Induction motor performance when fed from single to three phase converters

The most popular single-to-three-phase converter consists of a capacitor connected between the motor´s third phase and either the live or neutral of the single-phase supply. Proper voltage balance at any one given operating point is obtainable with the autotransformer-capacitor converter (ACC), while proper balance over the entire operating range is obtainable with a variable-inductor-variable-capacitor converter (LCC). The appropriate vector diagrams of the above-mentioned converters are developed to provide insight into their operation. An assessment of the derating necessary in the presence of unbalanced voltages and currents is presented. A technique for the measurement of the negative sequence voltage is discussed. Measured results for the case when an induction machine starts directly off a three-phase supply and off the above converters are included.<>