This paper presents a novel closed-loop active-gatecontrol (AGC) circuit for high-voltage SiC MOSFETs, used in the high-voltage, high-frequency and high-power-density applications. The proposed controller independently adjusts the switching di/dt and dv/dt by closed-loop control of the gate current and enables one to reach optimal performance in terms of loss, device stress, and EMI. The di/dt is adjusted to control the overvoltage stress and peak reverse recovery current while the dv/dt is adjusted to control the common mode (CM) noise and switching loss. The dv/dt is the primary source of the common mode noise in power electronics converters. Dynamic control of switching dv/dt has been somewhat overlooked in the state-of-the art works based on Si based power semiconductor devices (PSDs), and maximum achievable dv/dt is used to decrease the switching loss. However, the magnitude of generated dv/dt in the high-voltage SiC-based applications is appreciable because of the exceptionally higher switching speed of the SiC MOSFETs as compared to Si IGBTs. In contrast to other works, the proposed controller dynamically and independently controls the turn-off di/dt and dv/dt of a SiC MOSFET using closed-loop control of the gate current. Independent control of turn-off di/dt and dv/dt is achieved using a delay compensation circuit. This circuit compensates the total delay in the feedback loop and predicts the onset of transition between dv/dt and di/dt control regions. The proposed control circuit operation and advantages are presented and verified by experimental results.

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We have modelled the effect of 1 Me V electron irradiation on the performance degradation of a single junction AI,Gal_xAsIGaAs solar cell. The irradiation-induced defects result in energy states within the energy gap of the semiconductors. In this paper. we first model the effect of 1 MeV electron irradiation for the electron fluences from 1 x 10 14 to 1 xl0 16 elem2 using the'parameters of the irradiation-induced defects on the performance degradation of a solar cell. Then we present the results of a study for the effect of the layer thickness on the performance degradation of the solar cell. We will show that by choosing appropriate thickness for the layers, it is possible to considerably reduce the performance degradation of the solar cell.