Research On Improved Sliding Mode Control Strategy Of DC/DC Converter For Fuel Cell

The fuel cell industry has developed rapidly in today’s global energy shortage and environmental degradation.The DC/DC conversion device,as an important energy conversion device,has become an important component of the entire fuel cell system.However,fuel cells have problems with soft output characteristics,slow dynamic response,and chattering,making higher quality DC/DC converters a major challenge.This article focuses on the research of control strategies for DC/DC converters used in fuel cells to address these issues.The main content is as follows:Firstly,the characteristics of soft output and slow dynamic response of fuel cells were analyzed.On this basis,with the goal of reducing current output ripple,improving power level,and reducing the volume of filter devices such as inductors and capacitors,a two-phase interleaved parallel bidirectional DC/DC converter is selected as the main topology.This paper analyzes the working principles of the converter in different modes for starting,increasing load,and reducing load in the practical application of fuel cells.Based on the characteristic analysis,the small-signal modeling of DC/DC converter is established by using the state space averaging method,which lays the foundation for improving the design of sliding mode controller.Secondly,a double integral sliding mode controller based on exponential reaching law is designed to solve the problems of the traditional sliding mode controller,such as large errors in response to lumped disturbances,long time to recover to the reference voltage value,and large chattering.Then,aiming at some problems in the double integral Sliding mode control,the robustness and dynamic performance of the controller are further improved,and a non singular integral terminal sliding mode controller with rapid convergence is designed and verified by simulation.In order to further optimize the chattering phenomenon existing in the sliding mode controller of DC/DC converter,a nonsingular terminal sliding mode controller based on the variable exponential power reaching law was designed by adopting a new reaching law from the inside,and was verified by simulation.Finally,three improved sliding mode controllers are simulated and compared.Finally,based on the theoretical analysis above,the hardware and software design of the bidirectional DC/DC converter were carried out.In terms of hardware,the driving circuit,sampling circuit,and protection circuit were designed respectively.In terms of software,the main program and subroutine flowchart were designed,and the main components were selected.