Power supply device, programmable controller, and power supply method

Abstract

An execution unit (13) comprises: a program executor (135) that has a signal ground; a frame ground that has a terminal that is electrically connected to the outside; and a power supplier (131) that is electrically connected to the signal ground and the frame ground and supplies power extracted from common mode noise that occurs between the signal ground and the frame ground.

Description

Power supply device, programmable controller, and power supply method

[0001] The present disclosure relates to a power supply device, a programmable controller, and a power supply method.

[0002] In recent years, technologies for energy harvesting or ambient power generation that utilize energy existing in the environment have attracted attention. For example, Patent Document 1 describes a technology for extracting electric field energy existing in space and outputting that energy as electric power.

[0003] International Publication No. 2024 / 004731

[0004] In the technology of Patent Document 1, a large metal conductor is used as one of two antenna elements. When applying this technology to the site of FA (Factory Automation), since it is conceivable to use an existing metal conductor at the site as the antenna element that is a large metal conductor, one antenna element can be limited to some extent. However, it is not clear what kind of connection destination is appropriate as the other antenna element, and there was a possibility that effective energy harvesting could not be carried out at the site of FA.

[0005] The present disclosure has been made under the above circumstances, and an object thereof is to carry out effective energy harvesting at the site of FA.

[0006] To achieve the above object, the power supply device of the present disclosure includes a signal circuit having a signal ground, a frame ground having a terminal electrically connected to the outside, and a supply unit that is electrically connected to the signal ground and the frame ground and supplies power extracted from common-mode noise generated between the signal ground and the frame ground.

[0007] According to the present disclosure, effective energy harvesting can be carried out at the site of FA.

[0008] A diagram showing the configuration of a PLC according to an embodiment. A diagram showing the internal configuration of the units constituting the PLC according to an embodiment. A diagram showing the functional configuration of the execution unit according to an embodiment. A diagram showing an example of the circuit configuration of the power supply unit according to an embodiment. A diagram for explaining the monitoring results by the power monitoring unit and error monitoring unit according to an embodiment. A diagram showing the functional configuration of the execution unit according to a modified example.

[0009] The factory automation system according to the embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] Embodiment. The factory automation system 100 according to this embodiment is a control system that repeatedly performs predetermined processing steps by controlling controlled equipment in facilities such as factories and plants. Hereinafter, the factory automation system will be referred to as the FA system.

[0011] As shown in Figure 1, the FA system 100 includes a PLC (Programmable Logic Controller) 10 that controls the equipment 20, equipment 20 corresponding to the controlled equipment, and a control panel 30 for workers to input instructions, including the start and end of control by the PLC 10, at the worksite. The PLC 10 controls the equipment 20 to perform processing steps such as manufacturing, machining, welding, chemical application, inspection, or transport of a large number of workpieces. The equipment 20 may be, for example, an actuator, machine tool, sensor, or robot, or other FA equipment.

[0012] The PLC 10 is a building block type control device that operates by combining multiple units. The PLC 10 is an example of a programmable controller. The PLC 10 includes a power supply unit 11 that provides power to other units, a plate 12 that shields electromagnetic noise propagating from the power supply unit 11 to other units, an execution unit 13 that executes a control program that defines the content of control for the equipment 20, an I / O unit 14 that sends and receives signals to and from the equipment 20, a processing unit 15 that executes predetermined processing, a communication unit 16 for communication via a network NW, and a base unit 17 on which each unit is mounted.

[0013] The power supply unit 11 receives AC power from the commercial power supply 40 and supplies DC power obtained by A / D conversion to other units. The power supply unit 11 has three terminals, which are connected to the base unit 17. Two of the three terminals are for supplying the power supply potential and a reference potential that serves as a reference for the power supply potential to each unit via the base unit 17. The other terminal is for sharing the frame ground potential with other units via the base unit 17.

[0014] The potential of the frame ground may be shared not by terminal connections, but by fixing a conductive housing to a conductive fixing device. For example, if the housing that serves as the frame ground of the power supply unit 11 is fixed to the housing of the base unit 17 by conductive screws, the potential of the frame ground will be shared between the power supply unit 11 and the base unit 17. The terminals and fixing devices of the frame ground are examples of connections that are electrically connected to the outside.

[0015] In the following, the frame ground potential and the component of the PLC 10 having that potential may be denoted as FG without distinction. Also, the reference potential of the signal line in the signal circuit described later may be referred to as the signal ground, and the signal ground potential and the component of the PLC 10 having that potential may be denoted as SG without distinction.

[0016] FG is typically all or part of a housing made of a conductor, such as metal, but is not limited to this; it may also be a large conductive member equivalent to all or part of the housing of the unit. For example, if a conductive member for the purpose of blocking electromagnetic noise is arranged on almost the entire surface of one of the six faces of a roughly rectangular unit, this conductive member may be the FG. It is desirable that the FG be grounded, but it is not required.

[0017] Plate 12 is an example of a plate-shaped plate that serves as a frame ground, positioned between the power supply unit and the power supply device. Note that plate 12 may be built into the power supply unit 11 or it may be integrated with the power supply unit 11. The following description will focus on an example where plate 12 is independent of the power supply unit 11.

[0018] The execution unit 13, I / O unit 14, processing unit 15, and communication unit 16 each have three terminals corresponding to the three terminals of the power supply unit 11. Note that other terminals connecting the units are omitted in Figure 1. For example, the execution unit 13 transmits a signal indicating an operation command for the device 20 obtained by executing a control program to the I / O unit 14 via the base unit 17. Therefore, the execution unit 13 and the I / O unit 14 have terminals for sending and receiving signals, but these terminals are omitted in Figure 1. Also, the FGs of the execution unit 13, I / O unit 14, processing unit 15, and communication unit 16 may be electrically connected to the outside at connection points other than terminals, similar to the power supply unit 11.

[0019] Figure 2 schematically shows the internal configuration of the power supply unit 11, execution unit 13, I / O unit 14, and base unit 17. As shown in Figure 2, the power supply unit 11 includes an FLT / rectifier unit 111 that receives AC power from the commercial power supply through the N (Neutral) terminal and L (Live) terminal, filters and rectifies it to output DC power, and a DC / DC converter unit 112 that generates the power supply potential and an SG which serves as a reference for the power supply potential from the output DC power.

[0020] The FLT / rectifier unit 111 is connected to the LG (Line filter Ground) terminal by an electric wire, and the LG terminal is connected to the FG terminal by an electric wire and also to the control panel FG 30f, which is the FG of the control panel 30, by a cable. In Figure 2, the electric wire shown as a thin rectangle with hatched diagonal lines is the FG, which will be appropriately referred to as the FG wire below. The FG terminal is the terminal connected to the FG.

[0021] The DC / DC converter 112 supplies a voltage of 5V as the power potential and SG (signal generator) via a power line. In Figure 2, the power line, shown as a thin rectangle with dark hatching, has the potential of SG and will be referred to as the SG line below. The SG line 11s, which supplies SG from the DC / DC converter 112, is connected to a connector 11a for connection to the base unit 17.

[0022] Furthermore, an FG sheet metal 11f is provided inside the power supply unit 11 to block electromagnetic noise generated from the FLT / rectifier unit 111 and the DC / DC converter unit 112 from propagating to other units. The FG sheet metal 11f is connected to the FG terminal with an FG wire. The FG sheet metal 11f may correspond to a plate 12 that is located inside the power supply unit 12.

[0023] The base unit 17 includes an SG wire 17s, an FG wire 17f, and an FG sheet metal 17b. The SG wire 17s receives SG from the connector 11a and supplies SG to the execution unit 13 via the connector 13a of the execution unit 13, and supplies SG to the I / O unit 14 via the connector 14a of the I / O unit.

[0024] The FG wire 17f is electrically connected to the FG sheet metal 17b via a screw 17c. In addition, the FG wire 17f and the SG wire 17s are connected at multiple points via capacitors, creating a structure that allows noise from the SG wire 17s to be discharged to the FG wire 17f.

[0025] The FG sheet metal 17b may be all or part of the housing of the base unit 17, or it may be a sheet metal provided inside the base unit 17. The FG sheet metal 17b is electrically connected to the FG sheet metal 11f in the power supply unit 11, the plate 12, the FG line 13f in the execution unit 13, and the FG line 14f in the I / O unit 14 via the metal fittings 17d.

[0026] The execution unit 13 has two circuit boards 13x and 13y. Circuit board 13x has an Ethernet communication unit for Ethernet® communication and a USB (Universal Serial Bus) communication unit, and circuit board 13y has an SRAM (Static Random Access Memory) card reading unit. These communication and reading units are each enclosed by a signal ground (FG), so that the signal processing performed inside them is protected from external electromagnetic noise. These communication and reading units correspond to an example of a signal circuit having a signal ground. The FG is electrically connected to, or includes, a plate-shaped conductor larger than the circuit board on which the signal circuit is formed.

[0027] The FG of substrates 13x and 13y have a common potential, for example, due to a metal screw. The FG of substrate 13x corresponds to the FG line 13f. Substrates 13x and 13y are multilayer substrates and have an SG pattern as a solid pattern in the inner layer. In addition, connecting conductors and solid patterns as SG are formed on the surface layer of substrates 13x and 13y as needed.

[0028] Furthermore, the SG line 13s connected to the connector 13a of the execution unit 13 supplies SG to the communication unit described above, and also supplies SG to the substrate 13y via the connector. In addition, SG may be supplied from the substrate 13x to the substrate 13y via a metal spacer 13z, as shown in Figure 2.

[0029] The substrate 13x further includes a power supply unit 131 that extracts and utilizes power from common-mode noise generated between the SG line 13s and the FG line 13f. Common-mode noise is typically noise that leaks mainly through stray capacitance and returns to the power line via the ground. Common-mode noise is characterized by the fact that the direction of the noise current flowing on the positive and negative sides of the power supply is the same.

[0030] Figure 3 shows an overview of the functional configuration of the execution unit 13. As shown in Figure 3, the execution unit 13 has the following functions: a power supply unit 131, a power storage unit 132 that stores the power supplied from the power supply unit 131, an RTC (Real-Time Clock) 133 that measures time using the power stored in the power storage unit 132, a power monitoring unit 134 that monitors the power supplied from the power supply unit 131, a program execution unit 135 that executes a control program, an error monitoring unit 136 that monitors for errors that occur when the control program is executed, and a storage unit 137 that stores the monitoring results from the power monitoring unit 134 and the error monitoring unit 136.

[0031] The power supply unit 131 extracts power from the common-mode noise generated between the signal generator (SG) and the frame generator (FG) and supplies it to the energy storage unit 132. The power supply unit 131 is electrically connected to the signal ground of the signal circuit and the frame ground of the power supply device, and is an example of a power supply unit that supplies power extracted from the common-mode noise generated between the signal ground and the frame ground.

[0032] The RTC 133, for example, has a crystal oscillator and measures time using the power stored in the energy storage unit 132. The RTC 133 also measures time while the power supplied to the execution unit 13 or PLC 10 from the power supply unit 11 is switched to the OFF state, and even if the execution unit 13 or PLC 10 restarts, it provides the program execution unit 135 with time information that has been continuously measured since before the restart.

[0033] The power monitoring unit 134 records the time when the magnitude of power supplied from the power supply unit 131 exceeds a predetermined threshold in the storage unit 137 as the timing when excessive common-mode noise occurred. The power monitoring unit 134 is an example of a monitoring unit that monitors the power supplied from the supply unit and records the timing when power greater than a predetermined threshold is supplied.

[0034] The program execution unit 135 has a processing circuit represented by a CPU (Central Processing Unit) or MPU (Micro Processing Unit), and a storage device represented by RAM (Random Access Memory) and ROM (Read-Only Memory), and operates on power supplied from the power supply unit 11. The program execution unit 135 corresponds to an example of a signal circuit having a signal ground.

[0035] Figure 4 shows a specific circuit configuration of a power supply unit 131a, a power storage unit 132a, and a power monitoring unit 134a, which is an example of a power supply unit 131, a power storage unit 132, and a power monitoring unit 134. As shown in Figure 4, the power supply unit 131a is configured as a full-wave rectifier circuit including diodes 51, 52, 53, and 54, a Zener diode 55 which is an electrostatic varistor, and a reverse current prevention diode 56. The power storage unit 132a is a capacitor, and the capacitance of the capacitor is determined considering the amount of common-mode noise generated, the power consumption of the RTC 133, and the expected operating period length of the RTC 133. The power monitoring unit 134a is a high-resistance sensor or voltmeter. Figure 4 shows an example in which the power monitoring unit 134a operates with the output voltage of the power storage unit 132a, but is not limited to this, and the power monitoring unit 134 may operate with power supplied from the power supply unit 11.

[0036] Figure 5 shows an example of information stored in the memory unit 137. As shown in Figure 5, the power monitoring unit 134 records the time when excessive common-mode noise occurs as the time of excessive noise occurrence, and the error monitoring unit 136 records the error code indicating the type of error that occurred, in association with the time of the error occurrence. As indicated by the arrows in Figure 5, if excessive noise and an error occur at the same time, it strongly suggests that the noise is the cause of the error in subsequent maintenance work, and this can be used to investigate the cause of the error. Although Figure 5 shows an example in which UNIX® time is used as the time, the unit of time is not limited to this. The format of both or one of the times can be changed as long as it is possible to associate the occurrence of noise with the occurrence of errors.

[0037] As explained above, the power supply unit 131 of the execution unit 13 in the FA system 100 supplies power extracted from common-mode noise generated between the signal generator (SG) and the frame generator (FG). Noise generated in the PLC 10 can be distinguished into normal-mode noise and common-mode noise. Here, normal-mode noise is noise added to the signal or generated between power lines, and refers to the noise current that flows along the same route as the signal in the signal circuit. Common-mode noise has a greater impact on FA equipment than normal-mode noise. For this reason, common-mode noise countermeasures are important. According to the execution unit 13 of this embodiment, common-mode noise is converted into power and consumed, so not only is the occurrence of malfunctions due to noise suppressed, but the energy of the noise can also be effectively utilized. Furthermore, because the energy of the noise is consumed, it is expected to have noise immunity.

[0038] Furthermore, FG is the housing of a unit constituting the PLC 10 or a conductor of a similar size to that housing, and SG is the inner layer solid pattern of the substrate 13x, 13y. Therefore, the power supply unit 131 can be said to perform energy harvesting by generating electricity from electromagnetic noise present in the environment of the PLC 10 using a dipole antenna with FG and SG as antennas. From the above, the execution unit 13 can perform effective energy harvesting in the factory automation (FA) field.

[0039] Furthermore, the execution unit 13 includes a power storage unit 132 that stores power supplied from the power supply unit 131, and an RTC 133 that measures time using the power stored in the power storage unit 132. This makes it possible to omit or miniaturize the battery required to operate the RTC 133.

[0040] Typically, programmable logic controllers require a battery to retain time data measured by the Real Time Clock (RTC) even when the power is off. Since batteries have a limited lifespan, users are required to replace them. Thus, maintaining time data requires a power supply, which imposes a burden on the user.

[0041] In contrast, the execution unit 13 according to this embodiment supplies power stored from electromagnetic noise energy to the RTC 133. Therefore, battery replacement work can be omitted, and the workload on the user can be reduced.

[0042] Furthermore, the execution unit 13 has a power monitoring unit 134 that monitors the power supplied from the power supply unit 131 and records the timing when the power supplied exceeds a predetermined threshold. This allows for recording the timing of excessive noise to be used later. Specifically, as mentioned above, it can be used to investigate the cause of errors by comparing it with the monitoring results from the error monitoring unit 136. In addition, by recording the monitoring results of the power monitoring unit 134 for each candidate installation location of the PLC 10 and comparing the records of each candidate, it is possible to select a location where the frequency of noise occurrence is relatively low.

[0043] As described above, the embodiments of the present disclosure have been explained, but the present disclosure is not limited to the above embodiments.

[0044] For example, the power supply destination by the power supply unit 131 may be a component different from the RTC 133. For example, power from the power supply unit 131 may be supplied to a sensor that should also operate while the power of the PLC 10 is in the OFF state.

[0045] Also, the unit having the power supply unit 131 may be a unit other than the execution unit 13. Furthermore, the device having the power supply unit 131 may be a device other than the PLC 10.

[0046] Also, the power supplied from the power supply unit 131 may be output to the outside of the device having the power supply unit 131.

[0047] The execution unit 13 having the power supply unit 131 corresponds to an example of a power supply device in the FA system.

[0048] Also, although an example in which the PLC 10 is of the building block type has been described, it is not limited to this, and the PLC 10 may be an integrated control device having functions equivalent to those of the above units. Also, as examples of the signal circuit, the communication unit and the reading unit of the execution unit 13, and the program execution unit 135 have been given, but the signal circuit is not limited to these examples. The signal circuit may be any circuit that allows signals to flow in order to operate the FA system as designed.

[0049] Also, as shown in FIG. 6, the execution unit 13 may be configured by omitting the power storage unit 132, and the power supply unit 131 may directly supply power to the RTC 133. The power supply unit 131 corresponds to an example of a supply unit that directly supplies power to a real-time clock.

[0050] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure.

[0051] This disclosure is suitable for utilizing noise generated in factory automation (FA) environments.

[0052] 10 PLC, 11 Power supply unit, 11a, 13a, 14a Connectors, 11f FG sheet metal, 11s, 13s, 17s SG wires, 12 Plate, 13 Execution unit, 13f, 14f, 17f FG wires, 13x, 13y Circuit board, 13z Spacer, 14 I / O unit, 15 Processing unit, 16 Communication unit, 17 Base unit, 17b FG sheet metal, 17c Screws, 17d Metal fittings, 20 Equipment, 30 Control panel, 30f Control panel FG, 40 Commercial power supply, 51-54 Diodes, 55 Zener diodes, 56 Reverse current prevention diodes, 100 FA system, 111 FLT / rectifier section, 112 DC / DC converter section, 131, 131a Power supply section, 132, 132a Energy storage unit, 133 RTC, 134, 134a Power monitoring unit, 135 Program execution unit, 136 Error monitoring unit, 137 Memory unit.

Claims

1. A power supply device comprising: a signal circuit having a signal ground; a frame ground having a connection part electrically connected to the outside; and a supply unit electrically connected to the signal ground and the frame ground, which supplies power extracted from common-mode noise generated between the signal ground and the frame ground.

2. The power supply device according to claim 1, further comprising: a power storage unit for storing power supplied from the power supply unit; and a real-time clock for timing using the power stored in the power storage unit.

3. The power supply device according to claim 1, further comprising a real-time clock for timing, wherein the supply unit directly supplies power to the real-time clock.

4. The power supply device according to any one of claims 1 to 3, further comprising: a monitoring unit that monitors the power supplied from the supply unit and records the timing at which power greater than a predetermined threshold is supplied.

5. A programmable controller comprising: a power supply device according to any one of claims 1 to 4; and a unit different from the power supply device, wherein the power supply device and the unit share the potential of the signal ground and the frame ground.

6. A programmable controller comprising: a power supply unit; and a power supply device according to any one of claims 1 to 4, wherein the power supply device is an execution unit that executes a control program for controlling equipment, the signal ground is supplied with a reference potential from the power supply unit, and a plate-shaped plate electrically connected to the frame ground is disposed between the power supply unit and the power supply device.

7. A power supply method comprising supplying power extracted from common-mode noise occurring between the signal ground of a signal circuit and a frame ground having an externally electrically connected terminal.

Images