10 May 2023
Innoscience and University of Bern develop multi-level topology reference demo
Innoscience Technology of Suzhou, China has collaborated with the Bern University of Applied Sciences (BFH) to deliver a reference demo that employs its 650V InnoGaN gallium nitride high-electron-mobility transistor (HEMT) devices in a multi-level topology to address 850VDC applications such as e-mobility motor drivers, solar and industrial inverters, electric vehicle (EV) fast chargers, and potentially EV drivetrains.
The three-level ANPC (Active Neutral Point Clamped) converter uses Innoscience’s readily available INN650D080BS 650V, 80mΩ HEMTs in the 8mm x 8mm DFN package. No snubber capacitors or expensive silicon carbide (SiC) diodes are required, reducing system cost.
“At higher voltages, classic two-level topologies such as a half-bridge are not practical as the 650V-rated HEMTs will fail,” says BFH professor Timothé Delaforge, who worked on this development with professor Sébastien Mariéthoz. “But there are many other topologies which mean that we can keep the operating voltage of the HEMT well below its rated voltage, while working with much higher DC bus voltages. In this case we chose the ANPC topology because it enables us to switch 850VDC without needing SiC. 850V is high enough for many industrial and e-mobility applications – even potentially EV drivetrains – if enough care is taken on the circuity design to minimize parasitics. We chose Innoscience’s InnoGaN HEMTs as they are very high efficiency and reliable, whilst also being the most cost-effective devices available on the market,” he adds.
“Although this design uses six HEMTs, because we are switching at much higher frequency, we can reduce the size of the filter and hence shrink the overall size of the converter,” says Dr Denis Marcon, Innoscience’s general manager, Europe. “Also, with our InnoGaN HEMTs we can achieve inverter efficiencies of 99%, increasing system reliability and decreasing cost.”