Fuel Cell Vehicle Torque Control and Mode Transition
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Solution Overview
Problem
Conventional start-up control methods for fuel cell-supercapacitor hybrid vehicles require DC-DC converters or initial charging devices, leading to sudden torque increases when switching to hybrid mode, which can damage the fuel cell and prolong start-up time, while failing to optimize driving performance.
Innovation Solution
A method involving torque limit control and a torque correction factor to gradually connect the fuel cell to the power storage unit, using an insulated gate bipolar transistor (IGBT) for controlled charging and a main relay to transition from fuel cell only mode to hybrid mode, ensuring voltage matching and preventing sudden torque spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC-DC converter or initial charging device is used to charge the power storage unit during start-up, then the fuel cell can be protected from voltage mismatch, but the start-up time is prolonged and the device complexity increases
Solution Approach 1:
The fuel cell is started up first by the auxiliary battery before being connected to the power storage unit, preparing the system in advance for direct connection without requiring complex charging devices during the transition phase
Solution Approach 2:
The DC-DC converter and initial charging device are removed from the system, simplifying the structure while using the auxiliary battery to provide the necessary preliminary charging function during start-up
2Loss of time
If the fuel cell is directly connected to the power storage unit in hybrid mode, then the start-up time is reduced, but sudden torque increase occurs causing the vehicle to move suddenly
Solution Approach 1:
Torque limit control is applied in advance during the fuel cell only mode before transitioning to hybrid mode, preventing sudden torque spikes when the fuel cell is directly connected to the power storage unit
Solution Approach 2:
The torque correction factor is dynamically adjusted based on the operating mode, being applied during fuel cell only mode and gradually reduced as the system transitions to hybrid mode, allowing smooth torque management throughout the transition
3Object-affected harmful factors
If torque limit control is applied during fuel cell only mode, then sudden torque spikes are prevented, but the vehicle moves slowly requiring longer charging time
Solution Approach 1:
The torque correction factor is dynamically adjusted based on the operating mode, being applied during fuel cell only mode to prevent sudden torque spikes, and then gradually reduced as the system transitions to hybrid mode to restore full vehicle performance
Solution Approach 2:
The torque correction factor parameter is changed based on the operating mode transition, starting at a limiting value during fuel cell only mode and gradually increasing to full value in hybrid mode, optimizing both protection and performance
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 start-up time, protects the fuel cell, and improves driving performance by dynamically controlling torque and voltage, preventing sudden starts and optimizing charging efficiency.
Implementation Method 1
performing charging from the fuel cell to a power storage means while the vehicle moves slowly by the torque limit control under the fuel cell only mode
Implementation Method 2
The charging of the power storage means is performed by a current limit control according to a duty ratio control of an insulated gate bipolar transistor (IGBT) of an initial charging device
Implementation Method 3
directly connecting the fuel cell to the power storage means by a main relay to enter a hybrid mode, when a voltage difference between the fuel cell and the power storage means is within a predetermined range
Implementation Method 4
generating a torque (TACCEL) calculated based on an accelerator pedal depression value upon completion of start-up of a fuel cell and entering a fuel cell only mode; performing a torque limit control for the torque (TACCEL) calculated based on the accelerator pedal depression value
Data Source
AI summary
In one aspect a method for controlling a fuel cell vehicle is provided, comprising generating a torque (TACCEL) calculated based or an accelerator pedal depression value upon completion of start-up of a fuel cell and entering a fuel cell only mode; performing a torque limit control for the torque (TACCEL) calculated based on the accelerator pedal depression value; performing charging from the fuel cell to a power storage means while the vehicle moves slowly by the torque limit control under the fuel cell only mode; and directly connecting the fuel cell to the power storage means by a main relay to enter a hybrid mode, when a voltage difference between the fuel cell and the power storage means is within a predetermined range. Preferred methods can protect the fuel cell, reduce the time for vehicle start-up and improve driving performance.