Control method and device of gas compressor under low current of fuel cell

Abstract

The invention provides a control method of a gas compressor under low current of a fuel cell. The control method comprises the following steps: acquiring a characteristic curve of a fuel cell stack and the gas compressor; calculating the critical rotating speed nc of the gas compressor and the lower limit rotating speed n0 corresponding to the required current Ir according to the characteristic curve; and adjusting the rotating speed of the gas compressor from the critical rotating speed nc to the lower limit rotating speed n0, adjusting the opening degree of a bypass valve and the opening degree of a back pressure valve at each rotating speed in the adjusting process, and making the gas compressor to work in an operation area. The invention further correspondingly provides a control device. According to the invention, when the fuel cell runs in a low-current state, the rotating speed of the gas compressor is reduced as much as possible to reduce the power consumption of the gas compressor on the premise of avoiding surge of the gas compressor by adjusting the rotating speed of the gas compressor and adjusting the opening degrees of the bypass valve and the back pressure valve, sothat the system efficiency of the fuel cell in a low-current stage is improved.

Description

technical field [0001] The present application relates to the technical field of fuel cells, in particular to a control method and device for a compressor of a fuel cell under low current. Background technique [0002] The proton exchange membrane fuel cell system is a device that can directly convert the chemical energy of reactants into electrical energy through electrochemical means. It has the advantages of high efficiency and zero emission, and is considered to be one of the important directions for the sustainable development of the future automobile industry. [0003] The efficiency of the fuel cell system is mainly determined by the efficiency of the fuel cell stack and the power of the auxiliary system mainly based on the power of the compressor. The efficiency of the fuel cell stack is also affected by parameters such as the flow rate, pressure and humidity of the air provided by the compressor. The efficiency of the compressor is affected to a certain extent by th...

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Problems solved by technology

[0005] When the fuel cell system works in the low current stage, the required air flow rate is low, but due to the large flow resistance of the fuel cell stack, a higher intake pressure is required, resulting in the current mainstream centrifugal compressor running in the surge region, reducing the compressor. service life

Although compressor surge can be avoided by increasing the speed of the compressor and increasing the intake pressure and flow rate, there are technical problems: this will also lead to increased power consumption of the compressor and insufficient wetting of the inner membrane of the stack, which will eventually reduce the efficiency of the fuel cell system. reduce

[0011] In this method, when it is judged to be in the preset surge area, the speed of the air compressor and the opening of the air outlet throttle should be adjusted so that the air compressor exits the preset surge area and the fuel consumption must be ensured. The intake pressure and flow of the battery need to increase the speed of the compressor. As mentioned above, the power consumption of the compressor will increase during the low current stage of the fuel cell, which will reduce the efficiency of the fuel cell system

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