Anomaly detection device

Abstract

To provide an abnormality detection device capable of promptly detecting abnormality in a power supply system having a power supply circuit for supplying current at a predetermined frequency to multiple loads that are connected in parallel electrically by utilizing LC resonance via a capacitor along with the causes of the abnormality.SOLUTION: An abnormality detection device 10 detects abnormality in a power supply system P having multiple track circuits 3 that are connected in parallel electrically, and a power supply circuit 1 that has a capacitor 5 and supplies current at a predetermined frequency to the multiple track circuits 3 via the capacitor 5 by utilizing LC resonance. The abnormality detection device 10 includes: a disconnection detection part 11 for detecting disconnection of the multiple track circuits 3; an eddy current detection part 21 for detecting an eddy current generated within the power supply circuit 1; and an abnormality determination part 41 for determining causes of the abnormality of the power supply system P on the basis of waveform of current flowing to the multiple track circuits 3 when occurrence of an eddy current within the power supply circuit 1 is detected by the eddy current detection part 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abnormality detection device that detects abnormalities in a power supply system that includes a power supply that uses LC resonance to supply a current of a predetermined frequency to a plurality of loads electrically connected in parallel via a capacitor. [Background technology]

[0002] As an example of a power supply system having a power source that uses LC resonance to supply current of a predetermined frequency to a plurality of loads electrically connected in parallel via a capacitor, a power supply system that supplies power to a moving object traveling along a track, as disclosed in Patent Document 1, is known.

[0003] The power supply system disclosed in Patent Document 1 includes a capacitor connected to a power supply line so as to form a resonant circuit together with the power supply line. The resonant frequency of the resonant circuit is set to match the frequency of the current flowing through the power supply line. Patent Document 1 discloses that multiple power supply lines are provided for one power source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-72011 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when a current of a predetermined frequency is supplied to multiple loads using LC resonance, if a disconnection occurs in at least one of the multiple loads, the inductance of the load changes, but the capacitance of the capacitor does not change. Therefore, a current of a frequency different from the predetermined frequency flows into the load. When a current of a frequency different from the predetermined frequency flows into the load, the current flowing through the entire system increases.

[0006] In this way, even if a wire break occurs on the load side, it is detected as an overcurrent in the power supply system, making it difficult to distinguish between an overcurrent caused by a wire break on the load side and an overcurrent caused by some other factor.

[0007] In response to this, it is required to detect an abnormality in the power supply system as early as possible and also to quickly detect the cause of the abnormality in order to shorten the period of shutdown of the power supply system as much as possible.

[0008] An object of the present invention is to provide an abnormality detection device that can detect an abnormality, along with the cause of the abnormality, at an early stage in a power supply system that includes a power supply circuit that uses LC resonance to supply a current of a predetermined frequency to multiple loads electrically connected in parallel via a capacitor. [Means for solving the problem]

[0009] According to one embodiment of the present invention, an abnormality detection device detects an abnormality in a power supply system including a plurality of loads electrically connected in parallel, and a power supply circuit having a capacitor that supplies a current of a predetermined frequency to the plurality of loads via the capacitor using LC resonance. The abnormality detection device includes a disconnection detection unit that detects a disconnection in the plurality of loads, an overcurrent detection unit that detects an overcurrent occurring in the power supply circuit, and an abnormality determination unit that determines the cause of the abnormality in the power supply system based on the waveform of the current flowing through the plurality of loads when the overcurrent detection circuit detects an occurrence of an overcurrent in the power supply circuit (first configuration).

[0010] This allows the disconnection detection unit to detect disconnections in the plurality of loads, and also allows the overcurrent detection unit to detect overcurrents in the power supply circuit.

[0011] When the overcurrent detection unit detects an overcurrent in the power supply circuit, it is possible that the overcurrent in the power supply circuit has been caused by a disconnection in one of the loads. In contrast, in the above-described configuration, the abnormality determination unit can determine whether the disconnection is in one of the loads, i.e., the cause of the abnormality in the power supply system, based on the waveforms of the currents flowing through the loads.

[0012] Therefore, with the above configuration, an abnormality in the power supply system can be detected early, along with the cause of the abnormality.

[0013] In the first configuration, the abnormality detection device further includes a disconnection determination unit that determines whether a disconnection has occurred in the plurality of loads based on the waveforms of the currents flowing through the plurality of loads. The abnormality determination unit determines the cause of the abnormality in the power supply system based on outputs of the overcurrent detection unit and the disconnection determination unit (second configuration).

[0014] This allows the disconnection determination unit to determine whether or not there is a disconnection in the load even if the overcurrent detection unit detects an overcurrent in the power supply circuit. Therefore, with the above configuration, it is possible to detect an abnormality in the power supply system and the cause of the abnormality at an early stage.

[0015] In the second configuration, the abnormality judgment unit judges that a wire breakage abnormality has occurred when the overcurrent detection unit detects an overcurrent occurring in the power supply circuit and the wire breakage judgment unit judges that a wire breakage has occurred in the multiple loads (third configuration).

[0016] This allows the abnormality determination unit to accurately determine whether a disconnection has occurred in a plurality of loads based on the detection results of the overcurrent detection unit and the determination results of the disconnection determination unit, thereby enabling early detection of an abnormality in the power supply system and the cause of the abnormality.

[0017] In the second or third configuration, the disconnection detection unit, the overcurrent detection unit, and the disconnection determination unit are configured by analog circuits (fourth configuration).

[0018] This allows the anomaly detection device to detect disconnections and overcurrents in a power supply system even if it does not have a CPU or the like, and even if an overcurrent is detected in a power supply circuit, it can determine whether the cause is a disconnection in multiple loads. Therefore, the anomaly detection device can be realized at low cost and with a simple configuration.

[0019] In any one of the second to fourth configurations, the internal time constant of the disconnection determination unit is smaller than the internal time constant of the disconnection detection unit (fifth configuration).

[0020] This allows the open circuit determination unit to quickly determine the cause of the overcurrent in the power supply circuit. Therefore, an abnormality in the power supply system, along with the cause of the abnormality, can be detected earlier. Meanwhile, an open circuit detection unit with a large time constant is less susceptible to noise and other factors than an open circuit determination unit, preventing erroneous determination of an open circuit. Therefore, when shutting down the operation of the power supply system, the detection results of the open circuit detection unit are used to prevent system shutdown due to erroneous determination of an open circuit. [Effects of the Invention]

[0021] An abnormality detection device according to one embodiment of the present invention is a device for detecting an abnormality in a power supply system including a power supply circuit that uses LC resonance to supply a current of a predetermined frequency to multiple loads electrically connected in parallel via a capacitor. The abnormality detection device includes a wire break detection unit, an overcurrent detection unit, and an abnormality determination unit that, when the overcurrent detection unit detects an occurrence of an overcurrent in the power supply circuit, determines the cause of the abnormality in the power supply system based on the waveform of the current flowing through the multiple loads.

[0022] This allows the abnormality determination unit to determine the cause of the abnormality even if an overcurrent flows in the power supply circuit due to a wire break in one of the loads, thereby enabling early detection of an abnormality in the power supply system and the cause of the abnormality. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a power supply system having a power supply circuit including an abnormality detection device according to an embodiment and a plurality of track circuits. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of the abnormality detection device. [Figure 3] FIG. 3 is a diagram illustrating an example of a circuit configuration of the disconnection detection unit. [Figure 4] FIG. 4 is a diagram showing an example of a voltage waveform at each part in the disconnection detection part. [Figure 5] FIG. 5 is a diagram illustrating an example of a circuit configuration of the overcurrent detection unit. [Figure 6] FIG. 6 is a diagram showing an example of a voltage waveform at each part in the overcurrent detection part. [Figure 7] FIG. 7 is a diagram illustrating an example of a circuit configuration of the disconnection determination unit. [Figure 8] FIG. 8 is a diagram showing an example of a voltage waveform at each part in the disconnection determination part. [Figure 9] FIG. 9 is a diagram showing a schematic configuration of the abnormality determination unit. [Figure 10] FIG. 10 is a diagram showing the relationship between the output signals from the overcurrent detection unit and the disconnection determination unit, which are input to the abnormality determination unit, and the disconnection abnormality signal and the overcurrent abnormality signal, which are output from the abnormality determination unit. [Figure 11A] FIG. 11A is a diagram schematically showing a change in the internal current when a break occurs in the track circuit when the internal current is small. [Figure 11B] FIG. 11B is a diagram schematically showing a change in the internal current when a break occurs in the track circuit in the case where the internal current is large. [Figure 12]FIG. 12 is a diagram showing a schematic diagram of the relationship between the frequency of the current on the output side of the power supply circuit and the internal current of the power supply circuit. [Figure 13A] FIG. 13A is a diagram schematically showing a change in the internal current when a break occurs in the track circuit when the internal current is small. [Figure 13B] FIG. 13B is a diagram schematically showing a change in the internal current when a break occurs in the track circuit in the case where the internal current is large. [Figure 14] FIG. 14 is a diagram showing the relationship between the operations of the disconnection detection unit, the disconnection determination unit, and the overcurrent detection unit in the abnormality detection device and the determination results. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will not be repeated.

[0025] Fig. 1 is a diagram showing the schematic configuration of a power supply system P having a power supply circuit 1 with an abnormality detection device 10 according to an embodiment of the present invention, and multiple track circuits 3. The power supply circuit 1 is a track power panel that supplies power to multiple track circuits 3 (loads) electrically connected in parallel. The multiple track circuits 3 are circuits that supply power to, for example, mobile objects traveling along a track.

[0026] The power supply circuit 1 may supply power to circuits other than the track circuit. In other words, the power supply system P may have any other configuration as long as it supplies power from the power supply circuit 1 to multiple circuits electrically connected in parallel.

[0027] Specifically, the power supply circuit 1 has a current-fed inverter 2, a capacitor 5, and an input-side inductance 6. On the output side of the power supply circuit 1, a plurality of track circuits 3 are electrically connected in parallel to the current-fed inverter 2. Each of the plurality of track circuits 3 has its own inductance 4.

[0028] The current-fed inverter 2 converts a direct current supplied from a power source (not shown) into an alternating current of a predetermined frequency. The predetermined frequency is the resonant frequency of an LC resonant circuit (described later). The current-fed inverter 2 has the same configuration as a conventional current-fed inverter. Therefore, a detailed description of the configuration of the current-fed inverter 2 will be omitted.

[0029] The capacitor 5 is electrically connected in parallel to the current-fed inverter 2. The capacitor 5 forms an LC resonant circuit together with the inductances 4 of the multiple track circuits 3. In this embodiment, the power supply circuit 1 has multiple capacitors 5 electrically connected in parallel. The current-fed inverter 2 adjusts the frequency of the current it outputs to match the resonant frequency of the LC resonant circuit formed by the capacitor 5 and the inductances 4 of the multiple track circuits 3.

[0030] In this way, the power supply circuit 1 supplies current of a predetermined frequency to the plurality of track circuits 3 by utilizing an LC resonant circuit formed by the capacitor 5 and the inductances 4 of the plurality of track circuits 3. In Fig. 1, reference numeral 7 denotes an internal current detector that detects the current inside the power supply circuit 1, and reference numeral 8 denotes an output current detector that detects the output current of the power supply circuit 1.

[0031] The abnormality detection device 10 detects overcurrents occurring inside the power supply circuit 1 and disconnections in the multiple track circuits 3. The abnormality detection device 10 detects overcurrents by detecting the internal current of the power supply circuit 1, and detects disconnections in the track circuits 3 by detecting the currents flowing through the multiple track circuits 3.

[0032] Specifically, the abnormality detection device 10 includes a disconnection detection unit 11, an overcurrent detection unit 21, a disconnection determination unit 31, and an abnormality determination unit 41. FIG.

[0033] The wire break detection unit 11 detects a wire break in each track circuit 3 based on the current flowing through each of the track circuits 3. Specifically, the wire break detection unit 11 detects that a wire break has occurred in a track circuit 3 when the current flowing through that track circuit 3 is smaller than a first current threshold. In other words, the wire break detection unit 11 detects a wire break abnormality in the track circuit 3. The current flowing through the track circuit 3 is the current detected by the output current detector 8.

[0034] The disconnection detection unit 11 is, for example, a circuit including a half-wave rectifier circuit 12 and a comparison circuit 16. Fig. 3 is a diagram showing an example of the circuit configuration of the disconnection detection unit 11. The disconnection detection unit 11 of this embodiment is configured with an analog circuit. Fig. 4 is a diagram showing an example of voltage waveforms at each section (P1 to P5) in the disconnection detection unit 11.

[0035] As shown in FIG. 3, the half-wave rectifier circuit 12 includes a diode 13, a resistor 14, and a capacitor 15. The diode 13 allows current to flow in only one direction. Therefore, the AC voltage at P1 in FIGS. 3 and 4 is rectified by the diode 13 into a half-wave voltage waveform as shown at P2 in FIG. 4. The resistor 14 and the capacitor 15 smooth the voltage waveform. That is, the half-wave voltage waveform shown at P2 in FIG. 4 is converted by the resistor 14 and the capacitor 15 into a substantially DC waveform with reduced ripple voltage as shown at P3 in FIG. 4.

[0036] The comparison circuit 16 has a comparator 17 and a voltage divider circuit 18. The comparator 17 compares the voltage output from the half-wave rectifier circuit 12 with a voltage (first voltage threshold) obtained by the voltage divider circuit 18, and outputs a High signal if the voltage output from the half-wave rectifier circuit 12 is smaller than the first voltage threshold. Note that the configurations of the comparator 17 and the voltage divider circuit 18 are the same as those of conventional devices, and therefore detailed description of the comparator 17 and the voltage divider circuit 18 will be omitted. The first voltage threshold is a voltage threshold corresponding to the above-mentioned first current threshold.

[0037] The voltage output from the half-wave rectifier circuit 12 and the first voltage threshold, which are input to the comparator 17, have the voltage waveforms shown at P4 in Fig. 4. P5 in Fig. 4 is an example of a voltage waveform output from the comparator 17. For ease of explanation, the waveform of the first voltage threshold is shown by a dashed line at P4 in Fig. 4.

[0038] When a break occurs in the track circuit 3, as shown in Figure 4, the AC voltage at position P1 becomes zero, and the voltage at each position from P3 to P4 gradually decreases. After a time tp has elapsed since the break occurred, the voltage at P4 becomes smaller than the first voltage threshold output from the voltage divider circuit 18. Therefore, the comparator 17 outputs a High signal, as shown at P5 in Figure 4.

[0039] Therefore, the disconnection detection unit 11 can detect a disconnection in the track circuit 3.

[0040] The overcurrent detection unit 21 detects an overcurrent based on the current flowing upstream of the power supply circuit 1 relative to the current-fed inverter 2. Specifically, the overcurrent detection unit 21 detects that an overcurrent has occurred in the power supply circuit 1 when the detected current is greater than a second current threshold. The current flowing upstream of the power supply circuit 1 relative to the current-fed inverter 2 is the current detected by the internal current detector 7.

[0041] The overcurrent detection unit 21 is a circuit including, for example, a signal conversion unit 22 and an overcurrent determination unit 27. The overcurrent detection unit 21 of this embodiment is configured with an analog circuit. FIG. 5 is a diagram showing an example of the circuit configuration of the overcurrent detection unit 21. FIG. 6 is a diagram showing an example of the voltage waveforms at each unit (Q1 to Q4) in the overcurrent detection unit 21.

[0042] As shown in Fig. 5, the signal conversion unit 22 includes a resistor 23, a capacitor 24, an operational amplifier 25, and an amplification factor setting circuit 26. The resistor 23 and the capacitor 24 smooth the voltage waveform. That is, the substantially DC voltage waveform having a ripple voltage shown as Q1 in Fig. 6 is converted by the resistor 23 and the capacitor 24 into a substantially DC waveform with the ripple voltage suppressed as shown as Q2 in Fig. 6.

[0043] The operational amplifier 25 and the amplifying resistor circuit 26 function as a signal amplifying circuit that amplifies a signal. The amplifying resistor circuit 26 has multiple resistors electrically connected in series. The operational amplifier 25 receives a voltage having a substantially DC waveform obtained by the resistor 23 and the capacitor 24 and a divided voltage obtained by the amplifying resistor circuit 26, which is the difference between the output voltage of the operational amplifier 25 and the input voltage. As indicated by Q3 in FIG. 6 , the operational amplifier 25 amplifies and outputs the input voltage having a substantially DC waveform. The amplification factor of the voltage output from the operational amplifier 25 can be changed by changing the resistance value of each resistor in the amplifying resistor circuit 26. The overcurrent detection unit 21 does not necessarily have to include the operational amplifier 25 and the amplifying resistor circuit 26.

[0044] The overcurrent determination unit 27 has a comparator 28 and a voltage divider circuit 29. The comparator 28 compares the voltage output from the signal conversion unit 22 with a voltage value (second voltage threshold) obtained by the voltage divider circuit 29, and outputs a High signal if the voltage output from the signal conversion unit 22 is greater than the second voltage threshold. Note that the configurations of the comparator 28 and the voltage divider circuit 29 are the same as those of conventional devices, and therefore detailed description of the comparator 28 and the voltage divider circuit 29 will be omitted. The second voltage threshold is a voltage threshold corresponding to the above-mentioned second current threshold.

[0045] The voltage output from the signal conversion unit 22 and the second voltage threshold, which are input to the comparator 28, have voltage waveforms shown in Q3 of Fig. 6. Q4 of Fig. 6 is an example of a voltage waveform output from the comparator 28. For ease of explanation, the waveform of the second voltage threshold is shown by a dashed line in Q3 of Fig. 6.

[0046] When an overcurrent occurs in the power supply circuit 1, the voltage output from the signal conversion unit 22 becomes greater than the second voltage threshold after a lapse of time tq from the occurrence of the overcurrent, as indicated by Q3 in Fig. 6. Therefore, the comparator 28 outputs a High signal, as indicated by Q4 in Fig. 6.

[0047] Therefore, the overcurrent detection unit 21 can detect the occurrence of an overcurrent in the power supply circuit 1.

[0048] The disconnection determination unit 31 determines a disconnection in each track circuit 3 based on the current flowing through each of the track circuits 3. The determination result of the disconnection determination unit 31 is used for abnormality determination by the abnormality determination unit 41, which will be described later. The current flowing through the track circuit 3 is a current detected by the output current detector 8.

[0049] The disconnection determination unit 31 is a circuit including, for example, a pulse detection unit 32 and a monostable multivibrator 36. The disconnection determination unit 31 of this embodiment is configured with an analog circuit. FIG. 7 is a diagram showing an example of the circuit configuration of the disconnection determination unit 31. FIG. 8 is a diagram showing an example of the voltage waveforms at each unit (S1 to S4) in the disconnection determination unit 31.

[0050] The pulse detection unit 32 has a photocoupler 33, a resistor 34, and a capacitor 35. The photocoupler 33 converts the currents flowing through the plurality of track circuits 3 into pulse waveforms. That is, the sinusoidal voltage waveform shown in S1 of FIG. 8 is converted by the photocoupler 33 into a pulse waveform as shown in S2 of FIG. 8. The configuration of the photocoupler 33 is similar to that of a conventional photocoupler, and therefore a detailed description of the photocoupler 33 will be omitted. Note that the pulse detection unit may have another configuration capable of detecting the currents flowing through the plurality of track circuits 3 as pulses.

[0051] The resistor 34 and the capacitor 35 remove high-frequency noise and the like contained in the pulse-shaped waveform converted by the photocoupler 33. That is, the pulse-shaped voltage waveform containing high-frequency noise and the like shown in S2 of Fig. 8 is converted by the resistor 34 and the capacitor 35 into a substantially rectangular waveform shown in S3 of Fig. 8 from which the high-frequency noise has been removed.

[0052] The monostable multivibrator 36 determines whether or not a pulse is detected by the pulse detection unit 32. Specifically, as shown in S4 of FIG. 8, the monostable multivibrator 36 continuously outputs a low signal when a pulse output from the pulse detection unit 32 is input within a predetermined period, and outputs a high signal when the pulse is no longer input within the predetermined period. The predetermined period is set to a time range that is longer than one period of the pulse in S3 and shorter than the timing of the signal falling edge in the second period of the pulse. The monostable multivibrator 36 has the same configuration as a conventional one, and therefore a detailed description of the monostable multivibrator 36 will be omitted. Note that any configuration other than a monostable multivibrator may be used as long as it can determine whether or not a pulse is detected by the pulse detection unit 32.

[0053] When a break occurs in the track circuit 3, the AC voltage at position S1 becomes zero, and no pulses are input to positions S2 and S3, as shown in Fig. 8. If the time during which no pulses are input continues for the predetermined period (after ts has elapsed since the break occurred), the monostable multivibrator 36 outputs a High signal, as shown at S4 in Fig. 8.

[0054] Therefore, the disconnection determination unit 31 can detect a disconnection in the track circuit 3.

[0055] The internal time constant of the disconnection determination unit 31 is smaller than the internal time constant of the disconnection detection unit 11 (see ts and tp in FIG. 13A). Therefore, if the same voltage waveform is input from the output current detector 8 to the disconnection determination unit 31 and the disconnection detection unit 11 and the track circuit 3 is disconnected and the voltage waveform changes, the disconnection determination unit 31 can determine the disconnection earlier than the disconnection detection unit 11. On the other hand, the disconnection detection unit 11, which has a larger time constant, is less susceptible to the effects of noise and the like than the disconnection determination unit 31, and can therefore prevent erroneous determination of a disconnection.

[0056] The abnormality determination unit 41 uses the result detected by the overcurrent detection unit 21 and the result determined by the disconnection determination unit 31 to determine whether the abnormality occurring in the power supply system P is an overcurrent abnormality occurring inside the power supply circuit 1 or a disconnection abnormality in the track circuit 3. Specifically, when an overcurrent is detected by the overcurrent detection unit 21, if the disconnection determination unit 31 determines that there is a disconnection in the track circuit 3, the abnormality determination unit 41 determines that there is a disconnection abnormality, and if the disconnection determination unit 31 does not determine that there is a disconnection in the track circuit 3, the abnormality determination unit 41 determines that there is an overcurrent abnormality.

[0057] 9 is a diagram showing a schematic configuration of the abnormality determination unit 41. As shown in FIG. 9, the abnormality determination unit 41 has a disconnection abnormality determination unit 42 and an overcurrent abnormality determination unit 46.

[0058] The wire break abnormality determination unit 42 outputs a wire break abnormality signal when the outputs from the overcurrent detection unit 21 and the wire break determination unit 31 are both High signals. Specifically, the wire break abnormality determination unit 42 has an AND circuit 43 that obtains a logical product of the output signals from the overcurrent detection unit 21 and the wire break determination unit 31.

[0059] The overcurrent abnormality determination unit 46 outputs an overcurrent abnormality signal when the output signal from the overcurrent detection unit 21 is a High signal and the output signal from the disconnection determination unit 31 is a Low signal. Specifically, the overcurrent abnormality determination unit 46 has a NOT circuit 47 that outputs the negated value of the output signal from the disconnection determination unit 31, and an AND circuit 48 that obtains a logical AND of the negated value of the output signal from the disconnection determination unit 31 and the output signal from the overcurrent detection unit 21.

[0060] The abnormality determination unit 41 is a logic circuit configured using, for example, a general-purpose IC. The abnormality determination unit 41 may also be configured using a programmable logic device (PLD). The function of the abnormality determination unit 41 may be realized by a program.

[0061] 10 is a diagram showing the relationship between the output signals from overcurrent detection unit 21 and disconnection determination unit 31 that are input to abnormality determination unit 41, and the disconnection abnormality signal and overcurrent abnormality signal that are output from abnormality determination unit 41. As shown in Fig. 10, abnormality determination unit 41 outputs a disconnection abnormality signal (outputs a High signal for the disconnection abnormality signal) when the outputs from overcurrent detection unit 21 and disconnection determination unit 31 are both High signals, and outputs an overcurrent abnormality signal (outputs a High signal for the overcurrent abnormality signal) when the output signal from overcurrent detection unit 21 is High and the output signal from disconnection determination unit 31 is Low.

[0062] As a result, when the abnormality determination unit 41 detects the occurrence of an overcurrent in the power supply circuit 1, it can determine whether the overcurrent is caused by a break in the track circuit 3.

[0063] In the power supply circuit 1 configured as in this embodiment, the degree of increase in the internal current varies depending on the power supply status to the moving body. Therefore, even if a break occurs in the track circuit 3, it may be detected as an abnormality in the internal current depending on the power supply status to the moving body.

[0064] FIG. 11A is a diagram showing a change in the internal current when a break occurs in the track circuit 3 when the internal current is small. FIG. 11B is a diagram showing a change in the internal current when a break occurs in the track circuit 3 when the internal current is large. Note that FIGS. 11A and 11B also show the change in current in the break detection unit 11. When a break occurs in the track circuit 3, the current flowing in the break detection unit 11 decreases.

[0065] 11A and 11B, when a break occurs in the track circuit 3, the internal current of the power supply circuit 1 increases temporarily. The reason why the internal current of the power supply circuit 1 increases in this manner is as follows.

[0066] When a break occurs in one of the multiple track circuits 3, the combined inductance of the multiple track circuits 3 electrically connected in parallel increases. On the other hand, the combined capacitance of the capacitors in the power supply circuit 1 does not change, so the resonant frequency f of the LC resonant circuit (f = 1 / (2π√(L × C), L: combined inductance, C: combined capacitance)) decreases. Figure 12 is a diagram that schematically shows the relationship between the frequency of the current on the output side of the power supply circuit 1 and the internal current of the power supply circuit 1. As shown in Figure 12, when a break in the track circuit 3 causes a decrease in the resonant frequency f of the LC resonant circuit located on the output side of the power supply circuit 1, the internal current flowing inside the power supply circuit 1 at the drive frequency of the current-source inverter 2 increases.

[0067] 11A, when the internal current of the power supply circuit 1 is small, if a break occurs in the track circuit 3, the current in the break detection unit 11 decreases and becomes smaller than the first current threshold value earlier than the internal current of the power supply circuit 1 increases. Therefore, the break in the track circuit 3 can be detected by the break detection unit 11.

[0068] 11B, when the internal current of the power supply circuit 1 is large, if a break occurs in the track circuit 3, the internal current of the power supply circuit 1 increases and becomes larger than the second threshold value earlier than the timing at which the current in the break detection unit 11 decreases and becomes smaller than the first current threshold value. Therefore, in this case, the overcurrent detection unit 21 detects that there is an overcurrent in the power supply circuit 1.

[0069] Therefore, if the abnormality detection device only has a wire breakage detection unit and an overcurrent detection unit, it may not be possible to detect a wire breakage in the track circuit 3 accurately and quickly.

[0070] In contrast to this, as in the present embodiment, the abnormality detection device 10 has the disconnection determination unit 31 and the abnormality determination unit 41 in addition to the disconnection detection unit 11 and the overcurrent detection unit 21, so that even if an overcurrent in the power supply circuit 1 is detected before a disconnection in the track circuit 3 as described above, it can accurately determine the disconnection in the track circuit 3.

[0071] Fig. 13A is a diagram showing a change in the internal current when a break occurs in the track circuit 3 when the internal current is small. Fig. 13B is a diagram showing a change in the internal current when a break occurs in the track circuit 3 when the internal current is large.

[0072] 13A, when the disconnection detection unit 11 detects a disconnection in the track circuit 3 (when the disconnection detection unit 11 outputs a High signal), the abnormality detection device 10 detects that there is a disconnection abnormality in the track circuit 3 and outputs a disconnection abnormality signal. In this case, the disconnection determination unit 31 also determines that there is a disconnection in the track circuit 3 (outputs a High signal), but because the overcurrent detection unit 21 does not detect an overcurrent in the power supply circuit 1, the abnormality determination unit 41 does not determine that there is a disconnection abnormality in the track circuit 3.

[0073] 13B, when the overcurrent detection unit 21 detects an overcurrent in the power supply circuit 1 (when the overcurrent detection unit 21 outputs a High signal), and the disconnection determination unit 31 determines that there is a disconnection in the track circuit 3 (when the disconnection determination unit 31 outputs a High signal), the abnormality determination unit 41 determines that there is a disconnection abnormality in the track circuit 3. In this case, the disconnection detection unit 11 also detects the disconnection abnormality in the track circuit 3, but the disconnection determination unit 31 can detect the disconnection in the track circuit 3 earlier than the disconnection detection unit 11 (see ts and tp in FIG. 13B).

[0074] The determination operation of the abnormality detection device 10 having the above configuration will be described with reference to Fig. 14. Fig. 14 is a diagram showing the relationship between the operations of the disconnection detection unit 11, the disconnection determination unit 31, and the overcurrent detection unit 21 in the abnormality detection device 10 and the determination results.

[0075] 14, the abnormality detection device 10 determines that the device is normal when a low signal is output from the disconnection detection unit 11 and the overcurrent detection unit 21. In this case, whether the signal output from the disconnection determination unit 31 is a low signal or a high signal does not affect the determination of the abnormality detection device 10.

[0076] The abnormality detection device 10 determines that a wire breakage abnormality has occurred when the wire breakage detection unit 11 outputs a high signal. In this case, the signal output from the overcurrent detection unit 21 is a low signal, and whether the signal output from the wire breakage determination unit 31 is a low signal or a high signal does not affect the determination by the abnormality detection device 10. Note that the abnormality detection device 10 may also determine that a wire breakage abnormality has occurred when a rising edge of the signal output from the wire breakage detection unit 11 is detected.

[0077] Furthermore, the abnormality detection device 10 determines that a wire breakage abnormality has occurred when a high signal is output from the wire breakage determination unit 31 and the overcurrent detection unit 21. In this case, the signal output from the wire breakage detection unit 11 is a low signal. Note that the abnormality detection device 10 may also determine that a wire breakage abnormality has occurred when the wire breakage determination unit 31 outputs a high signal and a rising edge of the signal output from the overcurrent detection unit 21 is detected.

[0078] The abnormality detection device 10 determines that an overcurrent abnormality has occurred when the disconnection determination unit 31 outputs a low signal and the overcurrent detection unit 21 outputs a high signal. In this case, the signal output from the disconnection detection unit 11 is a low signal. The abnormality detection device 10 may also determine that an overcurrent abnormality has occurred when the disconnection determination unit 31 outputs a low signal and a rising edge of the signal output from the overcurrent detection unit 21 is detected.

[0079] The abnormality detection device 10 of this embodiment is an abnormality detection device that detects abnormalities in a power supply system P that includes a plurality of track circuits 3 electrically connected in parallel, and a power supply circuit 1 that has a capacitor 5 and uses LC resonance to supply current of a predetermined frequency to the plurality of track circuits 3 via the capacitor 5. The abnormality detection device 10 includes a disconnection detection unit 11 that detects disconnections in the plurality of track circuits 3, an overcurrent detection unit 21 that detects overcurrent occurring in the power supply circuit 1, and an abnormality determination unit 41 that, when the overcurrent detection unit 21 detects the occurrence of an overcurrent in the power supply circuit 1, determines the cause of the abnormality in the power supply system P based on the waveform of the current flowing through the plurality of track circuits 3.

[0080] With the configuration of the abnormality detection device 10 as described above, even if an overcurrent occurs inside the power supply circuit 1 due to a break in the track circuit 3, the break in the track circuit 3 can be detected quickly and accurately based on the waveforms of the currents flowing through the plurality of track circuits 3. Therefore, with the configuration of this embodiment, it is possible to obtain an abnormality detection device 10 that can detect an abnormality in the power supply system P and the cause of the abnormality at an early stage.

[0081] In this embodiment, the abnormality detection device 10 further includes a disconnection determination unit 31 that determines whether or not a disconnection has occurred in the plurality of track circuits 3 based on the waveforms of the currents flowing through the plurality of track circuits 3. The abnormality determination unit 41 determines the cause of the abnormality in the power supply system P based on the outputs of the overcurrent detection unit 21 and the disconnection determination unit 31.

[0082] As a result, even if the overcurrent detection unit 21 detects the occurrence of an overcurrent in the power supply circuit 1, the disconnection determination unit 31 can determine the presence of a disconnection in the plurality of track circuits 3. Therefore, the abnormality detection device 10 of this embodiment can detect an abnormality in the power supply system P and the cause of the abnormality at an early stage.

[0083] In addition, in this embodiment, when the overcurrent detection unit 21 detects an overcurrent occurring in the power supply circuit 1 and the disconnection determination unit 31 determines that a disconnection has occurred in multiple track circuits 3, the abnormality determination unit 41 determines that a disconnection abnormality has occurred.

[0084] This allows the abnormality determination unit 41 to accurately determine the occurrence of a disconnection abnormality in the plurality of track circuits 3 based on the detection result of the overcurrent detection unit 21 and the determination result of the disconnection determination unit 31. Therefore, the abnormality detection device 10 of this embodiment allows the occurrence of an abnormality in the power supply system P and the cause of the abnormality to be detected at an early stage.

[0085] Furthermore, in this embodiment, the disconnection detection unit 11, overcurrent detection unit 21, and disconnection determination unit 31 are configured with analog circuits. As a result, even if the abnormality detection device 10 is not equipped with a CPU or the like, it can detect disconnections and overcurrents in the power supply system P, and even if an overcurrent is detected in the power supply circuit 1, it can determine whether the cause is a disconnection in one of the multiple track circuits 3. Therefore, the abnormality detection device 10 can be realized at low cost and with a simple configuration.

[0086] (Other embodiments) Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and it is possible to appropriately modify the above-described embodiments within the scope of the spirit of the present invention.

[0087] In the above embodiment, the disconnection detection unit 11 includes a half-wave rectifier circuit 12. However, the disconnection detection unit may include another circuit, such as a full-wave rectifier circuit, instead of a half-wave rectifier circuit, as long as the circuit is capable of rectifying a voltage waveform.

[0088] In the above embodiment, the wire break detection unit 11 and the overcurrent detection unit 21 each have a comparator 17, 28 and a voltage divider circuit 18, 29. However, the wire break detection unit may have any configuration as long as it is capable of detecting a wire break based on the current flowing through the track circuit. The overcurrent detection unit may have any configuration as long as it is capable of detecting an overcurrent based on the current flowing inside the power supply circuit.

[0089] In the above embodiment, the pulse detector 32 of the disconnection determiner 31 has a photocoupler 33. However, the pulse detector may have another configuration as long as it is capable of detecting the current of the track circuit as a pulse.

[0090] In the above embodiment, the disconnection detection unit 11, the overcurrent detection unit 21, and the disconnection determination unit 31 are configured by analog circuits. However, at least one of the disconnection detection unit, the overcurrent detection unit, and the disconnection determination unit may be realized by a program.

[0091] In the above embodiment, the internal time constant of the disconnection determination unit 31 is smaller than the internal time constant of the disconnection detection unit 11. However, the internal time constant of the disconnection determination unit may be the same as or larger than the internal time constant of the disconnection detection unit.

[0092] In the above embodiment, the power supply circuit 1 has the abnormality detection device 10. However, the abnormality detection device may be a device separate from the power supply circuit. [Industrial Applicability]

[0093] The present invention can be used in an abnormality detection device capable of detecting an abnormality in a power supply system that includes a power supply circuit that uses LC resonance to supply a current of a predetermined frequency to a plurality of loads that are electrically connected in parallel via a capacitor. [Explanation of symbols]

[0094] 1 Power circuit 2 Current-fed inverter 3 Track circuit (load) 4 Inductance 5. Capacitors 6 Input inductance 7 Internal Current Detector 8 Output Current Detector 10. Anomaly detection device 11. Disconnection detection unit 12 Half wave rectifier circuit 13 Diode 14, 23, 34 Resistor 15, 24, 35 capacitors 16 Comparison circuit 17, 25, 28 Comparators 18, 29 Voltage divider circuit 21 Overcurrent detection section 22 Signal conversion unit 26 Amplifying resistor circuit 27 Overcurrent judgment section 31 Disconnection detection unit 32 Pulse detection unit 33 Photocoupler 36 Monostable Multivibrator 41 Abnormality determination section 42 Disconnection abnormality detection unit 43, 48 AND circuit 46 Overcurrent abnormality determination section 47 NOT circuit P Power supply system

Claims

1. a plurality of loads electrically connected in parallel; a power supply circuit having a capacitor, the power supply circuit utilizing LC resonance to supply a current of a predetermined frequency to the plurality of loads via the capacitor; An abnormality detection device for detecting an abnormality in a power supply system comprising: a disconnection detection unit that detects a disconnection in the plurality of loads based on a current flowing through each of the plurality of loads; an overcurrent detection unit that detects an occurrence of an overcurrent in the power supply circuit when an internal current of the power supply circuit is greater than a threshold value; a disconnection determination unit that converts currents flowing through the plurality of loads into pulses and determines whether a disconnection has occurred in the plurality of loads based on the presence or absence of the pulses, earlier than the disconnection detection unit; an abnormality determination unit that determines a cause of an abnormality in the power supply system based on an output of the disconnection determination unit when the overcurrent detection unit detects an occurrence of an overcurrent in the power supply circuit; having Anomaly detection device.

2. 2. The abnormality detection device according to claim 1, The abnormality determination unit An abnormality detection device that determines that a wire breakage abnormality has occurred when the overcurrent detection unit detects an overcurrent occurring in the power supply circuit and the wire breakage determination unit determines that a wire breakage has occurred in the multiple loads.

3. 3. The abnormality detection device according to claim 1, The abnormality detection device, wherein the disconnection detection unit, the overcurrent detection unit, and the disconnection determination unit are configured by analog circuits.

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