JP2017138212A - Self-power-fed current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-power-fed current sensor which is easy to manage and which easily stabilizes the operation a current detection unit and increases the accuracy of current detection.SOLUTION: Provided is a self-power-fed current sensor 1 comprising: a sensor unit 10 attachable to a detection object 90 of current detection; a current detection unit 30 connected to the sensor unit 10, for performing current detection operation to detect a current flowing through the detection object 90; a power storage unit 20 for performing power storage operation to store the electric power obtained from the detection object 90 via the sensor unit 10; and a control unit 80 for controlling the current detection unit 30. The control unit 80 determines a detection cycle on the basis of the magnitude of a detected current so that the detection cycle that is a cycle of the current detection operation becomes longer in correspondence to a decrease in the magnitude of the detected current and becomes shorter in correspondence to an increase in the magnitude of the detected current, and causes the current detection operation to be cyclically repeated by the current detection unit 30 in accordance with the determined detection cycle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a self-powered current sensor, and more particularly, a self-comprising sensor unit, a power storage unit that performs a power storage operation, a current detection unit that performs a current detection operation, and a control unit that controls the current detection unit. The present invention relates to a power supply type current sensor.

  In recent years, as a current sensor for detecting a current flowing through a detection target such as wiring for supplying AC power, a sensor unit that can be attached to the detection target for current detection, and electric power obtained from the detection target via the sensor unit. A power storage unit that performs a power storage operation for storing power, a current detection unit that performs a current detection operation that detects a current flowing through the detection target connected to the sensor unit, and a control unit that controls the current detection unit. There has been proposed a self-feeding type current sensor that uses the obtained electric power to detect a current flowing through a detection target and does not require battery replacement.

  For a conventional self-powered current sensor, Patent Document 1 and the like are disclosed. Hereinafter, the configuration of a conventional self-powered current sensor will be described with reference to FIG. FIG. 10 is an explanatory diagram showing a configuration of a conventional self-powered current sensor, and shows a configuration of a current measuring device 540 according to Patent Document 1. In FIG.

  As shown in FIG. 10, the current measurement device 540 includes a power storage unit 550 and a measurement unit 551. The power storage unit 550 includes a first current sensor 520 (sensor unit), a first rectifier circuit 522, and a power storage circuit 523 (power storage unit). The measurement unit 551 includes a second current sensor 521 (sensor unit), a second rectifier circuit 527, a resistor 524 (detection resistor), an integrated circuit 525, and a communication antenna 526. The

  The first current sensor 520 includes a magnetic core 520A and a coil 520B, and can detect a detection target with a gap 520C. The second current sensor 521 has a magnetic core 521A and a coil 521B, and can sandwich a detection target with a gap 521C.

  The first current sensor 520 is attached to the detection target and converts magnetism generated by the current flowing through the detection target into an electrical signal. The first rectifier circuit 522 rectifies the electrical signal output from the first current sensor 520 and converts it into electric power that can be stored. The power storage circuit 523 stores the power obtained via the first current sensor 520 and the first rectifier circuit 522 and supplies power to the measurement unit 551.

  The second current sensor 521 is attached to the detection target similarly to the first current sensor 520, and converts the magnetism generated by the current flowing through the detection target into an electrical signal. The second rectifier circuit 527 rectifies the electrical signal output from the second current sensor 521 and converts it into a DC electrical signal. The resistor 524 is connected to the output terminal of the second rectifier circuit 527, and the integrated circuit 525 detects the current flowing through the detection target based on the voltage across the resistor 524, and the output signal of the detection circuit Calculation operation for calculating the current value of the current flowing through the detection target based on the above, a transmission operation for wirelessly transmitting the calculated current value to the outside via the antenna 526, and a control operation for controlling the detection circuit and the communication circuit Is going.

  In this way, the current measuring device 540 detects the current flowing through the detection target by using the electric power obtained from the detection target via the first current sensor 520 and the first rectifier circuit 522. Although not disclosed in Patent Document 1, normally, the current detection operation for detecting the current flowing through the detection target is periodically executed in accordance with a certain detection cycle.

JP 2014-153184 A

  By the way, the current flowing through the detection target in which such a current sensor is used is not always constant, and may vary greatly depending on the current sensor installation environment (installation location, time zone, electrical appliances connected to the detection target, etc.). Yes. However, in the conventional current sensor, the current detection operation is repeated according to a certain detection cycle, so that the power consumption of the current detection unit and the frequency of the current detection operation are optimized according to the magnitude of the current flowing through the detection target. This could cause the operation of the current detection unit to become unstable and reduce the current detection accuracy.

  That is, if the detection cycle is set to be short in accordance with the state where the current flowing through the detection target is large, when the state where the current flowing through the detection target is small continues for a long time, the power storage unit cannot store sufficient power, and the current detection unit There is a possibility that the current detector can become unstable due to insufficient power that can be supplied. On the other hand, if the detection current is set to be long in accordance with the state where the current flowing through the detection target is small, even if the current flowing through the detection target, which is a particularly important state for accurately grasping the power consumption, is large, There was a possibility that current could not be detected with sufficient frequency, leading to a decrease in current detection accuracy.

  Although it is possible for the user to manually switch the detection cycle in accordance with the installation environment of the current sensor, the operation associated with the switching operation of the user is required, and the management of the current sensor tends to be complicated. .

  The present invention has been made in view of the situation of the prior art as described above, and an object thereof is a self-feeding type that is easy to manage and can easily stabilize the operation of the current detection unit or increase the accuracy of current detection. A current sensor is provided.

  In order to solve this problem, a self-powered current sensor according to claim 1 includes a sensor unit that can be attached to a detection target for current detection, and electric power obtained from the detection target via the sensor unit. A power storage unit that performs a power storage operation for storing power, a current detection unit that performs a current detection operation that detects a current flowing through the detection target connected to the sensor unit, and a control unit that controls the current detection unit. In the self-powered current sensor, the control unit, based on the magnitude of the detected current, the detection period that is the period of the current detection operation becomes longer as the magnitude of the current becomes smaller, The detection period is determined such that the detection period becomes shorter as the current magnitude increases, and the current detection operation is repeated by the current detection unit according to the determined detection period.

  In the self-powered current sensor of this configuration, the detection cycle can be changed according to the magnitude of the current flowing through the detection target, so the power consumption and current detection of the current detection unit can be adjusted according to the installation environment of the current sensor. Can be optimized, the operation of the current detector can be stabilized, and the accuracy of current detection can be increased. That is, when the current flowing through the detection target is in a small state, the detection cycle is lengthened so that a time for the power storage unit to store sufficient power is secured, thereby stabilizing the operation of the current detection unit. Become. In addition, when the current flowing through the detection target is large, the detection cycle is shortened to increase the frequency of current detection, thereby improving the current detection accuracy. In addition, the detection of the current to be detected, the determination of the detection cycle, and the control of the current detection unit can be performed together inside the current sensor, so there is no need for the user to manually switch the detection cycle. Thus, the current sensor can be easily managed.

  The self-powered current sensor according to claim 2, wherein the control unit causes the current detection unit to perform initial detection of the current, and a magnitude of the current detected in the initial detection. In accordance with a procedure including a second step of determining the detection cycle based on the second step and a third step of causing the current detection unit to repeat the current detection operation according to the determined detection cycle, the current detection unit A current detection operation is performed.

  In the self-powered current sensor with this configuration, after setting based on the result of initial detection, there is no need to determine the detection cycle or change the operation timing according to the change of the detection cycle. Compared to the case where the detection cycle is determined each time the operation is performed, the number of times of determination of the detection cycle, change of operation timing, and the like can be reduced. As a result, management of the current sensor is further facilitated.

  The self-powered current sensor according to claim 3 further includes a switching circuit unit that switches a connection state between the sensor unit and the current detection unit in accordance with the detection cycle.

  The self-powered current sensor with this configuration suppresses unnecessary current from flowing from the sensor unit to the current detection unit during power storage operation by switching the connection state between the sensor unit and the current detection unit according to the detection cycle. Thus, the power storage efficiency can be increased.

  The self-powered current sensor according to claim 4, further comprising a wireless transmission unit that wirelessly transmits data including the detection result of the current to the outside, and the control unit adjusts the magnitude of the detected current. Then, the period of wireless transmission of the data is changed.

  The self-powered current sensor having this configuration can wirelessly transmit data including the result of current detection to the outside by the wireless transmission unit, eliminating the need for wiring connection to the outside and increasing the degree of freedom in arranging the current sensor. It becomes easy to raise. In addition, by changing the period of wireless transmission of data according to the detected current magnitude, the power consumption of the wireless transmission unit can be optimized according to the installation environment of the current sensor. It becomes easy to stabilize the operation. Moreover, by changing the period of wireless transmission of data according to the detected current magnitude, the operation of the wireless transmission unit is optimized according to the installation environment of the current sensor, and the operation of the wireless transmission unit is stabilized. , Information transmission to the outside can be performed more reliably.

  The self-powered current sensor according to claim 5, wherein the current detection unit includes a detection resistor for current detection, and the control unit adjusts the detection resistor according to the magnitude of the detected current. The resistance value is changed.

  In the self-powered current sensor with this configuration, the voltage at both ends of the detection resistor is optimized by changing the resistance value of the detection resistor according to the magnitude of the current detected by the control unit, and the current detection accuracy is improved. It is possible to improve or suppress damage of the detection resistor due to overcurrent.

  The self-feeding type current sensor according to claim 6, wherein the current detection unit includes an amplification circuit for signal amplification, and the control unit is configured to adjust the amplitude of the amplification circuit according to the detected magnitude of the current. It is characterized by changing the gain.

  In the self-powered current sensor with this configuration, the gain of the amplifier circuit is optimized by changing the gain of the amplifier circuit according to the magnitude of the detected current, and the current detection accuracy is improved. Can do.

  According to the present invention, it is possible to provide a self-feeding type current sensor that is easy to manage and can easily stabilize the operation of the current detection unit and increase the accuracy of current detection.

It is explanatory drawing which shows the circuit structure of the current sensor which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the circuit structure of the electrical storage part which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the circuit structure of the electric current detection part which concerns on 1st Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of the current sensor which concerns on 1st Embodiment of this invention. It is explanatory drawing regarding the control action of the control part which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the circuit structure of the electric current detection part which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the circuit structure of the electric current detection part which concerns on 3rd Embodiment of this invention. It is explanatory drawing which shows the circuit structure of the current sensor which concerns on the 1st modification of this invention. It is explanatory drawing which shows the circuit structure of the current sensor which concerns on the 2nd modification of this invention. It is explanatory drawing which shows the structure of the conventional current sensor.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 is an explanatory diagram showing a circuit configuration of a current sensor 1 according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing a circuit configuration of the power storage unit 20 according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram showing the circuit configuration of the current detection unit 30 according to the first embodiment of the present invention, together with the switching element unit 41 of the switching circuit unit 40.

  FIG. 4 is a flowchart showing an operation procedure of the current sensor 1 according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram relating to the control operation of the control unit 80 according to the first embodiment of the present invention. FIG. 5A is a diagram illustrating a relationship between the current value Is0 and the detection cycle Ts. FIG. 5B is a timing chart showing operation timings of the power storage operation of the power storage unit 20, the current detection operation of the current detection unit 30, and the switching operation of the switching circuit unit 40.

  FIG. 6 is an explanatory diagram showing a circuit configuration of the current detection unit 130 according to the second embodiment of the present invention. FIG. 7 is an explanatory diagram showing a circuit configuration of the current detection unit 230 according to the third embodiment of the present invention. FIG. 8 is an explanatory diagram showing a circuit configuration of the current sensor 301 according to the first modification of the present invention. FIG. 9 is an explanatory diagram showing a circuit configuration of the current sensor 401 according to the second modification of the present invention.

[First Embodiment]
First, the configuration of the current sensor 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The current sensor 1 according to the first embodiment of the present invention is a self-feeding type current sensor that detects current flowing through a detection target using power obtained from the detection target such as wiring for supplying AC power. 1, the sensor unit 10, the power storage unit 20, the current detection unit 30, the switching circuit unit 40, the voltage detection unit 50, the constant voltage circuit unit 60, the wireless transmission unit 70, and the control unit 80. Are further provided.

  The sensor unit 10 is an electromagnetic induction type sensor that can be attached to a detection target 90 called a CT sensor. As shown in FIG. 1, a magnetic core 11 made of a ferromagnetic metal or the like, and a magnetic core 11 The coil 12 has a wound coil 12 and output terminals 13 connected to both ends of the coil 12, respectively. The magnetic core 11 is attached to the detection target 90 so as to surround the detection target 90. The coil 12 generates an electrical signal corresponding to the magnitude of the current flowing through the detection target 90 using electromagnetic induction. The electrical signal generated by the coil 12 is output from the output terminal 13.

  As illustrated in FIG. 2, the power storage unit 20 includes a rectifier circuit 21 and a power storage element 22. The rectifier circuit 21 is connected to the sensor unit 10 and rectifies the output signal of the sensor unit 10 to convert it into an electrical signal that can be stored. The storage element 22 stores the output signal of the rectifier circuit 21 as electric power for supplying to other circuits. The rectifier circuit 21 includes, for example, four diode elements 21a that are bridge-connected. As the storage element 22, a large-capacity capacitive element of about several hundred μF to several mF is used. In this way, the power storage unit 20 performs a power storage operation of storing power obtained from the detection target 90 via the sensor unit 10. The power stored in the power storage unit 20 is supplied to the control unit 80 via the voltage detection unit 50 and the constant voltage circuit unit 60, and is further supplied from the control unit 80 to the current detection unit 30 and the wireless transmission unit 70. .

  As shown in FIG. 3, the current detection unit 30 includes a detection resistor 31 for current detection and an amplification circuit 32 for signal amplification. The detection resistor 31 is connected to the sensor unit 10 via the switching circuit unit 40 and generates a voltage corresponding to the output signal of the sensor unit 10 at both ends of the detection resistor 31. The amplifier circuit 32 is a differential amplifier circuit formed by connecting a resistor element or a capacitor element to the differential amplification amplifier IC 32a. The amplifier circuit 32 is supplied with the power supply voltage Vcc and the reference voltage Vref from the control unit 80, and is connected to the detection resistor 31. The voltage at both ends is amplified and output as a detection signal for calculating the current value. In this way, the current detection unit 30 performs a current detection operation of detecting the current flowing through the detection target 90 connected to the sensor unit 10. The detection signal output from the current detection unit 30 is transmitted to the control unit 80.

  The switching circuit unit 40 is interposed between the sensor unit 10 and the current detection unit 30 and performs a switching operation for switching the connection state between the sensor unit 10 and the current detection unit 30. In the present embodiment, the switching circuit unit 40 includes two switching element units 41 for switching the connection state between the sensor unit 10 and the current detection unit 30, as shown in FIG.

  As shown in FIG. 3, the switching element unit 41 includes a pair of N-channel MOSFET elements 41a and a Schottky barrier diode element 41b. Then, the source terminals of the pair of MOSFET elements 41a are connected to each other, the drain terminals are respectively switched to other elements, the gate terminals are connected to each other, and a switching control switching signal Vsw is input. This is an input terminal. Further, the anode terminal of the diode element 41b is connected to the gate terminal of the MOSFET element 41a, the cathode terminal is connected to the source terminal of the MOSFET element 41a, and the voltage of the source terminal of the MOSFET element 41a and the voltage of the gate terminal are reversed. It is preventing.

  Then, in response to the switching signal Vsw, the switching circuit unit 40 changes the connection state between the sensor unit 10 and the current detection unit 30, the first connection state where the current detection unit 30 is disconnected from the sensor unit 10, and the current The detection unit 30 is switched to the second connection state connected to the sensor unit 10. In the circuit configuration as in this embodiment, when the switching signal Vsw is in the Hi state (the potential is high), the connection state between the sensor unit 10 and the current detection unit 30 is the first connection state, and the switching is performed. When the signal Vsw is in the Lo state, the connection state between the sensor unit 10 and the current detection unit 30 is the second connection state.

  The voltage detection unit 50 detects the output voltage of the power storage unit 20 in order to grasp the power storage state of the power storage unit 20. The constant voltage circuit unit 60 converts the output voltage of the power storage unit 20 into a predetermined power supply voltage. The wireless transmission unit 70 includes a transmission antenna 71, and wirelessly transmits data including the detection result of the current detected by the current detection unit 30 to the outside via the transmission antenna 71.

  The control unit 80 is an integrated circuit for control called MCU (Micro Controller Unit), and performs various arithmetic operations and various control operations. The calculation operation performed by the control unit 80 includes a calculation operation for calculating a current value corresponding to the magnitude of the current flowing through the detection target 90 based on the detection signal output from the current detection unit 30, and a calculation operation based on the calculated current value. And an operation for calculating and determining a detection cycle which is a cycle of the current detection operation. In the following description, the magnitude of the current calculated by the above-described calculation operation is defined as a current value Is, and the detection cycle determined by the above-described calculation operation is described as a detection cycle Ts.

  The control operation performed by the control unit 80 includes a control operation for controlling the current detection unit 30 by transmitting the power supply voltage Vcc and the reference voltage Vref to the current detection unit 30, and a switching operation for transmitting the switching signal Vsw to the switching circuit unit 40. A control operation for controlling the circuit unit 40, a control operation for controlling the wireless transmission unit 70 by transmitting the power supply voltage Vcc and the calculated current value Is to the wireless transmission unit 70, and the like are included.

  Next, the operation of the self-powered current sensor 1 of the present embodiment will be described with reference to FIGS. The operation of the current sensor 1 is as shown in FIG. First, in step St <b> 1, the control unit 80 causes the switching circuit unit 40 to switch the connection state between the sensor unit 10 and the current detection unit 30 to the second connection state and connects the current detection unit 30 to the sensor unit 10. In step St1, it is assumed that sufficient power has already been stored in the power storage unit 20.

  Next, in step St2, the control unit 80 causes the current detection unit 30 to execute a current detection operation as an initial detection of the current flowing through the detection target 90. Next, in step St3, based on the detection signal from the current detection unit 30 in the initial detection, the control unit 80 calculates the current value Is0 as a current value corresponding to the magnitude of the current detected in the initial detection.

  Next, in step St4, the control unit 80 determines the detection cycle Ts based on the calculated current value Is0. In step St4, as shown in FIG. 5A, the control unit 80 increases the detection cycle Ts as the magnitude of the current detected in the initial detection becomes smaller based on the magnitude of the current value Is0. Thus, the detection cycle Ts is calculated so that the detection cycle Ts becomes shorter as the magnitude of the current detected in the initial detection becomes larger.

  Next, in step St <b> 5, the control unit 80 causes the switching circuit unit 40 to switch the connection state between the sensor unit 10 and the current detection unit 30 to the first connection state, and connects the power storage unit 20 to the sensor unit 10. Next, in step St6, the power storage unit 20 performs a power storage operation. Next, in step St7, the control unit 80 determines whether or not the detection timing has come based on the detection cycle Ts. If it is not the detection timing in step St6, the process returns to step St6 and the power storage operation of the power storage unit 20 is continued. If the detection timing comes in step St6, the process moves to step St8.

  Next, in step St8, the control unit 80 causes the switching circuit unit 40 to switch the connection state between the sensor unit 10 and the current detection unit 30 to the second connection state, and connects the current detection unit 30 to the sensor unit 10. . Next, in step St9, the control unit 80 causes the current detection unit 30 to execute a current detection operation. Next, in step St10, in conjunction with the current detection operation, the control unit 80 calculates the current value Is based on the detection signal from the current detection unit 30. Next, in step St11, in conjunction with the current detection operation and the calculation operation of the current value Is, the control unit 80 causes the wireless transmission unit 70 to wirelessly transmit data including the current detection result to the outside. In the present embodiment, the data to be wirelessly transmitted to the wireless transmission unit 70 is information on the current value Is calculated by the control unit 80, but the data to be wirelessly transmitted to the wireless transmission unit 70 includes other information. It does not matter.

  Next, in step St12, the control unit 80 determines whether or not to continue the current detection operation. When continuing the current detection operation in step St12, the process returns to step St5, and the storage operation, current detection operation, and wireless transmission operation are matched with the detection cycle Ts in the storage unit 20, current detection unit 30, and wireless transmission unit 70. And repeat. When the current detection operation is terminated in step St12, the control unit 80 stops each circuit of the current sensor 1 from a predetermined function, and the current detection operation is terminated.

  When the current sensor 1 operates in such a procedure, the switching circuit unit 40 switches according to the detection cycle Ts determined based on the magnitude of the current detected in the initial detection, as shown in FIG. The operation will be repeated. In accordance with the switching operation, the power storage unit 20 repeats the power storage operation, the current detection unit 30 repeats the current detection operation, and the wireless transmission unit 70 repeats the wireless transmission operation.

  Note that steps St1 to St3 in the above-described procedure are the first steps in which the control unit 80 causes the current detection unit 30 to perform initial detection of current. Step St4 is a second step for determining the detection cycle Ts based on the magnitude of the current detected in the initial detection. Further, Step St5 to Step St12 is a third step in which the current detection unit 30 repeats the current detection operation according to the determined detection cycle Ts.

  Next, the effect of this embodiment will be described. In the current sensor 1 of the present embodiment, the power of the current detection unit 30 is adjusted according to the installation environment of the current sensor 1 by changing the detection cycle Ts according to the current value Is0 corresponding to the magnitude of the current flowing through the detection target 90. The consumption and the frequency of current detection can be optimized to stabilize the operation of the current detection unit 30 and increase the accuracy of current detection. That is, when the current flowing through the detection target 90 is small, the detection cycle Ts is lengthened to secure time for the power storage unit 20 to store sufficient power, thereby stabilizing the operation of the current detection unit 30. Will be able to. Further, when the current flowing through the detection target 90 is large, the detection cycle Ts is shortened to increase the frequency of current detection, thereby improving the current detection accuracy. In addition, since the detection of the current of the detection target 90, the determination of the detection cycle Ts, and the control of the current detection unit 30 can be performed collectively in the current sensor 1, the user manually switches the detection cycle Ts. Therefore, the current sensor 1 can be easily managed.

  In the current sensor 1 of the present embodiment, the control unit 80 causes the current detection unit 30 to repeat the current detection operation according to the detection cycle Ts set based on the result of the initial detection. The detection cycle Ts may be determined each time it is performed, and the timing of the current detection operation and the wireless transmission operation may be reviewed every time in accordance with the determined detection cycle Ts. However, when the detection cycle Ts is calculated every time the current detection operation is performed and the timing of the current detection operation or the wireless transmission operation is reviewed, the calculation operation of the detection cycle Ts or the operation timing associated with the change of the detection cycle Ts Changes need to be made frequently, and management of the current sensor 1 tends to be complicated.

  On the other hand, in the current sensor 1 of the present embodiment, the control unit 80 causes the current detection unit to perform initial detection of current, and the detection cycle based on the magnitude of the current detected in the initial detection. The detection period Ts is changed according to a procedure including a second step for determining the current detection unit and a third step for causing the current detection unit to repeat the current detection operation according to the determined detection period. After performing the setting, it is not necessary to determine the detection cycle Ts or change the operation timing in accordance with the change of the detection cycle Ts, and the detection cycle Ts is calculated every time the current detection operation is performed. In comparison, it is possible to reduce the number of times of calculation of the detection cycle Ts, change of operation timing, and the like. As a result, management of the current sensor 1 is further facilitated. Such a current sensor 1 is particularly suitable when the installation environment after the current sensor 1 is installed is stable.

  Further, in the current sensor 1 of the present embodiment, an unnecessary current is transferred from the sensor unit 10 to the current detection unit 30 during the power storage operation by switching the connection state between the sensor unit 10 and the current detection unit 30 according to the detection cycle Ts. Can be prevented from flowing, and the storage efficiency can be increased.

  In addition, since the current sensor 1 according to the present embodiment can wirelessly transmit data including the result of current detection to the outside by the wireless transmission unit 70, wiring connection with the outside is unnecessary, and the arrangement of the current sensor 1 is free. It becomes easy to raise the degree. Moreover, the control unit 80 allows the wireless transmission unit 70 to wirelessly transmit data in conjunction with the current detection operation, so that the data transmission cycle can be changed according to the magnitude of the current detected in the initial detection. become. Then, by changing the data transmission cycle according to the detected current magnitude, the operation of the wireless transmission unit 70 can be optimized according to the installation environment of the current sensor 1. In other words, when the current flowing through the detection target 90 is small, the data transmission cycle is lengthened together with the detection cycle Ts to secure time for the power storage unit 20 to store sufficient power, and thereby the wireless transmission unit 70 When the operation is stable or the current flowing through the detection target 90 is large, the data transmission cycle is shortened together with the detection cycle Ts to increase the frequency of wireless transmission, thereby more reliably transmitting information to the outside. Can be.

[Second Embodiment]
Next, the configuration of the current sensor 101 according to the second embodiment of the present invention will be described with reference to FIG. In addition, in this embodiment, when it is the same structure as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 6, the current sensor 101 according to the second embodiment of the present invention is obtained by replacing the current detection unit 30 of the current sensor 1 in the first embodiment with a current detection unit 130. These are obtained by replacing the detection resistor 31 of the current detection unit 30 with the detection resistor 131. The detection resistor 131 is a variable resistance value type detection resistor configured by connecting a plurality of resistor elements 131a and a switching element 131b using a semiconductor element or the like connected in series.

  In this embodiment, the control unit 80 (not shown) calculates the current value Is0 based on the magnitude of the current detected in the initial detection, and detects in the initial detection based on the calculated current value Is0. The resistance value Rs of the detection resistor 131 is changed so that the resistance value increases as the magnitude of the detected current decreases, and the resistance value decreases as the magnitude of the current detected in the initial detection increases. .

  Next, the effect of this embodiment will be described. In the current sensor 101 of the present embodiment, the control unit 80 can optimize the voltage across the detection resistor by changing the resistance value of the detection resistor in accordance with the magnitude of the current detected in the initial detection. That is, when the magnitude of the current detected in the initial detection is small, the resistance value Rs is increased, the voltage across the detection resistor 131 is increased to increase the sensitivity of the detection signal, and the magnitude of the current detected in the initial detection is increased. When the resistance value is large, the resistance value Rs can be reduced, and the voltage across the detection resistor 131 can be reduced to suppress distortion of the amplifier circuit. As a result, the current detection accuracy can be improved. Further, when the magnitude of the current detected in the initial detection is large, the resistance value Rs is decreased, the voltage at both ends of the detection resistor 31 is decreased, and the heat generation of the detection resistor 31 due to the current flowing through the detection resistor 31 is accompanied. It is also possible to prevent the detection resistor 31 from being damaged.

[Third Embodiment]
Next, the configuration of the current sensor 201 according to the second embodiment of the present invention will be described with reference to FIG. In addition, in this embodiment, when it is the same structure as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 7, the current sensor 201 according to the third embodiment of the present invention is obtained by replacing the current detection unit 30 of the current sensor 1 in the first embodiment with a current detection unit 230. These are obtained by replacing the amplifier circuit 32 of the current detection unit 30 with the amplifier circuit 132. The amplifier circuit 132 is an amplifier circuit having a two-stage configuration that includes an amplifier IC 132a that is a first-stage amplifier IC and an amplifier IC 132b that is a second-stage amplifier IC. The amplifier circuit 132 can obtain output signals from both the amplifier IC 132a and the amplifier IC 132b. Depending on which output signal is transmitted to the control unit 80 (not shown) as a detection signal. The gain of the amplifier circuit 132 can be varied.

  In this embodiment, the control unit 80 (not shown) calculates the current value Is0 based on the magnitude of the current detected in the initial detection, and detects in the initial detection based on the calculated current value Is0. The gain of the amplifying circuit 132 is changed so that the gain increases as the magnitude of the detected current decreases, and the gain decreases as the magnitude of the current detected in the initial detection increases.

  Next, the effect of this embodiment will be described. In the current sensor 201 of the present embodiment, the gain of the amplifier circuit can be optimized by changing the gain of the amplifier circuit in accordance with the magnitude of the current detected in the initial detection. That is, when the magnitude of the current detected in the initial detection is small, the gain of the amplifier circuit 132 is increased to increase the sensitivity of the detection signal. When the magnitude of the current detected in the initial detection is large, the gain of the amplifier circuit 132 is increased. The gain can be reduced and distortion of the amplifier circuit can be suppressed. As a result, the current detection accuracy can be improved.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to said embodiment, As long as it does not deviate from the summary of this invention, it can change suitably. Hereinafter, modified examples of the present invention will be described with reference to FIGS.

  In the embodiment of the present invention, the circuit configuration of each part of the current sensor 1 to the current sensor 201 may be appropriately changed. For example, if a predetermined switching operation is possible, the switching element unit 41 of the switching circuit unit 40 is connected only to one output terminal 13 of the sensor unit 10 like the current sensor 301 according to the first modification shown in FIG. The other output terminal 13 of the sensor unit 10 may be directly connected to the current detection unit 30. Further, like the current sensor 401 according to the second modification shown in FIG. 8, the switching element unit 41 is interposed between the sensor unit 10 and the current detection unit 30, and between the sensor unit 10 and the power storage unit 20. One of the power storage unit 20 and the current detection unit 30 may be connected to the sensor unit 10 with the switching element unit 42 interposed therebetween.

  Although not shown, in the embodiment of the present invention, if a predetermined switching operation is possible, the switching circuit unit 40 may have a circuit configuration other than that described above, and the switching element unit 41 may include a MOSFET element. Alternatively, a bipolar transistor element, a switching IC in which a large number of semiconductor elements are integrated, an element such as a photocoupler, an electromagnetic relay, or the like may be used.

  Further, in the embodiment of the present invention, as long as a predetermined power storage operation is possible, the power storage unit 20 may have a circuit configuration other than that described above, and the power storage element 22 may be a secondary battery other than those described above. It may be an element.

  In the embodiment of the present invention, if a predetermined current detection operation is possible, the current detection unit 30 may have a circuit configuration other than that described above, and an amplifier circuit using a bipolar transistor element, an FET element, or the like. It does not matter. The current detection unit 30 may output a digitized detection signal instead of an analog detection signal. Further, the detection resistor 131 in the second embodiment of the present invention may be a variable resistance element capable of continuously changing the resistance value. The amplifier circuit 232 in the third embodiment of the present invention may be a variable gain amplifier circuit.

  Further, in the embodiment of the present invention, the voltage detector 50 may be omitted if a reliable power storage operation is possible. Further, the constant voltage circuit unit 60 may not be provided as long as the control unit 80 can stably operate. In addition, the wireless transmission unit 70 may wirelessly transmit information other than the current detection result, and the wireless transmission unit 70 may be omitted as long as information transmission to the outside is possible with a wire.

  In the embodiment of the present invention, as long as a predetermined function can be realized, the current sensor 1 may be operated according to procedures other than those described above. For example, when the installation environment after the current sensor 1 is frequently changed, every time the current detection operation is performed, the calculation of the detection cycle Ts and the review of the timing of the current detection operation and the wireless transmission operation are performed. You can do it every time. Further, every time the current detection operation is performed a plurality of times, the calculation of the detection cycle Ts and the review of the timing of the current detection operation and the wireless transmission operation may be performed periodically. The same applies to the change in the resistance value Rs of the detection resistor 131 in the second embodiment and the frequency of the gain change in the amplifier circuit 232 in the third embodiment.

  In the embodiment of the present invention, as shown in FIG. 5A, the control unit 80 calculates the detection cycle Ts so that the detection cycle Ts changes stepwise corresponding to the change in the current value Is0. However, if a predetermined function can be realized, the detection cycle Ts is calculated so that the detection cycle Ts changes linearly corresponding to the change in the current value Is0, a quadratic curve, a cubic curve, or the like. The detection period Ts may be calculated so as to change along the line. The control unit 80 does not determine the detection cycle Ts by calculation, but stores a table in which the detection cycle Ts corresponding to the current value Is0 is determined in advance in a storage element or the like, and refers to the table to determine the current. The detection cycle Ts may be selected and determined from the value Is0.

  In the embodiment of the present invention, the current sensor 1 to the current sensor 201 may further include circuits other than those described above. In addition, the current sensor 1 to the current sensor 201 may be attached to a detection target other than those described above.

DESCRIPTION OF SYMBOLS 1 Current sensor 10 Sensor part 11 Magnetic body core 12 Coil 13 Output terminal 20 Power storage part 21 Rectifier circuit 21a Diode element 21b Capacitance element 22 Electric power storage element 30 Current detection part 31 Detection resistance 32 Amplification circuit 32a Amplifier IC
DESCRIPTION OF SYMBOLS 40 Switching circuit part 41 Switching element unit 41a MOSFET element 41b Diode element 42 Switching element unit 50 Voltage detection part 60 Constant voltage circuit part 70 Wireless transmission part 71 Transmitting antenna 80 Control part 101 Current sensor 130 Current detection part 131 Detection resistance 131a Resistance Element 131b Switching element 201 Current sensor 230 Current detector 232 Amplifier circuit 232a Amplifier IC
232b Amplifier IC
301 Current sensor 401 Current sensor

Claims (6)

A sensor unit that can be attached to a detection target of current detection;
A power storage unit that performs a power storage operation of storing power obtained from the detection target via the sensor unit;
A current detection unit that is connected to the sensor unit and detects a current flowing through the detection target;
A self-powered current sensor comprising a control unit for controlling the current detection unit,
The controller is
Based on the magnitude of the detected current, the detection period that is the period of the current detection operation becomes longer as the magnitude of the current becomes smaller, and the detection period becomes shorter as the magnitude of the current becomes larger. Determine the detection period as
A self-feeding type current sensor, wherein the current detection unit is made to repeat the current detection operation according to the determined detection cycle. The controller is
A first step for causing the current detection unit to perform initial detection of the current;
A second step of determining the detection period based on the magnitude of the current detected in the initial detection;
According to a procedure including a third step of causing the current detection unit to repeat the current detection operation according to the determined detection cycle,
The self-feeding current sensor according to claim 1, wherein the current detection unit performs the current detection operation.   The self-powered current sensor according to claim 1, further comprising a switching circuit unit that switches a connection state between the sensor unit and the current detection unit in accordance with the detection cycle. A wireless transmission unit for wirelessly transmitting data including the current detection result to the outside;
4. The self-feeding current according to claim 1, wherein the control unit changes a period of wireless transmission of the data in accordance with the detected magnitude of the current. 5. Sensor. The current detection unit has a detection resistor for current detection,
5. The self-powered current sensor according to claim 1, wherein the control unit changes a resistance value of the detection resistor in accordance with the magnitude of the detected current. 6. The current detection unit has an amplification circuit for signal amplification,
6. The self-powered current sensor according to claim 1, wherein the control unit changes a gain of the amplifier circuit in accordance with the detected magnitude of the current.