JP2005531272A - Voltage control device in generator by winding tapping and control relay means - Google Patents

Abstract

The voltage control device of the power source device ("generator") that is automatically and correlated to the load current can be connected to the generator clamp pair that receives the load current and taps the first generator voltage on the generator winding A first clamp pair for connecting to the generator clamp pair and a second clamp for tapping on the generator winding a second generator voltage that is smaller than the first generator voltage A control relay having a pair, a third clamp pair for supplying a control voltage to the control circuit, and a switch for switching the connection between the generator clamp pair and the first or second clamp pair (9), wherein the generator clamp pair connected to the first clamp pair via the switch when the control voltage is equal to or higher than the upper threshold voltage of the switch relay is the second clamp pair. And the generator clamp pair connected to the second clamp pair via the switch when the control voltage is less than or equal to the lower threshold voltage of the switch relay is connected to the first clamp pair and further by the switch Bypassing the connection between the formed generator clamp pair and the first clamp pair, the conduction voltage is greater than the difference between the first and second generator voltages and tapped on the first clamp pair A bridge element having a voltage correlation resistance ("varistor") that is less than the first generator voltage.

Description

Detailed Description of the Invention

  The present invention relates to automatic and load current compatible voltage control of a power source device (“generator”). In particular, the invention relates to the application of the device to the voltage control of a generator driven by a piston internal combustion engine.

  Devices for controlling the voltage of the generator are known. In a power source device having an electromagnet for exciting the induction winding, adapting the generator voltage to various load conditions is, for example, changing the control current of the electromagnet and the magnetic flux penetrating the induction winding following this. Implemented by change. This type of simple voltage control is not possible with a permanently excited generator. Therefore, technically cumbersome measures are required to control the voltage, which can be implemented, for example, in the form of a sliding contact along the main winding for controlling the number of active windings. The problem here is the high wear of the sliding contact, especially due to friction and sparks. This leads to winding shorts that cannot be avoided, resulting in a power loss that cannot be ignored. Furthermore, it is a problem that a short current interruption can always occur during the switching operation.

  German Patent Application Publication No. 2659600A1 automatically controls the load by controlling the generator output voltage by short-circuiting the partial winding at a certain phase by a triac connected to the winding tapping point and the control point. An apparatus for performing power source control is shown.

  US Patent Application Publication No. 2001 / 002802A1 describes a motor whose rotational speed / torque characteristics are changed by switching a supply voltage on a winding tapping point of a stator winding.

  German Patent Application No. 10047287A1 discloses an apparatus and a method for generating various output voltages by an AC generator that changes the connection configuration of stator windings by switching the configuration in order to generate various output voltages. Has been described.

  Accordingly, it is an object of the present invention to avoid complex control technology measures to adapt generator voltage to various load conditions. This prevents current interruption during switching operations.

  The object is solved according to the features of the independent claims by means of the proposal of the invention. The features of the dependent claims provide preferred additional configurations of the invention.

  According to the present invention, the voltage of the power source automatically and corresponding to the load current, which is provided with the first and second clamp pairs for tapping the first and second generator voltages on the generator winding. An apparatus for performing the control is proposed. Both the first and second clamp pairs can be connected to the generator pair, through which a load current is induced. There is always a larger number of windings between the first clamp pair than between the second clamp pair, so that the voltage tapped between the first clamp pair is always tapped between the second clamp pair. Will be greater than the applied voltage. As long as it is maintained that there is always a higher number of windings between the first clamp pair than between the second clamp pair, both the first and second clamp pairs are It can be sandwiched at an arbitrary position. The first generator voltage is preferably the generator main voltage, i.e. the voltage tapped from all the windings of the generator. The second generator voltage is always a tapping voltage smaller than the generator main voltage.

  Furthermore, the device according to the invention comprises a third clamp pair, which allows tapping the control voltage for the control circuit. The control voltage preferably corresponds to a voltage difference between the first generator voltage and the second generator voltage. It is preferable that the control circuit is configured such that current can only flow when a specific conduction voltage is exceeded. This can be achieved, for example, by a Zener diode whose breakthrough voltage corresponds to the conduction voltage of the control circuit.

  The control circuit includes a control relay having a switch for alternately connecting the generator clamp pair with the first or second clamp pair sandwiched between the generator windings. When the control voltage tapped on the third clamp pair becomes equal to or higher than the upper threshold voltage of the switch relay, it is connected to the first clamp pair via this switch by switching the switch of the control relay. A generator clamp pair is connected to the second clamp pair. When the control circuit is allowed to flow only after exceeding a certain conduction voltage, the upper threshold voltage is calculated from the sum of the conduction voltages of the control circuit, for example, the breakthrough voltage of the Zener diode provided therein and the pull-in of the switch relay. Derived from the voltage. Conversely, when the control voltage is lower than the lower threshold voltage of the switch relay, the generator clamp connected to the second clamp pair via the switch is connected to the first clamp pair by switching the switch. This lower threshold voltage is obtained from the sum of the conduction voltages of the control circuit, for example, from the breakthrough voltage of the Zener diode and the open voltage of the switch relay.

  The open voltage of the switch relay is always smaller than the pull-in voltage of the switch relay, where the hysteresis of the switch relay is important. This hysteresis is essential for stable switching of the switch relay, which results in an unstable switch state from the same upper and lower threshold voltage, ie from the same pull-in voltage and open-circuit voltage, and switches continuously. This is because there is a possibility.

  The spacing, or hysteresis width, between the upper and lower threshold voltages is generally correlated to the size of the switch relay. The relative position of the hysteresis can be changed depending on the size of the Zener diode provided in the circuit. When the breakthrough voltage of the Zener diode is low, the hysteresis moves to a smaller control voltage and vice versa. This Zener diode further provides a function of equalizing the hysteresis potential.

  If there are other elements in the control circuit, such as rectifier diodes that allow the DC control circuit to be used effectively, the breakthrough voltage of those elements is also necessary to switch the switch relay if necessary. Considered with respect to the magnitude of the control voltage.

  Furthermore, the device according to the invention comprises a bridge element for bypassing the connection between the first clamp pair and the generator clamp pair achieved by the switch. This bridging element comprises a voltage correlation resistor ("varistor"), here used as an exception, not as an overvoltage protection, which is greater than the difference between the first and second generator voltages. It has a breakthrough voltage that is less than the first generator voltage tapped on the pair. When the switch of the control relay connects the generator clamp pair with the first or second clamp pair, there is substantially no voltage drop along the connection between the first clamp pair and the generator clamp pair. The bridging element functions as a blocking element because of the absence of a potential difference and the resulting varistor current flow. However, when the switch of the control relay switches between the first and second clamp pairs, the potential of the first clamp pair is present on the varistor during the switching operation, and the bridge element is interrupted by opening the switch. Function as a current-carrying element suitable for bridging the connection between the generated first clamp pair and the generator clamp pair to induce a load current. When the second clamp pair is connected to the generator clamp pair by the switch, the varistor conduction voltage is selected to be greater than the difference between the first and second generator voltages to prevent a short circuit. There is a need to. Current interruption during the switching operation can be effectively prevented by the bridge element.

  In a preferred embodiment of the present invention, voltage control is performed with a tolerance of less than ± 5%. This means that the voltage is increased or decreased at the same time as the nominal voltage becomes 5% under or over. It is also suitable if voltage control is performed at an ohmic load in the vicinity of about 50% to 80% of the nominal load current. If the load is ohmic induction, the switching point will correspondingly move to a higher proportion of the nominal current. In particular, the device according to the invention complies with the G2 implementation class of the German Industrial Standard DIN 8528, which standardizes the voltage control accuracy of the current source device corresponding to the tolerance of the public power line network.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an exemplary circuit diagram of an apparatus according to the present invention for voltage control of one phase of a permanently excited synchronous generator. Only the generator winding 1 and the generator clamps N, L1 are shown from the generator. On the generator winding 1, the first clamp pair 1U1 and 1U2 and the second clamp pair 1U1 and “U” are tapping the first or second generator voltage. The first clamp pair 1U1, 1U2 sandwiches the total number of generator windings, while the second clamp pair 1U1, 2U2 sandwiches a smaller number of windings. Since the induced voltage is proportional to the number of windings, the second generator voltage is always smaller than the first generator voltage. Both the first and second clamp pairs can be coupled to the generators L1, N.

  In order to connect the generator clamps L1, N with the first or second clamp pair, a switch relay 8 having a switch 9 acts. The switch relay 8 is provided in the control circuit 2 connected to the clamps 2U2 and 1U2 of the first and second clamp pairs and thus taps the differential voltage between the first and second generator voltages. In the control circuit 1, a Zener diode 6 and a rectifier diode 7 are further provided. The zener diode 6 provides a blocking action that allows the zener diode 6 to flow only after exceeding the zener breakthrough voltage. The rectifier diode 7 acts to rectify the AC voltage, which makes it possible to use the DC switch relay 8 effectively.

  At the same time the voltage induced between the clamps 1U1 and 2U2 exceeds the upper threshold given by the breakthrough voltage of the Zener diode 6, the conduction voltage of the rectifier diode 7 and the pull-in voltage of the control relay 8, the switch 9 is turned on. Thus, a current for energizing the switch relay 8 flows in the control circuit 2. As a result, the voltage generated on the generator clamp pair N, L1 is switched from the high voltage value 1U2 to the low voltage value 2U2. The load current that activates this switching operation is induced through the circuit 4 of the second clamp pair. A decrease in the load current between the clamps 1U2, 2U2 of the control circuit further increases the control voltage tapped there, which assists the switching operation. Therefore, the effect of the load current on the voltage in this tributary is maintained.

  When the load current rises again, the tapped control voltage drops, and a new switching of the switch relay 8 is achieved at the same time that the control voltage reaches the lower threshold voltage. The lower threshold voltage is given by the breakthrough voltage of the Zener diode 6, the conduction voltage of the rectifier diode 7, and the open voltage of the switch relay 8. The lower threshold is always lower than the upper threshold voltage according to the hysteresis of the switch relay. When the control voltage drops below the breakthrough voltage of the Zener diode 6, no current flows through the control circuit 2. The increased internal resistance between the clamps 1U2, 2U2 of the control circuit caused by switching from the second clamp pair to the first clamp pair by the load current results in a further reduction of the control voltage, which assists the switching operation. To do.

  Current interruption during switching is prevented by a varistor 10 provided in the bridge element 5. This varistor has a high ohm value in the no-voltage state and therefore does not conduct any current. In contrast, when the voltage on that terminal rises, it switches to a low ohm value state at a particular conduction voltage and conducts current through circuit 3. When the switch 9 connects the first clamp pair to the generator clamp pair, no potential drop occurs on the terminal of the bridge element, and the varistor has a high ohm value and functions as a blocking element. During the switching of the switch 9 from the first clamp pair to the second clamp pair, the potential of the clamp 1U2 is applied to the varistor, thereby changing to a low ohm value state and inducing a control current. When the switch 9 forms the generator clamp pair connection to the second clamp pair, current induction through the circuit 4 is carried out, whereby the varistor again becomes a high ohm value and current flow through the bridge element. Shut off. The same applies to the switching of the switch 9 from the clamp 2U2 to the clamp 1U2. When the switch 9 connects the generator clamp pair N, L1 to the second clamp pair 1U1, 2U2 because the conduction voltage of the varistor is higher than the difference in voltage tapped between the clamps 2U2 and 1U2. Is prevented from being short-circuited through the circuit 3. In order to reduce the internal loss of the varistor as much as possible, the switch 9 needs to switch as fast as possible.

FIG. 2 shows a pure ohmic load (dotted line) where the current and voltage are in phase, ie cos φ = 1 (where φ corresponds to the angle between the current and voltage) and cos φ = 0.8. in the case of inductive loads, shows a load current _{I L} that shown generator clamp L1, the voltage across the tapped line by N _{U Str} (the phase voltage) as a percentage of the nominal voltage _{U StrN} a percentage of the nominal load current _{I LN} Correlation is shown.

  The voltage curve 2 corresponds to the first generator voltage tapped by the first clamp pair 1U1, 1U2, while the voltage curve 1 is the second smaller generator tapped by the second clamp pair 1U1, 2U2. Corresponds to voltage.

The switching operation is based on a tolerance range of ± 7%. In the unloaded condition (ie, I _L = 0), the generator clamp voltage is about 107% of the nominal voltage, corresponding to the voltage tapped between 1U1 and 2U2.

First, pay attention to the ohmic load (dotted line). Initially the generator is electrically loaded with zero load (dotted curve 1; I _L = 0), the load current increases continuously and reaches about 77% of the nominal load current when the control relay switching threshold (upper threshold) is reached. Voltage) and the generator clamp L1 is connected to the clamp 1U2 of the first clamp pair. This results in a voltage change from about 94% to about 101% of the line voltage. As indicated by the dotted line 2, the line voltage decreases when the load current is further increased.

Thereafter, when the generator load is released, i.e., when the load current continuously decreases, the voltage tapped between the generator clamps is approximately 55% of the nominal load current according to dotted line 2 and the switching threshold (lower threshold) Until the voltage reaches the voltage), the generator clamp L1 is connected to the clamp 2U2 of the second clamp pair. This results in a voltage change from about 105% to about 98% of the line voltage. When the load current is further reduced, the line voltage increases as indicated by the dotted line 1. Finally, 107% of the nominal line voltage is reached in the no-load condition (I _L = 0).

  The hysteresis of the control relay can be seen between both switching thresholds. The extreme value of hysteresis exists between about 77% and about 55% of the nominal load current. The area surrounded by hysteresis depends on the relative distance between the thresholds and the slope of the line voltage.

  The device according to the present invention is provided for controlling the phase voltage of each eddy current phase, so that there are a total of three in the case of three-phase current. This works particularly well for unbalanced loads, because the voltage drops in the heavy load phase and the voltage rises in the light load phase.

  In particular, the device according to the present invention can be interconnected in a cascade manner, the distance between the first and second generator voltages in the cascade is gradually narrowed, so that the voltage control is more sensitive. Become.

  A preferred mode of application of the device according to the present invention is for voltage control automatically and corresponding to a load current of a power supply device driven by a piston internal combustion engine. This applies in particular to synchronous generators driven by diesel engines. The present invention is also suitably applied to a permanently excited generator.

It is a circuit diagram which shows the voltage control apparatus of the synchronous generator by which permanent excitation was carried out. It is explanatory drawing which shows the change of the line voltage of the eddy current with respect to the load current in the switching operation open | released by the apparatus which concerns on ohmic load (dotted line) and ohmic induction load (solid line), and the apparatus which concerns on this invention.

Claims (13)

A first clamp pair (1U1, 1U2) that is connectable to a generator clamp pair (N, L1) to which a load current is applied and for tapping the first generator voltage on the generator winding;
A second clamp pair (1U1, 2U2) that can be connected to the generator clamp pair (N, L1) and taps a second generator voltage that is smaller than the first generator voltage on the generator winding. )When,
A third clamp pair (1U2, 2U2) for supplying a control voltage to the control circuit (2);
The control circuit (2) comprises a control relay (8) having a switch (9) for switching the connection between the generator clamp pair (N, L1) and the first or second clamp pair, where control is provided. When the voltage is equal to or higher than the upper threshold voltage of the switch relay, the generator clamp pair (N, L1) connected to the first clamp pair (1U1, 1U2) via the switch (9) is the second clamp pair. Generator clamp pair connected to the second clamp pair (1U1, 2U2) via the switch (9) when the other control voltage is below the lower threshold voltage of the switch relay. (N, L1) is connected to the first clamp pair (1U1, 1U2),
Bypass the connection between the generator clamp pair (N, L1) and the first clamp pair (1U1, 1U2) formed by the switch (9), the conduction voltage of which is the first and second generator voltages A bridge element (5) having a voltage correlation resistance ("varistor") (10) that is greater than the difference between and less than the first generator voltage tapped on the first clamp pair.
Voltage control device for power source device ("generator") automatically and correlated with load current.   The apparatus of claim 1, wherein the control voltage of the control circuit corresponds to a voltage difference between the first generator voltage and the second generator voltage.   2. Device according to claim 1, characterized in that the control circuit (2) reaches a conduction voltage and is capable of conducting current.   4. Device according to claim 3, characterized in that the control circuit (2) comprises a Zener diode (6) whose breakthrough voltage corresponds to the conduction voltage of the control circuit (2).   2. Device according to claim 1, characterized in that the control circuit (2) comprises a rectifying element, in particular a rectifying diode (7).   The device according to claim 1, characterized in that the first generator voltage tapped by the first clamp pair (1U1, 1U2) corresponds to the generator main voltage.   2. The device according to claim 1, wherein the voltage control is performed within a tolerance of ± 5%.   The apparatus of claim 1, wherein the voltage control at the ohmic load is performed at about 50-80% of the nominal load current.   2. The device according to claim 1, wherein the device complies with the implementation class G2 of the standard DIN8528.   The apparatus of claim 1, wherein the power source apparatus is permanently energized.   A configuration in which the apparatus according to any one of claims 1 to 10 is arranged for each of the three phases.   12. The apparatus according to claim 1, wherein the devices according to claim 1 are arranged in cascade, and a voltage difference between the first generator voltage and the second generator voltage is gradually reduced in the cascade. .   13. A method of applying the apparatus according to any one of claims 1 to 12 to voltage control in accordance with automatic and load current of a power source such as a synchronous generator driven by a piston internal combustion engine such as a diesel engine.

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