• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.133-139
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• 2003

In this paper, a new control scheme of Class-E inverter for Induction Heating (IH) Jar applications with clamped voltage characteristics using Pulse-Frequency-Modulation (PFM) is introduced. To reduce the voltage stress of switch, the proposed PFM control scheme doesn't need any auxiliary circuit in comparison to a family of Active Clamped Class-E (ACCE) inverter. It can decrease voltage stress of switch through modulation of switching frequency. The Class-E inverter using the proposed control scheme has the advantage of not only the same output power when it is compared with a Hybrid-Active Clamped Class-E (Hybrid-ACCE) inverter but also Zero-Voltage-Switching (ZVS), which are characteristics of conventional Class-E and ACCE inverter. The control principles and analysis of proposed method are explained in detail and its validity is verified through simulation and experimental results.

• Journal of Power Electronics
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• v.2 no.2
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• pp.104-111
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• 2002

This paper presents a new hybrid control scheme using Active-Clamped Class-E(ACCE) inverter for the Induction Heating (IH) jar. The proposed hybrid control scheme has characteristics, which acts as class-E inverter at lower switch voltage and ACCE inverter at higher switch voltage than reference voltage of the main switch by feeding back voltage of the switch. The proposedv hybrid control scheme also has advantage of conventional ACCE inverter such as Zero-Voltage-Switch(ZVS) of the main switch and the reduced switch voltage due to clamping cricuit. Moreover, the proposed hybrid control method using ACCE inverter has higher output power than convenional control scheme since ACCE inverter operates like class-E inverter at low input voltage condition. The principles of the proposed control are explained in detail and the validity of the proposed control scheme is verifed through the several interesting simulated and experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.719-724
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• 2012

A traffic detection system is a device that collects traffic information around an intersection. Most existing traffic detection systems provide very limited traffic information for signal control due to the restriction of vehicle detection area. A signal control scheme determines the transition among signal phases and the time that a phase lasts for. However, the existing signal control scheme do not resolve the traffic congestion effectively since they use restricted traffic information. In this paper, a new traffic detection system with a zone division signal control scheme is proposed to provide correct and detail traffic information and decrease the vehicle's waiting time at the intersection. The traffic detection system obtains traffic information in a way of vehicle-to-roadside communication between vehicles and sensor network. A new signal control scheme is built to exploit the sufficient traffic information provided by the proposed traffic detection system efficiently. Simulation results show that the proposed signal control scheme has 121 % and 56 % lower waiting time and delay time of vehicles at an intersection than other fuzzy signal control scheme.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.115-118
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• 2001

This paper presents a new sensorless control scheme using simple duty signal feedback technique in DC-DC converters. The proposed sensorless control scheme (DFC) has the characteristics that they show the same as operation performance of current mode control by using duty feedback technique without current sensor as well as present better dynamic response performance than conventional sensorless current mode control (SCM) in case that input source is perturbed by step change or DC input source includes the . harmonics. Also, the proposed control scheme has good noise immunity and simple control circuits since they have one feedback loop, and can be applied to all DC-DC converters. The concept and control principles of the proposed control scheme are explained in detail and the validity of the proposed control scheme is verified through several interesting simulated results.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1416-1418
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• 2005

This paper presents a new hybrid control method of asymmetrical half-bridge converter(AHBC) with low voltage stresses of the diodes and interleaved PFC(power factor correction). The proposed new control scheme can observe variation of secondary diodes voltage stresses by variation of duty ratio and then decide the control portions which are asymmetrical control and PFM(Pulse Frequency Modulation). Therefore, the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, low conduction loss according to the low voltage drop and wide zvs range by load variation. Through simulation results, the validity of the proposed control scheme is demonstrated.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.680-687
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• 2000

In this paper we present a new vector control scheme for induction motor. An exact knowledge of the rotor flux position is essential for a high-performance vector control. The position of the rotor flux is measured in the direct scheme or estimated in the indirect schemes. Since the estimation of the flux position requires a priori knowledge of the induction motor parameters, the indirect schemes are machine parameter dependent. The rotor resistance and stator resistance among the parameters change with temperature. Variations in the parameters of induction machine cause deterioration of both the steady state and dynamic operation of the induction motor drive. Several methods have been presented to minimize the consequences of parameter sensitivity in indirect scheme. In this paper new estimation scheme of rotor flux position is presented to eliminate sensitivity due to resistance change with temperature. Simulation results are used to verify the performance of the proposed vector control scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.952-960
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• 1996

In this paper, a new overload control scheme is proposed for a control system in ATM switching system. The proposed control scheme includes a counter that conunts the number of accepted calls and is decreased at cach D time interval. In overload condition of call processor, the control scheme detects over load condition when the counter value reaches a certain threshold value. Under overload condition, processor utilization is measured and the value of the D is updataed according to the difference between measured processor utilization and target utilization. A new call is accepted accepted only if the value of the counter is less than the threshold value. In overflow condition of cell traffic, accept probability of new call is reduced exponetially according to the elapsed time. The results of simulation show that the proposed overload contorl scheme maintains the target utilization very well under the various processor overload conditions and reduces the cell loss probability under the cell overflow conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.795-802
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• 2002

We present a new dynamic routing scheme for multiple autonomous guided vehicles (AGVs) systems. There have been so many results concerned with scheduling and routing of multiple AGV systems; however, most of them are only applicable to systems with a small number of AGVs under a low degree of concurrency. With an increased number of AGVs in recent applications, these AGV systems are faced with another problem that has never been occurred in a system with a small number AGVs. This is the stop propagation problem. That is, if a leading AGV stops then all the following AGVs must stop to avoid any collision. In order to resolve this problem, we propose a nonstop preferential detour (NPD) algorithm which is a new dynamic routing scheme employing an election algorithm. For real time computation, we introduce two stage control scheme and propose a new path searching scheme, k-via shortest path scheme for an efficient dynamic routing algorithm. Finally, the proposed new dynamic routing scheme is illustrated by an example.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.230-232
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• 2000

To improve the voltage profile of the load bus, it is important that the coordinated controls among the reactive power compensators at the distribution substation. However, the conventional control scheme of the Under Load Tap Changer (ULTC) is not proper for coordinate control with Static Var Compensator (SVC). This paper proposes a new control model for ULTC and a new coordinated control scheme between ULTC and SVC. The numerical simulation verifies that the proposed system could improve the voltage profile on the load bus and could decrease the number of ULTC tap operation.

• 전기의세계
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• v.29 no.12
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• pp.791-797
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• 1980

This paper is concerned with the study of improving the faults of phase control scheme and suggesting a new approach to the control of load circuit with AC source. AC current control can restrict the magnitude of current within the given upper and lower current and make current continuous during every cycle. Also the harmonic contents of current can be greatly reduced using this control scheme. Analog computer and digital computer simulations reveal that the current control scheme is superior to the phase control scheme in controlling the power supply to the load R-L. Experimintal results demonstrate the feasibility and verify the operation of current controlled system.