• Journal of Power Electronics
• /
• v.11 no.5
• /
• pp.704-712
• /
• 2011

This paper describes a hybrid induction motor drive system incorporating DTC-hysteresis and Direct Self Control (DSC) schemes to achieve excellent dynamic performance. The control scheme is switched from a circular to a hexagonal flux locus whenever a dynamic condition is encountered. On the other hand, when the motor operates under steady state conditions, a circular flux locus is used. Without major modifications to the simple structure of a basic DTC, hexagonal flux locus operation is established by modifying the flux error status, before it is fed to the look-up table. The feasibility of the proposed hybrid scheme to achieve excellent control performance is verified by experimental results.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.1
• /
• pp.486-493
• /
• 2017

Refineries and chemical plants with isolated power systems that have a limited power supply are more susceptible to voltage changes from disturbances compared to power systems connected with a power company. Furthermore, most loads in such cases are induction motor loads, and therefore, transient voltage characteristics when starting a high-capacity motor must be examined. In general, high-capacity motors are customized appropriately to the load performance curve by the manufacturer during the construction of an industrial plant. Subsequently, when complying with the voltage drop permitted by international standards during the design process, power supply equipment such as transformers and generators is overdesigned. Therefore, a novel analysis is necessary on standards for startup and constraint voltage drops, as well as on identifying the voltage drop limitations for starting high-capacity motors in refineries and chemical plants with isolated power systems. In this study, field tests on an industrial plant were conducted, and simulations modeled under conditions identical to those of the field test system were performed using the general-purpose program ETAP in order to compare the results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.1
• /
• pp.43-49
• /
• 1999

We propose a nonlinear feedback controller that can control the induction motors with high dynamic performance and high power efficiency by means of decoupling of motor speed and rotor flux. The nonlinear feedback controller needs the information on some motor parameters. New recursive adaptation algorithms for rotor resistance and mutual inductance which can be applied to our nonlinear feedback controller are also presented in this paper. The recursive adaptation algorithms make the estimated values of rotor resistance and mutual inductance track their real values. Some simulation and experimental results show that the adaptation algorithms are robust against the variation of stator resistance and stator inductance.

• Proceedings of the KIPE Conference
• /
• 1998.11a
• /
• pp.18-22
• /
• 1998

A PWM inverter with an induction motor often has a problem with a high frequency leakage current that flows through stray capacitor between stator windings and a motor frame to ground. This paper presents an equivalent circuit for high frequency leakage currents in PWM inverter feeding an induction motor, which forms an LCR series resonant circuit. A conventional common mode ckoke or reactor in series between the ac terminals of a PWM inverter and those of an ac motor is not effective to reduce the rms and average values of the leakage current, but effective to reduce the peak value. Furthermore, this paper proposes a leakage current damper which is different in damping principle from the conventional common mode choke. It is shown theoretically and experimentally that the leakage current damper is able to reduce the rms value of the leakage current to 25%, where the core used in the leakage current damper is smaller than that of the conventional common-mode choke

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.1984-1986
• /
• 1998

This paper presents an optimal efficiency control for the inverter fed induction machine system using neural network. The motor speed and the load torque vary the efficiency characteristics of an induction motor. The optimal slip frequency has nonlinearity varied by the load torque as well as the motor speed. The induction motor is driven using the inverter system and the indirect vector control method which input is slip frequency. The neural network for estimating the optimal slip frequency has two input layer(the motor speed and the load torque) and one output layer(the optimal slip frequency that minimize the input power). Learning algorithm of the neural network is the back-propagation. Using the equivalent circuit including the nonlinearity of the induction motor, the loss reduction is analyzed quantitatively. Experimental results are shown noticeable power savings by proposed scheme in high speed and light load conditions.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.2
• /
• pp.304-315
• /
• 2013

In this paper, analysis of cascaded H-bridge multilevel inverter in DTC-SVM (Direct Torque Control-Space Vector Modulation) based induction motor drive for FCEV (Fuel Cell Electric Vehicle) is presented. Cascaded H-bridge multilevel inverter uses multiple series units of H-bridge power cells to achieve medium-voltage operation and low harmonic distortion. In FCEV, a fuel cell stack is used as the major source of electric power moreover the battery and/or ultra-capacitor is used to assist the fuel cell. These sources are suitable for utilizing in cascaded H-bridge multilevel inverter. The drive control strategy is based on DTC-SVM technique. In this scheme, first, stator voltage vector is calculated and then realized by SVM method. Contribution of multilevel inverter to the DTC-SVM scheme is led to achieve high performance motor drive. Simulations are carried out in Matlab-Simulink. Five-level and nine-level inverters are applied in 3hp FCEV induction motor drive for analysis the multilevel inverter. Each H-bridge is implemented using one fuel cell and battery. Good dynamic control and low ripple in the torque and the flux as well as distortion decrease in voltage and current profiles, demonstrate the great performance of multilevel inverter in DTC-SVM induction motor drive for vehicle application.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.600-604
• /
• 2000

In this paper authors proposed a new nonlinear rotor flux observer for rotor field oriented control of an induction motor which is designed based on theory of the extended Luenberger observer(ELO) one of a nonlinear state observer. The proposed rotor flux observer is derived from the 2 phase model of induction motor by the theory of ELO. The simulation results taken under the varying condition of rotor resistance and load torque show fast convergence of estimated rotor flux and high performance of IM drive system is achieved 표 experiment.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.4
• /
• pp.241-247
• /
• 2014

This paper propose a variable parameter estimations of five-phase squirrel-cage induction motor(IM) for speed control system. In order to high performance control of AC motor using a field oriented control(FOC) and direct torque control(DTC) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, rotor position, speed estimation, and so on. We are suggest a analyzed estimation results of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental of variable input power frequency. There are results of stator winding test, no-load test, locked-rotor test, variable actual load test, and estimated parameters of equivalent circuits using manufactured experimental apparatus by IEEE Standard Test Procedure for Polyphase Induction Motors and Generators 112-2004.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.12
• /
• pp.1041-1047
• /
• 1989

In recent years, a.c servomotors have been gradually replacing d.c servomotors in various high-performance applications such as machine tools and industrial robots. Inparticular, the high performance slip-frequency control of an induction motor, which is often called the vector control, is considered ane of th ebest a.c drives. In this paper, the transient state equations and vector control algorithms of an induction type servomotor are described mathematically by using the two- axis theory (d-q coordinates). According to the result of these algorithms, we scheme the speed control system for the motor in which the vector control is adopted to give high performance. Motor drive through a PWM inverter with power MOSFET is controlled so that the actual input current to the motor may track the current reference obtained from a micro-computer (8086 CPU). Driving experiments are performed in the range of 0 to 3000 rpm, and it is verified that high speed response is obtained for this system.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.1
• /
• pp.3-8
• /
• 1987

The conventional autosequentially commutated current-fed inverter (ASCI) is widely employed with the induction motor drives for speed control. Howener, this inverter has a limit of high power and high frequency indution motor drives. One of the limitations is to be found in the commutation capacitors in the main circuit of this inverter. A new current-fed gate turn-off thyristor (GTO) inverter is developed. This inverter is composed of the main GTO bridge configuration and the improved energy rebound circuit (ERC)without the commutation capacitor. This inverter works stable at high frequency from light load to heavy one. The improved ERC is used not only to rebound the load reactive power to the dc link, but also to return the power in the load to the ac source. The new GTO inverter circuit and the characteristics of the inverter induction motor drives are explained and analyzed.