Resonate Driver Circuit for Solid State Light Sources
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Solution Overview
Problem
Conventional switching regulator configurations for solid state light sources lack protective isolation, result in dangerous unregulated DC voltages and low power factor, and face a tradeoff between output ripple current and capacitance, leading to inefficiency and cost issues.
Innovation Solution
A resonate driver circuit with a rectifier, inverter, transformer, power factor correction, and frequency control, which provides constant current output with low ripple and high power factor, using zero voltage switching and feedback mechanisms to optimize switching frequency and reduce bulk capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switching regulator configurations are used, then the circuit can convert AC to DC voltage, but the unregulated DC voltage becomes dangerous and lacks protective isolation
Solution Approach 1:
The patent introduces a resonant transformer as an intermediary component between the rectifier and the load. The transformer provides galvanic isolation through its magnetic coupling mechanism, blocking the transmission of dangerous unregulated DC voltage while allowing controlled power transfer. The resonant circuitry further mediates the energy transfer, ensuring safe operation.
2Use of energy by moving object
If conventional switching regulator configurations are used, then the circuit can operate, but the power factor becomes low due to pulsed current draw
Solution Approach 1:
The patent employs resonant oscillation at a specific frequency to create periodic current draw from the AC source. By tuning the resonant frequency to match the line frequency or its harmonics, the circuit draws current in a sinusoidal pattern rather than pulsed patterns, thereby improving power factor. The periodic resonant action synchronizes with the AC cycle to achieve unity or near-unity power factor.
3Stability of the object's composition
If output bulk capacitance is increased to reduce ripple current, then current ripple decreases, but power efficiency decreases and cost increases
Solution Approach 1:
The patent utilizes resonant oscillation (analogous to mechanical vibration principles) to naturally smooth current fluctuations. The resonant circuit stores and releases energy in a rhythmic fashion, providing inherent ripple reduction without requiring large bulk capacitance. This vibrational energy storage mechanism achieves ripple suppression while maintaining high efficiency and low cost.
Solution Approach 2:
The patent implements feedback control where the resonant circuit responds to load conditions and automatically adjusts energy transfer to maintain stable output. This feedback mechanism allows the system to compensate for ripple without additional capacitance, as the resonant frequency and impedance characteristics provide natural stabilization that reduces the need for large output capacitors.
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 achieves increased power efficiency, reduced current ripple, and improved power factor, ensuring safe and efficient operation of solid state light sources while minimizing costs and flicker.
Implementation Method 1
a transformer comprising: a primary winding coupled to the inverter circuit; a secondary winding configured to be coupled, through an output stage circuit, to a solid state light source
Implementation Method 2
generate a resonant AC signal from the unregulated DC voltage
Data Source
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AI summary
A driver circuit, solid state light (SSL) source assembly including same, and method of driving same are provided. The driver circuit includes a rectifier (202), an inverter (206), a transformer (208), a PFC circuit (204), and a frequency control (218). The rectifier receives an AC voltage and provides an unregulated DC voltage. The inverter includes two switches, and receives respective control signals to operate these, to generate a resonate AC signal from the unregulated DC voltage. The transformer includes a primary winding (210) coupled to the inverter, a secondary winding (214) to be coupled to an SSL source through an output stage, and a feedback winding (212). The PFC circuit controls the inverter in response to signals representative of the unregulated DC voltage and the inverter's current. The frequency control generates control signals to control the inverter's switching frequency in response to signals representative of the output stage's current and the feedback winding's current.