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- 저자 : Xiaochun Zhong (검색결과 2 건)
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Self-adjusting strategy based on rotating injection for sensorless control of high-power PMSM drives
Xiaofan Wang,Xiaochun Fang,Zhi Wang,Zhihong Zhong,Yizhi Wang,Fei Lin,Zhongping Yang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
As a sensorless control method suitable for permanent magnet synchronous motor (PMSM) at lowspeed, rotating high-frequency injection method will face some special problems in high power applications. On the one hand, the low switching frequency limits the injected signal frequency, which is very close to the fundamental frequency. On the other hand, under heavy load conditions, the fundamental current amplitude is several hundred times of the negative sequence current. This will result in difficulty in signal extraction. In this paper, current spectrum is analyzed quantitatively based on the parameters of PMSM drive for rail vehicles, which illustrates the limitations of conventional bandpass filters. A method based on self-adjusting filter is proposed. The negative sequence current is successfully extracted, and the precise rotor position is obtained under the condition of variable speed and variable load. Based on a fullscale test platform the effectiveness of the proposed method is proved.
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The Cement Content Measurement of Cement Mixing Piles with EDTA Titration Method
Fuhai Zhang,Lei Zhang,Liguo Yang,Tugen Feng,Lei Chen,Xiaochun Zhong 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11
The uniformity of cement mixing piles is visually tested on the drilled core samples, significantly relying on experience and extremely inaccurate. The cement content of core samples is an important parameter to quantify the uniformity of cement mixing piles. However, there were no well-accepted methods of testing the cement content of core samples. EDTA titration method is widely used as an effective way to test the cement content of cement-stabilized soil in highway subgrade. However, the cement mixing piles cannot be drilled until 28 days after construction, which causes remarkable change of water content and cement hydration during this period. In addition, factors affecting the EDTA titration results should be investigated before standard EDTA titration curves are constructed. In this paper, effects of different factors including curing method, curing period, soil type, content of water glass, and cement type, on EDTA titration testing results were investigated. It is found that cement type and soil type will significantly affect the test result. It is critical to keep the curing environment and soil unsieved before testing. Water glass will reduce the EDTA solution consumptions at early stages of curing. The EDTA titration results are verified by the proposed density estimation method.
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