A single-phase AC phase controlled series voltage conditioner

The use of a series transformer and phase-controlled element as a voltage compensator and power conditioner is described. The system eliminates the need for a tapped transformer and associated switches, either electromechanical or static. The system described uses a standard two-winding transformer in which the primary winding is excited by an AC phase-controlled source, while the secondary is interfaced with the AC supply and the load. By series boost configuration, acceptable voltage compensation of the network and lower harmonic content is reported, including experimental results. The innovative design element of this boost circuit is the phase control of the AC series voltage used. A cost-effective solution is realized for the application of low voltage drop (e.g., long sag duration) and disturbances of a continuous repetitive nature that are typical of weak primary distribution systems. The harmonics generated, normally associated with phase-controlled circuitry, are no longer problematic. The described power conditioner can be used to regulate voltage for long duration voltage sags typical of weak distribution systems.