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SR hybrid electric drive history innovation

4 min read / December 2, 2022 / Staff writer


Hybrid electric drive technology — a history of heavy equipment innovation that continues today

When you think of hybrid technology, your first thought might be a Toyota Prius or other consumer automobiles joining the electric vehicle craze. But the hybrid electric drive was a mainstay in mining equipment decades before the auto industry began to develop hybrid vehicles.

In fact, earthmoving industry pioneer R.G LeTourneau Inc. pioneered the use of electric drive in earth moving equipment back in the 1920s. Joy Global acquired R.G. LeTourneau, and Komatsu subsequently acquired Joy Global and its latest electric drive switched reluctance (SR) technology. Since then, the hybrid electric drive has evolved — it’s taken decades to perfect current hybrid electric drive products and innovate future ones.

Today, SR hybrid technology has progressed to become an integral technology that powers productivity at mines and construction sites around the world thanks, in part, to an expert Komatsu electric drive engineering team and innovation lab.

Komatsu WE1850-3 wheel loader offers faster cycle times and increased productivity.mp4

SR hybrid machine

Longview — the epicenter of hybrid electric drive development

Switched reluctance motor technology was first developed many years ago for wheel loaders in the Komatsu facility at Longview, Texas. We've taken that technology and continued to expand on it to improve efficiencies for our customers’ equipment. For instance, SR technology is now also used on our hybrid shovel. We also added the innovative Kinetic Energy Storage System (KESS) on several machines, which uses features of the SR technology to provide deep storage of electrical braking energy for on-demand use.

In 2019, we launched the Electric Drive Innovation Center in Longview to continue to further hybrid electric drive advancements. With developing all the SR intellectual property, intelligence and assets over 70 years in one location, it made sense to create a dynamic center with a growing team where hybrid electric technology could continue to evolve and thrive. Today, the Electric Drive Innovation Center is a state-of-the-art research and development facility — an engineering hub focused on ushering the mining industry into a new era of efficiency and productivity.

“The Electric Drive Innovation Center is representative of our desire to push the boundaries of what is possible,” says Mark Barr, Director of Engineering at Komatsu. “We’re taking our 100 years of experience in applying electric drive to earth moving equipment and we’re really ratcheting up the scope of the work we are doing.”

This facility is nearly 25,000 square feet with a 6,000-square-foot covered area outdoors. The Electric Drive Innovation Center provides our engineers opportunities to continue to develop switched reluctance motor technology with resources like:

  • Capability for full drive line testing for mining vehicles of all sizes
  • Four twenty-ton cranes
  • Thirteen large electric drive test rooms
  • Seven power electronics bench test rooms that allow accurate assessments of machine performance in simulated conditions
  • Humidity chambers and freezers in the bench test rooms to test performance in harsh climates


Unlocking the full potential of SR hybrid electric drive technology

Bringing new benefits to customers has been the driving force behind decades of engineering and field testing efforts: “The goal has always been to improve cost per hour and cost per ton, and we’re addressing that issue for operations around the world,” says Barr.

Besides fuel savings and less environmental impact, SR hybrid electric drive technology has many other advantages:

  • Power density — An SR motor can put out the equivalent power of a larger one in a smaller package
  • Improved life and duty cycle — The rotating portion of an SR motor is lighter, which translates to less stress on the gear train, improving the longevity of critical components
  • No speed limitations — SR effectively has no electrical speed limitations and, compared to other motors, has a significantly higher speed capability

Best of all, we’ve worked with our customers using SR technology in mines worldwide to substantially improve the practical applications of switched reluctance motor technology. Building on those experiences, we’ve developed several unique innovations:

  •  Advanced SR control algorithms to optimize efficiencies in applying torque to the ground, controlling wheel slip to minimize tire wear and significantly reducing fuel burn
  • Rugged motor and generator designs that we’ve incorporated from decades of mining duty traction experiences so that machines are up to the task of achieving long life in the tough mining environment
  • Bidirectional power flow allowing braking energy, that would otherwise be wasted as heat, to be fed directly into the generator, turning the generator into a motor to power the hydraulics and cooling system during braking events

The future of hybrid electric drives looks bright

Today, Komatsu has more than 150 surface wheel loaders using SR hybrid electric drive technology around the world. That means millions of cumulative operation hours and thousands of individual component operational hours.

“Hybrid electric drives reduce fuel consumption, lower the amount of CO2 that goes into the atmosphere and helps operations control their costs. It’s a win for customer operations and the environment,” says Barr. “We’ve taken this technology to where it is today, and we’re continuing to innovate here in Longview to take it to even greater heights.”