Parallel Fuel Cell Air Compressor Sequencing for Fast Restart
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Solution Overview
Problem
The existing fuel cell system start/stop control methods cause output delay and deterioration due to the difficulty in immediately reactuating the air compressor motor after sensorless motor position alignment, leading to delayed air supply and current output in parallel fuel cell systems.
Innovation Solution
A method that calculates a delay time based on the operating state information of each fuel cell system, including air compressor speed and rotor initial position alignment time, to sequentially perform stop controls, minimizing overlap and ensuring timely reactuation of air compressors, thereby preventing output delay and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensorless motor position control is used to perform rotor initial position alignment, then reliability of motor reactuation is improved, but output delay occurs due to the time required to apply d-axis current
Solution Approach 1:
The patent applies d-axis current to perform rotor initial position alignment before the air compressor motor is stopped. By performing this alignment action in advance while the motor is still rotating, the rotor position is pre-aligned to the correct initial position, eliminating the need to wait for alignment after stopping. This preliminary action resolves the contradiction by maintaining reliability through proper alignment while avoiding the time delay that would otherwise occur.
2Reliability
If air compressor is stopped for fuel cell system start/stop control, then fuel cell stack deterioration is prevented, but air supply delay occurs leading to fuel cell stack deterioration
Solution Approach 1:
The patent performs rotor initial position alignment before stopping the air compressor motor. By pre-aligning the rotor position while the motor is still running, the motor can be immediately reactuated after stopping without waiting for alignment procedures. This ensures continuous air supply to the fuel cell stack, preventing deterioration while still enabling necessary stop/control operations.
Solution Approach 2:
The patent ensures continuous air supply to the fuel cell stack by eliminating gaps caused by alignment delays. The rotor alignment is completed before motor shutdown, so when the motor restarts, air supply resumes immediately without interruption. This continuity prevents fuel cell stack deterioration while maintaining the stop/control functionality.
3Measurement precision
If d-axis current is applied for rotor initial position alignment, then motor position accuracy is improved, but torque generation is delayed
Solution Approach 1:
The patent applies d-axis current to align the rotor position while the motor is still rotating, before the actual stopping occurs. This preliminary alignment ensures accurate rotor position is established in advance, so when the motor needs to restart after a stop, torque generation can begin immediately without waiting for alignment. This resolves the contradiction by achieving position accuracy beforehand rather than sacrificing time during restart.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes output delay and prevents deterioration of the fuel cell stack by ensuring sequential and efficient stop and start controls in parallel fuel cell systems, improving power generation efficiency.
Implementation Method 1
a fuel cell stack that generates electric energy... generate electric energy by reacting hydrogen (H2) and oxygen (O2)... At the cathode electrode, the oxygen molecules, the hydrogen ions, and the electrons react with each other to generate electricity and heat
Implementation Method 2
an air supply system that supplies oxygen in the air, as an oxidant required for an electrochemical reaction, to the fuel cell stack
Data Source
AI summary
Disclosed herein is a method of controlling start/stop of a parallel fuel cell system, which, when controlling stop of a parallel fuel cell system in which two or more fuel cell systems are connected in parallel, considers operating state information of each fuel cell system, such as a current speed value of an air compressor and an opening degree of an air-exhaust-side air pressure valve of a fuel cell stack. Accordingly, the method can calculate a delay time for performing fuel cell system stop control for the two or more fuel cell systems, and sequentially perform the fuel cell system stop control for the two or more fuel cell systems based on the calculated delay time. Therefore, it is possible to minimize output delay of each fuel cell system and to achieve deterioration prevention and efficiency improvement of the fuel cell stack by fuel cell system start/stop control.