Chan Roh's research while affiliated with Inje University and other places

Publications (10)

Article
Full-text available
In this study, a hydraulic system generator power converter was modeled to verify the performance of a hydraulic-based power take-off (PTO) system. Moreover, the characteristics and output performance of the PTO system were analyzed with various load control algorithms applied for maximum power control. The simulation performance was verified throu...
Article
Full-text available
A study on the capacity increase of a power converter according to the increase in the single capacity of wave energy converters and four-leg topology that can supply stable power even under unbalanced load conditions during independent operation is required. Therefore, in this paper, the performances of various four-leg inverters, from two-level i...
Article
Full-text available
The installation of fixed offshore wind power systems at greater water depths requires a floating body at the foundation of the system. However, this presents various issues. This study analyzes the characteristics of the platform motion of a floating offshore wind turbine system based on the performance of the pitch controller. The motion characte...
Article
Full-text available
This study uses deep learning algorithms to predict the rotational speed of the turbine generator in an oscillating water column-type wave energy converter (OWC-WEC). The effective control and operation of OWC-WECs remain a challenge due to the variation in the input wave energy and the significantly high peak-to-average power ratio. Therefore, the...
Article
An integrated analysis is required to evaluate the performance of control algorithms used in power take-off (PTO) systems for floating wave energy converters (FWECs). However, research on PTO systems based on the existing hydraulic device has mainly focused on the input power generation performance rather than on obtaining maximum power through hyd...
Article
This paper presents a computational reduction algorithm for applying model predictive control to a three-level four-leg converter. An optimal switching state is selected by only considering 7 voltage vectors located near the reference voltage vector, rather than using 81 voltage vectors in every sampling period, as in the conventional method. The s...
Article
Finite control set model predictive control (MPC) method needs calculations corresponding to the total number of voltage vectors made by power converters. This operating principle of the MPC leads to an increase in the computational load and number of calculations, which dramatically increase proportional to the increase in the level of cascaded H-...

Citations

... The most common working principle of a point absorber is that a buoy heaves against the seabed as a reaction to incident waves, and a power take-off (PTO) system converts the kinetic energy of the buoy to useful energy. Although other degrees of freedom, e.g., pitch for solo Duck WECs [4,5], of a point absorber may also be employed to absorb wave energy, heave seems to be the most effective [6]. An axisymmetric buoy is preferred for a heaving point absorber due to its ability to absorb power equally efficiently from waves coming from different directions, and a vertical truncated cylindrical buoy is frequently chosen [7][8][9][10][11]. ...
... Among the best suitable power electronic device as switchmode DC to AC is Multi-Level Inverters (MLIs) [9]. So many MLIs topologies have been proposed by researchers such as cascaded H-bridge (CHB) [10,11], Flaying capacitors and the neutral point clamped NPC inverters [12][13][14]. The generation of the inverter control signals is based on the concept of pulse width modulation (PWM) which allows both to control the output voltage and to reduce the current harmonics in order to supply the AC load with consistent power quality [15]. ...
... The space vector pulse width modulation (SVPWM) is commonly used for the current control, where the reference voltage is synthesized by two neighboring candidate voltage vectors and a zero vector (see Figure 1) with a certain duty cycle calculated by the modulator. The motor current, as well as the torque generated by the SVPWM, is smooth, but the switching frequency for the inverters is constant, normally with a high value (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), even if the current reference is zero. It consequently results in high energy consumption and a low lifetime for the inverters [4]. ...