A high power coaxial inductive power transfer pickup

Abstract

A new pickup termed the "coaxial pickup" is presented in this paper, specifically designed to meet increased power demands by industry. The pick-up is designed for inductive power transfer applications where high power is delivered to a load, which operates on an essentially straight monorail section (such as a lift). The proposed pickup has many advantages including unity power factor, minimal winding loss, and the ability to be paralleled. The high coupling and low inductance of the coaxial pickup makes it ideal for use in high power systems with large track currents, without the associated problems of large resonant voltages. An LCL tuning topology together with a current sourced voltage multiplier is proposed to achieve unity displacement power factor at the input of the pick-up, with a standard output voltage for industrial use. Higher power loads can be driven by paralleling up the outputs of multiple pick-ups using an interleaved switching control strategy to reduce the power demand of each pickup, increase the effective switching rate seen by the load (thereby improving output voltage regulation), and minimize surges seen by the power supply. Currently two prototypes have been constructed, a smaller scale pickup and a single 12.5 kW full scale section. A final full scale prototype is to be constructed using four 12.5 kW sections to produce a 50 kW pickup. Initial results and prototype measurements are presented that confirm the proposed pick-up feasibility.