Operating a synchronous motor having a permanent magnet rotor

Abstract

The invention relates to a method of operating a synchronous motor (1) having a stator comprising a set of electromagnets (7, 9) and having a permanent magnet rotor (5), wherein the synchronous motor (1) is controlled by calculating in a flux controller (f) a measure of a flux magnitude, which is the magnitude of the stator flux of the motor (1), and is controlled by calculating in a load angle controller (g) a measure of a load angle. Information about a desired motor torque or a reduced motor torque, which is smaller than the desired motor torque, is input to the load angle controller (g) and the load angle controller (g) calculates the measure of the load angle depending on the input motor torque. The measure of the flux magnitude is combined with the measure of the load angle to obtain commands for controlling electric currents of electromagnets of the stator, thereby directly controlling the stator flux. A flux limit value which depends on a predetermined maximum value of the stator flux allowed for the motor (1), which depends on a maximum value of an electric voltage, which is used to drive the currents through the stator electromagnets (7, 9), and which depends on the actual rotor speed is repeatedly calculated. During acceleration of the rotor (5) while the stator flux is smaller than the maximum flux allowed for the motor the measure of the flux magnitude is calculated depending on the output of a predetermined function, wherein the output of the predetermined function depends on the desired motor torque and corresponds to the magnitude of the stator flux, which results in the desired motor torque using the minimum possible stator current. The measure of the load angle is calculated depending on the desired motor torque.

Description

technical field [0001] The invention relates to a method of operating a synchronous motor having a stator comprising a set of electromagnets and having a permanent magnet rotor. This motor is commonly referred to as a permanent magnet synchronous motor (PMSM). The invention also relates to a device for operating the electric motor. A particular area of ​​interest is the control of PMSMs, which are the propulsion motors of rail vehicles. Background technique [0002] Typically, asynchronous electric motors with a rotor with at least one electromagnet are used for propulsion of rail vehicles. The term "rail vehicle" includes any trajectory-constrained vehicle. These asynchronous motors can be easily controlled since not only the electromagnets of the stator but also single or multiple electromagnets of the rotor can be adapted to the desired operating behavior. However, PMSM motors have some advantages. In particular, the power density (power available per volume) is high...

AI Technical Summary

Problems solved by technology

On the other hand, as mentioned, if a fast response of the motor is required in dynamic situations, and if efficient use of resources (specifically available voltage and energy) is important, the control of PMSM is more difficult

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