Improving analysis of frequential performance of power components: a method of measuring instantaneous electrical stresses

The authors describe apparatus which acquires precise instantaneous values of voltage and current in a converter which is actually working and compute instantaneous power, conduction and commutation power losses of the switches. Acquiring these values means using specific sensors. Measurement computation allows metrological imperfections to be compensated. Performance and potential of this apparatus are illustrated by studying waveforms of a GTO thyristor buck converter. The usual method of computing the average power dissipated consists in adding switching losses and conduction losses of a stationary phenomenon. The validity of the method and the suggested device precision have been checked on the basis of a precise energy evaluation of equality between average electric and thermal powers.