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EPE Journal Volume 24-2 - Papers
- Research on Commutating Over-Voltage Protection for High Power Converter
- A Direct Method for Generating Optimum Sequence of Switching Vectors for Multilevel Inverters
- A PFC Based BLDCM Drive for Low Power Household Appliances
- Improvement of the Performance of DC/DC Converter Used for Transportations Applications. Test of Different Control Strategies
- Optimized Control of Multi-Terminal DC Grids Using Particle Swarm Optimization
- Space-Vector-Based Controller for Current-Harmonic Suppression with a Shunt Active Power Filter
EPE Journal Volume 24-2 - Editorial
By B. Sneyers
EPE Jounal Volume 24-2 - Editorial
EPE Journal Volume 24-2 - Papers
By Fengwei Zha; Zhiquan Song; Peng Pu; Lin Dong; Min Wang
In the course of converter normal operation, large transient surges called commutating over-voltage may be generated internally during the commutating process of thyristor. The commutating voltage can effectively be reduced by the RC snubber circuit parallel to thyristor. In the RC snubber circuit design of high power thyristor, the reverse recovery process of thyristor must be considered in detail. Based on the analysis about reverse recovery transient of thyristor, the mathematical model of the converter thyristor reverse recovery current is created. Through the equivalent transformation of converter circuit during thyristor reverse recovery period, the analytical expressions about the relationship between commutating over-voltage and RC value are derived based on the Kirchhoff's equation. Utilizing the analysis results, the optimal resistance and capacitance value can be selected by considering the reduction of peak over-voltage value and snubber power loss. It turns out that the proposed approach is available through the commutating over-voltage simulation and experiment results of high power converter.
By Anish T.; Anish Gopinath; Shiny G.; M.R. Baiju
The paper presents a generalized method for generating Space Vector PWM (SVPWM) signals in an optimum sequence directly from the instantaneous amplitudes of the reference vector without using any look up tables. The proposed method is based on the observation that for every inverter voltage vector in each of the three 120° regions in the space vector representation of a multilevel inverter, one of the three switches (defining the switching state) is at ‘0’ level. The overall voltage space vector representation of a multilevel inverter is thus divided into three segments on the basis of the switching state at ‘0’ level. This observation is used to generate the switching states directly from the coordinates of the inverter switching vectors. The relation between the inverter switching vectors and their corresponding switching states emerge as a consequence of representing the vectors in the sixty-degree coordinate framework thus avoiding fractional coordinates of the switching vectors. In the present work, simple generalized equations involving only arithmetic operation are also developed for generating the duty cycles for the gating signals in optimum sequence, from the switching states and their durations. The proposed method can be used for the direct generation of SVPWM for any n-level inverter. Experimental results are presented for an open-end winding based 5-level inverter.
By Vashist Bist; Bhim Singh
This work presents a low cost PFC (Power Factor Correction) based BLDCM (Brushless DC Motor) drive targeting low power household appliances. Development of a highly efficient BLDCM drive with minimum amount of sensing requirement is the primary objective of this work. The switching losses in the VSI (Voltage Source Inverter) feeding BLDCM is reduced by electronically commutating the BLDCM and controlling its speed by controlling the voltage of the DC bus. A PFC buck-boost converter is used as a front-end converter due to its simplicity in design, minimum number of component count and its ability to buck and boost the voltage to control the speed over a wide range. The PFC buck-boost converter operating in DICM (Discontinuous Inductor Current Mode) is used for the control of DC bus voltage. An inherent PFC is achieved for variation of speed over a wide range at universal AC mains (90-265 V). The obtained PQ (Power Quality) indices are within the recommended limits of international PQ standards IEC 61000-3-2. The performance of proposed BLDCM drive is simulated in MATLAB/Simulink environment and validated experimentally on a developed prototype of the drive.
By Alaa Hijazi; Eric Bideaux; Pascal Venet; Guy Clerc
This paper presents a study on DC/DC converter with supercapacitor stack for a trolleybus. After the description of transportation application, the performance of the system is studied by testing different control strategies. The comparison of SMC (Sliding mode Control) and PI controller on a developed test bench has shown the benefit of SMC in this type of applications.
By Kumars Rouzbehi; Arash Miranian; Alvaro Luna; Pedro Rodriguez
The electric networks of the future will make an extensive use of DC grids. Therefore, the control of Multi-terminal DC (MTDC) grids is a key issue, which is gathering the attention of the industry and the research community. In this regard, this paper proposes a grid control strategy for voltage-source converter (VSC)-based MTDC networks, based on the use of the particle swarm optimization (PSO) technique. In the proposed approach, the controllers of the power converters belonging to the MTDC grid are acting based on the concept of vector control, in which the AC currents and voltages are transformed into a rotating direct-quadrature (dq) reference frame for controlling of the active and reactive powers as well as the DC and AC voltages. Since the VSCs are nonlinear plants in nature, the classical approaches for tuning of the control system, which are usually based on the approximate linear model of the plants, do not lead to optimal results. As an alternative, in this paper an efficient PSO algorithm is used for tuning optimally the parameters of the controllers in the MTDC grid. In addition, the voltage droop control scheme is utilized to ensure the active power balance within the MTDC grid. The simulation results, obtained through a detailed model of a four-terminal DC grid, demonstrate the efficiency of the proposed approach. Finally a comparison with PI controllers which have been conventionally tuned also confirmed the favorable performance of the proposed PSO-tuned controllers.
By Miguel Ochoa-Giménez; Javier Roldán-Pérez; Aurelio García-Cerrada; Juan Luis Zamora-Macho
Active power filters are often proposed as flexible solutions to tackle power quality problems in electric distribution systems. It is well known that the need for tracking harmonic currents and voltages with these electronic devices exceeds the capabilities of conventional Proportional+Integral controllers and more sophisticated algorithms are sought. This paper presents a control method based on multiple reference frames for tracking or rejecting periodic signals in this context. The proposed scheme allows recursive calculation when referring signals to reference frames rotating synchronously with harmonic equivalent space vectors whilst only a very small number of trigonometric-function evaluations are required. Furthermore, using the proposed approach, the control of each harmonic can be dealt with using the same simple Integral controller. Experimental results of a shunt active power filter are provided to validate the main contributions of the paper, including an scenario with grid-frequency variation to evaluate the adaptation capability of the proposed controller.
EPE Journal Volume 24-2: Other
By B. Sneyers
The EPE Awards 2014 were presented on Wednesday 27 August 2014 in Lappeenranta. Open the article to find out who the awardees were.