Том 88, № 2 (2017)

A floating buoy absorber that allows direct conversion of wave energy into electricity using a linear generator is a simple, but promising, device for conversion of wave energy. Results of studies of direct conversion of wave energy using a moored floating point absorber and linear synchronous generator are considered in this paper. The average power and performance of a linear synchronous generator have been determined for a significant wave. An algorithm for calculations of equivalent frequencies and emf amplitudes has been suggested for a modular design of the linear synchronous generator. The analytical expressions and dependences to determine the number of pole pairs and modules, as well as the main dimensions of the machine, have been obtained. It has been concluded that it is necessary to increase the number of poles of a linear generator to obtain an efficient design with reduced weight and overall dimensions. Application of the concentrated winding and permanent magnets with a tangential position has been justified. The parameters of electromagnetic fields and the synchronous generator for different operational conditions have been determined by the finite-element method. The design data and parameters of the six-module, 16-pole SLGPM-30-16 permanent magnet linear generator with a rating power of 30 kW are considered. The design has been optimized by calculations of the electromagnetic field; as a result, a weight of the generator has been reduced and much higher specific ratings than those in similar developments and in other devices for converting ocean-wave energy have been obtained.

Seven control algorithms of a five-phase converter running on a five-phase symmetrical load have been analyzed. A theoretical study of the formation of resultant rotating vector of current when implementing seven control algorithms has been carried out. The space of states of the resulting rotating vectors of a five-phase converter includes six switching sequences: three sequences of five keys, one sequence of three keys, and one sequence of two keys. Each of these switching sequences can be used to form a symmetrical five-phase voltage required for feeding a five-phase motor. The sequence of commutations that generate voltage that is symmetrical in time, but do not provide the formation of a circular rotating field using the five-phase winding, has been investigated. Experimental results confirming theoretical studies are given.

The application of controlled series-compensation devices (SCDs) is one trend in development of controlled electric-power lines (EPLs). The influence of controlled SCDs on the regimes and stability of an electric-power system with two generating plants was considered. The methods of mathematical modeling, numerical integration, D decomposition, and computing experiment were used in the research. It was revealed that controlled SCDs make it possible to increase the EPL capacity and have a positive effect on the margins for the static aperiodic and dynamic stability, without leading to instability at compensation typical for the operating regimes of electric-power systems (EPSs). The methodology for determining the range of change of the parameter of a controlled SCD in order to define its optimal amount making it possible, on the one hand, to have a maximum positive effect on EPL capacity and static aperiodic and dynamic stability and, on the other hand, to prevent oscillatory instability was proposed. The possibility of constructing smart-grid networks based on controlled SCDs is revealed. The construction of a smart-grid network with use of controlled SCDs leads to the creation of highly integrated, new-generation smart electricity networks that are characterized by increased EPL capacity and increased static- and dynamic-stability margins.

In this paper, a soft-start circuit is present to prevent the large surge current and overshoot voltage to improve the reliability of the DC-DC converter. The proposed structure generates the step-shaped soft-start voltage through 7 bits DAC. Combining with the PWM comparator, the soft-start circuit controls the system duty cycle directly. The mechanism of the soft-start acts as the high clamp function, which eliminates the need of the clamp circuit. A DC-DC buck converter with the proposed soft-start circuit is based on a 0.4 μm BCD process for verification Hspice simulation shows that under the condition with 3.6 V input voltage, 1.8 V output voltage and 600 mA load current, the soft-start is achieved. After 1.2 ms of the soft-start time, the operation turns to stable.