Apparatuses and methods for transmitting a communication signal and electric power between two user stations of a bus system

Abstract

A method of transmitting a communication signal and electric power between two user stations of a bus system includes coupling the communication signal into a bus line via a low-pass filter that filters the communication signal, such that signal frequencies below a cut-off frequency of the low-pass filter are coupled into the bus line of the bus system. The method also includes coupling, using a power coupling device, electric power in the form of a high-frequency signal into the bus line, transmitting the communication signal and the electric power as a bus signal to an electrical load using the bus line, and decoupling the communication signal from the bus line via a low-pass filter that filters the bus signal, such that signal frequencies below the cut-off frequency of the low-pass filter are decoupled from the bus line of the bus system.

Claims

1. An apparatus for inputting a communication signal and electric power for at least one electrical load into a bus line for a bus system, comprising: a low pass filter configured to filter the communication signal, such that signal frequencies below a cutoff frequency of the low pass filter are input into the bus line of the bus system; and a power input device configured to input electric power as a high frequency signal into the bus line, wherein the power input device is configured to at least one of spread and jitter a frequency of the high-frequency signal in a frequency domain, wherein: the power input device includes a switched mode power supply unit configured to generate the high frequency signal, and an input of the communication signal is configured in regard to a communication for which, at least intermittently, exclusive, collision free access by one of at least two subscriber stations of the bus system to the bus line is ensured, wherein the power input device further includes a downstream high pass filter configured to filter a signal of the switched mode power supply unit, such that signal frequencies above a cutoff frequency of the high pass filter are input into the bus line.

2. A method for transmitting a communication signal and electric power between two subscriber stations of a bus system, comprising: inputting the communication signal into a bus line of the bus system via a low-pass filter that filters the communication signal, such that signal frequencies below a cutoff frequency of the low-pass filter are input into the bus line; inputting, using a power input device, electric power as a high frequency signal into the bus line; transmitting the communication signal and the electric power as a bus signal to an electrical load using the bus line; outputting the communication signal from the bus line via another low-pass filter that filters the bus signal, such that signal frequencies below a cutoff frequency of the other low-pass filter are output from the bus line; and outputting, using a power output device, electric power as a high frequency signal from the bus line for the electrical load, wherein the power input device is configured to at least one of spread and jitter a frequency of the high-frequency signal in a frequency domain, wherein: the power input device includes a switched mode power supply unit configured to generate the high frequency signal, and an input of the communication signal is configured in regard to a communication for which, at least intermittently, exclusive, collision free access by one of at least two subscriber stations of the bus system to the bus line is ensured, wherein the power input device further includes a downstream high pass filter configured to filter a signal of the switched mode power supply unit, such that signal frequencies above a cutoff frequency of the high pass filter are input into the bus line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure is described in more detail below using exemplary embodiments and with reference to the accompanying drawing, in which:

(2) FIG. 1 shows a simplified block diagram of a bus system according to a first exemplary embodiment;

(3) FIG. 2 shows a simplified frequency response of a low-pass filter of the bus system of FIG. 1;

(4) FIG. 3 shows a simplified frequency response of a high-pass filter of the bus system of FIG. 1;

(5) FIG. 4 shows a simplified block diagram of a bus system according to a second exemplary embodiment; and

(6) FIG. 5 shows a simplified block diagram of a bus system according to a third exemplary embodiment.

(7) In the figures, elements that are the same or have the same function are provided with the same reference symbols, unless indicated otherwise.

DETAILED DESCRIPTION

(8) FIG. 1 shows a bus system 1 that can be used in a vehicle, in particular a motor vehicle, an aircraft, etc., or in hospitals, etc.

(9) In FIG. 1, the bus system 1 has a first subscriber station 10, a power supply device 15, a second subscriber station 20, a first apparatus 30, a second apparatus 40 and a bus line 50 that interconnects the subscriber stations 10, 20, the power supply device 15 and an electrical load 60 depicted as an electric resistor. The electrical load 60 is an electrical appliance that needs electric power for operation.

(10) The bus system 1 may be, by way of example, a CAN bus system, a CAN FD bus system, a LIN bus system, a bus system in accordance with the PSI5 standard or the FlexRay standard, etc. Quite generally, the bus system in the present exemplary embodiment is configured for a communication for which, at least intermittently, exclusive, collision-free access by one of the subscriber stations 10, 20 to the bus line 50 is ensured.

(11) The first subscriber station 10 may be, by way of example, a controller or a display apparatus of a motor vehicle. The second subscriber station 20 may be, by way of example, a sensor of a motor vehicle.

(12) The first subscriber station 10 and the power supply device 15 are connected to the bus line 50 via the first apparatus 30. The second subscriber station 20 and the electrical load 60 are connected to the bus line 50 via the second apparatus 40. The bus line 50 is used to transmit a bus signal 51 to the second subscriber station 20. The apparatus 30 inputs a communication signal 52 and a high-frequency signal 53, which is a high-frequency electric current delivering electric power, into the bus line 50 as bus signal 51. The second apparatus 40 outputs the bus signal 51 received by it from the bus line 50 as communication signal 54 and high-frequency signal 55.

(13) For this, the apparatus 30 has a low-pass filter 31 that passes only the signal frequencies of the communication signal 52 below its cutoff frequency f.sub.GTP, as shown in FIG. 2. FIG. 2 shows the frequency response of the ratio A of output voltage to input voltage of the low-pass filter 31 over frequency f.

(14) Therefore, only the signal frequencies of the communication signal 52 below the cutoff frequency f.sub.GTP of the low-pass filter 31 are input into the bus line 50 of the bus system 1. The low-pass filter 31 may be configured as a resistor/capacitor combination, also generally called an RC element. The low-pass filter 31 is used for protecting the apparatus 30 against any radiated electromagnetic interference from other electrical appliances of the bus system 1 or its surroundings, so that the requirements in regard to electromagnetic compatibility (EMC) are observed.

(15) Moreover, the apparatus 30 has a power input device 32 that uses a high-pass filter 33 to input a high-frequency signal 53 into the bus line 50. The high-frequency signal 53 is a high-frequency electric current delivering electric power for the electrical load 60. The high-frequency signal 53 can thus also be referred to as a high-frequency power signal.

(16) The electric current is delivered by the power supply device 15 and converted into the high-frequency signal 53 by means of the power input device 32. The power input device 32 may accordingly be configured as a high-frequency generator and/or switched-mode power supply unit.

(17) The high-pass filter 33 of the apparatus 30 passes only the signal frequencies of the high-frequency signal 53 above its cutoff frequency f.sub.GHP, as shown in FIG. 3. FIG. 3 shows the frequency response of the ratio A of output voltage to input voltage of the high-pass filter 33 over frequency f.

(18) Therefore, only the signal frequencies of the high-frequency signal 53 above the cutoff frequency f.sub.GHP of the high-pass filter 33 are input into the bus line 50 of the bus system 1. The high-pass filter 33 may be configured as a capacitor/resistor combination, which is also generally referred to as a CR element.

(19) Preferably, the cutoff frequency f.sub.GTP and the cutoff frequency f.sub.GHP are so far apart (f.sub.GTP<f.sub.GHP) that the alternate influencing is very low. In this case, the spectra (frequencies used) of the communication signal 52 and the high-frequency signal 53 provided for providing the electric power do not overlap, since the signals are adequately reciprocally attenuated on the two paths. For filtering, the alternate influencing can be decreased e.g. by increasing the selectivity.

(20) The cutoff frequency f.sub.GTP of the low-pass filter 31 and the cutoff frequency f.sub.GHP of the high-pass filter 33 may be in the range from 20 to 50 MHz. The choice of cutoff frequencies f.sub.GTP, f.sub.GHP is accordingly geared to the symbol rate or data rate at which the bus system 1 is operated. At the frequencies in the range from 20 to 50 MHz, typically only a few signal components of the communication signal 52 are present in the case of a CAN bus system.

(21) The choice of frequency fp of the high-frequency signal 53 for power transmission can be chosen according to different EMC criteria. By way of example, the high-frequency signal 53 can also be spread and jittered over a frequency range in order to lower the power spectral density of the signal 53. To spread or scatter in the frequency spectrum, it is also possible, in addition or as an alternative to the jittered signals, for pseudo-noise signals and/or multiple carriers to be used, as in the case of a clock of a central processing unit (CPU).

(22) As FIG. 1 moreover shows, the apparatus 40 likewise has a low-pass filter 41 and a high-pass filter 42. The low-pass filter 41 has the same function as the low-pass filter 31. The high-pass filter 42 has the same function as the high-pass filter 33.

(23) The second apparatus 40 moreover has a power output device having a switched-mode power supply unit 431 that supplies the high-frequency signal 53 or power signal to a low-pass filter 432. The low-pass filter 432 also has the same function as the low-pass filter 31.

(24) Therefore, the second subscriber station 20 has not only low-pass filtering performed for the low-pass filter 41 to obtain the communication signal 54 but also output of a high-frequency signal 55 by the high-pass filter 42 matched to the characteristic impedance of the bus line 50. In this case, the switched-mode power supply unit 43, which is configured as a rectifier, is subsequently used to perform rectification and optional low-pass filtering. This achieves smoothing of the signal 55, which serves as a supply of electric power to the electrical load 60.

(25) The bus line 50 can therefore be used to transmit a message in the form of the communication signal 52 and the communication signal 54 received on the part of the subscriber station 20 between the subscriber stations 10, 20. Additionally, the bus line 50 is also used to provide the power supply for the electrical load 60 in the case of the second subscriber station 20.

(26) In one configuration, the first subscriber station 10 may also be an already existing CAN subscriber station (CAN node) that is connected to an existing bus line 50 by means of the low-pass filter 31. For the other CAN subscriber stations, an appropriate optional addition by means of a low-pass filter 41 is performed.

(27) Therefore, in the bus system 1 described above, the subscriber station 10 has conversion of an electric current for the supply of power to the electrical load 60 into a high-frequency signal 53 performed e.g. by the switched-mode power supply unit 32 and said high-frequency signal is input into the bus line 50 via the high-pass filter 33, which is used for decoupling the impedance in the low frequency range. In this context, the output-side matching of the high-pass filter 33 to the characteristic impedance of the bus line 50 is advisable.

(28) As a result of the EMC criteria, the field of application is particularly advantageously regarded as simple sensors, which are more robust toward radiated electromagnetic interference, since the possible radiation/power density falls proportionally with the power draw. Particularly for simple sensors, the large numbers mean that a great savings potential for the wiring of the bus system 1 arises in this case, however.

(29) FIG. 4 shows a bus system 2 according to a second exemplary embodiment. The bus system 2 according to the second exemplary embodiment is largely designed in the same manner as described in regard to the bus system 1 according to the first exemplary embodiment.

(30) In contrast to the bus system 1 according to the first exemplary embodiment, however, the bus system 2 according to the second exemplary embodiment has an apparatus 35 that has no low-pass filter 31 as in the case of FIG. 1. This may be advantageous in the case of a CAN bus system 2, for example, in which the CAN communication control device (CAN controller) already performs the function of the low-pass filter 31, or if the situation exists that no additional components are desirable for reasons of cost. In this case, it is then advantageous to establish the high-frequency signal 53 or power signal in a sufficiently high frequency range in which the signal frequencies of the communication signal are influenced only to a small extent (the usual spectrum generally drops off sharply at high frequencies).

(31) FIG. 5 shows a bus system 3 according to a third exemplary embodiment. The bus system 3 according to the third exemplary embodiment is largely designed in the same manner as described in regard to the bus system 1 according to the first exemplary embodiment.

(32) In contrast to the bus system 1 according to the first exemplary embodiment, the bus system 3 according to the third exemplary embodiment has the input of the high-frequency signal 53 for supplying electric power to the electrical load 60 provided at a different location on the bus line 50 than the input of the communication signal 52. The high-frequency signal 53 can be input at any location on the bus line 50. Therefore, the bus system 3 has an apparatus 37 that likewise has no low-pass filter 31, as described for the second exemplary embodiment.

(33) All the previously described configurations of the bus systems 1, 2, 3, the subscriber stations 10, 20, the bus line 50 and the method can be used individually or in every possible combination. In particular, all the features of the previously described exemplary embodiments can be combined as desired or else omitted. Additionally, the following modifications, in particular, are conceivable.

(34) The bus system 1, 2, 3, with the bus line 50 according to the exemplary embodiments, is described with reference to a bus system based on the CAN protocol. The bus system according to the exemplary embodiments may also be another kind of communication network, however. It is advantageous, but not a necessary requisite, for exclusive, collision-free access by a subscriber station 10, 20 to a shared channel to be ensured, at least for particular periods of time, on the first bus system in the communication system 1.

(35) The number of subscriber stations 10, 20 can be chosen as required. It is also possible for more than two subscriber stations. It is also possible for there to be only subscriber stations 10 or subscriber stations 20 in the bus system 1, 2, 3.

(36) As a modification to the bus systems 1, 2, 3, it is also conceivable to use the ground as an additional connection between the subscriber stations 10, 20 for the transmission of the high-frequency signal 53. This is possible through phantom powering, for example.

(37) In all the exemplary embodiments, the filters 31, 33, 41, 42, 432 may be configured in a different form. By way of example, an embodiment with/without an isolating transformer or common mode choke (CMC) can be used. Moreover, a combination of the low-pass filters 31, 41, 432 with a common mode choke (CMC) is conceivable.

(38) To generate the HF power on the power supply device 15 as a source, it is possible for different methods to be used. The aforementioned switched-mode power supply units are just one of many options.

(39) At the sink or electrical load 60, it is possible for various principles to be used to implement the switched-mode power supply unit 431 as a rectifier. By way of example, a rectification function is also possible with a diode circuit.

(40) The matching of the high-pass filters 33, 42 to the bus line 50 or the characteristic impedance thereof is possible adaptively, that is to say possible in a manner matched to the respectively prevailing circumstances. This allows even possibly occurring fluctuations as a result of different loads, such as multiple subscriber stations 10, 20, to be equalized.

(41) The power supply device 15 may be integrated in the subscriber station 10 or 20 or else provided separately.

(42) The electrical load 60 does not have to be integrated in the subscriber station 20, such as when the subscriber station 20 is a sensor, for example. The electrical load 60 may also be provided separately or in addition to the subscriber station 20, for example as a further sensor.

(43) In the product or the subscriber stations 10, 20, a combination with other communication systems is conceivable, which means that the bus line 50 can be used in the HF domain at the same time besides the CAN system by parallel HF communication systems, preferably decoupled from one another.