• Title/Summary/Keyword: Cascaded inverter

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Wind Power Grid Integration of an IPMSG using a Diode Rectifier and a Simple MPPT Control for Grid-Side Inverters

  • Ahmed, Tarek;Nishida, Katsumi;Nakaoka, Mutsuo
    • Journal of Power Electronics
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    • v.10 no.5
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    • pp.548-554
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    • 2010
  • In this paper, a 1.5 kW Interior Permanent Magnet Synchronous Generator (IPMSG) with a power conditioner for the grid integration of a variable-speed wind turbine is developed. The power-conditioning system consists of a series-type 12-pulse diode rectifier powered by a phase shifting transformer and then cascaded to a PWM voltage source inverter. The PWM inverter is utilized to supply sinusoidal currents to the utility line by controlling the active and reactive current components in the q-d rotating reference frame. While the q-axis active current of the PWM inverter is regulated to follow an optimized active current reference so as to track the maximum power of the wind turbine. The d-axis reactive current can be adjusted to control the reactive power and voltage. In order to track the maximum power of the wind turbine, the optimal active current reference is determined by using a simple MPPT algorithm which requires only three sensors. Moreover, the phase angle of the utility voltage is detected using a simple electronic circuit consisting of both a zero-crossing voltage detecting circuit and a counter circuit employed with a crystal oscillator. At the generator terminals, a passive filter is designed not only to decrease the harmonic voltages and currents observed at the terminals of the IPMSG but also to improve the generator efficiency. The laboratory results indicate that the losses in the IPMSG can be effectively reduced by setting a passive filter at the generator terminals.

A New Photovoltaic System Architecture of Module-Integrated Converter with a Single-sourced Asymmetric Multilevel Inverter Using a Cost-effective Single-ended Pre-regulator

  • Manoharan, Mohana Sundar;Ahmed, Ashraf;Park, Joung-Hu
    • Journal of Power Electronics
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    • v.17 no.1
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    • pp.222-231
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    • 2017
  • In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a single-ended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.

A Study on the Off-Grid Photovoltaic Generation System with Sequential Voltage System (순차전압시스템을 고려한 독립형 태양광 발전 시스템에 관한 연구)

  • Kim, Gu-Yong;Bae, Jun-Hyung;Kim, Jong-Hae
    • Journal of IKEEE
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    • v.24 no.1
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    • pp.364-367
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    • 2020
  • This paper presents the off-grid PV-ESS system of sequential voltage control method applied to OR logic gate. The conventional off-grid PV-ESS system with the low-voltage series connection has problems due to capacity expansion. To solve these problems, this paper proposes a noble PV-ESS system with high efficiency and low cost by applying sequential voltage control technique of the high-voltage series connection of analog circuit type. The input voltage of DC to AC inverter can be converted from the low-voltage by the combinations of series connection of the conventional cascaded 24V solar cell unit modules to the high-voltage of 384V in battery. The output voltage of the battery was 384V as the each input voltage of three phase DC to AC inverter, and the each output voltage of three phase 10kW DC to AC inverter is designed to be AC380V@60Hz as the line to line rms voltage value. To prove the validity of the theoretical analysis by PSIM simulation, the operating characteristics of sequential voltage control system with OR logic gate were confirmed through experiment results.

Control Method for Performance Improvement of BLDC Motor used for Propulsion of Electric Propulsion Ship (전기추진선박의 추진용으로 사용되는 브러시리스 직류전동기의 제 어방법에 따른 성능향상에 관한 연구)

  • Jeon, Hyeonmin;Hur, Jaejung;Yoon, Kyoungkuk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.802-808
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    • 2019
  • DC motors are used extensively on shipboard, including as the ship's winch operating motor, owing to their simple speed control and excellent output torque characteristics. Moreover, they were used as propulsion motors in the early days of electric propulsion ships. However, mechanical rectifiers, such as brushes, used in DC motors have certain disadvantages. Hence, brushless DC (BLDC) motors are increasingly being used instead. While the electrical characteristics of both types of motors are similar, BLDC motors employ electronic rectifying devices, which use semiconductor elements, instead of mechanical rectifying devices. The inverter system for driving conventional BLDC motors uses a two-phase excitation method so that the waveform of the back electromotive force becomes trapezoidal. This causes harmonics and torque ripple in the phase current switching period in which the winding wire through which the current flows is changed. Researchers have studied and presented various methods to reduce the harmonics and torque ripple. This study applies a cascaded H-bridge multilevel inverter, which implements a proportional-integral speed current controller algorithm in the driving circuit of the BLDC motor for electric propulsion ships using a power analysis program. The simulation results of the modeled BLDC motor show that the driving method of the proposed BLDC motor improves the voltage waveform of the input side of the motor and remarkably reduces the harmonics and torque ripple compared with the conventional driving method.

Identification of Open-Switch and Short-Switch Failure of Multilevel Inverters through DWT and ANN Approach using LabVIEW

  • Parimalasundar, E.;Vanitha, N. Suthanthira
    • Journal of Electrical Engineering and Technology
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    • v.10 no.6
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    • pp.2277-2287
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    • 2015
  • In recent times, multilevel inverters are given high priority in many large industrial drive applications. However, the reliability of multilevel inverters are mainly affected by the failure of power electronic switches. In this paper, open-switch and short-switch failure of multilevel inverters and its identification using a high performance diagnostic system is discussed. Experimental and simulation studies were carried out on five level cascaded H-Bridge multilevel inverter and its output voltage waveforms were analyzed at different switch fault cases and at different modulation index values. Salient frequency domain features of the output voltage signal were extracted using the discrete wavelet transform multi resolution signal decomposition technique. Real time application of the proposed fault diagnostic system was implemented through the LabVIEW software. Artificial neural network was trained offline using the Matlab software and the resultant network parameters were transferred to LabVIEW real time system. In the proposed system, it is possible to precisely identify the individual faulty switch (may be due to open-switch (or) short-switch failure) of multilevel inverters.

A Study on Luminescence and Discharge Characteristics of EEFL (External Electrode Fluorescent Lamp) Driven by Square Wave for Large sized-LCD panel (대형 액정디스플레이패널의 백라이트용 외부 전극 형광램프의 구형파 구동 방법에 대한 휘도, 방전 특성 연구)

  • Cho Dae-Youn;Lee Yeon-Jae;Cho Kyu-Min;Oh Won-Sik;Moon Gun-Woo;Lee Sang-Gil;Park Mun-Soo
    • Proceedings of the KIPE Conference
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    • 2006.06a
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    • pp.409-412
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    • 2006
  • EEFL can be driven by square wave driving method. A square wave is applied directly to both ends of EEFL by cascaded multi-stage full-bridge inverter. The various current shapes of lamp are achieved by various inductors between lamp and inverter. In this paper, it is newly investigated that the area of current directly influences the luminance. Furthermore, the 3-level square wave is considered to drive EEFL with self-discharge characteristics. The highest luminance efficiency is achieved by properly controlling the rate of self-discharge usage.

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A Hybrid Anti-islanding Detection Scheme for Utility Interactive Inverter with Enhanced Harmonic Extraction Capability (향상된 고조파 검출 능력을 갖는 계통연계 인버터의 하이브리드 단독운전 방지기법)

  • Kang, Sung-Wook;Kim, Kyeong-Hwa
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.4
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    • pp.312-319
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    • 2014
  • When distributed generation such as a wind power system is connected to the grid, it should meet grid requirements like IEEE Std. 1547, which regulates the anti-islanding method. Since the islanding may cause damage on electrical equipments or safety hazards for utility line worker, a distributed generation should detect it as soon as possible. This paper proposes a hybrid anti-islanding method coupled with the active and passive detection methods. To enhance the harmonic extraction capability for an active harmonic injection method, cascaded second-order band-pass filter and signal processing scheme are employed. Simulation and experiments are carried out under the islanding test condition specified in IEEE Std. 1547. Passive over/under voltage and over/under frequency methods are combined with the active method to improve the detection speed under certain condition. The simulation and experimental results are presented to verify that the proposed hybrid anti-islanding method can effectively detect the islanding.

Design and Application of a Photovoltaic Array Simulator with Partial Shading Capability

  • Beser, Ersoy
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1259-1269
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    • 2019
  • PV system performance is dependent on different irradiations and temperature values in addition to the capability of the employed PV inverter / maximum power point tracker (MPPT) circuit or algorithm. Therefore, it would be appropriate to use a PV simulator capable of producing identical repeatable conditions regardless of the weather to evaluate the performance of inverter / MPPT circuits and algorithms. In accordance with this purpose, a photovoltaic (PV) array simulator is presented in this paper. The simulator is designed to generate current-voltage (I-V) and power-voltage (P-V) curves of a PV panel. Series connected cascaded modules constitute the basic part of the simulator. This feature also allows for the modeling of PV arrays since the number of modules can be increased and high voltage values can be reached with the simulator. In addition, the curves obtained at the simulator output become similar to the actual curves of sample PV panels with an increase in the number of modules. In order to show the validity of the proposed simulator, it was simulated for various situations such as panels under full irradiance and partial shading conditions. After completing simulations, experiments were realized to support the simulation study. Both simulation and experimental results show that the proposed simulator will be very useful for researchers to carry out PV studies under laboratory conditions.

Development of 11,000V & 13,800V Medium Voltage Inverter using H-Bridge Multilevel (H-브릿지 멀티레벨을 적용한 11,000V & 13,800V 고압인버터 개발)

  • Park, Young-Min;Kim, Jong-Cheol;Cho, Sung-Joon
    • Proceedings of the KIPE Conference
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    • 2016.07a
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    • pp.415-416
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    • 2016
  • 본 논문은 입출력 전력품질이 우수하고 전압별 시리즈화가 용이한 Cascaded H-브릿지 멀티레벨 전력 회로를 적용한 고압 대용량 전동기 구동용 11,000V / 13,800V 고압인버터 개발에 관하여 기술하였다. 기존에 개발된 3,300V/200kVA - 6,600V/8,000kVA 고압인버터의 단상 인버터로 구성된 개별 파워 셀 전압 증대, 파워 셀의 직렬 갯수 추가, 입력 위상 전이 다권선 변압기 2차 권선수 확장, 그리고 분산 제어 기능을 확대하는 방식을 적용하여 전압을 증가시켰다. 실용량 제품의 제작 (11,000V/1,000kVA, 13,800V/2,400kVA) 및 실험을 통하여 개발된 11,000V/13,800V 고압인버터의 성능을 확인하였다.

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Verification of New Family for Cascade Multilevel Inverters with Reduction of Components

  • Banaei, M.R.;Salary, E.
    • Journal of Electrical Engineering and Technology
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    • v.6 no.2
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    • pp.245-254
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    • 2011
  • This paper presents a new group for multilevel converter that operates as symmetric and asymmetric state. The proposed multilevel converter generates DC voltage levels similar to other topologies with less number of semiconductor switches. It results in the reduction of the number of switches, losses, installation area, and converter cost. To verify the voltage injection capabilities of the proposed inverter, the proposed topology is used in dynamic voltage restorer (DVR) to restore load voltage. The operation and performance of the proposed multilevel converters are verified by simulation using SIMULINK/MATLAB and experimental results.