flows from the resonant load through switch m 2 and back to the return ground to the resonant load switch m 2 remains on from 0 to u03b2 and current ib flows from the return ground of the resonant load through switch m 2 and back to the resonant load the cycle then repeats itself with switch m 1 being turned on again fig1 illustrates the corresponding on and off times of switches m 1 m 2 and m 3 during one period of a typical resonant load current when u03b2 lt 0 switch m 1 turns on during the angle from 0 to u03b1 1 degrees current ia flows from vin through switch m 1 through the resonant load and back to the return ground to voltage vin switch m 1 is then turned off and switch m 2 is turned on during the angle from u03b1 1 to 180 degrees current ib flows from the return ground of the resonant load through the body diode of switch m 2 and back to the resonant load switch m 2 is then turned off and switch m 3 is turned on from 180 degrees to 360 degrees current ie flows from the resonant load through switch m 3 through capacitor cbus and returns to ground at the resonant load the cycle then repeats itself with switch m 1 being turned on again as conduction angles u03b1 and u03b2 change during the low frequency cycle of the line input voltage i e as shown in fig7 the conduction angles of the switches are controlled so that the average line input current is sinusoidal and in phase with.