Nonlinear Fault-tolerant Tracking Control for DC-DC Boost Converters with Measurement Faults

Power converters aim to provide powers suitable for loads, which can widely be found in our daily life and industrial systems. DC-DC boost converters can achieve a higher voltage on the load compared with the supply voltage, and a closed-loop controller is used to track desired inductor current and capacitor voltage. Due to age or unanticipated reasons, measurements via sensors could be faulty or distorted. The faulty measurements are sent to the controller which may cause incorrect control commands, leading to distorted trigger signals, so that the inductor current and capacitor voltage depart from the desired values. As a result, there is a strong motivation to design a fault-tolerant tracking controller for the boost converter to achieve a fault-tolerant performance under faulty sensor situations. In this chapter, fundamentals of boost converters including modelling and nonlinear tracking controllers are firstly reviewed. A nonlinear current observer is then presented to achieve a simultaneous estimate of system states and current sensor faults, from which a real-time monitoring and fault diagnosis is attained. By using current sensor signal compensation, a fault-tolerant current tracking nonlinear controller is designed, and the passivity of the closed-loop boost converter system is proved. Nonlinear fault-tolerant voltage tracking control approach is next addressed under faulty measurement of the capacitor voltage, using real-time voltage sensor fault estimation and sensor-compensation under nonlinear control scheme. For the scenario considering faulty measurements for both voltage and current sensors, a nonlinear dual fault-tolerant control strategy is proposed by using estimates of both voltage and current sensor faults, dual compensation and dual tracking under nonlinear dynamic control. The proposed nonlinear fault-tolerant control algorithms for boost converters are well demonstrated by simulation studies.