This paper investigates a modular high frequency high voltage (HV) power supply architecture with planar transformer to achieve compact size and high efficiency. The insulation stress and voltage distribution different architectures with planar transformer are analyzed in firstly. An optimized modular high frequency HV generator architecture with planar transformer is proposed with even voltage distribution, low high frequency AC stress, easy insulation design and good thermal performance. The HV insulation and electric design of the HV planar transformer are provided. A prototype with 300kHz 4kW 140kVDC HV power supply with modular HV generation architecture and planar transformer is built to validate the concept finally.

A novel modular high frequency high voltage (HV) generator with silicon carbide (SiC) power semiconductor devices is proposed in this paper to achieve high efficiency, sharp HV pulse and compact size. The modular architecture is introduced for high frequency operation firstly. The switching characteristics and detailed design consideration on the gate driver circuit are given. Finally, the 8kW output-power, 110kV output-voltage HV generator prototype with 300 kHz500 kHz switching frequency is built to validate the design. Compared with existing design, 2 times high power density, around 10% higher efficiency and 4 times faster HV pulse can be achieved from the proposed modular SiC HV generators.

This paper presents a medium frequency transformer with high insulation level design which is used for the DAB DC-DC converter. The transformer size is largely reduced when operating at medium frequency compared with conventional power frequency transformer which provides the possibility for higher power density. However, there is a trade-off between the high power density and thermal performance. First of all, the exposed cooling surface is reduced accordingly. And the dissipated heat is proportional to the exposed cooling surface directly. Secondly with higher frequencies, effects such as skin and proximity and hysteresis losses are significantly increased compared to transformer operation at 50/60 Hz. Besides the design process should consider high isolation requirement. And this again defects the transformer thermal performance and this is because firstly insulation material adds extra losses to the system, secondly the construction of the insulation will block some cooling surfaces and thirdly those insulation materials normally have relatively low thermal conductivity. As a consequence, the thermal design should be carefully considered and evaluated. To solve this problem, only the high voltage side winding is impregnated in epoxy resin which reduces the insulation material. The stacked transformer cores are gapped from each other which have helped the transformer heat dissipation. Such that, a design with low thermal resistance and high power density is achieved. FEM models are developed to analyze the transformer electric and thermal performances. Finally prototypes are built and tested to verify our design concept.

In this paper, a coupled-inductor-based LCC resonant converter with the primary-parallel-secondary-series (PPSS) configuration is proposed to achieve output-voltage sharing ability for HV generator applications. The PPSS configuration of the LCC resonant converter with the voltage multipliers is introduced to achieve high output-voltage and increase the output-power level. However, the variations of the magnetizing inductance, leakage inductance, and winding capacitance of the HV transformer and voltage multiplier impact on the output-voltage sharing performance. Subsequently, the resonant inductors in the primary side of the conventional LCC resonant converters with the PPSS configuration are coupled to achieve the output-voltage sharing without any additional circuits and control efforts. Furthermore, an analytical equivalent circuit model considering the magnetizing inductor of the HV transformer is derived to analyze the output-voltage sharing ability. Moreover, the design method for the coupled inductors considering the output-voltage sharing performance affected by the leakage inductance of the coupled inductors is presented. Finally, the output-voltage sharing performance of the proposed coupled-inductor-based LCC resonant converter with the PPSS configuration is validated by the experimental results of a 50-V input, 5-kV output 100-W prototype. The prototype experimental results show that the unbalance voltage degree decreases from 67.7% to 8.5% with the utilization of the coupled inductor.