AC Power Dimmer Pulse Control for Flicker-Free LED Dimming
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Solution Overview
Problem
Existing methods for regulating power supply to electrical loads, such as LED or fluorescent bulbs, are inadequate as they cause flickering or buzzing due to phase shift issues and require significant current consumption, and do not allow for complete extinction or low power consumption.
Innovation Solution
A method that adjusts the number of current pulses during each half-period of an alternating current to supply the load, using a power dimmer with a pulse generator and Darlington transistors to control the current pulses, allowing for low power consumption and complete extinction of the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase angle control is used to regulate power supply to LED or fluorescent bulbs, then power regulation is achieved, but the bulbs exhibit flickering and buzzing due to phase shift limitations
Solution Approach 1:
The patent applies periodic action by using Pulse Width Modulation (PWM) to switch the power supply to the bulb in periodic pulses rather than continuous phase angle control. The control unit generates PWM signals that periodically switch the triac on and off, providing stable power regulation without the flickering and buzzing caused by phase shift limitations in traditional phase angle control methods.
2Power
If MOS type transistor is used for rising phase control, then power regulation is achieved, but significant current is required to operate the transistor which disrupts low-power bulb operation
Solution Approach 1:
The patent replaces the MOS type transistor mechanical/electronic switching system with a triac-based PWM control system. The triac is controlled by low-current PWM signals from a microcontroller, eliminating the need for high current to drive a MOS transistor while achieving the same power regulation function. This substitution allows low-power bulb operation without significant control current consumption.
3Power
If PWM control is used for power regulation, then power adjustment is achieved, but zero illumination cannot be imposed on the bulb
Solution Approach 1:
The patent applies preliminary action by designing the PWM control system with sufficient pulse frequency and duty cycle resolution to allow complete extinction. The control unit can set the PWM duty cycle to 0%, completely blocking power supply to the bulb before any operation begins, ensuring zero illumination capability is built into the system design rather than requiring additional components or complex control logic.
4Illumination intensity
If phase angle control with delay angle close to 180° is used for low illumination, then dimming is achieved, but only fine pulses are delivered causing flashing and buzzing
Solution Approach 1:
The patent uses periodic PWM action with optimized pulse frequency and duty cycle to achieve dimming without flashing and buzzing. Instead of using delay angles close to 180° that produce fine pulses, the system maintains a consistent PWM frequency and adjusts the duty cycle to control illumination intensity, ensuring stable operation without the flashing and buzzing artifacts of extreme phase angle control.
Data Source
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AI summary
The invention relates to a method for regulating the power of an electrical load (1) supplied by an alternating current source of period T, the load being connected in series with a power dimmer (2) generating, for each half period T/2 of the alternating current, a number N of current pulses intended to supply said load, the method comprising adjusting the number N according to the power to be delivered to the electrical load (1).