SiC Enables more efficient power solutions

Article By : Maurizio Di Paolo Emilio

SiC technology is now widely recognized as a reliable alternative to silicon. Many manufacturers of power modules and power inverters have laid the foundations for SiC use in their product roadmaps.

Demand continues to grow rapidly for silicon carbide (SiC)-based devices to maximize efficiency and reduce size and weight, enabling engineers to create innovative power solutions. Applications that leverage SiC technology range from electric vehicles (EVs) and charging stations to smart power grids and industrial and aeronautical power systems.

New digital programmable gate driver solutions help accelerate the process from design to production. The higher electric field strength of SiC substrates permits the use of thinner base structures. Silicon carbide is also excellent in its voltage resistance but not very good in standup short-circuit conditions. The new gate drivers have been designed to address problems such as system noise, short-circuits, overvoltage, and overheating.

SiC technology

SiC technology is now widely recognized as a reliable alternative to silicon. Many manufacturers of power modules and power inverters have laid the foundations for SiC use in their product roadmaps. “The [market] growth in silicon carbide power semiconductor devices has doubled over the last three years,” said Orlando Esparza, strategic marketing manager at Microchip Technology. “There’s a lot of optimism in the market that it will reach up to US$10 billion within the next seven to 10 years. We are seeing rapid adoption [for SiC], and we are working on a large number of opportunities globally. These opportunities span across many different types of applications within industrial, automotive, medical, aerospace and defense, traction or train, and more.”

SiC power technology allows EV and other high-power switching applications to achieve maximum efficiency, said Esparza. “Silicon carbide serves the needs of applications requiring system voltages of 600 V and above. We’re seeing a lot of opportunity for our 700-V and 1,200-V devices within electric-vehicle applications that have either a 400-V or an 800-V bus, [as well as in] industrial medical equipment that is in the higher-voltage range.”

System designers are adopting SiC solutions to overcome the efficiency limitations of traditional, silicon-based devices, he added. “Silicon carbide allows their systems to be smaller and lighter-weight, and the overall system cost is actually lower.”

Microchip’s new power modules include commercially qualified Schottky barrier diodes (SBDs) at 700, 1,200, and 1,700 V to maximize switching efficiency, reduce heat gain, and reduce system footprint. Available topologies include dual diode, full bridge, phase leg, dual common cathode, and three-phase bridge, and multiple current and package options are offered.


Figure 1: What’s driving the adoption of SiC in power electronics?
(Image: Microchip Technology)


The addition of SiC SBD modules in designs maximizes switching efficiency, reduces thermal gain, and allows for a smaller system footprint. High device performance enables system designers to minimize the need for snubber circuits by leveraging the stability of the diode body without long-term degradation (Figure 1). Microchip offers several reference designs to accelerate design development. The MSCSICSP3/REF2 reference design provides an example of a highly isolated SiC MOSFET dual-gate driver for the SiC SP3 phase leg modules (Figure 2).

Figure 2: MSCSICSP3/REF2 reference design
(Image: Microchip Technology)

It can be configured by switches to drive in a half-bridge configuration with only one side on at any time and with dead-time protection. The low-inductance SP6LI driver reference design implements a half-bridge driver up to a 400-kHz switching frequency (Figure 3). The MSCSICPFC/REF5 is a three-phase Vienna power-factor–corrected (PFC) reference design for hybrid EV/EV chargers for 30-kW applications (Figure 4).

Figure 3: Low-inductance SP6LI driver reference design
(Image: Microchip Technology)

Figure 4: MSCSICPFC/REF5 is a three-phase Vienna PFC reference design
(Image: Microchip Technology)

The Vienna 30-kW three-stage PFC, the SiC, and the SP3/SP6LI modules drive reference projects and boards that provide system developers with tools to reduce development cycle time. Power-factor correction is critical in addressing the sources of potential loss and should be implemented accordingly.

Digital gate drivers

Microchip’s AgileSwitch digital gate drivers effectively reduce EMI problems and switching losses by up to 50% (Figure 5). Digital solutions are designed to address the critical challenges that arise in operating SiC and IGBT power devices at high switching frequencies. They can switch at up to 200 kHz and provide up to seven different failure conditions and monitoring conditions.

Figure 5: Digital gate driving is superior to analog driving. (Image: Microchip Technology)

“Our gate drivers were designed to address all of these issues such as noise in the system, short-circuit overheating, and overvoltage,” said Rob Weber, product line director for AgileSwitch at Microchip Technology. “We put in a lot of functionality with regard to these critical issues that emerge when you’re trying to drive silicon carbide.”

The drivers feature Microchip’s Augmented Switching technology and robust short-circuit protection and are fully configurable via software. They are optimized for transportation and industrial applications, including inverters and induction heating. “We turn the switch on and off in steps where we modify the voltage and the time at the different voltage level for the both the turn-on and the turn-off,” said Weber.

Microchip provides numerous development kits for productive development with digital gate drivers. The 62-mm Electrical Master Plug and Play SiC Gate Driver is optimized for traction, heavy-duty vehicle, and induction heating applications. The Augmented Switching Accelerated Development Kit (ASDAK) includes the hardware and software elements required for rapid optimization of SiC module and system performance, giving system designers the flexibility to adjust system performance through software updates using the Intelligent Configuration Tool (ICT). The ICT offers configuration of several drive parameters, including on/off gate voltages, DC link and temperature failure levels, and increased switching profiles.

By reducing turn-off spikes and ringing, under normal operation as well as under short-circuit (DSAT) conditions, SiC MOSFET modules can be safely operated at higher frequencies that enable dramatic increases in power conversion density. This allows SiC MOSFET modules to be operated closer to their rated specifications, resulting in size, cost, and performance improvements.


This article was first published on EE Times Europe

Leave a comment