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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Power Electronics
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Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 9, Issue 6 - Nov 2009
Volume 9, Issue 5 - Sep 2009
Volume 9, Issue 4 - Jun 2009
Volume 9, Issue 3 - May 2009
Volume 9, Issue 2 - Mar 2009
Volume 9, Issue 1 - Jan 2009
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Combined Dithered Sigma-Delta Modulation based Random PWM Switching Scheme
Kim, Seo-Hyeong ; Choi, Woo-Jin ; Choi, Se-Wan ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 667~678
The PWM (Pulse Width Modulation) control signals have a drawback in that their power spectrum tends to be concentrated around the switching frequency and the resulting harmonic spikes cause an EMI (Electromagnetic Interference) and switching losses in semiconductors, etc. The SDM (Sigma-Delta Modulation) is a type of switching modulation used to reduce these harmonic spikes, and several SDM schemes are investigated in this paper. In the DSDM (Dithered SDM), the SDSDM (Space-Dithered SDM) and TDSDM (Time-Dithered SDM), the signals are classified by the location of their random dither additions. In these schemes, the switching frequency is spread by a random dither generator placed on the input or the output parts. Experimental results are presented where the advantages of the new proposed CDSDM (Combined Dithered SDM) are confirmed by applying to a buck converter.
Torque Ripple Minimization for Induction Motor Driven by a Photovoltaic Inverter
Atia, Yousry ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 679~690
The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.
Series Active Power Filters to Compensate Harmonics and Reactive Power with the Direct Compensating Voltage Extraction Method in Three-Phase Four-Wire Systems
Kim, Jin-Sun ; Kim, Young-Seok ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 691~699
This paper presents the analysis of series active power filter for reactive power compensation, load balancing, harmonic elimination, and neutral current eradication in three-phase four-wire power systems. Generally, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3rd harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts directly influence its compensation characteristics. Hence, the advantage of this control algorithm is the direct extraction of compensation voltage reference without phase transformations and multiplying harmonic current value by gain and the required rating of the series active filter is much smaller than that of a conventional shunt active power filter. In order to show the effectiveness of the proposed control algorithm, experiments have been carried out.
Modeling and Parameter Identification of Coal Mill
Shin, Hwi-Beom ; Li, Xin-Lan ; Jeong, In-Young ; Park, Jong-Man ; Lee, Soon-Young ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 700~707
The coal mill used in the coal-fired power plants is modeled in view of the controller design rather than the educational simulator. The coal mass flow and the outlet temperature are modeled by reinvestigating the mass balance and heat balance models physically. The archived data from a plant database are utilized to identify the model parameters. It can be seen that the simulated model outputs are well matched with the measured ones. It is also expected that the proposed model is useful for the controller design.
A New Zero Voltage Transition Bridgeless PFC with Reduced Conduction Losses
Mahdavi, Mohammad ; Farzanehfard, Hosein ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 708~717
In this paper a new zero voltage transition PWM bridgeless PFC is introduced. The auxiliary circuit provides soft switching condition for all semiconductor devices. Also, in the resonant path of the auxiliary circuit, only two semiconductor devices exist. Therefore the resonant conduction losses are low. Furthermore, the auxiliary circuit semiconductor elements consist of only one diode and one switch. The proposed auxiliary circuit is applied to a bridgeless PFC converter to further reduce conduction and switching losses. In this paper, the operating modes of this converter are explained and the resulting ideal and simulation waveforms are shown. The presented experimental results justify the theoretical analysis.
A New Control Method for a Single-Phase Hybrid Active Power Filter based on a Rotating Reference Frame
Kim, Jin-Sun ; Kim, Young-Seok ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 718~725
To get instantaneous reference data in a single power system with vector space phasors, the instantaneous load current is adopted as a phase and another new signal, which is delayed through filtering by the phase-delay property of a low-pass filter, is used as the secondary phase. Because the two-phases have a different phase, the instantaneous value of the harmonic current can be obtained without a time-delay in calculation. The reference voltage is created by multiplying the coefficient k by the compensation current using the rotating reference frame synchronized with the source-frequency. To verify the validity of the proposed control method, experiments are carried out on a prototype of the single-phase hybrid active power filter system.
Bidirectional High-Frequency Link Inverter with Deadbeat Control
Salam, Zainal ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 726~735
This paper presents a Bidirectional High-Frequency Link (BHFL) inverter that utilizes the Deadbeat controller. The main features of this topology are the reduced size of the inverter and fewer power switches. On the secondary side of the transformer, the active rectifier employs only two power switches, thus reducing switching losses. Using this configuration, the inverter is capable of carrying a bidirectional power flow. The inverter is controlled by a Deadbeat controller, which consists of the inner current loop, outer voltage loop and a feedforward controller. Additional disturbance decoupling networks are employed to improve the system's robustness towards load variations. A 1-kVA prototype inverter has been constructed and the Deadbeat control algorithm is experimentally verified. The experimental results show that the inverter has high efficiency (91%) with low steady state output voltage total harmonics distortion (1.5%).
Single-Phase Z-Source AC/AC Converter with Wide Range Output Voltage Operation
Nguyen, Minh-Khai ; Jung, Young-Gook ; Lim, Young-Cheol ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 736~747
A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.
Compensation of Position Error due to Amplitude Imbalance in Resolver Signals
Hwang, Seon-Hwan ; Kwon, Young-Hwa ; Kim, Jang-Mok ; Oh, Jin-Seok ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 748~756
This paper presents a compensation algorithm for position error due to an amplitude imbalance between resolver output signals. Resolvers are typically used to obtain absolute position information for motor drive systems in severe environments. Position error is caused by an amplitude imbalance of the resolver output signals. As a result, the d- and q-axis currents of synchronous reference frame have periodic ripples in the stator fundamental frequency in permanent magnet synchronous motor (PMSM) drive systems. Therefore, this paper proposes a compensation algorithm to reduce the position error generated by the amplitude imbalance. The proposed method does not require any additional hardware, and reduces computation time with a simple integral operation according to rotor position. In addition, the position error can be directly compensated for by the estimated position error. The effectiveness of the proposed compensation algorithm is verified through several simulations and experiments.
Small-Signal Modeling and Control of Three-Phase Bridge Boost Rectifiers under Non-Sinusoidal Conditions
Chang, Yuan ; Jinjun, Liu ; Xiaoyu, Wang ; Zhaoan, Wang ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 757~771
This paper proposes a systematic approach to the modeling of the small-signal characteristics of three-phase bridge boost rectifiers under non-sinusoidal conditions. The main obstacle to the conventional synchronous d-q frame modeling approach is that it is unable to identify a steady-state under non-sinusoidal conditions. However, for most applications under non-sinusoidal conditions, the current loops of boost rectifiers are designed to have a bandwidth that is much higher than typical harmonics frequencies in order to achieve good current control for these harmonic components. Therefore a quasi-static method is applied to the proposed modeling approach. The converter small-signal characteristics developed from conventional synchronous frame modeling under different operating points are investigated and a worst case point is then located for the current loop design. Both qualitative and quantitative analyses are presented. It is observed that operating points influence the converter low frequency characteristics but hardly affect the dominant poles. The relationship between power stage parameters, system poles and zeroes is also presented which offers good support for the system design. Both the simulation and experimental results verified the analysis and proposed modeling approach. Finally, the practical case of a parallel active power filter is studied to present the modeling approach and the resultant regulator design procedure. The system performance further verifies the whole analysis.
A Novel Soft-Switching Two-Switch Flyback Converter with a Wide Operating Range and Regenerative Clamping
Kim, Marn-Go ; Jung, Young-Seok ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 772~780
A novel soft-switching two-switch flyback converter is proposed in this paper. This converter is composed of two active power switches, a flyback transformer, a blocking diode, and two passive regenerative clamping circuits. The proposed converter has the advantages of a low cost circuit configuration, a simple control scheme, a high efficiency, and a wide operating range. The circuit topology, analysis, design considerations, and experimental results of the new flyback converter are presented.
Direct Power Control of a DFIG in Wind Turbines to Improve Dynamic Responses
Jou, Sung-Tak ; Lee, Sol-Bin ; Park, Yong-Bae ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 781~790
This paper presents an implementation of a direct active and reactive power control for a doubly fed induction generator (DFIG), which is applied to a wind generation system as an alternative to the classical field-oriented control (FOC). The FOC has a complex control structure that consists of a current controller, a power controller and frame transformations. The performance of the FOC depends highly on parameter variations of the rotor and stator resistances and the inductances. The proposed direct power control (DPC) method produces a fast and robust power response without the need of complex structure and algorithms. One drawback, however, is its high power ripple during a steady state. In this paper, active and reactive power controllers and space-vector modulation (SVM) are combined to replace hysteresis controllers used in the original DPC drive, resulting in a fixed switching frequency of the power converter. Simulation results with the FOC and DPC for a 3kW DFIG are given and discussed, and the experimental results of a test involving identical machines are presented to illustrate the feasibility of the proposed control strategy.
Robust Disturbance Compensation for Servo Drives Fed by a Matrix Converter
Park, Ki-Woo ; Chwa, Dong-Kyoung ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 791~799
This paper presents a time-varying sinusoidal disturbance compensation method (based on an adaptive estimation scheme) for induction motor drives fed by a matrix converter. In previous disturbance accommodation methods, sinusoidal disturbances with unknown time-invariant frequencies have been considered. However, in the new method proposed here, disturbances with unknown time-varying frequencies are considered. The disturbances can be estimated by using a disturbance accommodating observer, and an additional control input is added to the induction machine drive. The stability analysis is carried out considering the disturbance estimation error and simulation results are shown to illustrate the performance of the proposed solution.
Pressure Control of SR Driven Hydraulic Oil-Pump Using Data based PID Controller
Lee, Dong-Hee ; Kim, Tae-Hyoung ; Ahn, Jin-Woo ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 800~808
This paper presents a practical method of pressure control for a hydraulic oil-pump system using an SR (Switched Reluctance) drive. For a 6Mpa grade hydraulic oil-pump, a 2.6kW SR drive is developed. In order to get high performance pressure dynamics in actual applications, a data based PID control scheme is proposed. The look-up table from a pre-measured data base produces an approximate current reference based on motor speed and oil-pressure. A PID controller can compensate for the pressure error. With the combination of the two references, the proposed control scheme can achieve fast dynamics and stable operation. Furthermore, a suitable current controller considering the nonlinear characteristics of an SRM (Switched Reluctance Motor) and practical test methods for data measuring are presented. The proposed control scheme is verified by experimental tests.
A Novel Soft-Switching Full-Bridge PWM Converter with an Energy Recovery Circuit
Lee, Dong-Young ; Cho, Bo-Hyung ; Park, Joung-Hu ;
Journal of Power Electronics, volume 9, issue 5, 2009, Pages 809~821
This paper proposes a new phase-shift full-bridge DC-DC converter by applying energy recovery circuits to a conventional full-bridge DC-DC converter in plasma display panel applications. The converter can achieve soft-switching in main-switches by an extra auxiliary resonant network even with the wide operating condition of both output load and input voltage. The un-coupled design guidelines to the main bridge-leg component parameters for soft-switching operation contribute to conduction loss reduction in the transformer primary side leading to efficiency improvement. The auxiliary switches in the resonant network also operate in zero-current switching. This paper analyzes the operation modes of the proposed scheme and presents the key design guidelines through steady state analysis. Also, the paper verifies the validity of the circuits by hardware experiments with a 1kW DC/DC converter prototype.