Textile Applications of Adjustable-Frequency Drives with Digital Ratio Control

The application of digital techniques to program and to process the input signals to adjustable-frequency inverters for the control of rugged ac motors is becoming widespread. It was perhaps inevitable that digital signal control would eventually be combined with the inherently digital adjustable-frequency power inverter to produce systems having high overall line speed accuracy, adjustable ``digital gearing´´ between sections, locked-in-step acceleration from creep to run speed, and in-train digital jogging. A short introduction to adjustable-frequency motor control is given, and the use of digital techniques for controlling adjustable-frequency inverters to produce digital speed systems is described. Early applications of the first solid-state inverters to synthetic fiber spinning and their continued use is described. Specific current applications of digitally controlled adjustable-frequency speed systems are discussed, and potential applications that demonstrate how the capabilities of such systems can be used to provide economic solutions to many textile industry drive problems are reviewed.