A High-Efficient Single-Switch Switched-Capacitor Partial Power Converter for On-Board Chargers
Niwton Gabriel Feliciani dos Santos, Ademir Toebe, Pedro Henrique Bulegon Löbler, Luciano Schuch, Mário Lúcio da Silva Martins, Cassiano Rech
Abstract
This article proposes a novel single-switch switched-capacitor (SC) series-connected partial power converter (S-PPC) for the dc–dc stage of an unidirectional on-board charger. The proposed step-down S-PPC features two key aspects: i) it performs partial power processing, reducing the active power processed by the dc–dc stage, and ii) it is transformerless, with the SC cell providing the necessary isolation to prevent a short-circuit between the low and high potentials of the electric vehicle (EV) battery pack. These characteristics allow the S-PPC to operate in a wide output voltage range with higher efficiency when compared to a conventional buck converter. To validate the analyzes, a 3 kW prototype was built and tested. It reached rated and peak efficiencies around 98.7% and 99.6%, respectively, in the constant current and constant voltage charging modes. Compared to previously published S-PPCs for EV charging applications, the SC S-PPC employs fewer semiconductors (only one active switch), which reduces its complexity and cost.