Simultaneous DC-Link and Stator Current Ripple Reduction With Interleaved Carriers in Multiphase Controlled Integrated Modular Motor Drives

To meet the demand for increasingly high power density in electric drives, the concept of a so-called integrated modular motor drive has emerged. The machine is composed of multiple identical modules, which receive individual control signals for multiphase control, to reduce unwanted stator current harmonics. Each module is equipped with its own power electronic converter, which is integrated in the machine housing. This integration imposes strict constraints on the dc-link capacitor design. To reduce the dc-link current ripple, and hence relax the design constraints on the dc-link capacitor, without compromising the possibility to eliminate unwanted stator current harmonics by means of multiphase control, a new interleaving strategy is proposed in this article. The n modules of the machine are split into p subgroups of m modules for interleaving, while the n-phase control is preserved. An analytical model, simulations and experimental results are provided for a 4 kW test setup, confirming that multiphase control can be combined with interleaving. As a result, both the stator current harmonic distortion and the dc-link current ripple can be reduced simultaneously.