Back-up Capacitor Driver Circuit for Fast Start-up
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Solution Overview
Problem
High voltage power supplies for light bulb assemblies face challenges in achieving short start-up times and bridging brief interruptions of the mains supply without increasing costs, as high capacitance capacitors prolong start-up times and additional transistors add components and cost.
Innovation Solution
A driver circuit with a switched-mode power converter, a controller, a supply voltage capacitor, and a back-up capacitor, where the supply voltage capacitor is charged during start-up and the back-up capacitor maintains operation during interruptions, allowing for quick start-up and prolonged bridging of interruptions without additional transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If capacitors with high capacitance are used to provide supply voltage to the controller, then the power supply can bridge brief interruptions of the mains supply, but the start-up time of the power supply increases
Solution Approach 1:
The patent divides the capacitance function into two separate capacitors: a first capacitor (C1) responsible for start-up and a second capacitor (C2) responsible for bridging interruptions. This segmentation allows each capacitor to be optimized for its specific function, with C1 having lower capacitance for fast charging and C2 having higher capacitance for extended energy storage, thereby resolving the contradiction between fast start-up and long bridging duration
Solution Approach 2:
The first capacitor (C1) is charged during the start-up phase to provide initial supply voltage to the controller, enabling the controller to become operational before the second capacitor (C2) is fully charged. This preliminary action allows the system to achieve fast start-up while the second capacitor prepares to provide extended energy storage for bridging interruptions
2Loss of time
If additional start-up transistors are used within the power supply, then the power supply can achieve short start-up times and bridge interruptions, but the cost of the power supply increases
Solution Approach 1:
The controller uses its own output terminal to control the coupling and decoupling of the first and second capacitors, eliminating the need for additional dedicated start-up transistors. The controller self-manages the capacitor switching function that would otherwise require separate control components, thereby reducing component count and cost while maintaining the ability to achieve fast start-up and bridge interruptions
Solution Approach 2:
The controller's output terminal is made multi-functional: it serves both its primary control function for the power converter and additionally functions as the control switch for capacitor coupling/decoupling. This universality eliminates the need for dedicated start-up transistors, reducing device complexity while maintaining all required functions
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 solution enables short start-up times and extended bridging of interruptions, enabling dimming control through 'Off/On' events without phase-cut dimmers, reducing costs by minimizing component count and maintaining reliable operation during power fluctuations.
Implementation Method 1
a back-up capacitor (403) coupled to the output of the driver circuit and arranged to receive electrical energy from the output of the driver circuit
Implementation Method 2
a start-up resistor which is coupled to the input of the driver circuit and which is configured to charge the supply voltage capacitor when coupled to the supply voltage capacitor
Data Source
AI summary
This invention relates to driver circuits used within high voltage power supplies, e.g. for light bulb assemblies. A driver circuit providing electrical energy at an output derived from electrical energy at an input is described. The driver circuit comprises a power converter, a controller, a supply voltage capacitor, and is configured to provide a supply voltage to the controller. A start-up resistor is coupled to the input of the driver circuit, charges the supply voltage capacitor, and is coupled to the supply voltage capacitor during start-up of the driver circuit. A back-up capacitor is coupled to the output of the driver circuit and with the supply voltage capacitor if a voltage at the back-up capacitor exceeds the supply voltage by a forward voltage threshold, and is decoupled from the supply voltage capacitor if the supply voltage exceeds the voltage at the back-up capacitor by a reverse voltage threshold.