A Double-T-Type Compensation Network and Its Tuning Method for IPT System

This paper presents a new design strategy for an S-LCC-type compensation network in inductive power transfer (IPT) systems to achieve constant voltage output. It was found that four resonant elements (three capacitors and one inductor) can compose two symmetric T-type resonant tanks, which is well-known for its impedance transformation characteristic and reciprocity between voltage source and current source. A simplified analytical technique is used to calculate the voltage gain and parameters for each resonant element. Besides, the proposed tuning method for an S-LCC network has negligible response to high-order harmonics, allowing wide range of output voltage regulation and easy implementation of zero voltage switching. To aid designers in practical design and circuit debugging, sensitivity of one critical resonant element is analyzed. To verify the analysis, a 165 W prototype with 50 mm gap and fixed voltage transfer ratio was fabricated and tested. An overall 90% efficiency was achieved from dc 70 V input to dc 30 V output.