Fuel Cell Voltage Control with Addition Term
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Solution Overview
Problem
Fuel cell systems face challenges in quickly and stably supplying necessary electric power due to delays and overshoots in voltage control, particularly when target electric power changes rapidly, affecting the controllability of converters used to increase input voltage.
Innovation Solution
A voltage control system that includes a converter device with a reactor, a converter controlling portion, a current value acquisition portion, and a voltage value acquisition portion, which sets the duty ratio using a feedforward term and an addition term. The addition term is derived from current deviations and previous cycle data to enhance output current and reduce response delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control is used to control the duty ratio, then the output voltage can be stabilized, but response delay and overshoot occur when target electric power changes rapidly
Solution Approach 1:
The invention calculates a preliminary duty ratio based on the relationship between input voltage, output voltage, and target power before feedback control is applied. This preliminary value serves as a predictive starting point that anticipates the required duty ratio adjustment, allowing the system to respond more quickly to power changes while maintaining stability through subsequent feedback refinement.
Solution Approach 2:
The invention changes the control parameter from direct feedback control of duty ratio to a two-stage approach: first calculating duty ratio based on voltage and power parameters, then applying feedback adjustment. This parameter transformation enables the system to balance rapid response with stability by separating the predictive calculation from the corrective feedback.
2Speed
If the duty ratio is adjusted rapidly to follow target power changes, then response speed improves, but overshoot and instability increase
Solution Approach 1:
The invention applies feedback control to the duty ratio calculation, where the actual output voltage is continuously monitored and compared with the target voltage. The feedback term adjusts the preliminary duty ratio to compensate for deviations, ensuring that rapid response to power changes does not cause overshoot or instability. The feedback gain is optimized to balance response speed with system stability.
3Device complexity
If conventional feedback control is used, then system simplicity is maintained, but controllability deteriorates under rapid power changes
Solution Approach 1:
The invention introduces a preliminary duty ratio calculation step that uses the measured input voltage, output voltage, and target power to predict the required duty ratio before feedback control is applied. This preliminary calculation enhances controllability under rapid power changes by providing an informed starting point, while adding minimal complexity to the overall control system structure.
Data Source
AI summary
A voltage control system includes: a converter controlling portion; a current value acquisition portion; and a voltage value acquisition portion. The converter controlling portion sets a duty ratio in a present cycle by adding an addition term to a feedforward term, the addition term being determined by use of a current deviation, which is a difference between a target value of an output current in the present cycle and a current measured value in a previous cycle, and the duty ratio in the previous cycle, the addition term being corresponding to an increase of the output current in the present cycle.