LED Emergency Backup Flyback Circuit for No-Load Output Reset
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Solution Overview
Problem
Conventional battery backup systems for fluorescent illumination are unsuitable for LED fixtures due to their different current, voltage, and drive characteristics, necessitating multiple emergency backup drivers for various voltage requirements.
Innovation Solution
A constant power battery backup system using a discontinuous conducting mode (DCM) flyback converter that supplies backup power to LED lighting fixtures with arbitrary voltage requirements, incorporating a low battery sense circuit, no load resetting circuit, and smart output/no load resetting circuit to ensure efficient and safe power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional battery backup systems are used for fluorescent illumination, then they can provide backup power for fluorescent fixtures, but they are unsuitable for LED fixtures due to different current, voltage and drive characteristics
Solution Approach 1:
The patent implements a universal constant power backup driver that can drive LED fixtures with different forward voltages (e.g., 12V, 20V, 30V, 48V) using a single device. The system uses a flyback converter with adjustable switching frequency and duty cycle to adapt to various LED string configurations, eliminating the need for multiple voltage-specific backup drivers.
Solution Approach 2:
The system dynamically adjusts operating parameters including switching frequency, duty cycle, and PWM pulse width to match the specific forward voltage and current requirements of different LED fixtures. This allows the same hardware platform to provide constant power across multiple voltage ranges by changing control parameters rather than hardware configuration.
2Adaptability or versatility
If constant current drivers are used for LED fixtures with different forward voltages, then each specific voltage requires a different driver, but this increases device complexity and reduces versatility
Solution Approach 1:
The backup driver is designed as a universal constant power device that can accommodate LED fixtures with different forward voltages through a single unified circuit architecture. The flyback converter topology with adjustable parameters enables one driver to replace multiple voltage-specific drivers, achieving multi-functionality.
Solution Approach 2:
The system employs dynamic control mechanisms where the switching frequency, duty cycle, and PWM parameters are continuously adjusted based on the detected LED fixture characteristics. This dynamic adaptation allows the driver to optimize performance for each specific voltage requirement without requiring separate static driver designs.
3Reliability
If the flyback converter operates without a load during power transition, then voltage can build up to dangerous levels, but connecting the load immediately may cause inrush current
Solution Approach 1:
The system performs preliminary load detection before initiating full power delivery. The control circuit checks whether the LED fixture is properly connected and determines the appropriate operating parameters in advance, preventing both overvoltage conditions and inrush current by preparing the system gradually before full engagement.
Solution Approach 2:
The system implements feedback control to monitor output voltage, current, and load presence continuously. Based on this feedback, the controller adjusts the PWM duty cycle and switching parameters in real-time to maintain safe operating conditions during power transitions, preventing both voltage buildup and inrush current by responding to actual system state.
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 system provides constant power to LED fixtures across a broad range of voltages, efficiently using battery capacity, preventing over-depletion, and safeguarding against dangerous voltage conditions, allowing the same system to be used with different types of LED lighting fixtures.
Implementation Method 1
a constant power LED driver circuit having a flyback converter with a transformer operating in discontinuous conduction mode. The flyback converter has a primary inductor winding that is electrically coupled to the storage battery, and a secondary inductor winding that is selectably electrically coupled to the LED light source.
Data Source
AI summary
A constant power backup power supply for LED lighting fixtures is disclosed. The power supply includes a storage battery that is charged while an AC power source is in an ON condition. When AC power transitions to an OFF condition, a capacitor bank charged by the battery supplies current to the primary side of a flyback converter operating in discontinuous conduction mode. The secondary side of the flyback converter supplies constant output power to the LED lighting fixture for an arbitrary output voltage within a predetermined range.