Final Project: Electric Rickshaw modelling

ans-

• 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.
• These rickshaws have an M.S(Mild Steel) tubular chassis, consisting of three wheels with a differential mechanism at the rear wheels. The motor is a brushless DC motor manufactured mostly in India and China. The electrical system used in the Indian version is 48V and in Bangladesh is 60V. The body design from the most popular Chinese version is of very thin iron or aluminum sheets. Vehicles made in fiber are also popular because of their strength and durability, resulting in low maintenance, especially in India.
• The body design is varied from load carriers, passenger vehicles with no roof, to full body with windshield for drivers comfort. It consists of a controller unit.

General detail of E-Rickshaw -

• Battery Type Lithium Ion 330 V 75 Ah
• Vehicle kerb weight 260 kgs
• Load capacity 340 kgs
• Vehicle speed 7 kmph
• Driving range 140 km (160 Ah)
• No of wheels per axel 2
• Frontal Area 91m
• Drag coefficient 5
• Wheel radius 306m
• Vertical load 3000 N
• Nominal Voltage 330 V
• Rated Capacity 75 Ah
• Initial SOC % 100
• Internal Resistance 5 ohm

1) vehicle body subsystem-

• Motor will produce the rotational output which will give to the vehicle body and transmission system. The rotational output is taken by the gear system here to maintain the constant speed throughout the transmission without any loss in speed from the motor to tires.
• Below is a diagram that is how it is how it inside the vehicle body and transmission system and in the main design, it is referred just only as a transmission system.
• Here I created a Rear wheel drive transmission system.
• The vehicle body has an H-Hub, S- Tire slip, N- Normal force, A- axel connection, wind velocity, inclination angle. The tires hub is connected as a common node to the vehicle body.
• The vehicle body wind velocity is connected to a constant block and the beta-inclination angle is connected to another constant block where we can assign wind velocity and inclination angle as per requirement. Velocity is the output port where we can get at which speed the vehicle is moving. The velocity is taken out to the get the distance travelled and state of charge.

    TYRES-

• Represents the longitudinal behavior of a highway tire characterized by the tire Magic Formula. The block is built from Tire-Road Interaction (Magic Formula) and Simscape Foundation Library Wheel and Axle blocks. Optionally, the effects of tire inertia, stiffness, and damping can be included.

GEAR-

Represents a fixed-ratio gear or gear box. No inertia or compliance is modeled in this block. You can optionally include gear

VEHICLE BODY-

• This block basically represents a two-axle vehicle body in longitudinal motion. The block accounts for - body mass, aerodynamic drag, road incline, weight distribution between axles due to acceleration road profile.
• Here, the connection H is the mechanical translational conserving port hub. NF & NR correspond to the output ports for nomral reaction forces on front axle and rear axle wheels respectively.
• Connection V represents the actual output translational velocity of the vehicle.

2)motor and power converter subsystem model-

H-BRIDGE-

• 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.

DC MOTOR-

• This block represents the electrical and torque characteristics of a DC motor includes Thermal port to sence the temperature of 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 flow 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.
• TheMotor controller will get input from the longitudinal driver. Its tasks are to control the speed of the motor and drive according to the input of the driver. Majorly motor controlled we designed had two main parts named PWM voltage generator and H-Bridge.

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.
• 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. Select Simulation mode as Averaged.

TEMPERATURE SENSOR-

• Temperature Sensor is used to mesure the temperature of H-Bridge and Motor.
• 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.

3)battery subsystem-

• The battery is required to power the controller and motor. The controller uses the battery power according to produce the input given by the motor to obtain maximum speed. The battery is also used to power every electrical component in the vehicle.
• The battery has a positive and negative terminal which is given the voltage-controlled source where the battery consumption is controlled by the motor controller and then it is given to the SOC block.

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.

powergui-

• Continuous, which uses a variable-step solver from Simulink
• Discretization of the electrical system for a solution at fixed time steps
• Continuous or discrete phasor solution

4)longituditional driver-

• It is a parametric longitudinal speed tracking controller for generating normalized Acceleration and Braking commands based on reference and feedback velocities.
• The VelFdbk port corresponds to the feedback velocity. The actual velocity output given by the vehicle body is connected here. By comparing the actual (feedback) velocity with the reference velocity, the driver block generates acceleration and braking signals in order to minimise the error between the two concerned velocities.
• Grade corresponds to the grade angle. For this simulation, no inclination is considered and hence, a constant block with value 1 is connected.

5)Reference velocity-

• Drive cycle is assumed as the driver's input of a vehicle, it replaced how a driver will drive a vehicle. Here I have used three drive cycles which is used to test the vehicle performances. These drive cycle will have high speed, low speed, braking conditions in it.

final simulation of electric rikshaw-

• Initially the current flows to DC Motor from the battery through the DC-DC power converter to drive the motor. The required voltage will be controlled in the controller. The Controller will follow the given drive cycle reference and run the motor in the required rpm.
• Then the motor power is transmitted to the wheels of a vehicle through the gear box. and the controller will take the vehicle speed and compare and controlled.

output-

1)FOR FTP-

2) FOR WOT-

FOR

CONCLUSION-

• Here I have compromised with the temperature of Motor and controller to achieve vehicle speed is near to reference speeds. Since I haven’t used any cooling system in the model. In the real time application, the motor temperature is less than 100 C.
• In the real time application, the motor, battery & controller temperature is controlled by air cooling. Hence, the temperature of this components is not increased to this extent.
• Hence, Created a MATLAB model of an Electric Rickshaw (three wheel passenger vehicle) by using Li-ion battery, PM Brushed DC Motor.
• Detremined the variations of Temperature of Motor and controller, SoC% and Energy consumed by the by vehicle for all the three Reference Drive cycles