22 results on '"Sul, Seung-Ki"'
Search Results
2. High-Fidelity Induction Motor Simulation Model Based on Finite Element Analysis.
- Author
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Lee, Joon-Hee, Kwon, Yong-Cheol, and Sul, Seung-Ki
- Subjects
FINITE element method ,INDUCTION machinery ,SIMULATION methods & models ,INDUCTION motors - Abstract
This article proposes a new high-fidelity simulation model of an induction motor (IM) based on finite-element analysis (FEA). The proposed model enables fast and accurate IM simulation with the inverter circuit model and control algorithm. That is, the proposed model can represent non-ideal features of IM, such as magnetic saturation, spatial harmonics, skew, and saturation-induced saliency in high accuracy. To construct the proposed model, a dq equivalent circuit of the squirrel cage rotor is introduced. Based on this, the static FEA is conducted which can accelerate the model construction compared to the conventional time-stepping FEA technique. Then, a flux-based IM model is established, which has advantages on speed, accuracy, and memory size in the simulation. To verify the effectiveness of the proposed model, the models are constructed for two commercial IMs used for the industrial drive. IM control algorithms are tested in various operating conditions on the proposed model. The results are compared with the time-stepping FEA and the experiment for the verification of the proposed model. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. MTPA Tracking Control of Sensorless IPMSM Based on Square-Wave Voltage Signal Injection.
- Author
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Yoo, Jiwon, Kim, Hyeon-Sik, and Sul, Seung-Ki
- Subjects
SQUARE waves ,SYNCHRONOUS electric motors ,VOLTAGE ,POSITION sensors ,ELECTROSTATIC induction ,SENSOR placement ,ELECTRIC inductance ,TORQUE control - Abstract
This article proposes an online maximum torque-per-Ampere (MTPA) control of an interior permanent-magnet synchronous motor (IPMSM) based on the square-wave voltage signal injection. Because the proposed method does not rely on a position sensor, it is applicable to sensorless IPMSMs. The proposed algorithm consists of a dynamic inductance estimator, frequency-adaptive flux observer, and an MTPA tracking controller. The proposed inductance estimation utilizes the pulsating square-wave voltage injection, which can maximize the injection frequency, and the dynamic performance can be preserved during the signal injection. Through the online flux and inductance estimation, the magnetic saturation of the IPMSM and the temperature variation can be fully considered in the MTPA control. The conventional rotor position estimator is replaced with the MTPA tracking controller, which does not rely on offline commissioning parameters. The proposed algorithm can operate under both the torque control and speed control mode, and accurate torque control on MTPA curve can be achieved. The simulation and experimental results demonstrate that the proposed method accurately tracks the MTPA point up to 200% of the rated torque in the mid- and high-speed region. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Dynamic Overmodulation Scheme for Improved Current Regulation in PMSM Drives.
- Author
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Yoo, Jiwon and Sul, Seung-Ki
- Subjects
- *
PERMANENT magnet motors - Abstract
The overmodulation scheme plays an essential role in the dynamic performance of the current regulation under voltage limitation. This article analyses how the nonlinearity of the voltage hexagon affects dynamic overmodulation. Most dynamic overmodulation schemes had considered the voltage hexagon as the limit of the output voltage to maximize the voltage utilization. However, these schemes do not show uniform dynamic performance according to the rotor position on the voltage hexagon. To overcome this limitation, this article proposes an overmodulation scheme that is robust against the rotor position variation. The computer simulation and experimental results verify that the proposed method has the consistent performance regardless of the rotor position with less d-axis current overshoot keeping the fast dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
5. Torque Ripple-Minimizing Control of IPMSM With Optimized Current Trajectory.
- Author
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Cho, Hyung-June, Kwon, Yong-Cheol, and Sul, Seung-Ki
- Subjects
TORQUE control ,TORQUE ,MAGNETIC hysteresis ,PERMANENT magnets - Abstract
In an interior permanent-magnet synchronous machine (IPMSM) for higher torque density, there would be undesirable torque ripples due to spatial harmonics. This article analyzes the torque ripple based on the actual torque map, which is more practical and accurate than the torque model-based analyses. Based on the analysis, a torque ripple-minimizing scheme is proposed for practical IPMSMs. In addition, an experimental identification method of torque map is proposed. The identified torque map is used not only for the proposed torque ripple-minimizing method, but also for the torque reconstruction in experiments. Simulation and experimental results are provided to verify the proposed method. It is confirmed that the harmonic torque ripple under target has been reduced by over 90%. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Time-Optimal Voltage Vector Transition Scheme for Six-Step Operation of PMSM.
- Author
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Cho, Hyung-June, Kwon, Yong-Cheol, and Sul, Seung-Ki
- Subjects
VOLTAGE ,DEGREES of freedom ,VOLTAGE control ,HARMONIC analysis (Mathematics) ,FLUX (Energy) - Abstract
This article analyzes the instantaneous flux trajectory of a permanent-magnet synchronous machine (PMSM) in the six-step operation. Not only the flux dynamics but also the instantaneous voltage vector are included in the analysis. Based on the analysis, a time-optimal voltage vector transition scheme is proposed for the six-step operation of a PMSM. In the proposed scheme, a few steps are added in the transition of the voltage vectors to bring additional degrees of freedom, and they can enhance the dynamic performance conspicuously under the given current constraint. Simulation and experimental results are provided to verify the proposed scheme. For the stepwise torque command, the proposed scheme saves the settling time more than 50% with 60% reduction of the peak current compared to the conventional transition method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
7. Stator Resistance Estimation Using DC Injection With Reduced Torque Ripple in Induction Motor Sensorless Drives.
- Author
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Yoo, Jiwon, Lee, Joohyun, Sul, Seung-Ki, and Baloch, Noor Aamir
- Subjects
INDUCTION motors ,STATORS ,TORQUE ,TORQUE control - Abstract
In this article, the torque ripple of an induction motor due to dc injection for the stator resistance estimation is analyzed. In the analysis, the fundamental component of rotor flux is used for rotor flux orientation to avoid the perturbation issue in synchronous reference speed. On the synchronous reference frame, flux and torque fluctuation due to injected dc and arbitrary second harmonic current is calculated. Furthermore, the current reference that nullifies the fundamental frequency torque ripple in the whole operating condition is proposed. An integral-based average filter is applied to extract dc signals in phase voltage and current. Simulations and experiments are carried out to verify the performance of the proposed methods. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. Online MTPA Control of IPMSM Based on Robust Numerical Optimization Technique.
- Author
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Kim, Hyeon-Sik, Lee, Younggi, Sul, Seung-Ki, Yu, Jayeong, and Oh, Jaeyoon
- Subjects
ROBUST optimization ,MATHEMATICAL optimization ,LAGRANGE multiplier ,CONSTRAINED optimization ,SIMULTANEOUS equations ,TORQUE control - Abstract
This paper presents an online maximum torque per ampere (MTPA) control that considers both magnetic saturation and cross-magnetization effects of interior permanent-magnet synchronous machines (IPMSMs). For IPMSM drives, especially in torque-controlled applications, torque accuracy and high-efficiency operations are important issues. They can be dealt as a constrained optimization problem to satisfy both torque reference tracking and loss-minimizing operation. In this paper, nonlinear simultaneous equations are derived from Lagrange multiplier method, which could be solved by numerical algorithms. Among them, Levenberg–Marquardt algorithm (LMA) is employed to guarantee a robust calculation of optimal current references. It is optimized to alleviate calculation burden while maintaining the stability of the proposed algorithm. In addition, a torque reference limiter is implemented to satisfy a current limit in real time. The feasibility of the proposed method is verified under various operating conditions by simulation and experimental results. Through the proposed algorithms, accurate MTPA control is achieved under not only unsaturated but also highly saturated operating conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
9. Minimum Torque Ripple Pulse Width Modulation With Reduced Switching Frequency for Medium-Voltage Motor Drive.
- Author
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Jung, Hyun-Sam, Hwang, Chae-Eun, Kim, Hyeon-Sik, Sul, Seung-Ki, Hee-Won, An, and Yoo, Hyunjae
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MOTOR drives (Electric motors) ,TORQUE ,ELECTRIC inverters ,SIMULATION methods & models ,FANS (Machinery) ,PERMANENT magnet motors ,INDUCTION machinery - Abstract
In this paper, the characteristics of ripple current of a multimegawatt drive system fed by a pulse-width modulation (PWM) inverter are investigated. Based on the investigation, a novel PWM scheme is devised to reduce the switching loss of the inverter under an identical amount of torque ripple of a motor. The proposed PWM is composed of two parts. The first is minimum torque ripple PWM (MTRPWM), which is optimized in terms of the minimum torque ripple in high modulation index (MI). The second determines the minimum switching frequency while holding the average torque ripple less than the allowable value under various operating conditions. It is termed reduced switching frequency PWM (RSFPWM). Consequently, by simply changing the PWM method from conventional fixed switching frequency continuous PWM to the proposed PWM, MTRPWM and RSFPWM, simulation results show that the switching loss of the inverter driving a 3.5 MW induction motor is reduced to 51.6% while keeping the torque ripple in the allowable boundary, where MI is 1.12. This approach is applied to small-scale experimental sets consisting of an interior permanent magnet synchronous machine (IPMSM) motor-generator set, and an induction machine MG set in an effort to verify the validity and feasibility of the proposed method. Based on these experimental results, the cost indexes of the IPMSM and the induction machine, as defined in this paper, decrease by up to 66% and 77%, respectively, when the proposed method is applied when MI is 1.12 compared with the outcome with the conventional PWM. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
10. Model-Based Sensorless Control of an IPMSM With Enhanced Robustness Against Load Disturbances Based on Position and Speed Estimator Using a Speed Error.
- Author
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Lee, Younggi and Sul, Seung-Ki
- Subjects
- *
DETECTORS , *ROBUST control , *ELECTRICAL load , *ELECTRIC potential , *ERRORS - Abstract
In this paper, new model-based sensorless control methods are proposed that include independent estimations of position and speed errors, and compatible position and speed estimators. Using the proposed position estimator, a unity transfer function can be achieved from the actual position to the estimated position, eliminating the effects of load disturbances. This implies that the position error would ideally be zero, even in a transient state. In addition, the effects of parameter and voltage synthesis errors on the steady-state position error are analyzed. Experimental results verify both the analysis and the effectiveness of the proposed methods under severe load disturbances such as speed transient (20 000 r/min/s) and load torque transient (10 p.u./s). With the proposed methods, position estimation errors are significantly reduced by more than 50% during speed and load torque transients at identical dominant-pole placements, verifying the enhanced tracking capability and robustness of the proposed methods against external load disturbances. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
11. Six-step operation of PMSM with instantaneous current control.
- Author
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Kwon, Yong-Cheol, Kim, Sungmin, and Sul, Seung-Ki
- Abstract
Six-step operation has many advantages on PMSM drives. Because the fundamental of inverter output is maximized by the six-step operation, capability of machine can be a lot enhanced. Furthermore, switching loss of inverter can be minimized by the six-step operation. Despite many merits of the six-step operation in AC machine drives, it was rarely adopted in dynamic applications because performance of current control is severely degraded during the six-step operation. In this paper, a control scheme for the six-step operation of PMSMs is proposed. Applying the proposed method, the six-step operation is successfully realized without losing control dynamics. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
12. Control of three phase inverter for AC motor drive with small DC-link capacitor fed by single phase AC source.
- Author
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Jung, Hyun-Sam, Chee, Seung-Jun, Sul, Seung-Ki, Park, Young-Jae, Park, Hyun-Soo, and Kim, Woo-Kyu
- Abstract
If a small DC-link capacitor is used in the DC-link fed by single phase AC source, the DC-link voltage fluctuates severely with twice of the source frequency. To handle this fluctuation, the concept of ‘average voltage constraint’ is proposed in this study. On the basis of the concept, a flux weakening scheme generating d-axis current reference (idsr*) for Interior Permanent Magnet Synchronous Machine (IPMSM) is devised. And, q-axis current reference (iqsr*) is modified for the unity power factor operation to AC source. The proposed scheme has been applied to inverter driven 1 kW compressor of an air-conditioner. From the experimental results, it has been verified that the compressor operates well at required operating condition regardless of the severe fluctuation of DC-link voltage due to the reduced DC-link capacitor. Also the frequency spectrum of the AC source current reveals that the harmonics of the source current meet IEC 61000-3-2 Class A and that the overall power factor is above 97% without any additional circuit such as an input filter and the power factor correction circuit. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
13. Six-Step Operation of PMSM With Instantaneous Current Control.
- Author
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Kwon, Yong-Cheol, Kim, Sungmin, and Sul, Seung-Ki
- Subjects
ELECTRIC currents ,ELECTRIC machinery ,ELECTRIC motors ,ELECTROMECHANICAL devices ,ELECTRIC power - Abstract
Six-step operation has many advantages in permanent-magnet synchronous machine (PMSM) drives such as maximum power utilization and widened flux-weakening region. However, due to the maximum utilization of inverter output, saturation of current regulator makes it difficult to maintain instantaneous current control capability. Accordingly, in most of conventional research studies, the six-step operation has been implemented by voltage angle control without current regulation, whose dynamic performance is quite unsatisfactory. This paper proposes a control scheme for the six-step operation of PMSM with enhanced dynamic performance of current control. By collaborative operation of dynamic overmodulation, flux weakening, and a technique for enhanced dynamic performance, the six-step operation is realized without losing instantaneous current control capability. Simulations and experiments are carried out to verify the effectiveness of the proposed control scheme. The experimental results show 17% extension of the constant torque region and 27% enhancement of torque capability at three times of the base speed. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
14. Control of Three-Phase Inverter for AC Motor Drive With Small DC-Link Capacitor Fed by Single-Phase AC Source.
- Author
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Jung, Hyun-Sam, Chee, Seung-Jun, Sul, Seung-Ki, Park, Young-Jae, Park, Hyun-Soo, and Kim, Woo-Kyu
- Subjects
POWER factor measurement ,COMPRESSORS ,ELECTRICAL harmonics ,ELECTRIC power factor ,VOLTAGE control - Abstract
If a small dc-link capacitor is used in the dc link fed by a single-phase ac source, then the dc-link voltage severely fluctuates at twice of the source frequency. To handle this fluctuation, the concept of “average voltage constraint” is proposed in this study. On the basis of this concept, a flux-weakening scheme, generating the d-axis current reference (ids^{r}^{\ast}) for the interior permanent-magnet synchronous machine, is devised. The q-axis current reference (iqs^{r}^{\ast}) is modified for the unity power factor operation in the viewpoint of an ac source without an additional sensor. The proposed scheme has been applied to the inverter-driven 1-kW compressor of an air conditioner. From the experimental results, it has been verified that the compressor operates well at the required operating condition, regardless of the severe fluctuation of dc-link voltage, because of the reduced dc-link capacitance. The frequency spectrum of the ac source current reveals that the harmonics of the source current meet the regulation of IEC 61000-3-2 Class A and that the overall power factor is above 96% without any additional circuit, such as an input filter and a power factor correction circuit. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
15. A Nine-Phase Permanent-Magnet Motor Drive System for an Ultrahigh-Speed Elevator.
- Author
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Jung, Eunsoo, Yoo, Hyunjae, Sul, Seung-Ki, Choi, Hong-Soon, and Choi, Yun-Young
- Subjects
ELEVATORS ,PERMANENT magnet motors ,SYNCHRONOUS electric motors ,ELECTRIC inverters ,MATHEMATICAL models ,CONTROL theory (Engineering) ,ELECTRIC fault location - Abstract
This paper presents a nine-phase permanent-magnet synchronous motor (PMSM) drive system based on multiple three-phase voltage source inverters. The nine-phase PMSM was developed as a traction motor for an ultrahigh-speed elevator. The mathematical model of the motor was simplified through symmetry of the system. Using the simplified model, the drive system can be controlled by the well-known d-q control theory. The feasibility and validity of the drive system were experimentally demonstrated at the world's tallest elevator test tower. Moreover, an additional experiment was performed to ensure the fault-tolerance capability of the system. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
16. Voltage Feedback Current Control Scheme for Improved Transient Performance of Permanent Magnet Synchronous Machine Drives.
- Author
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Kwon, Yong-Cheol, Kim, Sungmin, and Sul, Seung-Ki
- Subjects
TRANSIENT responses (Electric circuits) ,ELECTRIC flux ,DIRECT currents ,PID controllers ,OPTIMAL control theory ,DIGITAL signal processing - Abstract
This paper proposes a novel control scheme for the fast current control of permanent magnet synchronous machines. The proposed method mainly works in the transient state of current control without deteriorating steady-state characteristics. The proposed method is applicable in a wide range of speed: in the speed below the base speed and in the flux weakening region. Using the proposed method, the reference values of d-q currents are modified so that the currents follow the so-called “shortcut” trajectory in the d-q coordinate plane. The effectiveness of the proposed method is confirmed by computer simulations and experiments. The settling time is reduced by 55% compared with that of the conventional method. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
17. Flux-Weakening Strategy of an Induction Machine Driven by an Electrolytic-Capacitor-Less Inverter.
- Author
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Yoo, Anno, Sul, Seung-Ki, Kim, Hyeseung, and Kim, Kyung-Seo
- Subjects
- *
ELECTRIC inverters , *INDUCTION motors , *ELECTROLYTIC capacitors , *FLUCTUATIONS (Physics) , *STABILITY (Mechanics) , *TORQUE , *ELECTRIC current rectifiers - Abstract
This paper presents a novel flux-weakening strategy for an induction machine driven by an electrolytic-capacitor-less inverter. In the electrolytic-capacitor-less inverter, the dc-link voltage is fluctuating at six times the frequency of the input three-phase source due to its small dc-link capacitance. Hence, the decoupling of the fluctuation and maximum utilization of the dc-link voltage is a major issue in the electrolytic-capacitor-less inverter. In this paper, the cost function is set to increase the voltage utilization of the inverter for the flux-weakening operation of an induction machine. With the proposed flux-weakening strategy, the operating speed of the induction machine is extended above the base speed without any stability problems. The experimental results show the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
18. Novel Flux-Weakening Control of an IPMSM for Quasi-Six-Step Operation.
- Author
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Kwon, Tae-Suk, Choi, Gi-Young, Kwak, Mu-Shin, and Sul, Seung-Ki
- Subjects
MAGNETIC flux compression ,FLUX pinning ,TORQUE ,COMPRESSOR blades ,HYBRID electric vehicles ,ELECTRIC currents ,ELECTRIC potential ,FOURIER transform spectroscopy - Abstract
This paper proposes a novel flux-weakening control algorithm of an interior permanent-magnet synchronous motor for "quasi" six-step operation. The proposed method is composed of feedforward and feedback paths. The feedforward path consists of 1-D lookup table, and the feedback is based on the difference between the reference voltage updated by current regulator and the output voltage limited by the overmodulation. Using this method, the flux-weakening and the antiwindup controls can be achieved simultaneously. In addition, the quasi-six-step operation can be obtained. That is, the available maximum output torque in the flux-weakening region is close to that in the six-step operation while the ability of the current control is maintained. The effectiveness of this method is proved by the experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
19. New Direct Torque Control of Induction Motor for Minimum Torque Ripple and Constant Switching...
- Author
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Kang, Jun-Koo and Sul, Seung-Ki
- Subjects
- *
INDUCTION machinery , *TORQUE - Abstract
Proposes a direct torque control (DTC) method of an induction machine that enables the minimum torque ripple control while maintaining constant switching frequency. Configuration of the proposed DTC; Torque control and flux control performance of the proposed DTC; How the proposed strategy improves the performance of the DTC.
- Published
- 1999
- Full Text
- View/download PDF
20. Highly dynamic torque control of synchronous relunctance motor.
- Author
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Kang, Seog-Joo and Sul, Seung-Ki
- Subjects
- *
TORQUE , *SYNCHRONOUS electric motors - Abstract
Presents a direct torque controller of a synchronous reluctance motor (SynRM) based on the stator current vector. What is torque control; Methodology used to develop the torque controller; Validation of the performance of the controller.
- Published
- 1998
- Full Text
- View/download PDF
21. Analysis and compensation of current measurement error...
- Author
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Chung, Dae-Woong and Sul, Seung-Ki
- Subjects
- *
TORQUE , *ALTERNATING current machinery , *MEASUREMENT - Abstract
Proposes a compensation method in order to obtain precise torque control and eliminate speed ripples in a vector-controlled alternating current motor drives. Analysis of current measurement error; Compensation of current measurement error; Simulation and experimental results; Conclusions.
- Published
- 1998
- Full Text
- View/download PDF
22. Overmodulation strategy for high-performance torque control.
- Author
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Seok, Jul-Ki, Kim, Joohn-Sheok, and Sul, Seung-Ki
- Subjects
TORQUE ,PERMANENT magnets - Abstract
Presents information on an overmodualation technique for interior permanent magnet synchronous machine (IPMSM), with focus on the concept of torque control. Implementation of the technique to a inverter system; Characterization of the operation of the electrical drive system with a current controller; Difference between the machine terminal voltage and the machine-back electromotive force (EMF); Effects of current regulation performance on torque production.
- Published
- 1998
- Full Text
- View/download PDF
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