The cycloconverter operating on a circulating current free mode has many zero crossing points. If, however, an exact zero crossing point is not detected, the three phase unbalanced currents will flow in a motor.
In this thesis, the current feedback using a current reference wave is proposed to improve the problems of zero crossing detection, three phase unbalanced voltages / currents, and torque ripples.
To prevent the saturation of the air gap flux and keep the rated torque constant, the constant volts per hertz control including the IR drop compensation in the low frequency operating region is adopted. The PI controller is designed using the linearized model of the cycloconverter - induction motor system. Also, Z-80A single board computer has been used to implement the proposed scheme which results in the performance improvement of cycloconverter-fed induction motor speed control system.