Reconfigurable Battery for Charging 48 V EVs in High-Voltage Infrastructure

Abstract

48 V is emerging as a safe-to-touch alternative voltage level for electric vehicles (EVs). Using a low- instead of a high-voltage drive train reduces isolation efforts, eliminates the risk of electric shock, and thus increases the system safety. In contrast, fast charging of a 48 V battery would require very high currents and is incompatible with the widely established high-voltage electric vehicle charging infrastructure. Instead of employing additional on board power converters for fast charging, the concept of a reconfigurable battery is presented. A small-scale prototype system is designed consisting of eight 48 V lithium iron phosphate battery modules. In series configuration, they can be charged at 460 V with up to 25 A. In 48 V parallel configuration, the peak discharge current is up to 800 A. The MOSFET-based reconfiguration system also operates as a module charge balancer during high-voltage charging. The cost overhead for the reconfiguration system is estimated to 3% for a scaled-up full size EV. Due to the additional reconfiguration switch resistances, the simulation of a 48 V 75 kW electric vehicle in the World harmonized Light-duty vehicles Test Procedure showed a performance reduction of 0.24%.

Performance Analysis of Two Receiver Arrangements for Wireless Battery Charging System

“…All the parameters in Figure 2, such as current, voltage, resistance, and power, are normalized. The normalization is carried out as follows: (i) current is normalized to the CC mode current ICC; (ii) voltage is normalized to the maximum battery voltage VM; (iii) resistance is normalized to the resistance at point N, equal to the ratio of VM and ICC and is denoted by RN; and (iv) power is normalized to the power at point N, given by Different architectures are proposed for receiver power circuitry together with parallel compensation [19,20] proposed, where the power conversion circuitry of the receiver includes a diode rectifier to supply the load with a direct voltage and resorts to different solutions for the adjustment of the voltage amplitude; research [21,22] provide the control of the AC voltage before applying it to the diode rectifier for secondary parallel compensation; and [23][24][25] use a diode rectifier cascaded by a buck converter. The most popular technique for a WBC receiver is to charge the battery in a straightforward manner with the diode rectifier or through a chopper and control the voltage of the power source in the transmitter to adjust the power absorbed by the battery.…”

“…Different architectures are proposed for receiver power circuitry together with parallel compensation [19,20] proposed, where the power conversion circuitry of the receiver includes a diode rectifier to supply the load with a direct voltage and resorts to different solutions for the adjustment of the voltage amplitude; research [21,22] provide the control of the AC voltage before applying it to the diode rectifier for secondary parallel compensation; and [23][24][25] use a diode rectifier cascaded by a buck converter. The most popular technique for a WBC receiver is to charge the battery in a straightforward manner with the diode rectifier or through a chopper and control the voltage of the power source in the transmitter to adjust the power absorbed by the battery.…”

A V2G Enabled Bidirectional Single/Three-Phase EV Charging Interface Using Modular Multilevel Buck PFC Rectifier

“…In the case of three-phase boost rectifiers (e.g., the conventional active rectifier comprising three legs of complementary power switches) with an input voltage of 415 V RMS, the output voltage ranges from 700 VDC to 800 VDC, which is too high to directly feed the DC-bus of EVs. In the second stage, a DC-to-DC step-down converter is required to reduce this voltage to a nominal voltage suitable for EV battery charging [10]. In this configuration, the total standing voltage (TSV) of the power switches of the rectifier and the DC-DC converter reaches the same level as the DC-link voltage [11].…”

Improved Battery Balancing Control Strategy for Reconfigurable Converter Systems

“…Currently, reconfigurable battery energy storage systems have attracted increasing attention due to their ability to dynamically reconfigure the battery topology in real time to adapt to specific application requirements [15][16][17][18][19]. This can more effectively utilize battery resources, isolate corresponding batteries according to their current state of charge and health status without affecting the charge and discharge processes of other batteries, and extend the battery's service life while reducing the possibility of module failure [20,21].…”