Bleeder Circuit Controller for Phase Cut Dimmers
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Solution Overview
Problem
Phase cut dimmers face reliability issues when used with solid state lighting, as they require a minimum load and 'latching current' to transition from off-state to on-state, which is not efficiently managed by traditional bleeder circuits, especially with efficient dimmable LEDs.
Innovation Solution
A bleeder circuit controller that uses a bipolar junction transistor (BJT) to control bleed current, generating a control signal based on measured current flow through the phase cut dimmer, applying current limits to maintain the BJT in a linear or edge-of-saturation operation mode, ensuring efficient current sink capability and minimizing drive current loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional bleeder circuit is used with phase cut dimmer and solid state lighting, then the circuit can provide a bleed current path, but the operation is inefficient and causes energy wastage especially during low output voltage states
Solution Approach 1:
The patent applies dynamics by transitioning the BJT from fixed saturation mode to dynamically controlled linear/edge-of-saturation mode. The BJT operating state is continuously adjusted based on real-time monitoring of output voltage and current, allowing the circuit to adapt its bleed current characteristics to match actual operational needs, thereby reducing energy wastage while maintaining reliability.
Solution Approach 2:
The patent changes the operating parameters of the BJT from fixed saturation to variable linear/edge-of-saturation mode. By dynamically adjusting the base-emitter voltage and collector current based on monitored output conditions, the circuit optimizes the bleed current magnitude, preventing excessive energy consumption during low voltage states while ensuring adequate current during critical transitions.
2Reliability
If the bipolar junction transistor operates in saturation mode, then the bleed current is sufficient for dimmer operation, but the drive current loss increases
Solution Approach 1:
The patent changes the BJT operating parameters from fixed saturation mode to variable linear/edge-of-saturation mode. The controller dynamically adjusts the base drive current and collector-emitter voltage based on real-time output conditions, optimizing the balance between providing sufficient bleed current for dimmer reliability and minimizing drive current loss through reduced base-emitter voltage drops.
3Loss of energy
If the bleeder circuit adapts to low output voltage states, then energy efficiency improves, but the circuit complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the output voltage and current of the phase cut dimmer and using this information to dynamically adjust the BJT operating state. The controller receives real-time feedback signals and modifies the base drive accordingly, enabling energy-efficient adaptation to low voltage states without requiring complex external control circuitry.
Solution Approach 2:
The patent applies self-service by enabling the bleeder circuit to automatically adjust its own operation based on monitored output conditions. The BJT controller autonomously determines the appropriate operating mode (linear or edge-of-saturation) and adjusts base-emitter voltage and collector current without external intervention, reducing the need for additional control components.
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 bleeder circuit controller effectively manages bleed current, ensuring reliable operation of phase cut dimmers with solid state lighting by adapting to changes in current flow and maintaining efficient operation, even during low output voltage states, thus enhancing compatibility and reducing energy wastage.
Implementation Method 1
A bleeder circuit controller, configured to control the bipolar junction transistor, the bleeder circuit controller is further configured to generate a control signal for controlling the bleed current through the bipolar junction transistor
Data Source
Figure 1~3
Figure 2
AI summary
A bleeder circuit controller (11) configured to control a bipolar junction transistor (10) having a collector (12) configured to be connected to an output of a phase cut dimmer (2) for receiving a bleed current, an emitter (13) for connecting to ground and a base (14), the bleeder circuit controller configured to generate a control signal for controlling the bleed current through the bipolar junction transistor (10) and measure a signal indicative of the current flow through the dimmer (2) and apply a current limit to a base-emitter current flow as a function of the measured signal.