Permanent Magnet AC Motor Research Articles

A nonlinear optimal control approach for permanent magnet AC motors with non-sinusoidal back EMF

A nonlinear optimal control approach for permanent magnet AC motors with non-sinusoidal back EMF

Influence of a Winding Short-Circuit Fault on Demagnetization Risk and Local Magnetic Forces in V-Shaped Interior PMSM with Distributed and Concentrated Winding

This paper presents a comparison of 30/8 and 12/8 AC permanent magnet motors with distributed (DW) and concentrated winding (CW) designed for electric vehicle traction. Both prototypes are based on an interior permanent magnet (IPM) motor topology and contain V-shape magnets. The radial flux AC IPM motors were designed for an 80 kW propulsion system to achieve 125 N·m. Finite element models (FEM) used to design the geometry of IPM motors and the required useful parameters of electric motors are widely investigated. The accuracy of finite element models is verified and validated on the basis of test data. Numerical simulations of healthy and faulty operation states, and studies of winding faults based on the FEM offer a deeper understanding of the associated phenomena. Therefore, in this paper, a short-circuit fault in a stator winding was simulated to investigate the transient currents under an external load collapse, for all winding phases. These simulations were used to define other important machine parameters to improve mechanical reliability of the motors and to assess the potential risk of permanent magnet (PM) demagnetization. Furthermore, the analysis of local magnetic forces affecting the PMs in the rotor and their possible displacement in a short-circuit situation were performed, also taking into account the centrifugal force. Lastly, it is demonstrated that the choice of winding configuration has a significant impact on the uncontrolled displacement of magnets in the rotor.

Field Oriented Sliding Mode Control of Surface-Mounted Permanent Magnet AC Motors: Theory and Applications to Electrified Vehicles

Permanent magnet ac motors have been extensively utilized for adjustable-speed traction motor drives, due to their inherent advantages including higher power density, superior efficiency and reliability, more precise and rapid torque control, larger power factor, longer bearing, and insulation life-time. Without any proportional-and-integral (PI) controllers, this paper introduces novel first- and higher-order field-oriented sliding mode control schemes. Compared with the traditional PI-based vector control techniques, it is shown that the proposed field oriented sliding mode control methods improve the dynamic torque and speed response, and enhance the robustness to parameter variations, modeling uncertainties, and external load perturbations. While both first- and higher-order controllers display excellent performance, computer simulations show that the higher-order field-oriented sliding mode scheme offers better performance by reducing the chattering phenomenon, which is presented in the first-order scheme. The higher-order field-oriented sliding mode controller, based on the hierarchical use of supertwisting algorithm, is then implemented with a Texas Instruments TMS320F28335 DSP hardware platform to prototype the surface-mounted permanent magnet ac motor drive. Last, computer simulation studies demonstrate that the proposed field-oriented sliding mode control approach is able to effectively meet the speed and torque requirements of a heavy-duty electrified vehicle during the EPA urban driving schedule.

The Effect of Failure Prognosis and Mitigation on the Reliability of Permanent-Magnet AC Motor Drives

Fault diagnosis and its extensions to failure prognosis aim to develop methods that decrease outages and thus increase reliability. Among these methods are redundancies and changes of topology, power levels, and control algorithms. Since diagnosis methods are imperfect, false positives and negatives, as well as delayed fault diagnosis, may occur. Although the diagnosis of a fault can lead to appropriate maintenance, the estimation of the time to failure through prognosis can lead to the timely mitigation of the fault and, in turn, can extend the lifetime and reliability of the drive. In this paper, we present a new approach to the mitigation of permanent-magnet ac motors that uses a failure prognosis method to predict failures and the remaining useful life and uses the output of the prognosis algorithm to decide when to modify the system and mitigate the fault. A methodology to calculate the mean time between failures with and without mitigation is also presented. The proposed approach is illustrated through a simple example of how the prognosis of failure due to a developing intermittent open circuit in one of the phases increases the drive reliability.

Proximity Losses in the Windings of High Speed Brushless Permanent Magnet AC Motors With Single Tooth Windings and Parallel Paths

Proximity and additional eddy-current losses can be difficult to calculate and if there are parallel paths then there can sometimes be increased losses which can be unexpected. The paper addresses these winding losses in a brushless permanent magnet machine with 18 slots, 16 poles and a spoke type rare earth magnet rotor. The winding has coils that are one pitch. Different simulation scenarios are investigated to illustrate the even when the windings are in slots they can still experience increased ac copper losses when rotating at high speed. High speed machines often have few series turns because of the high rate of change of flux linkage so they can have many parallel turns or strands in hand. Simulations are carried out at 12 000 r/min then some simulations are run at 4000 r/min for completeness. The simulations are run in a 2-D finite-element analysis environment.

FPGA Based a PWM Technique for Permanent Magnet AC Motor Drives

<p>The permanent magnet AC motor trapezoidal (BLDC motor) is not strictly DC motor, which uses a pulsed DC fed to the stator field windings to create a rotating magnetic field. Therefore, the motor needs an electronic commutation to provide the rotating field. A pair of switches must be turned on sequentially in the correct order to energize a pair of windings. If the incorrect order is applied, then the BLDC motor will not operate properly. This paper presents a smart guideline to ensure that the order to energize a pair of windings is correct. To ensure the guideline, FPGA based a simple commutation state machine scheme to control BLDC motor is presented. The experiment results have shown that the guideline is correct. The commutation scheme was successfully realized using Altera's APEX20KE FPGA to control BLDC motor in both of forward/reverse rotations or forward/reverse regenerative braking properly.</p>

Literature Review of Permanent Magnet AC Motors and Drive for Automotive Application

Literature Review of Permanent Magnet AC Motors and Drive for Automotive Application

The Dynamic Simulation of the Three-Phase Brushless Permanent Magnet AC Motor Drives Using Lab View

In this paper, a mathematical model of the three-phase brushless permanent magnet AC motor drives in abc reference frame is described. A computer simulation of the motor drive is provided which utilized Lab VIEW software. The simulation can be conveniently used to study the dynamic as well as the Steady-state performance of the three-phase permanent magnet AC motor drives; with either trapezoidal or sinusoidal back emfs, under various operating conditions. The simulation results have been given in this paper.

Literature Review of Permanent Magnet AC Motors and Drive for Automotive Application

Literature Review of Permanent Magnet AC Motors and Drive for Automotive Application

Performance Improvement in High-Performance Brushless Rare-Earth Magnet Motors for Hybrid Vehicles by Use of High Flux-Density Steel

Hybrid and electrical vehicles use mostly high-efficiency brushless permanent-magnet AC motors and sinewave drives. The motors utilize rare-earth magnet material and also are required to have a very high torque-per-rotor volume. The designs are now very well refined and often use interior permanent-magnet (IPM) rotors for a better field weakening control. This configuration has been shown to increase the efficiency. In this paper, the Toyota Prius 2004 motor is modeled using finite element analysis with different laminated steel materials in order to assess the effectiveness of using high flux-density steel versus the material volume. Additionally to the IPM rotor in the manufactured design, a spoke magnet rotor is also investigated. It is found that using high flux-density laminated steel will either increase the performance of the motor or allow the motor to be reduced in size (in this case, reduction in axial length).

Development of Hydrogen Fuel Cell Motorcycle in South East Asia

Motorcycles are the most popular vehicles for motorised individual transport in Asia. Millions of motorcycles cause the majority of traffic-based air pollution. A prototype of a clean, silent and fuel efficient hydrogen fuel cell powered Motorcycle demonstrates an alternative. With the prototype of Pios Fuel Cell Motorcycle a proof of concept is done. "Pios" Fuel Cell Motorcycle is the latest prototype of a series of hydrogen fuel cell powered vehicles. The power train of the fuel cell motorcycle consists of fuel cell system, in hybrid with lithium polymer-ion battery and ultra capacitor module. A direct-coupled permanent magnet AC motor and an overrunning clutch coupled brushless DC motor are implemented as traction motors. To analysis different drive train configurations extensive dynamometer lab test were done. A comparison of direct fuel cell drive train with various hybridisation drive trains with ultra capacitor and lithium battery were systematically tested and analysed.

Diesel hybrid powertrain for passenger and light commercial vehicles

Diesel hybrid powertrain for passenger and light commercial vehicles

In-Depth Study of the Torque Constant for Permanent-Magnet Machines

The torque constant, together with the back-EMF constant, was originally used in permanent-magnet DC commutator (PMDC) motors to couple electric circuit equations with mechanical equations. It is still an open question how these two constants should be defined in brushless DC (BLDC) motors and permanent-magnet (PM) AC motors. We present an in-depth study of these two constants, and conclude that the definition based on the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> axes is applicable for the dynamic motion control of not only PM AC motors, but also BLDC motors.

Time–Frequency Analysis for Efficient Fault Diagnosis and Failure Prognosis for Interior Permanent-Magnet AC Motors

The detection of noncatastrophic faults in conjunction with other factors can be used to determine the remaining life of an electric drive. As the frequency and severity of these faults increase, the working life of the drive decreases, leading to eventual failure. In this paper, four methods to identify developing electrical faults are presented and compared. They are based on the short-time Fourier transform, undecimated-wavelet analysis, and Wigner and Choi-Williams distributions of the field-oriented currents in permanent-magnet ac drives. The different fault types are classified using the linear-discriminant classifier and k-means classification. The comparison between the different methods is based on the number of correct classifications and Fisher's discriminant ratio. Multiple-class discrimination analysis is also introduced to remove redundant information and minimize storage requirements.

A minimum-time control strategy for torque tracking in permanent magnet AC motor drives

A minimum-time torque control strategy for permanent-magnet AC motor drives is presented. The proposed technique neither requires the solution of a HJB-type equation, which would be practically unfeasible, nor uses Pontryagin's maximum principle. Instead, the solution is obtained by an ad hoc procedure based on the computation of reachability and controllability sets. In principle, the optimal control strategy can be carried out by iteratively solving a fourth-degree polynomial equation. For its efficient implementation, an algorithm based on Sturm sequences is suggested. The sequence of online operations required by the algorithm for a given tolerance on the optimal time is illustrated. The method has been tested on a laboratory prototype. Experimental results show the effectiveness of the technique.

Sensorless position estimation in a fault tolerant motor drive with redundancy

This paper proposes a sensorless position estimation scheme suitable for a fault tolerant permanent magnet (PM) AC motor drive with redundancy. The proposed fault tolerant motor has an electrically and magnetically isolated configuration to improve reliability and fault tolerance. The method utilises the instantaneous currents and voltages of the windings, and a mathematical model of the motor drives to estimate the rotor position. Simulation results are shown to demonstrate the effectiveness of the proposed estimation method.

Extended high-speed operation via electronic winding-change method for AC motors

In many applications, it is often needed to extend the speed range of an electric motor. In permanent magnet AC motors (PMAC), the maximum speed is limited by the available voltage for a given counter EMF value. Extension of the speed range can be achieved to some extent by using the Held weakening principle resulting in constant power characteristics, but is limited by machine parameters and inverter rating. Salient pole PMAC machines (inset or buried magnet types) are better suited for field weakening compared to surface mount PMAC machines. In induction motor-based spindle drives for machine tool applications, the wye/delta switchover method was adopted and still remains popular for extending the constant power range without sacrificing the torque capability at higher speeds. Conventionally, the wye/delta method employs mechanical contactors that have limited life and are associated with dead time in the range of tens to hundreds of milliseconds due to mechanical constraints. Power electronic versions of the contactors have been proposed, but they are rather complicated and involve many switching devices. This paper describes a novel and simple switching technique involving only two three-phase diode bridges and two IGBT switches to extend the speed range of AC machines (induction as well as permanent magnet type). The proposed method requires a center tap to be placed in each phase of the motor. The start, finish, and the center tap should be accessible thereby making the motor a nine-lead machine. Adopting the proposed method, results in an AC machine with dual-torque characteristics. When used in conjunction with field weakening principle, the highspeed range can be extended in PMAC machines. The circuit used to extend the speed range is described and supported by test results carried out on a non-salient type PMAC motor and an induction motor.

Effective method to measure back emfs and their harmonics of permanent magnet ac motors

As the HDD spindle motors become smaller and smaller, the back electromotive forces (emfs) measurement faces the new challenges due to their low inertias and small sizes. This article proposes a novel method to measure the back emfs and their harmonic components of PM ac motors only through a freewheeling procedure. To eliminate the influence of the freewheeling deceleration, the phase flux linkages are employed to obtain the back emf amplitudes and phases of the fundamental and harmonic components by using finite Fourier series analysis. The proposed method makes the freewheeling measurement of the back emfs and their harmonics accurate and fast. It is especially useful for the low inertia PM ac motors, such as spindle motors for small form factor HDDs.

Mechanical sensorless speed control of permanent-magnet AC motors driving an unknown load

A new sensorless scheme for high-performance speed control of permanent-magnet ac motors (PMACMs) driving an unknown load is proposed. This scheme uses an extended nonlinear reduced-order observer to estimate the induced electromotive force (EMF) and load torque. From the estimated variables, the rotor position, the rotor speed, and the position derivative of flux are calculated and are used to close the control loop. In order to improve the drive performance, the estimated load torque is incorporated as a feedforward signal in the closed control loop. In addition, the proposed sensorless PMACM drive allows the torque-ripple and copper-loss minimization for motors with an arbitrary EMF waveform. Simulation and experimental results to validate the proposal are presented in this paper.

Use of a matrix converter to enhance the sensorless control of a surface-mount permanent-magnet AC motor at zero and low frequency

This paper addresses the use of a matrix converter (MC) with high-frequency voltage injection for zero- and low-speed sensorless control of surface mount permanent magnet alternating current motors. This paper also proposes a dual compensation technique that can practically eliminate zero-current-crossing distortions in MCs, discusses the effect of such distortions on sensorless control using injection techniques, and presents experimental results that illustrate the enhanced low-speed sensorless performance that can be obtained from exploiting the effective linearity of the MC operation.