Jun 16, 2021The IIoT Power Challenge
Industrial Internet of Things (IIoT) devices present a range of challenges from a power-delivery perspective. Dedicated wired power isn't always cost-effective, due to the number of sensors that may be required on a network, and in many situations, it might not be possible at all. Such situations might include network edge applications, as well as environmentally extreme applications.
Battery power, meanwhile, might fit many use cases, but the constraints of long-term in-the-field battery deployment will be familiar territory for many. There are a vast range of solutions to this conundrum, including the search for lighter and better-performing batteries, design efficiencies to improve battery life, and entirely separate power sources.
IIoT Battery-Management Techniques
The obvious port of call in a constrained power situation is to ensure that power demand is minimized as much as possible. Common techniques include minimizing radio use, controlling in-device resource use (such as CPU overheads), optimizing sensor-sampling intervals and similar frugal strategies. However, once these strategies have been exhausted, there are ingenious additional tools and schemes on the horizon.
One such tool is Silicon Labs' Energy Friendly Power (EFPO1), an intermediary DC/DC power converter that sits between the battery and the power load. The clever bit is that the EFP can modulate the supply rails to reduce or cut power going to the load, allowing very granular power-management abilities even for components and circuits that lack inbuilt power management of their own. This, in turn, allows designers to add a simple capacitor-based "charge reservoir" that the EFP can charge in bursts, extending low-current device battery life considerably. Available in different formats for different battery voltages, the EFPO1 is software-configurable, enabling efficiencies to be made on the fly, as well as programmed as defaults.
Meanwhile, Rohm's Nano Energy technology targets reduced IC power consumption overall, decreasing current consumption during ultra-light loads while minimizing the ensuing trade-off, in order to approach a target of 10-year drive on a single coin battery. The technology aims to enable operations in extremely low-power environments, such as energy-harvesting systems.
Energy Harvesting Gathers Pace
Energy harvesting has been under discussion for many years in certain applications, but improvements across the board are gradually making harvesting increasingly practical for IIoT systems. One example is Maxim Integrated Products' new MAX20361 IC single- and multi-cell solar harvester—which, as the name implies, includes a solar cell that improves performance. Indeed, the company claims the technology is ideal for ultra-low-power applications such as wireless IoT sensor nodes and asset trackers, and that the adaptive Maximum Power Point Tracking (MPPT) approach boosts overall system-level efficiency by up to 5 percent alone.
Batteries Not Included
Of course, avoiding the use of a battery entirely does mitigate a lot of power-delivery issues. Improved Power over Ethernet (POE) is seeing burgeoning popularity; indeed, a recent analyst report put the global POE market at $97.7 million in 2020, but predicted an increase to $133.4 million by 2027. China is expected to reach a size of $23.6 million by 2027, trailing a CAGR of 4.3 percent, with Japan and Canada expected to grow at 4.4 percent and 3.6 percent, respectively.
Part of this growth is down to the emerging popularity of next-generation POE, or the IEEE 802.3bt standard, which enables substantially more power to be passed over the Ethernet link. However, while next-generation POE still requires hardwiring (albeit by potentially reusing pre-existing wiring), there are other strategies afoot to avoid adding cabling and batteries into the bargain.
Startup Everactive has developed IIoT sensors that can operate for more than 20 years, thanks to ultra-low-power integrated circuits designed to harvest energy from light sources and use vibrations to generate data, all battery-free. The flagship product is a battery-free steam trap monitoring sensor (see Everactive Intros IoT Steam-Trap Predictive-Maintenance Solution), requiring little maintenance and offering high sampling rates to combat the literal and monetary cost of stuck steam traps. The U.S. Department of Energy calculates that a single steam trap that is stuck open can cost a plant $6,640 per year by leaking 75.8 pounds of steam per hour.
Smarter Power—An Ongoing Battle
It's fair to say that as Industry 4.0 deployments gather volume, the hunt for smarter power will continue apace, as demonstrated by the sheer range and variety of application cases. As the IIoT matures, the need to iterate and optimize older hardware and power-delivery systems will gather momentum as well, creating new market opportunities for many such solutions. In short, while huge advances have been made, the battle is set to continue well into the foreseeable future—smarter than ever, but never quite smart enough.
Martin Keenan is the technical director at Avnet Abacus, which assists and informs design engineers in the latest technological challenges, including designing for Industry 4.0 and Industrial IoT manufacturing.
