Inverters are used to create single or polyphase AC voltages from a DC supply. In the class of polyphase inverters, three-phase inverters are by far the largest group. A very large number of inverters are used for adjustable speed motor drives. The typical inverter for this application is a “hard-switched” voltage source inverter producing pulsewidth modulated (PWM) signals with a sinusoidal fundamental. Recently research has shown detrimental effects on the windings and the bearings resulting from unfiltered PWM waveforms and recommends the use of filters.
According to the type of ac output waveform, these topologies can be considered as voltage source inverters (VSIs), where the independently controlled ac output is a voltage waveform. These structures are the most widely used because they naturally behave as voltage sources as required by many industrial applications.
The vital role of voltage source inverters for the high power AC motor drives has been described. The concept of pulse width modulation and different PWM Techniques has been emphasized. The proposed switched mode PWM inverter has been discussed in detail, which is one among the various types of VSI's. The concept of PWM current ripples in the output current, its variation due to change in high frequency clearly shows that the use of filters becomes mandatory in order to reduce it.
BOS, APOD, DSPs, MATLAB
