The Application of SiC Devices in Aviation Secondary Power Supply
Introduction
During flight and when the aircraft is parked, it experiences a wide range of rapidly changing climatic conditions. As a result, the working environment for aviation electrical equipment is more complex than that of ground-based industrial equipment, leading to higher demands on the aircraft power system.
The secondary power source is a critical component in the power system, including devices like aeronautical static converters, transformer rectifiers, DC-DC converters, and motor drivers. These systems operate under harsh conditions and require high performance, reliability, compact size, low weight, and efficient energy use. Currently, most aviation secondary power sources are based on silicon (Si) devices. However, after 60 years of development, the performance of Si power electronics has reached its theoretical limits, making further improvements difficult. This poses a challenge for the advancement of aviation power systems.
Researchers have made significant progress in developing wide bandgap semiconductor materials such as SiC. SiC power devices offer high temperature resistance, radiation tolerance, high breakdown voltage, and fast switching speeds, making them ideal for harsh environments. Compared to traditional Si devices, SiC can significantly reduce power losses, enabling smaller, lighter, and more reliable power electronic components. This makes SiC highly promising for future aviation secondary power supply systems.
2. Advantages and Development of SiC Devices
As one of the most widely used wide-bandgap semiconductors, SiC is considered the third-generation semiconductor after Si and GaAs. It has broad potential in power electronics. Table 1 compares the electrical properties of SiC with those of Si.
From Table 1, we can see:
1) SiC has a large bandgap, allowing operation at temperatures up to 600°C and offering excellent radiation resistance. High-temperature integrated circuits operating at 350–500°C are used in aerospace, nuclear, satellite, and geothermal applications.
2) The breakdown electric field of SiC is about 2.5 MV/cm, ten times that of Si. This enables SiC devices to operate at much higher voltages, making them suitable for high-voltage requirements in aviation systems.
3) The specific on-resistance of SiC is much lower than that of Si. At the same voltage level, SiC devices have only 1% of the on-resistance of Si devices, reducing losses and increasing efficiency.
4) SiC has high thermal conductivity, nearly three times that of Si. This allows for reduced or eliminated heat dissipation systems, improving integration and reliability in high-temperature and high-radiation environments.
5) SiC has a high electron saturation velocity, supporting high-frequency and high-power applications.
Currently, countries like Europe, the US, and Japan lead in SiC crystal production. Companies such as Cree, Infineon, and others are actively manufacturing SiC chips. Despite challenges in cost and reliability, the adoption of SiC is accelerating. Global investment in SiC exceeded $1 billion by 2011, and the market is expected to grow rapidly, reaching $8 billion by 2019.
Domestic research on SiC power devices started later due to material and equipment limitations. Institutions such as Xi'an University of Electronic Science and Technology and the Chinese Academy of Sciences are conducting research. China's Tianke Heda Blu-ray Company has also influenced the global SiC substrate market, helping to reduce costs and promote wider adoption.
3. Application of SiC Devices in Aviation Secondary Power Supply
Based on the advantages of SiC devices, their application in aviation secondary power systems is analyzed below.
3.1 Application in Aeronautical Static Inverters
A static inverter (ASI) converts DC power into AC for aircraft systems. It typically converts 270V DC to 115V/400Hz AC. The preamplifier stage requires high voltage isolation and low conduction loss. SiC devices offer much lower on-resistance compared to Si, improving efficiency. High-voltage SiC Schottky diodes are needed for the secondary side rectification.
The inverter stage is crucial for efficiency and power density. Using SiC devices increases switching frequency, significantly improving efficiency. For example, at 100 kHz, full SiC inverters can be 8% more efficient than all-Si inverters.
3.2 Application in Transformer Rectifiers
Transformer rectifiers convert AC to DC for various aircraft systems. Multi-pulse rectifiers are used in modern aircraft like the B787 and A380. SiC Schottky diodes are preferred due to their fast recovery and high-temperature tolerance, reducing switching losses and heat dissipation needs.
3.3 Application in DC-DC Converters
DC-DC converters are essential for power distribution in aircraft. Using SiC-MOSFETs reduces system losses and lowers temperatures. For example, in a 270V to 28V converter, SiC devices allow higher switching frequencies and better efficiency.
3.4 Application in Motor Drivers
Motor drivers in aviation systems benefit from SiC’s high temperature resistance and low reverse recovery current. This improves efficiency, reduces size and weight, and enhances reliability. As SiC fabrication processes mature, they will further optimize motor driver designs.
Digit Segment Led Display,Washing Machine Display,Smd Led Display,Bar Segment Led Display
Wuxi Ark Technology Electronic Co.,Ltd. , https://www.arkledcn.com