High Performance Control of AC Drives with Matlab / Simulink Models

3.1 Preliminary Remarks

The Pulse Width Modulation (PWM) technique is applied in the inverter (DC/AC converter) to output an AC waveform with variable voltage and variable frequency for use in mostly variable speed motor drives. The input to the inverter is DC, obtained from either a controlled or uncontrolled rectifier. Hence, an inverter is a two-stage power converter that transforms first the grid AC to DC and then DC to AC. PWM and the control of the Power Electronic DC-AC converter has attracted much attention in the last three decades. Research is still active in this area and several schemes have been suggested in the literature [1–6]. The basic idea is to modulate the duration of the pulses or duty ratio in order to achieve controlled voltage/current/power and frequency, satisfying the criteria of equal area. The implementation of the complex PWM algorithms have been made easier due to the advent of fast digital signal processors, microcontrollers, and Field Programmable Gate Arrays (FPGA). The PWM is the basic energy processing technique used in Power Electronic converters initially implemented with the analog technology using discrete electronic components. Nowadays, they are digitally implemented through modern signal processing devices. This chapter gives an overview of the PWM techniques based on the most basic and classical sinusoidal carrier-based scheme to modern space vector PWM (SVPWM). The literature shows an implicit relationship between the sinusoidal carrier-based ...