FR2709890A3 - Stabilization circuit. - Google Patents

Abstract

Stabilization circuit for a half-wave voltage rectified from the AC mains voltage with a semiconductor element with longitudinal passage between a capacitor and a rectifier and a reference voltage element on the pilot pole of the semiconductor element. longitudinal passage conductor, characterized in that the longitudinal passage semiconductor element is an electronic switch (12) which switches when the half-wave voltage has reached a value which is greater than the voltage reached in a smoothing capacitor ( 6) and as long as this is smaller than the reference voltage, and is blocked when the half-wave voltage is less than or equal to the voltage on the smoothing capacitor and a current limitation (13) is provided for the current going to the smoothing capacitor (6) when the switch (12) is switched.

Description

The invention relates to a stabilization circuit for a

  half-wave voltage rectified from alternating voltage

  mains cable with a semiconductor element with longitudinal passage between a capacitor and a rectifier and a reference voltage element on the pilot pole of

  the semiconductor element with longitudinal passage.

  Electrical appliances, for example household appliances

  which work with control electronics,

  attempt a mains block which reduces and rectifies the alternating mains voltage at the level of the signal voltage of the control electronics and rectifies it. According to the state of the art, regulators are used for stabilizing the supply voltage of the control electronics.

  with longitudinal passage. Such a long passage regulator

  dinal works with a transistor as a semi-element

  conductor with longitudinal passage. Usually the circuit is dimensioned so that the transistor is not yet fully saturated at maximum load current. The highest dissipated power occurs on the transistor when the value of the load current represents half of the maximum load current. Because the product resulting from current and voltage then has the maximum value

on the transistor.

  To dissipate the power dissipated by the step transistor -

  longitudinal wise, this is mounted on a cooling body

  or a cooling plate. The cooling body

  respectively the cooling plate are relatively expensive components which involve assembly costs and take up space in the construction of

control electronics.

  In DE 28 13 402 A1, a stabilization circuit is described for a supply voltage. Voltage

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  power supply is a DC voltage, however it is not a half-wave voltage derived from the AC mains voltage. The longitudinal transistor needs here too

  in the practice of a cooling plate.

  In DE 35 12 480 C2, a switching device is described for which a load must be suddenly connected to the supply voltage source as long as the

  Load specific voltage area dominates. Here, the ten-

  Supply voltage is also a DC voltage which can come either from a battery or from a mains device. A similar problem is also solved by the

  stabilization circuit of EP 0 226 725 B1.

  The object of the invention, for a circuit for stabilizing the

  type mentioned in the introduction, is to keep the power low

  this dissipating decreasing on the semiconductor element with step-

  longitudinal wise in order to save a cooling body

  respectively to be satisfied with a small body of

cooling.

  According to the invention, for a stabilization circuit of the type mentioned in the introduction, the object is achieved by the fact that the semiconductor element with longitudinal passage is a

  electronic switch which switches when the voltage half

  wave has reached a value which is greater than the voltage reached in a smoothing capacitor and as long as this is smaller than the reference voltage, and hangs

  when the half-wave voltage is less than or equal to the voltage

  on the smoothing capacitor and a current limitation is provided for the current going to the capacitor of

  smoothing when the switch is switched.

  The decreasing residual voltage on the electro-

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  nique, when it is switched, is very weak so that it only drops a weak dissipated power. In addition, the charging current is limited by the current limitation. The

  current limitation absorbs the power which, in the

  traditional baking includes a sheet for cooling the transistor with longitudinal passage. We thus obtain that no cooling body is necessary for the switch.

  electronic or a comparative cooling plate-

smaller is enough.

  The invention is also characterized by the fact that a) the electronic switch switches when the voltage on the smoothing capacitor is less than the reference voltage at least by the value of the starting voltage of the electronic switch,

  b) the electronic switch is a thyristor or a triac.

  c) an ohmic resistance is provided for limiting the current. d) for current limitation, a transformer placed

  in front of the rectifier is sized accordingly.

  e) between the cathode and the trigger of the respective thyristor

  ment of the triac, there is a resistor and a diode is com-

  mutated between the trigger and a resistor on the rectifier. Various other features of the invention emerge

  moreover from the detailed description which follows.

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  Embodiments of the subject of the invention are shown, by way of nonlimiting examples, in the accompanying drawings. FIG. 1 is a sector block presenting a stabilization circuit with cooling bodies according to the state

of technique.

  FIG. 2 is a sector block presenting a circuit of

  stabilization according to the invention without cooling plate

  sement. A sector block has a transformer (1) whose primary winding (2) is at the AC mains voltage (UN) and whose secondary winding (3) is placed

  after a bridge rectifier (4). On the terminal (5) of the redres-

  sor (4), there is a rectified half-wave voltage.

  According to the state of the art (fig. 1) a passing transistor

  longitudinal (7) is placed between the terminal (5) and a condensa-

  (6). The DC supply voltage (Ua) can be

  taken from the capacitor (6) for example for an electric

control board.

  At the base of the transistor (7) is connected, as a reference voltage element, a Zener diode (8). In addition, the base is applied to the terminal (5) via a resistor (9) and via a resistor (10) to the emitter of the transistor (7) respectively to the capacitor

(6).

  A cooling body (11) must be thermally connected

  with the longitudinal passage transistor (7) to evacuate the

  heat dissipated from the transistor (7).

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  In the circuit according to the invention according to FIG. 2, there is provided, in place of the transistor (7), a thyristor (12) as an electronic switch. It can also be used a triac. Between the thyristor anode (12) and the terminal (5), there is a current limiting resistor (13). The thyristor cathode (12) is connected to the capacitor of

  smoothing (6). In addition, the resistor (10) is connected to it.

  The Zener diode (8) is located on the trigger of the thyristor (12). In addition, on the trigger are also applied the resistor (10) and a diode (14) which is connected by the

resistance (9) at terminal (5).

  For the thyristor (12), no cooling body is necessary. Calculations show that the circuit according to fig. 2 is considerably less expensive in terms of labor and material costs than the circuit according to the

fig. 1.

  The operating mode of the circuit according to fig. 2 is approximately as follows: For each of the rectified half-waves coming from the terminal (5) of the bridge rectifier (4) the thyristor (12) is started each time a) the half-wave voltage reaches a value which is higher than the respective voltage on the smoothing capacitor (6) and b) the voltage on the smoothing capacitor (6) is smaller than the breakdown voltage (reference voltage) of the Zener diode (8) and, this, at least the value of the voltage

thyristor ignition (12).

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  When the thyristor (12) is started (conductive phase) a charge current flows through the smoothing capacitor (6) via the thyristor (12). This charging current is limited by the ohmic resistance (13). A dissipated power which must be absorbed and evacuated by the cooling body (11) drops to the resistance (13) in the case of the circuit of fig. 1. The resistance (13) is, as far as

  concerns the mounting and material costs, considerable-

  less expensive than this cooling body (11), even when this cooling body (11) is only a simple cooling plate. In the conductive phase, the

  thyristor (12), unlike the long-pass transistor

  gitudinal, is completely switched so that only a small residual voltage drops and there is thus only a small dissipated power. The thyristor (12) does not heat up enough for a large cooling plate

is necessary.

  Towards the end of each half-wave, the half-wave voltage

  does not exceed the voltage on the smoothing capacitor (6).

  The thyristor (12) is extinguished by the fact that it is no longer traversed by the current, until it is possibly re-primed during the next half-wave. During each half-wave, the time occurring during which a charge current passes over the smoothing capacitor (6) is then automatically regulated. Depending on the load (control electronics) connected to the direct supply voltage (Ua), the conductivity time is longer or shorter

  in each half-wave. The stabilized voltage on the condensa-

  smoothing level (6) corresponds approximately to the tension

of the Zener diode (8).

  The diode (14) is blocked as long as the voltage at the terminal (5) of the bridge rectifier (4) is lower than the stabilized voltage appearing on the capacitor of

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  smoothing (6). During this time, the trigger voltage of the thyristor (12) is maintained, via the resistor (10), at the same value as at its cathode. There is therefore no negative voltage between the cathode and the trigger of the thyristor (12) when the voltage in a half-wave is, at terminal (5), lower than the respective charging voltage of the

smoothing capacitor (6).

  The resistor (9) limits the current going to the trigger of the thyristor (12) during the conductivity phase of the diode (5). Another simplification of the circuit according to fig. 2 can be obtained by integrating the current limiting function of the resistor (13) in the transformer (1). To do this, the transformer (1) can be designed so that

  limit the current in the conductivity phase of the thyris-

  tor (12). This current limitation can be carried out by dimensioning the resistances of the primary winding (2)

  and / or the secondary winding (3). It can also be

  ment realized by a corresponding configuration of the induc-

  leakage transformer (1).

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Claims (6)

  1. Stabilization circuit for a half-wave voltage rectified from the AC mains voltage with a semiconductor element with longitudinal passage between a capacitor and a rectifier and a reference voltage element on the pilot pole of the element semiconductor with longitudinal passage, characterized in that the semiconductor element with longitudinal passage is an electronic switch (12) which switches when the half-wave voltage has reached a value which is higher than the voltage reached in a capacitor of smoothing (6) and as long as this is smaller than the reference voltage, and is blocked when the half-wave voltage is less than or equal to the voltage on the smoothing capacitor and a current limitation (13) is provided for the current going to the capacitor of   smoothing (6) when the switch (12) is switched.   2. Stablization circuit according to claim 1, character-   risk that the electronic switch (12) switches when the voltage on the smoothing capacitor (6) is less than the reference voltage at least the value of the voltage   the electronic switch (12).   3. Stabilization circuit according to claim 1 or 2, characterized in that the electronic switch is a thyristor (12) or a triac.   4. Stabilization circuit according to one of claims   previous, characterized in that a resistance is provided   ohmic (13) for current limitation.   5. Stabilization circuit according to one of the claims   above, characterized in that, for current limitation, a transformer (1) placed in front of the rectifier (4) 9 2709890 is sized accordingly.   6. Stabilization circuit according to one of claims   previous 2 to 5, characterized in that between the cathode and the trigger of the thyristor (12) respectively of the triac, there is a resistor (10) and that a diode (14) is switched between   the trigger and a resistor (9) located on the rectifier sister (4).