Circuit-level analytical models for hard-switching, soft-switching, and $dv/ dt$ -induced false turn on of SiC MOSFETs and their experimental validation are described. The models include the high-frequency parasitic components in the circuit and enable fast, accurate simulation of the switching behavior using only datasheet parameters. To increase the accuracy of models, nonlinearities in the junction capacitances of the devices are incorporated by fitting their nonlinear curves to a simple equation. The numerical solutions of the analytical models provide more accurate prediction than an LTspice simulation with a threefold reduction in the simulation time. The analytical models are evaluated at 25 °C and 125 °C. The effect of snubber capacitors on the soft-switching waveforms is explained analytically and validated experimentally, which enables the techniques to be used to evaluate future soft-switching solutions. Finally, the $dv/ dt$ -induced false turn-on conditions are predicted analytically and validated experimentally. It was observed that consideration of nonlinearities in the junction capacitances ensures accurate prediction of false turn on, and that the small shoot-through current due to false turn on can increase the switching loss by 8% for an off-state gate bias of −2 V.

A system-level modeling technique for a switched reluctance generator (SRG) is described for aerospace applications. Unlike existing techniques, this model is very simple and only reproduces the average behavior of the input-output variables that are required for system-level analysis of the aircraft power distribution system. The model is parameterized from the measured generator response, avoiding the need for a detailed knowledge of the equipment structure, which may be unavailable. The modeling procedure is described in detail and validated by measurements on an SRG within an aircraft test facility.

A single-shot switching test circuit and a continuously operating converter are used to investigate dynamic on-state resistance in three 600 V GaN devices under representative converter operating conditions. The increase in dynamic on-state resistance following an off-state stress of a few micro-seconds was measured and demonstrated to be in the range of 6%-35% depending on the individual device. The dynamic on-state resistance effect is seen to be insensitive to temperature over the range 25-125T. A more severe increase in dynamic on-state resistance is observed when the device is exposed to a stress voltage for an extended stress time, in particular the e-mode devices exhibited two to three times the DC resistance. The dynamic on-state resistance has a more pronounced effect in continuously operating converters at higher switching frequencies; an increased on-state loss of 35.9% compared with the DC value is estimated for a converter operating at 300 V, 10 A, 400 kHz and 0.5 duty ratio.

There is currently significant interest in offshore wind turbines up to 5 MW. One of the preferred options is doubly fed slip-ring generators. Turbine manufacturers have proposed an operating scheme for low speeds that is claimed to improve the overall energy extraction from the wind. This paper aims to examine the performance benefits for this new operational mode on a small experimental rig, confirmed by simulation, and to provide a fundamental understanding of the differences in the generator operation in both modes. This paper develops analytical steady-state models to provide this insight and correlates the operating performance with a dynamic real-time generator control scheme and experimental results obtained from a laboratory test machine. A theoretical study on a 2-MW commercial turbine is also undertaken

Analytical models for hard-switching and soft-switching SiC MOSFETs and their experimental validation are described in this paper. The models include the high frequency parasitic components in the circuit and enable very fast, accurate simulation of the switching behaviour of SiC MOSFET using only datasheet parameters. The much higher switching speed of SiC devices over Si counterparts necessitates a clear detailed analysis. Each switching transient was divided into four distinct sub-periods and their respective equivalent circuits were solved to approximate the circuit state variables. Nonlinearities in the junction capacitances of SiC devices were considered in the model. Analytical modelling results were close to the LTspice simulation results with a threefold reduction in the simulation time. The effect of snubber capacitors on the soft-switching waveforms is also explained analytically and validated experimentally, which enables the analytical model to be used to evaluate future soft-switching solutions. It was found that the snubber branch can significantly reduce the turn off ringing of the SiC MOSFET in addition to the reduction of switching losses.