Passive automatic maximum wind energy tracking wind power generation system
This paper proposes a novel off-grid wind power generation system, comprising a double-winding permanent magnet synchronous generator, a three-phase controllable saturated reactor, two rectifiers, a battery and a load. The output power curve of the new system keeps in accordance with the maximum output power curve of the wind turbine, which makes the system track maximum wind energy automatically. A 300W prototype was manufactured. Experimental results show that the power output curve of the new system matches with the maximum output power curve of the wind turbine in a wide range of rotational speed. Compared with the traditional system, Wind energy utilization coefficient of the new system is improved greatly.
Research on dual-stator winding multi-phase high-speed induction generator with rectifier load
Based on analysis and calculation of the relation between current harmonics and MMF harmonics in the dual-stator winding multi-phase high-speed induction generator with a rectifier load, a new idea, which divides the generator system into two sub-systems to be analyzed individually, is presented. For the sub-system of the 12-phase power winding with a rectifier load, the loop current method is used to establish network equation set in terms of the network graph theory. The numerical stability problem is solved by alternating use of fixed time-step and varied time-step, and the voltage and current with their fundamental components of the power winding are obtained. For the other sub-system of the induction generator with dual-stator winding and solid cage rotor, the electromagnetic field analysis method and the multi-variable optimization approach are combined to get the control winding current and stator frequency. Calculated results well match experiment results, indicating that the new proposed method is of effectiveness and high accuracy.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.