• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.564-565
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• 2005

AC induction motor equipped in electric train is driven by VVVF inverter which produces switching pulse like impuse. Impulse voltage is more dangerous than continuous alternative voltage for the insulating performance of AC induction motor. This paper has investigated PD characteristics caused by impuse voltage for stator coils inserted in AC induction motor.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1035-1040
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• 1989

This paper describes first Boxes algorithm as a good method to generate the pulse patterns for a pulse width modulated inverter which has a good characteristics and simple to excute. Second we present the motor analysis fed by P.W.M. inverter in steady-state operation. In this analysis we improve the MRF ( Multiple Reference Frames ) to can be easy apply to analyse all the induction motor parameters. Finally we presented all the results obtained for a 3-phase induction motor.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.255-265
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• 2009

This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a $120^{\circ}$ conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a core-less brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A $180^{\circ}$ conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.78-85
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• 1995

This paper covers stability and stabilization of Multi-Excited Induction Motor used in numberous electric equipment system of industrial field. The induction motor with multi-excitation has tow sets of three-phase system : One is connected to the AC source to supply most power required at the load, and the other is to the inverter for variable frequency and/or magnitude of voltage. The conventional induction motor is operated under single excitation mode only, that is called induction mode. But in multi-excited induction motor both the induction mode and the synchronous mode are possible, and the proposed multi-excited induction motor can be driven as a synchronous motor by the extra three-phase input. At the synchronous mode the efficiency is improved so higher than that at induction mode or conventional induction motor. The rating of the inverter used for speed control of numberous electric equipment system can be reduced upto one-tenth of that for conventional induction motor. Also the cost and maintenance fee of multi-excited induction motor can be reduced compared to any other motor.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.650-654
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• 2007

Induction motors are widely used as a source of driving force in electric vehicles and pulse width modulation (PWM) inverters are applied to their operation. The issue is that insulation of inverter-fed induction motors (IFMs) are more stressed than in line-powered motors by transient voltages. This paper dealt with experimental results on transient voltage produced by the PWM operation of an induction motor. The peak and the dv/dt of transient voltage depending on the length of power feeding cable and operating frequency were investigated. In the experiment, transient voltages up to 3.3PU of the rated-inverter voltage were recorded for the cable length of 50m. As the cable length is increased, the peak voltage appeared at the motor terminals increases. This phenomenon can be explained by the reflection and the transmission of travelling wave. Consequently, special care for the cable length between the motor and the inverter should be taken in the use of IFM to ensure the full life of insulation system.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.175-181
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• 2016

In the conventional E-bike, a 42 V/10 A Li-ion battery drives a 24 V/10 A BLDC motor via a 6-switch PWM DC/AC inverter. The major problems of the conventional battery-fed motor drive systems are listed as follows. To charge the battery, an external battery charger (adapter) is required, which degrades the portability of E-bike users. In addition, given the high-frequency operation of the motor drive inverter, the switching losses are significant, which degrades the whole power efficiency. High-voltage batteries (42 V) require a complex battery management system (BMS), which degrades the reliability of the battery pack. In this paper, an embedded boost-converter battery charger for E-bikes is proposed. The variable output boost converter, which converts 16.8 V battery voltage to the required variable voltage of the inverter input, can use a low-voltage battery and thus improve the reliability of batteries. By varying the inverter input voltage via boost converter, a DC link voltage control method can be applied to reduce the switching frequency of the inverter, which improves the whole power efficiency. Given that the function of a flyback charger is integrated in the proposed boost converter, the portability of the E-bike user can be maximized by excluding an external adapter. The validity of the proposed circuit will be confirmed by operation mode analysis and simulation. Moreover, experimental results of integrative charger using Li-ion battery and 200 W motor test will be showed with a prototype sample as well.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.450-454
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• 1994

From a point of view in energy saving and improvement of productivity, inverter for large power induction motor drive is very important. In this thesis, we developed high voltage inverter for large power induction motor drive. We experimented the inverter with R-L series load, successfully, and are going to do the field test in the real plant.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1067-1074
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• 2018

This paper presents a control method for variable-speed motor drives that do not use a DC-link electrolytic capacitor. The proposed circuit consists of a power factor correction converter for boosting the DC-link voltage, an inverter for driving the motor, and a small DC-link film capacitor. By employing a small DC-link capacitor, the proposed circuit that is small, and a low cost and weight are achieved. However, because the DC-link voltage varies periodically, the control of the circuit is more difficult than that of the conventional method. Using the proposed control method, an inverter can be controlled reliably even when the capacitance of the DC-link capacitor is very small. Experiments are performed using a 1.5-kW inverter with a $20-{\mu}F$ DC-link capacitor, and the experimental results are analyzed thoroughly.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.695-698
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• 1992

When the inverter driven Induction motor is compared with sinusoidal voltage driving, the loss is increased and efficiency in the same output is decreased by the time harmonics in inverter output. These are based on the eddy current on stator and the skin effects of rotor bar current induced from time harmonic. The aim of this paper is to estimate the equivalent circuit parameter of squirrel cage induction motor fed from inverter considering this effects.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1249-1254
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• 2013

A torque control algorithm suitable for detecting an open circuit failure in which one of the three phases is unable to supply power to a motor in the permanent magnet synchronous motor is presented in this paper. When the failure occurs in the inverter, the output torque of motor is restricted. A new method which is implemented by using only a processor algorithm internally without any hardware redundancy circuit is proposed. A simulation and experimental study is carried out with a three phase inverter system to show the validity of the proposed method.