Abstract:
Inductive Power Transfer (IPT) technology is a well-recognised technique for supplying power to a wide range of applications with no physical contacts. With the increasing concern over global climate change and rising costs of fossil fuel, bidirectional IPT systems are becoming increasing popular. Bidirectional IPT systems are attractive for applications such as Vehicle-to-Grid (V2G) and energy recovery systems, both of which allow the effective and efficient management of energy. However, bidirectional IPT technology is far from mature and many issues relating to design, modelling, and control remain to be solved. This thesis contributes to the solution of these issues by presenting both steady-state and state-space models of a bidirectional IPT system. The steady-state model is used to analyse the frequency behaviour of the system, while the state-space model is used to investigate the dynamic behaviour of the system. The interactions between various control variables and the degree of controllability of the system are analysed. From this analysis, a technique based on a genetic algorithm (GA) is proposed to determine the optimal parameters of a Proportional-Integral-Derivative (PID) controller for a bidirectional IPT system. Simulated and experimental results of a 1 kW prototype bidirectional IPT system are presented to demonstrate the effectiveness of the GA-tuned PID controller. A robust mechanism is essential to ensure that the power demanded by one converter is always met by the other converter without exceeding its power rating, and the GA-tuned controller is unable to guarantee this. Therefore, two new controllers are proposed that are based on varying the frequency of the system to regulate the power flow in both directions without a dedicated communication link. Simulated and experimental results of both controllers operating on a 1 kW prototype bidirectional IPT system are presented to show how the proposed controllers can successfully regulate the two-way power flow.