Electric Machines: Principles, Types, and Applications
Basic Principle of Electric Power Generation
Electric power is generated when a magnetic field interacts with a conductor, causing a movement that creates a current. This current is generated when the magnetic field alternates in the coil. When the magnets are perpendicular to the field, the current is at its highest point. As the field turns, the power decreases to”” when it becomes parallel to the field. If the field continues to turn, the current would reverse direction and become negative. Finally, the current would reach its maximum negative point and then return to its maximum positive point, completing a full cycle.
Collector Commutator Bars of a Dynamo
Starting with a single ring and brushes, the current can be maintained in the same direction. By increasing the number of thin bars, the flow becomes more frequent and closely resembles a continuous current (ripple current).
DC Generators
DC generators have four coils, two in the rotor and two in the stator. Both sets can operate independently, in series, parallel, or compound, which combines half of one winding with half of the other and connects them in series or parallel.
Brushless Motors
Brushless motors are based on DC motors with permanent magnets.
Universal Motors
Universal motors are DC motors that can also operate on alternating current. They are commonly used in washing machines and other appliances.
Tension and Speed Variation
The tension is proportional to the flux variation. Serial and parallel connections only increase the variance of flow velocity. When engines are separately excited, the flow speed is increased, as is the intensity of excitation. The speed is measured in rpm (revolutions per minute) with the letter n. Excitation intensity is another variable that varies the flow (Iex). To change the direction of the poles, change the direction of rotation, swap the poles with two contactors, or permute the rotor. This applies to serial, parallel, or loose connections.
Electric Motors
The operating principle of electric motors is based on the interaction of magnetic fields, current, and force. A magnetic field (B) and current (I) produce a torque (F), which is equivalent to force in rotary motion. The torque is proportional to the strength of the current. A motor with more torque has more acceleration.
Excitation
Excitation, like in generators, regulates the speed and prevents it from dropping too low.
Shunt Motors
Shunt motors connect a resistor in parallel with the rotor (inductor), varying the Iex and thus the speed of the motor. Advantages: Constant speed, increased torque.
Series Motors
Series motors connect the resistor in series with the rotor. Induction motors depend on the Iex, and their speed is inversely proportional to the torque. They are commonly used in cranes. When the torque is below the speed, the motor can break down.
Compound Motors
Compound motors combine the characteristics of both series and shunt motors, resulting in a larger torque.
Synchronous Machines
Synchronous machines have the same rotor and stator speed. Alternators must always operate at the synchronous speed of the network they are connected to.
Synchronous Motors
Synchronous motors operate at the speed at which they are driven by the frequency. They are useful in automation because they maintain a constant speed. The difference between the synchronous speed (n1) and the actual speed (n2) is called slip (S), which is characteristic of asynchronous motors.
Asynchronous Motors
As the load on an asynchronous motor increases, the slip increases, and the power consumption increases.
Armature Reaction
The magnetic flux created by the armature current distorts the motor’s inducer flux. This is perpendicular to the main magnetic flux created by the field poles. A similar phenomenon occurs in dynamos, where the armature reaction causes the neutral line to shift with respect to the direction of rotation.
Operating Principle of DC Motors
A DC motor is essentially a dynamo operating in reverse. A voltage is applied to the stator, which creates a current in the armature and consequently an electromagnetic torque that rotates the dynamo. The rotation produces a counter-emf that opposes the applied voltage.
Direction of Current
The direction of current in the coil is reversed in each half-cycle, crossing the neutral conductor line. This is achieved by changing the brush contact on the collector.
Principle of Operation of Synchronous Machines
The DC exciter feeds the rotor, creating a magnetic field. The rotor is rotated to N rpm for synchronous speed. The rotor’s magnetic field rotates at the same speed as the stator’s magnetic field, which is powered by an AC source. The interaction of the real poles of the rotor and stator produces fictitious tangential forces and a torque in the direction of rotation.
Single-Phase Induction Motor
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Its operation is the same as that of asynchronous induction motors. Within this first group have the following engines:
1. Auxiliary pole or so-called split-phase.
2. With condenser.
3. With short-circuit loop or so-called pole parties.
Single Phase Motor collector.
Similar to DC motors for its operation. There are two types of these engines:
1. Universal.
2. Repulsion ..
Ma chines and ncronas: Unlike synchronous machines normally employed as generators, asynchronous machines have found their main application as engines, due to the simplicity of its construction. The three-phase asynchronous motor is now the usual motor-operated in all distribution networks.
Match machine: Single-phase DC motor (Unversal work with (CA-wound rotor synchronous motors, hysteresis, reluctance – (asynchronous or induction motor in single phase Three phase, engine start -> capacitor, for auxiliary poles, shorted turns. Produccion AC in a coil that rotates within a magnetic field. When you rotate a rectangular loop between the polar icecaps of an electro magnet armature infuctor parties conrtan the fixed magnetic field is induced in them an induced emf whose value and meaning varies in each moment with the position. The coil terminals are connected to a ring conductor, where 2 brushes collect the current induced exterior.Para circuit and supplied to determine the meaning of the induced current rule is used the 3 fingers of right hand.Torque: The rotor conductors are electromagnetic forces which produce a pair of par fuerzas.Este will flip the rotor with the mechanical load to move