• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.173-183
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• 1998

In this paper, an auto-tuning method for fuzzy controller's membership functions based on the neural network is presented. The neural network emulator offers the path which reforms the fuzzy controller's membership functions and fuzzy rule, and the reformed fuzzy controller uses for speed control of induction motor. Thus, in the case of motor parameter variation, the proposed method is superior to a conventional method in the respect of operation time and system performance. 32bit micro-processor DSP(TMS320C31) is used to achieve the high speed calculation of the space voltage vector PWM and to build the self-learning fuzzy control algorithm. Through computer simulation and experimental results, it is confirmed that the proposed method can provide more improved control performance than that PI controller and conventional fuzzy controller.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.2
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• pp.69-76
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• 2002

To obtain a high performance in a vector controlled induction motor, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantage with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations and experimentals.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.464-466
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• 2001

The advantage of the squirrel cage induction motor is the brushless rotor. This advantage for operation and maintenance turns out to be a disadvantage for the detection of the cage rotor bar and endring defects, which means that the detection of cage faults is due to the measurement and analysis of only the stator input signals. The monitoring task in an inverter drive is complicated mainly because the voltage and current waveforms are nonsinusoidal and the high dv/dt values from fast switching inverterd distort the measurements. in this paper, we are going to discuss the detection method of broken rotor bar of squirrel cage induction motor by the motor current signal analysis(MCSA).

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.230-233
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• 1998

The conventional PI controller are fragile in parameter variation and load-variation. Therefore, in this paper, a speed control algorithm based on the Fuzzy PI controller is proposed for the high performance speed control of a voltage-source inverter to drive 3-phase induction motors. The computer simulation results show that the proposed controller are more excellent control characteristics than conventional PI controller in transient-state and steady-state response.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.117-125
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• 1998

In this paper, in order to develop the three phase GTO CSI of high efficiency 1M drive with low loss commutation and snubber energy, we studied the energy recovery circuit to recover stored energy in clamping capacitor and DC link inductor(VCC-l and VCC-2), and snubber capacitor(VCC-3). By using an induction motor as the load of inverter, experimental results show that dissipated DC power is decreased and capacitor voltage Vc is effectively suppressed by VCC-2 and VCC-3 system, and the validity of VCC-3 system with low loss commutation and snubber energy is proofed.roofed.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.73-75
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• 1998

Electromagnetic forces as a source of vibration and noise are analyzed and compared for an induction motor with different rotor slot number each other which drive high speed trains. Time stepped finite element method is used to analyze electromagnetic field considering the voltage harmonics supplied from a inverter. As a result, a rotor slot number is determined to reduce the harmonics of electromagnetic forces.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.240-243
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• 1995

This paper deals with the high efficiency drive of a vector controlled inverter fed induction motor system for electric vehicles. The loss equation is derived from the voltage equations in synchronously rotating reference frame. The ratio of the d-axis and q-axis component currents should be maintained constant to maximize the efficiency at a specified speed. Digital simulations are curried out and the results are compared with those of the conventional constant flux control.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.546-555
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• 2001

In this paper filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives are presented. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections ringing and the dv/dt, di/dt, at the motor terminals. Specially the output filter is used to limit the rate of the inverter output voltage and reduce common mode noise to the motor, The performance of the output filter is evaluated through simulations and experiment on PWM inverter-fed AC motor drive. An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board Finally, experimental result shows inverter output filter reduces more common mode voltage than low pass filter also reduce overoltage and ringing at the motor terminal.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.131-137
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• 2005

The purpose of this paper is to evaluate the axial magnetic flux measurement could be used as a tool of the condition monitoring system for the induction motor and to develope the diagnostic algerian for the electric motors. The magnetic leakage flux signal is captured by the flux coil located at the end of motor without the disturbance of the operation. And the signal is analyzed both time and frequency bases to detect the failure of the motor. Specific signature can be described in time and frequency domain for each faults of the motor. The spectrum of the signal was found more useful for the monitoring purpose. The supply voltage imbalance and tin to turn failure of the stator winding could be detected by analysing the specific sidebands of the axial flux and sideband of the rotor bar pass frequency with the high resolution spectrum. The goal of this study verity that the axial flux measurement for the induction motor is a powerful tool for the diagnostic method and develope the algorithm to detect the fault.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.535-540
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• 1998

This paper discusses a triple stage current source GTO inverter system for high power motor drives. The energy rebound circuit of the triple stage inverter not only controls the spike voltage of the GTO inverter but also facilitates PWM control of the thyristor rectifier operated at unity fundamental input power factor. Based on Pspice simulation and experiments, the principles and PWM pulse pattern for removing specific lower harmonics in the inverter's output current are discussed in detail.