Presentation_Dwarapureddy_Katta Raja Gopal_Cheeti

Rule based energy management strategy for parallel
hybrid electric vehicle with charge sustainment
Seminar Electromobility SS 2015 (07.08.15)
By,
Arjun Rao Dwarapureddy
Sharan Sai Katta Raja Gopal
Vikas Rao Cheeti
Masters in commercial vehicle technology
University of Kaiserslautern

Dwarapureddy, Katta Raj Gopal, Cheeti
Student of Commercial Vehicle Technology
Ruled Based Energy Management stratergy for parallel hybrid electric vehicle with charge sustainment
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Contents
1.Introduction and Motivation
Fundamentals about HEV‘s
Elements of QSS Tool box
Rule Based Statergy
2. Modeling
Torque Split ratio
Operation Modes
3. Results
Torque Split Ratio
Equivalent Fuel consumption
State of Charge
4. Conclusion & Future work

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Introduction
Motivation
• Why HEV’s ?
– there is a large concern about increase in oil prices and environmental emissions in today’s world
and there is a need to switch to electric, hybrid and fuel cell vehicles.
– With the available energy sources, the electric vehicle (EV) cannot compete with the conventional
vehicle.
– Hybrid vehicle techniques have been widely studied recently because of their potential to
significantly improve the fuel economy, drivability.
– Hybrid electric vehicles derives power from two different powers sources to run the vehicle.
– Since the fuel cell vehicles are still in development stage, hybrid vehicles are considered as fuel
efficient when compared to conventional IC engine vehicles.
• Types of HEV’s
– Series HEV: Electric motor is the means of providing power to the wheels.

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Introduction
Fundamentals
• Types of HEV’s
– Parallel HEV: both the engine and the motor are connected to the transmission and thus they can
power the vehicle either separately or in combination.
– Combined HEV: It can operate either in parallel or series, combining the advantages of both.
Hybrid Electric Vehicle

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Introduction
Fundamentals
• Advantages
– Hybrid electric vehicle can potentially improve fuel economy, emissions over the conventional
vehicle. This is because:
– The Engine size can be reduced with the same vehicle performance due to dual power sources.
– The Kinetic energy during braking can be captured and stored in battery using regenerative braking.
– Engine start & stop functionality in urban areas contributes to fuel economy.

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Introduction
Description
• Preface
– A parallel mild hybrid electric vehicle is chosen. A 60-kW diesel engine made by Mercedes-Benz was
used and a 12 kW permanent magnet synchronous motor was chosen as electric machine.
– An energy management strategy is introduced to reduce the fuel consumption by adhering to the
driver’s power demand by managing the power flow from the various energy storage devices and
maintaining the state of charge (SOC) of the battery within the desirable range.
– A Deterministic rule based control strategy was used for achieving this goal.
• QSS Toolbox
– The QSS TB gives basic idea to understand the modeling in MATLAB.
– The QuasiStatic Simulation Toolbox (QSS TB) permits a fast and simple estimation of the fuel
consumption for many powertrain systems.
• Elements of QSS Toolbox
– Driving Cycle: A comparison of the fuel consumption data of various drive systems are considered.

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Introduction
Description
– Typically, EU cycle and FTP cycle are used.
– Vehicle: This element is used by considering Aerodynamic losses, Rolling resistance losses and
Vehicle acceleration resistance losses (Inertia).
– Energy converter: Combustion Engine, Electric Motor and Generator and Fuel Cell are the energy
converters included in the QSS TB library.
– Gear system: The transmission of mechanical work between different levels of torque or rotational
speed, respectively, is possible due to either simple transmission or manual gear box or CVT.
– Energy Buffer: There are two types of energy buffers included in the QSS TB library, Battery & Super
capacitor.
– Energy Source: The total fuel mass is considered and divided by the total distance and transformed
in liters/100 km. The cold start losses are typically accounted for by multiplying the total fuel used
by a factor of 1.15.

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Introduction
Description
– Controller: Control systems in the QSS TB can be simple or quite complex. one example of a complex
controller system is a series hybrid system.
• Rule Based Control Strategy
– The rules for a Rule Based Control Strategy are designed based on heuristics, intuition, human
expertise, and even mathematical models and, generally, without a prior knowledge of a predefined
driving cycle.
– The main idea of rule based strategy is based on the concept of load leveling, which basically shifts
the load on the ICE in such a way that the ICE is operated at the optimal efficiency curve, fuel
consumption and emissions at particular engine speed.

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Modeling

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Operation modes

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Operation Modes

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Operation Modes

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Operation Modes
• Electric driving
– Efficiency of the engine low at low load points i.e. in urban traffic (low speeds).
– That means efficiency of the engine is also depends on speed
– By running the vehicle in electric mode at low speeds will result in good efficiency.
• Requirements
– The ratio of electric motor torque and manual gear box torque should be equal to 1.
– Constraints of motor, torque coupler and battery should be considered.
– Efficiency improvement must be larger than charging losses .
This can be implemented by using torque split ratio which is shown below
u = 1

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Operation Modes
• Start stop
– Operating the engine at idling condition will result in fuel consumption e.g. at traffic lights, traffic
jams.
– Stop of the engine during idling conditions will reduce the fuel consumption.
– Together electric driving and start stop will lead substantial reduction in fuel consumption.
• Requirements
– The ratio of electric motor torque and manual gear box torque should be equal to 1.
– Constraints of motor, torque coupler and battery should be considered.
– Start stop mode must be included with electric driving and regeneration.
This can be implemented by using torque split ratio which is shown below
u = 1

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Results

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Simulation
- Torque split ratio (u) characterizes the operation modes.
- The two power flows combined in Torque coupler (TC).
- The power balance can be controlled by selecting the Torque split ratio between secondary
power ( Electric motor ) and Engine.
Fig.1 Torque split ratio in NEDC Fig.2 Torque split ratio in FTP-75
Torque split ratio in NEDC Torque split ratio in
Results

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State of Charge
- Equal Battery charge is maintained at the beginning and end of the driving cycle.
- Charging and discharging of battery at various operating modes can be observed.
State of Charge in NEDC State of Charge in FTP-75
State of charge in NEDC
Results

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Results

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Results
Equivalent Fuel Consumption
- Fig.1,2. Compares the Equivalent fuel consumption of PHEV with the standard Conventional vehicle in
NEDC and FTP-75
Fig. 1 Eqiv fuel consumption Vs Time (NEDC) Fig. 2.Eqiv fuel consumption Vs Time (FTP-75)

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Results
Conventional Vehicle Vs Parallel Hybrid Vehicle
Table 1
Cycle
Standard Conventional
Vehicle Equiv. Fuel
Consumption
( L/100 Km)
Parallel Hybrid
Vehicle Equiv. Fuel
Consumption
( L/100 Km)
Fuel Saving
( L /100 km)
New European
Driving Cycle
(NEDC)
4.897 4.023 0.874
Federal Test
Procedure
( FTP-75)
4.675 3.591 1.084

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Results
• Contributions
– By implementing the proposed energy management strategy, there is a reduction in Fuel
Consumption as shown in Table 1 .
– The Fuel Reduction for an EU New European Driving Cycle (NEDC) is 17.9% and 23.2% for an US EPA
Federal Test Procedure (FTP-75).
– So, Overall Equivalent fuel consumption for Proposed Energy Management obtained is 20.55%.
–

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Results
– Hybridization has high potential in terms of fuel saving and maintaining Power requirements over
Conventional vehicle.
– Parallel HEV showed good fuel economy characteristics compared with a conventional vehicle with
the same power by using the load point shifting, pure electric driving and regenerative braking.
– The Fuel consumption is minimized at the end of driving cycle by subjecting the battery SOC
constraint and maintaining it to its initial state.
– Future work focus should be on further reduction in fuel consumption based on combination of
Rule-Based and Equivalent Consumption Minimization Strategies (RB-ECMS).
– Control strategy of engine Start – stop should be studied for further optimization.

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