• 제어로봇시스템학회논문지
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• 제13권11호
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• pp.1040-1047
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• 2007

This paper presents ripple-free method that can occur in multirate controller design. The conventional multirate input controller has the problem that the ripple occurs in track-following because of chattering phenomenon in control input signal. In order to resolve the problem of rippling, it was proposed to eliminate the ripple phenomenon using feedforward compensator. This paper makes explains problems in conventional ripple-tree multirate controller and introduces a multirate controller design method applying lifting technique based on current estimators in condition space. Using the ripple-tree multirate controller, we show that chattering does not occur in the control input signal through applying the final value theorem from the viewpoint of discrete-time transformation. Also, this study proves that the ripple of the proposed controller decreases with the increase of this sampling frequency and, when sampling frequency is fixed, it decreases with the increase of the control input period.

• Journal of Power Electronics
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• 제16권3호
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• pp.994-1003
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• 2016

Two major obstacles in the utilization of electrical vehicles are their price and range. The collaboration of direct torque control (DTC) with induction motor (IM) is preferred for its low cost, easy implementation, and parameter independency. However, in terms of edges, the method has drawbacks, such as variable switching frequency and undesired current harmonic distortion. These drawbacks result in acoustic noise, reduced efficiency, and electromagnetic interference. A feed-forward approach for stator-flux-oriented DTC with space vector pulse-width modulation is presented in in this paper. The outcome of the proposed method is low current harmonic distortion with fixed switching frequency while preserving the torque performance and simple application feature of basic DTC. The method is applicable to existing and forthcoming IM drive systems via software adaptation. The validity of the proposed method is confirmed by simulation and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.25-28
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• 1989

This paper is to study a modified hysteresis band current control technique for keeping the fixed switching frequency. The control technique is applied to an brushless DC motor(BLDCM). This paper gives an analysis of the modified hysteresis band with isolated neutral case and the PI controller with current limiter in forward loop; their characteristics are studied by simulation. The proposed control technique is implemented by using a microprocessor-based system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.397-401
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• 2004

In this paper, Inverter drives adopting 3-phase and 2-phase SRP-PWM (Separately Randomized Pulse Position PWM) with fixed switching frequency is proposed. In the proposed SRP-PWM scheme, each of 3 or 2 phase pulses Is located randomly in each switching interval. The experimental results show that the voltage / current harmonics and the switching noise harmonics are spread to a wide band area. Also, the performance of the 3-phase SRP-PWM and the 2-phase SRP-PWM are compared to each other. In result, the speed response is nearly similar to each other from the viewpoint of the v/f constant control.

• 전력전자학회논문지
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• 제23권6호
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• pp.415-423
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• 2018

This study uses a level selection algorithm with fixed sampling frequency for modular multilevel converter (MMC) systems. Theoretically, the proposed method increases the level infinitely while the sampling time remains the same. The proposed method called cluster stream buffer (CSB) consists of several clusters, wherein each cluster is composed of 32 submodules that depend on the level of the submodules in the MMC system. To increase the level of the MMC system, additional clusters are used, and the sampling time between clusters is determined from the sampling time between levels needed for utilizing the entire level from the MMC system. This method is crucial in the control of MMC-type HVDC systems because it improves scalability and precision.

• International Journal of Advanced Culture Technology
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• 제4권4호
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• pp.30-37
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• 2016

In this paper, the method of controlling the clock that is inputted on the hardware from the application, and the hardware design method are to be proposed. When the hardware is synthesized to the Field Programmable Gate Array(FPGA), the input clock is fixed, and when the input clock is changed, the synthesis process must be passed again to require more time. To solve this problem, the Mixed-Mode Clock Manager(MMCM) module is mounted to control the MMCM module from the application. The controlled MMCM module controls the input clock of the module. The experiment was process the Neural Network algorithm in the x86 CPU and SIMT based processor mounted the FPGA. The results of the experiment, SIMT-based processors, the time that is processed at a frequency of 50MHz was 77ms, 100MHz was 34ms. There was no additional synthesis time due to a change of the clock frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.364-368
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• 1999

This paper suggests switching regulator technique to overcome the drawback of conventional variable linear power supply. Switching regulator technique can eliminate the extremely lossy operation and reduce the size and weight of variable linear power supply and provide nearly constant output power over the majority of output voltage range. The topology of variable switched mode power supply is employed active clamp forward converter with a current doubler rectifier and by using control of variable-frequency together with control of fixed-frequency, output voltage can be controled. Equivalent circuits pertinent to each operational mode of converter are derived, and an experimental 20V, 50A converter was designed and built. The converter operates from an output voltage of zero to 25 V, under 100 kHz switching frequency.

• ETRI Journal
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• 제31권6호
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• pp.755-764
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• 2009

This paper presents a switched self-biasing and a tail current-shaping technique to suppress the 1/f noise from a tail current source in differential cross-coupled inductance-capacitance (LC) voltage-controlled oscillators (VCOs). The proposed LC VCO has an amplitude control characteristic due to the creation of negative feedback for the oscillation waveform amplitude. It is fabricated using a 0.13 ${\mu}m$ CMOS process. The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 4.85 GHz carrier frequency, while it draws 6.5 mA from a 0.6 V supply voltage. For frequency tuning, process variation, and temperature change, the amplitude change rate of the oscillation waveform in the proposed VCO is 2.1 to 3.2 times smaller than that of an existing VCO with a fixed bias. The measured amplitude change rate of the oscillation waveform for frequency tuning from 4.55 GHz to 5.04 GHz is 131 pV/Hz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.525-527
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• 1996

Hysteresis current control is one of the simplest techniques used to control currents for high speed drive systems, because of its simplicity of implementation, fast current control response, and inherent peak current limiting capability. However the conventional fixed-band hysteresis control has a variable switching frequency throughout the fundamental period, and consequently the load current harmonics spreaded on the wide frequency range. In this paper, a simple, novel alterative approach is proposed for a variable-hysteresis band current controller which uses feedback techniques to achieve constant switching frequency with good dynamic response. The method is easily implemented in hardware, the resultant controller is easily tuned to a particular load, and has good immunity to variation in PV parameter and dc supply voltage.

• 한국지능시스템학회논문지
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• 제15권2호
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• pp.135-142
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• 2005

본 논문에서는 변하는 주기 기준 신호를 추종하기 위한 광학 디스크 드라이브의 적응 반복 제어 기법을 제시한다. 주기가 알려진 주기적인 외란은 반복 제어 개념을 이용하면 충분히 제거할 수 있다. 광학 디스크 드라이브는 다양한 속도를 지원하기 때문에 변하는 주기의 외란을 가진다. 기준 주기 변화를 추종하기 위해 샘플링 주파수를 변화시키는 반복 제어를 기초로 하여 주기가 변하는 외란을 다루기 위한 적응 반복 제어를 제안한다. 제안한 제어 기법은 반복 제어기와 주파수 발생기고 구성된다. 전자는 외란 주파수의 고정 배수에서 동작하는 가변 샘플러를 사용하고 후자는 외란 주파수에 따라 변하는 샘플링 주파수를 발생한다. 광학 디스크 드라이브 제어 대한 실험 결과에서 제안한 기법의 우수성과 랜덤 탐색 시간의 개선을 보인다.