Ground Leakage Current Power Supply for Wireless Transceivers
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Solution Overview
Problem
Existing building automation systems face challenges in powering smart controllers and wireless transceivers within wall- or surface-mounted switches without a neutral wire, as conventional ground leakage current limits are insufficient for practical operation, leading to issues with energy storage and power supply.
Innovation Solution
A ground leakage current power supply circuit that utilizes an AC hot wire and earth ground, incorporating a rectifier, energy storage component, current limiter, and buck-boost regulator to generate a regulated output voltage, allowing for sufficient power supply while limiting ground leakage current within prescribed limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground leakage current is limited to less than 5 milliamperes to meet regulatory constraints, then ground fault interrupt compliance is achieved, but sufficient power for smart controllers and wireless transceivers cannot be supplied
Solution Approach 1:
The patent divides the power supply function into two independent parts: a current limiter that restricts ground leakage current to comply with regulations, and an energy storage component that accumulates sufficient power for the smart controller and wireless transceiver. This segmentation allows each component to optimize its function without compromising the other.
Solution Approach 2:
The patent introduces an energy storage component as an intermediary between the limited ground leakage current and the power-hungry smart controller. This intermediary accumulates energy over time and releases it when needed, decoupling the instantaneous power demand from the constrained ground leakage current.
2Ease of manufacture
If conventional power supply methods are used without an AC neutral line, then installation simplicity is maintained, but sufficient power for wireless transceivers cannot be achieved
Solution Approach 1:
The patent enables the power supply system to serve itself by using the existing AC hot wire and ground connection to charge the energy storage component, which then independently provides the necessary power to the wireless transceiver and smart controller without requiring additional neutral wiring or external power sources.
3Power
If energy storage component size is increased to provide sufficient power, then power availability for wireless transceivers improves, but ground leakage current constraints are violated
Solution Approach 1:
The patent separates the power accumulation function (energy storage component) from the ground leakage current limitation function (current limiter), allowing the energy storage component to be sized appropriately for power requirements while the current limiter independently ensures compliance with ground leakage current constraints.
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 reliable powering of remote or local loads and wireless transceivers within switches without an AC neutral line, ensuring sufficient power for a prescribed period while adhering to ground leakage current constraints.
Implementation Method 1
a rectifier, coupled to the hot node and to the earth ground node
Implementation Method 2
an energy storage component, coupled to a return node and coupled in series to a current limiter that receives rectified power from the rectifier
Implementation Method 3
a low voltage power supply including a buck-boost regulator, coupled to the energy storage component and to a return node, the return node providing a return reference voltage
Data Source
AI summary
A power supply, includes: a hot node coupled to a hot wire of an AC source, and a ground node coupled to an earth ground, where a neutral wire of the source is not present; a storage component, coupled to a return node and in series with a current limiter, where the current limiter enables the storage component to charge to a voltage while limiting leakage current to a prescribed value; a low voltage power supply including a buck-boost regulator, coupled to the storage component and to a return node that provides a reference voltage, where the low voltage power supply receives the voltage and generates an output voltage on an output node that is referenced to the reference voltage; and a wireless transceiver that employs the output voltage to transmit and receive messages from one or more corresponding wireless devices.