AC Motor - History

History

Alternating current technology was rooted in Michael Faraday’s and Joseph Henry’s 1830-31 discovery of a changing magnetic field that is capable of inducing an electric current in a circuit. Faraday is usually given credit for this discovery since he published his findings first.

In 1832, French instrument maker Hippolyte Pixii generated a crude form of alternating current when he designed and built the first alternator. It consisted of a revolving horseshoe magnet passing over two wound wire coils.

Because AC's advantages in long distance high voltage transmission there were many inventors in the United States and Europe during the late 19th century trying to develop workable AC motors. The first person to conceive of a rotating magnetic field was Walter Baily who gave a workable demonstration of his battery-operated polyphase motor aided by a commutator on June 28, 1879 to the Physical Society of London. Nearly identical to Baily’s apparatus, French electrical engineer Marcel Deprez in 1880 published a paper that identified the rotating magnetic field principle and that of a two-phase AC system of currents to produce it. Never practically demonstrated, the design was flawed as one of the two currents was “furnished by the machine itself.” In 1886, English engineer Elihu Thomson built an AC motor by expanding upon the induction-repulsion principle and his wattmeter. In 1887, American inventor Charles Schenk Bradley was the first to patent a two-phase AC power transmission with four wires.

"Commutatorless" alternating current induction motors seem to have been independently invented by Galileo Ferraris and Nikola Tesla. Ferraris demonstrated a working model of his single phase induction motor in 1885 and Tesla built his working two phase induction motor in 1887 and demonstrated it at the American Institute of Electrical Engineers in a 1888 (although Tesla claimed that he conceived the rotating magnetic field in 1882). In 1888, Ferraris published his research to the Royal Academy of Sciences in Turin, where he detailed the foundations of motor operation; Tesla, in the same year, was granted a United States patent for his own motor. Working from Ferraris's experiments, Mikhail Dolivo-Dobrovolsky introduced the first three-phase induction motor in 1890, a much more capable design that became the prototype used in Europe and the U.S. He also invented the first three-phase generator and transformer and combined them into the first complete AC three-phase system in 1891. The three phase motor design was also worked on by the Swiss engineer Charles Eugene Lancelot Brown and other three-phase AC systems were developed by German technician Friedrich August Haselwander and Swedish engineer Jonas Wenström.