Rapid Growth Of Renewable Energy

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Renewable energy production and use has grown at an overwhelming rate – the acceptance and uptake of this technology has been greater than anticipated with countries continuing to set target dates for converting to 100% renewable energy [1].

At least 30 countries generate more than 20% of their energy from renewables, and 120 countries have policy targets for longer-term shares of renewable energies. The European Sustainable Energy Vision outlines the transition of the energy supply and demand for the 27 EU countries to 100% renewable energy by 2050 [2] which was then revised to 2040 [3].

By the end of 2015, 23.7% of energy came from renewable sources: 16.6% from hydro power; 3.7% from wind; 2% from biomass; 1.2% from Photo Voltaic (PV) and 0.4% from geothermal, concentrated power and ocean [4].

Figures 1 and 2 show that solar PV has the highest growth rate, however recently large scale CSP has been gaining a lot of attention, and per kw, wind power has the fastest growth [4].

renewables figure 1

Figure 1: Average Annual Growth Rates of Renewable Energy Capacity and Biofuels Production, End-2010 to End 2015 [4]

A number of challenges arise with the use of renewable energies. Firstly, energy is not ‘on demand’ and therefore may not always be available when required. This issue is more pertinent in terms of a source like solar, which is only available during sunlight hours. The practiced solution to this problem is simply to have a combination of different power generation sources, such as those listed in Figure 2.

An important fact to note is that with the exception of solar PV (which creates DC through the photovoltaic effect), renewable sources create power through the use of a generator which is driven by a prime mover. The prime mover can be wind, steam from

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concentrating solar thermal, hydro, geothermal, ocean from currents/waves, or biomass.

renewables figure 2

Figure 2: Renewable energy indicators [4]

A second challenge with renewable energy is the land size required to sustain the planet’s energy needs. For a move to 100% renewable energy every step must be taken to design the  smallest footprint. To do this energy systems must be designed to be as efficient as possible. The generator is no doubt a key factor in these systems and should be designed and retrofitted to meet the prime mover’s needs.

Accepted facts about the most efficient generators are:

1.They use permanent magnets which leads to

  • High efficiency
  • Reduced copper losses associated with energising the rotor winding
  • Less heat generation
  • High torque density
  • Unity power factor
  • Very quiet operation

2. They use Interior Permanent Magnets (IPM) allows for flux focussing, meaning

  • High flux density
  • High power density
  • Low flux leakage
  • Robust structure
  • Easy heat dissipation

3. Removing electronics to obtain

  • Increased efficiency
  • Simpler design
  • High reliability

These are all concepts well-known to Radial Flux Laboratories (RFL), however, not satisfied with this, RFL is pushing the envelope by modelling and developing new configurations tailored to improving the efficiency of generators to integrate seamlessly with the renewable energy source.

Future posts will describe RFL’s sophisticated approach and design on developing generators that integrate with wind turbines, and the development of DC generators which have many advantages including combating harmonics produced by non-linear loads.

[1] Renewable Energy World. (2013). 100 Percent Renewable Vision Building [Online]. Available FTP: http://www.renewableenergyworld.com/articles/2013/04/100-percent-renewable-vision-building.html?amp%253bbuffer_share=fdc06

[2] International Network for Sustainable Energy. (2004). EU-25 Sustainable Energy Vision 2050 [Online]. Available FTP: http://www.inforse.org/europe/VisionEU25.htm

[3] International Network for Sustainable Energy. (2004). EU-27 Sustainable Energy Vision 2040 [Online]. Available FTP: http://www.inforse.org/europe/VisionEU27.htm

[4] Global Status Repot (2016). REN21 Renewable Energy Policy Network for the 21 Century [Online]. Available FTP: http://www.ren21.net/wp-content/uploads/2016/06/GSR_2016_Full_Report.pdf

Credit: Ezra Bowen

RFL’s Unique Design is Proving Extremely Valuable

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By the end of 2015, 23.7% of energy was delivered from renewable sources with 3.7% of the total worldwide electricity supplied by wind energy, which is growing at a rapid rate of 17% per annum.

Since 2011, the cost of wind generating infrastructure has fallen by 10%, making wind energy 14% cheaper than new coal and 18% cheaper than new gas.

There are a variety of electrical generators on the market for use in micro-wind turbine applications. These include induction and synchronous machines.

High-end machines use permanent magnet generators – they’re excellent because they eliminate the copper losses associated with rotor windings, making them far more

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efficient than induction and wound rotor machines. As such, these generators have gained interest in replacing conventional machines with Permanent Magnet Synchronous Generators (PMSG).

Until recently, wind energy converters have been designed for speeds from 750RPM up to 1800RPM, whereas wind turbines usually operate from 20RPM to 250RPM [3]. Consequently, a gearbox has been the link between the wind turbine and the generator. Gearboxes require maintenance, decrease efficiency, are noisy and are generally the first component to fail in the system.

By increasing the number of poles in the generator, the electrical frequency increases and the gearbox can be eliminated. PMSG are able to have a smaller pole pitch and therefore more poles as only the leakage flux between the two magnets sets the limitation.

Radial Flux Laboratories (RFL) has experience in modelling and developing machines utilising concentrated fractional windings which does not require an integer slot winding and hence allows for a higher pole count.

There are advantages with both an inner and outer rotor configuration which is generally designed around the application. An inner rotor (meaning the stator is on the outside) is the most typical design and is generally chosen as the majority of losses are contributed to by the copper losses within the stator. As a result, designing with the stator on the outside gives better cooling properties for a higher efficiency. Furthermore, having the stator on the outside allows for larger slots, and consequently a more efficient or higher rated machine.

A unique outer rotor design does bring a number of advantages though. For example, the larger rotor diameter allows for a higher number of poles, and the magnets stay cooler so the likelihood of demagnetisation is reduced. Additionally, the hub allows for the blades to be directly fixed to the rotor which results in a cheaper, simpler, and more integrated design.

Dual stator machines are now being considered for various motor and generator applications. The dual stator is incorporated in synchronous generators to increase the power capability.

Recently dual stators have been found to be useful as a part of uninterruptable power supplies, standalone power supplies, and generators of both ac and dc electric power [4]. Another advantage is the reliability of having a dual winding generator.

However, dual winding machines have also traditionally had the challenge of required heat dissipation associated with the inner winding. Recognising this, RFL has developed a unique design which transfers heat from both the inner and outer stator to the casing and cooling fins.

RFL has also optimised the mechanical structure, efficiency and thermal properties. This design shows promise in wind turbine applications, where the generator is required to be sealed for increased reliability and service timeframes.

As wind energy continues to grow it is paramount that wind turbines/generators are optimised for maximum efficiency and reliability. RFL has developed the most efficient and reliable generators on the market with the smallest footprint that can be tailored to meet the wind turbines design.

 

[1] Renewable Energy World. (2013). 100 Percent Renewable Vision Building [Online]. Available FTP: http://www.renewableenergyworld.com/articles/2013/04/100-percent-renewable-vision-building.html?amp%253bbuffer_share=fdc06

[2] C.Techies, “Renewables now cheaper than fossil fuels in Australia,” Environmental and Energy Study Institute, pp.1, Jan. 2013.

[3] M.Widyan, “Design, optimization, construction and test of rare-earth permanent magnet electrical machines with new topology for wind energy applications” in Phd Thesis. Berlin: Technical University of Berlin, 2006, pp. 16-76

[4] A.Dwivedi and R.K.Srivastava, “Analyses of Dual Stator PM Brushless DC Motor” in IOSR Journal of Electrical and Electronics Engineering (IOSRJEEE), Volume 1, Issue 2, pp 51-57

 

Credit: Ezra Bowen

RFL teams up with Eniquest

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Eniquest Case Study – “Compact, rugged and highly efficient generator sets”

Eniquest is an Australian leading manufacturing company that specialise in remote area power and independent energy solutions.  They provide quality, cost effective, reliable power production equipment for a variety of industries and applications.

The company is innovative and keen to adopt new efficient and environmentally responsible technologies and techniques for power production. Their systems use highly efficient technology providing a DC base with an AC inverter, and use technology that is widely recognised as the most efficient and safe way to produce and store electricity.  Eniquest have developed products that integrate with renewable energy devices to keep fuel usage to a minimum.

Eniquest has been providing reliable power distribution, providing DC Generators, AC Generators and Auxiliary Power Units to the Australian Military for over 10 years.  The relationship built with the Australian Military demonstrates Eniquest’s recognition of the need for reliable, compact and light weight power generation products. They have gained a reputation for providing power solutions that can perform efficiently and reliably in the harshest conditions.

Eniquest uses innovative power production technology to meet the ever growing industry challenges of today. Like Eniquest, RFL Alternators understand the evolving requirements of industry today and in the future and work to provide machinery that is more fuel efficient, more reliable and more innovative than currently available

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equipment.

RFL Alternators is a world class manufacturer of high quality permanent magnet RF2 AC2 pole series alternators which feature the powerful Magnetic Flux technology embedded in the permanent magnetic design.  The alternator is lighter in weight, has a 40% smaller footprint and is 92% more efficient than traditional wound rotor machinery.

 

The challenge

To further service the evolving needs and challenges faced by the Australian Military, Eniquest needed to source a highly efficient, robust and compact alternator to use in the manufacture of generator sets for military applications.

 

The solution

The highly efficient and compact design of the RFL alternator allowed the total generator set package Eniquest would provide to be much be smaller both in terms of size and weight.

The novel design and lack of any electronic components met the Military’s criteria for durability and the RFL Alternator is inherently compliant with MIL-STD-461 or electronic magnetic compatibility.

These qualities allowed Eniquest to service the Australian Military with technologically advanced 8kW and 16kW generator sets that meet their criteria for lower cost, low fuel consumption and superior reliability both today and in the future.

In collaboration Eniquest and RFL Alternators make a well matched team – utilising RFL’s lighter more efficient and rugged technology Eniquest would be able to provide the Australian Military with a superior, highly efficient and tough generator set to meet it’s ever growing needs.Eniquest workshop

PMSG technology supports the Army’s complex power requirements

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The array of electrically powered systems used in the military has expanded beyond anticipation over the past decade and is continuing to grow at an unprecedented rate.

Unfortunately, deployed power systems have not been upgraded to meet power requirements.  The Army has an extremely rapid, mobile, spontaneous and agile deployment, making its power solution requirements some of the most complex.

The Army currently relies on power generation from a series of wound rotor diesel generators ranging from single-phase 1.3kVA generators up to three-phase 60kVA generator sets.

The current scenario for an Army deployment is to work the ‘power planning’ around each mission, this dictates the power generation and distribution to be deployed. When the mission capability increases, larger generators are needed to handle increased loads. As the mission decreases, smaller generators are required to replace the larger ones in order to keep the generator load balanced.  This causes logistical problems and breaks the scalability and modularity requirements associated with an Army deployment.

A well-known constraint on three-phase generators is load balancing techniques. The Army has been known to deploy with load banks in order to keep three-phase generators balanced and maintain a reasonable load.  This is cumbersome to a mobile deployment force.

Permanent Magnets Synchronous Generators (PMSG) like those developed by RFL Alternators have significant advantages over the conventional wound rotor generators. Firstly, load balancing. Although load balancing is recommended for PMSG technology and should be practised, it does not bear the importance that it does on traditional wound rotor generators, and certainly does not need to be as closely balanced.

Perhaps the most significant advantage with the PMSGs is they can be paralleled. This

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eliminates the need for significant power planning. A “one size fits all” generator can be deployed, take for example an 8kVA generator that could run the minimal load, as the mission capability grows a second generator is paralleled, and so forth and so on. The reverse action happens as the mission capability is reduced. Generator paralleling brings with it a number of advantages including:

  • Reliability
  • Scalability
  • Ease of maintenance
  • Reduction of light loading on the prime mover
  • Reduction is cost of per Kw

Due to power demands in vehicle mounted configurations, recently the Army has been fitting vehicles with an Auxiliary Power Unit (APU). This APU has been a DC PMSG, which was chosen for two main reasons. Firstly, it eliminates the need for the vehicle to comply with strict high voltage standards and secondly, nearly all electrical equipment runs off DC voltage, so the need for rectification and voltage step-down is eliminated thus saving efficiency.  To meet these demands RFL Alternators have recently developed highly efficient DC PMSGs, which have an optional 24VDC and 48VDC output.

RFL generators are designed with an embedded permanent magnet synchronous generator using neodymium magnets. This clever design leads to highly efficient robust generators. They are smaller in size and lighter in weight than traditional wound generators and don’t have the need for complex electronic components – this dramatically increases reliability.

Our next post will reflect upon RFL Alternators have teaming up with an Australian company specialising in remote area power and independent energy to provide rugged and reliable generator sets to the Australian Army.

Electric Vehicle technology and the role of Permanent Magnets

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European legislation to phase out vehicles equipped with the internal combustion engine has led to a shift in the market – making way for Electric Vehicle technology to be embraced.

Permanent Magnet BLDC drives have been identified as the most promising technology to provide the attributes required for modern Electric and Hybrid Electric Vehicles.

Awareness of environmental problems is growing dramatically throughout the world. This is leading to a tremendous interest in developing non-polluting Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV).

Vehicles equipped with the traditional Internal Combustion Engines have been in existence for over a hundred years. Although ICE vehicles have been improved by modern automotive electronics technology, they only offer around 20% efficiency [1]. Electric vehicles are one of the most promising technologies that can lead to significant improvements in vehicle performance, energy utilisation efficiency, and emission reductions.

Multiple countries have already acted on enforcing a ban on combustion engines, initially led by Norway for 2025. Other European countries include Sweden, France, Germany, Belgium, Switzerland and the Netherlands whom are considering a phase-out by 2030. This is not only in order to cut CO2 emissions but also to reduce the European Union’s (EU) dependence on Russia. Outside of the EU, phase-out of ICEs also seems likely in Japan which is home to the world’s top-selling electric car, the Nissan Leaf [2].

Electric Vehicles and Hybrid Electric Vehicles have been identified to be the most viable solution to address the problems associated with the internal combustion engine. Electric drivers are the core technology for Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs). These vehicles need to meet a number of requirements to be competitive in the automotive field, including: interior comfort, extended range, efficiency, low cost, reliability, and low maintenance [3]. These requirements lead to developing smaller efficient and higher-output motors. The basic characteristics of an electric drive for Electronic Vehicles are [4]:

  • high torque density and power density;
  • very wide speed range, covering low-speed crawling and high-speed cruising;
  • high efficiency over wide torque and speed ranges;
  • wide constant-power operating capability;
  • high torque capability for electric launch and hill climbing;
  • high intermittent overload capability for overtaking;
  • high reliability and robustness for vehicular environment;
  • low acoustic noise;
  • reasonable cost

 

The technologies of all component hardware are technically and markedly available on the market. At present, almost all of the major automotive manufacturers are developing either HEVs or fully EVs.

There is a large variety of electric motors that come in a number of topologies, the key being to balance high efficiency, reliability, and Size Weight and Power (Swap). Presently the three most common topologies used in EVs are Brushed DC, Brushless DC (BLDC), and AC induction.

With the advent of high-energy permanent-magnet (PM) materials, PM motors are becoming increasingly attractive. Being continually fuelled by new machine topologies and control strategies, PM BLDC drives have been identified to be the most promising to provide the characteristics needed for modern EVs and HEVs.

PM motor drives have the magnetic field excited by high-energy PMs. This means the overall weight and volume can be significantly reduced for given output torque, resulting in higher torque density, very quiet operation and almost never requiring any maintenance. Because of the absence of the rotor winding and associated rotor copper losses, their efficiency is inherently higher than that of induction motors and do not have the added concern of removing heat generated in the rotor by copper losses. Induction motors need a low pole number (two or four) which requires large copper end windings and considerable

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stator back iron. This results in a larger and heavier machine [3].

In recent years, attention has been drawn to Interior Permanent Magnet (IPM) synchronous motors. This is due to their simple structure, robust configuration, high power density, easy heat dissipation, and suitability for high speed operations. The IPM motor takes advantage of flux focusing, which is performed by angling the magnets to gain a higher flux density in the air-gap than that of the PM flux density. The IPM topology has the highest power density and highest efficiency among all types of motors. Through flux focusing flux leakage is minimised up to as much as 20%. Furthermore, IPMs have a more robust rotor than that compared to other PM motors without the need of additional retainment and lower cost rectangular magnets [4] [5].

Regenerative braking can be considered a requirement in EVs it can increase the vehicle range by up to 15% [6]. Regenerative braking is easier with a PM motor because the magnets do not need to be energised. This results in less rotor heat generated with PM motors compared with induction motors which require a well-suited cooling system [7]. This gives PM motors a higher efficiency for the amount of kinetic energy that can be recovered. Without the rotor winding PM motors also produce a unity power factor. It is however noted that attention must be given to demagnetisation of higher continuous temperatures in PM motors, when designed with NdFeB magnets [7].

Legislation throughout Europe has begun to force EV into the market, and it is expected that most of the world will follow suit. This is leading to a large production of EVs. Currently IPM motors have the highest efficiency, smallest size, lowest weight and are the most efficient in recovering the vehicle’s energy in the form of regenerative braking. Due to high efficiency and smaller lighter motors, the vehicle will have an extended range on the same size battery bank.

Electric Vehicles will also play a major role in the dynamics of how we generate, store and use energy in the future.

Electric Vehicles provide an added benefit to existing energy grids – Off Peak Recharging. An EV can be recharged during the night, when the energy demand on the grid is low. This is similar to the off-peak tariff used to heat residential hot water systems.

As we move towards a more distributed generation model in the future, the additional storage capacity of an Electric Vehicle has significant potential.  Peak demand as mentioned above can be capped, and we will have the ability to consume energy at off-peak times, thus removing the expensive energy peaks currently experienced.

[1] C. R. Ferguson and A T Kirkpatrick, Internal Combustion Engines: Applied Thoermosciences, Third Ed, Colorado University. John Wiley & Sons Ltd, 2016, pp. 2.

[2] Pedestrianobservations. (2016). Several European Countries to Follow Norway’s Lead, Ban Fuel-Powered Cars [Online]. Available FTP: https://pedestrianobservations.wordpress.com/2016/04/01/several-european-countries-to-follow-norways-lead-ban-fuel-powered-cars/

[3] M. Ehsani and Y. Gao, “Hybrid Electric Vehicles: Architecture and Motor Drivers” in Proceedings of the IEEE, Vol. 95, 2007, pp. 719-728

[4] K. T Chau and C.C Chan, “Overview of Permanent-Magnet Brushless Drives for Electric and Hybrid Electric Vehicles” in IEEE transaction on industrial electronics, Vol. 55, 2008, pp. 2246-2257

[5] J.R.Hendershot, “MotorSolve analysis of the 2010 Toyota Prius Traction Motor” 2015

[6] J.Cody and O.Gol, “Regenerative braking inn an electric vehicle” in Zeszty Rplemowe – Maszyny Elektryczne, Vol. 81, 2009, pp. 113-118

[7] R.Rapter and M.Prathaler, “Regeneration of Power in Hyrbid Vehicles” VTC 2002, pp. 2063-2068

Makinex

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Reliable mobile power – anywhere anytime

 

“Part of the design for the mobile Makinex Generator sets required sourcing the right light weight components which were robust, reliant and had the grunt when needed. RFL Alternators worked closely with Makinex to provide technical guidance and expertise and continues to be valuable partner to the business”, says Rory Kennard, Managing Director of Makinex.

 

Generator sets need to tackle head on the demands of dusty worksites, harsh environmental conditions, remote locations, restricted access and handle varying output requirements anywhere at any time. This is a tough ask and demand is growing as smart thinking tradespeople and contractors are being rewarded by utilising efficient processes and equipment, which save them both time and money.

Makinex is an industry leading expert in designing and developing innovative product solutions for the construction, landscaping, equipment hire, and infrastructure industries. Working closely with local and National businesses Makinex creates unique, innovative and practical product solutions that provide contractors and tradespeople with a better way to do their jobs to save time, physical effort and money.

 

The situation/challenge

A reliable power source to equipment and tools is daily critical and flexibility is needed to a wide range of applications; whether it be lighting, appliances, tools, air conditioners, welders or brick saws and a generator set needs to be demand ready.  Even moving equipment on and off vehicles, OHS manual handling guidelines must be adhered to and weight becomes a major consideration when selecting the right generator set.

Makinex understood these challenges and set about designing a portable generator range which was lightweight, easy to move around, reliable and efficient to run. The current market had models which often encountered electronic failure and were not portable.

Part of the design required sourcing the right light weight components which were robust, reliant and had the grunt when needed. RFL Alternators specialises in and is well-known for its expertise in guiding and providing cost benefit ground-breaking alternator solutions, and subsequently Makinex and RLF Alternators teamed up.

 

The outcome/solution

RFL Alternators, a world class manufacturer of high quality permanent magnet RF2 AC 2 pole series alternators which features the powerful Magnetic Flux technology embedded in the permanent magnetic design. Rather than the traditional wound rotor with permanent magnet end, this new design allows the length of the rotor to reduce significantly. Consequently, the alternator is lighter in weight, has a 40% smaller footprint and 92% more efficient, providing Makinex the ideal component to be integrated into their new compact petrol and diesel 7 – 16 kVa generator set range.

Jason Clegg, Managing Director RFL says “the new permanent magnet alternators use strong rare earth Neodymium magnets, the most powerful commercial type of magnet available today, and with no electronics we see no failures. We will proudly continue to partner with Makinex to assist them in expanding their state-of-the-art portable generator range”.

The petrol driven 7kVa, 10kVA and 16kVA and 9kVa diesel Makinex generator set range was designed with high quality components such as a petrol or diesel engine, alternator and power outlets to make up the generators and are fixed within a heavy duty, but lightweight galvanized steel frame to enable the unit to easily be moved around. Featuring, single and 3 phase outlet capability; 15% more engine efficiency; along with the ability to provide either 240V single phase or 415V three phase power, as well as meeting industry safety standard regulations, you can feel confident your equipment will feel the power.

“The smart portable generator range is more versatile than ever, with the ability to join and synchronise generator sets to give more power when needed says Rory Kennard, Managing Director of Makinex. This is due to the high performing RFL alternator which uses an integrated basic phase matching control mechanism”.

The market now has a performance driven generator set solution, which is unsurpassed in both reliability and quality with capabilities to withstand harsh workplace environments.

 

Makinex Generator 10kVA set fitted with an RFL RF2-12.5 alternator- model powering two compressors simultaneously. The RFL Alternator uses ground-breaking Magnetic Flux technology and enables a powerful compact design.

 

Makinex generator 10kVA

Two Makinex Generator 10kVA sets operating in parallel to power a three phase concrete polisher. RFL Alternator incorporated in the design using ground-breaking Magnetic Flux technology.

 

Makinex generator 10kVA

 

 

Makinex Generator Set – Petrol driven 7kVa, 10kVA and 16kVA and 9kVa diesel range – RFL Alternator incorporated in design using ground-breaking Magnetic Flux technology.

 

Makinex generator set

 

 

Case Studies

RFL Alternator versus Kubota Alternator

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A comparison on the Kubota D722 Diesel Engine (Kubota GL9000 GenSet)

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RFL alternators

Unbalanced Loads

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For efficiency and maximum performance 3 phase alternators are the most common alternators on the market, however due to the very nature of the design they are required to work at a balanced load. Unfortunately, it is almost impossible and unrealistic to run 3 perfectly balanced loads. Any variation on any of the loads will cause unbalance in the alternator. An unbalanced load can cause a number of unwanted effects on a alternator which can in-turn affect the load.

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RFL alternators

Generator Paralleling

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The world is becoming more reliant on electrical power. Electrical power is required for a primary source of energy, back-up systems, military deployment and disaster relief. As technology increases the power demand grows, and systems can-not afford to go offline.

This drives the requirement to have larger and more reliable generators. Larger generators become unpractical and a single point of failure is evident. RFL have developed Interior Permanent Magnet Generators (IPMG) that are designed to allows a series of generators to run in parallel.

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RFL alternators

Unbalanced Loading Behaviour

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Abstract —Portable AC generators directly driving isolated AC loads require tight voltage regulation, good voltage waveform quality and high efficiency. This paper studies the performance of a 4 pole, 16 kW interior permanent-magnet generator under balanced 3ph and unbalanced 1ph resistive loading conditions. For the unbalanced 1ph condition, the use of star and delta winding connections is compared. The results of analytical and finite-element simulations have been compared with experimental results.

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