Authors: Abhinandan Dixit; Karan Pande; Sivanagaraju Gangavarapu; Akshay Kumar Rathore
On-board battery chargers (OBC) are a crucial part of electric vehicle (EV) industry. OBC comprises of a two-stage structure where front-end converter is a power factor correction (PFC) unit and a back-end DC-DC converter which controls the battery charging process. The front-end converter is the most complex part of the battery charger in terms of control and design. This paper proposes a single-phase switched-mode bridgeless ac-dc buck-boost derived converter that can serve as a front-end converter for the on-board EV charging application. The bridgeless scheme rules out the orthodox bridge rectifier and the affiliated losses. The proposed converter operates in discontinuous current conduction mode (DCM), thus achieving natural power factor correction for variable ac input. In addition to this, sensing of input voltage and input current is fended off because of DCM operation making the converter reliable, cost-effective, and robust compared with conventional continuous current conduction mode converters. Furthermore, the control becomes simple with the employment of a single sensor and the elimination of the phase-locked loop. The proposed front-end converter is well suited for low-voltage battery chargers ranging between 1.0 and 3.3 kW installed in golf-carts and E-rickshaws. A comprehensive steady-state analysis for one switching cycle and the design equations of the proposed converter are presented. The small-signal model of the proposed converter is presented for the implementation of the closed-loop control. Experimental results from a 1.0-kW concept-proof hardware prototype have been demonstrated, which upholds the converter analysis.
This paper is published in IEEE Journal of Emerging and Selected Topics in Industrial Electronics.
Check full paper at: https://ieeexplore.ieee.org/document/9107391