| The virtual motor system,as a power electronic load system that can emulate the characteristics of the motor port,provides a new method for the development and testing of motor driver.It has a good application prospect in the fields of new energy vehicle drivers,rail transportation,and industrial motor development.The virtual motor system has the flexibility of the all-digital system and real-time and reliability of the traditional motor test platform.Therefore,the development of virtual motor systems has gradually received attention.In order to simulate the complicated working conditions of the motor,this paper chooses the back-to-back two-level converter as the basic topology of the virtual motor.The research will be carried out from the two aspects of "converter control algorithm design considering fault characteristics simulation" and "high-quality power feedback" in order to improve the adaptability of virtual motor systems to complex working conditions and give full play to their excellent performance.In view of the complicated operating conditions of AC motors,transient and fault conditions need to be considered,and difficulties exist in mathematical modeling and real-time simulation of characteristics.When modeling the AC motor,the complex working condition of the stator winding interturn short circuit is considered,and then the results of different numerical calculation methods are compared,and the fourth-order Runge-Kutta is selected.Considering the characteristics of motor transient current and fault current,the quasi-proportional resonant controller is used for motor current tracking.Based on the consideration of the actual digital control delay,and on the premise of ensuring the stability of the system,the parameter design is aimed at maximizing the system bandwidth and dynamic response capability as much as possible.In order to achieve high-quality feedback of electric energy,the DC-side voltage fluctuations caused by the simulated motor transient process and fault conditions of the virtual motor system are analyzed first,and the grid-side current distortion caused by it is further analyzed.Then,the adaptive second-order digital notch filter is selected for harmonic suppression by comparison.At the same time,the parameters design and debugging methods of proportional integral controller considering different kinds of digital filters are analyzed.Finally,simulation and experimental results verify the reliability and rationality of the research content in this paper,and provide a reference for the research and application of virtual motor systems. |
