“With the promotion of 5G technology, the explosive growth of Industry 4.0 wireless sensor networks, smart logistics, smart cities, smart agriculture and other large-scale IoT applications has been achieved. In the process, designers have a unique opportunity to rethink every aspect of their network architecture, including new paradigm power supplies.
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Author: Jeff Shepard
With the promotion of 5G technology, the explosive growth of Industry 4.0 wireless sensor networks, smart logistics, smart cities, smart agriculture and other large-scale IoT applications has been achieved. In the process, designers have a unique opportunity to rethink every aspect of their network architecture, including new paradigm power supplies.
Providing scalable, reliable power for billions of wireless nodes is extremely challenging. If this problem is not solved, it will hinder the popularization of large-scale Internet of Things. Just using more batteries is not enough. In more and more cases, batteries will not be replenished or eliminated. Instead, various forms of energy harvesting (EH) technologies are needed to power the massive IoT. EH technology continues to advance, making it an increasingly attractive option for powering large-scale IoT devices. This is undoubtedly lucky for the designer.
This blog outlines the challenges of powering billions of large-scale IoT wireless nodes, and some factors to consider when determining whether EH technology offers a viable solution. Then, introduce EM Microelectronic and Nowi’s energy-harvesting power management ICs and the development environment needed to accelerate the evaluation of EH technologies in large-scale IoT.
Here are five factors to consider when determining how to power large-scale IoT nodes:
・ Data rate
・ Transmission range
· Delay
· working environment
・ Environmental impact and management/logistics
Data rate, transmission range, and latency affect a node’s peak and average power requirements and depend on the wireless communication protocol used. For example, when using Bluetooth low energy technology, a 10 cm square photovoltaic panel can support the regular transmission of data packets, and the approximate data is as follows:
・ Under the indoor lighting level of the retail store: 1 time / 100 ms
・ At the lighting level of a typical office environment: 1 time / 200 ms
・ Under the lighting level of warehouses and factories: 1 time / 2 s
The operating environment also affects battery suitability and cost. In relatively benign environments such as retail stores or offices, lower priced batteries can achieve a reasonable operating life, making the cost of EH technology relatively high. If wireless nodes are deployed in harsh industrial or outdoor environments, more expensive battery chemistries are required, making EH technology relatively attractive.
Environmental impact and management issues are also considerations. Primary batteries have a limited lifespan, which increases the number of battery replacements, increases maintenance and management/logistics costs, and ultimately impacts the environment by disposing of used batteries. To address so many problems, designers can choose from the following power architectures that support EH technology:
・ Powered by main battery, supplemented by EH technology to extend battery life.Maintain battery-powered advantages while reducing adverse effects
・Rechargeable battery combined with EH technology for longer life, no need to replace the battery
・ Capacitors or supercapacitors combined with EH technology for battery-free systems and longest life
EH Technology Controller and Power Management ICs
For applications that can benefit from a combined power management IC (PMIC) and EH controller, designers can turn to EM Microelectronic’s EM8500. The PMIC provides maximum power point tracking (MPPT) for the EH source and four independent output voltages for different system functions (Figure 1). The product can interface with a variety of EH technologies, including thermoelectric generators (TEGs), and photovoltaic cells in the microwatt (μW) to milliwatt (mW) range. The EM8500 can be used in combination with primary or secondary batteries, conventional capacitors or supercapacitors. The EM8500-A001-LF24B+ type device is available in a 4 x 4 mm 24-pin QFN package.
Figure 1: The EM8500 PMIC includes an MPPT for the EH source and provides four output voltages to the system. (Image source: EM Microelectronic)
EM8500 Development Kit
Designers can use the EMDVK8500 development kit to configure and evaluate the EM8500 (Figure 2). The development kit includes the software required to configure the EM8500, and tools to measure the performance of the resulting solution.
Figure 2: The EMDVK8500 can configure the EM8500 PMIC and measure the performance of the resulting solution. (Image source: EM Microelectronic)
EH Controller IC and Evaluation Board
For designs that do not require a complete power management solution, Nowi’s NH2D0245 is a compact, high-performance EH controller with MPPT algorithm for low-power applications in a 16-lead, 3 x 3 mm QFN package (Figure 3 ). NH2D0245 can be used in a variety of EH sources, including photovoltaic, inductive, and piezoelectric, as well as energy storage devices such as rechargeable batteries or supercapacitors. The MPPT algorithm operates independently of the specific energy harvester and can detect the maximum power point at 1-second intervals, maximizing efficiency in dynamic environments.
Figure 3: The NH2D0245 EH controller features the MPPT algorithm in a 3 mm square QFN package. (Image credit: Nowi)
The NH2D0245 evaluation board is designed to speed up testing the performance and functionality of the NH2D0245 (Figure 4). To use this evaluation board, an energy harvester, a battery or supercapacitor, and a multimeter are required. If using an energy harvester with an alternating current (AC) output, such as a piezoelectric harvester, a rectifier must be added between the energy harvester and the evaluation board’s direct current (DC) input.
Figure 4: The NH2D0245 evaluation board can speed up testing of the functionality and performance of the EH controller. (Image credit: Nowi)
in conclusion
With the introduction of 5G technologies enabling massive IoT, there are exciting challenges and opportunities for designers to rethink how wireless nodes are powered. We must consider a variety of technical, environmental, and economic factors to determine the best power architecture for each application. We have to use various EH-based methods to improve the capacity of the battery. In many cases, EH will be used in combination with primary or secondary batteries, conventional capacitors or supercapacitors.
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