• Journal of the Korean Solar Energy Society
• /
• v.32 no.spc3
• /
• pp.228-234
• /
• 2012

This paper presents the algorithm of the compensation of the grid current distortion caused by the grid voltage unbalance and distortion in 3-phase bi-directional DC to AC inverter. Usually 3-phase grid system has unbalance and distortion because of connecting 1-phase and non-linear load with 3-phase load using same input node. Controlling 3-phase inverter by general method under the unbalanced and distorted grid voltage, the grid current has distortion. This distortion of the grid current cause the grid voltage distortion again. So, it need to control the grid current balanced and non-distorted, even the grid voltage gets unbalanced and distorted. There are some complex method to compensate the gird current distortion. it sugest simple method to solve the problem. PSIM simulation is used to validate the proposed algorithm.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.3
• /
• pp.266-273
• /
• 2012

In this paper, the new open fault detection and tolerant operation method for 3 phase PWM rectifier is proposed. When open fault occurred on the inverter switches of 3 Phase PWM rectifier, the DC link voltage ripple is increased because the input current of the faulty phase is distorted. In this case, the quality of electric power would decrease, and the life time of DC link capacitor is decreased. The open fault is detected by a simple MRAS(Model Reference Adaptive System) without additional hardware sensors, and the tolerant operation carried out by turning on the opposite switch of the faulty switch without any redundancy. By the proposed method, the faulty phase input current can be controlled, so that 3-phase input current is balanced relatively under the faulty condition and the voltage ripple of DC link output is reduced. The validity of the proposed technique is proved on the 6kW 3-phase PWM rectifier system by simulation and experiment.

• Journal of the Korean Society of Visualization
• /
• v.2 no.1
• /
• pp.39-45
• /
• 2004

A time-resolved two-phase PIV system using a single camera has been developed, which introduces a method of image separation into respective phase images, and is applied to freely rising single bubble. Gas bubble, tracer particle and background have different gray intensity ranges on the same image frame when reflection and dispersion in the phase interface are intrinsically eliminated by optical filters and fluorescent particles. Further, the signals of the two phases do not interfere with each other. Gas phase velocities are obtained from the separated bubble image by applying the two-frame PTV. On the other hand, liquid phase velocities are obtained from the tracer particle image by applying the cross-correlation algorithm. As a result, the bubble rises rectilinearly just after it is released from an injector and then has a zigzag motion in the far field. From the trajectory of the bubble, it is found that the period of the zigzag motion is closely related to the vortex shedding although the wavelength of it varies along its movement.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.1101-1107
• /
• 2017

In this paper, a robust and fast grid synchronization method of a three-phase power converter is proposed. The amplitude and phase information of grid voltages are essential for power converters to be properly connected into the utility. The phase-lock-loop in synchronous reference frame has been widely adopted for the three-phase converter system since it shows a satisfactory performance under balanced grid voltages. However, power converters often operate under abnormal grid conditions, i.e. unbalanced by grid faults and frequency variations, and thus a proper active and reactive power control cannot be guaranteed. The proposed method adopts a second order generalized integrator in synchronous reference frame to detect positive sequence components under unbalanced grid voltages. The proposed method has a fast and robust performance due to its higher gain and frequency adaptive capability. Simulation and experimental results show the verification of the proposed synchronization algorithm and the effectiveness to detect positive sequence voltage.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.8
• /
• pp.281-288
• /
• 1984

A new method of protecting 3-phase squirrel-cage induction motor aginst burning-out by unbalance operation is proposed. This paper studied various kinds of situations occurred by unbalance operating in 3-phase induction motor, and we provided the search coils in the slots of stator and rotor for the purpose of detecting electrical phenpmena during unbalance operation. Through experiments, we find that search coils in the slots of stator is effective method for protecting the induction motor from unbalance operating.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.752-755
• /
• 2000

This paper describes a new algorithm for active power filters which can be control source current symmetrically under unbalanced condition in power system. Positive sequency voltage is detected by symmetrical coordinate method and compensating reference current of active power filters is calculated using by accurate phase angle information of positive sequency voltage. The basic principle of the proposed method is described in detail and the conventional and proposed phase detecting methods are compared and discussed through the simulation results.

• 한국전산유체공학회:학술대회논문집
• /
• 2001.05a
• /
• pp.176-180
• /
• 2001

For windshield defrosting, flow analysis of inner room(vehicle) and heat conduction on the windshield surface are undertaken. Simulation for defrosting enthalpy method is usedand verification of heat and fluid flow analysis for room is done in cavity flow. The defrosting process is three dimensional phenomena and phase is changing. The result of defrosting analysis are well presenting the phase change and these results offer basic design data for defrosting phenomena.

• Proceedings of the KIEE Conference
• /
• 2007.04a
• /
• pp.113-118
• /
• 2007

In this paper, a new method is proposed for robust proportional- integral - derivative (PID) control that is to ensure specified phase margin and iso - damping property using reduction model. This method is based on the second order plus dead time(SOPDT) reduction model of the high order model. Reduction model used to ensure iso-damping property in the feature frequency. Simulation results gives proof of effectiveness of proposed method.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.76-78
• /
• 1999

In this paper, the 2-phase excitation method is proposed to reduce vibration and noise. This excitation method produces reluctance torque by mutual action between two phases as well as conventional-reluctance torque due to two phases excitation at a time. The vibration and acoustic noise is reduced thought the sequential phase excitation. This is because that the scheme reduces abrupt change of excitation level by distributed. balanced excitation.

• Journal of Korean Society for Quality Management
• /
• v.12 no.1
• /
• pp.17-30
• /
• 1984

A computer method is developed for group technology layout and its simulation analysis. The method is composed of three phases: Phase I sorts the parts by its similar production routes and forms part families. Phase II plots the layout by machine cell and evaluates the group layout alternatives by the total process time analysis and the part travel distance evaluation analysis. Phase III also evaluates the alternatives by simulation analysis using SIMAN simulation software. All the computer programs are developed with BASIC except SIMAN simulation.