Early electric vehicles (EV), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) used either lead-acid batteries or NiMH batteries for storage.
However, these batteries were not optimal: EVs, HEVs, and PHEVs require impressive energy storage that even NiMH batteries, with a 68Wh/kg specific energy, aren't capable of.
In search of higher energy-efficiency, many manufacturers have turned to lithium-ion batteries, such as lithium-titanate, lithium-phosphate and lithium-manganese, for electric vehicles. Optimal and safety use of these batteries requires a battery management system (BMS).
Because each BMS function takes energy, BMS designers must prioritize designs. Many BMS do not log data, for example, and they may fall short when estimating the battery's present state or overall state.
However, one of the most critical functions is protecting the life of the EV's battery. Safety is vital in today's modern car. Due to the high energy contained in the battery and the risk in the event of a collision or short circuit, safety is a major consideration when choosing a battery management system.
A BMS must be linked to all battery components, as well as the vehicle's computer. The BMS will take several sensor readings, including but not limited to:
- Sensing the cells' voltage and timing the battery's charging or discharging. This gives a battery indicator to the user, but more importantly, it prevents overcharging, which can result in a dangerous thermal runaway. This will include balancing individual cells within the battery.
- Sensing and controlling temperature. Unusually high or low cell temperatures indicate serious problems in progress.
- Sensing current. Abnormal current indicates a safety risk and provides vital data to algorithms that determine the battery's present state and overall health.
- Detecting and reacting to ground faults.
- Taking logs on unusual readings for real-time and later diagnostics.
- Communication with other battery components.
- Prolonging battery life, which is made possible by careful application of the items above.
Design Challenges of Battery Management Systems
Taking the many sensor readings listed above poses a design challenge, regarding the physical structure of the battery.
Series- and parallel-connected cell structures both create accurate monitoring. Companies have traditionally used centralized, distributed and modular functions to meet the needs of BMS systems.
While many portable electronics have sophisticated BMS systems, EV, HEV, and PHEV BMS have traditionally lagged behind these due to the complicated task of balancing the hundreds of high-powered cells in an EV's battery.
Cell balancing often involves the development of new algorithms and more precise detection methods, although incremental design changes have assisted with cell balancing as well.
Isolation is also critical, to protect delicate systems from batteries' high energy. That's why Pulse Electronics has designed isolation transformers and common-mode chokes for battery management systems. These isolate multiple high-energy cells from one another, to improve safety and overall function.
Battery Management System (BMS) Components for Voltage Isolation, EMI Noise Suppression, Cell Protection, & Reliable Operation
Pulse Electronics offers a wide range of isolation transformers and common mode chokes for use in electric vehicles and energy storage systems.
All parts meet AEC-Q200 requirements for automotive applications, supports daisy chain connections, and large voltage differences within a single device.
Features and Benefits:
- Supports BMS isolation and EMI solutions
- Supports serial Daisy Chain isoSPI, SPI and other signal isolation
- Meets AEC-Q200 requirements for automotive applications
- PPAP documentation upon request
- IATF 16949:2016
- Operating temp. -40C up to +150C
- Multiple options for working voltages and voltage isolation
- 15 Years working life on Isolation
The following Pulse Electronics Battery Management System Components are available for product designers:
Battery Management System Components
battery-management-system-designer-kitFor networking devices used in small and large battery pack systems for serial port safety isolation and EMI noise rejection application.
- Electric Vehicle
- Energy Storage Systems
- Data Center UPS
- Solar energy storage
- Green – Renewable
You can purchase the parts by clicking the button below, or continue reviewing parts in the table and the schematic.