A two-phase dual-zero vector RCD-PWM (DZRCD) technique

A two-phase DZRCD (dual-zero vector RCD) technique is proposed to solve the problems of conventional two-phase RCD-PWM (random centered distribution PWM) which the discrete spectra in case of high modulation index (M) does not reduced considerably. In the proposed DZRCD technique, zero vector is selected as V(1 1 1) in case of M/spl ges/0.8. Also, zero vector is selected as V(0 0 0) if modulation index<0.8. For the implementation of the proposed method, a 16-bit micro-controller SAB C167 was used and the experiments were conducted with the 1.5 kW induction motor under no load condition. The experimental results show that the voltage and current harmonics are spread to a wide band area and that the acoustic switching noise is reduced by the proposed method.