Integrated Starter Alternator Research Articles

Mechanical Flux Weakening Methods for the Achievement of a Very Wide Constant Power Speed Range in Automotive Applications

Permanent magnet machines are widespread in the automotive industry, due to their high torque density and high efficiency. In automotive applications such as integrated starter alternators, a very wide constant power speed range is also required for electricity generation onboard. To maintain a constant voltage, flux weakening must be employed during generation. With the conventional electrical flux weakening methods, considerable amounts of current would have to be consumed to weaken the strong flux linkage from the magnets, which results in an efficiency decrease. Conversely, mechanical methods adjust the linked flux by manipulating the position of certain machine parts, avoiding the consumption of current. Thus, mechanical flux weakening might be more suitable for automotive applications, where a very wide constant power speed range is required while preserving high levels of motoring torque capabilities. In the present literature review, various implementations of mechanical flux weakening, from several authors, are analyzed and compared. The aim is to gain insight on the effectiveness of this method, in comparison with the electrical one, on fulfilling the mentioned automotive requirements.

Integrated Starter Alternator PMSM Drive for Hybrid Vehicles

Transportation electrification is gaining notoriety in recent years as to fulfill the aim of reducing the fossil fuels consumption and to increase energy efficiency. Accordingly, integrated starter alternator is a compelling method to convert conventional vehicles into hybrid ones. A deal of benefits can be reached by using ISA systems. In general, it provides vehicles performance enhancement and also reduces fuel consumption. This paper aims to present simulation results and preliminary experimental achievements with a power electronics-based prototype driving a permanent magnet synchronous machine (PMSM). The ISA operation is demonstrated throughout providing cranking torque and assistant torque for constant power and constant torque conditions and afterward the generation mode. Details of the hardware design and control strategies, which include an ADALINE neural network for properly find the mechanical position and the application of a metaheuristic technique to tune the controllers of the motor control, have been also addressed.

Integrated Starter–Alternator With Sensorless Ringed-Pole PM Synchronous Motor Drive

The so-called integrated starter–alternator (ISA) is a high-efficiency electrical machine that is connected to an internal combustion engine obtaining mild hybrid electric vehicles. The ISA has a twofold task: starting up the engine and generating electrical energy to be stored into a battery. This paper is focused on the first task. Two different motors are investigated: an external rotor surface permanent magnet (SPM) machine and an interior permanent magnet (IPM) machine. For drive control, both motors require knowledge of their rotor position; then, a sensorless technique based on the high-frequency (HF) voltage injection for rotor position detection has been implemented. In order to create an HF anisotropy in the SPM rotor configuration, a ringed-pole solution has been adopted. Experimental tests have highlighted that the first machine has a clear capability of starting up the engine with good speed and position estimation in spite of the particular nonconstant load torque. As regard the IPM machine, the sensorless engine startup appears not possible because the anisotropy disappears at a high current level due to saturation effects.

Computer Aided Design of New Type PMSM Based on ISAD

Integrated starter alternator damper (ISAD) system requires motor: high-efficient, high-power density, low-ripple torque. Halbach motor is a new type of PMSM: unique permanent magnet structure makes motor have a sinusoidal magnetic field, can increase magnetic flux density of air gap and decrease magnetic flux density of rotor, which could enhance the power density and efficiency of motor as well as reduce its size. Software of Halbach motor design is given, also with the finite element analysis software with ANSYS language. Experiment proves the advantage of Halbach motor in ISAD system.

Design Optimization of IPMSM for 42 V Integrated Starter Alternator Using Lumped Parameter Model and Genetic Algorithms

In this paper, the design optimization of an interior permanent magnet synchronous machine is presented using lumped parameter model and genetic algorithms for 42 V integrated starter alternator application. The aim of the optimization is to increase starting torque while keeping torque ripple below 10% and increasing power output in generating mode at high speed and reducing the permanent magnet weight. A finite-element method is used to verify and compare the optimized machine characteristics.

Design and Performance Analysis of an Integrated Starter-Alternator for Hybrid Electric Vehicles

In automotive applications, the requirements for the electrical machines are about performance and reliability - the permanent magnet synchronous machines ensure these requirements are fulfilled. The approach of the present paper is to analyze the permanent synchronous machines suited for the integrated starter-alternator (ISA) applications. The study design requires some analytical, followed by a numerical analysis and also a finite element method in order to achieve the performances of the machine. The operation modes of an ISA system and the constraints for an electric machine acting as an ISA are detailed. Finally a model for a ISA hybrid vehicle, developed in AMESim is presented and the results of a simulated drive cycle are presented.

Performance Evaluation of an Integrated Starter-Alternator with an IPM Synchronous Machine under Sensor-less Operation

This paper presents performance evaluation of an Integrated Starter-Alternator (ISA) prototype with an Interior Permanent Magnet (IPM) synchronous machine under sensor-less operation. To attain a high starting torque at zero speed and in subsequent extremely low speed range, a hybrid signal injection method is proposed. At higher speed, an improved stator flux observer is used for the stator flux estimation. This observer is able to produce accurately-estimated stator flux linkage for high performance Direct Torque and Flux Control (DTFC) implementation. The sensor-less DTFC IPM synchronous machine drive takes full advantage of the capacity of the power converter and fulfills the control specifications for the ISA. The trajectory control algorithm responds rapidly and in a well behaved manner over a wide range of operating conditions. The experimental results verify the feasibility and advantages of the system.

Stability Analysis of FPGA-Based Control of Brushless DC Motors and Generators Using Digital PWM Technique

Brushless dc (BLDC) drives have received significant attention, owing to their high efficiency, electromagnetic interference, and high mechanical reliability due to the absence of brushes in commercial, residential, and industrial applications. In generating mode, they are very suitable for small wind and hydro generator applications, as well as integrated starter alternators in hybrid electric vehicles. This paper discusses digital pulsewidth modulation control for a BLDC drive in both motoring and generating modes of operation. This control strategy is simple and robust, requires no current sensors, and is not computationally intensive. Owing to these attributes, the technique can be implemented on a low-cost field-programmable gate array. This paper investigates potential stability issues due to the simplicity of this control under various conditions of load disturbances and also owing to the reduction in processor capability. Lyapunov stability criteria have been used to analyze the closed-loop stability of the system. Furthermore, an approximate discrete model has been developed, and the stability of the system is analyzed to ensure closed-loop operation under various sets of loads, speeds, and input voltages. Simulation and experimental results have been presented to verify the claims.

Alternative Energy Vehicles Drive System: Control, Flux and Torque Estimation, and Efficiency Optimization

Indirect field-oriented control, direct field-oriented control, and direct torque control are the most widely used instantaneous torque control techniques for the drive system of alternative energy vehicles (AEVs). This paper evaluates three candidate alternating-current machines and investigates the suitability of different control techniques for the drive systems of battery-powered electric vehicles, hybrid electric vehicles, and integrated starter alternators. Accurate flux and torque estimation is the core of any opted control technique for all types of AEV drive systems. Therefore, an accurate closed-loop voltage model flux and torque estimator that is insensitive to stator resistance variation has been designed. This paper also analyzes loss model control and search control (SC) techniques for the drive system's efficiency optimization and proposes an offline SC efficiency optimization technique. Experimental results are presented to demonstrate the performance of the proposed flux and torque estimator and efficiency optimizer.

Interior permanent magnet integrated starter‐alternator

PurposeThe purpose of the paper is to present a complete design example of an interior permanent magnet integrated starter‐alternator (ISA).Design/methodology/approachAfter a preliminary design on the basis of an analytical model, finite element simulations are adopted to refine the design of the machine.FindingsThe designed ISA drive is able to satisfy all the requirements of modern cars, where the power of the electrical generators is increasing to deliver the on‐board power demand. The drive exhibits high torque, driving start, and a wide constant power speed range driving generation.Originality/valueThe entire system design is considered in the paper, both the electrical machine and the control strategy.

Performance evaluation of an integrated starter alternator using an interior permanent magnet machine

There is a worldwide effort in using more and more electrical-driven auxiliaries in road vehicles. The integrated starter-alternator (ISA) is an electric drive in which the functions of starting engine and generating electric power are fulfilled by only one electric machine, instead of two separate electric machines in a traditional automotive vehicle. The interior permanent magnet (IPM) synchronous machines are attractive for the ISA application thanks to their characteristics: the flux-weakening capability, the high efficiency, the high power density and the high overload capability. This study reports some analysis and test results of an ISA that has been developed using a fractional-slot IPM machine. The results confirm that the IPM machine configuration is an excellent candidate for this application.

IPM Machine Drive Design and Tests for an Integrated Starter–Alternator Application

This paper deals with an integrated starter-alternator (ISA) drive which exhibits a high torque for the engine start, a wide constant-power speed range for the engine speedup, and a high-speed generator mode operation for electric energy generation. Peculiarities of this ISA drive are thus its flux-weakening capability and the possibility to large torque overload at low speed. The focus on the design, analysis, and test of an interior permanent-magnet motor and drive for a prototype of ISA is given in this paper. In details, this paper reports on the design of stator and rotor geometries, the results of finite-element computations, the description of control system, and the experimental results of prototype tests.

On the Control of Engine Start/Stop Dynamics in a Hybrid Electric Vehicle

The starter/alternator technology is considered an easily realizable hybrid electric vehicle (HEV) configuration to achieve significant fuel economy without compromising consumer acceptability. Several examples can be found in production or near-production vehicles, with implementation based on a spark ignition (SI) engine coupled with either a belted starter/alternator (BSA) or an integrated starter/alternator (ISA). One of the many challenges in successfully developing a starter/alternator HEV is to achieve engine start and stop operations with minimum passenger discomfort. This requires control of the electric motor to start and stop the engine quickly and smoothly, without compromising the vehicle noise, vibration, and harshness signature. The issue becomes more critical in the case of diesel hybrids, as the peak compression torque is much larger than in SI engines. This paper documents the results of a research activity focused on the control of the start and stop dynamics of a HEV with a belted starter/alternator. The work was conducted on a production 1.9 l common-rail diesel engine coupled to a 10.6 kW permanent magnet motor. The system is part of a series/parallel HEV powertrain, designed to fit a midsize prototype sport utility vehicle. A preliminary experimental investigation was done to assess the feasibility of the concept and to partially characterize the system. This facilitated the design of a control-oriented nonlinear model of the system dynamics and its validation on the complete HEV hardware. Model-based control techniques were then applied to design a controller for the belted starter/alternator, ensuring quick and smooth engine start operations. The final control design has been implemented on the vehicle. The research outcomes demonstrated that the BSA is effective in starting the diesel engine quickly and with very limited vibration and noise.

Control design for an inductions machine based 42v integrated starter alternator

An improved implementation of an induction machine-based integrated starter alternator. This article presents a complete control design of an induction machine-based integrated starter alternator (ISA) for future 42-V PowerNet. The article also discusses the design of a fast dc voltage controller and field-weakening control to achieve the challenging requirements of ISA application.

A Matrix–$Z$-Source Converter With AC–DC Bidirectional Power Flow for an Integrated Starter Alternator System

This paper proposes a new converter using matrix converter theories and Z-source conversion concepts and illustrates its application for the integrated starter/alternator (ISA) system by a case study. The problem imposed by the traditional voltage source inverter to develop the relatively high dc voltage from the relatively low ac voltages of an ac machine in the ISA system has been addressed in this paper. The proposed converter achieved boost mode dc-ac inversion and buck mode ac-dc rectification, hence allowing the peak voltage of the ac motor to exceed the dc source voltage substantially. In the rectification mode, it can achieve the regulated output dc voltage with variable-voltage-variable-frequency ac source without extra close-loop control or large energy-storage devices. This paper investigates the quadrant operation of the converter, its control, its steady-state performance, and experimental verification.

An Integrated Starter–Alternator and Low-Cost High-Performance Drive for Vehicular Applications

This paper designs and implements an electromechanical propulsion system for a 42-V battery-sourced integrated starter-alternator (ISA) using an indirect-field-oriented (IFO) controller with a speed sensor on the shaft of the machine. The design aspects of the ISA energy conversion system are discussed, with emphasis on the motor selection and comparison of various candidate machines, power electronics, motor controller development and its integration with the engine controller, and a strategy for charging and discharging the energy source. A boost converter powered by the 42-V battery charges three 1-F ultracapacitors to 300 V, thus running the motor drive system at 300 V. The designed 300-V motor drive system is compared with the 42-V drive system directly powered by the 42-V battery. To improve the performance of the propulsion system, two modifications are proposed in this paper. First, terminal-quantities-based accurate voltage and current model flux observers (CMFOs) are designed, which can be used for any off-the-shelf machine. Second, a current model flux-observer-based sensorless controller is presented, which eliminates the need for the speed sensor on the rotor shaft, thus reducing the cost as well as the maintenance of the drive system. The proposed terminal-quantities-based flux observers and sensorless controller form the core of direct and IFO controllers commonly used in any alternative energy vehicular application including the ISA. The designed voltage model flux observer is insensitive to the stator resistance, and the CMFO is insensitive to the rotor resistance and speed, thus overcoming the long-standing problems in the area of flux observer design. The experimental results obtained while driving the vehicle are presented to demonstrate the effectiveness of the prototype ISA and to investigate its performance requirements as a sensorless drive system. Finally, the performance of the proposed flux observers and sensorless controller is evaluated through experimental results on a prototype induction machine to evaluate their potential for implementing a sensorless ISA drive system.

A Direct-Flux-Vector-Controlled Induction Generator With Space-Vector Modulation for Integrated Starter Alternator

A direct-flux-vector-controlled scheme of induction generator has been proposed in this paper for future 42-V automobile application. The fundamental relationship between the rotating speed of the stator flux vector and torque is analyzed. A simple structure with only one proportional-integral (PI) controller is shown to implement the torque and flux controls adequately. By controlling the electromagnetic torque of the induction machine, the required dc-bus voltage can be well regulated within the 42-V PowerNet specifications. Fixed switching frequency and low torque ripple are obtained with space-vector modulation technique. Simulation and experimental results indicate that the proposed scheme provides a practical solution for an integrated starter alternator other than the widely applied field-oriented- control scheme.

Modeling and Simulation of Various Hybrid-Electric Configurations of the High-Mobility Multipurpose Wheeled Vehicle (HMMWV)

Although hybrid-electric vehicles have been studied mainly with the aim of increasing fuel economy, little has been done in order to improve both fuel economy and performance. However, vehicular-dynamic-performance characteristics such as acceleration and climbing ability are of prime importance in military vehicles such as the high-mobility multipurpose wheeled vehicle (HMMWV). This paper concentrates on the models that describe hybridized HMMWV vehicles and the simulation results of those models. Parallel and series configurations have been modeled using the advanced-vehicle-simulator software developed by the National Renewable Energy Laboratory. Both a retrofit approach and a constant-power approach have been tested, and the results are compared to the conventional model results. In addition, the effects of using smaller engines than the existing ones in hybrid HMMWV drive trains have been studied, and the results are compared to the data collected from an actual implementation of such a vehicle. Moreover, the integrated-starter/alternator (ISA) configuration has been considered, and the results were encouraging

Parameter determination of an induction machine for integrated starter alternator

This paper presents a study on parameter variations of an induction machine for integrated starter alternator (ISA) with respect to stator frequency, magnetisation and slip frequency. No-load and stand-still tests are conducted under variable-frequency and variable-voltage instead of conventional constant frequency tests, using a PWM inverter in order to obtain the variations of rotor resistance, rotor leakage inductance, magnetising inductance and core-loss. In addition to these tests, impressed stator voltage and impressed stator current tests are carried out. Theory, analysis and results of the above parameter determination methods are presented. The parameter variations obtained from the variable-frequency variable-voltage no-load and stand-still tests are compared with conventional tests parameters as well as the parameters obtained from impressed stator voltage and stator current tests. The parameter variations found in this study can be used to obtain a detailed model that predicts the behaviour of the induction machine over wide speed range and under dynamic loading conditions more precisely than the conventional constant parameter model.

Starting engines and powering electric loads with one machine

The integrated starter alternator is an AC alternator with an electronic rectifier in which the functions of the starting engine and the generation of electric power are fulfilled by one electric machine on a vehicle, instead of two separate electric machines as in a traditional automotive vehicle. The objective of this article is to provide a guideline to ISA engineers and other automotive engineers as well as people who are interested in the mild-hybrid electric vehicles. The differences and similarities in the machine design of two ISA systems namely the crankshaft ISA and belt-driven alternator starters (BAS) are also addressed in this article