Light Electric Vehicle Applications Research Articles

In Search of the Proper Dimensions of the Optimum In-Wheel Permanent Magnet Synchronous Motor Design

In this paper, a new approach to the optimized design of outer rotor Permanent Magnet Synchronous Motors (PMSMs) for in-wheel light electric vehicle (LEV) applications is presented. The optimized design study is based on various dimensions such as back iron depth, permanent magnet depth and air gap length. The novel method is developed to reveal the quality factor of design (QFD), which implies the maximum possible performance results, and determine the best possible design for in-wheel PMSMs for direct-drive LEV applications. Therefore, the thickness of the back iron, permanent magnet and air gap dimensions are altered accordingly to obtain an optimized design. This design study is conducted for an in-wheel PMSM that has rated values of 2.5 kW, 150 V, 900 min−1, and 24-slot/20-pole configuration intended for LEV propulsion. These designs are simulated in order to obtain the maximized combination of efficiency, shaft power, shaft torque and a minimized combination of total weight, iron losses, copper losses, input current and cogging torque. The measure of the optimized parameters is named QFD, which indicates the goodness of the design through the use of radar charts. The values of the essential coefficients of QFD may vary for different applications, e.g., the design of PMSMs used in traction applications has some certain criteria that imply high-performance operation. Additionally, the QFD can guide motor manufacturers as a starting point for a design study.

Influence of Particle Size and Mass Loading of Hard Carbon on Sodium Ion Battery Rate Performance in Industrially Relevant Full Cells

Sodium-ion batteries (SIBs) represent a great opportunity for stationary storage, back-up power supply and light electric vehicle applications. Energy and power requirements for these applications needs to be satisfied. Beside material improvement, electrode microstructure plays a critical role. Herein, the influence of hard carbon (HC) particle size and mass loading on the rate performance have been comprehensively investigated. This work analyses the relative contribution of ionic resistance within the porous electrode (Rion) in SIB full cells employing relevant mass loadings. Rion was obtained by applying electrochemical impedance spectroscopy (EIS) to symmetrical cells and by fitting a transmission line model (TLM) under “blocking” conditions. The relative contribution of Rion arising from HC electrodes was further compared to the charge transfer resistance (RCT) in full cell configuration utilising a three-electrode cell under “non-blocking” conditions. Results illustrate mass loading to be as far more influential on cell rate performance compared to the two particle sizes analyzed. The three-electrode study reveals the contribution of Rion to be greater than that of RCT at high mass loadings and high states of charge for the HC electrode and elucidates that the gravimetric and volumetric discharge capacity of cells is limited by the layered oxide cathode and HC electrode respectively.

An Adaptive Delay Compensated Position Sensorless PMBLDC Motor Drive With Regenerative Braking for LEV Application

This paper deals with a new terminal voltage-based rotor position sensorless algorithm of permanent magnet brushless DC (PMBLDC) motor with adaptive phase angle compensation along with regenerative braking technique for light electric vehicle (LEV) application. Removal of Hall-Effect sensors from PMBLDC motor reduces the circuit complexity and makes the motor drive system robust and compact. Back EMF based position estimation of PMBLDC motor suffers poor accuracy at low speed. In this paper, position sensorless operation is achieved at very low speed below 100rpm. Position estimation of PMBLDC motor suffers with commutation error due to several factors like non-ideal back EMF, lowpass filter used, unbalanced DC bus voltage etc. An adaptive phase angle compensation strategy is developed to mitigate this issue, considering a generalized nonideal commutation case. This method is suitable for compensation of commutation error during variable speeds over a wide speed range, which is required for EV application. Moreover, the compensation method works with motor parameters variation as well. The proposed drive topology extends the vehicle's driving range with solar PV integration and energy regeneration algorithm. The system is simulated and experimentally validated in real case scenarios.

An Improved Time-Sharing Control of Multiport Converter for Solar-Powered EVs Application

In solar photovoltaic systems, multiport converters are proved to be a boon for efficient power flow management with higher reliability and low cost. In this paper, an improved time-sharing control strategy is proposed for a three-port converter that integrates solar photovoltaic (PV) to a light electric vehicle with an energy storage system using a lithium-ion battery. The proposed improved time-sharing closed-loop control strategy comprises incremental conductance maximum power point tracking (MPPT) algorithm, battery management system, and PI-controller-based voltage regulation. The incorporation of the battery management system in the controller ensures the safety and longevity of the battery. The results validate that the output voltage is regulated within the limits, and the battery operates in a safe operating region with efficient MPPT of the PV module. The proposed system is overall efficient, reliable, and safe which makes it suitable for light electric vehicle applications.

Bidirectional Quadratic Converter-Based PMBLDC Motor Drive for LEV Application

In this study, a bidirectional DC-to-DC quadratic converter (BDQC) is designed and developed for the motoring and regenerative braking (RB) of a permanent magnet brushless DC (PMBLDC) motor for a light electric vehicle (LEV) application. A PMBLDC motor is deemed more suitable for an electric vehicle (EV) due to its high efficiency and torque density. In the present work, a BDQC of 1 kW is designed to drive a 1.1 HP PMBLDC motor through a conventional voltage source inverter (VSI). An EV’s load cycle is emulated using a highly inertial load driven by a PMBLDC motor during the converter’s boost mode operation. RB is a crucial factor in extending the driving range of EVs by efficiently utilizing battery power. The converter operates in buck mode during RB, and simultaneously, the back electromotive force (EMF) of the PMBLDC machine is boosted by the self-inductance of the PMBLDC motor and the VSI. The braking technique used in this work eliminates the traditional drawback of RB in buck mode, as the power is extracted even when the motor’s back EMF is lower than the battery’s voltage. The control strategy has been implemented using the TMS320F28335 DSP controller for a developed converter prototype of the converter and driving the PMBLDC motor. The experimental results are compared to the simulation results, and a good alignment has been found.

Analysis and Implementation of a Frequency Control DC–DC Converter for Light Electric Vehicle Applications

In order to realize emission-free solutions and clean transportation alternatives, this paper presents a new DC converter with pulse frequency control for a battery charger in electric vehicles (EVs) or light electric vehicles (LEVs). The circuit configuration includes a resonant tank on the high-voltage side and two variable winding sets on the output side to achieve wide output voltage operation for a universal LEV battery charger. The input terminal of the presented converter is a from DC microgrid with voltage levels of 380, 760, or 1500 V for house, industry plant, or DC transportation vehicle demands, respectively. To reduce voltage stresses on active devices, a cascade circuit structure with less voltage rating on power semiconductors is used on the primary side. Two resonant capacitors were selected on the resonant tank, not only to achieve the two input voltage balance problem but also to realize the resonant operation to control load voltage. By using the variable switching frequency approach to regulate load voltage, active switches are turned on with soft switching operation to improve converter efficiency. In order to achieve wide output voltage capability for universal battery charger demands such as scooters, electric motorbikes, Li-ion e-trikes, golf carts, luxury golf cars, and quad applications, two variable winding sets were selected to have a wide voltage output (50~160 V). Finally, experiments with a 1 kW rated prototype were demonstrated to validate the performance and benefits of presented converter.

Performance Analysis of the Linear Launcher Motor via Modelling and Simulation for Light Electric Vehicles

This research aimed to analyse the linear launcher motor (LM) for the light electric vehicle (EV) application that generated a linear movement. LM will replace the piston engine and eliminate the internal combustion engine (ICE) issues namely engine weight and friction at piston wall. The finite element magnetic softwares (FEMs) for a magnetic field was described in this study by predicting the magnetic flux relationship using a 2D J-Mag software. In addition the finite element (FE) analysis was used to simulate the linear launcher motor by using MATLAB/Simulink software. The results show that the linear launcher motor can generate the axial force, speed, and displacement of with and without load. The maximum force without load was ~1.6kN while force with load was ~1.4kN at 100A supplied. The comparison between the force without load and load force was different by12.5%.

Active fault diagnosis of a switched reluctance motor using sliding mode observer and average torque estimator for light electric vehicle applications

Active fault diagnosis of a switched reluctance motor using sliding mode observer and average torque estimator for light electric vehicle applications

Eliminating starting hesitation for reliable operation of switched reluctance motor without machine parameters for light electric vehicle applications

In this study, an initial rotor position estimation at standstill condition is presented for reliable operation of switched reluctance motor (SRM) without initialising machine parameters for light electric vehicle (LEV) applications. The prime objective of this method is to startup an SRM without using the mechanical position sensor, and eliminate the starting hesitation and starting jerk issues from standstill condition. In the proposed method, the initial rotor position at standstill is determined by injecting a single pulse dc voltage simultaneously into all stator phase windings for a very short period (microsecond). The obtained current envelope data is then used to calculate the initial rotor position with the quadratic polynomial interpolation technique without any prior knowledge of other motor parameters. The experimental results for a 3.5 kW, 6/4 SRM are provided to substantiate the overall good performance. The developed system can be considered as a strong candidate for high precision LEV applications.

Average Torque Control of a Switched Reluctance Motor Drive for Light Electric Vehicle Applications

In this paper, an online average torque control (ATC) of a switched reluctance motor (SRM) for light electric vehicle (LEV) applications is proposed. The purpose of the ATC is to control the average torque in the most inner control loop to stabilize the system dynamics. This is carried out by estimating the average torque at every time instant by considering the motor primary parameters, i.e., rotor position, speed, and phase currents. To achieve the desired average torque in wide speed range and controller efficiency for traction control, the proposed ATC algorithm is designed to adjust the changing reference current and switching angles to obtain the desired average torque at the operating speed. This paper also proposes a torque estimation method based on the Fourier Series approximation of the inductance profile to obtain accurate torque estimation results. The simulation of a 3 kW, 6/4 SRM for LEV application is used to demonstrate the effectiveness of the proposed method.

Advanced battery management system design for SOC/SOH estimation for e-bikes applications

In this work, state of charge (SOC) and state of health (SOH) estimation algorithms for battery management system are proposed and compared. These algorithms are developed on a battery pack designed specifically for light electric vehicle (electric scooter or bicycles) applications. The advanced battery management system is designed in order to evaluate the instantaneous charge available in the battery and at the same time to monitor the slowly varying battery aging parameters. Two SOC estimation algorithms are proposed: an extended Kalman filter (EKF) and an adaptive extended Kalman filter (AEKF). With the adaptive version of Kalman filter a proper value of the model noise covariance is adaptively set using the information coming from the online innovation analysis. In the second part of this paper, a new estimation algorithm based on least squares is proposed to estimate the battery SOH. A general framework for a combined evaluation of SOC/SOH is discussed.

Rigorous Design of a Switched Reluctance Motor Using a Hybrid Design Model

Torque ripple is a very essential index for evaluating the effectiveness of a switched reluctance motor (SRM). Many common design strategies for reducing torque ripples of a SRM are changing the excitation trigger angle of stator windings, delaying the cut-off time of winding excitation, adjusting the ratio of arc angle between stator and rotor, and changing the geometric shape of rotor. However, the output torque or the efficiency of the SRM may drop as the above design strategies are solely adopted. In this paper, a hybrid design model which is obtained by the Taguchi Method for optimally designing a SRM with lower torque ripple and higher efficiency is presented. A 12S/8P motor is taken as a study case, and the 3D finite element method (FEM) is applied to analyze the characteristics of the motor and optimize the design process. The results have shown that the proposed method can achieve the design goal of obtaining a high-performance SRM for light electric vehicle applications. Keyword: Switched reluctance motor, Torque ripple, Taguchi method, Finite element method

Design Considerations for an In-Wheel PM Motor with Fractional Slot Concentrated Windings for Light Electric Vehicle Applications

Design optimization of traction motors for light electric vehicles requires a comparative analysis in order to account for both performance and efficiency, while considering overall cost, size limitations and manufacturing complexity. This paper presents a comparative study on different surface mounted permanent magnet (SMPM) in-wheel motor configurations, facilitating fractional slot concentrated windings (FSCW). On a first step, different pole/ slot combinations were investigated and evaluated in terms of performance primarily. On a second step, different stator geometries were analyzed, considering both double and single layer windings and both equal and unequal stator teeth. Two different operating conditions were taken into account, i.e. nominal load and overload. The most advantageous was selected, by means of efficiency, clean interface and overall weight, using an extensive sensitivity analysis. On a third step, the final geometry was optimized, via fine-tuning of key design variables, accounting for maximum efficiency and minimum machine weight.

Design and analysis of a sub-fractional slot concentrated winding BLDCM with unequal tooth widths

The paper presents a study on the design and analysis of a sub-fractional slot concentrated winding brushless direct current motor (BLDCM) with unequal tooth widths for a light electric vehicle application. This kind of brushless surface permanent magnet (SPM) motor is equipped with easy-to-manufacture features which are crucial for the electrical machinery market, especially for electric motors used in electric vehicles. The structure also responds quite effectively to field weakening operation, because of its inherent higher inductance value. The study is focused on increasing the winding inductance value by using the designs analysed in magnetic analysis software. A selected BLDC motor structure is manufactured and tested to verify the design.

High Efficiency Permanent Magnet Wheel Motor Design for Light Electric Vehicle Applications

Permanent magnet synchronous machines with non-overlapping concentrated fractional-slot windings present certain improved electrical characteristics compared to full pitch windings configurations. This paper describes the design process and construction of two 10-pole permanent magnet synchronous motors, featuring full-pitch and fractional-pitch windings. The paper compares these two configurations in terms of performance and efficiency. Both motors have been designed for direct-drive applications with low speed and high efficiency capability and are intended to be used as a traction drive in an electric prototype vehicle. The proposed motors have external rotor configuration with surface mounted NdFeB magnets. The electromagnetic characteristics and performance are computed and analyzed by means of finite elements analysis. These results are finally compared with the experimental measurements on respective prototypes.