Powering automation and IIoT wirelessly

Battery-powered solutions are expanding the realm of industrial automation to virtually all external environments, enabling remote wireless devices to thrive throughout the Industrial Internet of Things (IIoT).

Figure 1: Lithium thionyl chloride (LiSOCL2) batteries either are wound spirally or of bobbin-type construction. The photo shows several LiSOCL2 batteries. Courtesy: Tadiran Batteries

Industrial automation no longer is constrained to the factory floor. With the help of wireless communications and advanced lithium battery technology, the landscape is expanding rapidly to incorporate increasingly remote and hostile environments.

The explosion of wireless technology has fueled rapid expansion of the Industrial Internet of Things (IIoT), allowing billions of wireless devices to become seamlessly networked and integrated while being liberated from the power grid. Battery-powered devices have brought wireless connectivity to virtually all industrial sectors, including process control, asset management, machine-to-machine, systems and systems control and data automation, transportation infrastructure, energy production, environmental monitoring, manufacturing, distribution, health care, and smart buildings, to name a few.

Critical to this growth surge has been the evolution of low-power communications protocols, such as ZigBeeWirelessHART, and LoRa (a long range, low power wireless platform), and related technologies that permit two-way wireless communications while also extending battery life.

For example, the highway addressable remote transducer (HART) communications protocol has been providing a critical link between intelligent field instruments and host systems for decades, employing the same the caller ID technology found in analog telephony and operating via traditional 4-20 mA analog wiring. However, in the past, requirements for hard-wiring severely restricted the deployment of HART-enabled devices due to high initial expense, as it costs roughly $100 per foot to install any wired connection, even a basic electrical switch. This cost barrier becomes far more problematic in remote, environmentally sensitive locations, where complex logistical, regulatory, and permitting requirements cause expenses to skyrocket. Development of the WirelessHART protocol has eliminated all these constraints.

Choosing the ideal power source

The vast majority of remote wireless devices are powered by primary (non-rechargeable) lithium batteries. In addition, certain applications are well-suited to be powered by an energy harvesting device in conjunction with a rechargeable lithium-ion (Li-ion) battery to store the harvested energy.

The more remote the application, the more likely the need for industrial-grade lithium batteries. Inexpensive consumer-grade batteries may suffice if the device is easily accessible and operates within a moderate temperature range. However, the cost of replacing a consumer-grade battery can far exceed the price of the battery itself, causing the total cost of ownership to rise dramatically. For example, imagine having to replace a battery in a seismic monitoring system sitting on the ocean floor or in a stress sensor attached to a bridge abutment.

Specifying an industrial-grade battery involves multiple parameters, such as energy consumed in active mode (including the size, duration, and frequency of pulses); energy consumed in dormant mode (the base current); storage time (as normal self-discharge during storage diminishes capacity); thermal environments (including storage and in-field operation); equipment cutoff voltage (as battery capacity is exhausted, or in extreme temperatures, voltage can drop to a point too low for the sensor to operate); battery self-discharge rate (which can be higher than the current draw from average sensor use); and cost considerations. Industrial-grade lithium batteries most commonly are recommended for applications that demand the following:

  • Reliability: The remote sensor is in a hard-to-reach location where battery replacement is difficult or impossible, and data links cannot be interrupted by bad batteries.
  • Long operating life: The self-discharge rate of the battery can be more than the device usage of the battery, so initial battery capacity must be as high as possible.
  • Wide operating temperatures: Especially critical for extremely hot or cold environments.
  • Small size: When a small form factor is required, the battery’s energy density must be as high as possible.
  • Voltage: Higher voltage requires fewer cells.
  • Lifetime costs: Replacement costs over time must be taken into account.

Tradeoffs often are inevitable, so it is important to prioritize your list of desired battery performance attributes.

Choosing among primary lithium batteries

Lithium battery chemistry is preferred for long-term deployments due its intrinsic negative potential, which exceeds that of all other metals. Lithium is the lightest non-gaseous metal, and offers the highest specific energy (energy per unit weight) and energy density (energy per unit volume) of all available battery chemistries. Lithium cells, all of which use a non-aqueous electrolyte, with a normal operating current voltage ranging between 2.7 and 3.6 V. The absence of water allows lithium batteries to endure more extreme temperatures.

Numerous primary lithium chemistries are available including lithium iron disulfate (LiFeS2), lithium manganese dioxide (LiMnO2), lithium thionyl chloride (Li-SOCl2), and lithium metal oxide chemistry (see Table 1: Primary lithium chemistry comparisons).

Table 1: Primary lithium chemistry comparisons

Li-SOCl2 Li-SOCl2 Li metal oxide Li metal oxide Alkaline LiFeS2 LiMnO2
Primary cell Bobbin-type with hybrid layer capacitor Bobbin-type Modified for high capacity Modified for high power Lithium iron disulfate CR123A
Energy density (Wh/1) ۱,۴۲۰ ۱,۴۲۰ ۳۷۰ ۱۸۵ ۶۰۰ ۶۵۰ ۶۵۰
Power Very high Low Very high Very high Low Low Moderate
Voltage ۳.۶ to 3.9 V ۳.۶ V ۴.۱ V ۴.۱ V ۱.۵ V ۱.۵ V ۳.۰ V
Pulse amplitude Excellent Small High Very high Low Moderate Moderate
Passivation None High Very low None N/A Fair Moderate
Performance at elevated temperature Excellent Fair Excellent Excellent Low Moderate Fair
Performance at low temperature Excellent Fair Moderate Excellent Low Moderate Poor
Operating life Excellent Excellent Excellent Excellent Moderate Moderate Fair
Self-discharge rate Very low Very low Very low Very low Very high Moderate High
Operative temperature -۶۷ to 185°F; can be extended to 221°F for a short time -۱۱۲ to 257°F -۴۹ to 185°F -۴۹ to 185°F ۳۲ to 140°F -۴ to 140°F ۳۲ to 140°F

Source: Tadiran Batteries

Consumer grade LiFeS2 cells are relatively inexpensive, and can deliver the high pulses required to power a camera flash. These batteries have limitations, including a narrow temperature range of -4 to 140°F, a high annual self-discharge rate, and crimped seals that may leak.

LiMnO2 cells, including the popular CR123A, provide a space-saving solution for cameras and toys, as one 3-V LiMnO2 cell can replace two 1.5-V alkaline cells. LiMnO2 batteries can deliver moderate pulses, but suffer from low initial voltage, a narrow temperature range, a high self-discharge rate, and crimped seals.

Li-SOCl2 batteries are manufactured two ways: spirally wound or bobbin-type construction (see Figure 1). Of the two, bobbin-type Li-SOClbatteries are better suited for long-life applications that draw low average daily current, such as tank level monitoring, asset tracking, and environmental sensors that must endure extreme temperature cycling.

Bobbin-type Li-SOCl2 batteries feature the highest capacity and highest energy density of any lithium cell, along with an extremely low annual self-discharge rate-less than 1% per year, enabling certain cells to operate maintenance-free for up to 40 years. Bobbin-type Li-SOCl2 batteries also feature a glass-to-metal hermetic seal, and deliver the widest possible temperature range (-112 to 257°F).

A prime example is the medical cold chain, where wireless sensors are used monitor the transport of frozen pharmaceuticals, tissue samples, and transplant organs at carefully controlled temperatures as low as -112°F. Certain bobbin-type Li-SOCl2 batteries have been demonstrated to operate successfully under prolonged test conditions at -148°F, which far exceeds the maximum temperature range of alkaline cells and consumer-grade lithium batteries.

Bobbin-type Li-SOCl2 batteries also are deployed in virtually all meter transmitter units (MTUs) used in AMI/AMR metering applications for the water and gas utility industry. The extended battery life of a bobbin-type Li-SOCl2 cell is essential to AMI/AMR metering applications because large-scale system-wide battery failures can create potential chaos by disrupting billing and customer service operations. Bobbin-type Li-SOCl2 batteries installed in MTU units during the mid-1980s were tested nearly 30 years later and shown to have plenty of remaining available capacity.

Battery operating life is largely influenced by the cell’s annual energy usage along with its annual self-discharge rate. Battery operating life can be extended further by operating the device in a standby mode that draws little or no current, then periodically querying to data to awaken only if certain preset data thresholds are exceeded. If properly conserved, it is not uncommon for more energy to be lost through annual battery self-discharge than through actual battery use.

When specifying a bobbin-type Li-SOCl2 battery, be aware that actual operating life can vary significantly based on how the cell was manufactured and the quality of its raw materials. For example, the highest quality bobbin-type Li-SOCl2 cells can feature a self-discharge rate as low as 0.7% annually, thus retaining nearly 70% of their original capacity after 40 years. By contrast, a lesser quality bobbin-type Li-SOCl2 cell can have a self-discharge rate of up to 3% per year, causing nearly 30% of available capacity to be lost every 10 years due to annual self-discharge.

Though bobbin-type Li-SOCl2 batteries are not created equal, performance differences may not become apparent for years. Thus, due diligence is required when specifying a battery for long-term deployment in remote applications. Engineers must look beyond theoretical data to demand fully documented long-term test results along with actual performance data from the field.


Sol Jacobs, Tadiran Batteries


Novel circuit design boosts wearable thermoelectric generators

Using flexible conducting polymers and novel circuitry patterns printed on paper, researchers have demonstrated proof-of-concept wearable thermoelectric generators that can harvest energy from body heat to power simple biosensors for measuring heart rate, respiration or other factors.

Because of their symmetrical fractal wiring patterns, the devices can be cut to the size needed to provide the voltage and power requirements for specific applications. The modular generators could be inkjet printed on flexible substrates, including fabric, and manufactured using inexpensive roll-to-roll techniques.

“The attraction of thermoelectric generators is that there is heat all around us,” said Akanksha Menon, a Ph.D. student in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “If we can harness a little bit of that heat and turn it into electricity inexpensively, there is great value. We are working on how to produce electricity with heat from the body.”

The research, supported by PepsiCo, Inc. and the Air Force Office of Scientific Research, was reported online in the Journal of Applied Physics on September 28th.

Thermoelectric generators, which convert thermal energy directly into electricity, have been available for decades, but standard designs use inflexible inorganic materials that are too toxic for use in wearable devices. Power output depends on the temperature differential that can be created between two sides of the generators, which makes depending on body heat challenging. Getting enough thermal energy from a small contact area on the skin increases the challenge, and internal resistance in the device ultimately limits the power output.

To overcome that, Menon and collaborators in the laboratory of Assistant Professor Shannon Yee designed a device with thousands of dots composed of alternating p-type and n-type polymers in a closely-packed layout. Their pattern converts more heat per unit area due to large packing densities enabled by inkjet printers. By placing the polymer dots closer together, the interconnect length decreases, which in turn lowers the total resistance and results in a higher power output from the device.

“Instead of connecting the polymer dots with a traditional serpentine wiring pattern, we are using wiring patterns based on space filling curves, such as the Hilbert pattern — a continuous space-filling curve,” said Kiarash Gordiz, a co-author who worked on the project while he was a Ph.D. student at Georgia Tech. “The advantage here is that Hilbert patterns allow for surface conformation and self-localization, which provides a more uniform temperature across the device.”

The new circuit design also has another benefit: its fractally symmetric design allows the modules to be cut along boundaries between symmetric areas to provide exactly the voltage and power needed for a specific application. That eliminates the need for power converters that add complexity and take power away from the system.

“This is valuable in the context of wearables, where you want as few components as possible,” said Menon. “We think this could be a really interesting way to expand the use of thermoelectrics for wearable devices.”

So far, the devices have been printed on ordinary paper, but the researchers have begun exploring the use of fabrics. Both paper and fabric are flexible, but the fabric could be easily integrated into clothing.

“We want to integrate our device into the commercial textiles that people wear every day,” said Menon. “People would feel comfortable wearing these fabrics, but they would be able to power something with just the heat from their bodies.”

With the novel design, the researchers expect to get enough electricity to power small sensors, in the range of microwatts to milliwatts. That would be enough for simple heart rate sensors, but not more complex devices like fitness trackers or smartphones. The generators might also be useful to supplement batteries, allowing devices to operate for longer periods of time.

Among the challenges ahead are protecting the generators from moisture and determining just how close they should be to the skin to transfer thermal energy — while remaining comfortable for wearers.

The researchers use commercially-available p-type materials, and are working with chemists at Georgia Tech to develop better n-type polymers for future generations of devices that can operate with small temperature differentials at room temperatures. Body heat produces differentials as small as five degrees, compared to a hundred degrees for generators used as part of piping and steam lines.

“One future benefit of this class of polymer material is the potential for a low-cost and abundant thermoelectric material that would have an inherently low thermal conductivity,” said Yee, who directs the lab as part of the Woodruff School of Mechanical Engineering. “The organic electronics community has made tremendous advances in understanding electronic and optical properties of polymer-based materials. We are building upon that knowledge to understand thermal and thermoelectric transport in these polymers to enable new device functionality.”

Among the other prospects for the materials being developed are localized cooling devices that reverse the process, using electricity to move thermal energy from one side of a device to another. Cooling just parts of the body could provide the perception of comfort without the cost of large-space air conditioning, Yee said.

Story Source:

Materials provided by Georgia Institute of TechnologyNote: Content may be edited for style and length.

New manufacturing process for SiC power devices opens market to more competition

Researchers from North Carolina State University are rolling out a new manufacturing process and chip design for silicon carbide (SiC) power devices, which can be used to more efficiently regulate power in technologies that use electronics. The process — called PRESiCE — was developed with support from the PowerAmerica Institute funded by the Department of Energy to make it easier for companies to enter the SiC marketplace and develop new products.

“PRESiCE will allow more companies to get into the SiC market, because they won’t have to initially develop their own design and manufacturing process for power devices — an expensive, time-consuming engineering effort,” says Jay Baliga, Distinguished University Professor of Electrical and Computer Engineering at NC State and lead author of a paper on PRESiCE that will be presented later this month. “The companies can instead use the PRESiCE technology to develop their own products. That’s good for the companies, good for consumers, and good for U.S. manufacturing.”

Power devices consist of a diode and transistor, and are used to regulate the flow of power in electrical devices. For decades, electronics have used silicon-based power devices. In recent years, however, some companies have begun using SiC power devices, which have two key advantages.

First, SiC power devices are more efficient, because SiC transistors lose less power. Conventional silicon transistors lose 10 percent of their energy to waste heat. SiC transistors lose only 7 percent. This is not only more efficient, but means that product designers need to do less to address cooling for the devices.

Second, SiC devices can also switch at a higher frequency. That means electronics incorporating SiC devices can have smaller capacitors and inductors — allowing designers to create smaller, lighter electronic products.

But there’s a problem.

Up to this point, companies that have developed manufacturing processes for creating SiC power devices have kept their processes proprietary — making it difficult for other companies to get into the field. This has limited the participation of other companies and kept the cost of SiC devices high.

The NC State researchers developed PRESiCE to address this bottleneck, with the goal of lowering the barrier of entry to the field for companies and increasing innovation.

The PRESiCE team worked with a Texas-based foundry called X-Fab to implement the manufacturing process and have now qualified it — showing that it has the high yield and tight statistical distribution of electrical properties for SiC power devices necessary to make them attractive to industry.

“If more companies get involved in manufacturing SiC power devices, it will increase the volume of production at the foundry, significantly driving down costs,” Baliga says.

Right now, SiC devices cost about five times more than silicon power devices.

“Our goal is to get it down to 1.5 times the cost of silicon devices,” Baliga says. “Hopefully that will begin the ‘virtuous cycle’: lower cost will lead to higher use; higher use leads to greater production volume; greater production volume further reduces cost, and so on. And consumers are getting a better, more energy-efficient product.”

The researchers have already licensed the PRESiCE process and chip design to one company, and are in talks with several others.

“I conceived the development of wide bandgap semiconductor (SiC) power devices in 1979 and have been promoting the technology for more than three decades,” Baliga says. “Now, I feel privileged to have created PRESiCE as the nation’s technology for manufacturing SiC power devices to generate high-paying jobs in the U.S. We’re optimistic that our technology can expedite the commercialization of SiC devices and contribute to a competitive manufacturing sector here in the U.S.,” Baliga says.

The paper, “PRESiCE: PRocess Engineered for manufacturing SiC Electronic-devices,” will be presented at the International Conference on Silicon Carbide and Related Materials, being held Sept. 17-22 in Washington, D.C. The paper is co-authored by W. Sung, now at State University of New York Polytechnic Institute; K. Han and J. Harmon, who are Ph.D. students at NC State; and A. Tucker and S. Syed, who are undergraduates at NC State.

The work was supported by PowerAmerica, the Department of Energy-funded manufacturing innovation institute that focuses on boosting manufacturing of wide bandgap semiconductor-based power electronics.

معرفی مختصری از زبان برنامه نویسی پایتون

پایتون (Python  ) یک زبان برنامه نویسی همه منظوره ،‌ سطح بالا ، شیء گرا و مفسر است که توسط خودو فا روسوم ( به هلندی :    Guido van Rossum ) در سال ۱۹۹۱ در کشور هلند طراحی شد .

پایتون مدل‌های مختلف برنامه‌نویسی (از جمله شیء گرا و برنامه‌نویسی دستوری و تابع محور) را پشتیبانی می‌کند و برای مشخص کردن نوع متغییرها از یک سامانه‏ی پویا استفاده می‌کند.

این زبان از زبان‌های برنامه‌نویسی مفسر بوده و به صورت کامل یک زبان شیءگرا است که در ویژگی‌ها با زبانهای تفسیری پرل، روبی، اسکیم، اسمال‌تاک و تی‌سی‌ال مشابهت دارد و از مدیریت خودکار حافظه استفاده می‌کند.

از زبان برنامه نویسی پایتون برای طراحی وب ، طراحی اپلیکیشن اندروید ،‌ طراحی بازی ، باز کردن فایل های کامپیوتر و خواندن و یا ویرایش محتویات آن ها ، ارسال ایمیل ، بارگذاری محتوی در وب سرور  ، امنیت اطلاعات و بسیاری کاربرد های دیگر استفاده می شود . سازمان های بزرگی چون گوگل ، ناسا ،‌ یاهو و سرن از زبان برنامه نویسی پایتون استفاده می کنند .

  • پایتون زبانی مناسب برای شروع برنامه نویسی

پایتون به دلیل داشتن syntax منظم و دقیق و خوانا و در عین حال ساده بودن کد نویسی با آن ، برای آموزش به افراد مبتدی و کسانی که با برنامه نویسی آشنایی ندارند توصیه می شود . دانشگاه های مطرحی مانندMIT  و UC Berkeley‌ ،‌ این زبان برنامه نویسی را به دانشجویان تازه وارد خود آموزش می دهند .

  • نگهداری از source code‌ های پایتون بسیار ساده می باشد
  • Library ‌های قابل حمل فراوانی دارد که با Windows‌ ، Linux و Macintosh‌ سازگاری دارند.
  • زبان برنامه نویسی پایتون روی همه پلتفرم ها با یک رابط کاربری واحد و مشخص قابل استفاده میباشد.
  • از همه Database‌ های تجاری پشتیبانی می کند .
  • برنامه نویسی گرافیکی (GUI )

با این زبان می توان برای تمامی سیستم عامل های موجود در بازار برنامه گرافیکی تولیک کرد.

  • نزدیکی دستورات استفاده شده در پایتون به کلمات مورد استفاده در زبان انگلیسی

یکی از ویژگی های جالب زبان برنامه نویسی python‌ این است که تقریبا برای هر کاربردی که به ذهن ما می رسد یک تابع برای آن تعریف کرده اند .

  • قابلیت پیاده سازی مباحث شیء گرایی و وراثت را دارد

اگر بخواهم با یک مثال شیء گرایی را توضیح دهم به این صورت است که فرض کنید ما می خواهیم ماشین های شرکتی که برای مثال ۱۰۰ نوع ماشین دارد را لیست کنیم ، اگر بخواهیم برای هر ماشین یک تابع تعریف کنیم کار بسیار سخت و عبثی خواهد بود و خطوط برنامه ما بسیار زیاد خواهند شد ؛‌ لذا راه حل این است که برای هر مدل ماشین یک کلاس تعریف کنیم و بعد مثلا از کلاس پراید ۱۰۰۰ عدد ماشین تعریف می کنیم و از بقیه کلاس ها به همین صورت فقط اشیائی از آن کلاس را تعریف می کنیم .

برای کوتاه تر کردن خطوط برنامه یک کلاس مادر به اسم Car‌ می سازیم که در و چرخ و فرمان و رنگ و ویژگی هایی که هر ماشینی می تواند داشته باشد را دارا است ، سپس کلاس های دیگر مانند پراید ، تیبا ، برلیانس ، سراتو و … از کلاس Car‌ ویژگی هایش را به ارث می برند و هر یک ویژگی های خود را به صورت مجزا نیز خواهند داشت .

  • برخی از برنامه هایی که با زبان Java‌ می نویسند می توان با python نوشت.
  • قدرت محاسباتی بالایی دارد.

زبان پایتون بر خلاف زبان های برنامه نویسی که نیاز به کامپایلر دارند ،‌ به کامپایلر نیاز ندارد و خط به خط که کد نوشته می شود ،‌ اجرا می شود ، همین موضوع باعث می شود سرعت عملکرد بالایی داشته باشد .

پایتون تابع های بسیار خوبی برای کار با رشته ها دارد که به سادگی بسیاری از کار ها را انجام می دهد .

  • کاربرد به عنوان زبان آغازگر در برخی بازی ها

پایتون معمولا در بسته های انیمیشن ۳D‌ استفاده می شود ، مانند Houdini, Maya, Softimage XSI, TrueSpace: Poser, Modo, Nuke, Blender , GIMP,  ,کریتا , Inkcape  , Scribus , Paint Shop Pro.

  • در مباحث شبکه بسیار کاربرد دارد.

کتابخانه های مفیدی در زمینه ارسال داده ها به Web server‌ و دریافت داده ها از Web server‌ و Socket programming‌ و کار با پروتکل های Http‌ و UDP و … دارد .

در زمینه Web programming‌سایت های زیر به همراه پایتون بسیار پر کاربرد می باشند :

Django, Pyramid, Bottle, Tornado, Flask, web2py

  • Data type‌ های بسیار متنوعی دارد

برخی از انواع داده های آن عبارتند از : Str , Int , Float , Double , Complex , List , Tuple . Set , Dictionary (dict) , Bool

  • قابلیت تعامل با زبان های برنامه نویسی دیگر را دارد

مثلا Cpython‌ که به زبان C‌ نوشته شده است قابلیت تعامل با کد های نوشته شده به زبان C ، یا تعامل به صورت  Wrapperبر روی کتابخانه های نوشته شده با C‌ را دارد . Jython‌ قابلیت تعامل با کد های جاوا را دارد . Iron Python‌ قابلیت کار کردن با C#‌ و  Net‌ را داراست . pyobjc امکان نوشتن کد پایتون و استفاده از ابزار های objective C‌ را فراهم می کند . pyjs‌ امکان کامپایل پایتون به Javascript را می دهد .