Methodology of inductive power transfer asymmetrical coils design for space-constrained applications

Abstract

In the wireless power transfer (WPT) field, it is no doubt that Inductive Power Transfer (IPT) is widely used and popular with charging market. Nowadays, aiming to achieve the load independent current (LIC) and load independent voltage (LIV) for battery charging, some studies of hybrid IPT topologies have been analyzed, such as Hybrid SS and PS compensated converter, Hybrid SP and PP compensated converter. However, such hybrid compensation topologies ignore one thing which is the coil arrangement. Many papers assume the received-side and the transmitter-side coil is symmetry, but most of the receiver side of the WPT application has constrained space, which means that the transmit power will be limited. To further increase the transmit power, the asymmetric coil design should be considered. Nevertheless, it is challenged to convert the identical coil to non-identical coil with maintaining efficiency, since there are many factors that affect the charging efficiency of the IPT system. This paper studies those factors include coil size, coil distance and coil shape etc. and then simulate them in PSCAD and Maxwell. Identical and non-identical which are the main difference of the design for the coils. According to the theoretical analysis of the efficiency, mutual inductance between two coils relates to the efficiency. Therefore, MATLAB and Maxwell are used to calculate and simulate the parameters for the design of the coils, the design of the coils calculated are applied to verify the study of the coil by experiments by charging efficiency and charging current. Moreover, the design method is applied to an Automated Guided Vehicle (AGV) for an implement of a device that is benefited with WPT charging compared to traditional charging.