Abstract
Capacitive power transfer (CPT) technique possesses the advantages of safety, isolation, low cost, and insensitivity to conductive barriers. To charge lithium-ion batteries, CPT should possess the output profile consisting of first constant current (CC) output and later constant voltage (CV) output. To fulfill the output profile, many power switches or compensation components are added in the CPT circuit, which is not expected due to the bulky size and additional losses. To reduce the redundancy of the CPT system, an Lx-PS CPT circuit with only five compensation components is proposed in this paper. After a systematic analysis and a parameter design procedure, the proposed CPT circuit can realize input ZPA at both CC and CV modes. In addition, the output current at CC mode and the output voltage at CV mode are all adjustable based on the charging demands of different loads. Finally, simulations are done to prove the analysis in this paper. Compared to previous research, the CPT circuit proposed in this paper can not only achieve the charging demands of lithium-ion batteries, but also reduce the redundancy of the whole system.
Highlights
capacitive power transfer (CPT) circuit can realize input zero phase angle (ZPA) at both constant current (CC) and constant voltage (CV) modes
CC mode and the output voltage at CV mode are all adjustable based on the charging demands of different loads
Since the equivalent impedance of a load may change during the charging process, a wireless power transfer (WPT) charger should realize the load-required constant current (CC) or constant voltage (CV) output
Summary
The relationship between the six-capacitor model and the Π-type model satisfies (C +C )(C +C24 ). The Π-type model together with Cex and Cex can be further converted to a T-type model as shown in Figure 2b where capacitors CA , CB , and CC satisfy the equation: CA =. Taking the capacitive coupler and the external capacitors as a whole, CPT has four basic compensation circuits as shown in Figure 4 where L1 and L2 are compensation inductors and the capacitive coupler is equivalent to a T-type model.
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