In this study, a single-phase induction heating (IH)-applied water heating system with Silicon Carbide (SiC) MOSFET-based single-ended high frequency inverter is presented for home and consumer appliances. The proposed system exhibits high thermal response for fluid heating due to the ferromagnetic/non-ferromagnetic materials and work-coil structure. They which are suitably designed for electric heating as well as the newly-developed high-frequency inverter. Thus, efficient electric-thermal energy conversion is expected. This is competitive for conventional gas-based fluid heating. The performances of the proposed fluid IH system are demonstrated with a 5-kW prototype together with the relevant analysis and design. Subsequently, the feasibility is evaluated based on practical applications.

This study proposes a novel integrated transformer structure with simple circuit configuration and miniaturized magnetic components. In a bridgeless flyback rectifier, two flyback converters operate corresponding to the polarity of the AC input, requiring two transformers. This paper proposes a novel winding structure that realizes zero coupling coefficient between two sets of windings. This enables the integration of two transformers into a single transformer, preventing their flyback operations from interfering with each other. The integrated transformer has approximately 16% lower volume compared to that of conventional transformers. The proposed integrated transformer was built, evaluated, and verified by designing a 75W-bridgeless flyback rectifier with 100kHz switching frequency.

The authors proposed a rail brake that does not require a power supply by using capacitor self-excitation. In the case of capacitor self-excitation, the operating state changes passively as the rail brake gap changes. Hence, the capacitor capacity must be selected considering the effect of gap displacement. In this paper, the current-frequency characteristics of the equivalent circuit constants at several gaps are obtained. Using the current-frequency characteristic diagrams, a method for selecting the capacitor capacity is presented. This allows the excitation to continue even when the gap changes and does not cause overvoltage.

In our previous study, we developed the fixed power factor output method voltage control with reference voltage command value adjustment. This control method enables electronic frequency converters, interconnected to a distant power source, to appropriately share the power supply of the train load. However, we confirmed that overvoltage in line and phase voltage can occur when large unbalanced power flows from the distant power source, and this control method cannot suppress the unbalanced power. Therefore, in this study, we developed the fixed power factor output method voltage control with reference voltage command value adjustment adding unbalanced power suppression function, which we verified with power system analysis.

One way to reduce the size and increase the power density of a motor is to increase its rotational speed. However, to drive motors at high speeds, the operating frequency must be increased, which increases in harmonic losses, primarily iron loss and AC copper loss. Therefore, harmonic losses must be quantitatively evaluated with high accuracy at the design stage. In this study, the validity of the method for evaluating the AC copper loss during high-speed operation is examined by comparing the difference between analytical values and evaluation formulas based on the relationship between the harmonic components of the voltage and current and slot shape.