Control apparatus for inverter

摘要

An inverter control apparatus comprises a first current level setting unit 5 which sets a protection level for switching elements included in an inverter 1, and a second current level setting unit 7 which sets a current level that prevents a stall torque/slip point from being exceeded and which is determined in association with the load characteristic of an induction motor and the voltage/frequency ratio being delivered by the inverter. The smaller of the two current levels is selected to control the frequency to lower or stop its rise to prevent the slip frequency from being exceeded. Thus, stable operation without stalling or damage to the inverter elements is achieved regardless of the voltage/frequency ratio set to drive the motor or the particular induction motor used.