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This paper proposes a four-degree-of-freedom control method for a dual active Flexbattery H-Bridge converter, which operates similarly to dual-active- bridge converters. The Flexbattery pack is constructed from multiple modular units and each unit contains one voltage source, one inductor and four switches. Due to the cascaded structure of the pack, it is able to generate high-frequency square-waveform...
This article presents a study of a design of four controllers to a ladder converter modeled by the generalized equivalent continuous model. Two controllers are designed minimizing the energy of the input and minimizing the states; and the other two controllers are designed minimizing the changes in the input, and the states. Also, the article shows a Kalman filter with shaping noise filter to estimate...
A new control method for three-phase-bridge inverter with improved neutral forming transformer (INFT) is presented in this paper. The controlling PWM signal is obtained by combining the switching point preset PWM and unipolar SPWM, and the fundamental and harmonic content of the controlling signal are analyzed. By analysis of the relationship of phasor voltage of neutral forming transformer, an improved...
In this paper, a cost effective novel cascaded H-Bridge multilevel inverter topology is proposed. This topology is based on a cascaded connection of single-phase novel H-bridge converters with less number of components. When compared with the conventional multilevel converters, the number of DC voltage sources, switching devices, installation area, and converter cost is significantly reduced. For...
The widespread usage of power electronic in the end-user had increased the harmonic generation at the distribution level. Conventional, Passive Power Filter (PPF) is used to improve the power quality. However, in practice, there are several drawbacks to this filter. Therefore, Active Power Filter (APF) became a better solution to reduce harmonic distortion. APF will produce a compensation current...
This paper presents an advanced control scheme using repetitive controller (RC) to improve performance of three-phase AC/DC/AC converter in UPS application. To guarantee a high quality output voltage of UPS, i.e., balanced and sinusoidal under various types of load, a proportional integral (PI) plus RC is employed in the inverter control scheme. Meanwhile, to achieve unity power factor operation for...
This paper proposes a simple power circuit topology for single phase unified power quality conditioner (UPQC). The number of power circuit switches of conventional single-phase UPQC is reduced to half and hence it has resulted in considerable reduction of cost, weight, volume, protection circuits, power losses and control circuit complexity. The proposed system compensates for the utility voltage...
This paper will analyze the power quality of multilevel voltage waveforms generated using three modulation strategies: i) a conventional nearest level control (NLC) strategy, ii) NLC with harmonic elimination, and iii) optimized selective harmonic elimination (OSHE). A uniform sampling frequency of the sinusoidal voltage is considered for NLC modulation. It is found in all selected experimental results...
Multilevel converters (MCs) are utilized in medium voltage (MV) high power applications due to its higher efficiency than two level converters. On the other hand, modular multilevel converters (MMCs) provide several advantages with regard to other MCs, such as higher scalability, reliability and no requirement of a common DC capacitor. Particularly, low switching frequency modulations, such as (2N+1)...
In this paper two recent presented active grid current stabilisation strategies for direct matrix converter based drives with squirrel-cage asynchronous induction machines are compared with there passive counterparts. While the functionality of the active stabilisation strategies has been proven already this publication focuses on the harmonic distortion of grid and machine current as well as the...
For the future of sustainable energy, renewable energy will need to significantly penetrate existing utility grids. While various renewable energy sources are networked with high-voltage DC grids, integration between these high-voltage DC grids and the existing AC grids is a significant technical challenge. Among the limited choices available, the modular multi-level converter (MMC) is the most prominent...
A new 3-phase current controlled PFC rectifier has been proposed in this paper. Phase difference in between input voltage and current is minimized using an a-periodic control signal generated using input current, phase angle of input voltage, and output voltage. A 1V (P-P) 5KHz triangular wave is used here to generate PWM signal. Simple PID controllers have been added with the controller of the rectifier...
This paper proposes a variable time step controller with synchronous PWM. Since a frequency modulation index is low in an ultra-high speed or high power drive system, the modulated voltage by a fixed time step control includes large harmonic components. The optimal PWM method is one of the solution to minimize the harmonic components, but it needs many offline calculations and its structure is complicated...
This paper presents two hybrid four-leg inverters that can be be employed in unbalanced three-phase systems. The proposed topologies are based on a modular multilevel cascade converter (MMCC) with double-star chopper cells (DSCC) associated to a conventional two-level (2L) leg. A comparative analysis in terms of the harmonic distortion and semiconductor power losses between the proposed configurations...
The conventional Buck PFC converter adopts constant duty cycle control (CDCC), which can improve the PF to some degree. However, the peak and RMS values of the inductor current are large, which also occurs to the switch and diode. This paper derives the expressions of the input current and PF of DCM Buck PFC converter, and based on which, a kind of injecting 3rd current harmonic control (ICHC) is...
This paper presents a neutral point deviation compensating control algorithm applied to a 3-level NPC converter. The neutral point deviation is analyzed with a focus on the current flowing out of or into the neutral point of the dc-link. Based on the zero sequence components of the reference voltages, this paper analyzes the neutral point deviation and balancing control for 3-level NPC converter....
Selective harmonic elimination technique can eliminate any order harmonics theoretically, but it is restricted by the initial value of switching angles and the switching speed of power device, therefore, it has surplus high-order harmonics. The surplus harmonics exist in the form of harmonics group, there is a window which harmonic wave amplitude close to zero between the adjacent harmonic group....
The study of AC-DC matrix converter under unbalanced power grid is mostly focused on the suppression of the two harmonic of output voltage. In this paper, the voltage type AC-DC matrix converter under unbalanced power network is studied, focusing on the control of the three-phase current in the grid side and the predictive unbalance control strategy with negative sequence voltage compensation is proposed...
The paper develops a mathematical model for a modular multilevel converter (MMC) using extended-frequency dynamic phasors. The developed model is capable of capturing both the low- and high-frequency dynamic behavior of the converter depending on the requirements of the study to be performed. The paper shows the mathematical development of the model, its validation against a fully detailed electromagnetic...
Line Commutated HVDC converter stations consume large amount of reactive power. If the converters are connected to weak grid, then the reactive power is provided locally using large capacitor banks or synchronous generators. These capacitor banks along with filters possess most part of the converter station. Construction of such a large converter stations for off-shore application is very difficult...
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