LED Driver Circuit Synchronizes Switching Frequency with Ballast
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Solution Overview
Problem
Existing driver circuits for light emitting diodes (LEDs) are inefficient due to high power losses and unnecessary branch switches, and they suffer from interference caused by unsynchronized switching frequencies.
Innovation Solution
A driver circuit with a rectifier, switch circuit, and controller that synchronizes the switching frequency with the fluorescent ballast's frequency, reducing power losses and avoiding branch switches by converting AC to DC efficiently and using a detuning circuit to match impedances and filter interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching frequency of the switch circuit is set much higher than the frequency of the first current signal, then the power supply control is more responsive, but power losses increase significantly
Solution Approach 1:
The patent changes the switching frequency parameter from high frequency to equal to or lower than twice the frequency of the first current signal. This parameter change directly reduces power losses while maintaining adequate power supply control responsiveness for LED operation.
2Adaptability or versatility
If branch switches are added to control power to the load, then power distribution flexibility is improved, but device complexity and power losses increase
Solution Approach 1:
The patent removes the unnecessary branch switch from the circuit configuration. By extracting this redundant component, the invention simplifies the device structure and reduces power losses associated with the branch switch, while the main switch circuit maintains adequate power distribution control.
3Adaptability or versatility
If the switching frequency of the switch circuit is not synchronized with the fluorescent ballast frequency, then the circuit operation is independent and flexible, but interference occurs between the two circuits
Solution Approach 1:
The patent implements frequency synchronization by using the fluorescent ballast's operating frequency as a reference to control the switch circuit's switching frequency. This feedback mechanism ensures that the switch circuit operates in coordination with the ballast, eliminating interference while maintaining system-wide adaptability.
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 significantly reduces power losses and minimizes interference, enhancing the efficiency of the driver circuit while avoiding the need for branch switches, thus improving the overall performance of LED lighting systems.
Implementation Method 1
a rectifier for exchanging a first current signal with a fluorescent ballast and for supplying a second current signal to the load, the first current signal being an alternating-current (AC) current signal, and the second current signal being a direct-current (DC) current signal
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Driver circuits (1) for driving loads (2) comprising light emitting diodes are provided with rectifiers (11-14) for exchanging first current signals with fluorescent ballasts (3) such as active electronic ballasts and for supplying second current signals to the loads (2), with switch circuits (21-27) coupled to or forming part of the rectifiers (11-14) for controlling amounts of power supplied to the loads (2), and with controllers (31) for controlling the switch circuits (21-27) such that switching frequencies of the switch circuits (21-27) are equal to or lower than twice the frequencies of the first current signals. Detuning circuits (4) match output impedances of the fluorescent ballasts (3) and input impedances of the rectifiers (11-14). Start-up circuits (5) increase impedances at input terminals of the rectifiers (11-14) at start-up. Current sensors (6) and voltage sensors (7) provide feedback. The controllers (31) synchronize the switching frequencies of the switch circuits (21-27) and switching frequencies of the active electronic ballasts. Detectors (8) detect zero crossings in the first current signals.