Optimal Regular-Sampled PWM Inverter Control Techniques

A survey of eight different advanced Regular-Sampled pulsewidth-modulation (PWM) strategies is presented and compared for three-phase inverters. The PWM strategies represent modifications of the basic Regular-Sampled technique and are designed to closely reproduce the "exact" switching angles and performance of the well-known Harmonic Elimination, Harmonic Minimization, Space Vector Modulation, High-Frequency, and Hysteresis Band PWM strategies. Each strategy is compared, and the advantages and disadvantages of each are emphasized in terms of complexity and implementation. Experimental and computer-aided design simulation results are presented to show the differences between the various strategies and to confirm the validity and accuracy of each of the techniques

List of Principle Symbols

Amplitude of th voltage harmonic.

Degree of pulse position modulation (PPM).

Inverter frequency (in Hertz).

Reference modulating function.

FR

Frequency ratio or pulse number.

Fundamental root-mean-square (rms) current.

Motor line current.

th harmonic rms current.

, ,

Integers.

Load inductance.

Modulation depth.

Number of switching angles per quarter cycle of the pulsewidth-modulation (PWM) waveform.

p.u.

Per unit; 1 p.u. corresponds to the maximum fundamental voltage produced by sinusoidal PWM before overmodulation.

,

Active pulse times.

,

Null pulse times.

Carrier time period.

th sampling position.

Sample period for sampled Hysteresis Band strategy.

Per-unit fundamental voltage.

, ,

Inverter line to center tap voltage.

Line voltage.

Phase voltage.

th switching angle.

,

Prepulse and postpulse switching times.

Polar angle of reference vector.

Fundamental frequency.

Carrier frequency.

Instantaneous angular frequency.