Marcin Baszynski

Results of Investigation of Multicell Converters With Balancing Circuit—Part II

This paper presents the results of an investigation of the multilevel multicell converters with a passive RLC balancing circuit applied for the maintenance of the voltage sharing on the capacitive sources of the converters. The topologies of DC/DC, AC/AC, DC/AC, and AC/DC multicell converters were analyzed. For the purpose of multilevel modulation, a multicell converter employs several capacitors that are connected to every cell-the flying capacitors, charged to a given level of voltage. An inadequate relation between the voltages across the flying capacitors (the unbalance state) results in the increase of the voltages above their rated values across the switches. An RLC series circuit (a balancing circuit) with the properly selected resonance frequency is connected in parallel to the load in order to eliminate the unbalance. The balancing process with the use of passive RLC depends on the configuration and parameters of the balancing circuit, the parameters of the converter, as well as on the operating conditions. This paper presents the mathematical description of both the converter and the balancing process, the balancing circuit approach in the different topologies of the multicell converters, a selection of the balancing circuit parameters, and the analysis of the improper control conditions.

A Novel Speed Measurement Method for a High-Speed BLDC Motor Based on the Signals From the Rotor Position Sensor

The paper presents a digital algorithm of a speed control block for a dc brushless motor and a method for measuring the motors rotational speed based on the signals from the rotors position sensor. The proposed method allows an increase in the measurement frequency (six measurements per rotation for a two-pole motor or 12 measurements for a four-pole motor) and the measurement results are not affected by the misalignment mounting of the sensor. The paper describes a conceptual structure of a series PI controller.

Energy storage systems the flywheel energy storage

Storage of energy is one of the main problem of contemporary technology. Currently used manners of the energy store are listed below: (1) the magnetic accumulator - the energy is kept in the magnetic field of superconductive inductor, (2) the accumulator with super capacitors. The low voltage (1,6-2,5 V) is the fault of this one,(3) the accumulator with lead-acid or alkaline accumulator. The fault of this solution is very low charging and discharging efficiency, (4) the electromechanical accumulator. Flywheels store energy mechanically in the form of kinetic energy. In this article the flywheel energy storage will be described precisely and compared with other energy storage technologies.

Multicell DC/DC Converter with DSP/CPLD Control. Practical Results

The paper presents practical investigations of DC/DC multilevel, multicell converter with DSP/CPLD control. A flying capacitors topology, natural balancing process and method of control of three-cell DC/DC converter are presented. Practical realization of the controller with use of programmable logic, discrete regulators in signal processor, procedures of initial flying capacitors charging, protection and turn-off the converter are described

The High-Speed Flywheel Energy Storage System

At the present level of technology the electricity generation has already ceased to be a problem. However, years are passing by under the slogan of seeking for methods of effective energy storage. The energy storage method shall be feasible and environmentally safe. Thats why the methods, once regarded as inefficient, are recently taken into consideration. The development in materials technology (carbon fibre, semiconductors, etc.) brought back the concept of a flywheel. This idea has been applied to high-speed flywheel energy storage.