Implementation of a Si/SiC Hybrid Optically Controlled High Power Switching Device

摘要

The ever-increasing performance and economic requirements placed on commercial and military aircraft are resulting in the need for very complex avionic systems. To help alleviate some of the design complexity, fiber optic components have been suggested as an enabling technology that could allow the creation of an optical communications network routed throughout the avionic systems of an aircraft. Based on the often-cited benefits of high data throughput, immunity to EMI, reduced maintenance costs and reduced weight, the use of fiber optic links to communicate control signals and sensor information throughout the aircraft could lead to significant performance improvements for next generation aircraft. Fly-by-Light systems that use optical control signals to actuate the flight surfaces of an aircraft have been suggested as an important technology for avionic systems where degradation of signal integrity due to EMI can have catastrophic consequences. Current fly-by-light systems are limited by the lack of optically activated high-power switching devices. The challenge has been the development of an optoelectronic switching technology that can withstand the high power and harsh environmental conditions common in a flight surface actuation system. Wide bandgap semiconductors such as Silicon Carbide offer the potential to overcome both the temperature and voltage blocking limitations that inhibit the use of Silicon. Unfortunately, SiC is not optically active at the near IR wavelengths where communications grade light sources are readily available. Thus, we have proposed a hybrid device that combines a silicon based photoreceiver module with a SiC power transistor. When illuminated with a 5mW optical control signal the silicon chip produces a 15 mA drive current for a SiC Darlington pair. The SiC Darlington pair then produces a 150 A current that is suitable for driving an electric motor with sufficient horsepower to actuate the control surfaces on an aircraft. Further, when the optical signal is turned off, the SiC is capable of holding off a 270 V potential to insure that the motor drive current is completely off. We present in this paper the design and initial test results from a prototype device that has recently been fabricated.