Design and Development of Low Torque Ripple Variable-Speed Drive System With Six-Phase Switched Reluctance Motors

Switched reluctance motor (SRM) drives conventionally use current control techniques at low speed and voltage control techniques at high speed. However, these conventional methods usually fail to restrain the torque ripple, which is normally associated with this type of machine. Compared with conventional three-phase SRMs, higher phase SRMs have the advantage of lower torque ripple: To further reduce their torque ripple, this paper presents a control method for torque ripple reduction in six-phase SRM drives. A constant instantaneous torque is obtained by regulating the rotational speed of the stator flux linkage. This torque control method is subsequently developed for a conventional converter and a proposed novel converter with fewer switching devices. Moreover, modeling and simulation of this six-phase SRM drive system has been conducted in detail and validated experimentally using a 4.0-kW six-phase SRM drive system. Test results demonstrate that the proposed torque control method has outstanding performance of restraining the torque ripple with both converters for the six-phase SRM, showing superior performance to the conventional control techniques

Cost-Effective and High-Efficiency Variable-Speed Switched Reluctance Drives With Ring-Connected Winding Configuration

This paper presents a novel converter topology for six-phase switched reluctance motor (SRM) drives, which reduces the number of switches and diodes by half, compared with the conventional asymmetric half-bridge converter, but needs no additional energy storage component. A dynamic model of a six-phase SRM is developed in the MATLAB/SIMULINK environment and conventional current chopping and angle position control techniques are applied to the proposed converter, demonstrating successful operation across the full speed range with modified conventional control techniques, lower converter losses, and higher system efficiency compared with the asymmetric half-bridge converter. Experimental tests comparing two versions of the proposed converter with an asymmetric half-bridge are described and verify the predictions of the simulations

A torque ripple minimization method for six-phase switched reluctance motor drives

This paper presents a direct torque control (DTC) method on a six-phase SRM driven by a six-phase asymmetric half bridge converter. Modeling and simulations of the proposed drive system have been built with MATLAB/SIMULINK. In the proposed DTC method, instantaneous output torque of the six-phase SRM is directly controlled by flux-linkage magnitude and rotating speed regulation (acceleration or deceleration) respective to rotor movement. The simulation and test results accurately reflect the actual operation states of the SRM. Compared with traditional current chopping control (CCC), the DTC method can effectively reduce the torque ripple for the six-phase SRM

Effects of Winding Connection on Performance of a Six-Phase Switched Reluctance Machine

This paper investigates the effect of the stator winding connection on the performance of a six-phase Switched Reluctance Machine (SRM). Five winding connection types are proposed for the machine. Finite element analyses (FEAs) of flux distribution, output torque and core losses are presented under single-phase and multi-phase excitation for each connection and the results are used to compare the average torque and torque ripple ratio characteristics and to develop understanding of the respective contributions of mutual inductance in torque development. Experimental tests on a six-phase conventional SRM verify the torque performance and mutual inductance effects of the different winding connections. An optimum winding configuration for a six-phase SRM is proposed

Present and Future of Fault Tolerant Drives Applied to Transport Applications

An electric drive is an electromechanical conversion device, consisting of an electrical machine, a power electronic inverter, which interfaces between the machine and the electrical supply, a set of sensors and a digital electronic controller. Drives of this sort are manufactured in high volumes at power levels ranging from less than 1W to many MW. Reliability of the complete system depends upon the local environment, levels of thermal cycling and predictive maintenance schedules. Overall the drive system has a typical reliability of the order of 10-5 failures per hour, making it much more reliable than, say, an internal combustion engine. As part of the “electrical revolution” electric drives are increasingly being developed for safety critical applications, where their reliability is several orders of magnitude below the application requirements. This is particularly the case in electrical propulsion and actuation systems in aircraft, leading to intensive research into fault tolerant electric drives. This paper will illustrate some of the most common failure mechanisms and the consequences of such failures. It will then progress to examine architectures which are fault tolerant through partitioning of the drive into several independent lanes and examine the penalties of adopting such an approach. The paper will discuss pros and cons of different fault tolerant architectures and suggests future research and development steps that are required to increase the overall safety of electric drives

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented