Abstract
The paper presents the results of testing and research of the characteristics of a controlled autonomous magnetoelectric synchronous generator with a magnetic shunt. Structurally, the studied generator is a modified asynchronous machine in which the rotor is made with permanent magnets and an additional system in the form of a magnetic shunt. By adjusting the winding current of the magnetic shunt, the output voltage of the generator is regulated. The following characteristics were investigated: the no-load characteristic during operation with permanent magnets and when the winding current of the magnetic shunt changes with forward and reverse polarity. Also, the external characteristic for active and active-inductive loads; the control characteristic when the load current changes at a constant generator voltage. Analysis of the obtained characteristics makes it possible to determine the limits of regulation of the external characteristic, which is ≈40 % relative to the main magnetic flux. The obtained regulation depth allows maintaining the stability of the external characteristic for power factors not exceeding 0.9, which is the usual passport value for autonomous power plants based on synchronous generators. Comparison of the data of research conducted on the experimental setup shows sufficient convergence for engineering and practical tasks. The maximum quantitative difference is 9.3 %, which suggests the adequacy of the previously developed mathematical model. The control characteristic, constructed experimentally at constant generator voltage, is the control law of the magnetic shunt winding for the studied generator. The investigated version of a synchronous generator with a magnetic shunt should be used for autonomous power plants, renewable energy systems, and autonomous power supply systems.
Highlights
The achievements of the last 10 years in the field of creating new highly coercive rare-earth permanent magnets (NdFeBr and SmCo) made it possible to develop new contactless electric machines with powerful magnetoelectric excitation systems
One of the promising areas of this topic is the development of magnetoelectric generators with magnetic shunting, which allows controlling the magnetic flux in the core
The following objectives were set: – to obtain the no-load characteristics with the direct and reverse polarity of the power supply of the magnetic shunt winding with a further comparison with the calculated data; – to obtain the external characteristic at different power factors and compare the results with the calculated data; – to determine the control law of the magnetic shunt winding current, while maintaining a constant value of the output voltage, which is analogous to the traditional control characteristic
Summary
The achievements of the last 10 years in the field of creating new highly coercive rare-earth permanent magnets (NdFeBr and SmCo) made it possible to develop new contactless electric machines with powerful magnetoelectric excitation systems. An example of a promising development is stand-alone magnetoelectric synchronous generators for unconventional and renewable energy sources. These designs do not need excitation from an external source through a contact system, as in traditional generators with an electromagnetic excitation system. A relevant scientific and practical direction is the study of the efficiency of the developed and manufactured magnetoelectric generator with a magnetic shunt and radial magnetic flux. This generator is based on the design of a classic AC machine with a traditional stator. The relevance of the work lies in the use of commercially available asynchronous motors, which can be modified to produce controlled permanent-magnet synchronous generators
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