Fuel Cell Cold Start via Motor Torque Restriction
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Solution Overview
Problem
Fuel cell systems face challenges in cold start performance, particularly in low-temperature environments, where the fuel cell stack temperature drops below zero degrees, leading to potential freezing and prolonged cold start times, despite existing methods like phase resistance heating and anti-freezing liquids.
Innovation Solution
A device and method that control the cold start by applying an output current from the fuel cell to a motor, restricting motor torque using a torque restriction part, such as a P stage latch or hydraulic brake, to increase current consumption and facilitate self-heating of the fuel cell stack, allowing the rotor to rotate forward and reverse within a predetermined angle range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the fuel cell stack outputs substantial current to generate heat for rapid thawing, then the cold start time is reduced, but the motor cannot generate useful torque and the vehicle cannot be driven
Solution Approach 1:
The system dynamically switches the motor's operational mode based on temperature conditions. During cold start, the motor operates in braking mode to consume power and generate heat. Once the fuel cell stack temperature exceeds the freezing point, the motor transitions to normal driving mode, enabling vehicle operation. This dynamic state change resolves the contradiction between heating and drivability.
Solution Approach 2:
The control system implements periodic switching between braking mode and normal driving mode during cold start. The motor alternates between consuming power for heating and potentially providing torque, creating a periodic action pattern that gradually warms the stack while maintaining some drivability capability.
2Temperature
If the motor is used as a heating element by applying current to generate heat, then the stack temperature increases rapidly, but the motor torque generation prevents efficient power consumption
Solution Approach 1:
The invention converts the harmful effect of motor torque generation (which wastes power) into a beneficial braking action. By applying reverse current to the motor during cold start, the motor generates braking torque that consumes electrical power from the fuel cell stack, converting this power into heat that warms the stack. The torque that would normally be wasted is instead used as a controlled braking force to maximize power consumption for heating purposes.
3Productivity
If the rotor rotates forward and reverse to consume kinetic energy and increase current consumption, then the cold start performance is improved, but the motor generates torque that could cause unintended vehicle movement
Solution Approach 1:
The control system applies preliminary anti-action by engaging the parking pawl in the transmission system before the motor begins rotating the rotor forward and reverse. This mechanical locking prevents the motor torque from being transmitted to the driving wheels, eliminating the risk of unintended vehicle movement while allowing the motor to freely rotate and consume power for heating the fuel cell stack.
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 reduces cold start time by consuming kinetic energy, prevents motor-driven actual driving until the start is complete, evenly uses inverter IGBTs to prevent durability degradation, and aids in delamination between fuel cell parts, thereby enhancing cold start efficiency and durability.
Implementation Method 1
a motor (10) to which an output current of the fuel cell is applied
Implementation Method 2
a torque restriction part (20) configured to restrict a torque generated when a rotor of the motor rotates forward and reversely
Implementation Method 3
a fuel cell configured to apply a current to a motor during a cold start condition of the fuel cell system
Data Source
AI summary
A device and a method for controlling a cold start of a fuel cell system are provided and are capable of increasing a fuel cell load to reduce a cold start time using a kinetic energy storage method for a rotor of a motor for driving a fuel cell system. The method improves cold start performance by performing self-heating of a fuel cell stack based on an increase in an output current amount of a fuel cell and by restricting a motor torque simultaneously with generating the motor torque while applying a current to a motor when a vehicle stops to consume an output current of the fuel cell.