Triac Dimmer Compatible SMPS Eliminating Dummy Load
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Solution Overview
Problem
The integration of a triac dimmer in switching mode power supplies for LED drivers is inefficient due to the need for a bleeder dummy load, which reduces overall efficiency and is not compatible with power factor correction, leading to suboptimal performance in controlling light dimming.
Innovation Solution
The implementation of a power factor correction (PFC) controller in the switching mode power supply eliminates the dummy load by using the DC/DC converter to maintain a minimum conducting current in the triac dimmer, reducing LC resonance and enabling more precise control of the triac dimmer's phase angle for efficient dimming without the dummy load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder dummy load is used to maintain minimum conducting current in the triac dimmer, then the triac dimmer can operate reliably, but the overall efficiency of the power supply is reduced
Solution Approach 1:
The patent removes the dummy load from the circuit by using the DC/DC converter to provide the minimum conducting current directly to the triac dimmer. This extraction of the dummy load function eliminates the energy waste while maintaining the triac's reliable operation.
Solution Approach 2:
The DC/DC converter is made multi-functional by having it serve both as the main power conversion device and as the current source for the triac dimmer. This eliminates the need for a separate dummy load while ensuring the triac receives the necessary minimum current for reliable operation.
2Stability of the object's composition
If a bleeder dummy load is used to reduce LC resonance, then the circuit stability is improved, but the overall efficiency is reduced
Solution Approach 1:
The dummy load function is extracted and replaced by the DC/DC converter, which provides the necessary current to suppress LC resonance without the energy waste associated with traditional dummy loads.
Solution Approach 2:
The DC/DC converter serves itself by using its own output current to provide the minimum conducting current for the triac dimmer, eliminating the need for a separate dummy load and reducing overall energy loss while maintaining circuit stability.
3Reliability
If a dummy load is used in the triac dimmer circuit, then the minimum conducting current is maintained, but power factor correction is compromised
Solution Approach 1:
The DC/DC converter is designed to perform multiple functions: main power conversion, providing minimum conducting current for the triac, and supporting power factor correction. This multi-functionality resolves the conflict between maintaining minimum current and achieving PFC compatibility.
Solution Approach 2:
The control circuit uses feedback from the rectified voltage to dynamically adjust the DC/DC converter's output, ensuring the triac receives the necessary minimum current while maintaining power factor correction effectiveness.
Data Source
AI summary
Triac dimmer compatible switching mode power supplies used as LED drivers are disclosed herein. A PFC controller is configured in the switching mode power supplies. With the PFC controller, the current keeping the triac in the on-state is supplied by the DC/DC converter, and the LC resonance is reduced.