Project-1: Modelling an electric Car with Li-ion battery

Create a MATLAB model of electric car which uses lithium ion battery and suitable motor. Choose suitable blocks from Simscape or Powertrain block set. Implement the vehicle speed control using PI controller and generate brake and accelerator commands. Avoid using readymade driver block for speed control.

Prepare a report about your model including following:

Objectives, System level configurations, Model parameters, Results, Conclusion.

(Note- The simulink model file should be compulsorily attached)

Electric vehicles have low running costs as they have fewer moving parts for maintenance and are also very environmentally friendly as they use little or no fossil fuels (petrol or diesel). While some EVs used lead-acid or nickel-metal hydride batteries, the standard for modern battery electric vehicles is now considered to be lithium-ion batteries a  s they have greater longevity and are excellent at retaining energy, with a self-discharge rate of just 5% per month. 

a MATLAB model of an electric car which uses a lithium-ion battery and a suitable motor. Choose suitable blocks from Simscape or Powertrain block set. Implement the vehicle speed control using PI controller and generate brake and accelerator commands

PID controller subsystem:............................................

in this, we have used add block which:--

subtracts feedback velocity from reference velocity.

This output is given to the PID controller.

PID Controller:

the parameter of the PID controller has been shown in the above screenshot of PID COntroller

we have used SATURATION BLOCK :

Saturation Block:

one for acceleration 

and one we have used for brake/deacceleration

in this, the upper value has been given to 0 and the lower value to be -2

These block helps to limit the output signal from the PID controller and separate deceleration and acceleration values.

The output from these blocks is sent to a transfer function then these are provided to the motor controller block.

Motor Controller Subsystem:

• Controlled Voltage Source:
• 

• The Controlled Voltage Source block represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current flowing through the source.

• The output voltage is V = Vs, where Vs is the numerical value presented at the physical signal port

• Controlled PWM Voltage:

It is used to give the Pulse Width Modulation signals to the H bridge circuit at the PWM terminal. The +ve reference terminal of the block is connected to the controlled voltage source and -ve is connected to the electrical reference, the PWM is connected to the H bridge PWM as said above and REF is connected to the REF and REV terminals of the H bridge.

• The Controlled PWM Voltage block represents a pulse-width modulated (PWM) voltage source. The block has two modeling variants,

• Electrical input ports — The block calculates the duty cycle based on the reference voltage across its ref+ and ref- ports. This modeling variant is the default.

• PS input — Specify the duty cycle value directly by using an input physical signal port.

• For the Electrical input ports variant of the block, the demanded duty cycle is

  100∗Vref−VminVmax−Vmin %">100∗Vref−VminVmax−Vmin%100∗Vref−VminVmax−Vmin %

  where:

  • V_ref is the reference voltage across the ref+ and ref- ports.

  • V_min is the minimum reference voltage.

  • V_max is the maximum reference voltage.

H - Bridge :

As the name indicates that the H symbol in the block is connected to the DC motor and the PWM, REF, REV, and BRK are used to control the block DC motor.

in the input threshold, the valve for voltage is 50v provided

current sensor:-------

Electrical reference:

It is used to connect all the terminals of the negative signals and the reference values as the ground.

Ps-Simulink converter:

It is used to connect the line from the physical signal to Simulink which act as a converter.

DC Motor :

It is used to convert electrical energy to mechanical energy. In this electric vehicle model, we have used a type is permanent magnet DC motor. This motor can also act as a generator in the case of regenerative braking.

In this block, the motor's electrical side is represented with the blue color and the mechanical side is represented with green as well with the combination of shafts which is in the dotted line. here the motors +ve and -ve terminals are connected to the H-Bridge +ve and -ve terminals respectively with the electrical reference in the -ve side. 

Mechanical rotational reference:

It is represented as a mechanical ground reference point that is as a frame part that is used to connect rotational parts to the ground.

Vehicle Body :

simple gear

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

4 - Tyre :

Connection A is the mechanical rotational conserving port for the wheel axle

Connection N is a physical signal input port that applies the normal force acting on the tire

Connection S is a physical signal output port that reports the tire slip.

vehicle body:------------

• 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.

Battery :

In this subsystem we have used a battery block, a controlled current source block bus selector and Import and outport blocks.

the voltage supplied to the battery pack is about 450v

This demo illustrates the effect of temperature on the performance of a 7.2 V, 5.4 Ah Lithium-Ion battery model. The model (which includes the impact of cell/ambient temperature on the voltage, capacity and resistance) is submitted to a variable ambient temperature during a discharge and charge process. Its performance is compared to the case where the impact of temperature is neglected. As observed from the Scope, the temperature dependent battery model performs close to reality. As the cell/internal temperature increases/decreases due to charge(or discharge) heat losses and ambient temperature variations, the output voltage and capacity also increase/decrease

We can say that the battery is one of the main important parts or the block in the vehicle and model as well. By connecting this terminal to the controlled voltage source it supplies controlled signals to discharge and also charging in the regenerative type as well.

Bus Selector :

The bus selector is used to block the output signals which are given as an input to that bus

 Library:

• Simulink / Commonly Used Blocks

  Simulink / Signal Routing

  HDL Coder / Signal Routing

The Bus Selector block outputs the elements you select from the input bus. The block can output the selected elements separately or in a new virtual bus.

The Bus Selector block does not support mixing message and signal elements as outputs.

powergui

It is used for the analysis and measurement of parameters like voltage, current, active power, reactive power like that.

The powergui block allows you to choose one of these methods to solve your circuit:

The powergui block also opens tools for steady-state and simulation results analysis and for advanced parameter design.

You need the powergui block to simulate any Simulink model containing Simscape™ Electrical™ Specialized Power Systems blocks. It stores the equivalent Simulink circuit that represents the state-space equations of the model.

When using one powergui block in a model:

Solver configuration:

It is placed in the power control unit for the mathematical values in the model solver settings at the simulation time

To get the results of this model we have to keep the stop time to 2474 sec or above because of the given drive cycle source with FTP (2474 seconds)

Each physical network represented by a connected Simscape™ block diagram requires solver settings information for simulation. The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.

Each topologically distinct Simscape block diagram requires exactly one Solver Configuration block to be connected to it.

RESULT......................................................................

It is the combination of both the drive cycle and the vehicle body velocity which is called a feedback reference. Here the yellow represents the velocity and the blue is for the drive cycle source. They both are looks in similar lines with different values. The changes of the values of this give the acceleration and the deceleration values from the PID. Here if we observe that in the given graph in both values are changes in change in the accel and dec values but in the constant time they both are in the same 

• When the velocity and the drive cycle data can equally merged and the vehicle can control with respect the drive cycle FTP-75

 

SOC (%) :

It reduces based on the given input to the battery through the current signals

Voltage (V) :

Battery current:

 if we observe here that acceleration goes up its current values increased and in it decelerates it value is reduced respectively as above at the constant time that is from the near value of 1400 to 2000 sec time it gets decreased slightly due to losses.

MATLAB model of electric car which uses lithium-ion battery and suitable motor is created.