PARALLEL OPERATING SYSTEM FOR AC OUTPUT INVERTER

PURPOSE:To realize stabilized parallel operation of different types of AC sine wave power supplies by adding a command value of voltage major loop to the command value of minor loop for ensuring a sine wave bus voltage based on the instantaneous value of output current from an AC output converter. CONSTITUTION:An inverter 1, an AC generator 150 and another AC sine wave power supply are connected in parallel to feed a common load 5 with power. Output current of the inverter IV 1 is converted 8 into a voltage which is then added to the output from a limiter 16 thus forming a minor loop. Output current of the IV 1 is detected 7, and a load current IL is also detected 35 and fed to a bearing current detector 91 which then outputs the difference I between the bearing current IL/n and the current value of the inverter 1. A current control circuit 15 is then fed with a command value for a major loop comprising a I amplifier 92, a limiter 17, a voltage regulator 32 for matching the average voltage of the IV l taken out through a rectifier circuit 31 with a set voltage 22, a voltage controller 18, and a limiter 16. Consequently, load is born appropriately between different types of AC sine wave power supplies.