Final Project: Electric Rickshaw modelling

Electric Rickshaw

Aim: To create a detailed MATLAB model of an Electric Rickshaw (three wheel passenger wheel).

Software used:

MATLAB R2020a (SIMULINK).

Objectives:

• Rear wheels are 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.

Block Diagram:

In the designed Electric Rickshaw main blocks are battery, drive cycle, controller, DC motor, Vehicle body& Transmission system. Drive cycle is in the input data like how human drive his actual vehicle here FTP75, WOT& Excel (Manually prepared in Excel sheet) drive cycles are used to make the designed vehicle to give the output how it reacts to the drive cycle. The main objective is to obtain the speed by the driver, to estimate the temperature of motor and controller, to estimate the state of charge (SOC), distance travelled by the vehicle. There is a SOC block that will estimate the state of charge of charge of battery, distance calculated by speed and time parameters for all three drive cycles.

MATLAB Model of an Electric Rickshaw:

Initially current flows to DC motor from the battery through the DC-DC power converter to the drive motor. The required voltage will be required in the controller, the controller will follow the given drive cycle reference and run the motor in the require 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.

Model parameters

Drive Cycle:

Drive cycle is assumed s the driver’s input of a vehicle; it replaced how a driver will drive vehicle. I have used a three drive cycles which is used to test the vehicle parameters. These drive cycle will have high speed, low speed, braking conditions in it. These are different drive cycles like WOT etc.. Drive cycle source.

Generates a standard or user-specified longitudinal drive cycle. The block output is the vehicle longitudinal speed, it can import the drive cycle from:

• Predefined sources
• Workspace variables, including arrays and time series objects
• Mat, xls, xlsx, or txt files.
• 

Use the fault tracking parameters to identify drive cycle faults within specified speed and time tolerance.

Wide Open Throttle:

All three drive cycles are controlled by the controller provided above by constant through Multi-port switch.

Driver controller

A parametric longitudinal speed tracking controller for generating normalized acceleration and braking commands based on references 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 input commands, disable, hold, and override. Drive cycle is connected to longitudinal driver, it has six points namely velocity feedback, velocity reference, grade, info, Acceleration, Deceleration.

VelRef is given by the drive cycle data and VelFdbk is given by the output of the motor. These two will get compare and the acceleration or deceleration output will be given to the motor controller. Acclaimed is given the PWM generator block and declaimed is given to regenerative port the h-bridge uses to generates the regenerative braking. Info is used o get any other data from a longitudinal driver block. The grade is to give the input of grade ability to the driver block. This block helps to generate regenerate the driver’s conditions of the vehicle use the driver cycle block.

Motor& Controller

1. Motor type (PM brushed type motor):

This block represents the electrical and torque characteristics of a DC motor includes Thermal port to sense the temperature of Motor. The block assumes the no electrical energy is lost, and hence the back EMF and torque constants have the same numerical value when in SI units. Motor parameters can either by 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 values. When a positive current flow from the electrical + to – parts, a positive torque acts from the mechanical C to R ports. Motor torque direction can be changed by altering sign of back EMF or torque constants.

Motor parameters

The motor controller will get the input from the longitudinal driver. Its 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.

Input1 is getting from the accelmd of a longitudinal driver and its is given to a controlled voltage source block where its input to the controlled PWM voltage. Control PWM voltage will generate a PWM signal in such a way that Hybrid will generate the required voltage to operate the DC motor for the given driver input. PWM voltage block negative reference and REF grounded and RFE are 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 a signal from the PWM block. When declaration 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 Sims cape electrical components so they needed a connection to solver configuration block which helps to solve the simulation.

2. Controlled PWM Voltage Source:

This block creates a Pulse-width modulated (PWM) voltage cross 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. At time zero, the pulse is initiated as high unless the duty cycle is set to zero or the pulse delay, time is greater than zero. This simulation mode can be set to PWM or Averaged. In a 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 is averaged.

3. Power Converter:

H-bridge:

H-bridge is used as DC-DC Converter:

This block represents the 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 Enable threshold voltage. In Average mode, the PWM port voltage divided by the PWM signal amplitude parameters 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 must be 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 priority 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.

Motor controlled parameters:

4. Temperature Sensor:

Temperature sensor is used to measure the temperature of H-Bridge and motor.

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

5. Solver Configuration:

Defines solver settings to use for the simulation.

References:

• Thermal Reference: Used to ground the all the electrical connections.
• Mechanical Rotational Reference: Used to ground all the mechanical rotational parts.
• Thermal Reference: Used to ground the thermal sensor.

Battery:

Battery Parameters:

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 two stage one is charging and other one is discharging state. The battery is 75Ah capacity.

The Nominal voltage battery is 330v

The battery as a series internal resistance plus a charge-dependent voltage source defined by-

v= vom.soc/1-b.(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, 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 controlled and then it is given to the SOC block.

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 the giving to the rate transition and then to gain where 1\(nominal battery capacity) then to discrete time integrator and it will get minus from the 1 as it is considered a 100% battery and it is multiplied with 100 to get percentage of battery.

The majority of blocks are SIMSCAPE blocks here physical to SIMULINK converter is used to convert the physical signal from SIMSCAPE block to SIMULINK signal.

Vehicle Body & Transmission:

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 inside the vehicle body and transmission system and in the main design, it is referred just only as a transmission system.

The gear output is given to axis of Rear tires, in the circuit as shown that gear is connected to Rear wheels and front tire is free to rotational motion, thus vehicles moves forward 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 angle. Thus tire hub is connected a common node o the vehicle body. The vehicle body wind velocity is connected to a constant block and beta inclination angle is connected to another Constant block where we can assign wind velocity and inclination angle s 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 distance travelled and state of charge.

1. Vehicle Body:
2. Wheels:
3. 
4. Inertia:

The block represents the ideal mechanical rotational inertia.

The block has one mechanical rotational conserving port. The block positive direction is from its port to the reference point. This means that the inertial torque is positive if the inertia is accelerated in the positive direction.

4. Simple Gear box:

Gear ratio represents a fixed-ratio gear or gear box. No inertia or compliance is modeled in this block. It can optionally include gear meshing and viscous bearing losses. Connections B (base) and (Follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation direction with the output shaft rotates parameters. Optionally include thermal effects and expose thermal conserving port H by right clicking and selecting SIMSCAPE block choices to switch between variants. Output shaft rotates in same direction of input shaft. Base is connected to the Motor shaft and the follower is connected to the Rear wheel drive.

Results

1. For FTP5 Drive Cycle:

By running the vehicle with FTP75 Drive cycle for 2474sec. the distance travelled is

• The actual speed is approximately followed the 90% of reference Drive Cycle.
• Energy consumed by the battery is 3.10wh at the end of the cycle.
• The SOC% of the battery is reduced to 83%
• The Temperature of motor is increased to 370⸰c
• The temperature of controller is 180ﹾ

2. For WOT Drive Cycle

By running the Vehicle with WOT Drive cycle for 200sec, the distance travelled is

• The actual speed is approximately followed the 85% of reference Drive cycle.
• 
• Energy consumed by the battery is increased linearly till 100sec. to approx Then reduced gradually due to back EMF and finally at the end of the cycle, energy consumption is reached to 900Wh.
• The SOC% of battery is reduced to 91% and 100-200 sec. The batteries get charged by back EMF.
• The Temperature of Motor is increased to 180⸰c
• The Temperature of controller is 110⸰c.

3. For Manually prepared Drive Cycle:

To increase the speed of the vehicle, the output voltage amplitude is applied to 400v. By running the vehicle with manually operated Drive cycle for 120 sec. the distance travelled is 3.876km.

• The actual path of the speed is approximately followed the reference Drive cycle as above.
• 
• Energy consumed by the battery is varied with respect to time and distance 10500wh at the end of the cycle.
• The SOC % of the battery is reduced to 94.2%
• The Temperature of Motor is increased to 260ﹾc
• The Temperature of controller is 145⸰c.

Conclusion:

• The Temperature of Motor and Controller to achieve vehicle speed is near to reference speed. It doesn’t use any cooling system in the model. In the real time application, the motor temperature is less than 100ﹾ
• In real time application, the motor, battery& controller temperature is controlled by air cooling. Hence the temperature of this component is not increased in extent.
• To created a MATLAB model of an Electric Rickshaw (Three wheel passenger vehicle) by using Li-ion battery, PM Brushed DC motor.
• Determine the variations of Temperature of Motor & Controller, SOC % energy consumed by the vehicle for all the three reference drive cycles (i.e. FTP75, WOT, Manually prepared).
• This Battery powered Rickshaw will be most popular mode of transport in the Future.