A Wide Intermediate and Output DC Link Based Efficient Modulation Technique to Design PEV Charger Using Single Phase Vienna Rectifier

Abstract

For EV charging applications, single phase Vienna rectifier operated using classical modulation approach has problems with significant variations in efficiency and input current ripples. Additionally, for the efficient operation of DC-DC stage, the design of an electric vehicle (EV) charger employing an LLC resonant converter necessitates active management of the intermediate DC link with wide operation voltage range. To address this problem, this paper presents the design of single-phase portable EV charger using Vienna rectifier and full bridge LLC converter (FB-LLC). Here, rectifier stage is controlled through an efficient modulation technique (EMT), which provides half switching losses, current ripples and wide regulation of rectified voltage over real time variation in the battery terminal voltage. The LLC stage is controlled with optimum efficiency point frequency modulation technique to provide high efficiency operation over complete battery terminal voltage range. For better power factor correction (PFC) under distorted grid voltage scenarios, a frequency fixed (FF) second order generalized integrator (SOGI) is utilized for grid angle generation. This technique provides healthy estimation of grid angle under the presence of DC offset, harmonics, frequency, and phase drift in grid voltage. With the integration of grid voltage angle estimation algorithm in the control of single-phase Vienna rectifier, this converter possesses better PFC performance under both weak and strong grid conditions. A 2 kW EV charger with a battery pack terminal voltage range from 240–550 V, is designed and simulated to validate the performance of the designed system.