Verification of simplified model of inverter-Motor stator system.

A simplified inverter-motor stator system model is presented in the paper. The model is based on elementary dynamic blocks described by differential equations. The paper presents the results of research aimed at verifying the model on different devices with different types of inverters and motors. Model accuracy coefficients have been developed for all examined cases, confirming the high conformity of the model to the measured speeds and torques of asynchronous motors. The model was also used to simulate the operation of a drive system with a synchronous motor, obtaining high compliance of speed and torque mapping. The presented cases of verification of a simplified model confirm the possibility of using it to model different devices fed by frequency inverters, controlled both manually and automatically. The presented model, using simple description, ensures high accuracy of speed and torque mapping. It should be emphasized that most parameters in the presented model are calculated for motors and inverters based on data sheets.

Overview of Materials Used for the Basic Elements of Hydraulic Actuators and Sealing Systems and Their Surfaces Modification Methods.

The article is an overview of various materials used in power hydraulics for basic hydraulic actuators components such as cylinders, cylinder caps, pistons, piston rods, glands, and sealing systems. The aim of this review is to systematize the state of the art in the field of materials and surface modification methods used in the production of actuators. The paper discusses the requirements for the elements of actuators and analyzes the existing literature in terms of appearing failures and damages. The most frequently applied materials used in power hydraulics are described, and various surface modifications of the discussed elements, which are aimed at improving the operating parameters of actuators, are presented. The most frequently used materials for actuators elements are iron alloys. However, due to rising ecological requirements, there is a tendency to looking for modern replacements to obtain the same or even better mechanical or tribological parameters. Sealing systems are manufactured mainly from thermoplastic or elastomeric polymers, which are characterized by low friction and ensure the best possible interaction of seals with the cooperating element. In the field of surface modification, among others, the issue of chromium plating of piston rods has been discussed, which, due, to the toxicity of hexavalent chromium, should be replaced by other methods of improving surface properties.