Research On Control Strategy Of Synchronous Reluctance Motor Drive Fed By Back-to-back Current Source Converter

As an indispensable part of modern industry,motor industry has been widely concerned by scholars.In addition to the design and optimization of the motor module,the reliability and economy of motor drive are also the research emphasis.At present,the type of motor drive can be divided into current source converter and voltage source converter.Although the loss of current source converter is larger and the open circuit protection is more difficult compared with voltage source converter,there are some advantages such as simpler topology,better output waveform,inherent four-quadrant operation,reliable fuseless short circuit protection and lower output dv/dt.Gradually,scholars pay more attention to current source converter.In medium and high voltage motor drive system,the application of current source motor drive is also increasing.Permanent magnet motors are widely used in the field of motor technology.However,the rare earth resources used to make permanent magnet motors are expensive and having an unstable productivity.Synchronous reluctance motor(Sy R)has a natural cost advantage,which is a type of motor that works entirely by reluctance torque.In order to find a substitute to the permanent magnet motor,the research of synchronous reluctance motor is crucial.This paper presents a drive system of synchronous reluctance motor fed by back-to-back current source converter.In the drive system,the current source rectifier(CSR)and is connected back-to-back with the current source inverter(CSI)through a dc-link inductor.The input and output side of the converter are connected parallel with three-phase ac capacitor.At the same time,the three-phase inductance connects in series between the input side and the power grid,the output side connects directly to the synchronous reluctance motor.At first,this paper introduces the structure of back-to-back current source converter and the working mode and control strategy are analyzed in detail.Secondly,based on the operation principle of synchronous reluctance motor,this paper introduces the control method of synchronous reluctance motor and designs the vector control strategy of motor drive system fed by current source converter.Thirdly,the loss model of synchronous reluctance motor is deduced.At the same time,aims at the loss problem of current source converter,this paper analyzes and models the losses of the converter,including switching loss and conduction loss.The loss models of motor and converters are combined to reach the minimum loss control method for overall system.At last,because the rotor convex polarity of Sy R is obvious,this paper studies a sensorless control method based on high frequency signal injection,which eliminates the position sensor connected axially to the motor and reduces the total cost of proposed system.In order to verify the feasibility of the proposed control method,a prototype platform for current source converter fed motor drive is built in the laboratory.The principle verification of various control strategies is carried out on the prototype platform and the experimental results are analyzed in this paper.