Microprocessor implementation of new optimal PWM switching strategies

The microprocessor implementation of new optimal PWM switching strategies are presented, and the special features, characteristics and advantages of various microprocessor configurations are demonstrated. All the necessary microprocessor hardware/software techniques and algorithms required to implement and generate the new optimal PWM strategy on-line and in real time are developed in detail, and demonstrated using practical results from an experimental microprocessor-controlled PWM inverter induction motor drive system. The techniques developed and presented in the paper are readily applicable to other currently available microprocessors, with minor modifications to reflect the special features of the particular microprocessor used. The presentation is based on the design of a typical PWM operating strategy for a variable speed drive system, which covers the complete voltage/frequency operating range up to, and including, quasisquare wave operation, with minimised total harmonic current distortion (THD). In addition to drive applications, the optimal PWM techniques and microprocessor implementations can be used for uninterruptible power supplies and static frequency changer systems.