Evaluation of generator-sets with power factor correction circuits

Published work on the development of series hybrid electric vehicles (SHEVs) has always been directed towards volume and weight reduction for traction batteries and the electric drives with little attention into the generator-sets. This paper presents an overview as well as a comparison of conventional and unconventional power factor (PF) correction techniques applied to generator-sets operating in series hybrid electric vehicles (SHEV). The aim is to determine which rectifier topology demonstrates both: high PF, high output voltage and high efficiencies. Conventional PF correction techniques such as PWM operated rectifiers run at high switching frequencies, resulting in high switching losses. Controlled series compensator (CSC) rectifiers, which have been used in power transmission lines to improve the power factor, operate at much lower switching frequency, compared to conventional PWM controlled rectifiers, promising a reduction in switching losses, without PF degradation. The CSC rectifiers are less known in automotive and therefore here regarded as unconventional. The operation and performance of various topologies for both conventional and unconventional PF correction techniques for SHEVs is discussed and simulated using Matlab/Simulink. Simulation results in terms of the first harmonic of the phase current, total harmonic current distortion (THD), PF, output voltage and efficiency is provided. It is concluded that the switched variable capacitor (SVC) circuit is the most promising PF correction circuit for generators operating constant speed.