Week 5 Battery characteristics using drive cycle
Battery Characteristics using a Drive Cycle
Aim:
* To Visualize the behaviour of the Electric vehicle's battery by configuring it to operate on a Actual UDDS Drive cycle.
* To study the effect of UDDS Cycle on the electric vehicle battery's characteristics on the areas of,
1. Voltage
2. Current
3. State of charge
Drive cycle:
* Drive cycle is a test cycle for a vehicle with various input conditions which will be done for all the newly produced and about to launch vehicles.
* This Drive cycle is done to Test the Emmision , fuel efficiency , with various input of throttle and various hill climbing angles in case of an IC engine powered vehicle.
* In case of an Electric vehicle the test is done with various input of throttle and various hill climbing angles to analyze Power efficiency , Range of the vehicle and the State of charge of the battery that is left after running the test.
* In this simulation we are using the UDDS Drive cycle to know the electric vehicle's, battery's behaviour.
UDDS Drive cycle:
* UDDS stands for Urban Dynamometer Driving Schedule.
* The following are basic parameters of the cycle:
(i) Duration: 1060 seconds
(ii) Distance: 5.55 miles = 8.9 km
(iii) Average speed: 18.86 mi/h = 30.4 km/h
(iv) Maximum speed: 58 mi/h = 93.3 km/h
Simulating the battery behaviuor for UDDS Drive cycle:
* To know the effects of a electric vehicle's battery characteristics like, voltage , current and state of charge we need to do the simulation through the steps given below,
1. Signal Builder block
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2. Controlled current source
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3. Battery configuration
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4. Bus selector block
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5. Scope results
1. Signal Builder block:
* Our Aim is to determine the battery characteristics for a drive cycle, so that the vehicle's parameters such as range, performance can be know for that particular battery's usage and if there are any room for improvements it can also be done for the battery.
* For doing this we need to input the UDDS Drive cycle data, but the drive cycle data will be in speed vs time format. To relate this with the battery we are using the Signal Builder block.
* The signal builder block can only take the curent values as a input so the respective drive cycle data is changed to the current values and then fed as a input to the signal builder block.
* The above figure shows the value of the current with respect to time.
2. Controlled current source:
* As the electric vehicle's battery is a limited current source we need to simulate considering this.
* The current signals from the Signal builder block is related to a limited source current signal using this controlled current source block.
* Thit is converting the drivecycle equivalent current to a controlled current source signal so that this can be connected to a battery for the current draw as per the drive cycle requirements.
3. Generic Battery:
* The Generic battery model is a battery model available in Simscape / Electrical / Specialized Power Systems / Electric Drives / Extra Sources.
* This battery model can be configured as per our requirements to know the battery's behaviour.
* This battery model has two terminals at the right output side and a 'M' current measurement output signal on the other side.
* The current signals from the controlled current block is connected to the terminals of the battery as a battery's input signal so that the battery can supply the current accordingly.
* For this simulation we have configured our battery with the above mentioned battery parameters.
4. Bus selector:
* This block accepts a bus as input which can be created from a Bus Creator, Bus Selector or a block that defines its output using a bus object
* To know the behaviour of the battery in areas like Current, Voltage , and Stae of charge a bus selector block is attached to the 'M' current measurement output signal.
5. Scope result:
* To visualize the effect of the drive cycle on the battery's characteristics, it is connected to a Scope results block.
Simulation & Results:
* By connecting the above listed blocks in this way we are ready with the simulation model to find the electric vehicle's battery characteristics while running on a UDDS Drive cycle.
* The overall time for the simulation is as per the UDDS Drive cycle as 1371 Seconds and the simulation is ran to observe the effects on the battery through a plot.
* The result plot obtained shows the battery's behaviour in the areas of state of charge, Current, and Voltage.
State of charge:
* The first plot shows the state of charge of the battery for running over the UDDS Drive cycle.
* The charge intially from 100 % dropped to 90.7 % at the end of the drive cycle which is at 1371 seconds.
* The loss of charge from the battery is roughly around 9% from its overall capacity in driving the vehicle for a distance of 8.9 Km.
* Due to speed changes and braking in the drive cycle we can also observe the charging taken place at some time period because of regenerative braking.
* Thus the battery's state of charge is observed for UDDS Drive cycle in the simulation.
Voltage:
* The second plot shows the voltage behaviour of the battery.
* The voltage at the start of the drive cycle at time 0 is 4.32V and it came down to 4.21V at the end of the simulation which is at 1371 seconds.
* Due to the braking in the drive cycle, we can observe the voltage rises at some instance of the simulation.
Current:
* The third plot shows the Current behaviour of the battery for UDDS Drive cycle.
* The negative current indicates the charging of current in the battery and positive current indicates the discharging from the battery, due to the braking in the drive cycle.
* The maximum discharge current is - 3.98A and the maximum charging current at one time period is 7.83A.
* The current fluctuates in the battery as per the driving cycle.
* To predict the exact battery behaviours and range of the vehicle we can configure the battery with actual battery parameters in the above simulation.
* Thus the electric vehicles's battery characteristics are observed while making it to run over the UDDS Drive cycle from the above simulation.