To mitigate climate change, significant progress has been made in non-fossil fuel and renewable energy solutions, accelerating the electrification of transportation. These emerging technologies demand higher power supply capabilities, especially in high-power applications. For instance, electric vehicle (EV) battery packs now exceed 900 VDC with capacities reaching 95 kWh, while fast and ultra-fast charging systems easily surpass 240 kW. Similarly, hydrogen fuel cell stacks, another automotive power source, can generate over 500 kW with currents up to 1000 A.
While phasing out fossil fuels is essential, global energy consumption continues to rise. One example is server farms, where energy demand is increasing rapidly. To accommodate renewable energy sources, server farms are shifting from AC to DC power distribution, operating at 360 VDC and 2000 A. Additionally, some emerging technologies are pushing voltage levels to 1800 VDC.
To meet the demand for testing high-power products, EA needed to develop power supplies with higher output power and voltage, while also reducing test system size and energy costs.
Traditional silicon-based MOSFET designs require three transistors for 5 kW output. With 30% derating, a 5 kW module needs three 500 VDC units in series for 1500 VDC. Three such modules form a 15 kW unit.
For a 150 kW load, ten 15 kW supplies fill a 42U, 19-inch rack. A 450 kW load needs three racks, occupying 18 square feet. At 93% efficiency, they generate 31.5 kW of heat, demanding substantial cooling.
To overcome these challenges, EA’s engineers chose SiC power transistors, offering superior performance over silicon alternatives.
Earlier three-phase power systems relied on silicon Insulated-Gate Bipolar Transistors (IGBTs), which support 1200V operation and provide high current capacity. However, IGBTs suffer from high conduction and switching losses.
In contrast, SiC MOSFETs exhibit significantly lower conduction and switching losses. As shown in Figure 1, SiC MOSFETs have a lower voltage drop compared to equivalent IGBTs. Their on-state resistance (R_DS(on)) remains lower than the saturated IGBT’s pn junction resistance, reducing conduction losses. Moreover, switching losses are even more pronounced—SiC MOSFETs feature switching energy losses nearly one-tenth of IGBTs due to lower capacitance and shorter turn-off times.
SiC MOSFETs also operate at significantly higher switching speeds. As seen in Figure 2, their dv/dt rate is nearly twice that of silicon MOSFETs, both during turn-on and turn-off events. This faster switching capability allows for higher frequency operation, reducing the size of power conversion components.
SiC MOSFETs offer superior reliability, as their actual breakdown voltage exceeds rated values, as shown in Figure 3. This ensures better resistance to transient overvoltages. Additionally, SiC MOSFETs maintain their breakdown voltage even at low temperatures, whereas IGBTs require derating below -30°C to prevent failures.
Another advantage of SiC power devices is reduced chip size. A 1200V SiC MOSFET chip is only one-fourth the size of a comparable silicon IGBT. Moreover, silicon IGBTs require an additional reverse-biased diode for bidirectional current flow, whereas SiC MOSFETs inherently support bidirectional conduction through their internal body diode.
Because of these benefits, SiC transistors enable more compact power electronics designs, with lower stray inductance and higher power density than silicon counterparts.
Leveraging advanced SiC technology, EA developed the EA-10000 series programmable power supplies, featuring:
- 4U/30 kW and 6U/60 kW designs
- Up to 2000V output voltage
- 3% higher efficiency
- 37% increased power density
- 33% smaller footprint for 240 kW systems
- 42% reduction in heat dissipation
- 15-20% lower cost per watt
The EA-10000 series was designed to:
Achieve higher efficiency than existing programmable power supplies
Increase DC output voltage to 2000V
Enhance power density to reduce system size
Lower cost per watt
During development, EA engineers carefully evaluated traditional silicon vs. silicon carbide transistors. While silicon-based switching designs can achieve 93% efficiency, their power density is limited to 9.2 W/in³ using 5 kW modules.
By adopting SiC MOSFETs, EA’s new power supply series significantly improves efficiency, power density, and cost-effectiveness, making it a superior choice for high-power applications.
