• Title/Summary/Keyword: Synchronous converter

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Design of Robust Current Controller Using GA for Three Level 24-Pulse VSC Based STATCOM

  • Janaki, M.;Thirumalaivasan, R.;Prabhu, Nagesh
    • Journal of Power Electronics
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    • v.11 no.3
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    • pp.375-380
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    • 2011
  • A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).

Microprocessor Based Permanent Magnet Synchronous Motor Drive (마이크로 프로세서에 의한 영구자석동기 전동기의 구동)

  • Yoon, Byung-Do
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.35 no.12
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    • pp.541-554
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    • 1986
  • This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

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A High Efficiency MHD Lamp Ballast with a Frequency Controlled Synchronous Rectifier (주파수 가변 동기 정류기를 이용한 고효율 MHD 램프 안정기)

  • Hyun B.C.;Lee I.K.;Cho B.H.
    • Proceedings of the KIPE Conference
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    • 2004.11a
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    • pp.71-75
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    • 2004
  • In this paper, in order to develop a simple and high efficient ballast without an external igniter, a half-bridge type ballast with a coupled inductor and a frequency controlled synchronous rectifier is proposed. The internal LC resonance of the buck converter is used In generate a high voltage pulse for the ignition, and the coupled inductor filter is used for steady state ripple cancellation. Also, a synchronous buck converter is applied for the DC/DC converter stage. In order to improve the efficiency of the ballast, a frequency control method is proposed. This scheme reduces a circulation current and turn off loss of the MOSFET switch on the constant power operation, which results in increase of the efficiency of the ballast system about $4\%$, compared to a fixed frequency control. It consists a 2-stage version ballast with a PFC circuit. The results are verified with hardware experiments.

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Individual DC Voltage Balancing Method at Zero Current Mode for Cascaded H-bridge Based Static Synchronous Compensator

  • Yang, Zezhou;Sun, Jianjun;Li, Shangsheng;Liao, Zhiqiang;Zha, Xiaoming
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.240-249
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    • 2018
  • Individual DC voltage balance problem is an inherent issue for cascaded H-bridge (CHB) based converter. When the CHB-based static synchronous compensator (STATCOM) is operating at zero current mode, the software-based individual DC voltage balancing control techniques may not work because of the infinitesimal output current. However, the different power losses of each cell would lead to the individual DC voltages unbalance. The uneven power losses on the local supplied cell-controllers (including the control circuit and drive circuit) would especially cause the divergence of individual DC voltages, due to their characteristic as constant power loads. To solve this problem, this paper proposes an adaptive voltage balancing module which is designed in the cell-controller board with small size and low cost circuits. It is controlled to make the power loss of the cell a constant resistance load, thus the DC voltages are balanced in zero current mode. Field test in a 10kV STATCOM confirms the performance of the proposed method.

Implementation and Control of AC-DC-AC Power Converter in a Grid-Connected Variable Speed Wind Turbine System with Synchronous Generator (동기기를 사용한 계통연계형 가변속 풍력발전 시스템의 AC-DC-AC 컨버터 구현 및 제어)

  • Song Seung-Ho;Kim Sung-Ju;Hahm Nyon-Kun
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.12
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    • pp.609-615
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    • 2005
  • A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.

Torque Predictive Control for Permanent Magnet Synchronous Motor Drives Using Indirect Matrix Converter

  • Bak, Yeongsu;Jang, Yun;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.19 no.6
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    • pp.1536-1543
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    • 2019
  • This paper presents an improved torque predictive control (TPC) for permanent magnet synchronous motors (PMSMs) using an indirect matrix converter (IMC). The IMC has characteristics such as a high power density and sinusoidal waveforms of the input-output currents. Additionally, this configuration does not have any DC-link capacitors. Due to these advantages of the IMC, it is used in various application field such as electric vehicles and railway cars. Recently, research on various torque control methods for PMSM drives using an IMC is being actively pursued. In this paper, an improved TPC method for PMSM drives using an IMC is proposed. In the improved TPC method, the magnitudes of the voltage vectors applied to control the torque and flux of the PMSM are adjusted depending on the PMSM torque control such as the steady state and transient response. Therefore, it is able to reduce the ripples of the output current and torque in the low-speed and high-speed load ranges. Additionally, the improved TPC can improve the dynamic torque response when compared with the conventional TPC. The effectiveness of the improved TPC method is verified by experimental results.

Transformer Parasitic Inductor and Lossless Capacitor-Assisted Soft-Switching DC-DC Converter with Synchronous Phase-Shifted PWM Rectifier with Capacitor Input Filter

  • Saitoh, Kouhei;Abdullah Al, Mamun;Gamage, Laknath;Nakaoka, Mutsuo;Lee, Hyun-Woo
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.217-221
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    • 2001
  • This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and loss less snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

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A High Quality Power Factor Correction Converter Based on Half Bride Topology (Half bridge 회로를 기반으로 한 역률개선용 컨버터)

  • 이준영;문건우;정영석;윤명중
    • The Transactions of the Korean Institute of Power Electronics
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    • v.2 no.3
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    • pp.26-36
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    • 1997
  • An single stage AC/DC converter based on half bridge topology suitable for low power level applications is proposed. The proposed converter has high power factor, low harmonic distortion, and tight output regulations. Asymmetrical control and synchronous rectification are adopted to reduce the switching loss and rectification loss, respectively. The modelling employing average modelling method and detailed analysis are performed to derive the design equations. According to these design equations, a prototype converter has been designed and experimented. This prototype meets the IEC 555-2 regulations with near unity power factor and high efficiency.

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Real-Time Hardware Simulator for Grid-Tied PMSG Wind Power System

  • Choy, Young-Do;Han, Byung-Moon;Lee, Jun-Young;Jang, Gil-Soo
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.375-383
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    • 2011
  • This paper describes a real-time hardware simulator for a grid-tied Permanent Magnet Synchronous Generator (PMSG) wind power system, which consists of an anemometer, a data logger, a motor-generator set with vector drive, and a back-to-back power converter with a digital signal processor (DSP) controller. The anemometer measures real wind speed, and the data is sent to the data logger to calculate the turbine torque. The calculated torque is sent to the vector drive for the induction motor after it is scaled down to the rated simulator power. The motor generates the mechanical power for the PMSG, and the generated electrical power is connected to the grid through a back-to-back converter. The generator-side converter in a back-to-back converter operates in current control mode to track the maximum power point at the given wind speed. The grid-side converter operates to control the direct current link voltage and to correct the power factor. The developed simulator can be used to analyze various mechanical and electrical characteristics of a grid-tied PMSG wind power system. It can also be utilized to educate students or engineers on the operation of grid-tied PMSG wind power system.

Sensorless Control of PMSG for Small Wind Turbines (소형 풍력발전용 영구자석형 동기발전기의 센서리스 제어)

  • Jang, Suk-Ho;Park, Hong-Geuk;Lee, Dong-Choon;Kim, Heung-Geun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.1
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    • pp.15-22
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    • 2009
  • In this paper, a sensorless control of PMSG(Permanent Magnet Synchronous Generator) for small wind turbine systems, which is based on stator flux and back-emf estimation. Also, a cost-effective AE/DC/AC converter that consists of a two-leg three-phase PWM converter and a half-bridge PWM converter is used for vector control of PMSG, which is impossible with the conventional diode-rectifier type converter. A sensorless control algorithm can eliminate pulse encoders for speed measurement, which reduces the system cost. Using PSIM simulation, the validity of the converter control performance and MPPT control of PMSG have been verified.