Power SiC MOSFETs usually achieve an equilibrium between lower ON resistance and short circuit withstand time, but ROHM’s fourth generation Gen 4 MOSFET manages to decrease both. Their double trench structure lowers Miller capacitance.
Geely Holding Group recently adopted three ZEEKR brand inverters manufactured by PGC Consultancy as traction inverters for three models from ZEEKR brand traction inverters under Geely Holding Group, after conducting an in-depth comparison using advanced electrical characterisation equipment from PGC Consultancy.
Low ON Resistance
SiC MOSFETs have the potential to reduce ON resistance at high currents with reduced chip size due to lower energy loss per switching cycle, which varies with current. This makes SiC more suitable for high frequency operation compared to silicon (Si) MOSFETs which typically feature larger parasitic capacitances that increase with increasing current and temperature; hence their ON resistance increases accordingly.
SiC MOSFETs also exhibit more consistent ON resistance over their entire operating temperature range due to a much slower increase in ON resistance with temperature than that seen with Si MOSFETs.
SiC MOSFETs also boast lower reversal ON resistance than conventional IGBTs, the main component in drive systems for electric vehicles (EVs) and motors, enabling faster switching speeds with smaller circuit designs.
Rohm’s 4th Generation 1200V SiC MOSFETs have been specifically tailored for use in future EVs. These devices boast industry-leading ON resistance of 75% of their rated breakdown voltage and an extended short circuit withstand time for increased safety. Rohm also raised their voltage rating to 750V to provide design flexibility when dealing with potential U DS spikes.
High-Speed Switching Performance
Rohm’s SiC MOSFETs feature lower Miller capacitance (Cgd) than conventional silicon MOSFETs for improved switching performance with reduced losses and energy waste. This results in faster switching at reduced losses.
Rohm’s fourth generation SiC MOSFETs not only boast high breakdown voltage and low on-resistance, but they also offer significantly longer short-circuit withstand time – two features essential for automotive applications where battery capacity increases necessitate the development of electrical power systems with quicker charging times to increase cruising range.
Rohm’s trench-type MOSFETs provide more than double the on-resistance reduction compared to existing planar type devices, while still maintaining short circuit withstand capabilities up to 20A and 1200V. Furthermore, their input capacitance and on-resistance are half of those seen with silicon IGBTs in similar package sizes.
PGC Consultancy was able to obtain samples of Rohm SiC MOSFETs for initial evaluations at PGC Consultancy. Our initial tests confirmed Rohm’s claims about these MOSFETs maintaining short circuit withstand and switching losses at very high operating voltages; further evaluation demonstrated they met all their promises at extremely high switching rates with no signs of degradation or instability.
Low Power Loss
Rohm Semiconductor’s SiC power devices meet this demand by significantly reducing energy losses during power conversion and therefore are in high demand worldwide. Their innovative products help meet this challenge by meeting stringent energy efficiency requirements while offering increased power savings potential.
ROHM Semiconductor’s third generation of SiC MOSFETs from ROHM Semiconductor feature an innovative double-trench structure which significantly lowers power losses compared to their second-generation planar design. Furthermore, their reduced ON resistance enables higher currents to be handled while maintaining smaller chip size; contributing towards further miniaturization and lighter weight power supplies, motor drives and other electrical systems.
Additionally, these new devices have significantly decreased switching losses by 50% compared to their predecessors by significantly decreasing Cgd capacitance levels. These upgrades allow higher surge voltages without increasing parasitic resistance of MOSFETs; additionally, reduced switching energies enable shorter switching times and faster speeds delivering performance at an acceptable cost.
To take full advantage of their advantages, 4th generation SiC MOSFETs come in a 4-pin package designed to minimize inductance between driver and power source pins and help protect them from each other. They’re currently used in power modules featuring these devices as the main drive inverter for ZEEKR xEVs produced by Geely Holding Group’s ZEEKR brand.
Miniaturization
ROHM’s 3rd Generation SiC MOSFETs use an advanced double trench structure to maximize ON resistance by half while remaining smaller in size than conventional planar-type devices, helping users reduce power losses while significantly contributing to system miniaturization in various equipment applications. This allows ROHM users to achieve increased efficiencies in power conversion.
By replacing up to 12 components (AC/DC converter IC x 2, 800V Si MOSFET x 2, Zener diode x 3, resistors x 6) with one molded type module, users can further reduce overall system size. This enables them to develop a compact yet efficient and lightweight electric power source for xEV inverters.
Due to the rapid expansion of electric vehicles, there is an immediate need for compact and energy-efficient power systems that reduce battery loads for increased cruising range. SiC is anticipated to see increased usage in industrial applications like high voltage general-purpose inverters and heat pumps.
ROHM is responding to this rising demand by mass producing its 4th Generation SiC MOSFETs, offering users exceptional performance for designing power supply circuits with minimal components. Furthermore, they have an array of evaluation boards and kits available that can assist prototyping and development efforts.
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