JP2014085226A - Current detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current detection device capable of emitting a problem detection signal to prevent occurrence of serious accidents even when one of current sensors gets a problem.SOLUTION: A current sensor has a first current detection element, a second current detection element and a signal processing section. The current sensor is provided to only two current lines in three current lines on which three-phase AC current flows. When the output voltage from any of the first and second current detection elements is out of a predetermined range, the output voltage within the predetermined range in the output voltage from the first and second current detection elements is output after being character-adjusted and the problem detection signal is output.

Description

  The present invention relates to a current detection device for detecting a current in an electronic device, and more particularly to a current detection device for detecting a current value and a current phase of a current supplied to a three-phase AC motor of an electric vehicle or a hybrid vehicle. .

  Conventionally, as this type of current detection device, one in which a Hall element is disposed in a gap of a magnetic collecting core through which a bus bar passes is known. FIG. 5 is a block diagram when such a current detection device is applied to control of a drive system of an electric vehicle or the like.

  In FIG. 5, a motor control device that controls a three-phase AC motor 1 (hereinafter referred to as “motor” as appropriate) includes an IGBT substrate 2, an IGBT control substrate 3, and a motor control device 4. A high DC voltage of approximately 400 volts output from the main power supply 5 is converted by the IGBT substrate 2 into a three-phase AC voltage composed of a U phase, a V phase, and a W phase, and applied to the motor 1 by the bus bar.

  The motor control device 4 is supplied with motor rotation speed information Nm from a rotation sensor (not shown) of the motor 1 and accelerator position information ACL detected by an accelerator sensor (not shown). The current detection device 8 is provided as a current sensor on each of the U-phase, V-phase, and W-phase current lines of the motor 1 and detects the current value and current phase of each current line. The detected current information IU, IV, IW is input to the motor control device 4. Based on these pieces of information, the motor control device 4 outputs modulation signals MU, MV, and MW corresponding to the respective phases of the three-phase alternating current to be generated. The IGBT control board 3 controls the IGBT of the IGBT board 2 based on the modulation signals MU, MV, and MW generated in the motor control device 4.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP-A-9-304447

  Since the sum of the currents of the three-phase alternating current lines is always zero and the phases of the currents are shifted from each other by 120 degrees, the phases and magnitudes of the currents flowing through the U-phase, V-phase, and W-phase current lines It is sufficient to attach a current sensor to any two phases of each current line. However, in the motor control device described above, when an abnormality such as an offset or a gain characteristic occurs in the current detection device 8, an excessive or excessive current flows through the motor 1 and the controllability deteriorates. May cause damage. For this reason, in the conventional motor control device, current sensors are arranged on all of the U-phase, V-phase, and W-phase current lines, and even if an abnormality occurs in one of these current sensors, backup is performed by another current sensor. An abnormal detection signal is issued and a serious accident is prevented in advance.

  However, if current sensors are arranged on all of the U-phase, V-phase, and W-phase current lines, the current detection device itself becomes large, and the trouble and man-hour for attaching the current device to a predetermined position increases. was there.

  The present invention solves the above-mentioned conventional problems, and by providing a current sensor having two current detection elements only on two of the three current lines through which a three-phase AC current flows, It is possible to reduce the size of the detection device, reduce installation and adjustment, and even if an abnormality occurs in one of the two current detection elements in each current sensor, it is backed up by another current detection element. An object of the present invention is to provide a current detection device capable of preventing an accident and generating an abnormality detection signal at the same time.

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 is a current detection device in which a current sensor is provided only on two of the three current lines through which a three-phase alternating current flows, and each of the current sensors is a first one. A current detection element, a second current detection element, and a signal processing unit, and the output voltage of the first current detection element and the output voltage of the second current detection element are both within a predetermined range. Includes calculating the output voltage of the first current detection element and the output voltage of the second current detection element, then adjusting the characteristic of the output voltage after the calculation process, and outputting the first current. If any one of the output voltage of the detection element or the output voltage of the second current detection element is not within a predetermined range, it is determined that an abnormality has occurred in the current sensor and the first or second current is detected. The output voltage within the specified range of the output voltage of the detection element is specified. In addition to adjusting and outputting, it is configured to output an abnormality detection signal. According to this configuration, since two current sensors are required to be attached to the current line, the current detection device can be reduced in size, attached, The time for adjustment can be reduced, the output voltages of the two current detection elements provided in each current sensor are constantly monitored, and if any one of the abnormality occurs, an abnormality detection signal is issued and the other The output voltage of the current detection element can be used as the output signal of the current sensor, and there is an effect that a highly reliable current detection device can be realized.

  In the invention described in claim 2, in particular, the polarity of the output voltage of the first current detection element is different from the polarity of the output voltage of the second current detection element. Since the disturbance can be canceled, there is an effect that a current detecting device with more stable operation can be realized.

  As described above, the present invention is a current detection device in which a current sensor is provided only on two of the three current lines through which a three-phase alternating current flows. A current detection element, a second current detection element, and a signal processing unit, wherein the output voltage of the first current detection element and the output voltage of the second current detection element are both within a predetermined range; Performs a calculation process on the output voltage of the first current detection element and the output voltage of the second current detection element, then adjusts and outputs the output voltage after the calculation process, and outputs the first current detection element. If any one of the output voltage of the element or the output voltage of the second current detection element is not within a predetermined range, it is determined that an abnormality has occurred in the current sensor and the first or second current detection is performed. Characteristic output voltage within the specified range of element output voltage The current detection device can be reduced in size and can be reduced in installation and adjustment, and the two sensors provided in each current sensor. Even when an abnormality occurs in one of the current detection elements, an excellent effect is achieved in that a highly reliable current detection device can be realized by performing backup with the other current detection element.

The perspective view of the electric current detection apparatus in Embodiment 1 of this invention (A) The perspective view of the 1st current sensor which comprises the current detection apparatus in Embodiment 1 of this invention, (b) The longitudinal cross-sectional view of the 1st current sensor of the same current detection apparatus The block diagram which shows the circuit structure of the current sensor in the current detection apparatus in Embodiment 1 of this invention. (A) A perspective view of a current detection device according to Embodiment 2 of the present invention, (b) a longitudinal sectional view of a first current sensor of the current detection device. Block diagram of a drive system for an electric vehicle or the like using a conventional current detection device

(Embodiment 1)
Hereinafter, the current detection device according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a current detection device 21 according to Embodiment 1 of the present invention. In FIG. 1, 22U, 22V, and 22W are current lines through which three-phase AC U-phase, V-phase, and W-phase currents flow, respectively. The current detection device 21 includes a first current sensor 23 and a second current sensor 24 having the same structure. In FIG. 1, the first current sensor 23 and the second current sensor 24 are attached to the current lines 22U and 22V, respectively, but any two of the three current lines 22U, 22V and 22W. Can be installed on. When the XYZ axes are taken as illustrated, the current lines 22U, 22V, and 22W are assumed to extend in the X-axis direction within the XY plane.

  2A is a perspective view of the first current sensor 23, and FIG. 2B is a longitudinal sectional view of the sensor. The first current sensor 23 detects a current by detecting a magnetic field generated around the current, a first current detection element 24-1, a second current detection element 24-2, and a signal processing unit. 25. Magnetoresistive elements are used for the first current detecting element 24-1 and the second current detecting element 24-2. Although a Hall element can be used instead of the magnetoresistive element, in this case, a first bias magnet 26-1 and a second bias magnet 26-2 described later can be dispensed with. A first bias magnet 26-1 is provided in the vicinity of the first current detection element 24-1, and a second bias magnet 26-2 is provided in the vicinity of the second current detection element 24-2. . The first bias magnet 26-1 and the second bias magnet 26-2 are output particularly when the first current detection element 24-1 and the second current detection element 24-2 are magnetoresistive elements. This contributes to the improvement of linearity and the reduction of hysteresis.

  The first current sensor 23 includes a first holding unit 30, a second holding unit 31, and a connecting unit 32. The first holding unit 30 holds the first and second current detection elements 24-1 and 24-2 and the first and second bias magnets 26-1 and 26-2. The first and second holding portions 30 and 31 extend in the same direction with a space therebetween. The connecting portion 32 has a cylindrical shape extending in a direction perpendicular to the extending direction of the first holding portion 30 and the second holding portion 31, and connects the first holding portion 30 and the second holding portion 31. ing. As a result, the first holding unit 30, the second holding unit 31, and the connecting unit 32 are integrally formed to constitute the first current sensor 23.

  A method of attaching the first current sensor 23 of the current detection device 21 in the first embodiment of the present invention to the current line 22U will be briefly described with reference to FIGS. First, the first current sensor 23 is disposed between the current lines 22U and 22V. At this time, the extending directions of the first holding unit 30 and the second holding unit 31 are arranged so as to be substantially parallel to the X axis. Next, the first current sensor 23 is rotated around the Z axis, and the current line 22 </ b> U is held between the first holding unit 30 and the second holding unit 31. At this time, if the length of the connecting portion 32 is set to be substantially equal to the length of the current line 22U in the Z-axis direction, the surface of the current line 22U and the first and second current detection elements 24-1 and 24-2. 2 can be substantially fixed, and the first current sensor 23 can be clamped and fixed to the current line 22U. In this state, the first current detection element 24-1 and the second current detection element 24-2 are within the first holding unit 30, and the surface of the first current detection element 24-1 and the current line 22U. And the distance between the second current detection element 24-2 and the surface of the current line 22U are equal. Furthermore, if the connecting portion 32 is pressed against the end surface of the current line 22U in the Y-axis direction, the positions of the first and second current detection elements 24-1 and 24-2 in the Y-axis direction can be determined. Become. Similarly, if the second current sensor 24 is attached to the current line 22V, the current detection device 21 according to the first embodiment of the present invention shown in FIG. 1 can be configured.

  When three-phase AC U-phase, V-phase, and W-phase currents flow through the current lines 22U, 22V, and 22W in the X-axis direction, a loop-shaped magnetic field is generated in the YZ plane of each current line. The first current sensor 23 and the second current sensor 24 output a signal corresponding to the current value and current phase of the U-phase and V-phase currents by detecting this magnetic field.

  FIG. 3 is a block diagram showing a circuit configuration of the first current sensor 23 in the current detection device 21 according to Embodiment 1 of the present invention. The first current detection element 24-1 and the second current detection element 24-2 are each provided with four magnetoresistive elements constituting a full bridge circuit. A DC voltage is applied between the two contact points of the full bridge circuit, and the potential between the other two contact points is connected to the input terminal of a differential amplifier (not shown). An output voltage v1 of the differential amplifier (not shown) connected to the first current detection element 24-1 and an output voltage v1 of the differential amplifier (not shown) connected to the second current detection element 24-2. The output voltage v2 is input to the signal processing unit 25. The signal processing unit 25 includes a calculation unit 40, a detection unit 41, and a characteristic adjustment unit 42, and has an output terminal 50 and a state detection terminal 51.

  When a current flows through the current line 22U, the balance of the full bridge circuit of the first current detection element 24-1 and the second current detection element 24-2 is broken, and output signals v1 and v2 having the same polarity are output from the differential amplifiers. Is input to the signal processing unit 25. Whether the output signals v1 and v2 are within a predetermined voltage range is determined by the detection unit 41. The detection unit 41 can be formed by a window comparator. When the output signals v1 and v2 are within a predetermined range, a control signal is sent from the detection unit 41 to the calculation unit 40 to perform addition calculation of the output signals v1 and v2, and then the characteristic adjustment unit 42 Voltage level adjustment, offset adjustment, and the like are performed, and a signal corresponding to the current value and current phase of the U-phase current is output from the output terminal 50. On the other hand, when the detection unit 41 determines that one of the output signals v1 and v2 is not within the predetermined range, it is determined that an abnormality has occurred in the first current sensor 23, and the detection is performed. A control signal is sent from the unit 41 to the calculation unit 40 to stop the addition calculation, and an abnormality detection signal is output to the state detection terminal 51. The detection unit 41 selects an output voltage within a predetermined range from the output signals v1 and v2 and sends the output voltage to the characteristic adjustment unit 42. The characteristic adjustment unit 42 performs voltage level adjustment, offset adjustment, and the like. A signal corresponding to the current value and current phase of the U-phase current is output from the output terminal 50. Similarly, when the second current sensor 24 outputs a signal corresponding to the current value and current phase of the current flowing through the current line 22V, and it is determined that an abnormality has occurred in the second current sensor 24. In this case, an abnormality detection signal is output. In the current detection device 21 according to the first embodiment of the present invention, the first current sensor has two current detection elements only in two of the three current lines 22U, 22V, and 22W through which a three-phase alternating current flows. Since the current sensor 23 and the second current sensor 24 are provided, it is possible to reduce the size of the current detection device, reduce the time and effort of mounting and adjustment, and detect two currents in each current sensor. Even when an abnormality occurs in one of the elements, backup is performed by another current detection element, and an effect that an abnormality detection signal can be generated at the same time as preventing a serious accident in advance is obtained.

(Embodiment 2)
Hereinafter, a current detection device according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 4A is a perspective view of the current detection device 60 according to Embodiment 2 of the present invention. The current detection device 60 includes a first current sensor 61 and a second current sensor 62 having the same structure. FIG. 4B is a longitudinal sectional view of the first current sensor 61. In the current detection device 60 according to the second embodiment of the present invention, components having the same configuration as the configuration of the current detection device 21 according to the first embodiment of the present invention described above are denoted by the same reference numerals. The description thereof is omitted.

  4 (a) and 4 (b), the current detection device 60 according to the second embodiment of the present invention is different from the current detection device 21 according to the first embodiment of the present invention described above in that the first current sensor 61. , The first current detection element 24-1 and the first bias magnet 26-1 are arranged in the first holding unit 30, and the second current detection element 24-2 and the second bias magnet 26-2 are arranged. Is arranged in the second holding part 31.

  3, 4 (a) and (b), when the U-phase, V-phase and W-phase currents of the three-phase alternating current flow in the X-axis direction respectively in the current lines 22U, 22V and 22W, the YZ plane of each current line A loop-shaped magnetic field is generated. In the current detection device 60 according to the second embodiment of the present invention, the first current detection element 24-1 and the second current detection element 24-2 are provided on the front and back of the current line 22U. The polarity of the output signal v1 of the differential amplifier of the current detection element 24-1 and the output signal v2 of the differential amplifier of the second current detection element 24-2 are opposite. On the other hand, when a uniform external magnetic field is applied to the current detection device 60 according to the second embodiment of the present invention, the differential amplifier of the first current detection element 24-1 and the second current detection element 24- The two differential amplifiers output signals having the same polarity and the same magnitude. It is determined whether or not these output signals v1 and v2 are within a predetermined voltage range by the detection unit 41. When the output signals v1 and v2 are within the predetermined range, the detection unit 41 to the calculation unit 40 After the control signal is sent to the subtracting operation of the output signals v 1 and v 2, the characteristic adjustment unit 42 performs voltage level adjustment, offset adjustment, etc., and outputs the current value of the U-phase current from the output terminal 50. A signal corresponding to the current phase is output. On the other hand, when the detection unit 41 determines that any one of the output signals v1 and v2 is not within the predetermined range, it is determined that an abnormality has occurred in the first current sensor 61 and is detected. A control signal is sent from the unit 41 to the calculation unit 40 to stop the addition calculation, and an abnormality detection signal is output to the state detection terminal 51. The detection unit 41 selects an output voltage within a predetermined range from the output signals v1 and v2 and sends the output voltage to the characteristic adjustment unit 42. The characteristic adjustment unit 42 performs voltage level adjustment, offset adjustment, and the like. A signal corresponding to the current value and current phase of the U-phase current is output from the output terminal 50. Similarly, when the second current sensor 62 outputs a signal corresponding to the current value or current phase of the current flowing through the current line 22V, and it is determined that an abnormality has occurred in the second current sensor 62. In this case, an abnormality detection signal is output.

  According to this configuration, since the disturbance due to the external magnetic field can be canceled, there is an effect that it is possible to realize a current detecting device with further stable operation.

  The present invention can be miniaturized, can reduce the time and effort of mounting and adjustment, and even if an abnormality occurs in one of the two current detection elements provided in the current sensor, the other current detection element By performing backup, a highly reliable current detection device can be realized, and in particular, it is useful as a current detection device for detecting a motor drive current of an electric vehicle or a hybrid vehicle.

21, 60 Current detection device 22U, 22V, 22W Current line 23, 61 First current sensor 24, 62 Second current sensor 24-1 First current detection element 24-2 Second current detection element 25 Signal processing Part

Claims (2)

A current detection device in which a current sensor is provided only on two of the three current lines through which a three-phase alternating current flows, wherein each of the current sensors includes a first current detection element and a second current The first current detection element when the output voltage of the first current detection element and the output voltage of the second current detection element are both within a predetermined range. After calculating the output voltage of the element and the output voltage of the second current detection element, the output voltage after the calculation process is adjusted and output, and the output voltage of the first current detection element or the second current detection element is output. If any one of the output voltages of the current detection elements is not within the predetermined range, it is determined that an abnormality has occurred in the current sensor, and a predetermined one of the output voltages of the first or second current detection elements is determined. Adjust the characteristics of the output voltage within the range and output it. , Current detecting device and outputting an abnormality detection signal. The current detection device according to claim 1, wherein the polarity of the output voltage of the first current detection element is different from the polarity of the output voltage of the second current detection element.

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