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Wang, Guoning,Du, Xiong,Shi, Ying,Tai, Heng-Ming,Ji, Yongliang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Frequency coupling in the phase domain is a recently reported phenomenon for phase locked loop (PLL) based three-phase grid-inverter systems. This paper investigates the mechanism and stabilization method for the frequency coupling to the stability of grid-inverter systems. Self and accompanying admittance models are employed to represent the frequency coupling characteristics of the inverter, and a small signal equivalent circuit of a grid-inverter system is set up to reveal the mechanism of the frequency coupling to the system stability. The analysis reveals that the equivalent inverter admittance is changed due to the frequency coupling of the inverter, and the system stability is affected. In the end, retuning the bandwidth of the phase locked loop is presented to stabilize the three-phase grid-inverter system. Experimental results are given to verify the analysis and the stabilization scheme.
Guoning Wang,Xiong Du,Ying Shi,Heng-Ming Tai,Yongliang Ji 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Frequency coupling in the phase domain is a recently reported phenomenon for phase locked loop (PLL) based three-phase grid-inverter systems. This paper investigates the mechanism and stabilization method for the frequency coupling to the stability of grid-inverter systems. Self and accompanying admittance models are employed to represent the frequency coupling characteristics of the inverter, and a small signal equivalent circuit of a grid-inverter system is set up to reveal the mechanism of the frequency coupling to the system stability. The analysis reveals that the equivalent inverter admittance is changed due to the frequency coupling of the inverter, and the system stability is affected. In the end, retuning the bandwidth of the phase locked loop is presented to stabilize the three-phase grid-inverter system. Experimental results are given to verify the analysis and the stabilization scheme.
Bo Jiang,Xuewen Hu,Guoning He,Huan Peng,Haibo Wang,Yazheng Liu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
In this paper, the microstructures and properties of hot rolled ultra-low carbon steel sheet produced by different compact stripproduction (CSP) processes were investigated. The softening mechanism was also discussed and the control strategy wasproposed in order to obtain optimum properties. Result showed that the average ferrite grain sizes of austenite rolling sheetand multiphase rolling sheet were 31.0 μm and 74.6 μm, respectively. The sheet after austenite rolling had a slightly higheryield and tensile strength while had a 6.3% higher elongation than that of the sheet after multiphase rolling. The higher dislocationin the sheet after multiphase rolling increased the strength while decreased the elongation. The softening mechanismof the sheet after multiphase rolling was the coarsening of ferrite grain. The combined role of {001} and {111} orientationresulted in a slight increase of the r and ̄rvalue in the sheet after multiphase rolling. It was a wise choice to conduct rollingat the Ac1temperature in CSP process to increase the grain size and decrease the dislocation density. Then, the strength ofthe sheets could be further reduced and the elongation could also be improved.