Diseño De Bobina Para Induccion

Páginas: 37 (9236 palabras) Publicado: 9 de mayo de 2012
Induction

Coil design and fabrication: basic design and modifications
by STANLEY ZINN and S. L. SEMIATIN

I

n a sense, coil design for induction heating is built upon a large store of empirical data whose development springs from several simple inductor geometries such as the solenoid coil. Because of this, coil design is generally based on experience. This series of articles reviews thefundamental electrical considerations in the design of inductors and describes some of the most common coils in use.

2) The greatest number of flux lines in a solenoid coil are toward the center of the coil. The flux lines are concentrated inside the coil, providing the maximum heating rate there. 3) Because the flux is most concentrated close to the coil turns themselves and decreases fartherfrom

Basic design considerations

The inductor is similar to a transformer primary, and the workpiece is equivalent to the transformer secondary (Fig. 1). Therefore, several of the characteristics of transformers are useful in the development of guidelines for coil design. One of the most important features of transformers is the fact that the efficiency of coupling between the windings isinversely proportional to the square of the distance between them. In addition, the current in the primary of the transformer, multiplied by the number of primary turns, is equal to the current in the secondary, multiplied by the number of secondary turns. Because of these relationships, there are several conditions that should be kept in mind when designing any coil for induction heating: 1) Thecoil should be coupled to the part as closely as feasible for maximum energy transfer. It is desirable that the largest possible number of magnetic flux lines intersect the workpiece at the area to be heated. The denser the flux at this point, the higher will be the current generated in the part.
S. Zinn is executive vice president, Ameritherm, Inc., Rochester , N.Y.; (716) 427-7840.S.L. Semiatinis a project manager in the Center for Materials Fabrication at Battelle Columbus Division; (614) 424-7742. This article is excerpted from the book “Elements of Induction Heating,” published by Electric Power Research Institute (EPRI) and distributed by ASM International, (516) 338-5151 and used with permission of EPRI
32

Ep = primary voltage (V); Ip = primary current (A); Np = number ofprimary turns; Is = secondary current (A); Ns = number of secondary turns; Es = secondary voltage (V); Rl = load resistance(Ω)

Fig. 1: Electrical circuit illustrating the analogy between induction heating and the transformer principle.

them, the geometric center of the coil is a weak flux path. Thus, if a part were to be placed off center in a coil, the area closer to the coil turns wouldintersect a greater number of flux lines and would therefore be heated at a higher rate, whereas the area of the part with less coupling would be heated at a lower rate; the resulting pattern is shown schematically in Fig. 2. This effect is more pronounced in high-frequency induction heating. 4) At the point where the leads and coil join, the magnetic field is weaker; therefore, the magnetic center ofthe inductor is not necessarily the geometric center. This effect is most apparent in single-turn coils. As the number of coil turns increases and the flux from each turn is added to that from the previous turns, this condition becomes less important. Due to the impracticability of always centering the part in the work coil, the part should be offset slightly toward this area. In addition, the partshould be rotated, if practical, to provide uniform exposure. 5) The coil must be designed to prevent cancellation of the magnetic field. The coil on the left in Fig. 3 has no inductance because the opposite sides of the inductor are too close to each other. Putting a loop in the inductor (coil at center) will provide some inductance. The coil will then heat a conducting material inserted in the...
Leer documento completo

Regístrate para leer el documento completo.

Estos documentos también te pueden resultar útiles

  • DISEÑO DE UNA BOBINA
  • DISEÑO Y CONSTRUCCIÓN DE BOBINAS DE CALENTAMIENTO PARA HORNO DE INDUCCION ELECTROMAGNETICA
  • Descripción de la bobina de inducción
  • Diseño de bobinas de radiofrecuencia
  • Inducción y Diseño de puestos de trabajo
  • Bobinas de Induccion
  • Diseño de bobinas para nucleo de ferrita tipo e
  • Lineamientos para un programa de inducción

Conviértase en miembro formal de Buenas Tareas

INSCRÍBETE - ES GRATIS