No. Sokal et R. Redl, CONTROL ALGORITHMS AND CIRCUIT DESIGNS FOR OPTIMAL FLYBACK-CHARGING OF AN ENERGY-STORAGE CAPACITOR (EG FOR FLASH LAMP OR DEFIBRILLATOR), IEEE transactions on power electronics, 12(5), 1997, pp. 885-894
A flyback type of transformer-coupled dc/dc converter supplies a train
of current pulses to charge an energy-storage capacitor to a desired
high voltage, converting input de power obtained from a lower voltage
de source, The energy-storage capacitor is charged to a specified volt
age within a specified time with minimum peak and rms currents in the
transistor, the rectifier diode, the transformer windings, and the de
power source, minimizing the i(2)R losses, This is done by generating
1) energy-storage current pulses in the power transistor and the trans
former primary winding in which the current increment from the beginni
ng to the end of a pulse is only a small fraction of the final (peak)
value and 2) energy-delivery flyback current pulses in the capacitor a
nd the transformer secondary winding in which the current decrement fr
om the beginning to the end of a pulse is only a small fraction of the
initial (peak) value, Recommended methods are: 1) hysteretic current-
mode control with current sensing in both transformer windings; 2) pea
k-current-commanding current-mode control with switching frequency or
transistor-nonconducting time varying in a prescribed way during the c
harging; or 3) valley-current-commanding current-mode control with swi
tching frequency or transistor-conducting time varying in a prescribed
way during the charging, Compared with one nonoptimal method, peak cu
rrents are reduced by a factor of about 2 and i(2)R power losses are r
educed by a factor of about 1.33.