This paper analyzes the effects of the rotor position error in the performance of field-oriented-controlled permanent-magnet synchronous machine (PMSM) drives intended for electric vehicle (EV) traction applications. A special focus is given to the torque ripple generated along the characteristic trajectories in the different operating regions of the PMSM. An extended and generalized model of the torque ripple produced by the PMSM as a function of the rotor position error is analytically deduced. An infinite-speed interior-(I)PMSM drive and a finite-speed surface-mounted (SM)-PMSM drive are considered for the simulations carried out in MATLAB-SimPowerSystems. The experimental results have been validated with a TM4 EV drive controlling an 80-kW SM-PMSM. The torque ripple has been evaluated for both motoring and regenerative braking operation modes under maximum torque conditions going from 100 N · m at 1000 r/min up to 55 N · m at 9000 r/min. The obtained simulation and experimental results demonstrate the good accuracy of the proposed model for evaluating the torque ripple produced in PMSMs due to the error from the rotor position sensor.

Effects of Rotor Position Error in the Performance of Field-Oriented-Controlled PMSM Drives for Electric Vehicle Traction Applications

Permanent magnet synchronous machines (PMSM) have been widely used in a variety of applications. A strong electromagnetic force exists between the rotor magnets and the stator core in a PMSM. The force directly causes mechanical deformation and vibration of the stator. In small PM motors, mechanical vibration comes mainly from the electromagnetic force of the stator. This paper gives the general expression of the frequency and corresponding mode number of radial force harmonics for a PMSM with a three-phase symmetrical double-layer winding. The paper shows that the lowest mode number of radial force harmonics is the greatest common divisor of pole number and slot number. The force harmonics with a low mode number can induce a high mechanical vibration, especially for PMSMs with a fractional slot combination. This is simulated using a weak-coupling electromagnetic-mechanical finite element model. To illustrate the influence of radial force harmonics with a low mode number on vibration, a method to eliminate the lowest mode number force harmonics for the fractional slot combination motor is proposed. A test rig for the 12-slot 8-pole prototype motor is set up. The experimental and simulated results confirm that force harmonics with low mode number have a major impact on vibration.

Influence of Radial Force Harmonics With Low Mode Number on Electromagnetic Vibration of PMSM

In high-performance control of ac machines through variable frequency drives, the knowledge of machine parameters plays a decisive role. The accuracy with which machine parameters can be known is directly related to the time and effort put during the testing and commissioning process. In the ever-demanding industrial environments, the time spent on parameter identification translates into loss of production. To reduce commissioning times, research in this direction has focused on automatizing the identification procedure without loss of accuracy. This paper reviews different lines of research adopted over the past few decades for machine parameter identification. Parameter estimation of ac machines is considered because of their widespread applications from servomechanisms to traction to aviation. The surveyed works include self-commissioning schemes that have become an integral part and a salient feature of modern electric drives. This feature enables the drives to automatically identify machine parameters and tune the control loops.

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Parameter Identification and Self-Commissioning in AC Motor Drives: A Technology Status Review

In this paper, radial forces and torque ripple characteristics are investigated in permanent magnet (PM) machines having different pole and slot combinations. Using the PM machines with concentrated windings could be beneficial in direct-drive wind generators since it is possible to reduce the size and weight of the generator. The PM machines with concentrated windings having a large number of poles are compared to investigate the effect of pole and slot combinations on force and vibration characteristics in low-speed generators. Cogging torque waveforms and torque ripple are investigated using time-stepping finite-element analysis. Analysis of radial forces is presented, including investigation on radial force density distribution, total forces on teeth, and time-dependent force waveforms on a tooth. Structural analysis and experimental modal analysis are performed on the prototype generator. The main mode of vibration in the prototype machine is observed experimentally and the results are in good agreement with the simulations.

Influence of Pole and Slot Combinations on Magnetic Forces and Vibration in Low-Speed PM Wind Generators

Permanent-magnet synchronous motors (PMSMs) have been widely used as the driving core in electric vehicles due to the high power/torque density and high efficiency. Recent years have witnessed a great effort on the vibration and noise of PMSMs in order to ensure the driving comfort. In this paper, the state of the art and recent progress of the electromagnetic vibration and noise of PMSMs for electric vehicles are presented, with emphasis on the induced mechanism, prediction method, suppression method, and sound quality. The future trends faced are also described.

Electromagnetic Vibration and Noise of the Permanent-Magnet Synchronous Motors for Electric Vehicles: An Overview

This paper investigates the effect of pole and slot combination on the vibration and noise in permanent magnet synchronous motor (PMSM). Two PMSMs that have the same performances but different pole and slot combinations are studied. A numerical analysis process for the vibration is introduced. First, by using the electromagnetic field finite element analysis (FEA) and Maxwell stress tensor method, the radial forces of these two motors are analyzed. In order to evaluate the effect of the radial force on the vibration, then the equivalent magnetizing current method is used to calculate the local force which then is employed in the mechanical FEA analysis. Finally, an experiment is processed to test the vibration and noise of these two motors, and verify the proposed analysis process. The effect of the pole and slot combination on the noise and vibration are revealed.

Effect of pole and slot combination on noise and vibration in permanent magnet synchronous motor

This paper presents modeling of core loss resistance for d-q equivalent circuit analysis of IPMSM considering harmonic linkage flux. High efficiency is one of the major advantages of IPMSM, therefore precise loss analysis is required for high efficiency design. However, there is practical limitation of d-q equivalent circuit analysis in the calculation of core loss due to harmonic components of flux especially in high speed region where field weakening is generally applied. Harmonic components of linkage flux leads to the underestimation of core loss. Especially operation with high constant speed power range results in severe underestimate of core loss. Harmonic components of linkage flux are added to the general d-q axis equivalent circuits in this paper, therefore core losses due to harmonic components are considered by increased voltage drop across core loss resistance. From the presented modeling of core loss resistance, precise core loss can be obtained. Verification with FEA and experiments are presented.

Modeling of Core Loss Resistance for $d\hbox{-}q$ Equivalent Circuit Analysis of IPMSM considering Harmonic Linkage Flux

This paper introduces major potential faults of interior PM synchronous motor (IPMSM) and their simulation realization method based on Simulink@MATLAB. IPMSM often is operated in MTPA and flux weakening control strategies. If a fault occurs, the great current or backwash voltage may be generated and damaged the motor system. The faults of IPMSM, generally, contain single-phase open circuit, single-phase and 3- phase short circuit, uncontrolled generation, and switch-on failure of one transistor. When different fault occurs, the circuit of total system including motor and inverter also will be changed. Therefore, it is necessary to analyze and establish independent model for each kind of fault. In this paper, first, the system circuit is analyzed as different fault type. Then, the corresponding models based on Simulink@MATLAB are established. The absence of experiment results leads that the veracity of simulation results can not be verified, but the waveforms will be explained by theory analysis.

Faults analysis and simulation for interior permanent magnet synchronous motor using Simulink@MATLAB

An inductance measurement method for interior permanent magnet synchronous machine (IPMSM) is proposed in this paper. In this method, the motor is measured at standstill condition, and only a 3-phase voltage source, an oscilloscope and a DC voltage source are required. Depending on the deductive dq-axis voltage equations in the stationary frame of reference, the dq-axis inductances at different current magnetite and vector angle can be calculated by the measured 3-phase voltages and currents. And hence, the saturation and cross-magnetizing effect of the inductances are measurable. This paper introduces the principle equations, experiment setup, data processing, and results comparison on the concentrated-winding and distributed-winding IPMSMs.

An improved AC standstill method for testing inductances of interior PM synchronous motor considering cross-magnetizing effect

This paper investigates and compares the inductance evaluation methods for interior permanent magnet synchronous motors (IPMSM). Three major finite element methods will be discussed. First, their detail calculation processes are presented as well as their fundamental principles. Not only the results, but also their solving method, computation time and complexity are compared. Then, the discussion on the inductance classification is derived, and finally the calculated results are verified with a series of experiments. The investigation of the calculation methods and the comparison of the evaluated results will be helpful to choose the appropriate inductance calculation method for IPMSM.

Tao Sun

Papers

Effect of pole and slot combination on noise and vibration in permanent magnet synchronous motor

Modeling of Core Loss Resistance for $d\hbox{-}q$ Equivalent Circuit Analysis of IPMSM considering Harmonic Linkage Flux

Faults analysis and simulation for interior permanent magnet synchronous motor using Simulink@MATLAB

An improved AC standstill method for testing inductances of interior PM synchronous motor considering cross-magnetizing effect

Investigation and comparison of inductance calculation methods in interior permanent magnet synchronous motors