Current-limiting circuit and method for operating the circuit
View Patent ↗A current-limiting circuit for limiting switch-on currents or transients includes a switch, a diode, an inductance, an input with a first connection and second connection, and an output with a first connection and second connection. The second connection of the input is connected via the switch to the junction of an inductance and the anode of a diode and via the inductance to the second connection of the output. The cathode of the diode is connected to the first connection of the input and to the first connection of the output. The switch is preferably an electronic switch controlled to provide clocked current limitation.
1. A current-limiting circuit, comprising:
a first switch,
a diode,
an inductance,
an input having a first input connection and second input connection, and
an output having a first output connection and second output connection,
the second input connection being connected through the first switch to the inductance and to the anode of the diode and through the inductance to the second output connection,
the cathode of the diode being connected to the first input connection and to the first output connection of the output,
wherein the inductance is a component of a high frequency filter,
wherein the current-limiting circuit is operatively disposed between two capacitors of the high frequency filter,
wherein a first connection of a first capacitor of said two capacitors is connected to the cathode of the diode and is further connected to a second capacitor of said two capacitors via a shared connection node, and a second connection of the first capacitor is connected to the first switch, and
wherein a first connection of the second capacitor is connected to the cathode of the diode and is further connected to the first connection of the first capacitor via the shared connection node, and a second connection of the second capacitor is connected to the inductance.
2. The current-limiting circuit of claim 1 further comprising a second switch,
wherein the cathode of the diode is connected through the second switch to the first input connection of the input, and
wherein the first connection of the first capacitor is connected through the second switch to the cathode of the diode and is further connected to the second capacitor.
3. The current-limiting circuit of claim 1 , wherein the first and second input connections of the input are connected, respectively, to the first and second connections of the first capacitor and then for connection to a rectifier circuit.
4. The current-limiting circuit of claim 1 , wherein the switch comprises at least one electronic switch.
5. The current-limiting circuit of claim 4 , wherein the electronic switch is selected from the group comprising a transistor, a MOSFET, a thyristor, and an IGBT.
6. The current-limiting circuit of claim 1 , wherein a resistor is connected between the first switch and a junction of the anode of the diode and a first end of the inductance.
7. The current-limiting circuit of claim 1 , wherein the first and second input connections of the input are for connection to a preceding rectifier circuit.
8. The current-limiting circuit of claim 1 , wherein an electrolytic capacitor is connected across the first and the second output connections of the output.
9. The current-limiting circuit of claim 8 , wherein the first switch is connected so as to cause the electrolytic capacitor to be charged in a clocked fashion, at a clock speed that serves to limit current flow through the circuit.
10. The current-limiting circuit of claim 1 , wherein the current-limiting circuit is configured for connection to a power factor correction circuit across the first and the second output connections of the output.
11. The current-limiting circuit of claim 1 , wherein the output is configured for connection to a power supply.
12. The current-limiting circuit of claim 11 , wherein the power supply is a switched mode power supply.
13. The current-limiting circuit of claim 1 , wherein the first switch is operatively connected for clocked current limitation.
14. A current-limiting circuit, comprising:
a first switch,
a diode,
a first inductance,
an input having a first input connection and second input connection, and
an output having a first output connection and second output connection,
the second input connection being connected to the first inductance and to the anode of the diode and through the first inductance to the second output connection,
the cathode of the diode being connected to the first input connection through the first switch and to the first output connection of the output,
wherein the first inductance is a component of a high frequency filter,
wherein the current-limiting circuit is operatively disposed between two capacitors of the high frequency filter,
wherein a first connection of a first capacitor of said two capacitors is connected through the first switch to the cathode of the diode and is further connected to a second capacitor of said two capacitors via a shared connection node, and a second connection of the first capacitor is connected to the first inductance, and
wherein a first connection of the second capacitor is connected to the cathode of the diode and is further connected through the first switch to the first connection of the first capacitor via the shared connection node, and a second connection of the second capacitor is connected to the first inductance.
15. The current-limiting circuit of claim 14 further comprising a second inductance,
wherein the second inductance is a component of the high frequency filter,
wherein the cathode of the diode is connected through the second inductance to the first output connection of the output,
wherein the first connection of the first capacitor is connected through the second inductance to the second capacitor, and
wherein the first connection of the second capacitor is connected through the second inductance to the cathode of the diode.
16. The current-limiting circuit of claim 15 , wherein the first inductance and second inductance comprise, respectively, a first set of windings and a second set of windings, the first set of windings and the second set of windings both sharing a single core.
17. The current-limiting circuit of claim 16 , wherein the first and second input connections of the input are connected, respectively, to the first and second connections of the first capacitor and then for connection to a rectifier circuit.
18. The current-limiting circuit of claim 15 further comprising a second switch,
wherein the second input connection is connected through the second switch to the first inductance and to the anode of the diode, and
wherein the second connection of the first capacitor is connected through the second switch to the first inductance.
19. The current-limiting circuit of claim 18 , wherein the first inductance and second inductance comprise, respectively, a first set of windings and a second set of windings, the first set of windings and the second set of windings both sharing a single core.
20. The current-limiting circuit of claim 19 , wherein the first and second input connections of the input are connected, respectively, to the first and second connections of the first capacitor and then for connection to a rectifier circuit.
21. A current-limiting circuit, comprising:
a first switch,
a diode,
a first inductance,
an input having a first input connection and second input connection, and
an output having a first output connection and second output connection,
the first input connection being connected to the first inductance and to the cathode of the diode and through the first inductance to the first output connection,
the anode of the diode being connected to the second input connection through the first switch and to the second output connection of the output,
wherein the first inductance is a component of a high frequency filter,
wherein the current-limiting circuit is operatively disposed between two capacitors of the high frequency filter,
wherein a first connection of a first capacitor of said two capacitors is connected to the first inductance, and a second connection of the first capacitor is connected through the first switch to the anode of the diode and is further connected to a second capacitor of said two capacitors via a shared connection node, and
wherein a first connection of the second capacitor is connected to the first inductance, and a second connection of the second capacitor is connected to the anode of the diode and is further connected through the first switch to the second connection of the first capacitor via the shared connection node.
22. The current-limiting circuit of claim 21 further comprising a second inductance,
wherein the second inductance is a component of the high frequency filter,
wherein the anode of the diode is connected through the second inductance to the second output connection of the output,
wherein the second connection of the first capacitor is connected through the second inductance to the second connection of the second capacitor, and
wherein the second connection of the second capacitor is connected through the second inductance to the anode of the diode.
23. The current-limiting circuit of claim 22 , wherein the first inductance and second inductance comprise, respectively, a first set of windings and a second set of windings, the first set of windings and the second set of windings both sharing a single core.
24. The current-limiting circuit of claim 23 , wherein the first and second input connections of the input are connected, respectively, to the first and second connections of the first capacitor and then for connection to a rectifier circuit.
25. The current-limiting circuit of claim 21 further comprising a second switch,
wherein the cathode of the diode is connected through the second switch to the first input connection of the input, and
wherein the first connection of the first capacitor is connected through the second switch to the cathode of the diode and is further connected to the first inductance.
26. A method for triggering a current-limiting circuit including a first switch, a diode, a first inductance, an input having a first input connection and second input connection, and an output having a first output connection and second output connection; the second input connection being connected to the first inductance and to the anode of the diode and through the first inductance to the second output connection, the cathode of the diode being connected to the first input connection through the first switch and to the first output connection of the output, the first inductance being a component of a high frequency filter, and the current-limiting circuit being operatively disposed between two capacitors of the high frequency filter;
the method comprising connecting the output to a power supply, and opening the first switch when a predetermined voltage threshold at the current-limiting circuit input is exceeded,
wherein a first connection of a first capacitor of said two capacitors is connected through the first switch to the cathode of the diode and is further connected to a second capacitor via a shared connection node, and a second connection of the first capacitor is connected to the first inductance, and
wherein a first connection of the second capacitor is connected to the cathode of the diode and is further connected through the first switch to the first connection of the first capacitor via the shared connection node, and a second connection of the second capacitor is connected to the first inductance.
27. The method of claim 26 , further comprising measuring an instantaneous current through a resistor connected in series with the first switch and controlling the first switch in response to the measured current.
28. The method of claim 26 , wherein the first switch is closed and reopened at a predetermined clock speed.
29. The method of claim 28 , wherein the predetermined clock speed is a frequency in a range from 1 KHz to 1 MHz.
30. The method of claim 26 , further comprising deriving a pulse from the group comprising the first switch, at least one pulse generator, at least one Schmitt trigger, and at least one comparator, and triggering the first switch using the derived pulse.
31. A current-limiting circuit, comprising:
a first switch,
a diode,
an inductance,
an input having a first input connection and second input connection, and
an output having a first output connection and second output connection,
the first input connection being connected through the first switch to the inductance and to the cathode of the diode and through the inductance to the first output connection,
the anode of the diode being connected to the second input connection and to the second output connection of the output,
wherein the inductance is a component of a high frequency filter,
wherein the current-limiting circuit is operatively disposed between two capacitors of a high frequency filter,
wherein a first connection of a first capacitor is connected to the first switch, and a second connection of the first capacitor is connected to the anode of the diode and is further connected to a second capacitor via a shared connection node, and
wherein a first connection of the second capacitor is connected to the inductance, and a second connection of the second capacitor is connected to the anode of the diode and is further connected to the second connection of the first capacitor via a shared connection node.
32. The current-limiting circuit of claim 31 , wherein the first and second input connections of the input are connected, respectively, to the first and second connections of the first capacitor and then for connection to a rectifier circuit.
33. The current-limiting circuit of claim 31 , wherein the switch comprises at least one electronic switch.
34. The current-limiting circuit of claim 31 , wherein a resistor is connected between the first switch and a junction of the cathode of the diode and a first end of the inductance.
35. The current-limiting circuit of claim 31 , wherein the first and second input connections of the input are connected to a preceding rectifier circuit.
36. The current-limiting circuit of claim 31 , wherein an electrolytic capacitor is connected across the first and the second output connections of the output.
37. The current-limiting circuit of claim 31 , wherein a power factor correction circuit is connected across the first and the second output connections of the output.
38. The current-limiting circuit of claim 31 , wherein the output is connected to a power supply.
39. The current-limiting circuit of claim 31 , wherein the switch is operatively connected for clocked current limitation.