并联工作 meaning in English

parallel operation
parallel running
volume operation

The fourth part analyzed the intermediate dc voltage and its control principle and the technical parameter of the main parts in the ac transmission system . several key technical problems such as parallel working of the ac motors , the wheel diameter difference under the bogie - control mode , the ac motor - inverter matching principle are studied in detail . the principles to determine the electrical parameters are also discussed
论文第4章重点研究了变流器的中间直流电压的确定及其控制规律，确定了交流电传动系统主要部件的技术参数；研究了架控方式工作下电动机并联工作、轮径差、电机?变流器匹配原则等关键的技术问题；详细分析了交流传动系统在牵引工况和电阻制动工况下各参数的工作过程和控制原则。