Personal computer/programmable logic controller based variable frequency drive training platform using WxPython and PyModbus

Abstract

Variable frequency drive (VFD) is one of the key elements in industrial field. It is used to match the three-phase induction motor’s speed and torque to the industrial field process requirements in addition to energy saving and efficiency improvement. This important role of the VFD asks for the development of an efficient training and cost effective platform for the electrical engineering students, technicians, and maintenance personals. This paper introduces a user-friendly platform through which the users can understand and practice the configuration of the various parameters of the VFD unit. This platform uses two computing devices to deal with the VFD; these are the personal computer (PC) and the programmable logic controller (PLC) which is also a computer but designed to operate in wide range of temperature and humidity and can accept digital and analog signals. The PC uses WxPython (cross-platform graphical user interfaces (GUI) toolkit of Python programming language) and PyModbus communication utility to play the role of the human machine interfacing (which allows the user to execute the communication requirements and at the same time provide an oscilloscope like facility to display the platform response in real time mode or history recorded mode). With this platform, the VFD’s parameters configuration is done via the RS-485 communication port using Modbus recommandation temporaire d'utilisation (RTU) communication protocol.