LLC Transformer Control for Multi-Voltage Display Power Circuits
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Solution Overview
Problem
Conventional display devices face challenges in minimizing the size of transformer circuits due to the inclusion of electrolytic capacitors and the complexity of high-frequency transformers, which makes it difficult to accommodate various commercial voltages.
Innovation Solution
A display device with a transformer circuit that includes switching devices controlled by a controller to operate as a half bridge LLC converter, allowing the device to transform commercial power and adjust modulation frequency, width, and phase to follow a predetermined reference voltage, enabling operation with various commercial voltages and minimizing the transformer's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-frequency transformer with 60 Hz is used in the transformer circuit, then the transformer can serve as an insulating circuit, but the size of the transformer cannot be reduced due to the inclusion of an electrolytic capacitor
Solution Approach 1:
The patent removes the electrolytic capacitor from the transformer circuit by extracting its filtering function and replacing it with a resonant circuit comprising an inductor and capacitor. This extraction eliminates the bulky electrolytic capacitor while maintaining the necessary voltage smoothing function through resonance at a specific frequency.
Solution Approach 2:
The patent changes the operating parameters of the transformer from low-frequency (60 Hz) to high-frequency operation. By operating at higher frequencies, the transformer can achieve the same power transformation with significantly reduced size, and the resonant circuit replaces the electrolytic capacitor's function without requiring large capacitance values.
2Power
If a high-frequency transformer is used in the power-factor improvement circuit, then the transformer can transform commercial power, but the structure becomes complex and minimization of the structure becomes difficult
Solution Approach 1:
The patent merges the power-factor improvement function with the voltage transformation function into a single integrated circuit. The resonant circuit serves dual purposes: improving power factor by correcting the phase difference between voltage and current, and transforming voltage through the high-frequency transformer, thereby eliminating the need for separate circuits.
Solution Approach 2:
The high-frequency transformer circuit is designed to perform multiple functions simultaneously: voltage transformation, power-factor correction, and voltage regulation. By making the circuit universal and multi-functional, the patent reduces overall system complexity despite using high-frequency operation.
3Adaptability or versatility
If the transformer circuit is designed to accommodate various commercial voltages, then the device can operate with different voltage ranges, but the transformer size cannot be minimized
Solution Approach 1:
The patent employs a resonant circuit with adjustable parameters that can dynamically adapt to different input voltages. The controller adjusts the switching frequency and duty cycle of the switching elements to maintain resonance and proper voltage transformation ratio across various commercial voltage standards, allowing the transformer size to remain small while maintaining versatility.
4Manufacturing precision
If modulation control is implemented to follow a predetermined reference voltage, then the output voltage can be regulated, but the control complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the output voltage and adjusts the switching elements' operation to maintain the output voltage at the predetermined reference level. This feedback loop enables precise voltage regulation while using simple switching elements and control logic.
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 allows for a compact transformer circuit that can operate with various commercial voltages, reducing the device's size and improving power factor correction, making it more efficient and adaptable to different voltage ranges.
Implementation Method 1
a transformer configured to transform a commercial power and supply the transformed commercial power to the display
Implementation Method 2
controlling the plurality of switching devices on the basis of the output voltage of the transformer to perform a modulation control of the output voltage to follow a predetermined reference voltage
Data Source
AI summary
The present disclosure provides a display device, which enables minimization of a transformer circuit and which can be driven using various commercial voltages, and a method for controlling the display device.The display device according to an embodiment comprises: a display; a transformer which transforms commercial power and supplies the transformed commercial power to the display and which includes a plurality of switching devices; and a controller for determining, on the basis of the magnitude of an input voltage input to the transformer, whether or not to open at least one of the plurality of switching devices, and controlling the plurality of switching devices on the basis of an output voltage of the transformer to perform a modulation control of the output voltage to follow a predetermined reference voltage.