Final Project: Electric Rickshaw modelling
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.
(Note- The simulink model file should be compulsorily attached)
ANSWER:
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 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.
Design and Construction :
- 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. They are sold on the basis of voltage supplied and current output, also the number of MOSFET (metal oxide field-effect transistors) used. The battery used is mostly a lead-acid battery with life of 6-12
months. Deep cycle batteries designed for electric vehicles are rarely used. The weight of the electric car has also been a recurring design difficulty in them.
General detail of E-Rickshaw -
- Battery Type Lithium Ion 330 V 75 Ah
- Vehicle kerb weight 260 kgs
- Load capacity 340 kgs
- Vehicle speed 23 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
PROCEDURE :
(1) Vehicle Body Subsystem Model :
- 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 gear output is given to axels of Rear tires, in the circuit it is shown that gear is connected to Rear wheels and front tire is free to rotational motion, thus vehicle moves N is the normal force caused by the tires and it is given to the vehicle body normal force port.
- The vehicle body has an H-Hub, S- Tire slip, N- Normal force, A- axel connection, wind velocity, inclination 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.
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 :
- 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 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 Optionally expose physical signal port M by setting Parameterize by to Physical signal Magic Formula coefficients. Physical signal port M accepts a four element vector corresponding to the B, C, D, and E Magic Formula coefficients.
Gear:
- Represents a fixed-ratio gear or gear No inertia or compliance is modeled in this block. You can optionally include gear
meshing and viscous bearing losses.
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. beta is the road inclination angle & W corresponds to the headwind speed (headwind - direction opposite to that of vehicle). The gross weight is given to be 600
- The geometric parameters of the vehicle are given as -
Motor and power converter sub system:
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
- 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 HBridge
Battery and SOC subsystem:
Bus selector:
Battery:
Lithium Battery:
- The battery has two stage one is charging and another one is discharging state. The battery is of 75Ah
The Nominal voltage of battery is 330 V
Initial SoC is of 100%
The battery as a series internal resistance plus a charge-dependent voltage source defined by :
- where SoC is the state of charge and Vnom is the nominal voltage. Coefficient beta is calculated to satisfy a user-defined data point [AH1,V1].
- 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
Battery State of Charge :
- SoC is the percentage or level of battery presents after certain travel or consumption of battery charge by the
- In the designed vehicle battery charge or SOC is calculated by the giving it to the rate transition and then to gain where 1/(nominal battery capacity) then to a discrete-time integrator and it will get minus from the l as it is considered a 100% of battery and it is multiplied with 100 to get percentage of battery.
- The majority of blocks are simscape blocks where physical to simulink converter is used to convert the physical signal from simscape block to simulink
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.
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. PowerGUI :
The powergui block allows us to choose one of these methods to solve your circuit :
- 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
The powergui block also opens tools for steady-state and simulation results analysis and for advanced parameter.
Simulink MODEL:
Simulink Explanation :
• 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 PLOTS AND RESULTS:
VELOCITY GRAPH:
The actual Speed is approximately followed the 90% of reference Drive cycle. The Temperature of Motor is increased to 7000°C. O The Temperature of Controller is (2800)C.
Distance Graph
Voltage Graph:
Current Graph:
SOC GRAPH:
Temperature variations in Motor and H Bridge:
Energy Graph:
Simulink model file
https://drive.google.com/file/d/1MGEDQOHoOo_LmCDZsHZGZXifS7wNNUHN/view?usp=sharing
driving cycle
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 In the real time application, .
- 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
- Hence, Created a MATLAB model of an Electric Rickshaw (three wheel passenger vehicle) by using Li-ion battery, 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 (i.e.; FTP75, WOT, Manually prepared).
- This Battery powered Rickshaw will be the most popular mode of transport in the future.