LED Illumination Device Decoupling Power from Phase-Cut Dimming Angles
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Solution Overview
Problem
Conventional phase-cut dimmers provide inconsistent performance when used with LED loads due to the mismatch between the resistive load characteristics of incandescent bulbs and the diode-capacitor power supply of LEDs, leading to inconsistent brightness control and sensitivity to AC mains voltage variations, transients, and drift, which limits the range and precision of dimming.
Innovation Solution
An illumination device with a microcontroller-based control circuit decouples the power delivered to the LED load from the phase-cut dimming angle, using a dual-stage power supply with slow and fast control loops to regulate the LED drive current independently of the dimmer's conduction angle, and includes damping and bleeding circuits to remove AC transients and DC drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase-cut dimmers are used to control LED brightness, then power delivery can be adjusted, but brightness control becomes inconsistent due to mismatch between resistive load characteristics and diode-capacitor power supply
Solution Approach 1:
The patent introduces an intermediary control system between the phase-cut dimmer and the LED power supply. This intermediary measures the actual power delivered to the LED and adjusts the power supply output accordingly to achieve the desired brightness level, compensating for the inconsistent behavior of phase-cut dimmers with LED loads.
Solution Approach 2:
The patent implements a feedback mechanism where the actual power delivered to the LED is measured and used to adjust the power supply output. This closed-loop control ensures consistent brightness control by continuously monitoring and correcting for variations in the phase-cut dimmer behavior and LED load characteristics.
2Adaptability or versatility
If phase-cut dimmers are used with LED loads, then dimming function is achieved, but performance is sensitive to AC mains voltage variations, transients, and drift
Solution Approach 1:
The patent uses feedback control to monitor the actual power delivered to the LED and adjust the power supply output accordingly. This compensates for AC mains voltage variations, transients, and drift, maintaining stable LED brightness despite changes in the input power conditions.
Solution Approach 2:
The patent dynamically adjusts power supply parameters based on measured conditions. By changing the power delivery parameters in response to detected variations in AC mains voltage and load conditions, the system maintains consistent LED brightness performance across varying operating conditions.
3Productivity
If conventional power supply is used with phase-cut dimmers, then basic LED operation is achieved, but dimming range is limited and precision is reduced
Solution Approach 1:
The patent implements precise feedback control where the actual power delivered to the LED is measured and used to adjust the power supply output. This enables precise brightness control over a wide dimming range, allowing the LED to be dimmed accurately from full brightness down to very low levels (0.1% of maximum brightness).
Solution Approach 2:
The patent uses dynamic control to adapt the power delivery in real-time based on measured conditions. This enables the system to maintain precise brightness control across the entire dimming range, adjusting the power supply output dynamically to achieve the desired brightness level with high precision.
Data Source
AI summary
An illumination device and method are provided for controlling light emitting diodes (LEDs). The LEDs (specifically, the LED loads) are controlled, e.g., brightness and color of the LED loads, independent of a phase-cut dimmer applied to the AC mains feeding a DC power supply. The power supply is active dependent upon the duration of a conduction angle supplied from the dimmer. The power supply, however, produces drive currents that are independent from the conduction angle by using a two-stage power supply and a relatively slow and fast control loops that are controlled through a microprocessor based control circuit. Parameters stored in the control circuit are drawn by the microprocessor to control the two-stage power supply to produce the drive currents independent and decoupled from the conduction angle yet dependent on the controller parameters.