Pełna lista publikacji

Tytuł Data publikacji Autor
This paper presents primary-side voltage regulated multi-transformer quasi-resonant flyback converter (MTFC) for supplying isolated power switch drivers. The proposed topology offers distinct advantages over frequently used flyback converter possessing one high frequency transformer with isolated multiple outputs. Particularly, when a large number of separate dc supply units is required, then MTFC enables improved regular distribution of magnetic coupling between the common primary and the multiple secondary transformers' windings providing high degree of galvanic and electromagnetic isolation between multiple outputs. Primary side voltage regulation is based on the average value of output voltages estimation using auxilliary RDC circuit mounted across the primary windings. Operation principles of MTFC are enhanced with analytical study of cross regulation of multiple output voltages at unbalanced load conditions, indicating reduced voltage deviation of multiple outputs by applying the primary-side average voltage regulation. Experimental results of prototype 2, 3, and 6-transformer quasi-resonant flyback converters confirmed their cross regulation quality and application potential for independent multiple output supplies.
2020
Maciej Kolincio,
Piotr Chrzan,
Piotr Musznicki
The paper proposes an alternative and novel approach to the PWM duty cycles computation for Conventional Matrix Converters (CMC) fed by balanced, unbalanced or non–sinusoidal AC voltage sources. The presented solution simplifies the prototyping of direct modulation algorithms. PWM duty cycles are calculated faster by the smooth interpolation technique, using only vector coordinates, without trigonometric functions and angles. Both input voltages and output reference voltages are expressed by analytic signals in the proposed direct modulation. Input voltages are represented by the rotating vector collection in the two–dimensional Cartesian coordinate system. All reference output voltages are located inside the triangular surface, named here as the voltage synthesis field, formed by these rotating vectors. A certain degree of reference signals placement freedom allows to maximize the voltage transfer ratio to 0:866 with less switching compared to the Optimum–Venturini direct method. The proposed solution was verified by simulations and experiments for CMC3xk. The comparison with the Optimum–Venturini modulation is included. The proposed PWM duty cycle computation approach can also be applied to multiphase CMC converters for any number of inputs as well as outputs.
2020
Paweł Szczepankowski,
Patrick Wheeler,
Tomasz Bajdecki
The paper presents a novel approach to the Pulse Width Modulation (PWM) duty cycle computing for complex or irregular voltage vector arrangements in the two (2D) and three–dimensional (3D) Cartesian coordinate systems. The given vectors arrangement can be built using at least three vectors or collections with variable number of involved vectors (i.e. virtual vectors). Graphically, these vectors form a convex figure, in particular, a triangle or a tetrahedron. The reference voltage vector position inside that figure can be expressed by the barycentric coordinates, which are calculated using the second (2D case) or the third–degree determinant (3D case) – without trigonometry and angles. Thus, the speed of the PWM duty cycle computation rises significantly. The use of the triangle area or the tetrahedron volume, instead of the standard vector projection also permits for a well–defined and universal approach to identifying the reference vector position, especially for converters with complex and/or deformed space–vector diagrams (i.e. floating DC–link, multisource DC–link). The proposed computation scheme is based on simple instructions without trigonometry thereby, the DSP processor, or digital solution for field–programmable gate array, can fast–perform this operation using atomic operations. The aim of the presented considerations is not a novel PWM modulation, but a computable idea of a general calculation scheme for cases in which the distribution of vectors is non-trivial. A detailed algebraic and geometric analysis, as well as mathematical proofs on the total consistency of the results with the standard projection method, are also included. Subsequently, the Three–Dimensional Space Vector Modulation (3D–SVM), is considered as a special background to present a novel approach.
2020
Paweł Szczepankowski,
Nikolai Poliakov,
Denis Vertegel,
Krzysztof Szwarc,
Ryszard Strzelecki
The paper describes a synchronous generator model developed based on the multiple reference frame theory. The main physical phenomena included in the model are the machine armature non-sinusoidal voltage waveform and the influence of armature current in load conditions on the armature voltage waveform higher harmonic components. The modified multiple reference frame theory model is proposed. In this modified theory model the field and armature currents are the cause of the non-sinusoidal airgap spatial field distribution. The influence of this airgap spatial field distribution is also investigated. The resulting nonuniform saturation of the pole shoe affects the machine voltage waveform in load conditions. Simulation and measurements of the machine performance in steady and transient states are conducted in order to validate the model.
2020
Filip Kutt,
Michał Michna,
Grzegorz Kostro
This paper proposes the generalized direct modulation for Conventional Matrix Converters (CMC) using the concept of analytical signals and barycentric coordinates. The paper proposes a novel approach to the Pulse Width Modulation (PWM) duty cycle computing, which allows faster prototyping of direct control algorithms. The explanation of the new idea using analytical considerations demonstrating the principles of direct voltage synthesis has been presented in the article. The study concerns mainly the CMC3x3 but solutions for 3xn, 5x5, and 5x3 topologies have also been discussed. The transformation of instantaneous input voltages to analytic signals great permits for simple presenting of real input voltage conditions such as waveform type, asymmetry or other deformation like higher-order harmonics. The proposed interpolation methods allow for determining the values of PWM duty cycles using simple formulas based on the determinants of the 2nd-degree matrices. Therefore, the proposed method, which based on the barycentric coordinates, frees an algorithm from trigonometry and angles.
2020
Paweł Szczepankowski,
Tomasz Bajdecki,
Ryszard Strzelecki
Wyświetlanie 1 - 5 z 285 rezultatów.
z 57
RSS (otwiera nowe okno)