While silicon carbide (SiC) is still considered a relatively new material in the semiconductor market, it is now used in power circuitry that supports our everyday lifestyle — from the data centers that deliver our emails, to solar power grids that provide energy to offices and homes, to electric cars and trains we use to commute, and in factory equipment and robots that manufacture the goods we consume.
In the enterprise IT segment, SiC allows new topologies, such as the totem pole bridgeless PFC that has been limited by silicon’s (Si) inadequate performance1, to enable compliance with the Titanium standard for energy efficiency. SiC offers the solar market up to 99.5 percent efficiency, 3-times smaller size and 10-times less weight compared with Si. In an electric vehicle (EV), suitably packaged SiC modules can operate at higher ambient temperatures while delivering much lower losses. This enables anywhere from $300 to over $600 savings in battery costs, another $600 savings due to space reduction and, $500 to $1,000 savings due to less demanding thermal management2.
Wolfspeed Ramps SiC to Meet Explosive Demand
The company plans to use its over 30-year history of innovations and development experience with SiC to reach diverse end-use applications with a broad portfolio of bare die, discrete, and module platforms. As these application spaces grow, Wolfspeed is paced accordingly, with announced plans that include a Mega materials factory, a larger, highly-automated wafer fab, and 150 mm wafer processing with expansion capability to 200 mm SiC wafers3.
Wolfspeed has also taken a significant step in the direction of serving a broader market by launching its power module business into the large-scale, commercial-volume space with a line-up of both industry standard packages as-well as new SiC-optimized packages. Furthermore, the company has positioned itself to provide SiC into mainstream, high-volume markets, such as the industrial, energy, transportation, and automotive segments.
One Size Does Not Fit All
The widespread adoption of SiC power modules requires a variety of package sizes and device characteristics. The industry has historically used standard 45 mm, 62 mm and the even bigger EconoDUAL packages that are unable to take full advantage of the SiC technology. Competing SiC vendors often use packages originally designed to hold Si devices without any design improvements to account for the advantages of SiC — which is akin to fitting a Ferrari engine into an old beat-up pickup truck. Simply put, an old pickup is just not optimized to take advantage of the power of a Ferrari engine.
Wolfspeed is able to provide both the packages and die optimized to meet the benefits of SiC because of its vertically integrated model which enables co-development of new technologies to fit specific application spaces. When a module is specifically designed around the unique characteristics of SiC, it is capable of maximizing switching speeds, power density, and thermal performance. Taking the “not-one-size-fits-all” approach by offering both SiC-optimized footprints and standard legacy footprints, Wolfspeed’s module portfolio offers unprecedented flexibility in package design that fits all types of different end-use applications. As you are about to discover, the new XM3 module platform, sized at 53 mm, is a prime example of how Wolfspeed is setting the standard for SiC packaging.
The XM3 Platform: Creating New Module Footprints
Wolfspeed’s XM3 full-SiC power module establishes a new standard footprint within the module market, with 50% less weight and volume than a standard 62 mm module and industry-leading power density.This next-generation module has been optimized to accommodate all of Wolfspeed’s commercially available C3M MOSFETs up to 1,700 V. It can carry high currents up to 500 A in a small 53 mm x 80 mm footprint. Various internal device configurations will be offered within the XM3 power module platform to accommodate the various voltage and power demands across diverse applications.
In order to reach high switching speeds with low switching losses, a package must be designed to achieve low stray inductance; this is an important design philosophy in both the module and the system-level busbar design. The XM3 module beats the inductance of competitive legacy packages using a low-inductance, overlapping planar structure.
The current loops within the module are wide, low profile, and yield even distribution between the devices, resulting in equivalent impedances across a switch position. The power terminals on the module are also vertically offset. This enables design of simple bussing between the DC link capacitors and the module to be laminated all the way up to the module without requiring bends, coining, standoffs or any complex isolation. The end result is a power loop stray inductance of just 6.7 nH at 10 MHz — as demonstrated in the XM3 inverter reference design.
The high current density enabled by SiC devices requires a high-performance thermal stackup to maximize heat transfer. The XM3’s unique package design allows operation at a maximum junction temperature of 175°C. Other key features of the XM3 include an integrated temperature sensor on the low-side switch position; built-in voltage sensing (de-sat) connection for easy driver integration; and a high-reliability silicon nitride (Si3N4) power substrate to address demanding markets with enhanced power cycling capability.
When compared to similarly-rated Si IGBT power modules, the CAB450M12XM3 beats their performance with over five times lower switching losses — at 800 V and 400 A the total switching loss, including reverse recovery loss, is less than 30 mJ for an RGext of 0Ω. When we look at the switching-loss optimized CAB400M12XM3, the total switching loss at 800 V / 400A gets even lower at less than 15 mJ! The XM3 also delivers lower conduction losses without intrinsic knee-voltage to enable high efficiency at light loads.
The XM3 footprint offers enough internal layout flexibility to accommodate many different device configurations. As such, Wolfspeed will be releasing future derivative configurations of the XM3 all the way up to 1.7 kV, spanning several different topologies. These derivative configurations will target different end-use applications and power levels to cater to a wide variety of needs.
The first release in the XM3 platform is the CAB450M12XM3, which is targeted at conduction-loss optimized applications; followed by the CAB400M12XM3 and CAB425M12XM3, which are targeted at switching-loss optimized applications.
XM3 Evaluation Tools: Making SiC Implementation Easy
Designing around SiC can be challenging, so Wolfspeed creates educational material to teach new SiC designers best practices and help them master this new semiconductor material. The XM3 platform has system-level demonstrations, as well as laboratory evaluation tools to get you up and running quickly. The XM3 platform includes:
- the CGD12HBXMP Gate Driver
- the KIT-CRD-CIL12N-XM3 Dynamic Characterization Evaluation Kit
- the CRD---DA12E-XM3 200-300kW Three-Phase Inverter Reference Design (The ‘---’ in the part number is the power level, which is dictated by the module populated within the reference design, so there are multiple part numbers available.)
The CGD12HBXMP gate driver has been optimized for Wolfspeed’s C3M devices and is form-factor fitting to the XM3 footprint. Voltage rails of +15 V / -4 V on the output stage match the recommended VGS rating for C3M devices. The driver includes a Murata DC-DC converter with 2 W for each channel to enable high-frequency switching up to 80 kHz, with a peak isolation voltage of 5.2 kV for 1 minute and just 2.9 pF of isolation capacitance.
The driver offers up to 1,000 VRMS isolation (working voltage); overcurrent, shoot-through and reverse polarity protection; and 100 kV/μs Common-Mode Transient Immunity (CMTI). It also offers differential inputs for enhanced noise immunity. If your laboratory environment is not equipped to use differential signaling, Wolfspeed also offers a companion transceiver board that converts differential signals to single-ended — the CGD12HB00D. The design files for both the driver and the differential transceiver board are available for download, so that you can use the schematics as a learning tool to build your own driver if you’d like.
The KIT-CRD-CIL12N-XM3 design allows engineers to evaluate the XM3 module’s dynamic performance in their own lab. The design provides access points to enable both low-side and high-side switching characterization via configurable connections. This design is compatible with the 350 MHz current shunt and includes both bulk and high-frequency film capacitors with low stray inductance. The KIT-CRD-CIL12N-XM3 is a paper design that you can download from the Wolfspeed website and use to build your own evaluation board; some of Wolfspeed’s power distribution partners have this dynamic characterization kit available through loaner programs, so that you can test it out in your own lab.
The CRD---DA12E-XM3 inverter reference design is a demonstration in the incredible power density that SiC can provide. Each reference design includes three XM3 modules, three CGD12HBXMP gate drivers, a controller board, optimized bussing, DC link capacitors, current / voltage sensing, and a high-performance liquid cooled cold plate. As the XM3 platform grows, we release new configurations of the CRD---DA12E-XM3, so that users can test out their part number in an inverter; the first commercial module in the platform, the CAB450M12XM3, yields a 300 kW inverter, the CRD300DA12E-XM3. The entire inverter reference design measures just 279 mm x 291 mm x 115 mm for a 9.3 L volume. The CRD300DA12E-XM3 design delivers 32.25 kW/L power density, which is twice as much as that from Si-based inverters, and delivers over 98 percent efficiency. The CRD---DA12E-XM3 is available for purchase with design files available for download through the Wolfspeed website.
Powering Your Application
The XM3 platform powers a wide range of applications and is ideal for high-power, 100 kW – 300 kW, applications. Motor and traction drives, such as those used in railways and heavy equipment, uninterruptible power supplies (UPS), server power supplies, on-board and off-board EV chargers, and applications that require high power density, high efficiency or have large input or output filters can significantly benefit from the new power module.
Contact Wolfspeed now to power your application with the XM3.
1. Guy Moxey, March 2018, “Accelerating Adoption of SiC Power”: https://asets.wolfspeed.com/uploads/2020/12/Accelerating-Adoption-of-SiC-Power.pdf
2. Guy Moxey, June 26, 2019, “Silicon Carbide: Transforming the Future of Power”: https://www.wolfspeed.com/knowledge-center/article/silicon-carbide-transforming-the-future-of-power
3. Claire Simmons, September 23, 2019, “Cree Announces Update to Capacity Expansion Plan - Company to Build World’s Largest Silicon Carbide Device Manufacturing Facility in New York”: https://www.wolfspeed.com/news/cree-announces-update-to-capacity-expansion-plan