Study on a control method of a single-phase utility interactive inverter with a power decoupling function

The present paper introduces a singlephase grid connected inverter with a power decoupling function. A power pulsation with twice the grid frequency is contained in the input power of a singlephase inverter. In a conventional inverter, electrolytic capacitors having large capacitances have been used in order to stabilize the input dc-bus voltage. However, the lifetime of the capacitor is shortened by the power pulsation. The present authors have investigated an active power decupling (APD) method that reduces the pulsating power on the input dc bus line, because the pulsated energy on the input dc capacitors is transferred to the energy in a small film capacitor on an additional circuit. Hence, extension of the lifetime of the inverter can be expected by substituting a small film capacitor for the large electrolytic capacitors.