Single-Chip Solution Ahead for Motor-Speed Control

摘要

For many years the universal motor has been the motor of choice in the vast majority of home appliances, whether speed controlled or not. The reasons for choosing it more than two decades ago were clear: universal motors are inexpensive and can be controlled using a single semiconductor switch and a handful of other components. But is this motor type serving the industry well today? The fundamental problem with the universal motor is that it requires commutating brushes to feed current to the windings on the armature. These contact a number of slip rings around the rotor and are therefore subject to wear. With a growing demand by consumers for extended warranties, the brush life is a major factor in the cost of honoring such warranties. This has inevitably led many appliance manufacturers to reevaluate the universal motor.