Resonant circuit topology Comparison and CC / CV Characteristic Evaluation Considering the Difference in Power Supply in Capacitive Wireless Power Transfer circuits

CPT is cheaper and lighter than Inductive Wireless Power Transfer (IPT). In addition, Capacitive Wireless Power Transfer (CPT) doesn’t have risks of rising temperature of metallic foreign objects. Owing to these advantages, CPT will be able to use in various applications. But, No studies have made circuit comparisons considering differences between voltage and current sources. In this study, the typical circuits S-S, S-P, P-S and P-P circuits in CPT are compared, taking into consideration the difference in load value and the difference in power supply. In compensation condition, the conditions based on the gyrator characteristics and the ideal voltage transformer/current transformer characteristics are adopted. By satisfying this condition, CV characteristic or CC characteristic can be obtained in each circuit. As a result, it was found that the efficiency under the optimal load was the same value in all the circuits regardless of power supply, and the optimal load of S-S and P-S circuits was k² (coupling coefficient) times that of S-P and P-P circuits. When a voltage source is used, the output power of P-S and P-P circuits is k² times that of S-S and S-P circuits, and when a current source is used, the output power of S-S and S-P circuits is k² times that of P-S and P-P circuits. From the above results, it is concluded that when using a voltage source, S-S or S-P circuit should be selected. S-S should be selected when load resistance is low. S-P should be selected when load resistance is high. On the other hand, when using a current source, P-S or P-P circuit should be selected, P-S should be selected when load resistance is low. P-P should be selected when load resistance is high. These results could also be confirmed from experiments using actual circuits.