Design of efficient optimized wireless power transfer system
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ORIGINAL ARTICLE
Design of efficient optimized wireless power transfer system Qian Wu1 · Lei Wang1 · Dongqian Ju1 · Chang Chen1 · Changyuan Chang1 Received: 15 January 2020 / Revised: 15 May 2020 / Accepted: 18 May 2020 © The Korean Institute of Power Electronics 2020
Abstract To balance the output stability and maximum efficiency of a system, an efficiency optimization method based on adaptive frequency control is proposed. In this paper, load transmission is carried out using a DC–DC converter at the receiving end. When the load changes, controlling the rectified output voltage is carried out to realize the maximum efficiency point tracking. Meanwhile, the duty cycle of the rear stage DC–DC converter is changed to keep the output voltage constant. The sampled rectified voltage is compared with the estimated value and the resulting error data are sent to the system transmitter through ASK modulation wireless communication. Then the transmitter demodulation communication information through PID algorithm control is used to achieve the frequency of the adaptive adjustment. The feasibility of the proposed method has been verified by the simulation and experimental results. When the output voltage is 5 V, the constant voltage accuracy is within ± 1%, the maximum efficiency is up to 79.2%, and the dynamic response time is only 160 ms. Keywords Adaptive frequency control · Maximum efficiency point tracking (MEPT) · DC–DC converter · Wireless power transfer (WPT)
1 Introduction It is usually desired that WPT systems achieve maximum efficiency while providing a constant output voltage. However, in open-loop WPT systems, the output voltage and efficiency vary with the load and coupling coefficient. In addition, the load and coupling coefficients are also affected by the environment. To improve efficiency and provide a constant output voltage, different methods have been reported. The authors of [1] proposed a method to change the phase shift and rectified voltage of the active rectifier through impedance matching to improve efficiency and output power. However, for different values of the load impedance, the phase angle of the rectifier switch needs to be calculated and stored to match the impedance optimization value. In addition, when the load and coupling coefficients change, the efficiency decreases. Perturbation and observation (P&O) algorithms for MEPT were proposed in [3]. There are a number of differences among these methods. In [2], a pre-regulation DC–DC in the transmitter (Tx) is used to stabilize the * Changyuan Chang [email protected] 1
School of Microelectronics, Southeast University, Nanjing, China
output voltage, and a post-regulation DC–DC in the receiver (Rx) is used to optimize the load, which increases the system complexity. In [4], a post-stage cascaded boost–buck converter is used. Although the method in [5] can achieve output stability and maximum efficiency point tracking, there is a problem since the searching process of the P&O algorithm to find the optimization value is long, which resul
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