Research On Sensors Fault Diagnosis And Tolerant Control Of Inverter

With simple structure, easy fabrication, low price and etc, induction motors are widely used in industrial control system. Especially the application of high performance vector control makes induction motors have more obvious advantages.Generally, the vector control needs inverter. It is known that inverter is increasingly used in the industrial drive application because of its small size, high efficiency and the function of realizing a wide range of regulating speed smoothly. However, like other power electronic devices, inverter may have fault since device aging,abnormal condition or malfunctions caused by wrong operation. In some special cases, such as aviation, navigation or power stations and steel mills, the sudden failures of inverters lead to great economic losses, even personal casualties. Today,one of the important indicators of inverters’ performance is whether they have the ability of fault diagnosis and tolerant control. In general, current sensors and speed sensor are utilized in vector control, while the sensors are precise instruments which are too vulnerable to malfunction. In this paper, in order to increase the reliability of inverter, sensors fault diagnosis and tolerant control of inverter is researched.Firstly, the proposed current observer is introduced by analogy with Luenberger observer. The stability of current observer is proved from theoretical viewpoint and the detail derivation of the current observer’s parameters are presented. A novel vector control method of induction motor with single phase current sensor based on the current observer is proposed which is used for tolerant control when two current sensors have fault. The validation of the current observer is proved by means of simulation of Matlab and several experimental results.Secondly, the diagnosis principle of the first current sensor fault is deduced by means of analyzing the equivalent circuit of induction motor. Two kinds of approaches are used to analyze the change of values when the second current sensor has fault. The method of speed sensor fault diagnosis and tolerant control based on vector control of induction motor with single phase current sensor is proposed by means of analyzing the characteristics of current observer and analyzing the input of Luenberger observer. Extensive simulations and experimental tests verify the validation of proposed approaches.At last, the effectiveness of the proposed strategies is verified with the experimental results at d SPACE real-time simulation system and a 1.1k W induction motor dive system.