THE HISTORY OF ELECTRIC MOTOR TECHNOLOGY: A JOURNEY THROUGH TIME

09.19.20

THE HISTORY OF ELECTRIC MOTOR TECHNOLOGY: A JOURNEY THROUGH TIME

Since the birth of technology, the pace of innovation has continued to accelerate. New inventions and technologies make our lives easier, but what’s fascinating is that technology often leads to the next innovative ideas and discoveries, making it easier to design and build even newer technology. This ever-accelerating cycle of innovation continues to reshape and redesign the world we live in, and it’s the reason why you can sip on an old-fashioned and watch Seinfeld while you’re packed in a metal tube hurtling through the sky 30,000 feet above the Atlantic. 

The story of electric motor technology has been no exemption, following this trend of innovation for the past 200 years. Looking back at the invention of the first electric motor in 1832, it’s hard to imagine the impact electric motors have already made on our lives and other technologies,  and even harder to imagine the next 200 years of innovation. Through retelling the history of the electric motor, we will witness the accelerating cycle of innovation in live action and better understand what’s in store for the future.

 

The Invention of the Electric Motor

Hans Christian Ørsted was experimenting with electricity in 1820, when he observed that a compass deflected when he held an electrified rod next to it. He had just discovered electromagnetism and although undoubtedly he had no grasp of his discovery’s impact but he just set the ball in motion for the innovation of electric motor technology.

It wasn’t long before scientists around the world were searching for power generating applications of electromagnetism. William Sturgeon, an English physicist, is credited with inventing the first DC electric motor in 1832. His design was the first electric motor capable of moving machinery, however, it was still heavily limited by its low power output. 

A few years later in the United States, Thomas Davenport and his wife Emily Davenport were granted the first DC electric motor patent in 1837. Their design was a partial adaptation from Sturgeon’s first motor. Unfortunately, despite years of experimentation, Davenport’s motor design was still plagued by the same power and efficiency issues faced by Sturgeon’s original design.

Davenport's Patented Motor

Thomas and Emily Davenport's Patented Motor

Still, the most impressive early motor design was built by a Russian named Moritz Von Jacobi whose electric motor set a world record for mechanical power output in 1834, including Davenport’s motor. Jacobi didn’t waste any time when making his improvements either, and only a year later, in 1835, he demonstrated his new design’s increased power by ferrying 14 people across a river using a boat powered by his motor.

 

The First Practical DC Motor

Following the early demonstrations of electric motor capability, interest in electric motor technology exploded, inspiring hundreds of new inventions and discoveries. Still, the first generation of electric motors were glorified paperweights. They were terribly impractical, having voltage loss across windings, an unstable supply current, and common sparking. Over the course of the next 50 years, engineers and physicists worked to solve these problems by optimizing and redesigning the fundamental components of the electric motor.

A number of improvements were made to the rotor and armature design between 1835-1886 in an effort to develop the first ‘practical’ motor, with notable contributions being made by Italian physicist, Antonio Pacinotti and Belgian electrical engineer, Zénobe Gramme. However, only American inventor Frank Julian Sprague is credited with inventing the first ‘practical’ motor, in 1886. 

Sprague's Practical Motor

Frank Julian Sprague's 'Practical' Motor

Sprague’s electric motor eliminated sparking, voltage loss across windings, and could deliver power at a constant speed-- making it the first ‘practical’ DC electric motor, enabling the broader application of electric motors. Sprague’s motor designs were practically reliable and fairly powerful, but the efficiencies of these designs left much to be desired. Sprague would use his motors for the development of the first electric trolley system the following year in Richmond, Virginia in 1887.

 

The First Generators and Electrification

In Europe, further building off of his early discoveries and the discoveries of others, Zénobe Gramme developed his Gramme machine in 1871. His machine could convert mechanical energy into a continuous current of electrical energy. While presenting his invention at the 1873 World’s Fair in Vienna, Gramme accidentally discovered the reversibility of electric motors when he connected two DC devices 2 km from each other, with one functioning as the motor and the other as the generator. 

The discovery of DC electric motor reversibility proved that electric motors could be used as generators, converting mechanical work into electrical energy, as well as being able to return unused energy back to the source-- which assisted with the development of early power grids.

By the 1920’s, nations across the world had begun developing networks of electrical grids. Soon enough, electricity began creeping into everyday life:  gas lanterns were replaced by electric streetlights, air conditioning units now cooled offices and homes, and the streets of major cities were busy with systems of electric trolleys. The electrical take-over had begun, and the practicality of electric technology accelerated. 

 

Advanced Motor Technology - Air Gaps, Magnets and More

In 1921, a revolutionary new design concept was introduced to electric motors further increasing their reliability and efficiency. Although introduced by a motor maintenance team in the United States to prevent damage caused by friction between components, a small air gap between the rotor and the stator was also found to facilitate the flow of electromagnetic flux in DC machines, further increasing their efficiency.

ECM Motor Air Gap

ECM's PCB Stator BLDC Motor with Air Gap Labeled

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 be in contact with the commutators in order to send electrical signals; erosion due to this persistent friction would wear them out, sometimes 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.

This all changed with the invention of the brushless commutator. Although discovered in 1962, brushless permanent magnet motors only became widely used around 1982, when rare earth metals became readily available. With the help of permanent magnets, brushless DC motors could be designed to be more powerful and efficient than any brushed motor, while providing superior quality of motion.

Of course, the discovery of the brushless DC motor did not halt innovation and in the late 80’s, a pair of scientists, Jerry Genco and Norman Smith, patented a motor with a stator on a printed circuit assembly. Their design both electrically and mechanically connected the stator to a printed circuit board in an effort to reduce manufacturing and material costs associated with permanent magnet BLDC motors.

 

Modern Motor Technology

Brushless DC motors today are lightyears ahead of the old trolley motors of the 19th century, but their design is far from perfection. Conventional BLDC motors like the ones developed in the 80’s are the most popular type of motors on the market today, and their popularity continues to grow with the demand for carbon-neutral products and affordable air conditioning. The need for solutions with an even higher power output in a smaller package, a reduced environmental footprint, and a viable mass production process will continue to grow.

Building from 200 years of discovery, ECM’s team re-evaluated Genco and Smith’s idea, approaching it from a 21st century perspective. By embedding copper-etched conductors into a multi-layered printed circuit board to form a stator that works in conjunction with permanent magnets, ECM’s patented technology eliminates the need for wire winding and iron laminations used in conventional motors and generators. 

ECM's PCB Stator Motor Design

ECM's Patented PCB Stator and Motor 

ECM’s use of a PCB Stator in their permanent magnet BLDC design, allows them to design incredibly thin, lightweight motors that use up to 80% less raw materials. Additionally, using their revolutionary new design, ECM’s team created a design software, PrintStator, to automatically generate unique PCB Stator designs and incorporate all of ECM’s patented design features. PrintStator optimizes copper geometries and thickness in PCB Stators to deliver a machine with superior torque density and power efficiency.

ECM's PCB Stator Motor Design

Exploded View of ECM's Patented PCB Stator Motor Design

In 2015, PrintStator was launched and utilized to prototype a mid-drive solution for an electric bike. From discrete inputs, PrintStator automatically generated a unique PCB Stator design, complete with an associated Gerber file, specifying the detailed build characteristics ubiquitously utilized by a PCB manufacturing house to print the design. By the end of 2019, ECM had collected 10 patents surrounding their PCB Stator BLDC design and software. PrintStator has been used to successfully integrate the PCB Stator platform in the e-mobility, HVACR, robotics, military, maritime and medical industries. 

ECM’s PCB Stator motor design improves on many of the issues that have afflicted electric motors from their invention in 1832, significantly improving on motor reliability, efficiency, and power density, but also tackling modern technology obstacles including sustainability, manufacturability, size and weight. The use of PCB Stators in BLDC motors is certainly the next evolution in electric motor technology but as we can see from the past, it will not be the last.

 

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Appendix
[1]https://edisontechcenter.org/electricmotors.html#:~:text=History%20and%20Inventors%3A,motion%20devices%20using%20electromagnetic%20fields. - Early history of electric motors and inventors
[2] https://shodhganga.inflibnet.ac.in/bitstream/10603/50968/4/chapter%201.pdf  - First Brushless DC motors
[3] https://patents.justia.com/inventor/robert-e-lordo (BLDC Motor Patents)  - Patents for BLDC motors with permanent magnets
[4] https://www.eti.kit.edu/english/1382.php (sourcing image and information on Jacobi’s first motors)
[5] http://www.bera.org/articles/sprague.html (Sprague motor image)
[6] https://www.hemmings.com/stories/2020/01/31/why-thomas-and-emily-davenport-shouldnt-get-credit-for-inventing-the-electric-vehicle (Davenport motor image)
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