Commutation angle analysis of the slip energy recovery drive

A well known characteristic of the slip energy recovery drive (SERD) is the large commutation overlap of the rotor side rectifier, which compromises the accuracy of simplified dq models often used for its simulation. In this paper the variation of the rectifier commutation angle and the factors that determine its magnitude are investigated using a detailed hybrid abc-dq model of the SERD, the accuracy of which is validated by experimental results. The dependence of the commutation angle on the DC current and the operating slip is shown for a case study drive and practical relations are deduced which permit the evaluation and a-posteriori correction of the steady state error of simplified dq models, where the commutations and converter harmonics are ignored.