A Double-Side Self-Tuning LCC/S System Using a Variable Switched Capacitor Based on Parameter Recognition

In order to allow a wireless power transfer system to operate in a large-scale space where coupling coefficient has a significant variation due to different air gaps and displacements, a double-side self-tuning LCC/S system using a variable switched capacitor based on parameter recognition is proposed in this article. The main innovation is that the parameter recognition method is able to recognize both mutual inductance and double-side self-inductance with only rms value of sampling signal, phase information and auxiliary circuit being needless. Besides, based on the result of parameter recognition, the double-side use of variable switched capacitors and corresponding control strategy allow the proposed system to operate in a large-scale coupling space and help to improve system efficiency. Experiment results show parameters recognizing error less than 5%. A contrastive simulation verifies that variable switched capacitor can be equivalent to discrete capacitor with the same branch current in the proposed system. System feasibility is testified by a 700-W prototype and the effectiveness of the proposed system is demonstrated by a contrastive experiment with and without pulsewidth modulation (PWM) tuning, efficiency from dc to dc will increase about 3% with PWM tuning.