Alternating-Current Copper Loss Reduction in a High-Frequency Transformer for Railways Using a Magnetic Tape

The effective downsizing of power supply for railway by increasing the drive frequency is essential considering the mounting space. However, an increase in the drive frequency increases the loss in switching and magnetic elements used for power supplies. In this study, we focus on reduction of alternating current (ac) copper loss due to the skin and proximity effects by attaching a magnetic material at appropriate positions on the outer circumference of the wire in high-frequency transformers for railway. In this article, we propose a simple method of attaching magnetic materials to a winding in high-frequency transformers using a magnetic tape. In the magnetic field simulation, we could reduce ac copper loss in the high-frequency transformer using magnetic tape. The ac resistance at 16 kHz was reduced by 12.5% for the actual measurement using an impedance analyzer. The temperature rise at the thermal saturation was reduced by 21.4% for the energization experiment with a current of 31.6 A and frequency of 16 kHz. Analysis and actual measurements revealed that employing a magnetic tape in a high-frequency transformer can reduce ac copper loss and heat generation.