Top Ten Challenges – Energy Storage

Thinking about the top challenges we face in mechatronics there is one that’s connected and not really obvious.  It’s energy storage.   Our tendency is think in terms of batteries because that’s the form of energy storage that we are most familiar with.  Cell phones, laptop computers and many other portable gadgets of the Internet Age are very dependent on energy storage systems for their size, weight and hours of service.  But of course, these are all battery applications.

So  our first reaction to energy storage as a mechatronic challenge  might be that it’s really just a chemistry problem and not mechatronic at all.  But energy storage comes in many forms and applications.  Energy storage is a requirement of almost every form of energy and control systems.  Hydraulic and Pneumatic systems require accumulators to store energy so that short term loads don’t use up enough power to make the system unable to respond to demands placed on them.  Energy rate over time is a governing principle in all these systems.

The initial linkage in my thinking was the electric car.  As someone who worked in the electric car field many years ago, it was that the battery that killed the electric car.  Carrying 2200 pounds of lead acid batteries to make a car go from here to there simply didn’t make sense.

There has been a lot of debate on that subject and a LOT of incomplete information offered which clouds our understanding of the social or political problem.  But the cost and energy density of the battery pack is making sufficient progress to insure that quite a few new vehicle options will be available in 2010 and 2011.

In normal batteries energy densities of 30 Watt hours per kilogram of weight are common.  Nickel metal hydride doubled the energy density to about 80Wh/kg.  But the real improvements are coming from the lithium chemistries at 130+Wh/kg.  There are more dense chemistries around, but they are typically very high temperature or otherwise very expensive, and so not practical for widespread use.

But the energy storage problem is not limited to chemistry.  The flywheel energy storage system has been a topic of engineering development for decades.  Energy density in these systems is in the range of 100 to 130 Kilowatt hours per kilogram, a thousand times more power.

So why aren’t we working on that for cars?  It’s been done several times and never quite works out.  Chrysler had a prototype K type car with a Garrett flywheel system.  Couldn’t make it small enough to be cost effective.  And there were issues of life expectancy and failure modes due to the fact that flywheel was operating on magnetic bearings in a vacuum housing.

The national power grid has exactly the same problem at orders of magnitude more power.  If there is to be any hope of an intelligent national power grid, storage systems of this kind are needed to act as a buffer between demand and supply..   Solar power is only available when it is daylight and there are no clouds.  Wind power only happens when the wind is blowing.  This means that supply is intermittent over time.  So if there are big fleets of electric cars charging overnight, there have to be storage systems that can manage the energy storage requirement.

So mechtronic challenge #4 – Energy storage. Large and small, high efficiency and long term.

7″ High Resolution Widescreens from Maple Systems

Maple Systems’ Silver Series Graphic OITs include a 7 inch, 800×480 widescreen version. The HMI5070TH is raising the bar with its high definition screen. Compared to the 5.6″ and 5.7″ displays, the 7″ has the same panel cutout, 35 percent more screen area and 5 times the number of pixels-a sharper display with more room for data.

Other features of the display:
-4-wire analog resistive touchscreen
-400 MHz fanless cpu
-128 MB flash, 64 MB DRAM
-USB & Serial Ports(optional ethernet)

Maple Systems
www.maplesystems.com

Animatics Corp. Publishes New Motion Systems Catalog

Animatics Corporation has published a new 145 page catalog on their expanded line of Motion Systems Products and Peripherals. This comprehensive catalog includes eight product segments fully detailing SmartMotor™ specifications, FieldBus Protocols, Brake Options, Connectivity, Peripherals, Power Supplies, Gear Heads, and Software.

Included is an expanded, dynamic fold out selection chart comparing all the different SmartMotor frame sizes and lengths. Torque curves are now presented at three different input voltages with superimposed, easy-to-read power curves to help optimize use of the increased SmartMotor power for your application.

A new section includes Application Examples illustrating the numerous SmartMotor product features and capabilities. Design guides and conversion charts make the catalog an essential application development tool.

Also featured is information on the Animatics Institute which offers in-depth training programs covering SmartTechnologies™ and Sales and Marketing strategies for Smart products and systems.

Animatics Corporation
www.animatics.com

Control, Motors and Efficiency

I was talking with some friends about control technology and made the observation that over the last decade the progress in the control field has been really amazing.  Particularly, the processor technology that is available for controlling electric motors is operating 1000 times faster than the control platforms of a decade ago.  We look at events in nanoseconds, not microseconds.

Increasing the control system’s frequency response is not signficant in itself.  But it does mean that software can be applied to problems that are more subtle in the operation of a particular system.  Observation of the phase relationship between the rotor and stator in an electric motor is now commonplace in 3 phase systems.  Algorithms for optimizing this relationship dynamically are also commonplace to adjust the power factor or reduce energy consumption in inertial loads like fans.

But this is not where the big energy gains will come from.  These improvements are smaller and more incremental.

Variable speed motors are systems that are made up of electric motors and power electronic systems.  Both are subject to losses in the form of heat.  In the motor bulk magnetizing of the stator, phase loss due to load, and copper losses due to the construction methods used are common.

Better metallurgy is needed to reduce losses associated with magnetizing the stator core.  The steel industry has attempted to address this issue, but the high cost of exotic alloy laminations prevents the advanced materials from becoming widely used.

Copper loss is improved in the segmented stator, but this manufacturing technique is most often found in more expensive servo motors, even though analysis suggests the cost is lower.  This may have to do with scale effect, since the servo motor world runs at much lower volumes than the AC motor world.

The other major dependency in the speed control is the power semiconductor.  The costs for power devices are falling and performance is improving.

So where are the big efficiency gains going to come from?

The control system strategy.  If the application is not well regulated you might be able to get a big increase in efficiency by measuring things more carefully.  In a cooling tower changing from a +/- 10 degree thermostat to a +/- 1 degree thermostat allowed me to implement a control system that reduced the energy consumption sufficiently to pay for the equipment in less than two years.

No new technology motor, nothing special about the variable frequency drive.  Just what was available at the time.  The big difference was the strategy.  Measuring what was important and organizing everything in the control system to achieve our objective.

Stäubli Robotics Announces Next Generation Robot Series

Stäubli Robotics announces the introduction of the new TS series of high speed SCARA robots. This next generation robotic line features 100% Stäubli design and engineering, and are among the fastest commercially available SCARA robots in the industry. Stäubli’s high performance benchmarks of speed, rigidity and precision are exemplified by this series which includes the TS40, TS60 and TS80 with a range of 400mm, 600mm, and 800mm reach and a payload of up to 8kg. This represents a 30% increase in performance and higher inertia capabilities over the previous RS series of robots.

All TS series robots feature four-degrees of freedom, a hardened plastic external housing and electric servo-driven motors for reliability. These robots utilize the CS8C controller which features a compact lightweight design and is the most technologically advanced controller ideally suited for applications that require complex process control. The CS8C utilizes the VAL3 programming language which is perfectly adapted to robotics and features numerous possibilities to communicate with the outside world including several different Fieldbus options, Ethernet, ModBus, and an offline programming software package (SRS) for ease of integration and use.

The TS series is highly adaptable and well suited for a wide variety of high speed and precise applications including pick and place, material handling, packaging, assembly, loading, testing, and dispensing. These new robots increase productivity and throughput without giving up valuable floor space making them ideal for food, pharmaceutical / medical device, PV, automotive, electronics, and many other industrial market segments.

“The new high speed TS series robots are the next generation of SCARA robots reinforcing Stäubli Robotics as the leaders in innovation.  This new SCARA series is best in class in regards to speed, reliability, and precision – offered at a competitive price.” says David Arceneaux, Operations Manager-Assistant Division Manager at Stäubli Robotics”.

Today, Stäubli offers the widest range of 4 and 6 axis robots from 0.5kg to 250kg payload and from 220mm to 3500mm reach, all controlled from a common control platform.

New EPSON RS3 Robot

Rosemont, IL — EPSON Robots introduces the new EPSON RS3 Robot, featuring all the benefits of a typical SCARA plus more. The unique new design of the EPSON RS3 clearly puts it ahead of other robots in its class with superior cycle times and larger work envelope access thus opening up new application possibilities.

“Unique to the EPSON RS3 is our new work space design which maximizes work envelope usage” stated Michael Ferrara, Director of EPSON Robots. “No other robot vendor offers a 350mm SCARA arm featuring the largest working quadrangle greater than that of a typical 750mm SCARA arm. Since there is no dead space in the center of the work envelope, the EPSON RS3’s largest working quadrangle is 494mm x 494mm, which up till now has only been possible with a much larger SCARA robot. With the ability to maneuver back under itself for the shortest movements possible instead of having to move around itself, the EPSON RS3 delivers superior cycle rates. This means more parts processed in less time, while using a fraction of floor space which results in more profits for our customers.”

The EPSON RS3 is literally a zero footprint robot, thus saving our customers valuable floor space. It is also capable of easy integration into compact assembly cells. Furthermore, the unique work envelope allows for unprecedented design flexibility with over 360 degrees of axis rotation for omni directional access. All these exclusive features make the EPSON RS3 robot the most versatile and unique SCARA available in the market today.

The EPSON RS3 is perfect for lab automation and other process heavy applications where large quantities of parts are presented to process or testing stations.

EPSON Robots
www.robots.epson.com/rs-series.htm

Energy

Everyone has an opinion about Energy Policy.  Just ask.  They’ll tell you!  And I am glad for the fact that there is a lot of discussion taking place.  We need good dialog and good information.

We might be a little lacking on the information side.  Nuclear power for generating electricity is not a popular topic, but worse yet, no one seems to want to talk about pebble bed reactors.  Pebble bed reactors have been around for over 25 years and represent the most stable path for producing electricity without burning fuel.  Small spheres of an enriched radioactive material are encapsulated in a ceramic insulator so that the nuclear fuel cannot accidentally achieve critical mass.  The same property of the geometry causes the “pebbles” to achieve high enough temperature to heat steam and generate electricity, but reaches thermal equilibrium at 800 degrees remaining stable without coolant.  So there can’t be a meltdown.

This makes atomic energy safe enough to locate in a major city without fear of a metldown or a chain reaction, the two weaknesses of conventional nuclear powerplants.  The fuel is encapsulated in carbide and graphite materials with processes that are very difficult to circumvent.  And because of the simplicity of the design, these reactors are lower cost than the water cooled reactors.  Could we save the environment and satisfy our energy needs at the same time?  Maybe so.

But this conversation is not part of the energy plan for the US.  Neither is drilling off the US coastlines and putting American workers back in the business of supplying our oil and gas needs in the US.  That makes no sense. The oil industry chose to import gasoline directly from the middle east 30 years ago because it was cheaper.  But we have done nothing to update our supply chain since then, and now we have to buy oil from countries that don’t like the US.

The logic seems to be about reducing our energy consumption instead of increasing our energy production.  Using less is fine until it cuts into our ability to produce necessary goods like electronics.  We don’t need to hobble the largest sector of the economy by telling semiconductor companies that we have to turn off electricity to their plants during the summer months.  They will have no choice but to locate to other countries.

You can’t “save” your way out of a recession.  You can’t save enough money to keep a company in business if it stops selling it’s products.  That’s all there is to it. And our policy leaders need to understand and apply that logic to the current situation.  The best thing to “stimulate” the US economy is to get it’s businesses producing.  Produce more energy with the resources that we have.

And when the car companies can make a competitive electric or hybrid vehicle, we will produce less gasoline and make more electricity.   There are plenty of opportunities to sell new cars to stimulate that industry too!

Electric Vehicles and Electric Motors

A friend of mine finally got delivery of a Tesla Roadster.  This prompted discussion of the drive train and the fact that Tesla has had to go from two speed transmissions which were failing to a transmissionless drive train.  The ultimate mechatronic challenge, the electric car, is also a challenger in terms of the precise  application of electric motor technology.

But it has to be said that the motor and drive solution for the electric car is not where the problem has to be solved.  Any motor can be made to run an electric car.  What is critical is how you apply it.  The starting conditions require high torque at low speed and the running conditions require low torque at high speed.  So, typically, what looks like a small 5 to 15 horsepower running requirement at full speed, becomes a 150 horsepower starting requirement depending on how quickly you would like to start.  If you want to keep up with a Corvette, it uses 450 HP to start.

And this produces a lot of confusion.  Why not use at 2 speed transmission to help the situation.  Fine, but the ones that are available can’t handle the dynamic response of the electric motor.

Can electronics help this situation?  Interestingly, yes.  There is a control algorithm generally called vector control which allows you to manage the rotor torque and stator torque separately.  By varying the phase angle between the two, like advancing and retarding the timing of a mechanical distributor cap on an internal combustion engine, you get different speed torque curves out of the motor.  COOL!  Is there any downside to this?

Yes.  You need more current to produce more torque.  That doesn’t change.  So you have to be able to supply the current, and you have to be able to manage the heat.  The heat is transitory since you only need the high current during starting, but it is best to have sophisticated software running to keep track of the RMS temperature of the motor.  Lower operating temperatures mean longer life and reduced risk of demagnetizing the motor.

So, yes, you can run an electric car with a garden variety AC motor, and with good electronics, you can make it run fairly efficiently.  With higher efficiency motors, the benefit is increased driving range from a given power source.  High efficiency motors are frequently smaller and lighter weigh, but a weight savings in the motor of 50 or even 100 pounds is not that big a factor in the driving range when the curb weight of the vehicle is 3000 pounds.

Basically, its F=ma.  If you can reduce the mass of the vehicle, you reduce the battery payload required to power the car.  Aluminum space frames, like on the Prowler, have been studied by the car industry and can reduce curb weight by 400 pounds and reduce cost by 10% at the same time.  We need to bring all the mechatronic leverage to the situation that we can, if we are going to make electric cars that make sense.  Before its too late for Detroit.