Electrothermal modeling and characterization of SiC Schottky and silicon PiN diodes switching transients

Schottky diodes are known to have lower conduction and switching losses compared to PiN diodes, however, are prone to ringing in the output characteristics. In this paper, analytical models have been developed to calculate the turn-off switching energy of SiC Schottky and silicon PiN diodes. The models account for the reverse recovery current and diode voltage overshoot in the case of the PiN diode as well as the output oscillations for the Schottky diodes. PiN diodes during turn-off exhibit significant reverse current which increases with the switching rate and temperature whereas Schottky diodes exhibit output oscillations due to RLC resonance in the circuit. By combining these models with thermal networks derived from transient thermal impedance curves of the diodes, a fast and accurate method of predicting the temperature transient for different switching frequencies and electrical time constants has been developed. These models can be used by application engineers to predict the energy dissipation when designing converters and can take account of temperature and switching rate dependencies of the diodes.