Maxim Vorobyov

Optimizing of sampling in a low-cost single-phase instantaneous AC-grid synchronization unit with discrete calculation of derivative function

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 are calculated with highest accuracy. It is shown that the implementation of approximate derivative function can reduce start-up time of the synchronization unit. The method is implemented in a low-cost microcontroller and successfully experimentally verified with a physical model of the grid, as well as with a real voltage sensor.

Low-Cost Voltage Zero-Crossing Detector for AC-Grid Applications

Abstract Renewable energy sources and energy storage devices are becoming more popular. Some of them like small hydropower turbines, wind turbines and diesel generators produce AC voltage with different frequency and voltage than the main grid. For them power electronics converters are necessary. Power electronics converters presented in industry use two or three level energy conversion, although direct AC to AC converters exist, but one of the main problems is the switch commutation when current or voltage is crossing the zero point. Zero crossing sensors are used to solve this problem. They consist of current or voltage measurement unit and zero crossing detector. Different approaches are used for zero crossing: hardware or software. Hardware approach is simple but it has low precision. Software approach has high precision but it is complicated and expensive. In this paper a simple low cost high precision approach is presented. It takes all advantages from both approaches. While tested with two types of microcontrollers the precision of experimental measurement is 25 μs - 40 μs.

Battery monitoring using high frequency impedance modulation through series power line

The paper deals with a power line interface suitable for implementation in systems composed of series connected energy storage or generation cells, for example, battery cells supercapacitors etc. The interface, which does not use any additional wiring, utilizes amplitude modulation to transmit data in one direction and impedance modulation - to transmit in the opposite. In the paper the features of the proposed interface are described and analyzed. Then a practical example of the proposed interface is given. Possible implementation of the interface for battery monitoring needs is also discussed.

Development of power driver for vibration generator of bionic-like feedback for smart prosthesis

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 of 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 which loads user vision. To solve these two problems it was decided to develop prosthetic devices with other kind of feedback systems: thermal, electrical, pressure, vibration…etc. A vibro-tactile test bench was developed to evaluate vibration feedback systems. Vibro-tactile test bench works in wide range of frequencies and magnitudes. The main goal of the presented paper is to define the most optimal power driver. As main parameter is chosen acceleration magnitude dependence on frequency and input signal magnitude. Three possible solutions were tested: direct connection to analog discovery kit, connection trough A - type audio amplifier and connection trough B - type audio amplifier. As result the most optimal solution was A - type amplifier. It has unipolar supply, and output signal value is the same as for B - type amplifier‥

Implementation of single-phase grid synchronization module with low-end microcontrollers

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 module based on an MSP430 microcontroller. This example follows from a complete PLL system, finally giving simplified, operating system. The obtained preliminary results confirm the operation of the propose synchronizer, but show the necessity of its further improvement.

Considerations regarding the concept of cost-effective power-assist wheelchair subsystems

Abstract The present paper deals with the concept of a cost-effective power-assistant wheelchair. An analysis of the market situation and recent technical achievements is done at the beginning. On its basis, a set of solutions suitable for the development of such wheelchairs has been composed. It is shown that the key features of the considered concept are: segmented electrical motor and drive, sectioned battery pack, modular charger and an ANN matrix that provides easy and intuitive interfacing of sensor networks, pseudo-bionic feedbacks and the decision-making unit. Within the scope of the paper, a 3D model has been developed and 3D modelling has been conducted. As a result, certain drawbacks in the design and placement of elements have been found and a modification of the concept has been proposed

Comparison of 3D printed vibro-tactile actuator with permanent magnet only and standard vibro-actuator for prosthetic feedback devices

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 to the user. To reduce the load on the users vision, it was decided to create a system with a tactile vibration feedback. To test such a system, a test bench with vibration actuators was created. The main condition for the work of the vibration actuator is the possibility of adjusting the frequency and intensity of vibration in a wide range. The work described in this paper is a comparison between the vibration actuators: made at the factory and printed on a 3d printer. Vibration actuators were compared according to static and dynamic parameters. Static parameters: ratio of current and force, ratio of power consumption and power. Dynamic parameters: amplitude-frequency characteristic of acceleration. As a result, a vibro-actuator printed on a 3d printer has lower static parameters than the one factory produced, but works on a wider frequency range. As a result, the actuator printed on the 3d printer is a more acceptable solution for prosthetic bench application.

Development and optimization of adjustable vibration source for investigation of prosthesis-to-human feedback of intellectual artificial limb

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 which loads user vision. To solve these two problems decided develop prosthetic devices with other kind of feedback systems: thermal, electrical, pressure, vibration...etc. For using vibration feedback system vibration motors must work in wide range of frequency spectrum and produce controlled intensity in every frequency point. Unfortunately nowadays produced vibration motors cannot satisfy these requirements. In this paper represented three possible solutions of vibration devices for prosthetic feedback systems. Loudspeaker motor based system, linear motor based system and combined system. All three systems are modelled in comsoll metaphysics environment. Modelled parameters are flux density and force-frequency dependencies. As result the best candidate for vibration system is simple voice coil motor. It has linear force-frequency spectrum in wide range. Linear motor most have complex control system and have the same results as combined motor.