FR2863816A1 - Electric fence`s electrical resistance parameters measuring method, involves measuring parameters which are representative of electrical resistance of electric fence during voltage pulse - Google Patents

Abstract

The method involves delivering a voltage pulse by an electric fence through an output transformer (10). Parameters which are representative of the electrical resistance of the electric fence are measured during the voltage pulse using a measuring circuit (25). The parameters also include variable amplitude of a voltage taken back to a primary winding (9) of the output transformer. An independent claim is also included for an electric fence for measuring parameters representative of its electrical resistance.

Description

The invention relates to an electric fence energizer.

  The effectiveness of an electric fence depends on the level of invasion of the fence by the plants. The higher the number of plants affecting the fence, the lower the electrical resistance at the x output terminals of the fence energizer.

  When this electrical resistance is high (absence of plants affecting the fence), if an animal touches the fence, it receives most of the energy of the deterrent pulse applied to the fence, and it clearly perceives the effect deterrent. On the contrary, when the electrical resistance is low (presence of many plants affecting the fence) the energy of the deterrent pulse is divided between the plants and the animal, which receives only a part, and the deterrence is clearly less perceived.

  The electrical resistance seen at the output terminals of the energizer is therefore a parameter which it is important to know in order to optimize the operation of the energizer.

  Patent FR 2,640,845 describes a fence energizer comprising a circuit for measuring the degree of isolation of the fence installed at the secondary of the output transformer of the energizer.

  This arrangement has the disadvantage of taking a significant part of the energy of the pulse to supply the measurement circuit. In addition, if the energizer is equipped with an alarm system to warn of the inefficiency of the fence due to invasion by the plants, this alarm system can not be fed to the secondary of the output transformer because of the very high voltage prevailing therein, and it is necessary to provide an information transmission, electrically isolated, between the secondary of the output transformer and the alarm system, as in the patent FR 2 711 885.

  The document EP 0 374 055 describes a fence energizer in which the degree of isolation of the fence is measured by means of the voltage at the midpoint of a voltage divider connected in parallel with the primary of the output transformer: the duration the first alternation of this voltage is representative of the degree of isolation of the fence.

  WO 95/18520 discloses a fence energizer having two storage capacitors each connected to a primary winding. In parallel on the storage capacitors are mounted voltage dividing circuits respectively supplying the control microcontroller of the energizer signals representative of a high output load and a low output load.

  From these signals, the microcontroller controls, if necessary, the discharge of the second capacitor after the discharge of the first capacitor. The disadvantage of this energizer is its complexity, because it comprises separate circuits on the one hand for the discharge of the capacitors, on the other hand for the detection of the output loads.

  WO 03/55284 discloses a fence energizer measuring the fence voltage at the primary of the output transformer. To perform the measurement on the first half cycle, an LC filter is used, which entails a significant cost.

  When the duration of the first halfwave is measured, the fact of bringing the voltage back to a microcontroller requires the availability of an expensive microcontroller.

  An object of the present invention is to provide a control circuit energizer which may be a microcontroller, having at the output transformer primary a simple circuit for measuring the electrical closing resistance.

  Another object of the present invention is to provide a control circuit energizer which can be a microcontroller, using for the measurement of the electric closing resistance a simple parameter and easy to measure.

  Yet another object of the present invention is to provide a method of measuring a parameter representative of the electrical resistance of a fence.

  The invention relates to a method for measuring a parameter representative of the electrical resistance of an electric fence to which an energizer delivers voltage pulses via an output transformer, by means of the measurement of a voltage brought back to the primary of the output transformer during said voltage pulses, characterized in that said parameter is the second alternation of said voltage brought back to the primary.

  According to one characteristic, the parameter measured is the amplitude of the second alternation of the voltage brought back to the primary. The invention also relates to a fence energizer for implementing the aforementioned method, comprising: a power supply, a charge transformer at least one storage capacitor, an output transformer and a control circuit which may be a microcontroller; each storage capacitor being connected in series with the primary of the output transformer, a thyristor being connected in parallel with the series circuit formed by a storage capacitor and the primary of the output transformer to provide the discharge, under control of the circuit control which can be a microcontroller, the storage capacitor in the primary of the output transformer; so as to deliver to the secondary of the output transformer a voltage pulse applied to the fence, characterized in that it comprises: a measuring circuit of a parameter representative of the electric resistance of the fence; - Between the primary of the output transformer and the measuring circuit, a semiconductor component whose conduction direction ensures to transmit first to the measuring circuit that the second alternation of the primary voltage.

  According to other characteristics: the parameter representative of the electrical resistance of the fence is the amplitude of the second alternation of the primary voltage; in parallel with the primary of the output transformer, there is arranged a voltage divider whose midpoint is at a voltage proportional to the voltage across the primary of the output transformer, the semiconductor component being mounted between the midpoint and the measuring circuit; between the point common to the semiconductor component and the measurement circuit and, on the other hand, the ground, is mounted a capacitor for storing the maximum value of the voltage at said midpoint; - Between said midpoint and the ground is mounted a parasitic filter capacitor; the measuring circuit is connected to a display, to display the value of a characteristic quantity of the state of the fence, ie of the pulse applied to the fence; the semiconductor component is a diode; whose anode is connected to said midpoint and the cathode to the measuring circuit; the semiconductor component is a transistor whose base is connected to the midpoint, the emitter to the measurement circuit, and the collector to the power supply; the measuring circuit is integrated in the microcontroller; the power supply consists of a mains voltage, an accumulator, or a battery possibly fed by a solar panel in parallel.

  Other characteristics appear from the following description given with reference to the accompanying drawings in which: - Figure 1 shows schematically a fence energizer of the prior art; FIG. 2 represents the shape of the output pulse at the secondary of the output transformer of the energizer of FIG. 1; FIG. 3 represents the shape of the primary pulse of the output transformer, corresponding to the output pulse of FIG. 2; FIG. 4 represents an exemplary embodiment of the measurement circuit of the parameter representative of the electrical resistance of the fence of the energizer of FIG. 1; - Figure 5 shows another embodiment of the measuring circuit of the representative parameter of the electrical resistance of the fence of the energizer of Figure 1.

  FIG. 1 represents the simplified electrical diagram of a fence energizer described in the document FR 2 787 964. In this diagram, a power supply 1, which may be a mains voltage, an accumulator, or a battery possibly powered by a panel. parallel solar, feeds a load transformer 2 and a control circuit which can be a microcontroller 3. The load transformer 2 feeds, via diodes 4, 5, two storage capacitors 6, 7 mounted in parallel. The number of capacitors is not limited to two, but can be one or more.

  The primary 9 of the output transformer 10 is connected between the respective common point 8 to the two capacitors 6, 7 and the ground 11 of the circuit.

  A thyristor 12, 13 respectively is mounted between on the one hand the respective common point to a diode 4, 5 and a storage capacitor 6, 7, and on the other hand the ground 11.

  Each of the thyristors 12, 13 is thus mounted in parallel on a capacitor 6, 7 and the primary 9 of the output transformer. The thyristors 12, 13 are controlled by the control circuit which may be a microcontroller 3. The secondary 14 of the output transformer 10 is connected on the one hand at 15 to the electric fence, on the other hand 16 to ground.

  The operation of this energizer is well known. The charge transformer 2 charges the capacitors 6, 7 at a voltage of a few hundred volts, for example 600V. On command of the control circuit which can be a microcontroller 3, a thyristor 12 or 13 is made conductive with a period of the order of one second, but which can be several seconds.

  When a thyristor is made conductive, for example 12, the corresponding capacitor, 6 in this case, discharges through the thyristor 12 and the primary 9 of the output transformer 10. This discharge generates at the secondary 14 of the output transformer 10 a impulse whose amplitude is a few kilovolts, for example 6 to 10 kV. This impulse, applied to the electric fence, is felt by an animal that touches the fence as having a deterrent effect.

  In the example of FIG. 1, the control circuit which may be a microcontroller 3 can be programmed to trigger the conduction of a thyristor 12, then after a delay allowing the output transformer to return to its initial state, the conduction of the thyristor 13, so as to deliver at closure two successive pulses perceived by the animal as a single dual energy pulse.

  FIG. 2 gives a typical representation of the voltage S existing between the terminals 15 and 16 of the secondary 14 of the output transformer 10 during the discharge of a capacitor 6 or 7. In the absence of plants, the pulse presents a maximum voltage S1 (curve in solid line), then a reversal of the voltage to a minimum S2, then a damped oscillation towards zero.

  In the presence of plants affecting the fence, the electrical resistance seen from the secondary 14 is lower than in the absence of plants, and the pulse has substantially the same pace, but generally reduced scale. The maximum voltage S3 (dashed curve) is smaller than S1, the zero crossing point is earlier, and the minimum voltage S4 is of less magnitude than S2.

  The measurement of the maximum voltage S1 or S3 makes it possible to deduce the value of the electrical resistance seen from the secondary and to estimate the degree of isolation of the fence. However, as described above, the measurement made at the secondary of the output transformer 10 is energy consuming.

  FIG. 3 represents the voltage E existing, at the same times as in FIG. 2, across the terminals of the primary 9 of the output transformer 10, measured between the points 11 and 8 and corresponding to the voltage S at the secondary 14. As long as the thyristors 12 and 13 are blocked, the voltage E at point 8 is virtually zero. When the control circuit which may be a microcontroller 3 makes a thyristor conductive, 12 for example, the voltage at point 8 (FIG. 1) falls sharply and in FIG. 3 goes from point 17 to point 18. The capacitor 6 is discharged then through the thyristor 12 and the primary 9 of the output transformer, and the voltage E rises gradually from point 18 to the zero value. During this phase of going back to zero, energy is stored in magnetic form in the output transformer 10. Then it is restored (thanks to a diode not shown mounted between the ground and the common point of the diodes 4 and 5) and the voltage E rises to a maximum before going back to zero. The electrical resistance seen from the secondary 14 of the output transformer 10, brought back to the primary 9, depends on the invasion of the fence by the plants.

  In the absence of plants (curve in solid line) the tension goes up to the maximum El. In the presence of plants, (dashed curve) 15 the tension goes up to the maximum E2 lower than E1.

  At the primary 9 of the output transformer 10, the value of the maximum of the voltage E is therefore representative of the electrical resistance of the fence. The amplitude of the maximum of the voltage E at the primary, during the positive half-cycle of the voltage E, is used as a parameter representative of the electric resistance of the fence. To take this parameter into account, a complementary circuit is inserted in the diagram of FIG.

  In FIGS. 4 and 5 in parallel on the primary 9 of the output transformer 10, between the point 8 and the ground 11 is mounted a voltage divider consisting of two resistors 19 and 20.

  The voltage at the midpoint 21 of the voltage divider is proportional to the voltage E across the primary 9 of the output transformer. Between the midpoint 21 and the ground 11 is mounted a capacitor 22 parasite filtering can exist on the voltage E. Moreover, the midpoint 21 of the voltage divider is connected indirectly via a semi component The measuring circuit 25 is connected either to a display 26 which is preferably a liquid crystal or light-emitting diode digital display, for example, or to a digital display. control circuit which may be a microcontroller for varying an operating parameter of the energizer, for example the voltage, the energy of the pulse, the difference between the pulses or the sub-pulses.

  In the case of FIG. 4, between the midpoint 21 of the voltage divider and the measuring circuit 25, the semiconductor component is a diode 23 whose anode is connected to the midpoint 21 and the cathode to the measuring circuit 25. This diode transmits first only the second alternation of the voltage at point 21 in the example described the positive half cycle, as well as subsequent alternations of the same parity. A capacitor 24 is mounted between, on the one hand, the point common to the diode 23 and on the measurement circuit 25, and on the other hand the ground 11, for storing the maximum value of the voltage at the point 21, which is an image of the voltage E across the primary 9 of the output transformer. The measuring circuit 25 measures the voltage stored on the capacitor 24 and deduces therefrom either a characteristic quantity of the state of the closure, for example the degree of isolation of the fence, or the value of the electric resistance of the fence, a characteristic quantity of the pulse applied to the fence, for example the value of the voltage applied to the fence, or any other parameter. The corresponding value is displayed by the display 26.

  In the case of FIG. 5, between the midpoint 21 of the voltage divider and the measuring circuit 25, the semiconductor component is a transistor 27. The base of the transistor 27 is connected to the midpoint 21, the emitter to the measurement circuit 25 and the collector to the supply 1. The base-emitter connection of the transistor 27 acts as the diode 23 of FIG. 4 to transmit only firstly the second alternation of the voltage at the midpoint 21, in the example describes the positive alternation, as well as the subsequent alternations of the same parity. The charging current of the capacitor 24 is taken from the general power supply 1.

  A not shown resistance is connected in parallel with the capacitor 24 to discharge the capacitor 24 between the measurements.

  The values of the resistors 19 and 20 of the voltage divider are chosen high so that the energy they collect during the discharge of the capacitor 6 is minimal. In the embodiment of FIG. 5, the base current of the transistor 27 is very low, which makes it possible to further increase the values of the resistors 19 and 20, the energy taken from the discharge of the capacitor 6 being in this case. insignificant case.

  The measurement circuit 25 may comprise a micro-programmed electronic integrated circuit, microcontroller type. The software stored in this case in the program memory orders the reading of the voltage across the capacitor 24 and deduces therefrom a characteristic quantity of the pulse applied to the fence, for example the value of the voltage of the pulse applied to the capacitor 24. the fence, or the output energy, or a characteristic quantity of the state of the fence, for example the value of the electrical resistance of the fence, or the degree of insulation of the fence, or any other parameter. It orders the display 2863816 of the measured quantity and, by a link not shown, transmits it to the microcontroller 3. The measurement circuit can be integrated in the microcontroller 3.

  According to the invention, the measurement method retains only the second alternation of the voltage brought back to the primary, and not the first alternation, which imposes the direction of conduction of the semiconductor component 23, 27. In this second alternation, the measured parameter may be the duration, amplitude, or energy of the alternation, or any magnitude equivalent to a characteristic of the impulse or state of the fence.

  The described embodiments are not limiting and the invention covers their technical equivalents. In particular, the number of storage capacitors is not limited to two, it can be one or more. Similarly, the voltage divider can be resistors or capacitors.

Claims (12)

  1. A method for measuring a parameter representative of the electric resistance of an electric fence to which an energizer delivers voltage pulses via an output transformer, by means of the measurement of a voltage reduced to primary of the output transformer during said voltage pulses, characterized in that said parameter is the second alternation of said voltage brought back to the prim area.   2. Method according to claim 1, characterized in that the parameter measured is the amplitude of the second alternation of the voltage brought back to the primary.   3. Closing energizer for carrying out the method according to claim 1, comprising: a power supply (1) a charge transformer (2), at least one storage capacitor (6), an output transformer (10) and a control circuit which may be a microcontroller (3); each storage capacitor (6, 7) being connected in series with the primary (9) of the output transformer (10), a thyristor (12, 13) being connected in parallel with the series circuit formed by a storage capacitor (6). , 7) and the primary (9) of the output transformer (10) for discharging, under the control of the control circuit which may be a microcontroller (3), the storage capacitor (6, 7) in the primary ( 9) of the output transformer (10); so as to deliver to the secondary (14) of the output transformer (10) a voltage pulse applied to the fence, characterized in that it comprises: - a measuring circuit (25) of a parameter representative of the electrical resistance the fence; Between the primary of the output transformer (10) and the measurement circuit (25), a semiconductor component (23, 27) whose conduction direction ensures that it does not transmit first to the measuring circuit (25) than the second alternation of primary voltage.   4. An electrifier according to claim 3, characterized in that the parameter representative of the electrical resistance of the fence is the amplitude of the second alternation of the primary voltage.   5. An electrifier according to claim 3 or 4, characterized in that it comprises in parallel on the primary (9) of the output transformer (10), a voltage divider whose midpoint (21) is at a voltage proportional to the voltage across the primary (9) of the output transformer (10), the semiconductor component (23, 27) being mounted between the midpoint (21) and the measuring circuit (25).   Fence energizer according to claim 5, characterized in that between the point common to the semiconductor component (23, 27) and the measuring circuit (25) and the ground (11). ), is mounted a capacitor (24) for storing the maximum value of the voltage at said midpoint (21).   7. fence energizer according to claim 5, characterized in that, between said midpoint (21) and the ground (11) is mounted a capacitor (22) for filtering parasites.   8. fence energizer according to one of claims 5 to 7, characterized in that the measuring circuit (25) is connected to a display (26), to display the value of a characteristic quantity of the state of the closing of the impulse applied to the fence.   9. fence energizer according to claim 5, characterized in that the semiconductor component is a diode (23), whose anode is connected to the midpoint (21) and the cathode to the measuring circuit (25).   2863816 14 10. Closing energizer according to claim 5, characterized in that the semiconducting component is a transistor (27), the base of which is connected to the midpoint (21), the emitter to the measurement circuit (25), and the manifold to the feed (1).   11. fence energizer according to claim 3, characterized in that the measuring circuit (25) is integrated in the microcontroller (3).   12. fence energizer according to claim 3, characterized in that the power supply (1) is constituted by a mains voltage, an accumulator or a battery, possibly supplied by a solar panel in parallel.