Field oriented control of five-phase synchronous reluctance motor drive with flexible 3rd harmonic current injection for high specific torque

It is shown that 3rd harmonic current injection can produce higher shaft torque than conventional sinusoidal current regulation in five-phase synchronous reluctance machines with salient-pole rotors. This paper investigates the field oriented control (FOC) including the hysteresis-type PWM current regulator of such machine under flexible 3rd harmonic current injection. It is concluded that the sinusoidal current injection can be viewed as a special case of combined fundamental plus 3rd harmonic current injection with 0 percent of 3rd harmonic current. The flexible FOC control algorithm is designed and the developed model is confirmed by the simulation results in Matlab/Simulink environment. The complete strategy has been implemented on a digital signal processor based five-phase synchronous reluctance motor drive fabricated in our laboratory. The experimental results verify the developed flexible fundamental plus third harmonic FOC.