Three-phase Permanent Magnet Synchronous Motor Research Articles

Torque Superposition Compensation Fault-Tolerant Control for Dual Three-Phase PMSM with an Inverter Single-Leg Open-Circuit Fault

Dual three-phase permanent-magnet synchronous motors (PMSM) have wide applications in electric vehicles due to advantages such as excellent control performance and outstanding fault tolerance capability. However, present fault-tolerant control of inverter single-leg open-circuit faults cannot make full use of each phase winding of the motor, which limits the torque-production capability. This paper proposes a torque superposition compensation (TSC) control which can minimize the stator copper losses while increasing the torque-production capability. The phase winding originally connected to the faulty inverter leg is then linked to the DC-link mid-point. Thus, the winding in the faulty phase can be utilized to generate an additional torque. The symmetric dual three-phase windings torque model and the asymmetric five-phase windings compensation torque model for Ud/2 voltage level are constructed according to the torque superposition, respectively. Then, the three-subplane decomposition transformation matrix for the post-fault dual three-phase PMSM is derived, and the decoupling model in the d-q subplane is constructed, which achieves the optimal enhancement of the torque-production capability. The simulation results verify the effectiveness of the proposed TSC fault-tolerant control.

Accurate Calculation of Magnetic Field of Same-Pole and Same-Slot Surface-Mounted Three-Phase Permanent Magnet Synchronous Motor

This article presents a new type of surface-mounted three-phase permanent magnet synchronous motor with the same number of poles and slots which has obvious advantages in cogging torque. Since the same-pole and same-slot three-phase permanent magnet motor has three or more slot types and the slots are not evenly distributed on the circumference, this article adopts an accurate subdomain model that considers the position and slot width of each slot separately to perform an analytical calculation of the magnetic field. The motor is divided into three subdomains and modeled by Maxwell’s equations, and the magnetic scalar vector equation satisfied by each subdomain is solved by the method of separation of variables. A 24-pole 24-slot three-phase permanent magnet motor consisting of 13-pole 12-slot and 11-pole 12-slot is used to verify the correctness of the proposed analytical computational model. Compared with the finite element analysis, the proposed analytical model shows high accuracy in the calculations of the magnetic flux density of the three subdomains.

Open-Phase Fault Modeling for Dual Three-Phase PMSM Using Vector Space Decomposition and Negative Sequence Components

Post-fault modeling for dual three-phase permanent magnet synchronous motors (DTP-PMSMs) under the open-phase fault is presented in this article. By using the positive and negative sequence components for the dual three-phase system, the stator currents under the open-phase fault can be treated as a combination of the positive and negative sequence currents. By artfully constructing the negative sequence components in terms of the different initial angles and amplitudes, the single-phase open-circuit fault and certain dual-phase open-circuit fault can be represented. Based on the conventional and modified vector space decomposition (VSD), only the positive sequence components are projected into the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha \beta $ </tex-math></inline-formula> subspace, namely, the torque-producing subspace, and the negative sequence components are transformed into the harmonic subspace. With the conventional proportional–integral (PI) current regulators, the dc components of the positive and negative sequence currents can be readily controlled under the open-phase fault. Experiments based on a DTP-PMSM prototype verify the effectiveness of the proposed open-phase fault modeling using VSD and negative sequence components.

Extended Kalman Filter Based Inductance Estimation for Dual Three-Phase Permanent Magnet Synchronous Motors Under the Single Open-Phase Fault

Dual three-phase permanent magnet synchronous motors (DTP-PMSMs) feature a satisfactory capability of the fault-tolerant operation due to the inherent multiphase configuration. To improve the control performance of the DTP-PMSMs under the open-phase fault, accurate inductances are critical. This paper presents an extended Kalman Filter (EKF) based inductance estimation strategy for DTP-PMSMs with one phase opened. Firstly, the multi-synchronous-rotating frame (MSRF) based DTP-PMSMs modeling under the single open-phase fault is presented. Secondly, the system space-state model and proposed EKF based estimation algorithm considering inverter nonlinearity are presented. Finally, the inductance estimation is performed by experiments under both steady and transient states. The estimation results have been verified by torque measurements which confirm the validity of the proposed method.

Fault-Tolerant Control for Reducing Harmonic Distortion of Dual Three-Phase Permanent Magnet Synchronous Motor

Aiming at the open circuit fault of a dual three-phase permanent magnet synchronous motor, a normalized current method is used for open circuit fault diagnosis. Then, a fault-tolerant control strategy for reducing the harmonic distortion of a dual three-phase permanent magnet synchronous motor is proposed, which is based on current model prediction control and keeps the decoupling transformation matrix unchanged. The fault-tolerant control method based on current model prediction considers the influence of the control quantity on the future state of the system, and effectively reduces the total harmonic distortion. Two fault-tolerant control strategies for the motor are analyzed, with minimizing stator copper consumption and maximizing torque output as control objectives. Through simulation and experiment of fault-tolerant control strategies for a dual three-phase permanent magnet synchronous motor, the results verify the effectiveness and feasibility of the strategy.

Current Collapse Conduction Losses Minimization in GaN Based PMSM Drive

The ever-increasing demands on the efficiency and power density of power electronics converters lead to the replacement of traditional silicon-based components with new structures. One of the promising technologies represents devices based on Gallium-Nitride (GaN). Compared to silicon transistors, GaN semiconductor switches offer superior performance in high-frequency converters, since their fast switching process significantly decreases the switching losses. However, when used in hard-switched converters such as voltage-source inverters (VSI) for motor control applications, GaN transistors increase the power dissipated due to the current conduction. The loss increase is caused by the current-collapse phenomenon, which increases the dynamic drain-source resistance of the device shortly after the turn-on. This disadvantage makes it hard for GaN converters to compete with other technologies in electric drives. Therefore, this paper offers a purely software-based solution to mitigate the negative consequences of the current-collapse phenomenon. The proposed method is based on the minimum pulse length optimization of the classical 7-segment space-vector modulation (SVM) and is verified within a field-oriented control (FOC) of a three-phase permanent magnet synchronous motor (PMSM) supplied by a two-level GaN VSI. The compensation in the control algorithm utilizes an offline measured look-up table dependent on the machine input power.

An Online Compensation Method of VSI Nonlinearity for Dual Three-Phase PMSM Drives Using Current Injection

Compensation of voltage-source-inverter (VSI) nonlinearity is of great importance in parameter identification and position sensorless control method for motor drives. In this letter, a simple online compensation method has been proposed for the dual three-phase permanent-magnet synchronous motor (PMSM) drives. The key is to observe the change of voltage references contained VSI nonlinearity after injecting currents in z1z2-axis purposely. Compared with the existing estimation methods for VSI nonlinearity, the proposed method not only can avoid the tedious and time-consuming offline test for modeling inverter but also can achieve real-time estimation without machine parameters. Moreover, the current injection on z1z2 subspace has a slight influence on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> subspace (the torque subspace) thanks to the multiple decoupling subspaces of dual three-phase PMSM. The experiments have been given to verify the validity of the proposed method.

Control Strategy of Flywheel Energy Storage System Based on Primary Frequency Modulation of Wind Power

As a form of energy storage with high power and efficiency, a flywheel energy storage system performs well in the primary frequency modulation of a power grid. In this study, a three-phase permanent magnet synchronous motor was used as the drive motor of the system, and a simulation study on the control strategy of a flywheel energy storage system was conducted based on the primary frequency modulation of wind power. The speed and current double closed-loop control strategy was used in the system start-up phase, and the power and current double-closed-loop control strategy were used in the power compensation phase. The model reference adaptive control was used to accurately estimate the speed and position of the rotor. The system compensates for the wind power output by using a wind turbine in real-time and conducting simulation experiments to verify the feasibility of the charge and discharge control strategy. At the same time, it can be verified that the flywheel energy storage system has a beneficial effect on wind power frequency modulation.

Fault-tolerant control via four-leg inverter of a full-electric propulsion system for lightweight fixed-wing UAVs

The work deals with the development and the performance characterization of a novel control strategy for the detection, isolation and accommodation of coil faults in a three-phase Permanent Magnet Synchronous Motor (PMSM), used to drive the propeller of a modern lightweight fixed-wing UAV. The health-monitoring algorithms on motor currents (used to detect the open-circuit fault and to activate the control reconfiguration) are based on a slope method, associated to the evaluation of the current phasor trajectory in the Clarke plane. Actually, when an open-circuit fault occurs in PMSM driven by a standard three-leg converter, the typical circular trajectory of the current phasor in the Clarke plane collapses into a linear track and relevant torque ripples are generated. On the other hand, if the PMSM is driven by a four-leg converter, a control reconfiguration can be applied: the fourth leg of the power bridge is in stand-by when the system operates without faults, but it is enabled to regulate the current flowing at the central point of the Y connection of the 3-phase PMSM. The performances of the fault-tolerant algorithms are assessed via detailed nonlinear simulation of the propulsion system (including propeller loads, electrical faults, mechanical transmission compliance, digital signal processing and sensors errors). The results demonstrate that the health-monitoring algorithms and the fault-tolerant control strategies permit to obtain extremely small detection and isolation latencies, and negligible performance degradation in terms PMSM torque.

Harmonic and Vibration Analysis of Dual Three-Phase PMSM with One-Phase Open Circuit Fault

This paper analyzes the harmonics and vibration under different fault-tolerant current control when one-phase winding of dual three-phase permanent magnet synchronous motor (PMSM) is an open circuit fault. Firstly, the dual three-phase load condition subdomain model of breadloaf surface-mounted permanent magnet (PM) PMSM is established. Secondly, the working conditions of an open circuit fault of one-phase winding are set from the perspectives of no fault-tolerant (NFT) control, maximum torque (MT) control, minimum copper loss (MCL) control and single three-phase mode (STPM) control. The torque harmonics and electromagnetic force harmonics of the four working conditions are analyzed. Then, considering the multi-physical field of electromagnetic and structural coupling, the electromagnetic force in the motor air gap acts on the stator core, and the vibration under four different working conditions is calculated and analyzed. Through the comparison between the analytical method and finite element method, the accuracy of the established model is verified. The calculation method is effective and accurate, it can quickly predict the motor performance in case of one-phase open circuit fault of dual three-phase PMSM.

Analysis and Design of Dual Three-Phase Fractional-Slot Permanent Magnet Motor With Low Space Harmonic

There are many space harmonics in the stator magnetomotive force (MMF) of fractional-slot concentrated winding (FSCW). These harmonics will produce high eddy current losses in the permanent magnet (PM), which will reduce motor efficiency and affect motor performance. Aiming at the above problems, the harmonic components of traditional stator MMF are first analyzed in this article, and then, a novel space-shifted unequal-turn winding structure is proposed for dual three-phase fractional-slot permanent magnet synchronous motors (PMSMs). Meanwhile, the sub- and super-harmonics in the stator MMF can be simultaneously eliminated using the proposed winding structure. To verify the effectiveness of the proposed structure, an 18-slot/8-pole motor and a 30-slot/14-pole dual three-phase fractional-slot PMSM with low space harmonic are designed by using the proposed space-shifted unequal-turn winding structure based on the analysis of nine-slot/eight-pole and 15-slot/14-pole motors. Finally, by comparing the finite element analysis (FEA) results, it is verified that the dual three-phase PMSM motor with the proposed structure has smaller eddy current losses in PM and better motor performance.

Design and Implementation of LCL Filter-Based Electric Machine Emulator With Disturbance Compensation

The electric machine emulator (EME), using digital simulation and power electronics to emulate the characteristics of actual machines, can greatly accelerate the testing of electric drives. However, most existing EMEs are based on typical L filter and linear controller, which causes control conflicts and bandwidth limitation. To address this issue, this paper presents an EME based on LCL filter with passive damping for a three-phase permanent magnet synchronous motor. To improve the dynamic emulating accuracy, a dual closed-loop deadbeat predictive current control algorithm is proposed, which is computationally efficient and easy to implement. The system stability is analyzed in the discrete domain, and the parameter constraints of the filter are obtained. Then, two unknown input observers are designed to compensate for the disturbance currents and voltages caused by modeling errors. Moreover, instead of the empirical method, a theoretical one considering the harmonic suppression, bandwidth, stability and resonance is presented for filter design. Finally, the performance of the proposed EME is validated through simulation and experimental results under various conditions such as machine start-up, torque step change, and speed reversal.

Reinforcement learning control method of torque stability of three-phase permanent magnet synchronous motor

Regarding the control strategy of the permanent magnet synchronous motor, the field-oriented control based on the PI controller have the instability of the output torque. In order to stabilize the output torque of the permanent magnet synchronous motor, this paper adopts reinforcement learning to improve traditional PI controller. Finally, in the MATLAB/Simulink simulation environment, a new control method based on reinforcement learning is established. The simulation results show that the reinforcement learning control method used in this paper can improve the stability of the output torque.

Torque-Performance Improvement for Direct Torque-Controlled PMSM Drives Based on Duty-Ratio Regulation

This article proposes a new duty-ratio regulation-based strategy to improve the torque performance for the direct torque control (DTC) of three-phase permanent magnet synchronous motors (PMSMs). The conventional DTC schemes utilize two hysteresis regulators that are hard to be tuned to satisfy proper torque performance for wide speed ranges because of the contrary change in the positive and the negative torque deviations of the converter's voltage vectors with the rotational speed variations. In contrast, the proposed method uses a duty-ratio regulator that considers the operating speed impact on the torque deviation of the active voltage vectors and avoids triggering those of them that produce high torque deviations, therefore reducing the torque ripple of the DTC system. Moreover, it proposes a virtual reference generator to mitigate the steady-state torque error. The proposed method provides enhanced torque control performance, meanwhile maintaining the main advantages of the conventional DTC techniques, including simple structure, fast transient response, and good robustness. The feasibility and effectiveness of the proposed strategy are verified through a detailed comparative assessment with the conventional DTC scheme and two existing duty regulation-based methods using experimental results obtained from a 0.75-kW PMSM drive system.

Current Control System with High-Frequency Signal Injection for Dual Three-Phase Permanent Magnet Synchronous Motor

Current Control System with High-Frequency Signal Injection for Dual Three-Phase Permanent Magnet Synchronous Motor

Intelligent Permanent Magnet Motor-Based Servo Drive System Used for Automated Tuning of Piano

This paper presents an intelligent permanent magnet synchronous motor-based servo drive system used in automated piano tuning applications. The permanent magnet synchronous motor-based drives are able to improve the accuracy of the piano tuning process in comparison with the traditional direct-current motor-based and step motor-based servo drives. To explain the techniques, firstly, the structure and principles of the automated piano tuning devices with a surface-mounted permanent magnet synchronous motor-based drive system integrated are introduced, illustrating that it is feasible to implement the proposed piano tuning strategy. Secondly, the piano tuning devices have two functions: low-speed rotation and position holding. To ensure that the surface-mounted permanent magnet synchronous motor can rotate stably over the low-speed range with strong anti-interference capacity, a double closed-loop speed-regulation-based control scheme is employed. And to ensure high position control performance, a fuzzy-adaptive triple closed-loop position-regulation-based control scheme is employed. It terms of the control schemes, it deserves to be mentioned that main contributions include, firstly, the parameters of the proportional integral controllers in the double closed-loop speed-regulation structure is tuned relying on both stability and bandwidth analyses. Then, a fuzzy-adaptive proportional integral controller is specially-designed for the triple closed-loop position-regulation to adapt to the piano tuning applications. Simulation is conducted on a 20 rpm three-phase permanent magnet synchronous motor servo drive-based piano tuning system to validate the proposed piano tuning method and to verify the proposed control techniques.

Sensorless Fault-Tolerant Control of Dual Three-Phase Permanent Magnet Synchronous Motor

Dual three-phase permanent magnet synchronous motors (DTPMSM) are used in the steer-by-wire system of electric vehicles that require high reliability. Multiple faults should be considered for the steering system, such as open-circuit faults and speed sensor faults. However, the current speed sensorless control methods of the dual three-phase motor are mainly derived from the promotion of the three-phase motor. They fail when an open-circuit fault occurs, leading to the failure of fault-tolerant control. Researchers have noticed this problem and proposed many methods, but they are very complicated and computationally intensive. This paper proposes one type of improved model reference adaptive system (MRAS). By adding certain fault-related restraints to the output of the adjustable model, speed sensorless control can automatically fit the open-circuit fault and estimate accurately even if an open-circuit fault occurs, which makes sure the whole system continues to operate. Simulation results are presented that contain normal operation, open-circuit fault operation, fault-tolerant control operation, and the whole process from start to fault-tolerant operation. The results show that no matter what period the motor is in, the improved speed sensor can accurately estimate the motor speed and position. The improved model reference adaptive system is significant for improving the reliability of the motor steering system and ensuring the safety of people and property.

Fault-Tolerant Control of a Three-Phase Permanent Magnet Synchronous Motor for Lightweight UAV Propellers via Central Point Drive

This paper deals with the development and the performance characterization of a novel Fault-Tolerant Control (FTC) aiming to the diagnosis and accommodation of electrical faults in a three-phase Permanent Magnet Synchronous Motor (PMSM) employed for the propulsion of a modern lightweight fixed-wing UAV. To implement the fault-tolerant capabilities, a four-leg inverter is used to drive the reference PMSM, so that a system reconfiguration can be applied in case of a motor phase fault or an inverter fault, by enabling the control of the central point of the three-phase connection. A crucial design point is to develop Fault-Detection and Isolation (FDI) algorithms capable of minimizing the system failure transients, which are typically characterized by high-amplitude high-frequency torque ripples. The proposed FTC is composed of two sections: in the first, a deterministic model-based FDI algorithm is used, based the evaluation of the current phasor trajectory in the Clarke’s plane; in the second, a novel technique for fault accommodation is implemented by applying a reference frame transformation to post-fault commands. The FTC effectiveness is assessed via detailed nonlinear simulation (including sensors errors, digital signal processing, mechanical transmission compliance, propeller loads and electrical faults model), by characterizing the FDI latency and the post-fault system performances when open circuit faults are injected. Compared with reports in the literature, the proposed FTC demonstrates relevant potentialities: the FDI section of the algorithm provides the smallest ratio between latency and monitoring samples per electrical period, while the accommodation section succeeds in both eliminating post-fault torque ripples and maintaining the mechanical power output with negligible efficiency degradation.

On‐line dead‐time compensation method for dual three phase PMSM based on adaptive notch filter

For the dual three-phase permanent magnet synchronous motor(dual-PMSM), the deadtime can introduce fifth and seventh current harmonics, and they are only constrained by the small stator leakage impedance, which means even if there are only small fifth and seventh voltage harmonics, the resulting fifth and seventh current harmonics will be very large. The harmonic current will make an increment of the system loss, thus lead to an reduce of the efficiency of the speed control system. This paper proposes a harmonic current suppression strategy for dual-PMSM based on least mean square (LMS) adaptive notch filter. This strategy suppresses the fifth and seventh harmonic currents by introducing four LMS adaptive notch filters in the subspace. The proposed algorithm has good dynamic performance and is insensitive to motor parameters that are offset within a certain range. The effectiveness of proposed method is verified by a set of comparative simulations and experiments.

A novel high torque density six‐phase axial‐flux permanent magnet synchronous motor with 60° phase‐belt toroidal winding configuration

The three-phase permanent magnet synchronous motor (three-phase PMSM) has gained much popularity in many applications due to its various advantages. In addition, due to the good fault tolerance, simple inverter circuit structure and high torque density, the six-phase PMSM has better prospects than three-phase PMSM in biomedical devices, electric vehicles and other fields with high reliability requirements. In this study, a six-phase axial-flux PMSM inherently without cogging torque is proposed to improve torque density, which equips the 60° phase-belt toroidal winding (60°TW) and slotless stator core. Based on the same effective volume, permanent magnet material, power grade and the other major motor parameters, two six-phase PMSMs with 30° phase-belt toroidal winding (30°TW) and 60°TW are designed, respectively. The armature reaction field, air gap magnetic density, back-electromotive force, output torque, loss characteristic and torque-speed characteristic are compared by using three-dimensional (3D) finite-element models in detail. Finally, the experimental test is carried out using the prototype of three-phase PMSM with 120° phase-belt toroidal winding. The experimental results indirectly verify the feasibility of 60° phase-belt toroidal winding and correctness of 3D FEM. The 3D FEM analysis results are presented to show that torque density of the proposed six-phase PMSM with 60°TW is improved in comparison to the six-phase PMSM with 30°TW. Index Terms—60° phase-belt toroidal winding, axial flux, six-phase permanent magnet synchronous motor, torque density