PWM Dimmer for LED Luminaires Eliminates Flicker
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dimmers, such as leading and trailing edge dimmers, are incompatible with LED-based luminaires, causing issues like flicker, audible noise, and shimmer due to their phase-cut AC load signals, which lead to compatibility problems and a suboptimal user experience.
Innovation Solution
A pulse width modulated (PWM) dimmer is introduced, which provides a pulsed AC load signal that tracks the sinusoidal envelope of the AC supply signal, allowing for precise control of dimming levels and avoiding phase-cut issues by using a power stage and control circuitry to generate a pulsed AC load signal with varying duty cycles based on user input or remote control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional leading or trailing edge dimmers are used with LED-based luminaires, then dimming control is achieved, but flicker, audible noise, and shimmer occur due to phase-cut AC load signals
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to generate a pulsed AC load signal that delivers power in controlled pulses rather than continuous phase-cutting. The power stage switches the AC signal on and off periodically according to the desired dimming level, eliminating the harmful effects of traditional phase-cut dimming while maintaining effective dimming control.
2Ease of operation
If phase-cut AC load signals are used for dimming, then dimming levels are controlled, but compatibility issues arise with LED-based luminaires
Solution Approach 1:
The patent changes the fundamental parameter of the AC load signal from phase-cut waveform to pulsed waveform with full sinusoidal cycles. By maintaining complete AC cycles and controlling power delivery through pulse width modulation rather than phase-cutting, the system achieves compatibility with LED-based luminaires while preserving dimming control functionality.
3Reliability
If a PWM dimmer with power stage and control circuitry is implemented, then compatibility and stability are improved, but device complexity increases
Solution Approach 1:
The patent introduces a power stage as an intermediary component between the AC supply and the LED-based luminaires. This power stage acts as a mediator that conditions the AC signal into appropriate pulsed waveforms, isolating the LED luminaires from the complexity of dimming control while ensuring reliable and compatible operation.
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 PWM dimmer effectively eliminates flicker, shimmer, and audible noise, providing a stable and compatible lighting solution for LED-based luminaires by adjusting the RMS value of the pulsed AC load signal to match desired dimming levels, enhancing user experience and compatibility.
Implementation Method 1
A pulse width modulated (PWM) dimmer is disclosed. The PWM dimmer includes a source terminal, a load terminal, a power stage, an interface, and control circuitry. The power stage is coupled between the source terminal and the load terminal and is configured to receive from the source terminal an AC supply signal and provide a pulsed AC load signal to the load terminal in response to a control signal.
Implementation Method 2
The control circuitry is configured to receive the dimming control information from the interface and generate the control signal based on the dimming control information. When driven by the control signal, the power stage will provide the pulsed AC load signal such that an RMS (root mean square) value of the pulsed AC load signal corresponds with the desired dimming level and varies as the dimming level varies corresponding to the desired dimming level.
Data Source
AI summary
A PWM dimmer includes a source terminal, a load terminal, a power stage, an interface, and control circuitry. The power stage is coupled between the source terminal and the load terminal and is configured to receive from the source terminal an AC supply signal and provide a pulsed AC load signal to the load terminal in response to a control signal. The AC supply signal has a sinusoidal envelope with a positive half-cycle and a negative half-cycle for each cycle. The pulsed AC load signal tracks the envelope and includes a plurality of pulses in the positive half-cycle and the negative half-cycle for each cycle. The interface is configured to receive dimming control information bearing on a dimming level from a user or remote terminal. The control circuitry is configured to receive the dimming control information from the interface and generate the control signal based on the dimming control information.