LED Lighting Device Overvoltage Protection Circuit
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Solution Overview
Problem
LED lighting devices connected to fluorescent lamp sockets lack effective protection against overvoltage generated by stabilizers, leading to potential circuit damage and inoperability.
Innovation Solution
The LED lighting device incorporates first and second power input units, rectification units, a smoothing unit, and an overvoltage protection unit with Zener diodes and a silicon rectification controller to block overvoltage currents before they damage the circuit, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the LED lighting device is connected to the fluorescent lamp socket without removing the stabilizer, then the device can be directly installed and used, but the circuit is vulnerable to overvoltage damage from stabilizer discharge
Solution Approach 1:
The patent introduces an intermediary overvoltage protection circuit between the power input and the LED driving circuit. This circuit includes a varistor (MOV) connected in parallel with the power input terminals and a fuse connected in series. The varistor acts as a mediator that absorbs or diverts the harmful overvoltage energy from the stabilizer discharge, preventing it from reaching and damaging the sensitive LED driving circuit components.
Solution Approach 2:
The patent applies beforehand cushioning by pre-installing protective components (varistor and fuse) in the circuit path before the overvoltage can reach the vulnerable components. The varistor is positioned to intercept overvoltage spikes immediately upon entry, and the fuse is placed to break the circuit before damage occurs. This proactive protection allows the device to withstand stabilizer discharge events without requiring removal of the stabilizer.
2Reliability
If a fuse and varistor are used to block overvoltage current, then the circuit is protected from damage, but the circuit becomes inoperable even when normal voltage is applied later
Solution Approach 1:
The patent employs dynamic protection by using a thermal resettable fuse (PTC fuse) instead of a traditional one-time fuse. The PTC fuse changes its electrical resistance dynamically based on temperature: under normal conditions it has low resistance allowing current flow, but when exposed to overvoltage it heats up and transitions to high resistance state, blocking current. Crucially, after the overvoltage event subsides and the fuse cools down, it automatically returns to its low resistance state, restoring circuit operation without manual intervention.
Solution Approach 2:
The patent implements a recoverable protection mechanism where the protective components (especially the PTC fuse and varistor) can recover their functional state after absorbing the overvoltage energy. The varistor recovers its high-impedance state after the voltage spike passes, and the PTC fuse cools down and resets its low-resistance state, allowing the circuit to be automatically recovered and resume normal operation without replacing components or manual resetting.
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
Prevents circuit damage from overvoltage, maintains stable operation by blocking overvoltage flows and discharging them to ground, allowing the circuit to reactivate when normal voltage is applied.
Implementation Method 1
an overvoltage protection unit blocking a flow of current when a voltage outputted from the smoothing unit is an overvoltage that is equal to or greater than a critical value, the overvoltage protection unit including first and second Zener diodes reversely connected to an output terminal of the smoothing unit
Implementation Method 2
the silicon rectification controller serves as a switch device which guides a flow of current to a cathode connected to a ground point from an anode connected to an output terminal of the smoothing unit
Data Source
AI summary
The present invention provides an LED lighting device, which can be directly connected to a socket for a fluorescent lamp without revising the socket to a dedicated LED Light circuit. The LED lighting device may be prevented from being damaged by the overvoltage generated in the stabilizer and introduced into the driving circuit, and this device is reactivated when a normal voltage is introduced. For this purpose, the LED lighting device includes first and second power input units, first and second rectification units, a smoothing unit, an overvoltage protection unit, and a driving voltage generation unit.