v 2 3 a v 3 3 b v 4 3 c and v 5 3 d each at 25 khz where v 4 is 90 u00b0 out of phase with v 3 and v 5 is 90 u00b0 out of place with v 2 this results in half the full power being provided to the coil as shown by the corresponding hatched lines for 0 u00b0 phase shift between v 2 and v 5 and v 3 and v 4 the power delivered to the coil will be maximum for 180 u00b0 phase shift between v 2 and v 5 and v 3 and v 4 the power will be zero this is shown in fig3 e where v 5 is shown with a 180 u00b0 phase shift from v 2 and in fig3 f where v 4 is shown with a 180 u00b0 phase shift from v 3 in both cases the pulses do not overlap so no power is delivered to the coil for intermediate values of the phase shift intermediate values of the coil 39 s maximum power will be obtained the operation of each series resonant converter is such that the operating frequency must be above the resonant frequency of the series resonant network otherwise excessive overstress will be applied to the switches the zero power condition may be achieved by switching off one like switch high side or low side of each converter by 180 u00b0 phase shift as described above or by switching off both devices of one of the pair of converters three state condition in case.