LED Driver Phase Angle Detection via Converter Voltage Dip
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Solution Overview
Problem
Existing LED driver solutions face challenges in achieving high power factor, reduced losses, and low cost, particularly with phase cut dimming, where accurate phase angle detection is difficult and results in increased power loss due to bleeding currents.
Innovation Solution
A driver device and method that includes input terminals, a converter unit, a signal control device, and a detection circuit to detect the phase angle of the input voltage by measuring a voltage drop in the converted voltage, avoiding bleeding currents by creating a controlled voltage dip with an electrical signal, thereby reducing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bleeder circuit with bleeder resistors is used to drain the charged capacitor and detect the dimmer off state, then the phase angle detection is enabled, but the power loss increases due to bleeding current
Solution Approach 1:
The patent extracts the harmful bleeder resistors from the circuit and replaces them with a detection method that uses the existing converter circuitry. The phase angle detection is achieved by monitoring the converter's internal voltage drop during the switching cycle, eliminating the need for separate bleeder components that consume continuous power.
Solution Approach 2:
The converter circuit serves dual purposes: it both converts the rectified voltage to drive the LED load and simultaneously provides the voltage drop signal needed for phase angle detection. The detection circuit utilizes the converter's own operational characteristics rather than requiring separate dedicated detection hardware, thereby reducing overall power consumption.
2Loss of energy
If trailing edge phase cut dimmers are used to control lamp power, then the efficiency is improved and power loss is reduced, but the voltage step edge becomes insignificant and difficult to detect
Solution Approach 1:
Instead of detecting the phase angle from the voltage waveform directly (time domain), the patent transforms the detection approach by monitoring the voltage drop across the converter circuit during its switching cycle. This dimensional shift from external voltage edge detection to internal converter state monitoring enables accurate phase angle measurement even with trailing edge dimming where external voltage edges are insignificant.
Solution Approach 2:
The converter circuit acts as an intermediary between the dimmer and the detection circuit. Rather than detecting the dimmer's output voltage edges directly, the detection circuit monitors the converter's response to the dimmed voltage, using the converter's switching behavior as a mediator to extract phase angle information that would otherwise be lost in trailing edge dimming scenarios.
3Loss of energy
If phase cut dimming is used to control power delivery to LEDs, then the efficiency is improved, but accurate phase angle detection becomes difficult resulting in increased power loss
Solution Approach 1:
The converter circuit serves dual purposes: it both converts the rectified voltage to drive the LED load and simultaneously provides the voltage drop signal needed for phase angle detection. The detection circuit utilizes the converter's own operational characteristics rather than requiring separate dedicated detection hardware, thereby reducing overall power consumption.
Solution Approach 2:
The detection circuit continuously monitors the voltage drop across the converter during each switching cycle and uses this feedback to accurately determine the phase angle. This real-time feedback mechanism enables precise phase angle detection under phase cut dimming conditions, allowing the system to maintain optimal operating parameters and minimize power loss.
Data Source
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AI summary
The present invention relates to a driver device (60) for driving a load (12), in particular an LED unit comprising one or more LEDs, said driver device comprising input terminals (28, 30) for receiving an input voltage (V12) from an external power supply (16), output terminals for providing an output voltage to the load (12) for driving the load (12), a converter unit (34) for converting the input voltage (VI 2) to a converted voltage (VI 4) and for providing the converted voltage (VI 4) to internal connection elements (63, 64) of the driver device (60), a signal control device (62) for applying an electrical signal (I) to at least one of the connection elements (63, 64), and a detection circuit for detecting a phase angle of the input voltage (VI 2) by measuring a voltage drop of the converted voltage (VI 4) caused by the electrical signal (I).