Permanent magnets are an integral part of many motors t […]
Permanent magnets are an integral part of many motors that take advantage of advances in obtaining powerful and stable magnetic materials.
A revolutionary motor employs only permanent magnets to attract and repel forces in sequence, producing continued motion like a conventional electric motor without reversing polarity or using an external power source.
Today, rare earth magnets containing lanthanide elements such as neodymium and samarium carry large magnetic moments. For example, a neodymium (NdFeB) magnet comprised of neodymium, iron and boron and measuring only 10.16cm X 10.16cm X 5.08cm can have a Brmax of 14,800, a surface field Gauss of 4,933, a pull force of 557 kg, and is stable at 176oF. Unless overheated or physically damaged, the magnet will lose less than 1% of its strength over 10 years.
To see the impact of permanent magnets we have to look at a typical electric motor. As an external power source passes through the rotor field, it serves as an electromagnet that is attracted to the permanent magnet causing the motor to rotate. For continued rotation, the electromagnet allows the rotor field to reverse the polarity of its magnetic field producing repulsion. The repulsive force between the poles repels the electromagnet along its path of motion. If polarity of the rotor is not reversed, the attractive force that pulled the electromagnet toward the permanent magnet will prevent the electromagnet from escaping and cause it to return and rest opposite the permanent magnet.