TECHNOLOGY
A step change in energy harvesting system performance
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Near “Zero” operating voltages enables harnessing of trace energy sources
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“Real-world” applications at operating voltages of 10 to 100 times less than conventional systems
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Several times the output power for a given energy harvesting source and device feature size
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Powers hand-held and wearable electronics from users body heat instantaneously and continuously (real-time)
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No batteries to charge up
What is an Energy Harvesting System?
An energy harvesting system consists of a generator, a power processing system an output storage element and the output load. The energy source could be heat, light or movement which the generator converts to electricity in AC or DC form.
The power processing system may then convert this to DC by a rectifier and then boost the voltage using a DC to DC converter to charge the storage device which may be a battery or capacitor. It may also have a voltage regulator to provide stabilised continuous DC power to the load.
For momentary or pulsed wireless data capture applications, a switch may be incorporated after the storage device of a chosen capacity to release its contents to the transmitter once it is charged to the required voltage.
The Invention
Power Processing System
Presently, low voltage portable electronic systems operate with batteries having a voltage of 1.5 Volts or more. The internal circuits of these systems typically shut off when the voltage drops to 1 Volt due to the threshold voltage of transistors (typically 0.7 Volts for Silicon and 0.3 Volts for Germanium) .
With the present invention, it is possible to power devices by energy harvesting means without the limitations of transistor threshold voltage where otherwise a minimum output voltage would need to be available from the micro-generator and hence a minimum amount of heat from a thermoelectric generator for example, to turn the system on.
To this end, the invention demonstrates technology to power hand-held and wearable electronics from the users body heat.
This low voltage is then boosted to a few volts by a high current charge pump DC to DC converter using a switching element of resistance 10 to 100 less than best portable energy harvesting systems (for example 0.05 Ohms to 0.005 Ohms) depending on application.
This combined with this, low resistance windings in inductors and transformers while maintaining the same inductance, provide the step change in energy harvesting system performance and enables several times the output power than existing systems for a given energy source and device feature size.
This is then stored in the output storage device which supplies power to the load or provide a stabilised DC voltage for instantaneous continuous operation (real-time).
The system can be configured to meet the voltage and current requirements of the device it is powering.
The key enabling technology is the invention of a power processing system coupled with a non-battery zero carbon fast charge energy storage device
Batteryless Storage Device
No need for a battery or replacement of serviceable parts in future. Instead, capacitors are used for the output storage device to deliver power to the load or provide a stabilised DC voltage for instantaneous continuous operation (real-time).
Super-capacitors may be used as long term storage.
Super-capacitors are also used to provide a current boost at the input of the power processing system. Here they may be charged at 10 to 100 times less voltage (millivolts) than conventional electronics operate at. However, their very low ESR (effective series resistance) in the order of milliohms and high capacitance (in the order of several Farads) are taken advantage to provide a high current input to the energy harvesting system.
Due to the much lower operating voltage of the power processing system (millivolts), the super-capacitors are charged quickly providing a high power density source to the system.
Low ESR capacitors are used as the high power density output storage element and continuously charged and quickly due the high current charge pump DC to DC converter of very low switching resistance.
In turn, capacitors have a very fast charge rate compared to batteries hence, power is available in seconds rather than minutes or hours providing a fast charge-discharge cycle to the load.
