AU641491B2 - Current limiter circuit - Google Patents
Current limiter circuit Download PDFInfo
- Publication number
- AU641491B2 AU641491B2 AU75035/91A AU7503591A AU641491B2 AU 641491 B2 AU641491 B2 AU 641491B2 AU 75035/91 A AU75035/91 A AU 75035/91A AU 7503591 A AU7503591 A AU 7503591A AU 641491 B2 AU641491 B2 AU 641491B2
- Authority
- AU
- Australia
- Prior art keywords
- mosfet
- resistor
- source
- current limiting
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/001—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection limiting speed of change of electric quantities, e.g. soft switching on or off
Landscapes
- Electronic Switches (AREA)
- Emergency Protection Circuit Devices (AREA)
Description
Aft 'Y 49 1
ORIGINAL
COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-1969 COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED -a "CURRENT LIMITER CIRCUIT" The following statement is a full description of this invention, including the best method of performing it known to us:- This invention relates to a circuit arrangement for limiting a current surge caused by connecting a capacitive load to a power source, by means of a current limiting resistor in series with the load, and a control circuit which cancels the effect of the current limiting resistor depending on the state of charge of the capacitive load.
For limiting switch-on surge currents, a known technique is to insert a current limiting resistor into the supply voltage conductor, and to shunt this with a circuit element controlled by a control circuit as soon as the voltage drop across the resistor falls below a predetermined threshold value.
In one known circuit arrangement, a thyristor is used for the shunt component.
In another known circuit arrangement a MOS field-effect transistor (MOSFET) is used for the shunt component.
Although the current limiting resistor used in these known circuits normally is only me" loaded for a short time, it must be designed for large dissipation since situations can a arise in which the threshold initiating the shunting action may not be achieved eg.
mace a -Nia because of excessive current being drawn by the load. Thus the current limiting resistor requires considerable space, because of its size and expected dissipation which precludes °.the mounting of other components in its immediate vicinity.
An object of the present invention is to provide a circuit arrangement for current limiting, of the kind already mentioned, which no longer requires a special current lim- 20. iting resistor and can therefore be assembled in a smaller space.
0°O 00 According to the present invention there is provided a circuit arrangement of the S aforementioned type, wherein the source-drain path of a MOS field-effect transistor (MOSFET) is used as the current limiting resistor, that the control circuit adjusts the o.
gate-source voltage of the MOSFET so that the source-drain path of the MOSFET assumes a predetermined resistance suitable for current limiting, as long as the load me. capacitance has not yet reached a predetermined charge state, but changes to a lowg: resistance path when the predetermined charge state is reached or exceeded.
0 0 Instead of using separate components for providing current limiting and for removing it, here only one component is used which, depending on the state of charge of the load capacitance, is used both as the current limiting resistor and as a switch to cancel its effect. By using a power MOSFET both as the current limiting resistor and as a component to replace the shunting switch, the space that would have been taken up by the current limiting resistor is saved.
Preferably, the control circuit contains a circuit arrangement wherein the control circuit includes a voltage divider in which one resistor is connected to a positive potential which is stabilised with respect to the source potential of the MOSFET, the other resistor is connected to the source potential of the MOSFET via the collector emitter path of a transistor and the junction of the resistors is connected to the gate terminal of the MOSFET, and that the base of the transistor is connected to the load output terminal of the MOSFET via a resistor.
Preferably, means is provided for compensating the gate-drain capacitance of the MOSFET, which delays the switching action.
In order that the invention may be readily understood, an embodiment thereof will now be described in relation to the figure of the drawing.
The drawing shows a load consisting of a resistive portion RL and a capacitive portion CL which is to be supplied with current from a power source with an output voltage U In series with the load there is the source-drain path of a MOSFET V whose gate terminal is connected to the junction of the resistors R, and R, forming a SO voltage divider. One side of the voltage divider is connected to the stabilised positive voltage produced by the Zener diode V1 which is in series with the resistor R; the other side is connected via a transistor V to the negative terminal of the power sdurce and the 3 source terminal of the MOSFET V 2 The two resistors of the voltage divider are given such values that, with transistor V 3 switched on, the voltage at the mid point of the voltage divider has a value (relative to the source-potential of the MOSFET) such that the source-drain resistance is adjusted according to the MOSFET characteristic to produce the desired current limiting.
If the load is now connected to the power source via the circuit arrangement shown, the load capacitance is at first uncharged. Via the load, a positive voltage is applied to the gate terminal of the MOSFET, relative to the source terminal of the MOSFET which is connected to the negative terminal of the power supply. The voltage present across the source-drain path of the MOSFET then drives current via the resistor
R
4 into the base-emitter path of transistor V 3 switching it on. This results in the voltage required at the mid point of the voltage divider for current limiting operation of the MOSFET. The source-drain path of the MOSFET conducts and permits charging of the capacitive load portion with a limited current.
As the charge on the load capacitance increases, the voltage drop across the source-drain path is reduced and finally becomes so small that it no longer, suffices to keep transistor V 3 switched on. Then the transistor V 3 stops conducting, and the MOSFET gate-source voltage at the mid point of the voltage divider rises to the voltage across the Zener diode V 1 This then causes full conduction of the MOSFET. The latter then represents only a very low resistance which causes no significant losses.
The MOSFET displays bistable behaviour in the circuit arrangement shown, since a reduction of its source-drain resistance accelerates the switching off of transistor V 3 Here a return to current limiting operation is not possible without briefly switching off the power source. This can nevertheless be achieved, for example, by a switch momentarily shunting the gate-source path of the MOSFET.
A capacitor C i is connected in parallel with the voltage divider resistor R It compensates for the gate-drain capacitance of the MOSFET and prevents a momentary switch-on of the MOSFET when the load is connected.
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Claims (3)
1. A circuit arrangement for limiting a current surge caused by connecting a capacitive load to a power source, by means of a current limiting resistor in series with the load, and a control circuit which cancels the effect of the current limiting resistor depending on the state of charge of the capacitive load, wherein the source-drain path of a MOS field-effect transistor (MOSFET) is used as the current limiting resistor, the cont ol circuit adjusting the gate-source voltage of the MOSFET so that the source-drain path of the MOSFET assumes a predetermined resistance suitable for current limiting, provided the load capacitance has not yet reached a predetermined charge state, but changes to a low-resistance path when the predetermined charge state is reached or exceeded, wherein the control circuit includes a voltage divider in which one resistor is connected to a positive potential which is stabilised with respect to the source potential of the MOSFET, the other resistor is connected to the source potential of the MOSFET via the collector emitter path of a transistor and the junction of the resistors is connected to the gate terminal of the MOSFET, and whe ,n the base of the transistor is connected to the load output terminal of the MOSFET via a resistor.
2. A circuit arrangement as claimed in claim 1, wherein a capacitor is connected in parallel with the resistor which is connected to the source potential of the MOSFET via the collector emitter path of transistor. C C e
3. A circuit arrangement substantially as herein described with reference to the figure of the accnmpanying drawing. CC' DATED THIS TWENTY-THIRD DAY OF JULY 1993 ALCATEL N.V. ii
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4013731 | 1990-04-28 | ||
| DE19904013731 DE4013731C2 (en) | 1990-04-28 | 1990-04-28 | Circuit arrangement for limiting the inrush current |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU7503591A AU7503591A (en) | 1991-11-07 |
| AU641491B2 true AU641491B2 (en) | 1993-09-23 |
Family
ID=6405361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU75035/91A Ceased AU641491B2 (en) | 1990-04-28 | 1991-04-16 | Current limiter circuit |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU641491B2 (en) |
| DE (1) | DE4013731C2 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0541876A1 (en) * | 1991-11-15 | 1993-05-19 | International Business Machines Corporation | Overload protection circuit capable of sustaining high inrush current in the load circuit |
| FR2693851B1 (en) * | 1991-12-31 | 1994-08-19 | Saed | Method for protecting against overcurrents of a mains power transformer and device for implementing said method. |
| DE4215676A1 (en) * | 1992-05-13 | 1993-11-18 | Siemens Ag | Circuit arrangement for limiting the inrush current in an electronic assembly |
| US5742463A (en) * | 1993-07-01 | 1998-04-21 | The University Of Queensland | Protection device using field effect transistors |
| DE4494617T1 (en) * | 1993-07-01 | 1996-11-21 | Univ Queensland | Protection device using field effect transistors |
| DE4412640A1 (en) * | 1994-04-13 | 1995-10-19 | Abb Patent Gmbh | Limiter for inrush current to capacitive load |
| DE19546132C2 (en) * | 1995-12-11 | 2000-10-12 | Berthold Fuld | Circuit arrangement for protection against overcurrent on the input side for voltage intermediate circuit converters |
| DE19602121C1 (en) * | 1996-01-22 | 1997-06-05 | Siemens Ag | Current limiting circuit, e.g. for power supply or DC-DC converter |
| DE29602914U1 (en) * | 1996-02-19 | 1997-06-19 | Tridonic Bauelemente Ges.M.B.H., Dornbirn | Circuit arrangement for inrush current limitation and overvoltage protection for an active harmonic filter of an electronic ballast |
| SE9702335D0 (en) * | 1997-06-18 | 1997-06-18 | Asea Brown Boveri | Current limiting device and protection against faults in a current |
| DE10253980B4 (en) * | 2002-11-20 | 2005-06-23 | Daimlerchrysler Ag | Device for limiting the inrush current |
| US7646576B2 (en) | 2004-11-09 | 2010-01-12 | Bourns, Inc. | Apparatus and method for high-voltage transient blocking using low voltage elements |
| US7369387B2 (en) | 2004-11-09 | 2008-05-06 | Fultec Semiconductor, Inc. | Apparatus and method for temperature-dependent transient blocking |
| US7342433B2 (en) | 2004-11-09 | 2008-03-11 | Fultec Semiconductor, Inc. | Apparatus and method for enhanced transient blocking |
| US7492566B2 (en) | 2005-01-14 | 2009-02-17 | Bourns, Inc. | Low resistance transient blocking unit |
| US7576962B2 (en) | 2005-06-16 | 2009-08-18 | Bourns, Inc. | Transient blocking apparatus with reset |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU427645B2 (en) * | 1967-06-02 | 1969-11-20 | A circuit arrangement for limiting the starting current impulse in transformers for current supply devices ofthe communication art | |
| AU572250B2 (en) * | 1983-09-19 | 1988-05-05 | Alcatel N.V. | Electronic switch and associated devices |
| AU613467B2 (en) * | 1988-04-22 | 1991-08-01 | Alcatel N.V. | Current surge limiter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1253915A (en) * | 1984-07-05 | 1989-05-09 | Kazuhiro Sato | Overcurrent protection circuit |
| US4891728A (en) * | 1986-12-23 | 1990-01-02 | Siemens Aktiengesellschaft | Circuit arrangement for limiting the switch-on current and for providing an over voltage protection in switch mode power supply devices |
| DE3903789C2 (en) * | 1989-02-09 | 1995-02-02 | Sel Alcatel Ag | Circuit arrangement for inrush current limitation |
-
1990
- 1990-04-28 DE DE19904013731 patent/DE4013731C2/en not_active Expired - Fee Related
-
1991
- 1991-04-16 AU AU75035/91A patent/AU641491B2/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU427645B2 (en) * | 1967-06-02 | 1969-11-20 | A circuit arrangement for limiting the starting current impulse in transformers for current supply devices ofthe communication art | |
| AU572250B2 (en) * | 1983-09-19 | 1988-05-05 | Alcatel N.V. | Electronic switch and associated devices |
| AU613467B2 (en) * | 1988-04-22 | 1991-08-01 | Alcatel N.V. | Current surge limiter |
Also Published As
| Publication number | Publication date |
|---|---|
| DE4013731C2 (en) | 1995-07-13 |
| AU7503591A (en) | 1991-11-07 |
| DE4013731A1 (en) | 1991-10-31 |
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