Capacitive Energy Harvester Eliminates Earth Ground
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Solution Overview
Problem
Existing energy harvesting systems from AC power lines require a direct ohmic connection to earth ground, making them time-consuming and costly for large-scale infrastructure deployment, as they necessitate physical modifications like chipping wall panels for ground contact.
Innovation Solution
A capacitive energy harvester with non-ohmic contact that uses an inner and outer electrode configuration without a physical grounding connection, employing a diode rectifier bridge, storage capacitor, high-side switch, wireless MCU, and antenna to harvest energy from AC power lines, allowing for plug-and-play assembly and operation without an earth ground reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a direct ohmic connection to earth ground is used for energy harvesting from AC power lines, then reliable energy harvesting is achieved, but deployment becomes time-consuming and costly due to physical modifications like chipping wall panels
Solution Approach 1:
The patent introduces an intermediary capacitive coupling mechanism between the AC power line and the energy harvesting circuit. Instead of direct ohmic grounding, the system uses capacitive electrodes that couple to the power line through the wall material (concrete, plaster, etc.) without requiring physical penetration or direct contact with earth ground. This intermediary coupling method enables reliable energy transfer while eliminating the need for cumbersome physical modifications to the infrastructure.
2Stability of the object's composition
If physical grounding connections are required for energy harvesters, then stable reference potential is obtained, but infrastructure establishment becomes complex and expensive
Solution Approach 1:
The patent replaces the mechanical/physical grounding system with an electrical field-based capacitive coupling system. Instead of mechanically connecting to earth ground through copper plates and wire installations, the system uses electric field coupling through capacitive electrodes. The outer electrode serves as a reference potential that is capacitively coupled to the power line, eliminating the need for complex mechanical grounding infrastructure while maintaining stable reference potential for the energy harvesting circuit.
3Productivity
If ohmic contact is used for power line connection, then efficient energy transfer is achieved, but installation requires wall panel chipping and earth ground plate digging
Solution Approach 1:
The patent changes the fundamental parameter of electrical contact from ohmic (direct conductive) to capacitive (electric field-based). This parameter change allows the system to achieve sufficient energy transfer efficiency without requiring direct physical contact between the harvesting device and the power line or ground. The capacitive coupling maintains adequate electrical connection through the wall material, dramatically reducing installation time and complexity while preserving functional performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient energy harvesting up to 270 μJ in 12 minutes from a 14 cm interface, scalable by dimension and placement, and supports various sensing applications like temperature monitoring and appliance state logging without the need for battery replacement, reducing maintenance costs and deployment complexity.
Implementation Method 1
a battery-free, stick-on capacitive energy harvester that harvests the stray electric field generated around AC power lines (110 V/230 V) without an ohmic connection to earth ground reference
Implementation Method 2
harvests the stray electric field generated around AC power lines (110 V/230 V)
Implementation Method 3
The energy harvester comprises an inner electrode, an outer electrode and a circuit... The diode rectifier bridge is connected to the inner and outer electrodes
Data Source
AI summary
The various embodiments herein provide an energy harvester which can capacitively harvest stray electric field from low-voltage AC power lines without a physical grounding connection. The energy harvester comprises an inner electrode, an outer electrode and a circuit. The inner electrode forms an inner periphery of an upper portion of a harvester housing. The outer electrode forms an inner base of a lower portion of the harvester housing to provide a local ground reference. The circuit is housed within the lower portion of the harvester housing to direct stored energy and control an energy discharge.