Driver Circuit Supply Voltage Management for Solid State Lighting
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Solution Overview
Problem
The start-up and maintenance of a supply voltage for the integrated circuit in a driver circuit for solid state light sources, particularly when used with phase-cut dimmers, require high capacitance values, leading to increased power losses, longer start-up times, and higher costs, while also potentially causing flickering effects due to the impact of IC current on LED current.
Innovation Solution
A driver circuit utilizing a switched-mode power converter with a transformer, a supply voltage capacitor, and a supply voltage transistor to maintain the supply voltage within a predetermined interval, ensuring reliable operation and energy efficiency, while minimizing the impact of IC current on LED current through controlled operation of the power converter switch and supply voltage transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high capacitance values of supply voltage capacitor are used to maintain stable supply voltage with phase-cut dimmers, then supply voltage stability is improved, but start-up time increases and start-up current increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the supply voltage capacitor to a first threshold voltage before enabling the power converter switch. This preliminary charging phase allows the capacitor to be partially charged using only the start-up resistor, reducing the burden on the resistor during normal operation and enabling faster start-up while maintaining voltage stability during dimming operations.
Solution Approach 2:
The patent implements dynamics by dynamically switching between different charging paths for the supply voltage capacitor. A first charging path through the start-up resistor is used during initial start-up, while a second charging path through the power converter switch is used during normal operation. The controller dynamically enables or disables these paths based on the charging state of the capacitor, optimizing both start-up time and voltage stability.
2Stability of the object's composition
If high capacitance values of supply voltage capacitor are used to maintain stable supply voltage, then supply voltage stability is improved, but power losses increase
Solution Approach 1:
The patent applies preliminary action by pre-charging the supply voltage capacitor to a first threshold voltage before enabling the power converter switch. This preliminary charging phase allows the capacitor to be partially charged using only the start-up resistor, reducing the burden on the resistor during normal operation and enabling faster start-up while maintaining voltage stability during dimming operations.
Solution Approach 2:
The patent implements dynamics by dynamically switching between different charging paths for the supply voltage capacitor. A first charging path through the start-up resistor is used during initial start-up, while a second charging path through the power converter switch is used during normal operation. The controller dynamically enables or disables these paths based on the charging state of the capacitor, optimizing both start-up time and voltage stability.
3Stability of the object's composition
If high capacitance values of supply voltage capacitor are used, then supply voltage stability is improved, but component costs increase
Solution Approach 1:
The patent applies preliminary action by pre-charging the supply voltage capacitor to a first threshold voltage before enabling the power converter switch. This preliminary charging phase allows the capacitor to be partially charged using only the start-up resistor, reducing the burden on the resistor during normal operation and enabling faster start-up while maintaining voltage stability during dimming operations.
Solution Approach 2:
The patent implements dynamics by dynamically switching between different charging paths for the supply voltage capacitor. A first charging path through the start-up resistor is used during initial start-up, while a second charging path through the power converter switch is used during normal operation. The controller dynamically enables or disables these paths based on the charging state of the capacitor, optimizing both start-up time and voltage stability.
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
This solution reduces power losses, shortens start-up times, and prevents flickering by maintaining a stable supply voltage and separating the recharging of the supply voltage capacitor from the operation of the power converter, thereby enhancing system efficiency and reducing costs.
Implementation Method 1
a transformer, a primary coil of the transformer being arranged in series with the power converter switch
Implementation Method 2
a supply voltage capacitor coupled to the controller and configured to provide a supply voltage to the controller
Implementation Method 3
The power converter switch may comprise a transistor, e.g. a metal oxide semiconductor field effect transistor
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The present document relates to a driver circuit for a solid state light source. In particular, the present document relates to the start-up and/or the maintenance of a supply voltage for the integrated circuit of a driver circuit. A driver circuit (300) for a solid state light source (309) is described. The driver circuit (300) comprises a switched-mode power converter comprising a power converter switch (202) and a transformer (307). The switched-mode power converter is configured to convert an input voltage (230) at an input of the switched-mode power converter into an output voltage (231) at an output of the switched-mode power converter (200). Furthermore, the driver circuit (300) comprises a controller (306) configured to generate a gate control signal (232) for putting the power converter switch (202) into an on-state and/or an off-state. In addition, the driver circuit (300) comprises a supply voltage capacitor (310) coupled to the controller (306) and configured to provide a supply voltage to the controller (306). A primary coil (314) of the transformer (307) is arranged in series with the power converter switch (202), a secondary coil arrangement (313, 315) of the transformer (307) is configured to provide the output voltage (231), the secondary coil arrangement (313, 315) is coupled to the supply voltage capacitor (310) via a supply voltage transistor (350), and the supply voltage transistor (350) is controlled such that the supply voltage provided by the supply voltage capacitor (310) lies within a pre-determined voltage interval.