Lecture 4 - Actuator Flashcards
What is a solenoid?
Coild of wire generating a magnetic field when an electric current passes through it.
It consists of a coil and a movable iron core called an armature.
When the coil, shaped like a long cylinder, carries a current, it acts as a magnet, pulling a movable core into the coil as the current flows.
What is a relay?
Electrical operated switch that uses a smal current to control a larger current.
When the small current flows through the coil, it creates a magnetic field that moves a lever, opening or closing the contacts to switch the larger current on or off.
What is a voice coil?
A coil moving in a magnetic field produced by a permanent magnet (magnetic field generated by the internal structure of the component)
What is a commutator?
Changes/switches the direction of current in a generator/motor
Name the 4 categories of DC motor and explain short how they work.
- Permanent magnet - uses permanent magnets to create the magnetic field. The armature (rotating part) is powered by DC current
- Shunt wound - field winding (stationary coil creating the magnetic field) is connected parallel with the armature. Both the field and armature receive the same voltage.
- Series wound - field winding is connected in series with the armature. Current flows through both the field and armature in sequence.
- Compond wound - combines features of both shunt and series motors. Has two field windings: one parallel (shunt) and one in series with the armature
What is a DC motor (with brushes)
A DC motor uses permanent magnets, coil(s) connected to a shaft, and brushes to create rotational movement.
Current flows through the coils which creates a electromagnetic field. The shaft rotates to allign the the permanent magnets. The direction of current is switched using the brushes, which flips the polarity of the electromagnetic field from the coil. This makes the shaft turn once again. This is repeated.
