Performance Analysis of a Single-Phase Source Feeding Low Power Three-Phase Induction Motors

Abstract

The availability of single-phase AC sources in domestic applications makes the use of this low power source is recommended for feeding three phase induction motors, instead of the unavailable balanced three phase supply. Electric motors operating from single-phase power supply are widely used to provide the mechanical power for many domestic and light industrial types of equipment. The straightforward solution is to use an inverter to convert from single-phase supply to a three-phase supply via proper power electronic schemes. In this paper a shift capacitor with the rated voltage of the motor is inserted in one phase to ensure a specified phase shift to fulfill a relatively balanced operation of the motor. The verification of this system is implemented with a complete analysis of the motor driven under unbalanced cases during different operation conditions. The existence of the capacitor imposes extra harmonics and deterioration of the motor performance. A low pass passive filter is used for power factor correction and consequently improves for some extent the unbalance status of the supply. The system is simulated and verified experimentally with proper mitigation of harmonics and power factor improvement. The advantage of using this implementation is the lower cart in addition to the availability of application in a specified operating point, which leads to lower the overall cost. The proposed implementation performs operation of the three- phase induction motor from a modified balanced system in the rum status, keeping in mind the protection of the motor at starting, since it is subjected to an unbalanced supply in this case. The use of the shift capacitor as a part of the low pass filter improves the motor performance.