The effect of switching transitions on switched capacitor converters losses

The contribution of the rise and fall times of switches to the losses of Switched Capacitors Converters was evaluated by an approximate analysis applying the equivalent resistance concept. It was found that switch turn-on and turn-off durations increase the equivalent resistance of the converter and, consequently, the losses, except in the case of complete charge/discharge of the flying capacitors within the switching phase. Loss increase is related to the fact that during the current rise/fall state, the instantaneous losses are much higher than when the switch is in a constant `on´ state. Theoretical predictions were validated by full circuit simulations and experimental results. The present study integrates the switching losses into the generic equivalent resistance loss model, enabling the calculation and/or simulation of the total losses in switched capacitor converters.