CN1251224A

CN1251224A - Electronic safety device

Info

Publication number: CN1251224A
Application number: CN 98803643
Authority: CN
Inventors: B·比藤; B·布拉古斯
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1997-03-24
Filing date: 1998-03-20
Publication date: 2000-04-19
Also published as: BR9808624A; DE19712261A1; WO1998043334A1; EP0970555A1

Abstract

The invention relates to a circuit of an electronic fuse, wherein the criterion used to identify a short circuit and to disconnect a user is the energy converted in the switch transistor of the converter. Surges caused by voltage drops are not taken into account.

Description

Electronic safety device

The task of safety device is can stop to a defective parallel circuit to continue intake.Therefore for example in the DC-DC converter circuit, input voltage is transformed into the voltage through overregulating, and is noted that especially for sort circuit defective parallel circuit and input voltage are kept apart, and to avoid consequent malfunction, for example overheated or fire burns.Be connected with in the system of a plurality of this current transformers a supply line, must watch out for fault at the input circuit sudden short circuit of this current transformer.This is owing to flow through sizable electric current (ampere up to a hundred) when being short-circuited, this electric current can make system voltage be subjected to very big influence in the time interval before a safety device action, it also may cause other voltage landing by the output of the converter of same system voltage power supply, consequently cause loss of data, must restart.In order to prevent this from occurring, compensating circuit of each self-configuring of each converter by the system voltage power supply, this circuit is made of a decoupling diode and capacitor.When fault took place, according to the energy of laying in capacitor, user's power supply can also continue for some time.The voltage landing do not occur in order to keep normal operation, the capacitance of described capacitor must be enough big, so that can realize the bridge joint power supply when disturbance appears in voltage source voltage.The duration that short circuit is interrupted is directly depended on the type of the safety device that is disposed, and opening time is long more, and the capacitance of the capacitor that is connected in parallel on user's input is just big more.

Past; people stress to use fuse as safety device always; because fuse is shorter opening time than automatic safety device; at present; seen that by the maintenance technology angle automatic safety device is used for the safeguard protection of circuit mostly, its shortcoming is; need long opening time and the capacitor that requires configuration than high capacitance, therefore need take than large space and the more funds of input.

The purpose of this invention is to provide a kind of improved electronic safety device circuit.

Above-mentioned purpose is to adopt the technical characterictic of claim 1 and claim 4 to realize.

The present invention has such advantage, and it is subject to disturbance, and can not make mistakes when the short time voltage fluctuation appears in voltage source voltage and stop, and the present invention can omit the capacitor of high capacitance thus.Another advantage of the present invention is that its safety device only is made up of parts seldom, and is very economical.

Another advantage of the present invention is that the switching transistor that is adopted the overload problem can not take place.

Other characteristics of the present invention and function embodiment are in the theme of dependent claims.

Further specify other technologies details of the present invention below in conjunction with embodiment shown in the drawings.

Accompanying drawing is:

The circuit theory diagrams of an electronic safety device of Fig. 1;

Circuit design drawing of Fig. 2;

Fig. 3 voltage and current characteristics curve chart.

Circuit element M1 among the figure for example is a mosfet switching transistor, can extract the voltage between the drain electrode and source electrode during the current limliting, because at this moment, the electric current that flows through switching transistor M1 is changeless, leakage-source voltage be exactly switching transistor M1 moment loss power through image.Transistor voltage is carried out integral and calculating from a selectable undulating value, and people obtain a signal corresponding to loss of energy thus.According to well-known area of safety operaton SOAR chart (for example Siemens's databook SIPMOS-power transistor, 93/94, the 641 page), can know for various switching transistors to allow energy (maximum permission time of Power x) until the maximum of damaging.

Fig. 1 is the circuit theory diagrams of an electronic safety device.The unit that shows in these circuit theory diagrams comprises that a boost voltage generates the HV of unit, a flow straightener SR (the first data analysis unit), an integral computer INT (the second data analysis unit), a comparator K (the second data analysis unit) and a fault trigger FF.A boost voltage voltage source HV device realizes that to all the necessary parts of this circuit provide a voltage V through overregulating _Hilf

First SR of data analysis unit regulates the rated current of preset by measuring IST electric current (obtaining by the voltage on the measuring resistance Shunt), when operate as normal, flow straightener SR Control current is starkly lower than the rated current of preset, switching transistor M1 for example is a MOSFET, and this moment, it was complete conducting.When the electric current that flows through resistance Shunt surpassed rated current, flow straightener was limited in electric current below the load current value.Switching transistor M1 is by a load resistance R5 (Fig. 2) control conducting, and controlled when needed by flow straightener SR and to be in weak conducting state.When being short-circuited, switching transistor M1 is control like this, makes the input current of converter be limited at rated current.Fault trigger FF is limited to high level state (output is a high potential) at converter duration of work (being in system voltage), and it is connected with the load resistance R5 of MOSFETM1 by decoupling diode D2, D3.Under failure condition, that is to say when short circuit fault trigger FF trigger action, voltage V _GateTo remain on null value, be interrupted so flow through the electric current of MOSFET M1.This fault trigger FF can be provided with after losing system voltage in short-term once more, is short-circuited if be in operation, and fault trigger FF moved after the short time, and MOSFETM1 is discharged.

Two kinds of different situations mainly are discussed here, and the input current or the electric current restriction that occur increasing are movable.First short circuit (representing with switch S in Fig. 1 and Fig. 2), it two is capacitor C _SP1And C _SP2Charging.Only when short circuit, just should open circuit.The specification of circuit of the present invention must satisfy following condition, and promptly (the worst situation is the input voltage peak to occur) can not reach the limit that opens circuit in charging process.In other words, mosfet transistor M1 can not leave its safety operation area SOAR when charging.

Under short-circuit conditions,, open circuit immediately in case reach the potential value of the adjusting on the comparator K.

Fig. 2 is a circuit design embodiment.Boost voltage module HV is responsible for the parallel circuit OP1 for example in circuit of the present invention ..., OP4 supplies with operating voltage.This operating voltage is supplied with via a Z diode Z1, under trouble-free normal operation, in this circuit, be by the positive potential control of the power supply potential source (UBAT) on resistance R 1 and the R5 (operating resistance) as the control input of the switching transistor M1 of MOSFET, this switching transistor M1 is that Be Controlled is through-flow, and resistance R 2 and R3 form a reference voltage voltage divider that is used for operational amplifier OP1.At the current potential on the negative input of operational amplifier is the voltage that descends on resistance Shunt and resistance R 4.Under failure condition, flow through the electric current of increase on the resistance Shunt, so reduce voltage V in the control of switching transistor M1 input by operational amplifier OP1 with by diode D1 _Gate, the electric current that flows through switching transistor M1 also reduces thereupon.The capacitor C3 that the control input of switching transistor M1 is connected with source electrode should stop according to the Miller capacitance value in the switching transistor M1 in a grafting process and is communicated with by M1.Capacitor C2 is the control element of flow straightener SR, and fault trigger FF is in a high level state on the output FF-OK after the on-state.Have only when the output of operational amplifier OP3 when electronegative potential (being confirmed to be short circuit), fault trigger FF just begins to reset.Make the control input of switching transistor M1 be in electronegative potential by diode D3 simultaneously, operational amplifier OP2 itself remains on electronegative potential by resistance R 9.

The INT of circuit unit is to quadraturing at the voltage that descends on the switching transistor M1 (voltage drop on resistance Shunt is very little, can ignore), in the control that is subjected to operational amplifier OP1 under the current limliting situation that appears at of the decline of the voltage on the switching transistor M1.The INT of circuit unit at first begins the process of quadraturing according to a predetermined magnitude of voltage on the negative input of operational amplifier OP4, regulate by resistance R 13, R12, if should value coincide mutually with the Current Regulation of the first data analysis unit, carry out first integral according to this reference voltage integrator (an irreversible integrator), if greater than the reference voltage on resistance R 13, obtain this time point at the last voltage that descends of resistance R 15 (voltage divider R16, R15).Under the current limliting situation, the maximum that can be limited in switching transistor M1 up conversion by comparator K allows energy.By voltage divider R10, the R11 in the positive pole input of comparator K, can obtain the magnitude of voltage of an adjusting.Have the actual voltage value of integrator INT in the negative pole input of comparator K, in case surpass the magnitude of voltage that its positive pole is imported at the magnitude of voltage in the output of integrator INT, the output of comparator is an electronegative potential.This electronegative potential triggers fault trigger FF on the one hand, and transmits the control input end of this electronegative potential to switching transistor M1 by diode D4, D2.

The filter that disposes in the main line of DC-to-DC converter is by coupling choke L1, a L2 and a capacitor C who is connected the choke both sides _SP1And C _SP2Constitute, its main task is to capture pulse current, and the decoupling diode ED between switching transistor M1 and inductance L 2 should stop capacitor C at system voltage (UBAT) when voltage disturbance occurring _SP1And C _SP2Discharge.Capacitor C _SP1And C _SP2Charging can not cause opening circuit.At capacitor C _SP1And C _SP2Between choke and these capacitors constitute an oscillation circuit, the existence of this oscillation circuit can not damage the function of electronic safety device.

Signal curve 3a-31 is illustrated in the voltage curve or the current curve of the circuit shown in Fig. 1,2, can be well understood to the function of electronic safety device from these curves.

Fig. 3 A, 3D, 3G, 3J are the voltage Vdrain in the drain electrode of system voltage (UBAT) and switching transistor M1.

Fig. 3 B, 3E, 3H, 3K are the electric currents that flows through resistance SHUNT and resistance R MESS.

Fig. 3 C, 3F, 3I, 3L are the output voltage curves on comparative voltage Vkomp, Lgnd curve and the fault trigger on the voltage Vint, Lgnd curve, comparator on the integrator output terminal.

Signal curve 3A, 3B and 3C are capacitor C when connecting with system voltage _SP1, C _SP2Charging process.

The Current limited Control that after connecting system voltage VEIN, will begin in a minute, capacitor C _SP1And C _SP2Qualification is charged by electric current I (SHUNT).This causes the voltage drop in the drain electrode of MOSFET, and current transformer is to be in unactivated state (I (RMESS)=0) at the moment, and the voltage of obtaining by integrator INT integration can not surpass comparison value given in advance on comparator.(V (FF-OK, LGND)) during starts can not reset the output signal of fault trigger, so the generation of not opening circuit.

Fig. 3 D-3F is account for voltage source voltage interruption and one signal curve of charging process once more.Suppose that current transformer activates, and require a changeless power output.If system voltage is interrupted, user's (current transformer) can continue operation.Capacitor C _SP1And C _SP2On voltage (for example ELKOS) begin to descend (3D), the input current of current transformer increases, voltage is more little (constant power) just.If reach lower voltage limit, current transformer opens circuit (I (RMESS)=0) (3E).If restart to connect system voltage, then carry out the essentially identical process shown in signal curve 3A, 3B, 3C.But unique difference is that capacitor is now by the current charges that descends through current transformer, so precipitous slightly rising appears in the voltage on the capacitor, and in this case, the load of switching transistor M1 remains under the limiting value given in advance, and switching transistor M1 can not ended.

Electric current and voltage curve when signal curve 3G-3I is the short circuit generation.By means of the short circuit that illustrated switch S produces a 100M ohm, short circuit current can directly be measured on electric current I (RMESS), by the quick Current limited Control of MOSFET, until the current spike of a weak point, obtains a stable electric current at last.After this, the drain voltage on the MOSFET does not descend or has only very little decline, the voltage on integrator to rise to a starting value rapidly, then triggering fault trigger (V (FF-OK, LGND).This output that triggers element (KIPPGLIEDES) opens circuit switching transistor M1 in electronegative potential.

Signal curve 3J-3L is the characteristic curve that is short-circuited when a grafting process.Voltage drop between source electrode and drain electrode is kept and is not reduced, and this voltage is obtained integration fast, and comparator transforms to electronegative potential when reaching comparison value, and triggers trigger FF, and switching transistor M1 opens circuit.

Aforesaid electronic safety device is installed on all current transformers in system, is not needed to increase the extra connect hours, its positive role obviously is better than installing the input of required cost of current transformer itself and space requirement.

Claims

1, a kind of method of when short circuit, isolating user and voltage source (UBAT), wherein when surpassing the short circuit current of measuring by the first data analysis unit (SR), play metering function or realize the isolation of user and voltage source by regulating a switch element of control (M1), it is characterized in that, when too high output current takes place, described switch element (M1) becomes high value, obtain voltage drop on the described switch element (M1) by the second data analysis unit (A), and when surpassing comparison value, described switch element (M1) is ended.

According to the method for claim 1, it is characterized in that 2, the voltage drop on the described switch element (M1) is quadratured in data analysis unit (A).

According to the method for claim 1, it is characterized in that 3, when being short-circuited, described switch element (M1) remain off state reconnects with voltage source (VBAT) or till this voltage source reworks once more up to user (V).

4, a kind of circuit arrangement of when short circuit, isolating user (U) and voltage source (VBAT), have one first data analysis unit (SR), be used to measure short circuit current and limiting short-circuit current, perhaps control the isolation that a switch element (M1) that is connected between voltage source and the user is realized user (V) and voltage source (UBAT) by regulating, it is characterized in that, one second data analysis unit (A) has an integrator (INT) and a comparator (K), the voltage that is used for the decline of monitoring on switch element (M1), the first input end of integrator (INT) is connected with the output of switch element (M1), second input of integrator is connected with a reference potential, and the output of comparator is connected with the control input end of switch element (M1).

5, according to the circuit arrangement of claim 4, it is characterized in that, the described first data analysis unit (SR) is a differential amplifier (OP1), it is by the described switch element of reference input regulating and controlling (M1), the integrator (INT) of the second data analysis unit (A) is made of one second differential amplifier (OP4), and the first input end of described second differential amplifier (OP4) is connected with described reference input.

According to the circuit arrangement of claim 4, it is characterized in that 6, (R15's second input of differential amplifier (OP4) R16) is connected with an output (VDRAIN) of switch element (M1) by a voltage divider.

According to the circuit arrangement of claim 4, it is characterized in that 7, integrator (INT) is an irreversible integrator.

According to the circuit arrangement of claim 4, it is characterized in that 8, the output of comparator (K) is connected with the control input end of switch element (M1).

According to the circuit arrangement of claim 4, it is characterized in that 9, the output that triggers element (FF) is connected with the control input end of switch element (M1).

According to the circuit arrangement of claim 4, it is characterized in that 10, the output of comparator (K) is connected by the first input end of a voltage divider with a differential amplifier (OP2) of described triggering element (FF).