Fuel Cell Air Compressor Control for Stack Voltage Stability
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Solution Overview
Problem
Fuel cell vehicles experience a 'stumbling' phenomenon due to voltage drops in the fuel cell stack when drivers request high power, leading to limited acceleration and additional voltage drops from excessive current output, especially in low voltage operation modes.
Innovation Solution
A method and system for controlling the air compressor motor in fuel cell systems that limit the rotation speed and phase current based on sensing voltage, deriving target speed and phase current command values, and adjusting these to prevent voltage drops by implementing speed and current limits, thereby securing minimum voltage for the fuel cell stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air compressor motor rotation speed is increased to meet high power demand, then the air supply to cathode is improved, but the voltage drop of fuel cell stack occurs due to excessive current output
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the rotation speed command value of the air compressor motor based on the operating mode and voltage conditions. The control unit modifies the speed parameter according to the fuel cell stack's voltage state, preventing excessive current output that causes voltage drops while ensuring adequate air supply for power generation.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the voltage of the fuel cell stack and adjusting the air compressor motor speed accordingly. The control unit receives voltage information and feeds it back to modify the speed command, creating a closed-loop control system that maintains voltage stability while meeting air supply requirements.
2Power
If the air compressor motor current is increased to increase output, then the motor power is improved, but additional voltage drops occur in the fuel cell stack
Solution Approach 1:
The patent changes the current parameter by limiting the phase current command value based on the operating mode and voltage conditions. The control unit adjusts the current parameter to prevent excessive power consumption that would cause additional voltage drops, while still providing sufficient power for the air compressor to function effectively.
Solution Approach 2:
The patent applies partial action by providing just enough current to the air compressor motor to meet the air supply requirements without excessive current output. The control unit calculates and applies a limited current command value that is sufficient for operation but does not cause additional voltage drops in the fuel cell stack.
3Productivity
If the phase current command value is increased to improve motor performance, then the motor output is improved, but the voltage drop protection is compromised
Solution Approach 1:
The patent dynamically changes the phase current command value parameter based on the operating mode and voltage conditions. The control unit adjusts this parameter to optimize motor performance while preventing voltage drops, switching between different current limits depending on the fuel cell stack's voltage state and operational requirements.
Solution Approach 2:
The patent implements dynamic control by making the phase current command value adjustable and responsive to changing conditions. The control unit continuously adapts the current parameter based on real-time voltage measurements and operating mode, creating a dynamic balance between motor performance and voltage drop prevention.
Data Source
AI summary
A method and system for controlling an air compressor of a fuel cell system is capable of increasing the output of the air compressor motor while preventing a voltage drop of the fuel cell stack by limiting the rotation speed of the air compressor motor according to a demand output and at the same time limiting the phase current and power consumption of the motor when the demand output of a vehicle equipped with the fuel cell system is changed.