An Investigation of Fuel Economy Potential of Hybrid Vehicles under Real-World Driving Conditions in Bangkok

In the transportation sector, the fuel consumption model is a fundamental tool for vehicles’ energy consumption and emission analysis. Over the past decades, vehicle-specific power (VSP) has been enormously adopted in a number of studies to estimate vehicles’ instantaneous driving power. Then, the relationship between the driving power and fuel consumption is established as a fuel consumption model based on statistical approaches. This study proposes a new methodology to improve the conventional energy consumption modeling methods for hybrid vehicles. The content is organized into a two-paper series. Part I captures the driving power equation development and the coefficient calibration for a specific vehicle model or fleet. Part II focuses on hybrid vehicles’ energy consumption modeling, and utilizes the equation obtained in Part I to estimate the driving power. Also, this paper has discovered that driving power is not the only primary factor that influences hybrid vehicles’ energy consumption. This study introduces a new approach by applying the fundamental of hybrid powertrain operation to reduce the errors and drawbacks of the conventional modeling methods. This study employs a new driving power estimation equation calibrated for the third generation Toyota Prius from Part I. Then, the Traction Force-Speed Based Fuel Consumption Model (TFS model) is proposed. The combination of these two processes provides a significant improvement in fuel consumption prediction error compared to the conventional VSP prediction method. The absolute maximum error was reduced from 57% to 23%, and more than 90% of the predictions fell inside the 95% confidential interval. These validation results were conducted based on real-world driving data. Furthermore, the results show that the proposed model captures the efficiency variation of the hybrid powertrain well due to the multi-operation mode transition throughout the variation of the driving conditions. This study also provides a supporting analysis indicating that the driving mode transition in hybrid vehicles significantly affects the energy consumption. Thus, it is necessary to consider these unique characteristics to the modeling process.

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“…The sampling rate was 1 Hz. This experiment covered more than 400 km of the OBD data amount with at least three repetitions per route [20].…”

Section: Real-world Experimentsmentioning

confidence: 99%

“…The sampling rate was 1 Hz. This experiment covered more than 400 km of the OBD data amount with at least three repetitions per route [20]. population density from high to low as labeled by red, brown, orange, and yellow, respectively.…”

Section: Real-world Experimentsmentioning

confidence: 99%

Development of Hybrid Vehicle Energy Consumption Model for Transportation Applications—Part II: Traction Force-Speed Based Energy Consumption Modeling

Pitanuwat

Aoki

Iizuka

et al. 2019

WEVJ

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“…Only some studies in the transportation research field have substituted actual vehicles' specific information, such as mass, aerodynamic-drag coefficient, rolling-resistance coefficient, and frontal area, into the driving-power equation [20]. Some studies also implemented a more complex rolling-resistance term by introducing C roll , C 1 , C 2 , and normal force action on the tires.…”

Section: Introductionmentioning

confidence: 99%

“…Table 1. Driving-power estimation classified by contributing factors [2][3][4]20,21,[23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Development of Hybrid-Vehicle Energy-Consumption Model for Transportation Applications—Part I: Driving-Power Equation Development and Coefficient Calibration

et al. 2020

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This study is the first of a two-part paper. The overall study presents a new methodology to improve the accuracy of hybrid vehicles’ energy-consumption model over conventional transportation modeling methods. The first paper attempts to improve an equation for vehicles’ driving-power estimation to be more realistic and specific for a particular vehicle model or fleet. The second paper adopts the driving-power equation to estimate the requested driving power. Then, the data are utilized to construct the hybrid-vehicle energy-consumption model, namely, the traction-force–speed-based energy-consumption model (TFS model). The main concept of the first paper is to utilize the power-split hybrid powertrain’s accessible on-board diagnostics (OBD) dataset, and its dynamic model to estimate the total propulsion power. Then, propulsion power was applied as the main parameter for driving-power equation development and vehicle-specific coefficient calibration. For coefficient calibration, this study implemented the stepwise multiple regression method to select and calibrate an optimal set of coefficients. Results showed that conventional driving-power equations Vehicle-Specific Power (VSP) LDV 1999 and VSP Prius3Spec provide low prediction fidelity, especially under high-speed (>80 km/h) and heavy-load driving (≥50 kW). In contrast, D r v P w P r i u s 3 , proposed in this study, effectively improved prediction to become more accurate and reliable through all driving conditions and speed ranges. It dramatically helped to reduce prediction discrepancy over the conventional equations at heavy-load driving, from an R-square of 0.79 and 0.78 to 0.96. D r v P w P r i u s 3 also the prediction error at high-speed driving from the maximal error of approximately −20 to −5 kW. This study also discovered that aerodynamics and rolling resistance were the primary factors that caused the prediction error of conventional VSP equations. In addition, results in this study showed that both of the approaches used to establish the P P T d r v and D r v P w P r i u s 3 equations were valid for a power-split hybrid vehicle’s driving-power estimation. For the coefficient-calibration part, the stepwise and multiple regression method is low-cost and simple, allowing to calibrate an appropriate set of optimal coefficients for a specific vehicle model or fleet.

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“…However, the benefit of the hybrid vehicle has not been giving any doubt to anyone recently. Researchers Pitanuwat and Sripakagorn [6] in their research have determined that hybrid vehicle is the most beneficial under the most difficult traffic conditions, i.e., where there are frequent, intense accelarations and breakings. When moving at a higher velocity and when the acceleration is less changing the difference between the fuel consumption of the conventional and the hybrid vehicle makes up only 21...26%.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Conventional and Hybrid Cars Exploitation Costs

Pukalskas¹,

Rimkus²,

Melaika³

et al. 2018

Adv. Sci. Technol. Res. J.

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The paper analyzes three different, but similar class cars, two of them with conventional spark ignition (SI) engines, and one -hybrid (SI + electricity). Statistics of fuel consumption and mileage of several years are presented and analyzed, fuel price changes and provided exploitation costs. The analysis shows that in countries where are no privileges for the acquisition of hybrid cars or for operation (less parking or tolls, insurance or technical inspection price), the payback is hardly possible, because the hybrid car's price is about 2 times higher than that of a normal car, and fuel costs are reduced merely by about 20%. The results of the analysis show that payback of the hybrid car (at current fuel prices), in the best case possible after 0,73 million kilometers. Within annual mileage an average of 25 thousands km, the hybrid car will payback after 30 years!

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An Investigation of Fuel Economy Potential of Hybrid Vehicles under Real-World Driving Conditions in Bangkok

Cited by 25 publications

References 11 publications

Development of Hybrid Vehicle Energy Consumption Model for Transportation Applications—Part II: Traction Force-Speed Based Energy Consumption Modeling

Development of Hybrid Vehicle Energy Consumption Model for Transportation Applications—Part II: Traction Force-Speed Based Energy Consumption Modeling

Development of Hybrid-Vehicle Energy-Consumption Model for Transportation Applications—Part I: Driving-Power Equation Development and Coefficient Calibration

Comparison of Conventional and Hybrid Cars Exploitation Costs

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