Three-phase Permanent Magnet Synchronous Motor Research Articles

Efficiency improvement of dual three-phase permanent magnet synchronous motor using modified switching table DTC for electric ship propulsion

A direct torque control using a classical switching- table ST-DTC can be used to control the torque and thus the speed of Dual Three-Phase Permanent Magnet Synchronous Motor (DTP-PMSM). The principle is based on direct application of control sequence by using two hysteresis regulators and a switching table. A large stator current containing low order harmonics is produced during the application of the classic ST-DTC technique, this leads to higher losses affecting the efficiency of the machine. To allow a reduction of these harmonics a modified switching-table approach based DTC technique is examined. Indeed, an improved ST-DTC strategy, which consist of replacing the vectors of the classical table with synthetic vectors, is discussed. The simulation results confirm the validity of the selected strategy.

An open-circuit fault diagnosis method for PMSM drives using symmetrical and DC components

In this paper, a diagnostic method based on symmetrical and DC components is presented for multiple open-circuit faults (OCFs) in a three-phase permanent magnet synchronous motor drive. The remaining phase currents under faulty situations are theoretically analyzed based on the Fourier series method and the mechanism of torque generation. To evaluate the asymmetry and discriminate fault types, the magnitude ratio of the positive sequence to the negative sequence of phase currents is designed as a fault detection index. Thereafter, the DC components of the phase currents in different reference frames are utilized to locate faults. Specifically, the polarities of the DC contents in the natural reference frame are utilized to locate a single OCF and two OCFs in different legs. Two OCFs in the same leg are diagnosed by evaluating the signs of the phase currents in the dq reference frame with a negative rotating direction. The simulated and experimental results validate the effectiveness of the developed method in fault detection and robustness against operating point and motor parameter variations.

Advances in Fault Diagnostics and Post‐Fault Operation of Electrical Drives

Advances in Fault Diagnostics and Post‐Fault Operation of Electrical Drives

Motor Current Signature Analysis-based Non-invasive Recognition of Mixed Eccentricity Fault in Line Start Permanent Magnet Synchronous Motor

— In this study, a cost-effective and non-invasive detection strategy is proposed for three-phase line start permanent magnet synchronous motor (LSPMSM) under mixed eccentricity fault using motor current signature analysis. In this respect, theory of air gap magnetic field in eccentric LSPMSM is presented. The detection strategy is examined through modeling and experimental studies. Two-dimensional time stepping finite element method is employed to calculate the motor parameters. Effects of mechanical load and fault severity on eccentric LSPMSM are also investigated. Different fault-related components are scrutinized and the most effective features are identified for this new type of electrical motor. The results indicate that amplitudes of fault-related components at rotor frequency are precise for early detection of mixed eccentricity in LSPMSM. Finally, an efficient frequency pattern as well as detection criterion is specified.

Fault-tolerant torque control of a three-phase permanent magnet synchronous motor with inter-turn winding short circuit

System reliability and fault tolerance are very important features in safety-critical applications with electric motors. An inter-turn winding short circuit is one of the most common fault cases, which makes the fault-tolerant torque control a crucial task. In this paper, a novel fault-tolerant model-based torque control strategy for a three-phase permanent magnet synchronous motor (PMSM) with an inter-turn winding short circuit is proposed. The control scheme has a cascaded structure with a one-step model-predictive control (MPC) in the outer loop and subordinate PI current controllers. The control strategy is based on a magnetic equivalent circuit (MEC) model. Thus, magnetic saturation and non-fundamental wave behavior of the PMSM are systematically taken into account in contrast to existing works on this topic in the literature. The parameters of the inter-turn winding short circuit are identified by a model-based fault-identification method. The high torque control accuracy of the proposed control scheme is proven by a number of different experiments performed on a test stand.

Fault-Tolerant Control of Dual Three-Phase PMSM Drives With Minimized Copper Loss

In this article, a minimum-copper-loss fault-tolerant control scheme is proposed for open-phase fault and open-switch fault of dual three-phase permanent magnet synchronous motor (DT-PMSM) drives. Both the winding configurations of isolated neutral points and connected neutral points are studied in this article. In conventional minimum-copper-loss fault-tolerant control schemes, the constraints of sinusoidal phase currents result in insufficient copper-loss reduction. Different from them, the current references with the theoretically lowest copper losses are first derived and applied for different fault cases of DT-PMSM drives without using any unnecessary constraints in the proposed fault-tolerant control scheme. Thus, all phase currents in the proposed minimum-copper-loss fault-tolerant control scheme are optimized to be nonsinusoidal waveforms. Besides, the copper losses are further reduced by fully utilizing the remaining healthy switch in the faulty inverter leg for the open-switch fault of DT-PMSM drives with the proposed scheme. It has been theoretically and experimentally proved that the proposed fault-tolerant control scheme can reduce copper losses than all existing fault-tolerant schemes for both open-phase fault and open-switch fault in typical two-level voltage-source-inverter-fed DT-PMSM drives.

Direct Harmonic Current Control Scheme for Dual Three-Phase PMSM Drive System

The performance of model predictive control mainly depends on the accuracy of model and parameters, such as the back electromotive force (EMF) harmonics in dual three-phase permanent magnet synchronous motors (PMSMs). However, the back EMF harmonics would vary with the operation conditions. Thus, the parameter mismatches in the harmonic subspace would be inevitable. In this article, a direct harmonic current control scheme is proposed to provide further harmonic current suppression under parameter mismatches in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> subspace. First, deadbeat control concept is applied to calculate the reference voltage in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> subspace. This reference voltage vector is utilized to generate a group of control sets with different voltage vectors in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> subspace. Then, a slide mode control scheme is provided to deal with the inaccurate parameters in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> subspace. The reference voltage vector in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> subspace is obtained with this slide mode control scheme without the remaining inductance parameters. Third, a two-step modulation method and cost function are discussed to further suppress the harmonic currents. The control sets generated by deadbeat control are optimized with the cost function. Moreover, a switching pattern with fixed switching frequency is proposed in this section. Finally, experimental results verify that proposed control scheme could further suppress the harmonic currents.

An Online Flux Estimation for Dual Three-Phase SPMSM Drives Using Position-Offset Injection

The rotor flux linkage of permanent-magnet synchronous motor (PMSM) is of great importance for monitoring and high-performance control. However, most of the existing online estimation methods need prior knowledge of other PMSM parameters such as stator resistance and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> axis inductance, which are difficult to realize in the rank-deficient models of electrical machines. This article proposes a simple online estimation method of rotor flux linkage for the dual three-phase surface-mounted PMSM (SPMSM) drives with the assistance of injected position offset. The independent estimation model has been developed for the rotor flux linkage by appropriate setting of positon offset between two sets of three-phase windings of dual three-phase SPMSM drives. The proposed method not only has little influence on the output torque and high signal-to-noise ratio for observation, but also offers the superior performance in estimation accuracy irrespective of the influence of VSI nonlinearity. In addition, the proposed position-offset-based method is suitable for the full-speed region including the field-weakening operation. Finally, comprehensive experimental results are presented to verify validity of the proposed method under different working conditions.

Interleaved Model Predictive Control for Three-Level Neutral-Point-Clamped Dual Three-Phase PMSM Drives With Low Switching Frequencies

In this article, the control strategy is studied for the neutral-point-clamped three-level inverter-fed dual three-phase permanent-magnet synchronous motor (PMSM) drive with low switching frequencies. An interleaved finite-control-set model predictive control (MPC) scheme is proposed, where a two-layer MPC is designed to solve the multiobjective optimization problem. The two sets of windings in PMSM are sampled and controlled in an interleaved way so that the control delay and the prediction horizon of the drive system are reduced by half. Moreover, the proposed interleaved control scheme increases the equivalent sampling and control frequency from the perspective of the whole drive system, and thus provides better steady-state performance and dynamic performance. With the switching states of one inverter remaining unchanged, the cross traversal of vector candidate sets between two sets of windings is avoided, and the computational burden can be reduced effectively. Experimental results are given to verify the validity and effectiveness of the proposed interleaved control scheme.

Development of Three-Phase Permanent-Magnet Synchronous Motor Drive with Strategy to Suppress Harmonic Current

This study aimed to develop a three-phase permanent-magnet synchronous motor drive system with improvement in current harmonics. Considering the harmonic components in the induced electromotive force of a permanent-magnet synchronous motor, the offline response of the induced electromotive force (EMF) was measured for fast Fourier analysis, the main harmonic components were obtained, and the voltage required to reduce the current harmonic components in the corresponding direct (d-axis) and quadrature (q-axis) axes was calculated. In the closed-loop control of the direct axis and quadrature axis current in the rotor reference frame, the compensation amount of the induced EMF with harmonic components was added. Compared with the online adjustment of current harmonic injection, this simplifies the control strategy. The drive system used a 32-bit digital signal processor (DSP) TMS320F28069 as the control core, the control strategies were implemented in software, and a resolver with a resolver-to-digital converter (RDC) was used for the feedback of angular position and speed. The actual measurement results of the current harmonic improvement control show that the total harmonic distortion of the three-phase current was reduced from 5.30% to 2.31%, and the electromagnetic torque ripple was reduced from 15.28% to 5.98%. The actual measurement results verify the feasibility of this method.

Comparative analysis of the operating performance, magnetic field, and temperature rise of the three‐phase permanent magnet synchronous motor with or without fault‐tolerant control under single‐phase open‐circuit fault

In the power transmission system, the semiconductor device in the inverter is one of the main fault points. When the open- or short-circuit fault occurs in the semiconductor device, the motor can be turned into the operation with open-phase fault. To take into account the non-ideal factors existing in the calculation, this study establishes a system-level calculation model including the permanent magnet synchronous motor (PMSM), inverter, and different control strategies, which is used to analyse the operating performance of the PMSM with or without fault-tolerant control under single-phase open-circuit fault. In addition, based on the finite element method, the current fault characteristic and the change of the internal magnetic field distribution before and after the fault are studied, and the temperature rise of the PMSM with and without fault-tolerant control is compared. The aim of this study is to compare the operating performance of the three-phase PMSM under two common fault conditions, and quantitatively give the variation range of magnetic flux density and temperature rise. The theoretical analysis in this study is verified by building a systematic experiment platform.

Multisector Three-Phase PMSM Drive System With Low-Frequency and High-Frequency PWM Noise

Multi-sector three-phase permanent magnet synchronous motors (PMSMs) possess better performance against traditional motors. With the application of pulse width modulation (PWM) and consideration of switching losses, ear-piercing high-frequency noise from the motors has become unacceptable in sensitive environments. A drive topology covering K paralleled inverters with special open-winding magnetically coupled inductors is presented to feed the multi-sector motor. In this paper, a comprehensive suppression strategy with low-frequency compensation based on an adaptive-linear-neuron algorithm is proposed to eliminate the PWM noise around odd carrier multiples, and reduce the harmonics near even carrier multiples under 2K multiple through the impedance of the coupled inductors. Apart from the analysis of the elimination principle and advantages of the drive system, the simulation verification is also conducted. Finally, the detailed experimental results have verified the effectiveness of the proposed strategy in a two-sector three-phase PMSM drive system.

Virtual-Vector-Based FCS Model Predictive Current Control with Duty Cycle Optimization for Dual Three-Phase Motors

This paper presents an improved finite control set model predictive current control (FCS-MPCC) based on virtual vectors with duty cycle control for dual three-phase permanent magnet synchronous motor (DTP PMSM) drives. Virtual vectors synthesized by two basic voltage vectors of the inverter are introduced to suppress the harmonic current by the vector space decomposition (VSD) model. And the virtual vectors with the optimal duty cycle can be obtained by duty cycle control using zero vectors to generate a fixed switching frequency. Moreover, a simple scheme of centrosymmetric switching patterns is presented for the realtime implementation. In this way, the performance of current tracking is improved while the computational burden is reduced. Finally, results of simulation analysis and DSP test for the three different strategies are given to verify the validity of the proposed strategy.

Direct Modulation Pattern Control for Dual Three-Phase PMSM Drive System

The additional harmonic currents in multiphase permanent magnet synchronous motors (PMSMs) have been widely discussed and suppressed by the virtual vectors (VVs). However, the concept of VVs would result in an increasing in the switching frequency and losing the controllability in the harmonic subspace. In this article, a novel direct modulation pattern control (DMPC) method is proposed to provide the further discussion on the lower switching frequency and the better harmonic current suppression. First, a deadbeat control concept is applied to calculate the reference voltage vectors in torque production. In dual three-phase PMSM, there are several switching patterns which could generate the reference voltage vector. The designs of these switching patterns are determined according to the demand. In fact, two design concepts under the structure of DMPC is proposed. One is called the low switching frequency design. The control sets of this design is several switching patterns with only one switching signal. Another is called the low THD design. The control sets of this design is two switching patterns with opposite harmonic voltage vectors. Second, the influence of these different switching patterns in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> currents is optimized by a cost function. Actually, there are two types of cost function. One is a multiobjective cost function, which is designed to regulate both the amplitude of switching patterns and suppress the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> currents. Another is derived from the first cost function that regulates only the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> currents. The amplitude is determined directly in the voltage vector calculation. Finally, the experimental results show a good performance of these control strategies, in terms of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> currents production, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> currents and the switching frequency reduction.

Direct Torque Control of Dual Three-Phase Permanent Magnet Synchronous Motor

In this paper a direct torque control strategy for dual three-phase permanent magnet synchronous motor (DTP-PMSM) is presented, the machine has two sets of three-phase stator windings spatially phase shifted by 30 electric degrees. In order to reduce the stator harmonic current, torque and flux are controlled based on regulators and Vector Space Decomposition technique. The proposed approach has the benefits of low stator current distortion and low torque ripple. The validity and the efficiency of the selected technique are confirmed by simulation results.

A Stand-Alone PV-PEMFC System based SM-ANN-MPPT Controller: Solar Pumping Application using PMSM

Maximum Power Point Tracking (MPPT) is a tool to optimize the use of the produced power in renewable energy systems, particularly in photovoltaic (PV) systems. Many algorithms have been developed and reviewed in the literature. In this work, a Sliding Mode-Artificial Neural Network-based MPPT (SM-ANN-MPPT) technique is proved. A comparison is made with one of the simplest MPPTs in the literature Perturb and Observe (P&O). It has been found that the minimization of the PV power ripples and the dissipated energies have been gained using the SM-ANN-MPPT controller. The proposed controller is applied for a standalone PV system with a Proton Exchange Membrane Fuel Cell (PVPEMFC) considering variable irradiation and temperature. The application of the system is dedicated to a solar pumping system using a three-phase Permanent Magnet Synchronous Motor (PMSM). The control of the PMSM is ensured by a Direct Torque Control-Space Vector Modulation (DTC-SVM) approach. Two cases are tested: with imposed speed profile, and with a solar daily profile. Two cases of load profiles are also treated: constant and variable loads. The control behaviour is simulated and the results are revealed justifying the feats of the DTC-SVM PMSM drive. Results show improvement in robustness and stability under real daily climatic conditions.

Optimised design of LCC-S compensation topologies for wireless power transfer with dynamic load for electric vehicles

This paper proposes LCC-S compensation network structure to solve the problem of dynamic load changing that generally exists in wireless power transfer system. Transmitter current, phase angle, power factor, output power and efficiency are also analysed when the load changes. By preparing experimental platform and taking three-phase permanent magnet synchronous motor as equivalent load, we study the relationship between output power of the motor and output current of the transmitter under different motor speed and torque. We find the output current is stable at 1.87 A with resonant frequency at 20 kHz. Finally, system parameters are optimised by changing the ratio of each compensation element parameter, improving the output efficiency by 7.69%.

A Predictive Torque Control Method for Dual Three-Phase Permanent Magnet Synchronous Motor Without Weighting Factor

In order to solve the problem of the difficult design of weighting factor for model predictive torque control (MPTC) of dual three-phase permanent magnet synchronous motor (DT-PMSM), this paper proposes a MPTC strategy without weighting factor. Firstly, the virtual voltage vector (V3) is introduced to reduce the harmonic currents. Secondly, an approximate alternative principle for predicted current is proposed, which simplifies the dual-vector prediction model and decreases the complexity of the prediction model. The control set at ( $k+1$ )th is selected by judging the change in torque and the position of the stator flux, which reduces the number of candidate voltage vectors. Thirdly, the cost function is selected according to the system state at two adjacent moments. The cost function separates the electromagnetic torque and the stator flux, and eliminates the weighting factor. Decreasing the complexity of the prediction model, reducing the number of candidate voltage vectors, the combination of the two methods in this paper can significantly reduce the computational burden of the CPU. Finally, experiments verify the effectiveness of the proposed method. The results show that the proposed method greatly reduces the calculation burden of the system under the performance of electromagnetic torque does not change much.

Design of Three-Phase V-Shaped Interior Permanent Magnet Synchronous Motor for Air Conditioning Compressor of Electric Vehicle

Air conditioning system of electric vehicles has new change as the internal combustion engine is being replaced with electrified AC motor. With large amount of batteries installed at the bottom of frame, the conventional compressor, which is belt-driven, can be removed, and another AC motor can play the role for air conditioning in electric vehicles. From this change, the system efficiency would be improved since it is possible to control the electrified compressor independently from traction system in contrast with the belt-driven compressor. As a result, by applying the electrified compressor for air conditioning system, the whole system can achieve better efficiency and longer driving distance, which is most important in electric vehicles. In this paper, 3-phase interior permanent magnet synchronous motor (IPMSM) was designed using lumped-parameter model and finite element method.

Current harmonic elimination for dual three‐phase PMSM based on a spatial analytical model of flux linkage

Compared with the conventional three-phase motors, the dual three-phase permanent magnet synchronous motors (PMSMs) have many advantages and have been widely used in various drive fields. However, one major disadvantage of these machines is that they are easy to generate large stator current harmonics, which makes it difficult to have an excellent performance in the drive field. To solve this problem, this study introduces a current harmonic elimination method based on a spatial analytical model of flux linkage. The study reconstructed the analytical model of flux linkage from finite element analysis. The analytical model can describe the spatial harmonics of flux linkage by considering the rotor position information. Based on the model, an active feedforward controller was proposed to eliminate current harmonics by actively injecting the corresponding voltage harmonics, the voltage harmonics are calculated by the model of flux linkage. The performance of the proposed method in eliminating current harmonics is verified by simulations and experiments.