Silicon Carbide (SiC) power devices have attracted significant industry interest due to their superior performance compared to silicon-based IGBTs. SiC devices boast lower on-resistance, switching loss and operating temperature that enable new power applications.
Cree/Wolfspeed, Microsemi, Infineon, GeneSiC, ROHM and ST are among the numerous suppliers that offer both planar and trench MOSFETs.
Improved Voltage Characteristics
SiC power MOSFETs feature a wider bandgap that enables them to work at higher voltages, making them suitable for applications such as electric vehicle chargers, UPSs and solar string inverters. This translates to lower operating costs and reduced energy losses that contribute to environmental degradation while simultaneously improving efficiency by decreasing passive components and switching losses. This makes these devices ideal for demanding applications such as electric vehicle chargers, UPSs and solar string inverters where efficiency matters.
SiC power devices also benefit from having high breakdown electric field strength, enabling them to handle higher current levels with reduced external gate resistor size and cost – especially beneficial for LLC resonant DC/DC converters, where their voltage-switching capacity relationship (COSS/VDS) is much more linear compared with other device types.
SiC power MOSFETs boast high blocking voltages, making them safer in high-voltage environments than their silicon counterparts, which feature lower blocking voltages. This makes the SiC MOSFET more reliable as it can manage harsh conditions found in automotive drive systems; furthermore, SiC MOSFETs can handle higher di/dt conditions and higher body diode values, thus providing robust commutation while allowing higher BV values in body diodes for reliable commutation and body diode use.
Low Conduction Loss
Silicon Carbide (SiC) devices’ wide bandgap nature allows them to achieve higher voltage ratings with lower power losses compared to conventional silicon devices, leading to greater energy efficiency, reduced component counts, smaller packages and a more compact overall design.
SiC MOSFETs provide modern power converters with fast switching frequencies, making them a key component. Unfortunately, however, these MOSFETs may experience overshoots and oscillations that disrupt electromagnetic compatibility or lead to premature device failure. To reduce these adverse effects it’s essential that gate drive parameters be optimized as well as parasitic inductances are reduced as quickly as possible.
As the power industry shifts to greener sources of energy, demand for high-voltage devices has skyrocketed, prompting next-generation materials like SiC to meet this rising need. SiC enables megawatt applications such as railway traction converters and medium-voltage industrial drives – something SiC is ideal for.
SiC MOSFETs benefit from higher operating temperatures and wider bandgaps than can withstand much larger voltages, thus decreasing on-resistance and increasing power density. weEn’s CoolSiC G2 portfolios boast best in class RDS(ON) at both 650 V and 1200 V using trench-assisted planar technology as well as high performance diodes to ensure reliability and performance, suitable for applications from 10s of kW up to MW across rail, EV fast charging, industry solar wind applications.
High-Speed Switching
SiC power MOSFETs offer fast switching capabilities with minimal conduction loss and operating temperature range, providing significant benefits in new electronic circuit designs.
Fast switching can bring many advantages to circuit designs, including smaller footprints, increased efficiency and reduced total harmonic distortion (THD). But this method also presents numerous challenges; among these is the requirement of high-speed testing equipment such as passive voltage probes with adequate bandwidth and dynamic performance, as well as current viewing resistors with very small loading capacitance loads.
One challenge of making complex systems work efficiently lies in mitigating parasitic effects, such as measurement inaccuracies, current ringing, voltage/current spikes during transitions and gate driver/SiC FET galvanic isolation from low voltage circuitry – this may require optical, pulse transformers or capacitive isolation techniques to be effectively implemented.
Silicon carbide’s wide bandgap allows electrons to quickly travel along its channel, resulting in faster switching speeds, reduced on resistance, a thinner depletion region, and an increase in blocking voltage. As such, SiC MOSFETs are ideal for applications requiring fast switching with low loss – three phase inverters, Uninterruptible Power Supplies (UPS), and Photovoltaic Inverters among them.
Low On-Resistance
SiC MOSFETs boast lower on-resistance than their silicon counterparts, making them suitable for high voltage applications. This is possible thanks to SiC material’s wider bandgap that results in thinner depletion regions that enable electrons to travel more easily between source and drain terminals of the device. Furthermore, its superior thermal conductivity and higher saturation electron drift velocity contributes to faster switching operations that lower on-state resistance by up to 15 percent compared with silicon devices.
SiC power MOSFETs’ lower specific on-resistance can also help to decrease diode size and overall system losses, making these devices ideal for use in electric traction inverters and UPS applications.
As demand for high-voltage power devices increases, manufacturers are looking for ways to improve on-resistance performance to further decrease system losses and enable higher efficiencies in power systems. SiC power MOSFETs provide the ideal solution, boasting their superior electrical properties such as high critical breakdown field strength, thermal conductivity and intrinsic carrier concentration levels; making them an excellent solution.
SiC power MOSFETs have seen increased adoption due to their enhanced on-state characteristics, making more efficient switching designs possible across a variety of high voltage applications. Unfortunately, however, there still remain some reliability issues with these devices such as gate oxide degradation, accelerated life test high temperature reverse bias failure (ALT-HTRB), and neutron damage.
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