word "engine" always generates a representation of something rolling, and even more frequently - rotating.It is clear - and therefore the engine.The essence of any engine - to convert a form of energy into motion.Do you know what kind of engine was the first?It is believed that this was the sail.It would not be wrong to say that the most common engine - electric.Among the variety of electric cars in this class are the largest application received an induction motor, the principle of which is based on the two fundamental manifestations of electricity - electromagnetism and electric induction.
To understand the principle of the induction motor, remember the simplest experiences of school physics course:
- if through a wire to pass a current around it appears a magnetic field proportional to the current;
- if you take the two conductors with current, between them there is a force field - they repel or attract each other, just as it is done all the pieces of the magnets;
- if one current-carrying conductor moves relative to another, that is not connected to the source, but the circuit is closed, a current flows in it.
physical, or rather, speculative, process model includes the concept of magnetic field lines, which we denote the presence of the magnetic properties.That they who spread their "tentacles" in all directions, and if you come across in the way of a ferromagnetic material, ie,those in which the magnetic lines are concentrated, and then it operates the driving force.And if the material itself has a magnet, the force interaction of magnetic fields is even more marked.Enlarge the magnetic field of the conductor can be a large number of winding turns on the rod of a ferromagnetic - in the simplest case, this is an ordinary metal cylinder made of black metal.It is not difficult to make a rod-fired, and he put on the coil.The ends of the "horseshoe" steel poles of the magnet, which is when the current through the coil creates a strong maximum at the center of the poles, the magnetic field.Normally we visualize it on a stick figure.
If the gap between the poles placed a metal rod, and then begin to rotate our magnetic "horseshoe", we note that the rod will rotate.Why our device called an induction motor?The principle of operation of the electrical machine, as stated, is based on the phenomenon of electromagnetic induction, i.e.the intersection of magnetic lines of our body inductor core.A "crossing" is possible only when the rotational speed of the magnetic field of the inductor - "horseshoe" - more speed rod.This parameter motor - asynchronous speeds - called "slippage" and can reach up to 7% of the rated speed of the stator magnetic field.
maximum magnetic field in the gap, "horseshoe", changes its spatial position in its turn.In accordance with the law of electromagnetic induction, the rod an electric current along with his "life partner" - the magnetic field.Magnetic fields engage, interact, and ... turn the rotor.The actual principle of the induction motor repeats exactly as described herein.All full circle - two objects have no mechanical connection, but the rotation of one of them, which receives electrical energy results in rotation of the other.The role of the invisible "rope" perform the magnetic field of a horseshoe magnet and rod.
to create the engine remained almost nothing - you need not a "horseshoe" to rotate and force the rotating magnetic field of its own.In other words, the asynchronous motor operating principle shows that there point of maximum magnetic field in the stator is moved in a circle, as is our rotating electromagnet.It remains the case for small - "spin" the magnetic field.
task of the rotating magnetic field is solved as follows:
- circle have three pairs of poles - coils - at an angle of 120 degrees;
- each coil is supplied sine wave from a separate source.It is believed that a full time sine wave cycle (period) - is 360 degrees.Positive maximum voltage occurs at 90 degrees after zero - all as taught in school;
- highlight is that voltage peaks occur with a time shift in the third period (electricians say "three phase shift of 120 degrees") - this is the principle of the induction motor.Maximum intensity of the magnetic field is moved from the first to the second pair of poles, and then the third.Then the process is repeated, which is equivalent to the movement, or rather, "rotation" of the magnetic field.
So, simply and without fuss, the stator electrical energy is converted into mechanical motion of the rotor.To create this miracle engine, humanity took a few decades, and we had the 15 minutes to confidently say: induction motor?-No nothing easier.
