Integrated Starter Generator Research Articles

Combustion mode switching control in a HCCI diesel engine

HCCI (Homogeneous Charge Compression Ignition) combustion has the potential to significantly reduce NOx and PM emission of diesel engines due to its nature of even mixture and low temperature combustion. This combustion mode is only applicable in part load and low speed area so far. This range limitation results in frequently combustion mode switching from HCCI to CI and vice versa in real applications. HCCI realized by late injection with heavy EGR rate is investigated, which is also named PCCI (Premixed Charged Compression Ignition) sometimes. By changing control parameters (including injection timing, injection pressure and EGR rate) individually, the influences of these parameters on HCCI combustion and emissions are identified. Based on the evaluation of the influences, one pre-defined step-by-step air–fuel coordination strategy is presented. Additionally one hysteresis combustion mode determination method is proposed to avoid target mode fluctuation due to variation of engine speed or engine load in a small range. Torque deficiency occurs in acceleration transients as a result of fuel limitation to reduce soot emission, especially during HCCI to CI transitions. One ISG (Integrated Starter Generator) motor is applied to perform dynamic torque compensations in transient operations. Engine friction torque is estimated by means of cylinder pressure information from in-cylinder pressure sensors. On the basis of torque estimation, the difference between desired engine brake torque and actual engine brake torque is obtained. The torque output of ISG motor accounts for this torque gap and the torque pre distributed to ISG motor. The strategy is verified by engine tests. Experimental results indicate that, with the finely defined air–fuel coordination, less unstable combustion occurs and the target modes are established more quickly during transitions both in steady states and in transients. The torque deficiency during acceleration operations could be well compensated by the ISG motor.

Power-Split Hybrid Electric Vehicle Energy Management Based on Improved Logic Threshold Approach

We design an improved logic threshold approach of energy management for a power-split HEV assisted by an integrated starter generator (ISG). By combining the efficiency map and the optimum torque curve of internal combustion engine (ICE) with the state of charge (SOC) of batteries, the improved logic threshold controller manages the ICE within its peak efficiency region at first. Then the electrical power demand is established based on the ICE energy output. On that premise, a variable logic threshold valueKis defined to achieve the power distribution between the ISG and the electric motor/generator (EMG). Finally, simulation models for the power-split HEV with improved logic threshold controller are established in ADVISOR. Compared to the equally power-split HEV with the logic threshold controller, when using the improved logic threshold controller, the battery power consumption, the ICE efficiency, the fuel consumption, and the motor driving system efficiency are improved.

Power management of parallel hybrid electric power train

This paper presents an integrated and detailed procedure to improve the power management feature implemented in the integrated starter-generator (ISG) parallel hybrid electric vehicle. First, the configuration of the single-shaft ISG hybrid vehicle model established in MATLAB-Simulink environment is given. The vehicle model then is validated by comparing the experimental measurements and the simulation predictions of the traditional vehicle. The baseline rule based control strategy and the optimal control strategy using the dynamic programming (DP) algorithm are introduced. Finally, a suboptimal control strategy which employs the new control rules extracted from the optimal control strategy is designed with the remarkable fuel consumption performance.

Research on a diesel HCCI engine assisted by an ISG motor

HCCI combustion can substantially reduce NOx and soot emissions of diesel engines. However it is hard for diesel HCCI to obtain the same level of fuel economy as traditional diesel engines. This paper presents a way to improve the fuel economy of diesel HCCI by adopting Integrated Starter Generator (ISG). A set of diesel parallel hybrid power system (in this article, we name it “hybrid engine”) is constructed by installing an ISG motor on a diesel engine, which applies HCCI–CI combined combustion. Based on a lot of investigation on diesel HCCI, this paper is focus on improving HCCI engine performance, especially the fuel economy, by adopting ISG motor assist control. The coordination control strategies of engine and ISG motor in HCCI transient states, HCCI–CI transition, engine quick start and braking energy regeneration are developed. The results of equivalent New European Driving Cycle (NEDC) tests show that, by using ISG assistance, the fuel consumption of the diesel HCCI engine is greatly reduced. Meanwhile the NOx and soot emission are also improved.

A Permanent Magnet Integrated Starter Generator for Electric Vehicle Onboard Range Extender Application

This paper deals with a permanent magnet (PM) brushless machine used for integrated starter generator (ISG) in an electric vehicle (EV) onboard range extender (ORX). Proper machine configuration selection is briefly introduced. Then, ISGs with both surface-mounted PM (SPM) and interior PM (IPM) rotors have been developed for comparatively analysis. Some techniques for eddy current loss reduction are discussed, while influence of the rotor protecting sleeve material and thickness, axial segmental sleeves, and short circuit rings (ShCRs) around each magnet are particularly investigated. Subsequently, experimental results as of the starter and generator are presented respectively. Moreover, cost evaluation is also presented.

Design Considerations for Low Voltage Claw Pole Type Integrated Starter Generator (ISG) Systems

Due to the need for improved fuel consumption and the trend towards increasing the electrical content in automobiles, integrated starter generator (ISG) systems are being considered by the automotive industry. In this paper, in order to change the conventional generator of a vehicle, a belt driven integrated starter generator is considered. The overall ISG system, the design considerations for the claw pole type AC electric machine and a low voltage very high current power stage implementation are discussed. Test data on the low voltage claw pole type machine is presented, and a large current voltage source DC/AC inverter suitable for low voltage integrated starter generator operation is also presented. A metal based PCB (Printed Circuit Board) power unit to attach the 4-parallel MOS-FETs is used to achieve extremely high current capability. Furthermore, issues related to the torque assistance during vehicle acceleration and the generation/regeneration characteristics are discussed. A prototype with the capability of up to 1000 A and 27 V is designed and built to validate the kilo-amp inverter.

Optimisation multiphysique d’alterno-démarreurs par combinaison de modèles analytiques et éléments finis

The article describes an optimal multiphysic design method for automotive starter generators. The method is based on the association of analytical or semi analytical models (3D thermal lumped parameters network, electrical circuit theory with Park hyothesis, mechanical stress calculation) and finite elements models (2D flux density). These models are then implemented in a deterministic optimization loop. A synchronous permanents magnet integrated starter generator sizing illustrates the methodology interest.

Start and acceleration optimization of a parallel hybrid electric vehicle

The main issues relating to hybrid electric vehicle (HEV) emissions are starting and transient air-fuel ratio (AFR) control. The idle-cancelling function of an HEV will postpone the catalyst activation at cold start. So it is vital to confine the start emission to a much lower level. The conventional transient fuel also dramatically deteriorates emissions. The start and transient acceleration control strategies were developed on a uni-axis integrated starter–generator (ISG) parallel HEV. The optimization of each stage of the start process was realized. The start parameters of the engine controller (ECU) and vehicle controller (VCU) were determined by analysing unsuccessful starts. The results show that the engine starts smoothly without much speed overshoot. The AFR is superior to that of the prototype vehicle. At warming-up start and hot start there is also a smooth transition from ambient oxygen ratio to stoichiometric AFR. The concept is introduced of ‘fast’ and ‘slow’ torque to ISG boost acceleration. The conventional engine fuel wetting effect is overcome by ISG boost. The engine transient fuel and acceleration fuel compensation (AFC) for vehicle acceleration were replaced by ISG transient torque and continuous torque. The ISG boost acceleration calibration was completed and validated the result that the transient AFR was optimized without sacrificing vehicle drivability or acceleration performance. Both ISG start and ISG boost acceleration are effective approaches to solve the problem of HEV emission.

Permanent-Magnet Flux-Switching Integrated Starter Generator With Different Rotor Configurations for Cogging Torque and Torque Ripple Mitigations

This paper investigates the cogging torque and torque ripple features of a permanent-magnet flux-switching integrated starter generator. The effects of the rotor pole arc width on the cogging torque, torque ripple, and output torque are first established using finite-element analysis (FEA). Three torque ripple reduction techniques based on the optimization of three different rotor pole configurations, namely, uniform, step skewed, and axial pairing, are then proposed. The torque characteristics of each rotor configuration at varying load currents and phase angles are studied in detail. A prototype machine with a common stator and the three optimized rotor configurations are built for experimental validation. Both the FEA results and the experimental tests show that the step skewed and axial pairing techniques can alleviate the cogging torque significantly, but the latter is less effective than the former in reducing the overall torque ripple.

Modeling and Simulation of Direct Torque Controlled PMSM for PHEV

Direct torque control (DTC) method for permanent magnet synchronous motor (PMSM) used as Integrated Starter/Generator (ISG) in PHEV was analyzed. The DTC PMSM model, with PI produced a voltage space vector based on torque PI regulator and flux linkage PI regulator, was built up based on Matlab /Simulink and all simulation blocks were discussed. The results showed that this scheme was simple and effective, also had a good robustness. It is easy to realize in PHEV application, while to keep the fast torque response and little flux linkage and torque fluctuation.

A Permanent-Magnet Hybrid Brushless Integrated Starter–Generator for Hybrid Electric Vehicles

A new permanent-magnet (PM) hybrid brushless (PMHB) machine is proposed and implemented as the integrated starter-generator (ISG) for hybrid electric vehicles (HEVs). It has the advantages of higher torque density than other PMHB machines and much wider speed range than other PM brushless machines. The key is to tune its dc-field winding current in such a way that three major modes of ISG system operation for HEVs, namely, engine cranking, battery charging, and torque boosting, can be achieved effectively. The finite-element method is employed to simulate its steady-state and dynamic performances. Finally, a 2-kW prototype is constructed and tested to experimentally verify the simulation results and the validity of the proposed ISG system.

Design of a Switched Reluctance Generator Drive System for Hybrid Electric Vehicles

In this paper, the design and implementation of a 12/10 poles 6-phase switched reluctance generator (SRG) drive system for hybrid electric vehicles (HEVs) is investigated. Firstly, the principle of the SRG, its control parameters and operation characteristics are analyzed. Then, according to the requirements of the SRG using as an integrated starter generator for HEVs, an optimized switch angle position with current chopping control method is proposed to regulate the SRG power output. In order to improve the charge performance and extend the service life, the lead-acid battery group uses a two-stage charge mode, which is realized by two digital power regulators of the SRG. After that, an experimental system is set up and the controller's internal circuit is described. At last, the proposed SRG drive system is verified by experimental results.

An Online Power-Balancing Strategy for a Parallel Hybrid Electric Vehicle Assisted by an Integrated Starter Generator

Power-flow-control techniques that are capable of handling inefficiencies of both the electric motor/generator (EMG) and the internal combustion engine (ICE) are required to fully explore the fuel-saving potential of fully hybridized parallel hybrid electric vehicles (PHEVs). We propose an online power-flow-control strategy for fully hybridized PHEVs based on the power-balancing strategy (PBS), which controls the ICE within its peak-efficiency region by using the electrical system. We introduce a new PHEV assisted by an integrated starter generator (ISG) or ISG-assisted PHEV, in which the ISG supports the downsized EMG to maintain the electrical system's efficiency close to its peak efficiency and, therefore, to enhance the fuel-saving capability of the PBS controller. The key contributions of this study are given as follows: 1) identification of the ICE's peak-efficiency region as a function of the discharging and recharging efficiencies of the electrical system; 2) a new more fuel-efficient HEV architecture; and 3) proper regulation of the state of charge while maintaining infrequent stopping and restarting of the ICE by direct control of the ICE's energy output. Results show that the PBS controller achieves fuel efficiencies similar to the offline benchmark controller using the equivalent consumption minimization strategy. The PBS controller saves up to 9.3% of fuel on the ISG-assisted PHEV, compared with an equally powered PHEV without the ISG.

Rotor-Design Strategy of IPMSM for 42 V Integrated Starter Generator

In this paper, we proposed an optimal design strategy of interior permanent magnet synchronous machine (IPMSM) considering various design constraints in the 42 V integrated starter generator (ISG). Since conventional optimal process needs much calculating time to check many constraints such as high starting torque, the high generating power at the maximum speed, we adopted AT-MGPSO as an optimization algorithm due to its special advantage that it can efficiently search superior peaks in the multimodal problem with short time. In addition, in order to deal with mechanical stress in the rotor by centrifugal force at maximum speed we combined mechanical stress analysis with the optimal design process. The validity of our proposed methods was verified by comparing simulation results with experimental data.

Optimal control of brushless PM motor in parallel hybrid propulsion system

The paper outlines a case study on optimal control of a brushless direct-current (BLDC) motor as a part of an Integrated Starter-Generator and torque Booster (ISGtB) application in a hybrid propulsion system. The main scope of the introduced research work is the optimization of the BLDC motor torque characteristics. The discussed hybrid propulsion system consists of an internal combustion (IC) engine and a BLDC machine and is in its origin intended to drive the motorcycle. Stringent starting torque demands, electrical machine geometry limitations and a wide rotational speed range of the BLDC motor are reasons for control algorithm analysis in the low-speed operation range. Two approaches for the optimization of the torque characteristics are discussed, the flux-weakening method and a modification of transistor conduction angle. A novel control principle which includes both of the above approaches is proposed. A comparison between a commonly used control method and the proposed control method is presented. Simulation and experimental results fully confirm improvements in the starting procedure of the hybrid propulsion system attained by the proposed control algorithm of the BLDC motor.

ISG hybrid powertrain: a rule-based driver model incorporating look-ahead information

According to European regulations, if the amount of regenerative braking is determined by the travel of the brake pedal, more stringent standards must be applied, otherwise it may adversely affect the existing vehicle safety system. The use of engine or vehicle speed to derive regenerative braking is one way to avoid strict design standards, but this introduces discontinuity in powertrain torque when the driver releases the acceleration pedal or applies the brake pedal. This is shown to cause oscillations in the pedal input and powertrain torque when a conventional driver model is adopted. Look-ahead information, together with other predicted vehicle states, are adopted to control the vehicle speed, in particular, during deceleration, and to improve the driver model so that oscillations can be avoided. The improved driver model makes analysis and validation of the control strategy for an integrated starter generator (ISG) hybrid powertrain possible.

Optimization of Control Strategy for Medium Hybrid Electric Vehicle with ISG at Drive Condition

Based on the vehicle dynamics theory,the system efficiency of medium hybrid electric vehicle with ISG (Integrated starter/Generator) is instantaneously optimized,and then,the control strategy of medium hybrid electric vehicle(Medium-HEV) is obtained.The three important coefficients and their spans in this control strategy are defined,including battery shifting factor X SC,the charging curve factor of engine Xe_chg and the shutting off curve factor of engine Xe_off.By setting up simulation models of medium-HEV to calculate the equivalent fuel consumption of battery △SC based on Matlab/Simulink,the three important coefficients are optimized with the aim of minimizing the integrated fuel consumption of hybrid system,thereby the matching and optimal control strategy of hybrid system are determined.Simulation results indicate that the fuel consumption of medium HEV is reduced by 36.95% comparing with conventional vehicle,thus greatly improving the fuel economy.

Integrated Starter Generators

Two variants of permanent magnet (PM) based integrated starter generator (ISG) machines were compared for use during development of a new hybrid electric vehicle (HEV). Such a system design generally has high efficiency requirements, mainly regarding high power/weight ratio at minimal size. another criteria is high reliability for high-speed operation. In a study of Ricardo, two types of ISG were compared: one with permanent magnets placed on the surface of the rotor and the other with magnets integrated within the rotor core.

Integrated starter generators

Two variants of permanent magnet (PM) based integrated starter generator (ISG) machines were compared for use during development of a new hybrid electric vehicle (HEV). Such a system design generally has high efficiency requirements, mainly regarding high power/weight ratio at minimal size. Another criteria is high reliability for high-speed operation. In a study of Ricardo, two types of ISG were compared: One with permanent magnets placed on the surface of the rotor and the other with magnets integrated within the rotor core.

Integrated starter generator

Various types of electric machines can be considered for an application to integrated starter generator (ISG). Permanent magnet (PM) synchronous machines present interesting performances; nevertheless, it remains difficult to reach a significant constant power zone under good efficiency conditions and power factor. The loss of control of electronics at high-speed operations may lead to high-terminal voltages, which can become dangerous for the whole vehicle. In this study, we examine the main advantages and drawbacks of the induction machine, reluctant, and PM machine. Then we present more precisely the wound rotor synchronous machine (WRSM) performances for ISG applications. All these machines must follow strict rules and specifications (low length, high torque, speed, and efficiency). Different kinds of machines have already been evaluated.