Project-1: Modelling an electric Car with Li-ion battery

PROJECT 1:

MODELLING AN ELECTRIC CAR WITH LI-ION BATTERY AND PID CONTROLLER:

SIMULINK MODEL:

• The model of electric vehicle
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• The Li-ion battery block
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• PID controller block
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• The DC motor drive block
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• The vehicle body block
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REPORT:

• The FTP75 drive cycle choosen from the Drive cycle source block
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• The reference speed is connected is sum where it subtracted by speed of the vehicle togenerate error signal
• This error signal is connected to PID controller block
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• The PID gain values obtained by PID tuner tool by linearisation method as follows
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• The gain values obtained by adjusting the step response of plant
• For acceleration command,The PID controller output given to saturation block
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• An then connected to tranfer function block used to suppress the algebraic loop errors
• The final output given to PWM input through controlled voltage source
• For decceleration command.PID output given to saturation block
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• An absolute block used to make the signal postitve and given to transfer function block
• The decceleration command given to the BRK port of H-bridge converter
• The motor drive block contains PWM controller,H-bridge converter and DCmotor
• The PWM controller parameters choosen as folllows
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• The acceleration command from the driver block is connected to the ref+ port of PWM controller through a controlled voltage source
• The ref- port connected to the electrical reference
• The output voltage of PWM controller set to 50v in order to achieve the required output
• Thi output signal given to the input of H-bridge converter
• The H-bridge converter from simscape library used and parameters choosen a follows
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• The output voltage set to 300v according to the motor voltage
• The PWM input port receives the output voltage of PWM controller
• The REF port connected to the REF port of PWM controller and grounded
• The REV port connected to the electrical reference
• The BRK port get the input decceleration command from the driver block through a controlled voltage source which act as regeneratve braking
• The output of the H-bridge converter is connected to the DC motor through a current sensor
• The output from the current sensor is given to the battery block
• The DC motor model from simscape library used and parameters choosen as follows
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• Permanent magnet field DC motor type selected
• The rated load set to 50kw and rated voltage set to 300v
• The mechanical output of the DC motor connected through Rear wheel axle through a gear model
• And also it grounded using mechanical rotational reference block
• The simple gear block parameterss choosen as follows
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• The wheel blocks parameters choosen as follows
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• The vehicle body block parameters choosen as follows
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• The vehicle body hub port connected to the hub port of all rear and front wheels
• Rear wheel axle port and N port which is force signal connected and same done for front wheels as well
• The force to rear wheel applied by the NR port of vehicle body
• The force to front wheel applied by NF port ofvehicle body
• The wind velocity port is connected through constant block through goto &from block
• The output is velocity converted from physical signal to simulink signal using PS-Simulink converter
• The output velocity feeded back to the driver block
• The battery used in this model is LI-ION battery ,the battery parameters choosen according to the motor
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• The motor current is connected to the battery through controlled current source
• The state of charge and battery current is plotted in a scope
• The distance travelled by the electric vehicle calculated as
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• All the ouputs SOC of battery ,reference speed ,actual speed and distance connected to the scope block
• The model simulated for 2474 seconds same time as of the FTP75 drive cycle
• The output results plotted

RESULT:

• The FTP75 driving cycle used as reference iss hown below
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• The acceleration command from the PID controller is shown below
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• The decceleration command from the PID controller is shown below
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• The speed of the vehicle with repect to the reference speed is shown below
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• Graph 1:It represents the actual speed of the vehicle and the reference speed
• It observed that the actual speed of the vehicle is following the reference speed
• But due to inertia of the vehicle ,the decceleration takes more time compared to reference
• A better result can be obatined by fine tuning the controller
• Graph 2:It represents the distance travelled by the vehicle for the given drive cycle
• It observed that vehicle travelled almost 5km for the given drive cycle
• The battery current and state of charge is shown below
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• Graph 1: It represents the State of charge of the battery of electric vehicle for the given drive cycle
• Its oberved that almost 97% of charge remains in the battery after completing the drive cycle
• Graph 2: The current polarity changes as per the acceleration and decceleration commands

CONCLUSION:

• Designed model of an electric car which uses the lithium-ion battery
• The PID controller designed for the model and generated accelearation and decceleration command
• The model simulated for a defined drive cycle and analysed the vehicle performance