System for transmitting information via electric lines and method for operating the system

Abstract

In a system and method for operating a system, a drive is connectable to a supply-voltage source, especially an AC-voltage source, with the aid of an apparatus, in particular a control unit, via electric lines installed in the system, and information is transmittable between the control unit and the drive, using the lines.

Claims

1. A method for operating a system including an apparatus, having a control unit, connected to a multi-phase AC supply-voltage source, and a device arranged as a drive that includes an electric motor and an electronic circuit that are connected to the apparatus via three lines including a selective one of the three lines and two other lines, each line corresponding to a respective phase of the AC supply-voltage source, the apparatus including two power switches connected to the control unit, each power switch connected in parallel to a respective diode that is external to the power switch and connected in series to each other, each diode being positioned on a selective one of the lines, comprising: supplying AC voltage from the apparatus to the device via the lines to power the electric motor and the electronic circuit of the drive of the device; switching the two power switches among four different states of supply voltage of the selective one of the lines one after another in time to encode the information to be transmitted between the control unit and the device on the selective one of the lines, the four different states including: (i) a first state where current is blocked; (ii) a second state where only a positive current is enabled; (iii) a third state where only a negative current is enabled; and (iv) a fourth state where the current is completely conducted; transmitting the encoded information between the control unit and the device on the selective one of the lines by the switching of the power switches among the four different states of the supply voltage of the selective one of the lines; measuring supply voltages on each of the plurality of lines; at a beginning of the transmitting of the encoded information between the control unit and the device on the selective one of the lines, determining, from the measured supply voltages, an average voltage value over a time span for each of the plurality of lines and identifying which one of the plurality of lines is the selective one of the lines based on the average voltage value of the selective one of the lines being different than the average voltage value of other ones of the plurality of lines; decoding the information transmitted between the control unit and the device on the selective one of the lines by comparing the measured supply voltage on the selective one of the lines to a first threshold to determine that the power switches are in the first state, to a second threshold, different from the first threshold, to determine that the power switches are in the second state, to a third threshold, different from the first threshold and from the second threshold, to determine that the power switches are in the third state, and to a fourth threshold, different from the first threshold, the second threshold, and the third threshold, to determine that the power switches are in the fourth state; controlling, by the electronic circuit, a rotary motion of a rotor of the electric motor based on the decoded information; and during a time interval in which the information is transmitted from the control unit to the device over the selective one of the plurality of lines, fully powering the device by only the two other lines.

2. The method according to claim 1, wherein the drive includes a measurement device adapted to measure supply voltages assigned to the lines.

3. The method according to claim 1, wherein the method includes measuring, by the voltage-measurement device, voltage between each line and a reference potential.

4. The method according to claim 1, wherein the apparatus includes a half-wave control for at least one of the three lines.

5. The method according to claim 1, further comprising determining a difference between the measured supply voltage of the selective one of the lines and the measured supply voltage of at least one of the other ones of the plurality of lines.

6. The method according to claim 1, wherein the method includes reversing a rotation direction of the electric motor based on a polarity reversal.

7. The method according to claim 6, wherein the reversing is performed by the electronic circuit.

8. The method according to claim 1, wherein the comparison is performed by a comparator.

9. The method according to claim 1, wherein the decoding is performed by signal electronics.

10. The method according to claim 1, wherein the electronic circuit includes (a) a motor switch, (b) a soft start, and/or (c) a converter.

11. The method according to claim 1, wherein the power switches are switched among the four different states by the control unit.

12. The method according to claim 1, wherein the drive includes a rectifier, fed from the lines, having (a) unipolar and/or (b) rectified output voltage having a negative and positive potential.

13. The method according to claim 12, wherein the negative potential is arranged as a reference potential.

14. The method according to claim 1, wherein (a) the drive includes signal electronics provided at a negative potential and/or (b) a voltage between electrical contacts of components of the signal electronics and the negative potential is always lower in terms of absolute value than the voltage to a positive potential.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a system according to an example embodiment of the present invention.

(2) FIG. 2 shows an example of an idealized waveform for a first circuit state where current is blocked on one phase.

(3) FIG. 3 shows an example of an idealized waveform for a second circuit state where only a positive circuit is enabled on one phase.

(4) FIG. 4 shows an example of an idealized waveform for a third circuit state where only a negative circuit is enabled on one phase.

(5) FIG. 5 shows an example of an idealized waveform for a fourth circuit state where current is fully conducted.

(6) FIG. 6 shows a drive of the system

DETAILED DESCRIPTION

(7) Example embodiments of the present invention are explained in more detail below with reference to the figures.

(8) FIG. 1 shows a system according to example embodiments of the present invention. An apparatus 2 is provided which includes switches (S1, S2) for blocking or letting through the positive or negative half waves of a phase. In other words, the apparatus 2 includes a half-wave control 10 for at least one of the three lines.

(9) Switches (S1, S2) are driven from a control, which is to transmit an information stream, entering it as control signal 6, to a drive with the aid of the associated supply line.

(10) FIGS. 1 and 6 show that the drive includes at least one converter 3 for the supply of an electric motor 15. The drive includes the electric motor, preferably in the type of construction integrated with converter 3.

(11) In example embodiments of the present invention, the drive is also able to be implemented with a gear unit as a compact drive. Thus, only a single housing is needed for the gear unit, driven by the electric motor, together with converter 3. Such a drive is therefore able to be supplied both with energy and with information via its system supply lines.

(12) The converter according to FIG. 1 is powered via supply lines (L1, L2, L3). Apparatus 2 according to FIG. 1 is implemented such that switches (S1, S2) are each connected in parallel to a diode, and are connected in series to each other. Therefore, in a first circuit state, entire supply line L3 is interrupted. In a second circuit state, only the positive half wave is enabled; in a third, only the negative. In a fourth circuit state, the supply line is able to be provided for conducting the full current.

(13) The four circuit states are used for coding the information to be transmitted.

(14) In so doing, it is provided that the specific circuit state be reliably recognized in the area of the drive.

(15) The indicated converter of the drive includes a rectifier 5 for three-phase current, to which a smoothing capacitor is assigned on the output side. From the intermediate circuit voltage applied to this capacitor, an inverter, not shown, at an output stage of the converter is also supplied, which in turn supplies the electric motor.

(16) Voltage sensing 4 acquires measured values (L1*, L2*, L3*), which represent the voltage of supply lines (L1, L2, L3) against the negative potential of rectifier 5.

(17) Each of the measured values is evaluated. In an exemplary embodiment according to the present invention, in so doing, the respective average value is formed. The smallest of the three average values is measured at phase L3 at which the different circuit states are used for coding the information to be transmitted. Only in the fourth circuit state is the phase L3 indistinguishable from the other two phases (L1, L2).

(18) Advantageously, the average value is formed over a time span which corresponds to one or more line periods, thus, 20 ms or an integral multiple thereof at 50 Hz. Preferably, however, the time span is selected such that it also represents an integral multiple of one line period of another electrical network. Thus, for example, a selection of 100 ms is advantageous, since the apparatus is therefore usable at 50 Hz and at 60 Hz.

(19) Consequently, recognition of the phase relevant for the information transfer is made possible in a simple manner by generating the mean value of the associated voltage.

(20) Moreover, after recognition of the phase transmitting the information, the difference is formed, by difference device 11, of recognized phase L3 with respect to one of the two other phases (L1, L2). In FIGS. 2, 3, 4, and 5, idealized waveforms are represented for the first, second, third and fourth circuit states. In so doing, the difference of phase L3 with respect to phase L1 may be obtained. The averaging is applied to these characteristics. In this manner, a reliable recognition of the states of the phase containing the information is made possible; the error rate during the transfer of data is thus reducible, as well.

(21) Each of the four circuit states is able to be characterized by threshold values. Even if interference voltages occur, the threshold values are so far from each other that an unequivocal and reliable recognition of the circuit states is feasible. This is a special advantage of this method.

(22) After recognition of the specific circuit state, the drive evaluates the next, also as a function of the previous. A general data transmission is therefore made possible, as well. Thus, not only is information for a stop command, a manual control, a clockwise rotation and a counterclockwise rotation of the motor able to be transmitted, but also even further information such as an error reset or the like. This further information is able to be coded clearly and unmistakably in the time sequence of the circuit states.

(23) The control signal for control 1 is usable, for example, as a 0 volt or 24 volt signal. However, other types of signals are also usable.

(24) According to example embodiments of the present invention, systems in which a three-phase cable was already installed are able to be retrofitted by using the apparatus described herein and replacing the drive by one as described herein.

(25) Example embodiments of the present invention also provide the advantage that the evaluating signal electronics 9 are able to be provided at the potential of the negative potential of the intermediate circuit voltage. Thus, the entire control electronics of the converter are able to be provided there, together with the signal electronics.

(26) The measured-value signals are able to be evaluated in either analog or digital fashion. In the last-named case, to that end, the signal electronics include at least one analog-to-digital converter.

(27) In further exemplary embodiments of the present invention, instead of the averaging, another curve evaluation of the measured-value characteristics is carried out. For instance, the measured value of phase L3 is amplified by a suitable factor. In so doing, the factor is selectable such that in the second circuit state, the positive maximum value is permanently present, in the third, the negative maximum value, in the first, a value which is clearly different from zero and lies between the positive and negative maximum value, and in the fourth, a value which lies in a narrow range around zero.

(28) In further exemplary embodiments of the present invention, instead of the averaging, a different curve evaluation is carried out.

(29) In additional exemplary embodiments of the present invention, the drive is an inverter motor or a gearmotor or an inverter gearmotor. Alternatively, the drive is implemented as a simple electric motor; in that case, however, only the input power is able to be supplied according to the four circuit states.

(30) In further exemplary embodiments according to the present invention, control S is provided with elements for the input of information such as switches, push buttons, slides or rotary knobs or the like. Preferably, therefore, one knob is provided for clockwise rotation and one knob is provided for counterclockwise rotation. Control signals are generated and coded accordingly.

(31) In exemplary embodiments of the present invention, control 1 is connected to a bus system, including a 24 volt supply line. The control signals are thus then able to be generated and coded by a superordinate control.

(32) Apparatus 2 is thus arranged as a type of electronic control unit.

(33) In exemplary embodiments of the present invention, instead of the three-phase line, a single-phase supply line is used. In this instance, the information transmission functions in an analogous manner.

(34) In exemplary embodiments according to the present invention, instead of the drives or converters 3, different devices are connected to which information is transmitted in the same manner as described in the case of the drives. In particular, counting devices such as electricity meters or gas meters are usable as such devices. A time-dependent determination of consumption and/or a remote control and/or remote query of such counting devices is thus made possible.

(35) As stated above, in example embodiments, comparison is carried out with threshold values, and the result of the comparison is used as transmitted information. The comparison is performed by a comparator 12.

(36) As also stated above, in example embodiments, the drive includes an electronic circuit 8 for reversing the sense of rotation of the three-phase power supply.

(37) As further stated above, in example embodiments, the drive has an electronic circuit 8 for including the rotary motion of the rotor 18 of the electric motor 15, in particular, the circuit includes a motor switch 8a, soft start 8b or converter 8c.

(38) As stated above, the voltage-measurement device measures voltage between each line L1, L2, L3 and a reference potential R.