| Bidirectional DC/DC converters have been widely used in the fields of computer,new energy power generation,aerospace and transportation due to small size,light weight and high efficiency.Supercapacitors are widely used as energy storage components in electric locomotive,and the bidirectional DC/DC converter can realize the charge and discharge of supercapacitors.Sensor is an important part of the control system of bidirectional DC/DC converter.For the main circuit of the converter,the fault of switching devices will seriously affect the safe operation of the system.In view of this,this paper proposes a fault diagnosis and fault-tolerant control scheme for sensors and switching devices based on state observer to realize fault diagnosis and fault-tolerant control for sensors and fault diagnosis for converter switching devices at the same time.This paper established the mathematical model of bidirectional DC/DC converter and double closed loop control system design,according to the mathematical model for the further design state observer of bidirectional DC/DC converter in Buck and the Boost operating mode,through to the inductor current and output voltage accurately observation,can keep the observation error within the scope of the permit,and ensure the actual observed value to fast track sensor acquisition value,introduces the observed value of state observer to control system of double closed loop control of sensorless experiment,the results prove the validity of the proposed state observer.Aiming at the sensor fault diagnosis of bidirectional DC/DC converter and the fault diagnosis of switching devices,this paper obtains the observed values of inductive current and output voltage through the state observer,and differentiates the observed values from the collected values of the sensor to establish the residual and threshold analysis system,so as to realize the real-time online diagnosis of sensor faults.When the fault diagnosis unit detects the fault of the sensor,the fault-tolerant control system automatically switches the sensor acquisition value to the state observation value quickly and smoothly for the control system reconstruction,and finally realizes the fault-tolerant control in the case of sensor fault.For the switching device fault diagnosis,this article uses the algorithm of fault diagnosis based on state estimation,when switching device malfunction,the bidirectional DC/DC converter system has changed,and the mathematical model and state observer of the observation error can divergent rapidly in a short time,more than the threshold,then fault diagnosis unit fault signal of the output devices,and realizes the switching device fault diagnosis.Simulation results show the effectiveness and feasibility of the proposed algorithm.In order to verify the algorithm proposed in this paper,a physical experiment platform is built with TMS320F28335 as the controller,including the design and implementation of the main circuit,sensor detection and other circuits.Fault diagnosis and fault-tolerant control experiments of bidirectional DC/DC converter are carried out.Experimental results demonstrate the effectiveness of the proposed algorithm. |
