Total digital ASIC control for an induction motor drive

The authors describe the operation and commissioning of a novel control strategy enabled by the use of a pair of digital ASIC devices. The speed of operation of such devices allows the control of the induction motor drive power devices to within 1° of the zero crossing of the 50 Hz waveform. In addition a reduction in size of the control equipment by 10:1 was achieved. The inclusion of a synchro-emulator within one of the ASICs eliminates the danger of destruction of the power devices during commissioning by generating the signals which must otherwise be derived from the three phase mains supply. The use of EDA tools to simulate both digital and power electronics sections of the drive allowed a high level of confidence in the speed and predictability of the prototype, which enabled rapid progress to the fully operational cycloconverter now under test. The production of the cycloconverter system described has provided an insight into the use of ASICs in this field which leads to a more general appraisal of their application to control systems for motor drives