There are two important objectives for airflow control in proton exchange membrane fuel cells （PEMFCs）. One is to keep the desired excess ratio（to provide sufficient reactant airflow） to ensure fast transient resp...There are two important objectives for airflow control in proton exchange membrane fuel cells （PEMFCs）. One is to keep the desired excess ratio（to provide sufficient reactant airflow） to ensure fast transient response arid to minimize auxiliary power consumption, and the other one is to control the cathode pressure in stack within an acceptable range. In reality, the big inertia of stack＇s airflow-supplying activator limits the bandwidth of air-flow supply loop, which makes the first objective difficult to achieve, and another difficulty is that airflow is coupled with the cathode pressure in stack, which make it uneasy to keep the pressure unchanged in case of airflow perturbation. In order to overcome these difficulties, three dependant controllers are presented in this paper to control airflow, deeouple the cathode pressure in stack from airflow and stabilize the cat bode pressure in stack respectively. The effectiveness of these controllers is proven by subsequent simulation and test results.展开更多
Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/...Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/LF) mode. By optimizing process parameters, stress free(-0.27 MPa) Si Nx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited Si Nx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit(IC), micro-electro-mechanical systems(MEMS) and bio-MEMS.展开更多
文摘There are two important objectives for airflow control in proton exchange membrane fuel cells （PEMFCs）. One is to keep the desired excess ratio（to provide sufficient reactant airflow） to ensure fast transient response arid to minimize auxiliary power consumption, and the other one is to control the cathode pressure in stack within an acceptable range. In reality, the big inertia of stack＇s airflow-supplying activator limits the bandwidth of air-flow supply loop, which makes the first objective difficult to achieve, and another difficulty is that airflow is coupled with the cathode pressure in stack, which make it uneasy to keep the pressure unchanged in case of airflow perturbation. In order to overcome these difficulties, three dependant controllers are presented in this paper to control airflow, deeouple the cathode pressure in stack from airflow and stabilize the cat bode pressure in stack respectively. The effectiveness of these controllers is proven by subsequent simulation and test results.
基金supported by the National High Technology Research and Development Program of China(No.2015AA042603)the Fundamental Research Funds for the Central Universities of China(No.106112014CDJZR160001)
文摘Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/LF) mode. By optimizing process parameters, stress free(-0.27 MPa) Si Nx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited Si Nx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit(IC), micro-electro-mechanical systems(MEMS) and bio-MEMS.
