• Journal of Power Electronics
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• 제15권1호
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• 품질경영학회지
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• 제19권2호
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• pp.52-62
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• 1991

Consider a class of rank tests for comparing several treatments with a control and discuss some members among the class. New rank test based on orthogonal contrasts is proposed and compared with other well known tests. The approximate powers of the proposed test are also presented through the simulation studies.

• 대한전자공학회논문지TC
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• 제46권2호
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• pp.141-146
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• 2009

본 논문에서는 새로운 고조파 조절 회로를 이용한 Si LDMOSFET 고효율 전력증폭기를 구현하였다. 본 고조파 조절 회로는 2차, 3차 고조파 성분에 대하여 단락 임피던스를 갖으며, 입출력 정합 회로를 설계하기 위하여 사용된다. 제안된 고조파 조절 회로의 효율 개선 효과가 class-F 혹은 inverse class-F 고조파 조절 회로 보다 우수하다는 것을 증명하였다. 또한, 고조파 조절 회로가 출력 정합 회로뿐만 아니라, 입력 정합 회로에도 사용될 경우, 제안된 전력증폭기의 효율은 더욱 더 개선된다. 제안된 전력증폭기의 최대 전력 효율 (PAE)의 측정값은 1.71 GHz의 주파수 대역에서 82.68%이다. Class-F와 inverse class-F 전력증폭기와 비교할 때, 제안된 전력증폭기의 최대 PAE 측정값은 $5.08\;{\sim}\;9.91\;%$ 향상된다.

• Journal of Communications and Networks
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• 제9권3호
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• pp.319-329
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• 2007

This paper presents a price-based quality-of-service (QoS) control framework for two-class network services, in which circuit-switched and packet-switched services are defined as "premium service class" and "best-effort service class," respectively. Given the service model, a customer may decide to use the other class as a perfect or an imperfect substitute when he or she perceives the higher utility of the class. Given the framework, fixed-point problems are solved numerically to investigate how static pricing can be used to control the demand and the QoS of each class. The rationale behind this is as follows: For a network service provider to determine the optimal prices that maximize its total revenue, the interactions between the QoS-dependent demand and the demand-dependent QoS should be thoroughly analyzed. To test the robustness of the proposed model, simulations were performed with gradually increasing customer demands or network workloads. The simulation results show that even with substantial demands or workloads, self-adjustment mechanism of the model works and it is feasible to obtain fixed points in equilibrium. This paper also presents a numerical example of guaranteeing the QoS statistically in the short term-that is, through the implementation of pricing strategies.

• 제어로봇시스템학회논문지
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• 제13권4호
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• pp.385-391
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• 2007

A class D digital audio amplifier with small size, low cost, and high quality is positively necessary in the multimedia era. Since the digital audio amplifier is based on the PWM signal processing, it is improper to analyze the principle of signal generation using linear system theories. In this paper, a class D digital audio amplifier based ADSM (Advanced Delta-Sigma Modulation) is considered. We first model the digital audio amplifier and then explain the operation principle using variable structure control algorithm. Moreover, the ripple signal generated by the hysteresis in the comparator has a significant effect on the system performance. Thus, we present a method to find the magnitude and the frequency of the ripple signal using describing function. Finally, simulations and experiments are provided to show the validity of the proposed methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.234-236
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E inverter is used in this paper The proposed PFM control scheme doesn't used any auxiliary circuit. The proposed control strategy is executed by feeding back the input current. and the Zero-Voltage-Switching (ZVS) is ensured by operating beyond resonant frequency. Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulated results.

• Journal of Power Electronics
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• 제3권3호
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• pp.175-184
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is Introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and also voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E Inverter is used In this paper. The proposed PFM control scheme didn't use any auxiliary circuit. The proposed control strategy is executed by feeding back the Input voltage, and the zero-voltage-switching (ZVS) is ensured by maintaining constant turn-off time of the switch Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulations and experimental results.

• 한국통신학회논문지
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• 제21권3호
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• pp.629-642
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• 1996

ATM switch handles the traffic for a wide range of appliations with different QOS(Quality-of-Service) requirements. In ATM switch, the priority control mechanism is needed to improve effectively the required QOS requirements. In this paper, we propose a priority control mechanism using the cell transfer ratio type and discard threshold in order to archive the cell loss probability requirement and the delay requirement of each service class. The service classes of our concern are the service class with high time priority(class 1) and the service class with high loss priority control mechanism, cells for two kind of service classes are stored and processed within one buffer. In case cells are stored in the buffer, cells for class 2 are allocated in the stored and processed within one buffer. In case cells are stored in the buffer, cells for class 2 are allocated in the shole range of the buffer and cells for class 1 are allocated up to discard threshold of the buffer. In case cells in the buffer are transmitted, one cell for class 1 is transmitted whenever the maximum K cells for class 2 are transmitted consecutively. We analyze the time delay and the loss probability for each class of traffic using Markov chain. The results show that the characteristics of the mean cell delay about cells for class 1 becomes better and that of the cell loss probability about cells for class 2 becomes better by selecting properly discard threshold of the buffer and the cell transfer ratio according to the condition of input traffic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1009-1011
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• 2001

This paper presents a new hybrid control scheme using Active-Clamped Class-E (ACCE) inverter of induction heating(IH) jar for high power applications. The proposed hybrid control scheme has characteristics, which act as class-E inverter at lower switch voltage and ACCE inverter at higher switch voltage than reference voltage of the main switch by feeding back voltage one as well as advantages of conventional ACCE inverter such as zero-voltage switching(ZVS) of the main switch and the reduced switch voltage due to the clamping circuit. Moreover, the proposed control method makes higher output power than conventional ACCE inverter control one since ACCE inverter is operated like class-E inverter at low voltage condition. The principle of the proposed control are explained in detail and the validity of the proposed control scheme is verified through the several interesting simulated and experimental results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.129-132
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• 1999

In this Paper, new congention control schemes using the adaptive rate control for ATM LANs are presented. If is preferable for hosts in LANs to be able to send bursts at the same speed as the interface link speed in a lightly loaded condition, and as the network load increases, to reduce their traffic rate adaptively in order to avaid network congestion. We propose to apply such a rate control concept for two different traffic classed in the ATM LANs. For the first traffic class requiring no bandwidth reservation, i.e, a best effort service class, a combination of the end-to-end adaptive peak rate control with the link-by-link backpressure control is proposed. For the second traffic class, requiring the bandwidth reservation for the burst transmission, i.e. guaranteed burst service class, a combination of he adaptive peak rate control with the fast bandwidth reservation is proposed.