If you missed last month’s article The History of Electric Motors – Part 1, check it out.
Although William Sturgeon invented the first DC motor that provided enough power to drive machinery, it wasn’t until 1886 that Frank Julian Sprague invented the first DC motor that could run at a constant speed under variable weight. This motor paved the way for broad acceptance and use of electric motors for industrial applications.
Sprague continued to champion the DC electric motor’s acceptance by inventing technology that improved the electric grid distribution and ways to return power to the grid. He also figured out ways to distribute electricity via overhead wires for electric trolley systems (1887-1888), electric elevators and control systems, and the electric subway in Chicago in 1892.
The pace of innovation continued to accelerate as more inventions and refinements on existing inventions proliferated. By the 1920s, most developed nations were constructing electrical grids, and electricity became common in everyday life. Streetlights were now electric, major cities had electric trains or trolley systems, and the electric motor began taking over tasks that previously had to be done by hand or with farm animals’ assistance. Homes now had refrigerators, fans, washing machines, and much more. Life on the farm became a lot easier through the use of electric pumps to distribute water and processing grain.
This led to more innovations such as the induction motor, a rotating bar winding rotor, and more. In 1921, a new electric motor design was discovered that increased their efficiency and reliability. The use of an air gap between the rotor and the stator facilitated the flow of electromagnetic flux in DC motors. Originally designed to reduce wear and tear on components using brushes, this accidentally led to a motor efficiency breakthrough.
Brushed electric motors were still the standard, and they suffered a lot of wear and tear due to friction. They also had a tendency to overheat, which prevented them from being used for high power applications such as HVAC and electric vehicles.
Wear and tear would continue to be an issue for brushed DC motors, even following the discovery of the air gap. In brushed DC motors, the brushes must contact the commutators to send electrical signals; erosion due to this persistent friction would wear them out, sometimes caused overheating at high loads. Their reliability and temperature management issues prevented brushed DC motors from being widely used in high power applications like HVAC and electric vehicles.
The brushless commutator changed this forever. Discovered originally in 1962, brushless permanent magnet motors were not widely used until the early 1980s. With permanent magnet brushless motors, these DC motor designs were far more powerful and efficient than any brushed motor.
Innovation continues on DC electric motors to this day. Constant refinement of existing designs creates more powerful electric motors with higher efficiency using a smaller footprint every day. Today’s electric motors are integrated with computerized control systems for even smoother operation. As the demand for electric motors builds as the electric vehicle market grows, the innovation will continue.
This ends Part 2 of our blog series on the History of Electrical Motors.
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