The permanent magnet in is made of alnico 5, whose maximum energy product (-BmHm) is 40 kJ/m³. A flux density of B, = 0.8 T is to be established in the air gap. The air gap has the dimensions A,= 2.5 cm² and l,= 0.4 cm. (a) Determine the minimum volume of the permanent magnet to produce the necessary air gap flux density. (b) Repeat part (a) if the permanent magnet is NdFeB (Neodymium-Iron-Boron), whose maximum energy product is 295 kJ/m³. (c) Calculate the reduction of the permanent magnet volume (the ratio of the NdFeB volume to the alnico 5 volume) required to produce the same flux density in the air gap by replacing alnico 5 with NdFeB. Assumption: The magnetic reluctance of soft iron is negligible, and the permeability of free space is µo = 4-T-10-7 H/m.

The permanent magnet in is made of alnico 5, whose maximum energy product (-BmHm) is 40 kJ/m³. A flux density of B, = 0.8 T is to be established in the air gap. The air gap has the dimensions A,= 2.5 cm² and l,= 0.4 cm. (a) Determine the minimum volume of the permanent magnet to produce the necessary air gap flux density. (b) Repeat part (a) if the permanent magnet is NdFeB (Neodymium-Iron-Boron), whose maximum energy product is 295 kJ/m³. (c) Calculate the reduction of the permanent magnet volume (the ratio of the NdFeB volume to the alnico 5 volume) required to produce the same flux density in the air gap by replacing alnico 5 with NdFeB. Assumption: The magnetic reluctance of soft iron is negligible, and the permeability of free space is µo = 4-T-10-7 H/m.