Digital Control Implementation for Coupling Independent IPT Systems without Communication

Inductive Power Transfer (IPT) offers a convenient solution for charging electric vehicles (EVs). By synchronizing the inverter output voltage with current, a parity-time (PT)-symmetric IPT system can operate in the PT-symmetric mode, ensuring that the transfer power and efficiency remain independent of misalignment. However, the inherent propagation delay in the control circuit can lead to synchronization failure, reducing the efficiency of the system. In this article, the influence of propagation delay are analyzed. The results show that propagation delay increases the switching loss of system, causes working frequency and output power drift. To address this issue, a novel digital control scheme is proposed to compensate for propagation delay without requiring any extra component. The theoretical analysis and the feasibility of the compensation control scheme are validated through experiments with an IPT prototype. The results show that the maximum efficiency can be achieved when the system is slightly over-compensated. Within a misalignment range of 0-160 mm, the fully-compensated system maintains nearly constant output power.