An active power filter with saturable cores

The paper presents a method of realizing pulse width modulated wave for power applications using cores as a control unit. The unit is made up of cores with four windings, with each core fed a different amount of magnetomotive force to determine the order of the flux varying operation. Power transistors are switched by PWM voltage provided by the core unit; this switching action eliminates the harmonics lower than the n-th from the squarewave source. This method is superior to the conventional PWM method in temperature stability, reliability, and power consumption because of a smaller number of construction elements.