DE1463251C - Protective circuit for overcurrent shutdown using a protective switch for a power converter with a phase control circuit, which responds to overcurrent - Google Patents

Description

The invention relates to a protective scarf In this way, the throttling is in the event of an overcurrent for overcurrent shutdown using coil shorted by the circuit breaker and a circuit breaker that responds in the event of an overcurrent, the phase shift increases practically instantaneously for a converter with a phase control switch zero made so that the converter is blocked, device that has a phase rotation circuit with a through a 5 The switching capacity of the circuit breaker can behave- control direct current premagnetizable, saturable nismoderately low, because also those at the choke-choke coil contains which phase rotation circle such coil dropping voltage is relatively low is dimensioned that can be with a phase shift of.

90 ° the maximum current is delivered and with a Preferably, the circuit breaker consists of one

Phase shift of 0 ° the current is blocked io magnetically operated reed switch, the

There are already phase control circuits for current excitation windings in a current measuring circuit, and

Richter known (AEG-Mitteilungen, 49, 1959, 10/11, an electronic

P. 492 to 495), the saturable choke coils, switching element.

voltage-controlling transducers or similar In the switching path of the circuit breaker, min-

Contain devices that are the phase position of the 15 least one controllable silicon rectifier.

Converter ignition pulses depending on a Preferably the controllable silicon rectifier

Shift the control signal so that the converter has the ter between two opposite terminals of a '.

Has desired current flow angle. The phase diode bridge switched, with the remaining

The ignition pulses are shifted by the pair of clamps connecting the diode bridge to the saturable

the control signal is the point in the period that the inductor is located.

Choke coil feeding AC voltage determined, in series with the controllable silicon rectifier

in which the core of the choke coil is saturated. Another saturable choke coil can also be used.

the choke coil then flows a pulsed current that is switched on. -

the time of use with the time of saturation For these training courses, protection is only given in

the choke coil coincides and therefore displaceable 25 bond with the subject matter of the main claim

is cash. These impulses form the ignition impulses of the desired.

Converter. Such a phase control circuit. The invention is described below with reference to FIG

is explained in particular because of their robustness and tem- figures.

temperature insensitivity preferred. Based on FIG. 1, a schematic block diagram is a

inevitable self-inductance of the saturable 30 phase control circuit, which is a fast-responding

Choke coil has this phase control circuit each current-limiting protective circuit according to the invention

but a response delay time that has in manure;

is negligible in many cases, but then in Fig. 2 shows several diagrams showing the course

Weight falls when the current conduction angle reflects the voltage over time and for

judge, z. B. in the event of an overload, on the phase 35 Explanation of the operation of the in F i g. 1 shown

control circuit to be controlled back to zero immediately serve circuit; i

the should. In this case, the response delay would be F i g. 3 is a circuit diagram of a. Embodiment '

Approximation time of the phase control circuit too large to be a protection circuit according to the invention;

for example, in the event of a consumer-side short circuit F i g. 4 is a schematic circuit diagram of another

according to this by blocking the converter via the Sät- 4 ° teren embodiment of a protection circuit

shutdown phase control circuit before using the invention;

has had a harmful effect. Fig. 5 is a schematic circuit diagram of a third

It is also known for quick disconnection of th embodiment of a protective circuit according to

Converter systems with an output-side over- the invention; ·. ι

current to the control terminals of the controllable 45 Fig. 6 is a schematic circuit diagram of a fourth!

Rectifier of the converter fed ignition embodiment of a protective circuit according to the

pulses by an invention responsive to the overcurrent;

Interrupt or short-circuit the rapid relay. Fig. 7 shows several diagrams showing the course j

(AEG reports, 41, 1951, 9/10, pp. 240 to 243). the voltage over time and to illustrate

The disadvantage here is that the high-speed switching relay is a modification of the switching shown in FIGS. 3 to 6

must have a high switching capacity because the ignition pieces are used; j

pulse controllable rectifier for safe and

rapid ignition of the controllable rectifier a changed embodiment ein.er short circuit \

must have relatively high power. So with a controlled silicon rectifier, which one j

the grid circuit is interrupted at 55 for the protective S shown in FIGS. 3 to 6

the well-known grid shutdown in mercury. circuits can use; ' }

Over-vapor converter systems via contactors, Fig. 9 is a schematic circuit diagram of a two!

in turn by responding to the overcurrent th embodiment of a short circuit mil j

Fast switching relays can be switched. Apart from that, a controlled silicon rectifier, which is used in ver

from that powerful contactors costly 60 binding with the j shown in FIGS. 3 to 6

are, they also have a relatively large amount of protection circuits that can be used. j

Speech delay, which is still to that of the fast The circuit 1 shown in Fig. 1 is used for

switching relay added. Control of the phase shift and includes a j

According to the invention, these disadvantages, from quickly responding current-limiting protective switching

going from the protective circuit mentioned at the beginning, 65 device. The circuit 1 can, for. B. to control the

thereby avoided that the output current of an inverter circuit is closed in the event of an overcurrent

scne switching path of the circuit breaker parallel to the one that has a bridge circuit with four j

saturable inductor is connected. controlled silicon rectifiers SCR-I to SCR-4

3 4

owns. The output 101 of the circuit 1 is with the remains until it is blocked again. That can lock

Primary winding la of a pulse transformer 2 can be achieved in that the trailing edge of each

Connected in series. This series connection is fed to a blocking circuit via an ignition pulse,

Voltage source to the terminals Sa and which causes each rectifier only during the

Sb switched. The voltage source ensures that the ignition pulse remains conductive for a long time. How out

Angular switching voltage 3 available. Nor- Fig. 2 can be seen is the rectifier SCR-I

Sometimes the circuit calls 1 on the primary winding during positive half-waves of the voltage 3, the

treatment 2 a produces an output signal whose phase in rectifier SCR-2 during negative half-waves

is shifted with respect to voltage 3 and that of voltage 3, the rectifier SCR-3 during

the secondary winding 2 & a multivibrator 4 to- io positive output pulses of the multivibrator 4 and

to be led. The output of the multivibrator 4 is the rectifier 5Ci? -4 during negative output-

with the control electrodes of the controlled silicon pulses of the multivibrator 4 conductive. If you compare

rectifier SCR -3 and SCR-4 connected. The multi-Fig. 2, (a) and (c), it can be seen that during

vibrator 4 leads the controlled rectifiers SCR-3 of certain period segments the controlled SiIi-

and SCR-4 to a square-wave trigger voltage, 15 zium rectifiers SCR-I and SCR-4 at the same time.

which these controlled rectifiers in a pre- and that during similar periods

Matched sequence turns on, which depends on the size of the controlled silicon rectifier SCR-2 and

from the circuit 1 caused phase shift SCR-3 conduct simultaneously. During these periods

exercise is determined. The switching voltage 3 is without sections in which the conductive time sections

Phase shift via the lines 5 a ' and 5 b' 20 of the relevant controlled silicon rectifier

to the control electrodes of the controlled silicon overlap, the bridge circuit dem

rectifier SCR-I and SCR-2 laid. The bridge consumer 6 is supplied with power, as shown in Fig. 2, (d)

circuit is completed by a series circuit. To increase the consumer flow or

device with a consumer 6 and an overcurrent to reduce, these overlap times,

sensitive device 7. This series connection 25 during which two related controlled

lies between the connection point of the controlled silicon rectifier at the same time conduct, through a

Silicon rectifier SCR-3 and SCR-4 and the increase or decrease of the circuit 1

Connection point of the controlled silicon rectifier called phase shift enlarged or

ter 5C /? - l and SCR-2. Smaller at the + and - terminals. If z. B. the controlled by circuit 1

If a DC voltage is applied to the bridge circuit, the phase shift is reduced to zero,

out of the bridge circuit in a pulse as shown in Fi g. 2, (b) shows the dashed curve,

shaped alternating voltage is converted. Then there are no overlapping times with simultaneous

AC voltage is used to supply the electrical conductivity on, and the consumer is

6. no power supplied, as shown in FIG. 2, (e) shown

The device 7 is an overcurrent-sensitive 35. An object of the invention is a device that

Resistance or a current transformer with a low In- the circuit 1 very quickly in such a supply

ductility. A cable 8 α connects the two ends was offset, in which the phase shift is zero

the current-sensitive device 7 is on, so that the consumer current is also zero.

output of a control circuit 8, the output of which as- F i g. 3 shows a schematic circuit diagram of a

which is connected to the circuit 1. The switching 40 phase control circuit that has been modified to include the

Device 8 contains a solenoid that switches the reed switch circuit to the fast-responding current limiting

ter in the circuits of FIG. 3, 5 and 6 actuated to give protective properties according to the invention,

and / or any suitable pulse shaper switch. In the circuit of FIG. 3, A point is 101

device that connects the control electrodes of the controlled SiIi- (see FIG. F i g. 1) to a network 13 that

zium rectifier in the circuits of FIGS. 4, 8 45 is surrounded by a dashed line. The network-

and 9 actuated. plant 13 is controlled by a winding 20 of the pulse transmission

The operation of the circuit of FIG. 1 can best be illustrated with the help of the diagrams in FIG. 2 Form of a saturable choke coil 9 and understand, which represent the time course of the voltage of a waveform network 10 from a counter over time. Fig. 2, (α) shows the right-hand 50 stand and a capacity formed. To control the angular trigger voltage 3, the voltage fed to the network 13 via the lines 5 a ' , a and Sb' the control electrodes of the controlled SiIi phase control circuit is used, for. B. a saturated rectifier 5Ci? -1 and SCR-2 directly fed choke coil 14 capable of supply. Under the expression is. F i g. 2, (b) shows the voltage that is generated by the "saturable choke coil" is supposed to be generated by the "saturable inductor" and the multivibrator 4, e.g. B. voltage-controlling transducers is supplied. F i g. 2, (c) shows the phase-shifted magnetic amplifier and the like. The saturable voltage, which at the output of the multivibrator 4 choke coil 14 actually contains two separate ones, and the control electrodes of the controlled saturable choke coils, their primary winding silicon rectifier SCR-3 and 5Ci? -4 fed 60 to 15 or 16 are and is connected in parallel to one another. The secondary windings 17 or 18 which appear at the output of the multivibrator 4 in idle mode have the same waveform. Each winding group 15, 17 and frequency like the original Triggerspan- 16,18 has its own control winding 3 assigned to it; however, their phase is shifted by an amount 19 or 21, respectively, by the period point that is determined by circuit 1. 65 put alternating voltage control at which the

It goes without saying that every controllable rectifying core of the component saturates. Such setup lessons by the leading edge of the ignition pulses in the gene are known and have been described, exemplary leading State is controlled and as long as conductive in the book "Magnetic Amplifiers" by Her-

5 6

bertF. Storm, edited by John Wiley and coil (not shown) operated in the control panel

Sons, Inc., New York (1955). device 8 is included and to operate the tongue

It is characteristic of such a saturation switch in FIG. 3, 5 and 6 is used. The magnetic choke coil as shown in FIG. 3 is shown, the coil is controlled by the overcurrent sensitive device it energizes an electrical current 5 supplied to it 7.

during the period of time taken to saturation As F i g. 3, B shows, one can need the resistors of their core, providing a normal impedance. 24 each have a smoothing capacitor 28 in parallel - then the impedance of the saturable coil switches, which is shown in dashed lines. The mean decreases to about zero. The saturation point of the saturation taps of the voltage divider resistors 24 and capable choke coil is determined by the control current i _c io 25 are sent to the corresponding control electrodes of the silicon rectifier 22 and 23 controlled by the control windings 19 and 21. The control current i _c can be closed. In this circuit structure, when the current through the load 6 is activated, the supply operated by the solenoid is closed. switch 26 an ignition voltage the control elec-

The effects of a change 15 on the controlled silicon rectifiers 22 and 23

of the control current in the control windings 19, 21 is supplied. As a result, the windings 15 and

can best be short-circuited at hand 16. The consequence of this is that the

of FIG. 7 will be described. F i g. 7, (a) shows caused by the saturable choke coil 14

a case in which the maximum control current phase shift almost instantly approaches zero.

flows through the control windings 19 and 21 and the 20 is returned.

saturable inductor almost instantly in FIG. 3, C shows a fast responding saturation protection device. The consequence of this is that the circuit with a single phase, the voltage supplied between the network 13 with respect to the terminals α and b of the switching input voltage 3 shown in Fig. 3, A can be switched to a very small or even device . The in Fig. 3, C has no phase shift, as shown in Fig. 7, (α) 25 shows the arrangement works in exactly the same way. If the control current i _{c is} applied to an intermediate circuit such as the circuit shown in FIG. 3, B is reduced, then causes the saturation circuit and is therefore not described again in the single choke coil that the input voltage varies. F i g. 3, D shows a third Ausrend of a period of time that is determined by the size of the control control form of a protection circuit, which one between currents, television from the network 13 see the terminals α and & of the in FIG. 3, A is kept shown. This arrangement appears on the network 13. In the circuit of this case, the waveform shown in Fig. 7, (b). A f i g. 3, D are two diodes 31 and 32 in countercurrent decrease in the control current i _c to a mini-parallel circuit above the value painted by the magnet coil, the leading edge of the voltage-activated reed switch 26 with the terminals α and b voltage on the network 13 moves further and further connected right to 35.

a minimum value as shown in Fig. 7, (c). The circuit of FIG. 4 is constructed in exactly the same way. By changing the control current i _c , it is possible like the circuit of FIG. 3, except that two phases of the leading edge of the voltage supplied to silicon controlled rectifiers 35 and 36 opposite the saturable choke coil are paralleled between terminals α and b from a zero value [F i g. 7, (a)] up to a maximum of 40 are switched to make the windings the saturable value of the phase shift [F i g. 7, (c)] to coil 14 to short circuit. Move the control electrodes. The saturable coil 14 has silicon rectifiers 35 and 36 which are connected to a delay time of their own when connected to the pulse source (not shown) shown in FIG. 7, (a) after the state shown in FIG. 7, (c) circuit 8 is included. The circuit 8 is a state shown or of that shown in FIG. 7, (c). 45 pulse shaper circuit that is used for the state shown in FIGS. 4, 8 after the circuits shown in FIGS. 7, (d) and 9 shown serves. The impulse state passes over. The latter case is from a larger source and supplies ignition pulses to the control electrodes, meaning. This delay time is created by the controlled silicon rectifiers 35 and 36, the time that the magnetic flux through the winding switch to the conductive state,
lungs 15 to 18 needed to build up or 50 F i g. 8 shows another circuit that can be made to decay. As a result, the self-response time can be seen at the terminals α and b in FIGS. 3 and 4 of the control circuit limited. Can switch to some of the circuits shown here. To avoid the in rities caused by the long-term response F i g. The arrangement shown in FIG. 8 only needs one time to be generated, the rapidly activated silicon rectifier 37, the invention between two corresponding current-limiting protective circuit according to the 55 opposite terminals of a diode bridge, was developed. is switched, which is formed by diodes 38. The two

F i g. 3, B shows an embodiment of a fast the remaining opposing clamps

responsive protective circuit, which are connected between the diode bridge via a choke coil 39 to

can switch terminals α and b. This fast time delay connected to terminals α and b

Responsive protection circuit contains two controlled 60 den. The only silicon controlled rectifier 37

Silicon rectifiers 22 and 23 in opposite parallel can be in series with a current limiting resistor

circuit. The control electrodes of the controlled SiIi stand 41 are. Its control electrode is with the

Zium rectifiers 22 and 23 are connected to the corresponding output winding 42 of a pulse transformer.

Ignition circuits connected, each tied two, which forms part of the control circuit 8.

Have voltage divider resistors 24 and 25. The 65 with the arrangement of F i g. 8 it is possible to use the

Resistors 24 and 25, together with a silicon controlled rectifier 37, are effective from the

Reed switch 26 and an isolating diode 27 in series. Delay coil 39 to separate. This allows a

The reed switches 26 are operated by a magnetic second device for phase control of the

output signal, which is fed to the consumer 13, can be used and a small controllable one Delay time can be introduced into the operational sequence of the fast-responding protective circuit. A consequence of this is that there is a small delay time (determined by the time it takes to saturating the delay coil 39) occurs before the saturable inductor 14 is shorted when the silicon controlled rectifier 37 is turned on. This little delay time can be set as required so that the protection circuit responds in the event of overload somewhat delayed.

Fig. 9 shows a similar protection circuit. This circuit uses a diode bridge with the diodes 38 and, for short-circuiting, a single silicon controlled rectifier 43 which is connected between an opposing pair of terminals of the diode bridge. The two remaining terminals of the diode bridge are connected via a current limiting resistor 44 between terminals α and b of the fast-responding protective circuit of FIG. 3 or 4. The resistor 44 serves to limit the short-circuit current which flows through the silicon rectifier 43. The control electrode of the silicon controlled rectifier 43 can be connected to the control circuit 8.

Another embodiment of a fast-responding current-limiting protective circuit for a phase control circuit is shown in FIG. 5 shown. In this case, only a single saturable choke coil 71 is used, the windings 72 and 73 of which are connected in parallel with the network 13 in series. A control winding 74 surrounds the two windings 72 and 73 and carries the control current i _c , which controls the period point of the applied input signal at which the core of the choke coil saturates. The circuit of FIG. 5 furthermore contains a bridge circuit with diodes 75. A pair of terminals of the diode bridge is connected to the connection terminals α and b in order to connect the diode bridge to the parallel windings 72 and 73 in parallel. Between the two remaining terminals of the diode bridge there is a series circuit which contains a linear inductance 76, a fast-responding switch 77 and a current limiting resistor 78. In this circuit structure, the linear choke coil ensures that only a minimal holding current is maintained through the fast-responding switching device in order to ensure that the fast-responding switching device does not open again prematurely. The quick-responding switch 77 could e.g. B. open again when actuated by the control circuit 8; however, the additional holding current due to the linear inductance prevents such reopening. The circuit therefore operates in exactly the same way as the circuit of FIG. 3.

In the embodiment of the invention shown in Fig. 6, a choke coil 76 was used for time delay added outside the diode bridge. The delay coil 76 is connected to one terminal of the diode bridge 75 and to the connection point between the wave-shaping choke coil 9 and the Winding 2 c connected. Since this circuit corresponds to the circuit arrangement of FIG. 8 is very similar, except that the reed switch 77 is replaced by the silicon controlled rectifier 37, these work both circuits in almost the same way.

Claims (5)

Patent claims: 1.Protective circuit for overcurrent disconnection using a protective switch for a converter with an overcurrent response, with a phase control circuit which contains a phase rotation circuit with a saturable choke coil which can be pre-magnetized by a direct current control current, which phase rotation circuit is dimensioned in such a way that with a phase shift of 90 ° the maximum Current is delivered and the current is blocked with a phase shift of 0 °, characterized in that the switching path of the circuit breaker (Fig. 3, B, C, D; Fig. 5; Fig. 6; Fig. 8; Fig 9) is connected in parallel with (a, b) the saturable choke coil (14, 71). 2. Protection circuit according to claim 1, characterized in that the circuit breaker consists of a magnetically operated reed switch, the excitation winding of which is in a current measuring circuit, and an electronic switching element (22, 23) controlled by its contact (26). 3. Protection circuit according to claim 1 or 2, characterized in that in the switching path the circuit breaker is at least one controllable silicon rectifier. 4. Protection circuit according to claim 3, characterized in that the controllable silicon rectifier (37, 43) is connected between two opposite terminals of a diode bridge (38) and that the remaining pair of terminals of the diode bridge on the saturable choke coil (14, 71) lies. 5. Protection circuit according to claim 3, characterized in that a further saturable choke coil (39) is connected in series with a controllable silicon rectifier (37). 1 sheet of drawings 009 522/170