Developing New Thermal Protection Method for AC Electric Motors

Abstract

Monitoring the thermal state of windings of electrical machines is a backbone for protection from unacceptable overheating. A large number of different methods and systems aim to solve this problem. This article discusses the main known methods of thermal protection of electric motors and provides their comparative analysis. This paper shows that the most promising methods are those based on control of the current active resistance of the stator winding, as its value uniquely depends on temperature. It is demonstrated that the known methods have a number of disadvantages. A new phase method for thermal protection of AC motors is proposed. The method is based on the fact that a temperature-induced change in the active and reactive components of the winding impedance causes a corresponding change in the angle between the vectors of phase voltages and currents. This allows for thermal protection by controlling the change in this angle. This article provides tabular analytical substantiation of the proposed method, which is based on the direct measurements of voltage and current and the subsequent algorithmic calculation of physical values functionally related to the sought angle. The authors develop a structural block diagram of a device that implements the proposed thermal protection method. All relevant experimental studies were carried out. In this case, a small-sized electronic thermometer with a remote digital temperature sensor connected to the USB port of a personal computer was used as a temperature meter. The results obtained confirm the functional capability and efficiency of the proposed technical solution.

Application of a mathematical model for the Motoman MH-50 industrial robot’s electric drive system

“…The practical significance consists of the research of the automation system having been carried out and the structure of the electric drive having been studied on an industrial robot, which affects the quality of obtaining a welding seam. A six-axis robot manipulator MH50-35 [6], [7] model of the company Yaskawa was chosen as a basic industrial robot, the parameters of which are shown in Table 1. This robot is universal and was designed to execute a wide range of tasks, such as transferring objects and welding operations.…”

Investigation on Temperature Rise Characteristic and Load Capacity of Amorphous Alloy Vegetable Oil Distribution Transformers with 3D Coupled-Field Method

“…It is necessary to calculate and estimate the typical fluid velocity U 0 when comparing the buoyancy effect and the thermal diffusion coefficient. When the fluid is guided only by buoyancy, according to the Grashof number, its typical velocity U 0 can be estimated, as given in (4).…”

“…Relying on online monitoring, it is found that the temperature distribution of various parts of the transformer is not uniform during operation [4]. The durability and service life of transformers would be reduced once it is overheated locally [5].…”

Challenges in Winding Design and Thermal Calculations: Physical Model of Permanent Magnet Synchronous Machine

“…The equivalent thermal parameters (thermal conductivity [14,15] heat transfer coefficients [16,17]) are often historically defined as empirical values based on the comparison of the calculation and measurement. The same methodology is also used in [18,19].…”