Chang-Hwan Park
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Chang-Hwan Park has a total of 10 co-authors. Here are the top co-authors by number of shared publications:
- Jang-Mok Kim
Department of Electrical and Electronics Engineering, Pusan National University, Busan 46241, Republic of Korea
5 shared publications - Belete Belayneh Negesse
Department of Electrical and Computer Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, Korea
3 shared publications - Dong-Youn Kim
Department of Research and Development, Hyowon Powertech Company, Busan 46241, Republic of Korea
1 shared publication - Han-Beom Yeom
LG Electronics, Changwon 51544, Korea
1 shared publication - Hyun-Keun Ku
Next Generation Transmission & Substation, Korea Electric Power Research Institute (KEPRI), Daejeon, South Korea
1 shared publication - In-Kyo Seo
Air Solution Control Research Division, LG Electronic, 84, Wanam-ro, Seongsan-gu, Changwon 51554, Korea
1 shared publication
Latest Publications
- Open Access
Full Simulation Modeling of All-Electric Ship with Medium Voltage DC Power System
This paper proposes the full simulation model for the electrical analysis of all-electric ship (AES) based on a medium voltage DC power system. The AES has become popular both in the commercial and the military areas due to a low emission, a high fuel consumption efficiency, and a wide applicability. In spite of many advantages, it is complex and difficult to construct the whole system with many mechanical and electrical components onboard. Full electrical analysis is essentially required to simplify the design of the AES, a control and optimization of a ship electric system. The proposed full simulation model of the AES includes the mechanical and the electrical elements by using the MATLAB/Simulink. The mechanical elements are comprised of a steam turbine and a hydrodynamic model of a ship which is adopted by an average value model that is based on the characteristic equation of the mechanical system. The electrical elements are developed by full detailed models which consist of generators, a propulsion motor, a battery, and a power electronics system. In order to design the distribution of the ship, the presented simulation model combined the mechanical and the electrical systems. The consistency of the developed individual models and the integrated AES was verified through the results of the presence or absence of the energy storage system for the speed acceleration and deceleration, loss of prime mover, and full propulsion load rejection.
Open AccessFull Simulation Modeling of All-Electric Ship with Medium Voltage DC Power System
This paper proposes the full simulation model for the electrical analysis of all-electric ship (AES) based on a medium voltage DC power system. The AES has become popular both in the commercial and the military areas due to a low emission, a high fuel consumption efficiency, and a wide applicability. In spite of many advantages, it is complex and difficult to construct the whole system with many mechanical and electrical components onboard. Full electrical analysis is essentially required to simplify the design of the AES, a control and optimization of a ship electric system. The proposed full simulation model of the AES includes the mechanical and the electrical elements by using the MATLAB/Simulink. The mechanical elements are comprised of a steam turbine and a hydrodynamic model of a ship which is adopted by an average value model that is based on the characteristic equation of the mechanical system. The electrical elements are developed by full detailed models which consist of generators, a propulsion motor, a battery, and a power electronics system. In order to design the distribution of the ship, the presented simulation model combined the mechanical and the electrical systems. The consistency of the developed individual models and the integrated AES was verified through the results of the presence or absence of the energy storage system for the speed acceleration and deceleration, loss of prime mover, and full propulsion load rejection.
- Open Access
Optimized Modulation Method for Common-Mode Voltage Reduction in H7 Inverter
The three-phase H7 inverter topology installs an additional power semiconductor switch to the positive or negative node of the DC-link for reducing the common-mode voltage (CMV) by disconnecting the inverter from the DC source during the zero-voltage vectors. The conventional CMV reduction method for the three-phase H7 inverter uses modified discontinuous pulse width modulation (MDPWM) and generates a switching signal for the additional switch using logical operations. However, the conventional method is unable to eliminate the CMV for the entire dwell time of the zero-voltage vectors. It only has the effect of reducing the CMV in a limited area of the space vector where the zero voltage vector is applied. Therefore, this paper proposes an optimized modulation method that can reduce the CMV during the entire dwell time of zero-voltage vectors. The proposed method moves the switching patterns by adding an offset voltage to guarantee that only one kind of zero-voltage vector, , is applied in the system. It then turns off the seventh switch only during the zero-voltage vector to disconnect the inverter from the DC source. As a result, the CMV and the leakage current are attenuated for the entire dwell time of the zero-voltage vector. Simulation and experimental results confirm the validity of the proposed method.Open AccessOptimized Modulation Method for Common-Mode Voltage Reduction in H7 Inverter
The three-phase H7 inverter topology installs an additional power semiconductor switch to the positive or negative node of the DC-link for reducing the common-mode voltage (CMV) by disconnecting the inverter from the DC source during the zero-voltage vectors. The conventional CMV reduction method for the three-phase H7 inverter uses modified discontinuous pulse width modulation (MDPWM) and generates a switching signal for the additional switch using logical operations. However, the conventional method is unable to eliminate the CMV for the entire dwell time of the zero-voltage vectors. It only has the effect of reducing the CMV in a limited area of the space vector where the zero voltage vector is applied. Therefore, this paper proposes an optimized modulation method that can reduce the CMV during the entire dwell time of zero-voltage vectors. The proposed method moves the switching patterns by adding an offset voltage to guarantee that only one kind of zero-voltage vector, , is applied in the system. It then turns off the seventh switch only during the zero-voltage vector to disconnect the inverter from the DC source. As a result, the CMV and the leakage current are attenuated for the entire dwell time of the zero-voltage vector. Simulation and experimental results confirm the validity of the proposed method. - Open Access
A Study on Common Mode Voltage Reduction Strategies According to Modulation Methods in Modular Multilevel Converter
Low level modular multilevel converter (MMC) is a promising candidate for medium voltage applications such as MVDC (medium voltage DC current) transmission and megawatt machine drives. Unlike high-level MMC using nearest level modulation (NLM), the low-level MMC using the pulse width modulation (PWM) or NLM + PWM is affected by a common mode voltage (CMV) due to a frequent change of a switching state. This CMV causes electromagnetic interference (EMI) noise, common mode current (CMC) and bearing current leading to a reduction in the efficiency and durability of the motor drive system. Therefore, this paper provides a mathematical analysis on how the switching state affects the CMV and proposes three software based CMV reduction algorithms for the low level MMC system. To reflect the characteristic of MMC modulation strategy for upper and lower reference voltage independently, two separate space vectors are used. Based on the analysis, three different CMV reduction algorithms (complete CMV reduction (CCR), DPWM CMV reduction (DCR) and partial CMV reduction (PCR)) are proposed using NLC + PWM modulation strategy. The performance of the proposed CMV reduction algorithms was verified by both simulation and experimental result.
Open AccessA Study on Common Mode Voltage Reduction Strategies According to Modulation Methods in Modular Multilevel Converter
Low level modular multilevel converter (MMC) is a promising candidate for medium voltage applications such as MVDC (medium voltage DC current) transmission and megawatt machine drives. Unlike high-level MMC using nearest level modulation (NLM), the low-level MMC using the pulse width modulation (PWM) or NLM + PWM is affected by a common mode voltage (CMV) due to a frequent change of a switching state. This CMV causes electromagnetic interference (EMI) noise, common mode current (CMC) and bearing current leading to a reduction in the efficiency and durability of the motor drive system. Therefore, this paper provides a mathematical analysis on how the switching state affects the CMV and proposes three software based CMV reduction algorithms for the low level MMC system. To reflect the characteristic of MMC modulation strategy for upper and lower reference voltage independently, two separate space vectors are used. Based on the analysis, three different CMV reduction algorithms (complete CMV reduction (CCR), DPWM CMV reduction (DCR) and partial CMV reduction (PCR)) are proposed using NLC + PWM modulation strategy. The performance of the proposed CMV reduction algorithms was verified by both simulation and experimental result.
- 4 July 2019
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Industry Applications
- Vol. 55 (5) , 5005-5012
Compensation of Arm Current Sensor Errors in Modular Multilevel Converter
The modular multilevel converter(MMC) is an attractive topology for medium or high-power applications due to its high modularity, scalability and high power quality. Even if a direct modulated control algorithm guarantees a stable operation for the MMC system, it is unable to suppress the flow of a negative sequence second order leg current in the MMC. Mostly, for circulating current suppression, a PI Controller in the double fundamental frequency rotating reference frame is adopted. The three phase leg currents are calculated using the average of upper and lower arm currents of the respective phase after they are measured by arm current sensors. However, the previous Circulating current suppression controllers(CCSCs) do not consider the offset and scale error of the arm current sensors. This paper proposes an algorithm to compensate the offset and scale error of the arm current sensors. The proposed algorithm is easy to be implemented and effectively suppress the leg current components caused by the current sensor errors. The validity of the proposed algorithm is verified through both simulation and experimental results.
- 4 July 2019
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Industry Applications
- Vol. 55 (5) , 5005-5012
Compensation of Arm Current Sensor Errors in Modular Multilevel Converter
The modular multilevel converter(MMC) is an attractive topology for medium or high-power applications due to its high modularity, scalability and high power quality. Even if a direct modulated control algorithm guarantees a stable operation for the MMC system, it is unable to suppress the flow of a negative sequence second order leg current in the MMC. Mostly, for circulating current suppression, a PI Controller in the double fundamental frequency rotating reference frame is adopted. The three phase leg currents are calculated using the average of upper and lower arm currents of the respective phase after they are measured by arm current sensors. However, the previous Circulating current suppression controllers(CCSCs) do not consider the offset and scale error of the arm current sensors. This paper proposes an algorithm to compensate the offset and scale error of the arm current sensors. The proposed algorithm is easy to be implemented and effectively suppress the leg current components caused by the current sensor errors. The validity of the proposed algorithm is verified through both simulation and experimental results.
- Open Access
A Current Reconstruction Strategy Following the Operation Area in a 1-Shunt Inverter System
To reduce the cost of the inverter system in home appliances, a method using a shunt resistor at the DC-link can be substituted for a method using two current sensors at the inverter output. However, the minimum time of the active vector is required to sample the accurate current using a 1-shunt resistor. Therefore, many studies have been conducted investigating current reconstruction methods in the unmeasurable region of the current. The conventional methods using voltage injection have some problems such as high THD (Total Harmonic Distortion) and acoustic noise, because the PWM pattern is shifted. In addition, the current reconstruction is inaccurate in a low modulation region. In this paper, the cause of the noise in conventional methods is analyzed and a simple current reconstruction method based on an average current estimation and a current reference is utilized for reducing acoustic noise. In an immeasurable area, especially a low modulation region, an intermittent PWM shift method is proposed to enhance the accuracy of the reconstructed current. Therefore, a control strategy that combines all of the mentioned methods is implemented for the entire operating range. The effectiveness of the proposed methods is verified through the experimental results and the results of sound measurement in an anechoic chamber are included to compare with the acoustic noise.
Open AccessA Current Reconstruction Strategy Following the Operation Area in a 1-Shunt Inverter System
To reduce the cost of the inverter system in home appliances, a method using a shunt resistor at the DC-link can be substituted for a method using two current sensors at the inverter output. However, the minimum time of the active vector is required to sample the accurate current using a 1-shunt resistor. Therefore, many studies have been conducted investigating current reconstruction methods in the unmeasurable region of the current. The conventional methods using voltage injection have some problems such as high THD (Total Harmonic Distortion) and acoustic noise, because the PWM pattern is shifted. In addition, the current reconstruction is inaccurate in a low modulation region. In this paper, the cause of the noise in conventional methods is analyzed and a simple current reconstruction method based on an average current estimation and a current reference is utilized for reducing acoustic noise. In an immeasurable area, especially a low modulation region, an intermittent PWM shift method is proposed to enhance the accuracy of the reconstructed current. Therefore, a control strategy that combines all of the mentioned methods is implemented for the entire operating range. The effectiveness of the proposed methods is verified through the experimental results and the results of sound measurement in an anechoic chamber are included to compare with the acoustic noise.