Multi-level Staircase Signal Based Quadrature Phase Detection for Fundamental Power Angle Acquisition of BIPT Systems

Bidirectional inductive power transfer (BIPT) allows power to be transferred bidirectionally between two electrical systems. In BIPT systems, phase synchronization of the AC port excitation voltage with the resonant current is essential for a stable transmission of power, which requires the detection of the phase difference between the fundamental components of the voltage and current, which is the fundamental power angle. To detect the fundamental power angle, this paper proposes a quadrature phase detection based fundamental power angle acquisition method with multi-level staircase signal as multiplicand. By using the multi-level staircase signal with eliminated low order harmonics, the phase detection error caused by the resonant current harmonics can be reduced. The basic characteristics of the BIPT system as well as the working principle of the quadrature phase detection method are introduced. The impact of harmonics on the fundamental power angle detection result is analyzed. The low order harmonics elimination parameters of the multi-level staircase signal are calculated. And the method to implement the multiplication of the resonant current with the equivalent multi-level staircase signal without using any multiplier, is proposed. Simulations are performed with the proposed method under various conditions, which show the improvement of the accuracy of the phase detection result with the proposed method.