This study focuses on the performance improvement of direct torque controlled (DTC) five-phase induction motor (FPIM). The performance indices are common-mode voltage (CMV), torque ripple and demagnetisation during low-speed operation. The three-level five-phase inverter (TL-FPI) is used for feeding the FPIM, since more voltage vectors are available in TL-FPI than its two-level counterpart. Among available 243 voltage vectors, 41 non-vertex voltage vectors are employed. These 41 voltage vectors through seven-level torque comparator (SLTC) fires an inverter. The SLTC reduces the torque ripple. All the employed 41 voltage vectors have zero CMV output. The voltage vectors are selected so that the magnitude of radial component of the resultant stator flux under low-speed operation is more than the same under normal speed operation. This modification resolves the problem of demagnetisation during low-speed operation. The proposed method achieves the intended targets without losing simplicity and dynamics of the classical DTC method. The performance improvement of the five-phase machine is validated through several results.

中文翻译：

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低速区共模电压，转矩脉动和去磁的直接转矩控制五相感应电动机性能改进

这项研究的重点是直接转矩控制（DTC）三相感应电动机（FPIM）的性能改进。性能指标是低速运行期间的共模电压（CMV），转矩波动和退磁。三电平五相逆变器（TL-FPI）用于为FPIM供电，因为TL-FPI中提供的电压矢量比其两电平逆变器更多。在可用的243个电压矢量中，采用了41个非顶点电压矢量。通过七级转矩比较器（SLTC）的这41个电压矢量触发逆变器。SLTC减小了转矩波动。所有采用的41个电压矢量的CMV输出均为零。选择电压矢量，以使低速运行时合成定子磁通的径向分量的大小大于正常速度运行时定子磁通的径向分量的大小。该修改解决了低速运行期间的去磁问题。所提出的方法在不失去经典DTC方法的简单性和动态性的情况下实现了预期的目标。通过几个结果验证了五相电机的性能改进。