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Kyo-Beum Lee
Department of Electrical and Computer Engineering, Ajou University, Suwon, Korea

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Original article
Published: 08 July 2021 in Journal of Power Electronics
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This paper proposes a six-step operation strategy for direct self-control (DSC) method of interior permanent magnet synchronous motor (IPMSM) based on the torque angle. Conventional DSC methods for induction motors (IMs) have been studied for railway applications since these methods are suitable for controlling high-power traction drives and for extending voltage utilization through a six-step inverter operation. However, IPMSMs controlled via conventional DSC methods for IMs cannot be properly controlled through a six-step operation since the torque angle is not considered. In addition, synchronous frame rotation causes a phase error at high speeds owing to the time delay of digital controllers. This paper presents a torque angle compensation that improves the dynamic performance. The effectiveness of the proposed DSC method was verified through experimental results.

ACS Style

Byeol Han; June-Seok Lee; Yeongsu Bak; Kyo-Beum Lee. Six-step operation strategy for direct self-control method of interior permanent magnet synchronous motors based on torque angle. Journal of Power Electronics 2021, 21, 1352 -1364.

AMA Style

Byeol Han, June-Seok Lee, Yeongsu Bak, Kyo-Beum Lee. Six-step operation strategy for direct self-control method of interior permanent magnet synchronous motors based on torque angle. Journal of Power Electronics. 2021; 21 (9):1352-1364.

Chicago/Turabian Style

Byeol Han; June-Seok Lee; Yeongsu Bak; Kyo-Beum Lee. 2021. "Six-step operation strategy for direct self-control method of interior permanent magnet synchronous motors based on torque angle." Journal of Power Electronics 21, no. 9: 1352-1364.

Journal article
Published: 11 June 2021 in IEEE Transactions on Power Electronics
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The emerging switched-capacitor-based multilevel inverters (SC-MLIs) offer interesting merits such as self-balancing of capacitor voltages and boosting of voltage gain. While the switched-capacitors (SCs) in these topologies are charged in parallel with the dc source, severe current spikes issue is inevitable, rendering them impractical at high power. This paper proposes a novel switched-capacitor-based T-type inverter that mitigates the current spikes by enabling soft-charging for its integrated SCs, where both SC in the topological structure charges through a dedicated circuit comprises of an inductor and two switches. The proposed topology is capable of 5-level ac voltage generation and when compared to a classical T-type/ANPC inverter, it achieves higher dc-link voltage utilization since its maximum attainable voltage gain is doubled. Theoretical findings of the proposed topology are validated by both the simulation and experimental results.

ACS Style

Sze Sing Lee; Yam Siwakoti; Reza Barzegarkhoo; Kyo-Beum Lee. Switched-Capacitor-Based Five-Level T-Type Inverter (SC-5TI) With Soft-Charging and Enhanced DC-Link Voltage Utilization. IEEE Transactions on Power Electronics 2021, 36, 13958 -13967.

AMA Style

Sze Sing Lee, Yam Siwakoti, Reza Barzegarkhoo, Kyo-Beum Lee. Switched-Capacitor-Based Five-Level T-Type Inverter (SC-5TI) With Soft-Charging and Enhanced DC-Link Voltage Utilization. IEEE Transactions on Power Electronics. 2021; 36 (12):13958-13967.

Chicago/Turabian Style

Sze Sing Lee; Yam Siwakoti; Reza Barzegarkhoo; Kyo-Beum Lee. 2021. "Switched-Capacitor-Based Five-Level T-Type Inverter (SC-5TI) With Soft-Charging and Enhanced DC-Link Voltage Utilization." IEEE Transactions on Power Electronics 36, no. 12: 13958-13967.

Journal article
Published: 04 June 2021 in IEEE Transactions on Power Electronics
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Open- and short-circuit faults are the most severe issues that affect the stability and reliability of power conversion systems. The space vector modulation (SVM) technique is widely used to control power converters. However, conventional SVM is incapable of controlling the system effectively when such faults occur. Considering these, this paper proposes a modified SVM that is capable of tolerating the extreme cases of faults (including multi open/short-circuit faults) simultaneously. An innovative fault tolerance method is proposed to tolerate multi-faults in hybrid active neutral point converters (HANPCs). Furthermore, new voltage reference signals are created in addition to calculating voltage offset and inserting modified switching sequences. A descriptive performance analysis of the modified SVM technique is applied under healthy and faulty conditions. Correspondingly, the effects of the total harmonic distortion of the system performance are also highlighted and explained. The results reveal that the proposed control strategy can effectively maintain healthy and safe operation under faulty conditions without the need for additional parts or alteration of the topology configuration. In addition, the proposed method can be applied to HANPCs without special requirements to withstand high voltage levels. The effectiveness of the proposed method is verified by simulation and experimental results.

ACS Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. Multi Open-/Short-Circuit Fault-Tolerance Using Modified SVM Technique for Three-Level HANPC Converters. IEEE Transactions on Power Electronics 2021, 36, 13621 -13633.

AMA Style

Laith M. Halabi, Ibrahim Mohd Alsofyani, Kyo-Beum Lee. Multi Open-/Short-Circuit Fault-Tolerance Using Modified SVM Technique for Three-Level HANPC Converters. IEEE Transactions on Power Electronics. 2021; 36 (12):13621-13633.

Chicago/Turabian Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. 2021. "Multi Open-/Short-Circuit Fault-Tolerance Using Modified SVM Technique for Three-Level HANPC Converters." IEEE Transactions on Power Electronics 36, no. 12: 13621-13633.

Journal article
Published: 22 April 2021 in IEEE Transactions on Power Electronics
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Three-level neutral-point-clamped (3L-NPC) voltage source inverters are widely used in many low- and medium-power applications. However, these inverters have an inheritance issue of the unbalancing of the neutral-point (NP) voltage due to the deviation of dc-link capacitor voltages, causing distortions of the output waveform quality. Generally, discontinuous pulse-width modulation (DPWM) is used to reduce the stress on power transistors and prolong their lifespan; however, it cannot solve the issue of unbalancing of the NP voltage. Therefore, this paper proposes a simple voltage balancing control based on DPWM with a hysteresis NP error band. The balancing control method is only activated once the capacitance voltage error exceeds the hysteresis band through a momentary offset generated in the opposite direction of the DPWM offset. Thus, both the top and bottom capacitance voltages will converge within a predefined error band. Various hysteresis error bands are investigated by analyzing the power losses and total harmonic distortions, and common mode voltage. The advantages of the proposed method are its simplicity and ease of control while maintaining the features of DPWM. The effectiveness of the proposed method is validated using simulation and experimental results.

ACS Style

Ibrahim Mohd Mohd Alsofyani; Kyo-Beum Lee. Simple Capacitor Voltage Balancing for Three-Level NPC Inverter Using Discontinuous PWM Method With Hysteresis Neutral-Point Error Band. IEEE Transactions on Power Electronics 2021, 36, 12490 -12503.

AMA Style

Ibrahim Mohd Mohd Alsofyani, Kyo-Beum Lee. Simple Capacitor Voltage Balancing for Three-Level NPC Inverter Using Discontinuous PWM Method With Hysteresis Neutral-Point Error Band. IEEE Transactions on Power Electronics. 2021; 36 (11):12490-12503.

Chicago/Turabian Style

Ibrahim Mohd Mohd Alsofyani; Kyo-Beum Lee. 2021. "Simple Capacitor Voltage Balancing for Three-Level NPC Inverter Using Discontinuous PWM Method With Hysteresis Neutral-Point Error Band." IEEE Transactions on Power Electronics 36, no. 11: 12490-12503.

Original article
Published: 25 March 2021 in Journal of Electrical Engineering & Technology
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ACS Style

Ha-Rang Jo; Ye-Ji Kim; Kyo-Beum Lee. LCL-Filter Design Based on Modulation Index for Grid-Connected Three-Level Hybrid ANPC Inverters. Journal of Electrical Engineering & Technology 2021, 16, 1517 -1525.

AMA Style

Ha-Rang Jo, Ye-Ji Kim, Kyo-Beum Lee. LCL-Filter Design Based on Modulation Index for Grid-Connected Three-Level Hybrid ANPC Inverters. Journal of Electrical Engineering & Technology. 2021; 16 (3):1517-1525.

Chicago/Turabian Style

Ha-Rang Jo; Ye-Ji Kim; Kyo-Beum Lee. 2021. "LCL-Filter Design Based on Modulation Index for Grid-Connected Three-Level Hybrid ANPC Inverters." Journal of Electrical Engineering & Technology 16, no. 3: 1517-1525.

Journal article
Published: 09 March 2021 in IEEE Access
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This paper proposes a reduction method for DC-link ripple current and common-mode voltage (CMV) in a hybrid active neutral-point-clamped (ANPC) inverter. A Si and SiC hybrid ANPC inverter has been developed recently to overcome the extremely high cost of a full-SiC ANPC inverter. A hybrid ANPC requires much fewer SiC MOSFETs than a full-SiC ANPC inverter while providing a comparable power density. Voltage source inverters such as hybrid ANPC inverters utilize electrolytic capacitors, which have a large capacitance per volume, as a DC link. However, an electrolytic capacitor is one of the most vulnerable components in a power electronic converter due to its small allowable ripple current. A large ripple current flowing into the electrolytic capacitor generates a heat loss, which shortens the lifetime of the capacitor. Furthermore, the common-mode voltage (CMV) causes an undesirable leakage current and electromagnetic interference. The CMV depends on the pulse-width modulation of the voltage source inverters. The proposed method enhances the reliability of the hybrid ANPC inverter by reducing the DC-link ripple current and CMV simultaneously. The effectiveness and validity of the proposed method are verified through simulations and experimental results.

ACS Style

Sang-Won An; Seok-Min Kim; Kyo-Beum Lee. Capacitor Lifetime Extension in a Hybrid Active Neutral-Point-Clamped Inverter With Reduction of DC-Link Ripple Current and Common-Mode Voltage. IEEE Access 2021, 9, 40336 -40348.

AMA Style

Sang-Won An, Seok-Min Kim, Kyo-Beum Lee. Capacitor Lifetime Extension in a Hybrid Active Neutral-Point-Clamped Inverter With Reduction of DC-Link Ripple Current and Common-Mode Voltage. IEEE Access. 2021; 9 ():40336-40348.

Chicago/Turabian Style

Sang-Won An; Seok-Min Kim; Kyo-Beum Lee. 2021. "Capacitor Lifetime Extension in a Hybrid Active Neutral-Point-Clamped Inverter With Reduction of DC-Link Ripple Current and Common-Mode Voltage." IEEE Access 9, no. : 40336-40348.

Journal article
Published: 09 February 2021 in IEEE Transactions on Industrial Electronics
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This paper proposes a dynamic characteristic improvement of phase-shift full-bridge center-tapped (PSFB-CT) converter using a model predictive control (MPC) method. The PSFB-CT converter is widely used for low voltage DC/DC converters (LDC) in electric vehicles (EVs). In general, its output voltage is a control object which is usually controlled using a proportional-integral (PI) control-based output voltage controller and current controller. However, it has a disadvantage such as undesirable dynamic characteristic of the PSFB-CT converter and the necessity of gain tuning. Especially, if the gain of the PI controller is increased to improve the dynamic characteristic of the PSFB-CT converter, an overshoot of the output voltage can occur. In this paper, the advanced voltage control using the MPC method is proposed to improve the dynamic characteristic of the PSFB-CT converter without overshoot of the output voltage. As a result, not only fast dynamic characteristic but also robustness from a sudden change of load impedance. The effectiveness of the proposed MPC method was proved by the simulation and experimental results

ACS Style

Yeongsu Bak; Young Jae Lee; Kyo-Beum Lee. Dynamic Characteristic Improvement of Phase-Shift Full-Bridge Center-Tapped Converters Using a Model Predictive Control. IEEE Transactions on Industrial Electronics 2021, PP, 1 -1.

AMA Style

Yeongsu Bak, Young Jae Lee, Kyo-Beum Lee. Dynamic Characteristic Improvement of Phase-Shift Full-Bridge Center-Tapped Converters Using a Model Predictive Control. IEEE Transactions on Industrial Electronics. 2021; PP (99):1-1.

Chicago/Turabian Style

Yeongsu Bak; Young Jae Lee; Kyo-Beum Lee. 2021. "Dynamic Characteristic Improvement of Phase-Shift Full-Bridge Center-Tapped Converters Using a Model Predictive Control." IEEE Transactions on Industrial Electronics PP, no. 99: 1-1.

Original article
Published: 02 February 2021 in Journal of Power Electronics
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This paper presents a method for transitioning between sensorless rotor position estimation methods for an interior permanent magnet synchronous motor (IPMSM). Through the proposed method, rotor position estimation over the entire speed range of the IPMSM is possible. Considering that each sensorless method governs a different speed range for estimating rotor position and speed with good accuracy, a strategy for transitioning between two methods is indispensable. In this study, a sensorless method based on extended back electromotive force (EMF) is used for high-speed operation. In addition, during low-speed operation, rotor position is estimated using the slope of measured current through the application of a zero-voltage vector. A weight function is applied to the position and speed information obtained from the two sensorless methods. The combined information is then used throughout the speed range of the IPMSM. To achieve smooth transitions, the weight function is altered based on the rotor speed in the transition region. The effectiveness of the proposed transition method was demonstrated via simulations and experiments.

ACS Style

Hyung-Woo Lee; Dae-Hyun Cho; Kyo-Beum Lee. Rotor position estimation over entire speed range of interior permanent magnet synchronous motors. Journal of Power Electronics 2021, 21, 693 -702.

AMA Style

Hyung-Woo Lee, Dae-Hyun Cho, Kyo-Beum Lee. Rotor position estimation over entire speed range of interior permanent magnet synchronous motors. Journal of Power Electronics. 2021; 21 (4):693-702.

Chicago/Turabian Style

Hyung-Woo Lee; Dae-Hyun Cho; Kyo-Beum Lee. 2021. "Rotor position estimation over entire speed range of interior permanent magnet synchronous motors." Journal of Power Electronics 21, no. 4: 693-702.

Original article
Published: 28 January 2021 in Journal of Power Electronics
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This study proposes a modified modulation scheme based on the phase-shifted pulse-width modulation (PS-PWM) method to improve the output performance and reduce the switching loss in cascaded H-bridge multilevel inverters. The PS-PWM method is one of the most popular modulation schemes. However, it generates significant switching loss, which can lead to the failure of power semiconductor switches. Various studies have proposed modulation schemes to reduce switching loss. The clamped discontinuous PWM (DPWM) method achieves the best switching loss reduction performance in comparison with other modulation schemes. However, the clamped DPWM method has low output characteristics, such as total harmonic distortion. The proposed modulation scheme achieves the same switching loss reduction and improved output performance by modifying the dwell time order. The proposed evenly clamped DPWM method was compared with the conventional clamped DPWM method through simulations and experiments.

ACS Style

Eui-Jae Lee; Kyo-Beum Lee. Performance improvement of cascaded H-bridge multilevel inverters with modified modulation scheme. Journal of Power Electronics 2021, 21, 541 -552.

AMA Style

Eui-Jae Lee, Kyo-Beum Lee. Performance improvement of cascaded H-bridge multilevel inverters with modified modulation scheme. Journal of Power Electronics. 2021; 21 (3):541-552.

Chicago/Turabian Style

Eui-Jae Lee; Kyo-Beum Lee. 2021. "Performance improvement of cascaded H-bridge multilevel inverters with modified modulation scheme." Journal of Power Electronics 21, no. 3: 541-552.

Journal article
Published: 13 December 2020 in Electronics
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This study presents finite set-predictive torque control (FS-PTC) with discrete space vector modulation (DSVM) for indirect matrix converter (IMC)-fed permanent magnet synchronous motors (PMSMs). The implementation of FS-PTC with DSVM in an IMC requires high computation time due to the large number of synthesized voltage vectors (VVs). To reduce computation time caused by considering all VVs, a new preselection strategy is proposed to reduce the computational numerations from 37 to 6 VVs. The proposed algorithm can reduce torque and flux ripples and achieve robust characteristics against parameter variations. Additionally, the increased degree of VVs can improve the correlation between the rectifier and inverter sides of the IMC. The effectiveness of the proposed method is verified by simulation and experimental results.

ACS Style

Ibrahim Mohd Alsofyani; Yeongsu Bak; Kyo-Beum Lee. Improved Finite Set-Predictive Torque Control of PMSM Fed by Indirect Matrix Converter with Discrete Space Vector Modulation. Electronics 2020, 9, 2133 .

AMA Style

Ibrahim Mohd Alsofyani, Yeongsu Bak, Kyo-Beum Lee. Improved Finite Set-Predictive Torque Control of PMSM Fed by Indirect Matrix Converter with Discrete Space Vector Modulation. Electronics. 2020; 9 (12):2133.

Chicago/Turabian Style

Ibrahim Mohd Alsofyani; Yeongsu Bak; Kyo-Beum Lee. 2020. "Improved Finite Set-Predictive Torque Control of PMSM Fed by Indirect Matrix Converter with Discrete Space Vector Modulation." Electronics 9, no. 12: 2133.

Original article
Published: 30 October 2020 in Journal of Power Electronics
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A current-balancing strategy for a multileg interleaved DC/DC converter with a reduced number of current sensors for electric-vehicle chargers is proposed in this paper. There are imbalances between the leg currents of multileg DC/DC converters, which are caused by the difference between the leg impedances and the driver delay. Each of the leg current sensors must achieve current balancing. However, the conventional strategy is burdensome due to its high cost and volume. To mitigate these issues, the proposed balancing strategy effectively balances leg currents using fewer current sensors than the number of legs. The proposed strategy was verified by various simulation and experimental results.

ACS Style

Hye-Won Choi; Seok-Min Kim; Jinwoo Kim; Younghoon Cho; Kyo-Beum Lee. Current-balancing strategy for multileg interleaved DC/DC converters of electric-vehicle chargers. Journal of Power Electronics 2020, 21, 94 -102.

AMA Style

Hye-Won Choi, Seok-Min Kim, Jinwoo Kim, Younghoon Cho, Kyo-Beum Lee. Current-balancing strategy for multileg interleaved DC/DC converters of electric-vehicle chargers. Journal of Power Electronics. 2020; 21 (1):94-102.

Chicago/Turabian Style

Hye-Won Choi; Seok-Min Kim; Jinwoo Kim; Younghoon Cho; Kyo-Beum Lee. 2020. "Current-balancing strategy for multileg interleaved DC/DC converters of electric-vehicle chargers." Journal of Power Electronics 21, no. 1: 94-102.

Original article
Published: 28 October 2020 in Journal of Power Electronics
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This paper proposes the independent switching technique to remove abnormal output voltage in hybrid active neutral-point clamped (ANPC) inverters. The hybrid ANPC inverter is composed by mixing silicon (Si) devices and silicon carbide (SiC) devices, unlike the conventional ANPC inverter which is generally composed of Si devices only. SiC devices provide low switching losses under a high switching frequency and a high withstand ability under high temperature compared with Si devices. Therefore, the hybrid ANPC inverter using SiC devices provides low power losses, high efficiency, and high reliability compared with the conventional ANPC inverters. In this hybrid ANPC inverter, abnormal output voltages are generated when the sinusoidal output current crosses the zero point. The abnormal output voltages are momentary pulses that must not be generated, and these pulses distort the output current and degrade the power quality. These pulses have two typical causes: one is from the switching operation time difference between switches, and the other is from deadtime. This paper proposes the independent switching technique to remove the abnormal voltages caused by the two reasons and verifies the proposed technique by simulation and experiment.

ACS Style

Min-Geun Song; Seok-Min Kim; Kyo-Beum Lee. Independent switching technique to remove abnormal output voltage in hybrid active NPC inverters. Journal of Power Electronics 2020, 21, 85 -93.

AMA Style

Min-Geun Song, Seok-Min Kim, Kyo-Beum Lee. Independent switching technique to remove abnormal output voltage in hybrid active NPC inverters. Journal of Power Electronics. 2020; 21 (1):85-93.

Chicago/Turabian Style

Min-Geun Song; Seok-Min Kim; Kyo-Beum Lee. 2020. "Independent switching technique to remove abnormal output voltage in hybrid active NPC inverters." Journal of Power Electronics 21, no. 1: 85-93.

Journal article
Published: 13 October 2020 in IEEE Transactions on Power Electronics
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This paper proposes a method to eliminate abnormal output voltages generated in three-level hybrid active neutral-point clamped (ANPC) inverters. The hybrid ANPC inverter is a topology which silicon (Si) devices are replaced with silicon-carbide (SiC) devices in part from conventional ANPC topology. The hybrid ANPC inverters have the advantages of high-switching frequency and low power switching loss due to the SiC devices. In this hybrid ANPC inverter, abnormal output voltages occur when the polarity of the output pole voltage is changed from positive to negative. The cause of the abnormal voltages is the switching time difference between Si and SiC devices, and it is various from a few nano-seconds to a few micro-seconds. These abnormal output voltages need to be eliminated as it leads to degraded output power quality in the hybrid ANPC inverters. The proposed switching method effectively eliminates the abnormal output voltages and reduces output current distortion. The performance of the proposed method is verified using a prototype of the new three-level hybrid ANPC inverter type through both simulations and experiments.

ACS Style

Min-Geun Song; Seok-Min Kim; Kyo-Beum Lee. Elimination of Abnormal Output Voltage in a Hybrid Active NPC Inverter. IEEE Transactions on Power Electronics 2020, 36, 5348 -5361.

AMA Style

Min-Geun Song, Seok-Min Kim, Kyo-Beum Lee. Elimination of Abnormal Output Voltage in a Hybrid Active NPC Inverter. IEEE Transactions on Power Electronics. 2020; 36 (5):5348-5361.

Chicago/Turabian Style

Min-Geun Song; Seok-Min Kim; Kyo-Beum Lee. 2020. "Elimination of Abnormal Output Voltage in a Hybrid Active NPC Inverter." IEEE Transactions on Power Electronics 36, no. 5: 5348-5361.

Journal article
Published: 01 October 2020 in IEEE Access
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In recent decades, renewable energy has become an important part of the power generation field. In any renewable energy system, power converters form the dominant part, owing to their important role. However, such converters are exposed to the danger of single and/or multiple open- and short-circuit faults. This paper proposes a creative control strategy for tolerating the faults by generating a new switching sequence and reference signals in hybrid active natural point clamped (ANPC) converters. The hybrid ANPC convertors are exposed to consequent short- or open-circuit faults simultaneously for each kind of faults. In these regards, the operation under multi-short-circuit and multi-open-circuit faults are analyzed and described. Correspondingly, the control strategy with the selection of new vectors under the faulty conditions is explained and clarified in detail. Furthermore, the proposed strategy does not require installing any additional devices or changing the original topology, and it can be applied to hybrid ANPC converters without any special requirements to withstand high voltage levels. The effectiveness of the proposed control strategy is verified and confirmed by simulation results and experimentally tested using a 15-kW hybrid ANPC prototype converter.

ACS Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. Multiple-Fault-Tolerant Strategy for Three-Phase Hybrid Active Neutral Point Clamped Converters Using Enhanced Space Vector Modulation Technique. IEEE Access 2020, 8, 180113 -180123.

AMA Style

Laith M. Halabi, Ibrahim Mohd Alsofyani, Kyo-Beum Lee. Multiple-Fault-Tolerant Strategy for Three-Phase Hybrid Active Neutral Point Clamped Converters Using Enhanced Space Vector Modulation Technique. IEEE Access. 2020; 8 (99):180113-180123.

Chicago/Turabian Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. 2020. "Multiple-Fault-Tolerant Strategy for Three-Phase Hybrid Active Neutral Point Clamped Converters Using Enhanced Space Vector Modulation Technique." IEEE Access 8, no. 99: 180113-180123.

Journal article
Published: 29 September 2020 in IEEE Transactions on Power Electronics
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This paper presents a DC-link capacitor lifetime improvement method for three-level photovoltaic (PV) hybrid active neutral-point clamped (ANPC) inverters in full modulation index range. The capacitors are one of the components with vulnerable reliability in a power conversion system. The DC-link capacitor current ripples lead to temperature rise and wear-out failure of the capacitors. The accumulated thermo-mechanical damages from the temperature rise reduce the capacitor lifetime and reliability of the system. The proposed modulation method suppresses effectively the DC-link capacitor current ripple to improve the capacitor lifetime. In this paper, the proposed method is discussed via a comparison with conventional space-vector pulse width modulation (SVM) in full modulation index range. The modulation index range is divided into two regions, namely medium-vector modulation and hybrid modulation region. The capacitor lifetime is evaluated by the capacitor lifetime model according to the modulation methods and modulation regions. The effectiveness of the proposed modulation method is verified through simulation and experimental results.

ACS Style

Ye-Ji Kim; Seok-Min Kim; Kyo-Beum Lee. Improving DC-Link Capacitor Lifetime for Three-Level Photovoltaic Hybrid Active NPC Inverters in Full Modulation Index Range. IEEE Transactions on Power Electronics 2020, 36, 5250 -5261.

AMA Style

Ye-Ji Kim, Seok-Min Kim, Kyo-Beum Lee. Improving DC-Link Capacitor Lifetime for Three-Level Photovoltaic Hybrid Active NPC Inverters in Full Modulation Index Range. IEEE Transactions on Power Electronics. 2020; 36 (5):5250-5261.

Chicago/Turabian Style

Ye-Ji Kim; Seok-Min Kim; Kyo-Beum Lee. 2020. "Improving DC-Link Capacitor Lifetime for Three-Level Photovoltaic Hybrid Active NPC Inverters in Full Modulation Index Range." IEEE Transactions on Power Electronics 36, no. 5: 5250-5261.

Journal article
Published: 23 September 2020 in Electronics
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Direct torque control (DTC) is considered one of the simplest and fastest control strategies used in motor drives. However, it produces large torque and flux ripples. Replacing the conventional two-level hysteresis torque controller (HTC) with a four-level HTC for a three-level neutral-point clamped (NPC) inverter can reduce the torque and flux ripples in interior permanent magnet synchronous motor (IPMSM) drives. However, the torque will not be controlled properly within the upper HTC bands when driving the IPMSM in the medium and high-speed regions. This problem causes the stator current to drop, resulting in poor torque control. To resolve this problem, a simple algorithm based on a torque error average calculation is proposed. Firstly, the proposed algorithm reads the information of the calculated torque and the corresponding torque reference to calculate the torque error. Secondly, the average value of torque error is calculated instantaneously as the reference torque changes. Finally, the average value of the torque error is used to indicate the operation of the proposed algorithm without the need for motor speed information. By using the proposed algorithm, the torque can be controlled well in all speed regions, and thus, a better stator current waveform can be obtained. Simulation and experimental results validate the effectiveness of the proposed method.

ACS Style

Samer Saleh Hakami; Kyo-Beum Lee. Four-Level Hysteresis-Based DTC for Torque Capability Improvement of IPMSM Fed by Three-Level NPC Inverter. Electronics 2020, 9, 1558 .

AMA Style

Samer Saleh Hakami, Kyo-Beum Lee. Four-Level Hysteresis-Based DTC for Torque Capability Improvement of IPMSM Fed by Three-Level NPC Inverter. Electronics. 2020; 9 (10):1558.

Chicago/Turabian Style

Samer Saleh Hakami; Kyo-Beum Lee. 2020. "Four-Level Hysteresis-Based DTC for Torque Capability Improvement of IPMSM Fed by Three-Level NPC Inverter." Electronics 9, no. 10: 1558.

Journal article
Published: 21 September 2020 in Electronics
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The conventional finite set–predictive torque control of permanent magnet synchronous motors (PMSMs) suffers from large flux and torque ripples, as well as high current harmonic distortions. Introducing the discrete space vector modulation (DSVM) into the predictive torque control (PTC-DSVM) can improve its steady-state performance; however, the control complexity is further increased owing to the large voltage–vector lookup table that increases the burden of memory. A simplified PTC-DSVM with 73 synthesized voltage vectors (VVs) is proposed herein, for further improving the steady-state performance of the PMSM drives with a significantly lower complexity and without requiring a VV lookup table. The proposed scheme for reducing the computation burden is designed to select an optimal zone of space vector diagram (SVD) in the utilized DSVM based on the torque demand. Hence, only 10 out of 73 admissible VVs will be initiated online upon the optimal SVD zone selection. Additionally, with the proposed algorithm, no flux error is required to control the flux demand. The proposed PTC-DSVM exhibits high performance features, such as low complexity with less memory utilization, reduced torque and flux ripples, and less redundant VVs in the prediction process. The simulation and experimental results for the 11 kW PMSM drive are presented to prove the effectiveness of the proposed control strategy.

ACS Style

Ibrahim Mohd Alsofyani; Kyo-Beum Lee. Predictive Torque Control Based on Discrete Space Vector Modulation of PMSM without Flux Error-Sign and Voltage-Vector Lookup Table. Electronics 2020, 9, 1542 .

AMA Style

Ibrahim Mohd Alsofyani, Kyo-Beum Lee. Predictive Torque Control Based on Discrete Space Vector Modulation of PMSM without Flux Error-Sign and Voltage-Vector Lookup Table. Electronics. 2020; 9 (9):1542.

Chicago/Turabian Style

Ibrahim Mohd Alsofyani; Kyo-Beum Lee. 2020. "Predictive Torque Control Based on Discrete Space Vector Modulation of PMSM without Flux Error-Sign and Voltage-Vector Lookup Table." Electronics 9, no. 9: 1542.

Journal article
Published: 19 September 2020 in Electronics
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Three-level converters are the most important technologies used in high power applications. Among these technologies, active neutral point clamped (ANPC) converters are mainly used for industrial applications. Meanwhile, recent developments have reduced losses and increased efficiency by using a hybrid combination of Si-IGBT and SiC-MOSFET switches to achieve hybrid ANPC (HANPC) converters. Open-circuit failure is regarded as a common and serious problem that affects the operational performance. In this paper, an effective fault-tolerant method is proposed for HANPC converters to safely re-utilize normal operation and increase the reliability of the system under fault conditions. Sequentially, regarding different topologies with reference to earlier fault tolerance methods which could not be applied to the HANPC, the proposed strategy enables continuous operation under faulty conditions effectively without using any additional devices by creating new voltage references, voltage offset, and switching sequences under the faulty conditions. Consequently, no additional costs or changes are associated with the inverter. A detailed analysis of the proposed strategy is presented highlighting the effects on the voltage, currents, and the corresponding total harmonic distortion (THD). The simulation and experimental results demonstrate the capability and effectiveness of the proposed method to maintain normal operation and eliminate the output distortion.

ACS Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. Open-Circuit Fault Tolerance Method for Three-Level Hybrid Active Neutral Point Clamped Converters. Electronics 2020, 9, 1535 .

AMA Style

Laith M. Halabi, Ibrahim Mohd Alsofyani, Kyo-Beum Lee. Open-Circuit Fault Tolerance Method for Three-Level Hybrid Active Neutral Point Clamped Converters. Electronics. 2020; 9 (9):1535.

Chicago/Turabian Style

Laith M. Halabi; Ibrahim Mohd Alsofyani; Kyo-Beum Lee. 2020. "Open-Circuit Fault Tolerance Method for Three-Level Hybrid Active Neutral Point Clamped Converters." Electronics 9, no. 9: 1535.

Journal article
Published: 03 September 2020 in Electronics
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This paper proposes a fault-detection method for open-switch failures in hybrid active neutral-point-clamped (HANPC) rectifiers. The basic HANPC topology comprises two SiC-based metal-oxide-semiconductor field-effect transistors (MOSFETs) and four Si insulated-gate bipolar transistors (IGBTs). A three-phase rectifier system using the HANPC topology can produce higher efficiency and lower current harmonics. An open-switch fault in a HANPC rectifier can be a MOSFET or IGBT fault. In this work, faulty cases of six different switches are analyzed based on the current distortion in the stationary reference frame. Open faults in MOSFET switches cause immediate and remarkable current distortions, whereas, open faults in IGBT switches are difficult to detect using conventional methods. To detect an IGBT fault, the proposed detection method utilizes some of the reactive power in a certain period to make an important difference, using the direct-quadrant (dq)-axis current information derived from the three-phase current. Thus, the proposed detection method is based on three-phase current measurements and does not use additional hardware. By analyzing the individual characteristics of each switch failure, the failed switch can be located exactly. The effectiveness and feasibility of the proposed fault-detection method are verified through PSIM simulations and experimental results.

ACS Style

Sang-Hun Kim; Seok-Min Kim; Sungmin Park; Kyo-Beum Lee. Switch Open-Fault Detection for a Three-Phase Hybrid Active Neutral-Point-Clamped Rectifier. Electronics 2020, 9, 1437 .

AMA Style

Sang-Hun Kim, Seok-Min Kim, Sungmin Park, Kyo-Beum Lee. Switch Open-Fault Detection for a Three-Phase Hybrid Active Neutral-Point-Clamped Rectifier. Electronics. 2020; 9 (9):1437.

Chicago/Turabian Style

Sang-Hun Kim; Seok-Min Kim; Sungmin Park; Kyo-Beum Lee. 2020. "Switch Open-Fault Detection for a Three-Phase Hybrid Active Neutral-Point-Clamped Rectifier." Electronics 9, no. 9: 1437.

Journal article
Published: 18 August 2020 in IEEE Transactions on Industrial Electronics
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This paper presents a novel cascaded multilevel inverter as an alternative to the cascaded H-bridge (CHB). By adopting two H-bridges integrated with two inductors and two power switches, the proposed topology is able to generate a five-level voltage with merely a single dc source. Voltage-boosting capability is guaranteed despite its single-stage operation. A corresponding modulation technique is also established to charge the boost inductors with a constant duty-cycle, while simultaneously generating a 5-level ac voltage. Therefore, the proposed topology outperforms the CHB in reducing the isolated dc source count, enhancing the voltage gain, and lowering the dc source voltage magnitude. In addition, the modularity is preserved, where the proposed topology can be extended by cascading multiple modules. The operation and feasibility of the proposed cascaded multilevel inverter is analyzed and validated through simulation and experimental results.

ACS Style

Sze Sing Lee; Yongheng Yang; Yam Prasad Siwakoti; Kyo-Beum Lee. A Novel Boost Cascaded Multilevel Inverter. IEEE Transactions on Industrial Electronics 2020, 68, 8072 -8080.

AMA Style

Sze Sing Lee, Yongheng Yang, Yam Prasad Siwakoti, Kyo-Beum Lee. A Novel Boost Cascaded Multilevel Inverter. IEEE Transactions on Industrial Electronics. 2020; 68 (9):8072-8080.

Chicago/Turabian Style

Sze Sing Lee; Yongheng Yang; Yam Prasad Siwakoti; Kyo-Beum Lee. 2020. "A Novel Boost Cascaded Multilevel Inverter." IEEE Transactions on Industrial Electronics 68, no. 9: 8072-8080.