| Abstract |
The technique described here can be applied to permanent magnet excited machines which use a rotor with movable magnets to reduce the field at higher speeds. This method does not need actuators in the rotor to shift the magnets in order to achieve the desired angle between them. All forces needed for shifting, are produced by the stator currents. Under constant power operation in the field weakening range, the e.m.f. should be constant and the torque intensively proportional to the speed. To achieve such characteristics, special control of the currents in the d- and q-axes was developed. A machine which uses this new technique was built and tested in a drive with a PWM-converter controlled by a microprocessor. The first results showed correct operation of the system and proved the theoretical speculations. |
