METHOD AND SYSTEM FOR DETECTING UNBALANCE IN OUTPUT CURRENT FROM VOLTAGE TYPE INVERTER

摘要

PURPOSE: To provide a method and system for detecting unbalance in the output current from a voltage type inverter in which the normal inverter circuit is protected against failure by detecting the unbalance state of AC output current for each of a plurality of inverter circuits being driven in parallel before stopping the operation. CONSTITUTION: Output current signals ID1 -IDn from full-wave rectifier circuits 11-13 are compared with a mean output current value Ia being fed from an adder circuit 14. Based on the fact whether the difference comes within a predetermined reference range or not, a decision is made for each AC output current whether it is unbalanced or not and an unbalance detection signal IF1 -IFn is delivered to an OR circuit 18. Upon receiving an unbalance detection signal IF1 -IFn , the OR circuit 18 delivers an abnormal stop signal to a control circuit (not shown) in order to interrupt the delivery of a switching control signal to an inverter circuit thus stopping the operation.