Volume 1 (2012): Issue 1 (December 2012)

The paper considers the possibility of steam production and supply process improvement by perfection of the steam boiler control system, applying invariance principle that makes possible preemptive compensation of the influence of steam expenditure as a disturbance on the control process quality and efficiency. For the development of invariant control system, the mathematical modeling and simulation in MATLAB - SIMULINK environment is made. The control unit is low pressure steam boiler with one input impact to control - the heat flow of burning gas mixture fuel, one measured output parameter of the process - the steam pressure, and the main disturbance as a load impact - the steam expenditure. The mathematical and virtual models and block-diagrams for transient process simulation is compiled, allowing to start practical design and investigation of steam boiler invariant control system with high operation stability under essentially fluctuating load. The simulation results prove that the optimal solution for the transient process improvement in steam boiler, taking in account fluctuating load, is invariant PID-DPC two loop control system with disturbance impact on steam pressure preemptive compensation. Under invariant control the steam pressure overshoots decreases substantially in comparison with the traditional PID-feedback control method.

In this paper several modulation techniques for a three-level neutral-point-clamped quasi impedance source inverter are proposed and discussed. Mathematical descriptions with simulation results are presented for each modulation technique. Their advantages and disadvantages are shown and guidelines for further improvement are provided.

Focus is on implementation possibilities of surfacemount device (SMD) to be used in high power applications. SMD capacitors reduce the size and dimensions of a power circuit and increase the flexibility of placement of other components. Ceramic and electrolytic capacitors are compared by means of voltage ripple, volume, labour-intensity and impedance. A 1 kW experimental setup of a quasi-Z-Source inverter (qZSI) based converter was built to compare SMD capacitor performance in the quasi-Z-source (qZS) network.

This paper presents findings of a R&D project targeted to the development of a galvanically isolated step-down DC/DC converter for electrolyzer integration with renewable energy systems. The presented converter with an improved control algorithm for the full-bridge active rectifier features reduced energy circulation and switching losses. The performance can be improved under wide input voltage and load variations. The advantages of the converter were verified with a 1 kW converter prototype and the test results were in full agreement with the expected waveforms. The presented steadystate operation principle and mathematical analysis of the converter based on the simulation and experimental results can be used as design guidelines for component and parameter estimation in practical applications.

Usually wireless devices require autonomous power supply. They are equipped with radio frequency transceiver modules with relatively high energy consumption especially in data transmission mode. This also means that autonomous power supply of wireless device requires relatively large energy storage. Rechargeable battery in this case is a good solution, but the charging process of a battery takes a long time. In this paper the use of supercapacitor as energy storage for autonomous power supply of wireless node is further elaborated on the example of light sensor for illumination measurement test bench.

Features of combined mechatronic systems creation with a rigid mechanics are observed in details. The usage of astatic regulators for the basic positioning loop is offered. Efficiency of regulators and observers adjustment on Bessel polynomial is shown for mechatronic positioning systems. Outcomes of synthesis of the load observer taking into account the drive dynamics and different forms of load in the system are resulted.

The paper presents configuration of the traction drive test bench with energy storage system, calculation of the scale factors, estimation of the energy storage system size and Matlab simulation results of the bench operation in a braking mode at different levels of the supercapacitor initial voltage.