Compensation Method for Phase Distortion of Output Voltage in the Three-phase Triport UPS System

A new three-phase constant-voltage transformer is described. In this circuit, load unbalance and input voltage asymmetry can in principle be removed by ring-connected compensation windings. When the, triac of an Automatic Voltage Regulator (AVR) is controlled to give a constant output voltage, phase differences between the output voltages are kept at 120°. This principle can also be applied to conventional three-phase constant-voltage transformers with magnetic shunts and to three-phase Triport UPS systems.