Permanent Magnet Traction Research Articles

Dual-zone control of the traction permanent magnet synchronous motor in the unmanned aerial vehicle

Dual-zone control of the traction permanent magnet synchronous motor in the unmanned aerial vehicle

High-Order Sliding Mode Magnetometer for Excitation Fault Detection of Elevator Traction Synchronous Motor under the Background of Industrial Engineering

In order to solve the excitation problem of elevator traction permanent magnet synchronous motors (PMSMs), a new high-order sliding mode flux observer based on a hybrid reaching rate is proposed under the background of industrial engineering to detect loss of excitation faults in real time. Firstly, a new high-order sliding mode flux observer is designed to solve the problem of the traditional sliding mode observer not being able to accurately detect the loss of excitation fault when the load resistance changes. Then, based on the sliding mode variable structure equivalent control principle, a PMSM flux estimation formula is established. The sinusoidal input function replaces the traditional symbolic process, and a mixed approach law is designed to replace the constant speed approach rate. The adaptive adjustment of the boundary layer of the sinusoidal input function is realized through a fuzzy control system, which effectively suppresses the chattering problem caused by the sliding mode variable structure and improves the observation accuracy of rotor position. The stability of the system is verified by Lyapunov’s second method. MATLAB/Simulink is used to build the simulation model of the PMSM control system with the new sliding mode observer, and the simulation results are compared with those of a traditional sliding mode observer. The results show that compared with the conventional observer, the new sliding mode observer can track the rotor position quickly, and the system has better anti-interference abilities and stability. Finally, the feasibility and effectiveness of this method are verified via simulations and experiments.

High-Gain Nonlinear Active Disturbance Rejection Control Strategy for Traction Permanent Magnet Motor Drives

In order to improve the performance of the traction permanent magnet motor drives without weight transducer for direct-drive elevator applications during starting operation, this article proposes a novel control method based on the high-gain nonlinear active disturbance rejection control (HNLADRC) strategy. First, the limitation of linear and nonlinear error decay function of active disturbance rejection control (ADRC) method is analyzed, which is not suitable for the complex situation at starting operation of the traction motor. A high-gain nonlinear error decay function based ADRC method is proposed, which can achieve better performance in the starting operation of the traction motor. Both the high-gain extended state observer (HNLESO) and the high-gain nonlinear error feedback law (HNLEFL) are constructed by the high-gain error decay function to improve the compensation accuracy of the starting torque and the dynamics of the speed loop. By analyzing the error decay performance of the HNLESO and the HNLEFL, it is proved that the HNLADRC method has a faster error decay rate. Experimental results show that the proposed method can obtain a shorter rollback distance and faster response capability.

Model Predictive Current Control of Traction Permanent Magnet Synchronous Motors in Six-Step Operation for Railway Application

This paper proposes a finite set model predictive current control scheme for traction permanent magnet synchronous motors for railway application. For the rail transit drive system, it is necessary to realize the six-step operation. A method based on voltage vector clamping is presented to realize overmodulation including six-step operation and maximize the utilization ratio of dc voltage. The essence of voltage vector clamping is to gradually reduce the space of action of the closed-loop regulation mechanism until it enters six-step operation. This method is simple and feasible, which does not need to add controllers or switch the control framework. An ideal voltage vector reference coordinate system is established to analyze the current trajectory under different modulation ratios. Thus, an optimal control strategy in the ideal voltage reference coordinate system is proposed. Experiments are conducted to prove that six-step operation can be achieved and this strategy has an obvious effect on switching frequency index in the overmodulation area.

An Algorithm for Effective Design and Performance Investigation of Active Cooling System for Required Temperature and Torque of PM Traction Motor

The conventional mechanical design approach of cooling jackets serves the goal of heat dissipation to keep motor temperature below the maximum allowable limit for thermal protection. However, the desired motor performance cannot be effectively achieved by this approach since it only employs heat transfer mechanism. Therefore, a detailed algorithm is developed to provide a constructive cooling design process to achieve the desired performance of a permanent magnet (PM) traction motor. In the preprocessing stage, a two-way electromagnetic (EM) and thermal co-analysis method is developed for preinvestigation of motor temperature and torque to set the goal for the cooling requirement. In the solver, a shape and size optimization method is utilized to get the optimal cooling design for fulfilling the requirement. Further, a multiphysics finite-element analysis model is developed for structural optimization to ensure safe minimal weight of cooling design for the improvement in torque and power density. In the validation step, unlike using only computational fluid dynamics (CFD) to predict motor temperature, a two-way coupling of EM and CFD model is utilized to ensure the design goals of both torque and temperature for several operating conditions. Finally, the design optimization of a cooling jacket for an interior PM synchronous motor is conducted by implementing this algorithm.

Direct Liquid Cooling Method Verified With a Permanent-Magnet Traction Motor in a Bus

Direct liquid cooling (DLC) of electrical machine windings is a clearly effectual cooling method for high-torque and high-power-density applications needed, especially, in heavy vehicles. Usually, in electric vehicles, the stator copper winding losses are the most dominating losses during the accelerating or decelerating (recuperation) modes, and therefore, traditional windings may heat up significantly during high-torque periods. Removing the heat directly from the winding in which most of the heat is generated allows the most straightforward and effective way of cooling. This paper investigates the feasibility of the DLC in a radial-flux permanent-magnet traction motor. This case provides experimental information of the behavior of the DLC of the windings. The prototype motor equipped with DLC windings is installed in an electric bus so that typical bus load cycles can be tested.

Dynamic Reluctance Mesh Modeling and Losses Evaluation of Permanent Magnet Traction Motor

In this paper, dynamic reluctance mesh model (DRM) combined with an improved iron losses prediction model are presented to provide fast and accurate way to evaluate the iron losses for permanent magnet (PM) motors with pulsewidth-modulated power supply. A DRM model for high-speed train PM traction motor is first built. The magnetic field distribution for one cycle is then obtained using the DRM method. An improved engineering model of iron losses prediction is applied. Finally, the simulation and testing results are presented to confirm that the proposed combined method is accurate and effective as the finite element method (FEM) model with much less time consumed.

Multidisciplinary Design of a Permanent-Magnet Traction Motor for a Hybrid Bus Taking the Load Cycle into Account

An electrical and mechanical design process for a traction motor in a hybrid bus application is studied. Usually, the design process of an electric machine calls for close cooperation between various engineering disciplines. Compromises may be required to satisfy the boundary conditions of electrical, thermal, and mechanical performances. From the mechanical point of view, the stress values and the safety factors should be at a reasonable level and the construction lifetime predicted by a fatigue analysis. In a vehicle application, the motor has to be capable of generating high torque when accelerating, and in normal operation, the losses of the machine should be low to be able to cool the machine. Minimization of the no-load iron losses becomes a very important electrical design requirement if the traction motor and the generator are mechanically connected with an internal combustion engine when it is operating as the only source of torque. The manufacturing costs of the motor are also taken into account in this paper.

Drive Cycle Analysis of a Permanent-Magnet Traction Motor Based on Magnetostatic Finite-Element Analysis

This paper introduces a method for the drive cycle performance analysis of a permanent-magnet traction motor based on a fast magnetostatic finite-element analysis (FEA). The flux linkage and torque behavior of the permanent-magnet synchronous machine is studied by a nonlinear magnetostatic FEA as a function of direct- and quadrature-axis stator current components. In the analytical machine performance analysis, the current combinations producing the desired torque and minimizing the losses are determined. The iron loss is calculated with the time-transient FEA at no load. The maximum stator flux linkage, limited by the battery voltage, is taken into account. The drive cycle analysis, based on optimal current component surfaces, is carried out for a traction motor of an electric sports car. The results are compared with values measured for the drive cycle on a racetrack.

Weight-Transducerless Starting Torque Compensation of Gearless Permanent-Magnet Traction Machine for Direct-Drive Elevators

To improve the starting performance of a permanent-magnet traction machine without a weight transducer in a gearless elevator, an adaptive starting torque compensation strategy is proposed in this paper. The dynamic model of the direct-drive elevator traction system considering the rope elasticity, the brake releasing, and the friction torque is established. Based on the dynamic model, the characteristics of the synthetic load torque exerted on the traction machine during elevator start-up are obtained. In order to balance the unknown load torque for the gearless elevator, a fuzzy self-tuning strategy is adopted to generate a suitable starting torque for compensation by tuning the change rate of electromagnetic torque according to the encoder signal. The torque compensator is designed with the aim of getting a minimized sliding distance and avoiding traction sheave reversal. Both simulation and experimental results are provided to verify that the proposed weight-transducerless adaptive starting torque compensation strategy can achieve superior riding comfort of shorter sliding distance, faster dynamic response, and smaller sliding speed.

Design of a Traction Motor With Tooth-Coil Windings and Embedded Magnets

Traction motor design significantly differs from industrial machine design. The starting point is the load cycle instead of the steady-state rated operation point. The speed of the motor varies from zero to very high speeds. At low speeds, heavy overloading is used for starting, and the field-weakening region also plays an important role. Finding a suitable field-weakening point is one of the important design targets. At the lowest speeds, a high torque output is desired, and all current reserves of the supplying converter unit are used to achieve the torque. In this paper, a 110-kW 2.5-p.u. starting torque and a maximum 2.5-p.u. speed permanent-magnet traction motor will be studied. The field-weakening point is altered by varying the number of winding turns of machine. One design is selected for prototyping. Theoretical results are verified by measurements.

Development and design of a narrow-gauge hydrogen-hybrid locomotive

Hydrogen used as an energy carrier is a promising alternative to diesel for autonomous railway motive power, but, globally, few prototypes exist. In 2012, the Institution of Mechanical Engineers held the inaugural Railway Challenge, in which the participating teams had to develop, design and construct a locomotive to run on 10.25 inch (260.35 mm) gauge track while meeting certain set design criteria as well as competing in operational challenges. The University of Birmingham Railway Challenge Team’s locomotive design is described in this paper. The vehicle is the UK’s first hydrogen-powered locomotive and is called Hydrogen Pioneer. The drive-system consists of a hydrogen tank, a 1.1 kW proton-exchange-membrane fuel cell stack, a 4.3 kWh battery pack and two 2.2 kW permanent-magnet traction motors. The development of the locomotive, from the original concept to the final design, and the design validation are all presented in this paper. The locomotive completed successfully all challenges through which the proof of the concept of a hydrogen-hybrid locomotive was established.

A Fault-Tolerant Permanent-Magnet Traction Module for Subway Applications

A fault-tolerant permanent-magnet traction module is proposed for subway application, which has three different operation modes: normal, isolation, and fault-tolerant mode. In normal mode, 2 three-phase permanent-magnet synchronous machines (PMSMs) are controlled by 2 three-leg voltage-source inverters (VSIs), respectively. The proposed module can output maximum torque and reach the maximum velocity. When one leg fails, the corresponding PMSM is isolated from the fault VSI and the fault subway train operates in isolation mode, in which the traction effort is reduced but the maximum velocity can be maintained under light load. However, the fault subway train will stop if the load is heavy. To avoid the stop, the fault subway train is switched into fault-tolerant mode, in which the healthy VSI and fault VSI are reconfigured to 1 five-leg VSI by a fault-tolerant bridge. Due to lower phase-phase voltage apportionment ratio, the fault-tolerant mode is not used until the velocity is decreased to half of the maximum velocity. In fault-tolerant mode, the nonadjacent selection principle is proposed to prevent the common leg from overcurrent damage. The subway train equipped with the proposed module can maintain basic operation performances if any leg fails. The performances are analyzed and the effectiveness is verified by experimental results.

Series hybrid powertrain simulation and hardware-in-the-loop application for a light-duty nontactical vehicle

An improvement in the fuel economy of nontactical vehicles has and continues to be a significant initiative for US military ground vehicles. This paper investigates the potential improvement in the fuel economy of a prototype-built nontactical series hybrid cargo van. A baseline conventional vehicle is first modeled and validated. The current series hybrid van equipped with a lead–acid battery pack and an a.c. induction traction motor is then modeled and simulated in two driving cycles. A vehicle equipped with a nickel–metal hydride battery pack and a vehicle with a lithium-ion battery pack, together with an optimal hybrid powertrain control strategy, are simulated for further improvement in the fuel economy. The simulation results indicate improvements in the fuel economy of 39.6% and 43.6% for the vehicle with a nickel–metal hydride battery pack and the vehicle with a lithium-ion battery pack respectively. A hardware-in-the-loop application for motor-in-the-loop testing is also conducted to evaluate a permanent-magnet traction motor which is designed to replace the current induction motor. This study provides a design guideline and battery pack sizing for series hybrid powertrains in light-duty nontactical vehicles.

Thermal Modeling of a Segmented Stator Winding Design

This paper presents a thermal analysis of a segmented stator winding design. As the thermal performance is one of the main factors limiting a machine's output capability, a thermal test on a complete prototype machine is an essential part of the design process. However, for the segmented stator winding design, a test-informed thermal analysis on a single stator tooth can be performed prior to the manufacture of the full machine. This approach allows for a rapid and inexpensive assessment of the thermal performance of the complete machine and early identification of design modifications needed. The research has been applied to the design of a highly efficient and compact permanent-magnet traction motor. A thermal model for a single tooth was developed and supported by tests to identify key heat transfer coefficients. A number of winding assemblies were compared, and the most promising was selected for the final motor prototype. The results from the approach are compared with thermal test results from the complete machine.

IPM Traction Machine With Single Layer Non-Overlapping Concentrated Windings

In this paper, an interior permanent-magnet traction drive machine with single layer non-overlapping concentrated stator winding is analyzed. In the single layer winding design, the number of stator slots and a winding factor are specifically considered. Moreover, the effect of varying the coil pitch on the winding factor and torque pulsations is investigated. A new calculation method is proposed, whereby the constant torque and field-weakening speed characteristics of the machine drive can be predicted using torque and flux linkage functions. The measured and predicted field-weakening performance of a 150-kW direct traction drive machine is presented.