Efficiency Assessment of Modular Multilevel Converters for Battery Electric Vehicles

Abstract

This paper evaluates the performance of modular multilevel converters with integrated battery cells when used as traction drives for battery electric vehicles. In this topology, individual battery cells are connected to the dc link of the converter submodules, allowing the highest flexibility for the discharge and recharge. The traditional battery management system of battery electric vehicles is replaced by the control of the converter, which individually balances all the cells. The performance of the converter as a traction drive is assessed in terms of torque-speed characteristic and power loss for the full frequency range, including field weakening. Conduction and switching losses for the modular multilevel converter are calculated using a simplified model, based on the datasheet of power devices. The performance of the modular multilevel converter is then compared with a traditional two-level converter. The loss model of the modular multilevel converter is finally validated by experimental tests on a small-scale prototype of traction drive

Recent contributions and future prospects of the modular multilevel converters: A comprehensive review

“…Performance evaluation of MMCs when operated as traction drives for electric vehicles is performed in a comprehensive way in Quraan et al Proposed MMC topology is scrutinized in terms of torque speed characteristic, conduction, switching, and power losses. Comparative study is also carried out between presented topology and conventional two level inverter, which concludes good results.…”

A Control Strategy of Modular Multilevel Converter with Integrated Battery Energy Storage System Based on Battery Side Capacitor Voltage Control

“…In Reference [15], the SOC equalization of MMC-BESS considering the capacity inconsistency of batteries was proposed. In References [10,16], the MMC-BESS was applied in battery electric vehicles and the efficiency of this topology was assessed. Furthermore, the control strategy of MMC-BESS under AC and DC fault has been studies in Reference [17], realizing SOC equalization under fault conditions.…”

“…In this paper, this topology is abbreviated as the MMC-BESS. The integration was implemented by inserting battery cells into each submodule (SM) of MMC directly or through a DC/DC interface [10,11]. Due to this distributed integration mode of BESS, the state-of-charge (SOC) equalization of each battery was facilitated, improving the effective utilization rate of BESS compared with the centralized scheme at the DC-link of MMC [12].…”

Modified State-of-Charge Balancing Control of Modular Multilevel Converter with Integrated Battery Energy Storage System

“…However, the calculation of zero-sequence voltage is too complex. In [21,22], the DC and fundamental circulating current are regulated to balance the SOC among phases and between arms respectively. The SOC within arms is balanced by regulating the submodule voltage, which contains both the DC component and AC component.…”