Higher Efficiency Drive for Fluid Treatments

Abstract

In the paper is proposed a converter topology to be employed when the dynamic performances, required by the mechanical load, are not so pressing, but, on the contrary, good energetic motor performances are desired. Typical applications are the for all the drives devoted to fluid treatments (pumps, fans, etc.), where the motor is supplied by a VSI (Voltage Source Inverter), without current feedback. The proposed converter is based on a variable output voltage ac/dc converter followed by a unity modulation index PWM (Pulse Width Modulated) inverter. Experimental measurements of the efficiency, with motor supplied by the proposed converter or by a standard converter, are presented and compared. In addition, the possibility to reduce the supply voltage, at speed lower than the rated, is analysed. The experimental results confirms the better motor efficiency that can be reached with regulated dc bus voltage, unity modulation index, PWM-VSI inverters.