without the necessity of increasing the capacitance of the voltage smoothing capacitor interposed between the converter circuit and inverter circuit. In the converter circuit, before the supply of energy to the load is started, the voltage on a dc link is raised. Before collection of energy from the load is started, the voltage on the dc link is lowered.