Series Hybrid Research Articles

Efficiency enhancement strategy implementation in hybrid electric vehicles using sliding mode control

Introduction. Hybrid electric vehicles are offering the most economically viable choices in today's automotive industry, providing best solutions for a very high fuel economy and low rate of emissions. The rapid progress and development of this industry has prompted progress of human beings from primitive level to a very high industrial society where mobility used to be a fundamental need. However, the use of large number of automobiles is causing serious damage to our environment and human life. At present most of the vehicles are relying on burning of hydrocarbons in order to achieve power of propulsion to drive wheels. Therefore, there is a need to employ clean and efficient vehicles like hybrid electric vehicles. Unfortunately, earlier control strategies of series hybrid electric vehicle fail to include load disturbances during the vehicle operation and some of the variations of the nonlinear parameters (e.g. stator’s leakage inductance, resistance of winding etc.). The novelty of the proposed work is based on designing and implementing two robust sliding mode controllers (SMCs) on series hybrid electric vehicle to improve efficiency in terms of both speed and torque respectively. The basic idea is to let the engine operate only when necessary keeping in view the state of charge of battery. Purpose. In proposed scheme, both performance of engine and generator is being controlled, one sliding mode controllers is controlling engine speed and the other one is controlling generator torque, and results are then compared using 1-SMC and 2-SMC’s. Method. The series hybrid electric vehicle powertrain considered in this work consists of a battery bank and an engine-generator set which is referred to as the auxiliary power unit, traction motor, and power electronic circuits to drive the generator and traction motor. The general strategy is based on the operation of the engine in its optimal efficiency region by considering the battery state of charge. Results .Mathematical models of engine and generator were taken into consideration in order to design sliding mode controllers both for engine speed and generator torque control. Vehicle was being tested on standard cycle. Results proved that, instead of using only one controller for engine speed, much better results are achieved by simultaneously using two sliding mode controllers, one controlling engine speed and other controlling generator torque.

Effect of input shaft torque control during gear shifting processes in automatic stepped transmissions

Introduction (problem statement and relevance).Designing gear shifting algorithms is one of the major problems in development of control systems for automatic gearboxes. Structure and parameters of these algorithms govern such characteristics of shifting processes as torque transients and energy dissipation due to clutch slippage; these, in turn, affect vehicle comfort and lifespan of the gearbox components. In particular, one of the factors defining the said characteristics is engine torque control provided during gear shifts. The functionality of the torque control extends when using the gearbox as a part of a hybrid powertrain with a traction electric machine connected to the gearbox input shaft. Studying gear shifting processes in this aspect is a relevant task aimed at improving control systems of automatic transmissions.The purpose of the studyis to compare different methods of controlling torque at the gearbox input shaft regarding their effect on gear shifting dynamics, clutch energy dissipation, and vehicle comfort.Methodology and research methods.The study was conducted by means of simulations using a mathematical model describing dynamics of a vehicle equipped with an automatic gearbox with an option of having an electric machine installed at the input shaft. Considering straight-line accelerated motion of the vehicle, both upshifts and downshifts were simulated with a correcting torque introduced in inertia phases of the shifts. Analysis of the simulation results allowed calculating key parameters of vehicle dynamics and clutch energy dissipation.Scientific novelty and results.The simulation results show a significant decrease (aver. 40%) of jerks when using an electric machine to correct the input shaft torque in inertia phases of both upshifts and downshifts. It is also shown that correction of the shaft torque allows reducing energy dissipation due to clutch slippage by 16–24% in the case of engine torque control and by 28–34% in the case of torque correction by an electric machine. However, using torque correction by means of an electric machine during downshifts raises the clutch energy dissipation 1.4–2.4 times.The practical significance.The results of the study can be used in designing control systems for automatic gearboxes intended for both conventional and electrified vehicles.

Series and Exponentially-Fitted Two-Point Hybrid Method for General Second Order Ordinary Differential Equations

Series and Exponentially-Fitted Two-Point Hybrid Method for General Second Order Ordinary Differential Equations

A Survey of Transoral Robotic Mechanisms: Distal Dexterity, Variable Stiffness, and Triangulation.

Robot-assisted technologies are being investigated to overcome the limitations of the current solutions for transoral surgeries, which suffer from constrained insertion ports, lengthy and indirect passageways, and narrow anatomical structures. This paper reviews distal dexterity mechanisms, variable stiffness mechanisms, and triangulation mechanisms, which are closely related to the specific technical challenges of transoral robotic surgery (TORS). According to the structure features in moving and orienting end effectors, the distal dexterity designs can be classified into 4 categories: serial mechanism, continuum mechanism, parallel mechanism, and hybrid mechanism. To ensure adequate adaptability, conformability, and safety, surgical robots must have high flexibility, which can be achieved by varying the stiffness. Variable stiffness (VS) mechanisms based on their working principles in TORS include phase-transition-based VS mechanism, jamming-based VS mechanism, and structure-based VS mechanism. Triangulations aim to obtain enough workspace and create adequate traction and counter traction for various operations, including visualization, retraction, dissection, and suturing, with independently controllable manipulators. The merits and demerits of these designs are discussed to provide a reference for developing new surgical robotic systems (SRSs) capable of overcoming the limitations of existing systems and addressing challenges imposed by TORS procedures.

Torsional vibration analysis and optimisation of a hybrid vehicle powertrain

Torsional vibration analysis and optimisation of a hybrid vehicle powertrain

Torsional vibration analysis and optimisation of a hybrid vehicle powertrain

Torsional vibration analysis and optimisation of a hybrid vehicle powertrain

Aplikačné možnosti HCCI technológie

This text describes the current state of the art of HCCI technology, which is based on combining the characteristics of a petrol and diesel engine. HCCI engines offer higher fuel efficiency and lower nitrogen oxide emissions. However, they also have disadvantages such as limited load range, control complexity and cold weather starting problems. The next section of the text discusses hybrid propulsion, which uses a combination of an internal combustion engine and an electric motor. It describes the different types of hybrid powertrains such as soft hybrids, plug-in hybrids and full hybrids. Explains their advantages and possible applications. A solution is then proposed where the HCCI engine would serve as a generator in a series hybrid vehicle with an electric motor. Such an arrangement allows optimization of energy use and reduction of emissions. Finally, the relevance of HCCI technology for improving the efficiency of fuel engines and hybrid vehicle design is evaluated.

Real-Time Optimal Control for Eco-Driving and Powertrain Energy Management

This paper presents a real-time receding-horizon control solution for the optimal control problem on combined eco-driving and powertrain energy management for a series-hybrid electric vehicle. By defining the optimal control problem in the spatial domain, discretizing the dynamics and applying several relaxations to the constraints, the problem is formulated as a second-order cone problem. The online real-time solution is achieved through the reformulation into a receding horizon control problem. To reduce computational complexity, several move-blocking strategies are applied. Combining powertrain control of the hybrid powertrain with eco-driving, leads to a reduction of 33.7%, compared to only applying energy management.

Feasibility study for shunting locomotives with fuel cell hybrid-overhead electric bi-mode powertrain

Most shunting locomotives are equipped with diesel engines. Hydrogen fuel cell hybrid powertrains in combination with overhead electric driving capability (bi-mode) offer an emission-free option. Whereas a fuel cell hybrid traction chain is used for catenary-free shunting and main-line operations, in main-line sections under catenary electricity is drawn from the overhead wire. With the aim to examine the feasibility of various operations in freight transport, generic driving profiles had been simulated and a powertrain layout has been calculated. The results show that the layout is particularly well suited when shunting and electrified main-line sections alternate. Non-electrified main-line operations can be covered but with limited range. Fuel cell hybrid-overhead electric bi-mode powertrains thus offers flexible operating conditions for certain shunting locomotive applications.

A Deep Reinforcement Learning Based Hierarchical Eco-Driving Strategy for Connected and Automated HEVs

The advancement in vehicle connectivity and autonomy has fostered the development of eco-driving technology, aimed at optimizing driving behaviors to reduce vehicle energy consumption. This study proposed a real-time deep reinforcement learning based hierarchical eco-driving control strategy to optimally control a connected and automated hybrid electric vehicle in a traffic scenario with multiple constraints. The speed optimization layer of the proposed strategy employs a twin-delayed deep deterministic policy gradient (TD3) based reference speed planning strategy to compute the optimized speed, based on a pre-trained optimal policy and observed environmental states. Specifically, to learn the optimal policy, a multi-objective reward function is designed that integrates fuel consumption reward and shaping reward involving car-following and road speed limit. Additionally, a rule-based competition-decision model is embedded within the speed optimization layer to ensure compliance with traffic light rules. In the vehicle controller layer, a real-time controller is implemented to specify appropriate actuator variables for the hybrid powertrain to track the reference speed and conduct energy management control. Simulation results show that the proposed TD3 based eco-driving strategy achieves remarkable energy saving performance by optimizing the speed. Besides, the proposed eco-driving strategy is capable of satisfying the constraint of diverse traffic scenarios, including car-following and traffic light, while also being computationally lightweight.

ANALYSIS ON AN AUTOMOBILE BASED HYBRID ELECTRIC VEHICLE SYSTEM BASED ON VARIOUS INTERNAL COMBUSTION ENGINE

Increased environmental impact from the fast consumption of fossil fuel has provided a significant drive for the creation of more fuel-efficient automobiles. Having matured from their embryonic stage, hybrid electric vehicles (HEVs) are showing signs of being a viable solution to the critical existential threat to Earth. Higher efficiency vehicles (HEVs) not only help drivers save money on gas by getting greater mileage and producing fewer harmful emissions, but they also cushion drivers and passengers from the financial blow of steadily increasing gas costs. The electrification of powertrains is a tried-and-true response to environmentalists' worries about dependence on nonrenewable fuels and greenhouse gas emissions. Hybrid electric vehicles, which bridge the gap between conventional internal combustion engine vehicles and pure electric vehicles, are gaining market share and garnering a lot of attention from researchers in both the private and public sectors. An integral part of hybrid powertrains, the internal combustion engine affects vehicle performance significantly. There has been a lot of work done in recent years on engine technologies tailored to hybrid electric vehicles. It is crucial to study the engine's dynamic features through testing that mimic the vehicle's road running mode. The electric eddy current machine of an automotive engine test stand mimics the loading conditions of being driven on the road. Recommendations from a technological perspective all the way up to a powertrain perspective are presented in response to challenges and issues related to system complexity, restricted operating conditions, controls, cost, safety, etc. To inspire further study in this area, several potential avenues for future research are given.

Development of a piezoelectric-hydraulic series hybrid vibration exciter undergoing dynamic overloads

Development of a piezoelectric-hydraulic series hybrid vibration exciter undergoing dynamic overloads

Influence analysis of front grille shape on flow field in front cabin of series hybrid electric truck based on large eddy simulation

Influence analysis of front grille shape on flow field in front cabin of series hybrid electric truck based on large eddy simulation

Синхронизация работы поршневого и электрического двигателя в авиационной гибридной силовой установке параллельной схемы

The article discusses the synchronization of the operation of a piston and electric engine in an aviation hybrid power plant in a parallel circuit. Diagrams of a parallel and series hybrid power plant based on a piston engine and an electric motor are presented. The features of the parallel circuit hybrid power plant are noted. The power and torque graphs of a piston engine, an electric motor and a hybrid propulsion system with a propeller are analyzed. Conclusions are drawn about the possibility of synchronizing different types of engines as part of a hybrid power plant, taking into account power losses

Economic Potential for Hybrid Electric Vehicles in Urban Signal-free Intersections with Decentralized MPC

The development of electric and connected vehicles as well as automated driving technologies are key towards the smart city, providing convenient urban mobility and high energy economy performance. However, the global rise in electricity price provokes renewed interest on CAVs with hybrid electric powertrains rather than considering battery electric powertrains. This paper proposes a decentralized coordination strategy for a group of connected and autonomous vehicles (CAVs) with a series hybrid electric (sHEV) powertrain at urban signal-free intersections. The problem is formulated as a convex form with suitable relaxation and approximation of the powertrain model and solved by decentralized model predictive control (DMPC), which enables rapid search and a unique solution in real-time. Numerical examples validate the effectiveness of the proposed methods concerning physical and safety constraints. By utilizing the petrol fuel and battery charging prices over the last year, the performance of the proposed approach is evaluated against the optimal results produced by two benchmark solutions, conventional vehicles (CVs) and battery electric vehicles (BEVs). The comparison results demonstrate that the traveling cost of sHEVs approaches and, even under some circumstances, reaches the same level as for BEVs, which indicates the importance of hybridization, particularly under the current rising electricity price situation.

Influence analysis of front grille shape on flow field in front cabin of series hybrid electric truck based on large eddy simulation

Influence analysis of front grille shape on flow field in front cabin of series hybrid electric truck based on large eddy simulation

Integrated motion control and energy management of series hybrid electric vehicles: A multi-objective MPC approach

This paper considers the integrated motion control and energy management problems of the series hybrid electric vehicles (SHEV) with constraints. We propose a multi-objective model predictive control (MOMPC)-based energy management approach, which is embedded with the motion control to guarantee driving comfort. In addition, due to the slow response of the engine, it may cause excessive batter power when HEVs work in different conditions (e.g., uphill or sudden acceleration) with a certain request power; this implies the discharge current is too large. A battery current constraint is designed and incorporated into the MOMPC optimization problem and hence avoids the extra high charge-discharge current. This prevents potential safety hazards and extends the battery's life. Finally, the numerical experiments are performed to verify the proposed approach.

Validation of a Lumped Parameter Model of the Battery Thermal Management System of a Hybrid Train by Means of Ultrasonic Clamp-On Flow Sensor Measurements and Hydronic Optimization

Electrification of the field of transport is one of the key elements needed to reach the targets of greenhouse gas emissions reduction and carbon neutrality planned by the European Green Deal. In the railway sector, the hybrid powertrain solution (diesel-electric) is emerging, especially for non-electrified lines. Electric components, especially battery power systems, need an efficient thermal management system that guarantees the batteries will work within specific temperature ranges and a thermal uniformity between the modules. Therefore, a hydronic balancing needs to be realized between the parallel branches that supply the battery modules, which is often realized by introducing pressure losses in the system. In this paper, a thermal management system for battery modules (BTMS) of a hybrid train has been studied experimentally, to analyze the flow rates in each branch and the pressure losses. Since many branches of this system are built inside the battery box of the hybrid train, flow rate measurements have been conducted by means of an ultrasonic clamp-on flow sensor because of its minimal invasiveness and its ability to be quickly installed without modifying the system layout. Experimental data of flow rate and pressure drop have then been used to validate a lumped parameter model of the system, realized in the Simcenter AMESim® environment. This tool has then been used to find the hydronic balancing condition among all the battery modules; two solutions have been proposed, and a comparison in terms of overall power saved due to the reduction in pressure losses has been performed.

Performance and Total Cost of Ownership of a Fuel Cell Hybrid Mining Truck

The main objective of this work was to investigate the potential of hydrogen and fuel cells replacing diesel and internal combustion engines in the ultraclass haul trucks deployed in the mining sector. Performance, range, durability, and cost are the main criteria considered for comparing the two fuels and engine options. Fuel cell system (FCS) performance is characterized in terms of heat rejection, efficiency, and fuel consumption for a hybrid platform equivalent to a 3500 hp diesel engine operating on a representative open pit mining duty cycle. A hybrid platform was chosen because the heat rejection, with a constrained radiator frontal area, limits the maximum fuel cell-rated power by about 50% compared to that of the diesel truck. The hybrid powertrain was 81–88% more efficient than the diesel powertrain on the truck duty cycle. A liquid hydrogen storage system is required for an equal range or time between refilling, but the packaging remains a challenge. Fuel cell and battery durability were evaluated for their performance degradation and lifetime. Achieving a fuel cell lifetime comparable to the time between major overhauls for diesel trucks necessitates the oversizing of the membrane-active area, catalyst overloading, and voltage clipping. For an equal lifetime, the battery must be oversized to control its depth of discharge and charge/discharge rates. A total cost of ownership (TCO) analysis considering the initial capital expenditures, as well as the lifetime cost of fuel, operation, and maintenance, indicates that fuel cells and hydrogen can compete with diesel. A breakeven fuel cost for TCO parity is obtained if H2 is available at USD 5.79–6.85/kg vs. diesel at USD 3.25/gal and the FCS-specific cost is USD 323/kWe relative to USD 250/kW for a diesel genset. Volume manufacturing is required for FCS cost reduction. High volume is possible through the standardization, modularity, and proliferation of class 8 long-haul truck systems across different heavy-duty applications.

Introducing SNAP: a novel pedal-assisted electric ultralight vehicle

Innovation in transportation and mobility is central to sustainable development. There is a widespread awareness that society would benefit if transportation became more sustainable, promoting economic growth while respecting the environment. This paper introduces SNAP, a four-wheel pedal-assisted electric vehicle that represents a new concept in sustainable mobility towards filling the gap between bicycle and automobile. The choice of the architecture for the hybrid powertrain where the driver pedals are assisted with an electric motor is discussed along with the experimental analysis of the power loss associated with the single components of the transmission. In turn, this knowledge allows the overall quadricycle performance to be evaluated in terms of maximum speed, efficiency, and travel range at varying operating conditions that include vehicle load, road slope, and gear change. It is shown that SNAP can be a promising answer to address the problem of sustainable and safe micro mobility of persons and goods in urban settings.