News of network of global electric machinery: abundant
To asynchronous machine, electric machinery learns to did not resemble dc machine to use ideal sky to carry rotate speed and rotate speed to fall to convey rotate speed in that way, of rotate speed quarter changing is synchronism of have the aid of rotate speed N1 and turn poor rate S. A kind when serve as electromotor however, asynchronous engine rotate speed is likewise in fact carry rotate speed N0 and rotate speed to fall by ideal sky Δ N is formed, this is decided by the common law place of electromotor physical characteristic, also be the general expression form of electromotor rotate speed.
The synchronous rotate speed of asynchronous machine is advocate the metabolic speed of magnetic field is not mechanical movement, cannot maintain simply carry rotate speed for ideal sky; Turn the relation that poor rate is actual rotate speed and synchronous rotate speed, carry rotate speed to have nothing to do with ideal sky, more cannot turn poor rate is equal to fall at rotate speed. Analyse asynchronous machine ideal to carry rotate speed, rotate speed to fall for nothing deep then reach its and synchronous rotate speed, turn the relation of poor rate, the rule that finds out timing rotate speed then is very important.
Perhaps be the effect that gets afore-mentioned problems, at present communication timing theory thinks the outlet of asynchronous machine timing depends on changing synchronous rotate speed more, turn to the change poor rate timing objects, reason is to only former ability obtains efficient, high-powered timing. For example document 3 put forward: "Frequency control method and change turn poor timing method has essence to differ, turn from what high speed can keep finite to low speed poor rate, consequently frequency control has the timing property of efficient, wide range and high accuracy. Can think, a kind frequency control is AC motor more reasonable the timing method with ideal " . Consider deep to make clear however with practice however: Efficiency of asynchronous machine timing and function do not decide to be mixed at synchronous rotate speed turn poor rate, efficient the unique feature of timing is to change ideal sky to carry rotate speed, synchronous rotate speed is not the only decision amount that ideal sky holds rotate speed. Change turn what there is change ideal to carry rotate speed for nothing as much in plan of poor rate timing is efficient timing. The article puts forward to discuss an opinion for this, the hope causes the attention of concerned all circles.
1, the doubt of formula of asynchronous engine rotate speed
The maths that formula is objective law conveys a form, it can arise only at already some law, formulary, and the definition that cannot arise to be at the person.
Such building of the formula of asynchronous engine rotate speed that classical electric machinery learns.