• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1484-1488
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• 2009

This paper analyzes the noise reduction of traction motor for rolling stock. Nowadays, rolling stock becomes a attractive transportation as a friendly environment transportation. And this paper showed that vibration noise of motor coil by inverter switching frequency. That noise has influence on passenger. It is important that noise reduction for passenger in the rolling stock. In this paper, it shows that effect of variable switching frequency of propulsion inverter for noise reduction.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.37-38
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• 2010

For MHz-class high frequency inverter in wireless power transfer applications, the voltage/current surges can be occurred in power stage when driving on the inverter. And also, the high-frequency oscillations can be produced at a high switching frequency due to the parasitic elements. The voltage and current stresses of the switching devices lead to the switching losses. The efficiency of the high frequency inverter will be reduced. And the inverter circuit with the sudden voltage and current fluctuations also generates the noise such as the EMI. Zero voltage, zero current switching technique can be used to reduce the switching loss and the noise. The high power density and high efficiency can be obtained. In this paper, the high-frequency inverter for short-range wireless power transfer applications was discussed. The feasible inverter circuit is analyzed in the circuit operating characteristics and the results are verified by the simulation.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.193-199
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• 1997

Until now, environmental problem has become more and more serious, and acoustic noise is one of environmental pollutions. For many years, ANC(Active Noise Control) has been made to reduce this noise. In this paper, active silencer using switching method is studied. This silencer is composed of single-phase full bridge inverter to drive cancelling loudspeaker. The inverter is controlled to reduce noise by ramp comparison control method. At the vacuum cleaner, noise control with FFCS(Feed-Forward Control Structure) is applied and geometric arrangement is replaced to avoid unstability of FFCS.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.271-276
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• 2021

Arc fault detector based on multilevel DWT with analysis of high-frequency noise components over 100 kHz is proposed in this study to improve the performance in detecting serial arcs and distinguishing them from inverter noise in PV systems. PV inverters generally operate at a frequency range of 20-50 kHz for switching operation and maximum power tracking control, and the effect of these frequency components on the signal for arc detection leads to negative arc detection. High-speed ADC and multilevel DWT are used in this study to analyze frequency components above 100 kHz. Such high frequency components are less influenced by inverter noise and utilized to detect as well as separate DC series arc from inverter noise. Arc detectors identify the input current of PV inverters using a Rogowski coil. The sensed signal is filtered, amplified, and used in 800kSPS ADC and DWT analysis and arc occurrence determination in DSP. An arc detection simulation facility in UL1699B was constructed and AFD tests the proposed detector were conducted to verify the performance of arc detection and performance of distinction of the negative arc. The satisfactory performance of the arc detector meets the standard of arc detection and extinguishing time of UL1699B with an arc detection time of approximately 0.11 seconds.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.761-767
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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 will be examined. 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. Therefore, filtering techniques are investigated to reduce the motor terminal overvoltage, ringing, and EMI noise in inverter fed ac motor drive systems. The output filter is used to limit the rate of the inverter output voltage and reduce EMI(common mode noise) to the motor. The performance of the output filter is evaluated through simulations (PSIM) and experiment on PWM inverter-fed ac motor drive(3phase, 3hp(2.2kw), input voltage 220/380V, induction motor). An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board. Finally, experimental results showed that the inverter output filter reduces more CM noise than the LPF(low pass filter) and reduce overvoltage and ringing at the motor terminal.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.111-117
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• 2008

Generally, speed control for Induction motor widely used in industrial field is accomplished by commercial inverter. Induction motor driven by commercial inverter causes the micro surge voltage because of high speed switching of inverter. Micro surge brings about not only the breakdown of motor but also noise in PLC control system. And they court the enormous interference in activity for production. In this paper, we suggest the suppressible countermeasure for the breakdown of motor after the consideration of productive mechanism about micro surge. Experiment is performed by inverter with LCR filler in its output terminal. As a result, we confirmed that micro surge voltage is reduced. And the suppressible countermeasure for the noise of PLC control system is suggested by theoretical consideration.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.742-745
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• 2005

This paper describes a simple pseudo-random carrier modulation technique for the acoustic noise reduction of the three phase multi-level inverter based motor drives. The proposed method generates a new pseudo-random carrier by randomly synthesizing a carrier with fixed frequency and a carrier with opposition phase. To confirm the validity of the proposed method, a 130v three-phase multi-level inverter was Implemented and tested. The experimental results show that the output line voltage and acoustic noise harmonics spectra of an inverter have broadening effect of harmonics, as only simple synthesis of fixed frequency carries.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.309-312
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• 2002

In this paper, we discuss the design of high gain low noise amplifier by using the 0.2sum CMOS technology. A cascode inverter is adopted to implement the low noise amplifier. The proposed cascode inverter LNA is one stage amplifier with a voltage reference and without choke inductors. The designed 2.4GHz LNA achieves a power gain of 25dB, a noise figure of 2.2dB, and power consumption of 255㎽ at 2.5V power supply.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.200-207
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• 2000

Recently, it is increased to apply the inverter system to household electrical appliances, especially in the air c conditioners, refrigerators and washing machines, to reduce the power consumption and the acoustic noise by t the low speed operation, and to make their functions more comfortable for human beings. For the inverter s systems, however, it is highly required to reduce the undesirable electromagnetic noise and psychoacoustic n noise generated by PWM for variable speed operation. In this paper, the electromagnetic noise for the d detenninistic PWM and random PWM for the reciprocating compressors driven by the brusWess dc motor was a analyzed. It was also verified through the experiment that the elt'Ct$\tau$omagnetic noise was reduced and the s sound quality was improved by applying the random PWM.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.36-44
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• 2006

In general, the generated harmonics and noise of the PWM inverter are affected by PWM switching method, switching frequency, dv/dt and di/dt. Since multilevel inverters are often applied to the high power system, and operates with low switching frequency, theyproduce large size of harmonic contents and noise. Thus it is necessary to install output filters in the multilevel inverter. In this paper a filter design approach for the harmonic and noise reduction the three phase induction motor driving system using H-bridge 7-level inverter system is presented. The passive filter that has low cost and simple structure and can effectively reduce harmonics and noise, is designed and applied to the three phase induction motor drive having multilevel inverter system. The designed system is implemented and verified by simulation and experiments.