A Microcontroller Sensorless Speed Control of a Direct Current Motor

It is described a sensorless direct current motor drive. The speed was controlled using sliding mode with a first- order differential equation based on the speed error. The result of the switching function was integrated with a current limitation using a logic equation. The current limitation assures the machine protection and the output of the logic block is the signal of the voltage to apply on the motor armature. Instead to measure the rotor speed it was analytically inferred an external torque and speed observer. The motor is fed by a classic insulated gate bipolar transistor converter module. All gating signals for power switches are determined at every sample instant by a single microcontroller, which collects information and analyze voltage and current data from the motor to perform the necessary speed and torque estimation.