International Journals (SCIE)

 2021 

[34] U. M. Choi and J. S. Lee, “Single-Phase Five-Level IT-Type NPC Inverter with Improved Efficiency and Reliability in Photovoltaic Systems,” IEEE Journal of Emerging and Selected Topics in Power Electronics, in press.

[33] J. S. Lee and *U. M. Choi, “Velocity Profile based Evaluation and Improvements of Lifetime of Power Devices in Railway Propulsion Inverters,” IEEE Journal of Emerging and Selected Topics in Power Electronics, in press.
[32] U. M. Choi and T. Ryu, Comparative Evaluation of Efficiency and Reliability of Single-Phase Five-Level NPC Inverters for Photovoltaic Systems,” IEEE Access, in press.


 2020
[31] U. M. Choi, “Study on Effect of Installation Location on Lifetime of PV Inverter and DC-to-AC Ratio,” IEEE Access, vol. 8, pp. 86003-86011, 2020.
[30] U. M. Choi, I. Vernica, D. Zhou, and F. Blaabjerg, “Comparative evaluation of reliability assessment methods of power modules in motor drive inverter,” Microelectronics Reliability, vols. 114, 113730, Nov. 2020.
[29] I. Vernica, *U. M. ChoiH. Wang, and F. Blaabjerg, “Wear-out failure of an IGBT module in motor drives due to uneven thermal impedance of power semiconductor devices,” Microelectronics Reliability, vols. 114, 113800, Nov. 2020.
[28] U. M. Choi and J. S. Lee, “Comparative Evaluation of Lifetime of Three-Level Inverters in Grid-Connected Photovoltaic Systems,” Energies, vol. 13, no. 5, 2020.

 2019
[27] J. S. Lee and *U. M. Choi, "Comparison of Heat-Pipe Cooling System Design Processes in Railway Propulsion Inverter Considering Power Module Reliability, " Energies, vol. 12. no. 24, Dec. 2019.

[26] U. M. Choi, J. S. Lee, and F. Blaabjerg, Effects of Power Cycling Test Condition and Test Strategy on Lifetime Estimation of Power Modules in Power Electronic Systems,” Microelectronics Reliability, vols. 100-101, Sep. 2019.

[25] U. M. Choi, S. Jørgensen, and F. Blaabjerg, Impact of Cooling System Capacity on Lifetime of Power Module in Adjustable Speed Drives,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol.7, no, 3, pp. 1768-1776, Sep. 2019.

[24] U. M. Choi, I. Vernica, and F. Blaabjerg, “Effect of Asymmetric Layout of IGBT Modules on Reliability of Motor Drive Inverters,” IEEE Transactions on Power Electronics, vol. 34, no. 2, pp. 1765-1772. Feb. 2019.

 2018
[23] K. Ma, U. M. Choi, and F. Blaabjerg, “Prediction and Validation of Wear-Out Reliability Metrics for Power Semiconductor Devices With Mission Profiles in Motor Drive Application," IEEE Transactions on Power Electronics, vol. 33, no. 11, pp. 9843-9853. Nov. 2018.
[22] U. M. Choi, S. Jørgensen, F. Iannuzzo, F. Blaabjerg, “Power cycling test of transfer molded IGBT modules by advanced power cycler under different junction temperature swigns," Microelectronics Reliability, vols. 88-90, pp. 788-794, Sep. 2018.
[21] U. M. Choi , and F. Blaabjerg, “Separation of Wear-out Failure Modes of IGBT Modules in Grid-Connected Inverter Systems,” IEEE Transactions on Power Electronics, vol. 33, no. 7, pp. 6217-6223. July 2018.

[20] U. M. Choi, K. Ma and F. Blaabjerg, “Validation of Lifetime Prediction of IGBT Modules Based on Linear Damage Accumulation by Means of Superimposed Power Cycling Tests,” IEEE Transactions on Industrial Electronics, vol. 65, no. 4, pp. 3520-3529. Apr. 2018.

​[19] U. M. Choi, F. Blaabjerg, and S. Jørgensen, “Power Cycling Test Methods for Reliability Assessment of Power Device Modules in respect to Temperature Stress,” IEEE Transactions on Power Electronics, vol. 33, no. 3, pp. 2531-2551. Mar. 2018.

 2017
 

[18] U. M. Choi, F. Blaabjerg, S. Munk-Nielsen, S. Jørgensen and B. Rannestad, “Reliability Improvement of Power Converters by Means of Condition Monitoring of IGBT Modules,” IEEE Transactions on Power Electronics, vol. 32, no. 10, pp. 7990-7997. Oct. 2017.

[17] U. M. Choi, F. Blaabjerg and F. Iannuzzo, “Advanced Power Cycler with Intelligent Monitoring Strategy of IGBT Module Under Test,” Microelectronics Reliability, vols. 76-77, pp. 522-526, Sep. 2017.

[16] U. M. Choi, F. Blaabjerg, and S. Jørgensen, “Study on Effect of Junction Temperature Swing Duration on Lifetime of Transfer Molded Power IGBT Modules,” IEEE Transactions on Power Electronics, vol. 32, no. 8, pp. 7990-7997. Aug. 2017.

 2016

[15] U. M. Choi, S. Jørgensen and F. Blaabjerg, “Advanced Accelerated Power Cycling Test for Reliability Investigation of Power Device Modules,” IEEE Transactions on Power Electronics, vol. 31, no. 12, pp. 8371-8386. Dec. 2016 

[14] U. M. Choi, J. S. Lee, F. Blaabjerg, and K. B. Lee, “Open-Circuit Fault Diagnosis and Fault-Tolerant Control for a Grid-Connected NPC Inverter,” IEEE Transactions on Power Electronics, vol. 31, no. 10, pp. 7234-7247. Oct. 2016. 

[13] U. M. Choi, F. Blaabjerg, S. Jorgensen, F. Iannuzzo, H. Wang, C. Uhrenfeldt, and S. Munk-Nielsen, “Power cycling test and failure analysis of molded Intelligent Power IGBT Module under different temperature swing durations,” Microelectronics Reliability, vol. 64, pp. 403-408, Sep. 2016.

 2015

[12] J. S. Lee, U. M. Choi, and K. B. Lee, “Comparison of Tolerance Controls for Open-Switch Fault in a Grid-Connected T-Type Rectifier,” IEEE Transactions  on Power Electronics, vol. 30, no. 10, pp. 5810-5820, Oct. 2015.

[11] U. M. Choi, F. Blaabjerg, F. Iannuzzo, and S. Jørgensen, “Junction temperature estimation method for a 600 V, 30A IGBT module during converter operation,” Microelectronics Reliability, vol. 55, no. 9-10, pp. 2022-2026, Aug.-Sep. 2015.

[10] U. M. Choi, F. Blaabjerg, and K. B. Lee, “Control Strategy of Two Capacitor Voltages for Separate MPPTs in Photovoltaic Systems Using Neutral-Point-Clamped Inverters,” IEEE Transactions on Industry Applications, vol. 51, no. 4, pp. 3295-3303. July-Aug. 2015.

[9] U. M. Choi, F. Blaabjerg, and K. B. Lee, “Reliability Improvement of a T-Type Three-Level Inverter With Fault-Tolerant Control Strategy,” IEEE Transactions on Power Electronics, vol. 30, no. 5, pp. 2660-2673. May 2015.

[8] U. M. Choi, F. Blaabjerg, and K. B. Lee, “Study and Handling Methods of Power IGBT Module Failures in Power Electronic Converter Systems,” IEEE Transactions on Power Electronics, vol. 30, no. 5, pp. 2517-2533. May 2015.

[7] U. M. Choi, F. Blaabjerg, and K. B. Lee, “Method to Minimize the Low-Frequency Neutral-Point Voltage Oscillations With Time-Offset Injection for Neutral-Point-Clamped Inverters,” IEEE Transactions on Industry Applications, vol. 51, no. 2, pp. 1678-1691. Mar.-Apr. 2015.

 2014
 

[6] U. M. Choi, J. S. Lee and K. B. Lee, “New Modulation Strategy to Balance the Neutral-Point Voltage for Three-Level Neutral-Clamped Inverter Systems,” IEEE Transactions on Energy Conversion, vol. 29, no. 1, pp. 91-100. Mar. 2014.

[5] U. M. Choi, K. B. Lee, and, F. Blaabjerg “Diagnosis and Tolerant Strategy of an Open-Switch Fault for T-Type Three-Level Inverter Systems,” IEEE Transactions on Industry Applications, vol. 50, no. 1, pp. 495-508. Jan.-Feb. 2014.

 2013
 

[4] U. M. Choi, and K. B. Lee, “Space vector modulation strategy for neutral-point voltage balancing in three-level inverter systems,” IET Power Electronics, vol. 6, no. 7, pp. 1390-1398. Aug. 2013.

[3] U. M. Choi, H. H. Lee and K. B. Lee, “Simple Neutral-Point Voltage Control for Three-Level Inverters Using a Discontinuous Pulse Width Modulation,” IEEE Transactions on Energy Conversion, vol. 28, no. 2, pp. 434-443. Jun. 2013.

[2] U. M. Choi, and K. B. Lee, “Neutral-Point Voltage Balancing Method for Three-Level Inverter Systems with a Time-Offset Estimation Scheme,” Journal of Power Electronics, vol. 13, no. 2, pp. 243-249. Mar. 2013.

 2012
[1] U. M Choi, H. G. Jeong, K. B. Lee, and F. Blaabjerg, “Method for Detecting an Open-Switch Fault in a Grid-Connected NPC Inverter System,” IEEE Transactions on Power Electronics, vol. 27, no. 6, pp. 2726-2739, June 2012.