Liviu Dinca

Study of fuzzy logic controller for ZCS Boost converter

In this paper a study of the fuzzy logic controller for ZCS Boost converter is presented. The fuzzy logic controller provides an adaptive control for better system performance and it is used for controlling the non-linear processes. FLC is designed to regulate the output voltage of the converter. The converter is modeled and analyzed using Matlab/Simulink software and it was designed in an closed-loop configuration. Simulations have shown its accuracy and they confirm the validity of technique used.

Experimental tests regarding the functionality of a DC to DC Boost Converter

This article presents experimental tests made on a DC to DC Boost Converter of 24 V-48 V. The boost converter was first realized on a laboratory version, regarding its utility as a voltage source for the E.I.A (Equipments and Installations for Aviation) laboratory of the University of Craiova, and also to be used in teaching activities and for research. During tests it was point out the performances obtained, but also the inconvenient and the limitations of the purposed scheme. The improvements of this schema will be presented in a future study.

Numerical modeling of a Dc to Dc boost converter

This paper presents a simulation model for a DC to DC boost converter. The simulation model was accomplished in MULTISIM 12 and represents in fact the electronic scheme which was manufactured experimentally in the Avionics Laboratory of our faculty. The converter amplifies the 24 VDC input to 48 VDC output, with a maximum power of 500 W. This converter can be used in the aero-spatial domain, on satellites, especially. In these cases it is integrated in energetic systems by the side of fuel cells, hydrogen and oxygen regeneration systems or photovoltaic cells. The command is a classic PWM with a switching frequency of 5 kHz and a linear variable voltage generator using also the 555 circuit. This paper is in fact a more detailed study using numerical simulations of this type of converters presented in [8]. Some improvements of the electronic scheme were achieved and the input and output voltages were modified in order to adapt to the avionics standards. From the numerical simulations one obtained the converters behavior under different loads - 15 Ω and 35 Ω. The results are realistic and consistent with reality.

Optimization of a dc to dc boost converter using interleaved command technique

In this paper is optimized by numerical simulations a dc to dc boost converter with two parallel stages using the interleaved command technique. A comparative study between three converter topologies - one stage, two parallel stages and two interleaved stages is presented. First, the interleaved command converter is modeled in MULTISIM and is tested under many output loads. For comparison, simulations with constant and controlled duty cycle of the PWM are performed. The main characteristics of the three topologies are discussed: input current, input current ripple, output voltage ripple, and the MOSFET peak current.

A prototype for airflow speed control in a subsonic wind tunnel

The article presents the framework of an update program for the wind tunnel from the University of Craiova, Romania. The program consists of many stages: system prototyping with LabVIEW control, control algorithm implementation with a microcontroller, high-power rectifier development, and all system testing. In this article, a first prototype for the d.c. motor control system was detailed, which mainly consists of a three-phase rectifier and a PI control algorithm implemented in LabVIEW. The control loop is closed, using a rotation motor speed transducer. The motor speed, current waveform through the motor, and the voltages from each phase are acquired using a NI-USB 6251 data acquisition card. The command voltage for the three-phase rectifier is also obtained from one of the data acquisition card analog output. The power source used in this prototype was a three-phase rotating converter. The electronic scheme of the rectifier was designed using Multisim.

Fuzzy energy management for hybrid fuel cell/battery systems for more electric aircraft

In this paper is presented the simulation and analysis of a Fuzzy Energy Management for Hybrid Fuel cell/Battery Systems used for More Electric Aircraft. The fuel cell hybrid system contains of fuel cell, lithium-ion batteries along with associated dc to dc boost converters. In this configuration the battery has a dc to dc converter, because it is an active in the system. The energy management scheme includes the rule based fuzzy logic strategy. This scheme has a faster response to load change and is more robust to measurement imprecisions. Simulation will be provided using Matlab/Simulink based models. Simulation results are given to show the overall system performance.In this paper is presented the simulation and analysis of a Fuzzy Energy Management for Hybrid Fuel cell/Battery Systems used for More Electric Aircraft. The fuel cell hybrid system contains of fuel cell, lithium-ion batteries along with associated dc to dc boost converters. In this configuration the battery has a dc to dc converter, because it is an active in the system. The energy management scheme includes the rule based fuzzy logic strategy. This scheme has a faster response to load change and is more robust to measurement imprecisions. Simulation will be provided using Matlab/Simulink based models. Simulation results are given to show the overall system performance.

Comparative analysis of a dc to dc boost converter with constant and variable duty cycle

In order to use dc to dc boost converter in combination with a fuel cell, for modern aircraft APU, it is important that the input current ripples to be very small. This paper presents a comparative analysis of a dc to dc boost converter with variable duty cycle and one with constant duty cycle. The Dc to dc boost converter proposed was modeled in Multisim, with a PID controller. After numerical simulations it was found that input current ripples have a maximum output current of approximately 20A. The variation is more flat when operating with constant duty cycle. The use of this controller that changes the duty cycle also leads to a greater variation of ripples in relation with the output current. Thus, to make a comparison with theoretical results, which were achieved in the bibliography, numerical simulations were made with the PWM pulse at a constant value, with 50% duty cycle. Based on simulation results there were plotted the boost converter output characteristics for the two cases. Graphs were performed in Matlab. Besides these output characteristics, there were also plotted the output and input current variation, the current through the transistor, the ripples for the output voltage and for the input current in relation with the output current.

Multisim implementation and analysis of a DC to DC boost converter with two parallel stages

In this paper is presented the implementation in MULTISIM and numerical simulation analysis of a DC to DC boost converter with two parallel stages. For the boost converter with two stages in parallel implemented in this paper input voltage is 24 VDC and output voltage 48 VDC at a maximum power of 1.7 kW. The switching frequency was set about 10 kHz. The implementation scheme in Multisim has two stages of identical power, which are connected in parallel. The boost converter with two stages in parallel has been tested under various loads, for a variable duty cycle and for constant duty cycle. Based on numerical simulations there were drawn the characteristics for a boost converter with two stages in parallel. It was noted that the behavior of two stages in parallel boost converter is similar to the single stage mentioning that the second one has an extended domain for the output currents.

Mathematical model and numerical simulations for mechanic-hydraulic flow controller

The paper presents a model for a flow controller used in hydraulic power systems. The functioning principle of this flow controller is a combination between a two ways flow controller and a three ways flow controller, widely known in literature. One mathematical model is obtained and numerical simulations are performed in order to put in evidence the qualities of this mechanic-hydraulic scheme.

Simulation and analysis of a fuel cell/battery hybrid power supply for More-Electric Aircraft

Aircraft electrical power systems have had to make serious progress in recent years because aircraft depend more and more on electricity. The More-Electric Aircraft (MEA) concept highlights utilizing electrical systems to replace more conventional aircraft power transfer systems and to accommodate newly-introduced electrical load. There is a trend in the aircraft industry to replace hydraulic and pneumatic systems with electrical systems, thereby realizing more comfort and monitoring features and increasing the overall energy efficiency. This paper presents the simulation and analysis of a fuel cell/battery hybrid power supply. The simulated system contains a fuel cell/battery hybrid power supply with a single DC to DC buck converter. In this configuration, the battery does not have a DC to DC converter, as it is passive in the system. The simulation makes use of Matlab/Simulink-based models. The simulation results are given to show the overall system performance.