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This article shows both theoretical and experimental analyses of a fully integrated CMOS active gate driver (AGD) developed to control the high dv/dt of GaN transistors for both 48 and 400 V applications. To mitigate negative effects in the high-frequency spectrum emission, an original technique is proposed to reduce the dv/dt with lower switching losses compared to classical solutions. The AGD technique is based on a subnanosecond delay feedback loop, which reduces the gate current only during the dv/dt sequence of the switching transients. Hence, the dv/dt and di/dt can be actively controlled separately, and the tradeoff between the dv/dt and EON switching energy is optimized. Since GaN transistors have typical voltage switching times on the order of a few nanoseconds, introducing a feedback loop from the high voltage drain to the gate terminal is quite challenging. In this article, we successfully demonstrate the active gate driving of GaN transistors for both 48 and 400 V applications, with initial open-loop voltage switching times of 3 ns, due to a full CMOS integration. Other methods for dv/dt active control are further discussed. The limits of these methods are explained based on both experimental and simulation results. The AGD showed a clear reduction in the peak dv/dt from –175 to –120 V/ns for the 400 V application. [ABSTRACT FROM AUTHOR]

Applications such as renewable energy generation, electric vehicles, and low-power UPS require single-phase ac/dc conversion. However, this conversion introduces a considerable amount of second-harmonic ripple on the dc link. If not filtered, this distortion hinders the converter's performance as well as the energy quality on both the ac and dc side. To mitigate this problem, a large electrolytic capacitor is usually the solution of choice, which mitigates the voltage ripple, but has drawbacks of its own, including the increased size and cost associated with the large capacitance and the limited lifespan of electrolytic capacitors. Alternative solutions to the problem include integration of an active filter circuit to the converter, which can utilize a storage element with the objective of mitigating power ripple. Such solutions have often been proposed alongside a control system, which is either highly complex or relies on open-loop feedforward techniques. This paper presents a control system, which adapts the single-input space vector concept for a single-phase application and leverages its simplicity and closed-loop architecture, allowing the controller to perform well in the presence of disturbances and parameter uncertainty. Experimental results are provided to elucidate the controller's performance on a single-phase grid-connected photovoltaic array application. [ABSTRACT FROM AUTHOR]

This paper proposes a new concept for attaining a defined switching behavior of insulated-gate bipolar transistors (IGBTs) at inductive load (hard) switching, which is a key prerequisite for optimizing the switching behavior in terms of switching losses and electromagnetic interference (EMI). First, state-of-the art gate driver concepts that enable a control of the IGBT's switching transients are reviewed. Thereafter, a highly dynamic closed loop IGBT gate driver using simple passive diC /dt and dvCE/dt feedbacks and employing a single analog PI-controller is proposed. Contrary to conventional passive gate drivers, this concept enables an individual control of the current and voltage slopes largely independent of the specific parameters or nonlinearities of the IGBT. Accordingly, a means for optimizing the tradeoff between switching losses, switching delay times, reverse recovery current of the freewheeling diode, turn-off over voltage, and EMI is gained. The operating principle of the new gate driver is described and based on derived control oriented models of the IGBT, a stability analysis of the closed-loop control is carried out for different IGBT modules. Finally, the proposed concept is experimentally verified for different IGBT modules and compared to a conventional resistive gate driver. [ABSTRACT FROM AUTHOR]

At a certain level of abstraction, power converters can be represented as linear circuits connected to diodes and controlled electronic switches. The evolutions of the electrical variables are determined by the state-dependent switchings, which complicate the mathematical modeling of controlled power converters. Differently from the complementarity models previously presented in the literature, the model proposed in this paper allows to represent as a linear complementarity system also closed-loop power converters, without requiring the a priori knowledge of the converter modes. A model construction procedure, not dependent on the specific converter topology, is presented. The discretization of the continuous-time model allows to formulate mixed linear complementarity problems for the computation of the control-to-output frequency response and the evolutions of both transient and steady-state currents and voltages. As illustrative examples, Z-source, boost, and buck dc-dc power converters under voltage-mode control and current-mode control operating both in continuous and discontinuous conduction modes are considered. [ABSTRACT FROM AUTHOR]