• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.475-478
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• 2001

In performing the three-level SVPWM, it is nearly impossible to control the neutral-point potential exactly to the half of the dc-link voltage at all times. Therefore the inverter would produce an erroneous output voltage by this voltage unbalance. So the voltage unbalance has to be compensated in doing PWM, when the voltage unbalance occurs whether it is small or large, to make the inverter output voltage follow the reference voltage exactly the same. In this paper, a new compensating method for the neutral-point potential variation in a three-level inverter space vector PWM (SVPWM) is presented. By using the proposed method, the output voltage of the inverter can be made same as the reference voltage and thus the current and torque ripple of the inverter driven motor can be greatly improved even if the voltage unbalance is quite large. The proposed method is verified experimentally with a 3-level IGBT inverter.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.261-265
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• 1997

Driving the electrodeless fluorescent lamp, the high ac voltage with high frequency is required. The linear power amplifier has been widely used as a driving circuit of electrodeless fluorescent lamp. However, the low efficiency of the power amplifier causes th driving circuit to be replaced by a PWM switching inverter. In order to use a PWM switching inverter as the driving circuit of an electrodeless fluorescent lamp, the high switching frequency is required. But due to the switching loss at switches of the inverter, the limitation of high switching frequency appears in the inverter. One solution to this limitation is to reduce the switching loss by using the zero voltage switching technique. In this paper, zero voltage switching resonant inverter for driving an electrodeless fluorescent lamp is discussed. The results of analysis about the inverter are presented and the equations for design are established. And the validity of the analyzed results are verified through the experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.170-175
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• 2000

A new quasi-parallel resonant DC link inverter is proposed for three phase soft switching application. By i inserting only one additional switch, the proposed inverter excludes both voltage stresses and restricted PWM p problems, which are demerits of the conventional resonant inverter. In this paper, the circuit operations are e explained in detail using the operational mode analysis of the proposed inverter and design methods of the r resonant components are suggest('x:l. Lastly, the applicable possibility of the proposed inverter is vel예fied t through the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1047-1054
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• 2018

This paper proposed the strategies for controlling both the heater temperature and the output voltage of a single-phase inverter for the heat treatment. The single-phase inverter system for the heat treatment controls the heater temperature to its reference one, and also it limits the inverter output voltage to 60 V for safety. The stability may be deteriorated due to the large time constant difference between the heater temperature and inverter output voltage. In order to ensure the stability, a hysteresis on/off control approach for the heater temperature control is adapted, and both the open-loop and the closed-loop control strategies of the output voltage are suggested. The performances for the proposed strategies are demonstrated with the experiments.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.249-256
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• 2007

This paper presents a new circuit topology and its digital control scheme for a half-bridge resonant inverter. As the proposed half-bridge inverter can be operated in load-freewheeling modes, the pulse-width modulation (PWM) method can be used for the output power control. The proposed half-bridge inverter is based on the resonant frequency-tracking algorithm with the goal of maintaining the unity of the output displacement factor of the load impedance even in varying conditions. In this paper, the operation principle, electrical characteristics, and detailed digital control scheme of the proposed half-bridge resonant inverter are described. The experimental results of the prototype experimental setup to verify the validity of the proposed half-bridge inverter are presented and discussed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.68-72
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• 1990

In this paper, the technique of particul-ar harmonics elimination in three-phase PWM Inverter is discussed. And voltage control technique is derived whereby harmonics eli-mination is possible in variable voltage variable frequency three-phase I.M. The results show that experiments are in a good agreement with simulation based on the theory.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.222-227
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• 1997

Unbalanced source voltages due to unbalanced loads in the 3-phase power system is decomposed into positive, negative and zero sequence components. Also, assuming there is no neutural path in the system, the zero sequence component is not shown. Therefore, it is possible to compensate unbalanced source voltage by canceling the negative sequency component of the voltages of the source. In this paper, an algorithm compensating unbalanced source voltages by canceling the negative sequence component is presented and analysis of instantaneous voltage compensator using 3-phase PWM inverter is carried out through computer simulation.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.260-265
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• 1999

This paper describes a novel control method of a three-phase PWM inverter for uninterruptible power supply(UPS) applications. To obtain the fast dynamics and excellent harmonic characteristics, a new state feedback control technique is proposed. The proposed control consists of the inner-loop current and outer-loop voltage controllers with a load current estimator to reduce the effects of the load variations and nonlinearity. In order to verify the effectiveness of the proposed control, the simulation is carried out for various load condition.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.21-24
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• 2002

In this paper, induced voltages of the secondary conductors of a linear induction motor(LIM) with cage-type secondary are measured and analyzed when the LIM is fed by PWM inverter. The attenuation constant of the induced voltage of the secondary conductors near entry and exit zones of the the travelling magnetic field are determined from the experiment results.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.130-132
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• 1988

A usual line-commutated thyristor inverter with additional onebypass GTO is presented. With the added one bypass GTO, the extended commutating area is investigation and restrictions for the PWM to reduce the high frequency component of line current are shown.