Abstract: This paper deals with the closed-loop control method for SPWM inverter used in DC-link VSCF electrical power system. An instantaneous feedback control system is proposed, in which AC current inner loop and AC voltage outer loop are involved. For 1 kVA single phase SPWM inverter, the closed-loop control system is designed and analysed. The result of the experiments shows that the SPWM inverter with instantaneous feedback control has good static and dynamic electrical performance, with little distortion in the output waveform and the output voltage variation due to the variable DC voltage being effectively suppressed. It is suitable to use this closed-loop control method in the system suppliedby a permanent magnet generator.

Key words: VSCF, inverter, closed-loop control