Self-Tuning LCC Inverter Using PWM-Controlled Switched Capacitor for Inductive Wireless Power Transfer

• Published in: IEEE transactions on industrial electronics (1982) Vol. 66; no. 5; pp. 3983 - 3992
• Main Authors: Kim, Do-Hyeon, Ahn, Dukju
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: <named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX"> LCC</tex-math> </inline-formula> </named-content> resonant inverter; Capacitors; Coils; Compensation; Control theory; Feedback loops; Impedance; Inductance; Inverters; Magnetic materials; Magnetic shielding; Microcontrollers; P-n junctions; Power factor; Pulse duration modulation; Receivers; Self tuning; Switches; Switching; wireless power transfer; Wireless power transmission
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2018.2844796

Wireless power transfer with a self-tuning LCC inverter using pulsewidth modulation (PWM) controlled switched capacitor is proposed in this paper in order to compensate for the variations of Tx inductance. Usually, receivers contain magnetic and conductive materials for shielding and mechanical support. The inductance of the Tx coil is sensitive to the variation of Tx-Rx alignment because the interaction between the Tx coil and the Rx magnetic-conductive materials is also varied. It is shown that the detuning of the Tx inductance value exacerbates the losses in the LCC inverter. In the proposed method, the PWM duty ratio of a single capacitor adjusts the effective output impedance of the LCC inverter. The PWM feedback loop is designed such that the power factor and the real-part impedance of the LCC inverter are maximized. The PWM switch is turned on at zero voltage and turned off with low dv / dt , minimizing switching losses. Such a soft-switching tunable capacitor can handle higher power compared to the traditional hard-switching capacitor, p-n junction capacitor, or an analog IC capacitor. Another advantage of the proposed technique is the continuity in achievable capacitance value using only one capacitor. The feedback can be fully implemented by analog components, obviating the necessity of digital samplings, ADC/DACs, and microcontrollers. The power of 54 W is transferred at 76.6% and 60.7% with and without the proposed method, respectively.