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Series connected IGBTs provide a useful method to improve the voltage level, and which is a very important approach to achieve high-voltage power converters. However the imbalance of collector-emitter voltages across IGBTs is a key issue that must be addressed. This paper proposed a novel type of series connected IGBT circuit with voltage self-balance by using clamping diode and snubber capacitor,...
Accelerated developments of renewable energy production technologies and their integration to existing AC microgrids have led to the emergence of several new inverters control schemes. The recently introduced proportional resonant (PR) controllers have the ability to precisely track AC quantities and are increasingly used in grid supporting inverters, especially for current control loops which are...
This paper presents an approach for upgrading droop control aimed to improve its performance when used for two parallel inverters. The proposed control ensures equal voltage for the two inverters when different power flowing through them which guarantee zero current circulation. To fulfill the voltage regulation, the second inverter (slave) regulates its voltage to follow the master inverter reference...
This paper proposes a Current Deadbeat Control (DBC) algorithm for a three-phase 9-cells qZS based Cascaded H-Bridge (CHB) inverter to ensure grid current supply with low THD. The studied topology is considered as a single-stage DC/AC topology having the capability of boosting the DC input voltage with high-quality multilevel AC voltage, independent DC-link voltage compensation, and control of the...
Battery energy storage systems play a vital role in renewable energy based electric power grids. Inverters are essential to integrate DC energy storage devices such as batteries to AC power grids. In this paper, a cascaded boost inverter topology based single-phase grid-connected battery energy storage system is presented. A current feedback ripple reduction method is used to mitigate the second-order...
In this paper, the relationship between real and reactive power sharing in islanded microgrid considering the complex impedance effect is analyzed. It is determined that traditional droop control has drawbacks in achieving accurate power sharing caused by the mismatched feeder line effect. In order to enhance the power sharing accuracy, an adaptive droop control using virtual impedance for islanded...
This paper realizes a high power factor, high reliability, and low cost PMSM drive system with small DC-link capacitor. Compared with conventional bulky electrolytic capacitor for the regulation of DC-link voltage, a small-size film capacitor with capacitance reduction to 1% is used to realize a seneorless PMSM drive with high power factor, high reliability, and high compactness. To overcome high...
This paper presents an optimized active power control method for two-stage photovoltaic (PV) grid-connected inverter under unbalanced grid faults. The purpose of the control method is to reduce the active power deficit of grid by injecting the maximum active power of the PV system under the premise of ensuring the safety of the inverter itself. Safe operation region (SOR), which considers the limitation...
The hybrid high voltage direct current (Hybrid HVDC) system based on line commutated converter (LCC) and modular multilevel converter (MMC) is a feasible solution for long distance bulk power transmission. In order to handle the dc-side short-circuit fault, two kinds of methods can be adopted. The first one is to replace half-bridge sub-modules (HBSMs) with full-bridge SMs or clamp-double SMs which...
This paper presents a closed loop control design for the class-E2 WPT system with the pre- and post-regulation. In the proposed WPT system, the output voltage is regulated by changing the switch-on duty ratio of the post regulator, whose information is transmitted to the primary side by wireless communication. At the transmitter side, the input current is minimized by changing the switch-on duty ratio...
A three phase to five phase configured twenty pulse AC-DC converter fed 3-level modular multilevel inverter (MMLI) based vector controlled induction motor drive (VCIMD) is presented in this work. To limit the total harmonic distortion (THD) in the utility current as per IEEE-519 standard, a twenty pulse AC-DC converter is used at the input end of the proposed drive. A three phase system is converted...
In railway traction applications, due to the limitation of switching frequency and the attempt to fully utilize the DC-link voltage, the traction inverters usually work in six-step (or quasi-square-wave) mode under heavy load or high frequency condition. Meanwhile, DC-link voltage fluctuation, stemming from a common single-phase grid-side power supply, has a great impact on the drive system. To maintain...
This paper proposes an improved control strategy for switching frequency variation in hysteresis current controlled Voltage Source Inverter (VSI) fed induction motor (IM) drives. The advantages of simple hysteresis controller like simple implementation and fast dynamic response along with nearly constant switching frequency and reduction in current ripple are obtained in the proposed controller. Elimination...
Model predictive control (MPC) has recently emerged as a powerful control method for ac motor drives, featuring quick dynamic response and intuitive concept. However, conventional MPC requires lots of calculation resources due to the enumeration of each possible voltage vector, especially in the case of a multilevel converter. To achieve good performance with low switching frequency for high power...
The paper presents an overview about operation and control of the inverter-interface generation units (IGUs) when connected to a microgrid either alone or together with other generation units. The following key connection paradigms are considered: i) one IGU and a grid, ii) one IGU and one machine-interface generation unit, iii) a single IGU, and iv) two IGUs. After illustrating how the IGUs operate...
This paper investigates the problem of accurate active power sharing in virtual flux droop where flux angle droop control is used for DG controllers instead of traditional frequency droop control. Firstly, the virtual flux droop control method is introduced. Then, the reasons for inaccurate active power sharing in flux angle droop are analysed. Further, to solve this problem, an active power compensation...
In this paper a laboratory power inverter platform is proposed. The platform can operates autonomously by choosing an adequate signal processor or controlled by the powerful dSpace 1104 board, facilitating the rapid implementation of the design algorithms. At the same time, scalar and field oriented control of the three-phase asynchronous machine through the ControlDesk tool have been developed. Functional...
The design of a digital state-space controller employing a deadbeat state observer is presented for uninterruptible power source (UPS) inverter applications with inductor-capacitor (L-C) filters. Conventionally, the inductor current and capacitor voltage values are utilized as the measured feedback variables for the controller, and the load current is either measured or estimated. In the proposed...
In distributed generation and modern smart grids, the voltage source inverter (VSI) is commonly used as a basic interface between the different power sources and devices. The control capabilities of the VSI are very essential in transforming the passive distribution network into an active one. In this frame, the modeling, control and stability analysis of a VSI, standing as an interface between a...
The contribution deals with steady state estimation of an electromagnetic torque ripples and a current waveform of a two-phase induction motor (IM) supplied by an three-leg IGBT bridge connected voltage source inverter (VSI). The inverter's output voltage is controlled by a modified sinusoidal SPWM of the input DC voltage. The complex Fourier series analysis of the inverter's output voltage was made,...
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