JP2004045236A - Overcurrent sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To utilize characteristics in an electronic circuit, to improve prearcing time-current characteristics instead of a fuse for large currents, and at the same time to achieve a current protection function even to a use where a variation in load is large. <P>SOLUTION: The overcurrent sensor detects current to be measured in a current path passing through the inside of a magnetic material where a gap is formed in a closed magnetic circuit, and controls time to break according to the size. The overcurrent sensor comprises: Hall elements 2A, 2B installed in the gap; an inversely proportional voltage generation means 3 for making constant a Hall output voltage in the Hall element 2A, controlling a control current, and obtaining the output voltage being inversely proportional to the current to be measured; a current conversion means 4 for outputting the output current being proportional to the Hall output voltage in the Hall element 2B where the control current is constant; a charge voltage generation means 5 for charging the output current to a capacitor C3; and a comparison means 6 for comparing the output voltage of the inversely proportional voltage generation means 3 with a charge voltage in the charge voltage generation means 5 and for outputting a breaking signal when the charge voltage exceeds the output voltage of the inversely proportional voltage generation means 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used as a substitute for a fuse that cuts off a circuit when an abnormally large current flows in a battery of a hybrid vehicle or an electric vehicle. In particular, a fuse function of 100 to 1000 A class is replaced by an electronic circuit. The present invention relates to an overcurrent sensor that can be provided in a small size and at low cost.
[0002]
[Prior art]
Conventionally, a method of detecting an overcurrent using a fuse as disclosed in Japanese Utility Model Registration No. 2565750 and Japanese Patent Application Laid-Open No. 2001-54223 is known.
[0003]
[Problems to be solved by the invention]
The biggest problems with fuses are that they have large variations, and that the ideal shutoff function for protecting wiring and systems from thermal damage due to overcurrent in the event of a short circuit is unsatisfactory. When a short circuit occurs, heat is generated in proportion to the product of the resistance value of the wiring or system, the square of the short circuit current, and the holding time.From the viewpoint of thermal protection, consider setting the temperature so that it does not exceed a certain temperature. It is desirable not to interrupt the instantaneous current that does not exceed the maximum current value but to interrupt the current in a time inversely proportional to the square of the current value when a current exceeding the upper limit current value flows.
[0004]
FIG. 4 shows the breaking characteristics of a general high-current fuse. It can be seen that the fusing time is inversely proportional to the fifth to sixth powers of the current value. In other words, the larger the current, the earlier the blow (the earlier the time is inversely proportional to the square of the short-circuit current), and it is surprisingly difficult to set the fuse so that it does not blow with a surge current that is not a problem. Fuses have been difficult elements to protect applications.
[0005]
A first object of the present invention is to use a characteristic of an electronic circuit, replace a fuse for a large current, improve a fusing characteristic, and realize an overcurrent capable of realizing a current protection function even in an application in which load changes are severe. It is to provide a sensor.
[0006]
A second object of the present invention is to provide an overcurrent sensor capable of realizing a current breaker function capable of restoring in place of a fuse that cannot be reproduced.
[0007]
Other objects and novel features of the present invention will be clarified in embodiments described later.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application detects a measured current passing through a current path penetrating the inside of a magnetic body having a gap formed in a part of a closed magnetic circuit, and detects the measured current. In the overcurrent sensor that controls the time until the interruption by the size of
First and second Hall elements installed in the gap of the magnetic body,
Inverse proportional voltage generation means for controlling a control current of the first Hall element so that a Hall output voltage of the first Hall element is constant to obtain an output voltage inversely proportional to the measured current;
Current conversion means for outputting an output current proportional to a Hall output voltage of the second Hall element, wherein the control current is controlled to be constant;
Charging voltage generating means for charging an output current of the current converting means to a capacitor having a constant capacity to obtain a charging voltage thereof,
An output voltage of the inversely proportional voltage generator is inversely proportional to the current to be measured, and a charge voltage of the charge voltage generator is compared. When the charge voltage exceeds an output voltage of the inverse proportional voltage generator, a cutoff signal is generated. And a comparing means for holding the data.
[0009]
Further, the invention of claim 2 of the present application detects a measured current passing through a current path penetrating the inside of a magnetic body having a gap formed in a part of a closed magnetic circuit, and shuts off the current based on the magnitude of the measured current. In the overcurrent sensor that controls the time until
Two magnetic bodies are provided for the current path, a first Hall element installed in a gap of one magnetic body and a second Hall element installed in a gap of the other magnetic body,
Inverse proportional voltage generation means for controlling a control current of the first Hall element so that a Hall output voltage of the first Hall element is constant to obtain an output voltage inversely proportional to the measured current;
Current conversion means for outputting an output current proportional to a Hall output voltage of the second Hall element, wherein the control current is controlled to be constant;
Charging voltage generating means for charging an output current of the current converting means to a capacitor having a constant capacity to obtain a charging voltage thereof,
An output voltage of the inversely proportional voltage generator is inversely proportional to the current to be measured, and a charge voltage of the charge voltage generator is compared. When the charge voltage exceeds an output voltage of the inverse proportional voltage generator, a cutoff signal is generated. And a comparing means for holding the data.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an overcurrent sensor according to the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a block diagram showing a first embodiment of an overcurrent sensor according to the present invention, and FIG. 2 is a perspective view showing an arrangement of a Hall element with respect to a magnetic body. As shown in FIGS. 1 and 2, the overcurrent sensor includes a magnetic body 1, first and second Hall elements 2A and 2B, an inversely proportional voltage generator 3, a current converter 4, a charging voltage generator 5, and a comparator. 6 is provided.
[0012]
As shown in FIG. 2, the magnetic body 1 has a substantially C shape in which a gap G is formed in a part of a closed magnetic circuit, and two Hall elements 2A and 2B are installed in the same gap G. The bus bar 7 serving as a current path penetrates the center of the inner side. The bus bar 7 is supplied with a measured current Ib such as a battery supply current. For example, a current of 100 A or less flows in a normal state and a current of 1000 A flows in an abnormal state. When a current to be measured flows through the bus bar 7, a magnetic flux generated in the closed magnetic circuit of the magnetic body 1 due to the current to be measured passes through the first and second Hall elements 2A and 2B.
[0013]
The inverse voltage generating means 3 is output voltage which is inversely proportional to the control current I _CA control to the measured current Ib of the first Hall element 2A of the Hall output voltage V _HA is first to be constant of the Hall element 2A the vr, those obtained at both ends of the control current I _CA path inserted a resistor R1. In general, if the control current is constant, the Hall element outputs a Hall output voltage proportional to the magnetic flux density at the position where the control element is disposed (that is, proportional to the current value to be measured). as the inverse voltage generating means 3, by controlling the control current I _CA as Hall output voltage V _HA is constant, the control current I _CA will be inversely proportional to the current value to be measured, control current I _CA If the voltage drop is obtained by inserting the resistor R1 into the current path, it becomes a voltage value that is inversely proportional to the current value to be measured.
[0014]
On the other hand, the second Hall element 2B is the control current I _CB are controlled to a constant current value, therefore, it (proportional to That measured current value Ib) proportional to the magnetic flux density of the deployed position Hall output The voltage _VHB is output.
[0015]
The current converting means 4 receives the Hall output voltage VHB of the second Hall element 2B and outputs an output current proportional to the Hall output voltage _VHB. The capacitor C3 having a capacity is charged. The discharge resistor R12 is connected in parallel with the capacitor C3, a state that does not detect the output current is small regions (overcurrent of the current conversion unit 4, that is, the Hall output voltage V _HB of the Hall element 2B small state In ()), the discharging resistor R12 is set so that the charging voltage of the capacitor C3 does not increase.
[0016]
The comparing means 6 compares the charging voltage of the capacitor C3 of the charging voltage generating means 5 with the output voltage Vr of the inversely proportional voltage generating means 3, and when the charging voltage of the capacitor C3 exceeds the output voltage Vr, a cutoff signal. (An overcurrent detection signal indicating that an overcurrent has been detected, for example, a high level output) is output to the output terminal Vout and has a function of continuing to hold the cutoff signal.
[0017]
In the first embodiment, when the current to be measured flowing through the bus bar 7 in FIG. 2 is in the steady range, the magnetic flux density applied to the Hall elements 2A and 2B disposed in the same gap G is low, and the Hall element 2A The output voltage Vr, which is inversely proportional to the current to be measured, of the inversely proportional voltage generation means 3 for controlling the Hall output voltage V _HA to be constant has a high voltage value. Contrary to this, the control current I _CB Hall output voltage V _HB of the Hall element 2B, which is controlled to be constant is small, this output current of the current converter 4 in proportion is weak, it is discharged by the discharge resistor R12 The charging voltage of the capacitor C3 of the charging voltage generating means 5 does not rise to a voltage value exceeding the output voltage Vr. For this reason, the comparison means 6 does not detect an overcurrent and does not generate a cutoff signal (overcurrent detection signal).
[0018]
On the other hand, if an overcurrent flows through the bus bar 7, the magnetic flux density applied to the Hall elements 2A and 2B becomes several times or more of the steady state, and the inverse proportional voltage generation means 3 for controlling the Hall output voltage V _HA of the Hall element 2A to be constant. The output voltage Vr that is inversely proportional to the current to be measured has a low voltage value (approaches the ground level). On the other hand, the Hall output voltage V _HB of the Hall element 2B in which the control current I _CB is controlled to be constant increases, and the output current of the current conversion means 4 increases in proportion to this, and the discharge current by the discharge resistor R12 is reduced. In the meantime, the charging voltage of the capacitor C3 of the charging voltage generating means 5 exceeds the output voltage Vr. As a result, the comparing means 6 detects the overcurrent, outputs the cutoff signal, and holds the state. Then, a circuit breaker or the like that cuts off the current to be measured of the bus bar 7 is operated by the cutoff signal.
[0019]
Here, it will be described that, when the measured current becomes an overcurrent, the current can be cut off in a time inversely proportional to the square of the current value. Now, if one input voltage (output voltage Vr) of the comparison means 6 is constant, the output current of the current conversion means 4, that is, the current for charging the capacitor C3 increases in proportion to the measured current. As the overcurrent value flowing through the bus bar 7 increases, the time required for the charging voltage of the capacitor C3 to exceed the output voltage Vr decreases, and the time from the occurrence of the overcurrent to the generation of the cutoff signal has a relationship inversely proportional to the current value. . Actually, in the present embodiment, one input voltage of the comparison means 6, that is, the output voltage Vr is set so as to be inversely proportional to the current to be measured. Therefore, the time is inversely proportional to the square of the current to be measured due to a synergistic effect. It will be able to cut off. In other words, a characteristic of outputting a cutoff signal is obtained with a cutoff time (time from occurrence of overcurrent to cutoff) having an inverse square characteristic of the measured current. That is, the protection unit is an ideal protection unit because it is adjusted to the physical phenomenon of heat generation due to overcurrent. Further, since the charging voltage of the capacitor C3 included in the charging voltage generation means 5 is used for the detection operation, there is an advantage that it is hardly affected by the surge current. FIG. 4 shows the breaking characteristics (the relationship between the breaking time and the current to be measured) of the present invention (this embodiment) in comparison with the breaking characteristics of a conventional large current fuse.
[0020]
According to the first embodiment, a current to be measured passing through a current path penetrating the inside of the magnetic body 1 having a gap G formed in a part of a closed magnetic circuit is detected, and the magnitude of the current to be measured is detected. In the overcurrent sensor that controls the time until the interruption by the first and second Hall elements 2A and 2B installed in the gap G, the Hall output voltage V _HA of the first Hall element 2A is constant. second Hall element 2B inversely proportional voltage generating means 3 for controlling the current by controlling the I _CA obtain an output voltage which is inversely proportional to the current to be measured of the first Hall element 2A, the control current I _CB is controlled to be constant in Current conversion means 4 for outputting an output current proportional to the Hall output voltage _VHB of the above, charging voltage generation means 5 for charging the output current of the current conversion means 4 to a capacitor C3 having a constant capacity to obtain the charging voltage, Reciprocal ratio Example The output voltage Vr of the voltage generating means 3 is compared with the output voltage Vr which is inversely proportional to the current to be measured, and the charging voltage of the charging voltage generating means 5. When the charging voltage exceeds the output voltage Vr, a cutoff signal is generated. With the configuration including the comparing means 6 for holding, a function as a safety breaker can be realized. That is, it is possible to obtain a characteristic of outputting a cutoff signal (overcurrent detection signal) with a cutoff time (time from occurrence of overcurrent to cutoff) having an inverse square characteristic of the current to be measured.
[0021]
Therefore, the timing of outputting the cutoff signal (overcurrent detection signal) is adjusted to the physical phenomenon of heat generation due to the overcurrent, so that an ideal protection unit is obtained. Further, there is an advantage that the variation in the fuse is very small, the circuit is simple and the cost is low.
[0022]
FIG. 3 shows a second embodiment of the present invention, and shows a specific circuit diagram. The arrangement of the Hall element with respect to the magnetic body may be as shown in FIG.
[0023]
As shown in FIG. 3, between the positive line connected to the DC voltage supply terminal Vin (+5 V) and the ground line connected to the ground terminal GND, the resistor R11 and the terminal {1} − of the first Hall element 2A. (3) The control current _ICA is supplied to the first Hall element 2A through the path of the resistor R1. Here, inverse voltage generating means 3 Hall output voltage _{V HA} of the first Hall element 2A controls the control current _{I CA} of the first Hall element 2A so as to be constant, the operational amplifier OP1, OP2, resistors R1 , R11, a capacitor C2, and an offset voltage source Vof. The offset voltage source Vof is composed of a diode D2 and resistors R13 and R14, has a temperature dependency, and performs temperature compensation of the Hall element.
[0024]
The Hall output voltage V _HA of the first Hall element 2A appears between the terminals (2) and (4) (here, the potential of (2) ≧ the potential of (4)), and the voltage of the terminal (2) is calculated. It is applied to the non-inverting input of the amplifier OP1. Here, as the measured current Ib is greater flowing to the bus bars ▲ 2 ▼ potential _{V 2} of the _increases, the V 2 αIb × _{I CA.} The operational amplifier OP1 constitutes a voltage follower, operates as an amplifier having a high input impedance and a low output impedance and an amplification factor of 1, and the output voltage thereof is added with an offset voltage of an offset voltage source Vof, thereby obtaining an inverted input of the operational amplifier OP2. Is applied. The voltage of the terminal (4) of the first Hall element 2A is applied to the non-inverting input terminal of the operational amplifier OP2. The operational amplifier OP2 functions as a comparator, and the terminal (4) applied to the non-inverting input terminal. The voltage of (4) is applied to the inverting input terminal for comparison (voltage of terminal (2) + offset voltage; however, the polarity of the voltage of terminal (2) and the offset voltage are opposite to each other in the illustrated example. ) Is controlled so that the voltage at the output end (that is, the control current I _CA ) is matched. As described in the first embodiment described above, by controlling the control current I _CA as Hall output voltage V _HA is constant, the control current I _CA will be inversely proportional to the current value to be measured, voltage Vr which is inversely proportional to the current value to be measured at both ends of the control current I _CA inserted resistor in the current path of R1 is obtained. This voltage Vr is applied to one input terminal of the comparing means 6 described later.
[0025]
Constant current circuit 8 for supplying a constant control current I _CB in the second Hall element 2B is an operational amplifier OP3, the terminal of the Hall element 2B between its output terminal and ground line ▲ 1 ▼ - ▲ 3 ▼ and in series It comprises an inserted resistor R3, resistors R4 and R5 for dividing a supply voltage between the DC voltage supply terminal Vin and the ground terminal GND and applying the divided voltage to the non-inverting input terminal of the operational amplifier OP3, and a capacitor C4. By controlling the voltage of the terminal (3) of the Hall element 2B applied to the inverting input terminal of the operational amplifier OP3 to match the voltage (constant value) of the non-inverting input terminal, the control current _ICB becomes constant. Will be maintained. Accordingly, a Hall output voltage _VHB proportional to the measured current appears between the terminals (2) and (4) (here, the potential of (2) ≧ the potential of (4)).
[0026]
Current conversion means 4 for controlling current _{I CB} outputs an output current proportional to the Hall output voltage _{V HB} of the second Hall element 2B, which is controlled to be constant is composed of transistors Q1 to Q4, resistors R6~R9 . Here, the pair of the transistor Q2 and the resistor R6 and the pair of the transistor Q1 and the resistor R7 form a current mirror circuit (mirror current circuit), and the collector current of the transistor Q1 is substantially equal to the collector current of the transistor Q2. The current is controlled to be the same. The transistors Q3 and Q4 operate as an emitter follower that converts the input side (base side) to high impedance and the emitter side to low impedance, and the bases of the transistors Q3 and Q4 have terminals (2) and (4) of the Hall element 2B respectively. Is applied. Then, the current in the path of the resistor R6, the transistor Q2, the transistor Q3, the resistor R8, and the resistor R9 is proportional to the voltage between the terminals (2) and (4) of the Hall element 2B (that is, the hall output voltage V _HB ). The transistor Q3 operates. As a result, the collector current of the transistor Q1 forming a current mirror circuit with the transistor Q2 becomes substantially the same as the collector current of the transistor Q2, and charges the capacitor C3 of the charging voltage generating means 5 through the path of the resistor R7 and the transistor Q1. Note that the resistor R12 also serves as an offset current adjustment and a discharge resistor when charging the capacitor C3.
[0027]
The charging voltage generating means 5 is a parallel circuit of a capacitor C3 and an offset current adjusting resistor R12. The offset current adjusting resistor R12 prevents the charging voltage of the capacitor C3 from increasing with a small charging current and supplies a DC voltage. When the supply of the voltage to the terminal Vin is temporarily stopped and the overcurrent sensor itself is reset, it also has a function of a reset discharge for discharging the charge of the capacitor C3 and returning the charge voltage to zero.
[0028]
The comparing means 6 has an operational amplifier OP4 and a latch diode D1 for holding this high level output. Then, the charging voltage of the capacitor C3 is applied to the non-inverting input of the operational amplifier OP4, and the voltage Vr inversely proportional to the measured current value across the resistor R1 is applied to the inverting input. The comparison means 6 is set to output a high-level cutoff signal to the output terminal Vout when the charging voltage of the capacitor C3 exceeds a voltage Vr that is inversely proportional to the measured current value.
[0029]
Note that an AC bypass capacitor C1 is connected between the positive line and the ground line.
[0030]
In the second embodiment, when the current to be measured flowing through the bus bar 7 of FIG. 2 is in a steady range, the magnetic flux density applied to the Hall elements 2A and 2B disposed in the same gap G is low, and the Hall element 2A The output voltage Vr across the resistor R1, which is inversely proportional to the current to be measured, of the inversely proportional voltage generation means 3 for controlling the Hall output voltage V _HA to be constant has a high voltage value. Contrary to this, the control current I _CB Hall output voltage V _HB of the Hall element 2B, which is controlled to be constant is small, small base potential of the transistor Q3, Q4 of the current converting means 4, the collector current of the transistor Q3 is weak ( (Substantially zero). That is, the collector current of the transistor Q2 in series with the transistor Q3 and the collector current of the transistor Q1, which is substantially the same as the transistor Q2, are also weak (substantially zero). As a result, the charging voltage of the capacitor C3 of the charging voltage generating means 5 does not rise to a voltage value exceeding the output voltage Vr. Therefore, the operational amplifier OP4 of the comparison means 6 does not detect an overcurrent, and does not generate a cutoff signal (overcurrent detection signal).
[0031]
On the other hand, if an overcurrent flows through the bus bar 7 shown in FIG. 2, the magnetic flux density applied to the Hall elements 2A and 2B becomes several times or more of the steady state, and the inverse proportional voltage generation for controlling the Hall output voltage V _HA of the Hall element 2A to be constant. The output voltage Vr across the resistor R1, which is inversely proportional to the measured current of the means 3, has a low voltage value (approaches the ground level). Contrary to this, the Hall output voltage V _HB of the Hall element 2B in which the control current I _CB is controlled to be constant is increased, the base potential of the transistors Q3, Q4 of the current converter 4 increases, the collector current of the transistor Q3 is Increase. That is, the collector current of the transistor Q2, which is in series with the transistor Q3, and the collector current of the transistor Q1, which is substantially the same, also increase, and the charging voltage of the capacitor C3 of the charging voltage generating means 5 exceeds the output voltage Vr. As a result, the operational amplifier OP4 of the comparing means 6 detects the overcurrent, outputs the cutoff signal whose output terminal has become high level to the output terminal Vout, and applies the output voltage to the non-inverting input terminal via the diode D1. By doing so, the cutoff signal output is held. Then, a circuit breaker or the like that cuts off the current to be measured of the bus bar 7 is operated by the cutoff signal.
[0032]
As described in the first embodiment, when the measured current becomes an overcurrent, the current can be cut off in a time inversely proportional to the square of the current value.
[0033]
According to the second embodiment, the following effects can be obtained.
[0034]
(1) inverse voltage generation Hall output voltage V _HA of the first Hall element 2A is obtained an output voltage Vr which is inversely proportional to the first control to the current to be measured a control current I _CA Hall elements 2A so as to be constant Means 3, a current converting means 4 for outputting an output current proportional to the Hall output voltage V _HB of the second Hall element 2B in which the control current I _CB is controlled to be constant, and an output current of the current converting means 4 having a constant capacity. By using the charging voltage generating means 5 for charging the capacitor C3 of the above and obtaining the charging voltage, the comparing means 6 compares the output voltage Vr inversely proportional to the measured current with the charging voltage of the charging voltage generating means 5, and When the charging voltage exceeds the output voltage Vr of the inversely proportional voltage generating means 3, a cutoff signal (overcurrent detection force) is generated, and this signal can be maintained thereafter. As a result, it is possible to obtain a function as a safety breaker, that is, a characteristic of outputting a cutoff signal with a cutoff time having approximately the inverse square characteristic of the measured current.
[0035]
(2) The charging voltage of the capacitor C3 of the charging voltage generating means 5 is used as one input of the comparing means 6 so that a shutoff signal is not output when a surge current instantaneously flows through the bus bar 7. And a current protection function can be realized even in an application in which load fluctuation is severe.
[0036]
(3) The main components used are two Hall elements, a plurality of operational amplifiers, and transistors, which are inexpensive circuit configurations.
[0037]
In the first and second embodiments, the case where the first and second Hall elements are arranged in the same gap of the magnetic body is exemplified. However, the bus bar as the current path through which the current to be measured flows is described. It is possible on the operating principle that two magnetic bodies are provided, and the first Hall element is arranged in the gap of one magnetic body and the second Hall element is arranged in the gap of the other magnetic body. It is.
[0038]
Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims.
[0039]
【The invention's effect】
As described above, according to the overcurrent sensor according to the present invention, the fusing characteristics of a large-current fuse that is blown even by a surge current are improved, and a current protection function for an application with a severe load change is realized. It is also possible to realize a current breaker function capable of recovering by utilizing the characteristics of the electronic circuit. Further, there is an advantage that the variation can be reduced as compared with the fuse for a large current, and the fuse can be manufactured at a low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of an overcurrent sensor according to the present invention.
FIG. 2 is a perspective view showing an arrangement of a magnetic body and a Hall element in each embodiment.
FIG. 3 is a circuit diagram showing a second embodiment of the present invention.
FIG. 4 is a characteristic diagram showing a comparison between the fuse for a large current and the breaking characteristic of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetic body 2A, 2B Hall element 3 Inverse proportional voltage generation means 4 Current conversion means 5 Charge voltage generation means 6 Comparison means 7 Bus bar 8 Constant current circuits C1-C4 Capacitors D1, D2 Diodes OP1-OP4 Operational amplifiers Q1-Q4 Transistors R1- R9, R11 to R14 Resistance

Claims (2)

In an overcurrent sensor that detects a measured current passing through a current path that passes through the inside of a magnetic body that forms a gap in a part of a closed magnetic path, and controls a time to be cut off by the magnitude of the measured current,
First and second Hall elements installed in the gap of the magnetic body,
Inverse proportional voltage generation means for controlling a control current of the first Hall element so that a Hall output voltage of the first Hall element is constant to obtain an output voltage inversely proportional to the measured current;
Current conversion means for outputting an output current proportional to a Hall output voltage of the second Hall element, wherein the control current is controlled to be constant;
Charging voltage generating means for charging an output current of the current converting means to a capacitor having a constant capacity to obtain a charging voltage thereof,
An output voltage of the inversely proportional voltage generator is inversely proportional to the current to be measured and a charge voltage of the charge voltage generator, and a cutoff signal is generated when the charge voltage exceeds an output voltage of the inverse voltage generator. An overcurrent sensor comprising: a comparison unit that holds the current as a current. In an overcurrent sensor that detects a measured current passing through a current path that passes through the inside of a magnetic body that forms a gap in a part of a closed magnetic path, and controls a time to be cut off by the magnitude of the measured current,
Two magnetic bodies are provided for the current path, a first Hall element installed in a gap of one magnetic body and a second Hall element installed in a gap of the other magnetic body,
Inverse proportional voltage generation means for controlling a control current of the first Hall element so that a Hall output voltage of the first Hall element is constant to obtain an output voltage inversely proportional to the measured current;
Current conversion means for outputting an output current proportional to a Hall output voltage of the second Hall element, wherein the control current is controlled to be constant;
Charging voltage generating means for charging an output current of the current converting means to a capacitor having a constant capacity to obtain a charging voltage thereof,
An output voltage of the inversely proportional voltage generator is inversely proportional to the current to be measured and a charge voltage of the charge voltage generator, and a cutoff signal is generated when the charge voltage exceeds an output voltage of the inverse voltage generator. An overcurrent sensor comprising: a comparison unit that holds the current as a current.

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