A fuel cell system switch control method and device

Abstract

The invention discloses a turning on-off control method of a fuel cell system. The control method comprises a turning on preheating control method. The turning on preheating control method comprises the following steps: 1) in a process of starting a fuel cell, while an indicating temperature is lower than a setting temperature value, closing a contactor by a controller, enabling an electric current generated by a fuel cell stack to flow through a resistance to generate heat, heating cooling water in an internal circulating water route, and warming the fuel cell stack through internal circulation; 2) collecting a real-time current signal of the resistance; 3) according to an expected loading current signal and the real-time current signal, calculating a duty ratio controlled quantity by using PID closed-cycle control through the controller; 4) according to the duty ratio controlled quantity, outputting a PWM signal through the controller, controlling an opening-closing state of an electronic switch, and adjusting a current size of the resistance; and 5) while the indicating temperature is equal to or higher than the setting temperature value, breaking the contactor through the controller. The control method is capable of consuming a surplus reaction gas in the stack during shutdown, and avoiding lifetime decay of the fuel cell caused by overpotential.

Description

technical field [0001] The present invention relates to the technical field of fuel cell system control, in particular to a fuel cell system start-up control method and device. Background technique [0002] The normal operating temperature of the fuel cell is about 75°C. When starting in a low temperature environment, the fuel cell stack needs to be preheated. The existing technical solutions increase the internal resistance of the stack by short-circuiting the fuel cell stack or increasing the output current of the stack, thereby improving The waste heat generation rate of the electric stack makes the electric stack self-heating, but the former prevents the vehicle from being started at low temperature, and the latter has the disadvantage of uneven temperature distribution between the two ends of the electric stack and the single cells in the middle. Other technical solutions heat the coolant in the water tank through an additional heat exchange backup, but this method lead...

AI Technical Summary

Problems solved by technology

[0002] The normal operating temperature of the fuel cell is about 75°C. When starting in a low temperature environment, the fuel cell stack needs to be preheated. The existing technical solutions increase the internal resistance of the stack by short-circuiting the fuel cell stack or increasing the output current of the stack, thereby improving The waste heat generation rate of the electric stack makes the electric stack self-heating, but the former prevents the vehicle from being started at low temperature, and the latter has the disadvantage of uneven temperature distribution of the single cells at both ends of the electric stack and in the middle

Other technical solutions heat the coolant in the water tank through an additional heat exchange backup, but this method leads to an increase in the volume of the fuel cell system and a complicated structure

In addition, when the fuel cell is shut down, there will be some unreacted fuel remaining in the fuel cell stack, which will cause overpotential and damage the performance and durability of the fuel cell

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