An active power filter with saturable cores

We present a method to realize pulse width modulated wave for power applications by using cores as a control unit. This core unit is made of η cores with four windings. Each core is fed a different amount of magneto motive force to decide the order of flux varying operation. Power transistors are switched by PWM voltage made of the core unit mentioned above. This switching action eliminates the harmonics lower than n-th from supplied squarewave source. This output is followed by a simple lowpass filter and becomes sinusoidal wave. In temperature stability, reliability and power consumption, this method is superior to the conventional PWM method by comparing sinusoidal wave to triangular wave or using a digital circuit, because the number of constructing elements is less than that in conventional method.