The growth of fuzzy logic applications led to the need of finding efficient ways to implement them. The FPGAs (Field Programmable Gate Arrays) are reconfigurable logic devices that provide mainly practicality and portability, with low consumption of energy, high speedy of operation and large capacity of data storage. These characteristics, combined with the ability of synthesizing circuits, make FPGAs powerful tools for project development and prototyping of digital controllers. In this paper, the implementation of a Mamdani Fuzzy Inference System has been demonstrated using VHDL programming language. The accuracy of the model on FPGA was compared with simulation results obtained using MATLAB & Fuzzy Logic Tool Box.

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This paper presents an adapted carrierbased PWM modulation technique to be applied on both Neutral Point-Clamped (NPC) and Flying Capacitor (FC) structures of multilevel inverters. The proposed modulation leads to an improved performance on the output voltage THD. It also reduces the total loss dissipation across the semiconductors devices compared to other conventional carrier-based PWM modulation techniques, such as Phase-Shifted PWM (PSPWM) and Level-Shifted PWM (LSPWM). In order to demonstrate the effectiveness of the proposed technique, it was developed a three-phase, three-level, 6kW prototype for both NPC and FC topologies.

This paper presents the design, implementation and experimental results of a double conversion uninterrupted power supply (UPS), with integration of the rectifier and the inverter stages. The system is composed by a rectifier and an inverter, which employs a single-pole strategy for the switching modulation. The main system characteristics are: the control assembled with commercial integrated circuits, and the unified circuit of the rectifier and the inverter. Theoretical analysis, operation principle, and topology details are presented and validated through experimental results.

A three-phase soft-switched DC-DC resonant converter with variable frequency to perform the output voltage control is proposed. The open delta-wye connection provides a double output voltage reducing the primary current stress, turns ratio, weight and volume of high-frequency transformer. To achieve high efficiency, an LLC resonant tank is designed so that all switches can perform zero-voltage switching for the entire power range. In order to verify the operating principle of the converter, a design example is described, with the following converter specifications: input voltage 96 V, output voltage 380 V and a switching frequency up to 120 kHz. The feasibility and practicality of the proposed converter are confirmed by experimental results with a 1.5 kW prototype.

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SummaryDC microgrids rely strongly on bidirectional dc‐dc converters responsible for managing the power flow among distinct loads and renewable energy sources like fuel cells and batteries. In this context, this work presents a three‐phase inductor‐inductor‐capacitor (LLC) resonant dc‐dc converter with high‐frequency isolation and bidirectional power flow capability, employing phase‐shift control and frequency modulation. The resonant tank takes advantage of using the leakage inductance and the magnetizing inductance of the high‐frequency transformer (HFT), which allows for improving power density. The active switches operate with a fixed duty ratio of 50% so that the converter can always achieve zero‐voltage switching (ZVS). The mathematical analysis is carried out based on a single‐phase representation of the converter, which considers only the fundamental components. A dynamic model is derived using the gyrator theory, which allows representing the converter as a frequency‐controlled current source to regulate the output voltage. In addition, the power flow direction is determined from the estimation of an ideal phase‐shift angle for each frequency aiming to control the output power. An experimental prototype is implemented and thoroughly assessed to demonstrate that the introduced topology is feasible for dc microgrids and other applications that require bidirectional power flow.