KR20050012795A - Device for regulating the voltage in generators by means of coil tapping and a control relay - Google Patents

Abstract

The present invention relates to an apparatus for automatically adjusting the voltage of a generator in accordance with a load current. The device is a first pair of clamps that can be connected to a generator clamp pair that carries a load current and diverts the generator voltage from the generator coil, a second that can be connected to the generator clamp pair and less than the first generator voltage from the generator coil. A control voltage is provided to a control circuit provided with a control relay 9 having a second clamp pair for inducing a generator voltage and a switch for switching a connection between said generator clamp pair and a first clamp pair or a second clamp pair. A third clamp pair. If the control voltage is greater than or equal to the upper threshold voltage of the control relay, the generator clamp pair connected to the first clamp pair by a switch is connected to the second clamp pair, while the control voltage is greater than the lower threshold voltage of the control relay. In the case of less than or equal, the generator clamp pair connected to the second clamp pair by a switch is connected to the first clamp pair. The apparatus according to the invention also comprises a bridge member having a varistor and bridging a connection made by a switch between the generator clamp pair and the first clamp pair, wherein the on-state voltage of the varistor is between two generator voltages. Above the difference but below the first generator voltage.

Description

DEVICE FOR REGULATING THE VOLTAGE IN GENERATORS BY MEANS OF COIL TAPPING AND A CONTROL RELAY}

The present invention relates to an apparatus for automatically adjusting the voltage of an electricity generator ("generator") in accordance with a load current. In particular, the invention relates to the use of such a device for regulating the voltage of a generator driven by a reciprocating engine.

Devices for regulating the voltage of a generator are known. In the case of an electric generator having an electromagnet for exciting an induction coil, the generator voltage can be matched to various load states, for example, by varying the magnetic flow using the induction coil while simultaneously changing the control current for the electromagnet. However, in the case of a generator that is permanently excited, such a simple voltage adjustment is not possible. In such a case, technically complex regulation technical measures are necessary for the voltage regulation, and such an operation is possible, for example, in the form of a loop contact along the main coil to adjust the number of working coils. A disadvantage of this case is the high likelihood of abrasion of the loop contacts, especially resulting from wear and spark impacts. In addition, an unavoidable coil short circuit is often generated, which results in an insignificant loss output. Another disadvantage is that short current interruptions can occur continuously during the switching process.

German Laid-Open Patent Application No. 26 59 600 describes a device for automatically adjusting the electric generator according to the load current, in which the regulation of the generator output voltage is carried out by means of a triac (connected to the winding extraction and star point). by shorting the partial coil of the phase with triac).

US Published Patent Application 2001/002802 describes a motor in which the rotation speed / moment characteristics are varied by converting the supply voltage to the winding traction of the stator phase coil.

German Patent Application No. 100 47 287 describes an apparatus and a method for generating various output voltages by an alternator, in which case the configuration of the connection of the stator windings for generating the various output voltages is a configuration circuit. Can be varied by

It is an object of the present invention to avoid complex regulation technical measures for matching generator voltages to various load states. In addition, no current interruption should occur during the switching process.

This object is achieved by the features of the independent claims in accordance with one proposal of the invention. Preferred embodiments of the invention are described by the features of the dependent claims.

In the present invention, an apparatus for automatically regulating the voltage of an electrical generator in accordance with a load current is provided, in which the first and second clamp pairs are provided for branching the first and second generator voltages in the generator coil. The second clamp pair as well as the first clamp pair may be connected to a pair of generator clamps inducing load current. Since there are always more winding coils between the first pair of clamps than between the second pair of clamps, the voltage branching out of the first clamp pair is always greater than the voltage branching out of the second clamp pair. While there are more coils between the first clamp pair than between the second clamp pair, not only the first clamp pair but also the second clamp pair may be connected to any location of the generator coil. As the first generator voltage, a generator main voltage, that is, a voltage branched from the complete winding of the generator, is preferably used. The second generator voltage is always a write voltage that is less than the generator main voltage.

The apparatus according to the invention is also provided with a third clamp pair, by which the control voltage for the control current circuit can branch. The control voltage preferably corresponds to the voltage difference between the first generator voltage and the second generator voltage. The control current circuit is preferably formed such that the circuit guides the current only from a predetermined on-stage voltage. Such a guide can be made for example by a zener-diode having an on-state voltage corresponding to the on-state voltage of the control current circuit.

The control current circuit is provided with a control relay having a switch for alternately connecting the generator clamp pair with the first and second clamp pairs connected to the generator coil. By displacing the switch of the control relay, if the control voltage branching out of the third clamp pair takes a value equal to or greater than the upper threshold voltage of the switching relay, the generator clamp pair connected by the switch to the first clamp pair is connected to the second clamp. Connected with a pair. When the control current circuit only guides current from the on-state voltage, the upper threshold voltage is released from the on-state voltage of the control current circuit, for example, the breakdown voltage of the zener-diode there and the release of the switching relay. It is generally calculated from voltage. On the contrary, when the control voltage is less than or equal to the lower threshold voltage of the switching relay, the generator clamp coupled with the second clamp pair by the switch is connected with the first clamp pair by the displacement of the switch. The lower threshold voltage is generally calculated from the on-state voltage of the control current circuit, for example from the breakdown voltage of the zener diode and the release voltage of the switching relay.

The release voltage of the switching relay is always less than the write voltage of the switching relay, and this is because of the switching hysteresis of the switching relay. The switching hysteresis is essential for the stable switching of the switching relay, because from the same upper and lower threshold voltages, i.e. from the same switching voltage for attraction and release, an unstable switching state can occur by continuous switching replacement. to be.

The spacing between the upper and lower threshold voltages, i.e. the width of the switching hysteresis, generally depends on the design of the switching relay. The relative position of the switching hysteresis can be varied by the design of the zener-diode disposed in the switching circuit. In this case, the smaller breakdown voltage of the zener-diode causes a shift in the switching hysteresis to the smaller control voltage, and vice versa. Zener-diodes are also used for potential leveling of switching hysteresis.

If there are further elements in the control current circuit, for example a rectifier-diode which preferably enables the use of a DC-controlled relay, in some cases the on-state voltages of the elements are also necessary for the switching of the control relay. Can be considered for the control voltage level.

The apparatus according to the invention also comprises a bridge member for bridging the connection of the first clamp pair and the generator clamp pair made by the switch. The bridge member has a voltage dependent resistor ("varistor"), which is used atypically because it is not as an overvoltage protector in this case, the resistor being above the difference between the first generator voltage and the second generator voltage. And an on-state voltage below the first generator voltage branching out of the first clamp pair. When the switch of the control relay connects the generator clamp pair with the first and second clamp pairs, the voltage actually does not drop at all along the connection of the generator clamp pair and the first clamp pair. The bridge member acts as a blocking member due to no potential difference and hence the current impermeability of the varistor. However, if the switch of the control relay is switched between the first clamp pair and the second clamp pair, during the switching process the potential of the first clamp pair is used in the varistor and the bridge member is interrupted by the open switch. It is used as a traditional member suitable for conducting load current through a connection between a pair and a pair of generator clamps. To prevent a short circuit when the switch connects the second clamp pair with the generator clamp pair, the conventional voltage of the varistor should be chosen such that the voltage is above the difference between the first generator voltage and the second generator voltage. Preferably, interruption of current during the switching process can be avoided by the bridge member.

In one preferred embodiment of the invention, the voltage regulation is within a tolerance range of ± 5%. This means that as soon as the nominal voltage falls below or exceeds 5%, the voltage is adjusted high or low. Similarly, it is also desirable for voltage regulation to be in the vicinity of approximately 50% -80% of the nominal load current in ohmic loads. If the load is ohmic-inductive, the switching point will move to a relatively high portion of the nominal load current in a corresponding manner. In particular, the device according to the invention is designed to be homogeneous with the implementation class G2 of the DIN 8528 standard, which makes the voltage regulation accuracy for the current generator device unified in the public network corresponding to the tolerance.

The invention is described in detail below with reference to the description of examples, in which case the accompanying drawings are cited.

1 is a circuit diagram of an apparatus according to the invention for regulating the voltage of a synchronous generator that is permanently excited.

2 is a diagram showing the change in phase voltage of the three-phase current phase dependent on the load current in ohmic load (dashed line) and ohmic-inductive load (solid line), and the switching caused by the device according to the invention. It is a process.

1 shows an exemplary circuit diagram of a device according to the invention for regulating the voltage of one phase of a synchronous generator that is permanently excited. Only generator coil 1 and generator clamps N, L1 are shown among the electrical generators. In the generator coil 1, the first clamp pair 1U1, 1U2 and the second clamp pair 1U1, 2U2 branch off the first and second generator voltages. The first pair of clamps 1U1, 1U2 surrounds a complete number of coils of generator coils, while the second pair of clamps 1U1, 2U2 surrounds a smaller number of coils. Since the induced voltage is proportional to the number of coils, the second generator voltage is always less than the first generator voltage. The second clamp pair as well as the first clamp pair may be connected with the generator clamps L1, N.

In order to connect the generator clamps L1, N with the first or second clamp pair, a switching relay 8 with a switch 9 is used. The switching relay 8 is in the control current circuit 2, and the circuit is connected to the clamps 2U2 and 1U2 by means of first and second clamp pairs, whereby the difference voltage between the first generator voltage and the second generator voltage. Is forked. Also within the control current circuit 2 is a zener diode 6 and a rectifier diode 7. The zener-diode 6 causes a blocking effect in such a way that the control current circuit 2 guides the current only when the zener-breakdown voltage is exceeded. Since the rectifier-diode 7 is used for rectifying alternating current, a DC-switching relay 8 can preferably be used.

The voltage induced between the clamp 1U1 and the clamp 2U2 is a predetermined upper threshold determined by the breakdown voltage of the zener-diode 6, the traditional voltage of the rectifier-diode 7 and the starting voltage of the control relay 8. As soon as the voltage is exceeded, a current that causes the control relay 8 to pull the switch 9 flows in the control current circuit 2. Thereby, the voltage applied to the generator clamp pairs N and L1 is switched from the higher voltage value 1U2 to the lower voltage value 2U2. In that case the load current causing the switching process is guided through the current circuit 4 of the second clamp pair. By reducing the load current between the clamps of the control current circuits 1U2 and 2U2, the control voltage branching there is further raised, and this synergistic action supports the switching process. In other words, the action of the load current on the voltage within the branch is maintained.

When the load current rises again, the branched control voltage drops, which action causes a new switching of the switching relay 8 as soon as the control voltage reaches the lower threshold voltage. The lower threshold voltage is predetermined by the breakdown voltage of the zener-diode 6, the on-state voltage of the rectifier-diode 7 and the release voltage of the control relay 8. The lower threshold voltage is always lower than the upper threshold voltage by the switching hysteresis of the switching relay. When the control voltage drops below the breakdown voltage of the zener-diode 6, no current flows further in the control current circuit 2. As the internal resistance increases between the clamps of the control current circuits 1U2 and 2U2 by switching from the second clamp pair to the first clamp pair by the load current, the control voltage is further lowered, which is the switching process. Support.

The interruption of the current flow during the switching is prevented by the varistor 10 disposed in the bridge member 5. The varistors do not allow electrical flow because they are high impedance in the de-energized state. On the contrary, when the voltage rises at the connection of the varistor, the varistor is inclined to a low impedance state at a specific on-state voltage to conduct current through the current circuit 3. When the switch 9 connects the first clamp pair with the generator clamp pair, no voltage actually drops through the connection of the bridge member-the varistor is high impedance and acts as a blocking member. While the switch 9 is switched from the first clamp pair to the second clamp pair, the potential of the clamp 1U2 is used in the varistor, whereby the varistor is brought into a low impedance state to conduct the load current. If the switch 9 connects the generator clamp pair to the second clamp pair, the conduction of the current is through the current circuit 4, whereby the varistor again becomes high impedance to block the current from flowing through the bridge member. . The same applies to the case where the switch 9 is switched from the clamp 2U2 to the clamp 1U2. When the on-state voltage of the varistor is higher than the difference between the voltages branching from the clamps 2U2 and 1U2, the switch 9 connects the generator clamp pairs N and L1 with the second clamp pairs 1U1 and 2U2. In this case, a short circuit is prevented through the current circuit 3. In order to keep the loss inside the varistor as small as possible, the switch 9 should be connected as quickly as possible.

2 shows an ohmic-inductive load in which the current and voltage are in phase, i.e. cosφ = 1, in which φ is the purely ohmic load (dashed line) corresponding to the angle between current and voltage. For the case of (solid line), the load is expressed in% of the nominal load current I _LN and the phase voltage U _Str expressed by% of the nominal voltage U _StrN and branched by the generator clamps L1, N The relationship of the current L _L is shown.

Voltage waveform 2 corresponds to the voltage of the first generator voltage branched from the first clamp pair 1U1, 1U2, while voltage waveform 1 corresponds to the smaller second generator voltage branched from the second clamp pair 1U1, 2U2. Corresponds to the voltage.

The switching process is based on a tolerance range of ± 7%. At idle (ie I _L = 0), the generator clamp voltage reaches nearly 107% of the nominal voltage and corresponds to the voltage diverged between clamp pairs 1U1 and 2U2.

Observe the ohmic load (dashed line). If the generator receives an electrical load starting from 0-load (dashed curve 1; I _L = 0) and the load current continuously increases, the switching threshold of the control relay (upper threshold voltage) at approximately 77% of the nominal load current. Is reached, the generator clamp L1 is connected with the clamp 1U2 of the first clamp pair. The result is a voltage jump of phase voltage from about 94% to about 101%. As the load current rises further, the phase voltage decreases according to the dashed curve 2.

Then, when the generator's load is relieved, that is, the load current is continuously reduced, until the voltage branching out of the generator clamp reaches the switching threshold (lower threshold voltage) of the switching relay at about 55% of the nominal load current. The voltage increases with dashed curve 2 and generator clamp L1 is connected with clamp 2U2 of the second clamp pair. The result is a voltage jump of phase voltage from about 105% to about 98%. If the load current is further reduced, the phase voltage increases with dashed curve 1. Finally, at idle (ie I _L = 0), the phase voltage reaches 107% of the nominal phase voltage.

The hysteresis of the control relay can be seen between the two switching thresholds. The peaks of the hysteresis are at about 77% and about 55% of the nominal load current. The area surrounded by the hysteresis depends on the relative spacing of the switching thresholds and the slope of the phase voltage.

The device according to the invention is provided three times in total in three three-phase currents, in order to regulate the phase voltage of each three-phase current. Particularly preferably, the device according to the invention operates at an inclined load, since the voltage decreases when the phase is under heavy load and the voltage increases when the phase is under heavy load.

In particular, the devices according to the invention can be arranged in a cascade with each other, in which case the spacing between the first generator voltage and the second generator voltage becomes narrower within the cascade, so that the voltage regulation is further subdivided. Is done.

One preferred use of the device according to the invention is to automatically adjust the voltage of the electric generator driven by the reciprocating engine according to the load current. In this case in particular, a synchronous generator driven by a diesel engine is dealt with. Electric generators which are permanently excited are preferred according to the invention.

Claims (13)

A device for automatically adjusting the voltage of an electric generator ("generator") in accordance with a load current, A first pair of clamps 1U1, 1U2, which can be connected with a generator clamp pair N, L1 carrying a load current, for branching the first generator voltage in the generator coil, A second pair of clamps 1U1 and 2U2 which can be connected with the generator clamp pairs N and L1 to induce a second generator voltage which is smaller than the first generator voltage in the generator coil, Third clamp pair 1U2, 2U2 for supplying a control voltage to the control current circuit 2, and A bridge member bridging the connection of the first clamp pairs 1U1 and 1U2 and the generator clamp pairs N and L1 made by the switch 9 and having a voltage dependent resistance (“varistor”) ( 5), The on-state voltage of the resistor is above the difference between the first generator voltage and the second generator voltage and below the first generator voltage branched out of the first clamp pair, The control current circuit 2 is provided with a control relay 8 with a switch 9 for switching the connection between the generator clamp pair N, L1 and the first clamp pair or the second clamp pair; The generator clamp pair (N, L1) connected with the first clamp pair (1U1, 1U2) by the switch (9) if the control voltage is greater than or equal to the upper threshold voltage of the switching relay. Is connected to the second clamp pair 1U1, 2U2, while the second clamp pair 1U1, 2U2 is provided by the switch 9 when the control voltage is less than or equal to the lower threshold voltage of the control relay. And the generator clamp pair (N, L1) connected with is configured to be connected with the first clamp pair (1U1, 1U2). The method of claim 1, And the control voltage of the control current circuit corresponds to the voltage difference between the first generator voltage and the second generator voltage. The method of claim 1, The voltage regulating device, characterized in that the control current circuit (2) passes the current simultaneously with reaching the on-state voltage. The method of claim 3, wherein Wherein the control current circuit (2) comprises a zener-diode (6), the on-state voltage of the diode corresponding to the on-state voltage of the control current circuit (2). The method of claim 1, The voltage regulation device, characterized in that the control current circuit (2) comprises a rectifier, in particular a rectifier-diode (7). The method of claim 1, The voltage regulating device, characterized in that said first generator voltage branched by said first clamp pair (1U1, 1U2) corresponds to a generator main voltage. The method of claim 1, And the voltage regulation is within a tolerance range of ± 5%. The method of claim 1, At ohmic load, the voltage regulation is at about 50% -80% of nominal load current. The method of claim 1, A voltage regulating device, characterized by the same type as the implementation classification G2 of the DIN 8528 standard. The method of claim 1, And the electricity generator is permanently excited. A system according to any one of claims 1 to 10, for each three-phase current 12. A system according to any one of the preceding claims arranged in cascade, wherein the voltage difference between the first generator voltage and the second generator voltage is continuously reduced in the cascade. Use of the device according to any of claims 1 to 12, which is used to automatically adjust the voltage of a reciprocating engine, in particular a diesel generator driven by a diesel engine, in particular a synchronous generator, according to the load current.