JP2004304747A - Switching power source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power source having a function not only for supplying power to an external apparatus but also for exchanging a signal with the external apparatus. <P>SOLUTION: A communication means 20 is provided for allowing the external apparatus to mutually exchange communication data with a power line 10 of an AC power source as a communication interface when a coupling element 17 is connected between a primary winding wire of a transformer 12 and an FET 13 and the FET 13 is turned on. The communication means 20 includes a high frequency circuit 21, an encryption/decryption circuit 22, a modulation/demodulation circuit 23 and a signal processing circuit 24 and when personal computers PC1, PC2-PCN of external apparatuses transmit communication data, the transmitted data are modulated, encrypted and superimposed on an AC voltage as a high frequency so as to be outputted. When the communication data superimposed on the AC voltage are inputted, on the other hand, the data are decrypted and demodulated on the basis of the communication data so as to be inputted to the PC1, PC2-PCN of the external apparatuses. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a switching power supply, in particular, converts an AC input voltage into a predetermined AC voltage by a switching element, applies the converted AC voltage to a primary winding of a transformer, and extracts the AC voltage from a secondary winding of the transformer. The present invention relates to a switching power supply that smoothes a voltage and outputs a DC voltage to an output terminal.
[0002]
[Prior art]
In a conventional switching power supply, for example, when it is connected to a power line of an AC power supply, it is converted into a predetermined AC voltage by a switching element such as a field effect transistor (FET), and the converted AC voltage is converted to a primary voltage of a transformer. A voltage is generated in the secondary winding of the transformer by being applied to the winding. The generated voltage is output to an output terminal as a DC voltage by being smoothed.
[0003]
Various electric products such as a TV, a refrigerator, and a personal computer (hereinafter, abbreviated as a personal computer) in a home are connected to the output terminal. On the other hand, in a workplace of a company or the like, when a plurality of personal computers are connected to perform LAN (Local Area Network) communication with each other, a LAN card and a terminal adapter are installed in both personal computers, and a LAN cable is installed. It is necessary to connect with.
[0004]
[Problems to be solved by the invention]
As described above, a conventional switching power supply can supply DC power to external devices by being connected to an AC power supply, but it merely supplies power to external devices. It did not have the function of.
When the external device connected to the switching power supply is a personal computer, communication can be performed by connecting both computers by means of a LAN cable or the like, but communication data is transmitted / received when not connected by the LAN cable. There were problems such as being unable to do so. When the communication between both computers is wireless such as a wireless LAN, there is no wiring, but if there is no base station equipment such as an access point or equipment such as a repeater required for the wireless LAN, communication data is transmitted and received. There was a problem such as not being able to do.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a switching power supply having a function of not only supplying power to an external device but also transmitting and receiving a signal to and from the external device in view of the above-described problems of the related art.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention employs the following solutions.
That is, the invention according to claim 1 converts an AC input voltage into a predetermined AC voltage by a switching element, applies the converted AC voltage to a primary winding of a transformer, and extracts the AC voltage from a secondary winding of the transformer. In a switching power supply that smoothes an AC voltage and outputs it to an external device connected to an output terminal, when a primary winding of the transformer is applied, an external device connected to an output terminal of a secondary winding of the transformer On the other hand, there is provided a communication unit for transmitting and receiving a communication signal using the power line of the AC power supply as a communication line.
[0007]
According to the switching power supply according to the first aspect, when a switching power supply is connected to each of the power lines of the AC power supply, and an external device is connected to each of the switching power supplies, a signal from the external device on one switching power supply side is output. When the communication signal is transmitted to the other switching power supply, it is transmitted to the external device via the communication means on the switching power supply side, so that the external device on one switching power supply side and the external device on the other switching power supply side Communication can be performed.
[0008]
The invention according to claim 2 is the switching power supply according to claim 1, wherein the communication means includes a coupling element connected between a primary winding of the transformer and a switching element.
According to the switching power supply according to the second aspect, not only the power supply as an external device can be obtained by the transformer, but also the power supply of the communication means can be obtained by the coupling element, and when the switching element is in the ON state. , Communication can be reliably performed.
[0009]
According to a third aspect of the present invention, in the switching power supply of the first or second aspect, based on the duty cycle of the switching power supply, the compressed communication is transmitted at a value slightly larger than the reciprocal of the duty cycle, while the compressed communication is transmitted. It is characterized by having means for expanding and taking in communication data.
[0010]
According to the switching power supply according to the third aspect, the communication means transmits the communication data compressed at a value slightly larger than the reciprocal of the duty cycle based on the duty cycle of the switching power supply, or expands the compressed data. When a compressed communication signal is input, the receiving side can receive a so-called seamless signal and perform stable communication, thereby enabling the external power supply to be turned on. Even if the communication is performed only synchronously, the possibility that the communication data leaks can be eliminated.
[0011]
According to a fourth aspect of the present invention, in the switching power supply according to any one of the first to third aspects, the communication unit turns on / off a power supply to the external device and supplies power to the external device. It is characterized in that a control circuit is provided which selectively performs the variable operation by an external communication signal obtained through the power line.
According to the switching power supply according to the fourth aspect, not only can the selected external device be turned on / off, but also the applied voltage can be varied. For example, when the external device is a lighting fixture, In addition, the lighting equipment can be turned on / off, and the lighting equipment can be dimmed.
[0012]
According to a fifth aspect of the present invention, in the switching power supply according to any one of the first to fourth aspects, the communication unit includes a high-frequency transmitting / receiving circuit, an encryption / decryption circuit, a scramble circuit, a modulation / demodulation circuit, and a signal processing circuit. It is characterized by having.
According to the switching power supply according to the fifth aspect, when the external devices connected via the switching power supply connected to the AC power supply are personal computers, mutual communication can be reliably performed, and encryption / decryption can be performed. The circuit enables safe and reliable communication with only the intended communication partner.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific examples of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a switching power supply according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram showing communication means provided in the switching power supply.
The switching power supply according to the present embodiment is for supplying power to an external device by being connected to the power line 10 of the AC power supply shown in FIG. 2, and as shown in FIG. A field effect transistor (hereinafter, referred to as an FET) as a switching element that has a smoothing circuit including a smoothing capacitor 11 and a rectifier diode 16 in a preceding stage, and switches an AC power supply to a predetermined AC voltage in a subsequent stage of the primary side. 13).
[0014]
A diode 14 and a smoothing capacitor 15 are provided on the secondary side of the transformer 12. When the FET 13 is periodically turned on / off on the primary side of the transformer 12, an AC voltage is applied to the primary side accordingly. As a result, a secondary voltage is induced on the secondary side of the transformer 2, and the secondary voltage is half-wave rectified by the diode 14, then smoothed by the capacitor 15, and connected to an output terminal (not shown). A DC voltage is supplied to an external device.
The external devices include, for example, personal computers PC1, PC2,... PCN as shown in FIG. 2, and PC1, PC2... PCN are connected to the output terminals of the switching power supply connected to the power line 10 of the AC power supply. In FIG. 2, reference numerals 1, 2,... N indicate respective switching power supplies.
[0015]
In the switching power supply, a coupling element 17 is connected in series between the primary winding of the transformer 12 and the FET 13 on the primary side of the transformer 12, and when the FET 13 is in the ON state, the external device is connected to the power line 10 of the AC power supply. A communication means 20 for transmitting and receiving communication data to and from each other is provided so that the communication data can be used as an interface for communication.
[0016]
When the personal computer PC1, PC2,... PCN are connected to the power line 10 and are in the ON state as shown in FIG. 2, for example, communication data is output from one PC1 to the other PC2. Then, communication data from the PC 1 flows through the power line 10 to the primary sides of the switching power supplies 2 to N connected to the PCs 2 to PCN. The other switching power supply 2 selectively receives the communication data from the PC 1, and the communication means 20 provided in the other switching power supply 2 outputs the communication data from the personal computer PC1 to the other personal computer PC2. Communication data from the personal computer PC1 can be transmitted to the personal computer PC2.
[0017]
In this case, the transmission information from the personal computer PC2 is output to the personal computer PC1 in the opposite form to the above, so that the personal computer PC1 can communicate with the personal computer PC1. It is configured to be able to communicate as. Therefore, although not shown in detail, the personal computers PC1, PC2,..., PCN are configured to transmit and receive communication data when connected to the output terminal of the switching power supply.
[0018]
More specifically, as shown in FIG. 1, the communication means 20 includes a high-frequency transmission / reception circuit (RF) 21, a scramble circuit 25, a modulation / demodulation circuit (MODEM) 23, and a signal processing circuit 24, and is connected to an external terminal. When the personal computers PC1, PC2,..., PCN transmit communication data, the transmission data is modulated and scrambled and output by superimposing it as an RF voltage on an AC voltage, while the communication data superimposed on the AC voltage is input. , PCN, PC2,... PCN connected to external terminals.
[0019]
In this case, the communication between the personal computers is performed by using the same protocol as in the case of the Internet communication which is usually performed. Therefore, the communication means 20 has the same function as a general communication LAN card or terminal adapter provided in the personal computers PC1, PC2,. To send and receive.
[0020]
Further, in order to transmit and receive communication data more safely and reliably, for example, between the scramble circuit 25 and the modulation / demodulation circuit 23, the encryption / decryption circuit 22 is provided so that only the corresponding personal computers can communicate accurately. It is preferable to connect. Further, although not shown, when the power line communication is a narrow band communication, a circuit having a carrier sense function for determining a use condition of a carrier wave (carrier) frequency or the possibility of transmission at that frequency, A monitoring function of a bit error rate (BER) or a frame error rate (FER) is provided, and a circuit for determining whether transmission is possible according to the situation is provided. If a function of monitoring an error rate (BER) or a frame error rate (FER) is provided and a circuit for determining whether or not transmission is possible according to the situation is added, it goes without saying that better communication can be performed. As shown in FIG. 2, such a communication means 20 causes the high frequency circuit 21 to oscillate a high frequency of a predetermined frequency according to a command from a control circuit 26 connected between the secondary winding of the transformer 12 and the gate of the FET 13. It operates based on the synthesizer 27.
[0021]
Such a communication means 20 is turned on in conjunction with the turning on of the FET by the control circuit 26. In order to reliably synchronize communication signals during communication, at the time of switching of the power supply during communication, that is, at the time of turn-on / turn-off. It is preferable not to transmit or receive.
[0022]
Since the switching power supply of this embodiment is configured as described above, switching power supplies 1, 2,... N are respectively connected to the power line 10 of the AC power supply as shown in FIG. PC2... PCN are connected and in the on state.
[0023]
At this time, when the communication data is transmitted from one personal computer PC1 to the other personal computer PC2, when the FET 13 on the primary side of the transformer 12 in the switching power supply 1 on the personal computer PC1 side is in an on state, the signal is output from the personal computer PC1. When the communication data is converted into communication data via the communication means 20 and the coupling element 17 incorporated in the switching power supply 1 to which the personal computer PC1 is connected, and transmitted via the power line 10, the communication partner The communication means 20 built in the switching power supply 2 on the side decodes the communication data and processes it as a normal signal band used on the personal computer, thereby outputting the data to the personal computer PC2 connected to the switching power supply 2. It will be.
[0024]
As a result, communication data from the personal computer PC1 is transmitted to the personal computer PC2 via the switching power supplies 1 and 2 and the power line 10, and this is performed in the same manner between the personal computers PC1 to PCN. There is no need to connect with a cable. Therefore, it is not necessary for the personal computer to install an adapter such as a LAN card or a modem for communication, and the internal configuration of the personal computer can be simplified accordingly, so that the personal computer can be reduced in size and cost can be reduced. This is the same not only for a wired LAN but also for a wireless LAN. In place of wiring, base station equipment such as an access point required for the wireless LAN or equipment such as a repeater is not required, and a personal computer is not provided with wireless communication. Since it is not necessary to add a communication facility and the internal configuration of the personal computer can be simplified accordingly, the personal computer can be reduced in size and cost. The same applies to an LON (Local Operating Network) system or the like that realizes communication between various sensors and various actuators.
[0025]
Although the coupling element 17 is connected between the primary winding of the transformer 12 and the FET 13, the communication means 20 is configured so as to be able to reliably transmit a signal in synchronization with a communication partner. Thus, communication can be performed satisfactorily.
[0026]
FIG. 3 shows a switching power supply according to a second embodiment of the present invention. This embodiment differs from the above-described embodiment in that a compression / decompression circuit 28 for compressing or decompressing data is provided between the modem 23 and the signal processing circuit 24 of the communication means 20.
[0027]
Since the communication means 20 communicates only when the FET 13 is on and in synchronization with the other party, communication can be performed only intermittently.
[0028]
Therefore, as shown in FIG. 4B, for example, when transmitting communication data, the compression / expansion circuit 28 compresses the transmission data D by delaying it by one cycle and transmits the compression data D1. . The control circuit 26 monitors the duty cycle of the switching power supply, and instructs the compression / expansion circuit 28 to compress the communication data with a value slightly larger than a value obtained by dividing one cycle of the switching power supply by the primary power supply time. Is performed. At the time of reception, as shown in FIG. 3C, the received compressed data is expanded based on the compression ratio of the transmitting side folded as information in the received signal, and the expanded data D2 (= D ) Is generated and the decompressed data D2 is obtained.
Therefore, during transmission, the transmission means transmits the transmission data as compressed data delayed by one cycle, and when the compressed transmission data is input, the data is expanded and read by the compression / expansion circuit. It has become.
In the case of a switching power supply, the turn-on (T-on) and the turn-off (T-off) of the FET 13 contain large and broadband noise, and communication between the turn-on and the turn-off is avoided. The reason why the compression ratio is set to a value slightly larger than a value obtained by dividing one cycle of the switching power supply by the primary-side power supply time is to avoid transmission at the time of turn-on and turn-off.
[0029]
According to this embodiment, based on the duty cycle of the switching power supply, when transmitting communication data compressed with a value slightly larger than a value obtained by dividing one cycle of the duty cycle, or when receiving compressed data, Since the signal is expanded at the transmission-side compression rate built into the signal, when a compressed communication signal is input, the receiving side can receive a so-called seamless signal and perform stable communication. be able to.
[0030]
5 and 6 show a switching power supply according to another embodiment of the present invention. In the above-described embodiment, an example is shown in which only one personal computer PC1, PC2,... PCN is connected to one switching power supply. In this embodiment, however, the switching power supply 1 is connected to the power line 10 as shown in FIG. A personal computer PC1 is connected via the switching power supply 2, and the personal computer PC2, the lighting fixture 30, and the refrigerator 40 are connected via the switching power supply 2. That is, a plurality of electrical products such as a personal computer (PC1, PC2), a lighting device 30, and a refrigerator 40 are connected to the switching power supply as external devices, and power can be supplied to each of them. In this example, the lighting fixture 30 in this case has a dimming function that can change the amount of light.
[0031]
The communication means 20 built in the switching power supplies 1 and 2 outputs not only a signal for outputting an on / off signal to an external device in accordance with a command from the personal computer PC1, but also a signal for changing the amount of light in the on state. Can be transmitted via the power line 10, and by taking in the signal transmitted via the power line 10, the power supply to the external device can be turned on / off and the light amount can be changed in the on state. Has become.
[0032]
Therefore, as shown in FIG. 5, the communication means 20 of the switching power supply 2 is provided with an FET 19 for turning on / off the power to the external device or changing the voltage by the control circuit 26, and transmits the signal from one personal computer PC1. The signal processing circuit 24 of the personal computer PC2 processes the signal based on the received signal, and accordingly, the control circuit 26 selectively controls the FET 19, that is, turns on and off the power to the lighting equipment 30 and the refrigerator 40. It is possible to control the lighting by changing the input voltage to the lighting fixture 30.
[0033]
Therefore, as the communication means 20 of this embodiment, not only the signal processing circuit 24 transmits and receives the communication signal from the personal computer as in the above-described embodiment, but also the lighting fixture 30 and the refrigerator 40 connected to the switching power supply. The power supply to such an external device can be turned on / off, and the supply voltage can be changed. This can be applied not only to the lighting apparatus 30 and the refrigerator 40 but also to a case where another electric product such as a TV is connected.
[0034]
Also, an example is shown in which the coupling element 17 of the communication unit 20 is configured by a transformer including a secondary winding induced by a winding provided on the primary winding side of the transformer 12, but is not limited thereto. Instead, the secondary winding of the power conversion transformer 12 can be used, and for example, a transistor and a diode of a photocoupler can be used instead. In short, the communication unit 20 is turned on when the FET 13 as a switching element is turned on. Can be used as long as they can communicate.
[0035]
【The invention's effect】
As described above, according to the present invention, when a communication signal from an external device on one switching power supply connected to a power line is transmitted to the other switching power supply connected to the power line, the switching Since the external device can be received by the external device through the communication means on the power source side, it is possible to communicate with the external device on one switching power source side and the external device on the other switching power source side. Not only can a power source be obtained, but also communication can be reliably performed when the switching element is on.
In addition, since the power line is used as a communication line, a communication line that has been required separately from the power line is unnecessary.
The switching power supply having the function of transmitting and receiving signals to and from the external device according to the present invention can be provided with a lightning protection circuit or a fuse as a safety device, which is usually installed in the power supply, as compared with a case where a single communication device using a power line is separately used. And the power conversion transformer can be used as a coupling element, and as shown in the second embodiment of the present invention, the ON / OFF of the power output or the voltage adjusting function can be easily folded. Has advantages.
[0036]
Also, at the time of transmission, if a compressed communication signal is input, the receiving side can continuously receive the signal, so that stable communication can be performed, thereby synchronizing only when the power is on. Even if the communication is performed, there is an effect that the possibility that communication data leaks can be eliminated.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a switching power supply according to a first embodiment of the present invention.
FIG. 2 is a circuit diagram showing an example of using the switching power supply of FIG.
FIG. 3 is a circuit diagram showing a switching power supply according to a second embodiment of the present invention.
4A and 4B are diagrams showing the operation of a compression / expansion circuit provided in the communication means, wherein FIG. 4A is an explanatory diagram showing communication data, FIG. 4B is an explanatory diagram showing a transmission signal, and FIG. FIG. 4 is an explanatory diagram showing data.
FIG. 5 is a circuit diagram showing a switching power supply according to another embodiment of the present invention.
FIG. 6 is a circuit diagram showing an example of use of the switching power supply of FIG.
[Explanation of symbols]
1, 2 to N: Switching power supply 10: Power line 12 of AC power supply ... Transformer 13: Switching element (FET)
17 Coupling element 20 Communication means 21 High frequency circuit 22 Encryption / decryption circuit 23 Modulation / demodulation circuit 24 Signal processing circuit 25 Scramble circuit 26 Control circuit 28 Compression / expansion circuit

Claims (5)

The AC input voltage is converted to a predetermined AC voltage by a switching element, the converted AC voltage is applied to a primary winding of a transformer, and the AC voltage taken out of a secondary winding of the transformer is smoothed to an output terminal. In a switching power supply that outputs to connected external devices,
When the primary winding of the transformer is applied, an external device connected to an output terminal of a secondary winding of the transformer has communication means for transmitting and receiving a communication signal using a power line of an AC power supply as a communication line. Switching power supply characterized. The switching power supply according to claim 1,
The switching power supply, wherein the communication means has a coupling element connected between a primary winding of the transformer and a switching element. The switching power supply according to claim 1 or 2,
The communication means is characterized in that it has means for transmitting compressed communication with a value slightly larger than the reciprocal of the duty cycle based on the duty cycle of the switching power supply, while expanding and taking in compressed communication data. Switching power supply. The switching power supply according to any one of claims 1 to 3,
The communication means selectively performs on / off of a supply power to the external device and changes a supply voltage to the external device based on an external communication signal obtained through the power line. A switching power supply characterized by having a control circuit that performs the switching. The switching power supply according to any one of claims 1 to 4,
A switching power supply characterized in that the communication means includes a high-frequency transmission / reception circuit, an encryption / decryption circuit, a scramble circuit, a modulation / demodulation circuit, and a signal processing circuit.

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