A Battery Management System (BMS) manages Lithium-Ion (Li-ion) batteries in a storage system for pulsed power weapons aboard Naval vessels. The system charges the batteries with a buck converter and uses analog equipment to measure signals. It then digitally converts signals for transmittal to a Field-Programmable Gate Array (FPGA).
Software processing controls the voltage and current directed to the batteries to maintain proper control and maintenance of the batteries. The BMS’s design can manage the charge and discharge of four Li-ion batteries. The BMS is a complex system with many components that work together to accomplish its goal to manage Li-ion batteries.
The BMS system consists of a transformer rectifier, a buck converter, an FPGA controller, a data acquisition system, and Li-ion batteries. The components that handle the current signal are a Hall Effect Sensor, a buffer/amplifier, an analog-to-digital converter (ADC), and the FPGA. The components that handle the voltage signal are the voltage-to-frequency converter, an optocoupler for galvanic isolation, a computer model for processing the output from the voltage-to-frequency converter, and the FPGA.
At its core, the BMS is made of four FPGA-controlled buck converters -- one for each battery. Additionally, each converter contains sensors and a control system to allow for digital control of the buck converter by the FPGA. The FPGA varies the buck converter’s duty cycle to control the battery current.
The BMS is a complex system with many components that work together to accomplish its goal to manage Li-ion batteries. In order to control the charge delivered to Li-ion batteries, the cell current and voltage must be closely monitored. These two sensors are critical components of the BMS operation.
Tests showed that, when properly calibrated, the BMS accurately measures and transmits voltage data to the FPGA for processing and control.