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Many efforts have been devoted to describe the multi-timescale thermal dynamics of power modules and frequency-domain modeling is a relatively new approach. Unfortunately, only the frequency-domain response of thermal impedance has been studied in recent works, so the existing models can only describe the temperature behaviors of semiconductors. In the reality, it is not only the temperature of semiconductors which is important but also of other parts of the package. In this article, a novel perspective to study the thermal dynamics by analyzing heat flow behaviors is proposed. Frequency spectrum analysis in finite-element method simulation has been first used in this article, and it reveals that heat flow of the power semiconductor device behaves as a multi-layer low-pass filter (LPF). As a result, a novel modelling method of heat flow with a 7order-3frequencies LPF has been developed in this article and it can provide a comprehensive description of heat flow behaviors for power modules at full bandwidth. Meanwhile, the effects on heat flow behaviors brought by boundary conditions are also considered to ensure that the proposed model can be easily adapted to different boundary conditions. The effectiveness and accuracy of the proposed model has been verified by both simulations and experiments. [ABSTRACT FROM AUTHOR]

AC-DC conversion is required in many applications, and in some of them isolation is strictly required, certainly while maintaining characteristics such as a high power factor and low input current THD. In this paper, an AC-DC converter, comprising a full-bridge diode rectifier and a dual-active-bridge (DAB) converter, is utilized to fulfill these characteristics. The used modulation makes the converter behave as a resistive load, maintaining the output voltage constant while achieving a high power factor and low input current THD. The operation of the converter is simple, as only two voltage sensors are required, and no inner current loop is utilized. A low-power prototype was experimentally tested to corroborate the proposal. [ABSTRACT FROM AUTHOR]

This letter aims to present a generalized vector-based formulation for calculating the grid-side current reference to control reactive power delivered to the grid. Strategies for current reference generation were implemented on the abc stationary reference frame, and their effectiveness was demonstrated experimentally, perhaps validating the theoretical analysis even under grid fault conditions. Index Terms--Power distribution faults, pulsewidth modulated inverters, reactive power, wind power generation.

This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional-integral, proportional--resonant, and deadbeat (DB) controllers. Additionally, an improved DB controller robust against grid impedance variation is also presented. Since the paper discusses the implementation of these controllers for grid-connected applications, their evaluation is made in three operating conditions. First, in steady-state conditions, the contribution of controllers to the total harmonic distortion of the grid current is pursued. Further on, the behavior of controllers in the case of transient conditions like input power variations and grid voltage faults is also examined. Experimental results in each case are presented in order to evaluate the performance of the controllers. Index Terms--Current controllers, current harmonic distortion, distributed power generation systems (DPGSs), grid faults, input power variations.