High-Performance PWM Frequency Changers

Besides the ability to change the frequency and amplitude of output voltages a high-performance frequency changer (FC) should produce sinusoidal output voltages and sinusoidal in-phase input currents and allow bidirectional power flow. The Venturini FC meets all these requirements but has some deficiencies which affect its practicality. Three kinds of improved FC's¿a new direct FC and its special applications, a current source FC, and a voltage source indirect FC¿which retain all good features of Venturini's FC and overcome its deficiencies are investigated. Their principles, features, and problems are discussed. New control laws and control circuits are proposed.