CONTROL METHOD OF NEUTRAL POINT CLAMPING INVERTER

摘要

PROBLEM TO BE SOLVED: To quickly enable power running or regeneration again after operating an overvoltage suppression circuit regarding the control of an AC electric motor due to a neutral point clamping inverter. SOLUTION: In a control method of a neutral point clamp system inverter where an AC electric motor 4 is subjected to variable speed control by an inverter where an overvoltage suppression circuit for igniting switching elements 8U1-8W4 for discharging is provided at the DC side of an inverter 11 when filter capacitors 7p and 7n reach an overvoltage, when the switching element of the overvoltage suppression circuit is ignited and the voltage of the filter capacitor reaches a specific value while the AC electric motor 4 is being rotated, all switching elements of the inverter being included between clamp diodes 10U1-10W2 of the inverter and the AC electric motor are ignited over each phase.