Circuit Theory Analysis of Parity-Time-symmetric Wireless Power Transfer System

Abstract

Wireless power transfer (WPT) technology reduces the risks brought by connection between electrical equipment and power source, it has been widely used in various fields in recent years. To overcome issues of low transfer efficiency and poor robustness when coupling coefficient varies, a WPT system based on parity-time (PT) symmetric circuit is proposed, which consists of two RLC oscillators. The system state equation is obtained by circuit theory, then be analyzed to derive the system resonance frequency, transmission efficiency, and phase difference between Tx and Rx. A simulation based on PSIM is established to verify the theoretical derivation of transmission characteristics. The simulation results illustrate that the resonance frequency of the WPT system is adjusted automatically in the strong coupling region when the coupling coefficient changes, the output voltage across the load resistance always equals source voltage on the transmitter. Compared with the non-parity-time symmetric system, PT-symmetric WPT system could achieve higher transfer efficiency over a longer distance, this scheme can transfer power with constant efficiency of over 80% in a certain region. A set of simulations with variation load resistance are considered to verify the system robustness. All results are consistent with theoretical derivation and analysis.Wireless power transfer (WPT) technology reduces the risks brought by connection between electrical equipment and power source, it has been widely used in various fields in recent years. To overcome issues of low transfer efficiency and poor robustness when coupling coefficient varies, a WPT system based on parity-time (PT) symmetric circuit is proposed, which consists of two RLC oscillators. The system state equation is obtained by circuit theory, then be analyzed to derive the system resonance frequency, transmission efficiency, and phase difference between Tx and Rx. A simulation based on PSIM is established to verify the theoretical derivation of transmission characteristics. The simulation results illustrate that the resonance frequency of the WPT system is adjusted automatically in the strong coupling region when the coupling coefficient changes, the output voltage across the load resistance always equals source voltage on the transmitter. Compared with the non-parity-time symmetric system, PT-symmetric WPT system could achieve higher transfer efficiency over a longer distance, this scheme can transfer power with constant efficiency of over 80% in a certain region. A set of simulations with variation load resistance are considered to verify the system robustness. All results are consistent with theoretical derivation and analysis.