AC Network Analysis

Wireless power transfer for vehicle charging is inducted between two power pads. A power pad is combined with a tuned network (compensation network) to construct a resonant circuit for efficiently transmitting and receiving large quantities of energy. State-of-the-art wireless power transfer through inductive and magnetic resonances has numerous potential applications. A simple tuned network with a series or parallel inductor–capacitor (LC) circuit generates appropriate quality factors (Q factors) for various applications, such as induction cookers. Because of misalignment and a varying air gap between two power pads, specially tuned networks, such as inductor–capacitor–inductor and inductor–capacitor–capacitor networks, have been developed for various applications, such as electric vehicle charging. A tuned network with a high Q factor can achieve long-distance wireless energy transmission. A prototype system with magnetic resonance has been developed. This network can wirelessly transmit power of 60 W with an efficiency of approximately 40% over a distance of more than 2 m. A tuned network is constructed from an AC network, which contains inductors and capacitors. Different types of LC networks produce different effects. A series resistor–inductor–capacitor (RLC) resonant circuit can amplify voltage, whereas a parallel RLC resonant circuit can amplify current. This chapter describes the resonance principle, Q factor design, bandwidth, and selectivity of series and parallel RLC circuits.