At the recent IDTechEx Energy Harvesting and Storage conference Europe in Munich, an excellent presentation was given by the $20 billion Schneider Electric on a ZigBee Wireless Temperature Sensor Energized by a Thermo Generator. There is an increasing need for monitoring From Plant to Plug ™. Energy management requires monitoring of electrical parameters such as current and voltage and non-electrical parameters such as temperature and position. In the specific case considered, Schneider Electric needs to offer its large site customers a thermal monitoring solution to master their electrical installation and decrease maintenance cost, in order to maximize the capability of the installation.
Constraints are:
- Products targeted are working under hard environment constraints
- Dielectric and galvanic insulation
- Accessibility
Customer requirements include:
- Battery-less
- Wireless
- Ease of installation
- Maintenance free
Hundreds of ISO 18000D UHF passive RFID sensors have been deployed as illustrated. They works at one meter (500mW at 868 MHz) with one measurement every 350 microseconds but only in a star architecture.
Energy harvesting and voltage conversion involved a thin film thermo generator where 3°C temperature difference generated 126µW (@ 210mV) and a standard DC-DC converter had efficiency ~70%: 100µW (@2,4V). In a star architecture, measurement and data transmission could be achieved every 5 seconds using ZigBee but (some applications require 1/10 minutes. Extra energy will permit storage capacity to be increased and there will be work on a wireless communication protocol for the sensor to act as a "router" in a mesh or linear architecture. Combined sensors will become feasible.
Top image: Dr Gilles Thonet, Manager of Zigbee Excellence Center, Schneider Electric, France
For more read : Energy Harvesting and Storage for Electronic Devices 2009-2019
