Resonant Current Limiting System

Abstract

To suppress resonance in a circuit.SOLUTION: A resonance current restriction system 100 has a temperature detection element 1, a resonance frequency setting unit 2, and a resonance control unit. The temperature detection element 1 detects a temperature of a capacitive element 9 in a circuit 7 including an inductance element 8 and the capacitive element 9. The resonance frequency setting unit 2 is provided in the circuit 7 in series with the capacitive element 9. The resonance frequency setting unit 2 sets a resonance frequency of the circuit 7 variable. The resonance control unit changes the resonance frequency of the circuit 7 by controlling the resonance frequency setting unit 2, when a determination condition is satisfied. The determination condition includes an increase of a detection temperature detected by the temperature detection element 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to a resonant current limiting system, and more particularly to a resonant current limiting system that limits resonance occurring in a circuit including an inductive element and a capacitive element. [Background technology]

[0002] Patent Document 1 discloses a resonant current limiting device.

[0003] In a vehicle to which the resonant current limiting device of Patent Document 1 is applied, a first smoothing capacitor and an inverter circuit are connected across a battery, and a motor is controlled by the inverter circuit. A second smoothing capacitor is connected across the first smoothing capacitor via an inductor. A storage element is inserted between the second smoothing capacitor and ground. An electric device is connected across a series circuit of the second smoothing capacitor and the storage element. The voltage of the storage element is controlled by a voltage controller.

[0004] The voltage controller controls the terminal voltage of the storage element by charging and discharging the electric charge supplied from the drive power supply. The voltage controller is a step-down switching power supply circuit including an inductor, two FETs, and control logic for controlling the switching of the two FETs. The control logic controls the command voltage of the storage element so that the fluctuation in the terminal voltage of the first smoothing capacitor is equal to the fluctuation in the series terminal voltage of the second smoothing capacitor and the storage element. As a result, the voltage applied to the inductor does not have a resonant frequency component, so that a current with a resonant frequency component does not flow through the inductor, and resonance occurring between the inductor and the smoothing capacitor is suppressed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-46819 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a resonant current limiting system capable of suppressing resonance in a circuit. [Means for solving the problem]

[0007] A resonant current limiting system according to one aspect of the present disclosure includes a temperature detection element, a resonant frequency setting unit, and a resonant control unit. The temperature detection element detects a temperature of a capacitive element in a circuit including an inductance element and a capacitive element. The resonant frequency setting unit is provided in the circuit in series with the capacitive element. The resonant frequency setting unit variably sets a resonant frequency of the circuit. When a determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit. The determination condition includes an increase in a detected temperature detected by the temperature detection element. The resonance control section determines that the detected temperature has increased when the detected temperature has increased for a predetermined determination time. A resonant current limiting system according to an embodiment of the present disclosure includes a temperature detection element, a resonant frequency setting unit, and a resonant control unit. The temperature detection element detects a temperature of a capacitive element in a circuit including an inductance element and a capacitive element. The resonant frequency setting unit is provided in series with the capacitive element in the circuit. The resonant frequency setting unit variably sets a resonant frequency of the circuit. When a determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit. The determination condition includes an increase in a detected temperature detected by the temperature detection element. The circuit includes, as the capacitive element, a first capacitor connected between a pair of input terminals of the circuit, and a second capacitor connected between a pair of output terminals of the circuit. The resonant frequency setting unit is provided in the circuit between an input terminal on a high potential side of the pair of input terminals and an output terminal on a high potential side of the pair of output terminals. The temperature detection element includes a first temperature detection element for detecting a temperature of the first capacitor, and a second temperature detection element for detecting a temperature of the second capacitor. The determination conditions include both an increase in a first detected temperature detected by the first temperature detecting element and an increase in a second detected temperature detected by the second temperature detecting element. A resonant current limiting system according to an embodiment of the present disclosure includes a temperature detection element, a resonant frequency setting unit, and a resonant control unit. The temperature detection element detects a temperature of a capacitive element in a circuit including an inductance element and a capacitive element. The resonant frequency setting unit is provided in the circuit in series with the capacitive element. The resonant frequency setting unit variably sets a resonant frequency of the circuit. When a determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit. The determination condition includes an increase in a detected temperature detected by the temperature detection element. When the determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit from a first frequency to a second frequency, and when a release condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit from the second frequency to the first frequency. The release condition includes the detection temperature being equal to or lower than a release temperature. A resonant current limiting system according to an aspect of the present disclosure includes a temperature detection element, a resonant frequency setting unit, and a resonant control unit. The temperature detection element detects a temperature of a capacitive element in a circuit including an inductance element and a capacitive element. The resonant frequency setting unit is provided in the circuit in series with the capacitive element. The resonant frequency setting unit variably sets a resonant frequency of the circuit. When a determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit. The determination condition includes an increase in a detection temperature detected by the temperature detection element. The resonant current limiting system further includes an abnormal temperature detection unit that detects whether the detection temperature has risen to or above an abnormality determination threshold temperature, and a notification unit that notifies an outside party that the detection temperature has reached or exceeded the abnormality determination threshold temperature. A resonant current limiting system according to an embodiment of the present disclosure includes a temperature detection element, a resonant frequency setting unit, and a resonant control unit. The temperature detection element detects a temperature of a capacitive element in a circuit including an inductance element and a capacitive element. The resonant frequency setting unit is provided in the circuit in series with the capacitive element. The resonant frequency setting unit variably sets a resonant frequency of the circuit. When a determination condition is satisfied, the resonant control unit controls the resonant frequency setting unit to change the resonant frequency of the circuit. The determination condition includes an increase in a detected temperature detected by the temperature detection element. The resonant frequency setting unit includes a first path, a second path connected in parallel with the first path, and a switch provided in the first path. An inductance of an inductance component in the first path is different from an inductance of an inductance component in the second path. The resonant control unit switches the switch on and off when the determination condition is satisfied. The inductance of the inductance component in the second path is greater than the inductance of the inductance component in the first path. The resonance frequency setting unit further includes a second switch provided in the second path separately from the first switch, and the resonance control unit switches the first switch from on to off and switches the second switch from off to on when the determination condition is satisfied. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a resonant current limiting system capable of suppressing resonance in a circuit. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram showing a resonant current limiting system according to an embodiment and a circuit to which the resonant current limiting system is applied. [Diagram 2] FIG. 2 is a block diagram of a processing unit of the above resonant current limiting system. [Diagram 3] FIG. 3 is a side view showing an arrangement of a temperature detection element included in the resonant current limiting system and a capacitive element included in the circuit. [Figure 4]FIG. 4 is a plan view showing a first specific example of an arrangement of the temperature detection element and the capacitive element in the above embodiment. [Diagram 5] FIG. 5 is a bottom view showing a second specific example of an arrangement of the temperature detection element and the capacitive element in the above embodiment. [Figure 6] FIG. 6 is a time chart showing the operation of the resonant current limiting system. [Figure 7] FIG. 7 is a time chart showing another operation of the above resonant current limiting system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a resonant current limiting system according to an embodiment will be described with reference to the drawings. Each drawing described in the following embodiment is a schematic drawing, and the ratio of the size and thickness of each component in the drawing does not necessarily reflect the actual dimensional ratio.

[0011] (1) Overview As shown in Fig. 1, the resonant current limiting system 100 of this embodiment is applied to a circuit 7 including an inductance element 8 and a capacitive element 9. In this embodiment, the inductance element 8 and the capacitive element 9 are electrically connected in series. When a signal component having a frequency equivalent to the resonant frequency of the circuit 7 is input to the circuit 7, resonance may occur in the circuit 7, causing a resonant current to flow through the circuit 7. The resonant current limiting system 100 of this embodiment suppresses such resonance.

[0012] The resonant current limiting system 100 includes a temperature detection element 1, a resonant frequency setting section 2, and a resonance control section 30.

[0013] The temperature detection element 1 detects the temperature of the capacitive element 9. The resonant frequency setting unit 2 is provided in series with the capacitive element 9 in the circuit 7. The resonant frequency setting unit 2 variably sets the resonant frequency of the circuit 7. When a determination condition is satisfied, the resonance control unit 30 controls the resonant frequency setting unit 2 to change the resonant frequency of the circuit 7. The determination condition includes an increase in the detected temperature detected by the temperature detection element 1.

[0014] When resonance occurs in the circuit 7, the capacitive element 9 heats up due to the resonant current flowing through the circuit 7. In this embodiment, the resonance control unit 30 determines that resonance occurs in the circuit 7 when it detects that the temperature of the capacitive element 9 has increased due to heat generation. When it is determined that resonance occurs in the circuit 7, the resonance control unit 30 controls the resonant frequency setting unit 2 to change the resonant frequency of the circuit 7. This ends the resonance of the circuit 7, and as a result, resonance in the circuit 7 is suppressed. In this way, the resonant current limiting system 100 of this embodiment has the advantage of being able to suppress resonance in the circuit 7.

[0015] In addition, in the resonant current limiting device described in Patent Document 1, a control loop is formed that feedback controls the switching of two FETs of the voltage controller using the fluctuation of the terminal voltage of the first smoothing capacitor and the fluctuation of the series terminal voltage of the second smoothing capacitor and the storage element as inputs. Therefore, in this resonant current limiting device, control that takes into consideration the stability of the loop is required. In addition, if the control loop becomes unstable, the quality (stability) of the output power may be affected. In contrast, in the resonant current limiting system 100 of this embodiment, the occurrence of resonance is determined using the detected temperature of the temperature detection element 1 that is not connected to the circuit 7, and the resonance is suppressed by changing the resonance frequency of the circuit 7 by the resonance frequency setting unit 2. Therefore, according to the resonant current limiting system 100 of this embodiment, there is an advantage that control that takes into consideration the stability of the loop is not required. In addition, in the resonant current limiting system 100 of this embodiment, since the occurrence of resonance is determined using the detected temperature of the temperature detection element 1 that is not connected to the circuit 7, there is also an advantage that even if the temperature detection element 1 breaks down, the effect on the operation of the circuit 7 itself is small.

[0016] (2)Details Hereinafter, the resonant current limiting system 100 of the present embodiment will be described with reference to the drawings.

[0017] (2.1) Circuit First, a circuit 7 to which the resonant current limiting system 100 of the present embodiment is applied will be described with reference to Fig. 1. The circuit 7 is a closed circuit. The circuit 7 is provided in a power supply path from an on-board battery to on-board electronic devices in an electric vehicle, for example.

[0018] The circuit 7 includes a pair of input terminals 71 and 72, a pair of output terminals 73 and 74, an inductance element 8, and a capacitive element 9.

[0019] The circuit 7 includes a first inductor 81 and a second inductor 82 as the inductance element 8. That is, the inductance element 8 of the circuit 7 includes the first inductor 81 and the second inductor 82. The inductance element 8 of the circuit 7 may further include a wiring that includes an inductance component and connects between the circuit components.

[0020] The first inductor 81 is connected between the higher potential input terminal 71 of the pair of input terminals 71, 72 and the higher potential output terminal 73 of the pair of output terminals 73, 74. The second inductor 82 is connected between the lower potential input terminal 72 of the pair of input terminals 71, 72 and the lower potential output terminal 74 of the pair of output terminals 73, 74.

[0021] The circuit 7 includes a first capacitor 91 and a second capacitor 92 as the capacitive element 9. The first capacitor 91 is connected between a pair of input terminals 71, 72. The second capacitor 92 is connected between a pair of output terminals 73, 74.

[0022] As described above, the circuit 7 includes the first capacitor 91 connected between the pair of input terminals 71, 72, the second capacitor 92 connected between the pair of output terminals 73, 74, and the first inductor 81 connected between the high potential side input terminal 71 and the high potential side output terminal 73. In the circuit 7, the first capacitor 91, the second capacitor 92, and the first inductor 81 configure a π filter. The circuit 7 of this embodiment configures a filter circuit 70.

[0023] An external power supply 61 is connected between a pair of input terminals 71, 72. The power supply 61 is a DC power supply. The DC power supply is, for example, an on-board battery (storage battery) of an electric vehicle. Note that the DC power supply is not limited to a battery, and may be a combination of an AC power supply and an AC / DC converter, or the like.

[0024] An electric device (hereinafter also referred to as an "input side electric device") to which power is supplied from the power source 61 without passing through the circuit 7 may be connected between the pair of input terminals 71, 72. The input side electric device may include, for example, a circuit including an inverter and a motor in an electric vehicle.

[0025] An external electric device 62 is connected between the pair of output terminals 73, 74. The electric device 62 is a device to which power is supplied from the power source 61 via the circuit 7. The electric device 62 is, for example, an electronic device of an electric vehicle. Note that the electric device 62 is not limited to an electronic device, and may be any electric device that operates with DC power.

[0026] The circuit 7 (filter circuit 70) attenuates high-frequency noise input between a pair of input terminals 71, 72. The circuit 7 attenuates, for example, high-frequency noise superimposed on a DC voltage supplied from a power source 61 to an electric device 62. The high-frequency noise superimposed on the DC voltage may include noise caused by external electromagnetic waves. The high-frequency noise superimposed on the DC voltage may include noise generated in an inverter of the input-side electric device.

[0027] (2.2) Resonant current limiting system The resonant current limiting system 100 of this embodiment is applied to the circuit 7 described above.

[0028] The resonant current limiting system 100 includes the above-mentioned temperature detection element 1, a reference temperature detection element 10, a resonant frequency setting unit 2, and a processing unit 3. The resonant current limiting system 100 of this embodiment includes a first temperature detection element 11 and a second temperature detection element 12 as the temperature detection element 1.

[0029] The first temperature detection element 11 detects the temperature of the first capacitor 91. The first temperature detection element 11 is, for example, a thermistor.

[0030] As shown in, for example, FIGS. 3 to 5, the first temperature detection element 11 is provided near the first capacitor 91 on the substrate 700 on which the first capacitor 91 is provided. The first temperature detection element 11 is thermally coupled to the first capacitor 91. The first temperature detection element 11 is provided, for example, on a conductor pattern 710 that is provided on the substrate 700 and connected to the first capacitor 91. The first temperature detection element 11 indirectly detects the temperature of the first capacitor 91 by detecting the temperature of the conductor pattern 710. The first temperature detection element 11 may be provided on the substrate 700 on a first surface 701 (front surface) of the substrate 700 on which the first capacitor 91 is provided, or may be provided on a second surface 702 (back surface) opposite to the first surface 701. 3, the first temperature detection element 11 provided on the first surface 701 of the substrate 700 is indicated by a solid line, and an example of the position of the first temperature detection element 11 when the first temperature detection element 11 is provided on the second surface 702 of the substrate 700 is indicated by a two-dot chain line. The resonant current limiting system 100 is required to include at least one first temperature detection element 11.

[0031] In the first specific example, as shown by the solid line in Fig. 3 and Fig. 4, the first temperature detection element 11 is provided on the first surface 701 on which the first capacitor 91 is provided, and is provided close to the first capacitor 91 on a conductor pattern 711 provided on the first surface 701. The conductor pattern 711 is an example of the conductor pattern 710, and a ground terminal 910 of the first capacitor 91 is connected to the conductor pattern 711.

[0032] 5, the first temperature detection element 11 is provided on a second surface 702 opposite to the first surface 701 on which the first capacitor 91 is provided, and is provided close to the first capacitor 91 on a conductor pattern 712 provided on the second surface 702. The conductor pattern 712 is an example of the conductor pattern 710, and is connected through a via 713 to the conductor pattern 711 to which the ground terminal of the first capacitor 91 is connected. In the second specific example, at least a portion of the first temperature detection element 11 may overlap the first capacitor 91 in the thickness direction of the substrate 700 (see the two-dot chain line in FIG. 3).

[0033] The arrangement of the first temperature detection element 11 is not limited to the above-mentioned embodiment. For example, the first temperature detection element 11 may be embedded in a sealing material of the first capacitor 91, or may be arranged in the space between the substrate 700 and the first capacitor 91. In addition, the first temperature detection element 11 is not limited to a thermistor, and may be another temperature detection element such as a thermocouple.

[0034] The second temperature detection element 12 detects the temperature of the second capacitor 92. The second temperature detection element 12 is, for example, a thermistor. The positional relationship of the second temperature detection element 12 to the second capacitor 92 is similar to the positional relationship of the first temperature detection element 11 to the first capacitor 91, and therefore will not be described.

[0035] The reference temperature detection element 10 detects a reference temperature of the circuit 7. The reference temperature detection element 10 is, for example, a thermistor. The reference temperature detection element 10 is provided, for example, on a substrate 700. The reference temperature detection element 10 is used, for example, to detect heat generation from a circuit component other than the first capacitor 91 and the second capacitor 92 that may generate heat during operation of an electric device (for example, an electric vehicle) including the circuit 7 (hereinafter, also referred to as a "heat-generating component").

[0036] The detected temperature of the first temperature detection element 11 may increase due to the influence of heat from elements other than the first capacitor 91. For example, the temperature detected by the first temperature detection element 11 may increase due to heat generated by heat-generating components or the like. Therefore, by using the reference temperature detection element 10 to detect heat generated by elements (e.g., heat-generating components) other than the first capacitor 91, it is possible to determine whether the temperature rise of the first temperature detection element is due to heat generated by the first capacitor 91 or by heat generated by elements other than the first capacitor 91.

[0037] The reference temperature detection element 10 is disposed at a position less susceptible to the effects of heat generated by the first capacitor 91 than the first temperature detection element 11. Specifically, the reference temperature detection element 10 is disposed at a position where the distance between the reference temperature detection element 10 and the first capacitor 91 is greater than the distance between the first temperature detection element 11 and the first capacitor 91. In addition, the reference temperature detection element 10 is disposed at a position where it is affected by heat generated by heat-generating components to the same extent as the first temperature detection element 11.

[0038] Similarly, the reference temperature detection element 10 is disposed at a position less susceptible to the effects of heat generated by the second capacitor 92 than the second temperature detection element 12. Specifically, the reference temperature detection element 10 is disposed at a position where the distance between the reference temperature detection element 10 and the second capacitor 92 is greater than the distance between the second temperature detection element 12 and the second capacitor 92. In addition, the reference temperature detection element 10 is disposed at a position where it is affected by heat generated by heat-generating components to the same extent as the second temperature detection element 12.

[0039] As shown in FIG. 1, the resonant frequency setting unit 2 is provided in the circuit 7. The resonant frequency setting unit 2 is connected in series with a first capacitor 91 and a second capacitor 92 in the circuit 7. The resonant frequency setting unit 2 is provided between a high potential side input terminal 71 and a high potential side output terminal 73 in the circuit 7. The resonant frequency setting unit 2 is connected in series with a first inductor 81 between the high potential side input terminal 71 and the high potential side output terminal 73 in the circuit 7. The resonant frequency setting unit 2 variably sets the resonant frequency of the circuit 7.

[0040] 1, the resonant frequency setting unit 2 includes a first path 21 and a second path 22 connected in parallel to the first path 21. A first switch 23 is provided in the first path 21. A second switch 24 is provided in the second path 22. Each of the first switch 23 and the second switch 24 is an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET).

[0041] The second path 22 further includes a third inductor 25. Therefore, the inductance of the inductance component in the second path 22 is different from the inductance of the inductance component in the first path 21. More specifically, the inductance of the inductance component in the second path 22 is larger than the inductance of the inductance component in the first path 21. In the second path 22, the third inductor 25 is connected in series with the second switch 24.

[0042] The resonant frequency setting unit 2 variably sets the inductance of the circuit 7 by switching on and off at least one of the first switch 23 and the second switch 24. For example, when the first switch 23 is on and the second switch 24 is off, the inductance of the circuit 7 corresponds to the sum of the inductance of the first inductor 81 and the inductance of the second inductor 82, ignoring the inductance of the wiring, etc. When the first switch 23 is off and the second switch 24 is on, the inductance of the circuit 7 corresponds to the sum of the inductance of the first inductor 81, the inductance of the second inductor 82, and the inductance of the third inductor 25, ignoring the inductance of the wiring, etc. Since the resonant frequency of the circuit 7 depends on the inductance of the circuit 7, the resonant frequency of the circuit 7 is changed by switching on and off the first switch 23 and / or the second switch 24 of the resonant frequency setting unit 2.

[0043] The processing unit 3 can be realized by a computer system including one or more processors (microprocessors) and one or more memories. In other words, the one or more processors execute one or more programs (applications) stored in one or more memories to function as the processing unit 3. Here, the programs are pre-recorded in the memory of the processing unit 3, but they may be provided via a telecommunications line such as the Internet or recorded on a non-transitory recording medium such as a memory card.

[0044] 2, the processing unit 3 includes a resonance control unit 30. The resonance control unit 30 controls the resonance frequency setting unit 2. More specifically, the resonance control unit 30 controls the on / off of the first switch 23 and the second switch 24. The resonance control unit 30 includes an acquisition unit 31, a determination unit 32, and a switch control unit 33.

[0045] The acquiring unit 31 acquires, from the first temperature detecting element 11, a detected temperature detected by the first temperature detecting element 11 (hereinafter also referred to as a "first detected temperature T1"). Also, the acquiring unit 31 acquires, from the second temperature detecting element 12, a detected temperature detected by the second temperature detecting element 12 (hereinafter also referred to as a "second detected temperature T2"). Also, the acquiring unit 31 acquires, from the reference temperature detecting element 10, a detected temperature detected by the reference temperature detecting element 10 (hereinafter also referred to as a "reference temperature T0").

[0046] Specifically, the acquisition unit 31 acquires the measurement value of the first detection temperature T1, the measurement value of the second detection temperature T2, and the measurement value of the reference temperature T0 from the first temperature detection element 11, the second temperature detection element 12, and the reference temperature detection element 10 at a predetermined time interval (hereinafter also referred to as the "acquisition interval"). The acquisition interval of the first detection temperature T1, the acquisition interval of the second detection temperature T2, and the acquisition interval of the reference temperature T0 may be the same or different from each other. In addition, the acquisition timing of the first detection temperature T1, the acquisition timing of the second detection temperature T2, and the acquisition timing of the reference temperature T0 may be the same or different from each other. In this embodiment, it is assumed that the acquisition interval of the first detection temperature T1, the acquisition interval of the second detection temperature T2, and the acquisition interval of the reference temperature T0 are the same, and the acquisition timing of the first detection temperature T1, the acquisition timing of the second detection temperature T2, and the acquisition timing of the reference temperature T0 are the same.

[0047] The determination unit 32 determines whether or not resonance occurs in the circuit 7. The determination unit 32 determines whether resonance occurs in the circuit 7 based on a determination condition. If the determination condition is satisfied, the determination unit 32 determines that resonance occurs in the circuit 7.

[0048] The judgment conditions include an increase in the detected temperature detected by the temperature detection element 1. In this embodiment, the judgment unit 32 (resonance control unit 30) judges that the detected temperature has increased when the detected temperature increases for a predetermined judgment time. In other words, the judgment conditions include an increase in the detected temperature detected by the temperature detection element 1 for a predetermined judgment time. In this embodiment, "the detected temperature increases for the judgment time" means that the detected temperature continues to increase for the judgment time.

[0049] In this embodiment, the determination condition includes that the detected temperature increases for a determination time after the detected temperature becomes equal to or higher than the threshold temperature.

[0050] As described above, in this embodiment, the temperature detection element 1 includes the first temperature detection element 11 and the second temperature detection element 12. Therefore, the determination conditions include an increase in the first detection temperature T1 (hereinafter also referred to as the "first condition") and an increase in the second detection temperature T2 (hereinafter also referred to as the "second condition").

[0051] More specifically, the determination condition includes that the first detection temperature T1 rises for the determination time after the first detection temperature T1 becomes equal to or greater than the first threshold temperature TH1. In other words, the first condition is that the first detection temperature T1 rises for the determination time after the first detection temperature T1 becomes equal to or greater than the first threshold temperature TH1. The determination condition also includes that the second detection temperature T2 rises for the determination time after the second detection temperature T2 becomes equal to or greater than the second threshold temperature TH2. In other words, the second condition is that the second detection temperature T2 rises for the determination time after the second detection temperature T2 becomes equal to or greater than the second threshold temperature TH2.

[0052] The first threshold temperature TH1 is, for example, the upper limit temperature value that the first capacitor 91 can have when resonance does not occur in the circuit 7, or a value that adds a margin to this upper limit temperature value. The second threshold temperature TH2 is, for example, the upper limit temperature value that the second capacitor 92 can have when resonance does not occur in the circuit 7, or a value that adds a margin to this upper limit temperature value. In other words, the first threshold temperature TH1 is a value related to the upper limit temperature that the first capacitor 91 can have when the electric device (electric vehicle) including the circuit 7 is operating normally. The second threshold temperature TH2 is a value related to the upper limit temperature that the second capacitor 92 can have when the electric device including the circuit 7 is operating normally. By setting the first threshold temperature TH1 and the second threshold temperature TH2 in this manner, erroneous determination, for example, erroneous determination that a temperature rise at the start of the electric device including the circuit 7 is the occurrence of resonance, can be prevented.

[0053] As described above, in this embodiment, the acquisition unit 31 acquires the measured values ​​of the first detection temperature T1 and the second detection temperature T2 from the first temperature detection element 11 and the second temperature detection element 12 at a predetermined time interval (acquisition interval). Therefore, in this embodiment, the determination unit 32 (resonance control unit 30) determines that the detection temperatures (first detection temperature T1, second detection temperature T2) have risen for the determination time when the acquired measured values ​​have risen consecutively a predetermined number of times. The predetermined number of times is a value determined by the above-mentioned determination time and the acquisition interval. The predetermined number of times may be, for example, two times, or three times or more.

[0054] In this embodiment, the judgment conditions further include that the rate of increase of the detected temperature is greater than the rate of increase of the reference temperature T0 during the judgment time. Specifically, the judgment conditions include that the rate of increase of the first detected temperature T1 is greater than the rate of increase of the reference temperature T0 during the judgment time (hereinafter also referred to as the "third condition"). The judgment conditions also include that the rate of increase of the second detected temperature T2 is greater than the rate of increase of the reference temperature T0 during the judgment time (hereinafter also referred to as the "fourth condition"). In this embodiment, the "rate of increase of temperature" means the amount of increase (absolute value) of temperature per unit time. The unit time here may be, for example, a time corresponding to an acquisition interval at which the acquisition unit 31 acquires the measured value of the detected temperature. By including the third and fourth conditions in the judgment conditions, it is possible to prevent erroneous judgment, for example, erroneous judgment in which an increase in the detected temperature due to a factor other than the resonance of the circuit 7 (for example, heat generation of a heat-generating component) is judged to be resonance.

[0055] In this embodiment, when all of the first to fourth conditions are satisfied within a predetermined time limit that is longer than the above-mentioned judgment time, the judgment unit 32 judges that the judgment conditions are satisfied, that is, that resonance is occurring in the circuit 7.

[0056] The switch control unit 33 controls the on / off of the first switch 23 and the second switch 24 based on the determination result by the determination unit 32. When the determination unit 32 determines that resonance is occurring in the circuit 7, the switch control unit 33 switches on / off at least one of the first switch 23 and the second switch 24 (here, both). In this embodiment, "switching the on / off of a switch" means switching the switch from on to off, or switching the switch from off to on. As described above, the resonance frequency of the circuit 7 is changed by switching on / off of the first switch 23 and / or the second switch 24.

[0057] More specifically, when the determination unit 32 determines that resonance is occurring in the circuit 7, the switch control unit 33 switches the first switch 23 from on to off and switches the second switch 24 from off to on. In other words, when the determination condition is satisfied, the switch control unit 33 (resonance control unit 30) switches the first switch 23 from on to off and switches the second switch 24 from off to on. In order to avoid both the first switch 23 and the second switch 24 being turned off and the circuit 7 being cut off, when the determination condition is satisfied, the switch control unit 33 (resonance control unit 30) waits a delay time (hereinafter referred to as the "first delay time t D1 It is preferable to switch the first switch 23 from on to off after a first delay time t D1 is appropriately set in consideration of the response speed of the first switch 23 and the second switch 24, the stability of the circuit 7, and the like.

[0058] In short, when the resonance control unit 30 determines that resonance occurs in the circuit 7, it changes the resonance frequency of the circuit 7 by controlling the resonance frequency setting unit 2. When the determination condition is satisfied, the resonance control unit 30 switches the first switch 23 (and the second switch 24) on and off. As a result, the resonance frequency of the circuit 7 is changed from a value before the switch is switched on and off (hereinafter also referred to as the "first frequency") to a value after the switch is switched on and off (hereinafter also referred to as the "second frequency"). In this embodiment, the first frequency is the value of the resonance frequency of the circuit 7 when the first switch 23 is on and the second switch 24 is off, and the second frequency is the value of the resonance frequency of the circuit 7 when the first switch 23 is off and the second switch 24 is on. By changing the resonance frequency of the circuit 7 from the value (first frequency) at which resonance occurs to a different value (second frequency), the resonance of the signal of the first frequency ends, and as a result, the resonance in the circuit 7 is suppressed.

[0059] When the determination condition is satisfied and the resonant frequency of the circuit 7 is changed, the acquisition unit 31 changes the acquisition interval from the value before the resonant frequency is changed. More specifically, the acquisition unit 31 makes the acquisition interval shorter than the value before the resonant frequency is changed. For example, before the determination condition is satisfied, the acquisition unit 31 acquires the measurement values ​​of the first detection temperature T1, the measurement values ​​of the second detection temperature T2, and the reference temperature T0 at the first period LA as the acquisition interval. After the determination condition is satisfied and the resonant frequency of the circuit 7 is changed, the acquisition unit 31 acquires the measurement values ​​of the first detection temperature T1, the measurement values ​​of the second detection temperature T2, and the reference temperature T0 at the second period LB (<first period LA) as the acquisition interval.

[0060] In short, the acquisition unit 31 (resonance control unit 30) changes the acquisition interval before and after changing the resonance frequency. By changing the acquisition interval, it becomes possible to acquire the detected temperature at a timing according to the state of the circuit 7. In particular, by making the acquisition interval smaller after changing the resonance frequency than before changing the resonance frequency, it becomes possible to acquire the detected temperature at short time intervals when the capacitive element 9 is relatively hot.

[0061] In addition, in the period after the determination condition is satisfied and the resonant frequency of the circuit 7 is changed, the determination unit 32 determines whether or not resonance in the circuit 7 has ended. The determination unit 32 determines whether resonance in the circuit 7 has ended based on the release condition. When the release condition is satisfied, the determination unit 32 determines that resonance in the circuit 7 has ended.

[0062] In this embodiment, the release condition includes that the detection temperature is equal to or lower than the release temperature. More specifically, the release condition includes that the first detection temperature T1 is equal to or lower than the first release temperature and that the second detection temperature T2 is equal to or lower than the second release temperature. In this embodiment, the first release temperature is equal to the first threshold temperature TH1, and the second release temperature is equal to the second threshold temperature TH2. However, this is not limiting, and the first release temperature (or the second release temperature) may be different from the first threshold temperature TH1 (or the second threshold temperature TH2).

[0063] In this way, the judgment unit 32 judges that the resonance of the circuit 7 has ended when the temperature of the first capacitor 91 and the temperature of the second capacitor 92 become lower than the upper limit temperature values ​​(first threshold temperature TH1 and second threshold temperature TH2) that the circuit 7 can have during normal operation.

[0064] When the determination unit 32 determines that the resonance of the circuit 7 has ended, the switch control unit 33 switches on and off at least one (here, both) of the first switch 23 and the second switch 24. When the switch control unit 33 determines that the resonance of the circuit 7 has ended, the switch control unit 33 returns the first switch 23 and the second switch 24 to the states before it was determined that the determination condition was satisfied. Specifically, the switch control unit 33 switches the first switch 23 from off to on, and switches the second switch 24 from on to off. This changes the resonant frequency of the circuit 7 from the second frequency to the first frequency.

[0065] In this way, when the determination condition is satisfied, the resonance control unit 30 changes the resonance frequency of the circuit 7 from the first frequency to the second frequency. Also, when the release condition is satisfied, the resonance control unit 30 changes the resonance frequency of the circuit 7 from the second frequency to the first frequency.

[0066] When the release condition is satisfied, the switch control unit 33 switches the first switch 23 from OFF to ON and then waits a delay time (hereinafter, “second delay time t D2 It is preferable to switch the second switch 24 from on to off after a second delay time t D2 is the first delay time t D1 It may be the same as or different from.

[0067] FIG. 6 shows an example of the operation of the resonant current limiting system 100 when resonance occurs in the circuit 7. In FIG.

[0068] In the example of Fig. 6, in the period before the resonance occurs, the acquisition unit 31 acquires the measurement value of the reference temperature T0, the measurement value of the first detection temperature T1, and the measurement value of the second detection temperature T2 at an acquisition interval of a first cycle LA. Also, in the example of Fig. 6, at time t0, resonance of a first frequency occurs in the circuit 7 due to external noise or the like.

[0069] In the example of Figure 6, in the period after time t0, the first capacitor 91 and the second capacitor 92 generate heat due to the effect of resonance in the circuit 7, and at time t1, the first detection temperature T1 exceeds the first threshold temperature TH1 and the second detection temperature T2 exceeds the second threshold temperature TH2.

[0070] During the period from time t1 to time t2, the first detection temperature T1 and the second detection temperature T2 continue to rise. Then, at time t2, the determination unit 32 determines that the measurement value of the first detection temperature T1 and the measurement value of the second detection temperature T2 have risen a predetermined number of times (here, two times). As a result, the determination unit 32 determines that the first condition and the second condition are satisfied.

[0071] 6, during the period from time t1 to time t2 (the judgment time period), the reference temperature T0 also rises due to the influence of heat generation from the first capacitor 91 and the second capacitor 92. However, as shown in FIG 6, during the judgment time period, the rate of increase of the reference temperature T0 is smaller than the rate of increase of the first detection temperature T1 and is smaller than the rate of increase of the second detection temperature T2. Therefore, the judgment unit 32 judges that the third and fourth conditions are satisfied.

[0072] If it is determined that the determination condition is satisfied, the switch control unit 33 turns on the second switch 24 and waits for the first delay time t D1 After the lapse of time, the first switch 23 is turned off. This changes the resonant frequency of the circuit 7 from the first frequency to the second frequency. Furthermore, when it is determined that the determination condition is satisfied, the acquisition unit 31 changes the acquisition interval from the first period LA to the second period LB.

[0073] 6, the resonance frequency of the circuit 7 is changed from the first frequency to the second frequency, and the resonance in the circuit 7 ends, so that the rates of increase of the first detection temperature T1, the second detection temperature T2, and the reference temperature T0 gradually decrease and eventually start to decrease. Then, at time t3, the first detection temperature T1 becomes equal to or lower than the first threshold temperature TH1, and the second detection temperature T2 becomes equal to or lower than the second detection temperature TH2. This causes the determination unit 32 to determine that the release condition is satisfied.

[0074] If it is determined that the release condition is satisfied, the switch control unit 33 turns on the first switch 23 and waits for the second delay time t D2 After the elapse of time, the second switch 24 is turned off. This changes the resonant frequency of the circuit 7 from the second frequency to the first frequency. Furthermore, when it is determined that the release condition is satisfied, the acquisition unit 31 changes the acquisition interval from the second period LB to the first period LA.

[0075] In this manner, according to the resonant current limiting system 100 of the present embodiment, it is possible to suppress resonance in the circuit 7 by changing the resonant frequency of the circuit 7 when resonance occurs.

[0076] 1, the resonant current limiting system 100 further includes a third switch 51 and a fourth switch 52. The processing unit 3 further includes an abnormal temperature detection unit 34, a shutdown control unit 35, and a notification unit 36.

[0077] The third switch 51 is connected in series with the first capacitor 91 between a pair of input terminals 71, 72. The fourth switch 52 is connected in series with the second capacitor 92 between a pair of output terminals 73, 74. Each of the third switch 51 and the fourth switch 52 is an n-channel type MOSFET. The third switch 51 and the fourth switch 52 are normally kept on.

[0078] The abnormal temperature detection unit 34 detects whether the detection temperature has risen to or above the abnormality determination threshold temperature TH10. Specifically, the abnormal temperature detection unit 34 detects whether the first detection temperature T1 has risen to or above the first abnormality determination threshold temperature TH11. The abnormal temperature detection unit 34 also detects whether the second detection temperature T2 has risen to or above the second abnormality determination threshold temperature. The first abnormality determination threshold temperature TH11 and the second abnormality determination threshold temperature are thresholds for detecting an excessive temperature rise in the first capacitor 91 and the second capacitor 92, respectively. The first abnormality determination threshold temperature TH11 is a value larger than the first threshold temperature TH1, and the second abnormality determination threshold temperature is a value larger than the second threshold temperature TH2. The first abnormality determination threshold temperature TH11 and the second abnormality determination threshold temperature may be the same or different from each other.

[0079] An excessive temperature rise in the capacitive element 9 can cause a malfunction of the capacitive element 9. Therefore, the resonant current limiting system 100 uses the abnormal temperature detection unit 34 to detect whether the detected temperature has risen to or above the abnormality determination threshold temperature TH10.

[0080] When the abnormal temperature detection unit 34 detects that the first detection temperature T1 has risen to or above the first abnormality determination threshold temperature TH11, the cutoff control unit 35 switches the third switch 51 from on to off. Also, when the abnormal temperature detection unit 34 detects that the second detection temperature T2 has risen to or above the second abnormality determination threshold temperature, the cutoff control unit 35 switches the fourth switch 52 from on to off. That is, when the abnormal temperature detection unit 34 detects an excessive temperature rise in the capacitive element 9 (the first capacitor 91 or the second capacitor 92), the cutoff control unit 35 turns off the switch (the third switch 51 or the fourth switch 52) connected in series with the capacitive element 9.

[0081] If the temperature rise of the capacitive element 9 is caused by resonance of the circuit 7, turning off the switch (the third switch 51 or the fourth switch 52) ends the resonance of the circuit 7, and thus a further temperature rise of the capacitive element 9 is suppressed. In addition to the resonance of the circuit 7, a cause of the temperature rise of the capacitive element 9 may also be the application of a high voltage, such as a load dump, to the capacitive element 9. Even in such a case, turning off the switch (the third switch 51 or the fourth switch 52) stops the application of the high voltage to the capacitive element 9, and thus a further temperature rise of the capacitive element 9 is suppressed. This protects the capacitive element 9.

[0082] The cutoff control unit 35 may turn on the third switch 51 again when the first detection temperature T1 becomes equal to or lower than a predetermined threshold temperature (for example, the above-mentioned first threshold temperature TH1) after turning off the third switch 51. Similarly, the cutoff control unit 35 may turn on the fourth switch 52 again when the second detection temperature T2 becomes equal to or lower than a predetermined threshold temperature (for example, the above-mentioned second threshold temperature TH2) after turning off the fourth switch 52.

[0083] In short, the circuit 7 includes a pair of connection terminals as a pair of input terminals 71, 72 or a pair of output terminals 73, 74. The capacitive element 9 (the first capacitor 91 or the second capacitor 92) is connected between the pair of connection terminals (the pair of input terminals 71, 72 or the pair of output terminals 73, 74). The resonant current limiting system 100 further includes a cutoff switch (the third switch 51 or the fourth switch 52) and a cutoff control unit 35. The cutoff switch (the third switch 51 or the fourth switch 52) is connected in series with the capacitive element (the first capacitor 91 or the second capacitor 92) between the pair of connection terminals. When the abnormal temperature detection unit 34 detects that the detection temperature (the first detection temperature T1 or the second detection temperature T2) has risen to or above the abnormality determination threshold temperature TH10 (the first abnormality determination threshold temperature TH11 or the second abnormality determination threshold temperature), the cutoff control unit 35 switches the cutoff switch (the third switch 51 or the fourth switch 52) from on to off.

[0084] The notification unit 36 ​​notifies the outside that the detection temperature (the first detection temperature T1 or the second detection temperature T2) has become equal to or higher than the abnormality determination threshold temperature (the first abnormality determination threshold temperature TH11 or the second abnormality determination threshold temperature). That is, the notification unit 36 ​​notifies the outside that the temperature of the capacitive element 9 (the first capacitor 91 or the second capacitor 92) has risen excessively. Examples of the notification to the outside may include notification via wired or wireless communication, notification via sound or display (including light emission, etc.). The notification to the outside is not limited to being performed immediately when an excessive temperature rise of the capacitive element 9 occurs. For example, the notification unit 36 ​​may record a history of information on the excessive temperature rise of the capacitive element 9 in a built-in recording device or the like, and notify the outside of the history of the excessive temperature rise in response to a request from the outside (for example, when an external device is connected to a communication port of the recording device).

[0085] FIG. 7 shows an example of the operation of the resonant current limiting system 100 when the temperature of the first capacitor 91 increases excessively.

[0086] 7, a load dump is applied to the circuit 7 at time t10, causing the temperature of the first capacitor 91 to start rising. Then, at time t13, the abnormal temperature detection unit 34 detects that the first detection temperature T1 has risen to or above the first abnormality determination threshold temperature TH11. When it is detected that the first detection temperature T1 has risen to or above the first abnormality determination threshold temperature TH11, the cutoff control unit 35 turns off the third switch 51.

[0087] 7, turning off the third switch 51 stops the application of voltage to the first capacitor 91, which causes the rate of increase of the first detected temperature T1 to gradually decrease and eventually start to decrease. Then, at time t14, it is detected that the first detected temperature T1 has become equal to or lower than the first threshold temperature TH1, and the cutoff control unit 35 turns on the third switch 51 again.

[0088] In this example, the first detection temperature T1 becomes equal to or higher than the first threshold temperature TH1 at time t11, and the determination unit 32 determines that the measurement value of the first detection temperature T1 has risen a predetermined number of times (here, twice) in succession at time t12. As a result, the determination unit 32 determines that resonance is occurring in the circuit 7, and the switch control unit 33 switches the first switch 23 from on to off and the second switch 24 from off to on. The acquisition unit 31 also changes the acquisition interval from the first period LA to the second period LB. Then, at time t14, the first detection temperature T1 becomes equal to or lower than the first release temperature (first threshold temperature TH1), and the switch control unit 33 switches the first switch 23 from off to on and the second switch 24 from on to off. The acquisition unit 31 also changes the acquisition interval from the second period LB to the first period LA.

[0089] (3) Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, the same function as the processing unit 3 according to the above embodiment may be embodied in a data creation method, a computer program, or a non-transitory recording medium on which a computer program is recorded, etc.

[0090] Modifications of the above embodiment are listed below. The modifications described below can be applied in appropriate combination.

[0091] The resonant current limiting system 100 in the present disclosure includes a computer system in the processing unit 3, etc. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system, thereby realizing the function of the processing unit 3 in the present disclosure. The program may be pre-recorded in the memory of the computer system, may be provided through an electric communication line, or may be provided by being recorded in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits such as IC or LSI referred to here are called by different names depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, a field-programmable gate array (FPGA) that is programmed after the manufacture of the LSI, or a logic device that can reconfigure the connection relationship inside the LSI or the circuit partition inside the LSI, can also be adopted as a processor. The electronic circuits may be integrated in one chip or distributed among multiple chips. The chips may be integrated in one device or distributed among multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Thus, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0092] Furthermore, it is not essential that the multiple functions of the processing unit 3 are concentrated in one housing. For example, the components of the processing unit 3 may be distributed across multiple housings.

[0093] Conversely, multiple functions in the processing unit 3 may be integrated in one housing. Furthermore, at least some of the functions of the processing unit 3 may be realized by a cloud (cloud computing) or the like.

[0094] In one modified example, the judgment conditions do not need to include all of the first to fourth conditions. For example, the judgment conditions may include only the first condition, may include only the first and third conditions, may include only the second condition, may include only the second and fourth conditions, or may include only the first and second conditions. In that case, the first temperature detection element 11, the second temperature detection element 12, and the reference temperature detection element 10 may be omitted as appropriate.

[0095] In one modified example, the determination conditions may include, instead of or in addition to the first to fourth conditions, that the detected temperature (the first detected temperature T1 or the second detected temperature T2) is equal to or higher than a predetermined resonance threshold temperature.

[0096] In one modification, the circuit 7 in which resonance is suppressed by the resonant current limiting system 100 is not limited to a circuit including the first inductor 81, the second inductor 82, the first capacitor 91, and the second capacitor 92. For example, the circuit 7 in which resonance is suppressed by the resonant current limiting system 100 may be a circuit including the input side external device, the first inductor 81, the second capacitor 92, and the second inductor 82. In this case, the determination condition may include the second condition (and the fourth condition). In addition, in this case, the determination condition may further include that the rate of increase of the second detection temperature T2 is greater than the rate of increase of the first detection temperature T1. Alternatively, the circuit 7 in which resonance is suppressed by the resonant current limiting system 100 may be a circuit including the first inductor 81, the electric device 62, the second inductor 82, and the first capacitor 91. In this case, the determination condition may include the first condition (and the third condition). In addition, in this case, the determination condition may further include that the rate of increase of the first detection temperature T1 is greater than the rate of increase of the second detection temperature T2.

[0097] In one modified example, the release condition is not limited to the detection temperature (first detection temperature T1, second detection temperature T2) being equal to or lower than the threshold temperature (first threshold temperature TH1, second threshold temperature TH2). For example, the release condition may include the detection of the measurement value of the detection temperature being equal to or lower than the threshold temperature multiple times.

[0098] In one variant, the abnormal temperature detection unit 34 may determine that the capacitive elements (first capacitor 91, second capacitor 92) are abnormally heating when it detects that the measured value of the detection temperature is equal to or higher than the abnormality determination threshold temperature TH10 multiple times in succession.

[0099] In one modified example, the resonance frequency setting unit 2 may also have an inductor provided in the first path 21. Note that since the first path 21 is a path through which a current flows when no resonance occurs in the circuit 7, it is preferable that no inductor is provided in the first path 21 (or that the inductance of the inductance component in the first path 21 is smaller than the inductance of the inductance component in the second path 22) in consideration of heat generation in the inductor.

[0100] In one variant, the inductance of the inductance component in the second path 22 may be smaller than the inductance of the inductance component in the first path 21 .

[0101] In one modified example, the resonant frequency setting unit 2 may include a switch only in one of the first path 21 and the second path 22. Even in this case, the inductance of the circuit 7 is changed by switching the switch on and off, thereby changing the resonant frequency of the circuit 7. In this case, the inductor of the inductance component of the first path 21 may be the same as the inductor of the inductance component of the second path 22, as long as it has a magnitude that allows the resonant frequency of the circuit 7 to be changed by switching the switch on and off.

[0102] (4) Description The following aspects are disclosed from the above-described embodiment and modified examples.

[0103] A resonant current limiting system (100) of a first aspect includes a temperature detection element (1), a resonant frequency setting unit (2), and a resonant control unit (30). The temperature detection element (1) detects the temperature of a capacitive element (9) in a circuit (7) including an inductance element (8) and a capacitive element (9). The resonant frequency setting unit (2) is provided in series with the capacitive element (9) in the circuit (7). The resonant frequency setting unit (2) variably sets the resonant frequency of the circuit (7). When a determination condition is satisfied, the resonance control unit (30) controls the resonant frequency setting unit (2) to change the resonant frequency of the circuit (7). The determination condition includes an increase in the detected temperature detected by the temperature detection element (1).

[0104] According to this embodiment, it is possible to suppress resonance in the circuit (7).

[0105] In the resonant current limiting system (100) of the second aspect, in the first aspect, the resonant frequency setting unit (2) includes a first path (21), a second path (22), and a switch. The second path (22) is connected in parallel with the first path (21). The switch is provided in the first path (21). The inductance of the inductance component in the first path (21) is different from the inductance of the inductance component in the second path (22). The resonance control unit (30) switches the switch on and off when a determination condition is satisfied.

[0106] According to this embodiment, the resonant frequency of the circuit (7) can be changed by turning the switch on and off.

[0107] In the resonant current limiting system (100) of the third aspect, in the second aspect, the inductance of the inductance component in the second path (22) is greater than the inductance of the inductance component in the first path (21). The resonant frequency setting unit (2) further includes a second switch (24) provided in the second path (22) in addition to the first switch (23) which is the switch. When the determination condition is satisfied, the resonance control unit (30) switches the first switch (23) from on to off and switches the second switch (24) from off to on.

[0108] According to this embodiment, it is possible to change the resonant frequency of the circuit (7) by switching on and off the first switch (23) and the second switch (24). Even if either the first switch (23) or the second switch (24) is constantly on due to a malfunction, it is possible to change the resonant frequency of the circuit (7).

[0109] In the resonant current limiting system (100) of the fourth aspect, in the third aspect, when the determination condition is satisfied, the resonant control unit (30) switches the second switch (24) from OFF to ON and then waits a delay time (first delay time t D1 ) has elapsed, the first switch (23) is switched from on to off.

[0110] According to this embodiment, it is possible to prevent a situation in which both the first path (21) and the second path (22) are opened and the circuit (7) is interrupted.

[0111] In the resonant current limiting system (100) of the fifth aspect, in any one of the first to fourth aspects, the circuit (7) includes, as the capacitive element (9), a first capacitor (91) connected between a pair of input terminals (71, 72) of the circuit (7) and a second capacitor (92) connected between a pair of output terminals (73, 74) of the circuit (7). The resonant frequency setting unit (2) is provided in the circuit (7) between the input terminal (71) on the high potential side of the pair of input terminals (71, 72) and the output terminal (73) on the high potential side of the pair of output terminals (73, 74). The resonant current limiting system (100) includes, as the temperature detection element (1), a first temperature detection element (11) that detects the temperature of the first capacitor (91) and a second temperature detection element (12) that detects the temperature of the second capacitor (92). The judgment conditions include both that the first detected temperature (T1) detected by the first temperature detection element (11) rises during the judgment time and that the second detected temperature (T2) detected by the second temperature detection element (12) rises during the judgment time.

[0112] According to this embodiment, it is possible to suppress resonance in the circuit (7).

[0113] In the resonant current limiting system (100) of the sixth aspect, in any one of the first to fifth aspects, the resonance control unit (30) determines that the detected temperature has increased when the detected temperature has increased for a predetermined determination time.

[0114] According to this aspect, the accuracy of determining the occurrence of resonance can be improved.

[0115] In the seventh aspect of the resonant current limiting system (100), in the sixth aspect, the resonance control unit (30) acquires a measurement value of the detected temperature at a predetermined acquisition interval. When the acquired measurement value increases a predetermined number of times in succession, the resonance control unit (30) determines that the detected temperature has increased.

[0116] According to this aspect, it is possible to determine an increase in the detected temperature by digital processing.

[0117] In the resonant current limiting system (100) of the eighth aspect, in the seventh aspect, the resonance control unit (30) changes the acquisition interval before and after changing the resonant frequency.

[0118] According to this embodiment, it is possible to obtain the detected temperature at a timing according to the state of the circuit (7).

[0119] The resonant current limiting system (100) of a ninth aspect is any one of the sixth to eighth aspects, further comprising a reference temperature detection element (10) that detects a reference temperature of the circuit (7). The determination conditions further include that the rate of increase of the detected temperature is greater than the rate of increase of the reference temperature during the determination time.

[0120] According to this embodiment, it is possible to prevent an erroneous determination that a rise in the detected temperature due to a factor other than resonance of the circuit (7) is due to resonance.

[0121] In the resonant current limiting system (100) of the tenth aspect, in any one of the sixth to ninth aspects, the determination condition includes that the detected temperature increases for a determination time after the detected temperature becomes equal to or higher than the threshold temperature.

[0122] According to this embodiment, for example, it is possible to prevent an erroneous determination that a temperature rise at the start of an electric device including the circuit (7) is the occurrence of resonance.

[0123] In the resonant current limiting system (100) of an eleventh aspect, in any one of the first to tenth aspects, when a determination condition is satisfied, the resonance control unit (30) controls the resonance frequency setting unit (2) to change the resonant frequency of the circuit (7) from the first frequency to the second frequency. When a release condition is satisfied, the resonance control unit (30) controls the resonance frequency setting unit (2) to change the resonant frequency of the circuit (7) from the second frequency to the first frequency. The release condition includes that the detected temperature is equal to or lower than the release temperature.

[0124] According to this embodiment, it is possible to return the circuit (7) to its original state after the resonance of the circuit (7) ends.

[0125] The resonant current limiting system (100) of a twelfth aspect is any one of the first to eleventh aspects, and further includes an abnormal temperature detection section (34) and a notification section (36). The abnormal temperature detection section (34) detects whether the detected temperature has risen to or above an abnormality determination threshold temperature (TH10). The notification section (36) notifies an outside that the detected temperature has reached or exceeded the abnormality determination threshold temperature (TH10).

[0126] According to this embodiment, it is possible to detect abnormal heat generation in the capacitive element (9).

[0127] In the resonant current limiting system (100) of the thirteenth aspect, in the twelfth aspect, the circuit (7) includes a pair of connection terminals as a pair of input terminals (71, 72) or a pair of output terminals (73, 74). The capacitive element (9) is connected between the pair of connection terminals. The resonant current limiting system (100) further includes a cutoff switch (third switch 51, fourth switch 52) connected in series with the capacitive element (9) between the pair of connection terminals, and a cutoff control unit (35) that switches the cutoff switch from on to off when the abnormal temperature detection unit (34) detects that the detected temperature has become equal to or higher than the abnormality determination threshold temperature (TH10).

[0128] According to this embodiment, when the capacitive element (9) abnormally heats up, the supply of power to the capacitive element (9) can be stopped to protect the capacitive element (9). [Explanation of symbols]

[0129] 100 Resonant Current Limiting System 1 Temperature detection element 11 First temperature detection element 12 Second temperature detection element 10 Reference temperature detection element 2 Resonance frequency setting section 21 Route 1 22 Route 2 23 First Switch 24 Second Switch 30 Resonance control section 34 Abnormal temperature detection unit 36 Notification Department 51 Third switch (shutoff switch) 52 4th switch (shutoff switch) 7 Circuit 71,72 A pair of input terminals 73,74 A pair of output terminals 8 Inductance elements 9 Capacitive Elements 91 First Capacitor 92 Second Capacitor t D1 1st delay time (delay time) T1 First detection temperature T2 Second detection temperature TH10 Abnormality threshold temperature

Claims

1. a temperature detection element for detecting a temperature of a capacitive element in a circuit including an inductance element and a capacitive element; a resonant frequency setting unit that is provided in series with the capacitive element in the circuit and that variably sets a resonant frequency of the circuit; a resonance control unit that controls the resonance frequency setting unit to change the resonance frequency of the circuit when a determination condition is satisfied; Equipped with the determination condition includes an increase in a detected temperature detected by the temperature detection element, The resonance control unit determines that the detected temperature has increased when the detected temperature has increased for a predetermined determination time. Resonant current limiting system.

2. The resonance control unit acquires a measurement value of the detected temperature at a predetermined acquisition interval, The resonance control unit determines that the detected temperature has increased when the acquired measured value has increased a predetermined number of times in succession.

2. The resonant current limiting system of claim 1.

3. The resonance control unit changes the acquisition interval before and after changing the resonance frequency.

3. The resonant current limiting system of claim 2.

4. Further comprising a reference temperature detection element for detecting a reference temperature of the circuit, The determination condition further includes that a rate of increase of the detected temperature is greater than a rate of increase of the reference temperature during the determination time. A resonant current limiting system according to any one of claims 1 to 3.

5. The determination condition includes that the detected temperature rises for the determination time after the detected temperature becomes equal to or higher than a threshold temperature. A resonant current limiting system according to any one of claims 1 to 4.

6. A temperature detection element for detecting a temperature of a capacitive element in a circuit including an inductance element and a capacitive element; a resonant frequency setting unit that is provided in series with the capacitive element in the circuit and that variably sets a resonant frequency of the circuit; a resonance control unit that controls the resonance frequency setting unit to change the resonance frequency of the circuit when a determination condition is satisfied; Equipped with the determination condition includes an increase in a detected temperature detected by the temperature detection element, The circuit includes, as the capacitive element, a first capacitor connected between a pair of input terminals of the circuit; a second capacitor connected between a pair of output terminals of the circuit; Including, the resonance frequency setting unit is provided in the circuit between a higher potential input terminal of the pair of input terminals and a higher potential output terminal of the pair of output terminals, The temperature detection element includes: a first temperature detection element for detecting a temperature of the first capacitor; a second temperature detection element for detecting a temperature of the second capacitor; Equipped with The judgment condition is: A first detected temperature detected by the first temperature detection element increases; and A second detected temperature detected by the second temperature detection element increases; and Including both Resonant current limiting system.

7. A temperature detection element for detecting a temperature of a capacitive element in a circuit including an inductance element and a capacitive element; a resonant frequency setting unit that is provided in series with the capacitive element in the circuit and that variably sets a resonant frequency of the circuit; a resonance control unit that controls the resonance frequency setting unit to change the resonance frequency of the circuit when a determination condition is satisfied; Equipped with the determination condition includes an increase in a detected temperature detected by the temperature detection element, The resonance control unit is When the determination condition is satisfied, the resonant frequency setting unit is controlled to change the resonant frequency of the circuit from a first frequency to a second frequency; When a release condition is satisfied, the resonant frequency setting unit is controlled to change the resonant frequency of the circuit from the second frequency to the first frequency; the release condition includes that the detected temperature is equal to or lower than a release temperature. Resonant current limiting system.

8. A temperature detection element for detecting a temperature of a capacitive element in a circuit including an inductance element and a capacitive element; a resonant frequency setting unit that is provided in series with the capacitive element in the circuit and that variably sets a resonant frequency of the circuit; a resonance control unit that controls the resonance frequency setting unit to change the resonance frequency of the circuit when a determination condition is satisfied; Equipped with the determination condition includes an increase in a detected temperature detected by the temperature detection element, an abnormal temperature detection unit that detects whether the detected temperature has risen to or above an abnormality determination threshold temperature; a notification unit that notifies an outside source that the detected temperature has reached or exceeded the abnormality determination threshold temperature; Further comprising: Resonant current limiting system.

9. The circuit has a pair of connection terminals as a pair of input terminals or a pair of output terminals, the capacitive element is connected between the pair of connection terminals, The resonant current limiting system comprises: a cutoff switch connected in series with the capacitive element between the pair of connection terminals; a cutoff control unit that switches the cutoff switch from on to off when the abnormal temperature detection unit detects that the detected temperature is equal to or higher than the abnormality determination threshold temperature; Further comprising:

9. The resonant current limiting system of claim 8.

10. The resonant frequency setting unit: A first pathway; A second path connected in parallel to the first path; A switch provided in the first path; Equipped with an inductance of an inductance component in the first path is different from an inductance of an inductance component in the second path, The resonance control unit switches the switch on and off when the determination condition is satisfied. A resonant current limiting system according to any one of the preceding claims.

11. A temperature detection element for detecting a temperature of a capacitive element in a circuit including an inductance element and a capacitive element; a resonant frequency setting unit that is provided in series with the capacitive element in the circuit and that variably sets a resonant frequency of the circuit; a resonance control unit that controls the resonance frequency setting unit to change the resonance frequency of the circuit when a determination condition is satisfied; Equipped with the determination condition includes an increase in a detected temperature detected by the temperature detection element, The resonance frequency setting unit is A first pathway; A second path connected in parallel to the first path; A switch provided in the first path; Equipped with an inductance of an inductance component in the first path is different from an inductance of an inductance component in the second path, The resonance control unit switches the switch on and off when the determination condition is satisfied, an inductance of the inductance component in the second path is greater than an inductance of the inductance component in the first path; The resonance frequency setting unit is a second switch provided in the second path separately from the first switch, The resonance control unit switches the first switch from on to off and switches the second switch from off to on when the determination condition is satisfied. Resonant current limiting system.

12. When the determination condition is satisfied, the resonance control unit switches the first switch from on to off after a delay time has elapsed since switching the second switch from off to on.

12. The resonant current limiting system of claim 11.

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