Regenerative Active Front End based motor-drive systems with enhanced dynamic performance

Motor-drive systems with a Regenerative Active Front End (AFE) are a very important segment in the drives market. The main advantages are that they do not require braking resistors, they provide an input current with significantly reduced Total Harmonic Distortion (THD), and they generate a unity power factor. Furthermore, AFE based systems can inject reactive power back into the line as needed to provide power factor correction within a given drive's thermal capacity limits. However, AFE design as a critical part of a motor-drive system still faces several challenges such as LCL resonance condition, limited dynamic performance under certain grid conditions, and deteriorated performance when system parameters are not well known. This paper introduces a DC bus observer algorithm that can be utilized within an AFE to significantly reduce or even eliminate these challenges while improving dynamic performance.