A SURVEY OF DELTA-MODULATION TECHNIQUES CHARACTERISTIC AND SUB HARMONIC ELIMINATION FOR VSI

The PWM delta modulation (DM) is an established alternative to the sta ndard PWM techniques for providing gating signals to the static invert ers. It's inherent characteristics of constant volts/Hertz control wit hout feedback complexity makes it an unique one. This paper discusses the classic and the advanced DM and classifies them according to the n eed of a particular user. Additionally, it gives some simple yet effec tive techniques to overcome some of the inherent problems in DM, i.e. sub/partial harmonics and characteristic lower-order harmonics. Key wa veforms are confirmed with those from 'circuitry' constructed in SPICE environment designed to drive a PWM VSI that provides constant v/f co ntrol and near-sinusoidal motor current.