METHOD FOR REDUCING COGGING TORQUE EFFECTS OF AN ELECTRICAL PERMANENT MAGNET MACHINE

摘要

A method for reducing coggingtorque effects of an electrical permanent magnetmachine (1) where the machine (1) is connectedto a drive (8), and where the drive (8) includes afeature of adding a torque componentindependent of a torque generated by a speed regulator,the machine having a rotor and a stator, where themethod includes: - measuring the angular positionof the rotor relative to the stator and the angularspeed of the rotor by use of a sensor (6);- running at least two tests with at least two differentcogging compensation signals from the drive (8)where one of the tests are designated an "a" testand another test is designated a "b" test; - analysethe received signal from the sensor (1) or sensorsto find the corresponding amplitude and phaseresponses of the vibration signal for said tests;- calculate a first value by multiplying the complexcogging amplitude of the applied compensationsignal for the a test with the complex amplitude ofthe vibration signal representing vibrationsresulting from the cogging torque of the b test;- calculate a second value by multiplying the complexcogging amplitude of the applied compensationsignal for the b test with the complex amplitudeof the vibration signal representing vibrationsresulting from the cogging torque of the a test; - calculate the desiredcomplex cogging compensation amplitude by dividing thedifference between said first value and said second value by the differencebetween the complex amplitudes of the vibration signalsrepresenting vibrations resulting from the b test and the a test; -apply acogging compensation torque to the machine (1) based onthe desired complex cogging compensation amplitude.