PRESENTATION: EVHACK094

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BOSCH –IEEE HACKATHON

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Presented by,

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• SANJANA V
• YESHAS RAGHU GOWDA
• HARSHITHA M
• SOURAV S KASHYAP

PROBLEM STATEMENT

• Design and Simulate an Electric Vehicle
• Vehicle segment: 3-wheeler
• Growing EV 3-wheeler market in India
• More focus on powertrain and energy management system.
• Set performance benchmarks
• Achieve set baselines
• Compute results and compare with targets

BASELINING & METHODOLOGY

SIMULATION METHODOLOGIES

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1. Equation-based approach by studying the model in the reverse order (Backward facing model).
2. Controller is designed using control systems.
3. Motor is designed using ANSYS software.
4. SVPWM generation and FOC control logic is implemented.
5. Braking coordination is done between frictional and regenerative braking.
6. Battery and Ultracapacitor are coupled in Energy Management System(EMS).
7. By calculating forces acting on EV, motor ratings have been obtained.
8. Advisor and Labviews tools were used to enhance knowledge about specific parameters.

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PERFORMANCE BENCHMARKS

Data available on popular electric three wheelers(mahindra treo) was utilised to set the targets

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MODELLING

SIMULATION MODEL

Overview of the powertrain model

PID CONTROLLER MODEL

PID CONTROLLER MODEL

Knowing the number of poles and zeros for the controller, and by keeping the rise time, response time and maximum overshoot in control, we have used tuning tools to get the desired response as shown below.

PID CONTROLLER MODEL

This diagram shows the linearization of plant model, since the plant model is not linear due to the presence of switching and non linear elements and due to this transfer function of the plant cannot be obtained so hence we will have to linearize, this is done By using the concept of state space to transfer function.

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AMT STATE MACHINE MODEL

Gear transmission is included as we have used motor of less speed and torque rating .

GEAR SHIFTING

• Gear(1-4) shifting plot For FTP75 Drive cycle

MODEL FLOW

Accel value

0-1

Multiplied by max EM Tq

EM Torque map saturation

EM efficiency

map

Power formula

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Motor angular velocity

Torque Req

Flow chart to arrive at forward motoring torque from acceleration provided by driver

MODEL FLOW

Brake value

0-1

Multiplied by min EM Tq

Check for SOC

Terminate if SOC is high

Pass Tq if SOC is low

Same process as accel

Torque req

Flow chart to arrive at backward motoring torque

from brake input provided by driver

MOTOR MODEL

Torque and efficiency values are estimated by the lookup table initialized in the model workspace

MOTOR EFFICIENCY CONTOUR

SPEED - TORQUE CHARACTERISTICS

Constraints on the regenerative braking necessitates the frictional brake usage and this coordination is dictated by the speed torque characteristics shown beside

REGENERATIVE BRAKING

Brake Pedal input

Required brake torque, Tbr

if SOC>80%

If Tbr<=max

T regen

70% Tbr = front(max Tregen + friction brakes)

30%Tbr=rear friction brakes

70% Tbr = front friction brakes

30%Tbr=rear friction brakes

70% Tbr= Regenerative Braking

30% Tbr=rear friction brakes

Fully regenerative braking,

T regen= Tbr

YES

YES

YES

NO

NO

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NO

If 70%Tbr<=max Tregen

BRAKING CO-ORDINATION

SOC>80%

Flow chart showing the braking of vehicle using regenerative braking and frictional braking

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BRAKING SYSTEM

Braking coordination is modelled based on flow chart shown in the previous slide

ENERGY MANAGEMENT SYSTEM

Start

Sort power b/w +ve or -ve

Is it +ve

propulsion

+ve power

demand values

Below

30kW

NO

Is SOC min level??

Is UC_SOC high?

NO

END

NO

Use battery

Use UC

Traction

power

END

YES

END

YES

NO

NO

Is SOC>max limit?

Flow chart showing braking coordination in battery and ultracapacitor coupled energy management system

Regeneration

Negative Power

Charge Batt Charge UC

Is SOC>max limit

Is SOC=max limit?

NO

NO

Is SOC UC=SOC batt

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Is SOC UC=SOC batt?

Is SOC Batt=MAX?

0.5 charge UC

Is SOC UC=MAX?

0.5 Charge Batt

NO

YES

YES

YES

YES

YES

NO

NO

ENERGY MANAGEMENT SYSTEM

ENERGY MANAGEMENT SYSTEM

SOC CALCULATION

Model implementating Coulumb counting method for SOC estimation

SOC(t)= SOC(t-1)+I(t)

BATTERY MODEL

Model of a battery designed using charge and discharge characteristics

ULTRACAPACITOR MODEL

review

TRANSMISSION AND DIFFERENTIAL

Depending on the present gear, gear ratio is estimated in the lookup table and multiplied with the motor torque to get the desired torque

WHEEL MODEL

FRONT BRAKES

FRONT WHEEL

• The torque input is converted to tractive force

VEHICLE BODY

MODEL RESULTS

PLOT MATCHING FTP75 DRIVE CYCLE

SOC PLOT

As the regenerative braking power is given to ultracapacitor only,SOC increase can be observed in ultracapacitor but not in battery.

POWER COORDINATION

• Power above 30 KW is given to Ultracapacitor
• Power below 30 KW is given to Battery

• Regen power is given only to Ultracapacitor

BATTERY SPECIFICATIONS

Battery

PARAMETERS

TOOLS USED

Used LABVIEW software to calculate battery capacity.

RECOMMENDATIONS

• Using digital CONTROLLER because of its various applications over the analog controller like OTA (over the air updates) can only be used using the digital control method, even the control of a vehicle using any method like FOC can be achieved easily. Also, we can implement control algorithms just by writing C, C++or java codes if needed.

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• SOC Estimation can be done using series Kalman filter technique for accurate results.

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• Isolated converters can be used to reduce losses and increase efficiency of the system.

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LITERATURE SURVEY

• In present market most of the vehicles are just running with battery alone and due to this the battery life and health is reduced over time so hence we have come with combined energy source coupled with battery and ultracapacitor.

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• Search for alternate for Lithium ion batteries has continued, but replacing Li ion batteries in the near future is difficult. Lithium ion batteries are here to stay for a while.

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• Different motor control strategies are being used in the market(like FOC and VFD), but still its an area of research.

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• The estimated cost of our electric vehicle is around Rs.60000 and the average cost of the electric auto in the market is around Rs.90000

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THANK YOU