Rotor Synchronous Motor Research Articles

Analysis of high speed permanent magnet synchronous motor rotor supported by air foil bearings

Analysis of high speed permanent magnet synchronous motor rotor supported by air foil bearings

Design of A Novel Line Start Synchronous Motor Rotor

Line start permanent magnet synchronous motors (LS-PMSM) are preferred more and more in industrial applications, because they can start on their own and because of their high efficiency. In this study, a new LS-PMSM rotor typology is suggested, which is modelled using surface mount permanent magnets, in which two different slot types have been used together. The rotor of an asynchronous motor on the industrial market in the IE2 efficiency segment has been remodeled in the study, resulting in an increase in motor efficiency from 85% to 91.8%. A finite elements software was used for determining motor design and performance, in addition to analytical methods.

Design of Power Density Improvement by Applying Novel Shape of Slit and Notch to Outer Rib of Rotor of Spoke-type Permanent Magnet Synchronous Motor

Objective:In this study, improvement of power density by applying novel shape of slit and notch to outer ribs of a rotor that reduces magnetic flux leakage in outer rib and increases air-gap magnetic flux density for spe PMSM for a washing machine, was investigated.Methods:It is important that motors for home appliance require lower manufacturing cost, high power and high efficiency. In order to increase power, rotor shape is re-designed. In the outer rib of the rotor, magnetic flux leakage occurs by permanent magnet and magnetic flux is saturated which is one of the factors that reduces the power and efficiency. However, if the outer rib is designed to be too thin, the permanent magnet may scatter during high-speed rotation. Therefore, a design considering permanent magnet scattering is necessary. Motor for a washing machine has two operating points that washing mode at constant torque point and dehydrating mode at high-speed point.Conclusion:For improvement of higher power density, 2-D finite elements analysis was performed to optimize the parameters of the shape of slit and notch to increase the torque. The torque increases by optimizing width and length of slit shape and notch shape. Finally, with the optimized parameters of shape of slit and notch, stack length was adjusted as per torque requirement for a washing machine motor and power density increases considering the safe factor from stiffness analysis.

Performance Analysis of Synchronous Machines After Disconnecting Stator Coils

This paper offers methods to analyze the performance of three-phase synchronous machines operating with an unsymmetrical stator winding caused by cutting out and bypassing coils. The resulting unsymmetrical current distribution in the stator winding tends to produce overheating in parts of the stator and damper windings at full load as well as torque pulsations. Thus, the main objective of this study is to determine the maximal load, under which the unsymmetrical machine may operate without exceeding the permissible temperature limit. Based on the multiloop method, a mathematical model of a synchronous machine with missing coils in the stator winding is developed. In order to determine the current distribution, the machines’ system of differential equations is solved by using a numerical integration method (Runge–Kutta method). As an alternative method, the system of differential equations in the steady state is reduced to a system of algebraic equations, which can be solved with the Gaussian elimination method. Both methods are validated by the measurement results of a 25-kW salient pole synchronous machine. Furthermore, both the circulating current within the parallel branches and the line currents of the different phases as a result of coil or coil group cut-outs are analyzed for a large 41-MW cylindrical rotor synchronous motor.

An Innovative Rotor Position Detection at Stand-Still and Low Speed with Carrier Phase-Shifted PWM Method

An innovative permanent magnet synchronous motor rotor position detection method using d-q reference-frames derived from PWM inverter switching is presented based on carrier phase-shift PWM method. It also gives the development the polarity identification at standstill for permanent magnet synchronies motor in the rotary frame with position detected of the neutral voltage. The new technique detects the motor position from simple measurements of the neutral point voltage of the motor influenced by the variation of inductances with respect to rotor position. The transfer is derived with constant element and 2nd harmonic element of selfinductance and mutual-inductance between three phase inductances and the inductance of d-axis and q-axis. Theoretical studies are carried out and verified using experiment results with variation rotor position over one electrical cycle at standstill. Rotor position estimation from stator inductance variation with rotor position is effective in zero speed and low speed.

Self-Sensing Control of Wound Rotor Synchronous Motor Drive for Mine Hoist

Control of a wound rotor synchronous motor (WRSM) drive for a mine hoist has to address specific properties. One of them is reliable and safe operation without sensor of the rotor position. To fulfill this requirement, we propose a sensorless vector control allowing drive operation with maximum available torque. The proposed sensorless rotor position estimation utilizes natural ac components of the rotor field excitation current. This component acts as a modulation signal, which has measurable effect on the stator currents and can be used to estimate the actual position of the rotor. We investigate two techniques for identification of the rotor position: The phase-lock loop and the extended Kalman filter. Both techniques are able to estimate the rotor position and magnetic polarity. However, the Kalman filter offers faster convergence and higher accuracy. It is able to provide reliable rotor position estimation in the whole speed range of the drive. Proper function of the introduced control algorithm is verified by simulations and experiments made on a developed small-scale prototype of a mine hoist drive of rated power of 10 kW.

Study on optimal design of 210kW traction IPMSM considering thermal demagnetization characteristics

This study analyses the permanent magnet (PM) used in the rotor of an interior permanent magnet synchronous motor (IPMSM) used for driving an electric railway vehicle (ERV) in the context of controllable shape, temperature, and external magnetic field. The positioning of the inserted magnets is a degree of freedom in the design of such machines. This paper describes a preliminary analysis using parametric finite-element method performed with the aim of achieving an effective design. Next, features of the experimental design, based on methods such as the central-composition method, Box-Behnken and Taguchi method, are explored to optimise the shape of the high power density. The results are used to produce an optimal design for IPMSMs, with design errors minimized using Maxwell 2D, a commercial program. Furthermore, the demagnetization process is analysed based on the magnetization and demagnetization theory for PM materials in computer simulation. The result of the analysis can be used to calculate the magnetization and demagnetization phenomenon according to the input B-H curve. This paper presents the conditions for demagnetization by the external magnetic field in the driving and stopped states, and proposes a simulation method that can analyse demagnetization phenomena according to each condition and design the IPMSM that maximizes efficiency and torque characteristics. Finally, operational characteristics are analysed in terms of the operation patterns of railway vehicles, and control conditions are deduced to achieve maximum efficiency in all sections. This was experimentally verified.

Shock-Resistance Rotor Design of A High-Speed PMSM for Integrated Pulsed Power System

This paper provides stress analytical models for a variable-speed simplified rotor of the surface-mounted permanent magnet synchronous motor (PMSM). The impact developed by alternator discharge on the prime motor rotor was analyzed. Parameters, such as interference fits between sleeve and magnets, rotor core and shaft, sleeve thickness, rotor heating have significant influences on the design of the shock-resistance rotor. Then the stress distribution of the actual rotor was verified by a 3-D finite element analysis model, and the critical speed of the integrated rotor was computed.

A design method for permanent magnet synchronous motors by incorporating topology optimization and system parameter optimization based on the response surface methodology

When designing a structure of a rotor of interior permanent magnet synchronous motor (IPMSM), optimization for layouts of permanent magnets (PM) and a structure of yoke is concurrently required. Since the optimization problem becomes large and complicated, it is appropriate to decompose the original problem into sub problems. That is, the IPMSM rotor optimization problem is decomposed into an optimization problem of the structure of yoke under a fixed PM layout condition and an optimization problem of the layout of PM under a fixed yoke structure condition. However, a solution obtained from the decomposed problems is not necessarily optimal at the level of the original rotor optimization problem. In order to obtain an optimized solution at the original problem level, it is necessary to appropriately determine what conditions to be set for variables that are not designed. Therefore, we construct a meta-model relating the solution of topology optimization of yoke structure and the layouts of PM by using response surface methodology. Then, by determining the optimized layout of the PM using the meta-model, an optimized solution is obtained at the original problem level. Numerical example of optimization of the IPMSM rotor is shown. By the proposed method, high performance of average torque is realized.

Current Control of WRSM Considering Magnetic Saturation Phenomenon

This paper introduces the characteristics of a 120 kW class wound rotor synchronous motor (WRSM) considering the effects of magnetic saturation in electrical steel. The flux linkage due to the rotor windings and the $d$ -axis inductance of WRSM vary non-linearly because of the magnetic saturation. This affects the selection of a current combination for maximum torque per ampere (MTPA) control. The relation between the current combination for MTPA control and magnetic saturation is analyzed in this paper. Finding a current combination that satisfies the requirements is very difficult, because WRSM has complicated current combinations ( $i_{f}$ , $i_{d}$ , and $i_{q})$ . Therefore, an algorithm for the calculation of the optimal current is proposed using the Lagrange function, and the current map is presented. Finally, the validation of the selected current combination is performed through the comparison of the results of an experiment and the finite-element analysis.

Calculation of the Maximum Mechanical Stress on the Rotor of Interior Permanent-Magnet Synchronous Motors

This paper proposes a novel analytical method to calculate the maximum mechanical stress (MMS) on the rotor of the interior permanent-magnet synchronous motor with V-shaped rotor structure. Based on the traditional equivalent ring method, an improved method, which draws on the principle of equivalent centroid, is proposed to calculate the mechanical stress on the bilateral magnetic bridge. A rotor model with spokes is also built to calculate the mechanical stress on the central magnetic bridge. The stress concentration factor, together with its selection method, is also defined to calculate the MMS on the junctions. Then, the changing trends of the mechanical stress on the bilateral and central bridges are obtained along with the change in the V-shaped angle. The rotor faults of the two IPMSMs are analyzed based on the research results, and the optimized prototype is designed and fabricated. Experimental results of the optimized prototype show that the proposed equivalent methods have great applicability. Finally, the suggestion to design the V-shaped rotor structure is presented to determine the design rapidly and accurately.

Conceptual design of sleeve rotor synchronous reluctance motor for traction applications

Synchronous reluctance machines are very appealing for high speed traction motor design due to their robustness, simple structure, absence of magnets, and simple control. The absence of magnets means that synchronous reluctance (SynRel) machines are not susceptible to price variability and sustainability of rare-earth materials. Moreover, there are no concerns about demagnetisation or uncontrolled generation mode. However, the challenge of achieving a good constant power to speed ratio is dependent on the mechanical aspects of the design. Conventional SynRel designs perform poorly compared with the permanent magnet machines due to the presence of bridges and/or centre posts in absence of the magnets to help saturate these regions. In this case, the challenge of rotor mechanical retention is addressed with the help of a sleeve on the rotor to reduce the need for bridges and/or centre posts. Design optimisation including the mechanical aspects of the sleeve is presented in this study. The final design with a sleeve will be shown to be superior to a conventional design in terms of power density, rotor losses, saliency and torque ripple.

An Off-line Maximum Torque Control Strategy of Wound Rotor Synchronous Machine with Nonlinear Parameters

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Lookup table (LUT). The experiment shows the validity of algorithm.

Position Sensorless Control of PMSM Based on a Sliding Mode Observer

Sliding mode observer(SMO) for permanent magnet synchronous motor(PMSM) speed and rotor position is used in this paper to realize sensorless control. According to the PMSM mathematical model and sliding mode control theory, the SMO mode was given. The stability condition of SMO is studied to make sure that the observer is stable in converging to the sliding mode plane. This paper analyzes the structure and performance of the proposed SMO strategy with Simulink based simulation. Simulation results are presented to verify the proposed sensorless control algorithm.

Generic optimal control of synchronous motors

This paper presents one generic optimal current control that can be applied to all types of synchronous motors: interior permanent magnet synchronous motors, wound rotor synchronous motor and hybrid excitation synchronous motor. The control aims to meet the torque and speed requirements while insuring minimal losses. The main contribution of the work is that analytical expressions for the optimal reference currents are computed with respect to armature current limit in addition to armature voltage constraint. Another contribution is that the proposed optimisation algorithm is extended to include the iron losses, too, which cannot be done easily using the standard control method. Simulation proves that the presented control yields indeed to the solution with minimum losses.

48V 계자 권선형 동기전동기 고성능 자속기반 토크제어

In this paper, High performance torque control based on the flux mapping of 48V Wound Rotor Synchronous Motor has been studied to improve torque control. Flux map considering MTPA (Maximum Torque Per Ampere), MFPT (Minimum Flux Per Torque), Maximum efficiency point at the same torque command and flux command for each field current was produced. Current map using flux mapping of Each field current was applied to the MTPA, MFPT. Generating a current vector locus was to determine the characteristics of the operation region. Through the Matlab/Simulink simulation, difference between speed-torque map and flux map was represented. The suggested flux map was tested actual experiments on a dynamometer.

Hybrid Synchronous Motor Magnetic Field Analysis

This paper introduces researching results of hybrid synchronous motor rotor permanent-magnet part magnets’ magnetization influence on its starting torque. The magnetic field analysis is made in reluctance synchronous motor and synchronous permanent-magnet motor, as main parts of the hybrid motor.

PMSM Drive Position Estimation: Contribution to the High-Frequency Injection Voltage Selection Issue

High-frequency injection (HFI) is an alternative method to estimate permanent magnet synchronous motor (PMSM) rotor position using magnetic saliency. Once the maximum fundamental electrical frequency and the power converter switching frequency are set, the HFI voltage amplitude tuning is generally based on trial and error. This paper proposes a methodology to select the appropriate high-frequency signal injection voltage amplitude for rotor position estimation. The technique is based on an analytical model taking into account the noise in the voltage supply to derive the resulting currents containing the information on the rotor position. This model allows setting the injection voltage amplitude that leads to the maximum acceptable position error for a given signal-to-noise ratio and a speed range. The approach is validated with the analytical and the global drive models through extensive simulations. Experimental results on a 1-kW PMSM drive confirm the interest of the proposed solution.

Systemic Design and Modelling of a Coiled Rotor Synchronous Motor Dedicated to Electric Traction

In this paper, we present a methodology of design and modeling of the controlling parameters of synchronous motor with wound rotor, based on the analytical method. This methodology ensures a wide operating speed range of electric vehicles. It takes into account several physical and technological constraints. The model is highly parameterized and quickly helps to provide the dimensions and power train controlling parameters values by varying the mechanical characteristics of the vehicle. It is compatible with all brands of electric vehicle power with single motor. The analytical modeling approach is validated entirely by the finite element method.

A ZCS buck excitation converter for electric vehicle with wound rotor synchronous motors

In this paper, a high power density zero-current switching (ZCS) Buck excitation converter for electric vehicle (EV) with wound rotor synchronous motors is proposed. To eliminate the pulse noises in excitation current when considering the parasitic parameters for the rotor coil, a small coupled inductor and a small resonant capacitor are combined with basic Buck circuit. Owing to the existence of resonance, zero-current soft-switching for both turn-on and turn-off transitions is achieved, and more importantly, a constant output current without any spikes is guaranteed, which contributes to efficiency promotion and electromagnetic interference (EMI) reduction. Since no large-sized output filters or resonant components are adopted, the volume of the converter is minimised. In the end, PSIM simulation results are presented to verify the feasibility of theoretical analysis.