Carmakers and automotive suppliers are embracing 800-V drive systems to reduce electric vehicle (EV) weight, achieve much faster charging, and ensure longer driving ranges. And that’s pushing silicon carbide (SiC) semiconductors to the fore in EV powertrains and other applications where power density, energy efficiency, and reliability are critical design considerations.
The EV design building blocks where SiC is gaining popularity include traction inverters, on-board chargers (OBCs), and DC/DC converters. In the industrial realm, SiC components are increasingly employed in motor drives, renewable-energy converters and storage systems, and telecom and data-center power supplies.
Figure 1 Silicon carbide’s high-frequency capability allows smaller passive components within power systems. Source: STMicroelectronics
Eying SiC’s potential in the EV and industrial markets, STMicroelectronics is introducing its third generation of STPOWER SiC MOSFETs while claiming commercial maturity for most derivative products. According to Edoardo Merli, VP of Automotive and Discrete Group, the chipmaker aims to generate $1 billion in SiC revenue in 2024.
The qualification of the third-generation SiC technology implies the availability of SiC devices with nominal voltage ratings from 650 V and 750 V up to 1,200 V. That, in turn, gives design engineers access to a wider range of applications from ordinary AC-line voltages to high-voltage EV batteries and chargers. In this lineup, one of the first SiC devices, SCT040H65G3AG, is a power MOSFET operating at 750 V and is priced at $5.00.
Beyond SiC MOSFETs
With their higher voltage rating, SiC MOSFETs are made available in power modules and reference designs. Take, for instance, Microchip’s liaison with power management solution provider Mersen for creating a 150 kilovolt-ampere (kVA) three-phase SiC Power Stack Reference Design for EV and energy storage applications. It integrates Microchip’s SiC power modules, digital gate drivers, and Mersen’s bus bar, fuses, and capacitors in a single-stack reference design.
Figure 2 The SiC power stack claims to reduce time-to-market by up to six months. Source: Microchip
The power module is based on the 1,200 V MSCSM120AM042CD3AG SiC MOSFET. Along with AgileSwitch 2ASC-12A1HP digital gate driver, it enables design engineers to rapidly develop high-voltage systems using kits predesigned for their applications. With configurable digital gate drivers, the reference design allows engineers to select from 700 V and 1,200 V options in currents up to 750 A.
The AgileSwitch 2ASC-12A1HP gate driver is supported by Microchip’s Intelligent Configuration Tool (ICT), a free-of-charge download. It’s an interface that allows users to configure gate driver parameters such as gate switching profiles, system-critical monitors, and controller interface settings.
The reference design built around SiC MOSFETs provides 16 kilowatts per liter (kW/l) of power density and up to 130°C Tj, peak efficiency at 98% with up to 20 kHz switching frequency. Philippe Roussel, VP of global strategic marketing at Mersen, claims that reference design can help optimize any inverter topology. “Silicon carbide provides the capacity to extend primary specifications to a higher voltage, current and switching frequency to meet operating point needs.”
The availability of SiC devices, spanning from MOSFETs to power modules to reference designs, is a testament to this wide bandgap technology’s ability to serve EV applications and fast-charging EV infrastructures. SiC’s energy-saving potential also propels its use in industrial applications like solar inverters, energy storage systems, motor drives, and power supplies.
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