No abstract

Electric motors are systems that transform electric energy into mechanical energy. Many applications require controlling some output magnitude of motor as speed and position. To control these magnitudes, it is requires measuring the magnitude with an observer. There are two type of observer: conventional observers and sensorless observers. Conventional observers are mechanical systems coupled to the motor shaft and measure the magnitude of interest. Some examples are tachometers, encoders and potentiometers. Sensorless observers are methods or techniques that only measure the current and/or speed to estimate the magnitude of interest. The main advantages of sensorless observers, compared to conventional observers, are as follows: not require couple to motor any mechanical element, decreased maintenance, number of connections and cost of the final system, and an easier miniaturization process. Sensorless observers in DC motors are divided into three groups: those based on the dynamic DC model motor, those based on the ripple component and those based on the combination of the component ripple and the dynamic DC model motor. Due to different problems, the sensorless observers in DC motors have not replaced to the conventional observers yet. This work aims to solve some problems of sensorless observers used to estimate the speed and/or position measuring only the DC motor current. The work proposes three new methods and each method solves a different problem.