Powerless Bleeder Controller for LED Dimmer Compatibility
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Solution Overview
Problem
Solid state lighting devices, such as LED or OLED assemblies, are not compatible with conventional phase-cut dimmers due to their low power consumption and nonlinear behavior, leading to unreliable operation and increased power losses when attempting to emulate dimming functionality.
Innovation Solution
A controller for a driver circuit that operates a switched-mode power converter to regulate the output voltage and manage the commutation cycle and duty cycle, allowing the solid state light bulb assembly to operate stably with dimmers while maintaining power efficiency by determining the dimmer's on- and off-phases and generating control signals to manage energy transfer and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase-cut dimmers are used with solid state lighting devices, then dimming functionality is achieved, but the operation becomes unreliable due to low power consumption and nonlinear behavior
Solution Approach 1:
A controller is introduced as an intermediary device between the phase-cut dimmer and the solid state lighting driver circuit. The controller detects the dimmer's on- and off-phases and generates appropriate control signals to manage the power converter's operation, ensuring reliable dimming functionality while preventing multi-firing issues caused by the nonlinear behavior of LED drivers
Solution Approach 2:
The controller dynamically changes operational parameters of the power converter based on the detected dimmer phase. During the dimmer on-phase, the controller regulates the power converter to transfer energy to the output; during the off-phase, it prevents energy transfer, thereby adapting the system's electrical characteristics to match the dimmer's switching behavior and ensuring stable operation
2Ease of operation
If additional circuits are added to emulate dimming functionality, then dimming capability is achieved, but power losses increase and costs rise
Solution Approach 1:
The controller performs multiple functions using a single circuit: it detects dimmer phases, generates control signals for the power converter, prevents multi-firing, and manages energy transfer. This multi-functional approach eliminates the need for separate dimming emulation circuits, thereby reducing additional power losses and component costs while maintaining full dimming capability
Solution Approach 2:
The controller utilizes the existing power converter circuitry to achieve dimming functionality by controlling its operation modes rather than requiring separate dedicated dimming circuits. The power converter itself performs the dimming function when properly controlled, eliminating the need for additional power-consuming dimming-specific components
3Reliability
If the power converter operates in steady-state mode, then output voltage is regulated, but compatibility with dimmers is poor due to low load current
Solution Approach 1:
The controller dynamically switches the power converter between different operational modes based on the dimmer phase detection. During the dimmer on-phase, the converter operates in steady-state mode for proper voltage regulation; during the off-phase, it enters a switched mode to prevent multi-firing. This dynamic mode switching adapts the converter's behavior to the varying load conditions imposed by phase-cut dimmers
Solution Approach 2:
The controller implements periodic switching between operational modes synchronized with the dimmer's AC cycle. The power converter alternates between steady-state voltage regulation during the on-phase and a special switched mode during the off-phase, creating a periodic operation pattern that ensures both voltage regulation and dimmer compatibility by preventing the converter from drawing continuous current that would cause multi-firing
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
Ensures reliable operation of solid state lighting devices with dimmers, preventing multi-firing and energy wastage, and maintaining high efficiency by controlling the power converter's operation based on dimmer phases and current levels.
Implementation Method 1
the switched-mode power converter may comprise a switch which is configured to alternate the power converter between a first state and a second state. In the first state, the power converter may draw power (e.g. a current) from an input of the power converter and in the second state, the power converter may transfer the power (e.g. a current) towards an output of the power converter.
Implementation Method 2
the controller may be configured to receive a signal indicative of the output voltage. Furthermore, the controller may be configured to generate a control signal for the driver circuit (e.g. a gate control voltage for a gate of the switch of the switched-mode power converter) based on the signal indicative of the output voltage.
Data Source
AI summary
A power efficient method and system for ensuring a reliable operation of dimmers in conjunction with solid state lighting devices such as LED or OLED assemblies is presented. A controller for a driver circuit of a solid state light bulb assembly is described. The solid state light bulb assembly comprises a solid state light source. The driver circuit comprises a switched-mode power converter. The controller is configured to receive an input voltage indicative of a mains electricity supply submitted to a dimmer; to determine that the dimmer is in an off-phase, based on the input voltage; and, if it is determined that the dimmer is in an off-phase, to generate a control signal for the switched-mode power converter to operate the switched-mode power converter in a switched mode for discharging one or more capacitances at an input of the switched-mode power converter.