Single-phase induction motor with an electronically controlled capacitor

A single-phase induction motor using an electronically controlled capacitor is described. The system uses a DC capacitor switched by a transistor H bridge. By proper control of the transistor switching, the circuit synthesizes a continuously variable capacitance in series with the auxiliary winding. The system could be used to replace standard single-phase motor capacitor configurations to provide improved machine performance. The basic system is described and compared with a normal capacitor-run motor. The effects of independent adjustments in several system parameters are considered, and the circuit device requirements are described. Both analog and digital simulations are used to carry out the analysis. Illustrations of some of the design flexibility inherent in the system are included