Solid State Lamp Control for Trailing Edge Dimmers
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Solution Overview
Problem
Solid state lamps, particularly LED-based lamps, face challenges with leading edge and trailing edge phase cut dimmers due to the requirement of maintaining a minimum holding current to prevent triac device reset, leading to inefficiencies and compatibility issues with varying triac devices, which are exacerbated by the need for a bleeder circuit that reduces operational efficiency.
Innovation Solution
A lamp system with a controller that enables on and off switching cycles of the power switch based on a regulation threshold determined by feedback from previous AC half cycles, minimizing bleeder circuit activation during peak energy levels, thereby reducing power dissipation and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder circuit is added to maintain minimum holding current for the triac, then the triac remains in the on state and light flicker is prevented, but the operational efficiency of the lamp is reduced due to increased power dissipation
Solution Approach 1:
The patent applies dynamics by making the bleeder circuit switchable rather than continuously active. The bleeder switch is controlled dynamically based on real-time detection of triac state and holding current requirements, allowing the system to adapt between maintaining stability and minimizing energy loss depending on operational conditions.
Solution Approach 2:
The patent implements feedback by continuously monitoring the triac holding current and adjusting the bleeder circuit activation accordingly. The controller detects when the holding current threshold is approached and activates the bleeder switch only when necessary, creating a closed-loop control system that prevents unnecessary power dissipation while ensuring triac stability.
2Adaptability or versatility
If the bleeder circuit is continuously active to ensure triac operation, then compatibility with dimmer switches is improved, but the lamp draws excessive current from the AC mains
Solution Approach 1:
The system dynamically adjusts the bleeder circuit operation based on detected dimmer switch types and operational phases. The controller modifies bleeder activation patterns to match the specific dimmer compatibility requirements while minimizing overall current draw through intelligent timing and duration control.
Solution Approach 2:
The patent employs periodic action by activating the bleeder circuit in periodic pulses rather than continuously. The controller monitors AC mains cycles and triggers bleeder activation at specific periodic intervals when needed for dimmer compatibility, reducing average current draw while maintaining compatibility during critical phases.
3Illumination intensity
If the power switch operates continuously to maintain output regulation, then the LED output remains stable, but power dissipation increases during periods when dimmer disconnects the AC mains
Solution Approach 1:
The patent applies preliminary action by detecting when the dimmer is about to disconnect the AC mains and pre-adjusting the power switch operation. The controller anticipates the disconnection event and modifies switching cycles in advance, allowing the LED output to remain stable during the transition while minimizing energy dissipation during the disconnected period.
Solution Approach 2:
The power switch operation is made dynamic by continuously adapting switching frequency and duty cycle based on real-time detection of dimmer disconnection states. The controller reduces or suspends power switch cycles during AC mains disconnection periods while maintaining LED output stability through controlled energy discharge from storage elements.
Data Source
AI summary
Intelligent control of a solid state lamp when coupled to a trailing edge phase cut dimmer switch is provided. On and off cycles of the lamp's power stage switch are enabled during a period when the energy in the bulk capacitor is at its highest levels. During this period a bleeder circuit does not have to be enabled, which results in a greater operational efficiency as compared with normal switching schemes for trailing edge dimmers.