The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability ...The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability problem to the DAB converters. Thus, this paper,studies the stability of a digitally controlled DAB converter with an output voltage closed loop controller. Firstly, to accurately study the stability in a DAB converter, a discrete-time model established in a whole switching period is obtained. The model considers the output capacitor ESR,the digital control delay, and sample-and-hold process. By using this model, the stabilities of the DAB converter versus the proportional controller parameter and the output capacitor ESR are analyzed and the critical values are predicted accurately. Moreover, the stability boundary ofthe proportional controller parameter and the output capacitor ESR is also obtained. The result shows that the value of the output capacitor ESR can have a great effect on the stability region of the proportional controller parameter. Finally, the theoretical analyses are verified by the simulation and experimental results.展开更多
The electric parking mechanism is studied for an electrically controlled two-speed auto transmission that is being developed for electric vehicles.Safety requirements include low-speed safe parking,reliable self-lock ...The electric parking mechanism is studied for an electrically controlled two-speed auto transmission that is being developed for electric vehicles.Safety requirements include low-speed safe parking,reliable self-lock and the avoidance of abnormal parking.A dynamic model of the parking mechanism is established and analyzed using Adams software.Finally,failure of the parking mechanism due to wear is observed in bench testing and compared with experimental results after optimization.展开更多
基金supported by National Natural Science Foundation of China(NSFC)(No.51207126)
文摘The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability problem to the DAB converters. Thus, this paper,studies the stability of a digitally controlled DAB converter with an output voltage closed loop controller. Firstly, to accurately study the stability in a DAB converter, a discrete-time model established in a whole switching period is obtained. The model considers the output capacitor ESR,the digital control delay, and sample-and-hold process. By using this model, the stabilities of the DAB converter versus the proportional controller parameter and the output capacitor ESR are analyzed and the critical values are predicted accurately. Moreover, the stability boundary ofthe proportional controller parameter and the output capacitor ESR is also obtained. The result shows that the value of the output capacitor ESR can have a great effect on the stability region of the proportional controller parameter. Finally, the theoretical analyses are verified by the simulation and experimental results.
基金The authors acknowledge financial support from the Science and Technology Research Youth Fund Project of Hebei Colleges and Universities(QN2016197).
文摘The electric parking mechanism is studied for an electrically controlled two-speed auto transmission that is being developed for electric vehicles.Safety requirements include low-speed safe parking,reliable self-lock and the avoidance of abnormal parking.A dynamic model of the parking mechanism is established and analyzed using Adams software.Finally,failure of the parking mechanism due to wear is observed in bench testing and compared with experimental results after optimization.
