Silicon carbide diodes are becoming increasingly significant in various power electronics applications.
Silicon carbide (SiC) devices are intensively being adopted in an ever-increasing number of applications, ranging from otherwise traditionally “low-tech” applications such as washing machines, where power inverter technology is used, through to EV charge points, inverters and, increasingly, industrial power equipment. One of the key technology differentiators is the switching performance of the SiC diode which leads to a cascade of further attributes in terms of efficiency, reliability and general standards of performance in higher power applications.SiC Diode switching characteristics can be affected by a number of factors. They are:
Switching Speed
The major benefit of using SiC diodes relates to their ability to switch at high speed. The wide bandgap material allows the diode to switch faster than a silicon diode, which is important in applications where switching is required at high frequency. The fast switching brings lower figures for switching losses and better overall efficiency of the system. In power converters, inverters and motor drives, this fast switching means less energy is wasted in the transition from on to off and vice versa. Sdun-nanosecond switching speeds are achieved by SiC diodes in high frequency applications such as inverters driving renewable energy systems, and electric vehicle powertrains.
Reverse Recovery Time
This is one of the key parameters relating to the switching performance SiC diodes as well as other types of diodes. The reverse recovery time trr is the time required for the diode, after reversal of the polarity, to stop conducting. The shorter the time the better for use in powering a system as there is less energy lost during the switching. SiC diodes have much lower levels of trr than silicon diodes, because the charge carriers remain for less time as the SiC diode recovery characteristics are so much quicker. The shorter the time, the lower the switching losses in motors drives, inverters and dc/dc converters.These are associated with the forward voltage drop (Vf) of the diode. In high current applications, in general, SiC diodes present users with a forward voltage drop which is less than that typically offered by silicon at the moment and power loss through conduction is reduced.
There are compromises here in that often SiC diodes will show a higher Vf at low currents, but the benefit of lower losses at high current operation, where power systems spend their lives for the most part, greatly benefits the efficiency of such high-power systems, such as electric vehicle charging stations and ‘industrial’ power supplies.
Thermal Management. The technology of the SiC diode produces less heat, overall, than conventional silicon devices, but care still must be exercised in ensuring a level of thermal management through the use of conduction, and in some instancesReducing EMI is especially critical in applications such as telecommunications and industrial equipment such as solenoid valves, medical devices, and automotive systems. EMI protection is achieved by filtering and layout techniques adapted for SiC diode based circuits.
Advantages of the Diode in Power Electronics
The fast switching of the diodes provides the following key advantages for the power electronics: Efficiency Higher efficiency of the power system can be realized because of the diodes’ fast switching speed and lower conduction loss. Higher efficiency is of enormous advantage in applications as renewable energy generation where cost savings and reliability gain from lower loss in the power conversion system is obviously desirable. Smaller Size of the entire power system becomes possible as a result of the fast switching speed and extreme low switching loss of the diodes. The ability to run at higher temperatures obtain a further efficiency gain at the expense of less size brute force for cooling the system components. All these results to convincing advantages in terms of smaller power converters and inverters where size and weight of the components used are critical. Improved reliability of the power devices in the power system because of greater tolerance to extreme operating conditions such as high voltages, high temperatures and beyond. Applications SiC Diodes The applications of the SiC diodes are as follows: Electric Vehicles (EVs): In the automobile powertrain application, the role of diodes cannot be less important. In the IGBT topologies used in the inverter/motor drive circuits of electric or hybrid cars, address of the emitter low voltage drop Schottky barrier diodes become imperative. Power Inverter: We find SiC diodes used in solar inverters and wind turbine inverters as well to boost energy conversion efficiency while compacting system size. Industrial Equipment: We find diodes used in the motor drive of industrial machines and welding machinery, refrigeration application and any and other industrial power system which demand high reliability.
Renewables: Solar and wind application both enjoys the benefits of diodes which tolerate more high temperature and high voltage use than their silicon counterparts, in most applications. Conclusion These new SiC diodes will undoubtedly become a success, spreading to all sectors of power electronics. The fast switching speed and the low loss make it useful in the power electronics of all applications for reduced loss, and simpler, smaller designs and fast recovery. Overall, it is these superior features of the SiC units provide the reason for expecting general acceptance of manufacturers of inverters, converters and drives for electric vehicles, power inverters for renewable energy such as solar and wind farming utility, motor driving equipment in major applications.