Modern Automation Technologies Professional Magazine


НаименованиеThyristor Drive Control System


Among the various power converters available today, thyristor converters and electric drives have become widely used in various industries, with their capacities ranging from 1 kilowatt to hundreds of megawatts. But as a piece of equipment to be controlled, thyristor converters are fairly challenging, requiring precise execution of different control responses at specific times. Synchronizing such devices with power supplies with alternating current of questionable quality and stability is particularly difficult. Moreover, such equipment necessitates swift alerts to, and appropriate reactions to, emergency situations to protect the converter's power unit from going offline.

The developers of the SU-M1 system elected to address this challenge using a control system based on a powerful, yet relatively inexpensive controller with advanced software. The best controller for the job was Octagon Systems' 6040-series MicroPC, which met the necessary functional requirements, proved capable of controlling the equipment, had a discrete input-output port and digital/analog and analog/digital converters together with ISO 9001-certified reliability. In addition, this controller's processor was compatible with the x86-series processors widely used in PCs, giving access to a broad range of software, simplifying the development and deployment of applications.

The SU-M1's developer set out to create a system that would be highly reliable, that would be easy to use, that would provide the necessary data to control the equipment and identify and deal with extraordinary situations through a centralized diagnostics system, and that could work with new and legacy equipment. To meet these goals, the developers used hardware only where it could not be replaced with software, such as the 90-watt power supply, sensors, isolators, RS-422 signal interfaces and pulse shaper for the control of the thyristors. The SU-M1 can also be bundled with a 4x20 LCD display and a KP-2-16 keyboard from Octagon Systems or analog devices. The system can also be connected to a local network through an RS-485/422 port, or to a broader system through a standard radio modem.

The system's software is written in C and is multitasking in strict real-time conditions. The program is compiled for DOS and, after it is converted to protected mode, uses only the file-related functions. The software provides users with a flexible set of controllable parameters for controlling the system such that identically configured SU-M1 systems controlling different equipment will differ one from another only in their initial parameter files.

Currently a less expensive version of the system is being developed using the PC/104 modular controllers from Advantech. This version will not be capable of operating in the extreme conditions that the MicroPC allows for, but the software and functionality will be nearly the same.


Typical 100/440 thyristor DC electric drive.

By Mikhail Blazhenkov, Maxim Sankov and Denis Chentsov

Mikhail Blazhenkov,  Maksim Sankov,  Denis Chentsov