Transfer characteristics of the MCR-WPT system using two series transmitting coils

Purpose The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power transfer projects. However, it remains a challenge to obtain the constant output power and transfer efficiency in a fixed-frequency mode during variations in transfer distance and orientation of the coils. In this paper, using two series transmitting coils to achieve the constant output power and transfer efficiency is used. Design/methodology/approach First, the circuit model is established and transfer characteristics are studied. Second, using the two series transmitting coils to achieve the constant output power and transfer efficiency is investigated. Finally, the experimental system is designed; it can optimize the transfer performances by itself; the constant output power and transfer efficiency are achieved in the fixed-frequency mode. Findings When the receiving coil moves between the two series transmitting coils, the tolerance of the output power and transfer efficiency is less than 5 per cent. Research limitations/implications When a receiving coil is placed between the two series transmitting coils, there are space limits. The receiving coil only shifts between the two transmitting coils. Practical implications However, the rail guide vehicle may achieve constant output power and transfer efficiency when it moves on the rail guide. So, this topology may provide a practical solution. Originality/value In this research, the three-coil MCR-WPT system including two series transmitting coils is presented. In a fixed-frequency mode, the constant output power and transfer efficiency is achieved in experiments during variations in transfer distance and orientation of the coils. The fluctuation of the output power and transfer efficiency is less than 5 per cent.