DC-DC Converter Secondary Circuit Noise Reduction via Buck Rectifier
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Solution Overview
Problem
Conventional DC-DC high-frequency switch power supplies face issues with noise generation and low dynamic response due to transformer participation in voltage adjustments and the narrow bandwidth caused by isolation components like optocouplers.
Innovation Solution
A DC-DC power supply apparatus that eliminates the need for isolation components in voltage adjustments by using a buck rectifier circuit to directly control the transformer secondary circuit, reducing noise and enhancing dynamic performance through improved feedback response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transformer participates in voltage adjustment through the isolation optocoupler feedback loop, then the output voltage can be stabilized, but the transformer generates audible noise and the response speed is limited by the optocoupler bandwidth
Solution Approach 1:
The patent extracts the voltage adjustment function from the transformer feedback loop and relocates it to the secondary circuit. By using a secondary switching tube connected in parallel with the rectifier diode and controlled by a separate PWM signal, the adjustment function is separated from the transformer, eliminating the noise caused by transformer working state changes while maintaining voltage stabilization capability.
2Reliability
If the isolation optocoupler is used for feedback, then galvanic isolation is achieved, but the bandwidth is narrow and the dynamic response speed is reduced
Solution Approach 1:
The patent segments the feedback control into two independent parts: the primary side maintains galvanic isolation through the optocoupler for stable DC voltage regulation, while the secondary side implements rapid dynamic response through a separate adjustment switch controlled by PWM signals. This segmentation allows each part to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent applies preliminary action by pre-generating PWM adjustment signals based on voltage sampling feedback before actual voltage deviations occur. The secondary switching tube is ready to activate immediately when voltage changes are detected, reducing the overall response time despite the optocoupler bandwidth limitations.
3Adaptability or versatility
If the transformer working state changes frequently for voltage adjustment, then the output voltage adapts to load changes, but the transformer generates audible howling noises
Solution Approach 1:
The patent extracts the frequency-adjustment function from the transformer and relocates it to the secondary circuit switching tube. By controlling the secondary switch with PWM signals independent of the transformer frequency, the system can adapt output voltage to load changes without causing the transformer to operate in its audible noise generation range.
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 increases the bandwidth and response speed of the power supply, allowing for rapid voltage stabilization and improved dynamic performance by eliminating noise and delay associated with transformer and optocoupler participation.
Implementation Method 1
a transformer; a transformer primary circuit; a transformer secondary circuit, which includes a rectifier circuit capable of transformation and configured to transform a square-wave voltage output by the transformer into a DC output voltage
Implementation Method 2
a rectifier circuit capable of transformation and configured to transform a square-wave voltage output by the transformer into a DC output voltage
Data Source
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AI summary
A Direct Current to Direct Current (DC-DC) power supply apparatus includes: a transformer; a transformer primary circuit; a transformer secondary circuit, which includes a rectifier circuit capable of transformation and configured to convert a square wave voltage output by the transformer into a DC output voltage; and a control unit, which controls the transformer secondary circuit to stabilize the DC output voltage into a required value according to the DC output voltage. A method for improving a DC-DC power supply apparatus includes: coupling a rectifier circuit to a secondary winding of a transformer to convert the square-wave voltage output by the transformer into a DC output voltage; and monitoring the DC output voltage, and stabilizing the DC output voltage into a required value according to the DC output voltage.