JP2015192582A - Current-sensor failure detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current-sensor failure detection apparatus capable of identifying a failed current sensor among current sensors provided respectively for three-phase AC, while reducing processing time for detecting a failure.SOLUTION: A failure detection apparatus includes: current sensors, disposed respectively for three phases of a three-phase AC motor; sum current calculation means for calculating a sum current that is a sum of three-phase currents detected by the current sensor at first timing when a current detected by a current sensor disposed to a given phase of the three-phase AC motor is zero(0), the sensor among the current sensors, and at second timing that is shifted 90 degrees from the first timing; and identification means for identifying a current sensor outputting an abnormal value, among the current sensors, on the basis of the sum current calculated by the sum current calculation means at the first and second timing.

Description

  The present invention relates to a failure detection device that detects a failure of a current sensor that detects a three-phase alternating current.

2. Description of the Related Art Conventionally, a failure detection device that can identify a current sensor in which a failure (gain deviation) has occurred among current sensors provided in each phase of a three-phase AC motor is known (for example, Patent Document 1).
In Patent Document 1, if the absolute value of the sum of the currents of the respective phases (three-phase sum current) detected by the current sensors provided in the respective phases is larger than a set value, one of the current sensors of each phase has failed. A failure detection apparatus that determines that an occurrence has occurred is disclosed. When it is determined that any failure has occurred, the failure detection device further identifies the current sensor in which the failure has occurred by comparing the polarity or absolute value of the current value of each phase current sensor. To do. For example, the current values of the current sensors of the respective phases are compared, and a current sensor that detects a current value having a polarity different from that of the other two current sensors is specified as a current sensor in which a failure has occurred. Further, the current values of the respective phases are compared, and the current sensor having the largest absolute value of the current value is specified as the failed current sensor.

JP 2006-311491 A

  However, the above-described failure detection device calculates a three-phase sum current with a very short period in order to determine that a failure has occurred in one of the current sensors when the absolute value of the three-phase sum current is larger than the set value. There is a risk that real-time control may fail due to an increase in processing time.

  That is, when a gain deviation failure occurs in any of the current sensors of each phase, the three-phase sum current is the set value at the timing (phase) where the value of the current sensor where the failure occurred is near the top of the AC waveform. Over. Therefore, in order to detect a failure of the current sensor, it is necessary to calculate the three-phase sum current at the timing when the absolute value of the current value detected by the current sensor of each phase becomes maximum, and during one cycle of the AC waveform It is necessary to calculate the three-phase sum current at least three times.

  Accordingly, in view of the above problems, there is provided a failure detection device for a current sensor that can identify a current sensor in which a failure has occurred among current sensors of each phase of a three-phase alternating current while reducing processing time for failure detection. For the purpose.

In order to achieve the above object, in one embodiment, a failure detection device for a current sensor comprises:
A current sensor that is arranged in each phase of the three-phase AC motor and detects a current of each phase;
Among the current sensors, a first timing at which a current detected by a current sensor arranged in a predetermined phase of the three-phase AC motor becomes 0, and a second phase shifted by 90 ° from the first timing. Sum current calculation means for calculating a sum current that is a sum of three-phase currents detected by the current sensor at the timing;
Specifying means for specifying a current sensor that outputs an abnormal value among the current sensors based on the sum current calculated at the first timing and the second timing by the sum current calculating means; Prepare.

  According to the present embodiment, it is possible to provide a failure detection device for a current sensor that can identify a current sensor in which a failure has occurred among current sensors of each phase of a three-phase alternating current while reducing processing time for failure detection. can do.

It is a block diagram which shows an example of a structure of the failure detection apparatus which concerns on this embodiment. It is a figure which shows the waveform with respect to time passage of the three-phase sum electric current at the time of normal of a current sensor. It is a figure which shows the waveform with respect to time passage of the three-phase sum electric current when abnormality generate | occur | produces in any one of a current sensor. It is a flowchart which shows an example of the failure detection process of the current sensor by the failure detection apparatus (abnormality detection part) which concerns on this embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram illustrating an example of a configuration of the failure detection apparatus 1 according to the present embodiment. The failure detection device 1 detects a failure of the current sensor 50 that detects the current of each phase of the motor 30 that is driven by three-phase AC power (to be described later) (the electric wire that supplies power).

  The failure detection apparatus 1 includes a current sensor 50, an abnormality detection unit 60, and the like. Further, the drive device including the motor 30 that is a target of current detection by the current sensor 50 includes the battery 10, the inverter 20, the motor 30, the connection line 40, and the like. In addition, the said drive device may be mounted in a vehicle and may function as a drive force source of a vehicle, and typically may be mounted in a hybrid vehicle, an electric vehicle, etc.

  The battery 10 is a power storage device (DC power supply) that supplies electric power to the motor 30. For example, although a lithium ion battery, a nickel metal hydride battery, etc. can be used, it is not restricted to these, Arbitrary secondary batteries may be used and a capacitor etc. may be used.

  The inverter 20 is power conversion means that converts the DC power supplied from the battery 10 into three-phase AC power and supplies the three-phase AC power to the motor 30.

  The motor 30 is a rotary electric motor driven by three-phase AC, and specifically, is driven by three-phase AC power supplied from the battery 10 via the inverter 20. For example, the motor 30 may drive the vehicle with electric power supplied from the battery 10 as one of the drive sources of the vehicle. The motor 30 may function as a generator. For example, the motor 30 as a vehicle drive source may function as a generator by a regenerative operation when the vehicle is decelerated, and may charge the battery 10 with the generated power. When the vehicle is a hybrid vehicle, the motor 30 may be driven by an engine (not shown) to generate power.

  The connection line 40 is an electric wire that connects the inverter 20 and the motor 30 in order to supply a three-phase alternating current from the inverter 20 to the motor 30. Connection line 40 includes a U-phase line 40 u connected to the U-phase of motor 30, a V-phase line 40 v connected to the V-phase of motor 30, and a W-phase line 40 w connected to the W-phase of motor 30.

  The current sensor 50 is current detection means for detecting the current of each phase of the motor 30 driven by three-phase alternating current. The current sensor 50 includes a U-phase current sensor 50 u that detects a U-phase current of the motor 30, a V-phase current sensor 50 v that detects a V-phase current of the motor 30, and a W that detects a W-phase current of the motor 30. A phase current sensor 50w is included.

  U-phase current sensor 50 u is arranged on U-phase line 40 u and outputs a signal corresponding to detected U-phase current Iu of motor 30 to abnormality detection unit 60.

  V-phase current sensor 50v is arranged on V-phase line 40v and outputs a signal corresponding to detected V-phase current Iv of motor 30 to abnormality detection unit 60.

  W-phase current sensor 50 w is arranged on W-phase line 40 w and outputs a signal corresponding to detected W-phase current Iw of motor 30 to abnormality detection unit 60.

  The abnormality detection unit 60 detects an abnormality of the current sensor 50 and any of the current sensors 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w) has an abnormality. It is an abnormality detection means for specifying whether or not. The abnormality detection unit 60 is a signal corresponding to the U-phase current Iu, V-phase current Iv, and W-phase current Iw of the motor 30 input from the U-phase current sensor 50u, V-phase current sensor 50v, and W-phase current sensor 50w. Based on the above, the abnormality of the current sensor 50 is detected and the current sensor in which the abnormality has occurred is identified. A specific method will be described later.

  Next, a failure detection method for the current sensor 50 by the failure detection apparatus 1 (abnormality detection unit 60) according to the present embodiment will be described.

  FIG. 2 shows a three-phase sum current (U-phase current Iu, V-phase current Iv, and W-phase current) when the current sensor 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w) is normal. It is a figure which shows an example of the waveform with respect to time passage of (sum of Iw). FIG. 2A is a diagram illustrating an example of waveforms with respect to time of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw when the current sensor 50 is normal, and FIG. It is a figure which shows the waveform with respect to time passage of the three-phase sum current corresponding to (a). 2A, the solid line indicates the U-phase current Iu detected by the U-phase current sensor 50u, and the alternate long and short dash line indicates the V-phase current Iv detected by the V-phase current sensor 50v. A chain line indicates the W-phase current Iw detected by the W-phase current sensor 50w. Moreover, in FIG.2 (b), a continuous line shows a three-phase sum electric current.

  As shown in FIG. 2A, each phase current in the three-phase AC current has a sinusoidal current waveform with the same amplitude and the same period. Further, the current of each phase is different (shifted) by 120 ° in the order of U phase → V phase → W phase. Therefore, when each current sensor 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w) is normal, the three-phase sum current is always approximately 0 [A] as shown in FIG. ].

  On the other hand, FIG. 3 shows the waveform of the three-phase sum current over time when an abnormality occurs in any one of the current sensors 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w). It is a figure which shows an example. FIG. 3A is a diagram illustrating an example of waveforms of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw over time. Specifically, the U-phase current Iu, the V-phase currents Iv, and W It is a figure which shows the phase relationship of the phase current Iw. FIG. 3B is a waveform with respect to the passage of time of the three-phase sum current corresponding to the phase relationship among the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw shown in FIG. It is an example of the waveform with respect to time passage of the three-phase sum current when abnormality (gain deviation) occurs in the phase current sensor 50u. FIG. 3C is a waveform with respect to the passage of time of the three-phase sum current corresponding to the phase relationship among the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw shown in FIG. It is an example of the waveform with respect to time passage of the three-phase sum current when abnormality (gain deviation) occurs in the phase current sensor 50v. 3D is a waveform with respect to time of a three-phase sum current corresponding to the phase relationship among the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw shown in FIG. It is an example of the waveform with respect to time passage of the three-phase sum current when abnormality (gain deviation) occurs in the phase current sensor 50w. In addition, the current value (amplitude) in each phase of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw shown in FIG. 3A has no specific meaning.

  When an abnormality (gain shift) occurs in the U-phase current sensor 50u, the amplitude of the U-phase current Iu detected by the U-phase current sensor 50u is determined by the V-phase current sensor 50v and the V-phase current Iv by the W-phase current sensor 50w, It becomes a value (abnormal value) larger than the amplitude of the W-phase current Iw. Therefore, as shown in FIG. 3B, the three-phase sum current appears as a waveform in phase with the U-phase current Iu in FIG.

  Similarly, when an abnormality (gain deviation) occurs in the V-phase current sensor 50v or the W-phase current sensor 50w, the three-phase sum current is as shown in FIGS. 3 (c) and 3 (d). It appears as a waveform in phase with the V-phase current Iv or the W-phase current Iw in 3 (a).

  In this way, unlike the waveform (always approximately 0 [A]) of the three-phase sum current in the normal state of the current sensor 50 shown in FIG. When it occurs, a waveform in phase with the current detected by the current sensor in which the abnormality has occurred appears as a three-phase sum current.

  Here, in FIG. 3A, when the U-phase current Iu detected by the U-phase current sensor 50u switches from a negative value to a positive value (the U-phase current Iu switches from a negative direction to a positive direction), The timing when 0 [A] is set is the first timing t1. Further, the timing that is shifted by 90 ° (the phase is advanced) from the first timing t1 is defined as a second timing t2. Then, the three-phase sum currents of FIGS. 3B to 3D are compared at the first timing t1 and the second timing t2. The three-phase sum current at the first timing t1 is I1, and the three-phase sum current at the second timing t2 is I2.

  In addition, if the rotation speed N [1 / s] of the motor 30, the frequency f [Hz] of the three-phase alternating current (U-phase current Iu), and the number of pole pairs P of the motor 30, the relationship N = f / P is established. Therefore, the time T [s] from the first timing t1 to 90 ° phase shift that is ¼ of one cycle of the U-phase current Iu is T = 1/4 NP. That is, the timing when the time T [s] has elapsed from the first timing t1 may be set as the second timing t2. The rotation speed N of the motor 30 may be detected by a resolver (not shown) or the like.

  First, when an abnormality has occurred in the U-phase current sensor 50u, as shown in FIG. 3B, the three-phase sum current has a waveform in phase with the U-phase current Iu. Therefore, at the first timing t1. The three-phase sum current I1 is approximately 0 [A] (I1 = 0 [A]). Further, the three-phase sum current I2 at the second timing t2 becomes a positive maximum value, that is, a value sufficiently larger than 0 [A] (I2> 0 [A]).

  Further, when an abnormality has occurred in the V-phase current sensor 50v, as shown in FIG. 3C, the three-phase sum current has a waveform in phase with the V-phase current Iv. Therefore, at the first timing t1. The three-phase sum current I1 is a negative value, that is, a value sufficiently smaller than 0 [A] (I1 <0 [A]). The three-phase sum current I2 at the second timing t2 is also a negative value, that is, a value sufficiently smaller than 0 [A] (I2 <0 [A]).

  When an abnormality occurs in the W-phase current sensor 50w, the three-phase sum current has a waveform in phase with the W-phase current Iw as shown in FIG. The three-phase sum current I1 is a positive value, that is, a value sufficiently larger than 0 [A] (I1> 0 [A]). The three-phase sum current I2 at the second timing t2 is a negative value, that is, a value sufficiently smaller than 0 [A] (I2 <0 [A]).

  That is, the three-phase sum current I1 at the first timing t1 is approximately 0 [A] (I1 = 0 [A]), and the three-phase sum current I2 at the second timing t2 is less than 0 [A]. When sufficiently large (I2> 0 [A]), it can be specified that an abnormality has occurred in the U-phase current sensor 50u.

  The three-phase sum current I1 at the first timing t1 is sufficiently smaller than 0 [A] (I1 <0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently smaller (I2 <0 [A]), it can be specified that an abnormality has occurred in the V-phase current sensor 50v.

  The three-phase sum current I1 at the first timing t1 is sufficiently larger than 0 [A] (I1> 0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently smaller (I2 <0 [A]), it can be specified that an abnormality has occurred in the W-phase current sensor 50w.

  Further, as described above, when the current sensor 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w) is normal, the three-phase sum current is always approximately 0 [A]. Accordingly, as shown in FIG. 2, the three-phase sum current I1 at the first timing t1 is approximately 0 [A] (I1 = 0 [A]), and the three-phase sum current at the second timing t2. When I2 is approximately 0 [A] (I2 = 0 [A]), it can be determined that the current sensor 50 is normal.

  Note that the three-phase sum currents I1 and I2 being approximately 0 [A] means that the three-phase sum current is within a range of 0 [A] due to an error or the like when the current sensor 50 is normal. . Also, the three-phase sum currents I1 and I2 being sufficiently larger or smaller than 0 [A] means exceeding the above range of variation and larger than 0 [A] or smaller than 0 [A]. means. For example, if the absolute value of the three-phase sum current is equal to or less than the set value with respect to the set value assumed due to the above-described variation, it can be said that the three-phase sum current is approximately 0 [A]. When the absolute value of the three-phase sum current exceeds the set value, it can be said that the value is sufficiently larger or smaller than 0 [A] depending on whether the value of the three-phase sum current is positive or negative.

  Next, a specific failure detection processing operation to which the failure detection method of the current sensor 50 (U-phase current sensor 50u, V-phase current sensor 50v, W-phase current sensor 50w) described above is applied will be described.

  FIG. 4 is a flowchart illustrating an example of a failure detection process of the current sensor 50 by the failure detection device 1 (abnormality detection unit 60) according to the present embodiment. The abnormality detection unit 60 calculates the three-phase sum currents I1 and I2 at the first timing t1 and the second timing t2 during one cycle of the U-phase current Iu, and the processing flow includes the three-phase sum current I1, It is executed every time I2 is calculated.

  Referring to FIG. 4, in step S101, it is determined whether or not both the three-phase sum current I1 at the first timing t1 and the three-phase sum current I2 at the second timing t2 are substantially 0 [A]. Is done.

  When the three-phase sum currents I1 and I2 are both approximately 0 [A], the process proceeds to step S109. In step S109, it is detected that the current sensor 50 is normal, and the current process is terminated.

  On the other hand, if the determination condition is not satisfied, the process proceeds to step S102.

  In step S102, the three-phase sum current I1 at the first timing t1 is approximately 0 [A] (I1 = 0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. It is determined whether or not it is sufficiently larger (I2> 0 [A]).

  When the three-phase sum current I1 is approximately 0 [A] and the three-phase sum current I2 is sufficiently larger than 0 [A], the process proceeds to step S105, and an abnormality of the U-phase current sensor 50u is detected, and this time Terminate the process.

  On the other hand, if the determination condition is not satisfied, the process proceeds to step S103.

  In step S103, the three-phase sum current I1 at the first timing t1 is sufficiently smaller than 0 [A] (I1 <0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently smaller (I2 <0 [A]).

  When the three-phase sum current I1 is sufficiently smaller than 0 [A] and the three-phase sum current I2 is sufficiently smaller than 0 [A], the process proceeds to step S106, and an abnormality of the V-phase current sensor 50v is detected. This process is terminated.

  On the other hand, if the determination condition is not satisfied, the process proceeds to step S104.

  In step S104, the three-phase sum current I1 at the first timing t1 is sufficiently larger than 0 [A] (I1> 0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently smaller (I2 <0 [A]).

  When the three-phase sum current I1 is sufficiently larger than 0 [A] and the three-phase sum current I2 is sufficiently smaller than 0 [A], the process proceeds to step S107, and an abnormality of the W-phase current sensor 50w is detected. This process is terminated.

  On the other hand, when the determination condition is not satisfied, the process proceeds to step S108, where abnormality of a plurality of current sensors in the current sensor 50 is detected, and the current process is terminated.

  As described above, when the U-phase current Iu is switched from the negative value to the positive value, the first timing t1 at which the U-phase current Iu becomes 0 [A] and the second timing t2 that is shifted by 90 ° from the first timing t1. The failure of the current sensor 50 can be detected based on the three-phase sum currents I1 and I2. Specifically, the presence or absence of abnormality in the current sensor 50 and the current sensor 50 (any one of the U-phase current sensor 50u, the V-phase current sensor 50v, and the W-phase current sensor 50w) in which the abnormality has occurred may be specified. it can.

  Also, whether or not there is an abnormality in the current sensor 50, and the current sensor in which the abnormality has occurred, only by calculating the three-phase sum current twice (first timing t1 and second timing t2) during one cycle of the AC waveform. 50 identifications can be made. That is, when detecting a failure of the current sensor 50, it is possible to identify a current sensor in which a failure has occurred among the current sensors of each phase of the three-phase alternating current while reducing the processing time for detecting the failure.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

  For example, in the above-described embodiment, the timing when the U-phase current Iu becomes 0 [A] when the U-phase current Iu is switched from the negative value to the positive value is used as the first timing t1. When switching to a negative value, a timing of 0 [A] may be used. In this case, the three-phase sum current I1 at the first timing t1 is approximately 0 [A] (I1 = 0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. If it is sufficiently smaller (I2 <0 [A]), it can be specified that an abnormality has occurred in the U-phase current sensor 50u. The three-phase sum current I1 at the first timing t1 is sufficiently larger than 0 [A] (I1> 0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently larger (I2> 0 [A]), it can be determined that an abnormality has occurred in the V-phase current sensor 50v. The three-phase sum current I1 at the first timing t1 is sufficiently smaller than 0 [A] (I1 <0 [A]), and the three-phase sum current I2 at the second timing t2 is 0 [A]. ] Is sufficiently larger (I2> 0 [A]), it can be specified that an abnormality has occurred in the W-phase current sensor 50w.

  In the above-described embodiment, the timing at which the U-phase current Iu is 0 [A] is used as the first timing t1, but the V-phase current Iv or the W-phase current Iw is 0 [A]. Timing may be used. That is, among the three phases, the timing when the current of the predetermined phase becomes 0 [A] may be set as the first timing t1, and the timing shifted by 90 ° from the first timing t1 may be set as the second timing t2. . Thereby, similarly to the method described above, the current sensor 50 in which an abnormality has occurred can be identified based on the three-phase sum currents I1 and I2 at the first timing t1 and the second timing t2.

1 Failure detection device 10 Battery 20 Inverter 30 Motor (three-phase AC motor)
40 connection line 40u U-phase line 40v V-phase line 40w W-phase line 50 current sensor 50u U-phase current sensor 50v V-phase current sensor 50w W-phase current sensor 60 abnormality detection unit (sum current calculation means, identification means)
I1, I2 Three-phase sum current (sum current)
t1 first timing t2 second timing

Claims (1)

A current sensor that is arranged in each phase of the three-phase AC motor and detects a current of each phase;
Among the current sensors, a first timing at which a current detected by a current sensor arranged in a predetermined phase of the three-phase AC motor becomes 0, and a second phase shifted by 90 ° from the first timing. Sum current calculation means for calculating a sum current that is a sum of three-phase currents detected by the current sensor at the timing;
Specifying means for specifying a current sensor that outputs an abnormal value among the current sensors based on the sum current calculated at the first timing and the second timing by the sum current calculating means; Prepare
Fault detection device for current sensor.

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