Design on notch structure of stator tooth to reduce of cogging torque of single-phase BLDC motor
This paper proposes the design method on the notch structure of stator tooth to reduce the cogging torque of the single-phase brushless Direct Current (BLDC) Motor. The single phase BLDC motors generates the dead-point causing a starting failure. This problem is solved by using an asymmetric air-gap structure. However, the asymmetric air-gap structure increases the cogging torque causing a noise and vibration of BLDC motor. Therefore, the reduction of cogging torque is essential to improve the performance of BLDC motor. This study for reducing the cogging torque of BLDC motors applies to notch structure of stator because of ease of application and low cost. In this paper, Availability on reduction of cogging torque of the asymmetric notch is proved by using two-notches. Then, the reduction of cogging torque is proved by using the finite element analysis(FEA).
Investigation of the influence of variations in the number and width of anti-notch depending on cogging torque reduction
Cogging torque is one of the electromagnetic torque. This torque appears at the beginning of the rotation of permanent magnet electric machine, caused by the interaction between the stator slots and an electromagnetic field generated by the permanent magnet. Cogging torque pursued as small as possible so that the movement of the rotor is not hampered. Cogging torque reduction have researched for many years with a lot of methods. This research study continued from earlier study of cogging torque reduction using anti notch method. In this paper, the width and variation in some anti notch became investigated variable to cut the cogging torque. The 4 degree half cylinder anti notch simulate using FEMM 4.2 and the result is 4 degree width and one of anti notch has the highest reduction of the cogging torque. Adding coupled number of anti notch is not too influence to cogging torque reduction.
Experimental Study for a Double-Glazed Forced-Flow Solar Collector/Regenerator
Experimental study of a double-glazed forced-convection solar collector/regenerator for absorption solar cooling is presented. The south facing experimental solar collector/regenerator with 10 deg slope is located at Kaohsiung, Taiwan at 120{degree}19minutesE longitude and 22{degree}34minutesN latitude. The size of the collector is 1 m wide and 7 m long with an effective regeneration area of 0.9 m by 6 m. Previous study for single-glazed forced-convection solar collector/regenerator operated at the same location has shown to have a best day-average efficiency of 17%. In order to raise the system performance, a double-glazed collector/regenerator is constructed such that air can be preheated in the upper channel flow. The preheated air is then conducted into the lower channel where it contacts with the film flow of solar heated lithium-chloride solution and regenerates the solution by carrying out the evaporated water vapor. The preheated air has lower relative humidity but the same humidity ratio since it is sensibly heated. Therefore, the regeneration driving potential is increased. The present study shows that the best day-average efficiency can reach 20% which increases the feasibility of the open-cycle absorption solar cooling system. Effects of controlling parameters on the collector/regenerator performance are studied, and heat and mass transfer correlationsmore » are also presented for design purposes.« less