• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2891-2903
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• 2020

Phase-generated carrier (PGC) demodulation algorithm is the main demodulation methods in Fiber-optic interferometric sensors (FOISs). The conventional PGC demodulation algorithms are influenced by the carrier phase delay between the interference signal and the carrier signal. In this paper, an automatic carrier phase delay synchronization (CPDS) algorithm based on orthogonal phase-locked technique is proposed. The proposed algorithm can calculate the carrier phase delay value. Then the carrier phase delay can be compensated by adjusting the initial phase of the fundamental carrier and the second-harmonic carrier. The simulation results demonstrate the influence of the carrier phase delay on the demodulation performance. PGC-Arctan demodulation system based on CPDS algorithm is implemented on SoC. The experimental results show that the proposed algorithm is able to obtain and eliminate the carrier phase delay. In comparison to the conventional demodulation algorithm, the signal-to-noise and distortion ratio (SINAD) of the proposed algorithm increases 55.99dB.

• 대한전자공학회논문지
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• 제8권3호
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• pp.27-32
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• 1971

본논문은 초광대역AM파전송에 있어서 상·하측대파의 진폭 및 위상의 변화분이 반송파에 관하여 대칭일 경우와 기대칭일 경우에 발생하는 AM파의 진폭일그러짐을 해석하였다. AM파의 전송에서 AM파의 상·하측대파의 진폭변화분의 반송파에 관하여 대칭이고 상·하측대파의 위상변화분이 반송파에 관하여 기대칭일 경우에는 진폭일그러짐이 발생하지 않음이 밝혀졌다.

• 전력전자학회논문지
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• 제20권4호
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• pp.375-387
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• 2015

This study investigates an economic and highly efficient power-converter topology and its modulation scheme for 60 kW rapid EV charger system. The target system is a three-phase three-switch buck-type rectifier topology. A new carrier-based PWM scheme, which is characterized by simple implementation using logic gates, is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state to produce the same effective current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier with high-quality AC input and capacitor ripple current.

• Journal of Power Electronics
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• 제16권1호
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• pp.388-397
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• 2016

An error-compensated pulse width modulator (ECPWM) is proposed to improve the baseband harmonic performance and the switching loss of voltage source inverters (VSIs). Selecting between harmonic distortion and switching loss is a design tradeoff in the conventional space vector pulse width modulation. In this work, an accumulated difference in produced and desired phase voltages is considered to adjust the reference signal. This mechanism can compensate for the voltage error in the previous carrier period. With error compensation every half-carrier period, the proposed ECPWM allows one-half reduction in carrier frequency without scarifying baseband harmonic distortion. The proposed modulator is applied to a three-phase VSI with R-L load and a motor-speed-control system for experiments. The measured efficiency and operating temperature of switches confirm the effectiveness of the proposed scheme.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권7호
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• pp.352-360
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• 2003

This paper deals with a simple method in order to analyze and compare the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components becomes different according to the multi-carrier Pulse Width Modulation(PWM) techniques, the modulation index($M_i$) and the switching frequency The previous papers analyzed the harmonic characteristics from the viewpoint of the space voltage vector. Hence, the calculation of the harmonic vector becomes more difficult and complex in 4-level or over 5-level. However, the proposed method has reduced an amount of calculation and simplified the process of it, using the relationship between the reference voltage and the output phase voltage to the load neutral point. It is applied to the 5-level cascade inverter and the harmonic characteristics for each multi-carrier PWM technique are compared through the simulation.

• Journal of Power Electronics
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• 제18권2호
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• 전력전자학회논문지
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• 제8권3호
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• pp.292-298
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• 2003

교류전동기의 가변속 운전에 사용되는 삼상 인버터에는 두개 또는 세개의 전류센서가 장착되며 이를 이용하여 삼상 교류전류를 측정한다. 전류센서의 갯수를 줄이기 위하여 개발된 것이 직류링크에 한개의 전류센서로 직류전류를 측정하고 측정된 전류 값과 스위칭 상태로부터 삼상 교류전류를 추정하는 방법이다. 전류를 정확히 측정하려면 스위칭 상태가 최소 측정시간 이상 유지되어야 하며, 이를 위한 펄스폭 조정과 이에 따른 전압 왜곡의 보상 방법이 연구되어 왔다. 그러나 기존에 발표된 방식들은 공간벡터 전압변조법에는 적합하지만 산업체에서 널리 쓰이는 펄스폭 변조 방식인 삼각파 비교법에 적용하기에는 어려운 면이 많다. 본 연구에서는 삼각파 비교법에 적합한 전류 측정 방식과 전압왜곡 보상 방식을 제안하고 이의 타당성을 실험을 통하여 검증하였다.

• 전력전자학회논문지
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• 제17권6호
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• pp.478-485
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• 2012

In this paper, a new PWM method is proposed to reduce the input current harmonics of 3 phase PWM rectifier. In the conventional carrier comparison PWM method, a triangular wave is generally used as the carrier wave. However, the large d-axis current ripple by the triangle carrier wave may be a source of large input current THD(Total Harmonic Distortion). In this paper, a new carrier comparison PWM method with saw tooth wave is proposed. Depending on the sector where the voltage command vector places, one of the rising or falling saw tooth wave is selected. To reduce the switching losses of the saw tooth carrier PWM, the discontinuous PWM is also presented. The proposed PWM method can reduce the d-axis current ripple as well as the switching losses. The performance of the conventional and proposed PWM methods is verified by the simulation and experimental results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.247-250
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• 2002

Data embedding has recently become important for protecting authority. In this paper, we Propose a robust data embedding technique for images. Our techniques are based on the convolution between message image and a random phase carrier. We add extra bits with carrier image to improve precision of detecting rate, moreover, we use block by block based cyclic correlation for the compensation of distortion. In experiment, we show that the proposed a1gorithm is robust to Stirmark 3.1. attacks.

• ETRI Journal
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• 제33권6호
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• pp.841-848
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• 2011

A signal-to-noise ratio (SNR) enhancement algorithm using multiple chirp symbols with clock drift is proposed for accurate ranging. Improvement of the ranging performance can be achieved by using the multiple chirp symbols according to Cramer-Rao lower bound; however, distortion caused by clock drift is inevitable practically. The distortion induced by the clock drift is approximated as a linear phase term, caused by carrier frequency offset, sampling time offset, and symbol time offset. SNR of the averaged chirp symbol obtained from the proposed algorithm based on the phase derotation and the symbol averaging is enhanced. Hence, the ranging performance is improved. The mathematical analysis of the SNR enhancement agrees with the simulations.