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Serie Precision labs: motores de CC con escobillas

El motor de corriente continua (CC) con escobillas es el tipo de motor más sencillo y el conocimiento sobre cómo operar un motor de CC con escobillas es fundamental para aprender sobre los controladores de motores en general. En esta serie de videos se explica qué es un motor de CC con escobillas, cómo funciona y cómo funciona.

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      Welcome to the first chapter in the TI Precision Lab series on brushed DC motors. My name is Rick Duncan, and today, I will discuss the basics of brushed DC motors. Brushed DC motors are used to move a load in one direction or in both directions.

      Brushed DC motors provide a simple, low cost solution in many applications. Brushed DC motors do not require current control. Brushed DC motors are easy to control. Disadvantages of brushed DC motors include the lifetime of the brushes, noise, sparking, and possible EMI concerns. Brushed DC motors may not be suitable for some environments where the spark, or brush dust, is a concern.

      Applications for brushed DC motors include door locks, power windows and lifts, robotic vacuums, printers, toys, and currency counters. Brushed DC motors were invented almost 200 years ago. The brushed DC motor is the simplest type of motor. Brushed DC motors have a winding on the rotor.

      Brushes, made of metal or carbon, energize the winding through a commutator on the rotor. As the rotor rotates, the commutator changes the direction the current flows through the windings. When current changes directions in the winding on the rotor, the polarity of the rotor's magnetic field changes. The commutator ensures the polarity of the magnetic field on the rotor always opposes the magnetic field created by the magnets or windings on the stator.

      To operate a brushed DC motor, provide a voltage across the motor terminals, and the motor will spin. Changing the magnetic field on the rotor creates continuous motion in the brushed DC motor. To control a brushed DC motor in one direction only, a single FET plus a recirculation diode to protect the FET is required.

      Turn the FET on to drive the motor. Turn the FET off to stop the motor. The recirculation diode protects the FET by recirculating the current during the FET off time. The brushed DC motor cannot reverse direction in this configuration.

      To control a brushed DC motor in both directions, four MOSFETs are required to create an H-bridge configuration. The H-bridge looks like the letter H. The brushed DC motor is in the forward direction when the high side FET on out1 and the low side FET on out2 are on. To stop the motor, all FETs are disabled. When the FETs are disabled, the current will flow through the body diodes of the FETs, as shown.

      The motor is in the reverse direction when the high side FET of out2 and the low side FET of out1 are on. To stop the motor, all FETs are disabled. When the FETs are disabled, the current will flow through the body diodes of the FET, as shown. For more information on brushed DC motors and TI brushed DC motor drivers, please visit the brushed motor DC driver page on ti.com.

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      Serie Precision labs: motores de CC con escobillas