• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1117-1125
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• 2000

A current mode PWM method applied one cycle response to averaging circuit model Buck converters is presented. The controller nonlinear PWM implement is based on the error between the switched variable and the response reference to zero each cycle. As the result, the system transfer function is derived as a function of the desired close loop poles, simplifying the design procedure and bringing forward all the important characteristics of the close loop system. The proposed controller has significant advantages over conventional current mode control methods in noise susceptibility, dynamic response and without inductor current sensing, Finally, the simulation and experiment results confirm the proposed PWM control techniques.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.272-281
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• 2000

This paper deals with the parallel operation of several numbers of PWM converters for a high speed railway train application. Several considerations are made to reduce the transformer interaction which can cause a current control problem in severe case. Also, in this paper, novel control strategy is proposed to achieve a harmonic free primary-side current control under a light load condition using one current sensor independent of the number of converters. In addition, the modified predictive current controller, which is suitable to a digital current controller with a relatively large sampling period, is used. Finally, to verify the system validity, digital control system with TMS320C44 micro-processor and small scale simulator are made and tested.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.346-351
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• 1998

In design of a digital current controller for a 3-phase (3 ) voltage-source (VS) PWM converter, its conventional model, i.e., stationary or synchronous reference frame model, is used in obtaining its discretized version. It introduces, however, inherent errors since the following practical problems are not taken into consideration: the characteristics of the space vector-based pulse-width modulation (SVPWM) and the time delays in the process of sampling and computation. In this paper, the new hybrid reference frame model of the 3 VS PWM converter is proposed considering these problems. In addition, the direct digital current controller based on this model is designed without any prediction or extrapolation algorithm to compensate the time delay. So the control algorithm is made very simple. It represents no steady-state error in input current control and has the optimized transient responses. The validity of the proposed algorithm is proved by the computer simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.372-376
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• 2001

Due to several advantages of Pulse Width Modulation(PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system. In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments. So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.491-495
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• 2001

Compare with diode or thyristor bridge AC/DC converter, the 3 phase PWM converter has some merits of low THD and unit power factor. So, in many critical application like as UPS, using PWM converter is the trends. 3 phase PWM converter had been studied widely already. But analytical design procedure can not found from publication for hardware design and controller design. So, in this paper, 3 phase PWM converter analysis review was given. And from the DC analysis result, parameter design was done. From the AC model, the voltage controller and current controller was designed. The gain of controllers was calculated by analytical method.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.27-33
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• 1993

This paper presents the &tal controller for driving high frequency voltage fed PWM inverter that carrier frequency is over 2OkHz.We analyzed the conventional PWM to select a proper PWM pattern. as the result, obtained PWM pattern of the controller in which asynchronus staircase sinusoidal waveform is used as reference signal, and variable carrier ratio method was used for PWM control. The PWM controller is designed by fully digital method. Especially, Thk proposed controller is consisted of 8 bit one-chip microprocessor and digital logic. the former is for arithmetic and data processing, and the latter is for PWM pattern synthesis. Therefore, The responsibility and controllability is improved. Also, Data processing capability is improved using proper program to output modulation index with 9 bits. Circuits configuration of digital controller are made up of one chip 8051 and EPLD, and its controllability is tested by operating voltage fed inverter. Harmonics and current waveform is evaluated and analyzed for the voltage fed inverter system.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1248-1250
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• 2000

The aim of this paper is to present a review of recently used current control technique for three-phase voltage source pulse-width modulated converters. Various technique, different in concept, three current control methods are presented in this paper. Current -control methods to be applied in system are PI controller. Predictive current controller. Minimum-time current controller respectively. In initial state and transient state, the response characteristics of three current control methods are verified through simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.27-36
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• 2007

This paper proposes a current control scheme of the PWM converters under nonideal source voltage conditions such as unbalance and distortion. For the distorted source voltage, the harmonic current controllers are introduced to the conventional current controller. These control loops can eliminate the 5th and 7th order harmonics which are hardly to be done by using filters. For the unbalanced source voltage, a negative sequence current controller is introduced either to reduce the DC-link voltage ripples or to eliminate the source current unbalance. Experimental results show the validity of the proposed control scheme.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.259-267
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• 1994

This paper describes a current control of a single-phase PWM inverter. The proposed PWM inverter utilizes the instantaneous control method which is based on the real-time digital feedback control and the microprocessor-based deadbeat control. The deadbeat current controller is proposed to control the output current regardless of load component variations by the same method as voltage control. That is, in current control, with a very short sampling time and the successive feedback of the output current, the load current is mainly effected by the magnitude of load impedance rather than load component, the load current is mainly effected by the magnitude of load impedance rather than load component. Therefore, by treating the load as an impedance, the system's order is reduced and the instantaneous current control using the proposed deadeat controller is simplified.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.489-492
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• 1999

This paper proposes a control method for three-phase voltage-source PWM converters using only a single current sensor in the DC link. A predictive current controller for the voltage-source PWM converter is used so that all phase currents can be reconstructed in a switching period although one or two of active vectors are applied only for a short time. Compensation of the 2 step delays is also included. In this paper single sensor current control using predictive state observer will be discussed, and investigated experimentally.