Research On Simulation Method Of AC Motor And Load

In the experiments on performance test of motor driver,a scheme of "actual motor + mechanical load" is often adopted.It has many shortcomings,such as insufficient testing,complicated system,high energy consumption,and inflexible parameter adjustment.In this dissertation,a motor simulator system designed to simulate the characteristics of AC motors is proposed.It can replace the actual motor and its load.It makes the experiment of frequency conversion driving more convenient,while providing guidance for control optimization.According to the mathematical model of the motor,the motor simulator system of VTC-mode and CTV-mode is studied.For the latter,this dissertation studies two kinds of motor simulators of L and LCL respectively.The main content and innovations are as follows:(1)Establishment of dynamic mathematical model of AC motor and its load.Several different numerical calculation methods were analyzed.In order to choose the appropriate discrete step size,the accuracy of two-step Adams method for solving motor mathematical model is compared under different discrete steps.The difference equation of motor model is established.The command current or voltage of motor simulator is obtained by solving motor model.(2)Research on VTC-mode motor simulator system.The basic structure and working principle of VTC-mode motor simulator system are introduced.The current loop control strategy under two-phase stationary coordinates is adopted.Aiming at the difficulty of measuring PWM wave voltage,a sampling method based on double integral reset is proposed.In the case where motor simulator is connected to a sine wave power supply and a PWM wave power supply,the scheme of the voltage type motor simulator is verified.(3)Research on CTV-mode motor simulator system.Firstly,the motor simulator system with filter circuit L is introduced.and its current ripple and error are analyzed.The relationship between the switching frequency of the power supply and the switching frequency of the analog converter is analyzed.On this basis,the motor simulator system with filter circuit L is introduced,and a double-loop control strategy based on virtual rotor flux linkage is proposed.(4)Through simulation,the current and speed characteristics of improved currenttype motor simulator under various operating conditions is analyzed and compared with the VTC-mode motor simulator.The effects of parameter deviations on the virtual stator circuit are discussed.Taking DSP28377 as the core,the experimental platform of motor simulator was built.And the no-load and load-load conditions of motor simulator were experimentally verified.