ELECTRONIC SWITCH WITH N-CONDUCTION

Description

[0001] The invention relates to an electronic switch for electrical installation technology, comprising a first electrical connection for connecting an L-phase conductor of an alternating voltage of a power supply network, a second electrical connection for connecting an electrical load, a third electrical connection for connecting an N-conductor of the alternating voltage of the power supply network, an electronic switching device at least for switching the load between an on-state and an off-state, an electronic control for controlling the switching device, and a self-supply switching electronics with an internal self-supply voltage for control using a load current flowing through the load, wherein the electronic switching device comprises a diode bridge consisting of two discrete diodes and two MOSFET body diodes.the third electrical connection is connected to the self-supply switching electronics via a fifth diode in the forward direction.

[0002] These electronic switches are intended primarily as replacements for conventional electromechanical switches in building electrical installations. The latter often operate using two-wire technology, meaning they are connected between the live (L) conductor of the AC power supply (e.g., 230 V, 50 Hz in Europe) and a separate conductor to the load. In a conventional building installation, therefore, the switch boxes at the mounting point often only contain these two wires and no neutral (N) conductor. With such a two-wire electromechanical switch, the current through the load, and thus also through the switch, is zero in the OFF state. In the ON state, the voltage drop across the switch is zero. Both of these states are therefore unsuitable for the necessary self-supply voltage of an electronic switch.Therefore, the electronic switch must be supplied with an operating DC voltage for the switching electronics of the switch, depending on the load current of the load to be switched.

[0003] For the purposes of the invention, the "switched-on state" of the load means that at least enough voltage drops across the load for a person to perceive the load as switched on (i.e., not necessarily the entire voltage across the load). Similarly, the "switched-off state" of the load, for the purposes of the invention, means that at most enough current flows through the load for a person to still perceive the load as switched off (i.e., not necessarily no current flows through the load).

[0004] Electronic switches for two-wire systems are well-known; these draw their own power from the connected load using phase-cut dimming, similar to an electronic dimmer. When the switch is off, a significant portion of the input AC voltage drops across the switch. As a prerequisite, the connected load must still allow a small current flow even when off (without noticeably switching to the on state), meaning the load must not have an ideally high resistance when off. This is generally the case for most conventional loads in a building's electrical installation; however, the amount of current allowed (and remaining imperceptible) even when off varies considerably depending on the type and size of the load.

[0005] While larger incandescent bulbs (resistive load) can tolerate several milliamperes of current when switched off without causing undesirable, human-perceived flickering, newer LED lamps (capacitive load) with low power ratings (< 10 W), which allow only a few hundred microamperes when switched off, can lead to undesirable lighting conditions such as flickering and / or glowing. When the switch is off, i.e., with a high resistance, the entire voltage drop across it is minimized. The switch uses this voltage drop for its own power supply, but the current draw must not exceed the potentially small permissible current flow through the load.

[0006] When the switch is on, i.e., with the lowest possible resistance, as little voltage as possible drops across it, in order to provide full power to the load. To nevertheless ensure continued self-sufficiency, the switch is briefly and cyclically switched off. This causes a (brief) voltage drop across it, allowing the load to draw current again. The time interval for these switches is chosen so that the load disconnection is imperceptible to the human eye, effectively keeping the load in the "on" state.

[0007] In conventional electronic switches, cyclical switching typically occurs via a phase-cut or phase-off switch in each half-cycle of the mains voltage (dimmer principle). This principle works very well with purely resistive loads (ideal sinusoidal waveform of the load current), but disadvantages arise with inductive or capacitive loads, which can lead to malfunctions and, in extreme cases, to the destruction of the electronic switch.

[0008] Switching off (or briefly switching off, as in dimming) an inductive load, such as a low-voltage halogen light with a transformer, can generate very high overvoltages if the switch-off does not occur precisely at the zero crossing of the current. Therefore, phase-angle control should be used with inductive loads. Interference on the household electrical system makes it difficult to determine the zero crossing.

[0009] Switching on (or briefly switching on, as in dimming) a capacitive load, such as LED lights or electronic transformers, can generate very high current peaks due to the pulsed current draw at the peak of the mains voltage, unless the switch-on occurs precisely at the zero crossing of the voltage. Therefore, the phase-cut principle should be used when dealing with capacitive loads. However, the rapid, pulsed current waveform of a capacitive load makes determining the optimal switching-on time difficult.

[0010] Switching mixed loads with inductive and capacitive components on and off (or short-term switching on and off, as in dimming) is particularly problematic because the requirements for the switch or dimmer are contradictory. With common electronic switches, a mode for resistive, inductive, or capacitive loads can be manually selected, allowing switching between leading-edge and trailing-edge phase control.

[0011] Furthermore, another problem exists: the brief power interruption in each power phase visibly and permanently reduces the brightness of a connected lamp load. This dimming is more pronounced the longer the load is switched off during each power phase. With large loads, a very brief interruption is usually sufficient to power the electronic switch's control unit. Consequently, the dimming is minimal. However, with very small loads, which are now very common in the form of energy-saving LED lighting, it may be necessary to switch off or "dim" the light for a longer period during each power phase. The resulting significant reduction in the brightness of a lamp load is undesirable. With extremely small loads, e.g.,For LED lamps smaller than 10 W, even switching them off for the entire mains phase is often not enough to supply the switch with sufficient current, as the small load cannot supply this current in the "off" state.

[0012] For known electronic switches for two-wire technology with a dimmer function, whose power supply in a two-wire connection relies exclusively on the phase-cut or phase-angle control, the problem arises that the load cannot be switched on 100% of the time, as the dimmer electronics must be continuously supplied with a certain current. This prevents a connected light source from operating at full brightness. Instead, during each mains half-cycle, the load must be switched off, i.e., dimmed further, for a specific minimum period to ensure sufficient voltage is available to power the dimmer's own electronics. Consequently, with such a dimmer, the theoretically possible maximum brightness of, for example, a connected light source can never be achieved.

[0013] For self-sufficiency when switched off, a so-called offline switching regulator is typically used. This regulator can convert the relatively high mains voltage into a significantly lower voltage for self-sufficiency, thus drawing only a small amount of current from the mains. However, these switching regulators require a relatively high minimum input voltage for proper operation, for example, in the range of 40 to 70 volts. Consequently, the necessary phase-cut or phase-angle control for self-sufficiency cannot be performed at the lowest possible mains voltage, e.g., near the zero crossing, to minimize the impact on the load. Instead, dimming must occur at a correspondingly higher voltage. If, for example, a connected light source is required to operate at full power, this results in a significant reduction in brightness.

[0014] From EP 1 121 001 B1, an electronic switch for switching loads with low or high impedance, such as incandescent lamps or fluorescent lamps, is known. This switch comprises a controllable switching device for turning the load on or off, with at least one switching element connected in series with the load, and a power supply for internal self-powering of the switch from the AC mains by means of a buffer capacitor that can be recharged via the load. A control circuit controls the switching device, wherein a recharging initiator of the control circuit triggers a recharging process of the buffer capacitor for self-powering at time intervals adapted to the internal energy demand when the load is switched on. During each recharging process, the switching device is briefly activated to switch off, and an operating DC voltage is obtained via an alternative current path.Furthermore, the control circuit for self-supply when the load is switched off includes an additional high-impedance current source consisting of three transistors and five resistors. In certain cases, this current source causes an excessively high quiescent current with particularly small loads (e.g., LED lamps smaller than 3 W), causing them to be switched on even when the switch is off. This is especially problematic if the switch electronics also have to power their own signal LEDs or a radio receiver. As a result, the current draw can increase into the milliampere range, causing the load current to become so high, even when a small load is switched off, that the load appears to be switched on or is at least in an undesirable, undefined state.

[0015] A disadvantage is that the operating DC voltage for the control system is supplied directly via the buffer capacitor. This means the permissible voltage range (usually between 2 V and 5 V) across the buffer capacitor is relatively narrow and directly dependent on the control system, thus limiting the recharging options. At the same time, the buffer capacitor must also be designed for the maximum load current, as recharging can sometimes occur at the peak of the load current. This must be taken into account for particularly high loads, such as incandescent lamps > 300 W.

[0016] Furthermore, the operating DC voltage across the buffer capacitor is monitored and regulated by a microprocessor to calculate the charging intervals. With very small loads and unfavorable current draw, it can be very difficult for the microprocessor to determine the correct moment to charge or stop charging the buffer capacitor. With very large loads, the capacitor recharges extremely quickly, and the microprocessor, possibly also engaged in other functions, can miss the correct moment to stop charging, potentially damaging the capacitor.

[0017] Electronic switches typically offer the option of operating with two-wire technology and, if a neutral conductor is available at the connection point, also the possibility of connecting the neutral conductor and using it for direct power supply from the mains (three-wire connection). One would expect that no current would flow through the load connected to the electronic switch when it is switched off. However, it has been found that this is not the case with electronic switches or dimmers that have their own power supply electronics and are powered via the neutral conductor. Even when switched off, a relatively small current, particularly less than 500 µA, flows through the load. This current may be significant for extremely small loads.

[0018] This can occur in the exemplary embodiment of the electronic switch if the positive half-wave of the AC mains voltage is present at the first electrical terminal of the L-phase conductor and the primary switch is in the off state. In this case, current can flow from the L-phase conductor through a discrete diode to the self-powered switching electronics and from there back via a body diode of a MOSFET to the second electrical terminal and through the load. This can lead to undesirable effects such as flickering, flashing, or glowing when the switch is off, especially with relatively low lamp loads, particularly less than 3 W.

[0019] EP 3 322 080 A1 relates to a dimmer with a pre-regulator that can automatically detect whether it is connected in a 2-wire or 3-wire configuration. The dimmer also includes a switching unit and a DC power supply. The pre-regulator consists of a controllable resistor, a sensor, and a microcontroller unit. The sensor measures the current between a switch terminal and a DC terminal. The microcontroller uses this measurement data to determine the connection type (2-wire vs. 3-wire). Depending on the connection type, the resistance value is automatically adjusted to prevent undesirable effects such as LEDs glowing in 2-wire mode. In a 3-wire application, the charging current for the dimmer's DC supply is routed via the neutral conductor. For this purpose, an additional diode branch is integrated, the anode of which is connected to the neutral conductor and the cathode of which is connected to the DC terminal.This allows the charging capacitor to be charged directly via the neutral wire.

[0020] Application EP 3 471 246 A1 discloses a self-powered electronic fuse (eFuse) consisting of only two externally accessible terminals and characterized by a compact, battery-free architecture. It is suitable for use in AC networks for current-limiting protection of loads, e.g., in overcurrent conditions or for reducing inrush currents. The fuse features two switches in the main current path, four diodes for creating charging paths, a storage capacitor for powering the control electronics, a current-limiting charging unit, and a complex control circuit concept for state monitoring, including current and voltage sensing.

[0021] The invention is based on the objective of providing an electronic switch for two-wire connection technology with self-supply switching electronics, which improves the behavior for relatively low loads in the switched-off state when powered via the N conductor with a 3-wire connection.

[0022] The problem is solved according to the invention by the features of the characterizing part of claim 1.

[0023] The self-supply switching electronics are connected to the third electrical terminal for the neutral conductor via a sixth diode in the forward direction of the positive half-wave of the AC voltage, and a tertiary switch is arranged in series with the sixth diode between the third electrical terminal for the neutral conductor and the self-supply switching electronics, wherein, in the off state of the switch, the control unit makes the connection between the third electrical terminal for the neutral conductor and the reference ground conductive by means of the tertiary switch, so that a quiescent current during the positive half-wave of the mains supply can flow from the first terminal of the live conductor towards the third terminal for the neutral conductor and does not flow through the load L.and when the switch is on, the open (high-resistance) tertiary switch can prevent a short-circuit current from the first terminal of the L phase conductor via the reference ground to the third terminal of the N neutral conductor.

[0024] The tertiary switch thus makes it possible to completely de-energize the load when switched off, using a neutral conductor. This allows for an electrical switch that can utilize the advantages of a neutral conductor connection, provided one is available in the mounting opening of the electronic switch.

[0025] The tertiary switch comprises, in particular, a P-channel MOSFET switching element or a PNP transistor. Advantageously, the tertiary switch is controlled via a voltage converter, especially an inverting charge pump. Particularly advantageously, the inverting charge pump includes a maximum of two capacitors. This enables a particularly simple and cost-effective control of the tertiary switch while simultaneously providing a sufficient voltage level for driving a P-channel MOSFET switching element.

[0026] In an advantageous embodiment of the self-powered switching electronics, a primary switch of the switching device is arranged between the first and second terminals in a first current path. Furthermore, a secondary switch of the switching device is arranged in a second current path parallel to the first current path. Additionally, a high-impedance switching regulator is arranged in a third current path in parallel to the secondary switch. A low-impedance energy storage device is arranged in series with the secondary switch and the switching regulator, in parallel to the first current path. Both the switching regulator and the energy storage device serve to provide the self-power supply voltage for the control system.

[0027] The switching regulator is preferably a so-called "offline switching regulator" with low current consumption and, in particular, with input voltages of up to 400 V. Especially at low currents of < 5 mA, the switching regulator has an effective turns ratio of approximately 10 to 20, so that, for example, with a current requirement of 2 mA for the switching electronics with, for example, a radio receiver, the current draw from the mains and thus via the load is between 100 µA and 200 µA.

[0028] In an advantageous embodiment, the controller permanently switches off the primary and secondary switches when switched off. This allows the switching regulator to provide its own supply voltage via the third current path. When switched on, the controller switches on the primary and secondary switches. This means that, initially, the full AC voltage from the mains supply is available to the load, and the energy storage device alone provides its own supply voltage to the controller, rather than the switching regulator. If the supply voltage falls below a minimum threshold when switched on, the controller switches off the primary switch. This allows a portion of the mains AC voltage to be used to charge the energy storage device.When a maximum supply voltage is reached in the switched-on state, the control unit switches the primary switch back on, making the full AC voltage available again for the load.

[0029] This ensures, in particular, that when switched on for the purpose of recharging (i.e., switching from the first current path to the second current path), the load current is never interrupted, but rather, due to the small voltage drop across the switch, only reduced relatively slightly. This prevents, in particular, an undesirable reduction in brightness with small loads, e.g., LED lamps smaller than 10 W, which would occur especially with a pure phase-cut control for charging the energy storage device.

[0030] Furthermore, this allows the voltage across the load to be reduced only minimally during recharging while the load is switched on. This means that, theoretically, switching the load current from the first to the second current path and back again can occur at any time without significant current spikes in the capacitor of a capacitive load. In this way, the capacitive load is protected.

[0031] The primary and secondary switches are preferably implemented as N-channel MOSFETs. This allows for a relatively slow switching from the primary to the secondary current path, preventing rapid changes in the load current and consequently preventing overvoltage from being generated by the inductive load. If an inductive load were switched off while a certain amount of current was still flowing, especially at high speed, very high voltage spikes would occur, potentially damaging any connected electronics.

[0032] The switch according to the invention has the advantage, particularly with mixed loads (inductive and capacitive), that both the loads and the switch can be operated more gently. In particular, further precautionary measures, such as so-called "snubbers" or varistors, can be dispensed with.

[0033] In particular, the use of the switching regulator allows the required current flow to be minimized when the switch is off, so that even very small capacitive loads remain switched off despite the switch's own power supply.

[0034] The control system preferably includes a microprocessor that controls the switches of the switching device via output signals.

[0035] In a further advantageous embodiment of the invention, a voltage regulator is arranged between the self-supply voltage and the control system and is connected both to the energy storage device and, in parallel, to the switching regulator. This stabilizes the self-supply voltage at a value ideal for the control system. This allows the permissible voltage range at the energy storage device to be increased, which expands the selection of usable energy storage devices and makes the control of the switching intervals of the secondary switch more flexible.

[0036] In one possible embodiment, the voltage regulator reduces the self-supply voltage to a relatively lower supply voltage, in particular 3.3 V, for the control system. Therefore, the self-supply voltage at the energy storage device can be relatively high, in particular at least 10 V up to a maximum of 40 V. This makes it easier for the control system to determine a suitable time to end the recharging process for the energy storage device. In particular, the energy storage device can be charged more quickly. Furthermore, the control system's reaction time to prevent overcharging of the energy storage device can be extended, allowing for a different design of the control system's processing power.

[0037] In a possible alternative embodiment, the voltage regulator boosts the self-supply voltage to a relatively higher supply voltage for the control system. In this case, the self-supply voltage at the energy storage device can be relatively low, particularly between 1 V and 2 V. Preferably, in this case, a further switching regulator is operated in conjunction with the voltage regulator, which generates the supply voltage, preferably 3.3 V, for the control system. This minimizes the voltage drop across the switch, so that with particularly small loads, such as 3 W LED lamps, flickering can be minimized or avoided even with an unfavorable choice of charging intervals by the control system.

[0038] In a further embodiment of the invention, an independent limiting electronics circuit, when a maximum supply voltage of the self-supply is exceeded, forcibly switches on the primary switch independently of the control system. This serves as a particularly simple protective circuit to prevent damage to the energy storage device if the control system cannot complete a charging cycle quickly enough due to insufficient reaction time.

[0039] Advantageously, depending on the type of connected load, for example with complex loads (multiple connected LED lamps with different power ratings, e.g., from 3 W to 100 W) or very small resistive loads, the switching regulator can also provide a phase-cut / phase-angle self-supply even when switched on. The switching regulator converts the relatively high voltage drop across the switch during phase-cut operation into the required supply voltage for the control system. For this purpose, the control system permanently switches off the secondary switch and switches off the primary switch at correspondingly short intervals within a mains phase.With such an optional combination with a phase-cut dimming self-supply, a simple dimmer function can be provided in particular, whereby the combination with the second current path makes the full voltage available for the load in the switched-on state, so that maximum brightness can be achieved, which is not the case with conventional dimmers with phase-cut control.

[0040] Preferably, the electronic switch comprises a first detection element that determines the magnitude and / or phase of the load current. In particular, the primary switch comprises two separate switches connected in series, which are preferably switched on and off together when changing between the on and off states. The switches are preferably each configured as an N-channel MOSFET. Advantageously, a shunt resistor is connected in series between the series-connected switches of the primary switch as a first detection element for measuring the load current, wherein the voltage drop across the shunt resistor is fed as an input signal to the control circuit, in particular to an analog-to-digital converter of the microprocessor.

[0041] In a further advantageous embodiment, the current self-supply voltage is measured by a second detection means and is directed to an A / D converter of the control microprocessor.

[0042] In particular, the electronic switch has a third detection means which determines the level and / or phase angle of the alternating voltage of the power grid.

[0043] The detection of all currents and voltages is possible using either an analog-to-digital converter (ADC) or a comparator, with the respective threshold being set using an ADC. The method actually used depends on the capabilities of the specific microprocessor employed.

[0044] Preferably, the third electrical connection for the neutral conductor is connected to an input of the switching regulator via the fifth diode. In particular, a reference ground of the energy storage device and the switching regulator is connected to the third electrical connection for the neutral conductor via the sixth diode and the tertiary switch. This allows for the simple integration of the fifth and sixth diodes and the tertiary switch for connecting the neutral conductor into the advantageous embodiment of the self-supply switching electronics described above. Thus, when the switch is on, the load is connected in parallel to the energy storage device and the switching regulator, which are connected to the AC voltage via the first connection for the live conductor (L) and the third connection for the neutral conductor (N). Therefore, the full AC voltage is always present at the load when switched on, independent of the voltage drop across the energy storage device or the switching regulator.

[0045] In the advantageous embodiment of the electronic switch, the third detection means can also detect the connection of a neutral conductor to the third electrical terminal of the electronic switch.

[0046] In a further embodiment, the electronic switch according to the invention offers the possibility of using it as a dimmer with a phase-cut or phase-angle control function, e.g., to regulate the brightness of a connected light source. When the electronic switch according to the invention is used in its alternative function as a dimmer with a 2-wire connection, the disadvantage of dimmers with conventional circuitry described above is eliminated. In dimming mode, it can draw power from the voltage drop across it when a phase-cut or phase-angle change is performed via the primary switch during each mains half-cycle. However, the secondary switch, and thus the second current path, remains closed; the switch regulator provides its own power supply. If the desired dimming level approaches the maximum brightness value, for example, below 10% of the maximum dimming level, a [missing information] should be [missing information].If the connected light source is operated at full brightness, the switch function according to the invention is activated instead of dimming further.

[0047] The self-power supply is generated from the load current via the secondary switch and the second current path, as described elsewhere. If the primary switch, and thus the first current path, is switched off, the secondary switch, and thus the second current path, briefly takes over the load current, with only a minimal reduction in the voltage across the load. The load is supplied with power throughout both mains half-cycles and, if implemented as a light source, for example, achieves significantly better utilization of the maximum possible brightness.

[0048] Advantageously, the primary switch has two separate switches connected in series, which are switched on and off with a slight time delay during dimming, in particular with a maximum of 1 ms. This can be advantageous with inductive loads, reducing voltage spikes during the switching-on or switching-off process.

[0049] A key advantage is that the switch according to the invention can be identical for both functions, switching and dimming. The primary switch is preferably a series connection of two MOSFETs suitable for both phase-on and phase-off operation. The switching regulator, which provides its own power supply when connected via a 2-wire connection in the off state, can ensure the power supply to the electronics during dimming in phase-on or phase-off modes. The secondary switch, or the second current path, allows the circuit to function advantageously in dimmer mode at maximum setting without significant loss of brightness from, for example, a connected light source. The specific function performed by the electronics described here—whether as a switch, dimmer, or a combination—can be determined by a suitable control method.

[0050] Further advantageous embodiments of the invention will become apparent from the following description of the figures and the dependent subclaims.

[0051] They show: Fig. 1 a systematic representation of an exemplary first embodiment of an electronic switch with self-supply switching electronics, Fig. 2 an exemplary electronic circuit for an extension of the self-supply switching electronics with limiting electronics and buffer comparator, Fig. 3 a systematic representation of an electronic switch according to the invention with a third connection for a neutral conductor, Fig. 4 an exemplary electronic circuit for monitoring the load current, and Fig. 5 an exemplary electronic circuit for a detection means for determining the magnitude and / or phase angle of the AC voltage of the power grid.

[0052] In the various figures of the drawing, identical parts are always labelled with the same reference symbols.

[0053] In Fig. 1 This is a systematic representation of a possible first embodiment of an electronic switch 1 for electrical installation technology with a 2-wire connection and self-powered switching electronics. This serves to illustrate the functionality of self-powered switching electronics. The features according to the invention regarding the use of a third electrical connection for the neutral conductor are described in the following. Fig. 3 and the description that follows later.

[0054] The exemplary electronic switch 1 has a first electrical terminal A for connecting an L-phase conductor of an AC voltage UN of a power supply network and a second electrical terminal B for connecting an electrical load L. Furthermore, the electronic switch 1 has an electronic switching device for switching the load L between an ON state and an OFF state. Additional functions, such as dimming of the load L, may also be provided. The electronic switch 1 also has an electronic control SE for controlling the switching device. Additionally, the electronic switch 1 has means for an internal self-supply voltage UE for the control SE, using a load current IL flowing through the load L.

[0055] Between the first terminal A and the second terminal B of the electronic switch 1, a primary switch S1 of the switching device is arranged in a first current path I1. Furthermore, between the first terminal A and the second terminal B, a secondary switch S2 of the switching device is arranged in a second current path I2, which is parallel to the first current path I1. In the second current path I2, a rectifier G, preferably consisting of four diodes D1, D2, D3, and D4 as shown, is arranged. Preferably, two diodes D2 and D4 are formed from the body diodes of the primary switch S1, which is advantageously designed by two MOSFET transistors. Additionally, a high-impedance switching regulator SR for providing the self-supply voltage UE is arranged in a third current path I3, parallel to the secondary switch S2.An energy storage device C is connected in series with the secondary switch S2 and in series with the voltage output of the switching regulator SR, and in parallel with the first current path I1. The energy storage device C is preferably designed as a low-resistance buffer capacitor, as shown. The energy storage device C and the switching regulator SR are also connected to ground (GND). Ground (GND) is specifically connected to the negative terminal of the rectifier G.

[0056] In the advantageous embodiment shown, a voltage regulator UR is arranged between the self-supply voltage UE and the controller SE. The voltage regulator UR is connected to the energy storage device C and, in parallel, to the voltage output of the switching regulator SR. In a first possible embodiment, the voltage regulator UR reduces the self-supply voltage UE to a relatively lower supply voltage U SE for the controller SE. In an alternative embodiment, the voltage regulator UR increases the self-supply voltage UE to a relatively higher supply voltage U SE for the controller SE.

[0057] The control unit SE includes, in particular, a microprocessor which controls the switches, especially the primary switch S1 and the secondary switch S2, of the switching device via output signals. As shown, the primary switch S1 includes, in particular, two separate switches S1a and S1b connected in series, which are preferably switched on and off together when changing between the on and off states.

[0058] In the advantageous embodiment shown, a first detection means is provided which can determine the magnitude and / or phase angle of the load current IL in the first current path I1. For this purpose, a shunt resistor SH is connected in series between the series-connected switches S1a and S1b of the primary switch S1 to measure the portion of the load current IL flowing through the first current path I1 via the control unit SE. The voltage drop USH across the shunt resistor SH is fed to the control unit SE as an input signal. Additionally, the self-supply voltage UE is fed to the control unit SE as an input signal via a second detection means.

[0059] In the Fig. 1In the advantageous embodiment shown, a limiting electronics BE independent of the control unit SE is designed, which, at a maximum supply voltage U Emax, uses the current self-supply voltage UE to forcibly switch on the primary switch S1 independently of the control unit SE. This protects the energy storage device from overcharging.

[0060] Fig. 2Figure 1 shows an advantageous embodiment and possible integration of such limiting electronics BE. The limiting electronics BE comprise, in particular, a limiting transistor T1, a Zener diode DZ, and two resistors R1 and R2. By appropriately setting the Zener voltage of the Zener diode DZ, when the current self-supply voltage UE is exceeded by a maximum supply voltage U Emax, a switching transistor T2 is driven with the output signal O BE of the limiting electronics BE. This then outputs the output signal O S1 to the primary switch S1, thereby closing the primary switch S1. Alternatively, a simple voltage divider made of resistors could be used, but in this case, a current would constantly flow through the resistors of the voltage divider.Current only flows through the Zener diode DZ once the Zener voltage is exceeded; otherwise, the arrangement advantageously consumes only a negligible current, in particular a current < 1 µA. Simultaneously, the switching transistor T2 can also be controlled by transistor T3. Transistor T3 is directly driven by the controller SE with the output signal O S3, so that the switching transistor T2 forwards the output signal O S1 to the primary switch S1.

[0061] Furthermore, it shows Fig. 2In particular, an advantageous integration of a buffer comparator K1 and a digital-to-analog converter D / A. The self-supply voltage UE of the energy storage device C is compared with a threshold value SW1 by means of the digital-to-analog converter D / A, and the result is output at the buffer comparator K1. Preferably, the threshold value SW1 is determined by the controller SE, and the result is transmitted to the controller SE at the buffer comparator K1.

[0062] The buffer comparator K1 is used primarily during recharging. It detects the lowest charge level of the energy storage device C at a low threshold value SW1. As soon as this is reached, recharging must begin as quickly as possible. The self-supply voltage UE from the energy storage device C, which is fed to the buffer comparator K1, is divided by a ratio of 1 / 3, for example. With a minimum permissible charge of the energy storage device C of approximately 4V, the threshold value SW1 of the buffer comparator K1 is set accordingly to approximately 1.3V, for example.

[0063] Fig. 3 Figure 1 shows an embodiment of an electronic switch according to the invention, with a third electrical connection N for connecting a neutral conductor. A large part of the components shown in Figure 2 are... Fig. 1The electronics described here are simplified and summarized as self-supply switching electronics (ESE). However, the invention is not limited to the described embodiment of the self-supply switching electronics (ESE), but can also be combined with another implementation of a self-supply switching electronics (ESE).

[0064] The terminal N is connected via a diode D5 in forward direction, in particular in the forward direction of the negative half-wave of the AC voltage UN, to the inputs of the self-supply switching electronics EV, in particular according to Fig. 1connected to the input of the switching regulator SR. Advantageously, the reference ground GND of the energy storage device C and the reference ground GND of the switching regulator SR are also connected to terminal N via a diode D6 in the forward direction, specifically in the forward direction of the positive half-wave of the AC voltage UN. Thus, in the ON state, the load L is connected in parallel to the self-supply switching electronics EV, which are connected to the AC voltage UN via terminals A and N. Therefore, the full AC voltage UN is always present at the load L in the ON state, making it independent of the self-supply switching electronics EV. To completely de-energize the load L in the OFF state, the connection between terminal N and the reference ground of the self-supply switching electronics EV is advantageously interrupted by a tertiary switch S3.A conductive connection is established between the reference ground (GND) of the energy storage device C and the reference ground (GND) of the switching regulator SR. This allows for the provision of an electrical switch that can utilize the advantages of a neutral conductor connection, provided one is available in the mounting opening of the electronic switch. The tertiary switch S3 is advantageously of the P-channel type (MOSFET or transistor) and therefore requires a negative control voltage. A voltage converter CV converts the positive self-supply voltage UE of the self-supply EV into a negative voltage for controlling the tertiary switch S3. The voltage converter CV is specifically designed as an inverting charge pump. Advantageously, the inverting charge pump comprises a maximum of two capacitors.

[0065] Fig. 4Figure 1 shows an advantageous embodiment and possible integration of a load current monitoring system, particularly using the first detection means already described above. The load current monitoring system specifically includes a load current comparator K2 and a digital-to-analog converter D / A. The digital-to-analog converter D / A compares the portion of the load current IL flowing through the first current path I1 with a threshold value SW2, and the result is output at the load current comparator K2. Preferably, the threshold value SW2 is set by the controller SE, and the result is transmitted to the controller SE at the load current comparator K2. Furthermore, the load current monitoring system includes an analog-to-digital converter A / D, which converts the portion of the load current IL flowing through the first current path I1 from analog to digital and transmits it to the controller SE, so that the phase or zero crossing of the load current IL can be detected by the controller SE.The voltage measured by the first detection device is amplified, in particular via an operational amplifier, and transmitted to the load current comparator K2 and / or the analog / digital converter A / D.

[0066] The low threshold SW2 of the load current comparator K2 during recharging is advantageously used to detect a zero crossing of the load current IL. Theoretically, at the zero crossing, the voltage across the shunt resistor SH, and therefore also across the load current comparator K2, is 0V. However, the threshold SW2 is set to a slightly higher value, e.g., a few millivolts. This serves two purposes: firstly, to suppress disturbances around the zero point, and secondly, to compensate for delays caused by program execution times. In effect, the time just before the zero crossing is determined. The controller SE then has some time to react in order to subsequently hit the actual zero crossing as accurately as possible. Switching off the primary switch S1 also requires a certain amount of time. The comparator threshold SW2 of the load current comparator K2 allows the time between detection and the actual zero crossing to be adjusted depending on the detected load type.

[0067] Fig. 5Figure 1 shows an exemplary embodiment of a third detection element of an electronic switch according to the invention for determining the magnitude and / or phase of the AC voltage UN of the power grid. The third detection element is preferably arranged in series at the output of the rectifier, in particular after diodes D1 and D3 of the rectifier, and provides a signal OS4 for the control SE. The signal OS4 is, in particular, routed to an analog-to-digital converter (ADC) of the microprocessor. For this purpose, the third detection element comprises two current-limiting resistors R3 and R4 connected in series, with the signal OS4 for the control SE being tapped between the two resistors R3 and R4. Furthermore, another diode D7 is arranged between the third detection element and the switching regulator SR, which blocks current from the switching regulator towards the third detection element or towards ground GND.Diode D7 decouples, in particular, the voltage-buffered input of the switching regulator SR from the signal O S4, since the buffered voltage would otherwise be superimposed on the zero crossings. The third detection means can, in particular, be implemented in an embodiment without a third connection N for a neutral conductor, for example according to [reference missing]. Fig. 1 , or also in an embodiment with a third connection N for a neutral conductor, for example according to Fig. 3 ...be trained.

[0068] In the advantageous embodiment of the electrical switch according to Fig. 3With an additional neutral conductor (N-conductor), a signal OS5 for control SE is preferably provided downstream of diode D5, which is located downstream of the N-conductor terminal. The signal OS5 is, in particular, routed to an analog-to-digital converter (ADC) of the microprocessor. For this purpose, the third detection element comprises two current-limiting resistors R5 and R6 connected in series downstream of diode D5, which is located downstream of the N-conductor terminal. The signal OS5 for control SE is tapped between the two resistors R5 and R6. Furthermore, another diode D8 is arranged between the third detection element and the switching regulator SR. This diode blocks current from the switching regulator towards the third detection element and towards ground (GND). Diode D8 decouples, in particular, the voltage-buffered input of the switching regulator SR from the signal OS5, since the buffered voltage would otherwise be superimposed on the zero crossings.This means that, in addition to the level and / or phase angle of the alternating voltage UN, the third detection means that the connection of a neutral conductor can also be detected and the control sequence for self-supply can be adjusted accordingly.

[0069] The electronic switch 1 has an actuating element that can be operated by a person. The actuating element can be, for example, electromechanical or electronic in the form of a rocker switch or push button, electrostatic in the form of an electrostatic sensor, optical in the form of a camera or an IR sensor, or acoustic in the form of a microphone. The control unit SE detects the current state and / or a change in the state of the actuating element and assigns a meaning to it, for example, the switched-on state ON or the switched-off state OFF.

[0070] To switch the electronic switch on or off, it is advantageous to first detect the actuation of the actuating element and, depending on the current state, decide whether to switch on or off.

[0071] The following describes advantageous methods or a preferred control sequence in the controller SE. The control sequence is preferably implemented as software in the controller SE and is executed repeatedly in a control loop: In the OFF state of the electronic switch, the controller SE has permanently switched off the primary switch S1 and the secondary switch S2, so that the switching regulator SR provides the self-supply voltage UE via the third current path I3.

[0072] When the electronic switch transitions from the OFF state to the ON state, the SE control unit first switches on the primary switch S1 and the secondary switch S2.

[0073] In particular, the primary switch S1 is switched on first, followed by the secondary switch S2. Preferably, the control unit SE waits until the AC voltage UN is at its zero crossing before switching on the secondary switch S2 and the primary switch S1. Advantageously, a timer is synchronized to the mains voltage phase. The third detection method described above is used to determine the zero crossing of the AC voltage UN.

[0074] The load L is supplied with the full AC voltage UN, and the energy storage device C, previously charged by a charging process described below, provides the self-supply voltage UE for the control unit SE. If the supply voltage UEmin at the energy storage device C falls below a minimum, the control unit SE switches off the primary switch S1, so that a small portion of the AC voltage UN is used to charge the energy storage device C, while the larger portion of the AC voltage UN continues to supply the load L until a maximum supply voltage UEmax at the energy storage device C is reached. At this point, the control unit SE switches the primary switch S1 back on, so that the load L is again supplied with the full AC voltage UN. The second detection method described above is used, in particular, to determine whether the maximum supply voltage UEmax has been reached.

[0075] In the event of a transition from the ON state to the OFF state, the controller SE preferably first checks whether the energy storage device C is sufficiently charged, i.e., in particular whether the current self-supply voltage UE corresponds to the maximum supply voltage UEmax. This allows any potential delay of the switching regulator SR in generating a voltage in the OFF state to be overcome. If the energy storage device C is not sufficiently charged, it is first recharged in a recharging sequence described below.

[0076] When the energy storage device C is sufficiently charged, the secondary switch S2 and the primary switch S1 are switched off, thus completing the transition to the OFF state. Specifically, the secondary switch S2 is switched off first, followed by the primary switch S1. Preferably, the control unit SE waits until the load current IL is at zero crossing before switching off the secondary switch S2 and the primary switch S1. For this purpose, the control unit SE uses, in particular, the first detection means described above. In a further advantageous embodiment, the secondary switch S2 is switched off first, and the primary switch S1 is only switched off when the load current IL reaches zero crossing.

[0077] In an advantageous embodiment, the control unit SE performs load detection to determine the load type, in particular whether the load L is resistive, inductive, or capacitive, and / or its magnitude. Based on the determined load type, a recharging strategy optimized for that load type can be selected during the recharging process described below. In a preferred embodiment of the load detection, a phase shift between current and voltage is detected by the detection means one and three, thereby determining the load type. Load type detection can be performed, in particular, only once when the switch is first turned on with the load connected, or with each turn-on to detect load changes in the OFF state.

[0078] The following describes a preferred load detection procedure: During load detection, at least the primary switch S1, and thus the load L, is switched on. Specifically, the threshold SW2 of the load current comparator K2 is first set to a low threshold. Advantageously, "low threshold" refers to a value that small loads L, particularly those of 50 W or less, do not exceed. These small loads L are treated differently during recharging than larger loads L, so that the energy storage device C is not only recharged when it is almost empty.

[0079] Preferably, the probability of the presence of a capacitive load L is determined. In particular, it is determined whether the current draw is continuous and uniform over the mains phase, or rather only short or intermittent at the peak of the mains voltage. If this is the case, a capacitive load is assumed.

[0080] For this purpose, the duty cycle of the load current IL is determined in particular from the digital load current values ​​of the analog-to-digital converter (A / D) (see Fig. 4 ) determined. For this purpose, the course of the load current IL is continuously converted into digital values ​​using an A / D converter and examined by the controller SE.

[0081] Alternatively, the current draw can be determined using a comparator. This requires repeatedly changing the comparator threshold during the mains operation and attempting to derive the load current profile from these changes. Preferably, several comparators can be used in parallel, each with a different threshold.

[0082] Preferably, a probability for the presence of an inductive load is then determined. For this purpose, a phase comparison of the load current IL and the AC voltage UN is performed based on the mains voltage phase timer determined above. Alternatively, if a neutral conductor is connected to terminal N, a phase comparison between the load current IL and the neutral conductor voltage is performed. Subsequently, a load type is determined based on the probabilities estimated above.

[0083] The following describes a preferred recharging sequence. The recharging sequence is part of the control sequence and is also preferably implemented as software in the controller SE. Depending on a recharging cycle frequency, it is executed as often as possible per second until the recharging sequence is explicitly aborted: For recharging, the secondary switch S2 is switched on. Preferably, the controller SE decides, based on the detected load type, whether a longer recharging cycle, particularly with a frequency less than 25 Hz, is possible for the load L. This is possible for most loads. Only very small, and especially small capacitive, loads L require a very short recharging cycle, particularly with frequencies between 25 Hz and 100 Hz.

[0084] Preferably, the primary switch S1 is switched off for recharging in each half-cycle and switched on again when the self-supply voltage UE in the energy storage device C reaches the maximum supply voltage U Emax. This prevents flickering perceptible to humans with smaller loads L, while perceptible flickering does not occur with larger loads L. With larger connected loads L above, for example, 50 W, recharging only occurs when the energy storage device C is almost empty, corresponding, for example, only 3 times per second. For example, 50 W corresponds to approximately 200 mA load current IL, corresponding in particular to a voltage drop of approximately 20 mV across the shunt resistor SH. This voltage is amplified by a factor of approximately 10 for measurement purposes. The threshold SW2 on the load current comparator K2 is accordingly set to approximately 200 mV.

[0085] If a longer recharging cycle, particularly with a frequency < 25 Hz, is possible depending on the load type detected by the load detection, the system first checks whether the self-supply voltage UE of the energy storage device C has fallen below a minimum supply voltage U Emin. The minimum supply voltage U Emin depends in particular on the voltage requirements of the controller SE and / or other electronic components used in the switch. For this purpose, the buffer comparator K1 is preferably set to a low threshold SW1 so that the lowest permissible state of charge, i.e., the minimum supply voltage U Emin, is detected (e.g., approx. 4 V). If this value has not yet been reached or fallen below, the recharging process is terminated. However, if this value has been reached or fallen below, the recharging process continues by switching off the primary switch S1 from the controller SE, thus charging the energy storage device C.

[0086] If, on the other hand, a shorter recharging cycle, in particular ≥ 25 Hz, is required depending on the load type detected by the load sensor, then recharging preferably occurs independently of the state of the energy storage device C, i.e., the primary switch S1 is switched off by the controller SE. In this case, it can be assumed that at least a small portion of the charge of the energy storage device C has been consumed since the last recharging process. Advantageously, recharging occurs during each half-cycle of the AC voltage UN. The recharging process ends when the maximum supply voltage UEmax is reached in the last half-cycle; otherwise, the recharging process continues over the subsequent half-cycles.

[0087] Preferably, after determining the recharging cycle and before starting the recharging process, it is checked whether the specific load type requires recharging to begin at the zero crossing of the load current IL. This is particularly advantageous for certain load types or above a certain load size, which were determined using the load detection method described above. If a zero crossing of the load current IL is required, the system waits for the zero crossing first. If this is not necessary, the recharging process can continue immediately, and the primary switch S1 can be switched off by the controller SE, thus starting the recharging process. For small loads L, it is not absolutely necessary to wait for the zero crossing of the load current IL, since the diversion of the load current IL by the energy storage device C is relatively uncritical for small loads L and can occur at any time.For larger loads L, the charging process or the diversion of the load current IL through the energy storage device C should be started at the zero crossing of the load current IL in order to protect all components.

[0088] Preferably, the controller SE sets the buffer comparator K1 to a high threshold SW1, and charging continues until the self-supply voltage UE of the energy storage device C reaches this high threshold SW1 at the buffer comparator K1. During charging, the buffer capacitor K1 must be monitored for its maximum permissible voltage. Once this voltage is reached, charging is terminated. As mentioned, the voltage at the energy storage device C is applied to the buffer comparator K1 at a factor of 1 / 3 for example. If charging is to stop at, for example, 6V, the threshold SW1 should be set to approximately 2V.

[0089] Once the high threshold SW1 at the buffer comparator K1 is reached, the controller SE selects the optimal time to end the charging process. To do this, the controller SE first determines, based on the specific load type, whether charging should preferably end at the zero crossing of the load current IL. If so, the controller SE waits until the zero crossing of the load current IL. If not, the controller SE, in conjunction with a query of the load current comparator, switches the primary switch S1 back on, thus ending the charging process. Reference symbol list

[0090] 1 Electronic switch A Connection L Phase conductor A / D Analog / Digital converter B Connection Load BE Limiting electronics C Energy storage CV Voltage converter D1 First diode of rectifier D2 Second diode of rectifier D3 Third diode of rectifier D4 Fourth diode of rectifier D5 Diode D6 Diode D7 Diode D8 Diode DZ Rectifier diode D / A Digital / Analog converter EVE Self-supply switching electronics G Rectifier GND Reference ground IL Load current I1 First current path I2 Second current path I3 Third current path K1 Buffer comparator K2 Load current comparator L Load N Connection N conductor R1 Resistor R2 Resistor S1 Primary switch S1a Primary switch S1b Primary switch S2 Secondary switch S3 Tertiary switch SE Control SH Shunt resistor SR Switching regulator SW1 Threshold buffer comparator SW2 Threshold load current comparator O S1 Output signal for S1 O S2 Output signal for S2 O S3 Output signal for T3 O S4 Input signal for SE O BE Output signal limiting electronics for S1T1 Limiting transistor T2 Switching transistor T3 Transistor UN AC voltage of the mains supply UE Self-supply voltage U SE Control supply voltage U SH Voltage drop across the shunt resistor UR Voltage regulator

Claims

1. An electronic switch (1) for electrical installation technology, comprising a first electrical terminal (A) for connecting an L-phase conductor of an AC voltage (UN) of a voltage network, a second electrical terminal (B) for connecting an electrical load (L), a third electrical terminal (N) for connecting an N-conductor of the AC voltage (UN) of the voltage network, an electronic switching device at least for switching the load (L) between an on state (ON) and an off state (OFF), an electronic controller (SE) for controlling the switching device, and a self-supply switching electronics (EV) with an internal self-supply voltage (UE) for the controller (SE) using a load current (IL) flowing through the load (L), wherein the electronic switching device comprises a diode bridge made of two discrete diodes (D1, D3) and two MOSFET body diodes (D2, D4), wherein the third electrical terminal (N) is connected to the self-supply switching electronics (EV) via a fifth diode (D5) in the forward direction of the fifth diode (D5), characterized in that the self-supply switching electronics (EV) is connected to the third electrical terminal (N) via a sixth diode (D6) in the forward direction of the sixth diode (D6) during a positive mains half-wave of the AC voltage (UN), and a tertiary switch (S3) is arranged in series with the sixth diode (D6) between the third electrical terminal (N) and the self-supply switching electronics (EV), wherein the controller (SE) switches the connection between the third electrical terminal (N) and a reference ground (GND) to be conductive by means of the tertiary switch (S3) in the off state (OFF) of the switch, so that a quiescent current can flow from the first terminal (A) toward the third terminal (N) during a positive mains half-wave and does not flow off via the load (L), and in the on state (ON) of the switch avoids a short-circuit current from the first terminal (A) via the reference ground (GND) to the third terminal (N) by means of the open tertiary switch (S3).

2. The electronic switch (1) according to claim 1, characterized in that a primary switch (S1) of the switching device is arranged between the first terminal (A) and the second terminal (B) in a first current path (I1), and a secondary switch (S2) of the switching device is arranged in a second current path (I2) arranged parallel to the first current path (I1), and a high-impedance switching regulator (SR) is arranged in a third current path (I3) parallel to the secondary switch (S2), and a low-impedance energy storage device (C) is arranged in series with the secondary switch (S2) and the switching regulator (SR).

3. The electronic switch (1) according to claim 2, characterized in that the third electrical terminal (N) is connected to an input of the switching regulator (SR) via the fifth diode (D5), and a reference ground (GND) of the energy storage device (C) and of the switching regulator (SR) is connected to the third electrical terminal (N) via the tertiary switch (S3) and the sixth diode (D6).

4. The electronic switch (1) according to one of claims 1 to 3, characterized in that the controller (SE) switches the tertiary switch (S3) to be conductive in the off state (OFF) of the load (L) in order to make the load (L) completely current-free.

5. The electronic switch (1) according to one of claims 1 to 4, characterized in that the tertiary switch (S3) is configured as a P-MOSFET or PNP transistor.

6. The electronic switch (1) according to one of claims 1 to 5, characterized in that the tertiary switch (S3) is controlled via an inverting charge pump that comprises a maximum of two capacitors.

7. The electronic switch (1) according to one of claims 1 to 6, characterized in that the controller (SE) permanently switches off the primary switch (S1) and the secondary switch (S2) in the off state (OFF), so that the switching regulator (SR) provides the self-supply voltage (UE) via the third current path (I3), and switches on the primary switch (S1) and the secondary switch (S2) in the on state (ON), so that the energy storage device (C) provides the self-supply voltage (UE), and in the on state (ON) switches off the primary switch (S1) when a minimum supply voltage (UEmin) is undershot and switches on the primary switch (S1) when a maximum supply voltage (UEmax) is reached.

8. The electronic switch (1) according to one of claims 2 to 7, characterized in that a voltage regulator (UR) is arranged between the self-supply voltage (UE) and the controller (SE) and is connected both to the energy storage device (C) and in parallel thereto to the switching regulator (SR).

9. The electronic switch (1) according to claim 8, characterized in that the voltage regulator (UR) regulates down the self-supply voltage (UE) to a supply voltage (USE) for the controller (SE) that is relatively lower than the self-supply voltage (UE).

10. The electronic switch (1) according to claim 9, characterized in that the voltage regulator (UR) regulates up the self-supply voltage (UE) to a supply voltage (USE) for the controller (SE) that is relatively higher than the self-supply voltage (UE).

11. The electronic switch (1) according to one of claims 2 to 10, characterized in that a rectifier (G) is arranged in the second current path (I2) or third current path (I3).

12. The electronic switch (1) according to one of claims 1 to 11, characterized in that a limiting electronics (BE) independent of the controller (SE) forcibly switches on the primary switch (S1) independently of the controller (SE) when a maximum supply voltage (UEmax) of the self-supply voltage (UE) is exceeded.

13. The electronic switch (1) according to one of claims 1 to 12, characterized in that the controller (SE) comprises a microprocessor that controls at least the primary switch (S1) and the secondary switch (S2) of the switching device via output signals.

14. The electronic switch (1) according to one of claims 1 to 13, characterized in that a detection means downstream of the fifth diode (D5) determines the magnitude and / or phase position of the AC voltage (UN) of the voltage network.

15. The electronic switch (1) according to claim 14, characterized in that the detection means provides a signal (OS5) for the controller (SE) and routes it to an A / D converter of the microprocessor, and the detection means comprises two current-limiting resistors (R5, R6) connected in series downstream of the diode D5, wherein the signal (OS5) is tapped between the two resistors (R5, R6).