The invention relates to a circuit configuration for the transmission of data signals from and/or to household appliances between a first transceiver device and a second transceiver device via an AC power supply line system within a transmission frequency range which lies above the frequency of the AC power supply, wherein the respective transceiver is connected to a filter arrangement at the AC power supply line system.
In a known circuit configuration of the aforesaid type (D1: U.S. Pat. No. 6,396,392 B1) the respective transceiver comprises a modem connected to the respective household appliance which is connected to the AC power supply line system via a coupler. Various filters such as low-pass filters are contained both in the modem and in the coupler and the respective coupler is impedance-matched to the impedance of the AC power supply line system both on the input side and on the output side (see in particular FIG. 2 and FIG. 11 of U.S. Pat. No. 6,396,392 B1). In this connection, nothing is known about using filter arrangements in the AC power supply input circuit of the respective household appliance.
In a further known circuit configuration for the transmission of data signals from and/or to household appliances (D2: U.S. Pat. No. 6,590,493 B1), in each case a group of individual household appliances is connected to an AC power supply line system via a separate filter arrangement. The filter arrangements of different groups of household appliances are dimensioned so that the data signals transmitted in one group of household appliances cannot reach the household appliances belonging to another group of household appliances. LC low-pass filters of different configurations are used for the relevant filter arrangements. In this connection, nothing is known about problems with matching the impedances of these filter arrangements to the impedance of the AC power supply line system.
To avoid HF interference signals being emitted from a household appliance connected to a AC power supply line system, it is generally known (D3: Siemens Switching Examples, 1974/75 edition, page 128, FIG. 6.4 and page 129, FIG. 6.5) to connect a capacitor arrangement between the voltage-carrying power supply line and a neutral conductor, this capacitor arrangement comprising a series circuit of two capacitors (known as Y capacitors) of relatively low capacitance whose common connection point is connected to an ground connection of the relevant power supply of the relevant household appliance. Optionally, a higher-capacitance single capacitor (known as an X capacitor) is connected in parallel to this capacitor series circuit. Matching of the impedance of the AC power supply input circuit of the relevant household appliance to the impedance of the power supply line supplying the AC voltage is not provided here.
In addition to the interference suppression measure last considered it is further known (D4: Siemens Switching Examples, 1977/78 edition, page 137, FIG. 6.4 and page 152, FIG. 6.8) to provide a current-compensated choke arrangement in the AC power supply input circuit, comprising two choke windings of which one is located in the current-carrying power line and the other lies in the relevant neutral conductor. This type of current-compensated choke arrangement prevents common-mode interference pulses originating from the relevant appliance from entering into the power supply. In this case also, nothing is known about any matching the impedance of the filter arrangement used in the AC power supply input circuit of the relevant household appliance to the impedance of the AC power supply line system.
In a circuit configuration of the type specified initially, it has now been established that a filter arrangement used hitherto in conjunction with the respective transceiver device similar to the filter arrangement known from D1 with the usual dimensions can substantially reduce the respectively emitted transmission level at the AC power supply line system so that these signals can only be received without interference over a relatively short distance by a receiver device connected to the AC power supply line system.
It is thus the object of the invention to show a way of constructing a circuit configuration of the type specified initially with a relative low filter expenditure whilst avoiding the disadvantage indicated hereinbefore.
The object indicated hereinbefore is achieved in a circuit configuration of the type specified initially by the respective filter arrangement containing a power supply low-pass filter which is arranged in the input circuit of the power supply unit of the associated transceiver device and is provided with an impedance curve such that the impedance thereof in said transmission frequency range has a value that is at least twice as high as the impedance of the AC power supply line system in said transmission frequency range.
The invention has the advantage that as a result of said dimensioning of the power supply low-pass filter which is arranged in the input circuit of the power supply unit of the associated transceiver device, the transmission level delivered by the relevant transceiver device to the AC power supply line system is not reduced so substantially as is the case when using the filter arrangement used so far. The dimensioning of the afore-mentioned power supply low-pass filter according to the invention will be discussed in further detail below. At this point, it may be noted that a transceiver device is understood to be a transmitting and/or receiving device according to the case.
Appropriately in an AC power supply line system comprising at least one current-carrying line conductor and an ground conductor, the power supply low-pass filter consists of an inductive component located in the respective line conductor and a capacitor arrangement located between at least one end of the relevant inductive component and the ground conductor. This yields the advantage of a power supply low pass filter which is particularly easy to implement.
The afore-mentioned capacitor arrangement preferably consists of a single capacitor (X capacitor) which connects the end of the inductive component on the power supply unit side to the ground conductor of the AC power supply line system and a series circuit of two capacitors (Y capacitors) connected in parallel to this single capacitor, whose common connection point is connected to the ground connection of the relevant power supply unit. A capacitor arrangement having this structure thus particularly effectively prevents HF interference signals produced in the relevant household appliance or the relevant transceiver device from entering into the AC power supply line system.
An ohmic resistor is appropriately connected in parallel to said capacitor arrangement. This ohmic resistor advantageously serves to unload the capacitor arrangement after disconnecting the entire circuit configuration from the AC power supply line system so that in this state no problems arise through contact of otherwise current-carrying lines or part of the relevant circuit configuration.
In order to avoid common-mode interference signals from the respective household appliance or the respective transceiver device being delivered to the AC power supply line system, preferably respectively one winding of a current-compensated choke is inserted in the conductor sections of the power supply low pass filter connected to the respective line conductor and the ground conductor of the AC power supply line system.
The invention is explained in detail hereinafter using an exemplary embodiment with reference to the drawings.
The circuit configuration according to
Furthermore, a power supply filter FI is connected to the two lines NL and NO of the AC power supply line system NL on the input side. In the present case, this power supply filter FI is a power supply low pass filter which attenuates the AC power supply at the AC power supply frequency of 50 Hz or 60 Hz very little if at all. The impedance of the associated low-pass power supply filter FI at the AC power supply frequency is of the order of magnitude of a few milliohms. On the other hand, the impedance of the relevant low-pass power supply filter FI in the transmission frequency range in which data signals are transmitted from the modem MO and/or to said modem is substantially higher, being in the range of a few ohms. This will be discussed in further detail below.
The power supply filter FI considered previously is connected before the input of a power supply unit PS which provides the various supply voltages required by the individual devices or appliance parts of the household appliance HG under consideration. In the present case, merely a control device CT is shown as representative of all the devices of the household appliance HG provided which have their supply voltages supplied from the power supply unit PS. The control device CT is connected to the modem MO via control lines for bidirectional signal transmission. This means that the modem MO receives control signals supplied by the control device CT and that conversely signals for processing are fed to the control device CT from the modem MO. These signals are usually obtained from the transmission of data signals which are delivered from the modem MO via the AC power supply line system PL and/or which are supplied to the modem MO via this AC power supply line system PL.
The modem MO operates here as an AC power supply or powerline communication device, for example, in a working or transmission frequency range of 95 kHz to 148.5 kHz. This transmission frequency range is thus significantly higher than the power supply frequency (50 Hz or 60 Hz) of the AC power supply.
The relevant household appliance HG or more accurately its relevant transceiver, that is the modem MO, is in communicating connection with at least one second transceiver for transmission of data signals via the AC power supply line system PL. The relevant second transceiver can belong to a further household appliance or for example, to a common control and monitoring device provided for a plurality of household appliances. Data signals can be transmitted between this control and monitoring device and the individual transceivers of the respective household appliances via the AC power supply line system, for example in the course of updating control programs for the individual household appliances and/or for carrying out remote diagnoses in the relevant household appliances.
The equivalent circuit diagram shown in
The power supply line impedance Zn effective between the power supply conductor NL and the ground conductor NO of the AC power supply line system PL forms, together with the transmission-side impedance Zs, a voltage divider through which only a fraction of the amplitude of the data signals delivered by the generator G is decreased at the power supply impedance Zn. At a usual or typical power supply impedance Zn of about 3 Ohm at the aforementioned transmission frequency of, for example, 132.5 kHz, the original transmission amplitude is therefore only decreased by 75% at this power supply impedance.
In order that this amplitude should not be lowered considerably further, it is provided according to the invention that the low pass power supply filter FI whose impedance Zfi is in parallel with the power supply impedance Zn, in the transmission frequency range of the modem MO, that is in the present case at a frequency of 132.5 kHz, should be given an impedance which is at least twice as high as the impedance Zn in the relevant transmission frequency range. If for the numerical values given previously, the impedance Zfi at the frequency of 132.5 kHz is specified, for example, as 6 Ohm, the total impedance of Zn and Zfi is now 2 Ohm. This means that now only two-thirds, that is about 67.1% of the voltage amplitude of the data signal amplitude delivered by the generator G is available on the AC power supply line system PL.
If an impedance Zfi of 12 Ohm, that is four times the power supply impedance Zn, were to be given to the low pass power supply filter FI at the aforementioned frequency of 132.5 kHz, for example, this would give a total impedance between the power supply line NL and the ground conductor NO of the AC power supply line system PL of 2.4 Ohm. As a result, about 70% of the amplitude of the data signal amplitude delivered by the generator G would be available on the AC power supply line system, that is, more than in the case considered previously. As a result of this measure, the range for the transmission of data signals is increased significantly compared with the case where very low-resistance power supply filters FI are used, that is power supply filters which, at the afore-mentioned frequency of 132.5 kHz for example, have an impedance of the order of magnitude of the impedance of the AC power supply line system or even an impedance below this impedance.
At this point, it may be noted that the previously indicated effect of weaker attenuation of the AC power supply line system could be achieved in principle by an even higher-resistance low pass filter at the transmission frequency under consideration. However, this would necessitate an increased expenditure on circuitry which is undesirable. In any case, the measure according to the invention yields a power-supply low-pass filter optimised with regard to impedance relationships with relatively low expenditure on circuitry.
The right half of the equivalent circuit diagram according to
The incoming data signals via the impedance Zü on the receiving side of a second transceiver device are effective at the impedance Zn of the AC power supply line system on the receiving side. This impedance Zn, which can be 3 Ohm for example as specified above, firstly lies parallel to the impedance Zfi of the power supply low-pass filter provided on the receiving side and also the input impedance Ze of the circuit configuration provided on the receiving side lies parallel to the parallel circuit comprising the impedances Zn and Zfi. As a result of this parallel circuit, an overall relatively low input receiving level is obtained on the receiving side. In order not to allow this input receiving level to drop so sharply, the impedance Zfi of the power supply low pass filter provided on the receiving side is set in the transmission frequency range of the entire arrangement so that it has a value at least twice as high as the impedance Zn of the AC power supply line system in the aforementioned frequency range. The input impedance Ze on the receiving side should also be selected to be relatively high.
The aforementioned capacitor arrangement consists of a single capacitor C1, also designated as an X capacitor, which connects the inductive component L at the power supply unit end to the ground conductor of the AC power supply line system and a series circuit of two capacitors, also designated as Y capacitors, connected in parallel to the single capacitor C1. The common connection point of the two aforementioned capacitors C2 and C3 is connected to the ground connection of the relevant power supply unit PS.
Connected in parallel to the capacitor arrangement considered previously, consisting of the capacitors C1, C2 and C3, as shown in
In addition to the components considered previously, the power supply low pass filter shown in
Number | Date | Country | Kind |
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103 60 565.7 | Dec 2003 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP04/53656 | 12/22/2004 | WO | 10/16/2006 |