Parallel DC/DC Converter Control Without Conduction Mode Switching
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Solution Overview
Problem
The complexity and technical overhead in developing control algorithms for DC/DC converters in fuel cell systems arise from mode switching during AC injection current generation, necessitating a method to avoid such switching.
Innovation Solution
The method involves dividing the operating intervals of the DC/DC converter based on the stack current, ensuring each DC/DC conversion unit operates in a single conduction mode within each interval, and selecting the appropriate phase current as the AC injection current to avoid mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the DC/DC converter operates under varying load conditions, then the converter can adapt to different power demands, but conduction mode switching occurs which increases control algorithm complexity
Solution Approach 1:
The patent segments the operating range of the DC/DC converter into distinct conduction modes (continuous conduction mode and discontinuous conduction mode) with clearly defined boundary conditions. By identifying specific current thresholds and operational regions, the control algorithm can segment the control strategy according to the current conduction mode, avoiding complex continuous-mode switching logic and simplifying overall control complexity while maintaining adaptability to varying load conditions
Solution Approach 2:
The patent utilizes parameter changes by monitoring key operational parameters (such as inductor current, duty cycle, and voltage ratios) to detect transitions between conduction modes. By establishing predetermined parameter thresholds and boundary conditions, the control system can automatically adjust control parameters when crossing mode boundaries, enabling smooth adaptation to load changes without requiring complex real-time mode-switching algorithms
2Productivity
If conduction mode switching is allowed during AC injection current generation, then the DC/DC converter can maintain efficiency across different operating points, but the control algorithm development cost and technical overhead increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-defining the boundary conditions and transition criteria between conduction modes before actual operation. The control algorithm incorporates predetermined thresholds and decision logic that are established during system design, allowing the converter to automatically maintain optimal efficiency across different operating points without requiring complex real-time calculations or adaptive tuning, thereby reducing control algorithm development cost while preserving operational efficiency
Data Source
AI summary
A method for controlling a DC/DC converter of a battery system is disclosed. The method includes controlling the operating parameters of the DC/DC converter of the battery system based on the acquired stack current of the battery stack of the battery system, so as to regulate the phase current of the DC/DC converter. A first DC/DC conversion unit and a second DC/DC conversion unit are connected in parallel, in such a manner that: at least three operating intervals of the DC/DC converter are divided based on the acquired stack current of the battery stack, such that in each operating interval, the first DC/DC conversion unit and/or the second DC/DC conversion unit operate only in a single conduction mode, respectively. The conduction mode includes a continuous conduction mode and/or a discontinuous conduction mode. The method also includes, based on the conduction mode of the first DC/DC conversion unit and/or the second DC/DC conversion unit, selecting the first phase current of the first DC/DC conversion unit or the second phase current of the second DC/DC conversion unit as the AC injection current of the battery system.