Delta Electronics, a major industrial electric equipment maker from Taiwan, announced it has begun work on a unique new prototype ultra-fast 400 kilowatt EV charger with funding from the US Department of Energy.
Delta has been a commercial supplier of AC as well as CHAdeMO and CCS DC charging equipment in the past but has not been a major supplier yet to the various announced ultra-fast charging networks in Europe and North America. It’s relatively rare 100 kW charger model has been installed at a few locations in Europe such as Norway.
The new project, due for completion in 2020, aims to design a higher efficiency charger that can eliminate the need for a conventional on-site utility transformer by directly taking in 4.8 kV up to 13.2 kV AC from local utility distribution lines or by directly connecting to DC power sources.
Eliminating the conventional on-site transformer could reduce cost in some installations and improve efficiency. Since utilities often supply and install the on-site transformers it could also speed site installations by reducing some planning, scheduling and coordination with local utilities.
In addition to taking in higher AC voltage levels, the new prototype charger will also have a direct DC input which could lower costs and improve efficiency when using DC power from adjacent renewable energy sources or stationary battery storage without the need to first convert it to AC.
Delta says the core power electronics of the charger will be based on a new solid-state transformer based on a silicon carbide (SiC) MOSFET design that improves efficiency.
The new design is expected to take half the physical size of conventional DC charging designs and weigh four times less.
The new design is also expected to have a grid to vehicle efficiency of up to 96.5 percent. Older generation DC chargers typically had efficiencies in the lower 90 percentile range and that was taking in 480V AC after having the power go through a utility transformer.
As examples, Tesla’s Supercharger has a stated efficiency of 90 percent and the ChargePoint Express 200 DC charger that supports 50 kW (rebadged from Tritium of Australia) is rated as 92 percent efficient.
The new generation of ultra-fast DC chargers generally have higher efficiency ratings. ChargePoint’s new Express Plus 250 and related chargers are rated as 96 percent efficient at full load. New ultra-fast chargers from ABB and Efacec are specified as 95 percent efficient.
Utility distribution transformers installed since 2010 that take 4.8 or 13.2 kW AC down to 480V AC for local customer use are required under Energy Department Energy Star regulations in the US to be at least 98 percent efficient when operating at a power level of at least 20 percent of their rated capacity. The chart below compares these recent Energy Star transformers to typical older designs.
The new prototype charger is expected to enable an overall 3.5 percent improvement in grid-to-vehicle efficiency over existing designs, according to Delta.
The company says its partners for the 3-year, US$7 million project, include General Motors LLC, DTE Energy, CPES Virginia Tech, NextEnergy, the Michigan Agency for Energy’s Energy Office and the City of Detroit’s Office of Sustainability. Half of the project cost is being shared by Delta.