PROTECTING CIRCUIT FOR SERIES TYPE HIGH-FREQUENCY INVERTER

摘要

PURPOSE:To protect an inverter, by detecting the magnetic flux saturation of a transformer with the abnormal voltage of a magnetic-deviation-proof capacitor, and by tripping the inverter. CONSTITUTION:The protective device of an inverter is composed of a potential transformer PT, a full-wave rectifier circuit CR, a comparator 5, the overvoltage trip level setting unit 6 of the inverter, and an inverter trip signal output circuit 7. In this case, when a transformer Trm is magnetic-flux-saturated by the control error working of switching elements 1-4, then a capacitor Cm1 is charged with DC voltage. As this result, voltage at both the ends of the capacitor Cm1 exceeds an overvoltage trip level, and from the comparator 5, the output of inverter trip signal is generated, and the inverter is tripped.