How Do You Optimize Silicon Carbide (SiC) Device Performance?
Commercial interest in Silicon carbide (SiC) has significantly increased over the last several years as this novel semiconductor can amplify power management capability. Such performance is achieved by amalgamating higher power density and better efficiency with reduced form factors. Applications that harness SiC technology range from electric vehicles (EVs) and charging stations to smart power grids and industrial and aeronautical power systems. Some challenges, however, crop up with trying to drive SiC devices fast, such as system noise, short-circuits, overvoltage, and overheating. These tend to decrease overall efficiency and reliability.
Microchip has adopted a digital approach to controlling SiC devices while maintaining the highest efficiency and reliability levels. Standard analog solutions are excellent alternatives for Silicon devices, but analog control is unreliable for SiC devices and often suffers from varying degrees of ringing, overshoots, and undershoots. New digital programmable gate driver solutions from Microchip tame the SiC beast. The Augmented Switching Accelerated Development Kit (ASDAK) includes the hardware and software elements required to rapidly optimize SiC modules. This new kit enables designers to adjust system performance through firmware upgrades using the AgileSwitch Intelligent Configuration Tool (ICT) and a Device Programmer. Kit applications include heavy-duty traction vehicles, auxiliary power units in trains, buses, and trolleys, Electric Vehicle (EV) charging, and other high-power industrial systems.
Let's Take a Closer Look at Augmented Switching Technology
Augmented Switching technology for digital programmable gate drivers provides precise settings to turn on and turn off the devices, which softens the edges of a gate's output. Augmented Switching technology also reduces voltage overshoot and ringing, while optimizing system efficiency and minimizing EMI (Figure 1). By reducing turn-off spikes and ringing under normal operation and short-circuit (DSAT) conditions, SiC MOSFET modules can be safely operated at higher frequencies, enabling dramatic increases in power conversion density. This allows SiC MOSFET modules to operate closer to their rated specifications, resulting in size, cost, and performance improvements. This robust technology generally brings 80 percent lower VDS overshoot, 50 percent lower switching, and faster short circuit protection.
Figure 1: Comparative analysis of Analog vs. Digital programmable gate driver operations (Image Source: AgileSwitch.com)
The benefits continue in the form of a significant reduction in development time from benchtop testing to system-level production. AgileSwitch Digital Programmable Gate Drivers offer multiple configurability levels that allow system designers to fine-tune performance curated to their specific systems and applications.
Microchip provides many development kits for productive design with digital gate drivers. One significant advantage to the Microchip solution is their ability to is bundle the gate driver and SiC power module together. Designers are not obligated to individually procure each device. As Microchip's gate drivers already qualify for end-product production, engineers may skip the step of developing their own gate drivers. The Augmented Switching Accelerated Development Kit with Module (ASDAK+) series from Microchip is compatible with 1200V and 1700V SiC Power Modules, and packs an SP6LI SiC module, gate driver board, mounting hardware, programmer, cables, and a link to the ICT, allowing the designer to start testing right out of the box (Figure 2). The primary device parts include:
- 1 x 1200V SP6LI Low Inductance SiC module: The SP6LI module unifies Microchip’s in-house die production and rugged low-inductance power packaging. This a robust phase leg option with low Rdson, high temperature performance, and a stable body diode. The module provides high efficiency and performance at high-frequency operation for applications in welding converters, switched-mode power supplies, uninterruptible power supplies, EV motors, and traction drives. Each kit includes one of the following modules:
- 1 x AgileSwitch 2ASC-12A1HP – 1200V core: The 2ASC driver cores in this kit are fully qualified for production use. They are designed for harsh, high-noise environments, with optional conformal coating. AgileSwitch's patented, configurable Augmented Switching technology comes standard. Each 2ASC driver core is equipped with diagnostic and troubleshooting tools that continuously monitor critical parameters, such as short circuit, temperature, and DC link voltage.
- 1 x SP6CA1 – 1200V SP6LI module adapter board: The AgileSwitch SP6CA1 – 1200V SP6LI Core Adapter Board is an evaluation tool designed to work with the 2ASC-12A1HP SiC Driver Core. The combination is used with the Microchip SP6LI SiC Power Modules.
- 1 x – ASBK-014 device programmer kit: ASBK-014 kits include a programmer, adapter board, and cables that enable a PC to be connected to an AgileSwitch Digital Programmable gate driver core or board. These kits are required to change configuration parameters using the Intelligent Configuration Tool (ICT).
- 1 x – ICT Software: ICT is used to adjust the configurable parameters to optimize your system's performance. The ICT offers different drive parameters, including On/Off Gate Voltages, DC Link and Temperature Fault Levels, and Augmented SwitchingTM profiles.
- 1x – ASBK-015 Hardware mounting kit: ASBK-015 kit contains everything needed to mount and connect the gate driver to the power module. Stand-offs, screws, tools, and cable assemblies are all included to make the Vgs, NTC, and DC Link connections easy and straightforward.
Figure 2 series SiC Module (Image Source: Microchip)
Impact on Gate Driver Augmented Switching
Incremental changes to the Augmented Switching profiles can yield dramatic improvements in switching efficiency, overshoot, ringing, and short-circuit protection. Inserting one or multiple intermediate levels in the gate voltage between on and off (Figure 3) reduces ringing, switching losses, and inductance-induced overshoot voltages. This also helps reduce stress on the component during short circuit conditions.
Figure 3: Augmented turn-off uses one or more intermediate voltage steps to reduce ringing, losses, and overshoots.
Power management plays a major role in virtually every piece of electronic equipment. If you'd like to know more about how to approach power management in your designs or products, click here for more information.
- The OptiMOS Power MOSFET Source-Down Family
- Augmented Switching Accelerated Development Kit
- Silicon Carbide MOSFETs
- Selecting a Synchronous Buck Converter for a (POL) Application
- Benefits of Isolated DC-DC Converters for Gate Drive Power
- How System Power Protection ICs Prevent Field Failures and Unexpected Downtime
- The Benefits of a Compact Power Management IC and Power Loss Protection
- How to integrate multiple PMICs to build customized power management and safety solutions for complex SoCs
- The Benefits of Bidirectional Buck-Boost Controllers
- Wide-Input Buck-Boost DC/DC Converters