Bus system and method for operating a bus system
Patent Information
- Application Number
- EP2023711443
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-11
- Filing Date
- 2023-03-13
- Publication Date
- 2025-02-19
AI Technical Summary
Current bus systems for automation require additional and complex wiring for Safe Torque-Off (STO) signal transmission, which increases development and installation costs, and existing solutions require extensive drive development and commissioning according to safety guidelines.
A bus system with a data cable having at least four wires, where the feed module supplies DC voltage sources that can be switched between pairs of wires, and a detection unit in the consumer module monitors these voltages to transmit an STO signal, disconnecting the control unit from the supply voltage source when a switch-off signal is detected, thereby preventing torque generation without additional wiring.
This solution allows for safe and efficient transmission of the STO signal using existing data cable wires, reducing wiring effort and costs, while providing redundancy for increased security and reliability.
Smart Images
Figure 1.1
Abstract
Description
[0001] Bus system and method for operating a bus system
[0002] Description:
[0003] The invention relates to a bus system comprising a power supply module, a load module, and a data cable connecting the power supply module to the load module, wherein the data cable has multiple wires. The invention also relates to a method for operating a bus system according to the invention.
[0004] Today's automation systems feature bus systems for transmitting data between supply modules and load modules. Load modules, also known as field devices, include, for example, a control unit with power electronics for controlling an electric drive. A supply module is connected to a load module via a data cable with multiple wires for transmitting data signals.
[0005] One example of a generic bus system is EtherCAT. In its "Power Over EtherCAT" form, such a bus system offers not only data transmission but also the ability to provide two independent power sources for consumer modules.
[0006] An electric drive in such an automation system can be transferred to a safe operating state using a "Safe Torque Off" (STO) function. Such an STO signal can be transmitted, for example, via separate signal lines and prevents the generation of torque in the electric drive, for example, by deactivating the voltage supply to the gate drivers of the power electronics in the control unit. The disadvantage of this is the additional and complex wiring of the signal lines.
[0007] Alternatively, an STO signal can be transmitted via the bus system as a safe data set. The STO signal is evaluated in the load module, and torque generation on the electric drive is safely deactivated. Such a solution reduces wiring effort, but requires extensive drive development and commissioning in accordance with safety guidelines. Document DE 102016 109450 A1 discloses a bus system that includes a power supply module, a load module, and a data cable connecting the power supply module to the load module. The data cable has several wires for transmitting data signals and also allows the transmission of supply voltages.
[0008] DE 102015 116 800 B3 discloses an input / output module for a bus system that includes two DC power supplies. The DC power supplies are each connected to an electrical contact via an inductive module.
[0009] DE 102015 116 802 B3 discloses a bus system comprising a data cable with two wire pairs and an input / output module. The bus system includes two DC power supplies.
[0010] The invention is based on the object of developing a bus system and a method for operating a bus system.
[0011] The object is achieved according to the invention by a bus system having the features specified in claim 1. Advantageous embodiments and further developments are the subject of the subclaims. The object is also achieved by a method for operating a bus system according to the invention having the features specified in claim 6. Advantageous embodiments and further developments are the subject of the subclaims.
[0012] A bus system according to the invention comprises a feed-in module, a load module, and a data cable that connects the feed-in module to the load module. The data cable has at least a first wire, a second wire, a third wire, and a fourth wire, and the feed-in module has at least one DC voltage source that supplies a feed-in voltage. The feed-in module has a first switch, by means of which the feed-in voltage supplied by the DC voltage source can be applied between the first wire and the second wire. The load module has a detection unit that monitors a first voltage applied between the first wire and the second wire. The load module has a control unit, in particular for controlling a drive, which can be supplied by a supply voltage source that supplies a supply voltage.The detection unit has a controllable switching unit which disconnects the control unit from the supply voltage source when the detection unit detects a switch-off signal when monitoring the first voltage.
[0013] Using the bus system according to the invention, an STO signal can be easily and reliably transmitted as a shutdown signal from the supply module to the control unit of the load module, reliably preventing the generation of torque in the electric drive. The existing wires of the data cable are used to transmit the shutdown signal, thus eliminating the need for additional wiring. Furthermore, development and installation costs are relatively low.
[0014] According to an advantageous development, the feed module has a second switch, by means of which the feed voltage supplied by the DC voltage source can be applied between the third wire and the fourth wire, and the detection unit monitors a second voltage present between the third wire and the fourth wire. The switching unit disconnects the control unit from the supply voltage source if the detection unit detects a switch-off signal while monitoring the second voltage.
[0015] During normal operation of the bus system, the first switch and the second switch are closed. Thus, the supply module comprises two independent voltage sources for supplying components of the load module. The first voltage applied between the first wire and the second wire and the second voltage applied between the third wire and the fourth wire are available in the load module. A shutdown signal can be transmitted via each of these voltage sources. This redundancy advantageously increases safety.
[0016] According to an advantageous development, the detection unit detects a switch-off signal when the first voltage falls below a lower limit and / or when the second voltage falls below a lower limit. Opening the first switch causes the first voltage to drop. Opening the second switch causes the second voltage to drop. Such a voltage drop can be detected relatively quickly and reliably.
[0017] According to a preferred embodiment, the feed module has a data interface connected to the first wire and the second wire via a transformer and at least one capacitor in order to send a differential data signal to the first wire and the second wire. Likewise, the data interface is connected to the third wire and the fourth wire via a transformer and at least one capacitor in order to receive a differential data signal from the third wire and the fourth wire. The feed module is thus designed for data transmission in full-duplex mode. The data interface is galvanically isolated from the wires of the data cable.
[0018] According to a preferred embodiment, the consumer module has a data interface connected to the first wire and the second wire via a transformer and at least one capacitor in order to receive a differential data signal from the first wire and the second wire. Likewise, the data interface is connected to the third wire and the fourth wire via a transformer and at least one capacitor in order to send a differential data signal to the third wire and the fourth wire. The consumer module is thus designed for data transmission in full-duplex mode. The data interface is galvanically isolated from the wires of the data cable.
[0019] According to a method according to the invention for operating a bus system according to the invention, a switch-off signal is sent from the feed-in module to the first wire and the second wire. The detection unit monitors the first voltage present between the first wire and the second wire. If the switch-off signal is detected during monitoring of the first voltage, the switching unit is controlled such that the control unit is disconnected from the supply voltage source. Using the method according to the invention, an STO signal is transmitted as a switch-off signal simply and reliably from the feed-in module to the control unit of the load module. This reliably prevents the generation of torque on the electric drive.
[0020] According to an advantageous development, the feed-in module has a second switch, by means of which the feed-in voltage supplied by the DC voltage source can be applied between the third wire and the fourth wire. The feed-in module sends a switch-off signal to the third wire and the fourth wire. The detection unit monitors the second voltage present between the third and fourth wires. If the switch-off signal is detected during monitoring of the second voltage, the switching unit is controlled in such a way that the control unit is disconnected from the supply voltage source. Thus, a switch-off signal can be transmitted to the detection unit of the load module via each of the two voltage sources. This redundancy advantageously increases safety.According to an advantageous embodiment, a switch-off signal is sent to the first wire and the second wire by separating the DC voltage source from the first wire and / or the second wire by opening the first switch. A switch-off signal is detected by the detection unit when the first voltage falls below a lower limit. According to an advantageous embodiment, a switch-off signal is sent to the third wire and the fourth wire by separating the DC voltage source from the third wire and the fourth wire by opening the second switch. A switch-off signal is detected by the detection unit when the second voltage falls below a lower limit.
[0021] During normal operation of the bus system, the first switch and the second switch are closed. Opening the first switch causes the first voltage to drop. Opening the second switch causes the second voltage to drop. Such a voltage drop is detected relatively quickly and reliably by the detection unit.
[0022] According to an advantageous embodiment, a switch-off signal is sent to the first wire and the second wire by coupling a signal with a defined signal frequency into the first wire and the second wire. A switch-off signal is detected by the detection unit when a signal with the signal frequency is detected in the first voltage. According to an advantageous embodiment, a switch-off signal is sent to the third wire and the fourth wire by coupling a signal with a defined signal frequency into the third wire and the fourth wire. A switch-off signal is detected by the detection unit when a signal with the signal frequency is detected in the second voltage.
[0023] By coupling the shutdown signal as a signal with a defined signal frequency, the first voltage and the second voltage remain available to supply components of the load module even after the shutdown signal has been transmitted. The load module has an electronic circuit, for example, in the form of a bandpass filter, which detects the signal with the defined signal frequency.
[0024] According to an advantageous embodiment, a switch-off signal is sent to the first wire and the second wire by briefly separating the DC voltage source from the first wire and / or the second wire by opening and closing the first switch. A switch-off signal is detected by the detection unit when a brief interruption of the first voltage is detected. According to an advantageous embodiment, a switch-off signal is sent to the third wire and the fourth wire by briefly separating the DC voltage source from the third wire and / or the fourth wire by opening and closing the second switch. A switch-off signal is detected by the detection unit when a brief interruption of the second voltage is detected.
[0025] By briefly opening and closing one of the switches, the first voltage and the second voltage remain available to supply components of the load module even after the shutdown signal has been sent. The load module has an electronic circuit, for example in the form of a high-pass filter, which detects a brief interruption of the first voltage and the second voltage.
[0026] According to an advantageous development, the control unit has an evaluation unit that monitors the first voltage present between the first wire and the second wire, as well as the second voltage present between the third wire and the fourth wire. If the shutdown signal is detected during monitoring of the first voltage and / or during monitoring of the second voltage, the control unit is disconnected from the supply voltage source. In addition to the detection unit, the control unit also monitors the voltages present between the wires and disconnects the control unit from the supply voltage source when the shutdown signal is detected. This additional redundancy further increases safety.
[0027] The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.
[0028] The invention will now be explained in more detail with reference to the accompanying drawings. The invention is not limited to the exemplary embodiments shown in the drawings. The drawings only represent the subject matter of the invention schematically. It shows:
[0029] Figure 1 : a schematic representation of a bus system.
[0030] Figure 1 shows a schematic representation of a bus system. The automation system comprises a power supply module 10, a load module 20, and a data cable 30. The data cable 30 connects the power supply module 10 to the load module 20. The bus system is implemented, for example, as EtherCat or Power over EtherCat.
[0031] The data cable 30 has a first wire 31, a second wire 32, a third wire 33, and a fourth wire 34. The first wire 31 and the second wire 32 form a first wire pair, via which differential data signals can be transmitted. The third wire 33 and the fourth wire 34 form a second wire pair, via which differential data signals can also be transmitted.
[0032] The feed-in module 10 has a data interface 123. The data interface 123 is connected to the first wire 31 via a transformer 125 and a capacitor 127. The data interface 123 is connected to the second wire 32 via the transformer 125 and another capacitor 127. The data interface 123 is configured to send a differential data signal to the first wire 31 and the second wire 32.
[0033] The data interface 123 of the feed-in module 10 is connected to the third wire 33 via a further transformer 125 and a further capacitor 127. The data interface 123 is connected to the fourth wire 34 via the transformer 125 and a further capacitor 127. The data interface 123 is configured to receive a differential data signal from the third wire 33 and the fourth wire 34.
[0034] The load module 20 also has a data interface 123. The data interface 123 is connected to the first wire 31 via a transformer 125 and a capacitor 127. The data interface 123 is connected to the second wire 32 via the transformer 125 and a further capacitor 127. The data interface 123 is configured to receive a differential data signal from the first wire 31 and the second wire 32. The data interface 123 of the load module 20 is connected to the third wire 33 via a further transformer 125 and a further capacitor 127. The data interface 123 is connected to the fourth wire 34 via the transformer 125 and a further capacitor 127. The data interface 123 is configured to send a differential data signal to the third wire 33 and the fourth wire 34.
[0035] The feed-in module 10 has a DC voltage source 105, which supplies a feed-in voltage UE. The feed-in module 10 has a first switch 11. When the first switch 11 is closed, the DC voltage source 105 is connected to the first wire 31 via an inductance 121 and to the second wire 32 via another inductance 121. When the first switch 11 is closed, the feed-in voltage UE supplied by the DC voltage source 105 is present as the first voltage U1 between the first wire 31 and the second wire 32.
[0036] The feed module 10 also has a second switch 12. When the second switch 12 is closed, the DC voltage source 105 is connected to the third wire 33 via an inductor 121 and to the fourth wire 34 via another inductor 121. When the second switch 12 is closed, the feed voltage UE supplied by the DC voltage source 105 is present as a second voltage U2 between the third wire 33 and the fourth wire 34.
[0037] The load module 20 has a control unit 27. The control unit 27 is, for example, an inverter or a frequency converter and is used to control an electric drive. The control unit 27 is connected to a supply voltage source 29, which supplies a supply voltage UV, and can be supplied with electrical energy from the supply voltage source 29.
[0038] The load module 20 has a detection unit 25. The detection unit 25 is connected to the first wire 31 via an inductance 121 and to the second wire 32 via another inductance 121. The detection unit 25 monitors the first voltage U1 present between the first wire 31 and the second wire 32.
[0039] The detection unit 25 is further connected to the third wire 33 via an inductance 121 and to the fourth wire 34 via another inductance 121. The detection unit 25 monitors the second voltage U2 present between the third wire 33 and the fourth wire 34.
[0040] The detection unit 25 has a controllable switching unit 23. The switching unit 23 comprises a first transistor 41 and a second transistor 42. The transistors 41, 42 are embodied as normally-off transistors, in particular as bipolar transistors. Alternatively, field-effect transistors or relays, for example, are also conceivable.
[0041] A base of the first transistor 41 is connected to the first wire 31. An emitter of the first transistor 41 is connected to the second wire 32. A base of the second transistor 42 is connected to the third wire 33. An emitter of the second transistor 42 is connected to the fourth wire 34. If a voltage is applied between the base and emitter of a transistor 41, 42, the corresponding transistor 41, 42 is conductive. If no voltage is applied between the base and emitter of a transistor 41, 42, the corresponding transistor 41, 42 is blocking.
[0042] The transistors 41, 42 of the switching unit 23 are electrically connected in series and form a circuit with the control unit 27 and the supply voltage source 29. When the first transistor 41 and the second transistor 42 are conductive, the circuit is closed, and the supply voltage UV supplied by the supply voltage source 29 is applied to the control unit 27. When the first transistor 41 or the second transistor 42 is off, the circuit is open, and the supply voltage UV is not applied to the control unit 27.
[0043] When the first switch 11 of the feed module 10 is closed, the feed voltage UE supplied by the DC voltage source 105 is present as the first voltage U1 between the base and emitter of the first transistor 41. The first transistor 41 is thus conductive. When the first switch 11 of the feed module 10 is open, no voltage is present between the base and emitter of the first transistor 41. The first transistor 41 is thus blocking.
[0044] When the second switch 12 of the feed module 10 is closed, the feed voltage UE supplied by the DC voltage source 105 is present as a second voltage U2 between the base and emitter of the second transistor 42. The second transistor 42 is thus conductive. When the second switch 12 of the feed module 10 is open, no voltage is present between the base and emitter of the second transistor 42. The second transistor 42 is thus blocking.
[0045] A switch-off signal is sent to the first wire 31 and the second wire 32 by opening the first switch 11. The switch-off signal is detected by the detection unit 25 as a voltage drop in the first voltage U1 as soon as the first voltage U1 falls below a lower limit. The first transistor 41 then turns off. The switching unit 23 thus disconnects the control unit 27 from the supply voltage source 29 when the detection unit 25 detects the switch-off signal while monitoring the first voltage U1.
[0046] A switch-off signal is sent to the third wire 33 and the fourth wire 34 by opening the second switch 12. The switch-off signal is detected by the detection unit 25 as a voltage drop in the second voltage U2 as soon as the second voltage U2 falls below a lower limit. The second transistor 42 then turns off. The switching unit 23 thus disconnects the control unit 27 from the supply voltage source 29 when the detection unit 25 detects the switch-off signal while monitoring the second voltage U2.
[0047] List of reference symbols
[0048] 10 feed-in module
[0049] 11 first switch
[0050] 12 second switch
[0051] 20 consumer module
[0052] 23 Switching unit
[0053] 25 detection unit
[0054] 27 Control unit
[0055] 29 Supply voltage source
[0056] 30 data cables
[0057] 31 first vein
[0058] 32 second wire
[0059] 33 third vein
[0060] 34 fourth wire
[0061] 41 first transistor
[0062] 42 second transistor
[0063] 105 DC voltage source
[0064] 121 Inductance
[0065] 123 Data interface
[0066] 125 transformers
[0067] 127 Capacitor
[0068] UE feed-in voltage
[0069] U1 first voltage
[0070] U2 second voltage
[0071] UV supply voltage
Claims
Patent claims:
1. Bus system comprising a power supply module (10), a consumer module (20), and a data cable (30) connecting the power supply module (10) to the consumer module (20), wherein the data cable (30) has at least a first conductor (31), a second conductor (32), a third conductor (33), and a fourth conductor (34), and wherein the power supply module (10) has at least one DC voltage source (105) supplying a power supply voltage (UE), characterized in that the power supply module (10) has a first switch (11) by means of which the power supply voltage (UE) supplied by the DC voltage source (105) can be applied between the first conductor (31) and the second conductor (32), and that the consumer module (20) has a detection unit (25) which monitors a first voltage (U1) applied between the first conductor (31) and the second conductor (32), and that the consumer module (20) includes a control unit (27), in particular for controlling a drive,which can be supplied by a supply voltage source (29) that provides a supply voltage (UV), and that the detection unit (25) has a controllable switching unit (23) which disconnects the control unit (27) from the supply voltage source (29) when the detection unit (25) detects a switch-off signal while monitoring the first voltage (U1).
2. Bus system according to claim 1, characterized in that the power supply module (10) has a second switch (12) by means of which the power supply voltage (UE) supplied by the DC voltage source (105) can be applied between the third conductor (33) and the fourth conductor (34), and that the detection unit (25) monitors a second voltage (U2) applied between the third conductor (33) and the fourth conductor (34), and that the switching unit (23) disconnects the control unit (27) from the supply voltage source (29) when the detection unit (25) detects a switch-off signal while monitoring the second voltage (U2).
3. Bus system according to one of the preceding claims, characterized in that the detection unit (25) detects a switch-off signal when the first voltage (U1) falls below a lower limit and / or when the second voltage (U2) falls below a lower limit.
4. Bus system according to one of the preceding claims, characterized in that the power supply module (10) has a data interface (123) which is connected to the first via a transformer (125) and at least one capacitor (127). The first wire (31) and the second wire (32) are connected to send a differential data signal to the first wire (31) and the second wire (32), and which is connected via a transformer (125) and at least one capacitor (127) to the third wire (33) and the fourth wire (34) to receive a differential data signal from the third wire (33) and the fourth wire (34).
5. Bus system according to one of the preceding claims, characterized in that the consumer module (20) has a data interface (123) which is connected via a transformer (125) and at least one capacitor (127) to the first conductor (31) and the second conductor (32) in order to receive a differential data signal from the first conductor (31) and the second conductor (32), and which is connected via a transformer (125) and at least one capacitor (127) to the third conductor (33) and the fourth conductor (34) in order to send a differential data signal to the third conductor (33) and the fourth conductor (34).
6. Method for operating a bus system according to one of the preceding claims, characterized in that a switch-off signal is sent from the feed-in module (10) to the first conductor (31) and the second conductor (32) is sent; the first voltage (U1) applied between the first conductor (31) and the second conductor (32) is monitored by the detection unit (25); and the switching unit (23) is controlled in such a way that the control unit (27) is disconnected from the supply voltage source (29) when the switch-off signal is detected during the monitoring of the first voltage (U1).
7. Method according to claim 6, characterized in that the power supply module (10) has a second switch (12) by means of which the power supply voltage (UE) supplied by the DC voltage source (105) can be applied between the third conductor (33) and the fourth conductor (34), and that a switch-off signal is sent from the power supply module (10) to the third conductor (33) and the fourth conductor (34); the second voltage (U2) applied between the third conductor (33) and the fourth conductor (34) is monitored by the detection unit (25); and the switching unit (23) is controlled such that the control unit (27) is disconnected from the supply voltage source (29) when the switch-off signal is detected during the monitoring of the second voltage (U2).
8. Method according to one of claims 6 to 7, characterized in that a switch-off signal is sent to the first conductor (31) and the second conductor (32) by switching off the DC voltage source (105) from the first conductor by opening the first switch (11). (31) and / or is disconnected from the second conductor (32), and that a switch-off signal is detected by the detection unit (25) when the first voltage (U1) falls below a lower limit; and / or that a switch-off signal is sent to the third conductor (33) and the fourth conductor (34) by disconnecting the DC voltage source (105) from the third conductor by opening the second switch (12). (33) and is separated from the fourth wire (34), and that a switch-off signal is detected by the detection unit (25) when the second voltage (U2) falls below a lower limit.
9. Method according to any one of claims 6 to 8, characterized in that a switch-off signal is sent to the first conductor (31) and the second conductor (32) by coupling a signal with a defined signal frequency into the first conductor (31) and the second conductor (32), and that a switch-off signal is detected by the detection unit (25) when a signal with the signal frequency is detected in the first voltage (U1); and / or that a switch-off signal is sent to the third conductor (33) and the fourth conductor (34) by coupling a signal with a defined signal frequency into the third conductor (33) and the fourth conductor (34), and that a switch-off signal is detected by the detection unit (25) when a signal with the signal frequency is detected in the second voltage (U2); 10. Method according to one of claims 6 to 9, characterized in that a switch-off signal is sent to the first conductor (31) and the second conductor (32) by briefly disconnecting the DC voltage source (105) from the first conductor (31) and / or from the second conductor (32) by opening and closing the first switch (11), and that a switch-off signal is detected by the detection unit (25) when a brief interruption of the first voltage (U1) is detected; and / or that a switch-off signal is sent to the third wire (33) and the fourth wire (34) by briefly disconnecting the DC voltage source (105) from the third wire (33) and / or the fourth wire (34) by opening and closing the second switch (12), and that a switch-off signal is detected by the detection unit (25) when a brief interruption of the second voltage (U2) is detected.
11. Method according to one of claims 6 to 10, characterized in that the control unit (27) has an evaluation unit which monitors the first voltage (U1) applied between the first conductor (31) and the second conductor (32) and the second voltage (U2) applied between the third conductor (33) and the fourth conductor (34), and that the control unit (27) is disconnected from the supply voltage source (29) when the switch-off signal is detected during the monitoring of the first voltage (U1) and / or during the monitoring of the second voltage (U2).