The case for GaN in vehicle charging systems

This article originally appeared in the March '22 magazine issue of Electronic Specifier Design – see ES's Magazine Archives for more featured publications.

Gallium nitride (GaN) has many attractive properties. When used in power modules for electric vehicles (EVs) it operates at up to 20 times faster than traditional silicon chips, provides higher efficiencies, lowers heat loss and allows higher operating performance, compared with silicon devices. Advocates of GaN, including Navitas Semiconductor, Efficient Power Conversion (EPC) and GaN Systems, are channelling a lot of design effort into creating power modules for charging systems which will increase battery energy capacity. Another focus is for faster charging than is currently possible with silicon.

Today, GaN is more expensive than silicon; the price differential can be up to 20%, but manufacturers are confident this gap will close. Gene Sheridan, CEO of Navitas, a GaN power semiconductor manufacturer, has said that GaN may even be cheaper than silicon, but added that the entire energy system around the chip may need to be redesigned.

GaN-based on-board chargers (OBCs) can charge up to three times faster than silicon versions and have up to 70% energy savings. These performance gains can translate into extended EV range or reduced battery costs.

Designs on China

In January this year, Navitas opened its EV design centre in Shanghai, where its power system designers will work with EV manufacturers to develop electrical, thermal and mechanical design, software development as well as simulation and prototyping capabilities with EV customers.

The company’s GaNFast power ICs integrate GaN power, drive, control and protection in a single IC which can be used to increase switching speed and save energy in power conversion and fast charging for EVs. At the end of last year, the company sampled its high power 650V GaN ICs for EV applications and atCES, it exhibited its 6.6kW OBC. Vice president and general manager of Navitas China, Charles Zha commented: “E-mobility is an exciting expansion market for GaN, with an estimated $250 potential content per EV”.

Another benefit to GaN, according to Navitas is that it has a lower CO2 footprint, calculated on use-case efficiency, material size and weight reductions to save 4kg of CO2. “Overall, GaN is expected to address a 2.6Gton/yr reduction in CO2 emissions by 2050,” says the company.

GaN power modules

At the end of last year, another GaN supplier, GaN Systems, announced a partnershipwith Universal Scientific Industrial (USI), a subsidiary of Taiwan’s semiconductor assembly and test manufacturer, ASE Technology, to co-develop GaN power modules for the EV market. USI has acquired a minority share of the Canadian power semiconductor manufacturer.

GaN power modules enable higher efficiency, increased EV range, and increased EV performance, said GaN Systems. Presently, GaN power modules are transitioning to meet the demands of low heat loss and superior voltage control in the vehicle’s power conversion process.

USI’s senior vice president of Strategic Investment, JP Shi, says the company has been impressed with GaN Systems’ “leadership in high reliability, automotive-qualified GaN – an essential building block for EVs”.

The company believes that creating optimised, highly efficient modules “that will be the cornerstone of ... DC/ DC converters, on-board chargers and traction inverters”. USI manufactures power electronics manufacturing, working with different package types as well as power modules, DC/ DC converters, intelligent power modules (IPMs) and RF power transistors. The company supplies OEMs and Tier 1 automotive manufacturers and introduced ISO26262, the automotive functional safety standard.

“Through this partnership, we bring together USI’s leadership in complex, high-power integrated modules with our high-reliability GaN semiconductor technology to build truly disruptive, game-changing modules for next generation EVs,” comments Stephen Coates, general manager and vice president of operations at GaN Systems. He expects to build on relationships with BMW, Toyota, and Vitesco, to accelerate GaN adoption.

AEC-Q101-certification Another GaN manufacturer, Efficient Power Conversion (EPC) is concentrating design efforts on lidar (light detection and ranging) and radar systems within the vehicle, as well as high intensity headlights, infotainment systems and 48 to 12V DC/DC converters. Its EPC2202 and EPC2203 eGaN FETs are AEC-Q101 certified.

They are available in a wafer level chips scale package (WLCSP) measuring 2.1 x 1.6mm and 0.9 x 0.9mm respectively. The EPC2202 is an 80V, 16mΩ enhancement mode FET while the EPC2203 is an 80V, 73mΩ FET. Both are claimed to be smaller and switch 10 to 100 times faster than silicon MOSFET competing parts. To date, no EV manufacturer is using GaN, and given that the typical design cycle is three to five years, it is unlikely that GaN EVs will be on our roads before the end of this decade.