Digital Design of 12-Phase Cycloconverter Based on DSP with CPLD

Recently, analog control is replaced by digital control in cycloconverter-fed adjustable speed drives. However, cycloconverter has many thyristors and control signals. Multi-CPU has to be adopted for its complexity. In this paper, main circuit is redesigned due to multi-phase. An interstar winding method is used in insulating transformers to supply 12-phase power. A 12-phase cycloconverter based on DSP with CPLD is proposed. The inner structure of CPLD is designed especially to generate heavy firing pulses composed of control signal distributor, counting time delay and pulses widening, and pulses distribution parts. Simulation and experiment results denote that a digital cycloconverter based on DSP with CPLD has the convenience of design and debugging, and has preferable control performance and high reliability