STMicroelectronics’ STPower silicon carbide MOSFET technology sets new benchmarks in power efficiency, density and robustness – particularly within EV bus traction inverters.
Yole Group, a market, technology, engineering, and performance analysis provider, and SERMA Technologies, an electronics testing expert, have joined forces to analyze and compare five 1200 V-class discrete SiC MOSFET devices manufactured by Wolfspeed, ROHM, Infineon, STMicroelectronics and Anbonsemi under identical test conditions.
Low On-State Resistance Per Area
ST is the world leader in silicon carbide (SiC) power MOSFETs and continues to lead innovation around these devices by taking advantage of their superior efficiency and higher power density compared with silicon devices. Their latest generation is tailored specifically for use with future EV traction inverter platforms to provide further size reduction and energy-saving potential.
This next-generation SiC MOSFETs have been specifically engineered to deliver significantly lower on-state resistance (RDS(on)) per area on a smaller die, enabling more compact designs with reduced component counts and costs.
Lower on-state RDS(on) per area allows designers to develop more energy-efficient and smaller systems for electric vehicles, providing longer range, quicker charging time and reduced energy consumption. Furthermore, reduced RDS(on) per area results in fewer parasitic capacitances which further contribute to greater energy efficiency as well as smaller system size.
SiC MOSFETs’ avalanche ruggedness is dependent upon maximum gate drive voltage and DC bus voltage, but the mechanism of stress degradation differs dramatically from IGBTs’ short-circuit failure mechanism; hence it is essential to understand underlying phenomena to create reliable models. Our results indicate that Vth and Rds(on) gradually decline after repetitive avalanche stressing while parasitic capacitances such as Ciss, Coss, and Crss increase with repeated abuse.
High Power Density
St sic MOSFETs provide more efficient designs in applications with significant power requirements, such as electric vehicle chargers, server power supplies and energy systems. Their higher switching frequencies and reduced parasitic effects such as electromagnetic interference (EMI) help increase circuit performance and reliability; thanks to much lower on-state resistance per area and thermal management considerations than traditional silicon power MOSFETs.
STMicroelectronics’ fourth generation STPOWER silicon carbide (SiC) MOSFET technology, Generation 4, sets new benchmarks in power efficiency and density. It’s specially tailored for use in traction inverters – key components in electric vehicle powertrains – providing more affordable charging capacity as well as faster speed for premium models of electric vehicles.
SiC MOSFETs with 650 and 1200 V ratings feature some of the lowest RDS(on) x Area ratio and switching losses available, making for more compact, efficient and cost-effective power converter designs – providing higher energy-efficiency, reduced total system costs, and enhanced reliability.
These devices feature a zero voltage switch (ZVS), which enables them to function reliably without negative bias drive – eliminating costly gate drive circuits and saving costs in energy efficiency and power density. Furthermore, their lower on resistance and fast switching further increase energy efficiency and power density. Moreover, their 7 year device longevity program gives designers confidence that these long-term devices are available and cost-effective solutions.
High Reliability
STPOWER Silicon Carbide MOSFETs deliver advanced efficiency, reliability, and robustness in power converters for electric vehicles and other applications requiring high energy efficiency, power density density, fast switching times, or energy conservation. Available in various state-of-the-art packages like HiP247, H2PAK-7 long leads TO-247 TO PAK and STPAK packages these devices make a perfect addition to inverters or high efficiency power supplies.
Although SiC MOSFETs possess an advantageous 650-V rating over Si power devices, they still present challenges in certain power conversion applications. Gate oxide degradation exacerbates degradation during certain harsh stresses like short circuit (SC) stress or avalanche stress and must be considered carefully to minimize device degradation.
STMicroelectronics has taken steps to overcome these limitations by increasing device performance and reliability for its third-generation 650 V SiC MOSFETs. Their most advanced device, a 2-kV 4H-SiC MOSFET, boasts an astonishing lifetime that surpasses that of any traditional IGBT when subject to high temperature PCT stress conditions. Due to reduced cell pitch and possible optimization of dopant distribution in the drift region, this generation also achieves lower RDS(on). This device also displays exceptional reliability during dynamic reverse bias (DRB) tests, surpassing AQG324 automotive standard. This inaugural volume in Discretes Performance Comparison Analysis 2024 series compares five 1200 V-class discrete SiC MOSFETs from global vendors as well as one Si IGBT under identical test conditions.
Wide Bandgap Materials
Wide bandgap semiconductors are ideal for power electronics applications due to their larger energy gap and ability to function at higher temperatures while reducing power losses compared to first-generation semiconductor materials like silicon. Furthermore, wide bandgap semiconductors feature higher electron mobility that enables driving circuits at higher switching frequencies for more energy-efficient and compact systems.
Rising energy efficiency demands have led researchers to research new power semiconductor materials, with silicon yielding to two alternatives – silicon carbide (SiC) and gallium nitride (GaN) being seen as more advantageous options, particularly for use in high-voltage power applications. Silicon was once seen as a dominant contender but has recently given way to both these alternatives as power semiconductor solutions.
Silicon Carbide (SiC) and GaN have wider bandgaps than the first generation semiconductor material, providing higher operating voltages, lower temperature settings, and reduced energy loss. Furthermore, SiC/GaN devices are smaller and lighter than their silicon counterparts to reduce component size/cost while increasing system performance.
STMicroelectronics recently unveiled its third-generation 650 V SiC MOSFET using the industry-accepted Figure of Merit (FoM). According to STMicroelectronics, their device offers outstanding on-resistance RDS(on) values and boasts a higher quality factor than leading competitors thanks to a 20% reduced gate array pitch and optimized dopant distribution in its drift region. With such high performance standards in place, designers will now have access to designing power supplies suitable for renewable energy inverters, battery chargers or electric vehicles based upon these parameters.
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