JAJU732C June 2019 – July 2022
Figure 2-16 shows that the soft switching range of the converter is maximized when the turns ratio is chosen such that the primary voltage is equal to the reflected secondary voltage. In this condition, the voltage transfer ratio is equal to unity, and all of the switches of the primary and secondary side experience soft switching under all conditions. In practice, the total capacitance of the switching node must be discharged by currents i1 and i2 as given by Equation 7 and Equation 8 within the specified dead time so that switches turn on at zero voltage. For light load conditions where there is not sufficient inductive stored energy to discharge the capacitive energy of the MOSFETs, the dead time could be increased in accordance with current so as to affect ZVS.