Final Project: Electric Rickshaw modelling
ELECTRIC RIKSHAW MODELING
AIM: Design of an Electric Rickshaw using MATLAB Simulink
ABSTRACT:
In this project, we work to create the MATLAB model of the electric rikshaw by doing a PM brushed type DC motor and a suitable Lithium-Ion battery for the motor. Before this, we will remember what is Electric rickshaw, how it's functioning, and the privileges of EV rickshaw Then we make an actual EV rickshaw model in simulink with suitable blocks from the powertrain block set. My main motto is to examine "how my rickshaw performs for any three standard driving cycles showing energy consumption, the temperature rise of motor and controller for vehicle cover around 100 km at constant speed driving 45 kmph. Made a comparison with Mahindra e-Rickhshaw and my Simulink model.
OBJECTIVES:
Create a detailed MATLAB model of an electric rickshaw (three-wheel passenger vehicle) as per the 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, the temperature rise of the motor and controller for 100 km constant speed driving at 45 kmph.
METHODOLOGY:
- The electric vehicle consists of a battery, motors, and controller then it generates propulsion power.
- To design any vehicle 1st we have to calculate propulsion power then the motor is selected.
- Lastly based on the motor rating or operating range and no km/charge we want to depend on everything battery capacity and then battery capacity is selected.
So the Design flow of the vehicle engineers has to be like the following:
- Identify what amount of propulsion power is required.
- What is the best suitable motor for that propulsion power?
- Then type of battery and range of battery according to the range.
INTRODUCTION
Electric rickshaws (also known as electric tuk-tuks or e-rickshaws or toto or e-tricycles) are small 3-wheeled vehicles powered by anelectric motor and battery ranging from 650 to 1400 Watts. They save on fuel costs compared toauto rickshaws while offering greater ease-of-use than pulled rickshaws. This has led to their popularity and widened-acceptance in some cities since 2008.
If introduced in a systematic manner, electric rickshaws could be a low-emitter complementary transport for low-income people who suffer most from a lack of transport facility.They are mostly manufactured in India and China.
These rickshaws have a mild steel tubular chassis , consisting of three wheels with adifferential mechanism at the rear wheels. The motor is a brushless DC motor. The electrical system used in Indian versions is 48V and in Bangladesh is 60V. The body design from the most popular Chinese version is of very thin iron or aluminum sheets. Bodies made of fiberglass are also popular because of their strength and durability, resulting in low maintenance. Body design is varied from load carriers, passenger vehicles with no roof, to full body with windshields for drivers' comfort.
It consists of a controller unit.They are sold on the basis ofvoltage supplied and current output, also the number of mosfet (metal oxide field effect transistors) used. The vehicle's batteries are typically lead acid with a lifespan of 6–12 months.Deep cycle batteries designed for electric vehicles are rarely used. Weight of the electric car has also been a recurring design difficulty in them.
Basic block model of ev
Drive cycle: A drive cycle is typically represented by a series of data points which plots vehicle speed against time. Driving cycles are produced to assess the performance of vehicles in various ways, including fuel consumption and pollutant emissions.
Driver controller: The electric vehicle controller is the electronics package that operates between the batteries and the motor to control the electric vehicle's speed and acceleration much like a carburetor does in a gasoline-powered vehicle.
Power converter with regenerative braking:They are used to process and control the flow of electrical energy by supplying required voltages and current in a form that is optimally suited for the user loads.
Battery: This the powerhouse which supplies the energy required to drive the vehicle.
Motor:It is the rotating device which converts the electrical energy in the form of current and voltage into the mechanical energy at the vehicle through a transmission system.
Vehicle body:This is where the output is achieved via the motor power is transferred to the wheel considering the different forces and resistance and compare with the input drive cycle.
Power and Motor Controlled Subsystem Model ( With Temperature Sensor)
H BRIDGE
The H-Bridge block output is a controlled voltage that depends on the input signal at the PWM port. If the input signal has a value greater than the Enable threshold voltage parameter value, the H-Bridge block output is on and has a value equal to the value of the Output voltage amplitude parameter. If it has a value less than the Enable threshold voltage parameter value, the block maintains the load circuit using one of the following three Freewheeling mode options:
- Via one semiconductor switch and one freewheeling diode
- Via two freewheeling diodes
- Via two semiconductor switch and one freewheeling diode
• 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.
DC Motor:
• This block represents the electrical and torque characteristics of a DC motor includes Thermal port to series 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
• Motor parameters can either be specified directly or derived from the 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.
• The Motor 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 Input 1 is getting from the accelmd of a longitudinal driver and it is given to a controlled voltage source block where it is input to the controlled PWM voltage will generate a PWM signal in such a way that H-bridge will generate the required voltage to operate the DC motor for the given driver input
• PWM voltage block negative reference and REF are grounded and REF of H bridge respectively. H-bridge is a motor controller that has IGBT components aligned in the shape of H and will operate only two at a time respectively to the input of the signal from the PWM block.
• When deceleration occurs this H-bridge will give an output from the positive and negative terminals of it. These negative & positive terminals are later connected to the DC motor and battery. All these components are the simscape electrical components so they need a connection to the solver configuration block which helps to solve the simulation.
Controlled PWM Source
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.
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.
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 a value equal to the averaged PWM signal. Select Simulation mode as Averaged.
Temperature Sensor:
• Temperature Sensor is used to measure the temperature of the 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.
Solver Configuration:
Defines solver settings to use for simulation.
Vehicle Body and Tire 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 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.
Tire ( magic frame)
The Tire-Road Interaction (Magic Formula) block models the interaction between the tire tread and road pavement. The longitudinal force arising from this interaction is given by the magic formula, an empirical equation based on four fitting coefficients. Tire properties such as compliance and inertia are ignored.
The A ports of the tire are the mechanical rotational conserving port and receive mechanical rotational input from the gearbox which receives its input from the DC motor.
The H port of the tire is the mechanical translational conserving port for the wheel hub and is connected to the H port of the vehicle body through which the trust developed by the tire is applied to the vehicle.
Here we are not considering any slip, so an terminator block is connected to all the slip port of each tire. Also, grade angle and wind velocity are not considered.
The input is received from the DC motor to the simple gear block which is then transmitted to the wheel considering the inertia couple at the output shaft.
Simple Gear
This example shows a simple gear coupling two inertias (shafts). The gear ratio between the follower (F) and base (B) is 2:1. Thus the angular velocity of the follower shaft is half the angular velocity of the base shaft. The follower shaft torque is twice the base shaft torque.
Connections B (base) and F (follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation directions with the Output shaft rotates parameter.
Optionally include thermal effects and expose thermal conserving port H by right-clicking on the block and selecting Simscape block choices to switch between variants Output shaft rotates in the same direction of the input shaft.
The base is connected to the Motor shaft and the follower is connected to the Rear-wheel derive.
Vehicle Body
The Vehicle Body block represents a two-axle vehicle body in longitudinal motion. The vehicle can have the same or a different number of wheels on each axle. For example, two wheels on the front axle and one wheel on the rear axle. The vehicle wheels are assumed identical in size. The vehicle can also have a center of gravity (CG) that is at or below the plane of travel.
The block accounts for body mass, aerodynamic drag, road incline, and weight distribution between axles due to acceleration and road profile. Optionally include pitch and suspension dynamics. The vehicle does not move vertically relative to the ground.
The block has an option to include an externally-defined mass and an externally-defined inertia. The mass, inertia, and center of gravity of the vehicle body can vary over the course of simulation in response to system changes.
H- t is the mechanical translation converting port associated with the horizontal motion of the vehicle body
NR- Signal output port for rear normal wheel forces
NF- Signal output port for front normal wheel forces
V- Signal output port for vehicle velocity
Beta- Signal output port for road inclination angle
W- Signal output port for headwind speed
Battery And Soc Subsystem Model
Battery
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 block implements a generic dynamic model that represents the most popular types of rechargeable batteries.
The battery has two-stage one is charging and another one is discharging state.
The battery is of 75Ah capacity.
The Nominal voltage of the battery is 330 V
Initial SoC is 100%
The battery as a series internal resistance plus a charge-dependent voltage source
`V=(Vnom*SoC)/((1-beta)*(1-SoC))`
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,VI].
• 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
Battery State of Charge:
• SoC is the percentage or level of battery presents after certain travel or consumption of battery charge by the vehicle.
• In the designed vehicle battery charge or SOC is calculated by giving it to the rate transition and then to gain where 1/inominal battery capacity) then to a discrete-time integrator and it will get minus from the 1 as it is considered a 100% of battery and it is multiplied with 100 to get a percentage of battery.
• The majority of blocks are simscape blocks were physical to Simulink converter is used to convert the physical signal from simscape block to Simulink signal
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 the drop-down menu of measurement select current.
• Signal output will connect with scope by adding the current signal to it. (+) the terminal will connect with the 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 it with different Scope Block.
Longitudinal driver
The input from the drive cycle is attached to VelRef port, the feedback is gained from the vehicle body which acts as feedback signal is connected to VelFdbk. The AccelCmd & DecelCmd are the output signal given for accelerating and braking to the vehicle. A terminator block is connected to Info port as we are not using any bus signals for this model. A constant block is attached to the Grade port as road grade angle is 0 in our case, i.e the vehicle is running at a straight road.
VelRef - Input port for the reference velocity signal
VelFdbk- Input port for the feedback velocity signal
Grade- Input port for the gradability to the vehicle (road grade angle)
Info- Bus signal for Gear, clutch, acceleration, etc.
AccelCMD-Output port for the acceleration signal command
DecelCmd- Output port for the deceleration or braking signal command
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 are used to test the vehicle performances.
• These drive cycles will have high-speed low speed. braking conditions in it
• There are different drive cycles like WOT FTP75 etc. Here in this model I have used FTP 75 WOT & Manically prepared in excel Drive Cycle source
FTP 75 Drive cycle 
Wide Open Throttle (WOT)
Prepared Drive cycle
E Rickshaw Full model
Initially the current flow 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 gearbox and the controller will take the vehicle speed and compare and control.
Output Plots:
1. For FTP75 Drive Cycle:
Distance travelled
state of charge is of battery drops to75% after running 4.9 kms
Temperature of motor and controller
2. For WOT Drive Cycle:
For Manually prepared Drive Cycle
CONCLUSION
Created a MATLAB model of an Electric Rickshaw (three-wheel passenger vehicle) by using a 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. For every respective cycle we saw the velocity profile following the given drive cycle data, and attaining the close value to the actual speed of the drive cycle. The SOC of the battery for each cycle depends on various factors. The coefficient of rolling resistance, Thermal mass, Gear ratio, etc. By varying these parameters we can change the SOC of the battery for the particular drive cycle. This Battery-powered Rickshaw will be the most popular mode of transport in the future.