Device for monitoring power supply

Abstract

According to one aspect, the invention relates to a device (20) for monitoring a safe low-voltage power supply (10), comprising: a first monitoring element (110), which is designed to monitor a first current (I1) and a first voltage (U1), which are output on the secondary side by a voltage converter (100); a primary-side control element (105), which is connected to the first monitoring element (110) in a signal-conducting manner and is designed to control the voltage converter (100) on the primary side on the basis of a first current (I1) and a first voltage (U1) when a first threshold value is exceeded; and a second monitoring element (120) which is designed to monitor the second current (I2) and the second voltage (U2), the second current (I2) and the second voltage (U2) being based on the first current (I1) and the first voltage (U1), the second monitoring element (120) being supplied by the first monitoring element (110) with the first current (I1) and the first voltage (U1), and the second monitoring element (120) being designed to monitor the second current (I2) and the second voltage (U2) being based on the first current (I1) and the first voltage (U1). The primary-side control element (105) is connected to the second monitoring element (120) in a signal-conducting manner and is designed to control the voltage converter (100) on the primary side on the basis of a second current (I2) and a second voltage (U2) when a second threshold value is exceeded.

Description

Technical Field

[0001] The present invention relates to a technology for monitoring power supplies. Without being limited thereto, the present invention particularly relates to a device for monitoring a safety low-voltage power supply, wherein the extractable power is increased relative to the maximum possible output power. For this purpose, the regulation or limitation of voltage and current is realized redundantly in the case of two limiters arranged in series. Background Art

[0002] In the power supply for safety low voltage, also known as SELV (Safety Extra Low Voltage) in the profession, a direct current voltage (DC, direct current) of up to 60 volts is provided. For example, when a 12 volt or 24 volt direct current voltage is provided, in order to improve safety, the output power is limited to permanently less than 100 watts according to UL 1310 (Underwriters Laboratories, USA). In addition, corresponding limiting mechanisms such as voltage limitation, current limitation and power limitation must be simple error-proof (einfach-fehlersicher) redundantly and therefore implemented in a dual manner. The requirements for the increase of overvoltage and overcurrent are also applicable to this safety-oriented system. Considering this, the highest voltage in the power supply system determines the system voltage of the power supply, and the components only work safely to the maximum voltage limit. When the current limit is exceeded, the failed electrical appliances connected to the system may cause a fault.

[0003] This redundant power limitation is realized by small power supplies known in the prior art whose power throughput is significantly less than 100 Watt. In this case, the first power limitation is formed by the natural power limitation of the power supply, which results from the maximum power limitation of the transformer. The second current limitation is formed by the current limitation that is usually installed, for example in the form of a current protection device, for example as a fuse. Both mechanisms limit the maximum power to a certain upper limit in a simple and fail-safe manner.

[0004] However, due to the significant inaccuracy of the limitation, this requires a significant distance from the maximum possible output power. Likewise, downstream fuses at the output of the power supply require a significant safety distance, since these fuses allow for a certain period of time a significantly higher current than the rated value of the fuse, which is also highly dependent on the ambient temperature. Overall, these methods generally allow limiting to a maximum of 2 / 3 of the possible output power. Summary of the invention

[0005] Therefore, the object of the present invention is to provide a technology so that in a safety low-voltage power supply, the distance between the system power and the maximum possible output power can be reduced while complying with the required safety conditions. The maximum load of the power supply can be increased thereby, which also reduces the power supply cost.

[0006] This object is achieved by the features of the independent claim. Advantageous embodiments and advantageous developments of the invention are given in the dependent claims.

[0007] Embodiments of the invention which can be optionally combined with one another are disclosed below, partly with reference to the drawings.

[0008] The first aspect relates to a device for monitoring a safety low-voltage power supply. The device includes a first monitoring element. The first monitoring element is configured to monitor a first current I1 and a first voltage U1 output by a voltage converter on the secondary side. The device also includes a primary-side control element, which is connected to the first monitoring element in a signal-conducting manner and is configured to control the voltage converter on the primary side based on the first current I1 and the first voltage U1. The control starts working at least when a first threshold value is exceeded. In addition, the device includes a second monitoring element, which is configured to monitor a second current I2 and a second voltage U2. Here, the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1. In addition, the first monitoring element supplies the first current I1 and the first voltage U1 to the second monitoring element. The control element on the primary side is connected to the second monitoring element in a signal-conducting manner and is configured to control the voltage converter on the primary side based on the second current I2 and the second voltage U2 when the second threshold value is exceeded.

[0009] Advantageously, embodiments can make it possible to allow for simple fail-safe voltage and current limits or voltage and power limits or current and power limits to be regulated by means of a double feedback to the primary side of the power supply, and thus improve regulation on the primary side. In particular, compliance with the required limit values ​​can be better achieved by means of such regulation on the primary side, or a complete disconnection of the power supply can be achieved, for example, if regulation is not successful or is not successful in other ways (e.g. by limiting current, voltage or power, or by selectively disconnecting individual output units, i.e. output channels).

[0010] Preferably, the first threshold value may include a first upper current limit I1', and a first upper voltage limit U1', or a first upper power limit P1'. Here, exceeding the first threshold value may be achieved solely by exceeding the first upper current limit I1'. Supplementarily or alternatively, exceeding the first threshold value may be achieved solely by exceeding the first upper voltage limit U1'. Further supplementarily or alternatively, exceeding the first threshold value may be achieved solely by exceeding the first upper power limit P1'.

[0011] Alternatively or supplementally, the second threshold value may include a second upper current limit I2' and a second upper voltage limit U2', or a second upper power limit P2'. Here, exceeding the second threshold value may be achieved solely by exceeding the second upper current limit I2'. Additionally or alternatively, exceeding the second threshold value may be achieved solely by exceeding the second upper voltage limit U2'. Further additionally or alternatively, exceeding the second threshold value may be achieved solely by exceeding the second upper power limit P2'.

[0012] Here, the first upper current limit I1' may be equal to or greater than the second upper current limit I2'. Alternatively or supplementally, the first upper voltage limit U1' may be equal to or greater than the second upper voltage limit U2'. Alternatively or supplementally, the first upper power limit P1' may be equal to or greater than the second upper power limit P2'.

[0013] Advantageously, multiple upper limit violations can thus be introduced into the control of the voltage converter, which can monitor the current, voltage and their product - power. It is further advantageous that, by increasing the current, voltage and power values ​​relative to the second monitoring element, further output units can be connected to the first monitoring element by monitoring in parallel with the output unit with the second monitoring.

[0014] The device for monitoring the power supply may include a first output unit. The first output unit may provide a second current I2 and a second voltage U2 at a first power supply output. The power supply output of the output unit may be the same as the power supply output of the power supply. The power supply output may be used to power electrical appliances such as sensors or the like, which implement monitoring functions. In order to operate the electrical appliances reliably, it is necessary not to exceed a maximum current, a maximum voltage and / or a maximum power. The first output unit may include a second monitoring element.

[0015] Advantageously, the current provided at the output of the power supply, the voltage provided and the power provided can thus be introduced into the regulation together. It is further advantageous that the component design can be simplified or a modular structure can be achieved by making the combination of output unit and monitoring element configurable as a replaceable and / or supplementable component.

[0016] In addition, the first output unit may include a first switch for disconnecting the first power supply output terminal. The switch may be controlled by a second monitoring element. Here, the second monitoring element may monitor a second threshold value. This may include monitoring a second upper current limit I2, a second upper voltage limit U2 and / or a second upper power limit P2. However, alternatively, the upper limits of the current I1', the voltage U1' and the power P1' based on the second upper current limit I2, the second upper voltage limit U2 and / or the second upper power limit P2 may also be monitored.

[0017] Advantageously, an overload state, for example in the form of a first threshold value being exceeded with a lower upper limit, can thereby be locally stopped in the first output unit.

[0018] In addition, a second output unit providing a third current I3 and a third voltage U3 at a second power supply output terminal can be arranged in the power supply monitoring device and conductively connected. Here, the second output unit can be supplied with the first current I1 and the first voltage U1 by the first monitoring element. The second output unit can be arranged in parallel with the first output unit and / or connected in parallel with respect to the first voltage U1. Here, the second output unit can differ from the first output unit in terms of the type and range of monitoring and in terms of the upper limit value of the monitored current, voltage and / or power.

[0019] Thus, advantageously, a plurality of currents I2, I3, voltages U2, U3 and powers P2, P3 can be monitored, wherein the currents and voltages can differ from one another. Furthermore, advantageously, different monitoring mechanisms can be used due to different configurations of the output unit.

[0020] In addition, in the power supply monitoring device, the second output unit may include a second switch for disconnecting the second power supply output terminal. Here, the second output unit may monitor a third threshold value. The third threshold value may include monitoring of a third upper current limit I3, a third upper voltage limit U3, and / or a third upper power limit P3. However, alternatively, it is also possible to monitor the upper limits of the current I3', the voltage U3', and the power P3' based on the third upper current limit I3, the third upper voltage limit U3, and / or the third upper power limit P3.

[0021] Advantageously, an overload state in the form of a first threshold value being exceeded can thereby be locally stopped in the second output unit. Further advantageously, the second output unit can be designed more cost-effectively without reporting to a primary-side control element.

[0022] Furthermore, in the device, the first switch may be switched according to an excess of a second threshold. The second switch may be switched according to an excess of a third threshold. Alternatively or additionally, the reporting of the second threshold may be based on a failure of the first switch. Alternatively or additionally, optionally, the reporting of the third threshold may be based on a failure of the second switch.

[0023] Advantageously, it is thus possible to achieve different switch actuations and thus a corresponding disconnection of the power supply depending on the exceeding of a corresponding threshold value.

[0024] Furthermore, the separation of the second switch may be based on an internal signal of the second output unit.Alternatively or additionally, the separation of the first switch may be based on an internal signal of the first output unit.

[0025] Optionally, an overrun of the first threshold value can also be reported to the control element of the primary side while the first switch is disconnected. Furthermore, a failure of the first switch can optionally be reported to the control element of the primary side. This can include reporting when the switch fails to open. The reporting option to be activated can be preset in the device.

[0026] Furthermore, optionally, no reporting to the control element on the primary side may occur when the third threshold value is exceeded. Alternatively, the exceeding of the third threshold value may also be reported to the control element on the primary side while the second switch is disconnected. Furthermore, optionally, a failure of the second switch may be reported to the control element on the primary side. This may include reporting when the switch fails to open. The reporting option to be activated may be preset in the device.

[0027] Advantageously, a response to a violation of a threshold value or to a fault in an output unit can thereby be effected flexibly (eg selectively for individual output units) and / or in a predefined manner not only locally in the output unit but also in conjunction with the primary side.

[0028] Furthermore, the device may include a switching element arranged on the primary side, which is arranged between the control element on the primary side and the voltage converter and is conductively connected thereto. The switching element arranged on the primary side can control the voltage converter on the primary side based on a signal of the control element on the primary side. The control affects the first current I1 and the first voltage U1. Alternatively, the control causes the disconnection of the first current I1 and the disconnection of the first voltage U1.

[0029] Advantageously, a central control of the voltage converter is thus possible.

[0030] In each of the variants described herein, the connection of the control element conduction signal on the primary side in the device for monitoring the power supply can include an inductive and / or capacitive and / or optical coupling element. Optionally, the connection of the conduction signal with the first monitoring element can include a first coupling element, and the connection of the conduction signal with the second monitoring element can include a second coupling element (which is different from the first coupling element). Here, the first coupling element can also include a connection with the conduction signal of the second output unit. The coupling elements can be arranged in parallel. Here, the coupling elements can use the same or different technologies (inductive, capacitive, optical). In addition, alternatively, each connection of the conduction signal can include its own coupling element, wherein the coupling elements can optionally be arranged in parallel with each other. The coupling element can electrically isolate the secondary side from the primary side of the power supply.

[0031] Advantageously, therefore, fault redundancy in the threshold value monitoring can be increased with simultaneous galvanic isolation of the secondary side and the primary side of the power supply.

[0032] In addition, the monitoring element of the device for monitoring the power supply can be configured to monitor the threshold value being exceeded and the duration of the threshold value being exceeded. The report of the threshold value exceeding can be performed only after the predetermined duration has expired. Here, the value of the threshold value exceeding can be a multiple of the threshold value, for example, 2 to 10 times the threshold value. In addition, the duration of the threshold value exceeding can be 2 to 5 seconds. The threshold value exceeding and the duration of the threshold value exceeding can be preset in the device.

[0033] Advantageously, the monitoring can thus be adapted individually to the electrical load to be connected and can, for example, also include the operation and in particular the starting of a motor.

[0034] Furthermore, in the device for monitoring the power supply, the threshold value can be set by the user. Here, the setting can also be made by a remote (e.g. spatially or network topologically separated) station and received via the interface. Alternatively or additionally, the setting of the threshold value can each include a settable duration of a permissible threshold value violation.

[0035] Advantageously, an effective adaptation to the respectively connected electrical load can thus be achieved.

[0036] Furthermore, the power supply for safety low voltage can include a device for monitoring the power supply. Here, the power supply can comply with the low voltage requirements SELV. Furthermore, it can also comply with UL 1310 regulations.

[0037] Advantageously, a simpler wiring of the connected loads (eg with a smaller conductor cross section) can therefore be used. In addition, advantageously, the connection of the loads can also be carried out by less trained personnel.

[0038] Furthermore, the voltage converter of the power supply may include a transformer or a switching power supply or a hard-switching flow converter (Flusswandler) or a locking converter or a resonant switching converter.

[0039] Advantageously, different requirements on the power supply can thus be met with regard to costs, current, voltage and power stability and / or installation space.

[0040] A second aspect relates to a method for monitoring a power supply of a safety low voltage. The method includes monitoring a first current I1 and a first voltage U1 using a first monitoring element, which are output by a voltage converter on the secondary side. In addition, the method includes controlling the voltage converter on the primary side based on the first current I1 and the first voltage U1 by a control element on the primary side when a first threshold is exceeded, and the control element is connected to the first monitoring element in a signal-conducting manner. The method also includes monitoring a second current I2 and a second voltage U2 using a second monitoring element, wherein the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1. The second monitoring element is supplied with the first current I1 and the first voltage U1 by the first monitoring element. In addition, the method includes controlling the voltage converter on the primary side based on the second current I2 and the second voltage U2 if a second threshold is exceeded, wherein the primary side control element is connected to the second monitoring element in a signal-conducting manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be described in detail below with reference to the accompanying drawings based on preferred embodiments, which can be selectively combined with each other.

[0042] Figure 1 shows a schematic block diagram of a power supply having a device for monitoring a power supply according to a first embodiment,

[0043] Figure 2 shows a power supply with a device for monitoring a power supply according to a second embodiment,

[0044] Figure 3 A power supply having a device for monitoring a power supply according to a third embodiment is shown, which has a first monitoring element, a second monitoring element and a second output unit.

[0045] Figure 4 A power supply having a device for monitoring a power supply according to a fourth embodiment is shown, which has a first output unit and a second output unit, and

[0046] Figure 5 A method for monitoring a safety low voltage power supply is shown. DETAILED DESCRIPTION

[0047] Figure 1 A schematic block diagram of a power supply 10 with a device 20 for monitoring the power supply 10 is shown. The device 20 is used to monitor the power supply 10 for safety low voltage. The power supply 10 comprises input terminals, to which a common supply voltage of 230 volts or 120 volts AC is applied. In addition, the power supply comprises at least one pair of output terminals, to which an output voltage U2 is applied and an output current I2 is provided.

[0048] The device 20 comprises a first monitoring element 110, which is designed to monitor a first current I1 and a first voltage U1, which are outputted by the voltage converter 100 on the secondary side. For this purpose, the device 20 is electrically conductively connected to the voltage converter 100. In addition, the device 20 comprises a primary-side control element 105, which is signal-conductingly connected to the first monitoring element 110 and is designed to control the voltage converter 100 on the primary side based on the first current I1 and the first voltage U1 when a first threshold value is exceeded. For this purpose, a signal S(I1) corresponding to the first current and a signal S(U1) corresponding to the first voltage are generated in the first monitoring element 110 and provided to the primary-side control element 105. In addition, the device 20 comprises a second monitoring element 120, which is designed to monitor a second current I2 and a second voltage U2, wherein the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1. The second monitoring element 120 is supplied with the first current I1 and the first voltage U1 by the first monitoring element 110. Furthermore, the primary-side control element 105 is connected to the second monitoring element 120 in a signal-conducting manner and is configured to control the voltage converter 100 on the primary side based on the second current I2 and the second voltage U2 when a second threshold value is exceeded. For this purpose, a signal S(I2) corresponding to the second current and a signal S(U2) corresponding to the second voltage are generated in the second monitoring element 120 and provided to the primary-side control element 105. Accordingly, the first monitoring element 110 and the second monitoring element 120 are arranged on the secondary side of the power supply, while the primary-side control element 105 is arranged on the primary side, as already apparent from the concept.

[0049] The SELV power supply 10 is designed for safety low voltage according to UL 1310 (Class II power unit). The voltage converter 100 of the power supply 10 is electrically isolated or alternatively non-electrically isolated. The voltage converter 100 is a transformer or a switching power supply or a hard-switching flow converter or a lock-in converter or a resonant switching converter designed as LLC, for example. LLC converters (two inductors, one capacitor) are resonant converters with three reactive elements.

[0050] The first threshold value includes a plurality of measurement variables, including a first upper current limit I1' and a first upper voltage limit U1' or a first upper power limit P1'. Accordingly, a measurement limit pair may be composed of a first upper current limit I1' and a first upper voltage limit U1', or a first upper current limit I1' and a first upper power limit P1'. In addition or alternatively, a measurement limit pair may also be composed of a first upper voltage limit U1' and a first upper power limit P1'.

[0051] The second threshold value includes a plurality of measurement variables, including a second upper current limit I2' and a second upper voltage limit U2' or a second upper power limit P2'. Accordingly, the measurement limit pair may be composed of the second upper current limit I2' and the second upper voltage limit U2', or the second upper current limit I2' and the second upper power limit P2'. In addition or alternatively, the measurement limit pair may also be composed of the second upper voltage limit U2' and the second upper power limit P2'.

[0052] Here, the first upper current limit I1' is equal to or greater than the second upper current limit I2'. Here, the first upper voltage limit U1' is equal to or greater than the second upper voltage limit U2'. The first upper power limit P1' is equal to or greater than the second upper power limit P2'.

[0053] Figure 2 A power supply 10 with a device 20 for monitoring a power supply is shown. Here, the device 20 includes a first monitoring element 110 and a second monitoring element 120. The first monitoring element 110 includes a voltage divider on one side, which derives a signal S(U1) from the voltage U1. In addition, the first monitoring element 110 includes a current measuring device, which is implemented as a current measuring resistor (shunt). The current measuring device derives a signal S(I1) from the current I1. The signals S(U1) and S(I1) are supplied to a first comparator 115, which checks the individual threshold values ​​of the upper limits of the current I1', the voltage U1' and the power P1'. When at least one individual threshold value is exceeded, the first comparator 115 reports to the control element 105 on the primary side that the corresponding upper limit is exceeded. In addition, the report may also include the degree of the exceedance and an explanation of the variation curve of the exceedance. In particular, the over-limit may only be reported after a certain time has passed, as will be described in detail below.

[0054] The second monitoring element 120 includes a voltage divider on one side, which derives a signal S(U2) from the voltage U2. In addition, the second monitoring element 120 includes a current measuring device, which is implemented as a current measuring resistor (shunt). The current measuring device derives a signal S(I2) from the current I2. The signals S(U2) and S(I2) are supplied to a second comparator 125, which checks the individual threshold values ​​of the upper limits of the current I2', the voltage U2' and the power P2'. When at least one individual threshold value is exceeded, the second comparator 125 reports to the control element 105 on the primary side that the corresponding upper limit has been exceeded. As in the first comparator 115, the second comparator 125 can also include, in addition to the report, the degree of the excess and an explanation of the variation curve of the excess. In particular, the excess can be reported only after a certain time has passed, as will be described in detail below.

[0055] The power supply 10 together with the device 20 comprises a fuse F1 on the primary side, which is arranged on one of the two input conductors of the two input terminals. It also comprises an EMC protection circuit (without reference numerals), which is arranged between the two input conductors. It further comprises a rectifier circuit D1 terminating the two input conductors. It also comprises a capacitor C1 for smoothing the input voltage, which is connected to the two output conductors of the rectifier circuit D1. In addition, the device 20 comprises a voltage converter 100 of the primary side portion, which is connected to the capacitor C1. Finally, the device 20 comprises a control element 105 and a switching element 220 connected thereto, for switching of the primary side of the voltage converter 100. The control element 105 is also connected to the primary side portion of the optocouplers OC1 and OC2.

[0056] On the secondary side, the power supply 10 together with the device 20 comprises a voltage converter 100 of the secondary side, a diode D2 in one of the two conductors of the voltage converter 100 of the secondary side, and a capacitor C2, which is arranged between the conductors of the voltage converter 100 of the secondary side. In addition, the secondary side comprises an EMC filter (without reference numeral) at the output U2 / I2 of the power supply. Finally, the secondary side also comprises the secondary side parts of the optocouplers OC1 and OC2, which are connected to the comparator / regulator 115 or 125. On the primary side, the two optocouplers OC1 and OC2 control the power switch 220 by corresponding conversion 105, for example by pulse width modulation or pulse frequency modulation.

[0057] Figure 3A power supply 10 with a device 20 for monitoring a power supply is shown, the power supply having a voltage converter 100, a first monitoring element 110, a second monitoring element 120, and a second output unit 130. The power supply 10 with the device 20 comprises a first output unit 180, which provides a second current I2 and a second voltage U2 at a first supply output 190. The first output unit 180 comprises a second monitoring element 120. The second output unit 130 comprises a second supply output 140 that provides a third current I3 and a third voltage U3. The first monitoring element 110 is connected to an optocoupler OC1 230. It can also be supplemented with an optocoupler OC2. Here, the first monitoring element 110 reports signals S(I1) and S(U1). The second monitoring element 120 is connected to an optocoupler OC2 240. Here, the second monitoring element 120 reports signals S(I2) and S(U2). The first output unit 180 and the second output unit 130 are supplied with current I1 and voltage U1 by the first monitoring element 110. In another embodiment, a plurality of second output units 130 may be arranged in parallel, and the plurality of second output units are respectively supplied with current I1 and voltage U1 by the first monitoring element 110. In addition, alternatively or additionally, a plurality of first output units 180 may also be arranged in parallel, and the plurality of first output units are respectively supplied with current I1 and voltage U1 by the first monitoring element 110.

[0058] Figure 4 A power supply 10 with a device 20 for monitoring a power supply is shown, which has a first output unit 180 and a second output unit 130. The first output unit 180 includes a first switch 200 for disconnecting a first supply output 190. The first switch 200 is controlled by a second monitoring element 120 and interrupts the provision of a second current I2 and a second voltage U2 when a second threshold value is exceeded. In addition, the second monitoring element 120 includes a voltage divider for determining a signal S(U2) and a current measuring device for determining the signal S(I2) implemented as a current measuring resistor (shunt). The second monitoring element 120 also includes a second comparator 125. The first output unit 180 includes a display in the form of a light-emitting diode D4 for reporting a threshold value violation, which is controlled by the second comparator 125.

[0059] In addition, the power supply 10 having the device 20 includes the Figure 2 The primary-side electrical components known from the prior art, in particular the EMC filter, the rectifier D1, the capacitor C1, the primary-side portion of the voltage converter 100, the primary-side control element 105, the switching element 220 and the primary-side portion of the optocouplers OC1 and OC2 are shown. On the secondary side, a circuit similar to Figure 2The power supply 10 of the device 20, the voltage converter 100 of the secondary side, the diode D2, the capacitor C2, the EMC filter (without reference numeral) at the output of the first monitoring element 110 and the secondary side of the optocouplers OC1 and OC2. The connection of the components largely corresponds to Figure 2 .

[0060] The second output unit 130 provides a third current I3 and a third voltage U3 at the second supply output 140. In this case, the first monitoring element 110 provides the second output unit 130 with a first current I1 and a first voltage U1.

[0061] The second output unit 130 comprises a second switch 210 for disconnecting the second supply output 140. The second switch 210 is controlled by the second output unit 130 and interrupts the provision of the third current I3 and the third voltage U3 when the third threshold value is exceeded. Optionally, the second output unit 130 may comprise a voltage divider (not shown) for determining a signal S(U3) based on the voltage U3. In addition, optionally, the second output unit 130 may comprise a current measuring device (not shown), which is implemented as a current measuring resistor (shunt) for determining the signal S(I3). The second output unit 130 also comprises a display in the form of a light-emitting diode D3 for reporting the threshold value exceeding the limit, which is controlled by the second output unit 130. Further optionally, the second output unit 130 may electrically transmit the signals S(U3) and S(I3) to the first comparator 115 of the first monitoring element 110 via a connecting wire.

[0062] The first switch 200 is switched in response to the exceeding of the second threshold. Optionally, the reporting of the second threshold is based on a fault of the first switch 200. This can be coupled in combination with the reporting of the exceeding of the second threshold or reported separately. The report may include, in addition to the details of the exceeding of the second threshold, an indication of the first switch 200 and its function (e.g., fault) and position (open, closed). The separation of the first switch 200 is based on an internal signal of the first output unit 180.

[0063] The second switch 210 is switched according to the exceeding of the third threshold. Here, the separation of the second switch 210 is based on the internal signal of the second output unit 130. Optionally, the report of the exceeding of the third threshold can be based on the failure of the second switch 210. Further optionally, the second switch 210 can be controlled by the first comparator 115.

[0064] like Figure 2As shown, the switching element 220 arranged on the primary side is arranged between the primary-side control element 105 and the voltage converter 100 and is electrically conductively connected to them. Here, the switching element 220 controls the voltage converter 100 on the primary side based on the signal of the primary-side control element 105. The control causes an influence on the first current I1 and the first voltage U1. Alternatively, the control causes the disconnection of the first current I1 and the disconnection of the first voltage U1.

[0065] The connection of the conductive signal to the primary-side control element 105 comprises optical coupling elements 230, 240. Alternatively, the coupling elements 230, 240 may also comprise inductive and / or capacitive couplings. Optionally, the connection of the conductive signal to the first monitoring element 110 may comprise a first coupling element 230, and the connection of the conductive signal to the second monitoring element 120 may comprise a second coupling element 240. Here, the first coupling element 230 and the second coupling element 230 may be arranged in parallel.

[0066] The monitoring elements 110, 120 are designed to monitor the exceeding of a threshold value and the duration of the exceeding of the threshold value. The reporting of the exceeding of the threshold value can be carried out only after the expiration of a predetermined duration. The duration is selectable.

[0067] The thresholds can be set by the user. This includes the settability of the upper current limits I1', I2', I3', the upper voltage limits U1', U2', U3' and the upper power limits P1', P2' and P3'. Optionally, it can also include the individually settable duration of each threshold exceeding the limit.

[0068] The power supply 10 complies with the low voltage requirement SELV (Safety Extra Low Voltage).

[0069] The voltage converter 100 of the power supply 10 may include a transformer or a switching power supply or a hard-switching current converter or a latching converter or a resonant switching converter.

[0070] In other words, the invention can be summarized as follows: In a SELV low-voltage power supply system with a DC voltage <60 volts DC (direct current voltage), for example 12 volts or 24 volts DC, the output power is permanently limited to less than 100 watts in accordance with UL 1310 (class II power unit) for increased safety. Likewise, the corresponding limiting mechanisms such as voltage limiting, current limiting and power limiting must be implemented redundantly and therefore in duplicate in a simple fail-safe manner.

[0071] Likewise, safety-oriented systems also face increased demands for protection against overvoltages and overcurrents. It must be taken into account that the highest voltage in the power supply system determines the system voltage and that components only operate safely up to the voltage limit. If the current limit is exceeded, faulty loads connected to the system can cause malfunctions.

[0072] This limitation has a significant impact on the components connected thereto and the installation. In the case of non-redundant power-limited power supplies, for example, significant safety margins must be taken into account in the wiring and / or their installation is only permitted to those skilled in the art.

[0073] In the prior art, this redundant power limitation is achieved by a small power supply that does not allow a power throughput of 100 watts. Here, the first power limitation is constituted by the natural power limitation of the power supply, which is derived due to the maximum power limitation of the transformer 100. The second current limitation is constituted by the current limiter that is usually installed. These two mechanisms simply limit the maximum power to a certain upper limit in a fail-safe manner. However, due to the significant inaccuracy of the limitation, this requires a significant distance from the maximum possible output power. Similarly, the downstream fuses at the output of the power supply 10 require a significant safety distance because these fuses allow a significantly higher current than the rated value of the fuse for a certain period of time, and the rated value is also highly dependent on the ambient temperature. In short, these methods generally allow limitation to a maximum of 2 / 3 of the possible maximum output power. In order to significantly more closely approach the power limit value, an embodiment implements a power supply that redundantly implements two voltage and current regulation (or voltage and current limitation).

[0074] The solutions of the prior art described above have the disadvantage that they either cause a significant safety distance from the maximum output power or are implemented at increased cost by redundant regulation and / or limitation. Likewise, power limitation is only implemented in power supplies that have only this power limitation.

[0075] The present invention provides a solution for a flexible redundantly power-limited power supply having one or more redundantly limited output terminals 190 and one or more non-redundantly singly limited output terminals 140 .

[0076] In the power supply 10 according to the invention, the output voltage U1 is regulated, and the current I1 of the output terminal is simply detected and limited. Any number of modules 180 are connected downstream thereof, which have additional voltage- and current regulation / limitation 120, with voltage and current regulators / limiters for U2 and I2. These modules 180 also measure the output voltage and output current independently of the rest of the circuit, and report the corresponding output voltage and output current to the upstream power supply 110. The total output current of all unprotected output terminals 140 is also detected as I3. The power supply 10 calculates the current through each single redundant limited output terminal by subtracting the current I3 and the current I2 of all unprotected output terminals and, if necessary, the additional redundant limited output terminals from the total current I1. If the output current of the redundantly protected output terminal exceeds the limit, then as a first mechanism, the limiting device in the module 180 disconnects the output terminal. However, for redundancy, the power supply 10 can additionally no longer supply power to the output terminal, and thus disconnect the output terminal, or disconnect the entire output voltage U2 and U3 as a supplement.

[0077] For example, if redundantly protected outputs 190 supply sensors via wiring with a permissible small cross section, the complete disconnection of power supply 10 is particularly important. If these sensors fail, it is advantageous to disconnect the entire system in order to, for example, prevent unmonitored operation of connected loads.

[0078] The module 180 for voltage and current regulation (or limitation) can be powered independently of the measured output current of the power supply via another connection or also powered by the measured output current. In the latter case, the current consumption of the limiting module 180 is either taken into account in the calculation or can be ignored if the current consumption is significantly smaller than the limitation.

[0079] In this way, a modular power supply system can be realized, which provides significantly higher output power overall and also allows for redundant, simple, fail-safe outputs 180 with small cross-section wiring. The proposed power supply system can be realized in a power supply, for example. The individual output channels can be realized with different switchable current limits.

[0080] The power supply 10 is composed of an input end and a single voltage and current regulated output end 140 shown here and a redundant regulated output end 190. The power supply 10 has a primary side circuit part and a secondary side circuit part for this purpose. The energy of the input side is transmitted to the secondary side via the transformer TR1. The power supply can be designed as a galvanically isolated switching power supply with a galvanic isolation device, or it can be designed as not galvanically isolated. The voltage and current regulation U1 and I1 of the power supply 10 detect the output variable on the secondary side, and report the fault back to the primary side through the photocoupler OC1, where the power path of the primary side is controlled accordingly. However, the regulation of the first output variables U1 and I1 can also be carried out on the primary side, especially in the case of a fixed input voltage. Similarly, the described implementation does not depend on the type of switching power supply. This can be implemented arbitrarily, for example, in the form of a hard switch as a flow converter or a locking converter, or in the form of a resonant switch, for example, as LLC. Similarly, capacitive transmission can also be used instead of inductive power transmission. The implementation of feedback coupling is also only schematically shown in principle, and other methods such as inductive feedback coupling are also possible. The power switches 200 , 210 can likewise be controlled on the primary side or on the secondary side. What is decisive is only that a first control of the output variables U1 and I1 is present for the single-controlled output 140 .

[0081] In the first module 130 connected downstream, the first output 140 of the switched mode power supply 10 is supplied by the power path on the secondary side as a single protected output 140. The output is monitored redundantly with voltage and current limiting signals S(U2) and S(I2) in a simple fail-safe manner using a further module 180. If one of these signals S(U2) or S(I2) reports an excess of a limit value, at least the output 190 is disconnected via the switch S1. Likewise, in this fault situation, the entire power supply 10 is disconnected, or another switch before the output module 180 disconnects it. If the calculation of the total current I1 minus the current I3 through one or more unprotected outputs results in a redundant, simple fail-safe output current exceeding the limit, then the switch S1 is also disconnected and the redundantly regulated output 190 is disconnected.

[0082] The modules 180 and / or 130 on the output side can be installed or can also be implemented as plug-in modules. They can also individually send a signal to the user to maintain the current via LEDs D3 and D4. In addition, the individual outputs can be disconnected independently when the output current exceeds the limit. Similarly, the configuration of the outputs can be fixedly predetermined or can be adjusted by switches or by interfaces.

[0083] In this context, two types of outputs 190 and 140 are important in the power supply. The single-protected output 140 consists of a single monitoring and / or control (e.g. regulation) of the output voltage and output current U3 and I3. In contrast, one or more simple fail-safe outputs 190 each have a fully redundant monitoring and / or control (e.g. regulation) with two separate voltage and current measurements U1 and U2 or I1 and I2, separate control (e.g. regulation) and separate feedback couplings OC1 and OC2, and optionally separate intervention possibilities on the primary side.

[0084] Figure 5 A method 300 for monitoring a power supply of a safety low voltage is shown. The method comprises monitoring 310 a first current I1 and a first voltage U1 outputted by a voltage converter on the secondary side by a first monitoring element. In addition, the method comprises: if a first threshold value is exceeded, based on the first current I1 and the first voltage U1, a primary-side control element connected to the first monitoring element in a signal-conducting manner controls the voltage converter on the primary side 320. The method also comprises monitoring 330 a second current I2 and a second voltage U2 by a second monitoring element, wherein the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1. The second monitoring element is supplied with the first current I1 and the first voltage U1 by the first monitoring element. In addition, the method comprises controlling 340 the voltage converter on the primary side based on the second current I2 and the second voltage U2, if a second threshold value is exceeded, wherein the primary-side control element is connected to the second monitoring element in a signal-conducting manner.

[0085] Here, method 300 for regulating a switched mode power supply with the aid of at least two output voltages may include a first regulation, which generates a first output voltage U1, I1 and outputs it as a third output voltage U3, I3, and includes a second output voltage U2, I2, which is supplied by the first output voltage U1, I1 and outputs it as a second output voltage U2, I2.

[0086] Here, the output current I3 of the third output voltage U3, I3 is subtracted from the total output current I1 as the first calculated output current of the second output voltage U2, I2 and coupled back to the primary side as a first signal. The second output voltage U2, I2 includes its own, independent second regulation, which has a second independent feedback coupling to the primary side and enables a double, simple fail-safe regulation of the second output voltage U2, I2.

[0087] In an embodiment, the output voltages U2 and U3 of the output terminals may be settable. In another embodiment, the output current may be individually settable for each output terminal. Here, the output power may be individually settable for each output terminal. In addition, the current or power can be set to a certain limit value and the maximum time can be set individually for each output terminal. In addition, the behavior when the limit value exceeds the limit can be settable for this purpose, wherein in an embodiment, the entire power supply can be disconnected or the corresponding output terminal exceeding the limit value can be disconnected. In addition, the setting of the limit value and / or the output terminal or the reported state can be performed both on the power supply and through an interface with a control device. In addition, another output voltage can be generated and the other output voltage can be adjusted singly or doubly corresponding to the described method.

[0088] Although the present invention has been described with reference to exemplary embodiments, it is understood by those skilled in the art that various changes may be made and equivalents may be used to replace. In addition, many modifications may be made to adapt specific situations or electrical appliances to the teachings of the present invention. Therefore, the present invention is not limited to the disclosed embodiments, but includes all embodiments falling within the scope of the appended claims.

[0089] Description of Reference Numerals

[0090] 10 Power Supply

[0091] 20 Device for monitoring power supply

[0092] 100 Input Voltage Voltage Converter

[0093] 105 Primary side control elements

[0094] 110 First monitoring element for U1 and I1

[0095] 115 First Comparator

[0096] 120 Second monitoring element for U2 and I2

[0097] 125 Second comparator

[0098] 130 Second output unit

[0099] 140 second power supply output terminal

[0100] 180 first output unit (eg module)

[0101] 190 first power supply output terminal

[0102] 200 First Switch

[0103] 210 Second switch

[0104] 220 switch element

[0105] 230 first coupling element

[0106] 240 second coupling element

[0107] 300 Method for monitoring power supply

[0108] 310 Monitoring by the first monitoring element

[0109] 320 Primary side control via primary side control element

[0110] 330 Monitoring by the second monitoring element

[0111] Primary-side control of a 340 voltage converter

Claims

1. A device (20) for monitoring a power supply (10) for a safety low voltage, the device comprising: a first monitoring element (110) which is designed to monitor a first current I1 and a first voltage U1 which are output on the secondary side by the voltage converter (100), a primary-side control element (105) which is connected to the first monitoring element (110) in a signal-conducting manner and is designed to control the voltage converter (100) on the primary side based on a first current I1 and a first voltage U1 when a first threshold value is exceeded, and a second monitoring element (120) configured to monitor a second current I2 and a second voltage U2, wherein the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1, wherein the second monitoring element (120) is supplied with the first current I1 and the first voltage U1 by the first monitoring element (110), The primary-side control element (105) is connected to the second monitoring element (120) in a signal-conducting manner and is designed to control the voltage converter (100) on the primary side based on a second current I2 and a second voltage U2 when a second threshold value is exceeded.

2. The device (20) for monitoring a power supply according to claim 1, wherein: The first threshold includes a first current upper limit I1' and a first voltage upper limit U1', or a first power upper limit P1', The second threshold value includes a second current upper limit I2', a second voltage upper limit U2', or a second power upper limit P2'. The first upper current limit I1' is equal to or greater than the second upper current limit I2', and the first upper voltage limit U1' or the first upper power limit P1' is equal to or greater than the second upper voltage limit U2' or the second upper power limit P2'.

3. The device (20) for monitoring a power supply according to any one of the preceding claims, further comprising: A first output unit (180) provides a second current I2 and a second voltage U2 at a first power supply output terminal (190), wherein the first output unit (180) comprises a second monitoring element (120).

4. The device (20) for monitoring a power supply according to claim 3, The first output unit (180) comprises a first switch (200) for disconnecting the first power supply output terminal (190).

5. The device (20) for monitoring a power supply according to any one of the preceding claims, further comprising: a second output unit (130) which provides a third current I3 and a third voltage U3 at a second power supply output terminal (140), The first monitoring element (110) supplies the second output unit (130) with a first current I1 and a first voltage U1.

6. The device (20) for monitoring a power supply according to claim 5, The second output unit (130) comprises a second switch (210) for disconnecting the second power supply output terminal (140).

7. The device (20) according to any one of claims 4 to 6, in, The first switch (200) is switched in response to an exceeding of a second threshold, and / or wherein the second switch (210) is switched in response to an exceeding of a third threshold, and / or wherein the reporting of the second threshold is based on a failure of the first switch (200), and / or wherein, optionally, the reporting of the third threshold is based on a failure of the second switch (210).

8. The device (20) according to claim 7, The disconnection of the second switch (210) is based on an internal signal of the second output unit (130), and / or the disconnection of the first switch (200) is based on an internal signal of the first output unit (180).

9. The device (20) according to any one of the preceding claims, in, A switching element (220) arranged on the primary side is arranged between a control element (105) on the primary side and the voltage converter (100) and is electrically conductively connected to them. wherein the switch element (220) controls the voltage converter (100) on the primary side based on a signal of a control element (105) on the primary side, Therein, the control results in an influencing of the first current I1 and the first voltage U1 , or the control results in a disconnection of the first current I1 and a disconnection of the first voltage U1 .

10. Device (20) for monitoring a power supply according to any one of the preceding claims, in, The signal-conducting connection to the primary-side control element (105) comprises an inductive and / or capacitive and / or optical coupling element (230, 240), Optionally, the connection for conducting signals with the first monitoring element (110) includes a first coupling element (230), and the connection for conducting signals with the second monitoring element (120) includes a second coupling element (240).

11. Device (20) for monitoring a power supply according to any one of the preceding claims, in, The monitoring element (110, 120) is designed to monitor the exceeding of the threshold value and the duration of the threshold value exceeding, wherein the threshold value exceeding is not reported until a predefined duration has elapsed.

12. Device (20) for monitoring a power supply according to any one of the preceding claims, in, The threshold value can be set by a user and / or wherein the setting of the threshold value includes a respectively settable duration of the threshold value being exceeded.

13. A power supply (10) for a safety low voltage (10), wherein: The power supply complies with low voltage requirements SELV according to any of the preceding claims.

14. The power supply (10) for safety low voltage (10) according to claim 13, The voltage converter (100) comprises a transformer or a switching power supply or a hard-switching flow converter or a locking converter or a resonant switching converter.

15. A method (300) for monitoring a power supply (10) for safety low voltage, the method comprising: monitoring (310) a first current I1 and a first voltage U1, which are output on the secondary side by the voltage converter (100), by means of a first monitoring element (110), When a first threshold value is exceeded, the voltage converter (100) is controlled on the primary side (320) based on the first current I1 and the first voltage U1 by a primary-side control element (105), which is connected to the first monitoring element (110) in a signal-conducting manner, monitoring (330) a second current I2 and a second voltage U2 by means of a second monitoring element (120), wherein the second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1, wherein the second monitoring element (120) is supplied with the first current I1 and the first voltage U1 by the first monitoring element (110), When a second threshold value is exceeded, the voltage converter (100) is controlled (340) on the primary side based on the second current I2 and the second voltage U2, wherein the primary side control element (105) is connected to the second monitoring element (120) in a signal-conducting manner.

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