Device for monitoring a power supply

Abstract

According to one aspect, a device (20) for monitoring a power supply (10) for safety extra low voltage, comprises: 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) that 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 the first current (I1) and the first voltage (U1), if a first threshold value is exceeded; and, 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), wherein the second monitoring element (120) is supplied with the first current (I1) and the first voltage (U1) by the first monitoring element (110), wherein 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 the second current (I2) and the second voltage (U2), if a second threshold value is exceeded.

Description

[0001] Device for monitoring a power supply

[0002] The invention relates to a technology for monitoring a power supply. Without being limited thereto, the invention particularly relates to a device for monitoring a safety extra-low voltage power supply, in which the available power is increased relative to the maximum possible output power. For this purpose, voltage and current regulation or limitation are implemented redundantly with two limiters arranged in series.

[0003] In power supplies for safety extra-low voltage, also known in technical terms as SELV (Safety Extra Low Voltage), direct current (DC) of up to 60 volts is provided. For example, when providing 12 or 24 volts DC, the output power is limited to less than 100 watts permanently to increase safety according to UL 1310 (Underwriters Laboratories). In addition, the associated limiting mechanisms such as voltage, current and power limitation must be simple fail-safe redundant and therefore present in duplicate. Likewise, such safety-oriented systems are subject to increased requirements with regard to overvoltages and overcurrents. This takes into account that the highest voltage in a power supply system determines the system voltage of the power supply and that the components only operate safely up to a maximum voltage limit.If a current limit is exceeded, a faulty load connected to the system may cause errors.

[0004] This redundant power limitation is achieved by small power supplies known from the state of the art, whose power throughput is well below 100 watts. The first power limitation consists of the natural power limitation of a power supply, which results from the maximum power limitation of the transformer. The second current limitation consists of the typically built-in current limitation, for example, in the form of a current fuse, such as a fuse. Both mechanisms limit the maximum power to a specific upper limit in a simple, fail-safe manner. However, due to the considerable inaccuracy of the limits, this requires a considerable margin from the maximum possible output power.Likewise, downstream fuses at a power supply output require a considerable safety margin, as they allow a significantly higher current than the fuse's rated value for a certain period of time, which also depends heavily on the ambient temperature. In summary, these methods typically allow a maximum limit of two-thirds of the possible output power.

[0005] The invention is therefore based on the object of providing a technology for reducing the gap between the system power and the maximum possible output power in a safety extra-low voltage power supply while maintaining the required safety conditions. This allows the maximum utilization of the power supply to be increased, which also leads to a reduction in power supply costs.

[0006] The object is achieved by the features of the independent claims. Expedient embodiments and advantageous further developments of the invention are specified in the dependent claims.

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

[0008] A first aspect relates to a device for monitoring a power supply for safety extra-low voltage. The device comprises a first monitoring element. This is designed to monitor a first current I1 and a first voltage U1, which are output on the secondary side by a voltage converter. The device further comprises a primary-side control element which is signal-conductingly connected to the first monitoring element and is designed to control the voltage converter on the primary side based on the first current I1 and the first voltage U1. The control begins at least when a first threshold value is exceeded. The device further comprises a second monitoring element which is designed to monitor a second current I2 and a second voltage U2. The second current I2 and the second voltage U2 are based on the first current I1 and the first voltage U1.Furthermore, the second monitoring element is supplied with the first current I1 and the first voltage U1 by the first monitoring element. The primary-side control element is connected to the second monitoring element in a signal-conducting manner and is designed to control the voltage converter on the primary side based on the second current I2 and the second voltage U2 when a second threshold is exceeded.

[0009] Advantageously, by providing dual feedback to the primary side of the power supply, embodiments can easily incorporate fail-safe voltage and current limits, voltage and power limits, or current and power limits into their control, thus improving the control on the primary side. In particular, such control of the primary side can better ensure compliance with the required limit values ​​or achieve a complete shutdown of the power supply, for example, if the control fails or fails to achieve success in other ways (e.g., by limiting current, voltage, or power, or by selectively shutting down individual output units, i.e., output channels).

[0010] Preferably, the first threshold can comprise a first upper current limit, 11', and a first upper voltage limit, U1', or a first upper power limit, P1'. In this case, the first threshold can be exceeded by exceeding the first upper current limit, 11', alone. Additionally or alternatively, the first threshold can be exceeded by exceeding the first upper voltage limit, U1', alone. Further additionally or alternatively, the first threshold can be exceeded by exceeding the first upper power limit, P1', alone.

[0011] Alternatively or additionally, the second threshold can comprise a second upper current limit, I2', and a second upper voltage limit, U2', or a second upper power limit, P2'. In this case, the second threshold can be exceeded solely by exceeding the second upper current limit, I2'. Additionally or alternatively, the second threshold can be exceeded solely by exceeding the second upper voltage limit, U2'. Further additionally or alternatively, the second threshold can be exceeded solely by exceeding the second upper power limit, P2'.

[0012] The first current limit, I1', can be equal to or greater than the second current limit, I2'. Alternatively or additionally, the first voltage limit, U1', can be equal to or greater than the second voltage limit, U2'. Alternatively or additionally, the first power limit, P1', can be equal to or greater than the second power limit, P2'.

[0013] Advantageously, a large number of upper limit violations can be used to control the voltage converter, which can monitor both the current, the voltage, and their product, the power. Furthermore, due to the increased current, voltage, and power values ​​compared to the second monitoring element, additional output units with monitoring functions can be connected to the first monitoring element in parallel to the output units with the second monitoring function.

[0014] The device for monitoring the power supply can comprise a first output unit. This can provide the second current I2 and the second voltage U2 at a first supply output. The supply output of the output unit can be identical to the supply output of the power supply. The supply output can serve to electrically supply loads, for example, sensors or the like, that perform a monitoring function. For safe operation of the loads, it is necessary not to exceed a maximum current, a maximum voltage, and / or a maximum power. The first output unit can comprise the second monitoring element.

[0015] Advantageously, the current, voltage, and power provided at the power supply output can be incorporated into the control system. Furthermore, component design can be simplified or a modular design enabled by designing a combination of output unit and monitoring element as a replaceable and / or add-on component.

[0016] Furthermore, the first output unit can comprise a first switch for switching off the first supply output. This switch can be controlled by the second monitoring element. The second monitoring element can monitor the second threshold. This can include monitoring the second upper current limit I2, the second upper voltage limit U2, and / or the second upper power limit P2. Alternatively, upper limits of current I1', voltage U1', and power P1' can also be monitored, which are based on the second upper current limit I2, the second upper voltage limit U2, and / or the second upper power limit P2.

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

[0018] In addition, a second output unit, which provides a third current I3 and a third voltage U3 at a second supply output, can be arranged in the device for monitoring the power supply and electrically connected. 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. The second output unit can differ from the first output unit with regard to the type and extent of monitoring as well as the amount of the monitored upper limits of current, voltage and / or power.

[0019] Advantageously, a plurality of currents I2, I3, voltages U2, U3, and powers P2, P3 can be monitored, whereby the currents and voltages may differ from one another. Furthermore, different monitoring mechanisms can be used by designing the output units differently.

[0020] Furthermore, in the device for monitoring the power supply, the second output unit can comprise a second switch for switching off the second supply output. The second output unit can monitor a third threshold. This can include monitoring the third upper current limit 13, the third upper voltage limit U3, and / or a third upper power limit P3. Alternatively, upper limits for the current, I3', voltage, U3', and power P3' can also be monitored, which are based on the third upper current limit 13, the third upper voltage limit U3, and / or the third upper power limit P3.

[0021] Advantageously, an overload condition in the form of a first threshold violation can be eliminated locally in the second output unit. Furthermore, the second output unit can be designed more cost-effectively by eliminating the need for signaling to the primary control element.

[0022] Furthermore, in the device, the first switch can be switched depending on the second threshold being exceeded. The second switch can be switched depending on the third threshold being exceeded. Alternatively or additionally, signaling of the second threshold can be based on a malfunction of the first switch. Alternatively or additionally, signaling of the third threshold can optionally be based on a malfunction of the second switch.

[0023] Advantageously, a differentiated switch actuation and thus shutdown of the respective electrical supply can be achieved depending on the exceeding of the respective threshold values.

[0024] Furthermore, the disconnection of the second switch can be based on internal signals of the second output unit. Alternatively or additionally, the disconnection of the first switch can be based on internal signals of the first output unit.

[0025] Optionally, at the same time as the first switch is switched off, the primary-side control element can also be signaled that the first threshold has been exceeded. Further optionally, the primary-side control element can be signaled that the first switch is malfunctioning. This can include a signal if the switch is not opened successfully. The signaling options to be activated can be preset in the device. Further optionally, the signal to the primary-side control element can be omitted if the third threshold is exceeded. Alternatively, at the same time as the second switch is switched off, the primary-side control element can also be signaled that the third threshold has been exceeded. Further optionally, the primary-side control element can be signaled that the second switch is malfunctioning. This can include a signal if the switch is not opened successfully.The signaling options to be activated can be preset in the device.

[0026] Advantageously, it is possible to react flexibly (e.g. selectively for individual output units) and / or preset to exceedances of threshold values ​​or malfunctions in the output units both locally in the output units and in connection with the primary side.

[0027] Furthermore, the device can comprise a switching element arranged on the primary side, which is arranged between the primary-side control element and the voltage converter and is electrically connected thereto. The switching element arranged on the primary side can control the voltage converter on the primary side based on signals from the primary-side control element. This control influences the first current I1 and the first voltage U1. Alternatively, this control causes the first current I1 to be switched off and the first voltage U1 to be switched off.

[0028] This allows for central control of the voltage converter.

[0029] In each variant mentioned herein, in the device for monitoring the power supply, the signal-conducting connection to the primary-side control element can comprise an inductive and / or a capacitive and / or an optical coupling element. Optionally, the signal-conducting connection to the first monitoring element can comprise a first coupling element, and the signal-conducting connection to the second monitoring element can comprise a second coupling element (which is different from the first coupling element). The first coupling element can also comprise the signal-conducting connection to the second output unit. The coupling elements can be arranged in parallel. The coupling elements can use the same or different technologies (inductive, capacitive, optical). Further alternatively, each signal-conducting connection can comprise its own coupling element, wherein the coupling elements can optionally be arranged parallel to one another.The coupling elements can galvanically separate the secondary side from the primary side of the power supply.

[0030] This advantageously increases the fault redundancy in threshold monitoring while simultaneously galvanically isolating the secondary and primary sides of the power supply.

[0031] Furthermore, the monitoring elements of the power supply monitoring device can be configured to monitor for threshold exceedances and the duration of the threshold exceedance. Signaling of a threshold exceedance can only occur after the specified duration has elapsed. The value of an exceedance threshold can be a multiple of the threshold, for example, 2 to 10 times the threshold. Furthermore, the duration of the threshold exceedance can be 2 to 5 seconds. The exceedance threshold and the duration of the threshold exceedance can be preset in the device.

[0032] This advantageously allows monitoring to be individually adapted to the consumers to be connected, which may, for example, include the operation and, in particular, the start-up of motors.

[0033] Furthermore, the threshold values ​​in the power supply monitoring device can be user-adjustable. The settings can also be made from a remote station (e.g., one that is spatially or network-topologically separated) and received via an interface. Alternatively or additionally, the threshold settings can each include an adjustable duration for the permitted threshold exceedance.

[0034] This allows for effective adaptation to the respective connected consumers.

[0035] Furthermore, a safety extra-low voltage power supply can include a device for monitoring the power supply. The power supply can meet SELV (Safety Extra-Low Voltage) requirements. Furthermore, it can also comply with UL 1310 standards.

[0036] This allows for simpler wiring (e.g., with a smaller wire cross-section) for the connected loads. Another advantage is that the loads can also be connected by less qualified personnel.

[0037] In addition, the voltage converter of the power supply may comprise a transformer or a switching power supply or a hard-switching forward or flyback converter or a resonant switching converter.

[0038] This makes it possible to advantageously meet the various requirements for the power supply in terms of costs, stability of current, voltage and power and / or installation space.

[0039] A second aspect relates to a method for monitoring a safety extra-low voltage power supply. The method comprises monitoring, with a first monitoring element, a first current, I1, and a first voltage, U1, which are output on the secondary side by a voltage converter. The method further comprises controlling the voltage converter on the primary side with a primary-side control element that is signal-conductingly connected to the first monitoring element, based on the first current, I1, and the first voltage, U1, when a first threshold value is exceeded. The method further comprises monitoring, with a second monitoring element, 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 is supplied with the first current, I1, and the first voltage, U1, by the first monitoring element. Furthermore, the method comprises controlling the voltage converter on the primary side based on the second current, I2, and the second voltage, U2, when a second threshold is exceeded, wherein the primary-side control element is connected to the second monitoring element in a signal-conducting manner. The invention is explained in more detail below with reference to the accompanying drawings using preferred embodiments that can be optionally combined with one another.

[0040] They show:

[0041] Fig. 1 is a schematic block diagram of a power supply with a device for monitoring it according to a first embodiment,

[0042] Fig. 2 shows a power supply with a device for monitoring it according to a second embodiment,

[0043] Fig. 3 shows a power supply with a device for monitoring it with a first monitoring element, a second monitoring element and a second output unit according to a third embodiment,

[0044] Fig. 4 shows a power supply with a device for monitoring it with a first output unit and a second output unit according to a fourth embodiment, and

[0045] Fig. 5 shows a method for monitoring a safety extra-low voltage power supply.

[0046] Fig. 1 shows a schematic block diagram of a power supply 10 with a device 20 for monitoring it. The device 20 is used to monitor a power supply 10 for safety extra-low voltage. The power supply 10 comprises input terminals to which a standard supply voltage of 230 volts or 120 volts AC is applied. Furthermore, 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 available.

[0047] 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 output on the secondary side by a voltage converter 100. For this purpose, the device 20 is electrically connected to the voltage converter 100. The device 20 further comprises a primary-side control element 105, which is signal-conductively 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 corresponding to the first current S(I1) and a signal corresponding to the first voltage S(U1) are generated in the first monitoring element 110 and fed 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 signal-conductively connected to the second monitoring element 120 and is designed 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 corresponding to the second current S(I2) and a signal corresponding to the second voltage S(U2) are generated in the second monitoring element 120 and fed 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 evident from the term.

[0048] The SELV power supply 10 is designed for safety extra-low voltage according to UL 1310 (Class II Power Unit). The voltage converter 100 of the power supply 10 is galvanically isolating or, alternatively, non-galvanically isolating. The voltage converter 100 is a transformer or a switched-mode power supply, a hard-switching forward or flyback converter, or a resonant-switching converter, designed, for example, as an LLC. The LLC converter (two inductors, one capacitor) is a resonant converter with three reactive elements.

[0049] The first threshold comprises several measured variables, which include a first upper current limit IT and a first upper voltage limit UT or a first upper power limit PT. Accordingly, measurement limit pairs can consist of the first upper current limit IT and the first upper voltage limit UT, or of the first upper current limit IT and the first upper power limit PT. Additionally or alternatively, a measurement limit pair can also consist of the first upper voltage limit U1 ' and the first upper power limit P1 '.

[0050] The second threshold comprises several measured variables, which include a second upper current limit I2' and a second upper voltage limit U2' or a second upper power limit P2'. Accordingly, measurement limit pairs can consist of the second upper current limit I2' and the second upper voltage limit U2' or of the second upper current limit I2' and the second upper power limit P2'. Additionally or alternatively, a measurement limit pair can also consist of the second upper voltage limit U2' and the second upper power limit P2'.

[0051] The first upper current limit I1' is equal to or greater than the second upper current limit I2'. 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'.

[0052] Fig. 2 shows the power supply 10 with the device 20 for monitoring it. The device 20 comprises a first monitoring element 110 and a second monitoring element 120. The first monitoring element 110 in turn comprises a voltage divider which derives the signal S(U1) from the voltage U1. The first monitoring element 110 further comprises a current measuring device which is designed as a current measuring resistor (shunt). This derives the signal S(I1) from the current I1. The signals S(U1) and S(I1) are fed to the first comparator 115, which checks the individual threshold values ​​of the upper limits for current I1', voltage U1' and power P1'. If at least one individual threshold value is exceeded, the first comparator 115 signals to the primary-side control element 105 that the respective upper limit has been exceeded. Furthermore, the signalling may also include the extent of the excess and information on the course of the excess.In particular, the exceedance can only be signalled after a certain period of time has elapsed, as will be explained in detail later.

[0053] The second monitoring element 120, in turn, comprises a voltage divider that derives the signal S(U2) from the voltage U2. Furthermore, the second monitoring element 120 comprises a current measuring device designed as a current measuring resistor (shunt). This derives the signal S(I2) from the current I2. The signals S(U2) and S(I2) are fed to the second comparator 125, which checks the individual threshold values ​​of the upper limits for current I2', voltage U2', and power P2'. If at least one individual threshold value is exceeded, the second comparator 125 signals the primary-side control element 105 that the respective upper limit has been exceeded. As with the first comparator 115, the second comparator 125 can, in addition to the signaling, also include the extent of the exceedance and information about the course of the exceedance. In particular, the exceedance can only be signaled after a certain time has elapsed, as will be explained in more detail later.

[0054] The power supply 10 together with the device 20 comprises on the primary side a fuse F1, which is arranged on one input line of two input lines of two input terminals. It further comprises an EMC protection circuit (without reference symbol) arranged between the two input lines. It further comprises a rectifier circuit D1, which terminates the two input lines. It further comprises a capacitor C1 for smoothing the input voltage, which is connected to the two output lines of the rectifier circuit D1. The device 20 further comprises the proportional voltage converter 100 of the primary side, which is connected to the capacitor C1. Finally, the device 20 comprises the control element 105 and the switching element 220 connected thereto for switching the voltage converter 100 on the primary side. The control element 105 is further connected to the primary-side portion of the optocouplers OC1 and OC2.

[0055] On the secondary side, the power supply 10, together with the device 20, comprises the secondary side's proportional voltage converter 100, a diode D2 in one of the two lines of the secondary side's voltage converter 100, and a capacitor C2 arranged between the lines of the secondary side's voltage converter 100. Furthermore, the secondary side comprises an EMC filter (without reference symbol) at the output of the power supply U2 / 12. Finally, the secondary side also comprises the secondary side components of the optocouplers OC1 and OC2, which are connected to the comparators / control 115 and 125, respectively. On the primary side, the two optocouplers OC1 and OC2 control the power switch 220 by means of a corresponding conversion 105, e.g., by means of pulse width modulation or pulse frequency modulation.

[0056] Fig. 3 shows a power supply 10 with a device 20 for monitoring it, comprising the 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 the second current I2 and the second voltage U2 at a first supply output 190. The first output unit 180 comprises the second monitoring element 120. The second output unit 130 comprises a second supply output 140, which provides a third current I3 and a third voltage U3. The first monitoring element 110 is connected to the optocoupler OC1 230. It can additionally also be connected to the optocoupler OC2. The first monitoring element 110 signals the signals S(I1) and S(U1). The second monitoring element 120 is connected to the optocoupler OC2 240.The second monitoring element 120 signals the signals S(I2) and S(U2). The first output unit 180 and the second output unit 130 are supplied with the current I1 and the voltage U1 by the first monitoring element 110. In further embodiments, a plurality of second output units 130 can be arranged in parallel, each supplied with the current I1 and the voltage U1 by the first monitoring element 110. Furthermore, alternatively or additionally, a plurality of first output units 180 can also be arranged in parallel, each supplied with the current I1 and the voltage U1 by the first monitoring element 110.

[0057] Fig. 4 shows a power supply 10 with a device 20 for monitoring it, comprising a first output unit 180 and a second output unit 130. The first output unit 180 comprises a first switch 200 for switching off the first supply output 190. The first switch 200 is controlled by the second monitoring element 120 and interrupts the provision of the second current I2 and the second voltage U2 when the second threshold value is exceeded. The second monitoring element 120 further comprises the voltage divider for determining the signal S(U2) and the current measuring device, which is designed as a current measuring resistor (shunt), for determining the signal S(I2). The second monitoring element 120 further comprises the second comparator 125. The first output unit 180 comprises a display for signaling a threshold value exceedance in the form of an LED D4, which is controlled by the second comparator 125.

[0058] Furthermore, the power supply 10 with the device 20 comprises the electrical components of the primary side already known from Figure 2, in particular the EMC filter, the rectifier D1, the capacitor C1, the proportional voltage converter 100 of the primary side, the primary-side control element 105, the switching element 220, and the primary-side components of the optocouplers OC1 and OC2. On the secondary side, the power supply 10 with the device 20 shows, similar to Figure 2, the proportional voltage converter 100 of the secondary side, the diode D2, the capacitor C2, the EMC filter (without reference symbol) at the output of the first monitoring element 110, and the secondary-side components of the optocouplers OC1 and OC2. The connection of the components largely corresponds to that of Figure 2.

[0059] The second output unit 130 provides a third current I3 and a third voltage U3 at a second supply output 140. The second output unit 130 is supplied with the first current I1 and the first voltage U1 by the first monitoring element 110.

[0060] The second output unit 130 comprises a second switch 210 for switching off 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 is exceeded. Optionally, the second output unit 130 can comprise a voltage divider (not shown) for determining the signal S(U3), which is based on the voltage U3. Furthermore, the second output unit 130 can optionally comprise a current measuring device (not shown), which is designed as a current measuring resistor (shunt), for determining the signal S(I3). The second output unit 130 further comprises a display for signaling a threshold exceedance in the form of an LED D3, which is controlled by the second output unit 130.Further optionally, the second output unit 130 can electrically transmit the signals S(U3) and S(13) to the first comparator 115 of the first monitoring element 110 via a connecting line.

[0061] The first switch 200 is switched depending on whether the second threshold is exceeded. Signaling of the second threshold is optionally based on a malfunction of the first switch 200. This can be coupled with the signaling of the second threshold being exceeded or signaled separately. In addition to details of the second threshold being exceeded, the signaling can also contain information about the first switch 200 and its function, for example, the malfunction, and its position (open, closed). Disconnection of the first switch 200 is based on internal signals of the first output unit 180.

[0062] The second switch 210 is switched depending on whether a third threshold value is exceeded. Disconnection of the second switch 210 is based on internal signals from the second output unit 130. Optionally, signaling that the third threshold value has been exceeded can be based on a malfunction of the second switch 210. Further optionally, the second switch 210 can be controlled by the first comparator 115.

[0063] As shown in Figure 2, a 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 connected to them. The switching element 220 controls the voltage converter 100 on the primary side based on signals from the primary-side control element 105. The control influences the first current I1 and the first voltage U1. Alternatively, the control causes the first current I1 and the first voltage U1 to be switched off.

[0064] The signal-conducting connection to the primary-side control element 105 comprises an optical coupling element 230, 240. Alternatively, the coupling element 230, 240 can also contain an inductive and / or capacitive coupling. Optionally, the signal-conducting connection to the first monitoring element 110 can comprise a first coupling element 230, and the signal-conducting connection to the second monitoring element 120 can comprise a second coupling element 240. The first coupling element 230 and the second coupling element 230 can be arranged in parallel.

[0065] The monitoring elements 110, 120 are designed to monitor whether the threshold values ​​have been exceeded and to monitor the duration of the threshold value exceedance. Signaling of the threshold value exceedance can only occur after the specified duration has elapsed. The duration can be selected.

[0066] The thresholds can be user-adjustable. This includes the adjustability of the current limits IT, I2', I3', the voltage limits UT, U2', U3', and the power limits PT, P2', and P3'. This can optionally also include an individually adjustable duration for each threshold violation.

[0067] The power supply 10 complies with SELV (Safety Extra Low Voltage) requirements.

[0068] The voltage converter 100 of the power supply 10 may comprise a transformer or a switching power supply or a hard-switching forward or flyback converter or a resonant switching converter.

[0069] In other words, the invention can be summarized as follows: In a SELV extra-low-voltage power supply system with a direct voltage of < 60 volts DC (DC voltage), for example, 12 volts or 24 volts DC, the output power is limited to permanently less than 100 watts according to UL 1310 (Class II Power Unit) to increase safety. Likewise, the associated limiting mechanisms, such as voltage, current, and power limitation, must be redundant and thus implemented in duplicate.

[0070] Likewise, safety-oriented systems are subject to increased requirements regarding overvoltages and overcurrents. It should be noted that the highest voltage in a power system determines the system voltage, and components can only operate safely up to a certain voltage limit. If a current limit is exceeded, a failed load connected to the system can cause errors. This limitation has a significant impact on the connected components and the installation. For non-redundant power-limited power supplies, significant safety margins must be considered, for example, in the wiring, and / or they may only be installed by qualified personnel.

[0071] In the prior art, this redundant power limitation is achieved by small power supplies that do not allow a power throughput of 100 watts. The first power limitation consists of the natural power limitation of a power supply, which results from the maximum power limitation of the transformer 100. The second current limitation consists of the usually built-in current limitation. Both mechanisms limit the maximum power to a certain upper limit in a simple, fail-safe manner. However, due to the considerable inaccuracy of the limits, this requires a considerable margin from the maximum possible output power. Downstream fuses at an output of the power supply 10 also require a considerable safety margin, since they allow a significantly higher current than the nominal value of the fuse over a certain period of time, which also depends heavily on the ambient temperature.In summary, these methods typically allow a limitation to a maximum of two-thirds of the maximum possible output power. To get significantly closer to the power limit, some embodiments allow for power supplies that implement both voltage and current regulation (or voltage and current limitation) redundantly.

[0072] The previously outlined state-of-the-art solutions have the disadvantage that they either require a significant safety margin from the maximum output power or are implemented at increased cost due to redundant controls and / or limitations. Likewise, power limitation is only implemented in power supplies that only have this power limitation.

[0073] A solution for a flexibly redundant power-limited power supply is presented, which has one or more redundantly limited outputs 190 as well as one or more non-redundantly simply limited outputs 140. In the power supply 10 according to the invention, the output voltage U1 is regulated and the current of an output 11 is simply detected and limited. Any number of modules 180 are connected downstream of this, which have an additional voltage and current regulation / limitation 120 with a voltage / current regulator / limiter 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 respective output voltage and output current to the upstream power supply 110. The total output current of all unfused outputs 140 for I3 is also detected.Power supply 10 calculates the current through each redundantly limited output from total current 11 minus current I3 of all unprotected outputs and current I2, as well as any additional redundantly limited outputs. If the output current of a redundantly protected output exceeds the limit, the limit in module 180 is the first mechanism to shut it down. For redundancy, however, power supply 10 can also stop supplying this output and thereby shut it down, or additionally shut down the entire output voltages U2 and U3.

[0074] The complete shutdown of power supply 10 is particularly important if, for example, the redundantly secured output 190 supplies sensors via wiring with the then permitted small cross-section. If these sensors fail, it is advantageous to shut down the entire system, for example, to prevent unmonitored operation of the connected load.

[0075] The 180 modules for voltage and current regulation (or limiting) can be powered via an additional connection independently of the measured output current of the power supply or by the measured output current. In the latter case, the current consumption of the 180 limiting modules is either taken into account in the calculation or, if the current consumption is significantly lower than the limiting, it can be neglected.

[0076] This makes it possible to implement a modular power supply system that provides significantly higher overall output power and also enables redundant single-fail-safe outputs 180 for wiring with small cross-sections. The power supply system presented here can be implemented, for example, in a power supply. The individual output channels can be implemented with various switchable current limits.

[0077] A power supply 10 consists of the input and the simple voltage and current regulated output 140 shown here, as well as the redundantly regulated output 190. The power supply 10 has a primary-side circuit section and a secondary-side circuit section. The energy from the input side is transferred to the secondary side via a transformer TR1. The power supply can be designed either as a galvanically isolated switched-mode power supply with galvanic isolation or not. The voltage and current regulators U1 and 11 of the power supply 10 record the output variables on the secondary side and report any errors via the optocoupler OC1 back to the primary side, where the primary-side power path is controlled accordingly. Likewise, the first output variables U1 and 11 can also be controlled on the primary side, particularly with a fixed input voltage. Likewise, the described design is independent of the type of switched-mode power supply.This can be implemented in any way, for example, hard-switching as a forward or flyback converter, or resonantly switching, such as an LLC. Capacitive power transmission is also possible instead of inductive power transmission. The feedback implementation is also intended to illustrate only one principle; other methods such as inductive feedback are also possible. The power switch(es) 200, 210 can also be controlled on the primary or secondary side.

[0078] The only important thing is that there is a first control of the output variables U1 and U1 for the simply controlled output 140.

[0079] In a first downstream module 130, the first outputs 140 of the switched-mode power supply 10 are supplied from the secondary-side power path as single-fused outputs 140. A further module 180 redundantly monitors the outputs with single-fault protection using the voltage and current limiting signals S(U2) and S(I2). If one of these signals, S(U2) or S(I2), indicates that the limit value has been exceeded, at least output 190 is switched off via switch S1. Likewise, the entire power supply 10 is switched off in this fault event, or another switch upstream of the output module 180 switches it off. If the calculation of the total current 11 minus the current through the one or more unfused outputs 13 results in the redundant single-fault-safe output current being exceeded, switch S1 is also opened, and the redundantly controlled output 190 is switched off.

[0080] The output modules 180 and / or 130 can be built-in or designed as plug-in modules. They can also signal the user separately via LEDs D3 and D4 when the current limit is exceeded. Furthermore, the respective output can be automatically shut down if the output current is exceeded. Likewise, the output configuration can be fixed or adjustable via switches or an interface.

[0081] Important here are the two types of outputs 190 and 140 in a power supply. The single-fault-safe outputs 140 consist of simple monitoring and / or control (e.g., regulation) of the output voltage and output current U3 and I3. In contrast, the single-fault-safe output(s) 190 each have fully redundant monitoring and / or control (e.g., regulation) with two separate voltage and current measurements U1 and U2 or I1 and I2, separate controls (e.g., regulation) and separate feedback OC1 and OC2, as well as optionally separate intervention options on the primary side.

[0082] Fig. 5 illustrates a method 300 for monitoring a safety extra-low voltage power supply. The method comprises monitoring 310, with a first monitoring element, a first current, I1, and a first voltage, U1, which are output on the secondary side by a voltage converter. The method further comprises controlling 320 the voltage converter on the primary side with a primary-side control element that is signal-conductingly connected to the first monitoring element, based on the first current, I1, and the first voltage, U1, when a first threshold value is exceeded. The method further comprises monitoring 330, with a second monitoring element, 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 is supplied with the first current, I1, and the first voltage, U1, by the first monitoring element. Furthermore, the method includes controlling 340 the voltage converter on the primary side based on the second current, I2, and the second voltage, U2, when a second threshold is exceeded, wherein the primary-side control element is signal-conductively connected to the second monitoring element.

[0083] In this case, the method 300 for controlling a switching power supply with at least two output voltages can comprise a first control which generates a first output voltage U1, 11 and which is output as a third output voltage U3, I3, and a second output voltage U2, I2 which is supplied from the first output voltage U1, 11 and is output as a second output voltage U2, I2.

[0084] 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 fed back to the primary side as the first signal. The second output voltage U2, I2 includes its own independent second control circuit, which has a second independent feedback circuit to the primary side and enables double, single-fault-safe control of the second output voltage U2, I2.

[0085] In some embodiments, the output voltage of the outputs U2 and U3 can be adjustable. In other embodiments, the output current can be individually adjustable for each output. The output power can be individually adjustable for each output. Furthermore, a current or

[0086] Power overshoot up to a certain limit and for a maximum time can be individually adjustable for each output. In addition, a behavior when the limit values ​​are exceeded can be adjusted, wherein in exemplary embodiments the entire power supply can be switched off or wherein the respective output exceeding the limit value can be switched off. In addition, the setting of the limit values ​​and / or the states of the outputs or signaling can be carried out both on the power supply and via an interface with a controller. Furthermore, further output voltages can be generated and regulated singly or doubly according to the described method. Although the invention has been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes can be made and equivalents can be used as substitutes.Furthermore, many modifications may be made to adapt a particular situation or user to the teachings of the invention. Consequently, the invention is not limited to the disclosed embodiments, but encompasses all embodiments falling within the scope of the appended claims.

[0087] Reference symbol

[0088] Power supply

[0089] Device for monitoring the power supply

[0090] Voltage converter of an input voltage

[0091] Primary-side control element

[0092] First monitoring element for U1 and 11

[0093] First comparator

[0094] Second monitoring element U2 and I2

[0095] Second comparator

[0096] Second output unit

[0097] Second supply output

[0098] First output unit (e.g. module)

[0099] First supply exit

[0100] First switch

[0101] Second switch

[0102] switching element

[0103] First coupling element

[0104] Second coupling element

[0105] Method for monitoring a power supply

[0106] Monitoring with first monitoring element

[0107] Primary-side control with primary-side control element

[0108] Monitoring with a second monitoring element

[0109] Primary-side control of the voltage converter

Claims

Claims 1 . Device (20) for monitoring a power supply (10) for Safety extra-low voltage, comprising: a first monitoring element (110) 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) connected to the first monitoring element (110) in a signal-conducting manner and 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, and a second monitoring element (120) 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, wherein the second monitoring element (120) is supplied from the first monitoring element (110) with the first current, I1, and the first voltage, U1 ,wherein 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 the second current, I2, and the second voltage, U2, when a second threshold value is exceeded.

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

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

4. The power supply monitoring device (20) of claim 3, wherein the first output unit (180) comprises a first switch (200) for switching off the first supply output (190).

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

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

7. Device (20) according to one of claims 4 to 6, wherein the first switch (200) is switched as a function of the second threshold value being exceeded, and / or wherein the second switch (210) is switched as a function of a third threshold value being exceeded, and / or wherein a signaling of the second threshold value is based on a malfunction of the first switch (200) and / or wherein optionally a signaling of the third threshold value is based on a malfunction of the second switch (210).

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

9. Device (20) according to one of the preceding claims, wherein a 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, wherein the switching element (220) controls the voltage converter (100) on the primary side based on signals from the primary-side control element (105), wherein the control effects an influence on the first current, I1, and the first voltage, U1, or wherein the control effects a switching off of the first current, I1, and a switching off of the first voltage, U1.

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

11. Device (20) for monitoring the power supply according to one of the preceding claims, wherein the monitoring elements (110, 120) are designed to monitor an exceedance of the threshold values ​​and a duration of the threshold value exceedance, wherein a signaling of the threshold value exceedance only takes place after the expiration of the predetermined duration.

12. Device (20) for monitoring the power supply according to one of the preceding claims, wherein the threshold values ​​can be set by a user and / or wherein the setting of the threshold values ​​comprises a respectively adjustable duration of the threshold value exceedance.

13. Power supply (10) for safety extra-low voltage (10), wherein the power supply complies with the extra-low voltage requirements, SELV, according to one of the preceding claims.

14. Power supply (10) for safety extra-low voltage (10) according to claim 13, wherein the voltage converter (100) comprises a transformer or a switching power supply or a hard-switching forward or flyback converter or a resonant switching converter.

15. A method (300) for monitoring a safety extra-low voltage power supply (10), comprising: Monitoring (310), with a first monitoring element (110), a first current, U1, and a first voltage, U1, which are output on the secondary side by a voltage converter (100), primary-side controlling (320) the voltage converter (100) with a primary-side control element (105) that is signal-conductingly connected to the first monitoring element (110), based on the first current, U1, and the first voltage, U1, when a first threshold value is exceeded, Monitoring (330), with a second monitoring element (120), 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, from the first monitoring element (110), controlling (340) 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, wherein the primary-side control element (105) is connected to the second monitoring element (120) in a signal-conducting manner.

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