Three to single-phase high-power quality switch-mode cycloconverter

A new switch mode power supply-based cycloconverter circuit has been presented. Proposed circuit configuration offers conspicuous advantages over traditional 12-SCR (silicon controlled rectifier) cycloconverter. It facilitates output voltage and output frequency to be either greater or smaller than the input voltage and input frequency. The circuit operates with reduced total harmonic distortion (below 15%), improved efficiency (above 80%) and highly improved power factor (above 95%) for both resistive and inductive load. Moreover, only 4 insulated gate bipolar transistors (IGBTs) are required instead of 12 SCR. Reduced number of switches increases circuit longevity while reducing pulse generation complexity. As voltage driven switch is being used, it can be operated easily using digital IC or microcontrollers. In contrary to traditional cycloconverter, input AC voltage is made unidirectional by employing a full bridge three phase uncontrolled diode bridge rectifier. One positive and one negative converter differentially connected across load ensure proper output voltage and frequency by utilising appropriate switching pulse. As SMPS topology has been incorporated, the circuit can operate in four quadrant mode at voltage-frequency plane. Integration of fuzzy logic control provides better stability and grip over output voltage and frequency. Meticulous details of operation and circuit performance are presented in this study.