Silicon carbide (SiC) taking over power semiconductor market
Date: 15/01/2014
The DC voltage produced by solar PV cells is not in the right range of voltage to power most of the electrical and electronics appliances and devices. Even a mobile phone cannot be charged directly from a solar PV without using DC/DC converter circuit because voltages produced by Solar PV is unregulated and its voltage rating is wide. Most of the appliances in the home which operate from AC mains voltage require an inverter to convert solar DC voltage into AC mains voltage. There is lot of power switching involved both in inverters and in converter. The traditional pure-silicon power switching devices MOSFET, rectifier-diodes and IGBT used in inverters and converters are found to be energy in-efficient compared to compound semiconductor material based power switching devices for their ability to reduce switching losses, and increase the power conversion efficiency of both inverters and converters.
The wide band gap compound semiconductor material silicon carbide (SiC) offers higher thermal conductivity as well as higher breakdown voltage compared to silicon. They can switch at higher frequencies at higher efficiencies and by generating less heat compared to pure-silicon semiconductor devices. There is also another important benefit of size, SiC semiconductor devices have higher power density compared to silicon devices, so they occupy less space for the same power. Not only the size of switching devices, even the inductor and capacitors used in inverters and converters can be of small size due to the ability of silicon carbide devices to operate at higher frequencies. At higher frequencies a smaller value of capacitor and a smaller value of inductor can be used instead of larger value capacitors and inductors which are going to consume huge space on the board.
SiC devices can operate over a wide range of voltages due to which the inverters based on SiC devices can generate stable output power from unstable wide range DC voltage from solar PV cells which are exposed to un-uniform sunlight due to various weather conditions and position of sun. By using SiC based power conversion and other technologies solar PV inverters can be made more reliable power source.
Due to the high power conversion efficiency in the range of 95 to 97%, the same inverter can be used with less number of solar PV panels as well as large number of solar PV panels.
One of the leading solar power inverter manufacturer which is effectively using silicon carbide is Power-One, whose brand named Aurora is a very successful inverter around the world.
Not only in solar power inverters, even in electric cars, lighting and in many industrial inverters market, the silicon carbide and other wide bandgap compound semiconductor are sure to replace silicon in the coming years at faster pace.
There are also efforts by semiconductor researchers to employ wide band-gap semiconductor material instead of silicon in the deep node CMOS chips, but they are still trying it hard to make it successful for the cost and process disadvantages.
Another interesting compound semiconductor material explored for power semiconductor is Gallium Nitride (GaN), for time being SiC is more preferred over GaN.
Author: Srinivasa Reddy N
