Proportional–Resonant Controller Structure with Finite Gain for Three-Phase Grid-Tied Converters

The paper presents the study of a three-phase system coupling a DC power source to a power grid. This study, based on an FPGA, implements a real-time control system and digital models of the power circuit. The proposed proportional–resonant (P+R) controller with a modified structure was part of the system, which can be used as an alternative controller to traditional ones, e.g., in photovoltaic systems. Due to difficulties in implementing resonant controllers, a P+R with a new structure using a PI controller was elaborated. With an appropriate approach to the generation of phase current patterns, it is possible to set the reactive current and, thus, compensate for the reactive power. The operation of the system for typical operating conditions (e.g., system startup, change in preset load) was characterized and compared with a classical solution using a PI controller.

Impact on Gain and Noise : ECG Amplifier & Comb Filter Design using OTA

The research paper ventures a novel modelling strategy of finite gain and noise of an electrocardiogram (ECG) amplifier at 0.18, 0.5 and 0.9 micron standard CMOS technologies respectively. An active comb filter is used to design the amplifier for removing the selected frequencies of numerous signals. The presented filter is configured with only Operational Transconductance Amplifiers (OTAs) and capacitors that makes it apt for implementation of monolithic integrated circuits (ICs). The relevance of this analog circuit is verified for a suitable test signal of 60 Hz as in the ECG signal. Using Cadence Virtuoso analog design environment, the effect of transistor channel length and width is examined for analysis of noise and bandwidth. It is observed that the performance in terms of noise and gain considerably increases for advanced technology node. However, for a suitable supply of bias current, a portable ECG system can also provide an improved bandwidth performance of advanced CMOS technology

A Novel Offset and Finite-Gain Compensated Switched-Capacitor Amplifier with Input Correlated Level Shifting

A novel offset and finite-gain compensated differential switched-capacitor(SC) amplifier is presented. Incorporating the correlated double sampling (CDS) technique and input correlated level shifting (CLS) technique together, the DC offset and DC gain error of SC amplifier are further reduced by a factor of op-amp DC gain compared with the conventional offset and finite-gain compensated SC amplifier. The effectiveness of the new scheme has been analyzed and verified by extensive simulations. An SC amplifier with the proposed scheme is designed in 130 nm CMOS technology. Simulated results show that with an op-amp having a low DC gain of 30 dB and an input offset of 10 mV, the proposed SC amplifier achieves an output offset and DC-gain error of 154 µV and 0.05%, respectively, which are significantly improved compared with 1.155 mV and 0.42% achieved in the conventional SC amplifier.

Structural Improvements in Consensus-Based Cooperative Control of DC Microgrids

This study is dedicated to establishing a comparative analysis of the performance ofdifferent local controllers on the cooperative control of DC microgrids. One of the elementary andchallenging issues in DC microgrids is the assurance of fairness in proportional current sharingwhile accomplishing voltage regulation in parallelly connected distributed energy sources. In thiswork, structural improvements are proposed to enhance the system stability and controlperformance. A finite-gain controller was employed in the outer voltage control loop with a simpleproportional (P) controller in the inner current control loop of a converter. Due to the finite-gaincontroller, droop-like power sharing was achieved without droop coefficient. In order to furtherenhance the power-sharing accuracy and DC voltage regulation, a different method was adopted inconsensus-based cooperative control to estimate the average current and average voltage difference.Moreover, small signal analysis was used to scrutinize the stability and control performance of thelocal controller, while different communication delays and current disturbances were applied toexamine the performance of the controller. Finally, a four-node-based DC microgrid setup wasdeveloped in MATLAB/Simulink environment, and simulation results of the proposed and existingtechniques were scrutinized. The simulations results demonstrated the effectiveness of the proposedcontroller.