Ultrafast Rectifier for Variable-Frequency Applications

Abstract

In this paper, an ultrafast active rectifier is presented for variable-frequency applications. Three-phase ac-dc converters (rectifiers) are extensively implemented in motor-drives, wind turbines, electric vehicles, and aircraft's power systems. In some technologies, e.g., more electric aircraft and drones, power systems may employ variable-frequency generators for higher efficiency and reliability indices. The proposed ultrafast rectifier is equipped by a step-ahead predictive control scheme, an instantaneous phase-locked loop (PLL), and a module of six SiC MOSFETs. The control scheme regulates the dc voltage and maintains unity power factor with an extremely low total harmonic distortion in the input currents. The instantaneous PLL, applicable only for three-phase systems, is integrated to the proposed variable-frequency control scheme in order to minimize the error in the power factor. The step-ahead predictive scheme and instantaneous PLL combination provides fast and smooth dynamic responses under rapid frequency transients. Experimental results are presented using a laboratory-scale SiC-based MOSFET 115VLL/270Vdc rectifier, and the performance of the proposed controller is compared with a classical power factor correction controller in the presence of frequency ramp and step changes. The experimental results demonstrate a superior dynamic performance of the proposed ultrafast active rectifier.