Quasi-Z-source on-board charger based on reducing the size of the DC-Side active power buffer for electric vehicle applications

Abstract

Active power buffer (APB) modules in single-phase quasi-Z-source rectifiers (qZSRs) can effectively decrease the double-line frequency power ripple. APB modules can eliminate bulky passive devices, potentially improving system power density and reliability. However, single-phase qZSR systems with AC-side active power buffers (AC-SAPBs) raise system costs, power losses, and control complexity. They require low-reliability aluminum electrolytic capacitors (Al-Caps) and large inductors on the power grid input side to absorb the second-frequency ripple. This study, for the first time, proposes the inclusion of DC-side active power buffer (DC-SAPB) in single-phase qZSRs. The proposed system not only offers the benefits of AC-SAPBs but also reduces the power loss and control complexity. Moreover, metallized polypropylene film capacitors (MPPF-Caps) or multilayer ceramic capacitors (MLCCaps), and small inductors can be used with higher reliability levels. The proposed topology can be employed in the integrated on-board charger of electric vehicles. A comparison between the DC-SAPB and AC-SAPB modules reveals that the former provides a higher performance and efficiency than those of the latter owing to its reduced weight and volume; hence, a large amount of energy can be stored in the battery. The simulation and experimental results verified the performance of the proposed system.