Research On Full Speed Domain Flying Start Of Permanent Magnet Synchronous Motor Sensorless Control

Permanent magnet synchronous motors are widely used in the drive systems of rail transportation and new energy electric vehicles because of their advantages such as high efficiency and high power density.Position sensorless control with flying start technology is the current research hotspot of PM synchronous motor.However,in practice,it is difficult to meet the conditions of short-circuit current method in some working conditions,and due to the limitation of short-circuit time and short-circuit interval time,there is a contradiction that can not simultaneously suppress the inverter overcurrent and achieve high rotor position estimation accuracy.There are limitations in the application of the existing methods of flying start,and it is difficult to achieve the full speed domain flying start with a single method.In this paper,the full-speed band flying start technique for permanent magnet synchronous motors is studied.First,a parameter adaptive short-circuit current method is proposed in this paper.Unlike the traditional short-circuit current method which uses fixed parameters such as short-circuit time and short-circuit interval time,this method is based on the test short-circuit current calculation to obtain the test speed,and then determines the parameters of the short-circuit current method according to the test speed adaptively,which can avoid over-current in the high-speed region and also ensure the accuracy of the position estimation in the low-speed region.Secondly,for the problem that it is difficult to achieve full speed domain flying start by a single method,this paper proposes a strategy to cover full speed domain flying start.When the idling motor is in the weak magnetic region,the rotor position is observed using the Longberg state observer based on the three-phase motor current of the idling motor,and the flying start method using the adaptive short-circuit current method when it is in the non-weak magnetic region.For the switching interval where neither of the above two methods is applicable,this paper proposes a flying start method using repeated short circuit and combined with the Longaberger state observer.Based on this,a logical switching strategy is designed to combine the above three methods to achieve the full-speed domain flying start.Finally,simulations and experiments are conducted to verify the above methods,and the results show that the above methods can achieve the full speed domain flying start,and the proposed adaptive short-circuit current method also has higher accuracy than the traditional methods,and the current impact during the flying start is smaller and the results are excellent.