Browse Topic: Alternators
Complex FEAD system in modern powertrain is reality today due to demanding regulation, hybrid powertrain and increasing customer expectation. Gasoline engines are going to be preferred over diesel engines specially for passenger car application. These downsized engines lead to increase engine excitation and so to higher dynamics. Use of overrunning alternator pulley (OAP) is globally accepted as cost effective and technically proven product for FEAD system to make it robust by optimizing the system performance such as belt tension, hub load, slippage and vibrations to improve fuel consumption and to reduce engine emissions. OAP is a mechanical device with one-way clutch unit which eliminates the torsional vibrations coming from engine crankshaft and ensures only accelerating proportions of crankshaft forces are transferred to alternator which means reduction in force level of belt drive system. This paper describes the advantage of usage of OAP to achieve reduction in fuel consumption and emissions, to make the FEAD system efficient over the rigid alternator pulley by eliminating the rotational irregularities coming from FEAD system. In this paper, various engine driving conditions have been simulated to assess FEAD system performance in terms of hub load, belt pre-tension, belt slippage and vibrations by comparing rigid pulley and overrunning alternator pulley, followed by engine validation, which shows effectiveness of OAP.
This paper describes the implementation, integration, testing and performance evaluation of compact and battery-less alternator with external regulator for diesel engine for avionics application. The key responsibility of this alternator is to generate 2.8kW power with 28V regulated power supply for various loads. The alternator has been integrated and installed on the diesel engine and further tested on dynamometer and thrust cradle with propeller combination. The alternator when used in conjunction with ACU (Alternator Control Unit) that is designed to boot strap field voltage during low speed operation, has the ability to self-excite. The alternator / ACU system has the ability to generate power even in the absence of battery voltage i.e. in battery less systems or those in which the battery is not always connected to the alternator. External voltage regulator has been used which minimizes ripple up to 1.0V. The alternator rpm ranges from 3000 to 10000 for generating maximum power. Self-excitation ability is derived from residual magnetism in the rotor pole pieces. Experimental setup on thrust cradle and dynamometer with resistive load was setup and performance of alternator has been established as per design requirements.
Two-layer engine front end accessory drive systems (TEFEADS) are adopted generally by commercial vehicles due to the characteristics of the accessory pulleys, which have large torque and moment of inertia. An overrunning alternator decoupler (OAD) is an advanced vibration isolator which can reduce the amplitude of torsional vibration of alternator rotor effectively by an one-way transmission and they are more and more widely used in vehicles. This paper established a model of a generic layout of a TEFEADS with an OAD. The coupling effect between the TEFEADS, the nonlinear characteristics of OAD, the torsional vibration of crankshaft and the creeping on the belt were taken into account. A nine pulleys model was provided as a study example, the dynamic responses, which are respectively under steady and accelerating conditions, of the system were calculated by the established method and compared with the bench experiment. The influence of different belt material, the stiffness of OAD spring and the parameter of the tensioner on dynamic performances, such as the oscillation of tensioner arm and the dynamic belt tension were analyzed.
The generator is an important loaded component of an engine front end accessory drive system (EFEADS). With a huge moment of inertia and a highest running speed, the vibration and noise often occurs in operation, which has an effect on the service life. Thus an overrunning alternator decoupler (OAD) is used in the EFEADS for reducing the vibration of system. In this paper, a model of EFEADS with an OAD is established. The impact of the OAD on the dynamic responses of pulley of generator and the system are analyzed, and is verified by bench experiments. And the influence of parameters, such as spring stiffness, moment of inertia of generator and loaded torque on the dynamic performances of the system are studied. The influence of misalignment in pulleys on the dynamic performance of system is also discussed. The presented method is useful for optimizing the dynamic performance of system, such as the oscillation of tensioner arm and the slip ratio of the belt-generator pulley.
Why Volvo uses starter-generators and raised tunnels for its electrified vehicles. Volvo first demonstrated its Integrated Starter Generator (ISG) at the 2001 Frankfurt Motor Show. Replacing the starter-motor and alternator with the ISG allows a gas engine to shut off at will - mainly to prevent idling at a stop. For the company, it was a logical first step for fuel savings. But Volvo engineers at the time could hardly have predicted how useful an ISG would become, decades later, in the electric era. As Automotive Engineering discovered on our recent drive of the 2020 Volvo XC90 T8 plug-in hybrid during its media launch, an integrated crankshaft generator doesn't merely allow stop-start or mild-hybrid propulsion. While piloting the XC90 T8 along the Trans-Canada Highway in August, we were able to keep the three-row, full-size SUV in pure electric mode for its first 21 miles (34 km).
Increasingly research has been conducted lately towards reduction of both fuel consumption and gases emission in automotive vehicles propelled by Internal Combustion Engines. Among many initiatives, downsizing of those engines has been broadly adopted, arising side effects as increased vibration levels along Front-End Accessory Drive (FEAD) system. The present study focuses on the potential improvement of transmission efficiency and of vibration levels along FEAD by considering different layouts for the system. Multiple combinations of alternator pulley technologies and tensioner types are evaluated either during in-vehicle tests or in customized test rig that emulates vehicle FEAD in operating conditions. Specific transducers spred over the vehicle and at test rig assure the relevant data are captured for every layout arrangement investigated. Experimental results evidence the influence of distinct alternator pulley technologies and tensioner types on both transmission efficiency and vibration levels along FEAD during critical operating conditions. Moreover, the proposed experimental approach can be adopted to refine FEAD layout into a feasible arrangement, which can contribute to validate downsized internal combustion engines.
There is a clear concern about air pollution on the planet. Measures to reduce CO2 emissions in the Earth's atmosphere were taken to minimize the possibility of global warming. In the context, many countries have created laws and incentive programs that encourage an automotive industry to develop innovative technologies to increase the energy efficiency of their vehicles, thereby reducing fuel consumption and consequently reducing CO2 emissions. Often technologies are applied in combination so that there is an increase in energy efficiency of the vehicle. The objective of this work is to present an experimental evaluation of the energy consumption and reduction of CO2 with a combined application of the Stop & Start measures and mechanical decoupling of the alternator. The new alternator with mechanical and consequent electrical decoupling, consists of a pulley integrated to an electromagnetic clutch. The decoupling is performed according to the internal combustion engine operating conditions. This solution allows the complete unloading of the crankshaft in relation to the inertia and the electromagnetic field of the alternator. To measure the reduction of fuel consumption and carbon dioxide, a vehicle with the possibility of operation as two strategies to test in the cycles FTP75 + Highway. Each technology was tested separately and in combination, demonstrating that the combined application allows a considerable reduction of energy and CO2 emission. A strategy of the mechanical undocking of the alternator allowed a greater reduction than the effect of the isolated Stop & Start strategy.
With the adoption of the Worldwide harmonized Light Vehicles Test Procedure (WLTP) and the Real Driving Emissions (RDE) regulations for testing and monitoring the vehicle pollutant emissions, as well as CO2 and fuel consumption, the gap between real world and type approval performances is expected to decrease to a large extent. With respect to CO2, however, WLTP is not expected to fully eliminate the reported 40% discrepancy between real world and type approval values. This is mainly attributed to the fact that laboratory tests take place under average controlled conditions that do not fully replicate the environmental and traffic conditions experienced over daily driving across Europe. In addition, any uncertainties of a pre-defined test protocol and the vehicle operation can be optimized to lower the CO2 emissions of the type approval test. Such issues can be minimized in principle with the adoption of a real-world test for fuel consumption. However, repeatability and an accuracy of a few gCO2/km is difficult to achieve due to the actual drag, the road surface effect on driving resistance, the road slope, the battery and auxiliaries use etc., which come naturally with on-road tests. Since a reference value for CO2 emissions should not depend on the testing circumstances, modeling can be deployed in order to introduce the necessary correction of measurement variations in a harmonized manner, based on individual vehicle simulation models that can produce smoothed results under the same driving conditions, ambient temperature, alternator operation etc. In this paper, such a simulation approach for the correction of RDE compliant measurements is introduced and demonstrated with a few real cases. The approach incorporates the encountered real-world effects for the prediction of a reference CO2 value. It is shown that with an expansion of the approach to cover variations for existing engine types, powertrains, vehicle types etc., baseline accuracy for real world simulations can be established.
Real world driving conditions and tightening legislations require improved performance of aftertreatment systems at lower temperatures. Electric heat has been shown to be an effective method of heating exhaust, but having a practical means to provide power and control for the heater has been a barrier for implementation. Recent testing has demonstrated the ability of a 24Vdc heating and control system to effectively heat exhaust using only conventional alternator and battery power sources. Results from transient cycles show the effectiveness of the electrical system and the extent of exhaust heating.
On two wheelers, magneto/alternator generates either single/three phase AC power and Regulator Rectifier Unit (RRU) does regulated rectification to charge the battery. In order to face the requirements of 2-wheeler engine with respect to upcoming stringent regulations like electronic fuel injection (EFI), anti-lock braking system (ABS), automatic headlamp on (AHO) in emerging markets like India; vehicles demand more electrical power from batteries. This demands higher power from alternator and consequently from RRU. Requirement of higher output power presents challenges on regulator rectifier unit in terms of size, power dissipation management and reliability. In this paper, improved performance of MOSFET based RRU is discussed in comparison to Silicon Controlled Rectifier (SCR) based RRU. The motivation/benefits of MOSFET based design is described along with the thermal behavior and temperature coefficient performance of RRU with test results. The second topic discussed is how the MOSFET based RRU helps to improve performance by respecting form factor and total power dissipation compared to SCR based design.
For the purpose of improving vehicle fuel efficiency, it is necessary to reduce energy loss in the alternator. We have lowered the resistance of the rectifying device and connecting components, and control the rectifying device with an IC to reduce rectification loss. For the package design, we have changed the structure of the part on which the rectifying device is mounted into a high heat dissipation type. The new structure has enabled optimizing the size of the rectifying device, resulting in the reduction of size of the package. In addition, the rectifying device is mounted using a new soldering material and a new process, which has improved the reliability of the connection. Moreover, since the alternator has introduced a new system, the controller IC has a function for preventing malfunction of the rectifying device and a function for detecting abnormalities, in order to ensure safety. These technologies have realized a low-energy loss high-reliability rectifier, which contribute to the reduction of alternator loss and enhancement of vehicle fuel efficiency.
This paper presents a numerical methodology to predict the dynamic behavior of the front end accessory drive (FEAD) and the overrunning alternator decoupler (OAD) pulley. The methodology uses the commercial code Altair Radioss, and is based on 3D Lagrangian formulation, finite element method and explicit time integration schemes. Contact between different parts were considered using penalty methods. The methodology is divided in two independent parts: 1) FEAD with rigid pulleys, and 2) OAD pulley alone with flexible components. In the first part it is possible to evaluate the vibration of relevant components like the belt and the tensioner pulley, and in the second part it is possible to analyze not only the vibration of the OAD pulley, but also the stresses on critical components to durability. It is also presented a comparison between numerical and experimental results, where the torque profile as a function of the angle is presented for the OAD pulley in a quasi-static test, and the methodology showed good agreement.
The free piston engine combined with a linear electric alternator has the potential to be a highly efficient converter from fossil fuel energy to electrical power. With only a single major moving part (the translating rod), mechanical friction is reduced compared to conventional crankshaft technology. Instead of crankshaft linkages, the motion of the translator is driven by the force balance between the engine cylinder, alternator, damping losses, and springs. Focusing primarily on mechanical springs, this paper explores the use of springs to increase engine speed and reduce cyclic variability. A numeric model has been constructed in MATLAB®/Simulink to represent the various subsystems, including the engine, alternator, and springs. Within the simulation is a controller that forces the engine to operate at a constant compression ratio by affecting the alternator load. The complex interdependence of the free piston engine alternator is analyzed with respect to parametric changes to the spring stiffness. For a fixed compression ratio, it is shown that an increase in spring stiffness from 50 to 350 kN/m (which practically must be associated with an increase in total moving mass) raises system frequency (18%) and power (12%), but can also lead to a relatively small loss of system efficiency (2%). This is due to the decrease of charging efficiency (EGR increased by 12%) for fixed intake/exhaust conditions and higher frictional losses (4%). The gain in system frequency and power output is diminished according to the increased moving mass associated with stiffer springs. This study also investigates the ability of springs to dampen cyclic variation in response to combustion variation. Normally distributed noise is added to combustion efficiency and duration. Coefficients of variation of compression ratio and peak pressure are used to represent cycle to cycle variation response and compared for varied spring stiffnesses. It is shown that the stiff springs can be used to dampen the effects of combustion stochastics and the resulting variation brought on by cylinder pressure variation. This results in lower controller demand and higher operational sustainability.
ABSTRACT Predictive analysis of vehicle electrical systems is achievable by combining condition based maintenance (CBM) techniques and testing for statistical significance (TSS). When paired together, these two fundamentally sound sciences quantify the state of health (SOH) for batteries, alternators, starters, and electrical systems. The use of a communication protocol such as SAE J1939 allows for scheduling maintenance based on condition and not a traditional time schedule.
Micro Hybrid Systems are essentially first step towards the electrification of the powertrains. They are aimed at improving the fuel efficiency of the conventional gasoline and diesel power trains with conventional 12 V electrical system, and thus reduce the CO2 emissions as well. Various technologies like Engine Stop-Start, Intelligent Alternator Control, and Electrical Energy Management Systems are included in the bracket of micro hybrid systems. These system functions demand a totally different approach for managing the SLI battery, which is a total departure from the conventional approach. Particularly, the Alternator Shutdown function of Intelligent Alternator Control maintains a calibrated average level of State of Charge, which is typically around 80%, to ensure that the battery can accept more current, during the energy recuperation, which indirectly improves fuel economy. However, continuous operation under partially discharged condition, results in the sulfation in the battery which is the main reason for the ageing of the battery. Symptoms of ageing include permanent loss of capacity, increase in internal resistance, etc. This paper discusses a novel approach of ensuring the life of the battery in the altered operating conditions of a Micro Hybrid System. A Charge Refresh Cycle is implemented in the Battery Management System, which periodically performs a refresh charge on the battery to ensure that the battery is not affected due to partially discharged conditions, without having to disconnect the battery from the vehicle, and without the need of a visit to a service station. This is achieved by implementing a timer and an engine start counter, based on which the control signals for the refresh charge are triggered. The system not only ensures the performance of the battery, but also ensures the return of designed life of the battery. The function was validated under controlled conditions on several samples of batteries, and it was observed that the battery life is restored back to the designed life.
Micro hybrid Systems are emerging as a promising solution to reduce the fuel consumption and greenhouse gas emissions in emerging markets, where the strict emission requirements are being enforced gradually. Micro hybrid Systems reduce the fuel consumption and greenhouse gas emissions in a conventional vehicle with 12 V electrical system, by optimizing the electrical energy generation, storage, and distribution, with functions like Intelligent Alternator Control, Engine Stop/Start, and Load Management. With the advent of Connected Car Systems, information about the vehicle is seamlessly provided to the customer not just through the Human Machine Interface systems within the vehicle, but to other mobile devices used by the customers. In a vehicle with Micro Hybrid System, as the key feature is fuel efficiency improvement, it becomes essential to provide the information of improvement in fuel efficiency, in addition to the fuel consumption, so that the user appreciates the effectiveness of the system. However, real time mapping of the improvement, with respect to a base vehicle is challenging. In this paper, influence of Intelligent Alternator Control system functions, on the fuel economy returned by the vehicle are discussed, before the concept developed for the estimation of improvement in fuel economy. For the estimation of improvement in fuel economy, a novel concept was developed in which the alternator input torque is estimated under the influence of the IAC system, and the engine torque demand is estimated to arrive at an estimate of the total fuel consumption. A virtual base alternator model is implemented for comparing and estimating the improvement in the fuel economy. The concept was validated under controlled conditions and estimations were found to be accurate up to 63%.
As environmental concerns grow for R&D teams, OEMs look to bring the strategy further into the mainstream. Environmental issues have become a primary concern for research and development teams globally. Euro VI, mandated in all new cars sold in the European Union from September 2014, is stricter than ever. Bharat Stage IV, a prevalent emissions standard in NCR and 13 major cities in India, is proposed to be replaced by Stage V in 2017 nationwide. In fact, the deplorable air quality in Indian metropolitan cities has driven the Ministry of Environment and Forests to file an affidavit in the Supreme Court urging to leapfrog to Stage VI by 2020. The European Automobile Manufacturers Association, which accounts for roughly 85% of all cars sold in the European Union, has voluntarily agreed to limit their average CO2 emissions to 95 g/km by 2020. To put things in perspective, the average CO2 emissions for the passenger fleet was about 125 g/km in Europe in 2013. There is currently no regulation on CO2 emissions in India, but that is soon to change.
The fuel economy of a vehicle can be improved by recuperating the kinetic energy when the vehicle is decelerated. However, if there is no electrical traction component, the recuperated energy can be used only by the other electrical systems of the vehicle. Thus, the fuel economy improvement can be maximized by balancing the recuperated energy and the consumed energy. Also, suitable alternator and battery management is required to maximize the fuel economy. This paper describes a design optimization process of the alternator and battery system equipped with recuperation control algorithms for a mid-sized sedan based on the fuel economy and system cost. A vehicle model using AVL Cruise is developed for cycle simulations and validated with experimental data. The validated model is used for the parametric study and design optimization of the alternator and battery systems with single and dual energy storage. In this paper, recuperation systems with Flooded, AGM, and Li-ion batteries are compared and different design optimization processes are presented depending on the battery types and system architectures.
There are variety of motors and generators/alternators being manufactured internationally, for variety of applications. It is a difficult task for the user to identify and select the type of motor /generator/alternator for a specific use, by the designer and ultimately the user is totally unaware of what is bought and why. There is a need to designate the motors and generators. So that by interpretation of the identification nomenclature of the motor or generator, its type can be judged. Whether it is a series motor, an induction motor etc, in case of motors. This will eventually make it easy for the manufacturer, the buyer and the consumer to identify the motor or generator type. So a universally accepted and followed identification nomenclature is required to be developed which will henceforth make dealing in motors and generators simpler for all. It will prove to be useful during troubleshooting. During the time of failure or any abnormality in the machinery, the person using it need not carry the machine as a whole to the supplier for enquiring its type and then asking him to replace it, instead just by knowing the nomenclature the concerned person can simply ask the supplier or dealer to provide him with that machine. By setting the universal identification nomenclature, the standards of specifications of motors or generators and all the components used therein, can be formulated, so that all the manufacturers are brought on the same platform to meet the set standards, which eventually will result in ease of selection of motors or generators by designers and end users for optimum output. This will build a smooth functional channel between the manufacturers, the suppliers or the dealers, the buyers and the consumers. The authors have attempted to develop and suggest such identification methodology.
This paper details the methodology used to prevent Thermal events in a vehicle at design and development stages which can lead to vehicle fire or Thermal events. Vehicle Safety is always been in prime focus for designers while introducing newer products in markets for the customers. It is now common to see vehicles catching on fire in roads and in parking places leading to destruction of the surroundings as well as hazard to the passengers. Thermal events can take place due to the heat dissipated by the heat emitters such as Engine, Turbo, Alternator, Exhaust System etc. So the most critical area where Thermal event can take place are under hood which includes the complete engine compartment and under body. The extent of fire depends on the fire source, characteristics of the materials used in constructing and furnishing the vehicle. The Performance and life of Electronic parts and parts made of polymeric materials such as rubber and plastics which in result are greatly influenced by the temperature of their surroundings. Different materials have different sensitivities to temperature and decomposition processes will differ substantially from case to case. High temperatures, hot surfaces and a variety of combustible materials make the engine compartment and under body high fire risk areas. Under these scenarios it is important for any vehicle designer to consider the hazards associated with fire and choose the materials appropriately for avoiding and minimizing the fires to pose less risk to the occupants. In this paper the possible fire sources, combustible material in vehicles and considerations in design for minimizing the risks related to fire and Thermal safety are detailed taking into account the hazards associated and risk assessment.
City buses are equipped with an increasing number of electrical devices that are designed to improve the driver work and increase passengers' comfort. The alternator must therefore meet the requirements of increased levels of electric energy demand. In this paper, the focus is set on the amount of chemical energy in the fuel transformed into electric energy by the alternator, especially in the case of urban transport. The article presents the results of operating states of the alternator in the city bus while driving. During the study waveforms of rotational speed and load current of power generation system were recorded. The results of measurements made it possible to draw histograms showing the share of working time in different points of the alternator work. Only about 43% of the total working time corresponds to the bus stop and the operation of the idle speed of the alternator 2250 rpm. The remaining time corresponds to the average speed about 4200 rpm and does not exceed 6600 rpm. To determine the average efficiency of the bus alternator, the bench tests were performed. Test bench consists of a DC engine and alternator that were connected via a belt transmission. The results of the study were the characteristics of the alternator operating under different loads. The maximum alternator efficiency amounts to 65%. Assuming an average bus engine efficiency of 20 %, the efficiency of generating electricity on board of a bus is 10.2%.
Linear alternators coupled to Stirling power converters are promising candidates for high-efficiency heat-to-electricity power conversion in space. Presently, the external magnetic field emissions of such converters may exceed the allowed emission limits for use with certain sensitive scientific instrumentation. This invention, based on concepts of magnetic moment balancing, can reduce such field emissions sufficiently to enable use of the space power Stirling converters in sensitive instrumentation missions.
The demand for comfort level in commercial vehicles is steadily increasing. Hence, fine-tuned performance parameters and attributes are required to fulfill the expectations from these vehicles. Refinement of noise and vibration without affecting performances of sub-systems and components has become extremely challenging with increasing customer requirements. This paper presents an approach to identify and reduce the high level whistling noise that was perceived in the passenger compartment while the vehicle was accelerated above 50 kmph. Interior noise measurements in static engine run-up condition reveal that the whistling noise is of specific order. Since, whistling noise is related to aerodynamic response of components, engine cooling fan, turbo charger, alternators and compressors were suspected. Using order tracking and near field measurements, HVAC alternator was confirmed as the main cause for whistling noise. Noise measurements confirmed that orders related to alternator cooling fan became dominant above 50 kmph. HVAC alternator was tuned in a manner to reduce the noise without affecting the electrical performance. Significant reduction in whistling noise level was observed in both objective and subjective assessments in the passenger compartment with this modification.
This SAE Recommended Practice provides test methods and requirements for maintenance of design voltage in snowmobile electrical systems. It pertains to both battery-equipped and battery-less systems.
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