Design and Control of Modular Multilevel Converters for Battery Electric Vehicles

Abstract

New advanced power conversion systems play an essential role in the extension of range and life of batteries. This paper proposes a new modular multilevel converter with embedded electrochemical cells that achieves very low cell unbalancing without traditional balancing circuits and a negligible harmonic content of the output currents. In this new topology, the cells are connected in series by means of half-bridge converters, allowing high flexibility for the discharge and recharge of the battery. The converter features a cell balancing control that operates on each individual arm of the converter to equalise the state of charge of the cells. The paper shows that the proposed control does not affect the symmetry of the three-phase voltage output, even for significantly unbalanced cells. The viability of the proposed converter for battery electric vehicles and the effectiveness of the cell balancing control are confirmed by numerical simulations and experiments on a kW-size prototype.

Reverse-blocking modular multilevel converter for battery energy storage systems

“…Fig. 1b illustrates one of the possible SM realizations proposed in [25], which consists of two IGBTs with antiparallel diodes and one capacitor that together form a typical bidirectional chopper. The distributed battery banks are directly connected across the SM capacitors.…”

“…The published literature mainly relates to their applications to high-voltage DC (HVDC) transmission [16][17][18], MV electric drives [19][20][21], and STATCOMs [22,23]. MMCs used in BESSs for interfacing low-or medium-voltage batteries to mediumor high-voltage grids were reported in [24][25][26][27]. They enable a flexible scaling of power modules to integrate energy storage and power electronics to a wide range of operating voltages, output power and stored energy.…”

Research on Unbalance Fault-Tolerant Control Strategy of Modular Multilevel Photovoltaic Grid-Connected Inverter

“…With its unique advantages of decentralized energy storages, modular structure, easy redundant SMs (SMs), simple fault identification, and clearance [5], MMC has been widely applied at various levels of power converters, such as high-voltage direct current (HVDC) transmission systems [6,7], DC-DC power electronic transformers [8], battery electric vehicles [9], distributed energy resources (DERs) [10,11], and flexible AC transmission systems (FACTS) [12]. Considering the long-existing issues of low utilization rate of light energy and potential influence on power grid in photovoltaic (PV) grid-connected system, the application of MMC in PV grid-connected systems is gaining more and more attention [13][14][15].…”

Super Capacitor Energy Storage Based MMC for Energy Harvesting in Mine Hoist Application

“…Thus, the super capacitor energy storage based MMC (SCES-MMC) is more suitable for mine hoist application. However, published technical papers focus mainly on battery energy storage system (BESS)-based MMCs [20,21]. In view of the above issues, this paper adopts the SCES-MMC for energy-harvesting applications.…”