Active Class E Rectifier with Controlled Output Voltage for Megahertz Wireless Power Transfer

Wireless power transfer (WPT) is desirable for its elimination of direct electrical contact, i.e., safer charing solution, water-proof and dust-proof capability, sterile environment application, etc. However, the variable working conditions, such as the coupling coil relative position, can always lead to output voltage fluctuations. Therefore, output voltage regulation is especially necessary for the charging of electronic terminals. This paper proposes an active Class E rectifier that can perform both high frequency rectification and output voltage regulation. The basic working principle of the active rectifier is explained and design guidance is provided. Both simulations and experiments are done to demonstrate the proposed design and desired performance. With the duty cycle control of the active rectifier, an constant output voltage can be maintained under a varying coupling coefficients and final DC load.