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Liu W.,Xian Jiaotong University | Zhou H.,TBEA xiAn Electrical Technology Co. | Zhang L.,TBEA xiAn Electrical Technology Co. | Guo L.,TBEA xiAn Electrical Technology Co. | Liang H.,TBEA xiAn Electrical Technology Co.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2013

The control strategy of PV grid-connected inverter under the unbalanced grid conditions was studied, the theoretical analysis and the experiments were conducted to verify the effectiveness of the control strategy. The proposed control strategy enhances the stability of the on-grid system and improves the accuracy of the MPPT and the power factor control, as well as the efficiency of the inverter. Furthermore, it was used to control low voltage ride through absolutely. The experiments results showed that the proposed method has high values to be used in the real PV inverter plant application. Source


Liu W.,Xian Jiaotong University | Hao X.,Xian Jiaotong University | Yang X.,Xian Jiaotong University | Zhao M.,TBEA xiAn Electrical Technology Co. | And 2 more authors.
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2013

Sliding mode control (SMC) is recognized as robust controller with a high stability in a wide range of operating conditions, however it suffers from chattering problem. In addition, the sliding surface that is a linear combination of the system state variables and the generated references would drift while the system parameters change or external disturbance exists, which affects the tracking error and THD of system output seriously. In this paper, a fixed switching frequency multi-resonant SMC (MRSMC) is proposed for single-phase grid-connected inverter. The chattering problem of SMC is eliminated by adopting Gao's reaching law and the parameters of SMC are optimized according to the ripple of the system output based on pulse width modulation (PWM). In order to fully eliminate the grid current tracking error and suppress its THD effectively, multiple resonant terms of the grid current error are added to the sliding function. Simulation and experimental results on a 5-kVA single-phase grid-connected inverter prototype show the effectiveness of the proposed control strategy. © 2013 IEEE. Source


Li J.,Xian University of Technology | Du X.,China Aerospace Science and Technology Corporation | Song H.,TBEA xiAn Electrical Technology Co. | Zhong Y.,Xian University of Technology
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2014

For the loss model control based efficiency optimization strategies of induction machines, whether the motor parameters required in the strategy, especially those related to the iron loss and the copper losses, are accurately enough obtained, will directly affect the energy-saving effect. The induction machine model which does not neglect iron loss was established, the improved genetic algorithm is employed to identify all the electrical parameters of the induction machine including the iron loss equivalent resistance. At the same time, the constraint that the stator leakage inductance and the rotor leakage inductance equal each other is removed in order to approach practice. The data acquisition system is adopted to do the experiments to ensure that the induction machines which are installed into the production line can run without interruption. The experimental results show that the proposed scheme can provide accurate enough induction machine parameters which can reproduce the iron loss and the copper loss. This makes it possible to realize the maximum energy saving for efficiency optimization of induction machines. Source


Liu W.,Xian Jiaotong University | Zhao M.,TBEA xiAn Electrical Technology Co. | Yang X.,Xian Jiaotong University | Liu T.,Xian Jiaotong University | Chang X.,Xian Jiaotong University
Conference Proceedings - 2012 IEEE 7th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2012 | Year: 2012

This paper analyzes the influence of the photovoltaic (PV) inverter on photovoltaic simulator based on the small signal model for the purpose of improving the performance of the photovoltaic simulator. Since the photovoltaic simulator works cascading photovoltaic inverter, the input impedance of the inverter could change the characteristic of the simulator. Hence, some special requirements should be considered in the design of PV simulator. In this paper, a special analysis and design method is proposed to solve the issue. The experimental results confirm correctness of the analysis and the design methods. © 2012 IEEE. Source


Patent
TBEA XIAN Electrical TECHNOLOGY CO. and Tbea Sunoasis Co. | Date: 2011-05-05

Disclosed is a grid-connected inverter and a method for filtering AC output thereof. The grid-connected inverter comprises an AC output filter which includes two or more switchable filtering modules, power capacity of each filtering modules corresponding to a different output power of the grid-connected inverter; a monitoring module which is used to perform realtime monitoring on voltage and current outputted by the grid-connected inverter; and a control circuit which is used to calculate an output power grade of the grid-connected inverter according to the voltage and the current monitored by the monitoring module and control switching to the filtering module having a corresponding power capacity according to the power grade, the power grade being selected from a plurality of power grades which are divided according to power capacities of the filtering modules.

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