process and device for the formation of the scale of the reference voltage of a three-phase inverter that drives a motor of squirrel cage

摘要

A method of forming the amplitude of the reference voltage of a three-phase inverter supplying a squirrel cage motor requires no current measuring elements. In this method, the amplitude is formed by finding in predetermined constant flux curves which represent the squirrel cage motor in question, and in which the motor rotor current frequency appears as parameter, a curve from which is obtained the amplitude of the motor stator voltage, i.e. of the inverter reference voltage, corresponding to the frequency of the motor's stator voltage, i.e. of the inverter reference voltage, so that the magnetic flux in the stator will be constant.