• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.639-646
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• 2003

Nowadays traction motors in the urban rail transit vehicle are controlled by VVVF inverter and have capability of regenerative braking. The algorithms to deal with the regenerating vehicle in simulation for the DC traction power supply is introduced in this paper. Substations have to be separated from the system to represent reverse biased rectifiers in substations. The model of the trains in regenerative braking has to be changed from the ideal current source to the constant voltage source since the train input voltage has to be controlled below the certain train maximum voltage. Some mismatches are unevitable because the constraint of the regenerated power can not be imposed with the constant voltage source. The mismatches represent the unused regenerated power. A computer program is developed to verify the validity of the algorithm. The test run result shows the program behaves as it is expected and proves the algorithm's validity.

• Journal of Power Electronics
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• v.9 no.3
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• pp.481-490
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• 2009

This paper describes a SVPWM overmodulation scheme of NPC type three-level inverter for traction drives which extends the modulation index from MI=0.907 to unity. SVPWM strategy is organized by two operation modes of under-modulation and over-modulation. The switching states under the under-modulation modes are determined by dividing them with two linear regions and one hybrid region the same as the conventional three-level inverter. On the other hand, under the over-modulation mode, they are generated by doing it with two over-modulation regions the same as the conventional over-modulation strategy of a two level inverter. Following the description of over-modulation scheme of a three-level inverter, the system description of a vector controlled induction motor for traction drives has been discussed. Finally, the validity of the proposed modulation algorithm has been verified through simulation and experimental results.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.414-419
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• 1998

This paper describes the dynamical performance of a four-quadrant circulation current mode control of dc motor drive, using the controlled flywleeling technique, a four-quadrant closed-loop control drive with an inner current control loop and a speed fuzzy PI regulator is designed. The obtained computer simulation results of a dc motor drive below and above the base speed are demonstrated. These result show that compare to a conventional dual-converter-fed dc motor drive with simultaneous control, the overal system performance has been improved and also, agood stability and robstness has been achieved.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.739-742
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• 2004

The term 'Grid' refers to systems and applications that integrate and manage resources and services distributed across multiple control domains. Resource sharing is, necessarily, highly controlled, with resource providers and consumers defining clearly and carefully just what is shared, who is allowed to share, and the conditions under which sharing occurs. In this paper, we design and implement a grid access control system, called PGAM. This system works on heterogeneous resources, can be applied to the additional service development and its service, provides template account management mechanism, and tries to ensure site autonomy. This system is implemented to increase portability and to be tit tll any kind of economic model.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.87-92
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• 2001

Automotive suspension system is a mechanism for isolation of the vibration coming from the road inputs. Recently, the electronically controlled suspension systems which may improve ride and handling performance have been developed. Here, the continuously controlled semi-active suspension system is focused. As a mechanism to control damping forces continuously, a solenoid valve is used. The modeling for the solenoid valve is introduced briefly, a vehicle dynamics modeling is constructed, and then combined system model is completed. To design the efficient control algorithm for the semiactive suspension system the knowledge based fuzzy logic is applied and the technique how to apply the sky-hook theory to the fuzzy logic is developed. Finally, to confirm the improvement of performance the computer simulation is carried out.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.155-161
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• 2005

Governors control the revolution speed of heat engines such as diesel engines, steam turbines and gas turbines. Precise and prompt tests for the control performances of governors are essential both in governors' manufacturing processes and in governors' maintenance processes. In the conventional governor test systems controlled by analog type electronic controllers, the incorporation of heat engine's dynamics to the test system have been considered very difficult to realize. This study suggests a new governor test system controlled by a digital controller using a personal computer. The application of the digital controller to the test system instead of the analog type electronic controller have brought about the following advancements; (1) heat engine's dynamics could be implemented easily in the test system, (2) automatic test data acquisition both in steady state and in transient state enables us to save test time and to enhance the reliability of the tests.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.748-751
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• 1997

The White Beamline of the Pohang Accelerator Laboratory(PAL) consists of main and second slits, a microprobe system, two ion chambers, a video-microscope, and a Si(Li) detector. These machine components must be controlled remotely through computer system to make user experiments precise and speedy. A real-time computer control system was developed to control and monitor these machine components. A VNIEbus computer with OS-9 real-time operating system was used for low-level data acquisition and control. VME I/O modules were used for step motor control and scaler control. The software has modular structure for maximum performance and easy maintenance. We developed database, I/O driver, and control software. We used PC/Window95 for data logging and operator interface. Visual C++ was used graphical user interface programming. RS232C was used for communication between VME and PC.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.29-41
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• 2006

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.299-306
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• 2010

This paper proposes a new doubly-fed induction generator (DFIG) system using a matrix converter controlled by direct duty ratio pulse-width modulation (DDPWM) scheme. DDPWM is a recently proposed carrier based modulation strategy for matrix converters which employs a triangular carrier and voltage references in a voltage source inverter. By using DDPWM, the matrix converter can directly and effectively generate rotor voltages following the voltage references within the closed control loop. The operation of the proposed DFIG system was verified through computer simulation and experimental works with a hardware simulator of a wind power turbine, which was built using a motor-generator set with vector drive. The simulation and experimental results confirm that a matrix converter with a DDPWM modulation scheme can be effectively applied for a DFIG wind power system.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.527-529
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• 1986

Measurement and control system of weld pool is comprised of optical devices, image processor, personal computer and welding machine. Combinations of ND and Infrared filters were used to block the intense arc light and to get the clearer image of weld pool. Smoothing operation and conversion to binary data were performed to eliminate the noises and to decrease the processing time. A simple algorithm for feedback control was developed and weld pool size is controlled by welding current which is adjusted automatically with personal computer.