Induction Motor Voltage Amplitude Control Technique based on the Motor Efficiency Observation

摘要

The main problem in control of AC induction motor speed is control of amplitude of AC voltage provided by the frequency converter. There are two widely used amplitude control methods: scalar and vector control [1-7]. The scalar control is based on the steady-state model of motor. The linear law of voltage amplitude control (ratio amplitude to phase frequency U_A/f_p = const) should be applied to keep the magnetizing flux of the motor practically unchanged according this model. This allows us to keep the torque of the motor nearly independent on the motor velocity. The scalar control is used when the motor load is approximately independent on motor speed or if load dependence on speed is known in advance.