• Journal of Power Electronics
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• v.17 no.1
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• pp.190-199
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• 2017

In this paper, a predictive direct power control (DPC) method based on a Kalman filter is presented for three-phase pulse-width modulation (PWM) rectifiers to improve the performance of rectifiers with source voltages that are distorted with harmonic components. This method can eliminate the most significant harmonic components of the source voltage using a Kalman filter algorithm. In the process of predicting the future real and reactive power to select an optimal voltage vector in the predictive DPC, the proposed method utilizes source voltages filtered by a Kalman filter, which can mitigate the adverse effects of distorted source voltages on control performance. As a result, the quality of the source currents synthesized using the PWM rectifier is improved, and the total harmonic distortion (THD) values are reduced, even under distorted source voltages.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.85-89
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• 1998

A switching power stage is a very nonlinear system because it has two or more operation modes in one switching cycle. To model a switching power stage, the state space averaging method has been developed. Though it allows a unified treatment of a large variety of switching power stages, the model it yields is always very nonlinear. So, it is required to linearize the averaged model. But it is well known that a controller for a nonlinear plant designed by the linearization frequently fails in showing satisfactory control performance. Hence it is very natural to try to design a nonlinear controller for a switching power stage. In design of a switching power system, nonlinear control approaches such as adaptive control and fuzzy control have been widely studied so far. In this research, a recently developed control method, time delay control is briefly studied and a design example for a ZVS PWM half bridge converter is given. The performance of the time delay controller is compared to its conventional counterpart, PI controller by computer simulations.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.506-509
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• 2002

In this paper, a design method of LCL filter at the AC input side of a voltage source PWM converter is proposed. Effective method to prevent pollution of the utility caused by high frequency current ripple is to use a LCL filter instead of the L filter The C elements in the filter provide a low impedance path for the high frequency component, preventing them from entering the utility. A resistor in series with a capacitor is used for damping the resonance in the filter. The design examples are shown and the validity of the proposed design method is verified through the PSIM simulation.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1014-1015
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• 2006

In this paper, a new single phase voltage sag/swell compensator using direct power conversion is introduced. A new compensator consists of input/output filter, series transformer and direct at-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc-link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy to compensate voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method commonly required in the direct power conversion. Simulation results are shown to demonstrate the advantages of the new compensator and PWM strategy.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.325-329
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• 1994

This paper describes a compact design and control method of PWM inverter-mounted induction motor especially designed for reducing the size and weight considerably, which may be applied to the speed control system such as air conditionr,conveyor and textile mill, etc. To obtain higher power density without derating performance, a new mechanical configuration unifying the inverter circuit and motor is proposed. Also, through the use of current minimization control method during V/f operation it is possible to reduce the size of heat-sink related to the losses of power circuit. By the proposed design method, a compact inverter-mounted induction motor system of 1Hp is built and its validity can be verified through the experimental results.

• Journal of Power Electronics
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• v.9 no.4
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• pp.535-543
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• 2009

In this paper, pulse-width modulation (PWM) control strategy of various topologies of matrix converters is presented, which is based on direct duty ratio PWM (DDPWM). Because the DDPWM method has the characteristics of the inherent per-phase modular structure, it can be effectively applied to single-phase, two-phase and three-phase four-leg matrix converters as well as the common three-phase to three-phase matrix converter. Also, this paper treats command generation method in each matrix converter. The feasibility and validity of the proposed method are verified by experimental results.

• Journal of Power Electronics
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• v.13 no.1
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• pp.113-121
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• 2013

This paper introduces a simple core loss calculation method for output filter inductor in pulse width modulation (PWM) DC-AC inverter. Amorphous C-core (AMCC-320) is used to analyze the core loss. In order to measure core loss of the output filter inductor and validate the proposed method, a single-phase half-bridge inverter and a calorimeter are used. By changing switching frequency and modulation index (MI) of the inverter, core loss of the AMCC-320 is measured with the lab-made calorimeter and the results are compared with calculated core loss. The proposed method can be easily extended to other core loss calculation of various converters.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.290-298
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• 2010

This paper proposes an adaptive carrier-based pulse width modulation (PWM) method for a four-switch three-phase (4S3P) inverter under dc-link voltage ripple conditions. The proposed method guarantees balanced output currents despite of the existence of the voltage oscillations across two dc-link capacitors. And also, this new approach achieves a linear over-modulation with calculation time reduction. Simulation and experimental results are given to validate the feasibility of the proposed method.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.16-18
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• 2007

In this paper, an advanced DTC(Direct Torque Control) scheme for PMSM(Permanent Magnet Synchronous Motor) is presented. The proposed DTC method uses a conventional torque estimator and torque error. But the switching signal is generated by PWM method according to the switching rules and torque error. A simple calculation of PMW without any complex determination of space vector can assure the constant switching frequency with an excellent control performance. The proposed torque control scheme for PMSM is verified by computer simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.118-125
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• 2022

With the aim to maximize the use of a given voltage source in the field of railway and electric vehicles, this study applies a technique for controlling the overmodulation region between the linear and the six-step regions. High linearity overmodulation techniques that do not use look-up table (LUT) to digital signal processor (DSP) using carrier based pulse width modulation (PWM) are proposed. Such technique requires the phase of the voltage vector at the point where the circular trajectory of the voltage command vector and hexagonal cross each other. Therefore, a method is proposed to obtain a phase of a voltage vector that is derived through an equation and applied to a carrier-based PWM. Validity of the proposed implementation method is confirmed through simulation and experiment.