Microprocessor implementation of PWM switching strategies

A major problem that arises in the inverter-fed induction motor drives is the inevitable introduction of harmonics into the alternating output voltage of the inverter. These harmonics, particularly the low order ones, produce harmful effects such as torque pulsations, excessive motor heating etc. Various techniques for controlling inverters have been proposed in order to reduce the harmonic content of the inverter output waveforms and to effect the voltage/frequency relationship for optimum utilisation of the motor. The latest forms of inverter control employ sinusoidal Pulse-Width-Modulation (PWM) for producing an AC supply with variable voltage and frequency. [Continues.]