HEV Modelling & Optimization - Deepak Chandran Praveen S R
HEV Modelling & Optimization
- Deepak Chandran
Praveen S R
Objective
• To analyze the existing test data of the 2015 Honda Accord,determine the control strategy and model the same for a 1.4 UDDStest cycle data.
• To optimize the parallel mode region and deduce the change in MPG.
STEPS INVOLVED IN OPTIMIZATION
Reverse Engineering existing Test data
Obtain Parallel mode region
Use the above control strategy to model Accord HEV for a 1.4 UDDS cycle
Analysis of test data
The fuel economy and electrical energyConsumption for the given UDDS cycle ofThe test data has been calculated.
Time(s) vs SOC vs Speed (MPH) for the given cycle is plotted.
Similar analysis has been performed onDifferent cycles to obtain more data Points.
Obtaining Parallel operation in UDDS
To obtain the parallel region of operation for the given UDDS cycle, ratio of vehicle speed(MPH) and Engine Speed (rpm) was plotted against time(s). The region of constant ratio (0.027) was selected as the parallel operating mode.
Tractive Force Battery Current(A)
EV only Positive (Pretransmission power < ENG ON)
Positive
Engine (ParallelMode)
Positive Negative
Engine only (Series Mode)
Positive(Wheel demand > Engine power)
Negative
Engine (assist mode)
Positive(Pretransmission power > ENG ON)
Positive
Regen Mode Negative Negative
Parallel region analysis
Data points obtained from cycles Were plotted with respect to Tractive effortAnd Speed.
2 HWY 2 US 06 2 UDDS
Parallel operating region was determined As Speeds >45 MPH and Force <900N
HEV Modelling
Based on the control strategy obtained earlier we have modelled a HEV operating in 1.4 UDDS .
We have obtained a fuel economy analysis with the NETC tolerance limits.
Tractive Force Battery Current(A)
EV only Positive (Pretransmission power < ENG ON)
Positive
Engine (ParallelMode)
Positive Negative
Engine only (Series Mode)
Positive(Wheel demand > Engine power)
Negative
Engine (assist mode) Positive(Pretransmission power > ENG ON)
Positive
Regen Mode Negative Negative
Determination of Engine Power & Fuel Consumption –RSM Model
WW = -1.70711E-1 +2.17320E-4 * A2 +9.11151E-3 * B2 -1.41102E-9 * A2^2 +1.63838E-6 * A2B2 -1.09140E-4 * B2^2 -5.04269E-12 * A2^3 +9.58023E-10 * A2^2B2 -6.44252E-9 * A2B2^2 +6.38647E-7 * B2^3
For N < 2000 rpm, T = 0.015 * N + 60
For N > 2000 rpm & N < 2500 rpm, T = 0.04 * N + 10
For N > 2500, T = 0.02 * N + 60
Basis of Optimization
Reasons for picking Highway Cycle
In a highway cycle, vehicle is more often at high speeds and steady state. This lea to more opportunity for parallel analysis (High speed and Low traction conditions)
STEPS INVOLVED IN OPTIMIZATION
Reverse Engineering existing Test data
Obtain Parallel mode region
Modify speed and torque of Parallel Mode region of HWY data
Assumptions
• Pre-transmission wheel demand and opportunity charging are the same.
• Engine efficiency is 40% instead of 42% since it operates at a lesser power region.
THANK YOU