Multiphase DC to DC Converter Inductor Ripple Reduction
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Solution Overview
Problem
Existing multiphase DC to DC converters face high ripple current in output capacitors due to mismatched resonant components and difficulty in achieving soft switching across varying operating frequencies, leading to lower efficiency and increased electromagnetic interference (EMI).
Innovation Solution
Incorporating an inductor operatively coupled between converters and an output capacitor, with a drive circuit configured for a predetermined phase shift, to reduce ripple current and facilitate balanced current sharing and lossless switching transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resonant components are well matched in existing multiphase DC to DC converters, then current sharing between converters is improved, but the ripple current in the output capacitor remains high due to sinusoidal output currents
Solution Approach 1:
An inductor is introduced as an intermediary component between the resonant converters and the output capacitor. This inductor acts as a current smoothing element that filters the sinusoidal currents from multiple converters, significantly reducing the ripple current in the output capacitor while maintaining balanced current sharing between converters.
2Adaptability or versatility
If the operating frequency of resonant converters is varied to achieve regulation, then adaptability is improved, but soft switching becomes difficult to achieve under all operating conditions, resulting in lower efficiency and higher EMI
Solution Approach 1:
The system employs dynamic frequency adjustment of the resonant converters while maintaining soft switching through the use of an inductor-based output filter. The inductor provides continuous current delivery to the output, ensuring zero-current switching conditions are maintained even as the operating frequency varies for regulation, thereby preserving both adaptability and soft switching reliability.
3Power
If multiple independent resonant converters are operated in multiphase configuration with phase shift, then power delivery capability is improved, but the ripple current in the output capacitor becomes quite high
Solution Approach 1:
Multiple resonant converters are merged into a single multiphase system with their outputs connected through a common inductor. The inductor combines the sinusoidal currents from different phases and filters out the ripple components, allowing the system to deliver high power while minimizing output capacitor ripple current.
Data Source
AI summary
A multiphase DC to DC converter includes an input, an output, at least first and second converters, an inductor, an output capacitor, and a drive circuit. The drive circuit is configured for switching the first and second converters with a predetermined phase shift therebetween. The output capacitor is operatively coupled between the first and second converters and the output. The inductor can be placed either at the input side or the output side. When placed at the input side, the inductor is operatively coupled between an input capacitor and the first and second converters. When placed at the output side, the inductor is operatively coupled between the first and second converters and the output capacitor. The multiphase DC to DC converter is capable of achieving lossless switching transitions and negligible ripple current in the output capacitor.