[24] J. H. Lee and U. M. Choi, “Discontinuous Pulse Width Modulation for Improving Reliability of NPC Inverter operated at High Modulation Index” in Proc. of ECCE Europe, Sept. 2023.

[23] T. L. Lee and U. M. Choi, “Influence of Different PWM Methods on Thermal Loadings of Power Devices and DC-link Capacitors of Single-Phase Five-Level T-type NPC Inverter,” in Proc. of ICPE-ECCE Asia, May 2023.

[22] J. H. Lee and U. M. Choi, “Pulse Width Modulation Method for Reliability Improvement of DC-link Capacitors and Power Devices of NPC Inverter” in Proc. of ICPE-ECCE Asia, May 2023.

[21] J. H. Park, U. M. Choi, and J. S. Lee, “Sinusoidal Third Harmonic Voltage Injection PWM Method for Applying the LCL Filter to Vienna Rectifier,” in Proc. of ICPE-ECCE Asia, May 2019.

[20] U. M. Choi, and F. Blaabjerg, “Effect of Asymmetric Layout of IGBT Modules on Reliability of Power Inverters in Motor Drive System,” in Proc. of AEPC 2018, Mar. 2018.

[19] U. M. Choi, and F. Blaabjerg, “Real-time condition monitoring of IGBT modules in PV inverter systems,” in Proc. of CIPS 2018, Mar. 2018.

[18] U. M. Choi, and F. Blaabjerg, “Asymmetric Power Device Rating Selection for Even Temperature Distribution in NPC Inverter,” in Proc. of ECCE 2017, pp. 4196-4201, Oct. 2017.

[17] K. Ma, U. M. Choi and F. Blaabjerg, “Reliability Metrics Extraction for Power Electronics Converter Stressed by Thermal Cycles,” in Proc. of ECCE 2017, pp. 3838-3842, Oct. 2017.

[16] U. M. Choi, K. Ma and F. Blaabjerg, “Lifetime Prediction of IGBT Modules based on Linear Damage Accumulation,” in Proc. of APEC 2017, pp. 2276-2281, Mar. 2017.

[15] K. Ma, U. M. Choi, and F. Blaabjerg, “Impacts of Ripple Current to the Loading and Lifetime of Power Semiconductor Device,” in Proc. of APEC 2017, pp. 2305-2311, Mar. 2017.

[14] U. M. Choi, F. Blaabjerg, and S. Jørgensen, “Effect of Junction Temperature Swing Durations on a Lifetime of a Transfer Molded IGBT Module,” in Proc. of ECCE 2016, Sep. 2016.

[13] U. M. Choi, F. Blaabjerg, S. Munk-Nielsen, S. Jørgensen and B. Rannestad, “Condition Monitoring of IGBT Module for Reliability Improvement of Power Converters,” in Proc. of ITEC Asia-Pacific 2016, pp. 602-607. June 2016.

[12] U. M. Choi, and F. Blaabjerg, “A novel active T-type three-level converter with open-circuit fault-tolerant control,” in Proc. of ECCE 2015, pp. 4765-4772. Sep. 2015.

[11] U. M. Choi, I. Trintis, F. Blaabjerg, S. Jørgensen, and M. L. Svarre, “Advanced Power Cycling Test for Power Module with On-line On-state VCE Measurement,” in Proc. of APEC 2015, pp. 2919-2924, Mar. 2015.

[10] U. M. Choi, F. Blaabjerg, J. S. Lee, and K. B. Lee, “Open-circuit fault diagnosis for a grid-connected NPC inverter with unity Power Factor,” in Proc. of APEC 2015, pp. 213-220, Mar. 2015.

[9] U. M. Choi, and F. Blaabjerg, “Junction temperature estimation for an advanced active power cycling test,” in Proc. of ICPE-ECCE Asia 2015, pp. 2944-2950, June 2015.

[8] U. M. Choi, F. Blaabjerg, and K. B. Lee, “Independent control strategy of two DC-link voltages for separate MPPTs in transformerless photovoltaic systems using neutral-point-clamped inverters,” in Proc. of APEC 2014, pp. 1718-1724, Mar. 2014.

[7] U. M. Choi, K. B. Lee and F. Blaabjerg, “Method to minimize the low-frequency neutral-point voltage oscillations with time-offset injection for neutral-point-clamped inverters,” in Proc. of ECCE 2013, pp. 4022-4029. Sep. 2013.

[6] U. M. Choi, and K. B. Lee, “Detection method of an open-switch fault and fault-tolerant strategy for a grid-connected T-type three-level inverter system,” in Proc. of ECCE 2012, pp. 4188-4195. Sep. 2012.

[5] U. M. Choi, H. G. Jeong and K. B. Lee, “Method of neutral-point voltage balancing for a grid connected NPC inverter system with time-offset variant estimating,” in Proc. of IPEMC 2012, pp. 499-504. Jun. 2012.

[4] U. M. Choi, K. B. Lee and F. Blaabjerg, “Diagnosis method of an open-switch fault for a grid-connected T-type three-level inverter system,” in Proc. of PEDG 2013, pp. 470-475. Jun. 2012.

[3] U. M. Choi, Kyo-Beum Lee, and Frede Blaabjerg, “Power electronics for renewable energy systems: Wind turbine and photovoltaic systems,” in Proc. of ICRERA 2012, Nov. 2012.

[2] H. H. Lee, U. M. Choi, and Kyo-Beum Lee “Neutral-Point Voltage Control for Grid-connected Three-Level Inverters using a Discontinuous Pulse Width Modulation,” in Proc. of VCCP 2012, pp. 638-642, Oct. 2012.

[1] H. G. Jeong, U. M. Choi, Kyo-Beum Lee, “Control strategies for wind power systems to meet grid code requirements,” in Proc. of IECON 2011, pp. 1250 – 1255, Nov. 2011.