Fuel Cell Torque Control for Smooth Acceleration
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Solution Overview
Problem
Fuel cell systems experience sudden motor output limitations and abrupt acceleration when the temperature is low, leading to a discontinuous feeling of acceleration, especially during high-demand situations like Wide Open Throttle (WOT) and downhill driving.
Innovation Solution
Implementing a motor control system that limits the torque of the drive motor to be lower than its maximum output when the fuel cell temperature is below a prescribed level or when driving downhill, ensuring continuous torque limitation to maintain acceleration feel and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor output is limited when fuel cell temperature is low, then system voltage decrease is prevented, but acceleration feeling becomes discontinuous and unsatisfying
Solution Approach 1:
The motor control section dynamically adjusts the torque limitation based on real-time fuel cell temperature measurements. When temperature is below the prescribed threshold, torque limitation is applied; when temperature rises above the threshold, limitation is released. This dynamic adaptation resolves the contradiction by making the system response flexible rather than fixed, maintaining voltage stability only when necessary while preserving acceleration feeling when the fuel cell can support it.
Solution Approach 2:
The system changes the operational parameters (torque limitation status) based on the fuel cell temperature parameter. By monitoring temperature as a key parameter and adjusting torque limits accordingly, the system transitions between different operational states to balance voltage stability requirements with acceleration performance expectations.
2Stability of the object's composition
If high torque is demanded during downhill driving, then vehicle control becomes difficult, but motor output limitation prevents proper acceleration control
Solution Approach 1:
The motor control section implements dynamic torque limitation specifically for downhill driving conditions by detecting negative acceleration requests. The system continuously monitors acceleration pedal operation and vehicle motion state, applying torque limits only when downhill driving is detected, thereby maintaining speed control stability during coasting while preserving full acceleration capability when needed.
Solution Approach 2:
The system uses feedback from acceleration pedal position sensors and vehicle motion sensors to detect downhill driving conditions. Based on this feedback, the motor control section automatically adjusts torque output to prevent excessive acceleration during downhill coasting, while maintaining normal acceleration response when the driver requests positive acceleration.
3Reliability
If torque limitation is applied suddenly, then voltage stability is maintained, but noise and vibration increase due to abrupt torque changes
Solution Approach 1:
The motor control section applies torque limitation in advance when fuel cell temperature drops below the prescribed threshold or when downhill driving conditions are detected. By proactively limiting torque before voltage instability or excessive acceleration occurs, the system prevents the need for sudden corrective actions that would generate noise and vibration.
Solution Approach 2:
The torque limitation is implemented continuously as long as the temperature threshold is below the prescribed level or downhill conditions persist. This continuous control approach avoids abrupt on/off switching of torque limits, thereby maintaining smooth motor operation and reducing noise and vibration while still ensuring voltage stability.
Data Source
AI summary
A first power source system includes a first motor control section that controls at least torque of a drive motor. When a temperature of an FC is less than or equal to a prescribed temperature Th and a demand for high output is made to the drive motor, the first motor control section limits the torque of the drive motor to be lower than a maximum torque that can be output by the drive motor, and continuously implements this torque limitation.