Uncertainty hangs over the market for power devices made with the wide-bandgap semiconductor SiC (silicon carbide), due to uncertainty as to when EVs (electric vehicles) will adopt them for various applications under the hood, according to a recent study by analyst firm Yole Développement.
Validation is a slow process, as automotive qualification lasts up to five years. Although qualification for charger inverters for HEVs (hybrid electric vehicles) or full EVs is a few years shorter, SiC faces competition from other, more established devices.
Among the more commonly used devices, we find silicon superjunction MOSFETs, IGBTs (insulated-gate bipolar transistors), and wide-bandgap gallium nitride (GaN) devices. In general, SiC benefits from its ability to remain chemically stable at high temperatures with a relatively high electrical breakdown voltage and high frequency of operation in circuits. Yole's best-case scenario prediction for SiC devices such as transistors and diodes would lead to commercialization in EVs starting in 2015, grasping 11 percent of the market from silicon IGBT devices by 2020.
On the bright side, a more bullish assessment has been devised for SiC power control device usage in PV (photo-voltaic) solar inverter applications, since it has already broken into that market. Most inverter manufacturers have at least one model with SiC-based chips in them, helping boost SiC power device industry revenue to $76 million in 2012, not counting defense-related applications. PV inverter producers are the second industry to broadly adopt SiC devices, after manufacturers using SiC for power factor correction in high-end computer server power supplies.
Some PV inverter manufacturers use a SiC diode and a silicon IGBT or MOSFET; others offer full SiC inverters instead of silicon-based devices. Thus, inverter producers are selling more expensive SiC products just on the efficiency of the devices. They choose to ignore SiC's advantageous high-frequency and high-temperature capabilities. Their designs could benefit from the additional advantages that would streamline inverter systems by reducing the number of capacitors and inductors required.
The SiC market growth slowed last year overall, but the PV inverter segment remained strong. In 2011 and 2012, the SiC diode business was partially driven by microinverter applications; however, Yole expects JFET and MOSFET applications to accelerate the next three years and become dominant in revenue by 2016.
System Plus Consulting and Yole recently completed a more in-depth study of the benefits of increasing the standard PV inverter switching frequency from 12kHz to 32kHz and found that the higher frequency shortens the payback time for the SiC return on investment. As a result, 50kW SiC inverters would be cheaper than their silicon equivalents by 2020. If this scenario plays out as expected by Yole, it would boost annual revenue for SiC devices sold into PV inverters to $200 million by 2020.
However, even though PV inverters are much more established, EV and HEV inverter producers would be able to better leverage the overall technical advantages of SiC over silicon-based devices. Note that the stagnant market for electric cars will not help the cause of SiC for these applications nor will falling gasoline prices.