System and method for fast and low noise relay switching operation

Abstract

A hybrid relay (1) comprises an electromechanical part (10) having a movable contact (103), a solid-state relay (11) and a control unit (2) for applying a drive signal (S', S") to a drivable coil (101) of the electromechanical part. A method for operating the hybrid relay comprises the steps of determining a first minimum voltage (V1) value of the drive signal, above which the movable contact (103) starts to move away from an open position (P o ); and a step of determining a second minimum voltage (V2) value of the drive signal, above which the movable contact (103) reaches a closed position (P c ); and a step of shaping the waveform (W) of the drive signal, the waveform comprising a portion (W1) consisting of a vertical segment jumping from zero to the first minimum voltage value, a portion (W2) in which the voltage gradually increases from the first minimum voltage value to the second minimum voltage value, and a portion (W3) consisting of a vertical segment jumping from the second minimum voltage value to the upper voltage boundary (V sup ) is composed of another vertical segment (W3).

Description

Technical Field

[0001] The present invention relates to the field of electrical relays, and in particular to hybrid relays. Background Art

[0002] Switching electrical loads up to tens of amperes (eg, 5-20 A) can be performed using two different relay technologies (electromechanical or semiconductor-based). Each of them has advantages and disadvantages.

[0003] Electromechanical relays are acoustically noisy due to the sound produced by the mechanical impact of the metal moving contacts. Generally the higher the power ratio, the noisier the relay. In addition, the relay is subject to arcing, so the number of commutations during its service life is limited, usually averaging about 10 4 – 50.000 times. But as an advantage, the dissipated energy (electrical energy and therefore thermal energy) is very small.

[0004] In order to reduce the switching noise of such an electromechanical relay, US7116541 proposes the use of a drive unit comprising an optocoupler for applying a supply voltage to a drivable coil, wherein a first minimum value of the supply voltage sufficient to move the switch contacts and a second minimum value of the supply voltage at which the switch contacts come into contact with each other are defined. The supply voltage increases linearly from the first minimum value to the second minimum value. Although this solution should reduce the noise level by 4 orders of magnitude (about 6 dB) mainly by avoiding the switch contacts from bouncing against each other, it does not ensure that the resulting switching noise is substantially excluded from the audible range; moreover, on the other hand, it generates an irreducible time delay caused by a timer of the drive unit, which is in the form of a capacitor, which determines the time in which the supply voltage can be increased from the first minimum value to the second minimum value.

[0005] The second type of relay made of semiconductors is the so-called solid-state relay (SSR). They have the advantage of providing an almost unlimited number of commutations and that they are completely silent. However, they have significant heat dissipation, which reduces the use cases for which they are suitable. As a simple example, with today's available technology, in order to support a standard 16A contact, a heat sink as large as a 10-inch laptop is required. Furthermore, for a 16A load, the energy dissipated is of the order of about 20-25W.

[0006] Hybrid relays are also known that combine the features of an electromechanical relay and a TRIAC (standing for Triode Alternating Current) solid-state relay (SSR). In such relays, the TRIAC / SSR is used only during the entire commutation phase of the relay, with the aim of increasing its service life. Tests performed on hybrid relays have shown that after 10 million switching operations, the device will still function normally and the electrical contacts of the electromechanical relay will still remain intact.

[0007] However, although the service life of such hybrid relay devices is significantly increased, one problem that still needs to be solved is how to switch them silently, ie without generating hardly any audible noise.

[0008] A first option for solving this problem is to make the electrical contacts of the relay move more slowly, thereby reducing the switching noise generated. Slow movement is achieved by providing a slowly increasing amount of voltage or current to the coil of the relay.

[0009] A negative side effect of the slower movement of the contacts is that the total switching operation takes longer. This is not a big problem when switching on the relay (i.e. moving from "OFF" to "ON"), because the presence of the TRIAC, which is intended to increase the service life, will then immediately close the contacts, while the contacts of the relay travel slowly, causing no side effects but heating thereof. Therefore, the only limitation to making the relay work in such a configuration is that the TRIAC has sufficient dissipation capacity to withstand the current for the time required for the contacts of the relay to close slowly. The slow travel time considered here is of the order of 5 to 10 seconds.

[0010] Switching off the relay (i.e. moving from "on" to "off") is more critical in terms of delay, since this must still be done while keeping the contacts of the TRIAC closed, which means that the TRIAC can only be opened at the end of the travel. So, for example, if the travel takes 5 seconds, there will be a 5 second delay from the nominal or expected turn-off time to the actual turn-off. There are many applications where such a delay cannot be tolerated or would even cause safety issues.

[0011] In view of the above, there therefore exists a need to increase the closing speed of such hybrid relays while still keeping them silent.

[0012] Furthermore, when a stepwise V (voltage) or I (current) ramp is applied as a drive signal S to the relay to move it from its disconnected position P o Bring it to its closed position P c When (see Figure 1 ), there is a first time period t in the first stage A a, during the first phase A the contact does not move; followed by a second time period t in the second phase B b , during the second phase B the contacts are actually moving (see Figure 1 The middle part of the process, where the movement of the contact is depicted as piecewise linear for simplicity), and finally the third time period t in the third stage C c , during the third phase C the contacts no longer move, but the pressure increases at the mutual contact level, allowing a good low contact resistance. Therefore, the total closing time T of the relay o This is quite inefficient and there is room for improvement.

[0013] Since relays are generally inexpensive components - their prices range from less than a dollar to several dollars - they are often manufactured within imprecise tolerances so that performance consistency cannot be ensured. In fact, they are often made of plastics and metals, which necessarily come with large tolerances, which are reflected in different behaviors from one piece to another, even the same part number from the same manufacturing batch. This tolerance causes: for the same applied drive signal S, the position of the starting time when the relay contacts begin to move is offset, such as Figure 2A and Figure 2B As shown in Figure 2A and Figure 2B Two relays are represented in graphical form, having supposedly nominally equal characteristics, but showing different behavior. Figure 2A The first relay R1 depicted in FIG. 1 has a first time period t a1 Shorter than Figure 2B The first time period t of the second relay R2 depicted in a2 , so that the second phase B starts earlier, and the contact is moving for the second time period t b For both, the third time period t c Therefore, in each second time period t of the first relay R1 and the second relay R2, b The start of the highlight is a time offset Δt.

[0014] Therefore, to support this variability, a longer period of time is required to switch all relays silently.

[0015] Therefore, there also exists a need for new types of relays and related switching operations that take these different behaviors into account. Summary of the invention

[0016] An object of the present invention is to provide an enhanced relay having a long-lasting operating time while greatly reducing acoustic noise and performing a switching operation in the shortest possible time.

[0017] Another object of the present invention is to further improve the switching time efficiency of silent hybrid relays, as well as to cope with the performance variability of their electromechanical parts.

[0018] To this end, the present invention relates to a method for operating a hybrid relay below a predefined low noise level, i.e. substantially below a level detectable by the human ear, the hybrid relay comprising a solid-state relay part and an electromechanical part mounted in parallel, wherein the electromechanical part has a drivable coil, at least a first fixed contact and at least a movable contact, the movable contact being switchable alternately between a closed position and an open position, wherein a control unit is connected to the drivable coil via a digital-to-analog converter for applying a drive signal to the drivable coil in operation, the method comprising:

[0019] - a first step of determining a first minimum voltage value of said drive signal, above which said movable contact starts to move away from said open position;

[0020] - a second step of determining a second minimum voltage value of said drive signal, above which said movable contact reaches said closed position (P c );

[0021] - and a subsequent step of shaping the waveform of the modified drive signal, the waveform comprising: a first portion consisting of a substantially vertical segment jumping from zero to the first minimum voltage value obtained in the previous first step; a subsequent second portion, in which the voltage gradually increases from the first minimum voltage value to the second minimum voltage value obtained in the previous second step within a time period shorter than or equal to a noise-free linear closing time, the noise-free linear closing time representing the closing time achievable by actually or theoretically applying a linear drive signal with a predefined slope to remain below the predefined low noise level limit set for the hybrid relay; and a final third portion consisting of another substantially vertical segment jumping from the second minimum voltage value to the upper voltage boundary applicable to the drivable coil.

[0022] "Substantially vertical segments" are understood in this context as segments where the voltage is increased / decreased as quickly as possible, taking into account the components of the drive circuit. Thus, the duration of these segments is made as short as possible within the operating boundaries of the device. A waveform is understood to describe the drive signal as a function of time. One advantage afforded by the claimed solution is that it significantly reduces the total closing time of the relay by removing the idle time during which the movable contact is not moving, while still driving the relay smoothly enough so that the generated noise level is not affected and still remains within acceptable levels.

[0023] According to a preferred embodiment, the linear drive signal extends over a first section during a first stage when the movable contact is not moving and the relay is in the open position, then extends over a second section during a second stage when the movable contact is moving, and then extends over a third section during a third stage when the movable contact has come into contact with a fixed switch contact and reached the closed position, and wherein the second portion of the waveform of the modified drive signal corresponds to the second section of the linear drive signal.

[0024] An advantage afforded by this preferred embodiment is that it is very simple to implement by utilizing the first minimum voltage value and the second minimum voltage value previously obtained to establish a noise-free linear closing time.

[0025] According to another preferred embodiment, the second part of the waveform of the further modified drive signal is non-linear, and preferably, the voltage is gradually increased from the first minimum voltage value obtained in the previous first step to the second minimum voltage value obtained in the previous second step within a reduced time period strictly lower than the noise-free linear closing time.

[0026] One advantage afforded by this preferred embodiment is that it defines curves of other shapes, such as logarithmic shapes, which can be designed to compensate for the acceleration pattern of the moving contacts, which in turn can be characterized as being inversely proportional to the square of the separation between the armatures. By using such an improved curve shape, as opposed to the linear shape of the drive signal used in obtaining a noise-free linear closing time, the switch contacts can be made to move smoothly enough so as not to generate too much velocity when reaching the contact point, while further reducing the closing time of the relay.

[0027] According to another preferred embodiment, the first minimum voltage value and the second minimum voltage value are relay-specific. In this case, the voltage difference between the first minimum voltage value and the second minimum voltage value defines a waveform that is also specific to each relay, and therefore the closing time is not only reduced, but also optimized for each relay.

[0028] According to yet another preferred embodiment, said first step of determining said first minimum voltage value and said second step of determining said second minimum voltage value are performed during a characterization step of the relays, preferably during their manufacture. This helps to streamline the overall calculation process.

[0029] According to a variant of this preferred embodiment, this characterization step derives the first minimum voltage value and the second minimum voltage value for a whole batch of relays, so that a global optimization is performed while taking into account the performance variability.

[0030] According to yet another preferred embodiment, the hybrid relay further comprises an acoustic sensor allowing automatic detection of the first and second minimum voltage values ​​derived in the previous first and second steps during relay operation after performing the noise data collection step.

[0031] One advantage afforded by this preferred embodiment is that the characterization step described above can be omitted; moreover, in the event of a relay change, adjustments will be automatically provided and performance optimization is always guaranteed, since in this case the best device-specific values ​​can always be provided.

[0032] According to a preferred variant of this preferred embodiment, a default waveform is first defined in a subsequent step after the collecting step, wherein an ongoing step of adjusting the waveform to an improved waveform is then performed in a closed-loop feedback manner after analyzing further noise data during the entire operational service life of the hybrid relay.

[0033] One advantage afforded by this preferred variant embodiment is that the calculation of the closing time of the relay is adaptive to the wear and / or aging of the relay, thus always ensuring that the lowest possible switching time is achieved.

[0034] Furthermore, the invention also relates to a hybrid relay comprising a control unit suitable for implementing the method described previously and comprising an acoustic sensor to implement a preferred embodiment of the invention involving a self-learning algorithm for calculating an optimized closing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings, which were previously introduced and are related to the prior art, illustrate:

[0036] -for Figure 1 : The three-stage behavior of the contacts of the relay provided by the linear drive signal when switching the relay from its open position to its closed position;

[0037] – respectively for Figure 2A and Figure 2B : Comparison of the behavior of two different relays when they are switched from their open position to their closed position, highlighting the time offset between the start of the second phase when the contacts start to move for each of the relays.

[0038] The present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0039] Figure 3Schematically shows the structural components of a hybrid relay used in the framework of the invention, as well as a control unit and an acoustic sensor attached thereto, according to a preferred embodiment of the invention;

[0040] Figure 4 shows a modified drive signal according to a preferred embodiment of the present invention to shorten the total closing time;

[0041] Figure 5 An exemplary characterization procedure is shown to determine the boundary voltages for the beginning and end of the second phase when the contact begins to move and stops moving;

[0042] Figure 6 Another modified drive signal according to another preferred embodiment of the present invention is shown which takes into account a wider range of different possible switching behaviors of the relay.

[0043] Figure 7 A further modified driving signal according to yet another preferred embodiment of the present invention is shown, wherein the waveform of the further modified signal is non-linear.

[0044] Figure 8 A self-learning algorithm that can be applied to a hybrid relay including an acoustic sensor according to yet another preferred embodiment of the present invention is schematically illustrated. DETAILED DESCRIPTION

[0045] In the following, preferred methods and systems according to preferred embodiments of the present invention will be described. These exemplary embodiments are given by way of example only and should not be interpreted in a limiting manner. When describing the drawings, references to drawings that have already been introduced and are redundant with previously discussed drawings will be omitted.

[0046] The method used in the framework of the present invention uses a combination of electromechanical relays and solid-state relays, also called hybrid relays, to increase the total number of switches by shaping a new type of waveform to drive the relay coils, and to switch the relays while greatly reducing the noise and performing the switching in the shortest possible time.

[0047] exist Figure 3A preferred system for applying the disclosed method is depicted in , showing a hybrid relay 1 made of an electromechanical part 10 and a solid-state relay (SSR) part 11 including a TRIAC 11A. The contacts of the electromechanical relay, namely the first contact 12 and the second contact 13, are connected in parallel with the contacts of the SSR, here the first fixed switch contact 102A and the second fixed switch contact 102B, so that each of these two components can close a circuit and drive the load to be controlled. A control unit 2 including a central processing unit 22 is connected to the SSR part 11 via a TRIAC driver interface 20 through a connection line 5 on the one hand, and to the electromechanical part 10 via a relay driver interface 21 through another connection line 5 on the other hand, which generates a drive signal to drive the drivable coil 101 via a digital-to-analog converter 4 so as to smoothly drive the moving contact 103 of the electromechanical relay at an optimized switching speed. Next to the moving contact 103, a noise detector 3 is illustrated, which helps to implement the preferred method of the present invention involving the self-learning algorithm described later.

[0048] In order to maximize the total number of switches / commutations, i.e. to increase the service life of hybrid relay 1, the following procedure should be used to close hybrid relay 1:

[0049] 1. Close the SSR contacts;

[0050] 2. Close the mechanical relay contacts;

[0051] 3. Disconnect the SSR contacts.

[0052] When the contacts are held closed by the SSR, current (both inrush current and normal current) will flow through the SSR, generating heat dissipation.

[0053] No arcing will occur across the contacts of the electromechanical part 10, as most of the current will be through the SSR part 11. A small amount of energy will still pass through the mechanical relay due to the voltage drop across the junction of the SSR. This represents typically less than 1% of the total load (in typical mains 230V operation).

[0054] Once commutation of the electromechanical relay is complete, the SSR is disconnected and the load will be through the electromechanical relay only.

[0055] The procedure for opening the contacts is:

[0056] 1. Close the SSR contacts;

[0057] 2. Disconnect the mechanical relay contacts;

[0058] 3. Disconnect the SSR contacts.

[0059] Comparative laboratory tests have shown that after 50,000 commutations at a resistive load of approximately 70% on a 16A relay, the contacts of a system operated by an electromechanical relay are only approaching the end of their life; when using such a hybrid relay 1, on the contrary, even after 10 million switching cycles at full load (16A), the contacts are still very similar to their state at the beginning of operation.

[0060] In the following, further details are provided on how the mechanical moving contact 103 can be switched silently. Figure 3 The electromechanical part 10 of the relay illustrated in FIG. 1 comprises two fixed contacts, but it will be appreciated that only one such contact is required to perform the switching operation.

[0061] The goal during this step is to achieve a movement of the moving contact 103 of the electromechanical part 10 of the relay as smooth as possible, i.e. not to come into mutual contact with the fixed contacts at a speed that would be too high and generate too much sound. In order to achieve this goal, the drivable coil 101 of the hybrid relay 1 is driven with a stepwise increasing / decreasing voltage or current (depending on whether the contacts must be closed / opened). During the commutation time, the load is handled by the SSR part 11, so the electromechanical relay durability is not affected. Without the covering of the SSR part 11, it would not be possible to move the moving contact 103 slowly, because the extended arcing due to the slow movement would then destroy the contacts very quickly.

[0062] Based on a predefined noise level N which can usually be set to the lower boundary of the audible range L , we can get as previously in Figure 1 The linear drive signal illustrated in FIG. 1 is a stepwise linear drive signal S, whose slope α defines the so-called noise-free linear closing time T. L , i.e. the time required to perform the second phase B, i.e. the moving contact 103 is actually moving for a second period of time t b stage (see Figure 4 ).

[0063] Figure 4 In fact, a linear drive signal with a linearly increasing voltage during the closing phase of the hybrid relay 1 is shown, the linear drive signal having a slope α, which can be divided into three parts:

[0064] A first segment S1, which lasts for a first time period t in a first phase A a , during the first phase A the contacts do not move;

[0065] - a second segment S2, which lasts for a second time period t b - corresponds to the second phase B, during which the contact is then moving; and finally

[0066] - a third segment S3, which lasts for a third time period t in a third phase C c During the third phase C, the contacts no longer move, but the pressure increases at the mutual contact level until the voltage reaches the upper voltage boundary V applicable to the drivable coil 101. sup .

[0067] The combination of all linear segments S1, S2, S3 is a continuous linear waveform similar to that of the linear drive signal S known in the prior art ( Figure 1 ), but now with a slope α.

[0068] According to the invention, the switching of the hybrid relay 1 is obtained by still maintaining a predefined noise level N L Below, however, a new waveform W is defined for an arbitrary curve of V / I (voltage or current) (i.e., a drive signal) to save the time when the ramp rise of V / I does not produce any movement, which is passed through the first time period t a and the third time period is concretized, the first time period t a and the third time period is a stage where no movement occurs.

[0069] according to Figure 4 In the preferred embodiment illustrated above, the waveform W of the modified driving signal S' for driving the drivable coil 101 is shown as follows:

[0070] a sudden jump to the region where the movement starts, i.e., within the capability of the operation of the drive circuit, a movement from zero substantially immediately after the end of the first phase A (i.e., within the first time period t a After t has elapsed) the linear drive signal S reaches a first voltage minimum voltage value V1. This is indicated by a first substantially vertical portion W1;

[0071] a slow ramp that is linear and corresponds to the second segment ( S2 ) of the linear drive signal (S) in the second phase B, which is shown as the second portion W2 ;

[0072] · Apply pressure to the contacts to allow a final snap of good contact, in a linear noiseless closing time T L The end is immediately moved from the second minimum voltage value, as indicated by the third generally vertical portion W3.

[0073] Thus, due to the newly derived waveform W of the modified drive signal S', the total closing time T of the relay is o Reduce to near t b , which is equal to the noise-free linear closing time T LTherefore, since the first phase A and the third phase C are shortened to near zero, t a and t c Both have been significantly reduced.

[0074] According to a preferred embodiment, the first minimum voltage value and the second minimum voltage value are obtained by a preliminary so-called characterization step E, during which it is checked from which voltage or current level a noise can be detected due to the movement of the contacts and from which voltage or current level this noise stops after the moving contact reaches the fixed contact.

[0075] Figure 5 An exemplary characterization step E is shown, which is performed for a whole batch of relay devices, thereby obtaining a lower minimum voltage value V corresponding to the minimum value at which any relay starts to make noise min (i.e. when a predefined noise level N is detected L , where each column corresponds to one of the relays in the batch for the third column from the left), and a higher minimum voltage value V corresponding to the maximum value at which all relays stop emitting noise max (i.e. when the predefined noise level N is no longer detected L The threshold value is ΔV, where for the first column from the right, each column also corresponds to one of the relays in the batch). Therefore, the maximum voltage difference ΔV is defined. M , the voltage difference ΔV M Greater than the normal voltage gap ΔV between the second minimum voltage V2 and the first minimum voltage V1 of any single relay.

[0076] To account for performance variability, Figure 6 A diagram showing a similar solution for shaping the shape of the waveform W of the modified drive signal S' is shown, still anticipating the first time period t of the first phase A. a And skip the third time period t of the third stage C c The total closing time of the relay is T o Reduce to another second time period t b’ , however, the time period t b’ Slightly longer than the second time period t obtained for a single relay device b This is because the slope α of the drive signal S remains the same to comply with the predefined noise level N L limit, and now there is a larger voltage gap ΔV M >ΔV.

[0077] In this way, the system can adapt to the different behaviors of the different hybrid relays 1 provided, or more specifically to the different behaviors of their electromechanical parts 10. However, since the closing time is slightly longer than in the case of a single hybrid relay (t b’ >t b ,like Figure 6 As a variant of the present invention, a more complex shape of the modified waveform W for the drive signal S is therefore introduced, resulting in a further modified drive signal S". This variant allows finding a good trade-off between reducing the time implementation and supporting performance variability.

[0078] This waveform W is designed to still comply with the predefined noise level N L limit, but the intention is to make the total closing time T o Minimize to be strictly shorter than the previously defined linear noise-free closure time T L The closing time T is further reduced R , that is, minimized to substantially reduce to the second time period t b or a slightly longer second time period t for a batch of equipment b’ Closing time.

[0079] Figure 7 How this waveform W works is explained using a single hybrid relay 1 for which a first minimum voltage V1 and a second minimum voltage V2 have been defined. Although it can be understood that by using, for example, the lowest minimum voltage value V min and the highest minimum voltage value V max , the same waveform will be applied to the batch of relays. Figure 4 In the previous case illustrated in FIG. , the waveform includes a first substantially vertical portion W1, which is the same as the substantially vertical portion applied to the modified drive signal S'; however, the second portion W2 is no longer linear, but logarithmic, as shown, to better compensate for the acceleration of the moving contact 103 when the moving contact 103 is driven by the coil. Therefore, the W2 portion of the further modified drive signal S" stops before the W2 portion of the modified drive signal S' using only the linear segment, and it is at the reduced closing time T R After that, instead of the linear noiseless closing time T L Then, the second minimum voltage V2 is reached. Then, corresponding to increasing the voltage from the second minimum voltage V2 to the upper voltage boundary V sup The third substantially vertical portion W3 of the final sudden jump is applicable to both the modified drive signal S′ and the further modified drive signal S″ for the drivable coil 101 and is only offset by the time difference T L –T RThe waveform corresponding to the modified drive signal S' is indicated by a single arrow, whereas the waveform corresponding to the further modified drive signal S" is indicated by a double arrow, in order to better visualize their common parts and different parts or corresponding segments.

[0080] In order to control stepwise the voltage or current driving the drivable coil 101, preferably a small microcontroller acting as a central processing unit 22 and a digital-to-analog converter 4 are used to synthesize a controlled ramp-up (for the voltage / current of the coil) corresponding to the modified drive signal S' and the further modified drive signal S". In this way, a very precise control can be performed; the waveform W of the ramp can be stored in the memory of the microcontroller and / or in an external memory and can be updated remotely in case changes are needed after the device is deployed. The possibility of remote updating can be helpful in case of erroneous characterization of the waveform W or in case of unexpected changes in the behavior of the relay due to specific wear or aging. Remote updating can replace an old waveform with a new one.

[0081] Another preferred embodiment of the present invention is to use an acoustic sensor 3 (e.g., a microphone), as previously described in Figure 3 As shown above, a vibration sensor (such as a piezoelectric crystal) is used on the electromechanical part 10 of the hybrid relay 1. This sensor can be used to collect the noise generated by the electromechanical part 10 of the relay and then perform closed-loop feedback to self-learn the previous Figure 4 The position of each of the first phase A, the second phase B and the third phase C of the relay depicted in FIG.

[0082] The main advantages of having such a closed-loop self-learning algorithm are:

[0083] - No characterization step is required upfront (ie at the manufacturing stage), which can be very complex and time-consuming. The occurrence of erroneous characterization can also be avoided.

[0084] - No external or remote adaptation required in case of relay type change;

[0085] - Significant gains can be achieved in terms of operating speed: in practice, the opening and closing times are always shortened in an optimized manner, since it is always possible to Figure 4 Instead of using a chart Figure 6 Since the generated values ​​are device-specific, they are always better than those derived in batches;

[0086] - And another key advantage of this preferred embodiment is: adaptive to wear and / or aging of the relays while always maintaining the lowest possible switching time;

[0087] exist Figure 8A basic flow chart of a preferred embodiment of the proposed "self-learning" solution within the framework of the present invention is shown in FIG, wherein a closed loop L defines a first step L0 of operating a relay, and then another step of collecting noise data L1 to automatically detect a first minimum voltage V1 and a second minimum voltage V2 can be performed.

[0088] The "self-learning algorithm" can be implemented in many different ways. One of the many ways could be to first determine the waveform W via successive approximation, and only perform additional refinement loops when noise is sensed. Or, alternatively, if wear / aging modifies the characteristics of the relay, periodic re-tuning could be performed to always guarantee optimal performance during long periods of time. "Periodic re-tuning" could be triggered by elapsed time or by the number of commutations performed.

[0089] Figure 8 An example of such periodic fine-tuning is shown. In a first iteration, a default waveform W0 is defined in a subsequent step L2 after collecting step L1 and then adjusted to an improved waveform W' after analyzing further noise data throughout the operational life of the hybrid relay in an ongoing step L3.

[0090] By using the hybrid relay 1 and the method for operating such a relay as explained in the above description, noise level reductions of up to 18 dB have been reported, which is far beyond the usual reduction levels achieved so far (more than ten times better in terms of attenuation).

[0091] In addition to the above, without departing from the scope of the subject matter of the present invention, other well-known components may be used to replace the components of the above-described embodiments as appropriate. In addition, the modifications described above may be combined with each other as appropriate. For example, other shapes different from the logarithmic shape for the second portion W2 of the waveform may also be considered, as long as they provide a time reduction relative to the linear case by efficiently compensating for the acceleration of the moving contact.

Claims

1. For use at a predefined low noise level (N L ) A method for operating a hybrid relay (1) comprising a solid-state relay part (11) and an electromechanical part (10) mounted in parallel, wherein the electromechanical part has a driveable coil (101), at least a first fixed contact (102A) and at least a movable contact (103), wherein the movable contact (103) is capable of being moved in a closed position (P c ) and disconnect position (P o ), wherein a control unit (2) is connected to the drivable coil (101) via a digital-to-analog converter (4) for applying a drive signal (S, S', S") to the drivable coil (101) during operation, the method comprising: - a first step of determining a first minimum voltage value of the drive signal (S, S', S") above which the movable contact (103) starts to move away from the open position (P o ); - a second step of determining a second minimum voltage value of the drive signal (S, S', S") above which the movable contact (103) reaches the closed position (P c ); - and a subsequent step of shaping a waveform (W) of a modified drive signal (S', S"), said waveform (W) comprising: a first portion (W1) consisting of a substantially vertical segment jumping from zero to said first minimum voltage value obtained in said first preceding step; a subsequent second portion (W2) wherein the voltage is substantially perpendicular to the first minimum voltage value obtained in said first preceding step, and the voltage is substantially perpendicular to the first minimum voltage value obtained in said first preceding step; L ), the voltage gradually increases from the first minimum voltage value to the second minimum voltage value obtained in the previous second step, and the noise-free linear closing time (T L ) represents the predefined low noise level (N) set for the hybrid relay (1) by applying a linear drive signal (S) with a predefined slope (α) to maintain L ) limit the closing time that can be achieved below; and finally a third part (W3), which is jumped from the second minimum voltage value to the upper voltage boundary (V sup ) is composed of another generally vertical segment.

2. The method according to claim 1 for detecting a low noise level (N L ) A method for operating a hybrid relay (1) as follows, wherein the linear drive signal (S) is when the movable contact (103) is not moving and the relay is in the open position (P o ), then extends over the second section (S2) during the second stage (B) when the movable contact (103) is moving, and then extends over the second section (S2) when the movable contact (103) has reached mutual contact with the fixed switch contact and reached the closed position (P c ) extends over a third segment (S3) during a third phase (C) of the modified drive signal (S'), and wherein the second portion (W2) of the waveform (W) of the modified drive signal (S') corresponds to the second segment (S2) of the linear drive signal (S).

3. The method according to claim 1 for detecting a low noise level (N L ) A method of operating a hybrid relay (1) as follows, wherein the second portion (W2) of the waveform (W) of the further modified drive signal (S") is non-linear and is shorter than the noise-free linear closing time (T L ) of the reduction period (T R ), gradually increasing the voltage from the first minimum voltage value obtained in the previous first step to the second minimum voltage value obtained in the previous second step.

4. A method for detecting a noise level at a predefined low noise level (N) according to any one of claims 1 to 3. L ) The following method of operating a hybrid relay (1), wherein the first minimum voltage value and the second minimum voltage value are relay-specific.

5. A method for producing a signal at a predefined low noise level (N) according to any one of claims 1 to 3. L ) The following method for operating a hybrid relay (1), wherein the first step and the second step are performed during a characterization step (E) of the relay.

6. The method according to claim 5 for detecting a low noise level (N L ) The following method for operating a hybrid relay (1), wherein the characterization step (E) derives the first minimum voltage value and the second minimum voltage value for a whole batch of relays.

7. A method for producing a signal at a predefined low noise level (N) according to any one of claims 1 to 3. L ) The following method for operating a hybrid relay (1), wherein the hybrid relay (1) also includes an acoustic sensor (3) allowing the first minimum voltage value and the second minimum voltage value obtained in the previous first step and the second step to be automatically detected during relay operation after performing the noise data collection step (L1).

8. The method according to claim 7 for detecting a low noise level (N L ) The following method for operating a hybrid relay (1), wherein in a subsequent step (L2) after the collection step (L1) a default waveform (W0) is first defined, wherein then an ongoing step (L3) of adjusting the waveform (W) to an improved waveform (W') is performed in a closed-loop manner after analyzing further noise data during the entire operational service life of the hybrid relay (1).

9. Hybrid relay (1) comprising a control unit (2) for implementing the method according to any of the preceding claims 1 to 8.

10. The hybrid relay (1) according to claim 9, further comprising an acoustic sensor (3).

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