Power supply system

Abstract

This optical node (20) comprises: a photoelectric conversion circuit (22) that receives power-supplying light and converts the same into electric power; a capacitor (C) that is charged by the electric power; a derivation unit (31) that derives, as a function of a prescribed charging-start voltage (VL), a charging time period (ΔT) required in order for a capacitor voltage (Vc) to reach a charging-finish voltage (VH) from said charging-start voltage (VL); a calculation unit (32) that calculates a charging-finish voltage (VH1) that minimizes the charging time period (ΔT) on the basis of said function and a relational expression between the charging-start voltage (VL) and the charging-finish voltage (VH); and a setting unit (33) that sets the time at which the capacitor voltage (Vc) reaches the charging-finish voltage (VH1) calculated by the calculation unit (32) as the time at which the capacitor (C) starts supplying power.

Description

Power supply system

[0001] The present disclosure relates to a power supply system that supplies power from a light source to an optical node.

[0002] In Non-Patent Document 1, an optical power supply signal (hereinafter referred to as "power supply light") for supplying power to an optical node installed at a remote location via an optical fiber network is transmitted from a light source for optical power supply mounted on an in-house optical node installed in a communication building or the like, and a capacitor mounted on the optical node is charged. An optical fiber power supply system (also referred to as a POF (Power Over Fiber) system) is disclosed. In the optical node, the power charged in the capacitor can be used to drive the devices mounted on the optical node. Further, data on the charging voltage of the capacitor can be fed back to the in-house optical node.

[0003] In the POF system, the power supply light output from the light source is received by the optical node. In the optical node, the received power supply light is photoelectrically converted by a photoelectric conversion circuit and the capacitor is charged. The optical node starts driving the device when charging of the capacitor is started and the capacitor voltage reaches a predetermined charging end voltage VH. When the driving of the device ends, the optical node starts charging the capacitor again with the power supply light from this point. The voltage of the capacitor at this time is taken as the charging start voltage VL.

[0004] That is, in the optical node, the driving of the device is started when the capacitor voltage reaches the charging end voltage VH, and when the driving of the device ends, the charging of the capacitor is started. The optical node repeats the operation of driving the device again when the capacitor voltage rises from the charging start voltage VL to the charging end voltage VH. Therefore, the time required for the capacitor voltage to change from the charging start voltage VL to the charging end voltage VH (this is referred to as the charging time ΔT) becomes the interval time of device use.

[0005] IEICE Society Conference b-8-3, 2022, “Study on Remote Operation and Management / Maintenance Functions in Remote Optical Path Switching Nodes” OFC 2024 Th2A.35 “Estimation of Energy Storage Status in Power Supply System Using Power over Fiber for Outdoor Environment”

[0006] To shorten the interval between device usage on optical nodes, it is desirable to reduce the charging time ΔT. Furthermore, in POF systems using optical cables, from a safety standpoint, there are limitations on the power (dBm) of the powered optical energy that can be transmitted using the optical fiber cable, making it impossible to increase the power of the powered optical energy above a certain level. Moreover, the power consumption of devices mounted on optical nodes is often fixed, making it difficult to reduce the power consumption of these devices.

[0007] Therefore, under the condition that the power of the power-supplying light received by the photoelectric conversion circuit (hereinafter referred to as "received light power") and the power consumption of the device are constant, it is desirable to calculate the shortest charging time ΔT and start driving the device at the charging termination voltage VH corresponding to this charging time ΔT. Non-patent document 2 proposes a theoretical formula that shows the time change (dVc / dt) of the capacitor voltage Vc when charging a capacitor mounted on an optical node in a POF system.

[0008] However, Non-Patent Document 2 does not mention the relationship between the power consumption of the device mounted on the optical node, the charging time ΔT, and the received light power. Therefore, there was a problem in that it was difficult to calculate the charging termination voltage VH (device driving voltage) that minimizes the charging time ΔT, when the received light power of the power supply light received by the photoelectric conversion circuit and the power consumption of the device mounted on the optical node were determined.

[0009] This disclosure is made in view of the above circumstances, and its purpose is to provide a power supply system that can calculate a charging termination voltage that minimizes the charging time of a capacitor, when the light received by the power supply and the power consumption of the device are determined.

[0010] A power supply system according to one aspect of the present disclosure includes a light source that outputs power supply light and an optical node that receives the power supply light, wherein the optical node includes a photoelectric conversion circuit that receives the power supply light and converts it into power, a capacitor that charges the power, a derivation unit that derives the charging time required for the charging voltage of the capacitor to reach a predetermined charging end voltage from a predetermined charging start voltage as a function of the charging start voltage, a calculation unit that calculates the charging end voltage that minimizes the charging time based on the function and a relationship between the charging start voltage and the charging end voltage, and a setting unit that sets the time when the charging voltage of the capacitor reaches the charging end voltage calculated by the calculation unit as the start time for power supply by the capacitor.

[0011] According to this disclosure, when the received light power from the supplied light and the power consumption of the device are determined, it becomes possible to calculate the charging termination voltage that minimizes the charging time of the capacitor.

[0012] Figure 1 is a schematic diagram of the power supply system according to the embodiment. Figure 2 is a block diagram showing the detailed configuration of the optical node. Figure 3 is a circuit model of the photoelectric conversion circuit, control circuit, and charging circuit mounted on the optical node. Figure 4 is a graph showing the change in capacitor voltage Vc with respect to charging time. Figure 5 is an explanatory diagram showing each parameter of the circuit model shown in Figure 3. Figure 6 is an explanatory diagram showing the setting values ​​of each parameter used in the theoretical formula shown in equation (2). Figure 7 is a graph showing the relationship between charging time and capacitor voltage Vc. Figure 8 is a graph showing the relationship between the charging start voltage VL and charging time ΔT, and the relationship between the charging start voltage VL and charging end voltage VH. Figure 9 is a flowchart showing the processing operation of the power supply system according to the embodiment. Figure 10 is a block diagram showing the hardware configuration of this embodiment.

[0013] Embodiments will be described below with reference to the drawings. Figure 1 is a schematic diagram of the power supply system 100 according to the embodiment. As shown in Figure 1, the power supply system 100 according to this embodiment includes an in-house optical node 10 (another optical node) and an optical node 20. The in-house optical node 10 and the optical node 20 are connected by an optical fiber 5. The distance of the optical fiber 5 laid between the in-house optical node 10 and the optical node 20 is L [km].

[0014] The in-house optical node 10 comprises a light source 1, an optical circulator 2, an optical receiver 3, and a controller 4.

[0015] Light source 1 outputs power supply light. The power supply light output from light source 1 is introduced into optical fiber 5 via optical circulator 2 and transmitted to optical node 20.

[0016] The optical receiver 3 receives the optical signals transmitted from the optical node 20 and separated by the optical circulator 2.

[0017] The controller 4 controls the output of the light source 1 based on the control data contained in the optical signal received by the optical receiver 3.

[0018] The optical node 20 comprises a remote control board 6 and a plurality of devices 7 (7-1 to 7-n). Device 7 has a function, for example, to perform core switching of the optical fiber 5.

[0019] Figure 2 is a block diagram showing the specific configuration of the remote control board 6. As shown in Figure 2, the remote control board 6 includes a communication device 21, a photoelectric conversion circuit 22, a charging circuit 23, and a control circuit 24. Figure 3 is a circuit model of the photoelectric conversion circuit 22, the charging circuit 23, and the control circuit 24 shown in Figure 2.

[0020] The communication device 21 performs optical communication with the in-house optical node 10 shown in Figure 1 via the optical fiber 5. Specifically, the communication device 21 transmits and receives control signals with the in-house optical node 10. The communication device 21 receives control signals that control the operation of the device transmitted from the in-house optical node 10 and outputs the received control signals to the control circuit 24. The communication device 21 transmits data (capacitor voltage Vc, described later) of the charging voltage of the capacitor C (see Figure 3) mounted on the charging circuit 23 to the in-house optical node 10.

[0021] The photoelectric conversion circuit 22 receives the power supply light transmitted from the light source 1 of the in-house optical node 10, converts this power supply light into photoelectric energy, and supplies the generated power to the charging circuit 23. As shown in Figure 3, the photoelectric conversion circuit 22 is equipped with a photodiode PD1. The two terminals of the photodiode PD1 are connected to the control circuit 24 and the charging circuit 23.

[0022] The charging circuit 23 includes resistors RESR and Rleak, and a capacitor C (see Figure 3), and charges the capacitor C with the power generated by the photodiode PD1. Hereinafter, the voltage charged to the capacitor C will be referred to as the "capacitor voltage Vc".

[0023] The control circuit 24 includes a derivation unit 31, a calculation unit 32, a setting unit 33, and a drive unit 34. The control circuit 24 can be configured, for example, with an MPU (Micro Processing Unit).

[0024] The control circuit 24 supplies power to each device 7 shown in Figure 1 to drive each device 7 when the capacitor voltage Vc being charged to the capacitor C in the charging circuit 23 reaches a predetermined charging termination voltage VH. The charging termination voltage VH is a voltage slightly lower than the saturation voltage of the capacitor C and is a voltage that can supply enough power to drive the devices 7. Furthermore, once the driving of each device 7 is complete, the control circuit 24 controls the system to start charging the capacitor C at that point.

[0025] As shown in Figure 4, the capacitor voltage Vc decreases to the charging start voltage VL when the device 7 is driven after charging has progressed and reached the charging end voltage VH. Subsequently, the capacitor voltage Vc gradually increases as charging begins, and when it reaches the charging end voltage VH again, the device 7 is driven, and this operation is repeated. Therefore, the capacitor voltage Vc changes periodically as shown in Figure 4. The control circuit 24 sets the capacitor voltage Vc (charging end voltage VH) at the start of driving the device 7 so that the interval time between device usage, i.e., the charging time ΔT shown in Figure 4, is shortened.

[0026] The derivation unit 31 shown in Figure 2 calculates the charging termination voltage VH and the charging start voltage VL when driving each device 7 (see Figure 1) with the power charged in capacitor C. The derivation unit 31 starts charging capacitor C when the capacitor voltage Vc is at the charging start voltage VL, calculates the elapsed time (charging time ΔT) until the charging termination voltage VH is reached, and derives a function showing the relationship between the charging start voltage VL and the charging time ΔT. This will be explained in detail below.

[0027] Non-patent document 2, mentioned above, shows the following equation (1) for calculating the current I output from the photoelectric conversion circuit 22.

[0028]

[0029] In equation (1), e is the elementary charge (electron charge), V is the voltage of the photodiode PD1, n is the ideal coefficient of the diode D1, k is the Boltzmann constant, T is the temperature of the photodiode PD1 (calculated at 25°C, 298K absolute temperature in this embodiment), η is the ideal efficiency of the photodiode PD1, P is the light-receiving power (dBm) of the photodiode PD1, λ is the wavelength of light, h is Planck's constant, and c is the speed of light in a vacuum.

[0030] Non-patent document 2 further presents the following equation (2) as a theoretical formula showing the time change (dVc / dt) of the capacitor voltage Vc in the circuit model shown in Figure 3.

[0031]

[0032] The parameters in equation (2) are as shown in Figure 5. Furthermore, by substituting the values ​​shown in Figure 6 into the parameters in equation (2), the curve s1 shown in Figure 7 is obtained.

[0033] That is, under the condition that the power consumption E of each device 7 is constant, a curve s1 is obtained that shows the relationship between the charging time of capacitor C and the capacitor voltage Vc when the light received power (dBm) received by the photodiode PD1 of the photoelectric conversion circuit 22 and the capacitance of capacitor C are set to arbitrary values.

[0034] The curve s1 shown in Figure 7 illustrates the relationship between the charging time and the capacitor voltage Vc, when the light-receiving power of the photodiode PD1 is +7 [dBm], the capacitance of capacitor C is 0.49 [F], and the power consumption of device 7 is 0.3 [J].

[0035] Here, the capacitor voltage Vc at the start of operation of device 7 is denoted as the charging termination voltage VH, and the capacitor voltage Vc at the end of operation is denoted as the charging start voltage VL. The capacitance of capacitor C is also denoted by the same symbol "C". In this case, the power consumption E can be expressed by the following equation (3).

[0036] E=(1 / 2)・C(VH ２ -VL ２ ) ... (3) Also, if we let Vbottom be the voltage at which the control circuit 24 starts up and Vsatu be the voltage when the capacitor voltage Vc is saturated, then the following equation (4) holds true.

[0037] Vbottom < VL < VH < Vsatu ... (4) The derivation unit 31 calculates a combination of voltages VL and VH that satisfies the relationship shown in equation (4). For example, if a voltage VL greater than voltage Vbottom is arbitrarily set, and voltage VH is calculated from this voltage VL using equation (3) above, and if this voltage VH is less than voltage Vsatu, then the combination of voltages VL and VH satisfies equation (4).

[0038] The derivation unit 31 calculates the charging time ΔT from the difference (tVL to tVH in FIG. 7) between the charging elapsed time (tVL) when the voltage VL is substituted into the curve s1 shown in FIG. 7 and the charging elapsed time (tVH) when the voltage VH forming a combination with the voltage VL is substituted. That is, the elapsed time from when the capacitor voltage Vc reaches the charging start voltage VL to when it reaches the charging end voltage VH is calculated as the charging time ΔT.

[0039] The derivation unit 31 calculates the charging time ΔT for each combination of a plurality of voltages VL and VH. As a result, the charging time ΔT becomes a function of the voltage VL. That is, when the charging time ΔT with respect to the voltage VL is indicated as "ΔT(VL)", it can be expressed by the following equation (5).

[0040] ΔT(VL) = tVH - tVL ··· (5) In equation (5), "tVL" indicates the time when the capacitor voltage Vc becomes the voltage VL, and "tVH" indicates the time when the capacitor voltage Vc reaches the voltage VH. That is, when the voltage VL is determined, the charging time ΔT is uniquely determined. Also, based on the above-mentioned equation (3), when the voltage VL is determined, the voltage VH is uniquely determined.

[0041] As a result, as shown in FIG. 8, a curve s2 showing the relationship between the voltage VL and the charging time ΔT and a curve s3 showing the relationship between the voltage VL and the voltage VH are obtained. In FIG. 8, the curve s2 corresponds to the left scale, and the curve s3 corresponds to the right scale.

[0042] The derivation unit 31 derives the charging time ΔT required for the charging voltage (capacitor voltage Vc) of the capacitor C to reach the charging end voltage VH from the charging start voltage VL as a function of the charging start voltage VL. The derivation unit 31 derives the above-mentioned function under the condition that the received light power received by the photodiode PD1 of the photoelectric conversion circuit 22 and the power consumption of the device 7 are constant.

[0043] The calculation unit 32 shown in FIG. 2 calculates a voltage VL that minimizes the charging time ΔT. Specifically, the calculation unit 32 calculates the voltage VL at which the charging time ΔT is minimized on the curve s2 shown in FIG. 8, and the charging time ΔT at this time. By the calculation unit 32, for example, a voltage VL = 2.64 [V] that minimizes the charging time ΔT, and a charging time ΔT = 207.5 [sec] at this time are obtained.

[0044] The calculation unit 32 calculates the charging end voltage VH corresponding to the charging start voltage VL by associating the voltage VL calculated based on the curve s2 with the curve s3 shown in FIG. 8. That is, the calculation unit 32 calculates a combination of voltages VL and VH (let these be voltage VL1 and VH1, respectively) at which the charging time ΔT is minimized in order to shorten the interval time of device use. In the example shown in FIG. 8, VL1 = 2.64 [V] and VH1 = 2.86 [V]. The calculation unit 32 calculates the charging end voltage VH1 that minimizes the charging time ΔT based on the function showing the relationship between the voltage VL and the charging time ΔT and the relational expression between the charging start voltage VL and the charging end voltage VH.

[0045] The setting unit 33 sets the time when the capacitor voltage Vc reaches the voltage VH1 calculated by the calculation unit 32 as the drive start time of each device 7. That is, the setting unit 33 sets the time when the charging voltage of the capacitor C (capacitor voltage Vc) reaches the charging end voltage VH1 calculated by the calculation unit 32 as the start time of power supply from the capacitor C to the device 7.

[0046] The drive unit 34 performs control to supply driving power from the capacitor C to each device 7 at the drive start time set by the setting unit 33. The optical node 20 includes at least one device 7, and the drive unit 34 supplies the power charged in the capacitor C to the device 7 at the start time of power supply.

[0047] Next, the operation of the power supply system 100 configured as described above will be described with reference to the flowchart shown in FIG. 9. First, in step S11 of FIG. 9, the derivation unit 31 creates a graph showing the relationship between the charging elapsed time of the capacitor C and the capacitor voltage Vc based on the above-described equations (1) and (2). As a result, for example, the curve s1 shown in FIG. 7 is obtained.

[0048] In step S12, the derivation unit 31 sets a combination of the charging start voltage VL and the charging end voltage VH. Specifically, it calculates a combination of voltages VL and VH that satisfies the relationship shown in equation (4) above. For example, if a voltage VL greater than voltage Vbottom is arbitrarily set, and voltage VH is calculated from this voltage VL using equation (3) above, and if this voltage VH is less than voltage Vsatu, then the combination of voltages VL and VH satisfies equation (4).

[0049] In step S13, the derivation unit 31 substitutes the VL and VH values ​​for each combination into the curve s1 in Figure 7 to calculate the charging time ΔT for each combination.

[0050] In step S14, the derivation unit 31 creates a graph showing the relationship between voltage VL and charging time ΔT, i.e., the curve s2 shown in Figure 8, based on the charging time ΔT calculated in the process of step S13.

[0051] In step S15, the calculation unit 32 calculates the minimum value ΔTmin of the charging time ΔT based on curve s2. For example, in the curve s2 shown in Figure 8, the minimum value ΔTmin = 207.5 [sec]. The voltage VL at this time is 2.64 [V].

[0052] In step S16, the setting unit 33 calculates the voltages VL and VH corresponding to the minimum value ΔTmin and sets them to voltages VL1 and VH1, respectively.

[0053] In step S17, the setting unit 33 sets the voltage VH1 to the capacitor voltage Vc that starts driving the device 7.

[0054] In this way, the charging termination voltage VH1 that minimizes the charging time ΔT can be set. When the capacitor voltage Vc reaches voltage VH1, the drive unit 34 supplies the power stored in capacitor C to each device 7, thereby enabling each device 7 to be driven at short intervals. In other words, the interval time between device usage can be shortened.

[0055] As described above, the power supply system 100 according to this embodiment includes a light source 1 that outputs power supply light and an optical node 20 that receives the power supply light. The optical node 20 includes a photoelectric conversion circuit 22 that receives the power supply light and converts it into power, a capacitor C that charges the power, a derivation unit 31 that derives the charging time ΔT required for the charging voltage (capacitor voltage Vc) of the capacitor C to reach the charging end voltage VH from a predetermined charging start voltage VL as a function of the charging start voltage VL, a calculation unit 32 that calculates the charging end voltage VH1 that minimizes the charging time ΔT based on the above function and the relationship between the charging start voltage VL and the charging end voltage VH, and a setting unit 33 that sets the time when the capacitor voltage Vc reaches the charging end voltage VH1 calculated by the calculation unit 32 as the start time for power supply by the capacitor C.

[0056] In the power supply system 100 according to this embodiment, when the power consumption of each device 7 and the light receiving power of the power supply light are determined, the charging time ΔT required to raise the capacitor voltage Vc from the charging start voltage VL to the charging end voltage VH can be minimized. Therefore, it becomes possible to shorten the interval between device usage.

[0057] In the power supply system 100 according to this embodiment, the drive cycle of the device 7 can be calculated, which enables the smooth design and operation of the POF system. Furthermore, in the in-house optical node 10, it becomes possible to drive each device 7 (7-1 to 7-n) of the optical node 20 installed at a location far from the in-house optical node 10 (for example, at a location L [km] away) at the frequency required by each device 7.

[0058] In the power supply system 100 according to this embodiment, the light source 1 is installed in an in-house optical node (another optical node) that is located away from the optical node 20 and connected by an optical fiber 5, so that the capacitor C mounted on the optical node 20 can be charged remotely.

[0059] In the embodiment described above, an example was given in which the control circuit 24 is mounted on the remote control board 6 shown in Figure 1. However, the control circuit 24 may also be mounted in the controller 4 of the in-house optical node 10. In this case, the in-house optical node 10 may query the optical node 20 for the capacitor voltage Vc. The controller 4 may also be configured to have a function for estimating the capacitor voltage Vc.

[0060] Furthermore, when the capacitor voltage Vc reaches the charging termination voltage VH1 (the charging termination voltage VH at which the charging time ΔT becomes the minimum value ΔTmin), a control signal for operating the device 7 may be transmitted from the in-house optical node 10 to the optical node 20. These control functions may also be implemented as software in the controller 4.

[0061] As shown in Figure 10, the control circuit 24 of the power supply system 100 of this embodiment can use a general-purpose computer system, for example, that includes a CPU (Central Processing Unit, processor) 901, memory 902, storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), communication device 904, input device 905, and output device 906. The memory 902 and storage 903 are storage devices. In this computer system, each function of the control circuit 24 is realized when the CPU 901 executes a predetermined program loaded onto the memory 902.

[0062] The control circuit 24 may be implemented on one computer or on multiple computers. Furthermore, the control circuit 24 may be a virtual machine implemented on a computer.

[0063] The program for the control circuit 24 can be stored on a computer-readable recording medium such as an HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or it can be distributed via a network. A computer-readable recording medium is, for example, a non-transitory recording medium.

[0064] This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence.

[0065] 1 Light source 2 Optical circulator 3 Optical receiver 4 Controller 5 Optical fiber 6 Remote control board 7 (7-1 to 7-n) Devices 10 In-house optical node 20 Optical node 21 Communication device 22 Photoelectric conversion circuit 23 Charging circuit 24 Control circuit 31 Derivation unit 32 Calculation unit 33 Setting unit 34 Drive unit 100 Power supply system C Capacitor VH Charging end voltage VL Charging start voltage ΔT Charging time

Claims

1. A power supply system comprising: a light source that outputs power supply light; and an optical node that receives the power supply light, wherein the optical node includes: a photoelectric conversion circuit that receives the power supply light and converts it into power; a capacitor that charges the power; a derivation unit that derives the charging time required for the charging voltage of the capacitor to reach a predetermined charging end voltage from a predetermined charging start voltage as a function of the charging start voltage; a calculation unit that calculates the charging end voltage that minimizes the charging time based on the function and the relationship between the charging start voltage and the charging end voltage; and a setting unit that sets the time when the charging voltage of the capacitor reaches the charging end voltage calculated by the calculation unit as the start time for power supply by the capacitor.

2. The power supply system according to claim 1, wherein the optical node further comprises a drive unit that supplies power charged in the capacitor to the device at the start time of the power supply.

3. The power supply system according to claim 2, wherein the derivation unit derives the function under the condition that the light received power received by the photoelectric conversion circuit and the power consumption of the device are constant.

4. The power supply system according to claim 1, wherein the light source is installed in another optical node connected to the optical node by an optical fiber.

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