The resonant frequency will be changed, and the load voltage will be unstable with misalignments and load variations in wireless power transfer (WPT) systems. In this paper, the expression for solving the resonant frequency is obtained. The calculation result shows that the resonant frequency is changed with the changes of misalignment and load. First, a new control method of frequency tracking with a Fuzzy proportional-integral (PI) compound controller is proposed, which can eliminate the overshoot of resonant frequency and improve the speed of frequency tracking. Second, a mixed-modulation method for adjusting frequency and voltage is further proposed, which is mainly composed of the selection algorithm of the duty cycle, the phase-shifting angle calculation, and the method of frequency tracking based on the Fuzzy PI compound controller. The appropriate duty cycle is obtained by the selection algorithm of the duty cycle to adjust the load voltage. The phase-shifting angles of different duty cycles are obtained by the phase-shifting angle calculation, which play a role in adjusting the resonant frequency by combining the Fuzzy PI compound controller. The proposed method can not only make the system keep a resonant state, but also make the output voltage across the load stable. A WPT system via magnetically coupled resonance is designed. Calculation and simulation results validating the superiority of the proposed method are given.
2. Correia, R. and N. B. Carvalho, "Ultrafast backscatter modulator with low-power consumption and wireless power transmission capabilities," IEEE Microwave and Wireless Components Letters, Vol. 27, No. 12, 1152-1154, Dec. 2017.
3. Zhang, Y. and T. Lu, "Selective wireless power transfer to multiple loads using receivers of different resonant frequencies," IEEE Transactions on Power Electronics, Vol. 30, No. 11, 6001-6005, Nov. 2015.
4. Jin, K. and W. Zhou, "Wireless laser power transmission: A review of recent progress," Transactions on Power Electronics, Vol. 34, No. 4, 3842-3859, Apr. 2019.
5. Wang, Z. and W. Xu, "Joint trajectory optimization and user scheduling for rotary-wing UAV-enabled wireless powered communication networks," IEEE Access, Vol. 7, 181369-181380, Dec. 2019.
6. Liu, C. and C. Jiang, "An effective sandwiched wireless power transfer system for charging implantable cardiac pacemaker," IEEE Transactions on Industrial Electronics, Vol. 66, No. 5, 4108-4117, May 2019.
7. Yoshida, S. and N. Hasegawa, "Experimental demonstration of microwave power transmission and wireless communication within a prototype reusable spacecraft," IEEE Microwave and Wireless Components Letters, Vol. 25, No. 8, 556-558, Aug. 2015.
8. Mastri, F. and A. Costanzo, "Coupling-independent wireless power transfer," IEEE Microwave and Wireless Components Letters, Vol. 26, No. 3, 222-224, Mar. 2016.
9. Najjarzadegan, M. and I. Ghotbi, "Improved wireless power transfer efficiency using reactively terminated resonators," IEEE Antennas and Wireless Propagation Letters, Vol. 17, No. 5, 803-807, May 2018.
10. Hui, S. Y. R. and W. Zhong, "A critical review of recent progress in mid-range wireless power transfer," IEEE Transactions on Power Electronics, Vol. 29, No. 9, 4500-4511, Sept. 2014.
11. Lim, Y. and H. Tang, "An adaptive impedance-matching network based on a novel capacitor matrix for wireless power transfer," IEEE Transactions on Power Electronics, Vol. 29, No. 8, 4403-4413, Aug. 2014.
12. Teck, C. B. and I. Takehiko, "Basic study of improving efficiency of wireless power transfer via magnetic resonance coupling based on impedance matching," IEEE International Symposium on Industrial Electronics, 2011-2016, Nov. 2010.
13. Trevor, S. B. and R. Nicholas, "Antenna impedance matching for maximum power transfer in wireless sensor networks," IEEE Sensors, 916-919, Oct. 2009.
14. Kim, N. Y. and K. Y. Kim, "Adaptive frequency with power-level tracking system for efficient magnetic resonance wireless power transfer," Electronics Letters, Vol. 48, No. 8, 452, Mar. 2012.
15. Lim, Y. and H. Tang, "An adaptive impedance-matching network based on a novel capacitor matrix for wireless power transfer," IEEE Transactions on Power Electronics, Vol. 29, No. 8, 4403-4413, Aug. 2014.
16. Xu, L. and Q. Chen, "Self-oscillating contactless resonant converter with power transfer and current sensing integrated transformer," IEEE Energy Conversion Congress and Exposition (ECCE), 4539-4543, Sept. 2015.
17. Xu, L. and Q. Chen, "Self-oscillating resonant converter with contactless power transfer and integrated current sensing transformer," IEEE Transactions on Power Electronics, Vol. 32, No. 6, 4839-4851, Jun. 2017.
18. Xie, K. and A. Huang, "Half-cycle resonance tracking for inductively coupled wireless power transmission system," IEEE Transactions on Power Electronics, Vol. 33, No. 3, 2668-2679, Mar. 2018.
19. Fu, B. Z. W. and D. Qiu, "Study on frequency-tracking wireless power transfer system by resonant coupling," IEEE 6th Int. Power Electronics and Motion Control Conference, 2658-2663, May 2009.
20. Wang, J. and Z. Zhu, "PLL-based self-adaptive resonance tuning for a wireless-powered potentiometer," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 60, No. 7, 392-396, Jul. 2013.
21. Xie, K. and A. F. Huang, "Modular high-voltage bias generator powered by dual-looped self-adaptive wireless power transmission," Rev. Sci. Instrum., Vol. 86, No. 4, 044707, Apr. 2015.
22. Gati, E. and G. Kampitsis, "Variable frequency controller for inductive power transfer in dynamic conditions," IEEE Transactions on Power Electronics, Vol. 32, No. 2, 1684-1696, Feb. 2017.
23. Lu, F. and H. Zhang, "A dual-coupled LCC-compensated IPT system to improve misalignment performance," IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW), 1-8, May 2017.
24. Yang, J. and X. Zhang, "An LCC-SP compensated inductive power transfer system and design considerations for enhancing misalignment tolerance," IEEE Access, 1, Oct. 2020.
25. Lee, C. K. and W. X. Zhong, "Effects of magnetic coupling of nonadjacent resonators on wireless power domino-resonator systems," IEEE Transactions on Power Electronics, Vol. 27, No. 4, 1905-1916, Apr. 2012.
26. Zhang, Y. and Z. Yan, "A high-power wireless charging system using LCL-N topology to achieve a compact and low-cost receiver," IEEE Transactions on Power Electronics, Vol. 35, No. 1, 131-137, May 2019.
27. Ren, Y., et al., "Electromagnetic, mechanical and thermal performance analysis of the CFETR magnet system," Nuclear Fusion, Vol. 55, 093002, 2015.
28. Ren, Y., "Magnetic force calculation between misaligned coils for a superconducting magnet," IEEE Transactions on Applied Superconductivity, Vol. 20, No. 6, 2350-2353, 2010.
29. Ren, Y., et al., "Mechanical stability of superconducting magnet with epoxy-impregnated," Journal of Superconductivity and Novel Magnetism, Vol. 23, No. 8, 1589-1593, 2010.
30. Hsueh, Y. and S. Su, "Decomposed fuzzy systems and their application in direct adaptive fuzzy control," IEEE Transactions on Cybernetics, Vol. 44, No. 10, 1772-1783, Oct. 2014.
31. Wang, N. N. and M. J. Er, "Direct adaptive fuzzy tracking control of marine vehicles with fully unknown parametric dynamics and uncertainties," IEEE Transactions on Control Systems Technology, Vol. 24, No. 5, 1845-1852, Sept. 2016.