Variable frequency drives for commercial laundry machines

Variable-speed AC drives have a well-founded reputation for versatility and dependability, with many features and benefits that are just not available from other drive technologies. They are presently used in applications ranging from simple fan control to complex operations including process loops, positioning and indexing, and industrial laundry applications. The author briefly discusses variable frequency drives (VFD) theory and pulse width modulation. The author then describes a cost-effective VFD which is available for use on commercial laundry machines. It offers the latest in IGBT technology, the application-specific intelligent power module (ASIPM). This module eliminates control components normally associated with transistor firing schemes. All components are embedded in the ASIPM module. It can be used with both singleand three-phase input power, and voltages from 190 to 480 V. Control logic is stored in one application-specific IC and is user-addressable to allow programming for special requirements. Wash formulas, unbalance detection, and cycle times can all be programmed directly into the VFD software, eliminating the need for timers, microprocessors, etc.