In this paper, a proper duty cycle control method is proposed to reduce torque and flux ripples and harmonic loss in direct torque control (DTC) of six-phase induction machine (6PIM). Three different methods are proposed to improve the performance of switching table DTC for 6PIM. First, by the suitable selection of two vectors in each sampling period, the harmonic amplitude is significantly decreased, but the torque and flux ripples are still large. Then, the abovementioned method is combined with duty cycle control technique and the torque and flux ripples and current harmonics are significantly reduced. In addition, the switching frequency is also reduced by selecting the suitable voltage vector in each sampling period. Finally, a simple control method is suggested to calculate the duty ratio of voltage vectors independently of machine parameters. Although neglecting the one-step delay makes performance of the final technique similar to the previous one, considering this delay in real conditions shows the following advantages for the final method: less torque and flux ripples, less current harmonics, simplicity, and constant switching frequency. Despite these improvements, all duty cycle-based DTC approaches (duty-DTC and PI-duty-DTC) increase the inverter switching losses. The simulation and experimental results presented in this paper verify the performance advantages of the proposed methods.

中文翻译：

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基于PI调节器的占空比控制可减少六相感应电动机DTC中的转矩和磁通波动

本文提出了一种合适的占空比控制方法，以减少六相感应电机（6PIM）的直接转矩控制（DTC）中的转矩和磁通波动以及谐波损失。提出了三种不同的方法来提高6PIM交换表DTC的性能。首先，通过两个向量的在每个采样周期的合适的选择，谐波振幅显著下降，但转矩和磁通脉动仍然较大。然后，将上述方法与占空比控制技术相结合，可显着降低转矩和磁通波动以及电流谐波。另外，还通过在每个采​​样周期中选择合适的电压矢量来降低开关频率。最后，建议一种简单的控制方法来独立于机器参数来计算电压矢量的占空比。尽管忽略了一步延迟，但最终技术的性能与前一种方法相似，但考虑到实际条件下的这种延迟，对于最终方法显示出以下优点：扭矩和磁通量波动较小，电流谐波较少，简单且开关频率恒定。尽管有这些改进，所有基于占空比的DTC方法（占空比DTC和PI占空比DTC）都会增加逆变器的开关损耗。本文给出的仿真和实验结果证明了所提方法的性能优势。在实际条件下考虑这种延迟将显示出最终方法的以下优点：较小的转矩和磁通波动，较小的电流谐波，简单性和恒定的开关频率。尽管有这些改进，所有基于占空比的DTC方法（占空比DTC和PI占空比DTC）都会增加逆变器的开关损耗。本文给出的仿真和实验结果证明了所提方法的性能优势。在实际条件下考虑这种延迟将显示出最终方法的以下优点：较小的转矩和磁通波动，较小的电流谐波，简单性和恒定的开关频率。尽管有这些改进，所有基于占空比的DTC方法（占空比DTC和PI占空比DTC）都会增加逆变器的开关损耗。本文给出的仿真和实验结果证明了所提方法的性能优势。