Fuzzy logic applied to motor control

Abstract

Today, home appliance applications require more and more features such as motor speed adaptations to multipurpose accessories, user friendly interfaces, and security features. Such new requirements can be achieved through a low-end microcontroller-based electronic control using the fuzzy logic approach. Nowadays, most of fuzzy logic-based controls are only limited to a complicated ranking management of user interfaces, sensors, and actuators, corresponding to a slow software speed operation. This paper proposes a totally different use of fuzzy logic. In this case, fuzzy logic is implemented in a standard microcontroller to regulate the speed of a universal motor by a real time adjustment (every 30 millisecond) of the motor current. This microcontroller directly tunes the motor current by means of a chopper converter. Starting from a basic food-processor application, the paper practically shows how a fuzzy logic approach can be applied to build a closed speed regulation loop from a very low cost tacho-generator. Practical guidelines are successively given from the initial concept analysis phase, up to the final generation of the executable code to be loaded in the microcontroller. The paper also gives the practical procedure to define the input parameters and to build fuzzy logic rules when using the fuzzy logic development tool. Finally, the major benefits of this paper lie in an original approach where fuzzy logic is applied to fast "real-time" regulation loop without requiring any specific expertise in conventional methods of regulation. Benefits are discussed and concrete results are given.