Measurement and Analysis of Indian Road Drive Cycles for Efficient and Economic Design of HEV Component

Drive cycle pattern is different for different countries which depends on their traffic density, road condition and driver discipline. Drive cycle influences HEV`s components design, sizing and their ratings. Standard drive cycle data doesn't reveal much information to determine efficient and economic design of HEV`s components. In this research paper measurement and analysis of real time Indian road drive cycles (IRDC) are carried out for urban roads, state highway, national highway and express Highway where vehicles have their most run. Real time drive cycle data will expose impact of driver’s skills, traffic, road conditions and short acceleration / deceleration period, which can be represented on drive cycle chart. Analysis of IRDC in terms of rate of acceleration and deceleration, top speed, average speed with road length and analysed mathematically to find energy and power required for acceleration, normal operation and energy harvested during deceleration. Based on information from IRDC HEV`s components initial size are estimated. Initial estimated size is optimized to make HEV`s components design more efficient and economic. Teaching and learning based optimization algorithm (TLBO) and Multi objective genetic algorithm (MOGA) are used to optimize HEV`s components. Constraint of optimization algorithm are like engine and motor rating should be selected such that it has effective top speed with enough acceleration capability and can run enough distance to reach destination according to Indian urban, state, national and express highway pattern where cities are very closed compared with other countries and its regeneration component design should able to harvest maximum deceleration energy. For economic operation of HEV’s, running cost in terms of Rs. / Km. should be minimum.

Throughout the paper parallel configuration of HEV is considered which is explained in section 2. Information about real time drive cycle a method measurement on different Indian roads and its analysis cycle is done in section 3, Modelling of HEV`s components is done in section 4. In section 5, initial estimation of components is done by considering parameters of drive cycle. In section 6 initial estimation value is optimized by TLBO method which is new and never used for HEV`s component size optimization and MOGA method to make comparison. Economical comparison is shown in section 7. Result of all method of optimization is shown in section 8 and it is concluded in section 9.

System Configurations
HEV`s components design is done for medium size vehicle. Various drive train configurations can be used for HEV. Selection of drive train pattern depends upon application. In this paper parallel drive train configuration is used. Parallel drive train requires less space compared to series configuration and is suitable for use in medium sized car. Series configuration is used for heavy duty application and its drive train requires additional generator space. Figure 1 Shows block diagram of Parallel drive train configuration. For parallel drive train configuration battery, fuel tank, IC engine, motor and inverter, splitter which splits load between IC engine and electric motor and this entire set of components are connected to the a load.

Drive cycle measurement
The driving cycle is sequence of vehicle operating condition i.e. idling, acceleration, cruise, creeping and declaration with respect to time for a given city, region or a country. Indian roads are categorized in four ways which are (i) express highway (ii) national highway (iii) state highway (iv) urban roads/rural road [4]. So, the selection of population and road is very crucial while planning drive cycle measurement program. All type of Roads should be covered. Vehicle selection is also very crucial. Vehicle of similar rating should be selected as rating of HEV to be designed. Vehicle which is most economic while running is selected to start drive cycle measurement program. Table 1 shows parameters of vehicle to determine drive cycles.

Vehicle Dynamics
Vehicle dynamics are considered for calculation performance parameter of HEV. Vehicle's calculates performance parameter like its horsepower requirement, speed, torque, and acceleration & deceleration power can be determined by vehicle dynamics.   Figure 4 shows parameters of dynamic vehicle used for equations. This resistance are summed up to get actual power used during vehicle dynamics calculation.

Modelling of HEV`s components
From IRDC analysis battery kilo watt requirement, hour requirement, size of motor, size of IC engine and fuel tank is determined. The seizing is done for parallel configuration of HEV which is simulated in MATLAB Simulink. Data taken from table 2 are average HP and maximum HP to determine average power require by motor and IC engine and peak power required by the same and deceleration power to estimate power of battery and its recharging from deceleration energy. From those mean value of each parameter is considered [28]. All component size estimation and its optimization will be tested in MATLAB Simulink model. Parallel HEV model is modelled in MATLAB Simulink. Brushless DC Motor, Lead-Ion Battery, IC Engine same as motor rating is selected as component of HEV.
For simulation and modelling of parallel configuration of HEV, modelling equations are mentioned below.

Brushless DC motor model [23]
Modelling equations of brushless DC motor

Throttling model [24]
Throttle model is done by making look up table from standard throttle opening to fuel output graph of IC engine.

IC engine model [25]
B From this simulation model parameters like SOC%, fuel consumption, battery consumption torque & horsepower production will be analysed.

Influence of drive cycle in HEV`s components sizing
The main component of HEV`s power train are battery storage, power rating of electric machine and size and rating of IC engine and it's fuel tank capacity [20]. All this components mainly determines initial cost of HEV`s power train. Running cost is determined by fuel/battery power consumption.
To determine components size of HEV first step is to collect data of real time drive cycles of roads where HEV is to be driven. Influence parameter for battery ampere-hour rating is determined by how long vehicle has to be travelled which average distance of different is charging station and acceleration power requirement of motor. Similarly size of IC engine and motor is determined by average power and peak power required to fulfil drive cycle load requirement [19]. Deceleration energy determines rating recharging circuit which should be capable of holding and harvesting deceleration power. Deceleration and acceleration power is higher in urban roads and state highway while it is considerably less in express highway. From figure 5 and 6 initial component size can be estimated. Initial estimation is done to begin designing process of HEV`s component. Initial estimation of components is derived without keeping any constraint by simply finding means of drive cycle parameters. Initial sizing is done by mean value method and results are; Motor rating = 60hp IC engine rating = 60hp Battery rating = 22.7kw Fuel Tank = 22lit. Initial sizing is not done by any algorithm or any designing method but simply by considering the influence of drive cycle on HEV`s component sizing and from table 3 which shows mean load demand [27]. From this initial sized data of component, optimization will be done with consideration of constraints.

Economy
Economy of running HEV is based on electricity and fuel prices on year 2015. It is calculated in terms of Rs/km. Rs/km for convectional IC engine and HEV which contains design component are calculated [27]. How much money needed to be spent for kilometre ride for any drive cycle is compared in result.