EP4666380A1 - Controllable emi filter for automatic door operator - Google Patents

Abstract

ASSA ABLOY Entrance Systems AB has developed an automatic door operator (30). The automatic door operator (30) comprises a motor (36) and a controllable electromagnetic interference, EMI, circuit (100) configured to be connected to a current path (L, N) of the motor (36) powered by an AC power source (10). The controllable EMI circuit (100) comprises a switch device (110) and a filter circuit (120) connected in series. The switch device (110) is configured to selectively connect the filter circuit (120) to the current path (L, N) of the motor (36).

Description

CONTROLLABLE EMI FILTER FOR AUTOMATIC DOOR OPERATOR

TECHNICAL FIELD

The present invention generally relates to entrance systems having a movable door member (or more than one movable door member) and an automatic door operator for the movable door member. More specifically, the present invention relates to an EMI filter for an automatic door operator for use in such entrance systems, the automatic door operator having an AC motor capable of causing movement of the door member. The present invention also relates to a method of reducing EMI in an entrance system and an entrance system comprising such an automatic door operator.

BACKGROUND

Entrance systems having automatic door operators are frequently used for providing automatic opening and/or closing of movable door members in order to facilitate entrance and exit to buildings, rooms and other areas. To this end, an automatic door operator typically has an AC motor which is capable of causing the desired movement of a movable door member. The door member may, for instance, be a swing door, sliding door, revolving door or overhead sectional door.

Since entrance systems having automatic door operators are typically used in public areas, user convenience is of course important. In order to e.g. save energy, automatic door operators may be configured to open and close more rapidly. This decreases a time the movable door members are in transit and a total time that e.g. heated or cooled air may leak outside is reduced. The rapid opening and closing generally implies operating the AC motor at higher speed which may result in increased electromagnetic interference (EMI) being generated by the automatic door operator.

The present inventor has realized that there is room for improvements in this regard.

SUMMARY

An object of the present invention is therefore to provide one or more improvements to the problems or drawbacks identified in the preceding section of this document. Accordingly, a first aspect of the present invention is an automatic door operator comprising a motor and a controllable electromagnetic interference (EMI) circuit. The controllable EMI filter is configured to be connected to a current path of a motor powered by an AC power source. The controllable EMI circuit comprises a switch device and a filter circuit connected in series, wherein the switch device is configured to selectively connect the filter circuit to the current path of the motor.

The provision of such an automatic door operator will solve or at least mitigate one or more of the problems or drawbacks identified above, as will be clear from the following detailed description section and the drawings. A novel and inventive may of decreasing a current consumption of an automatic door opener without significantly decreasing EMIZEMC performance has been made possible.

In some variants, the filter circuit comprises a capacitor. A capacitor is a suitable low pass filter and will effectively filter high frequency components of a disturbance.

In some variants, the controllable EMI circuit further comprises a bleed device configured to discharge the capacitor at least when the filter circuit is disconnected from the current path of the motor. This is beneficial as it e.g. allows the automatic door operator to be safely serviced without risk of electric shock from the capacitor.

In some variants, a first EMI terminal of the controllable EMI circuit is connected to a forward current path of the motor and a second EMI terminal of the controllable EMI circuit is connected to a return current path of the motor. The switch device and the filter circuit are connected in series between the first terminal and the second terminal of the controllable EMI circuit.

In some variants, the switch device is one of a transistor, a thyristor or a relay.

In some variants, the automatic door operator further comprising a controller configured to cause control of the switch device.

In some variants, the controller is configured to cause the switch device to connect the filter circuit to the current path of the motor responsive to activation of the motor. This is beneficial as it may further reduce the power consumption and ensures that the filter is connected during operation of the motor.

In some variants, wherein the controller is configured to cause the switch device to disconnect the filter circuit from the current path of the motor responsive to deactivation of the motor. This is beneficial as it may further reduce the power consumption and ensures that the filter is disconnected when the motor is not operated.

In some variants, the controller is further configured to cause connecting and/or disconnecting of the filter circuit to/from the current path of the motor based on a voltage amplitude of the AC power source. This is beneficial as it may further reduce the power consumption and enables connection and disconnection of the filter without differences in voltage between the capacitor and the feed.

In some variants, the controller is further configured to cause connecting and/or disconnecting of the filter circuit to/from the current path of the motor responsive to the voltage amplitude of the AC power source being below an activation threshold. This is beneficial as it may further reduce the power consumption and enables connection and disconnection of the filter without differences in voltage between the capacitor and the feed.

In a second aspect, an EMI reducing method of operating an entrance system is presented. The entrance system comprises an automatic door operator and a movable door member. The automatic door operator comprises a motor powered by an AC power source. The method comprises obtaining a request indicating activation of the motor for causing movement of the movable door member; and, in response thereto, connecting a filter circuit of a controllable EMI circuit of the entrance system to a current path of the motor.

In some variants, connecting the controllable EMI circuit further comprises obtaining a voltage amplitude of the AC power source. Responsive to the obtained voltage amplitude being below an activation threshold, the method comprises controlling a switch device of the controllable EMI circuit to connect the filter circuit to the current path of the motor.

In some variants, the method further comprises obtaining a request indicating deactivation of the motor. In response thereto, the method comprises disconnecting the filter circuit of the controllable EMI circuit of the entrance system from the current path of the motor.

In some variants, disconnecting the switch device further comprises obtaining a voltage amplitude of the AC power source. Responsive to the obtained voltage amplitude being below an activation threshold, the method comprises controlling the switch device of the controllable EMI circuit to disconnect the filter circuit from the current path of the motor.

In some variants, the automatic door operator is the automatic door operator according to the first aspect.

In a third aspect, an entrance system is presented. The entrance system comprises a movable door member and an automatic door operator according to the first aspect which is configured to control a position of the movable door member.

Embodiments of the invention are defined by the appended dependent claims and are further explained in the detailed description section as well as in the drawings.

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc.]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

A reference to an entity being “designed for” doing something in this document is intended to mean the same as the entity being “configured for”, or “intentionally adapted for” doing this very something.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects, features and advantages of embodiments of the invention will appear from the following detailed description, reference being made to the accompanying drawings.

Figure 1 A is a schematic block diagram of an entrance system generally according to the present invention.

Figure IB is a schematic block diagram of an embodiment of an automatic door operator which may be included in the entrance system shown in Figure 1 A. Figure 2 is a schematic illustration of a motor drive arrangement for controlling operation of the AC motor in the automatic door operator.

Figure 3 is a schematic block diagram of an embodiment of an automatic door operator connected to an AC power source.

Figure 4 is a schematic block diagram of an embodiment of a controllable EMI filter which may be included in the automatic door operator shown in Figure 3.

Figure 5 is a schematic block diagram of an embodiment of an automatic door operator connected to an AC power source.

Figure 6A is a schematic block diagram of an embodiment of a controllable EMI filter which may be included in the automatic door operator shown in Figure 3.

Figure 6B is a schematic block diagram of an embodiment of a controllable EMI filter which may be included in the automatic door operator shown in Figure 3.

Figure 7 is a time-series plot of an input voltage from an AC power source.

Figure 8 is a schematic block diagram of an embodiment of a controllable EMI filter which may be included in the automatic door operator shown in Figure 3.

Figure 9A is a flowchart diagram illustrating a method, generally according to the present invention, of reducing EMI.

Figure 9B is a flowchart diagram illustrating a partial method, which may be included in the method of Figure 9 A.

Figure 9C is a flowchart diagram illustrating a partial method, which may be included in the method of Figure 9 A.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. Figure 1 A is a schematic block diagram illustrating an entrance system 1 in which the inventive aspects of the present invention may be applied. The entrance system 1 comprises one or more movable door members DM1 . . DMm, and an automatic door operator 30 for causing movements 50 of the door members DM1 . . .DMm between different positions, typically between closed and open end positions. The movements 50 may be rotational or translational. A linkage mechanism 40 conveys mechanical power from the automatic door operator 30 to the movable door members DM1 . . .DMm.

In the following, reference will predominantly be made to a single door member only, in an exemplifying and non-limiting sense. The door member will be referred to as DM1, again in an exemplifying and non-limiting sense. It is to be understood that there is no particular limitation in the number of door members operated by the automatic door operator 30 in the present disclosure. In some embodiments, the entrance system 1 may comprise a plurality of automatic door operators 30, each being installed for operating a respective door member or, alternatively, a respective group of door members.

The entrance system 1 advantageously has a control arrangement 20 which comprises a controller 32. Typically, the controller 32 is physically contained within the automatic door operator 30, as can be seen in the embodiment of Figure IB to be described below. In alternative embodiments, the controller 32 may be a separate device operably connected to the automatic door operator 30 and in effect forming a functional part thereof. The control arrangement 20 advantageously comprises a number n of external sensor units S 1 . . . Sn, where n > 0. Each sensor unit S 1 . . . Sn may generally be connected to the controller 32 by a wired connection, a wireless connection, or a combination thereof.

As is generally known by the skilled person, the sensor units SI . . . Sn may be any suitable sensor unit SI . . . Sn. One or more sensor units SI . . . Sn may be arranged to monitor a respective zone at the entrance system 1 for presence or activity of a person or object. The person may be an individual who is present at the entrance system 1, is approaching it or is departing from it. The object may, for instance, be an animal or an article in the vicinity of the entrance system 1, for instance brought by the aforementioned individual. Alternatively, the object may be a vehicle or a robot. Figure IB illustrates an embodiment of the automatic door operator 30 in more detail. The automatic door operator 30 may, for instance, be arranged as a concealed overhead installation in conjunction with a frame or other structure which supports the movable door member DM1 to move between different (e.g. closed and open) positions.

In addition to the aforementioned controller 32, the automatic door operator 30 comprises an electric motor 36, advantageously an electric AC motor, being connected to an internal transmission (e.g. gearbox) 38. An output shaft of the transmission 38 rotates upon activation of the motor 36 and is connected to the external linkage mechanism 40. The external linkage mechanism 40 translates the motion of the output shaft of the transmission 38 into an opening or closing motion 50 of the door member DM1 with respect to the frame or support structure.

The controller 32 is arranged for performing different functions of the automatic door operator 30, possibly in different operational states of the entrance system 1. To this end, the controller 32 may use sensor input data from the external sensor units SI . . . Sn. Hence, the controller 32 may be operatively connected with the sensor units SI ... Sn in the disclosed embodiment. Furthermore, the controller 32 may use input data from internal detectors D1-D4 in the automatic door operator 30. For instance, there may be an internal detector DI at the input of the AC motor 36, an internal detector D2 at the output shaft of the AC motor 36, an internal detector D3 at the output shaft of the transmission 38, and an internal detector D4 to monitor an internal operating environment parameter of the automatic door operator 30, such as temperature, supply voltage, current etc.

At least some of the different functions performable by the controller 32 have the purpose of causing desired movements 50 of the door member DM1. To this end, in the disclosed embodiment, the controller 32 has at least one control output connected to a drive unit 34 for the AC motor 36. An exemplary embodiment of the drive unit 34 will be described in more detail later in this document, particularly with reference to Figure 2.

The controller 32 may be implemented in any known controller technology, including but not limited to microcontroller, processor (e.g. PLC, CPU, DSP), FPGA, ASIC or any other suitable digital and/or analog circuitry capable of performing the intended functionality. The controller 32 also has an associated memory 33. The memory 33 may be implemented in any known memory technology, including but not limited to E(E)PROM, S(D)RAM or flash memory. In some embodiments, the memory 33 or parts of it may be integrated with or internal to the controller 32. The memory 33 may store software 35a comprising computer program instructions for loading into the controller 32 (as seen at 35b) and execution by the controller 32, as well as temporary and permanent data used by the controller 32. In some embodiments, the software 35b may be firmware, i.e. embedded software stored on-chip of the controller 32. The drive unit 34 may also have embedded software/firmware, as seen at 35c in Figure IB. Generally, when reference is made to “software” in this document, it may relate to such software 35a, 35b, 35c. Generally, when reference is made to “an arrangement configured for [doing something]” in this document, it may be implemented by such software 35a, 35b, 35c executed by the relevant hardware in the automatic door operator 30.

In the embodiment shown in Figure IB, the entrance system 1 has a communication bus 37. Some or all of the plurality of external sensor units SI ... Sn are connected to the communication bus 37, and so is the controller 32 and the memory 33 of the automatic door operator 30. In other embodiments, other devices or components of the automatic door operator 30 may be connected to the communication bus 37. In still other embodiments, the outputs of the sensor units SI . . . Sn may be directly connected to respective data inputs of the controller 32.

In Figure 2, a simplified view of an exemplary embodiment of the motor drive 34 is shown. In typical embodiments, the motor 36 is a three-phase electric induction motor. As is well known per se, the motor 36 therefore comprises three stator windings (these stator windings are seen as 36U, 36V and 36W in Figure 2). It is conceived that in alternative embodiments, the AC motor 36 may be a three-phase electric synchronous motor. In Figure 2, the motor drive 34 (cf. Figure IB) is a variable-frequency drive, VFD, of conventional design as such. The VFD 34 comprises a rectifier block 310 coupled to receive power at 302 from an AC power source 10, i.e. any suitable source of one-phase or three-phase alternating current. In the former case, the rectifier block 310 will have a phase input and a second input connected to ground. In the latter case, the rectifier block 310 will have first, second and third phase inputs. The rectifier block 310 contains power electronics designed to convert the one-phase or three-phase AC input to a rectified output. As is well known to a skilled person, the power electronics of the rectifier block 310 typically includes a number of diodes in a bridge rectifier configuration.

The rectified output from the rectifier block 310 is filtered by a DC link 320 which in turn is connected to an inverter block 330. The inverter block 330 comprises power electronics designed to synthesize three AC phase signals U, V and W to be fed into the respective stator windings 36U, 36V and 36W of the AC motor 36. As is well known to a skilled person, the power electronics of the inverter block 330 typically includes a number of electronic switches in a bridge inverter configuration (such as a three-phase, six-switch, full-wave bridge). The electronic switches are based on transistors, such as IGBTs or MOSFETs in pairs with anti -parallel diodes.

The VFD 34 further comprises PWM control circuitry 340 for controlling the electronic switches by PWM control signals 344. Fed by DC power from the DC link 320, the electronic switches are thus controlled by the PWM control circuitry 340 to vary the frequency and associated voltage or current (depending on inverter topology) of the synthesized AC signals U, V and W through the stator windings 36U, 36V and 36W, so as to control the speed and torque of the AC motor 36. In turn, the PWM control circuitry 340 may be controlled by control signals 342 from the controller 32 (not seen in Figure 2 but in Figure IB) to command a desired movement 50 of the door member DM1 by actuating the motor 36 accordingly.

Devices placed on the market are generally required to fulfill certain requirements when it comes to electromagnetic compatibility (EMC). One such standard is the well-known IEC TS 61000 specifying requirements for immunity and emissions (conducted and radiated). During operation, the inverter 330 will switch currents between the windings 36U, 36 V, 36W of the motor 36 based on the PWM control circuitry 340. These switching will generally introduce interference that may be transferred from the VFD 34 back to the AC power source 10.

As shown in Figure 3, in order to ensure that the VFD 34 and also the automatic door operator 30 complies with emission and immunity requirements, an electromagnetic interference (EMI) circuit 31 is generally provided between the drive unit 34 and the AC power source 10. The EMI circuit 31 may, as shown in Figure 3, form part of the automatic door operator 30, or be provided as a standalone circuit configured to be arranged between the automatic door operator 30 and the AC power source 10.

In Figure 4A, a simplified schematic of an EMI circuit 31 as is known in the art is shown. The skilled person will appreciate that the EMI circuit 31 in Figure 4A may be considered incomplete for some applications, and that components such as fuses etc. are omitted for explanatory efficiency. The EMI circuit 31 in Figure 4A is provided between the AC power source 10 and the automatic door operator 30. The EMI circuit 31 in Figure 4 A receives AC power at forward current path L and a return current path N. The forward current path L may be referenced as a phase and the return current path N may be references as a neutral. An input capacitor Cx is arranged between the forward current path L and the return current path N. The input capacitor Cx is provided to filter differences in changes in voltage between the forward current path L and the return current path N. The input capacitor Cx will filter such disturbance both towards (immunity) and from (emission) the automatic door opener 30. The EMI circuit 31 of Figure 4 A further comprises a common mode coil L arranged downstream from the input capacitor Cx. The common mode coil L is provided to filter changes common to both the forward current path L and the return current path N. The input capacitor Cx and the common mode coil L will filter such disturbance both towards (immunity) and from (emission) the automatic door opener 30. The EMI filter 31 of Figure 4A further comprises a forward capacitor Cl provided downstream from the common mode coil L connected between the forward current path L and a common potential Pe of the automatic door opener 30. The EMI filter 31 of Figure 4a further comprises a return capacitor Cn provided downstream from the common mode coil L connected between the return current path N and the common potential Pe of the automatic door opener 30. The forward capacitor Cl and the return capacitor Cn are provided to filter voltage changes in the respective current path L, N with reference to the common potential Pe. The common potential Pe may be ground or a protective ground of the automatic door opener 30. In Figure 4A, the EMI filter 31 further comprises a transformer T arranged to provide galvanic isolation to circuits (the automatic door opener 30) arranged downstream from the EMI filter 31. The transformer T is optional but advantageous as the galvanic isolation simplifies e.g. certification as a risk of having the AC power source 10 galvanically connected to circuit downstream the EMI filter 31 is reduced. In some embodiments, one or more transformers may be provided in circuits downstream from the EMI circuit 31.

The EMI filter 31 referenced in Figure 4 A, and EMI filters referenced in the following are generally described in conjunction with a single phase AC source 10. However, the teachings of the present disclosure are equally applicable to each of the three phases of a three phase AC source and it is well within the knowledge of the skilled person to implement embodiments of the present disclosure also on three phase systems.

It is recalled from previous sections of this disclosure, that it may be desired to control the motor 36 to operate at an increased speed in order to decrease a time the movable door member DM1 is in transit between e.g. an open and a closed position. Increasing the speed of the motor 36 implies increasing a current through the windings 36U, 36V, 36W of the motor 36. In order to accomplish this, the inverter 330 will have to increase its switching frequency. Increased current will, as the skilled person appreciates, increase an amplitude of disturbance generated by the inverter 330.

In order to ensure that requirements are fulfilled also with a higher speed of the motor 36, a straight forward approach may be to increase a capacitance of the forward capacitor Cl and the return capacitor Cn, but primarily to increase a capacitance of the input capacitor Cx. The inventor behind the present disclosure have realized that, although efficient for reducing emissions, increasing the input capacitor will increase an idle current consumption of the automatic door operator 30.

An impedance Z of a capacitor is, as is well known, dependent on a capacitance C and an operating frequency f as |Z| = A current I through the capacitor may be describes as I = = U ■ 2 fC, where U is a voltage provided by the AC power

1^1 source 10. Consequently, an increase of the input capacitor Cx will increase a current consumption of the EMI circuit 31 and thereby the automatic door operator 30 and the entrance system 1.

For environmental purposes and in order to reduce heating of components it is advantageous not to increase current consumption of any device more than required. The inventor behind the present disclosure have inventively provided a solution that may be utilized with substantially any input capacitor Cx without increasing current consumption or compromising EMC performance. In fact, in most use cases, the teachings of the present disclosure will decrease current consumption of the EMI circuit 31 and thereby the automatic door operator 30 and the entrance system 1.

In Figure 5, a controllable EMI circuit 100 according to some embodiments of the present disclosure is shown. In this embodiment, the controllable EMI circuit 100 comprises all components described with reference to the EMI circuit of Figure 4, but with the addition of a switch device 110 and a filter circuit 120. The switch device 110 is provided in series with the filter circuit 120 and configured to selectively connect the filter circuit 120 between the forward current path L and the return current path N. In Figure 5, the filter circuit 120 comprises the input capacitor Cx whereby the switch device 110 is provided in series with the input capacitor Cx and configured to selectively connect the input capacitor Cx between the forward current path L and the return current path N. In Figure 5, the switch device 110 is arranged between the input capacitor Cx and the forward current path L, but in other embodiments, the switch device 110 may be arranged between the switch device 110 and the return current path N. In Figure 5, a state (open/closed) of the switch device 110 is controlled by the controller 32 of the automatic door operator 30. Advantageously, the controller 32 is configured to control the switch device 110 to connect the input capacitor Cx between the forward current path L and the return current path N responsive to the automatic door operator 30 being operated. That is to say, the input capacitor Cx is advantageously connected between the forward current path L and the return current path N before, or simultaneous to activation of the inverter 330 and/or the motor 36.

In Figure 6A, an isolated block diagram of the controllable EMI filter 100 is shown. The controllable EMI filter of Figure 6A comprises a first EMI terminal 101 configured to be connected to the forward current path L of the automatic door operator 30 (i.e. the motor 36). The controllable EMI filter 100 further comprises a second EMI terminal 102 configured to be connected to the return current path N of the automatic door operator 30. The controllable EMI filter 100 further comprises a third EMI terminal 103 configured to be connected to the forward current path L of the automatic door operator 30. The controllable EMI filter 100 further comprises a fourth EMI terminal 104 configured to be connected to the return current path N of the automatic door operator 30. The controllable EMI filter may be commutative such that either the first and second EMI terminals 101, 102 may be upstream from the third and fourth EMI terminals 103, 104, or the first and second EMI terminals 101, 102 may be downstream from the third and fourth EMI terminals 103, 104. Correspondingly, the first and third EMI terminals 101, 103 may be configured to be connected to the return current path N and the second and fourth EMI terminals 102, 104 may be configured to be connected to the forward current path L. As shown in Figure 6A, the switch device 110 and the filter circuit 120 are connected in series between the first terminal 101 and the second terminal 102 of the controllable EMI circuit 100.

As seen in Figure 6A, the controllable EMI filter 100 may optionally comprise an additional filter circuit 130. The additional filter circuit 130 is exemplified in Figure 5 as comprising the common mode coil L, the forward and return capacitors Cl, Cn and the transformer T. The additional filter circuit 130 may comprise any suitable filter components connected in series with, between, or in parallel with the forward current path L and the return current path N.

It should be mentioned that, by arranging the switch device 110 in series with the filter device 120 and selectively connecting the two between the forward current path L and the reverse current path N, a circuitry that reduces excess current consumption is provided. If, for instance, the motor 36 and/or the drive 34 are idle, there is still an electrical connection between the AC power source 10 to e.g. the controller 32 and/or other downstream devices. This allows low current consuming devices and/or devices less likely to cause emissions and/or devices having issues with immunity to operate without the controllable EMI filter 100 wasting power by being configured for the worst case scenario (which is generally the case). To exemplify, the additional filter circuit 130 may comprise sufficient capacitance between the forward current path L and the reverse current path N to ensure EMC compliance in all cases except when the motor 36 is operated.

In some embodiments, the controllable EMI filter 100 comprises more than one set of EMI filter 120 and switch device 110 arranged in series between the forward current path L and reverse current path N. This is illustrated in Figure 6B wherein a first EMI filter 120a and a first switch device 110a are arranged in series between the forward current path L and reverse current path N, followed by a second EMI filter 120b and a second switch device 110b arranged in series between the forward current path L and reverse current path N, followed by further sets up until an n:th EMI filter 120n and an n:th switch device 1 lOn are arranged in series between the forward current path L and reverse current path N. This enables a granular control of the controllable EMI filter 100 wherein none, one or several of the switch devices 110a, 110b, . . ., 1 lOn may be configured to connect their associated EMI filter 120, 120b, . . ., 120b between the forward current path L and reverse current path N. The number of EMI filters 120, 120b, . . ., 120b connected between the forward current path L and reverse current path N may be determined based on a current operational mode of the automatic door operator 30. Operational modes may comprise e.g. fast opening of the movable door member DM1, fast closing of the movable door member DM1, medium opening of the movable door member DM1, medium closing of the movable door member DM1, slow opening of the movable door member DM1, slow closing of the movable door member DM1, etc.

The switch device 110 in, in Figure 5, shown as general switch device and it should be mentioned that any suitable switch device may be utilized. In some embodiments the switch device 110 is a transistor. In some embodiments the switch device is a thyristor. In an advantageous embodiment, the switch device 110 is a relay. The skilled person will understand and know how to implement specific control signals depending on a type of switch device 110 utilized and this will not be further explained.

As the switch device 110 will be provided between the forward current path L and reverse current path N rather than in series with the forward current path L or reverse current path N, current handling requirement of the switch device 110 are reduced.

The inventor behind the present disclosure have further realized that additional energy may be saved by synchronizing the control of the switch device 110 to a phase of the AC power source 10. That is to say, the control of the switch device 110 may be controlled based a voltage amplitude Vac (see Figure 6) of the AC power source 10. Assuming that the EMI filter 120 comprises the input capacitor Cx, as long as the switch 110 is configured to connect the input capacitor Cx between the forward current path L and reverse current path N, a voltage of the input capacitor Cx will be substantially the same as the voltage amplitude Vac of the AC power source 10. However, as soon as the input capacitor Cx is disconnected from the forward current path L and/or the return current path N, the voltage of the input capacitor Cx will remain the same (disregarding self-discharging etc.). This means that, when the input capacitor Cx is once more connected between the forward current path L and reverse current path N, there may be an inrush current, or rapid discharging of the input capacitor Cx depending on a difference in voltage between the input capacitor Cx and the AC power source 10, an instantaneous voltage of the AC power source 10. If the input capacitor Cx is large, and there is a comparably large difference in voltage between the input capacitor Cx and the AC power source 10, a mechanical switch device 110 may give rise to a spark gap when operated and this may even cause welding of the switch device 110.

In Figure 7, a time series plot of the voltage amplitude Vac of the AC power source 10 is shown. In Figure 7, an absolute value of the voltage amplitude Vac of the AC power source 10 is at its minimum value (zero in Figure 7) at time points T1-T7 indicated by dashed vertical lines in Figure 7. In some embodiments, the controller 32 is configured to detect the minimum absolute value of the AC power source 10 and to synchronize the connection and/or disconnection of the filter 120 to the time points Tl- T7 at which the voltage amplitude Vac of the AC power source 10 assumes its minimum absolute value. Depending on e.g. a frequency of the AC power source 10, and/or an accuracy in the detection of the voltage amplitude Vac of the AC power source 10, it may be advantageous to compare the voltage amplitude Vac of the AC power source 10 to activation thresholds VI, V2 of the controllable EMI filter 100. In Figure 7, a first activation threshold VI and a second activation threshold V2 are shown with horizontal dotted lines. In some embodiments, the controller 32 is configured to detect the voltage amplitude Vac of the AC power source 10 and to synchronize the connection and/or disconnection of the filter 120 to points in time at which the voltage amplitude Vac of the AC power source 10 is between the first activation threshold VI and the second activation threshold. In Figure 7, the activation thresholds VI, V2 are symmetrical at either side of the minimum absolute value of the voltage (generally zero). This means that the absolute value of the first activation threshold VI is equal to the absolute value of the second activation threshold V2. It should be mentioned that the connection and/or disconnection of the filter 120 may be synchronized to any voltage amplitude Vac of the AC power source 10. Advantageous is if both connection and disconnection of the filter 120 are synchronized to substantially the same voltage amplitude Vac of the AC power source 10. More advantageously is if both connection and disconnection of the filter 120 are synchronized to substantially the same voltage amplitude Vac of the AC power source 10 being a minimum absolute value of the voltage amplitude Vac of the AC power source 10.

The voltage amplitude Vac of the AC power source 10 may be obtained in any suitable way. In some embodiments, one or more of the internal detectors D1-D4 may be configured to obtain an indication of a current voltage amplitude Vac of the AC current source 10.

With reference to Figure 8. In addition to, or as an alternative to, utilization of the voltage amplitude Vac of the AC power source 10 to determine suitable times to connect or disconnect the filter circuit 120, the configurable EMU circuit 100 may further comprise a bleed device 140. The bleed device 140 may be any suitable device or circuit configured to discharge the capacitor Cx of the filter circuit 120 at least when the capacitor Cx is disconnected from the forward current path L and/or the reverse current path N of the motor 36. In Figure 8, the bleed device 140 is illustrated as a resistor connected in series with switch device 110 and in parallel with the input capacitor Cx. With such an arrangement, the bleed device 140 will allow for a controlled discharging of the input capacitor Cx. It should be mentioned that the bleed device 140 will generally increase a current consumption of the controllable EMI circuit 100, but by selecting the bleed device 140 such that a discharge current is comparably low, any increase in current consumption may be considered negligible.

Based on the teachings presented herein, one exemplary embodiment of an automatic door operator 30 comprises a controllable EMI circuit 100 according to any example or embodiment presented herein. A controller 32, which may the controller of the automatic door operator 30 or any other controller of an entrance system 1, is configured to control operation of the switch device 110 of the controllable EMI circuit 100. The controller 32 may obtain an indication from e.g. an external sensor unit SI . . . Sn operatively connected to the controller 32 indicating that a person is in the vicinity of a movable door member DM1, . . DMm controllable by the automatic door operator 30. Responsive to the indication, the controller 32 may obtain a current voltage amplitude Vac of an AC current source 10 connected to the controllable EMI circuit 100 of the automatic door operator 30. The current voltage value Vac is provided as input data from internal detectors D1-D4 of the automatic door operator 30. Responsive to an absolute value of the current voltage amplitude Vac being at its minimum absolute value, the controller 32 may cause control of the switch device 110 such that the filter circuit 120 of the controllable EMI circuit 100 is connected between a forward current path L and a reverse current path N of a motor 36 of the automatic door operator 30. If the automatic door operator 30 is configured such that the motor 36 is at an idle state during a time at which the movable door member DM1, . . . , DMm is at its end positions (i.e. open or closed, not transitioning there between), the controller 32 may obtain a current voltage amplitude Vac of the AC current source 10 connected to the controllable EMI circuit 100 of the automatic door operator 30. Responsive to the absolute value of the current voltage amplitude Vac being at its minimum absolute value, the controller 32 may cause control of the switch device 110 such that the filter circuit 120 of the controllable EMI circuit 100 is disconnected from the forward current path L and/or the reverse current path N of a motor 36 of the automatic door operator 30. Alternatively, or additionally, at a lapse of a timer or other suitable functionality the entrance system 1 may be configured to generate an indication to close the movable door member DM1, . . . , DMm. As when opening the movable door member DM1, . . . , DMm, responsive to obtaining the indication to close the movable door member DM1, . . ., DMm, the controller 32 may obtain a current voltage amplitude Vac of the AC current source 10 connected to the controllable EMI circuit 100 of the automatic door operator 30.

Responsive to the absolute value of the current voltage amplitude Vac being at its minimum absolute value, the controller 32 may cause control of the switch device 110 such that the filter circuit 120 of the controllable EMI circuit 100 is connected between a forward current path L and a reverse current path N of a motor 36 of the automatic door operator 30. One or more internal detectors D1-D4 may be arranged to generate an indication responsive to the movable door member DM1, . . ., DMm reaching its closed position. Responsive thereto, the controller 32 may obtain a current voltage amplitude Vac of the AC current source 10 connected to the controllable EMI circuit 100 of the automatic door operator 30. Responsive to the absolute value of the current voltage amplitude Vac being at its minimum absolute value, the controller 32 may cause control of the switch device 110 such that the filter circuit 120 of the controllable EMI circuit 100 is disconnected from the forward current path L and/or the reverse current path N of a motor 36 of the automatic door operator 30.

Based on the teachings presented herein, and with reference to Figure 9A, an EMI reducing method 200 will be presented. The method 200 is suitable for operating on an entrance system 1 as presented herein according to any example or embodiment. The entrance system 1 comprises an automatic door operator 30 which may be any suitable automatic door operator 30 comprising a controllable EMI filter 100 as presented within the present disclosure. The entrance system 1 further comprises at least one movable door member DM1, . . . , DMm. The movement of the at least one movable door member DM1, . . . , DMm is controlled by the automatic door operator 30. The automatic door operator 30 comprises a motor 36 powered by an AC power source 10. The method 200 comprises obtaining 210 a request indicating activation of the motor 36 for causing movement of the movable door member DM1, . . ., DMm. The method 200 further comprises, responsive to obtaining 210 the request, causing (a switch device 110 of the controllable EMI circuit 100 to) connection 220 of a filter circuit 120 of a controllable EMI circuit 100 of the entrance system 1 to a current path L, N of the motor 36.

In some embodiment, the method 200 may comprise, responsive to obtaining 230 a request indicating deactivation of the motor 36, causing (a switch device 110 of the controllable EMI circuit 100 to) disconnect 240 of the filter circuit 120 from the current path L, N of the motor 36.

In some embodiments, see Figure 9B, connecting 220 the filter circuit 120 may further comprises obtaining 222 a voltage amplitude Vac of the AC power source 10. Responsive to the obtained voltage amplitude Vac being below an activation threshold VI, V2, the method 200 may cause control of the switch device 110 of the controllable EMI circuit 100 to connect 224 the filter circuit 120 to the current path L, N of the motor 36.

In some embodiments, see Figure 9C, disconnecting 240 the filter circuit 120 further comprises obtaining 242 a voltage amplitude Vac of the AC power source 10. Responsive to the obtained voltage amplitude Vac being below an activation threshold VI, V2, the method 200 may cause control of the switch device 110 of the controllable EMI circuit 100 to disconnect 244 the filter circuit 120 from the current path L, N of the motor 36. The invention has been described above in detail with reference to embodiments thereof. However, as is readily understood by those skilled in the art, other embodiments are equally possible within the scope of the present invention, as defined by the appended claims. It is recalled that the invention may generally be applied in or to an entrance system having one or more movable door member not limited to any specific type. The or each such door member may, for instance, be a swing door member, a revolving door member, a sliding door member, an overhead sectional door member, a horizontal folding door member or a pull-up (vertical lifting) door member.

Claims

1. An automatic door operator (30) comprising a motor (36) and a controllable electromagnetic interference, EMI, circuit (100) configured to be connected to a current path (L, N) of the motor (36) powered by an AC power source (10), the controllable EMI circuit (100) comprises a switch device (110) and a filter circuit (120) connected in series, wherein the switch device (110) is configured to selectively connect the filter circuit (120) to the current path (L, N) of the motor (36).

2. The automatic door operator (30) of claim 1, wherein the filter circuit (120) comprises a capacitor (Cx).

3. The automatic door operator (30) of claim 2, wherein the controllable EMI circuit (100) further comprises a bleed device () configured to discharge the capacitor () at least when the filter circuit (120) is disconnected from the current path () of the motor (36).

4. The automatic door operator (30) of any one of the preceding claims, wherein a first EMI terminal (101) of the controllable EMI circuit (100) is connected to a forward current path (L) of the motor (36) and a second EMI terminal (102) of the controllable EMI circuit (100) is connected to a return current path (N) of the motor (36); the switch device (110) and the filter circuit (120) are connected in series between the first terminal (101) and the second terminal (102) of the controllable EMI circuit (100).

5. The automatic door operator (30) of any one of the preceding claims, wherein the switch device (110) is one of a transistor, a thyristor or a relay.

6. The automatic door operator (30) of any one of the preceding claims, further comprising a controller (32) configured to cause control of the switch device (110).

7. The automatic door operator (30) of claim 6, wherein the controller (32) is configured to cause the switch device (110) to connect the filter circuit (120) to the current path (L, N) of the motor (36) responsive to activation of the motor (36).

8. The automatic door operator (30) of claim 6 or 7, wherein the controller (32) is configured to cause the switch device (110) to disconnect the filter circuit (120) from the current path (L, N) of the motor (36) responsive to deactivation of the motor (36).

9. The automatic door operator (30) of claim 7 or 8, wherein the controller (32) is further configured to cause connecting and/or disconnecting of the filter circuit (120) to/from the current path (L, N) of the motor (36) based on a voltage amplitude (Vac) of the AC power source (10).

10. The automatic door operator (30) of claim 9, wherein the controller (32) is further configured to cause connecting and/or disconnecting of the filter circuit (120) to/from the current path (L, N) of the motor (36) responsive to the voltage amplitude (Vac) of the AC power source (10) being below an activation threshold (VI, V2).

11. An electromagnetic interference, EMI, reducing method (200) of operating an entrance system (1) comprising an automatic door operator (30) and a movable door member (DM1, . . ., DMm), the automatic door operator (30) comprising a motor (36) powered by an AC power source (10), the method (200) comprises: obtaining (210) a request indicating activation of the motor (36) for causing movement of the movable door member ((DM1, . . ., DMm); and, in response thereto, connecting (220) a filter circuit (120) of a controllable EMI circuit (100) of the entrance system (1) to a current path (L, N) of the motor (36).

12. The method (200) of claim 11, wherein connecting (220) the controllable EMI circuit (100) further comprising: obtaining (222) a voltage amplitude (Vac) of the AC power source (10), and responsive to the obtained voltage amplitude (Vac) being below an activation threshold (VI, V2), controlling a switch device (110) of the controllable EMI circuit (100) to connect the filter circuit (120) to the current path (L, N) of the motor (36).

13. The method (200) of claim 11 or 12, further comprising: obtaining (230) a request indicating deactivation of the motor (36); and, in response thereto, disconnecting (240) the filter circuit (120) of the controllable EMI circuit (100) of the entrance system (1) from the current path (L, N) of the motor (36).

14. The method of claim 13, wherein disconnecting (240) the switch device (110) further comprising: obtaining (242) a voltage amplitude (Vac) of the AC power source (10), and responsive to the obtained voltage amplitude (Vac) being below an activation threshold (VI, V2), controlling the switch device (110) of the controllable EMI circuit (100) to disconnect (244) the filter circuit (120) from the current path (L, N) of the motor (36).

15. The method of any one of claims 11 to 14, wherein the automatic door operator (30) is the automatic door operator (30) according to any one of claims 1 to 10.

16. An entrance system (1) comprising a movable door member (DM1, . . ., DMm) and an automatic door operator (30) according to any one of claims 1 to 10 configured to control a position of the movable door member (DM1, . . ., DMm).