Powercast recently presented (09/21/2011) at the Remote Monitoring & Control Conference in Nashville, TN. The cost of installing wiring can range from $200 per device to >$1000 per foot in some industrial environments. In either case, wireless power transmission over distance using RF energy can potentially be a suitable alternative to running wires or replacing batteries.
An article by Powercast titled “RF Energy Harvesting and Wireless Power” was published by Electronic Products.
“The market growth of low-power wireless devices particularly sensors is driving tremendous interest in using energy sources that can power the devices autonomously. The cost of running wires and the future cost of replacing batteries have discouraged users from widely deploying a verity sensor-based devices.
While solar has been widely used for years to power remote devices, several other types of energy-harvesting approaches have emerged for micro-power applications including vibration, thermal, mechanical, and RF. Of these technologies, RF energy is the only one that can provide either an intentional or ambient power source for wire-free or battery-free applications.”
Both ECN and Wireless Design & Development (WD&D) have published a recent article by Powercast titled “RF energy Harvesting Perpetually Powers Wireless Sensors”, which looks at using broadcasted RF energy as a reliable long-term power source for battery-less wireless sensors.
Powercast exhibited at the Sensors Expo 2011 and demonstrated using RF energy harvesting to wirelessly charge credit card size devices. The devices are representative of high function, rechargeable smart cards and contained rechargeable thin-film batteries - CYMBET EnerChip, Infinite Power Solutions THINERGY, and STMicroelectronics EnerFilm.
The video below shows the rechargeable smart card devices receiving charge from an RF transmitter. The transmitter was on the floor under the table.
Powercast has released a battery-less, wirelessly-powered sensor system for building and industrial automation - the Lifetime Power® Wireless Sensor System. The sensor units can be powered at a range of 60-80 feet (18-24 m) from Powercast’s 3W, 915MHz transmitter (TX91501). The initial sensor unit is for temperature and humidity and is to be followed by other types such as CO2, light, and motion.
Powercast Lifetime Power® Wireless Sensor System
The access point (WSG-101 BAS gateway) supports up to 100 sensors and 800 sensor points for large-scale and high-density deployment of sensors. The sensors are battery-free and operate when sufficient charge is stored to take sensor readings and send a data packet. Wireless communication from the sensor nodes to the access point is 2.4GHz using industry-standard 802.15.4 radios. The BAS gateway supports several physical interfaces and a range of BAS protocols to interface with nearly every major type of wired BAS network, including BACnet, Modbus, Metasys N2, and LonWorks.
The video below demonstrates how Powercast’s wireless power technology charges multiple devices simultaneously, and in this case a wireless keyboard, a wireless mouse, and a wireless game controller. The amount of power being delivered to these devices is in the low mW range.
Some applications can be powered directly from the transmitter, but for most consumer electronic devices trickle-charging a battery will be more appropriate.
In an earlier post we demonstrated an iPhone powering LEDs in close proximity using Powercast’s RF energy harvesting technology.
The video below demonstrates the use of a standard iPhone in 2G mode to generate RF energy that is used to power a battery-free wireless sensor node. The sensor node is part of Powercast’s Lifetime Power (TM) Energy Harvesting Development Kit for Wireless Senors (P2110-EVAL-01), the receiving board is based on the P2110 Powerharvester Receiver, and the antenna was slightly modified from it’s original tuning for 915MHz.
The wireless sensor node was designed by Powercast and Microchip for ultra-low power operation. At a distance of 2 feet from the iPhone packets are transmitted from node every every 1-2 seconds. As this video shows, mobile phones can be a practical, portable source of wireless power for a wide range of applications.
Broadcasted RF energy creates a predictable, controllable power source to provide power-over-distance and one-to-many charging. Unlike potentially unreliable or intermittent solar, heat or vibration micro-power energy sources, the TX91501 transmitter sends power to enable wireless devices to charge and operate completely untethered from the power source, and power can be sent on-demand, scheduled, or continuously. End-devices can be inherently dormant, with zero-standby power, until power is sent to operate the device, or batteries can be trickle-charged remotely. The operating distance for wireless power transfer (wireless charging) from the TX91501 transmitter to a device with the P2110 Powerharvester Receiver is about 40 feet with a reasonable size receiving antenna.
The kit (part number P2110-EVAL-01) includes the following items:
1 - 3W Powercaster Transmitter - 915MHz (TX91501-3W-ID)
2 - P2110 Evaluation Board (P2110-EVB)
2 - Directional, patch antennas - 915MHz
2 - Omni-directional dipole antennas - 915MHz
2 - Wireless Sensor Boards (WSN-EVAL-01)
1 - Microchip XLP 16-bit Development Board
1 - Microchip 802.15.4, 2.4GHz radio
1 - PICkit programmer/debugger
The components in the kit enable wireless and battery-free operation of the sensor nodes at a distance of 40-45 feet (13-15 meters). Each sensor board can measure temperature, humidity, light, and an external sensor. This can be used for a number of applications including building automation, energy management and industrial monitoring. Power is provided by Powercast’s new 3W transmitter (TX91501-3W-ID), which also sends factory-set data. The P2110 Powerharvester receiver converts the RF energy from the receiving antenna and stores it into a capacitor, which is then boosted to operate the wireless sensor board. The Microchip XLP 16-bit Development Board with the 802.15.4 radio is the access point.
Powercast released the the TX91501 Powercaster(TM) Transmitter to send power and data to remote devices for battery-charging or battery-free operation. The TX91501 uses DSSS modulator for power and ASK modulation for data, and is intended to be used in conjunction with Powerharvester Receivers. The power output is either 1W or 3W based on the product version, and the data is a transmitter ID code that can be used for activating specific end devices, location tracking, or other applications.
The TX91501 transmitter is approved by the FCC (Part 15) and Industry Canada. It can be used to broadcast RF energy for both power and data in numerous energy-harvesting applications such as environmental monitoring, building automation, energy management and industrial monitoring.
Broadcasted RF energy creates a perpetual power source, unlike potentially unreliable solar, heat or vibration energy sources, to provide power-over-distance, one-to-many charging, and controllable wireless power (continuous, scheduled or on-demand). A wire- and battery-free power source enables zero-maintenance devices which deploy to inaccessible locations, and embeds within sealed devices for use in wet or harsh environments.