The development and application of transverse flux machines (TFMs) with permanent magnet (PM) excitation have received more and more attention in recent years because of the high torque density at low rotating speed applications. This paper proposes a novel topology structure of TFM with dual-rotor and flat-type-stator (DRFTS-TFM). One of the advantages of the proposed structure is that the sandwiched design greatly reduces the manufacturing and assembling difficulties. Another advantage is that the number of the armature phase can be easily changed by converting the mechanical angle of the stator. To investigate the best electromagnetic torque performance of the machine, the multi-objective particle swarm optimization (MOPSO) algorithm is adapted and validated by the finite element method (FEM). The corresponding electromagnetic performances in different conditions are analyzed.

This paper proposes and implements a stepless frequency regulation method for wireless power transfer (WPT) with a simple LC compensation network to provide load-independent transmitter current. It should be mentioned that the capacitor in LC compensation network is controlled by a switch. Different from previous switched capacitor compensation networks, which can only select a limited number of resonant frequency points, this model can choose the resonant frequency arbitrarily in a wide frequency range. In theory, the frequency range can be controlled from a few kilohertz to hundreds of kilohertz. The key is controlling the turn-on time of the switch and adjusting the activation time length of the controlled capacitor in every WPT cycle. Therefore, the proposed system is very suitable for multi-frequency WPT, as the system can work at full resonance with practically arbitrary frequency. A Simulink simulation serves for verification, and the results prove the system can change the resonant frequency from 100 kHz to 300 kHz continuously while keeping the transmitter current load-independent.

In this paper, a wireless bipolar drive has been proposed and implemented for AC application, which not only performs selective wireless power transfer (WPT), but also secondary-converterless operation for frequency-controllable AC output. The key is to use the proposed self-drive circuit based on the selective WPT with two different resonant frequencies. Besides, the inductor-capacitor-inductor (LCL) compensation network is newly adopted to achieve power equalization so that only one transmitter is needed to serve two receivers and control the low-frequency AC output. As a result, there is no additional battery, controller, and converter at the secondary side and hence the system robustness can be significantly improved. Finally, experimental results are offered to verify the proposed topology.