DC-DC converter of the forward converter type for a switched-mode power supply of an actuator in automation technology, and actuator of said type

Abstract

The invention relates to a DC-DC converter for an actuator in automation technology with overload protection. According to the invention, electrical states of two circuit regions of the DC-DC converter are monitored and evaluated by means of a logic circuit.

Description

[0001] DC-DC converter of the flow converter type for a switched-mode power supply of an actuator in automation technology and such an actuator

[0002] The invention relates to a DC-DC converter for the power supply of an actuator used in automation technology. Such actuators are typically used to operate fittings in industrial plants, such as valves in pipelines. Actuators of this type are known, for example, from DE102019107721B4 and have an electronic operating circuit for actuating the motor. In the event of a fault, an overload can occur in a DC-DC converter supplying power to the electronic operating circuit or the motor, which can lead to the destruction of the power supply. Typically, DC-DC converters of the flow converter type are used in this power class of actuators, as these operate more efficiently than DC-DC converters based on the flyback converter principle.

[0003] The object of the invention is to propose a DC voltage converter for an actuator in which destruction in the event of overload can be avoided.

[0004] The problem is solved by a DC voltage converter according to the independent claim 1, and by an actuator according to the invention according to claim 16.

[0005] A DC-DC converter according to the invention is a DC-DC converter of the flow converter type and is suitable, and in particular configured, for a power supply of an actuator for automation technology and comprises: a first, in particular input-side, electronic circuit; a second, in particular output-side, electronic circuit; a transformer for the galvanically isolated transmission of electrical power from the first electronic circuit to the second electronic circuit; wherein the first electronic circuit comprises: a switching device with a switch for interrupting and closing a first electrical connection between a voltage input of the DC-DC converter and the transformer;a control circuit for clocked control of the switching device, wherein a duty cycle between pulse duration and pulse spacing of a switching signal is variable, wherein the control circuit has a minimum duty cycle of at least 1 / 10000 and in particular at least 2 / 10000 and preferably at least 5 / 10000, wherein the control circuit is configured to be supplied with electrical power by the transformer;A first state information circuit for detecting an electrical state of the first electronic circuit and for outputting a corresponding first state information signal, wherein the second electronic circuit comprises: a second state information circuit for detecting an electrical state of the second electronic circuit and for outputting a corresponding second state information signal, wherein the first electronic circuit has a monitoring circuit which is configured to detect an overload state of the DC-DC converter and to generate a shutdown signal in order to interrupt the power supply to the control circuit by means of the shutdown signal, wherein the first state information signal and the second state information signal are supplied to the monitoring circuit for the purpose of detecting the overload state.

[0006] The second status information signal can carry information about the level of a regulated output voltage. The output voltage level reacts to an output load.

[0007] The galvanic isolation between the first electronic circuit and the second electronic circuit by means of the transformer, or between an input side and an output side with respect to a power flow, means that an isolated DC-DC converter is present.

[0008] Commercially available control circuits used in typical and inventive DC-DC converters of the forward converter type are not capable of self-switching, but rather exhibit a minimum duty cycle of typically 1 / 1000, which can be applied to a switching signal. Therefore, in the event of a fault, despite the set minimum duty cycle, sufficient power may be transferred from the input side (the first electronic circuit) to the output side (the second electronic circuit), consequently causing the DC-DC converter to overheat.

[0009] To overcome this problem, the control circuit can be switched off by the inventive implementation of the DC-DC converter, so that no energy is transmitted through the transformer due to the lack of pulses. An overload situation must be distinguished, for example, from a switch-on situation, in which the first electronic circuit briefly experiences a higher load, while the second electronic circuit does not.

[0010] The DC-DC converter can be configured to convert an input AC voltage into a DC voltage.

[0011] The first state information signal and the second state information signal are each carried by electrical quantities such as a current, a voltage, a capacitance, or an inductance.

[0012] In one embodiment, the shutdown signal is configured to interrupt the power supply to the control circuit, with the shutdown signal being fed into a supply circuit for powering the control circuit. In this way, the actuation of the switching device can be interrupted.

[0013] In one embodiment, the first state information circuit is configured to detect a current along the electrical connection and generate corresponding signal values ​​of the first state information signal. For example, high current values ​​are an indicator of a high load.

[0014] A high load condition can be detected by exceeding a limit value for the electric current.

[0015] In one design, the first

[0016] State information signal supplied to the monitoring circuit, or wherein the first state information signal is supplied to the control circuit, which control circuit is configured to adjust the duty cycle based on the first state information signal, wherein the monitoring circuit is configured to use the duty cycle to detect the overload condition.

[0017] In one embodiment, the second state information circuit is configured to detect an output voltage of the second electronic circuit and to generate corresponding signal values ​​of the second state information signal, wherein in particular the second state information signal is supplied to the control circuit and / or an input of the monitoring circuit.

[0018] A high load condition can be detected by the output voltage falling below a certain threshold. As the load increases, the output voltage of the DC-DC converter tends to decrease.

[0019] In one embodiment, the first electronic circuit includes a restart circuit, wherein the restart circuit is configured to restart the control circuit after it has been switched off, with a time delay being provided between restart and switching off.

[0020] This avoids the need to manually restart the DC-DC converter, whereby, for example, sufficient time can be provided for the cooling of electronic components by setting a time delay, which can enter a critical temperature range in an overload situation.

[0021] In one embodiment, the time delay lasts at least 0.1 seconds, in particular at least 0.5 seconds and preferably at least 1 second and / or at most 200 seconds, in particular at most 100 seconds and preferably at most 50 seconds, and / or wherein the time delay is adjustable.

[0022] In one embodiment, the restart circuit includes an energy storage device designed to temporarily supply power to the control circuit after the time delay has elapsed. The energy storage device must be sufficiently sized to allow the control circuit to perform several switching operations. Typically, after approximately 10 switching operations, the power supply to the control circuit is ensured via the transformer. The energy storage device can be charged via the voltage input. For example, the time delay can be controlled by an adjustable charging rate.

[0023] In one embodiment, the second status information signal is supplied to the monitoring circuit and / or the control circuit via galvanic isolation between the first and second electronic circuits, for example by means of an optocoupler. The control circuit can also use the second status information to set a duty cycle. The second status information can

[0024] In this way, the first electronic circuit and the second electronic circuit can remain galvanically isolated from each other.

[0025] In one embodiment, the first status information signal is transmitted to the control circuit, the control circuit being configured to reduce power transfer to the second electronic circuit by adjusting the duty cycle in case of overload of the first electronic circuit.

[0026] In one embodiment, the monitoring circuit comprises a logic circuit such as a flip-flop and a duty cycle detection circuit, wherein the logic circuit is supplied with the first state information by means of a duty cycle signal from the duty cycle detection circuit and the second state information, wherein the logic circuit is configured to generate and output the shutdown signal.

[0027] By setting up the logic circuit, an overload condition of the DC voltage converter can be detected by querying the electrical states of the first electronic circuit and the second electronic circuit.

[0028] In one embodiment, the logic circuit has a low-active D flip-flop, wherein the duty cycle signal is fed to a data input of the D flip-flop, wherein the second state information signal is fed to a reset input of the D flip-flop, and wherein a clock signal of the control circuit is fed to a clock input of the D flip-flop.

[0029] In one embodiment, the transformer includes a transformer. The pulses of the switching signal cause a power transfer from the first electronic circuit to the second electronic circuit.

[0030] In one embodiment, the supply circuit is configured to draw energy from the transformer by means of a coil assembly comprising a coil. By switching off the power supply to the control circuit via the supply circuit, the power transmission via the transformer is stopped due to the absence of pulses from the switching signal, thus ending an overload situation.

[0031] In one embodiment, the second electronic circuit comprises a voltage rectifier, wherein the second state information circuit is configured to detect a rectified output voltage.

[0032] In this way, a robust and precise second state information signal can be created.

[0033] An actuator according to the invention for automation technology for actuating a fitting such as a valve comprises: a drive with a motor such as an electric motor or a fluid motor; a gearbox; an output for actuating the fitting, wherein the gearbox is configured to transmit a force or torque to the output, wherein the actuator has an electronic operating circuit which is configured to operate the drive, wherein the motor, output, gearbox and electronic operating circuit are arranged in particular in a housing arrangement with at least one housing, wherein the actuator has a switched-mode power supply with a DC-DC converter according to the invention.

[0034] The DC-DC converter is designed, for example, to shut down in the event of an overload caused by a fault in the drive or the electronic operating circuit. The DC-DC converter can be part of the electronic operating circuit or a separate component.

[0035] The invention is described below using exemplary examples.

[0036] Fig. 1 describes an exemplary DC voltage converter according to the invention;

[0037] Fig. 2 describes an exemplary actuator according to the invention;

[0038] Fig. 1 shows a sketch of an exemplary DC-DC converter 1 according to the invention, of the forward converter type, with a voltage input 18 and a voltage output 23. A first electronic circuit 10 is configured to transmit the input voltage of the voltage input 18 to the transformer 30 via the electrical connection 12 in a clocked manner by means of the switching device 11. The transformer is configured to transfer the electrical power transmitted to the transformer with the clock signals to a second electronic circuit 20. The transformer can, for example, comprise a transformer 31. The clocked input voltage is thereby inductively transferred from the input side to the output side of the DC-DC converter. The switching device comprises a switch 11, which is, for example, designed by a transistor or a transistor circuit.

[0039] For the purpose of pulsed actuation of the switching device, the DC-DC converter has a control circuit 13, which is configured to pulse the switching device 11, thereby opening and closing the switch to transmit electrical power to the transformer. The duty cycle between the pulse duration and pulse spacing of a switching signal is variable, with the control circuit 13 having a minimum duty cycle of at least 1 / 10000, and in particular at least 2 / 10000, and preferably at least 5 / 10000. During operation, a duty cycle of 1 can be set for maximum power transmission.

[0040] To prevent damage to the DC-DC converter in the event of an overload, the control circuit is designed to be switchable according to the invention. For example, as shown here, this can be achieved by transmitting a switch-off signal to a supply circuit 16 for the power supply of the control circuit 13 in the event of an overload of the DC-DC converter, thereby interrupting the power supply to the control circuit. Preferably, the switch is held in an open state. This stops the electrical power transfer from the first electronic circuit 10 to the transformer 30. As shown here, the supply circuit can include a coil device 16.1 with a coil 16.11 to tap off a portion of the power transmitted from the voltage input 18 to the transformer 30 and supply it to the control circuit 13.

[0041] According to the invention, a first state information circuit 14 and a second state information circuit 21 are provided to detect an overload situation. The first state information circuit is configured to detect the electrical state of the first electronic circuit and provide a corresponding first state information signal. The second state information circuit is configured to detect the electrical state of the second electronic circuit and provide a corresponding second state information signal. The first state information and the second state information are fed to a monitoring circuit 15, which is configured to detect an overload state of the DC-DC converter 1 and generate a shutdown signal to interrupt the power supply to the control circuit 13.

[0042] As shown here, the monitoring circuit can comprise a logic circuit 15.1, for example, with a particularly active-low D flip-flop. The D flip-flop has a data input D, a reset input R, and a clock input T. The switching signal from the control circuit is fed to the clock input, an average value of the switching signal is fed to the data input, and the second state monitoring signal is fed to the reset input. In the embodiment shown here, the first state monitoring signal is fed to the monitoring circuit indirectly via the control circuit 13, which sets a duty cycle of the switching signal depending on an electrical state of the first electronic circuit transmitted by the first state information signal. The control circuit can also use the second state information signal 21.1 to set the duty cycle, as shown here.By averaging the switching signal, and thus the duty cycle, and supplying the data input, the first status information reaches the logic circuit 15.1. This can be accomplished via a duty cycle detection circuit 15.2. For example, the duty cycle detection circuit can include an RC circuit for this purpose. Alternatively, the first status information signal can also be supplied to the monitoring circuit 15 directly, without going through the control circuit 13.

[0043] The first and second status information signals are transmitted by electrical quantities such as voltage or current, whereby different signal levels or different slopes of the electrical quantities carry different information. For example, a high load on the first electronic circuit 10 or the second electronic circuit 20 can be detected by exceeding or falling below a threshold value of the signal level, i.e., a threshold value for voltage or current.

[0044] In one version, the first

[0045] The status information circuit is set up to detect a current along the electrical connection and generate corresponding signal values ​​or signal levels of the first status information signal. For example, high current values ​​are an indicator of a high load.

[0046] In one embodiment, the second state information circuit is configured to detect an output voltage of the second electronic circuit and to generate corresponding signal values ​​or signal levels of the second state information signal. The output voltage can, for example, be tapped after a rectifier 22 in order to detect more robust and precise output voltage values.

[0047] As shown here, the second status information signal can be transmitted from the second electronic circuit to the first electronic circuit via a galvanic isolation 40, for example, comprising an optocoupler. The optocoupler converts the second status information signal from an electrical voltage into an electrical current, which, as shown here, is transformed back into a corresponding voltage via a current-to-voltage converter 19 and fed to the reset input R.

[0048] At high output voltage, in the illustrated configuration, the reset input R of the D flip-flop is supplied with a high signal, thus rendering the signals present at the clock input T and data input D ineffective. In this way, no shutdown signal is output to the supply circuit 16 when the output load or load of the second electronic circuit is low and the output voltage is correspondingly high. At low output voltage and correspondingly high load of the second electronic circuit 20, the reset input R is inactive, so that if a high load is also present at the first electronic circuit, a shutdown signal is output and sent to the

[0049] The data can be transmitted to the supply circuit 16. In the embodiment shown here, this occurs when a low signal is present at the data input. This corresponds to a small duty cycle in the range of the minimum duty cycle of the supply circuit.

[0050] The logic circuit configuration shown here is exemplary. A person skilled in the art can, for example, select equivalent logic circuits from circuit tables and implement them in accordance with the invention by appropriate wiring.

[0051] For example, the reset input can receive a permanent low signal, and the second state information signal 21.1 can be fed exclusively to the control circuit. By mixing the first state information signal and the second state information signal in the duty cycle, information relevant for detecting an overload condition can be supplied to the monitoring circuit 15 via the duty cycle detection circuit.

[0052] For example, the second state information signal can be supplied to the reset input R, and the first state information signal to the control circuit 13, so that the duty cycle is set by the first state information without the second state information.

[0053] In one embodiment, the DC-DC converter has a restart circuit 17, which is configured to restart the control circuit 13 after it has been switched off, with a time delay between the restart and the switch-off. This avoids the need to manually restart the DC-DC converter, and the time delay allows sufficient time for electronic components to cool down, which could otherwise reach critical temperatures in an overload situation.

[0054] In one embodiment, the time delay lasts at least 0.1 seconds, in particular at least 0.5 seconds and preferably at least 1 second and / or at most 200 seconds, in particular at most 100 seconds and preferably at most 50 seconds, and / or wherein the time delay is adjustable.

[0055] In one embodiment, the restart circuit includes an energy storage device designed to temporarily supply power to the control circuit after the time delay has elapsed. The energy storage device must be sufficiently sized to allow the control circuit to perform several switching operations. Typically, after approximately 10 switching operations, the power supply to the control circuit is ensured via the transformer. The energy storage device can be charged via the voltage input. For example, the time delay can be controlled by an adjustable charging rate.

[0056] The DC / DC converter can be used in a switching power supply 50 of an actuator 100.

[0057] Fig. 2 shows an exemplary embodiment according to the invention.

[0058] Actuator 100 comprising a housing arrangement 150 with at least one housing 151, here by way of example two housings 151, wherein the drive 110, the gearbox 120, the output 130, the electronic operating circuit 140 and the switched-mode power supply 50 with a DC-DC converter 1 according to the invention are arranged in the housing arrangement. For explosion protection reasons, for example, the switched-mode power supply and the electronic operating circuit can be arranged in a separate housing 151. The gearbox is configured to transmit a force or torque from the drive to the output. The drive can be an electric motor or a fluid motor. By means of the torque or force transmitted to the output, an actuator of a fitting, such as a valve, can be actuated to open, close, or move it.

[0059] Reference symbol list

[0060] I DC-DC converter

[0061] 10 first electronic circuit

[0062] II Switching device

[0063] 11.1 Switch

[0064] 13 expensive circuit

[0065] 14 first state information circuit

[0066] 14.1 First state information signal

[0067] 15 Monitoring circuit

[0068] 15.1 Logic circuit

[0069] 15.11 low-active D flip-flop

[0070] D Data input

[0071] R Reset input

[0072] T clock input

[0073] 15.2 Duty cycle detection circuit

[0074] 16 Power supply circuit

[0075] 16. I Coil device

[0076] 16. II coil

[0077] 17 Restart circuit

[0078] 17.1 Energy storage

[0079] 18 voltage inputs

[0080] 19 Current-to-Voltage Converters

[0081] 20 second electronic circuit

[0082] 21 second status information circuit

[0083] 21.1 Second status information signal

[0084] 22 voltage rectifier

[0085] 23 Voltage output

[0086] 30 transformers

[0087] 31 Transformer

[0088] 40 galvanic isolation

[0089] 41 Optocouplers

[0090] 50 Scha It net z part

[0091] 100 actuators for automation technology

[0092] 110 Drive 111 Motor

[0093] 120 gearbox

[0094] 130 downforce

[0095] 140 electronic operating circuit 150 housing arrangement

[0096] 151 cases

Claims

Claims 1. DC-DC converter (1) of the forward converter type, suitable and in particular configured for a switching power supply of an actuator (100) for automation technology, comprising: a first Electronic circuit (10); a second electronic circuit (20); a transformer (30) for galvanically isolated transmission of electrical power from the first electronic circuit (10) to the second electronic circuit (20); wherein the first electronic circuit comprises: a switching device (11) with a switch (11.1) for interrupting and closing an electrical connection between a voltage input (18) of the DC-DC converter and the transformer (30); a control circuit (13) for clocked control of the switching device, wherein a duty cycle between pulse duration and pulse spacing of a switching signal is variable, wherein the control circuit (13) has a minimum duty cycle of at least 1 / 10000 and in particular at least 2 / 10000 and preferably at least 5 / 10000, wherein the control circuit is configured to be supplied with electrical power by the transformer (30); a first state information circuit (14) for detecting an electrical state of the first electronic circuit (10) and for outputting a corresponding first state information signal (14.1), wherein the second electronic circuit (20) comprises: a second state information circuit (21) for. Detection of an electrical state of the second electronic circuit and for outputting a corresponding second status information signal (21.1) , characterized in that the first electronic circuit (10) has a monitoring circuit (15) which is configured to detect an overload condition of the DC-DC converter (1) and to generate a shutdown signal in order to interrupt the power supply of the control circuit (13) by means of the shutdown signal, wherein the monitoring circuit (15) receives the first status information signal and the second for the purpose of detecting the overload condition A status information signal is supplied.

2. DC-DC converter according to claim 1, wherein the Shutdown signal of a supply circuit (16) for Energy is supplied to the control circuit.

3. DC-DC converter according to one of the preceding claims, wherein the first state information circuit (14) is configured to detect a current along the electrical connection and to generate corresponding signal values ​​of the first state information signal (14.1).

4. DC-DC converter according to claim 3, wherein the first state information signal (14.1) of the monitoring circuit (15), and / or wherein the first status information signal (14.1) is supplied to the control circuit (13), which control circuit (13) is configured to determine the duty cycle based on the first to set the status information signal, whereby the The monitoring circuit (15) is set up to use the duty cycle to detect the overload condition. DC voltage converter according to one of the preceding claims, wherein the second state information circuit (21) is configured to detect an output voltage of the second electronic circuit (20) and to generate corresponding signal values ​​of the second state information signal (21.1), wherein in particular the second state information signal is supplied to the control circuit and / or an input of the monitoring circuit.

6. DC-DC converter according to one of the preceding claims, wherein the first electronic circuit (10) comprises a restart circuit (17), wherein the restart circuit is configured to restart the control circuit (13) after it has been switched off, wherein a time delay is provided between restart and switch-off.

7. DC-DC converter according to claim 6, wherein the time delay is at least 0.1 seconds, in particular at least 0.5 seconds and preferably at least 1 second and / or at most 200 seconds, in particular at most 100 seconds and preferably at most 50 seconds, and / or wherein the time delay is adjustable.

8. DC-DC converter according to claim 6 or 7, wherein the restart circuit (17) comprises an energy storage device (17.1) which is configured to temporarily supply the control circuit with energy after the time delay has elapsed.

9. DC-DC converter according to one of the preceding claims, wherein the second status information signal (21.1) of the first electronic circuit (10) is transmitted via a galvanic isolation (40) between the first electronic circuit (10) and the second electronic circuit (20), for example by means of is supplied to an optocoupler (41).

10. DC-DC converter according to one of the preceding claims, wherein the first status information signal (14.1) is transmitted to the control circuit (13), wherein the control circuit is configured to reduce power transfer to the second electronic circuit (20) in the event of overload of the first electronic circuit by adjusting the duty cycle and / or to regulate down a voltage drop across the transformer accordingly.

11. DC-DC converter according to one of the preceding claims, wherein the monitoring circuit (15) comprises a logic circuit (15.1) such as a flip-flop, and a duty cycle detection circuit (15.2), wherein the logic circuit receives the first state information by means of a duty cycle signal of the The duty cycle detection circuit and the second state information are supplied, wherein the logic circuit (15.1) is configured to generate and output the shutdown signal.

12. DC-DC converter according to claim 11, wherein the logic circuit (15.1) comprises a low-active D flip-flop (15.11), wherein the duty cycle signal is supplied to a data input (D) of the D flip-flop, wherein the second state information signal (21.1) is supplied to a reset input (R) of the D flip-flop, and wherein a clock signal of the control circuit (13) is supplied to a clock input (T) of the D flip-flop.

13. DC voltage converter according to one of the preceding claims, wherein the transformer (30) comprises a transformer (31).

14. DC-DC converter according to claim 13 in conjunction with claim 2, wherein the supply circuit (16) is configured to extract energy from the transformer by means of a coil device (16.1) comprising at least one coil (16.11).

15. DC-DC converter according to one of the preceding claims, wherein the second electronic circuit (20) comprises a voltage rectifier (22), wherein the second state information circuit (21) is configured to detect a rectified output voltage.

16. Actuator (100) of automation technology for Actuating a fitting such as a valve, comprising: an actuator (110) with a motor (111) such as an electric motor or a fluid motor; a gearbox (120); an output (130) for actuating the fitting, wherein the gearbox is configured to transmit a force or torque to the output, wherein the actuator has an electronic operating circuit (140) configured to operate the actuator, wherein the motor, output, gearbox and electronic operating circuit are arranged in particular in a housing arrangement (150) with at least one housing (151), characterized in that the actuator (140) has a switched-mode power supply (50) with a DC-DC converter (1) according to one of the preceding claims for power supply.

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