a two quadrant power modulator using bi - directional and uni - directional flyback converters in which output waveshape is determined by the modulation of the pulse repetition rate and width . the output voltage is equal to the square root of the driving function . a large number of converters may be paralleled with sequential switching to raise the output power and raise the output ripple frequency , thereby simplifying filtering . output voltage is constant with varying load condition irrespective of the reactive or non - linear nature of the load . a two quadrant power modulator using flyback converters to generate a time varying voltage . dynamic regulation and low output impedance are achieved without use of closed loop control . input voltage is not distorted by reactive and / or non - linear loads .