Zero-current pulse with constant current gradient for interrupting a direct current

Abstract

A configuration for generating a zero current pulse for generating a zero current crossing in an electrical component through which a direct current flows, in particular a vacuum interrupter, includes a switch and an electrical energy storage device or store having two poles through which the electrical energy storage device can be charged by a voltage source. A loop can be formed by the energy storage device, the electrical component through which the direct current flows and the switch, so that the energy storage device can be discharged by closing the switch while generating a zero current pulse counter to the direct current across the electrical component. The energy storage device has a plurality of energy storage elements for mutual generation of a zero current pulse.

Claims

1. A configuration for generating a zero-current pulse for generating a zero-current crossing in an electrical component or a vacuum interrupter through which a direct current flows, the configuration comprising: an electrical energy storage device having two poles, through which said electrical energy storage device can be charged by a voltage source, said electrical energy storage device including a plurality of energy storage elements for mutual generation of a zero-current pulse; said plurality of energy storage elements forming a chain conductor for the mutual generation of the zero-current pulse; said plurality of energy storage elements being chain links each being formed as a respective series circuit of an inductor, a resistor and a capacitor; said chain links including at least a first chain link and a second chain link, following said first chain link; said series circuit of said first chain link being formed between said poles of said electrical energy storage device and said series circuit of said second chain link, is connected in parallel with said capacitor of said first chain link; and a switch; said electrical energy storage device, the electrical component and said switch forming a loop for discharging said electrical energy storage device by closing said switch while generating the zero-current pulse flowing counter to the direct current across the electrical component.

2. The configuration according to claim 1, wherein said electrical energy storage device is configured to cause said loop to form a resonant circuit when said switch is closed causing the zero-current pulse to have alternating directions.

3. The configuration according to claim 1, wherein said energy storage elements are dimensioned to provide the zero-current pulse arising as a result of the mutual discharging of said energy storage elements with a current gradient which, in sections, is as a whole nearly constant.

4. The configuration according to claim 1, which further comprises a charging resistor connected between the voltage source and said poles, of said electrical energy storage device.

5. The configuration according to claim 1, which further comprises an energy absorber connected in parallel with the electrical component.

6. The configuration according to claim 5, wherein said energy absorber is a metal oxide arrester.

7. A method for generating a zero-current pulse in an electrical component through which a direct current flows, the method comprising the following steps: providing a vacuum interrupter as the electrical component through which a direct current flows; providing an electrical energy storage device having two poles, through which the electrical energy storage device can be charged by a voltage source, the electrical energy storage device including a plurality of energy storage elements for mutual generation of a zero-current pulse; forming a chain conductor with the plurality of energy storage elements for the mutual generation of the zero-current pulse; providing the plurality of energy storage elements as chain links each being formed as a respective series circuit of an inductor, a resistor and a capacitor, the chain links including at least a first chain link and a second chain link, following the first chain link; forming the series circuit of the first chain link between the poles of the electrical energy storage device and connecting the series circuit of the second chain link in parallel with the capacitor of the first chain link; providing a switch; forming a loop including the electrical energy storage device, the vacuum interrupter and the switch; and discharging the electrical energy storage device by closing the switch while generating the zero-current pulse flowing counter to the direct current across the vacuum interrupter.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention is explained in more detail below with reference to the attached drawings in terms of preferred exemplary embodiments.

(2) Here

(3) FIG. 1 shows an exemplary embodiment of the invention with a chain conductor of three chain links;

(4) FIG. 2 shows an exemplary embodiment of a use of the invention for the construction of a direct current switch.

DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a preferred exemplary embodiment of the invention. In FIG. 1 an arrangement for generating a zero-current pulse 1 for generating of a zero-current crossing in an electrical component 3 through which a direct current 2 flows can be seen, wherein the electrical component 3 is implemented as a vacuum interrupter.

(6) The arrangement comprises an electrical energy store 4 with two poles 12, 13, which can be charged from a voltage source 10 illustrated in FIG. 2. The arrangement further, through the energy store 4, the electrical component 3 through which direct current flows, and a switch 5, comprises a loop, so that the energy store 4 can be discharged by closing the switch 5 while generating a zero-current pulse 1 through which the direct current 2 flowing through the electrical component 3 is at first reinforced.

(7) The energy store 4 here comprises a plurality of energy storage elements in the form of chain links 6, 6 and 6 of a chain conductor for the mutual generation of a zero-current pulse 1. The chain links 6, 6, 6 of the chain conductor comprise inductors 7, 7, 7, resistors 8, 8, 8 and capacitors 9, 9, 9. Each chain link 6, 6, 6 is here formed of a series circuit of an inductor 7, 7, 7, a resistor 8, 8, 8 and a capacitor 9, 9, 9. A series circuit of a first chain link 6 is formed between the poles 12, 13 of the energy store 4. The series circuit of a following chain link 6, 6 is connected in parallel with the capacitor 9, 9 of the respectively previous chain link 6, 6.

(8) With a design of this sort, a resonant circuit is formed by the chain conductor whose oscillationswhen the electrical component 3 is in a conducting stateis initiated by closing the switch 5.

(9) When the switch 5 is closed, the capacitors 9, 9, 9 are discharged, forming a positive half wave of a zero-current pulse 1. The positive half wave of the zero-current pulse 1 exhibits the same direction as the direct current 2, so that the two currents are initially added in the electrical component 3.

(10) After discharging the capacitors 9, 9, 9, the inductors 7, 7, 7 maintain the zero-current pulse 1, until a reversal of the polarity of the voltage U in the capacitors 9, 9, 9 occurs. As the voltage continues to develop, the amplitude of the zero-current pulse 1 falls down to its zero crossing.

(11) As a result of the reversal of the polarity of the voltage U in the capacitors 9, 9, 9, the positive half wave of the zero-current pulse 1 is followed by a negative half wave. This negative half wave of the zero-current pulse 1 acts in the opposite direction to the direct current 2, so that, with appropriate dimensioning, the direct current 2 can be compensated by the negative half wave of the zero-current pulse 1, and a zero-current crossing can be achieved for the sum of the two currents in the electrical component 3.

(12) The inductors 7, 7, 7, resistors 8, 8, 8 and capacitors 9, 9, 9 of the chain links 6, 6, 6 are dimensioned such that the zero-current pulse 1 exhibits a current gradient which, in sections, is on the whole approximately constant.

(13) FIG. 2 shows an exemplary embodiment of a use of the invention for the construction of a direct current switch 17. The embodiment of the energy store 4, and its interaction with the electrical component 3 and with the switch 5 are identical to the exemplary embodiment in FIG. 1. In addition to the arrangement described in FIG. 1, it can be seen in FIG. 2 that the energy store 4 shown in FIG. 1, here represented by the chain conductor with the inductors 7, 7, 7, the resistors 8, 8, 8 and the capacitors 9, 9, 9, is connected to the voltage source 10 through a charging resistor 11.

(14) The electrical energy for the direct current 2 that is to be compensated is, furthermore, supplied from the same voltage source 10. The charging resistor 11 is here arranged such that it forms a second loop with the voltage source 10, the electrical component 3 and the switch 5, and is thus not contained in the previously mentioned loop of the switch 5, the electrical component 3 and the energy store 4, nor is it arranged in the current path of the direct current 2 that is to be compensated. A further, third loop, consisting of the voltage source 10, the energy store 4 and the charging resistor 11 allows the capacitors 9, 9, 9 to be charged up to the voltage U.sub.DC of the voltage source 10 as long as the switch 5 is open.

(15) If the switch 5 is closed, the capacitors 9, 9, 9 of the energy store 4 discharge through the electrical component 3 and the switch 5 in the form of the zero-current pulse 1. The electrical component 3, implemented in the form of a vacuum interrupter, is coupled with the switch 5, and is opened as the switch 5 is closed, so that when the zero-current crossing caused by the negative half wave of the zero-current pulse 1 is reached, the direct current 2 can be switched off.

(16) A switched load with an inductive component 15 and an ohmic component 16 is connected through the direct current switch 17 to the voltage source 10 with the voltage U.sub.DC, by which the direct current 2 is determined. It can also be seen in FIG. 2 that the arrangement comprises an energy absorber 14 that is arranged in parallel with the electrical component 3.

(17) When the direct current 2 is interrupted by the electrical component 3, an excess voltage resulting from the inductive component 15 of the switched load arises across the electrical component 3, and can be absorbed by the energy absorber 14 which is implemented as a metal oxide arrester.

REFERENCE SIGNS

(18) 1 Zero-current pulse 2 Direct current 3 Electrical component 4 Energy store 5 Switch 6 Chain link 7 Inductor 8 Resistor 9 Capacitor 10 Voltage source 11 Charging resistor 12 Pole of the energy store 13 Pole of the energy store 14 Energy absorber 15 Switched load, inductive component 16 Switched load, ohmic component 17 Direct current switch