All Courses
All Courses
Courses by Software
Courses by Semester
Courses by Domain
Tool-focused Courses
Machine learning
POPULAR COURSES
Success Stories
Aim1: Simulate the 3 test cases from harness dashboard and write a detailed report on the results Solution: Battery Management System (BMS) – A battery management system is the electronic system that manages the rechargeable battery, such as by protecting the battery from operating outside its safe operating area, monitoring…
Sanket Nehete
updated on 23 Nov 2021
Aim1:
Solution:
Battery Management System (BMS) –
A battery management system is the electronic system that manages the rechargeable battery, such as by protecting the battery from operating outside its safe operating area, monitoring its state, calculating secondary data, controlling its environment, authenticating it or balancing it.
Function of BMS –
Monitor:
A BMS may monitor the state of the battery as represented by various items such as:
Fuel gauge/ Current measurements:
The fuel gauge functional block keeps track of the charge entering and existing the battery pack. A charge is the product of current and time. There are several different techniques that can be used when designing the fuel gauge. A current sense amplifier and an MCU with an integrated low-resolution ADC is one method of measuring the current. The current sense amplifier operates in high common-mode environments and amplifies the signal, enabling higher resolution measurements. This design technique sacrifices dynamic range. Other techniques are to use a high-resolution ADC or to purchase a costly fuel gauge IC. Understanding the behaviour of the load in terms of current consumption versus time determines the best type of fuel gauge design.
Cell voltage and maximizing battery lifetime:
Monitoring the cell voltage of each cell within a battery pack is essential in determining its overall health. All cells have an operating voltage window that charging and discharging should occur to ensue proper operation and battery life. If an application is using a battery with lithium chemistry, the operating voltage typically ranges between 2.5V and 4.2V. the voltage range is chemistry dependent. Operating the battery outside the voltage range significantly reduces the lifetime of the cell and can render the cell useless.
Temperature Monitoring:
Temperature sensors monitor each cell for energy system applications or a grouping of cells for smaller and more portable applications. Thermistors powered by an internal ADC voltage reference are commonly used to monitor each circuits temperature. The internal voltage reference is used to reduce inaccuracies of the temperature reading versus environmental temperature changes.
State Machine or Algorithms:
Most battery management systems require an MCU or an FPGA to manage information from the sensing circuitry and to make decisions with the received information. In a select few offerings, such as Intersil’s ISL94203, the algorithm is encoded, with some programmability, digitally enabling a standalone solution with one chip. Standalone solutions are also valuable when mated to an MCU because the state machine within the standalone can be used to free up MCU clock cycles and memory space.
Other BMS functions:
Other BMS functional blocks include battery authentication, a real-time clock, memory and daisy chain. The real-time clock and memory are used for black-box applications where the RTC is used for a timestamp and memory are used for storing data, allowing the user to know the battery pack’s behaviour prior to catastrophic event. The battery authentication block prevents the BMS electronics from being connected to a third-party battery pack. The voltage reference/regulator is used to power peripheral circuitry around the BMS system. Finally, daisy chain circuitry is used to simplify the connection between stacked devices. The daisy chain block replaces the need for optical couplers or other level shifting circuitry.
BMS components –
MATLAB model of BMS:
This model has two main blocks BMS ECU and PLANT block. The plant represents a battery and ECU represents software in MATLAB and Simulink environment.
Plant Subsystem:
This plant subsystem consists of 3 blocks battery packs, pre charger circuit and charger block. The pre charger circuit is connected to the charger and load as the motor which is connected through the inverter and charger wires to the precharge block. Charger and load subsystem consists of charger and motor block which are connected in a parallel configuration.
Charge and load subsystem:
This subsystem represents DC driver load. This implement the battery current from the drive cycle this is virtually creating the current draw. The current source depends on the battery current drive cycle block. This will charge and discharge the battery block.
This will charge the battery in the reverse direction. Here the equation represents the charging of the battery in the continuous state. This is a continuous charging source.
Battery Pack Subsystem:
This represents a cell module block in which we have two sets one is 6 cell and another is 16 cell modules. From cell 1 module block, we get 6 cells connected in series with the temperature port is enabled to calculate the temperature of each cell and gives to the multiplexer through which it will be given to the BMS circuit. Connection 1 port gives us the battery positive and 7 connection port gives us the battery negative pack. We can observe here that the current sensor block is been connected in series to the negative port which will give output as pack current value.
Precharge circuit subsystem:
Basically, the precharge circuit connects and disconnects the pre-charge resistor for the inverter of charger. Here two resistors are used as the current direction is reversed in the circuit. Precharge relay commands are the input signals which are used to control the contactor in the circuit which will on and off the circuit.
Testing harness dashboard model:
This dashboard will show us the current situation of the BMS and the faults in the system. If there is green light glowing then there are no faults or if a red bulb glows then there is some fault in the system. We can also observe BMS status on the left-hand side knob like a block in which it will show whether the BMS is charging or driving or in a balanced state.
BMS ECU subsystems:
Charging and Discharging block:
In this block current and power, limit is controlled by two block one is for the charge current limit another is the discharge current limit. Based on 6 number of cells connected in series and minimum or maximum cell voltage current or temperature the limits are calculated for discharge and charge. Below is the equation representation in blocks format for discharge and charging calculations.
Discharge current calculation subsystem:
Charge current calculation subsystem:
These all are the algorithms that are going to run inside the state machine block. There will be a blue indication while block or which algorithms are running. All cell voltage cell current and also temperature-related calculation algorithms are going to run inside the state machine block. The output of the state machine is given to the BMS dashboard. There are 3 states at which we have to run the MATLAB BMS model.
Results:
Input Test signal-1:
Here initially battery is 100% charged and the battery is in the driving condition for 3000sec and then it goes under standby condition for balancing the circuits it is for 1000sec and then after standby, there is a charging period where SOC of the battery is raised to 100% this process takes 5000sec and the ageing same procedure continues.
Output:
Here in the dashboard, we can observe that all green LED’s are glowing which means there is no fault in the system.
Input test signal-2:
Here we can observe on the dashboard that 2 led are glowing as red because there are some faults in the battery pack system.
Input test signal-3:
Output:
Here in the dashboard, we can observe that all the green LED’s are glowing which means there is no fault in the system.
Result:
Aim2:
What is coulomb counting? Refer to the above model and explain how BMS implements coulomb for SOC estimation?
Solution:
Coulomb counting is a technique used to track State of Charge of a battery pack. It works by integrating the active flowing current over time to derive the total sum of energy entering or leaving the battery pack. This produces a capacity that is typically measured in Amp-hours.
As we observed the SOC of the cells were different this is due to the different calculation which is done in SOC simulation and balancing block.
Coulomb counting equation subsystem:
Leave a comment
Thanks for choosing to leave a comment. Please keep in mind that all the comments are moderated as per our comment policy, and your email will not be published for privacy reasons. Please leave a personal & meaningful conversation.
Other comments...
Week 7 State of charge estimation
Aim1: Simulate the 3 test cases from harness dashboard and write a detailed report on the results Solution: Battery Management System (BMS) – A battery management system is the electronic system that manages the rechargeable battery, such as by protecting the battery from operating outside its safe operating area, monitoring…
23 Nov 2021 07:00 AM IST
Project 2-Highway Assistant-Lane Changing Assistant
AIM: To develop an algorithm for one of the features of the Highway Lane Changing Assistance, create a Simulink Data Dictionary for the given signals data lists, develop a model advisor report and generate a C code for it using AUTOSAR coder in SIMULINK Objective: Model development in MATLAB Simulink as per MBD guidelines…
16 Oct 2021 06:49 PM IST
Project 1- Traffic Jam Assistant Feature
Aim: To create a Simulink Data Dictionary, develop an algorithm for one of the features of the Traffic jam Assistance and generate a C code for it using Simulink. Objective: Model Development as per the MBD guidelines Creation of Simulink Data Dictionary Code generation using Embedded Coder Generating Model Advisor Report…
13 Oct 2021 11:22 AM IST
Project 1 (Mini Project on Vehicle Direction Detection
Aim: To make a model for vehicle direction determination and making the sldd file Introduction: Identifying the direction of the vehicle is one of the important & diverse features in Autonomous driving & Advanced Driver Assistance Features. This particular sub-feature of identifying the direction of vehicle…
05 Oct 2021 07:56 AM IST
Related Courses
Skill-Lync offers industry relevant advanced engineering courses for engineering students by partnering with industry experts.
© 2024 Skill-Lync Inc. All Rights Reserved.