Series Hybrid Electric Vehicle Research Articles

Operating Point Optimization of Auxiliary Power Unit Based on Dynamic Combined Cost Map and Particle Swarm Optimization

Series hybrid electric vehicles improvements in fuel consumption and emissions directly depend on the operating point of the auxiliary power unit (APU). A new APU operating point optimization approach based on dynamic combined cost map (DCM) and particle swarm optimization (PSO) is presented in this paper. The influence of coolant temperature, catalyst temperature, and air/fuel (A/F) ratio on fuel consumption characteristics and HC, CO, NOx emission characteristics are quantitatively analyzed first. Then, the DCM is derived by combining the individual cost maps with predefined weighting factors, so as to balance the potentially conflicting goals of fuel consumption and emissions reduction in the choice of operating point. The PSO is utilized to search the optimum APU operating point in the DCM. Finally, bench experiments under three typical driving cycles show that, compared with the results of the traditional static steady-state fuel consumption map-based APU operating point optimization approach, the proposed DCM and PSO-based approach shows significant improvements in emission performance, at the expense of a slight drop in fuel efficiency.

Operational efficiency comparison on eco-friendly vehicles including dynamic wireless charging

Eco-friendly vehicle technologies for commercial bus applications, such as a plug-in series-hybrid electric vehicle (SHEV), a pure battery electric vehicle (BEV), and an electric vehicle (EV) with dynamic wireless charging electric vehicle (DWEV), are analyzed in view of operational efficiency by calculating the optimized energy consumption from simulation based upon derived specifications of each power drive system. By developing proper vehicle driving modelling and controllers to achieve the required performances of different types of commercial buses, energy consumption and efficiency analysis over NY Manhattan (NY), the High Speed Heavy Duty Diesel Truck (HHDT), and the actual measured ‘on-campus’ drive cycles are performed for equivalent and practical comparison. Typical driving behaviors, vehicle headways, and dynamic wireless charging phenomena associated with the on-board battery energy capacity are considered. For DWEV, several different schemes of installing an on-road powered track for stationary and dynamic on-road charging are compared. The overall operational efficiency of the BEV and the DWEV, in view of energy cost, showed higher than that of the SHEV. Compared with the baseline CNG-engine bus, the energy consumption reductions, in view of energy cost, were found to be 10% for the SHEV, 60% for the BEV, and 65% for the DWEV.

Encyclopedia of automotive engineering

Encyclopedia of automotive engineering

Development of a power management strategy to minimize the fuel consumption of a heavy-duty series hybrid electric vehicle

This paper presents a power management strategy to minimize the fuel consumption of a heavy-duty series hybrid electric vehicle. The vehicle model, which consists of a CNG engine, a generator, two driving motors and a battery, is developed and validated with experimental data. Dynamic programming (DP) is applied to design a control algorithm optimizing fuel consumption of the series hybrid electric vehicle. By imitating the behavior of the DP control signal, a rule-based control algorithm is proposed. The controller actuates the CNG engine, generator, and battery to minimize fuel consumption and maintain the battery state of charge within a proper region. Simulation studies and experiments are conducted for typical driving modes to investigate the performance of the proposed power management strategy. Results indicate that fuel economy can be enhanced by approximately 30% using the proposed power management strategy to the series hybrid electric vehicle over the conventional vehicle.

A Novel Equivalent Consumption Minimisation Strategy for a Series Hybrid Electric Vehicle

A Novel Equivalent Consumption Minimisation Strategy for a Series Hybrid Electric Vehicle

Energy Efficiency Comparison between Hydraulic Hybrid and Hybrid Electric Vehicles

Conventional vehicles tend to consume considerable amounts of fuel, which generates exhaust gases and environmental pollution during intermittent driving cycles. Therefore, prospective vehicle designs favor improved exhaust emissions and energy consumption without compromising vehicle performance. Although pure electric vehicles feature high performance and low pollution characteristics, their limitations are their short driving range and high battery costs. Hybrid electric vehicles (HEVs) are comparatively environmentally friendly and energy efficient, but cost substantially more compared with conventional vehicles. Hydraulic hybrid vehicles (HHVs) are mainly operated using engines, or using alternate combinations of engine and hydraulic power sources while vehicles accelerate. When the hydraulic system accumulator is depleted, the conventional engine reengages; concurrently, brake-regenerated power is recycled and reused by employing hydraulic motor–pump modules in circulation patterns to conserve fuel and recycle brake energy. This study adopted MATLAB Simulink to construct complete HHV and HEV models for backward simulations. New European Driving Cycles were used to determine the changes in fuel economy. The output of power components and the state-of-charge of energy could be retrieved. Varying power component models, energy storage component models, and series or parallel configurations were combined into seven different vehicle configurations: the conventional manual transmission vehicle, series hybrid electric vehicle, series hydraulic hybrid vehicle, parallel hybrid electric vehicle, parallel hydraulic hybrid vehicle, purely electric vehicle, and hydraulic-electric hybrid vehicle. The simulation results show that fuel consumption was 21.80% lower in the series hydraulic hybrid vehicle compared to the series hybrid electric vehicle; additionally, fuel consumption was 3.80% lower in the parallel hybrid electric vehicle compared to the parallel hydraulic hybrid vehicle. Furthermore, the hydraulic–electric hybrid vehicles consumed 11.4% less electricity than the purely electric vehicle did. The simulations indicated that hydraulic-electric hybrid vehicle could provide the best energy cost among all the configurations studied.

Cooperative control of regenerative braking and friction braking for a hybrid electric vehicle

In this paper, a rear-wheel-driven series hybrid electric vehicle which has a mechanically operated friction brake system is studied. A new cooperative control of regenerative braking and friction braking called ‘combined braking’ is proposed for this vehicle configuration. A mechanism to adjust the proportions of regenerative braking and friction braking was proposed in this paper. Further, the braking force distribution between the front wheels and the rear wheels was analysed to ensure stable braking. The brake system characteristics were considered to ensure that the driver’s feel remains the same in the new proposed combined braking strategy. The simulation results under urban driving and across the Modified Indian Driving Cycle and vehicle road testing results show that the proposed combined braking can regenerate more than twice the braking energy of conventional parallel braking. Also, with combined braking, the braking force distribution between the front wheels and the rear wheels is closer to the ideal braking force distribution curve, which is desirable to ensure stable braking.

Selection of appropriate working fluids for Rankine cycles used for recovery of heat from exhaust gases of ICE in heavy-duty series hybrid electric vehicles

Recently, the waste heat recovery system is studied for application in vehicles to improve fuel economy. Especially, Rankine cycle is representative and attractive technology as waste heat recovery system. In order to maximize efficiency of Rankine cycle in the vehicle application, selection of optimal working fluid is important. Thus, in this study, thermodynamic analysis with consideration of practical operating condition was conducted to find out optimal working fluids. Thermodynamic efficiency, recovery efficiency, and overall cycle efficiency were adopted to estimate Rankine cycle performance. In order to reflect practical operating condition on the analysis, limitations due to working fluid physical properties and components specifications are taken into account. 5 working fluids including dry and wet fluid were used to estimate efficiency. Consequently, R245fa which shows high efficiency and environment-friendly is suggested as optimal working fluid in vehicle application.

Reducing Soot Emissions in a Diesel Series Hybrid Electric Vehicle Using a Power Rate Constraint Map

This paper considers a diesel series hybrid electric vehicle (SHEV) and proposes the utilization of an engine-generator power rate constraint map to reduce soot emissions without a significant compromise in fuel economy. Specifically, model predictive control (MPC) is used to split the vehicle power demand between the engine-generator unit and the battery. To achieve a reduction in soot, the engine-generator power rate is constrained. Unlike existing strategies, the power rate limit is not a fixed value but varies, depending on the power level, resulting in a map. This constraint map is designed by formulating the soot emission reduction problem as an optimization problem, which is solved through a three-step offline discrete optimization process. The optimization relies on a quasi-static soot emissions map that captures the trends, even during transients, but underestimates the magnitudes. Therefore, to evaluate the performance of the MPC-based power management with the power rate constraint map, experiments are conducted through an engine-in-the-loop simulation framework. Experimental results show that compared with a constant power rate constraint, soot emissions can be reduced by 44.5% while compromising fuel economy by only 0.3% through the proposed approach. As a tradeoff, the ampere-hour (Ah) processed in the battery, which is a variable that has been shown to correlate with battery capacity loss, increases by 5.5%.

System Integration for the Environmental Friendly Electric Vehicle

This paper introduced a new power flow control strategy for a variable speed engine-generator based range-extended electric vehicle. The specific fuel consumption map of the internal combustion engine (ICE) has been obtained by off-line experiments to achieve optimal fuel efficiency. Finally, a typical range-extended electric vehicle is modeled and investigated such as acceleration traversing ramp, maximum speed, fuel consumption and emission are performed on the dynamic model of a range-extended electric vehicle. The energy consumption and cost were compared to tradition range-extended electric vehicle. Computer simulation results obtained, confirm the validity and performance of the proposed power flow control approach using for series hybrid electric vehicle.

Evaluation Methodology and Control Strategies for Improving Reliability of HEV Power Electronic System

The reliability prediction of hybrid electric vehicles (HEVs) is of paramount importance for planning, design, control, and operation management of vehicles, since it can provide an objective criterion for comparative evaluation of various configurations and topologies and can be used as an effective tool to improve the design and control of the overall system. This paper presents a mission-profile-dependent simulation model based on MATLAB for quantitatively assessing the reliability of the electric drivetrain of HEVs. This model takes into consideration the variable driving scenarios, dormant mode, electrical stresses, and thermal stresses. Therefore, more reliable and accurate prediction of system reliability has been achieved. The methodology is explained in detail, and the results of reliability assessment based on a series HEV are presented. Based on reliability analysis, two control strategies are proposed to increase the mean time to failure of HEV powertrains: 1) variable dc-link voltage control and 2) hybrid discontinuous pulsewidth modulation scheme. These novel control schemes reduce the power losses and thermal stresses of power converters, and consequently, enhance system reliability. Numerical simulation results verify the benefits of two proposed control strategies in terms of power losses and reliability.

Supervisory Power Management Control Algorithms for Hybrid Electric Vehicles: A Survey

The growing necessity for environmentally benign hybrid propulsion systems has led to the development of advanced power management control algorithms to maximize fuel economy and minimize pollutant emissions. This paper surveys the control algorithms for hybrid electric vehicles (HEVs) and plug-in HEVs (PHEVs) that have been reported in the literature to date. The exposition ranges from parallel, series, and power split HEVs and PHEVs and includes a classification of the algorithms in terms of their implementation and the chronological order of their appearance. Remaining challenges and potential future research directions are also discussed.

Real-time control strategy to maximize hybrid electric vehicle powertrain efficiency

The proposed supervisory control system (SCS) uses a control map to maximize the powertrain efficiency of a hybrid electric vehicle (HEV) in real-time. The paper presents the methodology and structure of the control, including a novel, comprehensive and unified expression for the overall powertrain efficiency that considers the engine-generator set and the battery in depth as well as the power electronics. A control map is then produced with instructions for the optimal power share between the engine branch and battery branch of the vehicle such that the powertrain efficiency is maximized. This map is computed off-line and can thereafter be operated in real-time at very low computational cost. A charge sustaining factor is also developed and introduced to ensure the SCS operates the vehicle within desired SOC bounds. This SCS is then tested and benchmarked against two conventional control strategies in a high-fidelity vehicle model, representing a series HEV. Extensive simulation results are presented for repeated cycles of a diverse range of standard driving cycles, showing significant improvements in fuel economy (up to 20%) and less aggressive use of the battery.

Control and HIL Simulation of Series Hybrid Electric Vehicles Based on Dynamic Programming Algorithm

Hybrid electric vehicles has the potential to save energy consumption and relieve exhaust gas emission while the power flow control techniques are very important for improving a hybrid electric vehicle’s performance. In this paper, the system simulation and control method of series hybrid electric vehicles were proposed. The control method was based on enhancing the energy transfer efficiency based on dynamic programming algorithm. The hardware in the loop (HIL) simulation was constructed containing a real-time driver and controller in the simulation platform, which can be used to evaluate the proposed strategy.

The Fuel Economy of Hybrid Buses: The Role of Ancillaries in Real Urban Driving

In the present context of the global economic crisis and environmental emergency, transport science is asked to find innovative solutions to turn traditional vehicles into fuel-saving and eco-friendly devices. In the last few years, hybrid vehicles have been shown to have potential benefits in this sense. In this paper, the fuel economy of series hybrid-electric and hybrid-mechanical buses is simulated in two real driving situations: cold and hot weather driving in the city of Taranto, in Southern Italy. The numerical analysis is carried out by an inverse dynamic approach, where the bus speed is given as a velocity pattern measured in the field tests performed on one of the city bus routes. The city of Taranto drive schedule is simulated in a typical tempered climate condition and with a hot temperature, when the air conditioning system must be switched on for passenger comfort. The fuel consumptions of hybrid-electric and hybrid-mechanical buses are compared to each other and with a traditional bus powered by a diesel engine. It is shown that the series hybrid-electric vehicle outperforms both the traditional and the mechanical hybrid vehicles in the cold weather driving simulation, reducing the fuel consumption by about 35% with respect to the traditional diesel bus. However, it is also shown that the performance of the hybrid-electric bus gets dramatically worse when the air-cooling system is continuously turned on. In this situation, the fuel consumption of the three different technologies for city buses under investigation is comparable.

Design to Reduce Cost and Improve the Mechanical Durability of IPMSM in Traction Motors

The interior permanent-magnet synchronous motor (IPMSM) is often used for the traction motor of hybrid electric vehicles (HEVs) and electric vehicles (EVs) due to its high power density and wide speed range. This paper introduces the 120kW class IPMSM for traction motors in military trucks. This system, as a SHEV (series hybrid electric vehicle), requires a traction motor that can generate high torque. This study introduces a way to reduce costs by proposing a design approach that creates reluctance torque that can be maximized by varying the dq-axis inductance. If a model designed by a design approach meets the desired torque, the magnetic torque can be reduced by an amount equal to the increase in reluctance torque and consequently the amount of permanent magnets can be reduced. A reduction gear and high speed operation of motors are necessary for the miniaturization of the motor. Thus, a fairly large centrifugal force is generated due to the high speed rotation. This force causes mechanical interference between the rotor and the stator, and a design approach for adding an iron bridge is explained to solve the interference. In this study, the initial model and the improved model that reduces cost and improves mechanical durability are compared by FEA, and the models are produced. Finally, the FEM results were verified experimentally.

Packaging Improvement for Unit Cell Vanadium Redox Flow Battery (V-RFB)

Packaging for vanadium redox flow battery is one of the key elements for successful implementation of flow battery in the electrical energy storage system. Usually the bulky battery size and low energy densities make this technology not available for mobility application. ThereforeRFB with improved packaging size and energy capacity are highly desirable. This paper focuses on the study of packaging improvement for unit cell V-RFB to the application on Series Hybrid Electric Vehicle. Two different designs of 25cm2 and 100cm2 unit cell V-RFB at same current density are used for the sample in this investigation. Further suggestions on packaging improvement are highlighted.

Dual rotor single- stator axial air gap PMSM motor/generator drive for high torque vehicles applications

The actual e – continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV. In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors, destined for hybrid electric vehicles (HEV) and military vehicles applications. The proposed topologies and the magneto-motive force analysis are the core of the paper.

A neurofuzzy-controlled power management strategy for a series hybrid electric vehicle

This paper focuses on the design of the power management strategy as the key factor in improving the performance in terms of the efficiency, the range and the fuel consumption for a small-scale series hybrid electric vehicle. A complex hybrid vehicle system is considered, and a practically realisable and traceable neurofuzzy strategy for improving the vehicle efficiency is introduced. The method results in extending the vehicle’s range while deciding when to switch the internal-combustion engine on or off as a function of the state of charge of the battery and the electrical power produced from the generator. Consequently, the speed of the internal-combustion engine (i.e. the current produced) is determined as a function of the driving conditions. Suitable tests were performed in order to verify the effectiveness of the proposed strategy; the verification tests were carried out using a consolidated model which also includes real-world experimental vehicle data. The results show that, by using the proposed power management strategy, a good compromise between the efficiency, the range and the fuel consumption can be obtained in many practically useful driving conditions.

Modeling and Control Strategy of Series Hybrid Electric Vehicles

The modeling method and control strategy for series hybrid electric vehicles were presented in this paper. Firstly, the system structure and operation principles are discussed systematically; and then a control strategy is proposed based on the modeling of powertrain. Control strategy focus on the multi-modes switch logic and power distribution. In the last part of this paper, the simulation made in MATLAB/Simulink was introduced, which results indicate that the model and control strategy are correct.