• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.172-178
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• 1986

The recent interest in the design of filters is motivatied by the fact that such filter can be fully integrated using standard metal-oxide-semiconductor processing technology. This is due to replacing all the resistors in the active RC filter network by the switched capacitors. The voltage gain of a SC filter depends only on the rations of capacitance and these ratios can be obtained and maintained to high accuracy. Therefore, it is known that a switched capacitor is much better than a resistor in temperature and linearity characteristics. This paper proposed a programmable SC filter and proved the fact that ${omega}_0$ Q and G of this circuit can be controlled by digital signal. Experiments show that SC filter remains the low sensitivities but it can't avoid little influence of parasitic capacitance. As the transfer characteristic of the SC filter is varied with sampling frequency and resistor array, SC filtering technigue can be applied for digital processing, speech analysis and synthesis and so on.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1159-1168
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• 1993

The Switched-Capacitor Integrator(SCI) is a basic building block of Switched-Scpacitor Filter(SCF). But owing to the errors from the finite gain and bandwidth of op-amp on SCI, the most of SCP are limited to their applications. Although many of the compensation methods developed for active RC filters can be directly adapted to SCF, this is not true for the analysis of the effects of the op-amp dynamics on the filter response. The effect of finite op-amp gain is similar to the active RC filters. But SCF is more toter-ant of the finite op-amp bandwidth. In this paper, we have considered the errors of the finite gain and bandwidth of op-amp on SCI , and presented the simple and effective methods of compensating the errors of SCI due to the finite op-amp gain using the buffer circuit.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.5
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• pp.69-74
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• 1985

In this paper five-order Butterworth Low pass active RC filter is designed by using FDNR (Frequency Dependent Ncgative Resistor) Method from LC ladder filter having the lowest sensitivity. In process of Transformation to SCF (Switched Capacitor Filter) from active RC filter, Bilinear Z Transfomation method is utilized. By the design of SCF using the bilinear Z transform method the problem of aliasing can be avoided, but the frequency distortion is generated. The transformation from analog filter to digital filter is not equal in the region of the cut off frequency caused by this effect. Avoiding the problem of this effect, we use prewarping method. The result shows that the prewarped SCF makes more remarkable improvement in the frequency distortion than SCF which is transformed by using bilinear Z transform.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.4
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• pp.23-30
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• 1980

All the resistors in the active RC filter networks cab be replaced by the switched capaciters, The swiftched capacitor is much bet tar than a resistor in temperature and linearity characteristics, and the former can be fabricated on the much smaller silicon area than the latter. In this paper, it is given the generaliged design method of the active SC filter from the active RC filter using Bilinear Z-transformatirm. SC filtering techniques using Bilinear Z-transform enable us to realize the FDNR and Gyrator filters which could not be realized by the exsisting designs 1 and to utilize the processing of signals at much higher frequencies than the conventional design method. Experiments show that the response of the active SC filter is similiar to that of its prototype active RC filler.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1010-1011
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• 2006

A new soft switched active snubber circuit is proposed to achieve zero voltage and zero current switching for all the switching devices in PWM DC-DC converters. The unique location of the snubber capacitor and inductor ensures low current/voltage stresses and commutation losses. With a saturable reactor, the conduction loss of the auxiliary switch could be further minimized. A boost converter adopting this technique is presented as an example, to illuminate its operation principles and derive the design procedures. Simulation and hardware implementation have been made to validate its performance. Some other basic PWM DC-DC topologies using the proposed snubber have also been given.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.265-267
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• 2008

As generally recognized, the driving performance of a SRM at higher speed will be degraded due to the effects of back electromagnetic force (EMF). This phenomenon can be improved via voltage boosting. So in this paper an improved converter of enhancing the performance for four-phase switched reluctance motor (SRM) is proposed. By using one additional capacitor and switches, an extra controllable boosted voltage can be produced during the rise and fall periods of a motor phase current. Then this active boosted voltage can reduce the effect of EMF on the current, particularly at high speeds. The attractive features of the proposed converter are as follows: obtaining boosted voltage to improve performance of SRM with same numbers of switch and diode as asymmetric converter, having higher control flexibility and capability of boosting voltage compared with passive boosting converters, possessing lower cost and simple control in comparison with existing active boosting converters. The performances of the proposed circuit are verified by the simulation and experiment results.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1819-1829
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• 2018

A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.

• Journal of Power Electronics
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• v.7 no.3
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• pp.246-256
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• 2007

In this paper, a novel type auxiliary active edge resonant snubber assisted zero current soft switching pulse modulation Single-Ended Push Pull (SEPP) series load resonant inverter using IGBT power modules is proposed for cost effective consumer high-frequency induction heating (IH) appliances. Its operating principle in steady state is described by using each switching mode's equivalent operating circuits. The new multi resonant high-frequency inverter with series load resonance and edge resonance can regulate its high frequency output power under a condition of a constant frequency zero current soft switching (ZCS) commutation principle on the basis of the asymmetrical pulse width modulation (PWM) control scheme. Brand-new consumer IH products using the proposed ZCS-PWM series load resonant SEPP high-frequency inverter using IGBTs is evaluated and discussed as compared with conventional high-frequency inverters on the basis of experimental results. In order to extend ZCS operation ranges under a low power setting PWM as well as to improve efficiency, the high frequency pulse density modulation (PDM) strategy is demonstrated for high frequency multi-resonant inverters. Its practical effectiveness is substantially proved from an application point of view.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.261-265
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• 2001

In this paper, a current-source type parallel indudor compensated load resonant high-frequency soft switching inverter using IGBTs for driving the newly-produced silent discharge type ozone generating tube and excimer lamp for UV generation which incorporate a single switched capacitor resonant snubber between the port in DC busline side is presented, together with its pulse modulated unique output power regulation characteristics.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.481-484
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• 2003

A strategy for a torque ripple reduction drive of single-phase SRM with high power factor is proposed. The drive for switched reluctance motor (SRM) is presented to achieve sinusoidal, near unity power factor input current with low torque ripple. The proposed SRM drive has no additional active switch. And a single-stage approach, which combines a DC link capacitor used as dc source and a drive used for driving the motor into one power stage, has a simple structure and low cost. The characteristics and validity of the proposed circuit is discussed in depth through the experimental results.