Induction motor driver

摘要

A switched resonant power converter applies AC to an induction motor. The power converter controls the magnitude and phase of the motor current, and tuning the stator flux accordingly in order to control the motor speed. A preprocessor operates on a speed command signal by getting the user speed command input to produce amplitude and phase-related signals for application to inputs of the power converter control.

主权项

1. A method for controlling the speed of an induction motor including a rotor, said method comprising the steps of:
selecting a desired rotor speed; determining motor rotor speed; comparing said motor rotor speed to said desired rotor speed, to thereby generate a speed error signal; applying said speed error signal to a proportional-integral controller, to thereby generate a torque command signal; normalizing said torque command signal to maximum specified torque to thereby generate normalized signals; determining a magnetizing current of said motor; generating a stator current amplitude command signal from said torque command signal; determining ideal volts/Hz value for the motor; subtracting an actual volts/Hz value from the ideal volts/Hz value for the motor, to thereby generate volts/Hz error; multiplying said volts/Hz error by at least a constant and an integral to thereby generate a phase correction signal; generating a current phase precursor signal from said torque command signal; adding said current phase precursor signal to said phase correction signal to thereby generate a signal representing the phase of the stator current; and controlling the switching of current to and from a central capacitor in response to said amplitude command signal and said signal representing the phase of said stator current.