CH658837A5 - Circuit arrangement for driving a current load in a failsafe fashion in terms of signalling technology - Google Patents

Description

The invention relates to a circuit arrangement for checking signals for errors and thus signaling safety for the technically safe control of a current consumer. enough.

658 837

The design of the electronic inverter is the subject of claim 4, while claims 5 and 6 relate to different types of control of the electronic inverter. The type of control described in claim 5 is particularly suitable for use together with inverters with quenching capacitors, while the type of control described in claim 6 can advantageously be used with inverters with quenching thyristors.

With inverters with quenching thyristors, signals without safety responsibility, e.g. Enter control pulses for the quenching thyristors via OR gates, which contributes to increasing the operational reliability.

Refinements of the circuit arrangement according to the invention, which are described in claims 8 and 9, relate to the blocking and interrupting means which prevent operation or actuation of the power consumer to be controlled in the event of a fault. The circuit arrangement can thus be adapted to the load to be controlled. Claim 10 relates to the processing of feedback signals of the actuators to be controlled.

On the basis of three circuit diagrams, exemplary embodiments of the circuit arrangement according to the invention will now be described in detail and their mode of operation will be explained.

Fig. 1 shows the principle of the circuit arrangement;

Fig. 2 shows the control of a single-phase inverter with quenching thyristors;

Fig. 3 shows a circuit arrangement for controlling a point machine.

1 shows two current consumers, an asynchronous motor 7 in a delta connection and a light source 8 of a signal lantern. These current consumers are combined to form an actuator unit 1 and are controlled via a common data line 10. The electrical line is taken from a three-phase supply network 13.

The actuator unit contains a rectifier 2, which provides two oppositely polarized direct voltages with respect to a common ground potential (eg rail potential) on two output lines 11, 12. The DC intermediate circuit created in this way feeds two controllable inverters 3, 4 via fuse elements 14, 15 and 16, 17, respectively, which supply the two current consumers with alternating current. In this case, the inverter 3 is of three-phase design and directly supplies the asynchronous motor 7, which can be a switch drive motor, for example. The inverter 4 is single-phase and outputs its alternating current to the light source 8 via a transformer 9. Depending on the design of the rectifier, more than two current consumers can also be connected to a DC circuit. The inverters are controlled by redundantly designed control circuits 5, 6, which convert control commands received via data line 10 in the form of data telegrams into control pulses for switching through or deleting the semiconductor switches (thyristors or transistors) contained in the inverters. The signaling safety, especially with regard to errors in the semiconductor components contained in the inverters, is, as will be shown, by the fuse elements, in the case of ohmic load by additionally inserted blocking means (e.g. transformer 9), which cause a direct current flow through the Prevent electricity consumers, guaranteed.

The control of an inverter for a single-phase current consumer is shown in FIG. 2. The inverter 4 contains, as a semiconductor switch, two main thyristors 18, which alternately connect the AC voltage output 22 via commutation reactors 20 and fuses 16, 17 to the positive output 11 and the negative output 12 of the one shown in FIG. Connect 2 DC intermediate circuit, not shown. The main thyristors are switched through via AND gates 24 by control pulses which are output by two microcomputers 25, 26 at the same time to the inputs of the individual AND gates.

If thyristors are used, as shown in FIG. 2, the previously live thyristor must be deleted at least with each phase change. This is done in the circuit shown in FIG. 2 by means of a commutation capacitor 21 and two quenching thyristors 19. Here, the quenching thyristors are also controlled by OR gates 23 by the microcomputers. Or gates can be used here, since the absence of the deletion - in contrast to an erroneous switching of the main thyristors - cannot lead to a safety-threatening state. At most, there may be a short circuit that triggers fuses 16 and 17 and is recognized with certainty. On the other hand, the use of the OR elements has the advantage that a defect which disables an output of a microcomputer connected to the relevant OR element does not yet lead to a failure of the entire control, since the second microcomputer still Outputs control pulses for the quenching thyristors.

The microcomputers 25, 26 receive their working cycle from 20 a clock generator 27 via a clock pulse input 30. Control commands are received via a common data line 29. The security of the processing of the control commands is achieved by a comparison of results, which after mutual data exchange via a data connection 28 is carried out independently in both computers and leads to a setting of the control pulse output if a processing error is determined.

The microcomputer can also be used to convert status messages from the actuator into data telegrams 30 and via the data line 29 or another data line, not shown, to a central monitoring point, e.g. B. a signal box.

In the circuit according to FIG. 2, which is intended to supply a signal lantern with current, for example, in addition to errors due to semiconductor failures 35, which lead to the absence of AC voltage or to the tripping of the fuses and which cannot bring about a safety-threatening state, an error is also possible, which Output of direct current via the output 22 leads. Since a signal lantern can also be operated 40 with direct current, it is necessary in this case. B. upstream of a transformer (as in Fig. 1) to prevent direct current flow through the power consumer.

The control of signal lanterns with the circuit arrangement according to the invention makes it possible to regulate the voltage in order to adapt the brightness of the signal lantern to the ambient brightness. This can then be done either via special data telegrams that specify a different control pulse sequence, or automatically, by means of a sensor circuit (not shown) connected to the microcomputers. Such a special day / night switchover can then be omitted.

3 shows a circuit arrangement according to the invention for an asynchronous motor 38 in a delta connection. This can e.g. B. be used in a point machine 37. The power required for operation is taken from a DC 55 intermediate circuit, which is supplied by a rectifier 35 and is protected against overcurrent by means of a fuse 36. As in the exemplary embodiment shown in FIG. 2, the control commands are given via a data line 33 in the form of data telegrams to two microcomputers 31, 32 60, which process all data telegrams in parallel and, after data exchange and comparison of results (via data connection 34), directly apply the corresponding control pulse sequences output the control electrodes of six main thyristors 39. Since the circuit according to FIG. 3 contains no quenching thyristors, 65 it cannot be used for voltage regulation. However, the frequency of the output voltage can be varied within wide limits. This enables the asynchronous motor to be started slowly in a delta connection, so that a star-three

658 837

corner switching to increase the starting torque can be omitted.

The commutation takes place here via commutation capacitors 41, with the function of the quenching thyristor being carried out by the main thyristor which is currently in turn for switching the current through. Diodes 40 serve to decouple the individual thyristor valves and to protect the thyristors by voltage peaks induced in the motor winding.

It can easily be seen from the figure that each semiconductor failure must lead to a short circuit and thus to the fuse responding after a short time. Can a thyristor e.g. no longer delete, a short-circuit occurs as soon as counter-voltage is applied to the corresponding connection of the asynchronous motor after the thyristor connected to the counter-voltage has been turned on. If a thyristor can no longer be switched through, the previously active thyristor is not deleted and a short circuit occurs for this reason. A short circuit also arises in any case where one of the thyristors, without having received a control pulse, switches through outside the intended time interval.

With this circuit, status messages, e.g. B. 10 transmit the turnout via the microcomputer and the data line 33 with signaling security to the associated signal box, provided that appropriate precautions (connection of the test contacts to the microcomputer, appropriately designed software) are taken.

M

3 sheets of drawings

Claims (10)

658 837 2 PATENT CLAIMS Such circuits are mainly used in railway signal 1. Circuit arrangement for signal-technically safe locations, but also in other technical facilities where it is important to control a current consumer, in particular for the greatest possible safety of operation. They train signaling devices, characterized in that an over differ from ordinary circuits in that a redundantly designed control circuit (5,6) controllable 5 they fulfill two important requirements: A fault, eg. B. a rer electronically safe inverter (3, 4) is provided, via the component failure, must never lead to a safety-endangering power consumer (7, 8) the suffering switching state necessary for operation. Every fault must be drawn directly from a DC circuit (11, 12) and that it must be recognized after it has occurred. Previously known safe power consumers have blocking means (9) or interrupting means, upstream of control circuits such as those for electrically operated white (14, 15, 16, 17, 36), which, depending on the type of 10 or signals used so-called signal relays, i.e. Electricity consumers formed load, a direct current flow through relays, the contacts of which are checked back and which can only be prevented by the current consumers or switched if an over-energy supply occurs. These signal relays are energized to interrupt the power supply. protected from the weather inside a signal box 2. Circuit arrangement according to claim 1, characterized and housed and switch from there the operating current of the draws that the redundant control circuit (5, 6) 15 of the respective current consumer. Due to the voltage drop, two microcomputers (25, 26 or 31, 32) contain which control signal in the cable feed is limited to the position distance, and signals with safety responsibility for controlling the elec- The costs for the low-resistance cable feed are high. Work out a tronic inverter (3, 4, 42) in parallel, including the signal relays near the actuators, e.g. compare other and only if there is agreement on the electrical on a switch, a control via signal wires would pass on the inverter. 20 small cross-section and thus a reduction in costs 3. A circuit arrangement according to claim 2, characterized for the supply line, but would be very attractive because of the fact that the microcomputers of the redundant hard environmental conditions (aggressive vapors, condensation, control circuit, a common serial input (10, 29) large temperature fluctuations) problematic. A use for the reception of data telegrams and a data channel of semiconductor components instead of the signal relays was avoided up to (28.34) for the exchange of their results for the sake of comparison, since these components do not indicate anything more reliable. State is known. A transistor or thyristor can 4. Circuit arrangement according to one of claims 1 to 3, fault either become electrically impermeable or characterized in that the electronic inverter form a short circuit. A sudden becoming conductive (3,4,42) to control its output current controllable without activation cannot be ruled out. Semiconductors such as thyristors (18, 19, 39) or transistors on 30 The invention enables such a signal-technically safe has. Control of electricity consumers without a relay with a pure 5. Circuit arrangement according to claim 4, characterized in electronic circuit arrangement. It is characterized in that the control of the electronic inverter is described in part of claim 1. ters (42) by the microcomputers directly via the control electronics. The controllable semiconductors (39) are implemented in the circuit arrangement according to the invention. Controllable inverters used are in themselves 6. Circuit arrangement according to claim 4, thereby known. You will u. a. for the control of asynchronous motors is characterized by the fact that the control of the electronic inverter is used (see W. Leonhard, "Regulation in the electri-ters (4) by the microcomputers via AND elements (24), see drive technology", page 154-157 , Teubner-Verlag, Stuttgart-entrances with outputs of both microcomputers (25, gart). 26) and their outputs with the control electrodes of the controllable 40 The circuit arrangement according to the invention can be connected without a semiconductor (18). special additional measures near the actuators 7. Circuit arrangement according to claim 6, characterized in that the components used, in particular that the microcomputer control signals without security when they are cast in plastic, largely irresponsible via OR elements (23) to the electronic. are sensitive to harmful environmental influences. In addition to the inverters (4), the inputs of which each have 43 advantages, which brings indirect control of the actuators with them to both microcomputers and their outputs with control electronics, there are further advantages through the use of the controllable semiconductor (19). are connected. controllable inverter achieved with relays either 8. Circuit arrangement according to one of the preceding claims not achieved at all or only with additional effort, characterized in that can be controlled. So now z. B. instead of a day / night of a current consumer (8), which represents an essentially ohmic 50 brightness switchover from signal lamps a voltage rain load, a transformer (9) can be made between controllable lungs, which are time-dependent or dependent on inverters (4) and current consumers (8 ) is switched. depends on the ambient brightness. Point machine 9. Circuit arrangement according to one of claims 1 to 7, can be started at a low frequency in a delta connection, characterized in that when driving a current, the previously conventional star-delta switchover can be user (7), which represents an essentially inductive load , 55 omitted. a fuse (14, 15) or an overcurrent protection switch in the particularly versatile circuit arrangement according to the DC circuit is. Invention are used when the redundant trained 10. Circuit arrangement according to one of claims 2 to 9, control circuit, as specified in claim 2, two micro-characterized in that the micro-computer contains additional ones, which work out all control signals in parallel and compare gears for status reports of the power consumers 60 to be controlled . It is then possible to have several actuators and to be able to convert these status messages into data transmitters according to claim 3 via a common data channel and to control them via a data line. All control elements of a line can be issued by a central control point. then operate with a single data line and under a supply line. By comparing the control signals developed, 65 which is carried out after mutual data exchange in both microcomputers becomes the processing result