SiC and GaN Again a Major Focus at PCIM Europe

Among the companies making announcements in silicon-carbide (SiC) and gallium-nitride (GaN) semiconductor devices were Toshiba Electronics Europe, ROHM, Cree, Transphorm and GaN Systems. Announcements included a hybrid N-channel injection-enhanced gate transistor (IEGT), high-voltage N-channel SiC MOSFETs, GaN HEMT devices and SiC modules.

Toshiba Electronics Europe announced a hybrid N-channel IEGT module that features an embedded SiC fast-recovery diode (FRD). The high-efficiency PMI (Plastic case Module IEGT) will help designers to save energy, space and weight in high-power switching, inverter and motor control applications. Rated at 1700V and 1200A, the half-bridge MG1200V2YS71 is ideal for switching in industrial, rail traction, renewable energy and electricity transmission and distribution systems. The module incorporates two switches (IEGTs), each with its own embedded SiC diode.

Use of an SiC diode leads to a significant decrease in reverse recovery current and a corresponding decrease in turn-on loss. As a result the new PMI offers a reverse recovery loss up to 97% lower than a module with a conventional silicon diode. This improvement in efficiency has allowed Toshiba to realize a cooling system that is much smaller than its silicon-based predecessor. In addition, thanks to the size reduction of some motor control parts, overall equipment size could be reduced by as much as 40%.

The new module has an isolation rating of 6000Vac (rms for one minute) and will operate with junction temperatures from -40°C to 150°C. As well as size, weight and efficiency improvements, use of the PMI module in applications such as rail traction can also lead to improved ride quality and lower acoustic noise.

Adding to its broad range of SiC products, ROHM presented its new line-up expansion of high-voltage N-channel SiC (Silicon Carbide) Power MOSFETs. The SCT2xx series without Schottky diode features different ON-resistance types and max. currents in a TO247 package without an integrated SiC SBD. They provide significantly lower power loss and handle a maximum junction temperature of 175°C which is unmatched in the market. The SCH2080KEC variant comes co-packed with a SiC SBD in a single package.

With low on-resistance, high breakdown voltage, high speed switching and reverse recovery these new MOSFETs (SCT2080KEC, SCH2080KEC, SCT2160KEC, SCT22280KEC and SCT2450KEC) are easy to parallel and to drive which makes them ideal for deployment in solar inverters, DC/DC converters, switch mode power supplies, induction heating or motor drives. Overall, these devices not only enable power saving and high speed operation but also the reduction of space and components, and can be configured based on customer requirements.

Current Si IGBTs commonly used in 1200V-class inverters and converters cause power switching loss due to tail current or recovery of the external FRD, bringing a need for SiC power MOSFETs capable of operating with low switching loss at high frequencies. However, conventional SiC power MOSFETs experienced numerous reliability problems, including characteristic degradation due to body diode conduction (e.g. increased ON resistance, forward voltage, and resistance degradation) as well as failures of the gate oxide film, making full-scale integration impossible. ROHM has succeeded in overcoming these problems by improving processes related to crystal defects and device structure and reducing ON resistance per unit area by approximately 30% compared to conventional products, also leading to increased miniaturization.

Transphorm announced the implementation of a high efficiency off-line 1 kW 48 Vdc power supply that has demonstrated peak efficiency of 97.5 percent. The power supply design utilizes Transphorm’s JEDEC-qualified GaN on silicon 600V high electron mobility transistors (HEMTs) to implement a 99-percent-efficiency totem pole power factor correction (PFC) front end, combined with a 98.6% efficiency LLC converter. A prototype circuit was on display during the event.

Based on Transphorm’s patented, high-performance EZ-GaNTM technology, the TPH3006PS HEMT combines low switching and conduction losses to reduce energy loss by 50 percent compared to conventional silicon-based power conversion designs. The TO-220-packaged GaN transistor features low on-state resistance (RDS(on)) of 150 milliohms (mΩ), low reverse-recovery charge (Qrr) of 54 nanocoulombs (nC) and high-frequency switching capability — all of which result in lower loss, more compact, lower cost systems.

“Transphorm’s GaN-based power supply design exceeds the best efficiency results possible with silicon by at least one percent,” said Umesh Mishra, CEO of Transphorm, Inc. “And while recent advances in super junction silicon devices have reduced the output capacitance by 20 percent and the Qrr of the intrinsic body diode by 25 percent, these improvements lag far behind the effective Qrr of the new GaN transistors which reduce Qrr by 95 percent.”

For approved customers, the TPH3006PS and TPH3006PD HEMT devices are available for sale at a price of $5.89 each in 1,000 quantities. The TPS3410PK and TPS3411PK diodes are priced at $2.06 and $1.38, respectively, also in 1,000-piece quantities.

When compared to state-of-the-art silicon modules, Cree’s new SiC 1.2 kV, 50A modules deliver performance equivalent to silicon modules rated at 150A. “The efficient switching of the SiC module allows us to use them with significantly less derating than silicon IGBTs,” stated Dr. Jun Kang, research and applications manager, Yaskawa America, Inc. “This feature enables significantly higher frequency operation, which both increases fundamental output frequency and reduces passive component size in the motor drive.”

“Cree’s SiC power module family can also provide significant benefits to applications such as solar inverters, uninterruptible power supplies (UPS) and industrial power supplies,” explained Mrinal Das, product marketing manager, Cree Power and RF. “Even when designers simply substitute Si modules with SiC in motor drive applications, the improved performance of SiC reduces power losses, leading to reduced cooling requirements and, in turn, to a reduction in size, weight, complexity and the overall cost of the power electronics system.”

GaN Systems announced the strengthening of its European design team with the news that industry-veteran Nigel Springett is joining company as Applications Consultant, based in Emmendingen Germany. In this role he will assist customers with the early adoption of the company’s gallium nitride power switching transistors.

“Nigel brings a wealth of experience in the application of compound semiconductors. This expertise will be of great value to our customers as we work with our development partners to bring their emerging gallium nitride products to fruition”, said Girvan Patterson CEO of GaN Systems. “In addition extends our European capabilities, following the recent opening of our UK office.”

By increasing the support services in offers, GaN Systems is aiming to demonstrate to design engineers that gallium nitride is a very real ‘now’ technology that can offer immediate performance benefits in a wide range of power electronics applications including renewable energy and smart grid, automotive and UPS and motor control.