LLC Resonant Converter Switching Frequency Control
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Solution Overview
Problem
Existing DC-to-DC converters for LED arrays face challenges in varying switching frequency, which limits the control over output power, as self-oscillating LC circuits make it difficult to adjust the switching frequency without altering the input DC voltage.
Innovation Solution
An LLC resonant converter with a control means that adjusts the switching frequency by modifying the capacitance of LC circuits, using multiple capacitors and switches to generate control signals for transistors, allowing for flexible frequency variation with minimal effort and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a self-oscillating LC circuit is used to generate control signals, then the converter can operate at high switching frequency, but the switching frequency cannot be easily varied
Solution Approach 1:
The patent applies dynamics by making the capacitance value in the LC circuit adjustable rather than fixed. The control means dynamically changes the capacitance value based on desired output power levels, which in turn dynamically adjusts the switching frequency. This resolves the contradiction by enabling frequency variation while maintaining the self-oscillating operation mode.
Solution Approach 2:
The patent changes the parameter of capacitance in the LC circuit to control the switching frequency. By varying the capacitance value through the control means, the resonant frequency of the LC circuit changes, thereby adjusting the switching frequency without changing the fundamental self-oscillating operation mode. This directly addresses the frequency adjustability issue.
2Power
If output power is controlled by varying DC input voltage, then power control is achieved, but it requires complex voltage regulation circuitry
Solution Approach 1:
Instead of changing the DC input voltage to control output power, the patent changes the switching frequency parameter of the converter. By adjusting the capacitance in the LC circuit, the switching frequency varies, which directly affects the power transfer characteristics of the resonant converter. This simplifies the control mechanism by avoiding complex voltage regulation circuitry.
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
Enables easy modification of switching frequency, thereby allowing for precise control of output power, enhancing the efficiency and flexibility of power delivery to LED arrays and other low-level DC power appliances.
Implementation Method 1
an LC circuit is used to generate a control signal for switching a transistor connected to the inductor with a high frequency
Implementation Method 2
energy from the chopped DC power is alternately stored into a magnetic field and discharged therefrom
Data Source
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AI summary
The present invention relates to an operating device for an illuminant comprising a voltage converter having at least one transistor (T1, T2) controlled by a control signal, a LC circuit (3) for generating the control signal having at least a first capacitor (C2; C4) and a second capacitor (C3; C5), at least one switch (S1; S2) for connecting the first capacitor (C2; C4) or the second capacitor (C3; C5) to the LC circuit (3), and a control means (4) for controlling the at least one switch (S1; S2) to change the switching frequency of the transistor (T1, T2).