• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권6호
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• pp.1743-1758
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• 2023

Automatic modulation classification is a critical algorithm for non-cooperative communication systems. This paper addresses the challenging problem of closed-set and open-set signal modulation classification in complex channels. We propose a novel approach that incorporates a self-learning filter and center-loss in Deep Residual Shrinking Networks (DRSN) for closed-set modulation classification, and the Opendistance method for open-set modulation classification. Our approach achieves better performance than existing methods in both closed-set and open-set recognition. In closed-set recognition, the self-learning filter and center-loss combination improves recognition performance, with a maximum accuracy of over 92.18%. In open-set recognition, the use of a self-learning filter and center-loss provide an effective feature vector for open-set recognition, and the Opendistance method outperforms SoftMax and OpenMax in F1 scores and mean average accuracy under high openness. Overall, our proposed approach demonstrates promising results for automatic modulation classification, providing better performance in non-cooperative communication systems.

• Journal of Power Electronics
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• 제10권4호
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• pp.365-373
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• 2010

This paper proposes a hybrid single carrier sinusoidal modulation suitable for multiphase multilevel inverters. Multiphase multilevel inverters are controlled by hybrid modulation to provide multiphase variable voltage and a variable frequency supply. The proposed modulation combines the benefits of fundamental frequency modulation and single carrier sinusoidal modulation (SC-SPWM) strategies. The main characteristics of hybrid modulation are a reduction in switching losses and improved harmonic performance. The proposed algorithm can be applied to cascaded multilevel inverter topologies. It has low computational complexity and it is suitable for hardware implementations. SC-SPWM and its base modulation design are implemented on a TMS320F2407 digital signal processor (DSP). A Complex Programmable Logic Device realizes the hybrid PWM algorithm and it is integrated with a DSP processor for hybrid SC-SPWM generation. The feasibility of this hybrid modulation is verified by spectral analysis, power loss analysis, simulation and experimental results.

• 전력전자학회논문지
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• 제17권4호
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• pp.337-344
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• 2012

A matrix converter is used for converting AC/AC power directly. In order to generate sinusoidal input/output waveform in matrix converter, it uses nine bidirectional switches and PWM modulation. This paper presents an analytical averaged loss model of matrix converter with DDPWM(direct duty ratio PWM) and proposes a new switching method for reducing switching losses. A Mathematical loss models with average magnitude of voltage/current are classed as conduction and switching loss. The proposed switching pattern is improved with existing DDPWM. To prove improved efficiency with proposed DDPWM, this paper compares losses between suggested switching pattern and conventional switching pattern using mathematical and simulation method. Each loss types are influenced by environmental factors such as temperature, switching frequency, output current and modulation method.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1914-1920
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• 2014

In this paper, characteristics of blushless direct current (BLDC) motor including core loss are analyzed considering pulse width modulation (PWM) of inverter. Input voltage of BLDC motor due to PWM is calculated considering duty ratio and carrier frequency of inverter in order to control torque or speed of BLDC motor. For the calculation of core loss, the input current with harmonics due to PWM voltage is calculated by using equivalent circuit model of BLDC motor according to switching pattern and carrier frequency. Next, core loss is analyzed by inputting the currents as a source of BLDC motor for FEM. Characteristics including core loss are compared with ones without PWM waveform according to reference speed.

• Journal of Power Electronics
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• 제10권3호
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• pp.277-284
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• 2010

This paper presents a novel hybrid carrier based space vector modulation for cascaded multilevel inverters. The proposed technique inherits the properties of carrier based space vector modulation and the fundamental frequency modulation strategy. The main characteristic of this modulation are the reduction of power loss, and improved harmonic performance. The carrier based space vector modulation algorithm is implemented with a TMS320F2407 digital signal processor. A Xilinx Complex Programmable Logic Device is used to develop the hybrid PWM control algorithm and it is integrated with a digital signal processor for hybrid carrier based space vector PWM generation. The inverter offers less weighted total harmonic distortion and it operates with equal electrostatic and electromagnetic stress among the power devices. The feasibility of the proposed technique is verified by spectral analysis, simulation, and experimental results.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.

• Journal of Power Electronics
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• 제17권6호
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• pp.1413-1421
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• 2017

In order to control the output voltage in a dual active bridge converter, this paper establishes a theoretical inductor current equation for a dual-pulse-width-modulation scheme that ensures low switching loss. It also proposes a modulation strategy that minimizes conduction loss. When compared to the conventional single-pulse-width-modulation strategy, the proposed approach can reduce the inductor current RMS and improve efficiency in the low power region, as verified through simulation and experimental results.

• 한국광학회지
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• 제18권2호
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• pp.93-99
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• 2007

본 논문에서는 주기적으로 분산 값의 부호가 바뀌는(dispersion managed: DM) 선로에서 급작스런 분산 변화로 인한 scattering을 완화시키도록 이득을 공간적으로 변조(gain management: GM)하는 시스템을 제안하고 이에 대한 modulation instability(MI) 변화에 대한 이론적인 분석과 수치해석적인 분석을 보고한다. 연구결과 어떤 경우에도 GM을 가한 시스템이 DM만을 한 시스템 보다 MI 이득의 크기와 cutoff frequency, side band peak모두가 작아짐을 확인하였다. 동일한 광신호 세기에 대해서 MI 이득이 작아지는 것은 four wave mixing 등 광섬유의 비선형 현상을 완화시킴으로써 파장분할다중화 전송의 품질 향상에 도움이 될 뿐 아니라, 솔리톤(soliton)을 이용한 전송에 있어서 하나의 펄스에 더 많은 에너지를 갖게 함으로써 신호대 잡음비를 개선할 수 있음을 의미한다. 본 논문에서는 분산과 이득이 동시에 조절된 선로의 효과를 솔리톤 전송 시스템의 개선된 특성을 편광모드분산(polarization mode dispersion: PMD)가 존재하는 선로에서의 펄스 폭 증가를 통하여 살펴본다.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2168-2180
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• 2014

In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

• Journal of Power Electronics
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• 제13권1호
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• pp.113-121
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• 2013

This paper introduces a simple core loss calculation method for output filter inductor in pulse width modulation (PWM) DC-AC inverter. Amorphous C-core (AMCC-320) is used to analyze the core loss. In order to measure core loss of the output filter inductor and validate the proposed method, a single-phase half-bridge inverter and a calorimeter are used. By changing switching frequency and modulation index (MI) of the inverter, core loss of the AMCC-320 is measured with the lab-made calorimeter and the results are compared with calculated core loss. The proposed method can be easily extended to other core loss calculation of various converters.