Wireless Charge Electric Mine Vehicle

Dr. Steve Mitchell

26th Mechanical Engineering Safety Seminar : 3 - 4 August 2016

Presenter Background

• Presently : Engineering Manager at Ampcontrol CSM • Formerly: Academic at the University of Newcastle • Research focus on electric power systems for power,

mining and heavy industry sectors • Investigated the viability of wireless charge technology

in mining applications on behalf of CRCMining in 2014

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ENERGY AND POWER RESEARCH PROGRAM

• A key program within CRCMining • Mission: The electric mine • Electric machines provide:

• High operating efficiency • High reliability • Zero particulate emissions

• Therefore the electric mine will facilitate: • Reduction in emissions • Reduction in energy consumption • Reduction in mining costs

WIRELESS CHARGE ELECTRIC MINE VEHICLE

• Project sponsors were: • Anglo American • Barrick Gold • Caterpillar • Joy Global • Sandvik

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Background – Underground Mining

• Hard rock => Metalliferous – Drill and blast

• Soft rock => Coal – Long wall mining – Continuous mining

– Explosive atmospheres

Today’s Underground Mining Vehicles

• Diesel powered vehicles – Load Haul Dump (LHD) – Trucks

– … • Trailing cable

– Shuttle car – Drill – ..

– Utility (e.g. Land Cruiser)

Today’s Underground Mining Vehicles

• Battery Change-out – Battery hauler – Coal Scoop – …

• Connector brushes – Dump truck – Train – …

Today’s Underground Mining Vehicles

• Range of trade-offs associated with power systems and their application in U/G vehicles

Diesel powered vehicles • Highly mobile and versatile • High energy density fuel

– 36MJ/litre – Long range/duty between refueling

• Poor energy efficiency – Typical energy efficiency of 37%

• High routine maintenance cycle • Diesel particulate emissions

– 2012 diesel exhaust classified as Group 1 carcinogen

A problem with diesel…

• The key motivation to move away from diesel powered vehicles is health

• Epidemiological studies specific to U/G mining demonstrated an increased risk of lung cancer due to DPM exposure

• Legal precedent in Canadian Superior Court – 2013 recognised the lung cancer of deceased miner

as an occupational disease despite no evidence to prove that the mine had exceeded exposure regulations

In addition…

• A second motivation to move away from diesel powered vehicles is ventilation costs

• Ventilation in underground mines is required for to: – Dilute and remove dust and noxious/explosive gases – To regulate temperature due to geothermal inputs and

machinery operation • Ventilation currently accounts for up to 40% of a

mine’s energy needs • Infrastructure costs for ventilation are significant

Ventilation requirements for diesels

Jacobs 2013

Hydrogen Fuel Cell Power System

• Generating significant interest as a potential replacement for fossil fuels

• Polarising technology with as many proponents as opponents – Nissan and Tesla are stanch critics – Toyota released the fuel cell hybrid “Mirai” in 2014

• Very enticing properties of high energy densitywith zero emissions

• Significant energy cost with each stage in the process

Fuel Cell versus Electric

Bossel 2006

Hydrogen Fuel Cell Power System

• Introduces challenge of maintaining safety whilst importing hydrogen into confined space.

• Fuel cell powered LHD and U/G Locomotive projects utilised metal hydride storage in order to chemically lock up the hydrogen

• Significant complexity, cost of the fast fill metal hydride storage system, poor conversion efficiency

Electric vehicle - Trailing cable

• No refuel/recharge • High efficiency electric machines • No emissions • Range limited • Limit to the number vehicles/section • Vulnerable to cable damage due to impact,

abrasion, tensile stress, fatigue – Arcing incidents in hazardous areas (average 1 per year, per mine in NSW 2008-2012)

• Logistics to shift machine between sections – Diesel vehicle tow between sections

Electric vehicle - Battery interchange

• High efficiency electric machines • No emissions • Battery change-out overhead leads to reduced

availability – 3 Battery carousel (Battery/shift)

• Very large battery system to maximise kWhr – Typically lead-acid – Long-Airdox CHA818 Un-a-Hauler = 7880kg…

• Battery change-out not readily conducive to future automation

Electric vehicle - Connector brush

• High efficiency electric machines • No emissions • Significant infrastructure costs • Vulnerable to damage due to impacts • Brush sparking => not suitable for explosive

atmospheres • Multi-vehicle use challenges (ie passing)

Electric vehicle - Connector brush

• Eg. Kiruna electric truck

Proposal: Wireless Charge Mining Vehicle • Promote the development of a wirelessly

charged underground mining vehicle system • Create technology to charge U/G mining

vehicles dynamically whilst they are in production

Wireless charge benefits

• No battery change-out • No trailing cables • No connector brushes • No particulate emissions • Immunity to dirt and water • Electrically isolated • Significantly reduced battery requirement • Ideal for future automation

The technology…

• Magnetic Resonant Coupling • Basic premise is similar to that of a

transformer • Power delivered between a coupled

transmitting and receiving coils • Poor transformer since in air (not iron core) • To maximise power transfer efficiency the

transmission is at a tuned resonant frequency

Technology origins

• The origins of this approach => Nikola Tesla • Tesla was fascinated by all types of resonance

• Tested the resonance of steel buildings in the 1890s resulting in “panic stricken steel-workers…”

• His electrical resonant transformer circuit (Tesla Coil) was invented around 1891

The technology…

• Both the transmitter and receiver coils are capacitively loaded to form tuned LC circuits with a common frequency – Efficient energy transfer over distances up to a

few coil diameters • The magnetic field is shaped with ferrite cores to

maximise energy transfer efficiency • Faraday’s Law

– Higher frequency – Higher the induced voltage – Better transfer efficiency.

The technology…

• However … in the MHz range – Skin and proximity effects become problematic

=> losses – Inverter IGBT switching efficiency dramatically

decreases • Human EM Exposure Limits

– Passive shielding used to keep the magnetic field exposure to international limits

– Example: < 2 μT (KAIST Campus bus)

The technology…

The All-Electric Car You Never Plug In - IEEE Spectrum 2013

Current state of the art

• Typically 20kHz – 120kHz range • In the past decade there has been significant

advances in wireless charging • Efficiencies of >80% demonstrated with 20cm

air gap (and continuing to improve) • Power transfer to buses of 180kW (suitable

for loaders/scoop vehicles)

KAIST campus bus

• 2012 Korea Advanced Institute of Science and Technology(KAIST) introduced Online Electric Vehicle

• 3.7km circuit around the campus • Charging whilst in motion • Dynamic charging stations 5 - 20% of journey

KAIST Fast train

• KAIST are also currently working on wireless charge fast train

• Train would require MW transfers • Current fast trains are speed limited by the

pantograph • This limitation and brush wear are eliminated

by wireless charge inductive coils

Eg: Mining wireless charge concept

Limitations/Applications

• Currently would be restricted from use in explosive atmospheres – AS/NZS 60079.0 => 6W for 9kHz – 60GHz – However generated interest with mine safety

bodies both in the US and Australia..

• Suitable for many metalliferous applications – An ideal solution for Block Cave mining

=> Automated wireless charge LHDs….

Wireless charge technology • World Economic Forum listed wireless

electromagnetic transmission as one of the 10 mostpromising technologies of 2013

• Road Embedded Rechargers was listed by TimeMagazine as one of the 50 best inventions of 2010

• Toyota, Nissan and Honda scheduled to releasewireless charge technology cars in 2016

• Currently exponential growth in wireless charge busand tram projects in Europe, USA and Korea

• Multiple technology vendors with 1MW systems atplanning stage (for light and heavy rail projects)

Conclusion

• Significant advances within the past 10 years… Where will it be in another 5 years?

• The technology has now reached a tipping point and may have significant potential for mining applications

• No one in the mining space yet…

Questions?

Thank you