Power supply device and state monitoring device

Abstract

To provide a power supply device capable of stably securing a power generation amount to a load in the power supply device having a vibration power generator.SOLUTION: The power supply device 10 includes a plurality of vibration power generators 11A to 11C that generate AC power by vibration, a plurality of rectifier circuits 12A to 12C that are respectively connected to the plurality of vibration power generators 11A to 11C, rectify a volts alternating current based on the generated AC power, and outputs a pulsating voltage, a smoothing capacitor 17 that smoothes the pulsating voltage, and an adjustment circuit 30 that adjusts a timing at which the pulsating voltage is outputted from at least one of the plurality of rectifier circuits, and outputs the pulsating voltage to the smoothing capacitor 17.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device having a vibration power generator that converts vibration energy into electrical energy, and a condition monitoring device. [Background technology]

[0002] Patent Document 1 describes a power supply device that generates power by converting vibration energy into electrical energy using a vibration power generator and supplies the generated power to a load. When the load is driven by DC power, the power supply device rectifies the AC power generated by the vibration power generator into a pulsating voltage, which is a DC voltage, using a rectifier circuit, and then smooths it using a smoothing capacitor before outputting it to the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-38268 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the amount of power generated by each vibration generator is small, a single vibration generator may result in an unstable power supply to the load. On the other hand, if the vibration generator is enlarged to increase the amount of power generated, the vibration energy applied to the vibration generator may not be efficiently converted into electrical energy.

[0005] In order to solve the above problems, the present invention aims to provide a power supply device having a vibration generator that converts vibration energy into electrical energy, which can stably ensure the amount of power generated relative to the load, and a condition monitoring device having this power supply device. [Means for solving the problem]

[0006] The power supply device of the present invention includes a plurality of vibration-driven power generators that generate AC power by converting vibration energy into electrical energy, a plurality of rectifier circuits that are connected to the plurality of vibration-driven power generators, respectively, and that rectify an AC voltage based on the AC power generated by the vibration-driven power generators to output a pulsating voltage, a smoothing capacitor that smoothes the pulsating voltage and outputs an output voltage, and an adjustment circuit that adjusts the output timing of the pulsating voltage output from at least one of the plurality of rectifier circuits and outputs it to the smoothing capacitor. [Effects of the Invention]

[0007] In the power supply device according to the present invention, the smoothing capacitor is charged with AC power generated by the plurality of vibration-induced power generators, thereby making it possible to stably ensure the amount of power generation required for the load. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a configuration diagram of a state monitoring device. [Figure 2] FIG. 2 is a diagram illustrating generation of an output voltage by a power supply device. [Figure 3] 4 is a timing chart illustrating the transition of a pulsating voltage and an output voltage. [Figure 4] 10 is a timing chart illustrating the transition of a pulsating voltage and an output voltage as a comparative example. [Figure 5] FIG. 10 is a configuration diagram of a state monitoring device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] A condition monitoring device having a power supply device according to this embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram of the condition monitoring device 1. The condition monitoring device 1 is a device that monitors the state quantities of a structure, which is a monitored object, and is used as part of a monitoring system. In the monitoring system, the presence or absence of cracks in the bridge and the degree of deterioration of the bridge can be determined by periodically acquiring detection signals from the condition monitoring device 1 attached to a bridge, which is an example of a structure, using an external device such as a server.

[0010] The condition monitoring device 1 has a sensor unit 2 and a power supply device 10 that supplies power to the sensor unit 2, which is a load. The sensor unit 2 has a vibration sensor 22 that detects vibrations occurring on the bridge and a communication IF 23 that outputs the detected vibrations to an external device. An input terminal 20 of the sensor unit 2 is connected to an output line 4 of the power supply device 10, and the vibration sensor 22 and the communication IF 23 are driven by an output voltage Vout supplied via the output line 4. A ground terminal 21 of the sensor unit 2 is connected to a ground line 5 that is connected to ground.

[0011] The vibration sensor 22 is a sensor that detects changes in acceleration due to vibration. The communication IF 23 outputs the detection result from the vibration sensor 22 as a detection signal, which is a wireless signal, to an external device. Since the condition monitoring device 1 is configured to transmit the detection signal to the external device via wireless communication using the communication IF 23, wiring required for communication is not required, and the degree of freedom in installation on the bridge can be increased. This makes it easier to install the condition monitoring device 1 in places on the bridge where vibration is likely to occur. The communication IF 23 may output the detection result from the vibration sensor 22 as is, or may convert the detection result from the vibration sensor 22 into some kind of data and output it.

[0012] The power supply device 10 is a device that generates an output voltage Vout required to drive the sensor unit 2, which is a load, and is mainly equipped with a vibration power generator 11, a rectifier circuit 12, a smoothing capacitor 17, and an adjustment circuit 30.

[0013] The vibration power generator 11 generates AC power by converting vibration energy into electrical energy, and outputs an AC voltage Va based on the generated AC power from each of the output terminals 13 and 14. Specifically, in the vibration power generator 11, an internal drive unit is driven by vibration energy, causing relative motion between a magnet and a coil, and the AC voltage Va is generated by electromagnetic induction in response to changes in the magnetic flux linking the coil. Note that the vibration power generator 11 may use electrostatic induction as a power generation method other than electromagnetic induction. Alternatively, AC power may be generated by deformation of a piezoelectric element due to vibration energy.

[0014] The vibration power generator 11 is configured to maximize the amount of power generated when vibration energy of a predetermined resonant frequency is applied to the drive unit. Therefore, as shown in Fig. 2(a), when vibration is applied to the vibration power generator 11, an AC voltage Va having a maximum amplitude is generated at the output terminals 13 and 14 with a period corresponding to the resonant frequency of the drive unit.

[0015] Because the amount of power generated by each vibration-driven power generator 11 is small, it is conceivable to increase the size of the vibration-driven power generator 11 in order to ensure the power required by the condition monitoring device 1. However, simply increasing the size of the vibration-driven power generator 11 increases the mass of the drive unit, reducing the efficiency of converting vibration energy into power, and may actually result in a decrease in the amount of power generated. Therefore, in this embodiment, the power supply device 10 ensures power using the power generated by the three vibration-driven power generators 11, thereby balancing the power required by the sensor unit 2 (the load) and the power generation efficiency of each vibration-driven power generator 11 with respect to vibration. In the following, when the three vibration-driven power generators 11 are described individually, they will be distinguished by adding the suffixes "A," "B," and "C." The same applies to the rectifier circuits 12 connected to each of the vibration-driven power generators 11A to 11C.

[0016] Output terminals 13, 14 of the vibration power generators 11A to 11C are connected to rectifier circuits 12A to 12C, respectively. The rectifier circuits 12A to 12C are circuits that rectify the AC voltage Va to generate and output a pulsating voltage Vp, which is a DC voltage. Specifically, the rectifier circuits 12A to 12C are diode bridge circuits that full-wave rectify the AC voltage Va, and are configured by connecting four diodes D1, D2, D3, and D4 in a bridge configuration.

[0017] The positive voltage of the AC voltage Va output from the positive output terminal 13 of the vibration power generators 11A to 11C is output as is from the output terminal 15 via the diodes D1 to D4. On the other hand, the negative voltage of the AC voltage Va output from the negative output terminal 14 is inverted in polarity by the diodes D1 to D4 and then output from the output terminal 15. As a result, a pulsating voltage Vp is output from the output terminal 15 of the rectifier circuits 12A to 12C, as shown in FIG. 2(b). Note that the rectifier circuits 12A to 12C may be circuits that perform half-wave rectification by outputting only the positive voltage of the AC voltage Va from the output terminal 15.

[0018] The output terminals 15 of the rectifier circuits 12A to 12C are connected in parallel to the output line 4 connected to the input terminal 20 of the sensor unit 2, and output a pulsating voltage Vp to the output line 4. The ground terminals 16 of the rectifier circuits 12A to 12C are connected in parallel to the ground line 5 connected to the ground terminal 21 of the sensor unit 2.

[0019] A smoothing capacitor 17 is connected between the output line 4 and the ground line 5. The smoothing capacitor 17 is, for example, a ceramic capacitor, and contributes to stabilizing the power supply. The smoothing capacitor 17 smoothes the pulsating voltage Vp by repeatedly charging and discharging in accordance with the pulsating voltage Vp applied to the output line 4 and the power consumption of the sensor unit 2, which is the load, and outputs the smoothed voltage as the output voltage Vout. Specifically, as shown in FIG. 2(c), the smoothing capacitor 17 repeatedly increases its voltage during the charging period and decreases its voltage during the discharging period, causing a ripple voltage Rv, which is an AC component, to be generated in the output voltage Vout. In this embodiment, a rectifier circuit 12 is provided between the smoothing capacitor 17 and the vibration power generator 11.

[0020] In the condition monitoring device 1 configured as described above, with each of the vibration power generators 11A-11C attached to a bridge, the vibration sensor 22 of the sensor unit 2 monitors vibrations acting on the bridge. When vibrations occur on the bridge, the drive units of each of the vibration power generators 11A-11C are driven to generate AC power through electromagnetic induction. The rectifier circuits 12A-12C generate a pulsating voltage Vp by full-wave rectifying an AC voltage Va corresponding to the AC power, and this pulsating voltage Vp charges the smoothing capacitor 17.

[0021] In the condition monitoring device 1, the AC voltages supplied from the plurality of vibration-driven power generators 11A to 11C are smoothed by the rectifier circuits 12A to 12C to charge the smoothing capacitor 17 in a stable manner. At this time, differences in the output timing of the pulsating voltage Vp from the rectifier circuits 12A to 12C may cause an excessive ripple voltage Rv to occur in the output voltage Vout charged to the smoothing capacitor 17. Differences in the output timing of the pulsating voltage Vp are caused by factors such as a shift in the phase of the vibration applied to the vibration-driven power generators 11A to 11C, differences in the resonance frequencies of the drive units in the vibration-driven power generators 11A to 11C, and differences in the wiring impedance between the vibration-driven power generators 11A to 11C and the rectifier circuits 12A to 12C.

[0022] If there is a large interval between the application of the pulsating voltage Vp to the smoothing capacitor 17 and the application of the next pulsating voltage Vp, the discharge period of the smoothing capacitor 17 becomes longer, leading to an increase in the ripple voltage Rv. As a result, when the next pulsating voltage Vp is applied after the discharge period of the smoothing capacitor 17, an inrush current flows through the smoothing capacitor 17, which may cause deterioration of the smoothing capacitor 17.

[0023] Therefore, in this embodiment, as shown in FIG. 1 , an adjustment circuit 30 is provided on the output line 4 between the output terminal 15 of the rectifier circuit 12A and the node N of the smoothing capacitor 17 to adjust the output timing of the pulsating voltage Vp1. In this embodiment, the adjustment circuit 30 is an RC circuit configured with passive elements, such as resistors and capacitors. This makes it possible to delay the output timing of the pulsating voltage Vp1 output from the rectifier circuit 12A to the smoothing capacitor 17, thereby achieving adjustment of the output timing of the pulsating voltage Vp1. By configuring the adjustment circuit 30 with passive elements, such as resistors and capacitors, the power consumption of the adjustment circuit 30 can be reduced compared to configuring it with active elements, such as transistors, and the AC power generated by the vibration-induced power generator 11A can be effectively utilized to supply power to the sensor unit 2, which is the load.

[0024] Fig. 3(a) shows the pulsating voltage Vp1 whose output timing is adjusted from the adjustment circuit 30. Fig. 3(b) shows the pulsating voltage Vp2 output from the rectifier circuit 12B, and Fig. 3(c) shows the pulsating voltage Vp3 output from the rectifier circuit 12C. Fig. 3(d) shows the output voltage Vout charged to the smoothing capacitor 17. Figs. 4(a) to 4(d) show, as a comparative example, the transition of the waveforms of each voltage when the output timing of the pulsating voltage Vp1 is not adjusted by the adjustment circuit 30.

[0025] 3 and 4, the periods during which the pulsating voltages Vp1 to Vp3 from the rectifier circuits 12A to 12C are output to the smoothing capacitor 17 do not overlap. When the output periods of the pulsating voltages Vp1 to Vp3 overlap, smoothing by the smoothing capacitor 17 prevents excessive ripple voltage Rv from occurring in the output voltage Vout.

[0026] 4(a), in the comparative example, the output timing of the pulsating voltage Vp1 from the rectifier circuit 12A is not adjusted, and the period from when the rectifier circuit 12A stops outputting the pulsating voltage Vp1 at time t11 to when the rectifier circuit 12B outputs the pulsating voltage Vp2 at time t12 is long. As a result, the discharge period of the smoothing capacitor 17 shown from time t11 to t12 is long, and an excessive ripple voltage Rv is generated in the output voltage Vout shown in FIG. 4(d) compared to the case shown in FIG. 3(d).

[0027] In contrast, in this embodiment, as shown in FIG. 3(a), the output timing of the pulsating voltage Vp1 output from the rectifier circuit 12A is delayed by the adjustment circuit 30, which is an RC circuit, by a delay time Dt relative to the waveform indicated by the dashed line. Therefore, the period from when the rectifier circuit 12A stops outputting the pulsating voltage Vp1 at time t1 to when the rectifier circuit 12B outputs the pulsating voltage Vp2 at time t2 is shortened. This shortens the discharge period of the smoothing capacitor 17, shown from time t1 to t2, compared to the discharge period (t11 to t12) shown in the comparative example of FIG. 4(d), thereby suppressing an increase in the ripple voltage Rv in the output voltage Vout (FIG. 3(d)). By suppressing the generation of excessive ripple voltage Rv in the smoothing capacitor 17, the generation of an inrush current when switching from the discharge period to the charge period is suppressed, thereby suppressing deterioration of the smoothing capacitor 17.

[0028] In the example shown in Figures 3 and 4, the period from when the rectifier circuit 12B stops outputting the pulsating voltage Vp2 until when the rectifier circuit 12C outputs the pulsating voltage Vp3 as shown in Figures 3(c) and 4(c) is short, and no excessive ripple voltage Rv occurs in the output voltage Vout.

[0029] The present embodiment described above can achieve the following effects. The power supply device 10 rectifies an AC voltage Va based on AC power generated by each of the vibration-induced power generators 11A to 11C using rectifier circuits 12A to 12C, and outputs the rectified voltage as a pulsating voltage Vp to a smoothing capacitor 17. The adjustment circuit 30 adjusts the output timing of the pulsating voltage Vp1 output from the rectifier circuit 12A, thereby preventing an excessive ripple voltage Rv from occurring in the output voltage Vout. As a result, the power supply device 10 charges the smoothing capacitor 17 with AC power generated by the multiple vibration-induced power generators 11A to 11C, thereby ensuring a stable supply of power to the sensor unit 2, which is a load. Furthermore, the power supply device 10 can prevent an inrush current from flowing through the smoothing capacitor 17 due to an increase in the ripple voltage Rv, thereby preventing deterioration of the smoothing capacitor 17.

[0030] By configuring the adjustment circuit 30 using passive elements such as resistors and capacitors, power consumption can be reduced compared to when it is configured using active elements, and the AC power generated by the vibration generator 11A can be effectively utilized to supply power to the sensor unit 2.

[0031] The vibration-driven power generators 11A-11C generate AC power through electromagnetic induction by moving a magnet and a coil relative to each other when a drive unit is driven by vibration energy. The power supply device 10 generates the power required for the sensor unit 2 using the AC power generated by the three vibration-driven power generators 11A-11C. This makes it possible to balance the power required for the sensor unit 2 with the power generation efficiency of each of the vibration-driven power generators 11A-11C in response to vibration, even in the vibration-driven power generators 11A-11C that generate AC power by driving a drive unit using vibration energy, and thus allows for a stable supply of the power required for the sensor unit 2.

[0032] The condition monitoring device 1 has a vibration sensor 22 that is driven based on the output voltage Vout smoothed by the smoothing capacitor 17. This eliminates the need for an external power source such as a storage battery in the condition monitoring device 1, thereby suppressing an increase in the running costs of the condition monitoring device 1.

[0033] The vibration power generators 11A-11C of the condition monitoring device 1 are attached to a bridge, which is a structure, and monitor environmental vibrations acting on the bridge as a state quantity. Because the vibrations occurring on the bridge are environmental vibrations, a phase shift is likely to occur in the vibrations acting on each of the vibration power generators 11A-11C. Therefore, even in the condition monitoring device 1 that monitors environmental vibrations, by adjusting the output timing of the pulsating voltages Vp1-Vp3 output from each of the rectifier circuits 12A-12C, it is possible to prevent excessive ripple voltage Rv from occurring in the output voltage Vout.

[0034] (Other embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to this and various modifications are possible without departing from the spirit of the present invention. For example, the adjustment circuit 30 may advance the output timing of the pulsating voltage Vp2 output from the rectifier circuit 12B to shorten the period from when the pulsating voltage Vp1 stops being output until the pulsating voltage Vp2 is output. In this case, the adjustment circuit 30 is configured as an RL circuit made up of passive elements, such as resistors and inductors, and is connected between the output terminal 15 of the rectifier circuit 12B and the node N of the smoothing capacitor 17. In this way, the adjustment circuit 30, which is an RL circuit, can adjust the output timing of the pulsating voltage Vp2 by advancing the output timing of the pulsating voltage Vp2 to the smoothing capacitor 17 within a specific frequency range.

[0035] The number of adjustment circuits 30 included in the power supply device 10 is not limited to one, and may be two or more. FIG. 5 is a configuration diagram of a condition monitoring device 1 according to a modified example, which includes a sensor unit 2 and a power supply device 10, similar to the first embodiment. However, unlike the first embodiment, the power supply device 10 according to the modified example has adjustment circuits 30 and 31 connected to the output terminals 15 of two rectifier circuits 12A and 12B. The power supply device 10 suppresses excessive ripple voltage Rv from occurring in the output voltage Vout by adjusting the output timing of each of the pulsating voltages Vp1 and Vp2 output from the rectifier circuits 12A and 12B using the adjustment circuits 30 and 31. In this modified example, the two adjustment circuits 30 and 31 may be RC circuits or RL circuits depending on the output timing of the pulsating voltages Vp1 and Vp2 to be adjusted.

[0036] The sensor included in the condition monitoring device 1 is not limited to the vibration sensor 22. For example, the condition monitoring device 1 may include in the sensor unit 2 a sensor that detects the amount of displacement or strain occurring in the bridge.

[0037] The object to be monitored by the condition monitoring device 1 is not limited to a bridge, but may be a structure other than a bridge, such as a dam, a building, or even an embankment. In this case, the condition monitoring device 1 may be configured to transmit the state quantity of the structure detected by the sensor to an external device via the communication IF 23.

[0038] The condition monitoring device 1 may be a device that is attached to a vehicle such as a railway vehicle or construction machine, and monitors the state quantities occurring in the vehicle. Specifically, the vibration power generators 11A-11C of the condition monitoring device 1 are attached to positions on the vehicle where vibrations occur, and generate AC power using vibration energy obtained from the vehicle. In this case, the sensor unit 2 may be equipped with a sensor that detects vibrations and accelerations occurring in the vehicle, and may be configured to transmit the monitoring results to an external device.

[0039] The number of vibration power generators 11 included in the state monitoring device 1 is not limited to three, and may be, for example, four or more vibration power generators 11. [Explanation of symbols]

[0040] 1...condition monitoring device, 2...sensor unit, 10...power supply device, 11...vibration generator, 12...rectifier circuit, 17...smoothing capacitor, 30, 31...regulation circuit, Rv...ripple voltage, Va...AC voltage, Vout...output voltage, Vp...pulsating voltage.

Claims

1. a plurality of vibration power generators that generate AC power by converting vibration energy into electrical energy; a plurality of rectifier circuits connected to the plurality of vibration-driven power generators, respectively, for rectifying AC voltages based on AC power generated by the vibration-driven power generators and outputting pulsating voltages; a smoothing capacitor that smoothes the pulsating voltage and outputs an output voltage; an adjustment circuit that adjusts the output timing of the pulsating voltage output from at least one of the plurality of rectifier circuits and outputs the pulsating voltage to the smoothing capacitor.

2. 2. The power supply device according to claim 1, wherein the adjustment circuit is configured with a resistor and a capacitor or a resistor and an inductor.

3. 3. The power supply device according to claim 1, wherein the vibration power generator generates AC power by electromagnetic induction by causing relative movement between the magnet and the coil when a drive unit is driven in response to vibration.

4. a plurality of vibration power generators that generate AC power by converting vibration energy into electrical energy; a plurality of rectifier circuits connected to the plurality of vibration-driven power generators, respectively, for rectifying AC voltages based on AC power generated by the vibration-driven power generators and outputting pulsating voltages; a smoothing capacitor that smoothes the pulsating voltage and outputs an output voltage; an adjustment circuit that adjusts the output timing of the pulsating voltage output from at least one of the plurality of rectifier circuits and outputs the pulsating voltage to the smoothing capacitor; a sensor that is driven based on the output voltage output from the smoothing capacitor and monitors a state quantity of an object to be monitored.

5. 5. The condition monitoring device according to claim 4, wherein each of the plurality of vibration power generators is attached to a structure that is a monitored object, and the sensor monitors a state quantity occurring in the structure.

6. 5. The state monitoring device according to claim 4, wherein each of the plurality of vibration power generators is attached to a vehicle that is an object to be monitored, and the sensor monitors a state quantity occurring in the vehicle.

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