Duty Cycle Balance Module for Switch Mode Power Converter Flux Saturation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switch mode power converters face magnetic flux saturation and output voltage regulation failure due to duty cycle imbalances caused by current limiting mechanisms, which are not addressed by traditional voltage-mode control systems.
Innovation Solution
A duty cycle balance module (DCBM) dynamically balances the duty cycles of switch drive signals in switch mode power converters, reducing or eliminating flux imbalances by adjusting the ON times of the signals when current exceeds a predetermined limit, thereby maintaining magnetic flux balance and preventing transformer saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cycle-by-cycle limit module is added to prevent over-current conditions, then current protection is improved, but duty cycle imbalance is caused leading to flux saturation
Solution Approach 1:
The patent implements a feedback mechanism where the duty cycle balance module continuously monitors the actual duty cycles of both half-cycles and compares them against reference values. When imbalance is detected, the module adjusts the duty cycle of one half-cycle to compensate for the other, ensuring magnetic flux balance is maintained while preserving the current protection function.
Solution Approach 2:
The duty cycle balance module acts as an intermediary between the cycle-by-cycle limit module and the switching elements. It receives the limited duty cycle signals from the current protection module and introduces corrective adjustments to balance the magnetic flux, thereby mediating between current protection and flux balance requirements.
2Stability of the object's composition
If voltage-mode control is used to prevent transformer saturation, then flux balance is improved, but peak current limit function is lost
Solution Approach 1:
The patent merges the functions of voltage-mode control (for flux balance) and peak current-mode control (for over-current protection) into a unified control system. The controller integrates both the voltage feedback loop for maintaining magnetic flux balance and the current sensing mechanism for peak current limitation, allowing both functions to operate simultaneously without interference.
3Power
If duty cycle is increased to meet current demand, then power output is improved, but flux saturation risk increases
Solution Approach 1:
The patent employs dynamic duty cycle adjustment where the duty cycle of each half-cycle is continuously adapted based on real-time feedback from the duty cycle balance module. This dynamic control allows the system to meet varying power demands while automatically adjusting to maintain magnetic flux balance, preventing saturation even during high-power operation.
Data Source
AI summary
A duty cycle balance module (DCBM) for use with a switch mode power converter. One possible half-bridge converter embodiment includes a transformer driven to conduct current in first and second directions by first and second signals during and second half-cycles, respectively. A current limiting mechanism adjusts the duty cycles of the first and second signals when a sensed current exceeds a predetermined limit threshold. The DCBM receives signals representative of the duty cycles which would be used if there were no modification by the current limiting mechanism and signals Dact<sub2>—</sub2>1 and Dact<sub2>—</sub2>2 representative of the duty cycles that are actually used for the first and second signals, and outputs signals Dbl<sub2>—</sub2>1 and Dbl<sub2>—</sub2>2 which modify signals Dact<sub2>—</sub2>1 and Dact<sub2>—</sub2>2 as needed to dynamically balance the duty cycles of the first and second signals and thereby reduce flux imbalance in the transformer that might otherwise arise.