LED Lamp Load Driving Apparatus with Determination Circuit
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Solution Overview
Problem
Conventional LED lamp driving devices malfunction when the LED is turned off, requiring a restart to turn it back on, and lack overcurrent protection, leading to unnecessary power loss when the LED is shorted.
Innovation Solution
A load driving apparatus with a PWM-based power converter and a determination circuit that controls the DC operation voltage based on lamp-on or lamp-off conditions, including a short protection circuit to prevent power loss when the LED is shorted, ensuring the PWM controller operates within a safe voltage range and avoiding additional power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the LED lamp is turned off by directly pulling down the operation voltage, then the lamp-off function is achieved, but the PWM controller malfunctions due to under voltage lockout
Solution Approach 1:
The patent divides the voltage control into two separate circuits: a determination circuit that controls the LED lamp switching and a voltage regulator circuit that maintains stable voltage for the PWM controller. This segmentation allows the LED to be turned off without affecting the PWM controller's power supply, preventing under voltage lockout while maintaining lamp-off functionality.
2Reliability
If winding turns of the transformer are increased to provide sufficient working voltage for the PWM controller, then the controller can operate reliably, but additional power loss is produced and conversion efficiency is reduced
Solution Approach 1:
The patent separates the voltage regulation function into a dedicated voltage regulator circuit that operates independently from the LED driving circuit. This allows the transformer to be optimized for LED driving with lower winding turns, reducing power loss while the voltage regulator ensures sufficient voltage for the PWM controller without requiring additional transformer winding increases.
3Reliability
If a voltage regulator circuit is additionally configured to provide working voltage for the PWM controller, then the controller can operate reliably, but additional cost is incurred
Solution Approach 1:
The patent designs the voltage regulator circuit to serve multiple functions: it regulates voltage for the PWM controller, provides over voltage protection, and maintains stable operation during LED switching. This multi-functionality justifies the additional circuit configuration by eliminating the need for separate protection circuits and reducing overall system complexity despite the added component.
4Reliability
If the PWM controller periodically outputs PWM signals with very short duty cycle when the LED is shorted, then over current protection is triggered, but unnecessary and repetitive high power loss occurs
Solution Approach 1:
The patent implements a determination circuit that detects LED lamp conditions (including short circuits) before the PWM controller can generate excessive PWM signals. When a short circuit is detected, the determination circuit immediately stops conducting operation voltage to the LED, preventing the PWM controller from entering repetitive short-cycle operation and the associated power loss.
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
The solution allows the LED lamp to be turned on without restarting the PWM controller and prevents unnecessary power loss by maintaining the PWM controller in a low-power state when the LED is shorted, thus maintaining conversion efficiency and reducing costs.
Implementation Method 1
a pulse width modulation (PWM)-based power converter... generates a direct current (DC) operation voltage of the LED lamp, and controls a current flowing through the LED lamp
Implementation Method 2
a transformer, an N-type power switch transistor... The transformer has a primary side and a first secondary side... rectifies and filters an AC induction voltage on the first secondary side
Implementation Method 3
The first rectification-filtering circuit receives an alternating current (AC) input voltage, and rectifies and filters the AC input voltage to generate and output a DC output voltage
Data Source
AI summary
A load driving apparatus related to an LED lamp and a method thereof are provided. The load driving apparatus includes a PWM-based power converter and a determination circuit. The PWM-based power converter is coupled to the LED lamp, and is configured to: generate a DC operation voltage of the LED lamp; and control a current flowing through the LED lamp in response to a dimming signal, so as to adjust a brightness of the LED lamp. The determination circuit is coupled to the PWM-based power converter and the LED lamp, and is configured to: receive the DC operation voltage; and stop conducting the DC operation voltage to the LED lamp in case that a lamp-off condition of the LED lamp is satisfied.