A novel controllable reactor of transformer type

With the primary and a secondary winding ports leading out, a multi-winding transformer with air-gapped core can be regarded as a linear two-port network. Adjust the current relationships between the ports, the input impedance of the primary winding can be a variable reactance; change the short-circuit conditions of other secondary windings, the reactance of primary winding will move in deferent intervals. With proper designing, these intervals can be jointed, so the reactance can be regulated continuously in a wide area. The controllable reactor based on this principle, whose power rating is determined by short-circuit capacity mainly, can adopt the low-rating pulse-width-modulation (PWM) inverters to accomplish the port adjusting.