Suchergebnisse

A method for the parametric analysis of electric generators of reciprocating motion with permanent magnets has been developed, which allows revealing the values of the parameters of the magnetic circuit (cross-sectional area) and the working winding (number of turns) at a given value of the efficiency, providing a minimum specific gravity of the generator. The method of parametric analysis of electric generators of reciprocating motion with permanent magnets consists of three stages. The first and second stages are the electromagnetic calculation of the generator: at the first stage, the main geometric dimensions of the magnetic system and the parameters of the working winding of the generator are determined; at the second stage, the verification of the electromagnetic calculation of the generator, calculation of the nominal mode, calculation of the efficiency and assessment of the thermal state of the generator are fulfilled. At the third stage, a parametric analysis of electric generators of reciprocating motion with permanent magnets with specified constraints is carried out, as well as the refinement of the geometric dimensions and configuration of the magnetic system of the generator using a two-dimensional finite element model of the magnetic field. As a result, to ensure better use of the electrical steel of the magnetic circuit of the generator and thereby reduce its mass, the most saturated areas and areas, which are characterized by low values of the magnetic field strength, are determined. Distinctive features of the proposed technique are: the use of a minimum specific gravity of electric generators of reciprocating motion with longitudinal, transverse or combined changes in the magnetic flux passing through the working winding as an objective function; combined approach to electromagnetic calculation; taking into account the influence of the operating temperature on the parameters of the permanent magnet, as well as overheating of individual parts of the generator.

A system for vector control of current in the circuit of a polyphase electric machine has been developed. For this, on the basis of the analysis of electromagnetic processes in a multiphase semiconductor converter of electrical energy, its discrete mathematical model was created, which takes into account the redistribution of electromagnetic energy by individual spatial harmonic components depending on the number of phases. Using this mathematical model and the scheme of injection of higher current harmonics, which provides a polyharmonic mode of operation of a semiconductor converter, a method for independent control of the spatial harmonic components of the input current of the converter has been developed. The formation in each of the phases of polyharmonic currents, conjugated in shape and phase with the voltage supplying the converter, is carried out by means of control actions in the form of voltage vectors of a semiconductor switch, the implementation of which is carried out by the method of multiphase space-vector modulation. To check the developed provisions, a simulation model of a nine-phase semiconductor converter of electrical energy with a vector control system was created. The results of the study of the model confirmed the adequacy of the developed technical solutions, the use of which will ensure the most complete realization of the own advantages of a multiphase electric machine in order to generally improve the weight, size and energy indicators of the autonomous power supply system.

The autonomous power supply system (APSS) from synchronous magnetoelectric generator and active voltage rectifier (AVR) maximally meets the requirements of the minimum specific mass and the complete coordination of the primary electric power source with the load. With multiphase (m > 3) execution of the electric machine, it is possible to obtain a trapezoidal electromotive force (EMF) and increase the specific power conversion provided that the EMF and the current at the output of the m-phase generator are fully matched. Therefore, the aim of the work is to synthesize the space-vector modulation (SVM) algorithm of the active voltage rectifier to fully match the primary source of electrical energy with the load under the condition of a trapezoidal EMF of the generator. Synthesis of the PVM algorithm for the m-phase AVR is based on the use of a vector-matrix mathematical apparatus. Using the example of a nine-phase system, a SVM algorithm has been developed, the feature of which is the transformation of the generalized voltage vector m-phase coordinate system into (m – 1)/2 voltage vectors with different angular velocities in two-phase orthogonal stationary αβ coordinate systems. At the same time, based on the developed PVM algorithm, it is possible to independently control the (m – 1)/2 voltage vectors in the corresponding αβ planes, providing a signal similar to the EMF of the generator at the input terminals of the AVR. In order to confirm the theoretical propositions, an imitation model of the space-vector modulation unit for the realization of trapezoidal signals at the terminals of a nine-phase AVR has been developed. The efficiency of the developed algorithm is confirmed by the results of simulation modelling. As a result of the evaluation of the energy parameters (operating power) of the phase of power supply system direct current, it is established that the application of the developed space-vector modulation algorithm for the active voltage rectifier in order to fully match the trapezoidal shape of the EMF and the current at the output of the m-phase generator will increase the power of the APSS by 14 % compared to a power supply system of direct current with a sinusoidal form of the EMF and the current of the generator phase. It is established that the developed measuring device can be used to establish the presence of defects like "delamination". The influence of the depth of the defect placement on the measured parameters is shown.