Generalized analysis of operating limits on PM motors and suitable machine parameters for constant-power operation

Permanent magnet synchronous motors (PM motors) are widely used in industrial applications. Some applications such as electric vehicles and compressor drives require constant-power operation. The available maximum power under specified voltage and current constraints can be obtained by optimal current vector control, such as maximum torque control and flux-weakening control. The operating limits, however, strongly depend on the machine parameters. This paper examines the relationships between the machine parameters and the output characteristics. It is shown that the power-versus-speed characteristic depends only on the difference between the magnet flux linkage and the maximum flux linkage of the d-axis armature reaction. The maximum torque and the constant-power operating range are obtained as functions of this difference. The optimal machine parameters and the design of PM motors for constant power operation are discussed based on the overall analytical results and on analyses that takes into account both copper loss and core loss in light-load operation. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 55–63, 1998     

液压卷带装置动态性能试验研究

介绍了卷带装置的液压系统组成及工作原理,分析了液压泵的功率特性,搭建了液压卷带装置试验台,介绍了试验原理和硬件组成。通过大量试验,研究了启动时卷带装置的动态性能以及不同负载下系统的恒功率特性。     

变频控制恒功率液压源系统的研究

变频技术的发展与应用,为液压系统的节能提供了一条新的途径。结合变频调速技术与恒功率液压泵的调节原理,构成一种变频控制恒功率液压源系统,实现了液压源系统的恒功率输出与系统节能。     

液压恒功率调速机构变量弹簧的优化设计

介绍恒功率变量柱塞泵与液压恒功率调速机构的关系,以及恒功率变量柱塞泵的输出压力p与输出流量q关系曲线。运用优化设计试图解决实际曲线与理论曲线的偏差问题,以其偏差的均方根为目标求解可行的最佳方案。     

基于恒功率负荷的牵引供电系统潮流计算

采用电力系统的潮流迭代算法进行牵引供电系统潮流计算。建立了牵引供电系统数学模型,将机车负荷作为恒功率模型,根据机车负荷和供电电压,分别采用牛顿-拉夫逊法和前推回代法,进行了直供和AT牵引供电系统潮流计算,通过典型算例比较了其与传统简化方法(机车负荷为恒电流模型)在机车网压计算的差异。结果表明,传统算法误差较大,尤其是在高速重载工况下误差更大,而电力系统潮流迭代方法进行牵引计算的精度更高。     

CMOS硅风速传感器热性能的分析

给出了一种能同时测量风速和风向的基于CMOS工艺的二维硅风速传感器的工作原理、结构及其热学模型。针对恒温差和恒定功率两种控制方式,建立各自的一维传感器热学模型,并采用有限元分析工具ANSYS/FLOTRAN141分析和比较了不同控制条件下传感器的热性能及其和传感器特征尺寸的关系。最后,通过试验结果验证了模拟的正确性。     

无级调速电机主传动系统设计探讨

主要研究无级调速电机的主传动变速系统的设计。根据已定的机床主要技术参数，确定主电机的恒功率调速范围，选用主电机的实际功率大小，齿轮变速组的档数，以及绘制出主轴机械特性曲线。     

基于模糊控制的电牵引采煤机恒功率自动控制系统

为提高采煤机的生产效率,采用PLC对系统进行恒功率模糊控制技术,设计了基于模糊控制的电牵引采煤机恒功率自动控制系统。该系统经过反复调试及实际运行,结果表明:基于该方法的控制系统抗干扰能力强,功能实现简单,取得了良好的调节功能。     

Performance analysis of self-controlled synchronous motors considering the effects of magnetic saturation

A self-controlled synchronous motor, which has similar characteristics to a conventional dc motor, is being used in various industrial fields as an adjustable speed motor. The inductances in the motor are changed with change in the air-gap flux due to magnetic saturation (as in a field-weakening region). A new and simple formula representing the inductances (i.e., reactances), in which the effect of magnetic saturation is taken into account, is proposed in this paper. The validity of the formula is shown for the transient performances of a tested motor when the field voltage was stepped down. The effects of magnetic saturation on the steady-state and dynamic performances are then clarified for a motor having average constants of synchronous machines. It is shown that the steady-state motor speed for small values of dc input current when the magnetic saturation is considered is larger than that for constant parameters. It is also clarified that the field-weakening speed control regions for constant-power driving become narrow if the motor has the property of considerable magnetic saturation. The transient responses when dc input and field voltages are changed, respectively, are finally investigated; it is shown that if magnetic saturation is considered, the commutation limit of inverter thyristors for a step-down change in the field voltage is widened when compared with the case for constant parameters. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 56–69, 1997     

MG250/591-WD电牵引采煤机恒功率控制

论述MG250/591-WD电牵引采煤机截割电机恒功率控制系统,确保截割电机始终工作在额定功率附近。根据截割电机负载状态来自动调节采煤机的牵引速度,使采煤机的截割电机工作在额定功率范围内,即所谓"恒功率"控制。