Final Project: Electric Rickshaw modelling

Global efforts towards minimizing greenhouse gas emissions are required to reduce the environmental issues caused by conventional combustion engine vehicles. Alternate clean and green modes of transportation such as electric vehicles are required in place of conventional vehicles. As a cheaper version of electric vehicle, electric rickshaws (popularly known as E-rickshaws or tuk-tuks) are most popular in India. This work deals with the modeling of popular e-rickshaws in MATLAB/Simulink. Software simulations are much helpful for quickly analyzing the distinct features of the electric vehicle, such as aerodynamic design, battery energy density, motor output, curb weight, etc and to visualize the effects on its performance due to variation in various parameters.

Mahindra Treo Specification

Block Diagram of EV Powertrain

Simulink Model for E Rikshaw

Building the Electric Vehicle body step by step

Subsytem

1.tire

Represents a model of a tire parameterized with static and kinetic friction coefficients. When the static friction limit is exceeded, the tire loses traction and begins to slip. The kinetic friction coefficient determines the ability of the tire to transmit torque when slipping. The kinetic friction coefficient is fixed or a function of the current slip. The tire regains traction when the magnitude of the relative velocity between the tire and ground is less than the traction velocity tolerance parameter.

Connection A is the mechanical rotational conserving port for the wheel axle. Connection H is the mechanical translational conserving port for the wheel hub through which the thrust developed by the tire is applied to the vehicle. Connection N is a physical signal input port that applies the normal force acting on the tire. The force is considered positive if it acts downwards. Connection S is a physical signal output port that reports the tire slip. Optionally expose physical signal port M by setting Friction model to Physical signal friction coefficients. Physical signal port M accepts a two element vector corresponding to the static and kinetic friction coefficients.

Simple Gear

Vehicle Body

The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. The vehicle can have the same or a different number of wheels on each axle. Optionally include pitch and suspension dynamics or additional variable mass and inertia. The vehicle does not move vertically relative to the ground.

Connection H is the mechanical translational conserving port associated with the horizontal motion of the vehicle body. The resulting traction motion developed by tires should be connected to this port. Connections V, NF, and NR are physical signal output ports for vehicle velocity and front and rear normal wheel forces, respectively. Wheel forces are considered positive if acting downwards. Connections W and beta are physical signal input ports corresponding to headwind speed and road inclination angle, respectively. If variable mass is modeled, the physical signal input ports CG and M are exposed. CG accepts a two- element vector representing the x and y distance offsets from vehicle CG to additional load mass CG. M represents the additional mass. If both variable mass and pitch dynamics are included, the physical signal port J accepts the inertia of the additional mass about its own CG.

Drag

DC Motor

This block represents the electrical and torque characteristics of a DC motor.

The block assumes that no electromagnetic energy is lost, and hence the back-emf and torque constants have the same numerical value when in SI units. Motor parameters can either be specified directly, or derived from no-load speed and stall torque. If no information is available on armature inductance, this parameter can be set to some small non-zero value.

When a positive current flows from the electrical + to - ports, a positive torque acts from the mechanical C to R ports. Motor torque direction can be changed by altering the sign of the back-emf or torque constants.

H- Bridge

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.

Controlled Voltage Source

The block represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current passing through it. The output voltage is V = Vs, where Vs is the numerical value presented at the physical signal port.

Solver Configuration

Temperature Calculation

This sytem is created to change the temperature of converter and DC motor.The temperature sensor is created to the thermal port of DC motor and H bridge converter. The output of this sensor is given to PS to simulink converter and then to bus creator follwed by temperature display.

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.

Bus creator

Driver Control System

A parametric longitudinal speed tracking controller for generating normalized acceleration and braking commands based on reference and feedback velocities.

Use the external actions to input signals that can disable, hold, or override the closed-loop commands determined by the block. The block uses this priority for the input commands: disable, hold, override.

Input port

Velocity Reference- Input reference voltage

Velfdbk- Velocity feedback for smooth functioning.

Grade- input port associated with inclination

BAttery Subsytem

Battery

The SOC of a battery is a combination of voltage, charge/discharge current and internal resistance parameters to estimate its size. These parameters are also affected by a variety of uncertainties such as battery aging, temperature changes and usage status.

State of charge (SoC) is the level of charge of an electric battery relative to its capacity. The units of SoC are percentage points (0% = empty; 100% = full). An alternative form of the same measure is the depth of discharge (DoD), the inverse of SoC (100% = empty; 0% = full). SoC is normally used when discussing the current state of a battery in use, while DoD is most often seen when discussing the lifetime of the battery after repeated use.

Knowing the amount of energy left in a battery compared with the energy it had when it was full gives the user an indication of how much longer a battery will continue to perform before it needs recharging. It is a measure of the short term capability of the battery. Using the analogy of a fuel tank in a car, State of Charge (SOC) estimation is often called the "Gas Gauge" or "Fuel Gauge" function.

Controlled Current Source

The block represents an ideal current source that is powerful enough to maintain the specified current through it regardless of the voltage across it. The output current is I = Is, where Is is the numerical value presented at the physical signal port

Rate Transition

Gain

Discrete Time Integrator

Electrical Reference

electrical reference port. A model must contain at least one electrical reference port (electrical ground).

Drive Cycle

The Simulation is run for 2474 seconds

Actual vs Reference speed of E rikshaw

SoC of Battery

Temperature change in converter and Motor

Drive cycle Condition

Wide open Throttle

Custom DAta set

Acceleration Command from drver block

Ref vs Actual speed

Temperature

SoC of BAttery

There is variation in the state of charge of battery . It keeps decreasing to 96.2% and due to regenerative braking it again increases to 96.5 %

Conclusion

Here two drive cycle is taken for consideration FTP75 and WOT and other all specification were kept same like motor ratings, convereter ratings, bus voltage etc.

Few variation was found in actual speed and reference speed.

parameters can be improved by using detailed simulation rather than averaged.

optimization of battery pack can be done improved milage during peak condition.

Actual PID controller can be used rather than PWM generator block.

BLDC motor can be used for more better efficiency,