Estimating the output power of flat pickups in complex IPT systems

Inductive power transfer (IPT) has been successfully applied to single phase track systems to transfer power to moving vehicles without contact. Such systems suffer from a rapid reduction in transferred power as the track and pickup become misaligned. This has hindered their use in vehicular systems where the pickups must be allowed to move freely. Poly-phase IPT tracks have recently been proposed as a method of increasing the tolerance of the system to horizontal misalignment of mobile pick-ups. The substantial improvement in the tolerance of the system to misalignment is complicated by the number of design variables in the system, making it difficult to produce an optimal design. This paper presents a method of obtaining a first order estimate of the output power from a standard flat pick-up when used in an IPT system with an arbitrary track. This is achieved by exploiting the linear nature of non-saturating magnetic circuits to combine the system response from one track conductor into a composite that accounts for all the conductors. The estimate can be used to quickly and easily optimize the design of an entire IPT system. The final solution can then be simulated, built and experimentally verified.