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Effects of Ohmic Area Etching on Buffer Breakdown Voltage of AlGaN/GaN HEMT
Chong Wang,Xiao-Xiao Wel,Meng-Di Zhao,Yun-Long He,Xue-Feng Zheng,Wei Mao,Xiao-Hua Ma,Jin-Cheng Zhang,Yue Hao 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.3
This study is on how ohmic area etching affects the buffer breakdown voltage of AlGaN/GaN HEMT. The surfacemorphology of the ohmic metal can be improved by whole etching on the ohmic area. The buffer breakdown voltagesof the samples with whole etching on the ohmic area were improved by the suppression of the metal spikes formedunder the ohmic contact regions during high-temperature annealing. The samples with selective etching on theohmic area were investigated for comparison. In addition, the buffer leakage currents were measured on the differentradii of the wafer, and the uniformity of the buffer leakage currents on the wafer were investigated by PL mappingmeasurement.
Effects of Ohmic Area Etching on Buffer Breakdown Voltage of AlGaN/GaN HEMT
Wang, Chong,Wel, Xiao-Xiao,Zhao, Meng-Di,He, Yun-Long,Zheng, Xue-Feng,Mao, Wei,Ma, Xiao-Hua,Zhang, Jin-Cheng,Hao, Yue The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.3
This study is on how ohmic area etching affects the buffer breakdown voltage of AlGaN/GaN HEMT. The surface morphology of the ohmic metal can be improved by whole etching on the ohmic area. The buffer breakdown voltages of the samples with whole etching on the ohmic area were improved by the suppression of the metal spikes formed under the ohmic contact regions during high-temperature annealing. The samples with selective etching on the ohmic area were investigated for comparison. In addition, the buffer leakage currents were measured on the different radii of the wafer, and the uniformity of the buffer leakage currents on the wafer were investigated by PL mapping measurement.
Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback
Long-Yue Yang,Jian-Hua Liu,Chong-Lin Wang,Gui-Fu Du 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.
A Novel Phase Locked Loop for Grid-Connected Converters under Non-Ideal Grid Conditions
Long-Yue Yang,Chong-Lin Wang,Jian-Hua Liu,Chen-Xi Jia 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1
Grid synchronization is one of the key techniques for the grid-connected power converters used in distributed power generation systems. In order to achieve fast and accurate grid synchronization, a new phase locked loop (PLL) is proposed on the basis of the complex filter matrixes (CFM) orthogonal signal generator (OSG) crossing-decoupling method. By combining first-order complex filters with relation matrixes of positive and negative sequence voltage components, the OSG is designed to extract specific frequency orthogonal signals. Then, the OSG mathematical model is built in the frequency-domain and time-domain to analyze the spectral characteristics. Moreover, a crossing-decoupling method is suggested to decouple the fundamental voltage. From the eigenvalue analysis point of view, the stability and dynamic performance of the new PLL method is evaluated. Meanwhile, the digital implementation method is also provided. Finally, the effectiveness of the proposed method is verified by experiments under unbalanced and distorted grid voltage conditions.
Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback
Yang, Long-Yue,Liu, Jian-Hua,Wang, Chong-Lin,Du, Gui-Fu The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.
A Novel Phase Locked Loop for Grid-Connected Converters under Non-Ideal Grid Conditions
Yang, Long-Yue,Wang, Chong-Lin,Liu, Jian-Hua,Jia, Chen-Xi The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1
Grid synchronization is one of the key techniques for the grid-connected power converters used in distributed power generation systems. In order to achieve fast and accurate grid synchronization, a new phase locked loop (PLL) is proposed on the basis of the complex filter matrixes (CFM) orthogonal signal generator (OSG) crossing-decoupling method. By combining first-order complex filters with relation matrixes of positive and negative sequence voltage components, the OSG is designed to extract specific frequency orthogonal signals. Then, the OSG mathematical model is built in the frequency-domain and time-domain to analyze the spectral characteristics. Moreover, a crossing-decoupling method is suggested to decouple the fundamental voltage. From the eigenvalue analysis point of view, the stability and dynamic performance of the new PLL method is evaluated. Meanwhile, the digital implementation method is also provided. Finally, the effectiveness of the proposed method is verified by experiments under unbalanced and distorted grid voltage conditions.
Yun Long,Chong Yao,En-Zhe Song,Quan Dong,Yan-Min Wang 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2
In this paper, an adaptive second-order sliding mode control approach is proposed for the performance improvement of electronic throttles (ET). Based on the traditional twisting approach, a novel adaptation mechanism based on the online zero-crossing checking is contained in the modified approach to make the control magnitude of the controller at the minimum admissible level. The idea behind it is to calculate the number of zero-crossings of the sliding surface in real time. The guaranteed stability condition and convergence region of the system are also deduced. In order to further prove its high adaptation capability, the commonly used adaptation mechanism called the Lyapunov-based type is also introduced for comparative study. Simulations and experiments validate the proposed approach with the advantages of chattering elimination, high speed and accuracy in the control of ET systems.