Alternating Converter Control for Display Power Supply Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power supply devices for display apparatuses with backlights use multiple control ICs, leading to increased ripple current, which is mitigated by large capacitors in rectification circuits, but this approach is inefficient and requires larger components.
Innovation Solution
A power supply unit that alternately controls first and second converters using different control methods, such as constant voltage and constant current control, and includes a processor to manage these converters, stopping the second driving power when external AC power is not detected, and reducing electromagnetic interference (EMI) with an EMI filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple control ICs are used to control multiple converters, then each converter can be controlled independently, but ripple current increases and larger capacitors are required
Solution Approach 1:
The patent combines multiple control functions into a single control IC that manages multiple converters through alternating control. The controller sequentially controls the first converter and second converter, integrating what would traditionally require separate control ICs. This merging approach reduces the number of control components while maintaining independent control capability for each converter, thereby reducing ripple current without sacrificing operational independence.
Solution Approach 2:
The patent implements periodic alternating control where the controller switches between controlling the first converter and the second converter in a cyclic manner. This periodic action allows each converter to be controlled independently at different time intervals, achieving the effect of independent control while using a single control IC. The alternating control pattern reduces simultaneous ripple current generation that would occur with parallel control of multiple converters.
2Object-generated harmful factors
If large capacitors are used in rectification circuits, then ripple current is reduced, but device size and cost increase
Solution Approach 1:
By implementing periodic alternating control of multiple converters, the patent distributes the power conversion load over time rather than having all converters operate simultaneously. This temporal distribution reduces peak ripple current demands, allowing the use of smaller capacitors in the rectification circuits while still maintaining adequate ripple current suppression. The alternating control pattern ensures that not all converters draw peak current at the same time.
Solution Approach 2:
The patent changes the operational parameters of the converters by controlling them alternately rather than simultaneously. This parameter change in control timing reduces the peak current draw and ripple current magnitude, which directly allows for the reduction of capacitor sizes in the rectification circuits while maintaining the same level of ripple current suppression.
3Power
If multiple converters operate simultaneously, then power supply capacity is increased, but peak input current increases requiring larger EMI filters
Solution Approach 1:
The patent uses periodic alternating control to distribute the power conversion load across different time intervals. Instead of all converters operating simultaneously which causes peak input current surges, the controller sequentially activates different converters. This maintains the total power supply capacity over time while eliminating simultaneous peak current draws, thereby reducing the requirements for EMI filters.
Solution Approach 2:
The patent segments the operation of multiple converters into distinct time intervals, with each converter being controlled during specific periods rather than all at once. This temporal segmentation of converter operation allows the system to maintain high power supply capacity through cumulative output while avoiding the simultaneous peak input current that would require oversized EMI filtering components.
4Device complexity
If a single control IC is used to control multiple converters, then device complexity is reduced, but control precision for each converter may be compromised
Solution Approach 1:
The patent employs periodic alternating control where the single control IC sequentially dedicates its control resources to each converter in turn. This time-division approach allows the controller to provide focused, precise control to each converter during its active period, maintaining control precision comparable to dedicated control ICs. The rapid switching between converters creates the effect of continuous precise control for each while using a single control component.
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 peak input current, allowing for smaller capacitors and EMI filters, and efficiently manages power supply to the backlight by alternating converter control, optimizing power usage and component size.
Implementation Method 1
a rectifier configured to rectify external AC power into DC power
Implementation Method 2
an electromagnetic interference (EMI) filter configured to reduce EMI according to the external AC power
Data Source
AI summary
A display apparatus is disclosed. The display apparatus may include a display configured to display an image using a backlight, an image signal provider configured to provide an image signal to the display and a power supply unit configured to generate first driving power and second driving power using a first converter and a second converter, respectively, and provide the first driving power to the image signal provider and provide the second driving power to the backlight, wherein the power supply unit is configured to control the first converter and the second converter alternately.