LED Driver Circuit Power Factor Correction Voltage Drop
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Solution Overview
Problem
Existing LED driver circuits face inefficiencies leading to high power losses due to poor voltage regulator performance and reactive power compensation issues, which burden the power grid.
Innovation Solution
A driver circuit with a power factor correction circuit, a controllable charging mechanism, and a current controller that minimizes voltage drop across the current regulator by regulating the capacitor voltage and using a measuring branch to adjust the influencing circuit, allowing for efficient reactive power compensation and reduced power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If power factor correction circuit charges capacitor with rectified sinusoidal AC line voltage, then reactive power compensation is achieved, but voltage drop across current regulator increases leading to power loss
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor to optimal voltage levels before the main operation. The control circuit determines appropriate charging points and limits based on the rectified sinusoidal voltage waveform, preparing the capacitor in advance to minimize voltage drop during the actual LED driving phase, thus reducing power loss while maintaining reactive power compensation.
2Loss of energy
If voltage is reduced to minimize drop across current regulator, then power loss is reduced, but LED operating point precision may be compromised
Solution Approach 1:
The patent employs dynamic control by continuously adjusting the capacitor charging process based on real-time voltage conditions. The control circuit dynamically determines when to start and stop charging, and at what voltage levels, adapting to changing operating conditions. This dynamic approach ensures optimal voltage drop minimization while maintaining precise LED operating point through continuous regulation.
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 minimizes voltage drop across the current regulator, reducing energy conversion to heat and power loss, while ensuring the driver circuit does not burden the power grid with reactive power, maintaining a constant operating point for LEDs.
Implementation Method 1
A power factor correction circuit with a capacitor (52) is provided. The controllable charging means (44) charges the capacitor (52) with the sinusoidal AC line voltage (35) rectified with the rectification circuit (26) in such a way that a capacitor voltage (57) is generated from the sinusoidal AC line voltage (35)
Implementation Method 2
An actual value is determined from the capacitor voltage (57) with the control circuit (40), and the controllable charging means (44) is controlled in such a way that an actual value determined from the capacitor voltage (57) is regulated to a desired value with the control circuit (40)
Implementation Method 3
A driver output current (89) is generated with the current regulator (82), with which LEDs (17a to 17c) connected to the driver circuit are operated at an operating point
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a driver circuit 10 and a method for supplying LEDs 17a to 17c with a sinusoidal AC mains voltage 18. To supply the LEDs, the sinusoidal AC mains voltage 18 is rectified and fed to a power factor correction circuit 36. The power factor correction circuit 36 charges a capacitor 52 with the rectified sinusoidal AC mains voltage 35. The capacitor 52 is charged by the power factor correction circuit 36 in such a way that an actual value determined from a capacitor voltage 57 of the capacitor 52 is regulated to a setpoint as far as possible by controlling the charging process. Furthermore, the driver circuit 10 includes a current regulator 82 with which a regulated driver output current 89 is generated from the capacitor voltage 57.The voltage drop 109 across the current regulator 82 is determined using a measuring instrument 108, and an influence factor is defined based on the determined voltage 109. Depending on this influence factor, the determined actual value of the power factor correction circuit 36 is manipulated by an influence circuit 72. Furthermore, the invention relates to a light source 12 with the driver circuit 10 according to the invention.