RELAY MODULE

Description

[0001] The invention relates to a relay module. In particular, but not limited thereto, the invention relates to an AC-powered relay module with an adjustable and low-hysteresis switching threshold.

[0002] Document DE 10 2007 006830 A1 describes a series of I / O modules and a plug-in control and / or data transmission module.

[0003] Document EP 3 185 272 A1 describes a built-in device for a bistable relay with control via an H-bridge.

[0004] Document WO 2015 / 017882 A1 describes an electrical relay driver arrangement for charging and discharging an electrical coil of an electromechanical relay, wherein the drive arrangement is intended to charge a capacitor arrangement with a resistor at defined intervals at the zero crossing of an AC voltage supply.

[0005] Document US 5 811 963 A describes a control circuit, such as a motion detector, that is permanently powered even when the power source is switched off. It includes an energy storage device.

[0006] Existing relay modules on the market include a low-pass filter on the input side, for example, an RC circuit. Since such relay modules are powered directly by the alternating current (AC) of the control signal, the low-pass filter is specifically used to suppress interference from the AC mains supply on the control side. However, due to the physical properties of the relay coil, such as the ferromagnetic state of the core, these modules have a relatively wide opening and closing voltage range. The advantage of lower current consumption compared to conventional contactors is also a disadvantage in this regard. For example, with a nominal control voltage of 230 V AC, the opening and closing voltage range can vary between 170 V opening and 40 V closing, depending on the relay coil. Voltage and current specifications for AC can refer to the respective RMS value or the root mean square (RMS) value.

[0007] Switching other motors and contactors often generates high interference voltages and currents. Even with separate AC networks, these can couple into the control lines of the relay module due to long cable lengths.

[0008] Interference voltages and currents in the control line can lead to unintended switching or delayed release of the relay coil. Furthermore, a status indicator, particularly a low-current light-emitting diode (LED), may illuminate even though the relay coil has not yet switched. This indicator and switching behavior is misleading and therefore undesirable.

[0009] To mitigate these undesirable characteristics of conventional relay modules, a filter, such as an RC circuit, is often connected in parallel to the input. This filter is intended to compensate for interference and ensure reliable switching on and off of the relay module. In some systems, particularly in power plant technology, this type of filter is insufficient, so malfunctions of relay modules still occur.

[0010] The invention aims to remedy this situation. In particular, the invention can be based on the objective of providing a relay module with an adjustable and / or low-hysteresis switching threshold.

[0011] The problem is solved according to the invention by the features of the independent claim. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0012] Further features and advantages of exemplary embodiments of the invention are described below with partial reference to the drawings.

[0013] According to the invention, a relay module comprises a control input which is supplied or can be supplied with alternating voltage for the combined control and power supply of the relay module. The relay module further comprises a fixed voltage regulator configured to generate a fixed voltage after rectification of the alternating voltage or a portion thereof. The relay module further comprises a comparator configured to be driven by the fixed voltage and to compare a reference voltage derived from the fixed voltage with a rectified and smoothed portion of the alternating voltage. The relay module further comprises a switching stage configured to operate a relay unit depending on the comparator's comparison. The relay module further comprises a relay unit that is connected on its input side to the switching stage and on its output side to switching terminals of the relay module.

[0014] Examples of relay module implementations can, based on the comparator's comparison, unambiguously control whether the switching stage operates the relay unit or not. Since the reference voltage for the comparison is derived from the fixed voltage, the switching threshold at the control input can be state-independent and / or have low hysteresis. Because the comparator is powered by the fixed voltage, these or other embodiments of the relay module can operate without a separate or permanent power supply.

[0015] The alternating voltage can be mains voltage. The alternating voltage can be 110 V AC to 230 V AC. Alternatively, or in combination, the fixed voltage can be 5 V DC to 12 V DC.

[0016] The derived reference voltage can be a fixed fraction of the fixed voltage. The relay module, in particular the comparator, can include a voltage divider configured to derive the reference voltage as a fixed fraction from the fixed voltage.

[0017] The relay module may also include a rectifier upstream of the fixed voltage regulator. The rectifier may be a bridge rectifier for rectifying the AC voltage or a portion thereof.

[0018] The switching stage can switch a coil circuit of the relay unit that is supplied by the rectifier. Depending on the comparison, the switching stage can be configured to selectively connect the negative terminal of the rectifier to the relay unit and disconnect it from the relay unit. A status indicator, preferably connected in series with the relay unit, can be connected in the coil circuit.

[0019] A reactance, preferably a capacitive reactance, can be arranged between the control input and the rectifier (connected upstream of the fixed voltage regulator), which generates the portion of the AC voltage used for rectification. A large portion, preferably more than half or more than 75%, of the AC voltage can drop across the reactance.

[0020] The comparator can include an operational amplifier to perform the comparison. The rectified and smoothed portion of the AC voltage and the reference voltage can be applied to the inputs of the operational amplifier. A control voltage for the switching stage can be generated by the operational amplifier.

[0021] The comparator can further be configured to generate the rectified and smoothed portion of the AC voltage for comparison with the reference voltage independently of the rectifier upstream of the fixed voltage regulator. For example, the comparator can comprise a half-wave rectifier with a smoothing capacitor. The AC voltage, or a portion thereof, can be applied as the input voltage to the half-wave rectifier. The half-wave rectifier can be configured to generate a smoothed DC voltage for the rectified and smoothed portion of the AC voltage in the comparator.

[0022] The comparator may also include a voltage divider. The smoothed DC voltage from the half-wave rectifier may be applied to the voltage divider of the comparator. The voltage divider of the comparator may be configured to generate a portion of the smoothed DC voltage that is equal to the rectified and smoothed portion of the AC voltage in the comparator.

[0023] The voltage divider can be controlled, for example, by means of a potentiometer. This allows the rectified and smoothed portion of the AC voltage used for comparison to be adjusted. In particular, this allows the switching threshold at the control input to be controlled. For example, the switching threshold can be manually adjusted on the relay module.

[0024] The comparator's input voltage can be tapped between the control input and the rectifier (connected upstream of the fixed voltage regulator). The comparator can tap the input voltage before the reactance (for example, via megaohm resistors in the comparator) or after the reactance (for example, with correspondingly smaller series resistors in the comparator).

[0025] The relay module can be housed in an enclosed enclosure. The enclosure may be enclosed due to the low power dissipation of the relay module, for example, because the relay module's circuit elements are only energized when the relay unit is operating and / or the dead man's switch reduces the AC voltage level with virtually no loss.

[0026] The housing may have externally accessible terminals for the switching connections. The housing may be designed for mounting on a mounting rail, in particular a DIN rail. The control input may also be wired via externally accessible terminals on the housing. Alternatively or additionally, the control input and / or the switching connections may have plug-in contacts on the housing, arranged to connect to busbars extending parallel to the mounting rail.

[0027] The housing may have an externally accessible slot for the interchangeable mechanical and electrical connection of the relay unit. This allows the relay module to be adapted to different switching capacities, switching voltages, switching currents, and / or relay functions by inserting or replacing the relay unit. For example, one relay unit can be used for an impulse relay and / or for more than two states.

[0028] The invention is explained in more detail below with reference to the drawings and a preferred embodiment.

[0029] They show: Fig. 1 is a schematic representation of a block diagram of a relay module according to a first embodiment of the invention; Fig. 2 is an exemplary diagram of the switching behavior of a relay module according to a second embodiment of the invention; Fig. 3 is a schematic circuit diagram of a relay module according to a third embodiment of the invention; and Fig. 4 is an exemplary perspective view of a relay module according to a fourth embodiment of the invention.

[0030] Fig. 1 shows a schematic representation of a block diagram of a first embodiment of a relay module generally designated by reference numeral 100.

[0031] The relay module 100 includes a control input 102, which is supplied with, or can be supplied with, alternating current (AC) for the combined control and power supply of the relay module 100. A fixed voltage regulator 114 of the relay module 100 generates a fixed voltage 116 after rectifying the AC voltage or a portion thereof. A comparator 120 of the relay module 100 is operated by the fixed voltage 116 as its supply voltage. The comparator 120 compares a reference voltage 118 derived from the fixed voltage 116 with a rectified and smoothed portion of the AC voltage applied to the control input 102. Depending on the comparison of the comparator 120, a switching stage 124 of the relay module 100 operates a relay unit 126 of the relay module 100. The relay unit 126 is connected on the input side to the switching stage 124 and on the output side to switching terminals of the relay module 100.

[0032] The first embodiment of the relay module 100 comprises the AC control input 102, the fixed voltage regulator 114, the comparator 120, the switching stage 124 and the relay unit 126. The relay unit 126 can also be referred to simply as the relay.

[0033] The relay unit 126 can comprise a mechanical relay. The switching stage 124 operates an electromagnet of the relay unit 126 according to the comparator 120. The current switched by the switching stage 124 flows in an excitation coil of the electromagnet of the relay unit 126 and generates a magnetic flux through a ferromagnetic core of the electromagnet. In one variant of the first embodiment, a movable armature (for example, also ferromagnetic) opens and / or closes the switching terminals of the relay module 100 in a switching position. Without current in the excitation coil, the armature returns from the switching position to an initial position by a spring force.

[0034] While voltage thresholds and / or current thresholds in the excitation coil can differ significantly for switching and dropping the armature, for example due to the ferromagnetic core, the switching stage 124 is configured to control the relay unit 126 either to switch or to drop the armature, according to the comparator 120. This reduces or at least substantially avoids hysteresis or deviation between the switching voltage and the drop-out voltage at the AC control input 102.

[0035] Preferably, the first embodiment of the relay module 100 further comprises a rectifier 110 between the AC control input 102 and the fixed voltage regulator 114 for rectifying the AC voltage or a portion thereof applied to the AC control input 102. The DC voltage 112 of the rectifier 110 (for example, a portion of the AC voltage rectified by the rectifier 110) supplies the fixed voltage regulator 114. Alternatively or additionally, the switching stage 124, according to the comparator 120, switches the DC voltage 112 generated by the rectifier 110 to operate the relay unit 126. For this purpose, a control voltage 122 output by the comparator 120 to the switching stage 124 corresponds to the result of the comparator 120's comparison.

[0036] Optionally, the first embodiment of the relay module 100 further includes a capacitive reactance 108 between the AC control input 102 and the rectifier 110. The capacitive reactance 108 is designed to adapt the voltage level of the AC voltage to the voltage level of the rectifier 110 or the fixed voltage regulator 114. For this purpose, a large portion of the AC voltage level drops across the capacitive reactance 108. Due to a dominant reactive power, the voltage drop across the capacitive reactance 108 is essentially without heat loss.

[0037] The low or virtually non-existent heat loss improves the energy efficiency of the Relay Module 100 and / or enables a compact design, for example, in a narrow housing and / or a housing without ventilation openings. A narrow housing width for the Relay Module 100 is particularly advantageous for housings intended for mounting on a DIN rail, such as a top-mounted rail. For example, the narrower width allows more modules to be mounted on the same DIN rail.

[0038] An input voltage 106, corresponding to or derived from the AC control input 102, is applied to the comparator 120. From the input voltage 106, the comparator generates the rectified and smoothed component of the AC voltage applied to the AC control input 102 for comparison with the reference voltage 118.

[0039] Since the reference voltage 118 is subject to the fixed voltage regulator 114 (i.e., derived from the fixed voltage 116) and the input voltage 106 is not subject to the fixed voltage regulator 114 (e.g., is linear from the AC voltage applied to the AC control input 102), the comparison of the comparator 120 can detect absolute changes in the AC voltage applied to the AC control input 102.

[0040] The input voltage 106 can be tapped directly at the AC control input 102 or between the AC control input 102 and the capacitive reactance 108.

[0041] Optionally, the first embodiment of the relay module 100 includes an RC filter 104 between the AC control input 102 and the capacitive reactance 108. The RC filter can filter out voltage fluctuations, for example, those that are shorter in time than an application-dependent switching rhythm of the relay module 100, preferably also if the voltage fluctuations exceed or fall below the uniform switching threshold of the relay module.

[0042] The input voltage 106 is preferably tapped off after the RC filter 104 and before the rectifier 110, for example before the capacitive reactance 108.

[0043] Fig. 2Figure 1 shows an exemplary diagram of the switching behavior of relay module 100 according to a second embodiment of the invention. The second embodiment can be implemented with one or all features of the independent claim and / or the first embodiment. Features that are identical to or interchangeable with those of the first embodiment are described in the second embodiment with the same reference numerals.

[0044] Diagram 200 illustrates how small the hysteresis can be due to the second embodiment of the relay module 100, for example, due to the fixed voltage regulator 114 in conjunction with the comparator 120 for controlling the switching stage 124 (also referred to as the comparator circuit). Here, the hysteresis refers to the difference between the switching voltage and the drop-out voltage (i.e., the voltage threshold for switching or dropping out of the relay unit 126) at the AC control input 102. The hysteresis is small in the sense that the difference is small compared to the switching voltage, for example, less than 10% or less than 1%.

[0045] Diagram 200 shows a time course (with the time scale on the horizontal axis). Voltages are plotted vertically. The AC voltage at the AC control input 102 is plotted on the right vertical axis. Input and output DC voltages for comparison in the comparator 120 are plotted on the left vertical axis and are labeled VIN and VOUT in Diagram 200.

[0046] The input DC voltage VIN is an example of the rectified and smoothed component 204 of the AC voltage 202 when compared with the reference voltage 118 in the comparator 120. For example, the input DC voltage 204 depends linearly on the AC voltage 202 applied to the AC control input 102, so that the left scale in diagram 200 for the input DC voltage 204 for the comparison in the comparator 120 corresponds to a corresponding value of the AC voltage 202 at the AC control input 102 on the right scale in diagram 200.

[0047] The comparator 120 compares the input DC voltage 204 with the reference voltage 118. The result is the output DC voltage (V OUT), which is an example of the control voltage 122. The control voltage 122 is a logic level that uniquely defines the switching (i.e., an operating state) of the relay unit 126 and the dropping out (i.e., a currentless state) of the relay unit 126.

[0048] The difference between the switching reference voltage 118 (i.e., the reference voltage starting from the no-current state) and the falling reference voltage 118' (i.e., the reference voltage starting from the operating state) is small compared to the reference voltage 118. For example, the difference is 0.2 V at a reference voltage 118 of 3.9 V, or 5% of the reference voltage 118. Due to the linear relationship between the AC voltage 202 and the rectified and smoothed component 204 of the AC voltage 202, the hysteresis at the AC control input 102 is also only 5%.

[0049] Fig. 3Figure 1 shows a schematic circuit diagram of relay module 100 according to a third embodiment of the invention. The third embodiment can be implemented with one or all features of the independent claim, the first and / or the second embodiment. Features that are identical to or interchangeable with those of the first or second embodiment are described in the third embodiment with the same reference numerals.

[0050] For the selective control of the relay module 100, an AC voltage 202 (e.g., 230 V AC) is applied as control voltage 202 to the terminals 302 of the control input (with contacts A1 and A2) of an AC control input 102. A varistor 306 connected in parallel to the terminals 302 in the AC control input 102 serves as overvoltage protection. A capacitive reactance 108 serves for voltage reduction.

[0051] The reduced AC voltage, i.e., the portion of the AC voltage 202 applied after the capacitive reactance 108, is rectified by a rectifier 110. The rectifier 110 comprises a bridge rectifier 308 with a smoothing capacitor 310.

[0052] A fixed voltage regulator 114 comprises a voltage regulator 312 (for example, a low-dropout voltage regulator) upstream of which a normally conducting (i.e., self-conducting) field-effect transistor 314 (for example, a depletion-mode MOSFET) is connected. The voltage regulator 312 generates a fixed voltage 116, which serves as the supply voltage and also partially as the reference voltage 118 for a comparator 120. The comparator 120 can also be referred to as a control stage.

[0053] The high input voltage range (e.g., 110 V DC) is achieved via the self-conducting MOSFET 314 in conjunction with the low-dropout voltage regulator 312. Since the required current (e.g., 1 mA) for the comparator 120 and the control of the switching stage 124 is very low, only very small power losses occur there.

[0054] The comparator 120 compares the reference voltage 118 with a rectified and smoothed component 204 of the AC voltage (i.e., the input DC voltage), which is derived from the input voltage 106 (for example, before or after an RC filter 104). The input voltage 106 is rectified by a half-wave rectifier 316 and smoothed by a further smoothing capacitor 318. The rectified and smoothed component 204 of the AC voltage 202 is adjustable via a voltage divider 320. Since the rectified and smoothed component 204 is the input DC voltage for comparison with the reference voltage 118, the (essentially uniform) threshold value (also: switching threshold) of the AC voltage 202 for switching and de-energizing the relay unit 126 can be set by means of the adjustable voltage divider 320.

[0055] When the reference voltage 118 is exceeded, the comparator 120 switches the switching stage 124 and thus operates the relay unit 126. The switching threshold can be determined (for example, depending on the specification) by changing the voltage divider 320 (e.g., by adjusting a potentiometer 322).

[0056] This ensures that the relay has a fixed (i.e., essentially uniform) switching-on and switching-off threshold. Furthermore, a status indicator 125 (e.g., a light-emitting diode, LED) only illuminates when the relay unit 126 is switched on.

[0057] This prevents unwanted relay switching, delayed relay release, and / or incorrect status indication. Furthermore, an additional (especially separate, continuous) supply voltage for relay module 100 is not required.

[0058] The circuit diagram of Fig. 3The voltages and currents shown are examples. For instance, with a 230V AC AC input 202, a corresponding input voltage 106 can be present at the AC control input 102. The current distribution can be as follows: Approximately 6 mA flows in the RC circuit 104. Approximately 4 mA flows in the excitation coil (i.e., the relay coil) when switched. The other circuit components require approximately 2 mA. Thus, the current consumption is low.

[0059] Due to the reactance 108 and the low current consumption of the other circuit components (especially the comparator 120), the power loss is therefore very low.

[0060] Fig. 4Figure 1 shows an exemplary perspective view of a relay module according to a fourth embodiment of the invention. The fourth embodiment can be implemented with one or all features of the independent claim, the first, second, and / or third embodiment. Features that are identical or interchangeable with those of another embodiment are described in the fourth embodiment with the same reference numerals.

[0061] Due to the capacitive reactance 108 at the input and the low current consumption of the comparator 120, only very low power losses occur in a closed housing 400. The housing 400 can, for example, contain a relay module (e.g., according to Fig. 4 ), preferably with a width of 14 mm.

[0062] The fourth embodiment can thus correspond to the existing physical conditions, particularly in the relay module, without an additional external supply voltage (i.e., without additional terminals, etc.). Each of the embodiments can realize a cost-effective, low-power, and space-saving relay module 100 with a uniform (i.e., low-hysteresis) and / or adjustable switching threshold.

[0063] Alternatively or additionally, the housing 400 can have a slot 402 for the interchangeable installation of the relay unit 126. When installed, the relay unit 126 can be flush with the housing. A pre-tensioned, longitudinally movable slider can secure the relay unit 126 in slot 402. Reference symbol list

[0064] Relay module 100 Tax input 102 RC filter 104 Input voltage 106 Capacitive reactance 108 rectifier 110 DC voltage 112 Fixed voltage regulator 114 Fixed voltage 116 Reference voltage 118 Comparator 120 Control voltage 122 Switching stage 124 Status indicator 125 Relay unit 126 diagram 200 AC voltage at the control input 202 Rectified and smoothed component of the alternating voltage 204 Control input connections 302 Switching connections 304 Varistor 306 Bridge rectifier 308 smoothing capacitor 310 Voltage regulator 312 Self-conducting field-effect transistor 314 Half-wave rectifier 316 Additional smoothing capacitor 318 voltage divider 320 Potentiometer 322 Housing 400 slot 402

Claims

1. A relay module (100), comprising: - a control input (102) to which an alternating voltage (202) is applied, or which is configured for said application, for the combined control and power supply of the relay module (100); - a fixed voltage regulator (114) which is configured to generate a fixed voltage (116) after rectification of the alternating voltage (202) or a portion of the alternating voltage (202); - a comparator (120) which is configured to be operated by the fixed voltage (116) and to compare a reference voltage (118) derived from the fixed voltage (116) with a rectified and smoothed portion (204) of the alternating voltage (202); - a switching stage (124) which is configured to operate a relay unit (126) depending on the comparison of the comparator (120); and - a relay unit (126) which is connected on the input side to the switching stage (124) and on the output side to switching connections (304) of the relay module (100).

2. The relay module (100) according to claim 1, wherein the derived reference voltage (118) is a fixed portion of the fixed voltage (116).

3. The relay module (100) according to claim 1 or 2, further comprising: - a rectifier (110) connected upstream of the fixed voltage regulator (114) with a bridge rectifier (308) for rectifying the alternating voltage (202) or a portion of the alternating voltage (202).

4. The relay module (100) according to claim 3, wherein the switching stage (124) switches a coil circuit of the relay unit (126) fed by the rectifier (110).

5. The relay module (100) according to claim 4, wherein a status indicator (125) is connected in series with the relay unit (126) in the coil circuit.

6. The relay module (100) according to one of claims 3 to 5, wherein a capacitive reactance (108) is arranged between the control input (102) and the rectifier (110), which generates the portion of the alternating voltage (202) for rectification.

7. The relay module (100) according to claim 6, wherein a large part, preferably more than half or more than 75%, of the alternating voltage (202) drops at the capacitive reactance (108).

8. The relay module (100) according to one of claims 3 to 7, wherein the comparator (120) is configured to generate the rectified and smoothed portion (204) of the alternating voltage (202) for comparison with the reference voltage independently of the rectifier (110) connected upstream of the fixed voltage regulator (114).

9. The relay module (100) according to one of claims 1 to 8, wherein the comparator (120) comprises a half-wave rectifier (316) with a smoothing capacitor (318), to which the alternating voltage (202) or a portion of the alternating voltage (202) is applied as an input voltage (106) and which is configured to generate a smoothed direct voltage for the rectified and smoothed portion (204) of the alternating voltage (202) in the comparator (120).

10. The relay module (100) according to claim 9, wherein the comparator (120) further comprises a voltage divider (320) to which the smoothed DC voltage of the half-wave rectifier (316) is applied and which is configured to generate a portion of the smoothed DC voltage as the rectified and smoothed portion (204) of the alternating voltage (202) in the comparator (120).

11. The relay module (100) according to claim 10, wherein the voltage divider (320) is controllable by means of a potentiometer (322).

12. The relay module (100) according to one of claims 9 to 11 and one of claims 3 to 8, wherein the input voltage (106) of the comparator (120) is tapped between the control input (102) and the rectifier (110) connected upstream of the fixed voltage regulator (114), preferably upstream of the capacitive reactance (108).

13. The relay module (100) according to one of claims 1 to 12, wherein the relay module (100) is arranged in a closed housing (400).

14. The relay module (100) according to claim 13, wherein terminals of the switching connections (304) that are accessible from the outside are arranged on the housing (400), and the housing (400) is designed for fastening to a support rail, in particular a top hat rail.

15. The relay module (100) according to claim 13 or 14, wherein the housing (400) has an externally accessible slot (402) for the exchangeable mechanical and electrical connection of the relay unit (126) to the relay module (100).