Module Connection Topologies and Interleaving Strategies for Integrated Modular Motor Drives

Abstract

The search towards increasingly high power density in electric drives led to the integration of the power electronics in the housing of the electrical machine. To obtain such a socalled integrated modular motor drive, the machine is split into several modules, with their own dedicated converter and control signals. The individual control of the modules allows to eliminate unwanted current harmonics by means of multiphase control. However, the integration of the power electronics in the machine housing imposes a stringent volume constraint on the DC link capacitor. In order to be able to downsize the DC link capacitor, without compromising the additional degrees of freedom that allow to compensate current harmonics, a new interleaving strategy is proposed in this article. Simulations and experimental results for a 4 kW test setup show that multiphase control can be combined with interleaving, resulting in both a reduction in stator current harmonic distortion and DC link current ripple. Fifteen phase- instead of three phase control reduces the stator current harmonic distortion for the considered drive by a factor 1.74, but increases the DC link current ripple with a factor 1.15. If combined with interleaving, the reduction in stator current harmonic distortion remains a factor 1.69, but the difference in DC link current ripple decreases to a factor 1.01. The proposed fifteen phase interleaving strategy leads to a real-life reduction of more than 50% in the DC link current ripple.