WO2005017933A1

WO2005017933A1 - Device and method for controlling electric switching devices

Info

Publication number: WO2005017933A1
Application number: PCT/EP2004/004606
Authority: WO
Inventors: Bernd Trautmann; Mikko Koivisto; Norbert Mittlmeier
Original assignee: Siemens Aktiengesellschaft
Priority date: 2003-07-17
Filing date: 2004-04-30
Publication date: 2005-02-24
Also published as: DE10332595B4; CN100461323C; DE10332595A1; CN1830048A; EP1647040B1; EP1647040A1

Abstract

The aim of the invention is to optimise the displacement of the armature of an electromagnetic switching device, in particular a contactor or relay, during the closing operation. To achieve this, the acceleration of the armature is controlled in such a way that the contacts or magnetic components of the switching device meet at an appropriately defined speed. The advantage of the invention is that the de-excitation of the solenoid is accelerated by a negative field voltage, reducing the time constant of the control process.

Description

description

Device and method for controlling electrical switching devices

The present invention relates to a control device for controlling a magnetic actuator or an electrical switching device, in particular a contactor or relay, which has an armature, with a receiving device for receiving or detecting a movement quantity with respect to the armature and / or a motion associated therewith Contact and a control device for controlling or regulating the movement of the armature or the contact. Furthermore, the present invention relates to a corresponding method for controlling a magnetic actuator or an electrical switching device.

When contactors are switched on, the magnetic tensile force must overcome the opening spring forces. It should be taken into account that when the main contacts are closed by a contactor, the spring forces increase to about five times the value at a defined distance from the closed position. Nevertheless, it must also be ensured in this area that the contacts close at a minimum speed, but the closing speed is not too high either. It is advantageous for the service life of a contactor if the impact speed of the main contacts is limited to reduce the switch-on burnup. This reduces mechanical bouncing when the contacts meet and the associated occurrence of arcs, which increases the electrical life. It is also advantageous if the magnet system closes gently, which leads to an increase in the mechanical life.

Such preferred closing movements can essentially be achieved by a control system for controlling the magnet system. For example, in the publications EP 0 865 660 and DE 195 35 211 regulate the magnetic flux. Either a constant value or a position-dependent value of the magnetic flux is aimed for. In any case, the setpoint of the magnetic flux must be so high that an excess traction can always be ensured. The flow control can prevent very high impact speeds, but even in favorable cases, relatively high impact speeds of around 0.8 m / s are still achieved, as the simulation according to FIG. 1 shows. The uppermost diagram in FIG. 1 shows the voltage at the coil with a solid line, the mains voltage with a dashed line and the current through the coil with a dotted line. The voltage on the coil is switched on and off according to the control cycles. At the beginning, the voltage on the coil is switched on and remains on until a predetermined magnetic flux (solid line in the middle diagram) is reached. The current (dotted line in the top diagram) increases rapidly in this time range in accordance with the usual switch-on behavior of an inductor. By de-energizing the voltage, the current then remains approximately constant and then gradually decreases to very small values as the opening between the contacts becomes smaller.

The middle diagram in FIG. 1 shows, in addition to the flux multiplied by the number of turns N (solid line), which is regulated to a constant value, the spring force (dashed line) and the magnetic force (dotted line). At the beginning of the closing process, the spring force is higher than the magnetic force, so that the contact carrier with the contacts is not yet moving. After a certain time, the magnetic force exceeds the spring force, whereupon the contacts move relative to one another. Only after this point in time is the flow regulated to a constant value so that the contacts can move towards each other. Just before closing, the spring force suddenly increases several times, as mentioned at the beginning. With the reduction of the opening gap when closing, the magnetic force (dotted line) increases sharply.

In the bottom diagram the path (dashed line) and the speed (solid line) are also plotted against time. The speed of the contacts to each other increases steadily when closing and reaches a peak when the contacts meet, where the spring force also increases by leaps and bounds. The speed is initially reduced due to the increased spring force. Due to the constant flow, however, it increases slightly again up to the closed position. Closing also takes place at the relatively high speed of about 0.8 m / s as already mentioned.

In the further document DE 195 44 207 a special method for regulating the speed when closing the contacts of a contactor is described. This method has the same disadvantages as simpler speed controllers. The controller switches off when the set speed is exceeded and switches on again when the set speed is undershot. In the special example, the controller switches off and on only once during the entire closing movement. The electromagnetic time constant and the inertia of the mechanics cause very large deviations from the speed setpoint. A simulation of this speed control is shown in FIG. 2. In the individual diagrams, the same quantities as in FIG. 1 are shown in their time course. At the beginning of the closing process, the voltage on the coil is switched on (see the solid line in the top diagram of FIG. 2). The voltage is only switched off again when the speed of the contacts to one another reaches the value 0.5 m / s (compare solid line in the bottom diagram of FIG. 2). While the voltage on the coil is switched on, the current through the coil increases (dotted line in the top diagram). After switching off the voltage drops the current gradually decreases. According to the current, the magnetic flux (solid line in the middle diagram) and the magnetic force (dotted line) increase to an absolute or local maximum until the voltage is switched off. For the speed (solid line in the bottom diagram in FIG. 2), this means that it continues to increase even after the voltage has been switched off, since the current and thus the magnetic force decrease only very slowly. The speed reaches a height of about 1.0 m / s when the contacts hit it and then drops due to the increased spring force (see dashed line in the middle diagram) to about 0.6 m / s when the components of the magnet system meet , The path of the contacts to one another, ie the opening of the contacts, decreases steadily when closing, similarly to the control according to FIG. 1.

The requirements for the closing movement mentioned at the outset are not adequately met in both documented regulations. The object of the present invention is therefore to propose a control device or a corresponding method with which a smooth closing of the contacts, for example of a contactor, is possible.

According to the invention, this object is achieved by a control device for controlling a magnetic actuator or an electrical switching device, in particular a contactor or relay, which has an armature, with a recording device for recording or recording a movement variable with respect to the armature and / or connected with it and a control device for controlling or regulating the movement of the armature or the contact, the acceleration device of the armature or the contact being controllable or regulatable with the control device.

Furthermore, a method is provided according to the invention for controlling a magnetic actuator or an electrical switching device, in particular a contactor or relay, which has an armature, by recording or detecting a movement quantity with respect to the armature and / or an associated contact and controlling or regulating the movement of the armature or the contact, the acceleration of the armature or the contact being controlled or regulated.

With the acceleration control according to the invention, it is possible that the impact speed can be limited to, for example, 0.4 m / s to 0.5 m / s. Knowledge of the spring force curve is not necessary at these speeds.

The distance traveled or the position is preferably recorded or recorded as the movement variable. However, the speed and / or the acceleration of the armature can also be recorded directly.

The control in the control device can be carried out on the basis of a target curve which represents the relationship between speed and position or acceleration and position. It can be calculated in advance whether the target curve will be exceeded or undershot in a certain position and a corresponding decision can be used as the basis for controlling the coil.

The setpoint curve preferably comprises a region which includes the contact contact and expediently also the magnetic contact. This allows the movement of the contacts to be regulated even after the contact has been made.

The recording device can comprise a displacement sensor, from the signal of which speed and / or acceleration for the control is derived by analog or digital differentiation. The displacement sensor can be implemented by a coil, the current of which is measured and the magnetic flux of which is determined from the integral of the induced voltage, so that the position of the contacts can be calculated can be determined. For this purpose, a special measuring coil can be used, which is attached to the magnet system of the magnetic actuator or the electrical switching device, ie to its drive coil. This measuring coil is then independent of the current-carrying drive coil, so that the flow can be measured precisely.

The control device can furthermore have a processor and a semiconductor switch, wherein the semiconductor switch can be used for switching a drive coil on and off and the processor for controlling the semiconductor switch is connected to the latter.

In addition, the control device according to the invention can have a freewheeling circuit in which a current is reduced by a counter voltage when a drive coil is switched off. The current can thus be reduced more quickly, so that the regulation is correspondingly less sluggish.

The distance between two contacts or two magnetic components for regulating the acceleration can advantageously be taken into account in the control device. This means that a different control behavior can be achieved in the vicinity of the closed position than in the open position.

The control devices according to the invention in all their variants can optionally be integrated directly into electrical switching devices, in particular contactors and relays.

The present invention will now be described with reference to the accompanying

Drawings explained in more detail, in which:

1 shows simulation diagrams for a control according to the prior art; 2 shows simulation diagrams for an alternative control according to the prior art; 3 shows a block circuit diagram of a contactor coil controlled according to the invention;

4 shows a setpoint curve for the control;

5 shows a family of functions for determining the path from the current and flow signal;

6 shows simulation diagrams for the acceleration control according to the present invention and

7 shows a circuit diagram for the rapid de-excitation of contactors.

The exemplary embodiments listed below represent preferred embodiments of the present invention.

Since a pure speed control is too sluggish, the acceleration is used as a control variable in the method according to the invention. 3 shows a basic circuit diagram for this. A contactor coil Ls is supplied with mains voltage by a controller RG. The regulation is carried out by means of a setpoint curve in which the speed v is plotted over the position s.

The position s as a manipulated variable is determined with the help of a measuring coil LM. For this purpose, the voltage Uϊ induced in the measuring coil LM and the current I flowing through the coil LM are detected with the aid of an evaluation circuit. The magnetic flux can be determined from the induced voltage by integration. The position s can be determined on the basis of a defined relationship between the flux and the current I flowing through the coil LM. It is forwarded to the RG controller as a manipulated variable. According to the control principle described in more detail below, the force on the armature in the contactor coil Ls or its acceleration is regulated to a defined value.

FIG. 4 shows the setpoint curve “speed over position * used for the control. With an air gap of 3.8 mm, in any case before closing the Main contacts, the speed should be about 0.5 m / s and should be maintained until the magnet system closes. It should be noted that the main contacts already come into contact a predefined distance before the armature hits the yoke of the magnet system. The starting point for closing is the rest position (off position) with zero speed of the armature or moving contact. In each position or size of the air gap, an attempt is made according to a first embodiment of the present invention to set the acceleration in such a way that the speed at 3.8 mm air gap reaches the value 0.5 m / s if this acceleration is kept constant. This means that when calculating an acceleration value to be used, it is determined in each measurement time step whether the current speed and the current acceleration exceed or fall below the corner point 0.5 m / s at 3.8 mm of the speed curve if the current one Acceleration is maintained. Accordingly, the drive coil of the magnet system is switched on or off.

The setpoint curve shown in FIG. 4 can also have a different course. For example, between the closed position (0 mm) and the 3.8 mm position, at which the speed is regulated to 0.5 m / s, further corner points can be defined, if necessary, to ensure the mechanics of the

Closing of the electrical switching device may take better account.

In the selected exemplary embodiment, a distance, speed or acceleration sensor is not used directly to detect the corresponding variables. Rather, the position is derived from the current and flow signals from the measuring coil LM.

5 shows in a family of curves the relevant mathematical relationship Ψ = f (I, x). From the family of curves, one can clearly see a known current and a known flow Opening width of the contacts can be closed. According to a simple solution approach, the path s can be determined from the curves using a third or fifth degree polynomial. The value of the path s determined on the basis of this family of curves is transmitted according to FIG. 3 by the evaluation unit AW to the controller RG.

Simulation results of the circuit according to the invention with acceleration control are shown in the diagrams in FIG. 6. The quantities shown correspond to those of FIG. 1 and FIG. 2. FIG. 6 also shows the switching-on movement of a contactor over time. In the ideal case, the switch-on movement runs along the predetermined setpoint curve of FIG. 4. In this case, control is made for constant acceleration. However, if points next to the setpoint curve are determined as actual values during the switch-on process, the acceleration is tracked in such a way that the corner point (compare arrows in FIG. 4) is reached again. Such a deviation from the setpoint curve is particularly important when using rectified AC voltage for driving the drive coil, since the current drops lead to actual values below the setpoint curve.

As can be seen from the uppermost diagram in FIG. 6, the voltage at the drive coil is first switched on, as is also the case in the example in FIG. The current (dotted line) increases accordingly rapidly. As soon as the current has reached a certain value, the control starts by switching the voltage on and off. It should be noted that a negative voltage, ie. H. a counter voltage is applied so that the current or flow can be lowered more quickly if necessary.

The middle diagram of FIG. 6 shows that the magnetic force (dotted line) is kept constant above the spring force (dashed line) during the control. This is indicates that the force on the armature and thus its acceleration remains the same during the switch-on process.

When the speed of 0.5 m / s is reached (see the solid line in the bottom diagram of FIG. 6), the current and thus also the magnetic force is regulated somewhat downwards, so that the magnetic force corresponds to the amount of the counteracting spring force and the speed is thus maintained ,

When the contacts meet afterwards, when the spring force increases suddenly, the magnetic force (dotted line in the middle diagram) must be adjusted to maintain the speed. This is achieved by switching on the voltage on the coil (solid line in the top diagram) or increasing the current through the coil (dotted line in the top diagram). The short drop in speed when the contacts hit each other can thus be compensated (see the solid line in the bottom diagram). The distance covered by the contacts during the switch-on process (compare dashed line in the bottom diagram of FIG. 6) over time essentially corresponds to that of FIG. 1.

In the example shown here, a tracking acceleration control is carried out. This means that one or more setpoint points (vsoii, ssoii) are specified in a table or curve according to FIG. The current values for acceleration, speed and distance bakt, vakt and sakt are measured or evaluated. Based on the formula trest = (Sakt - Ssoll) / ((Vsoll + Vakt) / 2), a residual term trest is calculated, from the current state until the corner point (3.8 mm, 0.5 m / s) is reached FIG 4 remains. This remaining term is calculated according to the formula

Vsohalt = Vakt + bakt • trest a switching speed value vsch-αt is predicted with which the contacts would move towards one another at the switching time if the acceleration is maintained. The regulation criterion is now that the voltage at the coil is switched on when schait <Vsoii. Otherwise, if Vsohait> vsoii, the voltage on the coil is switched off.

The acceleration control described can be expanded in such a way that a further degree of freedom is introduced, which has an effect in particular at the start of the switch-on process. To calculate the speed vsohait at the time of switching, use the formula

Vschait = Vakt + k • bakt • trest a distance factor k is taken into account. This can be calculated as follows: = (Sakt - sρι) / (sj - SJ-1)

Here, j means a point on the nominal curve of FIG. 4. In this example, point j = 1 corresponds to the open position at akt = 0, point j = 2 corresponds to the position (3.8 mm, 0.5 m / s) and the point j = 3 corresponds to the closed position at s = 0 mm.

At the start of the switch-on process, k = 0, while at the end of the switch-on process, k = 1. This means that the actual acceleration bakt at the start of the switch-on process has practically no influence on the control. Rather, the regulation at the beginning of the switch-on process is only dependent on the current speed value, which results in a speed regulation in this phase. At the end of the switch-on process, the speed control is replaced by the acceleration control.

A very simple acceleration control can also be used as a variant of the acceleration controls described above. This consists only in the specification of a table or function of the acceleration depending on the path bsoiι (s). The current acceleration bakt and the current Rapid movements are measured or evaluated. For control purposes, the voltage at the coil is switched on when bakt <bsoii (sakt). In the event that bakt> bsoii (sakt), the voltage is switched off.

As already mentioned and shown in connection with FIG. 5, the position can be determined from the measurement of the current and the flow. According to a first embodiment, the flux measurement, which takes place indirectly via a voltage measurement, can take place with the aid of a separate measuring winding, in which an induced voltage U is measured on an independent measuring coil LM according to FIG. The flow is then calculated by means of numerical integration over the induced voltage Uι or determined with the aid of an analog circuit.

According to a second embodiment, the voltage measurement for determining the flux is determined directly on the excitation winding or drive coil. For exact determination of the winding voltage Uw, the winding resistance is corrected from two integration intervals during the current rise without movement. For this purpose, for example, an interval 1 of 1 = 0 to I = 0.5 A and an interval 2 of 1 = 0 to I = 1.0 A are specified. An integral over the current HO and an integral over the voltage IU01 are determined for the interval 1. A corresponding integral 1102 over the current and an integral IU02 over the voltage are also calculated for the interval 2. The ohmic resistance of the coil is calculated from the formula R = (IU02 - 2 • IU01) / (1102 - 2 • 1101). Knowing the current i can according to the formula

Uι = Uw - R • i the induced voltage Ui can be calculated from the winding voltage Uw. In order that the magnetic flux can be broken down more quickly when the acceleration control described above is de-energized, a counter-voltage must be generated in a freewheeling circuit. In the uppermost simulation diagram of FIG. 6, this negative counter voltage is indicated, as already mentioned. 7 shows a circuit diagram according to which a contactor coil Ls can be controlled. A capacitor C and a control circuit RG (see FIG. 3) are supplied with DC voltage via a rectifier GL. The contactor coil Ls is supplied via a bridge circuit consisting of two transistors T1 and T2 and two diodes D1 and D2, which is also supplied with the DC voltage. When the contactor coil is switched on, the current flows from the rectifier GL via the transistor T1, the contactor coil Ls, the transistor T2 diagonally opposite the transistor T1 and back into the rectifier. When the contactor coil Ls is switched off, however, the current flows via the diode D2, the contactor coil Ls, the diode D1 diagonally opposite the diode D2 and the capacitor C parallel to the rectifier GL. The capacitor C is already charged to the amplitude of the mains voltage Uc and is available as a counter voltage source. If the capacitance of the capacitor C is very large, the rate of excitation of the contactor coil Ls is approximately identical to the rate of de-excitation. However, if the capacitance of the capacitor C is chosen to be small, the counter voltage increases due to the reduction of the magnetic flux in the contactor coil Ls to the value U'c. This results in the following energy change in the capacitor:

AE _C = - C - (U ' _C ² -U _C ² ) As a result of this voltage rise at the capacitor, the rate of excitation is greater than the rate of excitation. The capacitor should be dimensioned so that it can absorb the maximum occurring magnetic energy Eunax from the contactor coil Ls (ΔE _C = E _imax ).

Claims

claims

1. Control device for controlling a magnetic actuator or an electrical switching device, in particular a contactor or relay, which has an armature with

a recording device for recording or recording a movement variable with respect to the armature and / or a contact connected therewith and

- A control device (RG) for controlling or regulating the movement of the armature or the contact d a d u r c h g e k e n n z e i c h n e t, d a s s

- With the control device (RG) the acceleration of the armature or the contact can be controlled or regulated.

2. Control device according to claim 1, wherein the movement quantity is the distance covered (s).

3. Control device according to claim 1 or 2, wherein the control in the control device (RG) can be carried out on the basis of a target curve which represents the relationship between speed and position.

4. Control device according to claim 1 or 2, wherein the control in the control device (RG) can be carried out on the basis of a target curve, which represents the relationship between acceleration and position.

5. Control device according to claim 3 or 4, wherein the desired curve includes the area of the contact contact.

6. Control device according to one of claims 3 to 5, wherein the target curve includes the area of the magnetic contact.

7. Control device according to one of the preceding claims, wherein the receiving device comprises a displacement sensor, speed and / or acceleration can be derived from the signal thereof by analog or digital differentiation.

8. Control device according to claim 7, wherein the displacement sensor has a coil (L _s ), the current of which is measured and whose magnetic flux is determined from the integral of the induced voltage, so that the position of the armature or of the contact can be determined therefrom.

9. Control device according to one of claims 1 to 6, wherein the receiving device comprises a speed sensor, from whose signal path and acceleration of the armature or the contact can be derived by analog or digital differentiation or integration.

10. Control device according to one of the preceding claims, which has a measuring coil (L _M ) for determining the magnetic flux, which can be attached to a drive coil of the magnetic actuator or the electrical switching device and is independent of this.

11. Control device according to one of the preceding claims, which has a processor and a semiconductor switch, wherein the semiconductor switch can be used for switching a drive coil (L _s ) on and off and the processor for controlling the semiconductor switch is connected to the latter.

12. Control device according to one of the preceding claims, which has a freewheeling circuit in which a current can be reduced by a counter voltage when a drive coil is switched off.

13. Control device according to one of the preceding claims, wherein in the control device (RG) the distance between two contacts or two magnetic components can be taken into account for the control of the acceleration.

14. Electrical switching device, in particular contactor or relay with a control device according to one of the preceding claims.

15. A method for controlling a magnetic actuator or an electrical switching device, in particular a contactor or relay which has an armature

- Recording or capturing a movement variable with respect to the armature and / or a contact associated therewith and - Controlling or regulating the movement of the armature or the contact d a d u r c h g e k e n n z e i c h n e t, d a s s

- The acceleration of the armature or the contact is controlled or regulated.

16. The method according to claim 15, wherein the movement quantity is the distance covered.

17. The method according to claim 15 or 16, wherein the control is carried out on the basis of a target curve which represents the relationship between speed and position.

18. The method according to claim 15 or 16, wherein the control is carried out on the basis of a target curve which represents the relationship between acceleration and position.

19. The method of claim 17 or 18, wherein the target curve includes the area of contact contact.

20. The method according to any one of claims 17 to 19, wherein the target curve includes the area of magnetic contact.

21. The method according to any one of claims 15 to 20, wherein the movement quantity is recorded by a displacement sensor, from the signal of which speed and / or acceleration is derived by analog or digital differentiation.

22. The method according to claim 21, wherein the displacement sensor comprises a coil (L _s ), the current of which is measured and whose magnetic flux is determined from the integral of the induced voltage, from which the position of the armature or contact is subsequently determined.

23. The method according to any one of claims 15 to 20, wherein the movement quantity is determined with the aid of a speed sensor.

24. The method of claim 21 or 22, wherein the magnetic flux is measured by a measuring coil (L _M ) which is attached to the drive coil of the magnetic actuator or the electrical switching device and is independent of this.

25. The method according to any one of claims 15 to 24, wherein the current when switching off a drive coil (L _s ) of the magnetic actuator or the electrical switching device is reduced by a counter voltage in a freewheeling circuit.

26. The method according to any one of claims 15 to 25, wherein the distance between two contacts or two magnetic components of the magnetic actuator or the electrical switching device is taken into account for the regulation of the acceleration.

FIG 1 FIG 2

Spg M Current [A] Voltage to voltage at .00 of the coil of the coil θ.50 Mains voltage Mains voltage Current through current through