Magnetron Reactor And Its Application In Induction Motor Soft Starter

Three-phase AC asynchronous motor is a very important equipment in industry, agriculture, and traffic. It has the characteristic :low cost ,high reliability ,simple structure and convenient maintenance so that it is applied widely .But huge current and wallop will bring influence and damage to the motor itself ,the load the electric net and other equipments under the same net if the motor is started directly with full voltage .In this thesis, synchronous motor soft-start system based on variable reactance technique is studied .Magnet control soft-start system is the system that apply magnetic-valve type of controllable reactor into motor soft-start .Reactor winding is contacted with motor stator wind directly .Motor start with constant current by regulating the inductance of reactor. The reluctivity of reactor is controlled by accessional DC current which is got by commutating the net voltage through thyristors. In this system, we control the size of accensional DC current through changing the bust-angle of thyristor.First ,we analyze the circuit structure and basic work theory of magnet-control reactor in detail ,expatiate magnetization specialty and dynamic magnetization curve ,list the normal math-model and discuss the converting of all work states of magnet-control reactor .We analyze its harmonic characteristic and control specialty based on the MATLAB emulation model of magnet-control reactor used in soft-start system .What is more , the result shows that magnet-control reactor has the characteristic : smaller harmonic ,near linear V-A specialty ,faster response ,littler power loss ,etc.Secondly, we discuss the design and work theory of magnet-control Ac asynchronous motor soft-start system and analyze the design of hardware system based on INTEL 80C196KC .We draw the circuits of all parts .In the part of software, we design the flow charts of every segment with fuzzy PID arithmetic .Through the MATLAB we test the emulate the process of motor start with full voltage and under the control of oft-start system. The result shows that the soft-start system can reducemotor start-current.Last, we discuss and study the characteristic of traditional PID control theory and design the schema of PID parameter regulation of magnet-control motor soft-start system. We develop a new control scheme which is named as Fuzzy PID Control arithmetic. We also design the arithmetic table and the flow chart of Fuzzy PID Control software used in magnet-control asynchronous motor soft-start system.