AC Phase Dimmable LED Driver With Digital PWM Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current AC phase dimmable LED lighting systems require a fixed live input connection, which is not available in retro-fitted installations, and can only operate in constant-current mode, limiting their applicability to LED lighting systems that require a constant-voltage power source.
Innovation Solution
A circuit with digital processing circuitry and a DC output chopper generates a pulse width modulated signal to produce a chopped DC output duty cycle voltage, enabling linear dimming for LED loads without a fixed live input, using a combination of analog and digital processing to regulate DC output and provide current limiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If AC phase dimmable converters operate without a fixed live input connection, then ease of installation is improved for retro-fitted applications, but the converter can only operate in constant-current mode which limits adaptability to constant-voltage LED lighting systems
Solution Approach 1:
The patent changes the operational parameters of the LED driver by implementing a duty-cycle controlled PWM output that can operate in both constant-current and constant-voltage modes. The digital processing circuitry adjusts the duty cycle of the PWM signal to regulate either output current or output voltage based on the specific LED lighting system requirements, enabling the same hardware to adapt to different operational modes without requiring fixed live input connections.
2Ease of operation
If constant-voltage LED lighting systems are dimmed by manipulating DC voltage level or duty cycle, then dimming control is achieved, but the LED light output changes non-linearly
Solution Approach 1:
The patent implements feedback control through digital processing circuitry that monitors the LED lighting system's response and dynamically adjusts the PWM duty cycle to achieve linear dimming. The system measures the actual light output or electrical parameters and uses this feedback information to compensate for non-linearities, ensuring that the perceived brightness decreases linearly with the dimming control signal while maintaining stable constant-voltage output.
Data Source
AI summary
A method and circuit for dimmable light emitting diode (LED) applications are provided. The circuit includes digital processing circuitry and a DC output chopper. The digital processing circuitry produces a pulse width modulated (PWM) signal in response to one or more of voltage, frequency, dimmer type and phase angle requirements determined from a voltage and a phase position of a received input signal. The DC output chopper is coupled to the digital processing circuitry and operates in response to the PWM signal to generate a chopped DC output duty cycle voltage signal from a DC output signal derived from the input signal to provide linear dimming for a LED load.