JP2006033146A - Communications system and communications apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system wherein systems transmitting/receiving optical signals among a plurality of power converters can be operated under sure synchronization, by eliminating human-induced mistakes for setting a regenerative repeater. <P>SOLUTION: A master communication apparatus 101 includes a communication controller 107 and a two-way module 107 for transmitting an initial signal and receives the initial signal transmitted via a loopback path 135. The master communication apparatus 101 transmits a control signal to slave communication apparatuses 111a to 111c, after reception of the initial signal. Each slave communication apparatus includes a communication signal discriminating section 119 for discriminating whether or not a received signal is the initial signal, and a counter 123 for counting the number of discrimination times of the initial signal. Further, each slave communication apparatus includes a SW control circuit 232 for switching a first switch 17 to form a communication return path W2, when the received signal is discriminated to be the initial signal and uses switches 113a, 113b and the regenerative repeaters 115a, 115b to carry out regenerating processing for the signal, when the count of the counter 123 is smaller than a threshold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication system and a communication apparatus.

  Currently, there is a power control system that controls power supplied to one load by cooperating a plurality of power conversion devices. As a conventional example of such a power control system, for example, there is an invention described in Patent Document 1. In the invention of Patent Document 1, as shown in FIG. 10, n power converters 14 a to 14 n cooperate to supply power to a load 15 such as one motor. The power converters 14 a to 14 n are controlled by one master control device 10.

In the invention of Patent Document 1, the master controller 10 and the power converters 14a to 14n are connected only by the transmission signal line 13, and a carrier signal (a signal serving as a reference for changing a transmitted signal) is transmitted. Wiring is unnecessary. For this reason, in the illustrated master control device 10, the synchronization signal generator 11 gives a synchronization signal to the master communication device 12 in order to synchronize signals. The master communication device 12 transmits a control signal in units of communication frames based on the synchronization signal.
According to such an invention of Patent Document 1, synchronization between the power conversion devices 14a to 14n can be stably and easily taken.

  11 shows a configuration in which power converters 14a to 14n are connected using an optical fiber 17 in place of the transmission signal line 13 in the configuration shown in FIG. Optical communication using the optical fiber 17 is more advantageous for insulation between power conversion devices and noise countermeasures than the transmission signal line 13. The configuration shown in FIG. 11 includes a bidirectional module (not shown) in the master controller 10 and the power converters 14a to 14n for optical communication, and the bidirectional modules are connected by two optical fibers. The electrical signal generated inside the apparatus is converted into an optical signal and transmitted, and the received optical signal is converted into an electrical signal and input into the apparatus.

  In the configuration shown in FIG. 11, termination is set in the power conversion device n in the final stage (the signal is transmitted most recently from the master control device) among the power conversion devices 14. The optical cable is folded back by the termination setting, which is equivalent to a state where the master control device 10 and the power conversion devices 14a to 14n are connected in a loop. As for the arrangement of each power converter, in general, the master controller 10 and the power converter 14a are long distances, and the distance between the power converters is often shorter than the distance from the master controller 10.

FIG. 12 is a diagram showing the configuration of power converters 14a to 14n in more detail. The power converters 14a to 14n have the same configuration, and only the power converter 14a is illustrated. As illustrated, the power converter 14 a includes a slave communication device 30, and the slave communication device 30 includes a slave communication device 31.
In communication using an optical fiber cable and a bidirectional module, it is known that signal deterioration such as a decrease in the amount of light of an optical signal and waveform distortion increase with the communication distance. The slave communication device 31 includes a regenerative repeater 18 for regenerating and transmitting a high-quality signal from the deteriorated optical signal. The regenerative repeater 18 is configured by a digital PLL (Phase Locked Loop) or the like.
JP-A-8-317632

  However, in the configuration shown in FIG. 12, when the regeneration process of the synchronization signal is performed by all of the power converters 14 a to 14 n, the synchronization signal cannot be used for synchronization because of the process of adding the delay of the synchronization signal. In order to solve this problem, there is a case where a signal is regenerated by the regenerative repeater 18 only by the power converter 14a from which the received signal is transmitted from a relatively long distance, and a signal transmitted / received at a short distance is not regenerated. .

Whether or not to regenerate a signal in the power converter is manually set by an operator using a manual setting unit 32 provided in each power converter. For this reason, a human error may occur in the setting, and the entire power converter may not be synchronized due to the error.
An object of the present invention is to provide a communication system and a communication device that eliminates an artificial mistake in setting a regenerative repeater and that enables a system that transmits and receives an optical signal between a plurality of power converters to operate in a synchronized manner. To do.

  In order to solve the above problems, a communication system according to claim 1 of the present invention includes a first communication device and a plurality of second communication devices communicating with the first communication device. Each of the communication forward path for receiving the signal transmitted by the other second communication device in the previous stage and transmitting it to the other second communication device in the next stage, and the other second communication device in the next stage A communication return path capable of receiving the transmitted signal and transmitting to the other second communication device in the previous stage, and of the second communication device in the first stage among the plurality of second communication apparatuses. The signal input terminal of the communication forward path is connected to the signal output terminal of the first communication device, and the output terminal of the communication return path of the second communication device at the first stage is connected to the signal input terminal of the first communication device. Connected, the signal output terminal of the communication forward path of the second communication device at the final stage is folded back, and the final stage A communication system connected to a signal input terminal of the communication return path of the second communication device, wherein the first communication device is transmitted prior to a control signal for controlling the second communication device. Initial signal transmitting means for transmitting a signal; initial signal receiving means for receiving an initial signal transmitted by the initial signal transmitting means and returned via the communication return path of the second device; and the initial signal Control signal transmitting means for transmitting a control signal to the second communication apparatus after an initial signal is received by the receiving means, wherein the second communication apparatus is a type of received signal received via the communication return path If the signal discrimination means and the signal discrimination means determine that the received signal is an initial signal, it is possible to transmit a signal through the communication return path. A communication return path switching means for switching to a state, an initial signal counting means for counting the number of times that the signal determining means determines that the received signal is an initial signal, and a value counted by the initial signal counting means satisfying a predetermined value. If not, signal reproduction means for reproducing the received signal to remove attenuation and distortion is provided.

  According to the first aspect of the invention, the first communication device can transmit an initial signal to the second communication device prior to the control signal. The transmitted initial signal reaches the second communication device at the final stage via the communication forward path, and receives the type discrimination in the second communication device. When it is determined that the signal is an initial signal, the communication return path is switched to a signal transmittable state, and the initial signal is transmitted to the second communication device or the first communication device in the preceding stage. When the communication return path is ready for signal transmission in all of the plurality of second communication apparatuses, the initial signal transmitted by the first communication apparatus is returned to the first communication apparatus via the communication return path.

With the above configuration, the first communication device can detect that the communication return path has been switched to a signal transmission enabled state in all the second communication devices, and can determine the control signal transmission start timing.
In the second communication device, the number of times that the signal is determined to be an initial signal is counted, and only when the counted value is less than a predetermined value, the signal reproducing means reproduces a signal received thereafter. Remove attenuation and distortion.

  With the above configuration, a predetermined count value is set in accordance with the initial signal reception order of the second communication device to be subjected to signal regeneration processing, thereby automatically causing only any second communication device to execute signal regeneration processing. Can be set automatically. For this reason, it is possible to provide a communication system that eliminates an artificial mistake in setting the regenerative repeater and can operate in a reliable manner.

According to a second aspect of the present invention, there is provided the communication system according to the first aspect, wherein the signal regeneration means includes a regeneration circuit forming means for forming a regeneration circuit through which a received signal passes through a regeneration repeater, and the regeneration. A non-regenerative circuit forming means for forming a non-regenerative circuit that bypasses the repeater; and a circuit switching means for switching between the regenerative circuit and the non-regenerative circuit, the circuit switching means being counted by the initial signal counting means. When the measured value reaches a predetermined value, the circuit is switched to a non-regenerative circuit, and the regenerative repeater is bypassed for the received signal.
According to such a second aspect of the invention, it is possible to switch between the signal reproduction circuit and the non-reproduction signal circuit according to the count value by the initial signal counting means, and to switch the presence or absence of the signal reproduction processing.

According to a third aspect of the present invention, there is provided the communication system according to the second aspect, wherein the circuit switching means has a value counted by the initial signal counting means reaching a predetermined value, and the first communication device. When the signal discriminating means determines that the signal transmitted from is an initial end signal indicating that the communication return path has been switched to a signal transmittable state in all of the second communication devices, the circuit is turned off. Switching to the regenerative circuit, the regenerative repeater is bypassed for the received signal.
According to such a third aspect of the present invention, it is possible to switch between the reproduction circuit and the non-reproduction circuit according to the count value of the initial signal and the presence / absence of reception of the initial end signal, and to switch the presence / absence of the signal reproduction processing.

According to a fourth aspect of the present invention, there is provided the communication system according to the third aspect, wherein the first communication device receives the initial signal that has passed through the communication return route, so that all the second communication devices have the communication return route. Detecting the completion of communication return path formation, and transmitting the initial end signal, wherein the initial end signal is transmitted.
According to such a fourth aspect of the invention, since the initial end signal can be transmitted after the formation of the communication return path is completed with certainty, the reliability of automatic signal reproduction setting can be improved.

According to a fifth aspect of the present invention, in the communication system according to any one of the first to fourth aspects, the plurality of second communication devices include power conversion means for converting power supplied to a load. The power conversion system is configured to control the load in cooperation with each other.
According to such an invention, the communication system according to any one of claims 1 to 4 can be applied to a power conversion system.

  A communication device according to claim 6 of the present invention is a plurality of communication devices connected together with another communication device, and receives a signal from another communication device in the previous stage among the plurality of communication devices connected, A communication forward path for transmitting a signal to another communication apparatus in the subsequent stage, and a signal return path for receiving a signal transmitted to the other communication apparatus in the subsequent stage via the communication forward path and transmitting to the other communication apparatus in the previous stage And a signal discriminating unit for discriminating the type of the received signal received via the communication return path, and the signal discriminating unit are signals transmitted prior to the control signal for synchronizing the communication. When it is determined that the signal is an initial signal, a communication return path switching unit that switches the communication return path to a state in which signal transmission is possible, and an initial signal count that counts the number of times the signal determination unit determines that the received signal is an initial signal. And stage, when the value counted by the initial signal counting means is less than a predetermined value, characterized in that it comprises a signal reproducing means for removing decay and distortion by reproducing the received signal.

  According to such an invention, the initial signal can be received via the signal return path and transmitted to the preceding communication device. For this reason, notifying the outside that the communication return path has been switched to a state in which the signal can be transmitted in all the communication devices because the first-stage communication device among the plurality of communication devices has transmitted the initial signal. Can do. For this reason, it is possible to detect the timing at which the synchronization signal is transmitted to the connected communication device to start the operation.

  In addition, by counting the number of times that the signal is determined to be an initial signal, only when the counted value is less than a predetermined value, the signal reproducing means reproduces a signal received thereafter to remove attenuation and distortion. In addition, a predetermined count value is set in accordance with the initial signal reception order of the communication device that is to perform the signal reproduction process, and the setting for selectively executing the signal reproduction process can be automatically performed. For this reason, it is possible to provide a communication device that can eliminate the human error in setting the regenerative repeater and can operate in a synchronized manner.

According to a seventh aspect of the present invention, there is provided the communication device according to the sixth aspect, further comprising power conversion means for converting the power supplied to the load to constitute a power conversion device.
According to such an invention, the communication apparatus of the present invention can be applied to a power converter.

Embodiments 1 and 2 of a communication system according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining a communication system according to a first embodiment of the present invention. The communication system of Embodiment 1 is applied to a power conversion system in which a plurality of power conversion devices cooperate to convert power supplied to a load. For this reason, the communication apparatus which comprises a communication system comprises the power converter device provided with the power converter 100 which converts the electric power supplied to the load 150. FIG. The load 150 indicates, for example, a motor for driving the device.

The power conversion system includes a master control device 1 and a plurality (three) of power conversion devices 2a to 2c. The master control device 1 includes a master communication device 101. The power conversion device 2a includes a slave communication device 109a, and the slave communication device 109a includes a slave communication device 111a. Similarly, the power conversion device 2b includes a slave communication device 111b, and the power conversion device 2c includes a slave communication device 111c.
In the first embodiment, the master communication device 101 is a first communication device, and each of the slave communication devices 111a to 111c is a second communication device. The master communication device 101, the slave communication device 111a, and the slave communication devices are connected by an optical fiber 104 and transmit / receive optical signals to / from each other.

Each of the slave communication devices 111a to 111c receives a signal transmitted by the other slave communication device in the previous stage and transmits it to the slave communication device in the next stage, and is transmitted by the slave communication device in the next stage. And a communication return path W2 capable of receiving the transmitted signal and transmitting it to the preceding slave communication device. Also, among the slave communication devices 111a to 111c, the signal input terminal of the communication forward path W2 of the first-stage slave communication apparatus 111a is connected to the signal output terminal of the master communication apparatus 101, and the communication return path W2 of the slave communication apparatus 111a. The output terminal is connected to the signal input terminal of the master communication device 101.
Therefore, for the slave communication device 111a, the communication forward path W1 receives the signal transmitted by the master communication device 101 and transmits it to the slave communication device 111b at the next stage. The signal return path W2 is configured to receive a signal transmitted from the slave communication device 111b at the next stage and transmit the signal to the master communication device 1110.

  In this specification, in the communication forward path W1, a slave communication device that receives a signal first is referred to as a previous slave communication device with respect to a subsequent slave communication device, and a slave communication device that receives a signal later is received first. It is assumed that the slave communication device in the subsequent stage is the slave communication device that performs this. The slave communication device 111a that directly transmits and receives signals to and from the master communication device 101 is referred to as a first-stage device, and the slave communication device 111c that receives the signal transmitted by the master communication device 101 lastly is the last-stage slave communication. It is called a device.

In the final stage slave communication device 111c, a return path 135 is configured. According to the return path 135, the signal transmitted from the slave communication device 111c is received again by the slave communication device 111c.
The master communication device 101 transmits a control signal to the slave communication devices 111a to 111c. The control signal in the first embodiment refers to a synchronization signal for synchronizing each device when the slave communication devices 111a to 111c perform a normal operation (power conversion). The master communication device 101 transmits an initial signal prior to the control signal in order to prepare the slave communication devices 111a to 111c to receive control signals.

  For this reason, the master communication apparatus 101 includes a bidirectional module 103. The bidirectional module 103 is configured to transmit and receive a plurality of types of signals including initial signals to and from the slave communication devices 111a to 111c. In the first embodiment, an initial signal transmitting means for transmitting an initial signal, an initial signal receiving means for receiving the initial signal transmitted to the slave communication devices 111a to 111c and returned by the return path 135, and after the initial signal is received. It functions as a control signal transmitting means for transmitting a control signal to the slave communication devices 111a to 111c.

In addition, the master communication device 101 performs communication of the master communication device 101 according to the type of signal detected by the communication signal detection unit 105 that detects whether the received signal is an initial signal, and the signal detected by the communication signal detection unit 105. A communication controller 107 for controlling is provided.
Note that both the control signal and the initial signal are transmitted and received as optical signals. Therefore, the bidirectional module 103 includes a transmission E / O (Electrical / Optical Converter) 130 that converts an electrical signal into an optical signal, and a reception O / E (Optical / Electrical Converter) 131 that converts an optical signal into an electrical signal. ing. The electrical signal generated inside the master communication device 101 is converted into an optical signal by the transmission E / O 130 and transmitted. The optical signals transmitted from the slave communication devices 111a to 111c are converted into electrical signals by the reception O / E 131.

On the other hand, when the slave communication devices 111a to 111c determine that the type of signal received from the slave communication device at the subsequent stage and the communication signal determination unit 119 determine that the received signal is an initial signal, A return path switching unit that switches the communication return path W2 to a state in which a signal received from the slave communication apparatus can be transmitted to the preceding slave communication apparatus.
Further, for the first-stage slave communication device 111a, the communication return path W2 is switched to a state in which a signal received from the subsequent-stage slave communication device can be transmitted to the master communication device 101.

The return path switching unit according to the first embodiment includes the SW control circuit 121 and the first switch 117. That is, when the communication signal determining unit 119 determines that the received signal is an initial signal, the SW control circuit 121 switches (CLOSE) the first switch 117.
The CLOSE of the first switch 117 switches the signal return path W2 so that the slave communication apparatus 111c receives a signal via the return path 135 and transmits it to the slave communication apparatus 111b.

  Further, when the first switch 117 is closed in the slave communication device 111b, the signal return path W2 of the slave communication device 111b is switched to transmit the signal received from the slave communication device 111c to the slave communication device 111a. Further, when the first switch 117 is closed in the slave communication device 111a, the signal return path W2 of the slave communication device 111a is switched to transmit the signal received from the slave communication device 111b to the master communication device 110.

Each of the slave communication devices 111a to 111c includes a counter 123 that is an initial signal counting unit that counts the number of times that the communication signal determining unit 119 determines that the received signal is an initial signal. Then, a signal reproducing means for reproducing a signal received thereafter and removing attenuation and distortion during a period when the value counted by the counter 123 is less than a predetermined value is provided.
The signal regeneration means of the first embodiment includes second switches 113a and 113b and a regeneration repeater 115b provided on the communication return path W2. A regenerative repeater is a device that regenerates from a signal that has been attenuated or distorted during propagation to compensate for signal degradation. The signal regeneration means of the first embodiment forms either a regeneration circuit Ab through which a signal passes through the regeneration repeater 115b or a non-regeneration circuit Bb that bypasses the regeneration repeater 115b.

According to the signal regeneration means described above, by switching the switching of the second switch 113a and the second switch 113b, the signal can be passed through the regeneration circuit Ab in the return path W2 and regenerated by the regeneration repeater 115b. Further, the signal can be transmitted to the non-regenerative circuit Bb and transmitted to the preceding apparatus without being processed by the regenerative repeater 115b.
In the first embodiment, signal reproduction means is also provided in the communication forward path W1. The signal regeneration means provided in the communication forward path W1 includes second switches 113a and 113b and a regeneration repeater 115a. By switching the second switch 113a and the second switch 113b, the regeneration circuit Aa and the non-regeneration circuit One of Ba is formed.

The SW control circuit 121 controls both the second switches 113a and 113b on the communication forward path W1 and the second switches 113a and 113b on the communication backward path W2, and controls the reproduction circuits Aa and Ab and the non-reproduction circuits Ba and Bb. Switching.
Furthermore, the slave communication devices 111a to 111c include a communication controller 125 that controls the above configuration in an integrated manner.

  The configuration described above operates as follows. The operation described below is performed after the power conversion system is reset and released. After the reset is released, in the slave communication devices 111a to 111c, the first switch 117 is in a state (OPEN) that does not form the communication return path W2, and the second switches 113a and 113b are switched to form the reproduction circuits Aa and Ab. ing.

After canceling the reset, the communication controller 107 of the master communication device 101 outputs an electrical initial signal to the bidirectional module 103. The initial signal is converted into an optical signal by the transmission E / O 130 and transmitted to the bidirectional module 102 of the slave communication device 111a. Then, the bidirectional module 131 receives the received O / E 131 and converts it into an electrical signal.
A reproduction circuit Aa is formed immediately after the bidirectional module 102. The initial signal is transmitted to the slave communication device 111b. The initial signal is branched and input to the communication controller 125.

  The transmitted signal is received by the slave communication device 111b. The slave communication device 111b operates in the same manner as the slave communication device 111a described above and transmits the received initial signal to the slave communication device 111c. The slave communication device 111c is terminated as described above. For this reason, the initial signal transmitted to the slave communication device 111c is folded and received by the reception O / E 131 in the bidirectional module 102 inside the slave communication device 111c. The received initial signal is branched and input to the communication signal determination unit 119.

A communication frame 200 of signals transmitted and received in the power conversion system of the first embodiment is configured as shown in FIG. The communication frame 200 includes a pattern (hereinafter referred to as a type pattern) 201 indicating the type of communication using signals. The type pattern 201 indicates whether the signal type is “initial signal” or “control signal”.
The initial signal is a signal used for initial communication (communication for setting whether or not to perform processing by the regenerative repeater in each slave communication device prior to starting communication) between the power converters. It is not a communication that is performed for the purpose of synchronizing. Communication performed using a control signal that is a synchronization signal is referred to as normal communication, and normal communication is performed after completion of initial communication.

  The discrimination result of the communication signal discriminating unit 119 is transmitted to the outside as a discrimination signal S indicating the type of signal discriminated by the type pattern 201 described above. The determination signal S is input to both the communication controller 125 and the SW control circuit 121. The SW control circuit 121 counts the initial signal by the counter 123 only when it is determined that the signal is an initial signal. When the counter 123 counts one initial signal, the SW control circuit 121 closes the first switch 117.

  By CLOSE of the first switch 117, the signal return path W2 of the slave communication device 111c is switched to a state in which subsequent signals can be transmitted to the slave communication device 111b. The counted initial signal is not output to the slave communication device 111b because the first switch 117 is not switched at the time of counting (OPEN). The counted initial signal disappears without being received by the master communication apparatus 101.

  When the transmitted initial signal is not received, the master communication device 101 transmits the initial signal again to the slave communication device 111a. The initial signal reaches the slave communication device 111c through the same route as described above, is turned back, and is input to the slave communication device 111c again. The communication signal determination unit 119 of the slave communication device 111c inputs a determination signal indicating that the signal is an initial signal to the SW control circuit 121, and increases the counter 123 by one. As a result, the count value of the counter 123 of the slave communication device 111c is 2.

  At this time, since the first switch 117 of the slave communication device 111c is CLOSEd, the initial signal is further reproduced through the reproduction circuit Ab and transmitted to the slave communication device 111b. In the slave communication device 111b, similarly to the slave communication device 111c, the communication signal determination unit 119 determines a signal. Then, a determination signal S indicating that the signal is an initial signal is output to the SW control circuit 121. The SW control circuit 121 closes the first switch 117. By this CLOSE, the return path W2 of the slave communication device 111b is switched to a state in which a signal can be transmitted to the slave communication device 111a.

In addition, the SW control circuit 121 increases the counter 123 by one when the determination signal S is input. As a result, the count value of the counter 123 of the slave communication device 111b becomes 1.
The initial signal transmitted for the second time disappears inside the slave communication device 111b. Therefore, the master communication device 101 does not receive the initial device transmitted for the second time. For example, when the initial signal is not received for a predetermined time from the transmission of the initial signal, the master communication device 101 transmits the initial signal to the slave communication device 111a again.

  The transmitted initial signal reaches the slave communication device 111c and is returned. In the slave communication device 111c, the count value of the counter 123 is increased to 3. When the count value of the counter 123 reaches 3, in the first embodiment, the SW control circuit 121 switches the second switches 113a and 113b to form the non-reproducing circuits Ba and Bb. As a result, the slave communication device 111c is set to a state in which signal regeneration by the regeneration repeater 115b is not performed thereafter. Note that the initial signal is transmitted to the slave communication device 111b through the reproduction circuit Ab before switching.

  The slave communication device 111b receives the initial signal. The communication signal determination unit 119 outputs a determination signal S, and the SW control circuit 121 increases the counter by one and increases the count value to two. The initial signal is input to the slave communication device 111a via the reproduction circuit Ab, and disappears at the first switch 117 of the slave communication device 111a. At this time, in the slave communication device 111a, the first switch 117 is closed, and the communication return path W2 is switched to a state in which signal transmission is possible.

Furthermore, since the initial signal is not received, the master communication device 101 transmits the initial signal again to the slave communication device 111a. At this time, since the communication return path W2 of the slave communication devices 111b and 111c is switched to a state in which signal transmission is possible, the initial signal reaches the slave communication device 111a and is transmitted to the master communication device 101. The master communication device 101 receives the initial signal and detects that the communication return path W2 has been switched to a signal transmittable state in all of the slave communication devices 111a to 111c.
At this time, the count value of the counter 123 of the slave communication device 2b also reaches 3. For this reason, the SW control circuit 121 of the slave communication device 2b switches the second switches 113a and 113b to form non-reproducing circuits Ba and Bb.

  FIG. 3 is a table collectively showing the operations of the communication system according to the first embodiment described above. According to the table shown in FIG. 3, in the slave communication devices 111a to 111c, the first switch 117 is closed when the counter 123 counts, and the communication return path W2 to the previous device is in a state where signal transmission is possible. I understand that. It can also be seen that when the count value reaches 3, the second switches 113a and 113b form non-reproducing circuits Ba and Bb.

  Master communication apparatus 101 receives the initial signal by the fourth initial signal transmission. By receiving the initial signal, it is detected that all of the slave communication devices 111a to 111c are ready for signal transmission in the communication return path W2, and it is determined that preparation for communication of the slave communication devices 111a to 111c is completed. Then, in order to perform normal communication from the next time, transmission of a control signal is started.

  However, the present invention is not limited to the first embodiment described above. In other words, the slave communication devices 111a to 111c are not limited to those that switch the communication return path to a signal transmittable state when the count value of the counter 123 becomes 1. The count value (threshold value) forming the communication return path can be arbitrarily set according to the use of the system and the user's desire.

  Further, the count value (threshold value) forming the non-reproducing circuit in each of the slave communication devices 111a to 111c is not limited to 3. That is, the first embodiment is made for the purpose of performing the signal reproduction process only in the slave communication device 111a in which signal degradation is a concern. Accordingly, the threshold value for forming the non-regenerative circuit may be any numerical value as long as this purpose can be realized.

  The threshold value 3 of the first embodiment can achieve the above-described object in the configuration of the first embodiment, and defines a minimum value. That is, the first embodiment sets the threshold value to n in a system to which n slave communication devices are connected. The setting of the first embodiment can detect that the communication return path is completed when the master communication apparatus 101 transmits the initial signal n + 1 times. At this time, the counter value of the counter of the slave communication device (slave communication device 111a in the first embodiment) that directly transmits and receives signals to and from the master communication device 101 is focused on two points. It is.

Next, the operation described above will be described with reference to a flowchart. FIG. 4 shows the initial signal count processing in the SW control circuit 121. First, the SW control circuit 121 determines whether communication has been performed. When communication is performed, it is further determined whether or not the signal type is an initial signal and the communication is initial communication (S401).
If the result of determination in step S401 is that the communication is initial communication (S401: Yes), the counter 123 is incremented by one (S402). Also, as a result of the determination in step S401, if at least one of the conditions for communication or initial communication is not satisfied (S401: No), the process is terminated without increasing the counter 123.

  FIG. 5 is a flowchart showing the control performed by the SW control circuit 121 to close the first switch 117. The SW control circuit 121 determines whether or not the count value of the counter 123 is 0 or more (S501). If the count value is 0 or more (S501: Yes), the first switch 117 is closed, and the communication return path W2 is switched to a state in which a signal can be transmitted to the preceding slave communication device (S502).

  FIG. 6 is a flowchart for explaining processing in which the SW control circuit 121 switches the second switch 113a, 113b to switch between the reproduction circuit and the non-reproduction circuit. The SW control circuit 121 determines whether or not the communication signal determination unit 119 has detected initial communication and the count value of the counter 123 has reached the threshold value K (S601). As a result of the determination, if the count value is less than the threshold value K (S601: No), the second switches 113a and 113b are maintained in the state at the time of the previous initial signal count (S602).

In the first embodiment, the second switches 113a and 113b are set to form a reproduction circuit at the time of reset. Therefore, the reproduction circuits Aa and Ab are formed in each slave communication device until the count value reaches the threshold value K.
In step S601, when the count value reaches the threshold value K (S601: Yes), the SW control circuit 121 switches the second switches 113a and 113b to form the non-reproducing circuits Ba and Bb (S603). . In step S601, the non-reproducing circuits Ba and Bb are formed whatever the count value is equal to or greater than the threshold value K. Therefore, in the slave communication device once formed with the non-reproduction circuits Ba and Bb, the signal reproduction process is not performed until the reset is performed.

According to the first embodiment described above, signal regeneration processing by the regeneration repeaters 115a and 115b is performed only with the first-stage slave communication device 111a among the slave communication devices 111a to 111c communicating with the master communication device 101. be able to. Generally, the communication distance between the master communication device and the slave communication device is longer than that between the slave communication devices. For this reason, signal degradation in the system is most concerned with communication between the master communication device 101 and the slave communication device 111a.
From this point, the first embodiment can realize a communication system that can prevent synchronization loss due to signal delay while correcting signal deterioration.

  Furthermore, the present invention is not limited to the configuration described above. For example, in the first embodiment, the master communication device 101 and the slave communication device 111a, or the slave communication devices 111a to 111c are connected by the optical fiber 104. Such a configuration is shown because communication using an optical fiber is often provided with a regenerative repeater to prevent signal deterioration. Therefore, the first embodiment of the present invention is not limited to the configuration in which communication is performed by the optical fiber 104, and can also be applied to a communication system in which a master communication device or a slave communication device communicates through an electric signal transmission line.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described. In the description of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and a part of the description is omitted. Moreover, Embodiment 2 shall apply the communication system of this invention to a power conversion system similarly to Embodiment 1. FIG.

FIG. 7 is a diagram illustrating a communication frame 700 according to the second embodiment. The communication frame 700 includes a type pattern 701 indicating the type of signal. The type pattern 701 of the communication frame 700 is a pattern that can determine the initial end signal in addition to the initial signal and the control signal (normal communication) described in the first embodiment.
The initial end signal is a signal indicating that the communication return path W2 can be transmitted to all the slave communication apparatuses 111a to 111c with respect to the slave communication apparatus 101.

  After the value counted by the counter 123 reaches a predetermined value, the SW control circuit 121 according to the second embodiment further transmits a signal transmitted from the master communication device 101 to the communication return path in all of the slave communication devices 111a to 111c. When the communication signal discriminating unit 119 discriminates that W2 is an initial end signal indicating that the signal can be transmitted, the second switch 113a, 113b switches the circuit to the non-reproducing circuit Ba, Bb and is received. The regenerative repeaters 115a and 115b are bypassed by the received signal.

  That is, in the power conversion system of the second embodiment, the initial signal is counted by the counter 123 in the slave communication devices 111a to 111c, as in the first embodiment. Then, by counting, the communication return path W2 is switched to a state in which signal transmission is possible in each slave communication device. The master communication device 101 detects that the communication return path W2 can be transmitted by all of the slave communication devices 111a to 111c by receiving the transmitted initial signal. Then, an initial end signal is transmitted to the slave communication device 111a.

  The initial end signal is transmitted to the slave communication devices 111a to 111c, and is returned on the return path 135 in the slave communication device 111c. The communication signal determination unit 119 of the slave communication device 111c determines that the signal is an initial end signal. Then, a determination signal S indicating that the signal is an initial end signal is input to the SW control circuit 121. The SW control circuit 121 switches the second switches 113a and 113b only when the count value of the counter 123 has reached the threshold value, thereby forming the non-reproducing circuits Ba and Bb.

  FIG. 8 is a flowchart showing the operation of the SW control circuit 121 of the second embodiment. The SW control circuit 121 according to the second embodiment further determines whether or not the count value of the counter 123 has reached the threshold value K when the communication signal determination unit 119 determines that the signal type is the initial end signal. (S801). As a result of the determination, if at least one of the determination of the initial end signal and the count value has reached the threshold value K is not satisfied (S801: No), the second switches 113a and 113b are turned on the previous time. The initial signal count state is maintained (S802).

In the first embodiment, the second switches 113a and 113b are set to form a reproduction circuit at the time of reset. Therefore, while the initial end signal is received via the communication return path and the count value is less than the threshold value K, the reproduction circuits Aa and Ab are formed in each slave communication device.
In step S801, when the initial end signal is determined and the count value reaches the threshold value K (S801: Yes), the SW control circuit 121 switches the second switches 113a and 113b to perform non-reproduction. Circuits Ba and Bb are formed (S803).

  FIG. 9 is a diagram collectively showing the operation of the communication system according to the second embodiment described above. According to the table shown in FIG. 9, in the slave communication apparatuses 111a to 111c, as in the first embodiment, the counter 123 counts and the first switch 117 is CLOSEd. By CLOSE, the communication return path W2 is switched to a state in which a signal can be transmitted to the preceding apparatus. At this time, in the second embodiment, the second switches 113a and 113b maintain the reproduction circuits Aa and Ab regardless of the count value of the counter 123.

  Master communication apparatus 101 receives the initial signal by the fourth initial signal transmission. In the second embodiment, after receiving the initial signal, the master communication device 101 further transmits an initial end signal to the slave communication device 111a. The initial end signal reaches the slave communication device 111c via the communication forward path W1, is returned, and is transmitted again to the slave communication devices 111a to 111c.

  At this time, if the communication signal determination unit 119 determines that the type of the initial end signal is the initial end signal, and the count value of the counter 123 has reached 3, the slave communication devices 111a to 111c receive the second switch. 113a and 113b form non-reproducing circuits Ba and Bb. As a result, the slave communication device 111b and the slave communication device 111c can transmit and receive signals without using the regenerative repeater. The signal can be reproduced only in the slave communication device 111a to correct the signal deterioration.

After transmitting the initial end signal, the master communication device 101 determines that the slave communication devices 111a to 111c are ready for communication. Then, in order to perform normal communication from the next time, transmission of a control signal is started.
According to the second embodiment described above, the master communication apparatus 101 can detect the completion of the communication return path W2 by receiving the initial signal. Further, after this, an initial end signal can be transmitted to switch between the reproduction circuit and the non-reproduction circuit. For this reason, an initial end signal can be transmitted to each slave communication device via the communication return path, and signal reproduction of each slave communication device can be reliably set.

It is a figure for demonstrating the communication system of Embodiment 1 of this invention. It is a figure which shows the communication frame of the communication system of Embodiment 1 of this invention. It is a table | surface which shows collectively the operation | movement of the communication system of Embodiment 1 of this invention. 6 is a flowchart for explaining a process of counting an initial signal according to the first embodiment. It is the figure which showed the control which forms the communication return path of Embodiment 1 of this invention with the flowchart. 4 is a flowchart for explaining a process of switching between the reproduction circuit and the non-reproduction circuit according to the first embodiment of the present invention. It is a figure which shows the communication frame of the communication system of Embodiment 2 of this invention. It is a flowchart for demonstrating the process which switches the reproduction | regeneration circuit and non-reproduction | regeneration circuit of Embodiment 2 of this invention. It is a table | surface which shows collectively the operation | movement of the communication system of Embodiment 2 of this invention. It is a figure which shows the structure equivalent to the prior art example of this invention. It is a figure which shows the structure which replaced the signal wire | line with the optical fiber in the structure shown in FIG. It is the figure which showed the structure of the power converter shown in FIG. 11 in detail.

Explanation of symbols

2a to 2c Power conversion device 100 Power conversion unit 101 Master communication device 102, 103 Bidirectional module 104 Optical fiber 105 Communication signal detection unit 107 Communication controller 109a to 109c Slave communication device 111a to 111c Slave communication device 113a, 113b Second switch 115a 115b Regenerative repeater 117 First switch 119 Communication signal determination unit 121 SW control circuit 123 Counter 125 Communication controller 131 Bidirectional module 135 Return path 150 Load 200,700 Communication frame 201,701 Type pattern

Claims (7)

A first communication device and a plurality of second communication devices communicating with the first communication device, each of the second communication devices receiving a signal transmitted by the other second communication device in the previous stage; A communication forward path for transmission to the second communication device at the next stage and a signal transmitted by the second communication device at the next stage are received and transmitted to the other second communication device at the previous stage. Possible communication return path,
Of the plurality of second communication devices, the signal input terminal of the communication forward path of the second communication device of the first stage is connected to the signal output terminal of the first communication device,
An output end of the communication return path of the second communication device of the first stage is connected to a signal input end of the first communication device;
A communication system in which a signal output end of the communication forward path of the second communication device at the final stage is folded and connected to a signal input end of the communication return path of the second communication apparatus at the final stage,
The first communication device is
Initial signal transmission means for transmitting an initial signal transmitted prior to a control signal for controlling the second communication device;
Initial signal receiving means for receiving an initial signal transmitted by the initial signal transmitting means and returned via the communication return path of the second device;
Control signal transmitting means for transmitting a control signal to the second communication device after an initial signal is received by the initial signal receiving means,
The second communication device is
Signal discriminating means for discriminating the type of received signal received via the communication return path;
A communication return path switching means for switching the communication return path to a state in which a signal can be transmitted;
Initial signal counting means for counting the number of times the signal determining means determines that the received signal is an initial signal;
If the value counted by the initial signal counting means is less than a predetermined value, a signal reproducing means for reproducing the received signal to remove attenuation and distortion;
A communication system comprising: The signal reproducing means includes
Regenerative circuit forming means for forming a regenerative circuit through which a received signal passes through a regenerative repeater;
Non-regenerative circuit forming means for forming a non-regenerative circuit that bypasses the regenerative repeater;
Circuit switching means for switching between the regeneration circuit and the non-reproduction circuit,
The circuit switching means switches the circuit to a non-regenerative circuit when the value counted by the initial signal counting means reaches a predetermined value, and bypasses the regenerative repeater for a received signal. The communication system according to 1.   In the circuit switching means, the value counted by the initial signal counting means reaches a predetermined value, and the signal transmitted from the first communication device is the signal of the communication return path in all of the second communication devices. The circuit is switched to a non-regenerative circuit when the signal discriminating unit determines that the signal is an initial end signal indicating that the transmission is possible, and the regenerative repeater is bypassed for the received signal. The communication system according to claim 2.   The first communication device detects that the communication return path has been switched to a signal transmittable state in all of the second communication devices by receiving the initial signal via the communication return path, and the initial end The communication system according to claim 3, wherein a signal is transmitted.   5. The plurality of second communication devices include a power conversion unit that converts power supplied to a load, and constitutes a power conversion system that controls the load in cooperation with each other. The communication system according to any one of the above. A plurality of communication devices connected together with other communication devices,
Out of a plurality of connected communication devices, a communication forward path that receives a signal from another communication device in the previous stage and transmits the signal to the other communication device in the subsequent stage;
A signal return path capable of receiving a signal transmitted to the other communication device of the subsequent stage via the communication forward path and capable of being transmitted to the other communication apparatus of the previous stage;
Signal discriminating means for discriminating the type of received signal received via the communication return path;
When the signal determining means determines that the received signal is an initial signal that is transmitted prior to a control signal for synchronizing communication, the communication return path is switched to a state in which signal transmission is possible. Communication return path switching means;
Initial signal counting means for counting the number of times the signal determining means determines that the received signal is an initial signal;
If the value counted by the initial signal counting means is less than a predetermined value, a signal reproducing means for reproducing the received signal to remove attenuation and distortion;
A communication apparatus comprising:   The communication apparatus according to claim 6, further comprising a power conversion unit configured to convert power supplied to the load, and constituting a power conversion apparatus.

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