Fuel Cell System Voltage Control via Sequential Converter Stabilization
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Solution Overview
Problem
Rapid variances in input voltage and output terminal voltage in hybrid fuel cell systems can exceed control limits, leading to potential control breakdowns during rapid changes in load demand.
Innovation Solution
A fuel cell system with a fuel cell and an accumulator connected in parallel, an inverter, and voltage conversion units to control terminal and input voltages, where the control system manages the operations of these units to ensure the input voltage reaches a set demand voltage before adjusting the fuel cell's terminal voltage, preventing excessive control frequency operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the demand power for the load is rapidly increased, then the input voltage of the inverter is rapidly raised toward the set target input voltage, but the output terminal voltage of the fuel cell is rapidly lowered toward the set target output terminal voltage, requiring the FC converter to operate in excess of control limits and causing control breakdown
Solution Approach 1:
The control method performs preliminary action by first adjusting the battery converter to reach the target input voltage before adjusting the FC converter for the target output terminal voltage. This sequential approach prevents simultaneous rapid adjustments that would exceed control limits and cause breakdown, while still achieving the required response speed through coordinated preliminary actions.
2Productivity
If the target input voltage of the inverter shifts to a high voltage side and the target output terminal voltage of the fuel cell shifts to a low voltage side simultaneously, then the voltage conversion units must operate rapidly, but this causes operation in excess of control limits
Solution Approach 1:
The control method segments the voltage adjustment process into two distinct phases: first adjusting the battery converter to achieve the target input voltage, then adjusting the FC converter to achieve the target output terminal voltage. This segmentation divides the complex simultaneous control into manageable sequential steps, maintaining ease of operation while achieving rapid power delivery.
Data Source
AI summary
Even in a case where a rapid variance is demanded as to the input voltage of a converter and the output terminal voltage of a fuel cell, stable converter control is realized. On judging that the change ratio of the demand power of a fuel cell exceeds a set threshold value, a controller executes converter stabilization processing. First, the controller controls a battery converter so that an input voltage of an inverter becomes a set target input voltage. Then, after the input voltage of the inverter reaches the target input voltage, the controller controls an FC converter so that an output terminal voltage of the fuel cell becomes a set target output terminal voltage.