JP2013169020A - Charge/discharge state monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and reliably monitor a charge state and a discharge state of a monitored object.SOLUTION: A charge/discharge state monitoring system includes: current sensors 10 attached to cylindrical busbars 102 disposed in a regeneration system 100 between a storage battery 40 and an inverter 60 and between a motor/generator 70 and the inverter 60, respectively; an ECU 20; and a monitor 30. The current sensors 10 each have a current detection element 12 and a quadrupole auxiliary magnet 13, and detect a current I flowing through the busbar 102 by detecting an angle formed to a predetermined direction by the direction of a composite magnetic field M of a magnetic field Hip generated by the current I and a magnetic field Hs given by the quadrupole auxiliary magnet 13. The ECU 20 determines that a charge/discharge state is normal if the angle of the composite magnetic field M is within the range of ±45°, and if not, asserts an abnormal condition and stops charge/discharge-related operations of the regeneration system 100.

Description

  The present invention relates to a charge / discharge state monitoring system capable of accurately monitoring a charge state and a discharge state using a current detection device that detects a current using a magnetic detection element.

  In recent years, a so-called low-carbon pursuit society has been achieved, and vehicles such as automobiles are HEV (Hybrid Electric Vehicle), PHEV (Plug-in HEV: Plug-in Hybrid Vehicle), EV (Electric Vehicle: Electric Vehicle), FCEV. (Fuel Cell EV: fuel cell electric vehicle) and the like.

  In these vehicles, a motor and various storage batteries are mounted as a drive source different from that of a vehicle using a conventional internal combustion engine. For this reason, the state of regenerative current that flows from the motor to the storage battery and charges the storage battery (charged state) and the state of the drive current that flows from the storage battery to the motor and drives the motor (discharge state) are sequentially monitored to ensure stable charging and discharging. It is necessary to perform control so as to avoid excessive charging current and discharging current flowing.

  As an apparatus for performing such control, an energy control system for a fuel cell vehicle disclosed in Patent Document 1 below is known. In this control system, when the charge / discharge state detector detects overdischarge or overcharge of the secondary battery, the control system switches from the state of controlling the output voltage of the fuel cell to the state of controlling the current of the secondary battery. Is made.

  In addition, as a current sensor used with the above control systems, the magnetic sensor disclosed by the following patent document 2 or the following patent document 3 is normally used. The thing of the patent document 2 uses a Hall element, and the thing of the patent document 3 uses an anisotropic magnetoresistive (AMR) element.

JP 2009-54397 A Japanese Patent No. 3896590 JP-A-9-43327

  However, the Hall element disclosed in Patent Document 2 is difficult to improve the measurement accuracy due to the influence of temperature characteristics. For example, a secondary coil for passing a secondary current may be required, and erroneous measurement occurs. There is a problem that the configuration is complicated and the configuration is increased and the size is increased. In particular, when the purpose is to detect an overcurrent, it is necessary to prevent magnetic saturation of the magnetic material due to the overcurrent. Therefore, an extremely large element is required, which is not suitable for a system that requires a large current.

  Further, since the AMR element disclosed in Patent Document 3 detects a current only by a change in resistance value, a simple charge / discharge can be detected, but a charge current or a discharge current exceeding a predetermined value flows. In applications where it is detected whether or not (overcharge or overdischarge detection), there is a problem that the responsiveness is poor.

  An object of the present invention is to provide a charge / discharge state monitoring system that can accurately and reliably monitor a charge state and a discharge state of an object to be monitored in order to solve the above-described problems caused by the prior art.

  The charge / discharge state monitoring system according to the present invention generates power for driving a drive target using a storage battery and power discharged from the storage battery, and generates power based on the operation of the drive target. A motor / generator for charging the storage battery, a current detection device for detecting a current flowing through the conductive member disposed in the vicinity of the conductive member forming a current path between the motor / generator and the storage battery, and And a control unit that controls to stop the operation of the motor / generator when the magnitude of the current reaches a predetermined value, and the current detection device is disposed in the vicinity of the conductive member and applies a first magnetic field An auxiliary magnet, a second magnetic field that is arranged in the vicinity of the conductive member and changes according to the magnitude and direction of the current flowing through the conductive member, and a test that changes according to the direction of the combined magnetic field of the first magnetic field. And a magnetic detecting element for outputting a signal, the control unit in accordance with the detection signal, characterized in that stops the operation of the motor / generator.

  ADVANTAGE OF THE INVENTION According to this invention, the charging / discharging state monitoring system which can monitor the charging state and discharge state in a monitoring target object correctly and reliably can be provided.

It is a figure which shows the structure of the regeneration system to which the charging / discharging state monitoring system which concerns on the 1st Embodiment of this invention was applied. It is a perspective view for demonstrating the arrangement | positioning aspect of the current sensor in the charging / discharging state monitoring system. It is a side view which shows the structure of the current sensor of the charging / discharging state monitoring system. 4 is a schematic diagram showing a configuration of a four-pole auxiliary magnet 13. FIG. 2 is a schematic diagram showing a configuration of a magnetic detection element 12. FIG. It is a block diagram which shows the structure of EPU25. It is a conceptual diagram explaining the principle which detects the magnitude | size of direct current I. FIG. 4 is a graph showing a relationship between an angle θ and a current I. It is a conceptual diagram explaining the principle which detects the magnitude | size of alternating current I. FIG. It is a conceptual diagram explaining the principle which detects the magnitude | size of alternating current I. FIG. It is a conceptual diagram explaining the principle which detects the magnitude | size of alternating current I. FIG. It is a conceptual diagram explaining the principle which detects the magnitude | size of alternating current I. FIG. It is a conceptual diagram explaining the principle which detects the magnitude | size of alternating current I. FIG. It is a side view which shows the other structure of the current sensor of the charging / discharging state monitoring system. It is a top view which shows a 4-pole auxiliary magnet. It is a figure which shows the structure of the hybrid system to which the charging / discharging state monitoring system which concerns on the 2nd Embodiment of this invention was applied.

  Embodiments of a charge / discharge state monitoring system according to the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration of a regeneration system to which a charge / discharge state monitoring system according to a first embodiment of the present invention is applied, and FIG. 2 illustrates an arrangement mode of current sensors in the charge / discharge state monitoring system. FIG. This charge / discharge state monitoring system (hereinafter abbreviated as “monitoring system”) is applied to a regeneration system 100 provided in a vehicle such as an automobile, for example.

  The regenerative system 100 includes a storage battery 40, an inverter 60, and an electric motor / generator 70. The storage battery 40 has a function of converting (accumulating) stored chemical energy into electric energy (DC voltage) and supplying (discharging) it to the outside, and storing (charging) electric power supplied from the outside. The inverter 60 has a function of converting the direct current supplied from the storage battery 40 into alternating current and supplying the alternating current to the electric motor / generator 70, while converting the alternating voltage generated in the electric motor / generator 70 into direct current voltage. That is, the inverter 60 has a function as an AC / DC converter. The electric motor / generator 70 generates kinetic energy by the alternating current supplied from the inverter 60 to drive the wheel 101 and regenerates the kinetic energy of the wheel 101 to generate an alternating voltage.

  The monitoring system applied to the regenerative system 100 includes a current sensor 10. The current sensor 10 is attached to a position in the vicinity of the bus bar 102 (see FIG. 2) that is a cylindrical conductive member that is disposed between the storage battery 40 and the inverter 60 and forms a current path. The current sensor 10 is also attached to a position in the vicinity of the bus bar 102 that is a cylindrical conductive member that is disposed between the motor / generator 70 and the inverter 60 and forms a current path. In this embodiment, an example having two current sensors 10 will be described. However, either the bus bar 102 between the storage battery 40 and the inverter 60 or the bus bar 102 between the motor / generator 70 and the inverter 60 is used. Only one current sensor 10 may be provided.

  Furthermore, this monitoring system performs various arithmetic processing based on the detection signal from each current sensor 10, and controls the whole regeneration system 100, and the information from this ECU 20 is displayed on a screen. And a monitor 30 for notification. As will be described later, the ECU 20 includes an A / D converter that converts an analog signal into a digital signal, a D / A converter, a CPU, and the like. The monitor 30 may have a function of outputting sound through, for example, a speaker in addition to notifying information by screen display.

  As shown in FIG. 2, the bus bar 102 has cable connection portions 104 and 105, and is connected to the storage battery 40 and the inverter 60 through the cable connection portions 104 and 105. Bus bar 102 forms a current path between storage battery 40 and inverter 60 or between motor / generator 70 and inverter 60. When the current I flows through the bus bar 102, a magnetic field Hip is generated in the circumferential direction. Each current sensor 10 is attached to the bus bar 102 at a predetermined position via an attachment jig 103, and a combined magnetic field M of a magnetic field Hip generated by a current I and a magnetic field Hs provided by a 4-pole auxiliary magnet described later. A detection signal based on the direction of the is output.

  FIG. 3 is a side view showing the configuration of the current sensor 10 of the charge / discharge state monitoring system. Each current sensor 10 includes, for example, a 4-pole auxiliary magnet 13 mounted on the substrate 11 and a magnetic detection element 12 mounted on the opposite side of the substrate 11. The quadrupole auxiliary magnet 13 is a ring-shaped magnet as shown in FIG. 4A, for example, and is magnetized so that magnetic moments are formed in directions of + 45 ° and −45 ° with respect to the center line passing through the center O. Yes. The quadrupole auxiliary magnet 13 may be composed of a rare earth permanent magnet such as samarium cobalt. The magnetic detection element 12 is installed at a position in the vicinity of the bus bar 102 so that the combined magnetic moment of the magnetic moments in the + 45 ° and −45 ° directions is along the longitudinal direction of the bus bar 102.

  The magnetic detection element 12 is made of, for example, permalloy (Ni—Fe alloy), and is disposed in a combined magnetic field M formed by combining a magnetic field Hip based on the current I and a magnetic field Hs provided by the quadrupole auxiliary magnet 13. The quadrupole auxiliary magnet 13 is mounted at a position shifted from the center O. The magnetic detection element 12 has a pair of sensor units 121 and 122 as shown in FIG. 4B. The sensor unit 121 is configured by bridge-connecting four MR elements 111. Similarly, the sensor unit 122 is configured by bridge-connecting four MR elements 111 '.

  The four MR elements 111 of the sensor unit 121 are arranged such that their easy magnetization axes are shifted by 90 ° and are bridge-connected. The same applies to the four MR elements 111 ′ of the sensor unit 122. In addition, the MR elements 111 and 111 'are arranged with their easy magnetization axes inclined by 45 °. Since the magnetic detection element 12 has such a configuration, the direction (angle θ) of the combined magnetic field M of the fixed magnetic field Hs based on the magnetic moment of the quadrupole auxiliary magnet 13 and the magnetic field Hip generated by the current I is changed. The detection signal including the information of the angle θ is output to the CPU 25. Details will be described later.

  The detection signals output from the output terminals B, D, E, and G of the magnetic detection element 12 include information on the angle θ. As shown in FIG. 4C, the A / D converter 21 in the ECU 20 The A / D conversion is performed at 24 to 24 and is input to the CPU 25 mounted in the ECU 20.

  The CPU 25 processes a detection signal including information on the angle θ provided from the current sensor 10 according to a program stored in the EEPROM 26 to calculate the angle θ. The data of the angle θ is calculated as an angle formed by the combined magnetic field M of the magnetic field His generated by the current I flowing through the bus bar 102 and the fixed magnetic field Hs provided by the quadrupole auxiliary magnet 13 with respect to the longitudinal direction of the bus bar 102. Is done. From the angle θ data, tan θ is also calculated. The current I is a value proportional to the tan θ and is calculated by a method described later. The CPU 25 determines whether or not the angle θ is within a predetermined angle range (for example, within ± 45 ° with respect to the longitudinal direction of the bus bar 102).

  When the angle θ is outside the predetermined angle range, it is determined that the current I is excessive and charging / discharging due to the overcurrent is performed, and the operation related to charging or discharging in the regenerative system 100 is stopped. Specifically, when the wheel 101 is braked, when the current sensor 10 attached to the bus bar 102 between the storage battery 40 and the inverter 60 detects that the angle θ exceeds a predetermined angle range, The charging operation is stopped assuming that the storage battery 40 is charged by the overcurrent.

  On the other hand, when it is detected by the current sensor 10 attached to the bus bar 102 between the electric motor / generator 70 and the inverter 60 when the driving force is applied to the wheel 101, the angle θ exceeds the predetermined angle range. The discharge operation is stopped assuming that the electric motor / generator 70 is discharged due to overcurrent.

  In parallel with this, the ECU 20 outputs information related to the monitoring results of the charge / discharge states of the storage battery 40 and the electric motor / generator 70 to the monitor 30 and displays the information. When a charge / discharge state due to overcurrent is detected, a warning signal or the like notifying the occurrence of overcurrent is displayed on the monitor 30 together with information indicating that the operation has been stopped so as not to cause a serious accident. It is preferable to configure the ECU 20 as described above.

  Here, a calculation method of absolute angle detection data by the current sensor 10 and the ECU 20 of the monitoring system configured as described above will be specifically described. Here, it is assumed that a direct current I flows through the bus bar 102 (radius R) between the storage battery 40 and the inverter 60. In this case, the magnetic field Hip generated by the current I at a distance r (> R) from the center of the bus bar 102 can be expressed as follows.

[Equation 1]
Hip = I / 2πr

  FIG. 5 is a conceptual diagram illustrating a method for calculating the angle θ when a direct current I flows through the bus bar 102. As shown in FIG. 5A, the direction of the magnetic field Hs provided by the quadrupole auxiliary magnet 13 is the positive direction of the z axis (the same direction as the current I, in other words, the same direction as the longitudinal direction of the bus bar 102). A 4-pole auxiliary magnet 13 is installed. Further, the positive direction of the z-axis is set as the reference direction (angle 0 °). The direction of the magnetic moment Hip generated by the current I is taken as the x axis.

  The current I is allowed to change in the range of 0 A to the maximum allowable current Ip_max (for example, 300 A), and when the current I (overcurrent) exceeding the maximum allowable current Ip_max flows, the electric motor / generator 70 Consider a regenerative system 100 that stops operation. When the current I changes between 0 and Ip_max (A), the magnitude of the magnetic field Hip generated by the current I also changes in proportion to the current I in the range of 0 to Hipo (= Ip_max / 2πr). To do. That is, Hipo is the maximum allowable value of the magnetic field Hip, and is set to Hipo = Hs. The current sensor 10 is arranged and calibrated at a position (distance r) at which this relationship is obtained. However, the direction of the magnetic field Hip is the X-axis direction regardless of the magnitude of the current I.

  The current sensor 10 detects the direction (angle θ) of the combined magnetic field M of the magnetic field Hip and the aforementioned magnetic field Hs, and outputs detection signals from the output terminals B, D, E, and G. The CPU 25 calculates the angle θ and further tan θ based on this detection signal. Whether the current I is a discharge current or a charge current can be determined based on whether the angle θ is positive or negative. Further, the current I is calculated based on the following equation.

[Equation 2]
I = Hip / 2πr
= Hs · tanθ / 2πr

  Here, θ and tan θ are in a relation that can be approximated by a linear function within the range of −45 ° ≦ θ ≦ 45 ° (FIG. 6). The relationship can also be approximated by a linear function. When θ is outside the range of −45 ° ≦ θ ≦ 45 °, tan θ increases exponentially with increasing θ, and a linear output signal cannot be obtained with respect to the detection signal of the current sensor 10. Therefore, the detection range of the current sensor 10 is preferably set to −45 ° ≦ θ ≦ 45 °.

  The above describes the operation when the current sensor 10 detects the magnitude of the direct current I. The operation in the case where the current sensor 10 is arranged in the bus bar 102 through which an alternating current I = Iosin ωt (ω is an alternating angular frequency) flows will be described below with reference to FIG.

  In this case, the magnitude of the magnetic field Hip generated by the current I can be expressed by the following equation.

[Equation 3]
Hip = Hipo x sin ωt
However, Hipo = Io / 2πr

  As in the case of the direct current, when the magnitude of the magnetic field Hip is larger than the magnetic field Hs, the angle θ exceeds ± 45 °, and the value of tan θ exceeds 1 as shown in the following formula. In this case, it can be determined that the current I is an overcurrent.

[Equation 4]
tan θ = Hip / Hs
= (Hipo × sinωt) / Hs

If the amplitude Io of the current I is small, and therefore the amplitude Hipo of the magnetic field Hip is less than or equal to the magnetic field Hs, tan θ is less than or equal to 1 regardless of the phase wt. Determined.
On the other hand, when the amplitude Io of the current I increases and thereby the amplitude Hipo of the magnetic field Hip becomes larger than the magnetic field Hs, tan θ becomes larger than 1 in any of the ranges 0 ≦ ωt ≦ 360 °. In this case, it can be determined that the current I is an overcurrent. This is the same when the current I is discharged and charged.
8 to 10 show the magnetic field Hip at each phase wt (−90 °, 0 °, 90 °, 180 °, −180 °) and the combined magnetic field M when the amplitude Hipo of the magnetic field Hip is just equal to the magnetic field Hs. Is shown. In this case, in any phase wt, the angle θ is within ± 45 °, and the current I is determined to be appropriate.

  On the other hand, FIG. 11 shows a case where the amplitude Hipo of the magnetic field Hip is larger than the magnitude of the magnetic field Hs, and therefore the angle θ exceeds ± 45 ° in a partial range of the phase wt. In this case, it is determined that the current I is an overcurrent.

Thus, in the monitoring system according to the first embodiment, the magnitude of the current I can be detected as the angle θ of the combined magnetic field M. The tan θ and the current I are in a proportional relationship, and the relationship between the detection signal and the output signal can be expressed by a linear function.
In the monitoring system according to the first embodiment, the current sensor 10 includes a magnetic detection element 12 made of permalloy and a four-pole auxiliary magnet 13 made of a rare earth permanent magnet. Therefore, the operating temperature range is wide, current can be detected stably even in a high temperature environment such as an engine room of a vehicle, and the charge / discharge state can be monitored accurately and reliably.

  In addition, the monitoring system configures the current sensor 10 to detect a change in the angle θ of the combined magnetic field M of the magnetic field Hip generated by the current I and the magnetic field Hs of the quadrupole auxiliary magnet 13 in a range of ± 45 °. Yes. For this reason, since the relationship between the angle θ detected by the current sensor 10 and the current I can be approximated by a linear function, a highly accurate current sensor 10 can be provided.

  The current sensor 10 including the magnetic detection element 12 made of permalloy and the quadrupole auxiliary magnet 13 made of a rare earth permanent magnet has a broadband response characteristic of about 1 MHz, for example. For this reason, by setting the circuit elements and clock frequency of the ECU 20, the control loop time can be greatly shortened and a wideband response of, for example, 500 KHz can be realized.

  FIG. 12 is a side view showing another configuration of the current sensor of this monitoring system, and FIG. 13 is a plan view showing a 4-pole auxiliary magnet. In the following description, the same reference numerals are given to the same portions as those already described, and description thereof is omitted. As shown in FIG. 12, the current sensor 10 </ b> A is configured monolithically on the silicon substrate with the above-described magnetic detection element and the 4-pole auxiliary magnet.

  That is, the current sensor 10A includes a silicon substrate 14, a silicon oxide film layer (SiO2) 15, a conductor film layer 16, a silicon nitride film layer (SiNx) 17, a chromium film layer (Cr) 18, and a magnetic film. A layer 19, a chromium film layer (Cr) 27, and a passivation film layer (silicon nitride film layer) 28 are provided.

  In this example, an AMR effect element (Anisotropy Magnetic Sensor) is formed as an example of a magnetic detection element. This AMR effect element is disposed in the magnetic field H of the magnetic field H generated by the current I, and a detection signal corresponding to the angle θ of the combined magnetic field M of the magnetic field Hip generated by the current I and the magnetic field Hs provided by the quadrupole auxiliary magnet. Is output.

  The magnetic detection element is not limited to the AMR effect element, and the current sensor 10A may include a magnetoresistive effect element such as a GMR sensor, a TMR sensor, or a CMR sensor instead of the AMR effect element. .

  The magnetic film layer 19 is a layer on which the quadrupole auxiliary magnet 160 shown in FIG. 13 is formed. The magnetic film layer 19 is formed of a ferromagnetic material such as samarium (Sm) or cobalt (Co), and has a predetermined direction. Fixedly magnetized. A combined magnetic field M of the magnetic field Hs provided by the quadrupole auxiliary magnet 160 and the magnetic field Hip generated by the current I flowing through the bus bar 102 is provided.

  The conductor film layer 16 is a layer that constitutes a magnetic detection element, and is constituted by bridging ferromagnetic materials such as permalloy (for example, an alloy of Ni: Fe = 81: 19). When the direction of the combined magnetic field M changes depending on the magnitude of the magnetic field Hip, the magnetoresistance of the magnetoresistive element bridge-connected in the magnetic detection element changes. By detecting this change in magnetoresistance, the angle of the combined magnetic field M as described above is detected. Since such bridge connection is well known, description thereof is omitted.

  The chromium film layers 18 and 27 are formed so as to sandwich the magnetic film layer 19 from above and below, and have a role of preventing samarium (Sm) oxidation of the magnetic film layer 19. The passivation film layer 28 is made of, for example, a silicon nitride film (SiNx), and has a role of protecting the chromium film layer 27.

  As shown in FIG. 13, the quadrupole auxiliary magnet 160 formed on the magnetic film layer 19 and arranged close to the AMR effect element of the conductor film layer 16 is a cross-shaped magnet, and is a horizontal line (x-axis) passing through the center O. : Magnetized so that a magnetic field is formed in directions of 0 ° and 90 ° with respect to the reference direction). The combined magnetic field formed by combining the magnetic fields in the directions of 0 ° and 90 ° is configured to face the 45 ° direction with respect to the reference direction (x axis).

  Specifically, the four-pole auxiliary magnet 160 configured as described above includes a radial magnet portion 161 and a demagnetizing magnet portion 162. The radial magnet part 161 includes first magnetic pole pieces 161a to 161d and a ferromagnetic part 161z. The ferromagnetic part 161z is located at the center of the radial magnet part 161, and specifically, is arranged so that the center thereof substantially coincides with the center O. The ferromagnetic part 161z is made of, for example, iron (Fe).

  The first magnetic pole pieces 161a to 161d are arranged radially at intervals of 90 ° so as to be in contact with one of the four sides of the ferromagnetic part 161z. That is, the first magnetic pole piece 161a is arranged in the positive direction (0 ° direction) of the x axis when viewed from the center O. Further, the first magnetic pole piece 161b is arranged in the positive direction (90 ° direction) of the y-axis when viewed from the center O.

  Further, the first magnetic pole piece 161c is disposed in the negative x-axis direction (180 ° direction) as viewed from the center O, and the first magnetic pole piece 161d is the negative y-axis direction (270 ° direction) as viewed from the center O. Is arranged. The radial magnet portion 161 is magnetized so that a magnetic field is formed in the x-axis direction (0 ° direction) and the y-axis direction (90 ° direction).

  For this reason, the first magnetic pole pieces 161a and 161b are magnetized so as to have an N pole at the tip in the radial direction and an S pole at the opposite end. On the contrary, the first magnetic pole pieces 161c and 161d are magnetized so as to have an S pole in the radial direction and an N pole at the opposite end. Therefore, the combined magnetic field formed by combining the magnetic fields formed by the four first magnetic pole pieces 161a to 161d is a magnetic field oriented in the 45 ° direction with respect to the x axis, for example.

  The demagnetizing magnet unit 162 includes two second magnetic pole pieces 162a and 162b. The second magnetic pole piece 162a is defined by a first rectangular region 164 sandwiched between the first magnetic pole pieces 161a and 161b (a virtual line extending from the contour portion of the first magnetic pole piece 161a and the contour portion of the first magnetic pole piece 161b). In this example, it has a substantially rhombus shape.

  The second magnetic pole piece 162a is magnetized along the 45 ° direction with respect to the x-axis. Thereby, as will be described later, it has a function of erasing a reverse magnetic field in a direction opposite to the combined magnetic field obtained by combining the magnetic fields generated by the first magnetic pole pieces 161a to 161d. The vertex at furthest from the center O preferably has an acute angle α (<90 °) and is located outside the first rectangular region 164.

  The second magnetic pole piece 162b is a second rectangular region 165 sandwiched between the first magnetic pole pieces 161c and 161d (an imaginary line obtained by extending the outline of the first magnetic pole piece 161c and the outline of the first magnetic pole piece 161d). (Region defined by). Similar to the second magnetic pole piece 162a, the second magnetic pole piece 162b is magnetized along the 45 ° direction with respect to the x-axis in order to erase the aforementioned reverse magnetic field. The vertex bt farthest from the center O preferably has an acute angle α (<90 °) and is located outside the second rectangular region 165.

  Due to the presence of the second magnetic pole pieces 162a and 162b, undesirable magnetic field lines (reverse magnetic fields) generated by the radial magnet portions 161 can be eliminated. The second magnetic pole pieces 162a and 162b are formed to be sandwiched between first magnetic pole pieces 161a to 161d whose tips are magnetized in the same direction.

  In the case shown in FIG. 13, the second magnetic pole piece 162a is formed so as to be sandwiched between the first magnetic pole pieces 161a and 161b magnetized so that the tip has an N pole, while the second magnetic pole piece 162b is It is formed so as to be sandwiched between first magnetic pole pieces 161c and 161d magnetized so that the tip has an S pole.

  The second magnetic pole pieces 162a and 162b are preferably formed so as to have substantially the same area as each of the first magnetic pole pieces 161a to 161d (when formed with the same structure and the same material). . This is because the reverse magnetic field cannot be sufficiently erased if the areas differ greatly.

  Further, it is desirable that the vertices A1 and A2 of the second magnetic pole pieces 162a and 162b substantially coincide with the apex on the tip side of the first magnetic pole pieces 161a and 161b (hereinafter referred to as “one-point crossover”). This is because if the vertices of both do not match, the reverse magnetic field is not sufficiently erased. For this reason, the error of the position of both vertices is suppressed to about ± 1 μm.

  Further, at the vertices A1 and A2, the angle β1 formed by the side on the tip side of the first magnetic pole pieces 161a to 161d and the side of the second magnetic pole pieces 162a and 162b adjacent to this side is set to an obtuse angle (> 90 °). It is desirable to be done. This is because, when this portion has an acute angle, demerits such as the reverse magnetic field becoming larger occur.

  As described above, the second magnetic pole pieces 162a and 162b are preferably formed so as to satisfy the following three conditions (1) to (3). In particular, the conditions (1) and (3) are strongly required from the viewpoint of eliminating the reverse magnetic field and improving the detection accuracy. The three conditions (1) to (3) are as follows.

(1) One second magnetic pole piece 162a, 162b has substantially the same area as one first magnetic pole piece 161a-161d.
(2) The apexes A1 and A2 of the second magnetic pole pieces 162a and 162b substantially coincide with the apexes on the tip side of the first magnetic pole pieces 161a to 161d.
(3) The accuracy β1 is an obtuse angle.
As long as the two conditions (1) and (3), preferably (1) to (3) are satisfied, the second magnetic pole pieces 162a and 162b should have various shapes. Can do. For example, it may have a hexagonal shape or an octagonal shape, and may have a so-called cracked shape or a leaf shape instead of a polygonal shape.

  When the demagnetizing magnet portion 162 (second magnetic pole pieces 162a and 162b) configured as described above is not present, the radial magnet portion 161 is provided in the vicinity of the first rectangular region 164 and the second rectangular region 165, although illustration is omitted. A reverse magnetic field is generated in the opposite direction to the combined magnetic field formed by the. This reverse magnetic field may interfere with the detection of the angle of the combined magnetic field M. In order to eliminate such a reverse magnetic field, it is possible to perform a step of generating a magnetic field in the direction of 45 ° with respect to the quadrupole auxiliary magnet 160 when viewed from the x-axis. However, implementation of such a process leads to an increase in detection angle error and usually increases the manufacturing cost of the quadrupole auxiliary magnet.

  On the other hand, in the case of the above-described four-pole auxiliary magnet 160, such a reverse magnetic field is erased by the second magnetic pole pieces 162a and 162b magnetized in the 45 ° direction. Therefore, the angle of the synthetic magnetic field M can be detected accurately and reliably. Further, the second magnetic pole pieces 162a and 162b having such a magnetization direction can be easily formed by using a semiconductor processing process, and form a four-pole auxiliary magnet 160 without reverse magnetism with a high yield and low cost. be able to. In addition to the 4-pole auxiliary magnets 13 and 160 included in the current sensors 10 and 10A described above, for example, 8-pole or 16-pole multipole auxiliary magnets may be used.

[Second Embodiment]
FIG. 14 is a diagram showing a configuration of a hybrid system to which the charge / discharge state monitoring system according to the second embodiment of the present invention is applied. The monitoring system here is applied to, for example, a hybrid system (hereinafter abbreviated as “HV system”) 100A mounted on a vehicle such as an automobile.

  The HV system 100A is the same as the previous regenerative system 100 in that the storage battery 40, the inverter 60, and the electric motor / generator 70 are provided, but in addition, an engine such as an internal combustion engine that generates driving energy for driving the wheels 101. 80 and the transmission 90 which transmits the driving force from the engine 80 to the wheel 101 is different. Note that the monitoring system applied to the HV system 100A has the same configuration as that in the regenerative system 100, and includes a plurality of current sensors 10, the ECU 20, and the monitor 30.

  Even in the monitoring system in the HV system 100A configured as described above, the storage battery 40 is detected by the current sensor 10 attached to the bus bar 102 between the storage battery 40 and the inverter 60 when the wheel 101 is driven by the driving energy from the engine 80. The state of charge to is monitored.

  Further, when the wheel 101 is driven by the discharge from the storage battery 40, the current sensor 10 attached to the bus bar 102 between the motor / generator 70 and the inverter 60 monitors the discharge state to the motor / generator 70. . Other functions and effects are the same as those described above, and a description thereof will be omitted.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to these embodiments, and various modifications and additions can be made without departing from the spirit of the invention. For example, in the first embodiment, a ring-shaped permanent magnet is used as the four-pole auxiliary magnet 13 of the current sensor 10, but the four-pole auxiliary magnet is not particularly limited to a ring shape, for example, an elliptical permanent magnet. It is also possible to use magnets. In this case, magnetization may be performed at an angle symmetric with respect to the short axis or the long axis.

  In the first and second embodiments, the regenerative system 100 and the HV system 100A have been described as examples to which the monitoring system is applied. However, the brushless DC motor as well as the electric vehicle and the fuel cell electric vehicle are described. The above monitoring system may be applied to the control of the driving current and the direct current conversion control of the regenerative current of the brushless DC motor.

  In addition, the monitoring system can be used to monitor the charge / discharge state of a large-capacity battery, or various industrial control devices such as NC control machine tools, various robot devices, welding machines, and electric vehicles. It is also possible to use for monitoring the charge / discharge state in.

  DESCRIPTION OF SYMBOLS 10 ... Current sensor, 10A ... Current sensor, 11 ... Substrate, 12 ... Magnetic detection element, 13 ... Quadrupole auxiliary magnet, 14 ... Substrate, 15 ... Silicon oxide film layer, 16 ... Conductor film layer, 17 ... Silicon nitride film layer , 18 ... chrome film layer, 19 ... magnetic film layer, 20 ... ECU, 21 ... chrome film layer, 22 ... passivation film layer, 30 ... monitor, 40 ... storage battery, 60 ... inverter, 70 ... motor / generator, 80 ... engine, 90 ... transmission, 100 ... regenerative system, 100A ... hybrid system.

Claims (3)

A storage battery,
An electric motor / generator for generating power for driving a driving target using electric power discharged from the storage battery, and for generating electric power based on the operation of the driving target to charge the storage battery;
A current detection device that is disposed in the vicinity of a conductive member that forms a current path between the motor / generator and the storage battery and detects a current flowing through the conductive member;
A control unit that performs control to stop the operation of the motor / generator when the magnitude of the current reaches a predetermined value;
The current detection device includes:
An auxiliary magnet disposed in the vicinity of the conductive member and providing a first magnetic field;
A magnetic detection element disposed in the vicinity of the conductive member and outputting a detection signal that changes in accordance with a direction of a combined magnetic field of the first magnetic moment and a second magnetic field that changes according to the magnitude and direction of a current flowing through the conductive member. ,
The controller is configured to stop the operation of the electric motor / generator according to the detection signal. The auxiliary magnet is arranged to give the first magnetic field along a longitudinal direction of the conductive member,
The control unit stops the operation of the electric motor / generator when an angle formed by a direction of the synthetic magnetic field detected by the magnetic detection element with respect to a predetermined direction is outside a predetermined angle range. The charge / discharge state monitoring system according to claim 1.   The charge / discharge state monitoring system according to claim 2, wherein the controller stops the operation of the electric motor / generator when the angle reaches ± 45 ° with respect to the longitudinal direction of the conductive member.

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