Research On Four-quadrant Control Of Induction Motor Based On Hybrid Of Thyristor And IGBT

Induction motors,as a bridge between mechanical energy and electrical energy in production and life,are often in a uncontinuous working state,especially when the motor is in a braking state,the motor generates energy.Front-end rectification uses fully controlled power electronic devices such as insulated gate bipolar transistors(IGBTs)to form a dual PWM converter,so that the energy generated when the induction motor is in a braking state can be fed back to the grid to save energy.However,Due to the large number of dual-PWM converter power electronic devices currently used,On the one hand,It increases the cost of the induction motor control system;On the other hand,It also increases the switching losses of power electronic devices.Therefore,Thesis uses thyristors to replace part of insulated gate bipolar transistors(IGBTs),and proposes a dual PWM conversion topology based on thyristors and IGBTs.The PWM conversion topology structure can not only feed back the energy generated in the braking state of the induction motor to the power grid,but also reduce the cost of the induction motor drive system and reduce the switching losses of power electronic devices.In this regard,based on the mathematical model,This paper is based on the double PWM conversion pulse width modulation technology of thyristor and IGBT,the rectifier control strategy based on thyristor and IGBT hybrid,the induction motor control strategy based on thyristor and IGBT hybrid,and the four-quadrant operation coordination of induction motor Control and other key technologies have been theoretically analyzed and studied.First of all,the working principle of four-quadrant operation of induction motors composed of thyristors and IGBTs is analyzed in detail,and the mathematical models of the front-end rectifier and induction motors in three different coordinate systems are established.Secondly,Due to the symmetry of the new rectifier and inverter structure based on the thyristor and IGBT,the front-end rectifier is used as an example to analyze its energy transmission path under different switching states and establish the switching timing diagram;for the IGBT drive signal,Analysis based on SPWM pulse width modulation technology.Then,the four-quadrant operation topology structure of induction motor based on thyristor and IGBT is divided into rectification part and induction motor control,and the control system is designed by double closed-loop control strategy and vector control strategy respectively.In order to better integrate the front-end rectification part and the back-end induction motor control part,the load current feedforward control is introduced.In order to verify the rationality of the four-quadrant control system for induction motors based on thyristor and IGBT hybrids designed in this paper,simulation models were built in simulation software.The simulation results show that the induction motor drive system based on thyristor and IGBT hybrids proposed in this paper can realize the four-quadrant operation of induction motor while reducing the system cost.Finally,In order to verify that the topology based on thyristor and IGBT hybrid proposed in this paper can realize PWM modulation,an experimental platform of inverter based on thyristor and IGBT hybrid is built.The experimental results show that the inverter based on thyristor and IGBT hybrid can be realized.Orthogonal transformation,and the three-phase sinusoidal waveform degree is better,demonstrates the feasibility of the proposed induction motor drive system based on thyristor and IGBT hybrid.