Time filter

Source Type

Wang X.-X.,Beihang University | Wang Y.,Beihang University | Wang X.-C.,Beihang University | Wang A.-M.,Hong Feng Control Company Ltd of San Jiang Astronautics | Peng Z.-Q.,Hong Feng Control Company Ltd of San Jiang Astronautics
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

Fiber optic current transducer (FOCT) overcomes the weakness of electromagnetic current transducer in transient current response and meets the demands of accurate current measurement of modern power system in real-time. Experimental research on FOCT's dynamic character is done to ensure the system dynamic characteristics meet the practical requirements. A dynamic model is established based on the working principle of FOCT, and its transfer function is also deduced, so that the dynamic characteristics of FOCT can be evaluated. Furthermore, the relationship between several important parameters in the dynamic model and the closed-loop bandwidth is analyzed; the experiment result shows that system bandwidth is inversely proportional to the length of delay fiber optic cable and proportional to the gain of forward channel. And the bandwidth is proportional to important parameters of the gain of forward channel, such as gain adjustment coefficient, interference intensity, and sampling numbers. In order to guarantee the dynamic performance in the FOCT's designing and using, theoretical basis and reference are provided in the choice of length of delay fiber optic cable and the parameters of the gain in forward channel.


Wang X.,Beihang University | Wang Y.,Beihang University | Li C.,Power Electronic Institution | Qin Y.,Beihang University | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2013

The fiber quarter-wave plates are an important part of fiber-optic current transformers (FOCT). In order to decrease the error caused by the quarter-wave plates on the ratio under the varying temperature environments, more accurate relationship between the temperature and the phase delay of fiber quarter-wave plates is required. Based on the intensity method, a measuring way of the temperature dependence of the phase delay of quarter-wave plates is put forward. It is applied to measure fiber quarter-wave plates in real time and continuously. A mathematical model of the test systems is established by using Jones matrix, and the temperature characteristics of the quarter-wave retarder are tested. The experimental results show that: the relationship between the temperature and the phase delay is linear, and the temperature coefficient of inland quarter-wave plates is much larger than that of the abroad ones; in the temperature self compensation technology of ratio error of FOCT, the smaller the temperature coefficient of the phase delay of quarter-wave plates is, the higher the self compensation limit precision is and the wider the original phase retardation is.


Wang X.,Beihang University | Zhang M.,Beihang University | Li C.,Beihang University | Wang A.,Hong Feng Control Company Ltd of Sanjiang Astronautics | Peng Z.,Hong Feng Control Company Ltd of Sanjiang Astronautics
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2013

It is difficult to verify the dynamic model of the digital closed-loop fiber optic gyroscope (FOG) due to the limitation of the turntable's output frequency. To solve this problem, a novel evaluation method based on the magneto-optic Faraday effect is developed. The Sagnac phase difference is substituted by the Faraday phase difference induced by alternating current (AC) to eliminate the limitation of stimuli. Based on the dynamic system model of the FOG, the relationship between bandwidth and the parameters is analyzed and the system transfer function is obtained. The frequency response characteristic of the gyro is simulated via the obtained transfer function. Finally, some experiments are conducted to investigate the dynamic performance of the gyro. The experimental data are in agreement with the theoretical findings, which demonstrates the correctness of the dynamic model and provides the groundwork for optimizing dynamic characteristics.


Wang X.-X.,Beihang University | Zhang M.,Beihang University | Li C.-S.,Beihang University | Yang H.,Beihang University | And 3 more authors.
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2014

The frequency response scale in the dynamic performance test of the fiber optical gyroscope's (FOG) is limited by the output frequency of the turntable. In this paper, a novel evaluation method to evaluate frequency characteristic of the FOG is presented based on the magneto-optic Faraday effect to eliminate the limitation. The Sagnac phase diffidence induced by rate is substituted by the Faraday phase diffidence induced by a current. Then the validly of the proposed method to evaluate frequency characteristic of fiber optic gyroscope is analyzed and theoretically verified. The evaluation system is implemented based on the proposed evaluation method, and it can imitate the signal process of FOG. The experimental result shows that the evaluated FOG has a bandwidth of 9 kHz. The proposed evaluation method is capable of test the high dynamic performance of the FOG, which benefits study of the dynamic performance of the FOG.

Loading Hong Feng Control Company Ltd of San Jiang Astronautics collaborators
Loading Hong Feng Control Company Ltd of San Jiang Astronautics collaborators