Transformer-Voltage Control of Synchronous Rectifiers in DC-DC Converters
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Solution Overview
Problem
DC-DC converters experience variations in primary-side current due to manufacturing inconsistencies in coils and transformers, leading to inaccuracies in predicting secondary-side current and resulting in significant power loss from rectifying switching elements.
Innovation Solution
A power converter that includes a transformer, rectifying elements, and a controller, which uses transformer voltages to determine the off-timing of rectifying elements, thereby suppressing variations in power loss by turning off rectifying elements without relying on primary-side current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If secondary-side current is predicted from primary-side current, then control of rectifying switching element can be achieved, but manufacturing variations in coils and transformers cause inaccuracies in current prediction
Solution Approach 1:
The patent introduces an intermediary approach by using primary-side current detection combined with transformation ratio information to indirectly determine secondary-side current characteristics. Instead of directly measuring secondary current, the system uses the relationship between primary and secondary sides through the transformer ratio as an intermediary parameter to achieve accurate control.
Solution Approach 2:
The system implements feedback by continuously monitoring primary-side current and using this information along with transformation ratio data to dynamically adjust the control of rectifying switching elements. This feedback mechanism compensates for manufacturing variations by adapting the control strategy based on actual measured values.
2Productivity
If off-timing is controlled based on predicted secondary-side current, then rectification efficiency can be optimized, but manufacturing inconsistencies cause significant power loss from rectifying switching elements
Solution Approach 1:
The patent applies parameter changes by utilizing transformation ratio as a key parameter to adjust the control strategy. By changing how off-timing is determined—from direct current prediction to using transformation ratio combined with primary current measurement—the system reduces power loss while maintaining rectification efficiency.
Solution Approach 2:
The system performs preliminary action by pre-establishing the relationship between primary-side current and secondary-side current characteristics using transformation ratio information. This allows the control system to proactively optimize off-timing before power loss occurs, rather than reacting to inefficiencies after they arise.
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 effectively suppresses power loss by shortening the power-loss period of rectifying elements, reducing variations in off-timing, and maintaining efficient operation despite manufacturing variations in transformer characteristics.
Implementation Method 1
a converter that converts a DC voltage into an AC voltage
Implementation Method 2
a transformer that steps up or down the AC voltage
Data Source
AI summary
A power converter includes a converter, a transformer, a rectifying element, a detector, and a controller. The converter converts a DC voltage into an AC voltage, the DC voltage supplied from a DC power supply. The transformer steps up or down the AC voltage. The rectifying element is a transistor, and rectifies the AC voltage that is stepped up or down by the transformer. The detector detects a transformer voltage between the transformer and the rectifying element. The controller turns off the rectifying element that is in an on-state, based on the transformer voltage.