A K M Arafat

Optimal sustainable fault tolerant control of five-phase permanent magnet assisted synchronous reluctance motor

This paper presents the optimal sustainable fault tolerant control of a five-phase permanent magnet synchronous reluctance motor (PMa-SynRM). Advanced fault tolerant control system has been required for applications where high reliability and safety is required including hybrid/electric vehicles and aerospace industry. The proposed fault tolerant control strategy is based on advanced vector control of multiphase machine which provide safe machine operation under various phase loss fault conditions. To achieve effective and sustainable fault tolerant operation of PMa-SynRM which utilizes reluctance torque through large saliency ratio, the optimum torque angle has been derived to deliver the maximum output torque while reducing the phase currents to lessen saturation effect in the machine. The optimal set of currents during the fault has been found to provide sufficiently smooth and long-time fault tolerant operation under fault condition. Extensive theoretical analysis, finite element analysis (FEA), and MATLAB simulation has been carried out to derive proposed method. The experimental result has been found by utilizing the 5hp dynamo system controlled by TI DSP F28335.

Fault tolerant control of five-phase permanent magnet assisted synchronous reluctance motor based on dynamic current phase advance

In this paper, fault tolerant control of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) has been discussed. Reliable control method under any fault conditions has been predominantly required in critical applications such as hybrid/electric vehicular applications and aerospace industries. The proposed method utilizes the advance vector control of multiphase machine to provide maximum amount of torque under different types of open phase fault conditions. To maximize the amount of torque, the current phase advance in the five-phase reluctance machine has been introduced which varies with saturation effects and load dynamic behavior. Under such condition, the phase advance has been calculated dynamically at different faults and load conditions. Considering that, the optimal set of currents has been injected to provide maximum amount of torque under different open phase fault conditions. Extensive theoretical analysis along with Finite element methods has been carried out to support the proposed method. The experimental results have been provided utilizing the 5hp dynamo system which consists of TI DSP control board and five-phase inverter system.

Investigation of a thermal model for a Permanent Magnet assisted Synchronous Reluctance motor

The use of High Power Density (HPD) electric machines in applications such as Electric Vehicles amplifies the need for their optimal thermal design in conjunction with their electromagnetic design. Permanent Magnet Synchronous Reluctance Machines (PMaSynRMs) are specialized Interior Permanent Magnet Synchronous Machines where the magnet content in the flux barrier paths is reduced resulting in a relatively economical design. This paper provides the overview of a study of a thermal model for a Five Phase Permanent Magnet Synchronous Reluctance Machine with two flux barrier paths. The proposed thermal model is then verified with experimental results and FEA simulations. Once developed, its use for online temperature estimation or integrated with an optimization algorithm will be considered as future work.

Detection and Estimation of Extremely Small Fault Signature by Utilizing Multiple Current Sensor Signals in Electric Machines

This paper presents a novel motor current signature analysis algorithm for accurate detection and precise estimation of extremely small fault signature by utilizing multiple–phase-current signals in an electric machine. The two most critical challenges in developing a reliable diagnosis method are the detection of extreme small signals under extremely harsh environment, and the formulation of adaptive threshold under dynamic operation and noise variation of a motor. These challenges are addressed in this paper by logically and statistically utilizing multiple existing current sensors and current signals to make an accurate detection, and statistical/adaptive threshold for precise detection and decision making. The performance of the proposed algorithm has been mathematically and theoretically proved under modeled Gaussian noise conditions. Proposed theory is also experimentally verified on a 3-kW five-phase permanent-magnet-assisted synchronous reluctance motor.

Comparison of electrical losses in an inverter-fed five-phase and three-phase permanent magnet assisted synchronous reluctance motor

This paper is to present a comparison of the electrical losses that occur in the five-phase and three-phase permanent magnet assisted synchronous reluctance motors (PMa-SynRM). Minimizing the losses has been the best practice to get maximum efficiency from high performance motor drive systems. This paper investigated four types of electrical losses which are common in a motor drive. Comparative loss analysis are done for both machines that includes core losses, winding losses, switching losses and conduction losses. The efficiency have been calculated and compared for five-phase and three-phase machines. Extensive theoretical analysis has been done through the MATLAB Simulink and finite element analysis (FEA) to make the comparison. The experimental results are done for the five-phase system under maximum torque per ampere (MTPA) condition by utilizing 5hp dynamo system controlled with TI DSP (F28335) and five-phase inverter system.

Novel frequency determination method for dynamic magnet temperature estimation of a five phase PMa-SynRM using signal injection method

The use of signal injection methods in the estimation of magnet temperature is an innovative and non-intrusive approach used in permanent magnet motors. One of the biggest challenges in these approaches however involves the determination of the optimal frequency of the injected signal in order to accommodate its detection, accuracy, sensitivity and implementation. This paper presents an innovative strategy which will dynamically determine the bandwidth of suitable frequencies at which these signals may be injected in a five-phase Permanent Magnet Assisted Synchronous Reluctance Motor (PMa-SynRM). The process involves the elimination of the known fundamental, harmonic and fault dependent frequencies from the current frequency spectrum to resolve a range of remaining frequencies at which the signal may be injected. A randomization process is then adopted to determine a frequency from the dynamically determined range of available frequencies to effectively estimate the magnet temperature. The experimental analysis has been conducted on a five-phase 3.7kW PMa-SynRM and the values obtained have been verified using an innovative wireless temperature measurement setup.

Fault detection of a five-phase permanent magnet synchronous reluctance motor based on symmetrical components theory

This paper presents a new approach for phase fault detection of a five-phase permanent magnet synchronous reluctance motor (PMa-SynRM). The proposed fault detection method has been developed through novel decomposition technique of sequential components of a five-phase electrical machine. Unlike conventional three phase machines, phase fault of five-phase machine shows different response under single phase fault, two adjacent phase fault, and two non-adjacent phase fault. A newly developed symmetrical component analysis is applied to identify those phase fault condition in five phase machines. The analysis has been further extended to detect the types of faults based on magnitude pattern of the fundamental frequencies of the symmetrical components in frequency domain. In this paper, open-phase fault detection analysis has been carried out through extensive simulation and experimental tests to validate the proposed method. A 5Kw dynamo system controlled by TI-DSP F28335 has been used.

Optimal Phase Advance Under Fault-Tolerant Control of a Five-Phase Permanent Magnet Assisted Synchronous Reluctance Motor

In this paper, optimal phase advances under fault-tolerant control (FTC) of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) have been proposed under different fault conditions. Critical applications where the consistency and safety are the major concerns in automotive and aerospace industries require reliable control systems. The multiphase motor is considered a promising candidate for these applications as it has redundant phases primarily for fault-tolerant operation. However, advanced FTC for a PMa-SynRM with maximization of reluctance torque has been limitedly studied until now. In the conventional approach, to maintain constant magnetomotive force under fault conditions, phase currents of a motor need to increase significantly. However, this will easily saturate the PMa-SynRM resulting in significantly reduced reluctance torque. To overcome this issue, this paper proposes a novel phase current control method that maximizes the reluctance torque with minimum phase current. Here, a phase current control with a novel phase advance has been proposed under various fault conditions. Extensive theoretical and experimental analysis has been carried out to verify the effectiveness of the proposed idea with 5-hp dynamo system controlled by TI DSP F28335.

Torque ripple minimization under unbalanced phase resistance in a five-phase permanent magnet assisted synchronous reluctance motor

This paper presents an analysis of the torque ripple minimization under unbalanced phase resistance (UPR) in a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM). There are many reasons for arising UPR conditions in a motor. One of the key reasons can be the shortening winding turns of the motor which significantly reduces the winding insulations. Therefore, over the times, the torque ripple increase gradually. Excessive torque ripple leads to early degradation of the drive train components with an increased acoustic noise that reduces the performances of a PMa-SynRM. Especially, under UPR conditions, the torque ripple becomes prominent which require smart and easy mitigation approach to retain the advantages of a PMa-SynRM. This paper investigates three different UPR conditions that commonly arise a five-phase PMa-SynRM. A simple phase voltage compensation technique has been utilized to improve the torque ripple under different UPR conditions. Extensive theoretical analysis has been carried out through finite element analysis (FEA) to verify the proposed idea. The effectiveness of the method has been evaluated by the experimental tests that are conducted by utilizing 3.7 kW dynamo system.

Study of the thermal effects of a five-phase permanent magnet assisted synchronous reluctance motor under fault tolerant control

This paper presents a study on the thermal effects of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) under various fault conditions. The major advantage of a five-phase system is the additional number of phases which make it suitable for fault tolerant control in critical service applications. However, under the fault tolerant control (FTC), to maintain maximum torque, the phase currents are changed (magnitude and phase) in the remaining healthy phases. This change results in higher copper losses and heat generated in the healthy phases. Additionally, under FTC, the temperature rises unevenly inside the machine which leads to unbalanced magnetic pull. Due to this unbalanced magnetic pull, the actual torque capability of the machine reduces which may seem counterproductive to the fault tolerant advantage of the system. In this study, the temperature sensitivity of a five-phase PMaSynRM under FTC has been investigated through finite element (FE) analysis. The experimental analysis has been conducted on a 5 hp five-phase motor drive system.