Fault-tolerant Permanent Magnet Motor Research Articles

Design and Analysis of a High Speed Wet-type Fault Tolerant Permanent Magnet Motor Considering Oil Frictional Loss for Aerospace Electro-Hydrostatic Actuator Application

Design and Analysis of a High Speed Wet-type Fault Tolerant Permanent Magnet Motor Considering Oil Frictional Loss for Aerospace Electro-Hydrostatic Actuator Application

Design and Analysis of a Five-phase Flux-Intensifying Fault-Tolerant Permanent-Magnet Motor With Active Sensorless Strategy Under Multimode Operation

In this paper, a new flux-intensifying fault-tolerant permanent magnet synchronous motor (FI-FTPMSM) is proposed to improve sensorless operating capacity under multimode operation including fault conditions. Most previous studies regarding fault-tolerant motors aim to improve fault-tolerant capability but suffer the saliency characteristic problem, which is unfavorable for sensorless control. In this study, an active sensorless strategy is developed by considering the sensorless operating capability under multimode operation in the motor design stage. Based on this novel idea, a new FI-FTPMSM with a high inverse saliency ratio is designed. By carefully choosing slot-pole combination, subtly setting <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis magnetic barrier shape, and improving air gap waveform, the superior inverse saliency characteristic is obtained, which effectively improves the dynamic and steady-state sensorless operating performance. Through simulation analysis and experimental tests, the rationality and validity of the proposed strategy are verified.

Design and analysis of three-phase FTPMM for Partial Energy Electric Pump System

As the core component of the More Electric Aircraft (MEA) hydraulic system, the partial energy Electric Pump System (EPS) determines the performance of the hydraulic servo device. In this paper, a three-phase Fault-Tolerant Permanent Magnet Motor (FTPMM) for the partial energy EPS is proposed. The three-phase FTPMM drive system for the partial energy EPS can replace the traditional engine pump source hydraulic system, which can save costs, reduce weight and volume, and improve efficiency. Moreover, it can solve the problem of high reliability application of the motor drive system in aeroengine. The slot-pole combinations and centrifugal height are designed and analyzed for the proposed three-phase FTPMM, and a prototype model was produced based on this. Finally, the basic electromagnetic performance and fault-tolerant performance of three-phase FTPMM are verified through simulation and experiment. The results show that the proposed three-phase FTPMM has good fault isolation and suppression capabilities under winding fault.

A Simplified LPTN Model for a Fault-Tolerant Permanent Magnet Motor under Inter-Turn Short-Circuit Faults

This paper proposes a simplified lumped parameter thermal network (LPTN) model for thermal analysis under the inter-turn short-circuit (SC) faults of a five-phase fault-tolerant permanent magnet (PM) motor for electric vehicles. The proposed model can consider circumferential heat transfer, variable copper loss, and uneven loss distribution. Firstly, an analytical calculation formula of inter-turn SC current is proposed to separate the copper loss of SC turns from electromagnetic simulation, and the accuracy of the formula is verified by finite element analysis (FEA). Secondly, a simplified LPTN model is proposed, the calculation formulas of the thermal resistance are given, and the simplified principle is explained. By comparing the results of different simplifications, it is found that the error between the simplified model and the original model is small. Finally, the proposed model is verified by experiments. The results show that the simplified model can achieve not only a high calculation speed but also a high accuracy. Moreover, the proposed model is applicable to all cases of asymmetrical temperature distribution.

Design and optimization of dual-winding fault-tolerant permanent magnet motor for aviation fuel pump applications

With the development of electric drive technology, the integrated electric engine fuel pump on the aircraft has many potential advantages such as lighter weight, smaller volume and simpler configuration. This paper aims to optimize the parameters of the existing dual-winding fault-tolerant permanent magnet motor (DWFT-PMM) which merges the advantages of permanent magnet (PM) motor with high efficiency and dual-winding motor with strong fault-tolerance. The existing DWFT-PMM is designed with a rated speed of 5000 rpm, rated power of 10 kW and the cooling mode is natural air cooling. However, in practical application, because the aviation fuel pump motor needs higher speed and better heat dissipation performance. This paper mainly focuses on the design and optimization of the existing DWFT-PMM aviation fuel pump motor, and compares and analyzes it through simulation and experiment. The comparative analysis results before and after optimization are given in terms of moment, no-load back EMF in simulation and experiment, etc. Finally, the simulated and experimental results show that about 20% higher rated speed, 5.43% higher torque density, 35.85% smaller volume and better heat dissipation can be obtained for the optimized DWFT-PMM when compared with existing DWFT-PMM.

Remedy Strategy for Five-Phase FTPMMs Under Single-Phase Short-Circuit Fault by Injecting Harmonic Currents From Third Space

This article proposes a new fault-tolerant control for five-phase fault-tolerant permanent-magnet motors under single-phase short-circuit fault. In the proposed method, the effect on torque performance caused by a short-circuit fault is attributed into two parts: the loss of the short-circuited phase, which is equivalent to a phase open-circuit fault, and the resultant short-circuit current. The remedial action for loss of a phase is realized in the fundamental space, while the torque ripple caused by the short-circuit current is compensated by the harmonic currents in the third space. To decouple the control of the fundamental and third space, the reduced-order Clarke and Park transformation matrixes for the two spaces are obtained separately under single-phase short-circuit fault. Afterward, the fundamental currents with minimum joule losses or equal joule losses for loss of a phase, and the harmonic currents in the third space for torque ripple reduction are derived. Hence, the proposed method can realize torque ripple-free operation under single-phase short-circuit fault. Finally, the effectiveness of the proposed method is verified by experimental results under various operational conditions.

A Generalized Open-Circuit Fault-Tolerant Control Strategy for FOC and DTC of Five-Phase Fault-Tolerant Permanent-Magnet Motor

A generalized fault-tolerant control (FTC) strategy for the field-oriented control (FOC) and direct torque control (DTC) of five-phase fault-tolerant permanent magnet (FPFTPM) motors under various open-circuit faults is presented in this article. Most previous studies regarding FTC target a specific primary control algorithm and involve different reduced-order transformation matrices and additional current controllers, which increase the complexity of the entire drive system. In this study, a solution to the aforementioned problems is devised by developing optimal fault-tolerant voltages, which are derived from fault-tolerant mechanism analysis and steady-healthy design. Because the coordinate transformation need not be changed and additional voltage compensation is not required, a minimal control drive system reconfiguration under various open-circuit faults can be achieved to avoid accommodating the change of the primary control algorithm. The proposed control strategy not only improves the torque performance and dynamic response under healthy and fault conditions, but also adapts to both FOC and DTC. Experimental results for a 2 kW FPFTPM motor prototype are provided to evaluate the proposed strategy.

Simplified Universal Fault-Tolerant Direct Torque Control of FPFTPM Motor With Steady-Healthy Design Under Open-Circuit Fault

A simplified universal fault-tolerant direct torque control (FTDTC) strategy of five-phase fault-tolerant permanent magnet (FPFTPM) motors under various open-circuit faults is presented in this article. In the proposed FTDTC strategy, the fault-tolerant currents are derived from the fault-tolerant mechanism analysis and steady-healthy design. The problems of existing FTDTC strategies that need to change coordinate transformation and add extra voltage compensation can be overcome. Thus, the minimal control drive system reconfiguration under different faults can be realized in the real sense. Especially, the steady-healthy controller is designed to suppress the torque ripples and achieve the high-quality torque given even under fault operation conditions; then, it is not necessary to set a special voltage vector or add a PI controller. Furthermore, the FTDTC strategy is improved to be realized under the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> coordinate system based on the flux adaption. Hence, the reduced <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current under different operating conditions, including fault conditions, can be ensured. This FTDTC strategy without any control reconfiguration is proposed under the premise of ensuring good performance during both healthy and fault operations. Finally, the simulation and experimental results for an FPFTPM prototype are offered to verify the feasibility of the proposed strategy.

Position Estimation of Fault‐Tolerant Permanent Magnet Motor in Electric Power Propulsion Ship System

The electric power propulsion is becoming the important development direction of ship propulsion technology recent years, as it is conducive to the realization of automation, intelligence, reduced noise, enhanced propulsion efficiency, high power density, flexible arrangement, and energy saving. The good fault‐tolerant capacity and robustness of the fault‐tolerant permanent magnet motor (FTPMM) make it a potentially highly effective and economical propulsion motor in the electric power propulsion ship than other alternatives. In this paper, the structure and mathematical model of FTPMM are analyzed and the improved sliding mode observer (SMO) is constructed according to the deviation between the observed currents and actual currents. Combined with model reference adaptive control (MRAC) method and the phase‐lock loop (PLL), the switch function is replaced by the continuous Sigmoid function to reduce the chattering and finally the rotor position estimated accuracy is improved. When the motor winding open‐circuit and short‐circuit fault occur, the current vector fault‐tolerant control strategy is introduced into the improved SMO algorithm, and the rotor position is estimated accurately under faulty conditions. Finally, the proposed improved SMO position estimation algorithm under healthy and faulty conditions is verified in Matlab/Simulink. The FTPMM position sensorless technology would play a critical role in the electric power propulsion ship, and may have a profound impact on the high‐performance advanced ships and green shipping industry as well. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Study of rotor position estimation algorithm based on back-EMF voltage for dual-winding fault-tolerant permanent magnet motor

An improved position estimation of the sensorless control system with online parameter identification based on back-Electromotive Force (EMF) voltage is presented for the dual-winding fault-tolerant permanent magnet motor (FTPMM). In this control system, the rotor position is estimated by the flux linkage and the back-EMF which are generated by each phase winding. By introducing phase-locked loop technology to compensate the steady-state error of the system and online identification of motor parameters which is using the least-square method with forgetting factor, more accurate position estimation can be obtained. The current vector fault-tolerant control strategy improves the fault tolerance of the system and makes it strong robust stability. The simulation results have shown that the accurate position data can be acquired both under healthy condition and single-phase fault condition. Then, the hardware experimental results show the feasibility and validity of the proposed algorithm.

SVPWM technique for common-mode voltage elimination of dual-winding fault-tolerant permanent magnet motor drives

A new space vector pulse-width modulation (SVPWM) technique to eliminate common-mode voltage (CMV) is proposed for a dual three-phase inverter fed-dual-winding fault-tolerant permanent magnet motor (FTPMM) drive. In general, since both the PWM module-1 of an inverter-1 drive and the PWM module-2 of an inverter-2 drive adopt the conventional SVPWM (CSVPWM) technique, two identical CMVs are generated in the drives. Each of the CMCs generated by the CMVs flows through the stray capacitances between the stator windings and the motor frame. These currents flow into the ground of the drive, where they are combined. Hence, in the proposed technique, each of the PWM modules adopts the remote-state PWM (RSPWM)2A and RSPWM2B. As a result, two CMVs with same absolute values and opposite polarities are generated at every switching period, and the corresponding generalized total CMV of the dual-winding FTPMM drive always becomes zero. Analytical and experimental results are provided to verify the validity of the proposed technique.

Short-Circuit Fault-Tolerant Operation of Dual-Winding Permanent-Magnet Motor Under the Four-Quadrant Condition

In this paper, a short-circuit fault-tolerant operation control strategy of dual-winding permanent-magnet motor (DWPMM) under the four-quadrant condition for electrical flight surface actuator application is proposed and investigated. By the comparative analysis of the current fault-tolerant permanent-magnet motor drive system, it can be concluded that the DWPMM drive system is suitable for electrical flight surface actuator application. However, the current DWPMM drive system lacks the research on short-circuit fault-tolerant operation under the four-quadrant condition. Then, the electrical flight surface actuator system based on the DWPMM and short-circuit fault-tolerant operation control strategy under the four-quadrant condition is proposed and investigated. The experimental results show that the electrical flight surface actuator system based on the DWPMM can achieve the high performance of the four-quadrant fault-tolerant control with short-circuit fault under the four-quadrant operational condition.

Design and optimization of dual-winding fault-tolerant permanent magnet motor

To improve the performance of the traditional fault-tolerant permanent magnet (PM) motor, the design and optimal schemes of dual-winding fault-tolerant permanent magnet motor (DWFT-PMM) are proposed and investigated. In order to obtain small cogging torque ripple and inhibiting the short-circuit current, the air gap surface shape of the PM and the anti short-circuits reactance parameters are designed and optimized. According to the actual design requirements of an aircraft electrical actuation system, the parameters, finite element analysis and experimental verification of the DWFT-PMM after optimal design are presented. The research results show that the optimized DWFT-PMM owns the merits of strong magnetic isolation, physics isolation, inhibiting the short circuit current, small cogging torque ripple and high fault tolerance.

Current Vector Control Strategy in a Dual-Winding Fault-Tolerant Permanent Magnet Motor Drive

The dual-winding fault-tolerant permanent magnet motor (FTPMM) incorporates the merits of high power density and high efficiency of the permanent magnet (PM) motor and high fault-tolerance of the single FTPMM. In this paper, a three-phase dual-winding FTPMM is investigated to study fault-tolerant control strategy. To generate the same output torque and reduce the torque ripples under healthy, winding open-circuit fault and winding short-circuit fault conditions, the current vector fault-tolerant control strategy is proposed. The currents under one-phase open-circuit and short-circuit failure conditions are calculated in detail. The torque ripples and copper loss are obtained and compared with other different fault-tolerant strategies. The simulation model of the dual-winding FTPMM drive is built and the hardware experimental platform based on TMS320LF28335DSP is developed. The simulation and experimental results have proved that the proposed dual-winding FTPMM has good operation performance under healthy condition, and the proposed vector fault-tolerant control strategy can compensate the function of faulty phase to obtain the invariable torque with small ripples under open-circuit and short-circuit fault conditions, which verified the proposed current vector fault-tolerant control strategy correct and valid.

Decoupling control of a five-phase fault-tolerant permanent magnet motor by radial basis function neural network inverse

This paper proposes a new decoupled control for a five-phase in-wheel fault-tolerant permanent magnet (IW-FTPM) motor drive, in which radial basis function neural network inverse (RBF-NNI) and internal model control (IMC) are combined. The RBF-NNI system is introduced into original system to construct a pseudo-linear system, and IMC is used as a robust controller. Hence, the newly proposed control system incorporates the merits of the IMC and RBF-NNI methods. In order to verify the proposed strategy, an IW-FTPM motor drive is designed based on dSPACE real-time control platform. Then, the experimental results are offered to verify that the d-axis current and the rotor speed are successfully decoupled. Besides, the proposed motor drive exhibits strong robustness even under load torque disturbance.

Nonlinear Model Suitable for the Offline Cosimulation of Fault-Tolerant PM Motors Drives

This paper presents a dynamic model suitable for accurate cosimulation of fault-tolerant permanent-magnet motor drives featuring independent-phase structure. The model is developed in a circuital form where the usual inductive parameters and back electromotive force coefficient are replaced by current and rotor position dependent functions, so that the exact electromagnetic nature and geometry of the machine are accounted over the large flux-current operating range. The model functions are precomputed by a finite element method analysis of a single phase of the machine, once the magnetic independence among the phases has been verified. Then, the circuital model is solved by a dynamical simulator which implements also the drive system, converter, and control, following on the offline cosimulation approach. The proposed model is validated by experiments carried on a fault-tolerant five-phase permanent-magnet motor-drive for aeronautical application, controlled by the brushless dc technique. The results show that the modeling solution is capable to simulate the motor dynamics with a high degree of accuracy, and can be used for an effective rapid prototyping of fault-tolerant drives.

Performance Study of Three-Phase Fault-Tolerant Permanent Magnet Motor Drive for Marine Propulsion System Based on Structure Design

The fault-tolerant permanent magnet motor (FTPMM) drives are desired in electric ship propulsion systems. The winding inductance, the sinusoidal degree of the back electromotive force (back-EMF) waveform, and the total harmonic distortion (THD) of the cogging torque are the important factors that affect the operating performance of FTPMM drive. A performance optimization of a three-phase FTPMM by varying motor structural parameters is presented in this article. By analyzing mathematical formulas, notch parameters and permanent magnet size are designed optimally to obtain large winding self-inductance, good sinusoidal degree of back-EMF, and low THD of cogging torque. The finite element verification in Ansoft proves selected parameters reasonable. Finally, an experimental prototype motor is specifically built according to determined parameters; and good performances, magnetic isolation, and fault-tolerant capacity can be guaranteed.

Fault‐tolerant control for a dual‐winding fault‐tolerant permanent magnet motor drive based on SVPWM

The dual-winding fault-tolerant permanent magnet motor (FTPMM) drive can overcome the shortcomings of single FTPMM and dual-redundant FTPMM drive and further improve the fault-tolerant capability of motor drives. The vector control technique based on voltage space vector pulse width modulation (SVPWM) can reduce switching frequency and improve the dynamic performances of the motor drive. In this study, the structure and principle of vector control system based on SVPWM for a dual-winding FTPMM drive was introduced. The distribution of voltage space vectors was analysed and the vector control strategies under healthy and one-phase open-circuit faulty conditions were proposed in which the magnetomotive force was kept constant with the minimum copper loss. The simulation and experimental results are provided to verify the validity of the proposed fault remedial strategy based on SVPWM technique.

A Novel Five-phase Double-Stator Tubular Fault-tolerant Flux-Modulation Permanent Magnet Motor

Tubular permanent magnet motors have been applied to many direct drive systems. This paper proposes a novel double-stator tubular fault-tolerant flux-modulation permanent magnet motor for an electromagnetic suspension system. The key of the proposed motor is the special double-stator and flux-modulation structure. The double-stator structure can make best use of the inner space of the motor. The flux-modulation structure is based on the magnetic gear effect, which can use effective harmonic components of magnetic field. Thus, the thrust force density is improved. Additionally, the idea of single-layer fractional-slot concentrated windings and fault-tolerant teeth is used to enhance fault-tolerant capability. The electromagnetic performance is analyzed by using the time-stepping finite-element method, verifying the effectiveness of the theoretical analysis.

Comparison of Two SVPWM Control Strategies of Five-Phase Fault-Tolerant Permanent-Magnet Motor

Five-phase fault-tolerant permanent-magnet motors incorporate the merits of high-efficiency and high fault-tolerant capability. By adopting the fault-tolerant control technique, these motors can continue operating even fault occurs. This paper proposes two space vector pulse-width modulation (SVPWM) control strategies, namely the symmetric one and the asymmetric one. The novelty of the proposed SVPWM control strategies includes two parts. One is that voltage vector locations in both SVPWM strategies are reconfigured based on a new vector space diagram. Another is that the process of switching vector calculation under fault is similar to that under healthy condition. A five-phase fault-tolerant permanent-magnet motor drive is developed and the proposed fault-tolerant control strategies are evaluated in terms of the torque, voltage, current waveforms, and total harmonic distortion. Simulated and experimental results are provided to verify the effectiveness of the theoretical analysis.