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© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper presents a control scheme that simultaneously solves the problems of negative-sequence voltage compensation and negative-sequence current sharing in grid-connected microgrids using grid-feeding inverters. State-of-the-art schemes have previously solved these problems with low-performance control solutions or, alternatively, with high-performance solutions but paying the cost of high control-data traffic in the communication network. The proposed control scheme improves the performance of previous schemes for grid-feeding inverters with the following characteristics: 1) negative-sequence voltage compensation at any point of the microgrid, 2) accurate negativesequence current sharing, and 3) low control-data traffic. In terms of implementation, two key points of the proposed control scheme are: the voltage compensation is based on a band-pass filter with complex coefficients and the current sharing is reached only with local current measurements. In the theoretical analysis, the system model is based on transfer functions with complex coefficients. This fact facilitates the control design due to 1) the system model is linear in this complex domain and 2) the multiple-input singleoutput model can be represented as a single-input single-output model for voltage compensation. The characteristics of the proposed control are validated by means of experimental results measured in a laboratory microgrid. This work is part of the project I+D+I RTI2018-1000732-B-C22, funded by MCIN/AEI/10.13039/501000011033 and FEDER “A way to make Europe”.

The enhanced phase-locked loop (EPLL) is one of the most famous PLLs in single-phase applications and a versatile tool for different signal processing applications, especially for the grid synchronization of power converters. Recently, it has been proved that the EPLL has a quite narrow stable zone (compared to its unstable zone) in the positive parameter space from a small-signal point of view. This zone will be even more narrow if maintaining a minimum stability margin is required. This article aims to modify the EPLL structure to improve its stability margin, and at the same time, make it unconditionally stable in the positive parameter space from a small-signal point of view.

This article presents an agile supply modulator with optimal transient performance that includes improvement in rise time, overshoot and settling time for the envelope tracking supply in linear power amplifiers. For this purpose, we propose an on-demand current source module: the bang-bang transient performance enhancer (BBTPE). Its objective is to follow fast variations in input signals with reduced overshoot and settling time without deteriorating the steady-state performance of the buck regulator. The proposed approach enables fast system response through the BBTPE and an accurate steady-state output response through a low switching ripple and power efficient dynamic buck regulator. Fast output response with the help of the added module induces a slower rise of inductor current in the buck converter that further helps the proposed system to reduce both overshoot and settling time. This article also introduces an efficient selective tracking of envelope signal for linear PAs. To demonstrate the feasibility of the proposed solution, extensive simulations and experimental results from a discrete system are reported. The proposed supply modulator shows 80% improvement in rise time along with 60% reduction in both overshoot and settling time compared to the conventional dynamic buck regulator-based solution. Experimental results using the LTE 16-QAM 5 MHz standard shows improvement of 7.68 dB and 65.1% in adjacent channel power ratio (ACPR) and error vector magnitude (EVM), respectively.

DOI: 10.1109/TPEL.2016.2613888 URL: http://ieeexplore.ieee.org/document/7577863/ Filiació URV: SI Info. add.: Article number 7577863 This part of the paper illustrates the use of the expression derived in Part I for predicting subharmonic oscillation in switching regulators. Six case studies with different control schemes from the recent literature are used to validate the novel approach and the new derived expression, which is benchmarked for these case studies against results obtained using the discretetime modeling approach or Floquet theory combined with Filippovmethod. Numerical simulations from the circuit-level switched models, implemented in PSIM software, are used to demonstrate the correctness of the derived closed-form condition. A procedure is presented to apply the approach of the paper to power converters with nonlinear sources, such as photovoltaic (PV) arrays or fuel cells. Experimental measurements from a boost converter prototype for PV applications are also provided to validate the theoretical predictions and the numerical simulations showing a remarkable agreement.