DE10349242B3 - Contactless electrical coupling system for load current and data involves electrical wire carrying medium frequency AC and synchronization pulses and inductive coupling circuit in movable equipment - Google Patents

Abstract

The power transmission and signaling system incorporates a stationary generator feeding medium frequency, especially 25 kHz AC (4) and timing pulse signals (5) into a conductor wire. The stream of data uses a high-frequency carrier with a frequency of 0.1-10 MHz. The synchronization or timing pulse signals have an amplitude of 0.1 to 10 V and a duration of between 0.5 and 3 milliseconds. Receivers on movable pieces of equipment perform a Fourier transform and an inverse Fourier transform.

Description

The The invention relates to a device and a method for non-contact transmission of electrical Performance and information.

Out the publication: BENYOUCEF, D. and others a.: Spectral spreading by linear block codes for OFDM in Powerline Communications' 7th International OFDM Workshop 2002 is a method of transmitting information known; at the via OFDM, that is an orthogonal frequency-division multiplexing method is applied. It is advantageous that even with pronounced disorders Transfer data from a sender to a receiver at a low error rate become. Thus, such methods are suitable for data transmission on industrial power cables.

Out the publication: TIMOTHY, M. u. a::, Robust Frequency and Timing Synchronization for OFDM ', IEEE transactions on Communications, Vol. 12, December 1997 pp. 1613-1621 an OFDM method in which the data stream is an inverse Fourier transform IFFT is subjected and then into a serial data stream is converted to digital-to-analog conversion and Filtering over a transmitter is transmitted on at least one frequency band. Of the receiver leads the received signals to an analog-to-digital converter, whose output data stream is converted into parallel data and a Fourier transform FFT supplied becomes. Necessary for one correct FFT is a synchronization time. This is in the transmitter initially a certain sequence of bit patterns to the IFFT input placed. This episode can also be referred to as pseudonoise training codes become. In the receiver The received, still serial data stream from a part of the receiver Correlation detected, but with a high computing power and appropriate hardware needed becomes. Once the desired correlation is found, the Start time detected and the FFT can be started with the thus determined synchronization signal for the FFT in particular after a predefinable delay time.

Out the publication, Low-Complex Frame Synchronization in OFDM Systems' by Jan-Jaap van de Beek, Magnus Sandell, Michael Isaksson and Per Ola Börjesson, in: Proc. IEEE Int. Conf. Universal Personal Commun., Nov. 1995, pp. 982-986 is an OFDM Known method. There, however, the synchronization signal will be determined by the fact that the data stream of a log-likelihood function is fed which makes the start time determinable. It is, however a high computational effort and appropriate hardware necessary.

From the DE 100 53 373 A1 a device and a method for non-contact energy transfer from a stationary to a moving part is known. In this case, an infeed is connected to an adapter, wherein the adapter is an actively controlled switch 25 and has the associated control electronics with control electronics. In this case, an information transfer is not provided.

From the DE 44 46 779 C2 Such a device and a method for contactless energy transmission is also known, although a U-shaped ferrite core must be used.

From the DE 196 53 522 A1 a method for wireless transmission of energy and data is known in which the data transmission is performed outside the switching edges of the carrier signal. In this time range, however, depending on the type of system still isolated interference voltage pulses may occur, which then lead to incorrect data transmission.

From the DE 42 40 238 C2 is a complex and complex device for non-contact energy and data transmission for single-coil and Zweispulensysteme known in which of several coils of a stationary micro station only a limited phase difference is transmitted.

Of the Invention is therefore based on the object, a device and a method for contactless transmission electrical power and information, with information from stationary transferable to the moving part should be, especially simple and inexpensive.

According to the invention Task in the device for non-contact transmission electrical power and information according to claim 1 and in the method according to the features specified in claim 7. Special embodiments The invention are specified in the subclaims.

Essential features of the invention in the apparatus are that the device is provided for non-contact transmission of electrical power and information from a first part to a movable part relative to the first part,
wherein the first part comprises a primary conductor connected to an AC or AC source having a first frequency, in particular to a medium frequency AC chip or alternating current source,
wherein the movable part comprises a secondary winding which is coupled to the primary conductor electromagnetically, in particular magnetically,
wherein additionally signals with a higher frequency than the first frequency are coupled or modulated onto the primary conductor,
and in time ranges within which the value of the current in the primary conductor is less than a critical current value I_crit, one or more synchronization pulses are additionally coupled or modulated onto the primary conductor.

From Advantage is in the invention that data by modulating transferable to the primary conductor and a particularly simple and inexpensive synchronization method is applicable. In particular, the length of the frame prefix can be reduced. Transmitted in burst mode Data show a higher Useful time, because the delay time is reduced. The necessary Cost of hardware is low and therefore cost-predictable.

at an advantageous embodiment, the movable part and include the first part each at least one receiver or a transmitter, wherein the transmitter comprises a transformation unit provided with a synchronization signal freely chargeable, in particular after a predefinable delay time, and the receiver a corresponding back transformation unit comprising, with a corresponding received synchronization signal freely chargeable, in particular after a predefinable delay time, wherein the synchronization signal from one or more synchronization pulses is determinable. The advantage here is that any transformations are usable, which require a synchronization signal for correct implementation. Because after receiving the synchronization signal, the transformation or inverse transformation be started, in particular after an additional predetermined delay time. Thus leads the inverse transformation the transformed data back to the original data stream. There are So also all transformations usable, the one time zero point for correct back and forth transformation need.

Especially If the transformation is an FFT or IFFT, it belongs to the class of Fourier transformations. The advantage here is that a well-known transformation process usable and therefore inexpensive executable is.

at According to an advantageous embodiment, the transmitter comprises at least a parallel-to-serial converter and a digital-to-analog converter and the receiver comprises at least one Serial-to-parallel converter and an analog-to-digital converter. Advantageous is that known standard components are necessary and thus no expensive special parts need to be made.

at an advantageous embodiment are transmitter and receiver for execution an OFDM data transmission method intended. The advantage here is that a high data transfer rate achievable with a low error rate, although on the transmission link transmit electrical power is and the resulting interference or interference currents very can be big.

Essential features of the invention in the method are that the method for non-contact transmission of electrical power and information from a first part is provided on a relative to the first part movable part,
the first part comprising a primary conductor through which an alternating current is conducted at a first frequency, in particular at a center frequency,
wherein the movable part comprises a secondary winding which is coupled to the primary conductor electromagnetically, in particular magnetically,
wherein in addition to the primary conductor signals with a higher frequency than the first frequency are coupled or modulated,
and that in time ranges within which the current in the primary conductor is less than a critical current value I_krit, one or more synchronization pulses are additionally coupled or modulated onto the primary conductor.

From Advantage is the method that data by means of modulation transferable to the primary conductor and a particularly simple and inexpensive synchronization method is applicable. In particular, the length of the frame prefix can be reduced. Transmitted in burst mode Data show a higher Useful time, because the delay time is reduced. The necessary Cost of hardware is low and therefore cost-predictable.

Further Advantages emerge from the subclaims.

1

feed device

2

portable part

3

inductive coupling

4

electricity in the primary conductor

5

synchronization pulse

The invention will now be explained in more detail with reference to figures:
In the 1 a device according to the invention is shown schematically. In this case, the system consists of a stationary part, comprising a feed device 1 and one or more movable sharing 2 ,

The system is constructed for energy transfer in a known manner, so as in the Scriptures DE 100 53 373 A1 as in the Scriptures DE 197 35 624 C1 as in the Scriptures DE 44 46 779 C2 or the writings cited therein. The invention thus also has the features of these publications in corresponding embodiments of the invention. In such systems, current flows in a primary conductor 4 , The moving part 2 has at least one coil, so transformer head or the like, whereby an inductive coupling to the primary conductor can be produced. In this way, then creates a secondary current to supply the movable part 2 of the system.

As electricity 4 a medium frequency current, for example at about 25 kHz, is used. However, other frequencies from the mid-frequency range are also advantageous.

Essential is in the present invention that the primary conductor in addition to the said medium-frequency current control signals or other signals for information transmission wearing.

In the invention, for this purpose, a data stream with a higher frequency, for example from the MHz range, from the stationary feed device 1 in addition to the medium-frequency electricity intended for transmission of energy 4 modulated. An advantageous modulation frequency has a value between 0.1 and 10 MHz. The stationary feed device 1 additionally includes a corresponding transmitter. About the inductive coupling 3 This higher-frequency signal passes from the stationary part to the moving part 2 where a corresponding receiver is installed. Similarly, in the presence of several moving parts 2 these are provided with such transmitters and Aufmodulationseinrichtungen and in this way data transfers between the moving parts 2 be executed.

The transmitter is schematically in 3 shown. In this case, the data stream is subjected to an inverse Fourier transformation IFFT and then converted into a serial data stream. The associated device is marked P / S. In this case, the part representing the real part and the imaginary part of the transformed information is respectively supplied to a digital-to-analog converter and then to a filter. The two parts are mixed with a signal frequency which is at the imaginary part 90 ° out of phase with the mixed at the real part frequency. In further embodiments of the invention, the mixing is not necessary if the carrier frequency is below 10 MHz. In 3 After merging the two parts and subsequent filtering and amplification, the resulting signal is coupled to the power via a coupling 4 modulated. A detector 6 monitors the electricity 4 to zero crossing or a magnitude falls below a critical current value I_krit and then generates a pulse which is coupled onto the primary conductor. At the same time, a start or synchronization signal is given to the IFFT device.

In the 4 the receiver is shown schematically. In this case, the received signal is decoupled from the secondary current or led out via its own coupling from the primary conductor. After filtering with a bandpass and gain, the signal is again mixed with the medium frequency signal frequency in the manner corresponding to the transmitter and filtered in each case. The resulting signals representing the real and imaginary parts are respectively fed to an analog-to-digital converter and then from an S / P labeled device to a parallel data stream which is retransformed with an FFT to correspond to the original transmitted data stream , In the above-mentioned embodiments with corresponding carrier frequency, in turn, the mixing is omitted. In the 4 represents the detector 7 the receiver determines the synchronization pulse on the primary conductor and forwards it to start or synchronize the FFT, wherein a delay time is set, which takes into account the calculation time for the IFFT. In this way a correct inverse transformation of the data is possible.

In the 2 is an exemplary current flow of the stream 4 with synchronization pulses 5 shown. The synchronization pulses 5 are sent only in time ranges when the value of the stream 4 is below a selected critical current value I_crit. The selected critical current value I_krit is selected such that the synchronization pulse 5 amount is significantly greater than the value of the current 4 , so that a sufficiently large signal-to-noise ratio is available.

advantage the method according to the invention is that synchronization is extremely easy and executed quickly is. The proportion of time for the transfer the payload, ie the information actually to be transmitted to the total for the transfer to disposal standing time is increased. Furthermore When using burst mode, the delay time is greatly reduced and the useful life increases. The amount of hardware is very low.

Advantageously, the pulse has a pulse duration which is between 0.5 and 3 μs. However, other pulse durations are also beneficial. An advantageous pulse height is between 0.1 V to 10 V, where the numbers depend on the strength of the fault signals, which in turn are different in different systems.

In further embodiments of the invention, instead of a synchronization pulse 5 two or more synchronization pulses sent in quick succession, in particular within the mentioned time ranges. Thus, a further reduction of the error rate is foreseeable.

at further embodiments of the invention The data transformed by the IFFT unit is buffered written, then after receiving the synchronization signal immediately is freely available. Thus, there is no delay time in the receiver too consider, however, the FFT unit of the receiver in turn has some Calculation time needed. Here is the delay time the analog-digital conversion and the delay time the digital-to-analog conversion, in particular by Default.

at further embodiments of the invention, where the system is no interference in the time range of the zero crossing, are also the synchronization signals dispensable and the zero crossing itself as a synchronization signal usable.

Claims (10)

A device for non-contact transmission of electrical power and information from a first part to a part movable relative to the first part, the first part comprising a primary conductor connected to an AC or AC source having a first frequency, the movable part comprising a secondary winding electromagnetically coupled to the primary conductor, characterized in that signals having a higher frequency than the first frequency are additionally coupled or modulated onto the primary conductor, and that in time ranges within which the values of the current in the primary conductor are smaller in magnitude than a critical one Current value I_krit, one or more synchronization pulses are additionally coupled to the primary conductor or modulated. Device according to claim 1, characterized in that that the AC or AC source with a first Frequency a medium frequency AC or AC source is. Device according to one of the preceding claims, characterized characterized in that the movable part and the first part respectively at least one recipient or a transmitter, wherein the transmitter is a transformation unit includes, which is freely chargeable with a synchronization signal, in particular after a predefined delay time, and the receiver a corresponding back transformation unit comprising, with a corresponding received synchronization signal freely chargeable, in particular after a predefinable delay time, wherein the synchronization signal from one or more synchronization pulses is determinable. Device according to one of the preceding claims, characterized characterized in that instead of the synchronization pulses of the respective Sign change of the primary current is used or this sign change to generate the Pulse is used. Device according to one of the preceding claims, characterized characterized in that the transformation is an FFT or IFFT, ie belongs to the class of Fourier transformations. Device according to one of the preceding claims, characterized in that the transmitter has at least one parallel-to-serial converter and a digital-to-analog converter and the receiver at least a serial-to-parallel converter and an analog-to-digital converter. Device according to one of the preceding claims, characterized characterized in that sender and receiver to carry out a OFDM data transmission method are provided. Method for non-contact transmission of electrical Performance and information from a first part to a relative to first part moving part, the first part being a primary conductor includes, through which an alternating current with a first frequency passed becomes, wherein the movable part comprises a secondary winding connected to the primary conductor is electromagnetically coupled, characterized in that on the primary conductor additionally Signals with a higher Frequency be coupled or modulated as the first frequency, and that in time ranges, within which the current in the primary conductor is less than a critical current value I_crit, one or more Synchronization pulses in addition on the primary conductor be coupled or modulated. A method according to claim 8, characterized in that the data with an OFDM Ver to be transferred. Method according to claim 8 or 9, characterized that instead of the synchronization pulses of the respective sign change of the primary current is used or this sign change to generate the Pulse is used.