Fuel Cell Air Pump Torque Control via Feedforward
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Solution Overview
Problem
Existing fuel cell systems face challenges in rapidly responding to changes in electric power requirements, leading to inadequate rotation speed control of air compressors, which can result in inefficient air supply and increased burden on secondary batteries.
Innovation Solution
The system adjusts torque command values for the air pump based on changes in accelerator position, rotation speed, and electric power requirements, using an electronic control unit to calculate and set torque command values that prevent overshooting or undershooting, and sets a lower limit to prevent reverse rotation, ensuring efficient air supply and maintaining output power balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the air compressor rotation speed is controlled based on standard feedback control, then the system stability is maintained, but the response speed to rapid changes in electric power requirements is insufficient
Solution Approach 1:
The control device calculates a feedforward torque command value based on the change rate of the rotation speed command value before the rotation speed actually changes. This preliminary action allows the air compressor to respond more quickly to rapid changes in electric power requirements by anticipating the needed torque adjustment, thereby improving response speed while maintaining control stability through the combination of feedforward and feedback control.
2Speed
If the torque command value is increased to improve response speed, then the rotation speed reaches the target faster, but the rotation speed may overshoot the command value
Solution Approach 1:
The control device combines feedforward control (based on change rate of rotation speed command) with feedback control (based on actual rotation speed vs. command value). The feedback mechanism detects when the actual rotation speed approaches or exceeds the command value and adjusts the torque command accordingly, preventing overshoot while maintaining fast response through the feedforward component.
3Reliability
If the air compressor response is delayed, then the control system remains stable, but the secondary battery must compensate for power shortages increasing its burden
Solution Approach 1:
By calculating the feedforward torque command value based on the change rate of the rotation speed command value, the system anticipates power requirements and adjusts the air compressor torque proactively. This preliminary action ensures the air compressor delivers the required power without delay, reducing the need for secondary battery compensation while maintaining control stability through the integrated feedback mechanism.
4Speed
If the torque command value is not adjusted for rapid changes, then the control algorithm remains simple, but the air pump cannot reach the required rotation speed promptly
Solution Approach 1:
The control device calculates a feedforward torque command value based on the change rate of the rotation speed command value, which is a relatively simple calculation that can be implemented efficiently. This preliminary torque estimation, combined with standard feedback control, enables the air compressor to reach the required rotation speed promptly without requiring a significantly more complex control algorithm.
Data Source
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AI summary
In a vehicle including a fuel cell system, an electronic control unit (200) is configured to perform first processing in which a rotation speed of an air pump (360) is controlled based on a torque command value and a rotation speed command value, and to perform, in the first processing, at least one of second processing in which the torque command value is set to be larger than the calculated torque command value when at least one of values of an accelerator position, required electric power, and the rotation speed command value or a change rate thereof is increased by a prescribed first value or more, and third processing in which the torque command value is set to be smaller than the calculated torque command value when at least one of the values or the change rate thereof is decreased by a prescribed second value or more.