International Journal of Powertrains (11 papers in press)

Regular Issues

• Improving Latency Time of an Energy Harvesting Chain by Implementing a Fully-Integrated-LDO for Aircraft WSN.  
  by Hatim Ameziane 
  Abstract: This paper presents an energy harvesting system to reduce the mass of the cables within an aircraft, focusing on the development of a power conversion chain to harvest energy from Data lines, which is eventually used to supply the aircraft sensors or wireless monitoring. This proposed interface harvests energy from data CAN bus without disturbing the data transmission, providing an output current up to 60 mA and an output voltage of 1.65V at the output of the Fully integrated LDO and an output voltage of 5.035 V at the output of the charge pump within a very short settling time of less than 5ms and a low voltage ripple of 158.2 mV, in order to feed the aircraft sensors. The most common energy harvester sources are solar cells, wind turbines, vibration energy, and thermoelectric generators. The Energy-Harvesting Chain (EHC), which does not depend on the environment, is composed by fast analog devices that are based on integrating a fully integrated LDO with a fast transient response, in order to make the aircraft sensors self-powered and operate in real time. The harvesting system is designed in 0.18 μm CMOS technology; the simulation results prove the advantage of the proposed architecture.
  Keywords: Low Dropout Regulator (LDO); Energy Harvesting; Integrated Circuits (ICs); embedded system; wireless sensors network (WSN); Aircraft.
  
  
• Parametric analysis of asymmetric involute spur gear tooth  
  by Priyakant Vaghela, Priyakant Vaghela, Jagdish Prajapati, Jagdish Prajapati 
  Abstract: The focus of this work is a geometric parameter of an asymmetric involute spur gear tooth. Gear strength is influenced by tooth geometry. So, knowledge of tooth geometric is required which will help to improve the strength of a gear tooth. In this article, a data generated from an equations and presented in form of graph for better interpretation of the effect of drive side pressure angle on various parameters like contact ratio, HPSTC radius, load angle, tip thickness, thickness of tooth at pitch circle radius, critical section thickness, bending moment arm height etc,. Parametric analysis of gear tooth gives an idea about how different parameters affect tooth geometry of an asymmetric involute spur gear tooth which is essential for modelling and manufacturing. Parametric analysis help to calculate optimize drive side pressure angle. It is also predicted or calculates % reduction in bending stress at the root of the tooth without using ANSYS. It is explained with illustration and results are compared to justify it.
  Keywords: Pressure angle; Fillet radius; Bending stress; Asymmetric spur gear tooth; parametric analysis,Gear tooth geometry.
  
  
• On the future of gears in electrified drive trains  
  by Joshua Goetz, Karsten Stahl 
  Abstract: The development of transmission types for passenger cars clearly shows a significant increase in vehicles with an electrified powertrain. Due to the electrification of the powertrain the total number of necessary gears is drastically reduced in battery electrical vehicles (BEV). Transmissions become lighter, more compact and their complexity is decreased. These changes leave the question open whether transmissions are still needed in the future. However, the requirements in terms of power density, efficiency and NVH are becoming more demanding. To meet these requirements, a large number of research projects are in progress which face the challenges in electrified transmissions. The following paper gives a broad overview over those research projects and shows the essential necessity of transmissions in electrified powertrains in the future.
  Keywords: electrified powertrain; battery electric vehicle; BEV; passenger car transmission; efficiency; power density; noise vibration and harshness; NVH; gear production; future potentials of gears; plastic gears.
  
  

Special Issue on: Advanced Powertrain Technologies for New Energy Vehicles Modelling, Control and Optimisation

• Flash Boiling Hollow Cone Fuel Spray from a Piezoelectric Fuel Injector under Low Ambient Pressure  
  by Zengyang Wu, Libing Wang, Tiegang Fang 
  Abstract: In this study, an experimental study of the spray characteristics under flash boiling conditions from an outwardly opening piezoelectric gasoline direct injection fuel injector was conducted in an optically accessible constant volume chamber (CVC). Distinct spray structure is noticed when the ambient pressure is extended to a lower range (0.01 bar to 0.1 bar) under flash boiling spray regime. While the original hollow-cone structure is still observable, spray deforms from a hollow-cone structure to a diamond-like shape with a long central plume at the downstream of the spray. Liquid signals at the plume region are much weaker than the original hollow-cone shape region. Within this pressure range, a higher ambient pressure leads to a shorter central plume. Spray penetration length is greatly enlarged due to the change in spray structure. Spray under a lower ambient pressure penetrates much longer at the same time step. Fuel injection pressure and fuel injection duration has little effect on spray front penetration length development. Specially, the highest spray front penetration velocity observed at 0.01 bar is expected to approach to the local sound speed. Spray structure, spray penetration length and spray penetration velocity are mainly dominated by ambient pressure conditions in this study. Compared to isooctane fuel, commercial gasoline generates stronger flash boiling due to the wide boiling range, but the spray structures are quite similar.
  Keywords: Flash boiling; Hollow cone spray; Low ambient pressure; Gasoline direct injection; Isooctane.
  
  
• A comparative study of integral order and fractional order models for estimating state-of-charge of lithium-ion battery  
  by Yifan Zhang, Tao Sun, Yuejiu Zheng, Xin Lai 
  Abstract: Battery state estimation is a key technology for battery management systems for electric vehicles, and state-of-charge(SOC) estimation of battery is the basis for numerous state estimations. In this paper, five fractional order equivalent circuit models are compared and evaluated based on a LiNMC cell. First of all, the particle swarm optimization(PSO) is used to identify the parameters of the fractional order models, and the fractional Kalman filter algorithm is further adopted to estimate the SOC and compared with the SOC estimation obtained by the integral order models. The results indicate that the fractional battery model has higher accuracy, especially in the low SOC interval. Through comparative analysis of several fractional order models, it is found that the fractional order model with the Wurburg component can be better describe the battery characteristics in the low SOC interval. From the perspective of model accuracy and computational cost, the addition of the Wurburg element to the fractional second-order RC model is the best choice.
  Keywords: lithium-ion battery; fractional order model; Kalman filter algorithm; state of charge.
  
  
• Model-Based Electric Traction Drive Resolver Fault Diagnosis for Electrified Vehicles  
  by Tianpei Li, Giorgio Rizzoni, Qadeer Ahmed, Jason Meyer, Mathew Boesch, Bader Badreddine 
  Abstract: In electric and hybrid electric vehicles (EVs/HEVs) the electric traction drive plays an important role in producing driving torque. The motor torque request is calculated based on pedal positions from the driver and motor speed measurement from the position and speed sensor, typically the resolver. When there is a fault in the resolver that leads to inaccurate motor speed measurement, the vehicle supervisory controller may request undesired motor torque, which may lead to motor torque oscillations that could result in safety or degradation problems. This paper presents a model-based approach for diagnosing the resolver fault in the electrified vehicles, with focus on two typical types of faults, amplitude imbalance and quadrature imperfection. Before the diagnostic strategy is designed, resolver failure modes and fault propagation are analyzed using a high-fidelity hybrid electric vehicle powertrain simulator. The proposed diagnostic strategy is implemented and validated through model-in-the-loop simulation, augmented by experimental data.
  Keywords: fault diagnosis; hybrid electric vehicle; electric traction drive; permanent magnet synchronous machine (PMSM); structural analysis.
  
  
• Optimal Design of Discrete-Time Fractional-Order PID Controller for Idle Speed Control of an IC Engine  
  by Yi Yang, Haiyan H. Zhang, Wangling Yu, Li-Zhe Tan 
  Abstract: Fractional-Order PID (FOPID) controller, as a nonlocal generalization of the conventional PID controller, exhibits a better control performance for the complex system dynamics. This paper aims at proposing a discrete-time FOPID controller, which can be implemented in the digital computer to stabilize the variation of the idle speed of an internal combustion engine due to the occurrence of the external load disturbance. The idle speed of an internal combustion engine is the revolution speed of the crankshaft when the drivetrain is uncoupled to the engine and the throttle is completely closed. The nonlinear idle speed dynamics is linearized, and the linearized idle speed dynamics is approximated by a first order plus dead time (FOPDT) model so that a Ziegler-Nichols type tuning rule can be applied to the FOPDT plant to initialize the five parameters (K_p,K_i,K_d,?,?) of the FOPID controller. The parameters-initialized FOPID controller can stabilize the idle speed of the linearized model, but it may lose its control capability when it is applied to the nonlinear idle speed dynamics. Therefore, an optimization problem is constructed to minimize an integral squared error function within a small region around the initial value of the FOPID parameters. The problem is solved through genetic algorithm (GA). The optimal FOPID is discretized and applied to the nonlinear idle speed plant. The simulation results of the optimal discrete-time FOPID controller are compared to those obtained from a conventional discrete-time PID controller. The comparison study reveals that the optimal discrete-time FOPID controller secures an excellent control performance to the nonlinear idle speed model. This controller design methodology can be transformed and applied in other complicated systems.
  Keywords: Fractional-Order PID; discrete-time FOPID; idle speed control; Internal combustion engine; FOPDT; Ziegler-Nichols type tuning rule; genetic algorithm.
  
  
• Modeling and Estimation of Combustion Variability for Fast Light-off of Diesel Aftertreatment  
  by Bryan Maldonado, Mitchell Bieniek, John Hoard, Anna Stefanopoulou, Brien Fulton, Michiel Van Nieuwstadt 
  Abstract: Combustion phasing retard is commonly used on diesel engines to achieve faster aftertreatment light-off and lower tailpipe cycle emissions by increasing the enthalpy of the exhaust gas. More aggressive combustion phasing retard can achieve higher exhaust gas enthalpy at the cost of increased combustion variability, which can create vehicle noise, vibration, and harshness (NVH) issues. To avoid NVH while maximizing exhaust heating, it has been proposed that feedback from cylinder pressure sensors be used to control the coefficient of variation of the indicated mean effective pressure (CoV_IMEP) to a maximum allowable value by retarding combustion phasing. Therefore, a control-oriented combustion model that captures the stochastic properties of the cycle-to-cycle variability for IMEP has been developed for control design. Initial explorations have focused on using finite impulse response (FIR) filters to estimate CoV_IMEP and generate the feedback signal, which requires constant repopulation of a vector for filter states and recalculation of the windowed statistics. An infinite impulse response (IIR) filtering strategy using exponentially weighted moving averages is presented which reduces the computational and storage burden of generating online statistics. Note, however, that the methods for fast aftertreatment light-off are transient in nature due to the increase in engine coolant temperature, while the CoV_IMEP is a characteristic of a stationary stochastic signal. Therefore, this paper presents, in addition to the control-oriented combustion modeling, an unbiased estimation method for CoV_IMEP that accounts for engine transient conditions. Finally, the performance of the proposed IIR strategy is tested during an engine warmup phase to show that it is a suitable alternative for generating a feedback signal for control.
  Keywords: estimation; filtering; stochastic systems; cycle-to-cycle combustion variability model; aftertreatment light-off; coefficient of variation.
  
  

Special Issue on: PMC2018 Powertrain Modelling and Control

• Design of a test rig in support of E-clutch dynamics characterization, modelling, and control  
  by Matija Hoić, Mario Hrgetić, Joško Deur, Andreas Tissot 
  Abstract: E-clutch systems have emerged recently as solutions that allow the powertrain control system to operate the clutch, while the driving procedures remain the same as with the regular manual transmissions (MT). These systems offer possibilities of improved fuel economy and driving comfort over MT systems, while the driver maintains the existing driving habits. This paper presents design of a test rig developed for a dry E-clutch equipped with a hydrostatic actuator mechanism driven by a spindle-based electric servomotor. The main purpose of the test rig is to provide a basis for experimental characterization of both static and dynamic behaviours of the E-clutch, as well as to facilitate E-clutch model validation and control strategy verification. The use of the test rig is illustrated through presenting recordings of basic E-clutch static curves and time responses. These recordings are employed to validate axial dynamics and thermal dynamics models of an E-clutch, which are presented in the paper, as well.
  Keywords: control; design; E-clutch; modelling; test rig.
  
  

Special Issue on: ISAECT 2018 Advanced Research on Powertrains

• ANFIS-based hysteresis comparators with intelligent dual observer and speed controller of a direct torque control  
  by Chaymae Fahassa, Mohamed AKHERRAZ, Yassine ZAHRAOUI 
  Abstract: This article presents the adaptive-network-based fuzzy inference system (ANFIS) based direct torque control (DTC) for induction motor (IM). Direct torque control is distinguished by merging a simple structure with a good dynamic behavior, when compared with the other vector control techniques. Despite the cited advantages the DTC offers, some disadvantages are also present. For this aim, which consists of reducing the ripples in electromagnetic torque, flux and current; and to improve the IM response characteristics, the conventional hysteresis comparators of the torque, flux and the PI speed controller are replaced by others based on ANFIS technique. Furthermore, an intelligent dual observer is implemented to achieve sensorless control; merging a Luenberger observer (LO) based on ANFIS to insure the adaptation mechanism in order to estimate the rotor speed, and a Kalman filter (KF) to insure the flux components estimation. The proposed sensorless ANFIS-DTC shows a robust performance which is presented in reduced ripples, decreased overshoots, short time of rising and settling, in addition to high resistance to perturbations. The simulation results are validated using Matlab/Simulink.
  Keywords: anfis; hysteresis comparators; dual observer; Luenberger observer; Kalman filter; sensorless DTC; induction motor.
  
  

Special Issue on: Software Development in Automotive Electronic Systems

• Realizing ZVS and ZCS in a Continuous Conduction Boost Converter with Boundary Mode Control  
  by Nagesh Vangala, Srinivasa Rao Gorantla, Rayudu Mannam 
  Abstract: Boost regulators working in the continuous conduction mode (CCM) are very popular in switch-mode power conversion. This configuration is widely adapted for Power Factor Correction (PFC) in Switch mode AC to DC converters. For lower power levels of up to 200 watts, boundary conduction mode (BCM) PFC is adapted, and for power requirements beyond about 200W, CCM boost with average current control scheme is favored. A novel technique is proposed in this paper to achieve complete soft-switching viz. Zero Voltage Switching and Zero Current Switching for the main boost switch in CCM mode. The uniqueness of the scheme lies in not adding any auxiliary MOSFET switch and /or control algorithm. All the switching elements exhibit soft-switching, thus improving efficiency and reducing the EMI considerably. Most of the reported techniques for soft switching in CCM boost utilize additional active switches. A working model is fabricated to demonstrate and validate the scheme. The test results and the waveforms are presented and analyzed. An 800 watts PFC converter exhibiting complete soft switching is built using the proposed technique and is evaluated for its performance.
  Keywords: Boost Converter; Continuous Conduction mode; ZVS; ZCS; Soft Switching; PFC pre-regulator; Variable Frequency; Resonant Converter.CCM; BCM Control.