Analysis of the Development Status of SiC Power Electronic Devices

2015-08-10

Silicon carbide power electronic devices will play an increasingly important role in improving energy efficiency and realizing miniaturization of power electronic devices. Silicon carbide power electronic devices can improve the efficiency of power utilization and reduce power loss, because compared with silicon devices, silicon carbide devices have advantages in reducing on-resistance and switching loss. For example, in the inverters consisting of diodes and switching tubes, only silicon is replaced by silicon carbide, the power loss of the inverters can be reduced by 15-30%. If the switching tube material is replaced by SiC, the power loss can be reduced by more than half. The power electronic devices made of silicon carbide on a single chip have three characteristics that make the power converter miniaturized: higher switching speed, lower loss and higher operating temperature. Silicon carbide devices can switch at several times the speed of silicon devices. The higher the switching frequency, the easier the energy storage and filter components such as inductance and capacitance are to achieve miniaturization; the lower the power loss, the less the calorific value will be, so the miniaturization of power converter can be realized; and in junction temperature, the silicon device reaches the limit at 200 C, while the silicon carbide device can achieve higher junction temperature and ambient temperature. In this case, the cooling mechanism of the power converter can be reduced or omitted.

With the development of silicon carbide power electronic devices, single-chip silicon carbide devices have not only great advantages in performance, but also advantages in system cost. According to Cree's assessment, using the company's second generation SiC MOSFET and SiC diodes can reduce the total cost of boost converters compared with using silicon IGBT and silicon diodes. Specifically, by increasing the switching frequency to reduce the cost of inductors, the total cost can be reduced to a lower level than when using Si power elements. Taking a 10 kW step-up converter as an example, according to Cree's estimate, the cost of switching on and off at 20 kHz with Si power components is $181.4, while driving at 60 kHz and 100 kHz with SiC power components, the cost will be reduced to $170 and $163 respectively. The use of SiC power components is expected to reduce the total cost of power converters.

In many applications of power electronic devices, such as transmission system, distribution system, electric locomotive, hybrid electric vehicle, various industrial motors, photovoltaic inverters, wind power Grid-connected inverters, air conditioners and other white household appliances, servers and personal computers, silicon carbide devices will gradually show their performance and reduce the system composition. Advantages in this respect. As the main direction of next generation power electronic devices, silicon carbide power electronic devices will bring important technological innovation to power electronics, and promote the development of power electronics in the next two or three decades.


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