Apparatus providing leading leg current sensing for control of full bridge power supply

A full bridge switching regulator comprising:

• switching elements in the arms of the full bridge switching regulator;
• means for cycling the switching elements on and off in staggered phases to provide zero voltage drop switching of the switching elements;
• means responsive to a current in an arm of a leading leg in the full bridge switching regulator for generating a sensed current signal;
• and
• means for blanking a trailing edge of the sensed current signal to generate a control waveform which is substantially zeroed during periods of conduction of freewheeling current through the arms of the leading leg.

A voltage and power regulator comprising:

• a full bridge switching network having two parallel legs connected between input terminals, each of the parallel legs having an upper switching element and a lower switching element and an output terminal between the upper and lower switching elements;
• current mode controller means responsive to a feedback control wave for supplying phase staggered control signals to opposed upper and lower switching elements of the two parallel legs, the phase staggered control signals providing for establishing one of the parallel legs as a leading leg in which the upper and lower switching elements conduct substantially unidirectional current having a duty cycle component and a free wheeling component and for establishing the other parallel leg as a lagging leg in which the upper and lower switching elements conduct current bidirectionally;
• a power output transformer having a primary winding connected between the output terminals;
• a current sensing transformer connected in series with the upper switching element of the leading leg and a second current sensing transformer connected in series with the lower switching element of the leading leg, whereby sensed signals are generated on a sensed signal output terminal;
• and
• means for generating the feedback control wave by summing the sensed signals from the leading leg and for blanking portions of the sensed signals corresponding to the freewheeling components of current conducted in the leading leg to produce clean peaks in the feedback control wave.