Communication system

Abstract

To provide a communication system for enabling preferable communication between devices while preventing a connection structure from being large-sized.SOLUTION: An impedance upper is provided between a cable 300 and one unit of a control unit 110 and a drive unit 210. An insulation section is provided between the cable 300 and one section of a communication section 120 and a communication section 220. Between the one communication section and the cable 300 is formed a matching circuit 410 that includes a coil of the impedance upper and a capacitor of the insulation section to reduce reflection of a communication signal at an end of the cable 300. Or, the insulation section is provided between the one communication section and the cable 300. A filter circuit is provided between the insulation section and the one communication section. Between the one communication section and the cable 300 is formed a matching circuit 410 that includes a coil of the insulation section and a capacitor of the filter circuit to reduce reflection of a communication signal at the end of the cable 300.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication system for supplying power and performing communication. [Background technology]

[0002] In a communication system including a control device and a drive device, power is supplied from the control device to the drive device, and communication is performed between the control device and the drive device. In this configuration, the control device and the drive device are connected by various cables, and therefore the connection structure between the control device and the drive device tends to be large. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-150621 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, Patent Document 1 discloses a technology related to power line communication. Signal reflection due to impedance mismatch may occur between the terminal device and the power line in Patent Document 1. In this case, good communication over the power line cannot be achieved. Therefore, it is preferable to provide a filter that maintains impedance matching between the terminal device and the cable. However, adding such a filter to the control device in Patent Document 1 increases the size of the connection structure between the terminal device and the power line. Therefore, it is necessary to miniaturize the connection structure between the devices.

[0005] An object of the present invention is to provide a communication system that is capable of performing good communication between devices while preventing the connection structure from becoming large. [Means for solving the problem]

[0006] A communication system according to one aspect of the present invention is a communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance and a drive unit to which power is supplied through the cable, and includes: a first communication unit and a second communication unit that input or output communication signals indicating communication information to each other through the cable; a first impedance increaser that is provided between one of the control unit and the drive unit and the cable, increasing the impedance between the one unit and the cable and including a first coil; and a first insulating unit that is provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from the power supplied by the control unit and including a first capacitor, and a first matching circuit that includes the first coil and the first capacitor and reduces reflection of the communication signal at the end of the cable is formed between the one communication unit and the cable.

[0007] A communication system according to another aspect of the present invention is a communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance and a drive unit to which power is supplied through the cable, and includes: a first communication unit and a second communication unit that input or output communication signals indicating communication information to each other through the cable; a first insulating unit that is provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from the power supplied by the control unit and including a first coil; and a first filter circuit that is provided between the first insulating unit and the one communication unit and includes a first capacitor, and a first matching circuit that includes the first coil and the first capacitor and reduces reflection of the communication signal at the end of the cable is formed between the one communication unit and the cable. [Effects of the Invention]

[0008] According to the present invention, good communication between devices can be achieved while preventing the connection structure from becoming large. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a configuration of a communication system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of one of the interface circuits. [Figure 3] FIG. 10 is a diagram showing the configuration of the other interface circuit. [Figure 4] FIG. 10 is a diagram showing the configuration of a control device in a first modified example. [Figure 5] FIG. 10 is a diagram illustrating a configuration of a communication system according to another embodiment. [Figure 6] FIG. 10 is a diagram illustrating a configuration of a control device in a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. First embodiment (1) Communication system configuration A communication system according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a control system including a communication system according to a first embodiment of the present invention. As shown in FIG. 1, a control system 500 includes a control device 100, a drive device 200, and a cable 300. The control system 500 is, for example, a servo motor system. In this case, the control device 100 is a servo amplifier, and the drive device 200 is a servo motor. The cable 300 is a cable including two wires, and is used to connect the control device 100 and the drive device 200. The cable 300 has a predetermined characteristic impedance (75 Ω in this example).

[0011] The control device 100 includes a control unit 110, a communication section 120, an impedance upper 130, an insulating section 140, a CMCC (common mode choke coil) 150, and a filter circuit 160. The control unit 110 is connected to one end of one wire of the cable 300 by a wire 101, and is connected to one end of the other wire of the cable 300 by a wire 102. The control unit 110 includes, for example, a CPU (central processing unit) and a power supply.

[0012] The control unit 110 generates, for example, a PWM (pulse width modulation) voltage with an amplitude of several hundred volts and a frequency of several tens of kilohertz, an AC voltage, or a DC voltage of several volts to several tens of volts. The control unit 110 also supplies power for driving a drive unit 210 (described later) of the drive device 200 to the drive unit 210 through wires 101 and 102 and a cable 300. Note that the control system 500 may include a three-phase cable connecting the control unit 110 and the drive unit 210 in addition to the cable 300. In this case, the control unit 110 may supply AC power or a PWM voltage for driving the drive unit 210 to the drive unit 210 through the three-phase cable. When the control system 500 includes a three-phase cable in addition to the cable 300, the control unit 110 may supply power required by the drive unit 210 to the drive unit 210 through the cable 300, in addition to AC power for driving the drive unit 210. For example, the control unit 110 may supply power to an encoder included in the drive unit 210 through the cable 300 .

[0013] The communication unit 120 includes, for example, a PLC (Power Line Communication) modem, and inputs or outputs a communication signal indicating communication information through the wiring 101, 102 and the cable 300. This enables mutual communication with a communication unit 220 (described later) of the drive device 200. The communication information includes information used to control the drive unit 210, such as the operating state of the drive unit 210. In this example, the center frequency of the communication signal is several tens of MHz.

[0014] The impedance upper 130 includes coils 131 and 132. The coil 131 is provided between the node 11 on the wiring 101 and the control unit 110. The coil 132 is provided between the node 12 on the wiring 102 and the control unit 110. The impedance of the portions of the wirings 101 and 102 where the coils 131 and 132 are provided increases. This prevents communication signals output by the communication unit 120 to the wirings 101 and 102 from being input to the control unit 110.

[0015] The insulating unit 140 includes capacitors 141 and 142 and an isolation transformer 143. The isolation transformer 143 includes coils 143a and 143b wound around a core and electrically insulated from each other. One end of the coil 143a of the isolation transformer 143 is connected to a node 11 of the wiring 101 via the capacitor 141. The other end of the coil 143a of the isolation transformer 143 is connected to a node 12 of the wiring 102 via the capacitor 142. Both ends of the coil 143b of the isolation transformer 143 are connected to the communication unit 120. This isolates the communication unit 120 from the power supplied by the control unit 110.

[0016] The CMCC 150 includes two coils 151 and 152 with the same number of turns wound around a core. The coil 151 is provided between the capacitor 141 of the insulating unit 140 and the node 11 of the wiring 101. The coil 152 is provided between the capacitor 142 of the insulating unit 140 and the node 12 of the wiring 102. This removes common mode noise from the communication signal output by the communication unit 120.

[0017] The filter circuit 160 is a high-pass filter and includes capacitors 161 and 162. The filter circuit 160 may be a band-pass filter having a cutoff frequency near the center frequency of the communication signal. The capacitor 161 is provided between one end of the coil 143b of the insulating unit 140 and the communication unit 120. The capacitor 162 is provided between the other end of the coil 143b of the insulating unit 140 and the communication unit 120. This prevents signals with relatively low frequencies, such as power supplied by the control unit 110, from being input to the communication unit 120.

[0018] The drive device 200 includes a drive unit 210, a communication section 220, an impedance upper 230, an insulator 240, a CMCC 250, and a filter circuit 260. The drive unit 210 is connected to the other end of one wire of a cable 300 by a wire 201, and is connected to the other end of the other wire of the cable 300 by a wire 202. The drive unit 210 includes, for example, a motor body, and is driven by power supplied through the cable 300. The communication section 220 includes, for example, a PLC modem, and communicates with the communication section 120 of the control device 100 by inputting or outputting communication signals through the wires 201, 202 and the cable 300.

[0019] The impedance upper 230 includes coils 231 and 232. The coil 231 is provided between the node 21 on the wiring 201 and the drive unit 210. The coil 232 is provided between the node 22 on the wiring 202 and the drive unit 210. The impedance of the portions of the wirings 201 and 202 where the coils 231 and 232 are provided increases. This prevents the communication signals output by the communication unit 220 to the wirings 201 and 202 from being input to the drive unit 210.

[0020] The insulating unit 240 includes capacitors 241 and 242 and an isolation transformer 243. The isolation transformer 243 includes coils 243a and 243b wound around a core and electrically insulated from each other. One end of the coil 243a of the isolation transformer 243 is connected to a node 21 of the wiring 201 via the capacitor 241. The other end of the coil 243a of the isolation transformer 243 is connected to a node 22 of the wiring 202 via the capacitor 242. Both ends of the coil 243b of the isolation transformer 243 are connected to the communication unit 220. This isolates the communication unit 220 from the power supplied by the control unit 110.

[0021] The CMCC 250 includes two coils 251 and 252 with the same number of turns wound around a core. The coil 251 is provided between the capacitor 241 of the insulating unit 240 and the node 21 of the wiring 201. The coil 252 is provided between the capacitor 242 of the insulating unit 240 and the node 22 of the wiring 202. This removes common mode noise from the communication signal output by the communication unit 220.

[0022] The filter circuit 260 is a high-pass filter and includes capacitors 261 and 262. The filter circuit 260 may be a band-pass filter having a cutoff frequency near the center frequency of the communication signal. The capacitor 261 is provided between one end of the coil 243b of the insulating unit 240 and the communication unit 220. The capacitor 262 is provided between the other end of the coil 243b of the insulating unit 240 and the communication unit 220. This prevents signals having relatively low frequencies, such as power supplied by the control unit 110, from being input to the communication unit 220.

[0023] (2) Communication Systems A communication system 400 is configured by the communication units 120 and 220, the impedance uppers 130 and 230, the insulating units 140 and 240, and the filter circuits 160 and 260. In the communication system 400, a matching circuit 410 is formed between the communication unit 120 and the cable 300 to reduce reflection of a communication signal at one end of the cable 300. An interface circuit 1 is also configured by the communication unit 120, a load other than the matching circuit 410 between the communication unit 120 and the cable 300, and the matching circuit 410. Similarly, a matching circuit 420 is formed between the communication unit 220 and the cable 300 to reduce reflection of a communication signal at the other end of the cable 300. An interface circuit 2 is also configured by the communication unit 220, a load other than the matching circuit 420 between the communication unit 220 and the cable 300, and the matching circuit 420.

[0024] In the present embodiment, the matching circuit 410 includes coils 131 and 132 of the impedance upper 130 and capacitors 141 and 142 of the insulating section 140. The coils 131 and 132 and the capacitors 141 and 142 each have a circuit constant that matches the impedance of the interface circuit 1 with the characteristic impedance of the cable 300. Specifically, the coils 131 and 132 and the capacitors 141 and 142 each are determined to have a circuit constant that makes the real part of the complex impedance of the interface circuit 1 match the characteristic impedance of the cable 300 and makes the imaginary part of the complex impedance of the interface circuit 1 zero at the center frequency of the communication signal.

[0025] Similarly, in the present embodiment, matching circuit 420 includes coils 231 and 232 of impedance upper 230 and capacitors 241 and 242 of insulating section 240. Each of coils 231 and 232 and capacitors 241 and 242 has a circuit constant that matches the impedance of interface circuit 2 with the characteristic impedance of cable 300. Specifically, each of coils 231 and 232 and capacitors 241 and 242 is determined to have a circuit constant that makes the real part of the complex impedance of interface circuit 2 match the characteristic impedance of cable 300 and makes the imaginary part of the complex impedance of interface circuit 2 zero at the center frequency of the communication signal.

[0026] 2 is a diagram showing the configuration of one interface circuit 1. The interface circuit 1 in FIG. 2 is shown as an equivalent circuit of the interface circuit 1 in FIG. 1. As shown in FIG. 2, the interface circuit 1 includes a matching circuit 410 and a load 3. The matching circuit 410 also includes a coil 411 and a capacitor 412. In this example, communication information is transmitted differentially using the wires 101 and 102 in FIG. 1, so that the coil 411 is equivalent to each of the coils 131 and 132, and the capacitor 412 is equivalent to each of the capacitors 141 and 142.

[0027] In the interface circuit 1, the coil 411, the capacitor 412 connected in series, and the load 3 are connected in parallel. In this case, the complex admittance Y1 (the reciprocal of the complex impedance) of the interface circuit 1 is expressed by the following formula (1). Furthermore, R p1 is expressed by the following formula (2), and X p1 is expressed by the following formula (3).

[0028]

number

[0029]

number

[0030]

number

[0031] Here, f is the center frequency of the communication information. L1 is the inductance of the coil 411 (each of the coils 131 and 132). C1 is the capacitance of the capacitor 412 (each of the capacitors 141 and 142). R1 ​​and X1 are the real and imaginary parts of the complex impedance of the load 3, respectively. The complex impedance of the load 3 can be measured by an impedance measuring instrument.

[0032] C1 is determined so that the real part of the complex impedance of the interface circuit 1, i.e., the inverse of the real part of equation (1), matches the characteristic impedance of the cable 300 at the center frequency of the communication signal. Also, L1 is determined so that the imaginary part of equation (1) (more precisely, the imaginary part of the complex impedance of the interface circuit 1) becomes 0 at the center frequency of the communication signal. Therefore, the characteristic impedance of the cable 300 is determined as R H Then, C1 is expressed by the following formula (4), and L1 is expressed by the following formula (5).

[0033]

number

[0034]

number

[0035] When the capacitor 412 and the coil 411 have the circuit constants shown in equations (4) and (5), respectively, the standing wave ratio in the cable 300 can be set to 1, and reflection of the communication signal at the end of the cable 300 can be prevented. As an example of numerical values, when f is 70 MHz, R1 is 40 Ω, X1 is 10 Ω, and R H is 75Ω, C1 is determined to be approximately 48 pF from equation (4), and L1 is determined to be approximately 182 nH from equation (5).

[0036] 3 is a diagram showing the configuration of the other interface circuit 2. The interface circuit 2 in FIG. 3 is shown as an equivalent circuit of the interface circuit 2 in FIG. 1. As shown in FIG. 3, the interface circuit 2 includes a matching circuit 420 and a load 4. The matching circuit 420 also includes a coil 421 and a capacitor 422. In this example, communication information is transmitted differentially using the wiring 201 and 202 in FIG. 1, so that the coil 421 is equivalent to each of the coils 231 and 232, and the capacitor 422 is equivalent to each of the capacitors 241 and 242.

[0037] In interface circuit 2, coil 421 is connected in parallel to capacitor 422 and load 4, which are connected in series. Here, similar to interface circuit 1, the inductance of coil 421 (each of coils 231 and 232) is denoted by L2, the capacitance of capacitor 422 (each of capacitors 241 and 242) is denoted by C2, and the complex impedance of load 4 is denoted by R2+jX2. In this case, C2 is expressed by the following equation (6), and L2 is expressed by the following equation (7). When capacitor 422 and coil 421 have the circuit constants expressed by equations (6) and (7), respectively, the standing wave ratio in cable 300 can be set to 1, and reflection of the communication signal at the end of cable 300 can be prevented.

[0038]

number

[0039]

number

[0040] (3) Effects In communication system 400 according to this embodiment, drive unit 210 of drive device 200 is driven by power supplied from control unit 110 of control device 100 through cable 300 having a predetermined characteristic impedance. Communication section 120 of control device 100 and communication section 220 of drive device 200 mutually input or output communication signals indicating communication information through cable 300.

[0041] An impedance increaser 130 including coils 131 and 132 is provided between the control unit 110 and the cable 300 to increase the impedance between the control unit 110 and the cable 300. An insulating unit 140 including capacitors 141 and 142 is provided between the communication unit 120 and the cable 300 to insulate the communication unit 120 from the power supplied by the control unit 110. A matching circuit 410 including a coil 411 (each of the coils 131 and 132) and a capacitor 412 (each of the capacitors 141 and 142) is formed between the communication unit 120 and the cable 300 to reduce reflection of a communication signal at one end of the cable 300.

[0042] According to this configuration, matching circuit 410 is formed by coils 131 and 132 of impedance upper 130 and capacitors 141 and 142 of insulating section 140. In other words, a matching circuit for reducing reflection of a communication signal at one end of cable 300 can be configured by utilizing a circuit configuration for impedance upper and a circuit configuration for insulation. This allows good communication between control device 100 and drive device 200 while preventing the connection structure of communication system 400 from becoming large.

[0043] The interface circuit 1 is formed by the communication unit 120, the load 3 other than the matching circuit 410 between the communication unit 120 and the cable 300, and the matching circuit 410. Each of the coil 411 (each of the coils 131 and 132) and the capacitor 412 (each of the capacitors 141 and 142) of the matching circuit 410 has a circuit constant that matches the impedance of the interface circuit 1 with the characteristic impedance of the cable 300. In this case, the matching circuit 410 can easily reduce reflection of the communication signal at one end of the cable 300.

[0044] Specifically, the coil 411 and the capacitor 412 each have circuit constants such that, at the center frequency of the communication signal, the real part of the complex impedance of the interface circuit 1 matches the characteristic impedance of the cable 300 and the imaginary part of the complex impedance of the interface circuit 1 is 0. In this case, the matching circuit 410 can more reliably reduce the reflection of the communication signal at one end of the cable 300.

[0045] Furthermore, an impedance increaser 230 including coils 231 and 232 is provided between the drive unit 210 and the cable 300, and increases the impedance between the drive unit 210 and the cable 300. An insulating unit 240 including capacitors 241 and 242 is provided between the communication unit 220 and the cable 300, and insulates the communication unit 220 from the power supplied by the control unit 110. A matching circuit 420 including a coil 421 (each of the coils 231 and 232) and a capacitor 422 (each of the capacitors 241 and 242) is formed between the communication unit 220 and the cable 300, and reduces reflection of the communication signal at the other end of the cable 300.

[0046] In this case, matching circuit 420 is formed by coils 231 and 232 of impedance upper 230 and capacitors 241 and 242 of insulating section 240. In other words, a matching circuit for reducing reflection of a communication signal at the other end of cable 300 can be configured by utilizing the circuit configuration for impedance upper and the circuit configuration for insulation. This allows for better communication between control device 100 and drive device 200 while preventing the connection structure of communication system 400 from becoming larger.

[0047] The interface circuit 2 is formed by the communication unit 220, the load 4 other than the matching circuit 420 between the communication unit 220 and the cable 300, and the matching circuit 420. Each of the coil 421 (each of the coils 231 and 232) and the capacitor 422 (each of the capacitors 241 and 242) has a circuit constant that matches the impedance of the interface circuit 2 with the characteristic impedance of the cable 300. In this case, the matching circuit 420 can easily reduce reflection of the communication signal at the other end of the cable 300.

[0048] Specifically, the coil 421 and the capacitor 422 each have circuit constants such that, at the center frequency of the communication signal, the real part of the complex impedance of the interface circuit 2 matches the characteristic impedance of the cable 300 and the imaginary part of the complex impedance of the interface circuit 2 is 0. In this case, the matching circuit 420 can more reliably reduce the reflection of the communication signal at the other end of the cable 300.

[0049] (4) Variations 4 is a diagram showing the configuration of control device 100 in a first modified example. As shown in FIG. 4, in this example, control device 100 further includes low-pass filter 170. Low-pass filter 170 includes coils 171 and 172 and capacitors 174 and 175, as well as coils 131 and 132. That is, coils 131 and 132 of impedance upper 130 form part of low-pass filter 170.

[0050] Low-pass filter 170 is provided between control unit 110 and communication unit 120. Specifically, coil 171 is connected between coil 131 and control unit 110. Coil 172 is connected between coil 132 and control unit 110. Capacitor 174 is connected between coils 131 and 171 and ground potential. Capacitor 175 is connected between coils 132 and 172 and ground potential. With this connection, low-pass filter 170 forms a third-order low-pass filter. Capacitors 174 and 175 may be connected between a portion of wiring 101 between coils 131 and 171 and a portion of wiring 102 between coils 132 and 172.

[0051] As described above, in the communication system 400 according to the first modification, a low-pass filter 170 is provided between the control unit 110 and the communication unit 120. The coils 131 and 132 form part of the low-pass filter 170. In this case, part of the low-pass filter 170 is formed by the coils 131 and 132 of the impedance upper 130. This prevents high-frequency components of the power supplied from the control unit 110 from being input to the communication unit 120. As a result, better communication can be achieved between the control device 100 and the drive device 200 while preventing the connection structure of the communication system 400 from becoming large.

[0052] Low-pass filter 170 is a high-order low-pass filter and further includes coils 171 and 172 and capacitors 174 and 175. Coil 171 is connected between coil 131 and control unit 110. Coil 172 is connected between coil 132 and control unit 110. Capacitor 174 is connected between coils 131 and 171 and ground potential. Capacitor 175 is connected between coils 132 and 172 and ground potential. In this case, high-frequency components of the power supplied from control unit 110 are more reliably prevented from being input to communication unit 120.

[0053] 2. Second embodiment In the first embodiment, the circuit constants of the coil 411 (each of the coils 131 and 132) and the capacitor 412 (each of the capacitors 141 and 142) are determined so that the impedance of the interface circuit 1 matches the characteristic impedance of the cable 300. Also, the circuit constants of the coil 421 (each of the coils 231 and 232) and the capacitor 422 (each of the capacitors 241 and 242) are determined so that the impedance of the interface circuit 2 matches the characteristic impedance of the cable 300. However, the embodiment is not limited to this.

[0054] The circuit constants of the other circuit elements provided in the interface circuit 1 may be determined so that the impedance of the interface circuit 1 matches the characteristic impedance of the cable 300. Similarly, the circuit constants of the other circuit elements provided in the interface circuit 2 may be determined so that the impedance of the interface circuit 2 matches the characteristic impedance of the cable 300.

[0055] For example, the interface circuit 1 includes the coils 131 and 132 of the impedance upper 130 and the capacitors 141 and 142 of the insulating unit 140, as well as the isolation transformer 143 of the insulating unit 140 and the capacitors 161 and 162 of the filter circuit 160. The interface circuit 2 includes the coils 231 and 232 of the impedance upper 230 and the capacitors 241 and 242 of the insulating unit 240, as well as the isolation transformer 243 of the insulating unit 240 and the capacitors 261 and 262 of the filter circuit 260.

[0056] Therefore, in this embodiment, matching circuit 410 is formed by setting coil 411 of interface circuit 1 as a coil equivalent to coil 143a or coil 143b of isolation transformer 143, and capacitor 412 as a capacitor equivalent to each of capacitors 161 and 162 of filter circuit 160. Also, matching circuit 420 is formed by setting coil 421 of interface circuit 2 as a coil equivalent to coil 243a or coil 243b of isolation transformer 243, and capacitor 422 as a capacitor equivalent to each of capacitors 261 and 262 of filter circuit 260. The method of determining the circuit constants of the circuit elements of matching circuits 410 and 420 in this embodiment is similar to the method of determining the circuit constants of the circuit elements of matching circuits 410 and 420 in the first embodiment.

[0057] As described above, in communication system 400 according to the present embodiment, an insulating unit 140 is provided between communication unit 120 and cable 300. The insulating unit 140 insulates communication unit 120 from the power supplied by control unit 110 and includes an insulating transformer 143 including coils 143a and 143b. A filter circuit 160 including capacitors 161 and 162 is provided between insulating unit 140 and communication unit 120. A matching circuit 410 is formed between communication unit 120 and cable 300, and includes a coil 411 (coil 143a or coil 143b) and a capacitor 412 (each of capacitors 161 and 162) to reduce reflection of a communication signal at the end of cable 300.

[0058] According to this configuration, the matching circuit 410 is formed by the coils 143a and 143b of the insulating section 140 and the capacitors 161 and 162 of the filter circuit 160. In other words, a matching circuit for reducing reflection of a communication signal at one end of the cable 300 can be configured by utilizing a circuit configuration for insulation and a circuit configuration for a filter circuit. This enables good communication between the control device 100 and the drive device 200 while preventing the connection structure of the communication system 400 from becoming large. Furthermore, by performing impedance matching using the coils 143a and 143b and the capacitors 161 and 162, the circuit constants of the coils 131 and 132 and the capacitors 141 and 142 that constitute the matching circuit 410 in the first embodiment can be freely set.

[0059] The interface circuit 1 is formed by the communication unit 120, the load 3 other than the matching circuit 410 between the communication unit 120 and the cable 300, and the matching circuit 410. Each of the coil 411 (coil 143a or coil 143b) and the capacitor 412 (each of the capacitors 161 and 162) of the matching circuit 410 has a circuit constant that matches the impedance of the interface circuit 1 with the characteristic impedance of the cable 300. In this case, the matching circuit 410 can easily reduce reflection of the communication signal at the end of the cable 300.

[0060] Specifically, the coil 411 and the capacitor 412 each have circuit constants such that, at the center frequency of the communication signal, the real part of the complex impedance of the interface circuit 1 matches the characteristic impedance of the cable 300 and the imaginary part of the complex impedance of the interface circuit 1 is 0. In this case, the matching circuit 410 can more reliably reduce the reflection of the communication signal at the end of the cable 300.

[0061] Furthermore, an insulating unit 240 is provided between the communication unit 220 and the cable 300, which insulates the communication unit 220 from the power supplied by the control unit 110 and has an insulating transformer 243 including coils 243a and 243b. A filter circuit 260 including capacitors 261 and 262 is provided between the insulating unit 240 and the communication unit 220. A matching circuit 420 is formed between the communication unit 220 and the cable 300, which includes a coil 421 (coil 243a or coil 243b) and a capacitor 422 (each of capacitors 261 and 262) and reduces reflection of the communication signal at the end of the cable 300.

[0062] In this case, the matching circuit 420 is formed by the coils 243a and 243b of the insulating unit 240 and the capacitors 261 and 262 of the filter circuit 260. That is, a matching circuit for reducing reflection of the communication signal at the other end of the cable 300 can be configured by utilizing a circuit configuration for insulation and a circuit configuration for the filter circuit. This enables better communication between the control device 100 and the drive device 200 while preventing the connection structure of the communication system 400 from becoming larger. Furthermore, by performing impedance matching using the coils 243a and 243b and the capacitors 261 and 262, the circuit constants of the coils 231 and 232 and the capacitors 241 and 242 that constitute the matching circuit 420 in the first embodiment can be freely set.

[0063] The interface circuit 2 is formed by the communication unit 220, the load 4 other than the matching circuit 420 between the communication unit 220 and the cable 300, and the matching circuit 420. Each of the coil 421 (coil 243a or coil 243b) and the capacitor 422 (each of the capacitors 261 and 262) of the matching circuit 420 has a circuit constant that matches the impedance of the interface circuit 2 with the characteristic impedance of the cable 300. In this case, the matching circuit 420 can easily reduce reflection of the communication signal at the end of the cable 300.

[0064] Specifically, the coil 421 and the capacitor 422 each have a circuit constant such that, at the center frequency of the communication signal, the real part of the complex impedance of the interface circuit 2 matches the characteristic impedance of the cable 300 and the imaginary part of the complex impedance of the interface circuit 2 is 0. In this case, the matching circuit 420 can more reliably reduce the reflection of the communication signal at the end of the cable 300.

[0065] 3. Other embodiments (1) In the above embodiment, the cable 300 is a single-phase cable or a twisted pair cable, but the embodiment is not limited to this. The cable 300 may be a cable having another type. FIG. 5 is a diagram showing the configuration of a communication system 400 according to another embodiment. As shown in FIG. 5, in this example, the cable 300 is a three-phase three-wire cable including three wires.

[0066] In this case, the control unit 110 is connected to one end of each of the three wires of the cable 300 by wires 101 to 103. Similarly, the drive unit 210 is connected to the other end of each of the three wires of the cable 300 by wires 201 to 203. The impedance upper 130 further includes a coil 133 provided on the wire 103. The impedance upper 230 further includes a coil 233 provided on the wire 203. Other configurations of the communication system 400 are similar to those of the communication system 400 in FIG. 1.

[0067] 5 may further include a low-pass filter 170. FIG. 6 is a diagram showing the configuration of the control device 100 in the second modification. As shown in FIG. 6, in this example, the low-pass filter 170 further includes a coil 173 and a capacitor 176, and also includes a coil 133. That is, the coil 133 of the impedance upper 130 also constitutes a part of the low-pass filter 170.

[0068] Coil 173 is connected between coil 133 and control unit 110. Capacitor 176 is connected between coils 133, 173 and ground potential. With this connection, low-pass filter 170 forms a third-order low-pass filter. Capacitor 174 may be connected between a portion of wiring 101 between coils 131, 171 and a portion of wiring 102 between coils 132, 172. Capacitor 175 may be connected between a portion of wiring 102 between coils 132, 172 and a portion of wiring 103 between coils 133, 173. Capacitor 176 may be connected between a portion of wiring 103 between coils 133, 173 and a portion of wiring 101 between coils 131, 171. Other configurations of control device 100 are similar to those of control device 100 in FIG. 4.

[0069] (2) In the above embodiment, the control device 100 includes the CMCC 150 and the drive device 200 includes the CMCC 250, but the embodiment is not limited to this. The control device 100 does not have to include the CMCC 150. Furthermore, the drive device 200 does not have to include the CMCC 250.

[0070] (3) In the above embodiment, the control device 100 includes both the impedance upper 130 and the filter circuit 160, but the embodiment is not limited to this. In the first embodiment, the control device 100 may include the impedance upper 130 but not the filter circuit 160. Furthermore, the insulating unit 140 may include the capacitors 141 and 142 but not the isolation transformer 143. On the other hand, in the second embodiment, the drive device 200 may include the filter circuit 160 but not the impedance upper 130. Furthermore, the insulating unit 140 may include the isolation transformer 143 but not the capacitors 141 and 142.

[0071] Similarly, the driving device 200 includes both the impedance upper 230 and the filter circuit 260, but the embodiment is not limited to this. In the first embodiment, the driving device 200 only needs to include the impedance upper 230, and does not need to include the filter circuit 260. Furthermore, the insulating unit 240 only needs to include the capacitors 241 and 242, and does not need to include the isolation transformer 243. On the other hand, in the second embodiment, the driving device 200 only needs to include the filter circuit 260, and does not need to include the impedance upper 230. Furthermore, the insulating unit 240 only needs to include the isolation transformer 243, and does not need to include the capacitors 241 and 242.

[0072] (4) In the above embodiment, the communication system 400 is provided with both the matching circuits 410 and 420, but the embodiment is not limited to this. The communication system 400 may be provided with the matching circuit 410 but not with the matching circuit 420. In this case, the driving device 200 may not include both the impedance upper 230 and the filter circuit 260, and may not include the insulating unit 240. Alternatively, the communication system 400 may be provided with the matching circuit 420 but not with the matching circuit 410. In this case, the control device 100 may not include both the impedance upper 130 and the filter circuit 160, and may not include the insulating unit 140.

[0073] Furthermore, the communication system 400 may be provided with the matching circuit 410 disclosed in the first embodiment and the matching circuit 420 disclosed in the second embodiment. Alternatively, the communication system 400 may be provided with the matching circuit 410 disclosed in the second embodiment and the matching circuit 420 disclosed in the first embodiment.

[0074] (5) In the above embodiment, low-pass filter 170 is a third-order low-pass filter, but the embodiment is not limited to this. Low-pass filter 170 may be a first-order low-pass filter. In this case, low-pass filter 170 does not include coils 171-173 or capacitors 174-176. Alternatively, low-pass filter 170 may be a higher-order low-pass filter, such as a fifth-order or seventh-order low-pass filter. In this case, low-pass filter 170 includes additional circuit elements in addition to coils 131-133, 171-173, or capacitors 174-176.

[0075] (6) The functions of the above-disclosed elements may be implemented using circuitry or processing circuitry, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (application-specific integrated circuits), conventional circuitry, and / or combinations thereof, configured to perform the disclosed elements or programmed to perform the disclosed functions. A processor is considered processing circuitry or circuitry when it includes transistors and other circuitry therein. In this disclosure, a circuitry, unit, or means is hardware that performs the recited function or hardware programmed to perform the function. The hardware may be any hardware disclosed herein or other known hardware that is programmed to perform or configured to perform the recited function. When the hardware is a processor, which may be considered a type of circuitry, the circuitry, means, or unit is a combination of hardware and software, software used to configure the hardware, and / or processor.

[0076] 4. Correspondence between each element of the claims and each part of the embodiment Below, examples of correspondence between each element of the claims and each element of the embodiments will be described, but the present invention is not limited to the following examples. Various other elements having the configuration or function described in the claims can also be used as each element of the claims.

[0077] In the above-described embodiments, cable 300 is an example of a cable, control unit 110 is an example of a control unit, communication unit 120 is an example of a first communication unit, drive unit 210 is an example of a drive unit, communication unit 220 is an example of a second communication unit, control system 500 is an example of a control system, drive device 200 is an example of a drive device, and coil 411 (each of coils 131 and 132 or each of coils 143a and 143b) is an example of a first coil.

[0078] Impedance upper 130 is an example of a first impedance upper, and capacitor 412 (each of capacitors 141, 142 or each of capacitors 161, 162) is an example of a first capacitor. Insulation unit 140 is an example of a first insulation unit, matching circuit 410 is an example of a first matching circuit, communication system 400 is an example of a communication system, interface circuit 1 is an example of a first interface circuit, and coil 421 (each of coils 231, 232 or each of coils 243a, 243b) is an example of a second coil. Impedance upper 230 is an example of a second impedance upper, and capacitor 422 (each of capacitors 241, 242 or each of capacitors 261, 262) is an example of a second capacitor.

[0079] The insulating unit 240 is an example of a second insulating unit, the matching circuit 420 is an example of a second matching circuit, the interface circuit 2 is an example of a second interface circuit, the low-pass filter 170 is an example of a low-pass filter, the coils 171 and 172 are examples of a third coil, the capacitors 174 and 175 are examples of a third capacitor, the filter circuit 160 is an example of a first filter circuit, and the filter circuit 260 is an example of a second filter circuit.

[0080] 5. Summary of the embodiment (1) The communication system according to paragraph 1 is 1. A communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance, and a drive unit that is supplied with power through the cable, a first communication unit and a second communication unit that mutually input or output a communication signal indicating communication information through the cable; a first impedance upper provided between one of the control unit and the drive unit and the cable, the first impedance upper increasing the impedance between the one unit and the cable and including a first coil; a first insulating unit provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from power supplied by the control unit, and including a first capacitor; A first matching circuit including the first coil and the first capacitor is formed between the one communication section and the cable, and reduces reflection of the communication signal at the end of the cable.

[0081] In this communication system, the first matching circuit is formed by the first coil of the first impedance upper and the first capacitor of the first insulating section. That is, a matching circuit for reducing reflection of a communication signal at the end of a cable can be configured by utilizing a circuit configuration for impedance upper and a circuit configuration for insulation. This enables good communication between the first communication section and the second communication section while preventing the connection structure of the communication system from becoming large.

[0082] (2) In the communication system according to (1), a first interface circuit including the first matching circuit is formed between the one communication unit and the cable; Each of the first coil and the first capacitor may have a circuit constant that matches the impedance of the first interface circuit with the characteristic impedance of the cable.

[0083] In this case, the first matching circuit can easily reduce reflection of the communication signal at the end of the cable.

[0084] (Item 3) In the communication system according to item 2, Each of the first coil and the first capacitor may have a circuit constant such that, at a center frequency of the communication signal, the real part of the complex impedance of the first interface circuit matches the characteristic impedance of the cable and the imaginary part of the complex impedance of the first interface circuit is zero.

[0085] In this case, the first matching circuit can more reliably reduce reflection of the communication signal at the end of the cable.

[0086] (4) The communication system according to any one of paragraphs 1 to 3, a second impedance upper provided between the other of the control unit and the drive unit and the cable, for increasing impedance between the other unit and the cable, and including a second coil; a second insulating unit provided between the other of the first communication unit and the second communication unit and the cable, insulating the other communication unit from power supplied by the control unit, and including a second capacitor; A second matching circuit including the second coil and the second capacitor may be formed between the other communication unit and the cable, the second matching circuit reducing reflection of the communication signal at the end of the cable.

[0087] In this case, the second matching circuit is formed by the second coil of the second impedance upper and the second capacitor of the second insulating part. That is, a matching circuit for reducing reflection of the communication signal at the end of the cable can be configured by utilizing the circuit configuration for impedance upper and the circuit configuration for insulation. This allows for better communication between the control device and the drive device while preventing the connection structure of the communication system from becoming larger.

[0088] (5) In the communication system according to the fourth aspect, a second interface circuit including the second matching circuit is formed between the other communication unit and the cable; Each of the second coil and the second capacitor may have a circuit constant that matches the impedance of the second interface circuit with the characteristic impedance of the cable.

[0089] In this case, the second matching circuit can easily reduce the reflection of the communication signal at the end of the cable.

[0090] (Item 6) In the communication system according to item 5, Each of the second coil and the second capacitor may have a circuit constant such that, at a center frequency of the communication signal, the real part of the complex impedance of the second interface circuit matches the characteristic impedance of the cable and the imaginary part of the complex impedance of the second interface circuit is zero.

[0091] In this case, the second matching circuit can more reliably reduce the reflection of the communication signal at the end of the cable.

[0092] (7) The communication system according to any one of paragraphs 1 to 6, further comprising a low-pass filter provided between the control unit and the first communication unit; The first coil may form part of the low-pass filter.

[0093] In this case, a part of the low-pass filter is formed by the first coil of the first impedance upper. This prevents high-frequency components of the power supplied from the control unit from being input to the first communication unit. As a result, better communication can be achieved between the control device and the drive device while preventing the connection structure of the communication system from becoming large.

[0094] (Item 8) In the communication system according to item 7, The low-pass filter is a third coil connected between the first coil and the control unit; The high-order low-pass filter may include a third capacitor connected between the first coil and the third coil and ground potential.

[0095] In this case, high frequency components of the power supplied from the control unit are more reliably prevented from being input to the first communication section.

[0096] (Item 9) The communication system according to item 9 is 1. A communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance, and a drive unit that is supplied with power through the cable, a first communication unit and a second communication unit that mutually input or output a communication signal indicating communication information through the cable; a first insulating unit provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from power supplied by the control unit, and including a first coil; a first filter circuit provided between the first insulating unit and the one communication unit and including a first capacitor; A first matching circuit including the first coil and the first capacitor is formed between the one communication section and the cable, and reduces reflection of the communication signal at the end of the cable.

[0097] In this communication system, the first matching circuit is formed by the first coil of the first insulating section and the first capacitor of the first filter circuit. That is, a matching circuit for reducing reflection of the communication signal at the end of the cable can be configured by utilizing the circuit configuration for isolation and the circuit configuration for the filter circuit. This allows for good communication between the control device and the drive device while preventing the connection structure of the communication system from becoming large.

[0098] (Item 10) In the communication system according to item 9, a first interface circuit including the first matching circuit is formed between the one communication unit and the cable; Each of the first coil and the first capacitor may have a circuit constant that matches the impedance of the first interface circuit with the characteristic impedance of the cable.

[0099] In this case, the first matching circuit can easily reduce reflection of the communication signal at the end of the cable.

[0100] (Item 11) In the communication system according to item 10, Each of the first coil and the first capacitor may have a circuit constant such that, at a center frequency of the communication signal, the real part of the complex impedance of the first interface circuit matches the characteristic impedance of the cable and the imaginary part of the complex impedance of the first interface circuit is zero.

[0101] In this case, the first matching circuit can more reliably reduce reflection of the communication signal at the end of the cable.

[0102] (12) The communication system according to any one of paragraphs 9 to 11, a second insulating unit provided between the other of the first communication unit and the second communication unit and the cable, insulating the other communication unit from power supplied by the control unit, and including a second coil; a second filter circuit provided between the second insulating unit and the other communication unit and including a second capacitor; A second matching circuit including the second coil and the second capacitor may be formed between the other communication unit and the cable, the second matching circuit reducing reflection of the communication signal at the end of the cable.

[0103] In this case, the second matching circuit is formed by the second coil of the second insulating section and the second capacitor of the second filter circuit. That is, a matching circuit for reducing reflection of the communication signal at the end of the cable can be configured by utilizing the circuit configuration for isolation and the circuit configuration for the filter circuit. This allows for better communication between the control device and the drive device while preventing the connection structure of the communication system from becoming larger.

[0104] (13) In the communication system according to claim 12, a second interface circuit including the second matching circuit is formed between the other communication unit and the cable; Each of the second coil and the second capacitor may have a circuit constant that matches the impedance of the second interface circuit with the characteristic impedance of the cable.

[0105] In this case, the second matching circuit can easily reduce the reflection of the communication signal at the end of the cable.

[0106] (14) In the communication system according to claim 13, Each of the second coil and the second capacitor may have a circuit constant such that, at a center frequency of the communication signal, the real part of the complex impedance of the second interface circuit matches the characteristic impedance of the cable and the imaginary part of the complex impedance of the second interface circuit is zero.

[0107] In this case, the second matching circuit can more reliably reduce the reflection of the communication signal at the end of the cable. [Explanation of symbols]

[0108] 1, 2... interface circuit, 3, 4... load, 11, 12, 21, 22... node, 100... control device, 101 to 103, 201 to 203... wiring, 110... control unit, 120, 220... communication section, 130, 230... impedance upper, 131 to 133, 143a, 143b, 151, 152, 171 to 173, 231 to 233, 243a, 243b, 251, 252, 411, 421... Coil, 140, 240...insulating part, 141, 142, 161, 162, 174 to 176, 241, 242, 261, 262, 412, 422...capacitor, 143, 243...insulating transformer, 150, 250...CMCC, 160, 260...filter circuit, 200...drive device, 210...drive unit, 300...cable, 400...communication system, 410, 420...matching circuit, 500...control system

Claims

1. 1. A communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance, and a drive unit that is supplied with power through the cable, a first communication unit and a second communication unit that mutually input or output a communication signal indicating communication information through the cable; a first impedance upper provided between one of the control unit and the drive unit and the cable, the first impedance upper increasing the impedance between the one of the control unit and the drive unit and the cable, and including a first coil; a first insulating unit provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from power supplied by the control unit, and including a first capacitor; a first matching circuit including the first coil and the first capacitor, the first matching circuit reducing reflection of the communication signal at the end of the cable, formed between the one communication unit and the cable;

2. a first interface circuit including the first matching circuit is formed between the one communication unit and the cable; 2. The communication system according to claim 1, wherein each of the first coil and the first capacitor has a circuit constant that matches the impedance of the first interface circuit with the characteristic impedance of the cable.

3. 3. The communication system according to claim 2, wherein the first coil and the first capacitor each have a circuit constant such that a real part of a complex impedance of the first interface circuit matches the characteristic impedance of the cable and an imaginary part of the complex impedance of the first interface circuit becomes zero at a center frequency of the communication signal.

4. a second impedance upper provided between the other of the control unit and the drive unit and the cable, for increasing impedance between the other unit and the cable, and including a second coil; a second insulating unit provided between the other of the first communication unit and the second communication unit and the cable, insulating the other communication unit from power supplied by the control unit, and including a second capacitor; 4. The communication system according to claim 1, wherein a second matching circuit including the second coil and the second capacitor is formed between the other communication unit and the cable, the second matching circuit reducing reflection of the communication signal at the end of the cable.

5. a second interface circuit including the second matching circuit is formed between the other communication unit and the cable; 5. The communication system according to claim 4, wherein each of the second coil and the second capacitor has a circuit constant that matches the impedance of the second interface circuit with the characteristic impedance of the cable.

6. 6. The communication system according to claim 5, wherein the second coil and the second capacitor each have a circuit constant such that a real part of a complex impedance of the second interface circuit matches the characteristic impedance of the cable and an imaginary part of the complex impedance of the second interface circuit becomes zero at a center frequency of the communication signal.

7. further comprising a low-pass filter provided between the control unit and the first communication unit; 4. The communication system according to claim 1, wherein the first coil forms a part of the low-pass filter.

8. The low-pass filter is a third coil connected between the first coil and the control unit; 8. The communication system of claim 7, wherein the high-order low-pass filter includes a third capacitor connected between the first coil and the third coil and ground potential.

9. 1. A communication system provided in a control system including a control unit that supplies power through a cable having a predetermined characteristic impedance, and a drive unit that is supplied with power through the cable, a first communication unit and a second communication unit that mutually input or output a communication signal indicating communication information through the cable; a first insulating unit provided between one of the first communication unit and the second communication unit and the cable, insulating the one communication unit from power supplied by the control unit, and including a first coil; a first filter circuit provided between the first insulating unit and the one communication unit and including a first capacitor; a first matching circuit including the first coil and the first capacitor, the first matching circuit reducing reflection of the communication signal at the end of the cable, formed between the one communication unit and the cable;

10. a first interface circuit including the first matching circuit is formed between the one communication unit and the cable; 10. The communication system according to claim 9, wherein each of the first coil and the first capacitor has a circuit constant that matches the impedance of the first interface circuit with the characteristic impedance of the cable.

11. 11. The communication system according to claim 10, wherein each of the first coil and the first capacitor has a circuit constant such that a real part of a complex impedance of the first interface circuit matches the characteristic impedance of the cable and an imaginary part of the complex impedance of the first interface circuit becomes zero at a center frequency of the communication signal.

12. a second insulating unit provided between the other of the first communication unit and the second communication unit and the cable, insulating the other communication unit from power supplied by the control unit, and including a second coil; and a second filter circuit provided between the second insulating unit and the other communication unit and including a second capacitor; 12. The communication system according to claim 9, wherein a second matching circuit including the second coil and the second capacitor is formed between the other communication unit and the cable, the second matching circuit reducing reflection of the communication signal at the end of the cable.

13. a second interface circuit including the second matching circuit is formed between the other communication unit and the cable; 13. The communication system according to claim 12, wherein each of the second coil and the second capacitor is matched to an impedance of the second interface circuit and the characteristic impedance of the cable.

14. 14. The communication system according to claim 13, wherein the second coil and the second capacitor each have a circuit constant such that a real part of a complex impedance of the two interface circuits matches the characteristic impedance of the cable and an imaginary part of a complex impedance of the second interface circuit becomes zero at a center frequency of the communication signal.

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