[Adoption Example] Kikusui Electronics Corp. 20kW Bidirectional Large Capacity DC Power Supply

ROHM SiC MOSFETs Contribute to Smaller, More Efficient, Reliable High Power Bidirectional Power Supplies

Kikusui Electronics Corp. 20kW Bidirectional Large Capacity DC Power Supply

Adoption Background (Product Development)

The transition towards an era of carbon neutrality has led to an increased demand for high capacity bidirectional power supply devices to be used as testing equipment for inverters and motors when developing EVs (Electric Vehicles), PHVs (Plug-in Hybrids), FCVs (Fuel Cell Vehicles), and the like. To this end, Kikusui Electronics Corp. has developed a 3U size 20kW bidirectional high capacity DC power supply that meets these market needs. Existing products in the same size featured a maximum power of 8kW, but user requests for a 20kW power supply that could operate in both directions proved quite difficult to develop. To achieve this in the same size required more than double the power density, so it was necessary to review conventional circuit methods. As a result, a three-phase inverter circuit consisting of three arms was adopted to provide high efficiency bidirectional (regenerative) operation in the primary circuit, which normally uses a rectifier bridge and boost chopper type PFC.

Adoption Background (SiC MOSFETs)

Initially, IGBTs were planned to be used in three-phase inverters due to their high withstand voltage and low ON resistance. However, when employing IGBTs with built-in diodes to return energy to the choke coil, their slow reverse recovery time (trr) can lead to the generation of instantaneous through-currents, resulting in device heating and surge-like noise due to efficiency deterioration. Element heat generation in particular is a critical issue that not only degrades electrical characteristics, but also causes element failure, posing a significant risk to product safety. Attaching FRDs and SiC diodes to IGBTs without built-in diodes was also considered, but the larger circuit size would have created space issues. In the end, ROHM SiC MOSFETs were recognized as being able to solve this problem, which led to their adoption.

< Customer Feedback > 

・ Development Manager, Kikusui Electronics Corp.

After considering various options, we found ROHM SiC MOSFETs to be the best solution to solving this problem. The decision to adopt was based on a comprehensive evaluation that considered high breakdown voltage, high-speed reverse recovery characteristics, low ON resistance, and low package thermal resistance, along with the established reliability and prompt support from a domestic semiconductor manufacturer. So it is no exaggeration to say that ROHM's products were essential to the development of a high reliability, high efficiency 3U20kW bidirectional large-capacity DC power supply.

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About Kikusui Electronics

Kikusui Electronics Corp.

Kikusui Electronics Corp.

Established in 1951, Kikusui Electronics Corp. has been restructured into a holding company, taking over the company name, development, and sales operations.
As a manufacturer of power supply equipment and measuring instruments, our company has long supported electronics technology. We will continue to respond to customers’ needs and provide them with high-quality products and trusted services.
We strive for continuous improvement. We want to evolve with society and keep contributing to raise the quality of life. This philosophy guides our company’s operations.