How to Unleash the Full Benefits of Silicon Carbide Power Modules

Silicon is traditionally the go-to material for power semiconductors, but recently silicon carbide (SiC) has emerged as an alternative material choice that offers improved performance for high heat, high voltage applications.

SiC power modules feature higher switching frequencies with reduced losses for more compact passive filter components, thus providing higher power density in systems at reduced costs.

Fast switching

Wide-bandgap silicon carbide (SiC) power semiconductors could revolutionize the power module market with faster switching speeds, lower losses, and reduced electromagnetic interference (EMI). But taking full advantage of SiC modules’ advantages requires using an appropriate approach when designing and assembling them – here are a few best practices that may help developers overcome any hurdles and realize its full benefits.

High-speed SiC power transistors have the potential to reduce system voltage by as much as 50% while offering superior harmonic performance, enabling designers to utilize smaller passive components and increase power density. Commutation inductance remains one of the primary challenges associated with SiC devices; to mitigate it, designers may want to incorporate SiC MOSFETs in packages with minimal parasitic inductance.

The SEMITOP E1/E2 power module platform features the latest chip generations across various topologies, such as sixpack, half-bridge and H-bridge topologies. Its pinout is optimized for easier PCB designs and paralleling multiple power modules simultaneously, and features an extremely low specific RDS(on) temperature coefficient that enables fast operation speeds.

Silicon carbide power modules are an excellent choice for applications requiring increased power density, reliability and faster switching speeds. Their wide temperature range and high efficiency make them an attractive option for motor drives and battery chargers alike; furthermore they can withstand large surge currents while offering superior thermal behavior compared to conventional silicon power semiconductors for significant cost savings.

Even with its many benefits, high-speed switching still presents several obstacles to its widespread adoption in industrial applications. These include difficulty accurately testing and measuring switches; circuit parasitics which may cause voltage spikes; noncompliance with EMI regulations; as well as highly complex design and integration requirements of power stages. Thankfully, several best practices can overcome these issues and unleash SiC technology’s full potential in high-speed applications.

Wolfspeed’s LM Power Module Platform leverages silicon carbide’s advantages in demanding power-density applications like electric vehicle chargers and industrial UPSs, such as its innovative 62 mm module package combining SiC switching semiconductors with an industry standard baseplate to produce 175 degC continuous junction temperature operation and features a reliable Si3N4 power substrate to guarantee mechanical robustness against harsh environments, in addition to an AlSiC baseplate with an extremely low junction-to-fluid thermal resistance of 0.15degC/W per switch position for maximum thermal resistance performance and mechanical durability in harsh conditions.

High power density

Traction drives account for much of an electric vehicle (EV)’s energy output, so they must perform with maximum efficiency while taking up minimal space to minimize weight. Furthermore, to maximize range it must generate high power output from small spaces; to do this requires inverters that convert power with higher switching frequencies and reduced losses than traditional silicon IGBTs.

Wide-bandgap silicon carbide (WBG SiC) is the optimal material to meet these performance goals. Compared with conventional Si devices, WBG SiC devices can operate at higher temperatures and voltages without incurring switching losses as seen with silicon devices; additionally it boasts lower switching losses than silicon allowing higher switching frequencies which ultimately increase efficiency and power density.

As such, designers of power conversion systems increasingly rely on silicon carbide devices (SiC). Their benefits are vast; however, using SiC can present its own set of challenges; for instance, its high temperature and power levels can put undue stress on solder joints that reduce power cycling capability significantly. Vincotech has responded by creating an innovative chip-soldering technology which mitigates such stresses to enhance SiC modules’ power cycling abilities.

SiC modules boast superior thermal conductivity over other devices, enabling designers to reduce passive filter component sizes for greater power density while also decreasing heat dissipation needs, thus lowering overall system costs.

SiC can also help reduce the weight and size of power converters due to its much smaller footprint than traditional silicon devices, helping improve system efficiency and reliability while cutting weight and size.

No matter the application, power-converter manufacturers must ensure their modules can meet demanding performance criteria. This includes attaining high switching frequency and low stray inductance – essential elements to maintaining fast edge rates required for optimal performance. Luckily, Wolfspeed’s all-SiC 3.3kV power modules meet these stringent standards thanks to industry-leading current sharing and gate driver strengths.

High efficiency

Wide-bandgap SiC power semiconductors boast significantly reduced losses when compared with silicon counterparts, allowing for higher switching frequencies and smaller passive components. Additionally, SiC can withstand extreme temperatures without losing its performance over time.

These factors enable designers to build more energy-efficient, compact, and cost-effective power conversion systems using SiC modules. Their lightweight yet flexible construction has resulted in weight savings of 20% for rail car traction inverters used on Japan’s Shinkansen train system; similarly EV chargers and railway battery chargers may take advantage of SiC’s increased efficiency and performance.

SiC’s thinner material also reduces commutation inductance, enabling faster switching speeds that result in smaller magnetic filter component sizes and increased power density. A higher switching frequency also lowers ripple voltage for shorter feedback loops with reduced EMI levels; its reduced switching loss reduces power losses further while increasing temperature stability.

Wolfspeed provides an extensive portfolio of silicon carbide modules to meet the requirements of various applications, including AC-DC power-factor correction modules, buck/boost DC/DC modules, bidirectional AC/DC modules and high frequency DC/DC modules that will help designers harness its benefits. Wolfspeed’s portfolio also includes reference designs and evaluation toolkits to assist the design process.

SiC is an attractive choice, yet realizing its full power potential requires addressing certain mechanical properties. These challenges include thermal stress, high operating temperatures and limited power cycling capability – yet Vincotech’s advanced die-attach technology offers solutions to overcome these difficulties by relieving solder joints of stress – the weak link in SiC power modules.

The company’s technology utilizes a patented solder alloy to ensure that power modules can withstand long-term thermal stress without damage to silicon wafers, thus increasing cycle lifetime and decreasing failure risk in demanding medical power supply applications. Furthermore, this advanced technology strengthens bonding between SiC chips and metal substrates, thus further increasing cycling capability of SiC chips.

Robustness

Silicon carbide (SiC), as a wide bandgap semiconductor material, can provide numerous advantages in power conversion applications. These benefits can include improved efficiency, lower costs and smaller size – though in order to realize these potential advantages it’s necessary to overcome various technical design hurdles.

SiC power modules present an additional challenge when it comes to increasing their power cycling capabilities. Power cycling tests simulate real-life events that put strain on internal mechanisms and materials of devices. Industry uses power cycling tests as a benchmark of their performance under differing conditions; to conduct these tests, an alternating current test machine applies high voltage alternating current to devices which causes dissipative events that increase temperature significantly; higher temperatures require greater amounts of energy for them to switch from blocking state to conducting state.

Increased switching energy leads to heat production, shortening device lifespan and increasing risk for short circuit or avalanche breakdown. Under such conditions, SC failures or avalanche breakout may occur, rendering these devices nonfunctional and ultimately failing completely.

Traditional solutions have included adding additional components into circuits to protect devices, but this increases overall cost and complexity of power converters. As a result, Danfoss has come up with an innovative new bonding and joining technology known as Bond Buffer that effectively resolves these issues.

This patented technique utilizes copper wire bonding and sintered die attach to replace solder joints in modules, enabling them to operate at higher maximum junction temperatures without degrading current, as well as improving reliability and extending power cycling capability.

Vincotech’s SiC module platform brings together the speed and efficiency of silicon carbide MOSFETs with industry standard 62 mm packaging for maximum user benefit in low inductance applications such as industrial motor drives, EV chargers or battery powered applications.

Vincotech’s SiC modules demonstrated superior power cycling capability compared to competitive offerings using conventional solder alloy. This improvement can be attributed to its improved ability to absorb and dissipate thermal energy efficiently.