Analyse the vehicle range and performance using Advanced Vehicle Simulator Tool (ADVISOR Tool) in MATLAB and Simulink

AIM :- To Analyse the vehicle range and performance using Advanced Vehicle Simulator Tool (ADVISOR Tool) in MATLAB and Simulink

OBJECTIVE :-

•  To Study the Range of an electric vehicle using FTP drive cycle  using ADVISOR tool.
•  To Study the battery capacity of the electric vehicle and battery capacity and drive cycle dependency in the range of the electric vehicle using ADVISOR tool.
• To Study the gradeability test with PRIUS_Jpn default vehicle in ADVISOR tool.

ADVANCED VEHICLE SIMULATOR (ADVISOR) :-

This tool, originally developed by the National Renewable Energy Laboratory (NREL), allows users to simulate and analyze conventional, advanced, light, and heavy vehicles, including hybrid electric and fuel cell vehicles. The tool allows users to assess the effect of changes in vehicle components (such as motors, batteries, catalytic converters, climate control systems, and alternative fuels) and other modifications that might affect fuel economy, performance, or emissions. This allows system-level analysis and trade-off studies of advanced vehicles.

ADVISOR approximates the continuous behavior of a vehicle as a series of discrete steps during each of which the components are assumed to be at steady state. That is, at each time step, the effects of changing current, voltage, torque, and RPM are neglected. This allows efficiency or power loss tables, which are generated by testing a drivetrain component at a fixed torque and RPM (and current and voltage, if applicable), to be used to relate the power demands of the components at each time step. A significant advantage of using a model that is in the Simulink/MATLAB environment is the flexibility and ease of changing the model, such as replacing one control strategy or regenerative braking algorithm with another.

MATLAB also allows easy plotting of results that makes detailed analysis of vehicle configurations possible. ADVISOR is driven by the input driving profiles which can be the classic speed vs. time, such as the federal urban driving schedule (FUDS), or a speed and grade vs. time driving profile. With a given driving profile goal, ADVISOR then works its way backwards from the required vehicle and wheel speeds to the required torques and speeds
of each component between the wheels and the energy source, which is either fuel from the hybrid power unit (HPU) or electricity from the batteries. Limits for each of the components are included, so the actual speed vs. time profile computed is the one that is within the limits of all components and includes all component losses and vehicle drag.

• ADVISOR operates in the MATLAB/Simulink environment
• Vehicle data is provided in Matlab files (m files) and models are developed in Simulink (calculations)
• Emperical  model using drivetrain component performances Graphical User Interface (GUI), allows the user to model any type of ICE/EV/HEV by easily
  changing the vehicle configuration and parameters without having to modify the Simulink block diagrams.
• ADVISOR is a backward facing model with limited forward facing capabilities

MAIN SIMULINK MODEL IN ADVISOR :-

STEPS FOR SIMULATION IN ADVISOR :-

Defining a vehicle :-

1. User can adjust his own vehicle configuration & components using drop-down menus user can modify variables in the variable list.
2. Graphical representation of the powertrain selected
3. Shows the performance information of the components (efficiency contours, emission contours and batteries)

                                        vehicle input configuartion screen 

Simulation Wizard :-

1. User can select a drivecycle/test procedure, no. of cycles etc. Declare initial conditions soc correction for HEV.
2. Gradeability and acceleration requirements parametric analysis can be done.
3. Views drive cycle selected and associated statistics description.
4. Drive cycle graphical representation. 

                                                    Simulation setup screen

Results :-

1. Plot controls
2. Shows the fuel economy gasoline equivalent and distance covered.
3. Emission data
4. Acceleration gardeability
5. warnings  
6. Versus graphs info. (Max 4 nos.)

                                          Result display screen

STUDY 1 :-

For EV_defaults_in file, if cargo mass is 500 kg with all other default conditions, can the vehicle travel for 45 km with FTP drive cycle?

• Open the ADVISOR tool on matlab by typing ADVISOR on command window.
• Choose the mertic unit format and press start.
• Choose the EV_defaults_in file from drop down menu at the top of the vehicle input screen 

Motor Charaterstics

Now, Input mass of the vehicle is 592 kg, mass of the battery is 275 kg, mass of the motor is 91 kg, mass of the transmission is 50 kg and the cargo mass is 500 kg, total mass is 1508 kg. The number of battery used is 25 pieces and the battery voltage is 308 volts.

• Now, Continue to simulation screen.
• In the simulation screen choose the FTP drive cycle keeping No. drive cycle value 1.
• Press the run button to proceed to result window.

The above figure consists of max speed average speed of the vehicle, overall time and distance, Maximum acceleration and deacceleration of the vehicle, idle time, number of stops, and grade percentage. Here the total distance covered is 17.75 km approx. The maximum speed of the vehicle is around 91 kmph and average speed maintained by the vehicle is 26 kmph for overall the distance of 18.5km. The time taken to cover the distance is 2477 sec i.e., 41'17" (41 minutes and 17 seconds). The maximum acceleration of the vehicle is 1.475 m/s2 and the average acceleration maintained is 0.51 m/s2. The number of stops captured as 22 times which the vehicle is in idle position i.e., keyoff time. The idle time taken by the vehicle for 22 stops as 360 sec, the average time taken for each stop as 16 seconds which represents the vehicle deaccelerate and reach 0 speed. The maximum deacceleration of the vehicle is 1.475 m/s2 and the average deaccelerate of the vehicle is 0.576 m/s2. The straight line represents 0 % gradeability.

The Federal Test Procedure (FTP) represents a commuting cycle with a part of urban driving including frequent stops and a part of highway driving. During urban road driving, the number stops are 18 times which is travelled around 12.55 km and time taken as 1400 seconds i.e.,(23' 33"). The average velocity maintained is around 32.3 kmph in urban drive cycle. In this cycle the acceleration is less and deacceleration is more due to frequent stops. During Highway driving cycle, the number of stops are less in this cycle which is 4 times. The distance covered in this cycle is 5.2 km and time taken as 477 seconds i.e., (8') approx. The velocity maintained in this cycle is 39.3 kmph more than the urban cycle. In this cycle the deacceleration is less and acceleration is more.

In the Result, results shows that the vehicle can travel 17.5 km with this battery charge for 1 cycle and the drive cycle used as FTP. The max speed is reached as 88.5 kmph and Depth of discharge is 0.6.

STUDY 2 :-

 In STUDY 1, try changing the battery capacity and repeat the simulation

A battery consists of two or more electric cells connected together. The cells convert chemical energy to electrical energy. The cells consist of positive and negative electrodes in an electrolyte. It is the chemical reaction between the electrodes and the electrolyte which generates DC electricity. In the case of secondary or rechargeable batteries the chemical reaction can be reversed by reversing the current and the battery returned to a charged state. From the EV designer’s point of view the battery can be treated as a ‘black box’ thathas a range of performance criteria. These criteria will include specific energy, energydensity, specific power, typical voltages, amphour efficiency, energy efficiency, commercial availability, cost, operating temperatures, self-discharge rates, number of life cyclesand recharge rates. The cells can be connected in series to give the overall voltage required. Traction batteries for EVs are usually specified as 6V or 12 V, and theseunits are in turn connected in series to produce the voltage required.

Battery capacity = 308 volts, the number of cells used is 150

Battery capacity = 370 volts, the number of cells used is 180

Battery capacity = 493 volts, the number of cells used is 240

Changing the battery capacity won't effect the max distance travelled by  this vehicle because  as we saw in the figure.9 the energy soc history  the charge is still above 50% so we need to increase the drive cycle step wise to see at what capacity the battery drains fully to zero. once the charge reaches value zero then we will increase the battery capacity of that step drive cycle.

                                 drive cycle increased to 2 (5000 sec) andbattery capacity remains default 

                                 drive cycle increased to 3 (6000 sec) andbattery capacity remains default 

                        drive cycle increased to 3 (6000 sec) and battery capacity changed by 27 packs 

 As we can see, the energy SOC for battery reached 0 value for 3 cycle period and maximum distance travelled is  41.4km . so now we need to increase the battery capacity  to 27  ans observe the results the max distance travelled is 44.8 km which nearly close to 45 km . So we can conclude that to reach the distance of 45 km we need 3 drive cycle and increase the battery capacity more that 27 packs .

STUDY 3 :-

Study the gradeability test with PRIUS_Jpn default vehicle in ADVISOR tool and Compare Results

Gradeability is defined as the highest grade a vehicle can ascend maintaining a particular speed. When designing an automobile, various performance targets are kept in view, the major ones being weight, fuel economy, power, torque, speed, and acceleration, gradeability is given a lesser significance unless a special purpose vehicle is being designed like a Sports Utility Vehicle (SUVs) or other heavy duty vehicles. Urban vehicles do have to encounter situations where they might have to ascend slopes like a basement or a bridge.These situations might prove to become difficult for the driver when on full load, hence making it an important performance factor not only for Special Purpose vehicles but also to those driven in the urban land.

Open the PRIUS_jpn from the vehicle input screen from the drop down menu and proceed to simulation setup window.

• Choose the CYC_UDDS driving cycle as default set in simulation window.
• Click on the gradeablity test checkbox then go the grade option to set the values.
• Keep the value of gradient value 7% and  duration 40 sec  as constant change the value of speed and run the simulation to see the result.

                    simulation setup screen for PRIUS_jpn file for gradeablity test. 

I4auf the the result shows the value of gradeablity then it passes the test and if it is blank  then it means it has failed the test.  

                                        Grade option for 55 mph and result display of 7% gradeablity test pass  

                                          Grade option for 50 mph and result display of 7% gradeablity test pass  

                                             Grade option for 46 mph and result display of 7% gradeablity test pass  

                                     Grade option for 45 mph and result display of 7% gradeablity test fails   

As we can see from the above figures  we can conclude that PRIUS model for 40 sec duration and 7 % gradeability fails at 45 mph i.e 72.4 kmph. To pass the gradeablity test the vehicle must be above the 45 mph speed.

CONCLUSION :-

• As the mass increases, the velocity decreases and energy consumption increases in any vehicle.
• Hybrid vehicle can achieve high torque than the electric vehicle and ic engine.
• Hybrid vehicle can attain high speed than the electric vehicle.
• By changing the battery capacity, the state of charge increases which inturn the overall efficiency also increases.