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In the world is about one billion of disabled people. About one third of these people are people with mobility or movements impairments. For most part of people, high precision prosthetic devices with neural control and feedback are very expensive. Almost all average price prosthetic devices have visual feedback system, which loads user vision. To solve these two problems decided develop prosthetic...
According to WHO, around a billion people with disabilities live in the world. About one third of these people are people with mobility or movements impairments. For most of these people, high-precision hand prostheses such as bebeonics or touchebonus are very expensive. Prosthetics controlled from the nervous system directly exist only as prototypes. All of the above devices provide only visual feedback...
During recent years Riga Technical University continuously modifies its teaching processes to comply with the Bologna process. Previous study plan and course's content of Riga Technical University did not always provide good interaction between courses and successful synergy of student skills, obtained from different practical and laboratory works. This paper shows how recent scientific achievements...
The paper presents a technique of parameter stabilization of a wireless, resonance based energy transfer system for maximizing its power. The technique combines tuning of resonant frequency by means of variable capacitance and adjustment of magnetic coupling to maximize power. The paper presents experimental test results on a laboratory prototype of the system.
Reliable and precise grid synchronization unit is an essential part of the control system of grid inverters and rectifiers. Typically, such synchronization units are based on three-phase Phase-Locked Loop (PLL), which can be easy implemented in high-end microcontrollers and programmable logic devices (PLDs), and which is more suitable in higher power systems. Obviously, such approach is not applicable...
Accurate grid synchronization unit is essential for reliable operation of grid converters. Single-phase unit may utilize measured function and its digital derivative as the base for PLL. This paper compares some solutions of accuracy problems typical for such derivative approach: oversampling of measurements, interleaved calculation of derivative and averaged evaluation pulse signals. The proposed...
This paper deals with single-phase grid synchronization unit suitable for integration in interface converters of distributed renewable energy sources. A well known problem of the second orthogonal component for Park transformation of a phase-locked loop is successfully solved with a help of the approximate derivative function for the first time. Optimal sampling times for finding this derivative function...
Today SiC Schottky diodes are becoming less expensive and more affordable in the market of electronic components. However, the price is still higher in comparison with common fast and ultrafast diodes with the same current and voltage rating. The main aim of this research is to find are the SiC diodes more advantageous in non-isolated converters for LED applications. From the one side SiC diodes have...
According to World Health Organization data about one billion of people worldwide are disabled people. About one third of these people are people with mobility or movements impairments. First problem is that for that kind people high precision prosthetic devices with neural control and feedback are very expensive. Second problem almost all average price prosthetic devices have visual feedback system...
The operation stability and robustness are usually the main criteria for the practically implemented systems. This is especially critical in LED lighting applications, where voltage regulators are used to control current of nonlinear LED load. Also the parameters of the load significantly changes with the temperature change and bin change even for the same brand LEDs. The control system of LED driver...
A simple yet suitable energy meter has been developed and described to estimate the performance of a previously designed electric kart lithium ion battery pack cell balancing module. A brief introduction regarding the battery pack and battery management system with passive dissipative resistor balancing construction under investigation is given. Both hardware and software design of the energy measurement...
Global energy market reveal the necessity of the use of renewable energy sources which requires an interface converter if their energy has to be passed into the grid. The operation of the interface converters depends on the operation of their synchronisation unit. Low power sources need simpler and cheaper control systems. This paper shows an example of simple implementation of the grid synchronization...
The conventional approach in modern LED drivers is the usage of voltage regulators with rapid current feedback (current limit). Previously, the authors hypothesized that the current regulators can provide some advantages compared to the voltage regulators in LED lighting applications. Previous studies were related with theoretical basis and experimental verification of this hypothesis. This paper...
The high power LED driver based on non-inverting buck-boost converter is considered in this paper. The special regulation approach of this converter is described in order to simplify the control strategy. Thus, the implementation of this control strategy in microcontroller based closed loop regulation system allows to increase number of regulation steps (to achieve higher resolution) and to utilize...
Amplitude mode LEDs light regulation is most functional when LEDs are supplied from current fed buck drivers, which practical implementation is conjunction of non-inverting buck-boost circuit, extra coil and specific control methods. This report experimentally evaluates the efficiency of driver's versions making focus on their losses and possible electric power savings.
One of major problems related with PV-applications is common mode currents. The issue can be solved in two ways: galvanic decoupling of AC-grid and chopping the common mode currents by additional actively controlled circuitry. Flyback converter is good solution for MPPT tracking for PV-modules up to 100–150 W with galvanic decoupling. The problem of designing of this type of converter is that most...
The growing energy demand all over the world and the approaching deficit of traditional energy resources makes the development of renewable energy sources including wind energy necessary. A significant part of any wind turbine is the grid interface converter, operation of which depends a lot on the control system. Although this consideration is valid for all wind turbines, it is especially important...
The given paper deals with equipment for smart lighting systems. A hypothesis, that current fed dimmable electrical ballasts with amplitude modulation of light could improve the controllability of such systems, is brought forward. Since there are very few natural current sources it is proposed to use a combination of a voltage source, switch mode voltage-to-current converter and current regulator...
Maximal energy harvesting of photovoltaic panels is possible only if the load of photovoltaic cell is consuming current that corresponds to the maximal power point for condition combination on a certain moment. Correct and detailed mathematical modeling of photovoltaic panels is able to help to develop control techniques for maximum power point tracking converters. In order to overcome the disadvantages...
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