Final Project: Electric Rickshaw modelling

AIM:- Create a detailed MATLAB model of an electric rickshaw (three-wheel passenger vehicle) as per details below:

• Rear wheels driven by PM brushed type motor
• Assume efficiency points of motor controller and motor
• Make an excel sheet of all input and assumed data
• Results: For any three standard driving cycles show energy consumption, temperature rise of motor and controller for 100 km constant speed driving at 45 kmph.

INTRODUCTION

     Electric E-Rickshaw is also known as electric tuk-tuk, e-rickshaw and auto which are going more popular after 2018 in Indian    market. This E-rickshaw is best alternative of petrol/ CNG auto rickshaw and human or horse pulled rickshaws because of their    low fuel cost, zero emissions and less human efforts.

     The electrical system used in Indian version is 48VDC can run 90– 100 km/full charge, top speed 25 km/hour and this            electric motor power ranging from 650-1400 Watts; the battery takes 8–10 hrs to become fully charged. Basic seating capacity    is driver plus 4 passenger total 5 persons.

     Here basically, e-rickshaw is designed in CREO and MATLAB Simulink. In the designed electric rickshaw main blocks are            battery, drive cycle, controlled, DC Motor, Vehicle body and transmission system. Drive cycle is the input of human effort that      how he is going to drive his actual cycle. We can use drive cycle like FTP75, WOT or by using Excel.

     The main objective of this project is to obtain speed by driver, to estimate the temperature of motor and controller, to               estimate the state of charge (SOC) and distance travel by the vehicle. There is a SOC block that will estimate the state of           charge of battery, distance is calculated by speed and time parameter for all the three Drive cycle.

General detail of E-Rickshaw

• Battery Type Lithium Ion 60.8 V 160 Ah
• Vehicle kerb weight 400 kgs
• Load capacity 320 kgs
• Vehicle speed 7 kmph
• Driving range 140 km (160 Ah)
• No of wheels per axel 2
• Frontal Area 91m²
• Drag coefficient 5
• Wheel radius 306m
• Vertical load 3000 N
• Nominal Voltage 8 V
• Rated Capacity 160 Ah
• Initial SOC 0
• Internal Resistance 5 ohm

System Confrigation :-

Vehicle Subsystem :-

 Vehicle Body :-

• represents a two-axle vehicle body in motion.
• accounts for body mass, aerodynamic drag, grade,externally-defined mass and center of gravity of the vehicle body.

   Input Ports:

• W - Wind Velocity in m/s
• beta - Grade angle in radians

   Output Ports:

• V - Velocity in m/s
• NR - Normal force on Rear Axle  (N)
• NF - Normal Force on Front Axle (N)

Vehicle Body Parameters:

• Vehicle body mass, Centre of gravity distance values and aerodynamic drag variables are modified.
• Pitch dynamics are kept ON with other variable values as default values.

Tire :-

• Used to model a tire with longitudinal behavior given by equation based on four fitting coefficients.
• The block can model tire dynamics under constant or variable contact surface conditions.

   Input Port:

• N - Normal force acting on tire, positive when force is acting downwards/towards the contact surface,

   Output Port:

• S -  Slip value relative to tire and surface of contact.

   Conserving Ports:

• H - represents wheel hub which transmits thrust generated by the wheel to the body of the vehicle.
• A - represents axle on which the tires are mounted.

Gear Box :-

 

• A simple gear block is used to connect the motor to the rear axle of the vehicle.
• It represents the gearbox which connects the input shaft to the base gear and ouput from the foller gear.

Conserving Ports :-

• B - port associated with input shaft (motor shaft)
• F - port associated with ouput shaft (axle / differential)

Simple Gear Parameters :-

• Gear ratio and output direction is modified.
• Meshing loss is kept constant and gear is having a constant efficiency throughout the simulation.
• Viscous losses and faluts are kept at default conditions.

INERTIA

This block generally represents the mechanical rotational element.

Where,

         T = Inertia torque  J = Inertia  Ω = Angular velocity  T = Time

MOTOR SUBSYSTEM :-

Dc Motor :-

This is the DC Motor which would give the rotational power to the wheels and become the sole power generation source. 

The DC Motors terminals are connected as mentioned below,

+ = Electrical signal to the motor Positive Terminal

- = Electrical signal to the motor Negative Terminal

R = Casing of the Motor connected with the Mechanical Rotational Reference Block

C = Rotor Case connected to the Mechanical Rotational reference

The parameter considered are, The Armature inductance is as default,  varied the changes in the No-Load Speed @ 5000 rpm, the rated speed @ 1500 rpm, the Rated Load at 6.6 kW, and the Rated DC Supply Voltage @ 60.8 V. All other parameters are as default.

Ideal Rotational Motion Sensor :-

This block measures angular velocity or angle in a mechanical rotational network. The sensor is ideal since it does not account for inertia, friction, delays, energy consumption and so on.

The physical signal ports W and A report the angular velocity and angle, respectively, of port R relative to port C. The measured angular velocity is positive when the angular velocity at port R is greater than the angular velocity at port C

Temperature Sensor  :-

This block measures temperature in a thermal network. There is no heat flow through the sensor. The physical signal port T reports the temperature difference across the sensor. The measurement is positive when the temperature at port A is greater than the temperature at port B

Control Subsystem :-

H-Bridge :-

The H-Bridge helps in controlling the power that is input according to the requirement. The output provided are converted voltage as per the controlled parameters.

      This block represents an H-bridge motor drive. The block can be driven by the Controlled PWM Voltage block in PWM or Averaged mode. In PWM mode, the motor is powered if the PWM port voltage is above the Enable threshold voltage. In Averaged mode, the PWM port voltage divided by the PWM signal amplitude parameter defines the ratio of the on-time to the PWM period. Using this ratio and assumptions about the load, the block applies an average voltage to the load that achieves the correct average load current. The Simulation mode parameter value must be the same for the Controlled PWM Voltage and H-Bridge blocks.

      If the REV port voltage is greater than the Reverse threshold voltage, then the output voltage polarity is reversed. If the BRK port voltage is greater than the Braking threshold voltage, then the output terminals are short circuited via one bridge arm in series with the parallel combination of a second bridge arm and a freewheeling diode. Voltages at ports PWM, REV and BRK are defined relative to the REF port.

If exposing the power supply connections, the block only supports PWM mode.

CONTROLLED PWM VOLTAGE :-

   This block creates a Pulse-Width Modulated (PWM) voltage across the PWM and REF ports. The output voltage is zero when the pulse is low, and is equal to the Output voltage amplitude parameter when high. Duty cycle is set by the input value. Right-click the block and select Simscape->Block choices to switch between electrical +ref/-ref ports and PS input u to specify the input value.At time zero, the pulse is initialized as high unless the duty cycle is set to zero or the Pulse delay time is greater than zero.

The Simulation mode can be set to PWM or Averaged. In PWM mode, the output is a PWM signal. In Averaged mode, the output is constant with value equal to the averaged PWM signal.

Battery Subsystem :-

CONFIGURATION BATTERY AND SOC :-

In given block there are some changes to configure the Lithium battery.

Basically, in battery a special change has done and i.e.

Under Parameter > Lithium-Ion (Change the following data)

• Nominal Voltage = 60.8 (V)
• Rated Capacity = 160 (Ah)

Under Discharge (Change the following data)

• Maximum Capacity = 160 (Ah)
• Cut-off Voltage = 51.6 (V)
• Fully Charged Voltage = 80.0823 (V)
• Nominal Discharge Current = 69.5652 (A)
• Internal Resistance = 0.0043 (Ohms)
• Capacity at Nominal Voltage = 144.69 (Ah)

So, at Discharge rate of [6.5 13 32.5] the plot will be Done.

Controlled Current Source

The Controlled Current Source block converts the Simulink input signal into an equivalent current source. The generated current is driven by the input signal of the block. The positive current direction is as shown by the arrow in the block icon.

We can initialize the Controlled Current Source block with a specific AC or DC current. If we want to start the simulation in steady state, the block input must be connected to a signal starting as a sinusoidal or DC waveform corresponding to the initial values.

• Double click controlled current source and from drop down menu of measurement select current.
• Signal output will connect with scope by adding current signal to it.
• (+) terminal will connect with battery (-) terminal.

Battery

The Battery block implements a generic dynamic model that represents most popular types of rechargeable batteries.

• In battery setup just do the above changes which I highlighted above.
• Just connect ambient temperature with Ta input of battery.
• “M” will be connected with BUS selector lock.

BUS Selector

The Bus Selector block outputs the signals you select from the input bus. The block can output the selected elements separately or in a new virtual bus.

• Here just we have mange the output and connect with different Scope Block.

Driver Model :-

The Driver Model has the Input and Output Ports which are connected to the following, 

Velocity Reference - Multi Port switch

Velocity Feedback - Distance Calculation 

Grade - Constant 0 

Info - Terminated Block Connected

Acceleration Command -  Controlled PWM Source

Deceleration Command - Brake in H-Bridge to maintain the speed according to the Drive Cycle.

Multi Port Switch

     Pass through the input signals corresponding to the truncated value of the first input. The inputs are numbered top to       bottom (or left to right). The first input port is the control port. The other input ports are data ports.

Drive Cycle :- 

1. FTP75 Drive Cycle

 

2. Constant Speed 45Kmph For 100 KM

3. Wide Open Throttle ( WOT)

Result /Output :-

Case 1. Using FTP75 Drive Cycle  :-

starting with the Drive Cycle,let consider a  FTP75 Drive Cycle for the operation of the Cycle in which the test duration would be 2474 seconds.

The model with the above details is simulated and the results are as follows :-

1.The Velocity Feedback and the Drive Cycle Source :-

Battery State of charge (SOC) 74.65 %

Motor Tempeature :-

Controller Tempeature :-

Motor RPM :-

Average Power :-

Case 2  Constant speed 45Kmph For 100Km

The Velocity Feedback and Source :-

Soc :- Battery Soc Remaing 0%

Controller Temperature :-

Motor Tempeature :-

Motor RPM :-

Power :- 

Case 3

Using Wide Open Throtale :-

Output :-

Soc Of Battery:-  99.24%

Controller Tempeature:-

Motor Tempeature :-

Motor RPM :-

Power :-

Conclusion

• If we compare with real model then the motor, battery and controller temperature is controlled by using air cooling system because it is not high.
• The MATLAB model of e-rickshaw is created by using Li-ion Battery 60.8 V 160Ah and PM Brushed DC Motor.

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