Braking Operation Research Articles

Approaching and stopping behaviors to the intersections of aged drivers compared with young drivers

According to the many reports of the traffic accidents, the number of the accidents near the intersections was increased in the cases of the aged drivers. The purpose of the research was to measure the sensitivity of elder drivers through behavioral responses in approaching and stopping to the intersections and to obtain the difference of the responses for braking and stopping comparing with young drivers. In the field tests of real running on experimental proving ground, elder and young drivers were observed their driving behaviors in various conditions of approaching and stopping at intersections. Comparing the results of the elder with the young, the unstable driving behaviors were examined in elderly and they were apt to run fast in approaching the intersection and also stopping rapidly. The rates of deceleration change (Jerk) with braking operation were unstable and the driving behaviors were affected by the environments or conditions of the intersection. These driving performances should be interfered with the traffic flow and exposed to the risk of accidents. If the features of these aged driver's behaviors were clarified better, the more effective driving assistant systems for elderly could be developed based on characteristics of elderly driver's driving performances and their physical and psychological features of driving.

Incorporated Operation Control of DC Microgrid and Electric Vehicle

This paper presents the establishment and operation control of a dc microgrid incorporating with electric vehicle (EV) as movable energy storage. The developed microgrid consists of a wind permanent-magnet synchronous generator ac source and a dc source, a battery/supercapacitor (SC)/flywheel hybrid energy storage system, and a grid-connected bidirectional single-phase three-wire (1P3W) load inverter. Various harvested ac and dc sources can be plugged into the microgrid via the developed interfaced power converters. In addition to good microgrid operation performance, the microgrid-to-grid and grid-to-microgrid operations can be successfully conducted with good power quality. As to the developed EV interior permanent-magnet synchronous motor drive, the SC auxiliary storage is equipped to assist the main battery source in intermittent energy conversion. Satisfactory acceleration/deceleration/reversible and regenerative braking operation characteristics are obtained via the developed power stages and control schemes. Moreover, the successful microgrid-to-vehicle and vehicle-to-microgrid interconnected operations of EV and microgrid are achieved. In addition, the vehicle-to-grid/grid-to-vehicle operations can be also performed via the developed 1P3W inverter.

Analysis of forces in single‐side linear induction motor with lateral displacement for linear metro

This study investigates the influence of lateral displacement of the primary on the thrust, vertical and lateral forces in a single-side linear induction motor for linear metro. A three-dimensional analytical model, which is able to consider the longitudinal and transversal end effects, overhang of the primary windings and lateral displacement, is developed to obtain the air-gap flux density distributions along longitudinal and transverse directions as well as forces. Variations of the thrust, vertical and lateral forces with the lateral displacements are comprehensive investigated when the motor is torque motoring, negative sequence braking or regenerative braking operation. The analytically predicted results are experimentally validated by measurements on reciprocal power-fed test rig. It shows that the thrust and vertical force of single-side linear induction motor decrease almost linearly with the increase of the lateral displacement in all regions, and lateral force is restoring which helps centralising the railcar in the regenerative braking and most parts of motoring regions.

Effects of Rotor Position Error in the Performance of Field Oriented Controlled PMSM Drives for Electric Vehicle Traction Applications

This paper analyzes the effects of the rotor position error in the performance of field-oriented-controlled permanent-magnet synchronous machine (PMSM) drives intended for electric vehicle (EV) traction applications. A special focus is given to the torque ripple generated along the characteristic trajectories in the different operating regions of the PMSM. An extended and generalized model of the torque ripple produced by the PMSM as a function of the rotor position error is analytically deduced. An infinite-speed interior-(I)PMSM drive and a finite-speed surface-mounted (SM)-PMSM drive are considered for the simulations carried out in MATLAB-SimPowerSystems. The experimental results have been validated with a TM4 EV drive controlling an 80-kW SM-PMSM. The torque ripple has been evaluated for both motoring and regenerative braking operation modes under maximum torque conditions going from 100 N · m at 1000 r/min up to 55 N · m at 9000 r/min. The obtained simulation and experimental results demonstrate the good accuracy of the proposed model for evaluating the torque ripple produced in PMSMs due to the error from the rotor position sensor.

Development of a Simulink-CarSim Interaction Package for ABS Simulation of Discrete Tire Models

ABSTRACT Automotive and tire companies have to spend extensive amounts of time and money to tune their products through prototype testing at dedicated test facilities. This is mainly because of the limitations in the simulation capabilities that exist today. With greater competence in simulation comes more control over designs in the initial stages, which in turn lowers the demand for the expensive stage of tuning. This article aims at taking today's simulation capabilities a step forward by integrating models that are best developed in different software interfaces. An in-plane rigid ring tire model has been developed to understand the transient response of tires to various high-frequency events such as antilock braking and short-wavelength road disturbances. A rule-based antilock braking systems (ABS) model performed the high-frequency braking operation. The tire and ABS models were created in the Matlab-Simulink environment. A vehicle model was developed in CarSim. The models developed in Simulink were integrated with the vehicle model in CarSim, in the form of a design tool that can be used by tire as well as car designers for further tuning of the vehicle functional performances, as they relate to handling and braking maneuvers. The straight-line ABS performance was predicted using these models for a sample vehicle, and the results were substantiated through physical outdoor tests on the same vehicle to validate the developed integration package. The tool development, simulation results, and the objective test will be discussed.

Characterization of surface morphology and its correlation with friction performance of brake pads

The present work presents the morphology evolution of a brake material surface submitted to braking tests through a laboratory-scale tribometer. Optical microscope images of the material’s surface were obtained for every 10 braking operations. These images were post-processed in appropriate computational software. By means of the image segmentation technique, morphological parameters related to the brake material surface were estimated. The wear rate and also the coefficient of friction resulting from the tests were measured. For the NAO material used in this study, the friction behaviour revealed to be strongly associated with the amount of contact plateaus. Besides, the mean area of the contact plateaus was the main factor responsible for increasing the real contact area of the friction material. The higher wear rate observed in the first braking operations can be mainly attributed to the higher surface roughness measured in this condition. As the braking operations progress, the plateaus becomes flatter and wear rate is reduced. Finally, the image segmentation technique proved adequate for investigating morphological aspects in friction material surface.

Efficient braking energy recovery using bidirectional step-up converter in fuel cell and battery electric vehicles

The topology of the power conditioning unit (PCU) that is used with energy storage system (ESS), has a vital role especially in braking energy recovery. In recent studies, conventional bidirectional half-bridge topology is widely used as a PCU for ESSs. Due to its structure, it does not have the capability of capturing braking energy when the voltage across the motor terminals is lower than ESS voltage. This study investigates the feasibility of utilising a PCU with stepping up capability in regenerative braking operation mode, focusing on the additional braking energy that can be captured in comparison with that of the conventional half-bridge buck/boost converter. In order to verify the advantageous of the proposed approach in braking energy recovery, two 1 kW prototypes, a conventional half-bridge buck-boost and cascaded buck-boost converters are designed and tested for three different drive cycles including normalised version of ECE-15.

自動走行車両が緊急事態を回避するための制御系（実数型免疫アルゴリズムを用いた操縦波形生成法）

With the development of the modern vehicle industry, research and development of intelligent transport system has been undertaken. As an active safety feature, there is a need to develop a system with an appropriate steering and braking operation for accident avoidance. In this study, it is assumed that an automatic vehicle, which runs on the highway, encounters an obstacle in distance of collision by braking without steering operation. Our study aims to find operations that the vehicle can perform to avoid an obstacle by a combination of steering and braking. This paper proposes a method to generate operating waveforms using an immune algorithm (IA) that can generate plural quasi-optimum solutions. CarSim (Mechanical Simulation Company), which possesses full vehicle dynamics with 27 degrees of freedom, is adopted as the vehicle model in our study. Inputs for this model include wheel steering angle and brake pressure. Operation waveforms are generated by linear interpolation through designated data points. Real number type IA, which is coded real number expression, is adopted in order to find data points. The efficacy of the proposed method is verified through an emergency avoidance simulation using CarSim. The simulation result demonstrates operation patterns to avoid an obstacle; in addition, real number type IA is shown to perform better than conventional binary type in a search performance of the solution.

Modeling of thermal contact problem of disc brake system with frictional heat generation

Safety aspect in automotive engineering has been considered as a number one priority in development of new vehicle. Each single system has been studied and developed in order to meet safety requirement. Instead of having air bag, good suspension systems, good handling and safe cornering, there is one most critical system in the vehicle which is brake systems. The objective of this work is to investigate and analyze the temperature distribution of rotor disc during braking operation using ANSYS Multiphysics. The work uses the finite element analysis techniques to predict the temperature distribution on the full and ventilated brake disc and to identify the critical temperature of the rotor. The analysis also gives us, the heat flux distribution for the two discs.

Friction and wear behavior of copper matrix composite for spacecraft rendezvous and docking under different conditions

The tribological properties of a copper matrix composite (Cu-MMC) for use in spacecraft rendezvous and docking operations were investigated using a special ground system that was capable of testing at various temperatures and pressures. The temperature range was between −100°C and +100°C, and pressures ranged from ambient to as low as 1×10−4Pa. The results indicate that the friction and wear behavior were identified as a function of the operation conditions. During braking operations, Cu-MMC showed the steady-state friction characteristics in air at 25°C and in vacuum at −100°C. In vacuum at 25°C and 100°C, the mean friction coefficients (μmean) exhibited significant fluctuations and the wear rates increased remarkably. While in the process of clutching operations, the tribological performances showed little sensitivity to friction cycles in air at 25°C, in vacuum at 25°C and 100°C. But the friction became unstable in vacuum at −100°C. Examinations, analyses and profiles of the friction surfaces and subsurfaces corroborated the correlation between environments and tribological behavior and wear mechanism.

Modeling of thermal contact problem of disc brake system with frictional heat generation

Safety aspect in automotive engineering has been considered as a number one priority in development of new vehicle. Each single system has been studied and developed in order to meet safety requirement. Instead of having air bag, good suspension systems, good handling and safe cornering, there is one most critical system in the vehicle which is brake systems. The objective of this work is to investigate and analyze the temperature distribution of rotor disc during braking operation using ANSYS Multiphysics. The work uses the finite element analysis techniques to predict the temperature distribution on the full and ventilated brake disc and to identify the critical temperature of the rotor. The analysis also gives us, the heat flux distribution for the two discs.

Energy Management and Control of Electric Vehicles, Using Hybrid Power Source in Regenerative Braking Operation

Today’s battery powered electric vehicles still face many issues: (1) Ways of improving the regenerative braking energy; (2) how to maximally extend the driving-range of electric vehicles (EVs) and prolong the service life of batteries; (3) how to satisfy the energy requirements of the EVs both in steady and dynamic state. The electrochemical double-layer capacitors, also called ultra-capacitors (UCs), have the merits of high energy density and instantaneous power output capability, and are usually combined with power battery packs to form a hybrid power supply system (HPSS). The power circuit topology of the HPSS has been illustrated in this paper. In the proposed HPSS, all the UCs are in series, which may cause an imbalanced voltage distribution of each unit, moreover, the energy allocation between the batteries and UCs should also be considered. An energy-management scheme to solve this problem has been presented. Moreover, due to the parameter variations caused by temperature changes and produced errors, the modelling procedure of the HPSS becomes very difficult, so an H∞ current controller is presented. The proposed hybrid power source circuit is implemented on a laboratory hardware setup using a digital signal processor (DSP). Simulation and experimental results have been put forward to demonstrate the feasibility and validity of the approach.

A New Powertrain System for Electric Hybrid Vehicles

A new powertrain system was developed for electric vehicle driving application with adoption of one electric motor and one set of planetary gear set. With the control of fork, the sleeve of synchronizer can mesh two different parts on the left and right side; the system can provide pure electric driving, hybrid driving and regenerative braking operation modes to meet vehicle practical conditions. It can reduce both power train structure size and cost with fewer parts.

Possibility research of the use of energy reserve of aerial ropeway drives taking into account the twisting forces diagrams

Purpose. It is necessary to study the formalization of approaches to determination of energy reserves of aerial ropeways drives taking into account the twisting forces diagrams. Methodology. To determine the energy reserves the twisting forces diagrams were used. A method is based on the comparative analysis of areas of braking and power operation modes of ropeway drive. Their area depends on the road profile (length and overfall of clearance heights, carrying rope deflection) and location of the drive station (on the lower or the upper supporting points). Findings. The application of the method of energy accumulation in the braking mode with its subsequent consumption in the power mode enables to use the energy reserves of drives. Taking into account the relief, it is possible on the stage of planning to set the parameters the road profile, as well as to locate the drive station so that on the twisting forces diagram the areas of braking mode alternated with the areas of the power mode and were approximately equal in size. This, in turn, will save the electric power in the process of operation. Originality. The approach to determination of energy reserves of the aerial ropeway drives is offered. Practical value. The use of the offered method will help (before the construction) to calculate such a road profile, which will increase the areas of braking mode. The latter in turn will positively affect the size of the accumulated energy.

Fail-safe control allocation for a distributed brake-by-wire system considering the driver’s behaviour

A distributed brake-by-wire system provides flexible and precise braking force control with shorter or no brake pipes. Fail-safe control is a critical part of the system which guarantees braking safety during failure of the brake actuators. The purpose of this paper is to develop a fail-safe control strategy that cooperates better with the driver so as to enhance the fail-safe control performance. Therefore, the driver’s behaviour should be taken into account during the design of fail-safe control strategies. Two design goals considering the driver’s behaviour are proposed. The first concerns the braking performance; the second concerns whether the driver can handle the failure situation easily. A qualified fail-safe control strategy should meet both the design goals. The driver model used includes an anti-wind-up proportional–integral controller braking operation model and an optimal preview control steering operation model. Two different fail-safe control strategies, namely strategy I and strategy II, are proposed and examined with the design goals. Strategy I is designed to follow the nominal motions of the vehicle in all the three degrees of freedom in the yaw plane. The pseudo-control vector is determined by sliding-mode controllers and allocated to follow the nominal motions. Strategy II is designed to minimize the braking force imbalance between the left side and the right side of the vehicle on the premise that the brake deceleration demand has been achieved. Simulation results show that strategy I generates a longer braking distance and requires a harder brake pedal force, which violates both the design goals. Strategy II meets both the design goals and therefore is a qualified strategy to cooperate with the driver model. Its capability to be implemented in real time is verified on a hardware-in-the-loop test bench. Its advantages considering the unmodelled behaviour of the driver is also discussed. The distributed electrohydraulic braking system developed is used as the distributed brake-by-wire system.

Bidirectional Quasi Z Source Inverter with Fuzzy Logic Controller for Traction Motor Speed Control

The Fuzzy Logic Controller is implemented to control the speed of the electric vehicle applications. The speed and output voltage of the motor, controlled by Proportional Integral (PI) controller and Fuzzy Logic Controller can be compared. During starting and braking of the electric vehicle applications the performance comparison is done. The reverse power flow is obtained by Bidirectional Quasi-Z-source inverter (BQ-ZSI). The inverter with the design and operation is analyzed. The Electric vehicles and hybrid electric vehicles are emerging vehicles in the future generation. The power flow and speed can be controlled during starting and braking of the vehicles .The comparison of the speed control using PI and Fuzzy controller is done and output results. The simulation results are presented to prove the functionality of the circuit and the effectiveness of the proposed control strategy. Index Terms: Bidirectional quasi-Z-source inverter (BQ-ZSI), electric vehicle (EV) applications, feed-forward compensation, reverse power flow, small signal model. I. Introduction The evolution of Electric Vehicles (EV) creates a global push and provides better replacement of the fuel based vehicles. The Vehicles are charged by batteries and the power flow during starting and braking operations can be designed by Bidirectional quasi Z Source Inverter. The power (SDP) by 15% over the dc-dc converter with the VSI topology, which reduces the total cost and further improves the efficiency of the traction drive system . However, the input current of ZSI is not continuous, which will shorten the lifetime of the battery pack and degrade the vehicle performance. By rearranging the components in the Z-source network, a new topology called quasi-Z-source inverter (QZSI) is proposed. The QZSI realizes the continuous input current, at the same time retaining all the merits of the ZSI, which makes it a good candidate for EV applications. However, the traditional QZSI only allows unidirectional power flow from the dc to the ac side. The traction drive system requires the reverse power flow to realize the regeneration break of the EV. To achieve the bidirectional power flow capability, the same approach as in is utilized and the diode in the quasi-Z-source network (QZSN) is replaced by an active switch. A similar approach is also utilized in the bidirectional ZSI .However, much of the previous operation mode analysis was based on the topology of the ZSI and mainly focused on the power flow from the dc to the ac side. To better understand the circuit, this paper first gives a detailed circuit analysis of the bidirectional quasi-Z-source inverter (BQ-ZSI) during the regeneration mode, i.e., when the power flows from the ac to the dc side. The analysis proves that with the active switch, the inductor currents in the QZSN can be reversed and the energy from the ac side can be delivered to the dc source. The analysis also shows that, unlike in the ZSI, part of the dc link ripple current will be absorbed by the two capacitors in the QZSN and not go through the dc source, which provides a better operating condition for the battery pack in EV. Furthermore, with the additional switch, the discontinuous conduction mode (DCM) can be avoided and the BQ-ZSI can have a better performance with small inductance or under low power factor condition, such as when the electric motor is operated with a light load. Based on the circuit analysis, the small signal model can be obtained, and the control algorithm of the BQ-ZSI in EV applications can be developed. By rearranging the components in the Z-source network, a new topology called quasi-Z-source inverter (QZSI) is proposed. The QZSI realizes the continuous input current, at the same time retaining all the merits of the ZSI, which makes it a good candidate for EV applications.

Collision-mitigation level of collision-avoidance braking system

In this study, a methodology for estimating the collision mitigation ratio using collision-prevention support braking system is discussed. A method for analysing the collision-mitigation ratio is discussed through a time series Monte-Carlo simulation based on the integrated error of driver and system. First, driver performance in terms of braking timing and deceleration level for collision avoidance was investigated in a driving simulator when the control timing of the braking-support system was changed. In this analysis, the braking behaviour of the driver during malfunction of the system and this behaviour when the driver was informed about the malfunction of the system were also investigated. Next, a driver model simulating braking operation, when a preceding vehicle started slowdown, was constructed. Through time series Monte-Carlo simulations using this driver model, the frequency of collisions to a preceding vehicle and the collision velocity were estimated.

Improvement of Energy Efficiency in Light Railway Vehicles Based on Power Management Control of Wayside Lithium-Ion Capacitor Storage

The paper suggests an energy management control strategy of wayside Li-ion capacitor (LiC) based energy storage for light railway vehicles (LRV). The installation of wayside supercapacitor (SC) storage devices, as widely recognized, allows the recovery of the braking energy for increasing the system efficiency as well as a better pantograph voltage profile. A new type of SC, LiC, interfaced with dc-interleaved converter has been presented. This technology has an energy density comparable to batteries and power density much higher than the batteries. The authors propose a control strategy based on the maximum kinetic energy recovery throughout braking operations of the running vehicles. The stored energy comes back to the vehicles during the accelerations. The strategy stays on the knowledge of the state of charge of LiC device and the actual vehicle speeds. In particular, the control algorithm evaluates, in real time, the actual value of LiC voltage and current references on the basis of the vehicles inertial forces and acceleration estimations, taking into account the power losses of the system. Experimental tests made on electromechanical simulator, equipped with a 136-V, 30.5-F LiC module, fully confirm the validity of the suggested control. Finally, experimental characterization of LiC module has been achieved.

Energy-Regenerative Braking Control of Electric Vehicles Using Three-Phase Brushless Direct-Current Motors

Regenerative braking provides an effective way of extending the driving range of battery powered electric vehicles (EVs). This paper analyzes the equivalent power circuit and operation principles of an EV using regenerative braking control technology. During the braking period, the switching sequence of the power converter is controlled to inverse the output torque of the three-phase brushless direct-current (DC) motor, so that the braking energy can be returned to the battery. Compared with the presented methods, this technology can achieve several goals: energy recovery, electric braking, ultra-quiet braking and extending the driving range. Merits and drawbacks of different braking control strategy are further elaborated. State-space model of the EVs under energy-regenerative braking operation is established, considering that parameter variations are unavoidable due to temperature change, measured error, un-modeled dynamics, external disturbance and time-varying system parameters, a sliding mode robust controller (SMRC) is designed and implemented. Phase current and DC-link voltage are selected as the state variables, respectively. The corresponding control law is also provided. The proposed control scheme is compared with a conventional proportional-integral (PI) controller. A laboratory EV for experiment is setup to verify the proposed scheme. Experimental results show that the drive range of EVs can be improved about 17% using the proposed controller with energy-regeneration control.

A Compact and Integrated Multifunctional Power Electronic Interface for Plug-in Electric Vehicles

The basic power electronic interfaces rendering volume and weight of electric and plug-in hybrid electric vehicles are an inverter, an on-board charger, and a bidirectional dc/dc converter. This paper proposes an innovative integrated bidirectional converter with a single-stage on-board charger to reduce the number of switches, size, and weight of the power electronic interfaces. The analyses show that 266 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and 1.1 kg can be saved due to the elimination of the inductor core used for power factor correction in charging mode, in addition to the reduction achieved through removal of inductor winding, power switches, diodes, and additional heat sink of the conventional structures. A proof-of-concept prototype with power limits of 8.4 kW in charging and 20 kW in propulsion modes has been designed and validated at various power levels. The peak efficiencies for propulsion and regenerative braking operations are measured as 96.6% and 94.1%, respectively. The power factor is recorded as 0.995 at 1.8 kW charging power, where crest factor and peak efficiency are recorded as 1.49 and 91.6%, respectively.