Nonlinear control of five phase induction motor with synchronized third harmonic flux injection

The paper deals with the novel control system for five phase induction motor (IM) that enables the injection of the rotor flux 3rd harmonic component. Two multiscalar models are transformed from the α₁-β₁ and α₂-β₂ vector models developed in the 1st and 3rd harmonic planes. Based on the obtained multiscalar models the synthesis of dual multiscalar control is established. The obtained two multiscalar control systems can independently regulate amplitudes and the relative position of rotor flux and stator current vectors in the 1st and 3rd harmonic plane respectively. Full decoupling of rotor angular speed and rotor flux control and possibility of the injection of third harmonic flux exactly synchronized with fundamental flux component are main benefits of the proposed control. The alignment of 1st harmonic and 3rd harmonic components of the rotor flux is provided by the action of the second multiscalar control system. The cascade of two controllers: 3rd harmonic flux angle controller and 3rd harmonic flux angular velocity controller is used for generation of torque reference signal in the second control system. Compared to previously published control schemes the proposed algorithm gives the possibility of exact alignment of the fundamental and 3rd harmonic rotor flux waveforms. The newly derived control structure was investigated by simulations. The obtained simulation results show that the air-gap flux is aligned both in steady state and transients of the five phase IM which ensures trapezoidal shape of air gap induction waveform independently of the machine load condition.