Measurement of instantaneous losses in switching power devices

A novel technique is proposed for measuring instantaneous power and energy losses in static switching devices during the different operating intervals (turn-on delay, rise time, on-state, turn-off delay, full time, and off-state) of a switching cycle. To this end, a system for measuring voltages and currents is used, based on sampling at 200 Ms/s for data acquisition. The data are then transferred to a personal computer (PC), where they are conditioned and processed to obtain the instantaneous values and the average values of power losses for any desired duty cycle or single impulse. It is concluded that the high-speed digital acquisitions of voltage and current data along with the possibility of automatically processing on a PC allows the calculation of the losses during the fast switching transients with a greater degree of accuracy and detail than that afforded by classical techniques