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Technical Paper

Optimization and Implementation of Three-Phase PMSM Current Harmonic Decomposition Technique

2019-04-02
2019-01-0604
With the development of electric vehicle (EV), permanent magnet synchronous motor (PMSM) has received more and more attention. PMSM torque ripple suppression is one of the core technologies of PMSM control. Current harmonic injection method is a commonly used torque ripple suppression method. In order to accurately control the injecting current harmonics, it is necessary to quickly and efficiently decompose the three-phase PMSM current harmonics first. In this paper, an existing instantaneous harmonic decomposition method based on multiple reference coordinates is adopted. First, the causes of the analysis error of the harmonic decomposition technique are analyzed which are divided into internal factors (e.g. analysis errors generated during the discretization of continuous functions) and external factors (e.g. sampling errors). Analysis errors will directly affect the decomposition result.
Technical Paper

Impedance Modeling and Aging Research of the Lithium-Ion Batteries Using the EIS Technique

2019-04-02
2019-01-0596
As the core component of electric vehicles (EVs), batteries attach increasingly general attention along with the rapid expansion of electric vehicle market. Battery performance effect directly the safety and reliability of the EVs, so its managing technologies are more and more crucial. Among them, the methods of estimating the state of health (SoH) and predicting remaining useful life become the focuses, which are essential to ensure their dependability and optimum performance over time. This paper mainly focuses on impedance modeling and aging research (aging diagnosis and life prediction) of lithium-ion batteries. Electrochemical impedance spectroscopy (EIS) technique is used to obtain impedance characteristic of batteries. On the one hand, equivalent circuit modeling (ECM) can be motivated by EIS, with the goal to fit measured impedance data using circuit elements.
Technical Paper

Tracking of Extended Objects with Multiple Three-Dimensional High-Resolution Automotive Millimeter Wave Radar

2019-04-02
2019-01-0122
Estimating the motion state of peripheral targets is a very important part in the environment perception of intelligent vehicles. The accurate estimation of the motion state of the peripheral targets can provide more information for the intelligent vehicle planning module which means the intelligent vehicle is able to anticipate hazards ahead of time. To get the motion state of the target accurately, the target’s range, velocity, orientation angle and yaw rate need to be estimated. Three-dimensional high-resolution automotive millimeter wave radar can measure radial range, radial velocity, azimuth angle and elevation angle about multiple reflections of an extended target. Thus, the three-dimensional range information and three-dimensional velocity information can be obtained. With multiple three-dimensional high-resolution automotive millimeter-wave radar, it is possible to measure information in various directions of a target.
Technical Paper

Driver Behavior Classification under Cut-In Scenarios Using Support Vector Machine Based on Naturalistic Driving Data

2019-04-02
2019-01-0136
Cut-in scenario is common in traffic and has potential collision risk. Human driver can detect other vehicle’s cut-in intention and take appropriate maneuvers to reduce collision risk. However, autonomous driving systems don’t have as good performance as human driver. Hence a deeper understanding on driving behavior is necessary. How to make decisions like human driver is an important problem for automated vehicles. In this paper, a method is proposed to classify the dangerous cut-in situations and normal ones. Dangerous cases were extracted automatically from naturalistic driving database using specific detection criteria. Among those cases, 70 valid dangerous cut-in cases were selected manually. The largest deceleration of subject vehicle is over 4 m/s2. Besides, 249 normal cut-in cases were extracted by going through video data of 2000km traveled distance. In normal driving cases, subject vehicle may brake or keep accelerating and the largest deceleration was less than 3 m/s2.
Technical Paper

Model-Based Pitch Control for Distributed Drive Electric Vehicle

2019-04-02
2019-01-0451
On the dual-motor electric vehicle, which is driven by two electric motors mounted on the front and rear axles respectively, longitudinal dynamic control and electro-dynamic braking can be achieved by controlling the torque of front and rear axle motors respectively. Suspension displacement is related to the wheel torque, thus the pitch of vehicle body can be influenced by changing the torque distribution ratio. The pitch of the body has a great influence on the vehicle comfort, which occurs mainly during acceleration and braking progress. Traditionally active suspension is adopted to control the pitch of body. Instead, in this paper an ideal torque distribution strategy is developed to limit the pitch during acceleration and braking progress. This paper first explores the relationship between the torque distribution and the body pitch through the real vehicle test, which reveals the feasibility of the vehicle comfort promotion by optimizing the torque distribution coefficient.
Technical Paper

Numerical Analysis and Optimization Design of a Centrifugal Compressor’s Volute for PEM Fuel Cell Vehicle

2019-04-02
2019-01-0376
Centrifugal compressors used in polymer electrolyte membrane fuel cell systems are different from turbochargers in internal combustion engines, because they are required to work at high speed, low mass flow rate, narrow range which nears surge boundaries. In order to meet these requirements, a centrifugal compressor’s volute is designed, analyzed and optimized on its cross-section area, shape of volute tongue and tapered angle of exit. The numerical results show that surge boundary of the compressor is influenced by spiral area significantly and that volute tongue has a major impact on aerodynamic performances at high mass flow rates.
Technical Paper

Genetic Algorithm-Based Parameter Optimization of Energy Management Strategy and Its Analysis for Fuel Cell Hybrid Electric Vehicles

2019-04-02
2019-01-0358
Fuel cell hybrid electric vehicles (FCHEVs) composed of fuel cells and batteries can improve the dynamic response and durability of vehicle propulsion. In addition, braking energy can be recovered by batteries. The energy management strategy (EMS) for distributing the requested power through different types of energy sources plays an important role in FCHEVs. Reasonable power split not only improves vehicle performance but also enhances fuel economy. In this paper, considering the power tracking control strategy which is widely adopted in Advanced Vehicle Simulator (ADVISOR), a constrained nonlinear programming parameter optimization model is established for minimizing fuel consumption. The principal parameters of power tracking control strategy are set as the optimized variables, with the dynamic performance index of FCHEVs being defined as the constraint condition. Then, the genetic algorithm (GA) is applied in the control strategy design for solving the optimization problem.
Technical Paper

Real-Time Testing Technology of Powertrain System in Proton Exchange Membrane Fuel Cell Electric Vehicles: A Review

2019-04-02
2019-01-0371
The proton exchange membrane fuel cell (PEMFC) vehicle is one kind of new energy vehicle with fuel cell as power source, which has environmental friendliness, high power density and quick refueling. However, the productlization testing in powertrain system, especially for subsystems and key parts, is one of the critical technical challenges, which restricts the industry development and large-scale commercialization of fuel cell electric vehicles (FCEVs). In this paper, comprehensive testing requirement and latest testing technologies were reviewed, the development status and directions of testing technologies in FCEV powertrain system were presented. Based on comprehensive analysis, X-in-the-Loop (XiL) testing technology was proposed, and it is quite helpful to improve Real-time testing performance and functions for FCEV powertrain system. Furthermore, real-time and reliability as the two key factors for the XiL application was deeply analyzed and discussed.
Technical Paper

Transfer Path Analysis and Low-Frequency Vibration Reduction by Locally Resonant Phononic Crystal

2019-04-02
2019-01-0786
The motor has vibration characteristics of order and multi-band in the frequency domain, which is different from the internal combustion engine when it is used as the vehicle’s drive. These characteristics cannot be briefly attenuated by general methods, but make the phononic crystal (PC) an ideal solution to eliminate the vibration transmission of the motor, because the concentrated vibration peak can easily be blocked by the bandgap. In this paper, one dimensional locally resonant phononic crystal (LRPC) which has low-frequency bandgaps are arranged on the automotive subframe to absorbing vibration. The partial coherence analysis is used to analyze the transfer characteristic of vibration on the subframe. Then, 6 main paths are selected from the 18 vibration transmission paths, based on its high ratio of partial coherence coefficient in a certain frequency, and the arranged position, the spring stiffness and the resonator’s mass of the LRPCs are chosen based on this result.
Technical Paper

Robust Multi-Lane Detection and Tracking in Temporal-Spatial Based on Particle Filtering

2019-04-02
2019-01-0885
The camera-based advanced driver assistance systems (ADAS) like lane departure warning system (LDWS) and lane keeping assist (LKA) can make vehicles safer and driving easier. Lane detection is indispensable for these lane-based systems for achieving vehicle local localization and behavior prediction. Since the vision is vulnerable to the variable environment conditions such as bad weather, occlusions and illumination, the robustness is important. In this paper, a robust algorithm for detecting and tracking multiple lanes with arbitrary shape is proposed. We extend the previously lane detection and tracking process from the space domain to the temporal-spatial domain by using a more robust and general multi-lane model. First, new slice images containing temporal information are generated from image sequences. Instead of binarization process, we use a more general detector for extracting the lane marker candidates with prior knowledge to generate the binary slice image.
Technical Paper

Experimental Study on Particulate Emission Characteristics of an Urban Bus Equipped with CCRT After-Treatment System Fuelled with Biodiesel Blend

2017-03-28
2017-01-0933
Biodiesel as a renewable energy is becoming increasingly attractive due to the growing scarcity of conventional fossil fuels. Meanwhile, the development of after-treatment technologies for the diesel engine brings new insight concerning emissions especially the particulate matter pollutants. In order to study the coupling effects of biodiesel blend and CCRT (Catalyzed Continuously Regeneration Trap) on the particulate matter emissions, the particulate matter emissions from an urban bus with and without CCRT burning BD0 and BD10 respectively was tested and analyzed using electrical low pressure impactor (ELPI). The operation conditions included steady state conditions and transient conditions. Results showed that the particulate number-size distribution of BD10 and BD0 both had two peaks in nuclei mode and accumulation mode at the conditions of idle, low speed and medium speed while at high speed condition the particulate number-size distribution only had one peak.
Technical Paper

Parameter Identification of Battery Pack Considering Cell Inconsistency

2017-03-28
2017-01-1214
Lithium-ion batteries have been applied in the new energy vehicles more and more widely. The inconsistency of battery cells imposes a lot of difficulties in parameter and state estimations. This paper proposes a new algorithm which can online identify the parameters of each individual battery cell accurately with limited increase of computational cost. An equivalent circuit battery model is founded and based on the RLS (recursive least squares) algorithm, an optimization algorithm with the construction of weight vectors is proposed which can identify the parameters of lithium battery pack considering inconsistency of single battery cell. Firstly, the average value of the parameters of the battery pack is identified with the traditional RLS algorithm. Then the ratios between the parameters of each battery cell can be deduced from the mathematical model of battery. These ratios are used to determine the weight vector of each parameter of individual battery cells.
Technical Paper

Experimental Investigation of AC Pulse Heating Method for NMC Lithium-Ion Battery at Subzero Temperatures

2017-03-28
2017-01-1217
An alternating current (AC) heating method for a NMC lithium-ion battery with 8Ah capacity is proposed. The effects of excitation frequency, current amplitudes, and voltage limit condition on the temperature evolution are investigated experimentally. Current amplitudes are set to 24A(3C), 40(5C), and 64A(8C), and excitation frequencies are set to 300Hz, 100Hz, 30Hz, 10Hz, 5Hz, and 1Hz respectively. The voltage limitations are necessary to protect cells from overcharge and over-discharge. Therefore the voltage limit condition (4.2V/2.75V, 4.3V/2.65V, and 4.4V/2.55V) are also considered in depth to verify the feasibility of the AC heating method. The temperature rises prominently as the current increases, and the decrement of frequencies also lead to the obvious growth of battery temperature. The battery obtain the maximum temperature rise at 64A and 1Hz, which takes 1800s to heat up the battery from -25°C to 18°C.
Technical Paper

A Study of Parameter Inconsistency Evolution Pattern in Parallel-Connected Battery Modules

2017-03-28
2017-01-1194
Parallel-connected modules have been widely used in battery packs for electric vehicles nowadays. Unlike series-connected modules, the direct state inconsistency caused by parameter inconsistency in parallel modules is current and temperature non-uniformity, thus resulting in the inconsistency in the speed of aging among cells. Consequently, the evolution pattern of parameter inconsistency is different from that of series-connected modules. Since it’s practically impossible to monitor each cell’s current and temperature information in battery packs, considering cost and energy efficiency, it’s necessary to study how the parameter inconsistency evolves in parallel modules considering the initial parameter distribution, topology design and working condition. In this study, we assigned cells of 18650 format into several groups regarding the degree of capacity and resistance inconsistency. Then all groups are cycled under different environmental temperature and current profile.
Technical Paper

Functional Safety and Secure CAN in Motor Control System Design for Electric Vehicles

2017-03-28
2017-01-1255
Permanent magnet synchronous motors (PMSM) are widely used in the electric vehicles for their high power density and high energy efficiency. And the motor control system for electric vehicles is one of the most critical safety related systems in electric vehicles, because potential failures of this system can lead to serious harm to humans’ body, so normally a high automotive safety integrity level (ASIL) will be assigned to this system. In this paper, an ASIL-C motor control system based on a multicore microcontroller is presented. At the same time, due to the increasing number of connectivity on the vehicle, secure onboard communication conformed to the AUTOSAR standard is also implemented in the system to prevent external attacks.
Technical Paper

Analysis of Steering Model for Emergency Lane Change Based on the China Naturalistic Driving Data

2017-03-28
2017-01-1399
A driver steering model for emergency lane change based on the China naturalistic driving data is proposed in this paper. The steering characteristic of three phases is analyzed. Using the steering primitive fitting by Gaussian function, the steering behaviors in collision avoidance and lateral movement phases can be described, and the stabilization steering principle of yaw rate null is found. Based on the steering characteristic, the near and far aim point used in steering phases is analyzed. Using the near and far aim point correction model, a driver steering model for emergency lane change is established. The research results show that the driver emergency steering model proposed in this paper performs well when explaining realistic steering behavior, and this model can be used in developing the ADAS system.
Journal Article

Effects of Installation Environment on Flow around Rear View Mirror

2017-03-28
2017-01-1517
External rear view mirror is attached at the side of the vehicle which is to permit clear vision for the driver to the rear of the vehicle. When the vehicle is running, the flow field around external rear view mirror is highly three-dimensional, unsteady, separated and turbulent which is known to be a significant source of aerodynamic noise and a contributor to the total drag force on the vehicle. While among all the researches on the flow field around external rear view mirror, different installation environment were employed. The external rear view mirror is mounted on a production car in most researches which presents the real condition and it can also be mounted on the ground of a wind tunnel, a specially designed table, or a generic vehicle model based on the SAE model. While, the relationship between the flow field around external rear view mirror and the installation environment is not very clear.
Technical Paper

Investigation of Scavenging Process for Steady-State Operation of a Linear Internal Combustion Engine-Linear Generator Integrated System

2017-03-28
2017-01-1087
The Linear Internal Combustion Engine-Linear Generator Integrated System (LICELGIS) is different from conventional crank-based engine for reducing frictional losses by eliminating the crankshaft. Thus, the LICELGIS piston stroke is not constrained geometrically and the system compression ratio is variable. During steady-state operation, the LICELGIS converts the fuel chemical energy into electric power with piston assembly reciprocating motion, which can be used as a range-extender in hybrid electric vehicles. The LICELGIS scavenging process is prerequisite and key for the system steady-state operation, which has remarkable influence on mixture gas and, eventually, on engine combustion performance. In order to achieve high scavenging performance, a LICELGIS is investigated in this paper. The LICELGIS motion characteristics and scavenging process were analyzed.
Technical Paper

A Method of Acceleration Order Extraction for Active Engine Mount

2017-03-28
2017-01-1059
The active engine mount (AEM) is developed in automotive industry to improve overall NVH performance. The AEM is designed to reduce major-order signals of engine vibration over a broad frequency range, therefore it is of vital importance to extract major-order signals from vibration before the actuator of the AEM works. This work focuses on a method of real-time extraction of the major-order acceleration signals at the passive side of the AEM. Firstly, the transient engine speed is tracked and calculated, from which the FFT method with a constant sampling rate is used to identify the time-related frequencies as the fundamental frequencies. Then the major-order signals in frequency domain are computed according to the certain multiple relation of the fundamental frequencies. After that, the major-order signals can be reconstructed in time domain, which are proved accurate through offline simulation, compared with the given signals.
Technical Paper

Chassis Dynamometer and On-Road Evaluations of Emissions from a Diesel-Electric Hybrid Bus

2017-03-28
2017-01-0984
Recently Hybrid Electric Buses (HEBs) have been widely used in China for energy saving and emission reduction. In order to study the real road emission performance of HEBs, the emission tests of an in-use diesel-electric hybrid bus (DHEB) are evaluated both on chassis dynamometer over China City Bus Cycles (CCBC) and on-road using Portable Emissions Measurement Systems (PEMS). The DHEB is powered by electric motor alone at speed of 0~20km/h. When the speed exceeds 20km/h, engine gets engaged rapidly and then works corporately with the electric motor to drive the bus. For chassis dynamometer test over CCBC, emissions of NOx, particulate number, particulate mass, and THC of the DHEB are 7.68g/km, 5.88E+11#/km, 0.412mg/km, and 0.062g/km, respectively. They have all decreased greatly compared to those of the diesel bus. But the CO emission which is 3.48g/km has increased significantly. Then the Real Driving Emissions (RDE) of the DHEB are compared with the dynamometer test results.
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