Abstract :
An analytical study of some implementations consisting of AC motors and various current source inverters (dual source, PWM chopping, capacitor filter). It is shown that with a well chosen time origin, the vectors representing the fundamental and the harmonic currents from the inverter are vectors having the same direction then enabling a very simple analytical torque ripple formula to be derived. In particular, it is shown that the torque ripple is not directly dependent on the bulk of the harmonic currents. In fact the current vectors must be examined by pairs. Those of a same pair produce torque pulsating at the same frequency which add or subtract to each other depending on their phase shift (vectorial sum). Examples are given for some specific schemes (such as dual current source inverter, PWM current source inverter, dual CSI and capacitor filter) as well as calculation of electrical resonance frequency and the filtering efficiency in relation to it.
