1. Field of the Invention
The present invention relates to a current detecting apparatus for detecting a current flowing through an electric circuit loaded on an apparatus such as automobile and a current detecting method, and more particularly to technology for improving detection accuracy for a current flowing through each branch conductor.
2. Description of The Related Art
Recently, with prevailing of, for example, electric car, hybrid car and the like, the necessity of a current detecting apparatus for, for example, charge/discharge control has been intensified. As such a current detecting apparatus, a current detecting apparatus which is installed in an electric connecting box for distributing currents from a power supply and detecting a current flowing through a conductor incorporated in the electric connecting box using an electromagnetic transducer has been well known. However, the current detecting apparatus using the electromagnetic transducer has such a problem that because a plurality of conductors are incorporated in the electric connecting box, an accurate current detection is impossible due to an interference of magnetic flux generated by a current flowing through other conductor than the conductor in which a detection object current flows.
To solve such a problem, a current detecting apparatus for electric wire has been disclosed in, for example, Japanese Patent Application Laid-Open No. 63-63974. In this current detecting apparatus as shown in FIG. 1, a conductor B in which the detection object current I1 flows is disposed substantially at right angle to other conductor A and further, a magnetic core 1a through which the conductor B passes is disposed substantially at the right angle to that conductor B.
With this structure, magnetic fields H2 and H3 generated by current I2 flowing through other conductor A are canceled in a magnetic core 1a and only a magnetic field H1 generated by a current I1 flowing through a conductor B passes through the magnetic core 1a. Thus, the electromagnetic transducer 1b placed in a gap of the magnetic core 1a does not receive an interference from other conductor B, the current I1 flowing through the conductor B can be detected accurately.
However, because this conventional current detecting apparatus for electric wire employs the magnetic core, there are such problems that its weight and occupied volume cannot be reduced beyond each predetermined level and production cost is high. Particularly, if a plurality of conductors through the detection object current flows are arranged in parallel, the same number of the magnetic cores are necessary, so that the weight and occupied volume increase depending on the number of the conductors and further the production cost is increased.
On the other hand, for example, in automotive current connecting box, not only a plurality of conductors are arranged in parallel in some case, but also a conductor is branched to a plurality of conductors in the electric connecting box, so that it comes that those plural conductors are disposed in parallel in other case.
An object of the present invention is to provide a current detecting apparatus capable of detecting a current flowing through each conductor even if a plurality of the conductors are disposed together, by positively using a condition including branch conductors provided in an electric connecting box, the current detecting apparatus being capable of being reduced in its size and weight at a low cost. Another object of the present invention is to provide a current detecting method capable of detecting a current flowing through each conductor at a high sensitivity even if a plurality of the conductors are disposed together.
To achieve the above object, according to a first aspect of the present invention, there is provided a current detecting apparatus comprising: n (n: integer satisfying nxe2x89xa73) conductors disposed so as to be branched radially from a branch point; m (m: integer satisfying mxe2x89xa72) electromagnetic transducers disposed between adjacent conductors of the n conductors; and an operation processing circuit for detecting a current flowing through each of the n conductors based on an operating output obtained from a predetermined operation based on an electric signal from each of the m electromagnetic transducers.
According to the first aspect of the present invention, the electromagnetic transducers are disposed on both sides of each of the n conductors. A current flowing through each conductor is detected by carrying out a predetermined operation on an electric signal from the two electromagnetic transducers. In this case, each of the two electromagnetic transducers receives a magnetic flux produced by a difference between a current before branching and a current after branching. Thus, even if the current which is a detection object is constant, the magnetic flux is converted electromagnetically. As a result, a current flowing through each conductor can be detected with a high sensitivity even if it is small.
Because no magnetism collecting core is used in the first aspect (in principal, it is not necessary to use the magnetism collecting core), the size, weight and production cost of the current detecting apparatus can be reduced. Particularly, this effect is remarkable in detecting a current in each branch route.
According to a second aspect of the invention, there is provided a current detecting apparatus according to the first aspect wherein the n conductors are disposed on a flat plane including the branch point and the m electromagnetic transducers are disposed such that a magnetism sensitive surface of each thereof exists on the flat plane.
According to the second aspect, because n conductors and m electromagnetic transducers are disposed on the same plane, magnetic flux generated by current flow through each conductor enters a magnetism sensitive surface of each electromagnetic transducer. As a result, in the operation processing circuit, an electric signal from each electromagnetic transducer does not have to be corrected, so that operation on the operation processing circuit is simplified.
According to the third aspect, there is provided a current detecting apparatus according to the second aspect wherein the n is xe2x80x9c3xe2x80x9d while the three conductors are disposed every 120xc2x0 from the branch point on the flat plane in three directions; the m is xe2x80x9c3xe2x80x9d while the three electromagnetic transducers are disposed at the same distance from adjacent conductors and at the same distance from the branch point; and the operation processing circuit detects a current flowing through the conductor by obtaining a difference of electric signal between the two electromagnetic transducers sandwiching each conductor.
According to the third aspect, a current flowing through each conductor is detected by obtaining a difference of electric signal from two electromagnetic transducers sandwiching the conductor. In this case, one electromagnetic transducer receives a magnetic flux in a predetermined direction generated by a current before branching and a current after branching, while the other electromagnetic transducer receives a magnetic flux in an opposite direction generated by the current before branching and the current after the branching. Thus, even if the detecting object current is constant, it comes that a magnetic flux three times a magnetic flux generated by a current if there is no branch is converted electromagnetically. As a result, even if the current flowing through each conductor is small, it can be detected at a high sensitivity.
Further, even if there is a disturbing magnetic flux near this current detecting apparatus, it is canceled by obtaining a difference of electric signal from the two electromagnetic transducers. As a result, even if other conductors are provided together, an influence from them is not received. Thus, a current flowing through each conductor can be detected at a high sensitivity. Further, currents flowing through three conductors can be detected at a high sensitivity using three electromagnetic transducers. Therefore, this current detecting apparatus can be produced at a lower cost as compared to a current detecting apparatus for detecting a current flowing through a conductor with two electromagnetic transducers.
According to a fourth aspect of the present invention, there is provided a current detecting apparatus according to the second aspect where the n is xe2x80x9c3xe2x80x9d while the three conductors are disposed in three directions from the branch point on the flat plane such that an angle between the first conductor and the second conductor is 90xc2x0, an angle between the second conductor and the third conductor is 90xc2x0 and an angle between the third conductor and the first conductor is 180xc2x0; the m is xe2x80x9c4xe2x80x9d while the first electromagnetic transducer is disposed at the same distance from the first conductor and the second conductor and at the same distance from the branch point, the second electromagnetic transducer is disposed at the same distance from the second conductor and the third conductor and at the same distance from the branch point, the third electromagnetic transducer is disposed symmetrically with the second electromagnetic transducer with respect to the third conductor and at the same distance from the branch point, and the fourth electromagnetic transducer is disposed symmetrically with the first electromagnetic transducer with respect to the first conductor and at the same distance from the branch point; the operation processing circuit detects a current flowing through the conductor by obtaining a difference of electric signal between the four electromagnetic transducers sandwiching each conductor.
According to this fourth aspect, a current flowing through each conductor is detected by obtaining a difference of electric signal from the electromagnetic transducers which sandwich each conductor. In this case, a current flowing through each of the first conductor, second conductor and third conductor can be detected at a high sensitivity.
Further, because the disturbing magnetic flux existing near the current detecting apparatus can be canceled, the current flowing through each conductor can be detected at a high accuracy. Further, because currents flowing three conductors can be detected at a high sensitivity using only four electromagnetic transducers, this current detecting apparatus can be produced at a lower cost than a current detecting apparatus for detecting a current flowing through a conductor using two electromagnetic transducers.
According to a fifth aspect of the present invention, there is provided a current detecting apparatus according to the second aspect wherein the n is xe2x80x9c4xe2x80x9d while the four conductors are disposed every 90xc2x0 from the branch point on the flat plane in four direction; the m is xe2x80x9c4xe2x80x9d while the four electromagnetic transducers are disposed at the same distance from adjacent two conductors and at the same distance from the branch point; and the operation processing circuit detects a current flowing through the conductor by obtaining a difference of electric signal among the four electromagnetic transducers sandwiching each conductor.
According to the fifth aspect of the present invention, a current flowing through each conductor can be detected at a high sensitivity by obtaining a difference of electric signal from four electromagnetic transducers which sandwich each conductor.
Because the disturbing magnetic flux existing near the current detecting apparatus is canceled, a current flowing through each conductor can be detected at a high accuracy. Further, because currents flowing through the four conductors can be detected at a high sensitivity using only four electromagnetic transducers, the current detecting apparatus can be produced at a lower cost than a current detecting apparatus for detecting a current flowing through a conductor using two electromagnetic transducers.
According to a sixth aspect of the present invention, there is provided a current detecting apparatus according to the first aspect wherein the n conductors are disposed on three-dimensional axes perpendicular to each other with the branch point as a home position and the m electromagnetic transducers are disposed such that magnetism sensitive surfaces thereof exist on a flat plane including two axes of the three axes.
According to this sixth aspect, the n conductors are disposed the three-dimensional axes perpendicular to each other with the branch point as a home position and m electromagnetic transducers are disposed such that the magnetism sensitive surfaces thereof exist on the same plane including two axes of the three axes. Thus, the magnetic flux generated by current flow into each conductor existing on the same plane enters the magnetism sensitive surface of each electromagnetic transducer vertically. As a result, an electric signal from each electromagnetic transducer becomes accurate in the operation processing circuit, so that operation in the operation processing circuit is simplified.
According to a seventh aspect of the present invention, there is provided a current detecting apparatus according to the sixth aspect wherein the n is xe2x80x9c3xe2x80x9d while the three conductors are disposed in three directions of the three axes; the m is xe2x80x9c3xe2x80x9d while the first electromagnetic transducer is disposed at the same distance from the first conductor and the second conductor existing on the flat plane and at the same distance from the branch point, the second electromagnetic transducer is disposed symmetrically with the first electromagnetic transducer with respect to the second conductor and at the same distance from the branch point and the third electromagnetic transducer is disposed symmetrically with the first electromagnetic transducer with respect to the first conductor and at the same distance from the branch point; and the operation processing circuit detects a current flowing through each conductor of the first-third conductor by obtaining a difference of electric signal between three electromagnetic transducers sandwiching each of the first conductor and the second conductor existing on the flat plane.
According to the seventh aspect, a current flowing through the first-third conductors is detected by obtaining a difference of electric signal from the three electromagnetic transducers which sandwich each conductor of the first conductor and the second conductor existing on the flat plane.
Further, even if the disturbing magnetic flux exists near this current detecting apparatus, it is canceled by obtaining a difference of electric signal from the three electromagnetic transducers. As a result, even if other conductors are provided together, an influence therefrom is not received. Thus, a current flowing through each conductor can be detected. Further, currents flowing through the three conductors can be detected at a high sensitivity using only three electromagnetic transducers. Thus, this current detecting apparatus can be produced at a lower cost than a current detecting apparatus for detecting a current flowing through a conductor using two electromagnetic transducers.
According to an eighth aspect of the present invention, there is provided a current detecting apparatus according to the sixth aspect wherein the n is xe2x80x9c4xe2x80x9d while the four conductors are disposed on the three axes and a negative direction axis of one of the three axes; the m is xe2x80x9c4xe2x80x9d while the first-fourth electromagnetic transducers are disposed on a flat plane including two axes of the three axes and the negative direction axes; the first electromagnetic transducer and the second electromagnetic transducer are disposed at the same distance from the first conductor which is one of the first-third conductors existing on the flat plane and at the same distance from the branch point, the third electromagnetic transducer is disposed symmetrically with the second electromagnetic transducer with respect to the second conductor and at the same distance from the branch point, and the fourth electromagnetic transducer is disposed symmetrically with the third electromagnetic transducer with respect to the third conductor and at the same distance from the branch point; and the operation processing circuit detects a current flowing through each conductor of the first-fourth conductors by obtaining a difference of electric signal between the four electromagnetic transducers sandwiching each conductor of the first-third conductors existing on the flat plane.
According to the eighth aspect, a current flowing through each of the first-fourth conductors is detected by obtaining a difference of electric signal from the four electromagnetic transducers which sandwich each conductor of the first-third conductors existing on the flat plane.
Further, the disturbing magnetic flux existing near this current detecting apparatus is canceled in the same way as the seventh aspect. Thus, a current flowing through each conductor can be detected. Further, currents flowing through the four conductors can be detected at a high sensitivity using only four electromagnetic transducers. Thus, this current detecting apparatus can be produced at a lower cost than a current detecting apparatus for detecting a current flowing through a conductor using two electromagnetic transducers.
According to a ninth aspect of the present invention, there is provided a current detecting apparatus according to the third-eighth aspect wherein the m electromagnetic transducers are disposed such that the magnetism sensitive surfaces thereof are directed in the same direction.
According to this ninth aspect, because the m electromagnetic transducers are disposed such that the respective magnetism sensitive surfaces are directed in the same direction, the electric signal from each of the electromagnetic transducer can be handled easily in the operation processing circuit, so that operation in the operation processing circuit is facilitated.
According to a tenth aspect of the present invention, there is provided a current detecting method comprising: disposing n (n: integer satisfying nxe2x89xa73) conductors so as to be branched radially from a branch point; disposing m (m: integer satisfying mxe2x89xa72) electromagnetic transducers between adjacent conductors of the n conductors; and detecting a current flowing through each of the n conductors based on an operating output obtained from a predetermined operation based on an electric signal from each of the m electromagnetic transducers. According to the tenth aspect, the same operation and effect as the first aspect are exerted.
According to an eleventh aspect of the present invention, the n conductors are disposed on a flat plane including the branch point and the m electromagnetic transducers are disposed such that a magnetism sensitive surface of each thereof exists on the flat plane. According to the eleventh aspect, the same operation and effect as the second aspect are exerted.
According to a twelfth aspect of the present invention, there is provided a current detecting method comprising: while the n is xe2x80x9c3xe2x80x9d, disposing the three conductors every 120xc2x0 from the branch point on the flat plane in three directions; while the m is xe2x80x9c3xe2x80x9d, disposing the three electromagnetic transducers at the same distance from adjacent conductors and at the same distance from the branch point; and detecting a current flowing through the conductor by obtaining a difference of electric signal between the two electromagnetic transducers sandwiching each conductor. According to the twelfth aspect, the same operation and effect as the third aspect are exerted.
According to a thirteenth aspect of the present invention, there is provided a current detecting method according to the eleventh aspect comprising: while the n is xe2x80x9c3xe2x80x9d, disposing the three conductors in three directions from the branch point on the flat plane such that an angle between the first conductor and the second conductor is 90xc2x0, an angle between the second conductor and the third conductor is 90xc2x0 and an angle between the third conductor and the first conductor is 180xc2x0; while the m is xe2x80x9c4xe2x80x9d, disposing the first electromagnetic transducer at the same distance from the first conductor and the second conductor and at the same distance from the branch point, disposing the second electromagnetic transducer at the same distance from the second conductor and the third conductor and at the same distance from the branch point, disposing the third electromagnetic transducer symmetrically with the second electromagnetic transducer with respect to the third conductor and at the same distance from the branch point, and disposing the fourth electromagnetic transducer symmetrically with the first electromagnetic transducer with respect to the first conductor and at the same distance from the branch point; and detecting a current flowing through the conductor by obtaining a difference of electric signal between the four electromagnetic transducers sandwiching each conductor. According to this thirteenth aspect, the same operation and effect as the fourth aspect are exerted.
According to a fourteenth aspect of the present invention, there is provided a current detecting method according to the eleventh aspect wherein the n is xe2x80x9c4xe2x80x9d while the four conductors are disposed every 90xc2x0 from the branch point on the flat plane in four direction; the m is xe2x80x9c4xe2x80x9d while the four electromagnetic transducers are disposed at the same distance from adjacent two conductors and at the same distance from the branch point; and a current flowing through the conductor is detected by obtaining a difference of electric signal among the four electromagnetic transducers sandwiching each conductor. According to the fourteenth aspect, the same operation and effect as the fifth aspect are exerted.
According to a fifteenth aspect of the present invention, there is provided a current detecting method wherein the n conductors are disposed on three-dimensional axes perpendicular to each other with the branch point as a home position and the m electromagnetic transducers are disposed such that magnetism sensitive surfaces thereof exist on a flat plane including two axes of the three axes. According to this fifteenth aspect, the same operation and effect as the sixth aspect are exerted.
According to a sixteenth aspect of the present invention, there is provided a current detecting method wherein the n is xe2x80x9c3xe2x80x9d while the three conductors are disposed in three directions of the three axes; the m is xe2x80x9c3xe2x80x9d while the first electromagnetic transducer is disposed at the same distance from the first conductor and the second conductor existing on the flat plane and at the same distance from the branch point, the second electromagnetic transducer is disposed symmetrically with the first electromagnetic transducer with respect to the second conductor and at the same distance from the branch point and the third electromagnetic transducer is disposed symmetrically with the first electromagnetic transducer with respect to the first conductor and at the same distance from the branch point; and a current flowing through each conductor of the first-third conductor is detected by obtaining a difference of electric signal between three electromagnetic transducers sandwiching each of the first conductor and the second conductor existing on the flat plane. According to this sixteenth aspect, the same operation and effect as the seventh aspect are exerted.
According to a seventeenth aspect of the present invention, there is provided a current detecting method wherein the n is xe2x80x9c4xe2x80x9d while the four conductors are disposed on the three axes and a negative direction axis of one of the three axes; the m is xe2x80x9c4xe2x80x9d while the first-fourth electromagnetic transducers are disposed on a flat plane including two axes of the three axes and the negative direction axes; the first electromagnetic transducer and the second electromagnetic transducer are disposed at the same distance from the first conductor which is one of the first-third conductors existing on the flat plane and at the same distance from the branch point, the third electromagnetic transducer is disposed symmetrically with the second electromagnetic transducer with respect to the second conductor and at the same distance from the branch point, and the fourth electromagnetic transducer is disposed symmetrically with the third electromagnetic transducer with respect to the third conductor and at the same distance from the branch point; and a current flowing through each conductor of the first-fourth conductors is detected by obtaining a difference of electric signal between the four electromagnetic transducers sandwiching each conductor of the first-third conductors existing on the flat plane. According to the seventeenth aspect, the same operation and effect as the eighth aspect are exerted.
According to an eighteenth aspect of the present invention, there is provided a current detecting method wherein the m electromagnetic transducers are disposed such that the magnetism sensitive surfaces thereof are directed in the same direction.