The past life and future of permanent magnet motors?

Today, the motor market is flooded with permanent magnet motors, and it is normal, not just lucky, that permanent magnet brushless motors are growing at a rate that will continue for a long time. Decades after the first motors were invented, permanent magnet motors became practical, and the first motors used bar magnets. Unfortunately, the quality of these magnets was so poor that the first permanent magnet motors were industrially impractical. This limitation provided a platform for many inventors to experiment with magnets of various sizes, shapes, constructions and materials, resulting in the powerful and compact magnets used in today's permanent magnet motors.

Permanent magnets: the first electric motors

The first inventors of the rotating motor (later called the electric motor) used permanent magnets in their designs, but these "machines" were not actually electric motors compared to the motors we know today. Michael Faraday, one of the earliest experimenters in the emerging field of electricity and electromagnetism, built the rotating motor, known as the first electric motor. Using Hans Christian Oersted's idea of "generating a magnetic field by means of an electric current" and experimenter William Wollaston's method of using a magnet to rotate a current-carrying wire on an axis, Faraday constructed a laboratory model to convert electrical energy into mechanical (rotational) motion. The model used fixed and rotating permanent magnets with wires connected to a bowl of mercury and a battery. When the battery is connected to the wire, current flows in the circuit, generating an electromagnetic field that interacts with the permanent magnet to produce torque and cause mechanical motion.

After Faraday invented the "electric motor," other inventors quickly took steps to improve it and make it more similar to the motor we know today. In 1882, Peter Barlow (Peter Barlow) invented a spinning wheel called the Barlow wheel, which caused mechanical motion when the wheel was lowered until the spokes were immersed in mercury and a voltage was applied to the terminals.

The electromagnet: a historical halt to the permanent magnet motor

The first inventors of the electric motor knew early on that the permanent magnet motor had severe limitations as far as its practical applications were concerned. In 1882, John Urquhart, an electrician, wrote in his paper on the electric motor: "When electro-mechanics are applied with a large amount of energy, it is advisable to use an electromagnet instead of a permanent magnet. When equipped with electromagnets instead of permanent magnets, motors can significantly increase power. Moreover, the size and weight of the motor can be greatly reduced, the cost is much lower, and the machine is able to convert a larger current into a mechanical effect.

The British inventor William Sturgeon is credited with the invention of the first electromagnet in 1825. A few years later, in 1827, Hungarian inventor Istvan (nyos) Jedlik invented "the first rotating motor with an electromagnet and commutator. But the first practical electromagnetic DC motor was invented by Moritz Hermann Jacobi in 1834. Jacobi's motor lifted 10 to 12 pounds at a speed of 1 foot per second, about 15 watts of mechanical power. It is interesting to note that Jacobi wrote in 1835 that he was not the sole inventor of the electromagnetic motor, pointing out the priority of the Botto and Dal Negro inventions.

The electromagnetic DC motor first became popular in the 1880s, when DC was the main power source, and its use would change radically when Nikola Tesla invented the electromagnetic AC motor in 1889. AC motors consist of only two parts, a fixed stator and a rotor, and are simpler than electromagnetic DC motors. The fixed stator provides the rotating electromagnetic field, while the rotor connected to the output shaft receives its torque through the rotating magnetic field. The magnetic field is generated by two or more alternating currents that are out of synchronization with each other, and is referred to as a multiphase system. Tesla's AC motor offered simplicity, but it had controllability and operability issues that prevented DC motors from maintaining a stable presence in industrial applications for decades. With the imminent development of high-energy permanent magnets, the spring of permanent magnet motors is approaching.

The return of the permanent magnet motor

Until the twentieth century, permanent magnet materials were limited to naturally occurring magnetite, commonly referred to as magnetite. At the turn of the century, the world saw what could be described as a renaissance in the discovery of new magnetic materials, such as carbon, cobalt and tungsten steel. However, the quality of these first new magnetic materials was still very low. It wasn't until the development of Alinco magnets that the world had high quality magnets that could be used for many applications and opened the door for the return of permanent magnet motors yet.

After extensive research in the 1930s, the addition of large amounts of aluminum, nickel and cobalt to iron solutions resulted in efficient, commercially viable powder metallurgy produced by conventional ingot casting. They were called Alnico magnets and were 100 times stronger than any ore. 1950s saw the emergence of ferrite permanent magnets, which were used in motors for small household appliances. The widespread use of permanent magnets in electric motors took another important step forward in the 1960s when compounds of rare earth metals (sa) and cobalt were invented. Important in their own right, these permanent magnets were overshadowed by the invention of neodymium-iron-boron permanent magnets in the 1980s, which produced higher energy and were more common than the rare cobalt. Brushless permanent magnets did not appear until the 1970s. DC motors started to appear on the market, delayed not only by the development of high-energy permanent magnet motors, but also by the development of power devices and electronic controllers that could replace mechanical commutation with electronic commutation.

The future: nanocomposite permanent magnets

What is the future of permanent magnet motors? There is evidence that their use will continue to grow as they are used in new applications. However, new innovations are emerging in the field of high-energy permanent magnets, and one of these innovations is nanocomposite permanent magnets. These magnets are artificially constructed magnetic structures (called metamaterials) that produce strong permanent magnets by fabricating nanostructured hard/soft phase composites smaller than a micron. Currently, they are used in biomedicine, magnetic storage media, magnetic particle separation, sensors, catalysts and pigments. In the future, the world may see nanocomposite magnetic materials being used in the next generation of permanent magnet motors.