GaN has the potential to replace silicon boosting EV performance and cutting costs
Dr. Daniel Sherman VP of R&D Visic Technologies presents the case
There is a growing interest in using GaN over other solutions such as silicon-based integrated circuits and Silicon Carbide (SiC), according to sales forecasts, the most profitable market will be the one involving electric mobility and self-driving vehicles,
e-motec. What is the key difference between gallium nitride (GaN) and silicon?
DS. Silicon chips have been used in power applications for decades and GaN simply performs better. Engineers can use GaN to create power electronics systems that are 4× smaller and lighter and have 4× less energy loss than Si-based systems GaN chips are four times smaller and lighter and cut power losses by four times, often at reduced cost. They require fewer materials to produce. This is what’s driving demand away from silicon to GaN power. These are not only two different semiconductor materials with different solid state physics properties, but also the conduction channel principle is different.
These differences bring about performance advantages:
- Lower capacitances per voltage and resistance rating -> significantly better switching and conduction efficiency.
- No built-in body diode -> no diode reverse recovery losses.
- Gradually with optimization GaN technology exhibits lower costs then Si.
e-motec Can you tell us a little about Visic’ GaN technologies?
DS. Our D3GaN technology platform utilizes a d-mode GaN device which provides highly-reliable GaN gate structure that helps provide the overall system robustness and reliability required in the automotive market. Additionally, in the D3GaN approach, the series-connected Si Mosfet does not participate in the switching operation, therefore allows to fully employ the advantageous switching performance GaN HEMT provides.
For inverter applications, the ability to parallel GaN devices is paramount, and the D3GaN topology was a priori designed in a manner which support device paralleling. Together with the already highest current rating per die (i.e. 200Amp), VisIC’s solution paves the way to the simplest system implementation that meets the high power demand from the automotive market.
Additional exciting system development, aimed for 800V application by utilizing the proven 650V rated devices is the 3 Level flying capacitor Inverter. This design showcase our GaN devices capabilities to improve 800V Electric Motor inverter systems by lowering the phase current ripple and improving drive cycle efficiency. On this topic, VisIC recently announced another route moving forward by leveraging a cooperation with the well-established Hofer powertrain expertise in building 3-level power solutions.
This design also showcases the optimal heat dissipation design with its isolated top cooling SMT packaging solution with up to 100Arms output phase current. The 3-level topology provides lower total losses versus standard 2-level approach. The D3GaN power switches provides best performance to improve efficiency and TCO.
The design can operate as a 3-level inverter in Open Loop and in a Multi Pulse configuration.
e-motec. Lithium-ion batteries, for example, can take up to 30 percent of an EV’s cost price. How will GaN-based components help reduce these costs?
DS. GaN technology can improve the efficiency of the inverter and therefore increase the driving range between successive battry charges. GaN based technology allows opens the door towards faster motor frequencies, which in turn will provide even more efficient motors. Alternatively, efficiency increase can enable to keep the same driving distance and reduce the required battery capacity. To show case the potential based on real life examples, according to publication, Tesla where able to increase the drive range by 10% only by a 4% improvement in the efficiency of the inverter.
e-motec. Current manufacturing processes are the limiting factor for both gallium nitride and silicon carbide. Like any innovative technology, it needs an acceptable performance/cost ratio for entry to the mass market. How is Visic addressing this issue?
DS. We are developing next generation technology which improves the utilization of the semiconductor area. Meaning for a specific application we will need lower semiconductor area. From a manufacturing perspective – GaN technology has fundamental advantages over SiC in both starting material cost and fabrication process. Unlike SiC devices, GaN technology can utilize the existing “aging” Si manufacturing lines, this helps in finding the required allocations.
e-motec. As electric vehicles enter the mainstream, demand for critical semiconductor components will increase for vehicle manufacturers. That makes strategic partnerships with GaN providers even more important.
How is Visic placed to serve this demand?
DS. We have built a strong supply chain, and long standing partnership with industry leading companies. Our partners are aware to the dramatic volume manufacturing requirement and are ready to deliver. Note that today, GaN has shorter lead times than Si based solution. The biggest factor in why GaN is important to EVs is the substantial number of semiconductors used in EV’s. There are about $200 worth of semiconductors in an ICE vehicle, compared to about $600 in semiconductors in an EV. That $400 is a huge new market.
We are targeting specific applications in the automotive market and being focused helps us in providing the best service to our customers. We are also collaborating with our suppliers to meet the required demand in the future years. We are working on several projects in this field and are closely collaborating – the development is still confidential.
Daniel Sherman VP of R&D Visic Technologies.
