FR2511806A1 - PROCESS FOR THE SUPPLY AND DEMAGNETIZATION OF HIGH-POWER DIRECT CURRENT MAGNETS - Google Patents

Abstract

A SERIAL MOUNTING OF TWO C CAPACITORS, D IS CONNECTED IN PARALLEL WITH THE L REEL OF THE ELECTRO-MAGNET M. A DIODE D, D IS CONNECTED IN PARALLEL WITH EACH THESE TWO CAPACITORS OR WITH ONLY ONE CAPACITOR. DEMAGNETISATION IS PRODUCED AUTOMATICALLY AT THE OPENING OF SWITCH K IN THE COIL SUPPLY CIRCUIT 1. THIS ASSEMBLY ALLOWS THE USE OF POLARIZED CAPACITORS AND IN PARTICULAR ELECTROLYTIC CAPACITORS.

Description

Z 5 11806

  The invention relates to an assembly for the supply, with a view to magnetization, of electromagnets supplied with direct current, in particular of high power electromagnets as well

  only for their degtisatin by their own self-induction current.

  By US Patent 2,445,459, we know that we can obtain u: ed $ n isaticn efficient, autoiatic and complete by means of a capacitor q 1 ii is connected in parallel with the coil of an electro-aimsnt and which produces demagnetization when

  the electrical supply to the coil is cut off.

  The assembly represented in this patent has however the incon-

  vê: ient that the non polarized capacitors and of high capacity which are necessary become very large, thus at the same time bulky

  and expensive, in the case of high power electromagnets.

  The invention therefore aims to provide an improved electrical coupling or mounting method, in particular allowing the use of polarized capacitors, which are smaller, of electrolytic capacitors for example i nco: porés in assemblies suitable for supply and demagnetization of electromagnets with current

  continuous, in part from very strong electromagnets.

  According to an essential characteristic of the method of the invention, a series shading of two capacitors is connected in parallel with the coil of the electromagnet, a diode is connected in parallel with each of the two capacitors or with only one capacitor and mount a switch in the coil supply circuit The invention even allows the use of non-polarized capacitors According to another characteristic, applicable to polarized capacitors and in particular to electrolytic capacitors, the capacitors are mounted in series by connection to each other with poles of the same sign and one connects a diode in opposite direction parallel to each _ of the two capacitors or to a capacitor only In case

  use of electrolytic capacitors, diodes, in combination

  due to the capacitor charges, prevent the capacitors

  sators are exposed to and charged under a reverse voltage of

  their polarity under the influence of excitation and self-tension

11806

  induction The result is that the demagnetization current created in the electromagnet coil by the self-induction voltage only raises the voltage across the terminals of one and suppresses it at

  terminals of the other electrolytic capacitor.

  Other characteristics and advantages of the invention

  will emerge more clearly from the description which follows from

  several nonlimiting exemplary embodiments, as well as appended drawings, in which: FIG. 1 is the diagram of an assembly with two diodes, according to a first example of implementation of the method of the invention, FIG. 1 shows a variant the assembly of Figure 1; Figure 2 is a diagram of a diode assembly, according to a second example of implementation of the method of the invention Figure 2a shows a variant of the assembly of Figure 2; and Figures 3, 4 and 5 are voltage / time graphs

  relating to the assembly of FIG. 1.

  When, in the example of FIG. 1, the closing of

  switch K in supply circuit 1 causes the appli-

  cation of the voltage of the current source VL at the terminals of the coil L of the electromagnet M, so that the voltage UL at the terminals of the coil L corresponds to the section T 1-T 2 in FIG. 3, the current flowing through the coil L magnetizes the electromagnet M, the electrolytic capacitor Cl is charged through the diode D 1 at a higher voltage than that of the current source VL, as indicated by the section T 1-T 2 of Figure 4, representing the voltage Uc 1 across the capacitor Cl and the electrolytic capacitor

  CI is charged, under the influence of pulsating direct current through-

  the diode Dg, at a voltage lower than that of the current source VL, as indicated in the section T 1-T 2 of FIG. 5, representing the voltage UC 2 at the terminals of the capacitor C When

  the supply circuit 1 is cut by opening the interrup-

  tor K the energy of the electromagnetic field is discharged, creating in the coil L of the electromagnet M a self-induction voltage tooth polarity is reversed compared to that of the voltage

  at supply source VL, self-induction voltage which is represented

  felt in the section T 2-T 3 of FIG. 3 and which raises the charge of the electrolytic capacitor C 2 through the diode D 2

  (tronçoa T 2-T 3 in figure 5), reduces the charge of the condensate

  electrolytic separator C 1 (section T 2-T 3 of FIG. 4) and circulates in the coil L of the electromagnet M a current reversed with respect to the magnetization current, that is to say a current of

dem agnétisation.

  Because of its resistance in the conductive direction, the

  diode D 2 is unable to avoid the effect of the dema

  generation on the charge of the capacitor C 1 but the charge of this capacitor will be partially removed under the effect of this current

  demagnetization, as indicated by the section T 2-T 3 of FIG. 4.

  At the end of demagnetization, similar charges remain in the capacitors C 1 and C 2 (sections T 3-T 4 of FIGS. 4 and 5) In the event that the charge of the capacitor C 1 is sufficiently high, it is even possible to obtain the same result without using the diode D 2,

  as in the assembly of figure 2 or as in the equilibrium assembly

  are the same as in FIG. 2 a Depending on the application, one or both of the electrolytic capacitors C 1 and C 2 of the assemblies according to the invention, like those shown in FIGS. 1, la, 2 and 2 a, can be replaced by non-polarized capacitors The switch K of the supply circuit can be a contact switch, a

  transistor, a thyrlstor or a switch of another type.

  The mounting method according to the invention is particularly suitable

  especially to direct current electromagnets but it is applied

  general cable to power and demagnetization

of different inductances.

11806

R E V E ND I CA T I O N S

  Method for supplying inductors supplied with direct current, in particular electromagnets, and for their

  demagnetization by a current produced by self-induction, characteristic

  laughed in that a series connection of two capacitors (C 1, C 2) is connected in parallel with the coil (L) of the electromagnet (M),

  connects a diode (D 1, D 2) in parallel with each of the two conden-

  sators or with a capacitor only and a switch is mounted

  (K) in the supply circuit (1) of the coil.

  2 Method according to claim 1, characterized in that the two capacitors (C 1, C 2) are polarized capacitors, which are mounted in series by connection to each other of poles of the same sign of the capacitors, and we plug in a diode

  (D 1, D 2) in the opposite direction parallel to each of the two capacitors.

  3 Method according to claim 2, characterized in that

  a rectifying diode (D 1) is connected in the opposite direction parallel

  only to a capacitor (C 2) only.

  4 Method according to claim 1, characterized in that

  the two capacitors (C 1, C 2) are non-polarized.

  5 Method according to claim 4, characterized in that a diode is connected in parallel with a capacitor (C 1 or C 2) only. 6 Method according to claim 1, characterized in that one of the capacitors (C 1 or C 2) is polarized, while the other

is not.

  7 Method according to claim 1, characterized in that the switch (K) is a contact switch, a transistor, a

  thyristor or a switch of another suitable type.