JPS5829645Y2 - Signal generator that uses the power grid - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a signal generator that utilizes a power system.

It is well known that power grids are used for the transmission of signals.

In remote control technology, for example, alternating current pulses, preferably audio frequencies, from a transmitter are superimposed on the power system at a central location by link coupling.

These alternating current pulses are spread throughout the power system and can be taken out of the power system at any point by well-known means to carry out commands, for example for remote control purposes.

In remote control, the required direction of propagation of said signals corresponds to the direction of energy flow in the power system.

It has also been proposed to use power lines to transmit signals in a direction opposite to the direction of energy flow.

In the first case of remote control, the standard practice is to use only one central transmitter and multiple receivers, whereas in the second case
The case particularly concerns the transmission of signals from many locations outside the power system by means of a plurality of transmitters to a central location with one or a few receivers.

Due to the large number of transmitters required in the second case, it is economically necessary to reduce their cost.

However, despite this, they must meet pressing technical needs.

Due to the large number of transmitters acting on the same power system, their transmit power is also limited, not only in terms of cost, but also in terms of possible interference caused by signals from these transmitters on adjacent data transmissions. In some cases, this has to be significantly lower than in the case of remote control.

Similar transmitters proposed in the past are based on oscillator circuits with pulsed excitation at the mains frequency, which are connected to the power system, for example (e.g. Swiss Patent Specification No. 442.505, British Patent Specification No. Book 1,148,55
No. 3).

This type of transmitter generates vibrations not only at discrete frequencies, but also at relatively closely occupied ranges.

In practical applications, this makes it difficult or impossible to use other discrete frequencies within the same power system simultaneously.

This is a serious disadvantage, especially when data originating from many sources is being transmitted.

The object of the present invention is to provide a signal generator that is advantageous for transmitting a signal in a power system in a direction opposite to the direction of power energy flow, that is, has low transmission power, is inexpensive, and has little interference.

As observed in an advantageous application of the invention, if the power system is used as a communication channel for transmitting signals of frequency f8, relatively high noise levels can be expected on the communication channel.

Experiments have shown that the interference voltage is a high harmonic of the main frequency fN.

Therefore, what is very important is that the optimal signal frequency f8
is to choose.

Due to the relatively dense interference frequency range, it is advisable to keep the bandwidth at the receiving end as narrow as possible.

For example, it is limited to just the width required by the characteristics of the data transmitted by the signal at frequency fs.

It is believed that the signal spreads in the opposite direction to the direction of energy flow in the power system, and the transmitted power is several times lower than with normal remote control techniques.

In addition to limited bandwidth and high selectivity, a receiver suitable for this purpose must also exhibit high selectivity, since only weak signals are received.

Since neither the dominant frequency fN nor its harmonics, the interference frequency, are constant over time, a constant signal frequency fs is maintained under all circumstances, i.e. when the dominant frequency fN deviates abnormally from its ideal level. This is particularly difficult when finding a suitable signal frequency f, which still exhibits a sufficient spacing ratio from adjacent interfering frequencies.

It is therefore very advantageous to select a signal frequency f8 at which the main frequency fN is not constant.

It is particularly advantageous to maintain this signal frequency f8 in a fixed relationship to the main frequency fN.

The spacing ratio of the signal frequency f8 from adjacent interfering frequencies is thus kept intact even when fluctuations of the main frequency fN occur.

A receiver whose response frequency automatically adapts to the signal frequency f8, which varies in a known manner with the main frequency fN, is known, for example, from Swiss Patent Specification No. 424,968.

Oscillations at frequency f8 can be generated by simple means by pulse exciting an oscillator circuit tuned to frequency f8.

However, in addition to the required signal frequency f8 and the audio signal frequency f8, known transmitters that work on the principle of excitation of audio frequencies also generate a more or less wide range of undesired interference frequencies.

According to the present invention, human power is connected to the control signal source of the main frequency by pressing a button on a device that generates a transmission signal of frequency f8 in the power grid, which has a fixed relationship with the main frequency fN of the power grid. A pulse generator is provided, the pulse generator including a frequency multiplier and a splitter in series with the pulse shaper, and a controllable switching element having an input connected to an output of the pulse generator. , an oscillator circuit connected to the power system and tuned at least approximately to a frequency f8 is provided, the oscillator circuit being coupled to a circuit controlled by a switching element.

Next, embodiments of the present invention will be described with reference to the drawings.

The various embodiments of the transmitter described below substantially eliminate the disadvantage of generating a wide range of unwanted interference frequencies.

All of them require energy at least once during each cycle of the required frequency f8, preferably l/4 of l cycles.
It is based on the fact that during the period of time, the pulse is sent by a pulse to an oscillator circuit tuned at least to the frequency fs.

FIG. 1 is a simple circuit diagram of a first embodiment.

An LC oscillator circuit 1 with a coil 2 and a capacitor 3 is connected to a phase conductor P and a neutral conductor O of a power system with a mains voltage UN and a frequency fN.

The LC oscillation circuit 1 is closed via the impedance of the power system.

Any oscillating current generated in the LC oscillator circuit 1 therefore flows substantially through the phase conductor P to the supply point and from there to the neutral conductor C.

The controllable switching element 5 is coupled to the KC oscillator circuit 1 via a winding 4 which is coupled to the coil 2 .

In the embodiment shown in FIG. 1, a switching transistor acts as controllable switching element 5. In the embodiment shown in FIG.

However, other controllable switching elements known in particular from semiconductor technology, such as thyristors, etc., may also be used for this purpose.

Emitter of switching transistor 6/d, 41m7
is connected to terminal 8 via.

The collector 9 of the switching transistor is connected to a terminal 11 via a coupling winding 4 and a resistor 10.

A supply voltage U is applied between terminals 8 and 11.

The supply voltage U is generated in a known manner, for example, by a feed line of a known type connected to a phase conductor P and a neutral conductor O.

The control input of the controllable switching element 5 , ie the base 12 of the switching transistor 5 , is connected via a conductor 13 to the output 14 of the pulse generator 15 .

Pulse generator 15 connects conductors 16. to terminals 11-8, respectively.
17.

One input 18 of the pulse generator 15 is connected to the phase conductor P via a line 19.

The pulse generator 15 generates pulses whose repetition frequency matches the signal frequency f8.

The controllable switching element 5 is controlled by these pulses.

The current pulse is repeatedly applied to the switching element 5 at a frequency f8.
The current flows through the coupled winding 4 of the power supply circuit of the LC oscillator circuit 1.
is excited by forced vibration of frequency f8.

Pulse frequency f8 generated by pulse generator 15
is determined by the main frequency signal fN, which is sent via conductor 19 to pulse generator 15 in the manner described below.
maintained in a fixed relationship to

The pulses from the pulse generator 15, the current pulses flowing through the button and the coupling winding 4 preferably have a pause ratio l:3.

The coherent excitation of the LC oscillator circuit 1 results in contrast to other known pulse-excited transmitters which generate an oscillating power^decay cycle of approximately constant amplification and frequency.

Referring now to FIG. 2, a second type of transmitter will now be described as an example, with particular emphasis on the structure and method of operation of the pulse generator 15.

Components that are the same in FIG. 1 and FIG. 2 are designated by the same reference numerals.

Pulse generator 15 includes a frequency multiplier 20 .

One example of a suitable frequency multiplier is an oscillator that is synchronized in a known manner to a high frequency of the main frequency fN.

Input 18 of pulse generator 15 is connected to input 21 of frequency multiplier 20.

The output 22 of the frequency multiplier 20 is connected to the input power 23 of the frequency divider 24.

The output 25 of the frequency divider 24 is connected to the input 26 of the pulse shaper 27, and the output 28 of the pulse shaper 27 is connected to the output 14 of the pulse generator 15.

As described with reference to FIG. 1, the output 14 of the pulse generator is connected to the controllable switching element 5.

The frequency multiplier 20 also uses n of the control frequency fN that is sent.
It can be in the form of a multivibrator that vibrates at twice the frequency.

Therefore, the output frequency of the frequency multiplier 20 is nfN.

This frequency is determined by a frequency divider 2 which is adjusted to a division ratio l:P.
Sent to 4.

The output frequency of the frequency divider 24 is thus equal to the required signal frequency 0 The next stage pulse shaper, for example in the form of a monostable flip-flop, is advantageous as far as the excitation of the oscillator circuit is concerned, e.g. Ratio of pulse frequency to.

The repetition frequency f reaching the output 14 of the pulse generator 15
The 8 pulses then drive the controllable switching element 5 by 1/4 of 1 cycles in each cycle of oscillation of frequency fs, so that the LC oscillator circuit 1 drives the controllable switching element 5 in the coupled winding 4 and its feed circuit. It is excited at f8 by the current pulse flowing through the switching element 5.

If the signal frequency f8 is specified as 275 c/s (ideal value) for a main frequency of 50 c/s (ideal value), in this case the frequency multiplier 20 is adjusted to a factor of 11 and the frequency divider 24 is adjusted to have a divisor of 2.

The signal frequency f8 is thus always equal to 5.5 times the main frequency fN even when the main frequency varies.

As can be easily seen, other fixed ratios between the signal frequency f8 and the main frequency fN can be adjusted by changing the aforementioned factors or divisors.

The third embodiment shown in FIGS. 3 and 4,
It is shown how a pulse train with the above-mentioned pulses with a pause ratio l:3 occurs at the output of the pulse generator 15 even with variations in frequency.

Identical components on buttons in each of FIGS. 1, 2, and 3 are designated by the same reference numerals.

Both the frequency multiplier 20 button and the frequency divider 24 are arranged in a well-known manner such that their output signals U22> and U25 respectively follow a rectangular pattern as shown in FIG. 4 as a function of time in graphs a and b. configured.

If, according to FIG. 3, the output signal U2° of the frequency multiplier 20 (graph a in FIG. 4) is tapped off via the conductor 29 to the first input 30 of the AND gate 31, Figure 4 graph b) is this AND gate 31
, the output voltage U34 at the output 34 of the AND gate 31 follows a time pattern of the kind shown in graph C of FIG.

Since the output signal U25 already has the required frequency f8, the pulses of the output voltage U34 also occur with a repetition frequency f8.

Due to the aforementioned conjunction of the two voltages U22 and U25, the output signal U34 receives the necessary pulses with a rest ratio of 1:3 even if the main frequency fN1 and therefore the frequency f8 varies.

The output voltage U34 of the AND gate 31 is applied to the pulse generator 15.
via a line 35 to the output 14 of the controllable switching element 5 and via a line 13 to the input 12 of the controllable switching element 5.

A fourth embodiment will be described with reference to FIG.

5, the same components are designated by the same reference numerals as in FIGS. 1, 2, and 3.

The main frequency control signal is sent via conductor 19 from phase conductor P through resistor 36 to input 18 of pulse generator 15 .

This control signal is sent via resistor 36 to base 37 of transistor 38.

Diode 39 is connected between base 37 and conductor T at zero potential.

This diode 39 limits the negative potential at the base of transistor 38.

The transistor 38 has an opposite phase output signal connected to an emitter 40 via an emitter resistor 41 and a collector resistor 4.
3 to the collector 42, driven by the positive half-wave of the control signal at the main frequency.

These output voltages have an approximately square pattern.

Corresponding parts of the two output signals are therefore always directed in opposite directions.

The output signal of transistor 38 is passed through an RC stage with capacitor 44 and resistor 45, and capacitor 46 and resistor 47.
is differentiated by another RC stage with .

These differentiated output signals are sent as control signals from switching points 48 or 49 via diodes 50 or 51 to multivibrator 52 in a known manner.

The sweep frequency of the multi-ibrator 52 is synchronized and sized so that it oscillates at n times the main frequency fN.

The factor n of the frequency multiplier 20 and the divisor of the frequency divider are selected such that the generated signal frequency f8 no longer corresponds to a harmonic of the main frequency fN.

This is the case when n/P is not an integer. frequency n-f
N signals appear at the output 22 of the multivibrator 52, which acts as a frequency multiplier 20.

In the embodiment according to FIG. 5, frequency divider 24 (FIG. 3) is in the form of Texas Instruments product 5N7472.

As described with reference to FIGS. 3 and 4, the output signal U2° of the frequency multiplier 20 (in this case, the multivibrator 52) and the output signal U2 of the frequency divider 24 (SN7472)
5 is a digital signal.

Diodes 53, 54, 55 connected to terminal 11 via resistor 56 are used for this purpose.

The diode 55 is further connected via a resistor 57 to the output 14 of the pulse generator 15;
8 to the conductor 7.

This digital circuit also acts as a pulse shaper.

As can be seen from the fourth embodiment shown in FIG. 5, the transmitter of the invention can be obtained with very little outlay, especially if integrated circuits are used.

Signal frequency f8 that must be provided at the transmitting end
The requirement for a fixed ratio between and the main frequency fN is ideally met.

At the receiving end, the requirement regarding the correspondence between the response frequency of the receiver and the signal frequency f8 controlled by the main frequency fN is met by simple means, as already described.

The invention is particularly advantageously used when it is desired to report the position (on, off) of a switching element of a power distribution system to a central location, for example by transmitting a signal through the power system.

With only a few watts of transmission power, distances of, for example, 10 km and more can be covered reliably.

According to the present invention, the frequency f8 used for signal transmission is
Since it has a fixed relationship with the main frequency fN of the power system, the signal frequency f8 can be easily and well detected by pressing the button on the receiving side from the relationship with the main frequency fN.

Furthermore, since the signal frequency f8 is not an integral multiple of the main frequency fN, that is, the signal frequency f8 does not match the frequency of the harmonic of the main frequency fN, the signal frequency f8 is changed from the harmonic of the main frequency fN through the transmission path. interference is effectively prevented.

In the present invention, an oscillator circuit connected to the power system and at least approximately tuned to frequency f8 is excited only once for each cycle of the generated signal frequency f8.

This therefore makes it practically possible to obtain very clear pulses without the simultaneous generation of uncorrelated and interfering oscillations.

A preferred embodiment of the present invention is as follows.

l) A signal generating device as claimed in the claims for registration of a utility model, characterized in that the frequency multiplier includes an oscillator synchronized by a harmonic of the main frequency.

2) The oscillator is characterized in that it includes as an oscillator a multivibrator that is synchronized to the harmonics of the main frequency by a main frequency control signal. signal generator.

3) The signal generating device according to claim 2) or 2), wherein the pulse shaper includes a monostable flip-flop.

4) An input of a switching element whose output is controllable, with one input connected to the output of the frequency multiplier, the other input connected to the output of the frequency divider, and the other input connected to the output of the frequency divider. The signal generating device according to claim 1), 2) or 3), characterized in that it comprises a digitally operated switching element connected to the signal generator.

[Brief explanation of the drawing]

1 is a highly simplified circuit diagram of a first transmitter according to the invention, FIG. 2 is a circuit diagram of a second transmitter according to the invention, and FIG. 3 is a circuit diagram of a third transmitter according to the invention. Figure 4 is a circuit diagram showing the voltage characteristics of the pulse generator of the third embodiment.
The figure is a detailed circuit diagram of a fourth transmitter according to the present invention. 1...LC oscillation circuit, 2...Coil,
4... Winding wire, 5... Switching element,
15... Pulse generator, 20... Frequency multiplier, 24... Frequency divider, 52...
Multi vibrator.

Claims (1)

[Scope of utility model registration request] In a device that generates in a power system a transmission signal having a frequency f8 having a fixed relationship with the main frequency fN of the power system, and sends this transmission signal through the power system in a direction opposite to the flow direction of electric power energy. , a pulse generator having an input connected to a main frequency control signal source, the pulse generator including a frequency multiplier and a divider in series with the pulse shaper, a controllable switching element having an input connected to the terminal, an oscillator circuit connected to the power system and at least approximately tuned to a frequency f8, the oscillator circuit being controlled by the switching element; If the frequency f8 of the transmission signal does not match the frequency of the harmonics of the main frequency fN of the power system, the oscillator circuit 7>E is excited only once in each cycle of the frequency f of the generated transmission signal. A signal generating device that utilizes an electric power system, characterized in that: