Synchronous servo motor with field weakening

A synchronous servo motor with field weakening can reach higher speeds with simultaneously, slowly reducing engine torque.

In addition, control reserves be achieved in the area of 'characteristic speed point'.

 

 

During the transition to the field weakening, the inverter injects in the winding a negative field weakening current Id.

Thereby, the field of the permanent magnet is weakened. The 'voltage constant Ke' decreases, which reduces the induced voltage.

A torque-generating current Iq can flow.

 

The negative field weakening current Id caused losses. The maximum motor current "Imax" must not be exceeded.