Difference in geometrically optimized wireless power transmission systems with SS and SP compensations

Geometric optimization of the coils takes important part in the design of the inductive powering systems. This paper presents the evaluation of the geometry of the coils integrated in the two different inductive powering systems, with series-series (SS) and series-parallel (SP) compensation circuits. The both systems are designed in order to provide 1±0.1 W to the 20 Ohm load at the distance equal to the 10 mm and in the presence of lateral displacements in the range 0…30 mm. Operating frequency was 880 kHz. The receiving coils were identical for the both systems. The transmitting coils have the same inner and outer radii, 30 mm and 27 mm respectively. At the same time, the turns numbers differs notably. It was significantly higher for SS system (16 instead of 5). Consequently, the transmitting coil for the SS-system have much higher self-inductance. It was found that the output characteristics of the both systems as a function of the lateral displacement are almost the same. On the other hand, the swap of the coils couple between systems change the output characteristic dramatically.