Digital measurement of ac voltage, ac current and phase angle of measurement signal

摘要

The zero crossing of the measurement signal (U) is detected by superimposing a d.c. voltage (Uref) as a reference voltage onto the actual measurement signal . The zero crossing of the measurement signal is detected in relation to the potential of the reference voltage. A further voltage (Uref*) is generated which continuously increases during the positive half cycle of the measurement signal and continuously decreases during the negative half cycle of the measurement signal. This further voltage is superimposed on the reference voltage and hence onto the measurement signal.