ONE、 Silicon carbide SIC MOSFET characteristics

The higher the voltage withstand device is in the Si material, the larger the on resistance per unit area is (increased in the proportion of the voltage withstand value to the power of about 2~2.5). Therefore, IGBT (insulated gate bipolar transistor) is mainly used for voltages above 600V.

IGBT injects holes as minority carriers into the drift layer through conductivity modulation, so the on resistance is smaller than that of MOSFET. But at the same time, due to the accumulation of minority carriers, tail current will be generated during turn off, resulting in great switching loss.

The impedance of the drift layer of SiC devices is lower than that of Si devices, so high withstand voltage and low impedance can be achieved with MOSFET without conductivity modulation. In addition, MOSFET does not produce tail current in principle, so when SiC MOSFET is used to replace IGBT, switching loss can be significantly reduced, and miniaturization of heat dissipation components can be realized. In addition, SiC MOSFET can be driven under the high-frequency condition that IGBT cannot work, so it can also realize the miniaturization of passive devices. Compared with 600V~900V Si MOSFET, SiC MOSFET has the advantages of small chip area (small package can be realized) and very small recovery loss of body diode. It is mainly used in inverter or converter of industrial machine power supply and high efficiency power regulator.

With the improvement of SiC MOSFET fabrication technology and the solution of driving problems, it will be widely used in the field of high frequency switching in power electronics.

TWO、 Advantages of silicon carbide SIC MOSFET replacing traditional MOSFET and IGBT

Advantages of silicon carbide MOS: high frequency, high efficiency, high voltage withstand and high reliability. It can achieve energy saving and consumption reduction, small size, low weight and high power density. Compared with traditional MOSFET and IGBT, it has the following advantages:

1. High operating frequency: the operating frequency of traditional MOSFET is about 60KHZ, while that of silicon carbide MOSFET is 1MHZ.

Purpose: High frequency operation can reduce the volume of capacitance, inductance or transformer in the power supply system, reduce the power supply cost, and make the power supply miniaturized and beautiful. So as to realize the upgrading of power supply.

2. With low on impedance, the minimum internal resistance of silicon carbide MOSFET single tube can reach 15 milliohms, which is unimaginable for traditional MOSFET.

Purpose: easily meet the requirements of energy efficiency, reduce the use of heat sink, reduce the volume and weight of power supply, lower power temperature, and higher reliability.

3. The withstand voltage is high. At present, the withstand voltage of silicon carbide MOSFET in mass production can reach 3300V, the withstand voltage of general MOSFET is 900V, and the withstand voltage of IGBT is 1200V.

4. High temperature resistance, silicon carbide MOSFET chip junction temperature up to 300 degrees, reliability, stability is much higher than traditional MOSFET.

Therefore, the use of silicon carbide MOSFET can enable the power supply to achieve high efficiency and small size. In some high temperature and high voltage environments, it must not be used.