Abstract
Conventional balance modules are integrated with the battery management system (BMS) and occupy a large area of the BMS system. In addition large balance currents generate high heating rates and require heat dissipation mechanisms. This study proposes an independent structure for the balance module. Specifically the balance module is removed from of the BMS and is integrated with an off board charger. A new BMS structure is therefore created with a simplified BMS inside the battery module and the heat dissipation requirement for the balance module could be easily met on the charger side. The design, fabrication and test of this new type of BMS on a 72 V heavy electric motorcycle application is detailed in the current work. The new BMS reduces the space and weight required for the BMS in the e-motorcycle. Complexity in the battery module or on the EV side is significantly reduced. The heat dissipation problem associated with the large balance current is also resolved by moving the balance module to the charger end.
Highlights
Discrepancies in cell internal resistance and differences in cell capacity are common among cells connected in series
A 72 V electric heavy motorcycle as shown in Figure 8 was designed and fabricated in the current study to test the performance of the developed battery management system (BMS)
The remaining BMS or main control subsystem is electrically connected with the main battery module inside a 72 V motorcycle to measure cell operation parameters, protect cells from extreme operation limits, and extract and monitor vehicle power parameters
Summary
Discrepancies in cell internal resistance and differences in cell capacity are common among cells connected in series. Without an effective balancing mechanism in the battery management system (BMS), the lifetime of battery modules could be prematurely shortened and this could lead to catastrophic disasters [1,2]. The BMS is imperative for active or passive balance circuits to overcome the inconsistency problems among serially connected cells. Low power resistors are used to shunt charging currents to overcome the inconsistency among cells in series [3,4,5]. If fast balance is needed, high resistors with high heat generation are required with passive methods. If the inconsistency level is high among cells, overcharging is unavoidable in practice. Overall passive methods have low efficiency and are not suitable for large storage capacity applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
