A new 'slope-modulated' PWM strategy for implementation in a single chip gate array

Abstract

The task of designing a gate-array-based, dedicated, three-phase PWM (pulsewidth-modulated) modulator for electric drive control is addressed. A novel slope-modulated PWM strategy is presented. Sine-wave and square-wave signal references, under several operating modes, are used to demonstrate the modulation properties. Performance parameters, such as reliable inverter switching, minimum on/off times, peak inverter switching frequency, total harmonic distortion, and pulse dropping are described. The modulator is shown to generate high-resolution PWM waveforms, with excellent performance when a variable-frequency ratio strategy is used with a sine-wave reference signal. The square-wave reference signal uses less complex digital circuitry, with a reliable operation of the inverter bridge.<>