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).
The Implement of Permanent Magnet Material Variations on the Reduction of Cogging Torque in PMSG
Permanent magnet synchronous generator is a type of electric machine that is extensively adopted for wind turbines. However, the operation of permanent magnets in the rotor sets up a unique issue, particularly an enormous cogging torque value. Cogging torque is a torque that occurs because the interaction that takes place between the flux provided by a permanent magnet and the slot on the stator. This torque affects the rotor’s initial movement in the generator where the rotation of the rotor will be heavy and not smooth. Therefore, this torque is crucial to be decreased so that indeed in small wind speed inputs, the rotor can rotate. In this research, variations in the handling of permanent magnets will be analysed, especially ALnico, NdFeB, Ceramics and SmCo employing the anti-notch method. From the results achieved, each type of permanent magnet influences the value of tangential flux density which further influences the value of cogging torque reduction. By applying the new anti-notch method, the cogging torque value is significantly reduced compared to the reference generator design.
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.