Design win; silicon carbide FETs enable portable e-Car charger

May 31, 2016 // By Graham Prophet
STMicroelectronics has disclosed that its silicon-carbide (SiC) devices are used in the ZapCharger Portable, claimed by makers Zaptec (Stavanger, Norway) as the smallest, smartest, and safest electric-car charging station, from this start-up company that has focussed on the transformer industry.

Described as the first portable electric-car charger with built-in electronic transformer, ZapCharger works with any electric car on any grid. The power-conversion capabilities of ST’s SiC MOSFET devices have enabled Zaptec engineers to design a portable, yet powerful piece of equipment. Ten times smaller and lighter than products with the comparable performance, the 3 kg, 45 x 10 x 10cm charger delivers an energy efficiency of 97%.


Mindful of safety, the water- and weather-proof ZapCharger is fully galvanically insulated and continuously monitors the grid it is connected to. It dynamically adjusts the amount of power it delivers and can shut down immediately if it detects a fault, to protect the car. The charger offers GPRS connectivity and operates over an extended temperature range from -40°C to +55°C.


Inside the ZapCharger, 32 high-voltage SiC Power MOSFETs from ST deliver efficient power conversion with minimum losses. Compared with traditional (silicon) solutions, these components can sustain much higher voltages, currents, and temperatures, and their power-conversion circuits operate faster, enabling smaller, lighter designs, higher system efficiency, and reduced cooling requirements.


Zaptec’s publications make extensive reference to its solid-state transformer technology, without specifying precisely what that comprises; it appears to be a compact isolating and conversion transformer operated at elevated switching rate by virtue of the SiC FETs. Other aspects of Zaptec’s portfolio relate to methods of achieving higher charging rates that would normally be available from domestic power outlet, including making use of 3-phase mains where available.


“The key for us was to find a power technology with a very high efficiency so we could reduce the overall size of the charger without compromising performance..[resulting in]...a product that dramatically changes the user experience, and by allowing consumers to take their chargers anywhere eliminates ‘range anxiety” and can accelerate the adoption of electric vehicles worldwide,” said Jonas Helmikstøl, COO, Zaptec.


In addition to electric-car charging, Zaptec’s patented, electronic-transformer technology targets