Method for data transmission from a transmitter to a receiver in an AC power supply system, and apparatus for data transmission with AC power supply systems

Abstract

The invention relates to a method for the data transmission from an emitter (1) to a receiver (2) in an AC voltage network, comprising a distributor (3) and at least one user group (4) with one or several users (5), wherein the emitter (1) feeds a signal to the AC voltage network by means of a power source (6).

Claims

1. A method for transmitting a data signal in a return channel from a transmitter arranged at a load in the direction of an AC voltage source to a receiver in an AC power supply system having a distributor and at least one load group with one or more loads, the transmitter comprises a current source and a pulse generator, and the current source is connected in parallel to the load, the method comprising: generating via the pulse generator and the current source a current signal, with a predetermined or predeterminable pulse shape on a basis of the data signal, wherein the data signal comprises information about the status of the load, connecting the transmitter, via the AC power supply system, to the receiver so that the current source of the transmitter can transmit the current signal, along the AC power supply system to the receiver, supplying the current signal directly from the current source of the transmitter to the AC power supply system; receiving the current signal, which is transmitted along the AC power supply system, by the receiver; and rejecting crosstalk by the signal from the transmitter in a first load group to the receiver in a second load group via a series resonant circuit arranged in the distributor.

2. The method as claimed in claim 1, wherein the current source simulates an additional load.

3. The method as claimed in claim 1, wherein the signal is subjected to current FSK modulation.

4. The method as claimed in claim 1, wherein the signal is supplied close to or in the load.

5. The method as claimed in claim 1, wherein the transmitter and the receiver are synchronized using the zero crossing of the AC voltage.

6. The method as claimed in claim 1, wherein the signal is supplied independently of a zero crossing of the AC voltage.

7. The method as claimed in claim 1, wherein the receiver reads the signal from the AC power supply system using a shunt resistor.

8. The method as claimed in claim 1, wherein the signal is read close to the distributor.

9. An arrangement for transmitting a data signal in a return channel from at least one transmitter arranged at a load in the direction of an AC voltage source to a receiver in AC power supply systems, comprising an AC power supply system having a distributor and at least one load group with one or more loads, the transmitter, the receiver, wherein the transmitter comprises a current source and a pulse generator, and the current source is connected in parallel to the load, the pulse generator and the current source generate a current signal with a predetermined or predeterminable pulse shape on a basis of the data signal, wherein the data signal comprises information about the status of the load, the transmitter is connected to the receiver via the AC power supply system so that the current source of the transmitter can transmit the current signal, along the AC power supply system to the receiver, the current source of the transmitter is connected directly to the AC power supply system for supplying the current signal directly from the current source to the AC power supply system to be transmitted along the AC power supply system and to be received by the receiver, wherein the distributor has a series resonant circuit for rejecting crosstalk by the signal from the transmitter in a first load group to the receiver in a second load group.

10. The arrangement as claimed in claim 9, wherein the transmitter is integrated in the load or is arranged close to the load.

11. The arrangement as claimed in claim 9, wherein the transmitter comprises a current FSK modulator.

12. The arrangement as claimed in claim 9, wherein the receiver comprises a shunt resistor for reading the signal from the AC power supply system.

13. The arrangement as claimed in claim 9, wherein the receiver is arranged close to the distributor.

14. The arrangement as claimed in claim 9, wherein the series resonant circuit comprises a first and a second series resonant circuit.

15. The arrangement as claimed in claim 14, wherein said first series resonant circuit has a resonant frequency which corresponds to the first current FSK frequency.

16. The arrangement as claimed in claim 14, wherein said second series resonant circuit has a resonant frequency which corresponds to the second current FSK frequency.

Description

(1) The invention is explained in more detail below with reference to figures, which merely show exemplary embodiments and in which:

(2) FIG. 1 shows a schematic illustration of an arrangement according to the invention in a building power supply system,

(3) FIG. 2 shows a simplified equivalent circuit diagram of an arrangement according to the invention with two load groups,

(4) FIG. 3 shows the equivalent circuit diagram from FIG. 2, but with a modified distributor and a capacitive load,

(5) FIG. 4 shows a frequency response for the currents on both shunts in the Cenelec B band from FIG. 3,

(6) FIG. 5 shows a variant of a double series resonant circuit,

(7) FIG. 6 shows an equivalent circuit diagram of a current FSK transmitter according to the invention with a current mirror,

(8) FIG. 7 shows an equivalent circuit diagram of an alternative circuit for a current FSK transmitter without a current mirror.

(9) FIG. 1 shows a schematic illustration of an arrangement according to the invention in a building power supply system. In this case, a system access 18 has a distributor 3 connected to it which performs the distribution of the alternating current over the individual load groups 4, 4 in the building. Each load group 4, 4 has a fuse 12 which isolates the load group from the system in the event of a fault. Arranged directly adjacent to the fuse 12 in each load group 4, 4 is a receiver 2, before the system voltage is delivered to the load 5 via a lines 13. Arranged directly upstream of the load 5 is a transmitter 1 which can impress a current signal on the AC power supply system. If a plurality of loads 5 are connected in the same load group 4, 4, each load may have a dedicated transmitter.

(10) FIG. 2 shows a simplified equivalent circuit diagram of an arrangement according to the invention with two load groups 4, 4 and a distributor 3. The fuses 12 (see FIG. 1) are not shown in this case. In accordance with the requirements for power distribution, the system impedance which can be measured at the distributor 3 is represented by a small resistor. On account of the inevitable line inductances, FIG. 2 additionally shows a coil in series with this resistor, which results in a significantly higher source impedance for the system in the region of the current FSK transmission frequencies.

(11) In this case, the load 5 in the load group 4 is simulated by a resistance of 500 and a capacitance of 100 nF, for example. Such a load model corresponds approximately to a light bulb and an appliance with a radio interference suppression capacitor. The load 5 in the adjacent load group 4 is modeled with 50 and 500 nF, for example. This corresponds to the entirely realistic case of a plurality of light bulbs switched on and a plurality of appliances with radio interference suppression capacitors.

(12) The supply lines from the distributor 3 to the load 5, 5 is represented by the equivalent circuit diagram of a line 13, 13. For a 20 m line, this corresponds approximately to a resistance of 0.7 and an inductance of 8 H. Next to the distributor 3 in each load group, a shunt 8, 9 is shown which represents the receiver. Such a shunt 8, 9 has a resistance value of 0.1, for example. For the purpose of supplying a signal, the load 5 has a current source 6 which delivers a transmission current I.sub.S with a peak value of approximately 200 mA. This current source 6 is part of the transmitter, which impresses a current-FSK-modulated current signal onto the line 13. This current signal is then detected via the shunt 8 of the receiver and is converted into an appropriate voltage.

(13) FIG. 2 also shows the split of the transmission current I.sub.S. Inevitably, a portion I.sub.1 which does not flow via the shunt 8 of the receiver is already picked up by the individual load. The current I.sub.N flowing via the system passes through the individual shunt 8. Although the current I.sub.2 flowing into the adjacent load group 4 also passes through the individual shunt 8, it also passes through the shunt 9 of the adjacent load group 4. Since this load group has been shown to be heavily loaded and has a plurality of lights and a plurality of radio interference suppression capacitors, for example, the current I.sub.2 is not negligible and results in undesirable crosstalk. The following then applies:
I.sub.S=I.sub.1+I.sub.N+I.sub.2

(14) In FIG. 3, two series resonant circuits 10 and 11 are disposed at the location of the distributor. These resonant circuits are attuned to the two current FSK frequencies. With careful component selection to attain a high level of quality, the series resonant circuits behave almost like short circuits at the transmission frequencies. As a result, the impedances of the system and the load groups are almost negligible. In the case of the usually low line impedances 13 and 13, the following then applies approximately for the current split:

(15) I.sub.NI.sub.S The current flowing via the system and the shunt 8 is almost as large as the transmission current.

(16) I.sub.10 The current absorbed by the load 5 itself is negligible.

(17) I.sub.20 The current penetrating the adjacent circuit 4 is negligible. This prevents crosstalk.

(18) At current FSK frequencies of 100 kHz and 110 kHz, it is possible for the series resonant circuits to be formed by a capacitance of 470 nF and an inductance of 4.45 H or 5.4 H, respectively.

(19) FIG. 4 shows a frequency response for the currents on both shunts 8, 9. In this case, the frequency response 14 shows the current in the shunt 8 (see FIG. 3) and the frequency response 15 shows the current in the shunt 9 (see FIG. 3). The figure likewise shows the two current FSK frequencies 16 and 17, which are at 100 kHz and 110 kHz, respectively. The short-circuit-like response of the series resonant circuits at the transmission frequencies is clearly evident here from the values with acutely to severely negative profiles.

(20) FIG. 5 shows a variant of a double series resonant circuit in which only a large high-voltage capacitor C1 is required in order to achieve small component dimensions. This means that there is also a fall in the reactive current produced at the system frequency. The frequency response of this circuit corresponds to FIG. 4 in qualitative terms, and likewise has two sharp minima at the transmission frequencies. The capacitor C2 can be designed for far lower peak voltages and retains a small size. This circuit variant is suitable for low transmission frequencies at which the current FSK frequencies are relatively far apart. Otherwise, unfeasible values of C2 and L2 are obtained during the design calculation.

(21) FIG. 6 schematically shows an equivalent circuit diagram of a current FSK transmitter 1 according to the invention with a current mirror 20. In this case, the transmitter 1 is connected to the AC power supply system, represented by the two 230V connections, in parallel with a load 5, represented by a light bulb. On the basis of a signal from a data communication output, a pulse generator 21 generates a sin.sup.2 signal which is then forwarded to the current mirror 20. This current mirror 20 now impresses a current signal, modulated by a current FSK modulator (not shown) as appropriate, on the AC power supply system via the MOSFET 24. An optional resistor 25 is used for current limiting.

(22) FIG. 7 schematically shows an equivalent circuit diagram of an alternative circuit for a current FSK transmitter 1 according to the invention without a current mirror. In this case too, the transmitter 1 is connected to the AC power supply system, represented by the two 230V connections, in parallel with a load 5, represented by a light bulb. On the basis of the FSK signal from a data communication output, a pulse generator 21 generates a sin.sup.2 signal which is then forwarded to the power transistor 24.

(23) It goes without saying that instead of the current FSK modulator it is also possible to use a modulator for other modulation methods, for example for a pulse position method or a single pulse method or pulse encoding, both in the circuit shown in FIG. 6 and in the circuit shown in FIG. 7.