Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linea...Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linear motor is used in the linear driving system of trains, neither an overhead line nor a third rail is needed. However, the doubly- fed motor will lead to more severe thrust fluctuation than the unilateral motors. In order to overcome this shortcoming, the thrust fluctuation of the doubly-fed motor should be analyzed. In this paper, an expression for motor thrust is derived. It points out that the slot effect caused by the slotted structure is the main reason for the increase of thrust fluctuation. The method of adopting unequal pole pitch and unequal slot numbers per pole per phase of stator and mover, is proposed to weaken the slot effect when designing the motor slot parameters. Three different motor models are simulated by ANSOFT. The proposed method results in a motor thrust fluctuation coefficient of 8.4%, compared to 49.4% for the conventional method. Therefore, the motor＇s thrust fluctuation is effectively suppressed by the proposed method.展开更多
ELECTRIFIED transportation in automotive,railway,aviation and navigation has received more and more attention in recent years.Innovations in energy efficiency,speed and performance of all kinds of transportation vehic...ELECTRIFIED transportation in automotive,railway,aviation and navigation has received more and more attention in recent years.Innovations in energy efficiency,speed and performance of all kinds of transportation vehicles are hot topics both in academia and industry.The corresponding researches relate to the design and control of electrical machines,power converters and energy storage systems.展开更多
Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed t...Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).展开更多
The permanent magnet electromagnetic hybridmagnet (PEHM) has the advantages of low energy consumptionand a large suspension air gap. In this study, an unbalancedPEHM structure is proposed, which combines the advantage...The permanent magnet electromagnetic hybridmagnet (PEHM) has the advantages of low energy consumptionand a large suspension air gap. In this study, an unbalancedPEHM structure is proposed, which combines the advantages ofthe previous hybrid magnet structure. First, by establishing themagnetic circuit model of the new hybrid magnet structure, theinfluence of magnetic field distribution on the working magneticcircuit of the magnet is analyzed, and the method of magneticforce correction calculation of the new structure magnet isgiven. Then, the validity of the magnetic calculation method isverified by the 3D finite element method (FEM). Furthermore, theaverage suspension power force ratio is used as the optimizationgoal, and the system parameters of the hybrid magnet under aworking air gap of 6–10 mm and a load condition of 15000–20000 N are optimized by a genetic algorithm. Compared withthe previous hybrid magnet, the optimized hybrid magnet systemcan maintain lower power consumption under comprehensiveworking conditions.展开更多
文摘Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linear motor is used in the linear driving system of trains, neither an overhead line nor a third rail is needed. However, the doubly- fed motor will lead to more severe thrust fluctuation than the unilateral motors. In order to overcome this shortcoming, the thrust fluctuation of the doubly-fed motor should be analyzed. In this paper, an expression for motor thrust is derived. It points out that the slot effect caused by the slotted structure is the main reason for the increase of thrust fluctuation. The method of adopting unequal pole pitch and unequal slot numbers per pole per phase of stator and mover, is proposed to weaken the slot effect when designing the motor slot parameters. Three different motor models are simulated by ANSOFT. The proposed method results in a motor thrust fluctuation coefficient of 8.4%, compared to 49.4% for the conventional method. Therefore, the motor＇s thrust fluctuation is effectively suppressed by the proposed method.
文摘ELECTRIFIED transportation in automotive,railway,aviation and navigation has received more and more attention in recent years.Innovations in energy efficiency,speed and performance of all kinds of transportation vehicles are hot topics both in academia and industry.The corresponding researches relate to the design and control of electrical machines,power converters and energy storage systems.
文摘Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).
基金the Fundamental Research Funds for the Central Universities of China(No.2682017CX050).
文摘The permanent magnet electromagnetic hybridmagnet (PEHM) has the advantages of low energy consumptionand a large suspension air gap. In this study, an unbalancedPEHM structure is proposed, which combines the advantages ofthe previous hybrid magnet structure. First, by establishing themagnetic circuit model of the new hybrid magnet structure, theinfluence of magnetic field distribution on the working magneticcircuit of the magnet is analyzed, and the method of magneticforce correction calculation of the new structure magnet isgiven. Then, the validity of the magnetic calculation method isverified by the 3D finite element method (FEM). Furthermore, theaverage suspension power force ratio is used as the optimizationgoal, and the system parameters of the hybrid magnet under aworking air gap of 6–10 mm and a load condition of 15000–20000 N are optimized by a genetic algorithm. Compared withthe previous hybrid magnet, the optimized hybrid magnet systemcan maintain lower power consumption under comprehensiveworking conditions.
