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Alleviating the Magnetic Effects on Magnetometers using Vehicle Kinematics for Yaw Estimation for Autonomous Ground Vehicles

Michigan Technological University-Ahammad Basha Dudekula, Jeffrey D. Naber
  • Technical Paper
  • 2020-01-1025
To be published on 2020-04-14 by SAE International in United States
Autonomous vehicle operation is dependent upon accurate position estimation and thus a major concern of implementing the autonomous navigation is obtaining robust and accurate data from sensors. This is especially true, in case of Inertial Measurement Unit (IMU) sensor data. The IMU consists of a 3-axis gyro, 3-axis accelerometer, and 3-axis magnetometer. The IMU provides vehicle orientation in 3D space in terms of yaw, roll and pitch. Out of which, yaw is a major parameter to control the ground vehicle’s lateral position during navigation. The accelerometer is responsible for attitude (roll-pitch) estimates and magnetometer is responsible for yaw estimates. However, the magnetometer is prone to environmental magnetic disturbances which induce errors in the measurement. The present work focuses on alleviating magnetic disturbances for ground vehicles by fusing the vehicle kinematics information with IMU senor in an Extended Kalman filter (EKF) with the vehicle orientation represented using Quaternions. In addition, the error in rate measurements from gyro sensor gets accumulated as the time progress which results in drift in rate measurements and thus affecting the vehicle…
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Research on Topology Analysis Method of Static Magnetic Network Model of New High Speed Electromagnetic Actuator

Changsha University of Science and Technology-Peng Liu
Harbin Engineering University-Yunpeng Wei, Liyun Fan, Yun Bai, Yang Liu
  • Technical Paper
  • 2020-01-0202
To be published on 2020-04-14 by SAE International in United States
In this paper, based on the design of composite magnetic circuit, a new type of high-speed electromagnetic actuator (NHSEMA) with permanent magnetic was invented, which has the characteristics of low power consumption, strong electromagnetic force and high response. Those characteristics were systematically and deeply studied by means of theoretical analysis, numerical simulation and experiment. The magnetic network topology method was proposed to subdivide the structure of the NHSEMA, and construct the static characteristics simulation model of NHSEMA, with taking into account the magnetic flux leakage and edge flux of the system. The accuracy of simulation model of the NHSEMA was verified by set up the test platform. The error is about 3.1%, which proves that the model can achieve both calculation accuracy and speed. The static electromagnetic characteristics, energy conversion and magnetic flux distribution of NHSEMA were studied by using magnetic network topology simulation model. The research shows that compared with the traditional high-speed electromagnetic actuator (THSEMA), the electromagnetic force of NHSEMA is increased by about 30% under the same current driving. Meanwhile, the Joule…
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Minimization of Electric Heating of the Traction Induction Machine Rotor

South Ural State University-Elena Nikiforova, Victor Smolin
University of Michigan-Sergey Gladyshev
  • Technical Paper
  • 2020-01-0562
To be published on 2020-04-14 by SAE International in United States
The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance. The quasi-independent excitation of the induction machine is performed according to the model by stabilizing the current of the magnetizing branch using the algorithms to control the voltage amplitude, synchronous frequency and electromagnetic…
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Searching for Optimal Solutions for Motor Performance Design

Honda R&D Co.,Ltd.-Yuko Miyabe, Masahito Kakema, Toshihiro Saito
  • Technical Paper
  • 2020-01-0460
To be published on 2020-04-14 by SAE International in United States
This paper relates a method for seeking Pareto solutions for strength, torque-rotational speed characteristics, losses, and exciting force in the preliminary design of interior permanent magnet synchronous motors (IPMSM) and carrying out optimal design in an integrated manner. As to the constraint on strength, it was determined that the von Mises stress on the rotor core with respect to the load of the centrifugal force at 1.2 times the maximum rotational speed should not exceed the breaking strength of common electrical steel sheet material. As to the torque-rotational speed characteristic, this was determined to be the maximum torque for each rotational speed, taking into account the maximum voltage and current input when maximum torque per ampere control and field weakening control are applied. The maximum torque at low rotational speed and the maximum power at maximum rotational speed were taken as evaluation parameters. Losses were defined as the total value of DC copper loss occurring in the coil and iron loss occurring in the stator and rotor core. As to the exciting force, the 6th…
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Effect of stator surface area on braking torque and wall heat dissipation of magnetorheological fluid retarder

Suizhou-WUT Industry Research Institute-Gangfeng Tan
Wuhan University of Technology-ZhiQiang Liu, Zhongpeng Tian, Mi Zhou, Philip Agyeman, Justice Frimpong
  • Technical Paper
  • 2020-01-0937
To be published on 2020-04-14 by SAE International in United States
Magnetorheological fluid (MRF) is used as the transmission medium of the hydraulic retarder. The rheological properties are regulated by changing the magnetic field to realize the accurate control of the slow braking torque magnetic field. In magnetorheological fluid retarder and under the action of magnetic field, the flow structure and performance will be changed in a short time. The apparent viscosity coefficient increases by several orders of magnitude, the fluidity deteriorates and the heat generated by the brake cannot be well transferred through the liquid circulation. And it has influence on brake torque and wall heat dissipation of retarder to change stator surface area. In this study, the relationship between the braking torque of the MRF retarder and the stator surface area of the retarder was analyzed. In addition, phase change materials were used to directly dissipate heat on the retarder surface to reduce the retarder's operating temperature and improve the stability of the retarder's braking torque. In order to study the effect of stator diameter on braking torque of MR retarder under external magnetic…
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Current control method for asymmetric dual three-phase Permanent Magnet Synchronous Motor

Tongji University-Zhihong Wu, Weisong Gu, Yuan Zhu, Ke Lu
  • Technical Paper
  • 2020-01-0470
To be published on 2020-04-14 by SAE International in United States
Based on the vector space decomposition (VSD) transformation, the phase currents of the asymmetric dual three phase permanent magnet synchronous motor (ADT-PMSM) can be mapped into three orthogonal subspaces, i.e., α–β subspace, x-y subspace and O1-O2 subspace. The mechanical energy conversion takes place in the α–β subspace, while in the x-y and O1-O2 subspaces only losses are produced. With neutral points being isolated, O1-O2 subspace can be omitted. So the vector control algorithm can control the α–β and x-y subspaces separately to realize the four dimensional current control. In the α–β subspace, deviation decoupling control method is employed to realize the mechanical energy conversion, which is robust to the motor parameters. In order to reduce the 5th and 7th harmonic currents caused by the inverter nonlinearity and some other factors, a resonant controller is adopted based on a new synchronous rotating coordinate transformation matrix to implement the current closed loop control strategy in the x-y subspace. The resonant controller can track sinusoidal references of arbitrary frequencies of both positive and negative sequences with zero steady-state…
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Lumped Parameter Thermal Network Modeling for Online Temperature Prediction of Permanent Magnet Synchronous Motor for Different Drive Cycles in Electric Vehicle Applications

University of Windsor-Muhammad Towhidi, Firoz Ahmed, Shruthi Mukundan, Ze Li, Narayan C. Kar
  • Technical Paper
  • 2020-01-0455
To be published on 2020-04-14 by SAE International in United States
Electric vehicle is increasingly becoming popular and an alternate choice in automotive industries because of its environment-friendly operation. Permanent magnet synchronous machines are widely and commonly used as traction motors since they provide higher torque and power density. High torque and power density means higher current which eventually causes higher temperature rise in the motor. Higher temperature rise directly affects the motor output. Standard tests for UDDS (Urban Dynamometer Driving Schedule) and HWEFT (Highway Fuel Economy Driving Schedule) drive cycles are used to determine performance of traction motors in terms of torque, power, efficiency and thermal health. Traction motors require high torque at low speed for starting and climbing; high power at high speed for cruising; wide speed range; a fast torque response; high efficiency over wide torque and speed ranges and high reliability. For both UDDS and HWEFT driving conditions, it is essential to monitor the performance of the motor and predict the temperature of stator winding and magnet in order to maintain required torque and power generation. This paper proposes a simplified Lumped…
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Modeling and analysis of temperature field of permanent magnet synchronous motor considering high frequency magnetic field characteristics

Tongji University-Jie Xu, Lijun Zhang, Dejian Meng
  • Technical Paper
  • 2020-01-0457
To be published on 2020-04-14 by SAE International in United States
The vehicle permanent magnet synchronous motor has the advantages of high power density, compact structure and small size, which makes it generate heat obviously in the process of energy conversion, which seriously affects the service life of the motor and the performance of permanent magnet. Predicting magnet temperature is a challenging task, in lab and various specialized applications, infrared sensors or thermocouples are used to measure the temperature, but it cost a lot. In order to predict the temperature field of the motor, the hysteresis characteristic test of the core material of the motor is carried out in this paper. The hysteresis characteristic and loss of electrical steel under different temperature, magnetic field intensity and magnetic field frequency are tested. It is found that the loss of electrical steel increases with the increase of magnetic induction intensity and magnetic field frequency. Then based on the Preisach theory, the hysteresis model of the core material is established, and analyses the advantages and disadvantages of the limiting magnetic hysteresis loop density function separation method and the symmetric…
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Research on Thermal Management of Magnetorheological Fluid Retarder Based on Phase Change Principle

Wuhan University of Technology-Jiakang Quan, Bo Huang
  • Technical Paper
  • 2020-01-0948
To be published on 2020-04-14 by SAE International in United States
In order to avoid the braking recession on heavy commercial vehicles caused by the long-distance continuous braking of the main brake, the hydraulic retarder is widely used as an important brake auxiliary device in various heavy commercial vehicles to improve the vehicle safety. However, the hydraulic retarder not only has the advantages of large braking torque and good stability, but also has the disadvantages of poor retarding ability at low rotating speed, braking lag and difficulty in accurately controlling the braking torque. This paper introduces a new type of hydraulic retarder. The new retarder replaces the oil in the retarder with magnetorheological fluid and applies a magnetic field in the retarder arrangement space, so that slows down the vehicle by using the rheological properties of the magnetorheological fluid under the magnetic field. The magnetorheological fluid hydraulic retarder generates a large amount of heat during working which not only decreases the braking performance, but also causes the structure to be damaged, and even risks the safety of the driver and the vehicle. This paper studies on…
new

Tiny Magnetics Show Promise for Medical Applications

  • Magazine Article
  • TBMG-36246
Published 2020-03-01 by Tech Briefs Media Group in United States

Small magnetic objects are showing promise in the biomedical field. Magnetic nanostructures have interesting properties that enhance novel applications in medical diagnosis and allow the exploration of new therapeutic techniques.