HYBRID POWERTRAINS
ULTRA-CAPACITOR VS BATTERY
Komatsu launched the world’s first hybrid
(electro-hydraulic) powered piece of construction
equipment with the PC200-8 Hybrid excavator,
which was made available in Japan, China and
North America in 2008.
Today Komatsu has several more machines in
its Hybrid range, but the technology still has the
same basis. Komatsu Hybrid technologies
comprise: diesel engine; ultra-capacitor for energy
storage/delivery; electric swing motor/generator;
electric motor/generator on engine; plus a control
system to optimise power flow between them all.
The system works by using the electric
swing motor/generator to provide regenerative
charge to the ultra-capacitor, which holds energy
that can be drawn on by the machine’s electric
motor when needed.
Komatsu’s hybrid engine technology has been
20 years in development and is 100% designed,
developed in house. “The ultra-capacitor used in
Komatsu Hybrid products is still unique in the
industry, as far as I am aware,” says James
Venerus product marketing general manager at
Komatsu Europe.
The advantages over battery, or other storage
methods include: high power density versus
volume, compared to alternative energy storage
methods (such as battery). This means that space,
weight, performance, and ultimately machine life,
are optimised. Typical power density is typically at
least 10 times that of batteries, with close to 100%
efficiency due to negligible internal resistance.
The devices themselves, and the manufacturing
processes, do not involve the use of harmful
chemicals or toxic materials.
Charge and discharge of the ultra-capacitor is
by flow of ions and electrons, and is
instantaneous, meaning faster charge and
delivery of energy due to instantaneous charge /
discharge response. Batteries require a chemical
reaction to charge and discharge (even with the
latest lithium-ion, solutions) which is
fundamentally slower and may compromise
response to high transient loads which are seen
when using construction machines. Furthermore,
the ultra-capacitor response and performance is
ABOVE: A Komatsu Hybrid
excavator in action
BELOW: How the Komatsu
Hybrid system works
independent of temperature (within normal
machinery operating range). Battery performance
tends to diminish, particularly at low
temperatures.
Finally it is worth noting that ultra-capacitor
performance does not diminish over the machine
lifetime. Battery performance tends to reduce
over time / number of cycles.
“Komatsu’s hybrid components are
maintenance free and designed to perform beyond
the standard machine life,” says Venerus.
Performance has been proven with over
11 years of field experience.
34 iVTInternational.com November 2019
/iVTInternational.com
