A bidirectional AC series voltage regulator that regulates an output AC voltage level regardless of the varying AC input voltage utilizing high frequency series inductors that only process a proportion of the total output power. The AC series voltage regulator detects the power inductor current direction data signal and can generate power inductor current direction data signals for its control to determine the AC input voltage polarity at all time; wherein the determination of the AC input voltage polarity is unambiguous during the AC input voltage zero crossover and near zero points; and wherein the determination of the AC input voltage polarity allows normal switching sequence of the AC bidirectional switches during the AC input voltage zero crossover and near zero points to prevent power “shoot-through.”