Project 2
A hybrid system that is connected directly to the crankshaft of the engine with some type of clutch/fluid coupling between the electric motor and the gearing.
This Drivetrain operates on feedback signals. Output Velocity from the Powertrain is fed into the Driver which then generates the Acceleration and Brake. The same Acceleration and Brake are fed into the Controller as input and are used for the rest of the operations.
Controller:-
There is a different kinds of Controllers, one is the Supervisory Controller and the others are the Control Units. The input data for the Control Units come from the Supervisory Controller. The supervisory Controller has conditions to follow which directly depend on the Driver's action and based on the same, the control signals are given to the other Control Units.
Supervisory Controller has modes/States like to Stop, Start, Drive, and Regenerative Breaking. Based on the input from the Driver different Modes are selected by the Supervisory Controller for the Vehicle.
Engine Control Unit
In the existing Engine Control Unit for the Conventional Vehicle, there are some changes made to be a Hybrid Drivetrain. New input signals are implemented like 'Eng_on'. The logic behind this is to make the Vehicle more Fuel efficient by turning off the engine whenever it is not required.
Idle Speed Controller
The same logic is applied here as Engine Control Unit. The idle speed is made to be 0 whenever the Engine is off. The 'Eng_on' input signal is used with the 'Eng_idle_spd' with the product block for the logic to implement.
Transmission Control Unit
A 'Memory' block is used in the existing Transmission Control Unit for Conventional Vehicle. Memory block outputs the input from the previous time step. The Memory block holds and delays its input by one major integration time step. When placed in an iterator subsystem, it holds and delays its input by one iteration.
Using the 'Throttle' and 'VehicleSpeed' input signals it is controlling the gears. Depending on the vehicle speed ShiftLogic is upshifting and downshifting the gears. At Gear more than or equal to 3rd gear, it gives the 'Clutchlockup' signal to the vehicle.
EM Control Unit
Engine Machine Control Unit block is operating using the 'EngSpd' signal. By using the Engine Speed, EM Control Unit is giving 'EMTrqReq' which is Engine Machine Torque Requirement. Engine Speed data is used for the maximum and minimum Torque for the EM, which is then decided using the 'Switch' block, where the threshold is the product of the 'EM_Throttle' divided by 100.
There is also a 'rate Limiter' block used to limit the range of the Torque requirement for the EM Control Unit.
Powertrain:-
This is a P1 Hybrid Powertrain architecture which has an electric Machine connected parallel to the 'Engine' and both are connected to the 'Crankhub' of the Vehicle. It also has a 'Ess' which is an Energy Storage System or Battery for P1 Hybrid Vehicle.
Engine
Compare to the Conventional Vehicle everything remains the same, the only thing implemented is the 'Eng_On' 'From' signal from the Supervisory Controller. It operates on the 'EngSpd' and 'EngTrqreq' which is the Engine Torque requirement and gives the 'EngTrq' of the Vehicle.
Engine block uses a similar concept of generating Engine Torque as an Electric Machine, using the input signal 'Engine Speed' with the maximum and minimum torque and passing through the 'Switch' block. Considering 'EngTrqReq' as a threshold value.
From the Engine block, 'Eng_Fuel_Rate' and 'Eng_ Fuel_Consumption' can find out. Eng_On signal will make the Engine Fuel Consumption 0 whenever the engine is turned off. As Fuel Consumption is the product of the saturated max Torque and Eng_On signal.
Electric Machine
Electric Machine which is connected to the crankshaft of the Engine. EM also uses the same method of generating 'EMTrq' which is the Torque of the EM as the Engine generating Engine Torque using a 'Switch' block condition. It also got the input signal as Engine Speed and 'EMTrqReq' which is the threshold value for the Switch condition.
In Electric Machine block it is using the method of Power as the product of Torque and Speed. By using the same method with a '2D lookup table' data 'ElecPwr' of the vehicle is generated.
Crankhub
Crankhub block is adding both the Torque values (Engine Torque & EM Torque) for the vehicle and generates 'CrankTrq'. This CrankTrq is further used in the Vehicle.
Energy Storage System (ESS)
Energy Storage System or the Battery of the HEV is the storage system of the Electric Machine. It uses the generated Electric Power from the Electric Machine which is then divided with the 'Voltage' (feedback signal from the 'Terminal_Voltage' subsystem) to produce 'Current'.
Energy Storage System determines the 'SOC' (State of Charge) signal of the Vehicle. The state of charge (SOC) of a cell/battery denotes the capacity that is currently available as a function of the rated capacity. The value of the SOC varies between 0% and 100%. If the SOC is 100%, then the cell/battery is said to be fully charged, whereas a SOC of 0% indicates that the cell/battery is completely discharged.
Transmission
The transmission transfers mechanical power from the engine and/or electric traction motor to drive the wheels. It uses inputs like CrankTrq, TransInSpd, and Clutchlockup for the 'Torque Converter' to get 'TransInTrq'. Product of 'GearRatio' (Rate Limited) and TransInTrq gives the 'TransOutTrq'.
It also generates 'TransInSpd' using the product signal of TransOutTrq and 'GearRatio' (Rate Limited).
Torque Converter
Torque Converter is generating the transmission input torque from 'TrubineTrq' and 'CrankTrq', and 'TrubineTrq' is generated from 'TrqRatio' and 'PumpTrq'. It uses the Engine Dynamics which subtracts the PumpTrq from CrankTrq and the product of that is divided by the inertia (Eng_inertia+EM_inertia) to give the PumpSpeed.
To select from Turbine speed and Pump speed, the Switch condition is used where the threshold is Clutchlockup at 0. So if the clutch is close Turbine speed will be considered or vice versa.
Fuel Economy (kmpl):-
Drive Cycle UDDS
The EPA Urban Dynamometer Driving Schedule (UDDS) is commonly called the "LA4" or "the city test" and represents city driving conditions. It is used for light-duty vehicle testing. The UN/ECE Regulation 53 refers to the EPA UDDS as the "Test Equivalent to the Type 1 Test (verifying emissions after a cold start)."
Fuel economy is 14.2044 [kmpl] (Project 1)
Fuel economy is 26.4945 [kmpl] (Project 2)
Drive Cycle HWFET
The Highway Fuel Economy Driving Schedule (HWFET) represents highway driving conditions under 60 mph.
Fuel economy is 16.5010 [kmpl] (Project 1)
Fuel economy is 36.9793 [kmpl] (Project 2)
As per the Drive Cycles, in the city condition, the fuel economy is not as great/much as in the highway condition. This is the same in both Project 1 and Project 2. This is because generally in the city condition due to more traffic, waiting time for the vehicle increases, and also, starting and stopping the vehicle repeatedly due to traffic consumes more fuel. Gives more fuel consumption and also increases the fuel rate resulting in less fuel economy than that highways.
Plots:-
UDDS Drive Cycle
Time trace for the engine
Comparing plots for both the drive cycles, the brake pedal has more movements in city conditions and less or remains constant for most of the time in highway conditions. It can also be seen that with an increase in gear, the accelerator pedal increases and there is no movement with the brake pedal. The speed increases with the moment of transmission input and output. Speed seems to be zero when there is movement in the brake pedal.
The vehicle reaches max gear only once in this UDDS drive cycle, the maximum time it is in 2nd or 3rd gear. Whereas in HWFET drive cycle vehicle is in 3rd or highest gear which at 4th most of the time.
HWFET Drive Cycle
Time trace for the engine
Max curve remains the same for both the drive cycles. Operating points of the UDDS drive cycle seem to be moving at a slower pace to higher Engine Speed from starting. But not in the case of the HWFET drive cycle, operating points move towards a higher speed at an instant from the starting point. Operating points on the highway seem more stable than in the city condition.