JP2012225692A - Abnormal contact detecting device - Google Patents

Abstract

Provided is a contact abnormality detection device capable of obtaining a contact resistance of a connection portion arranged in a path to which an alternating current is supplied and detecting an abnormality in a contact state of the connection portion with higher accuracy.
A connecting portion is arranged on a path through which an alternating current is supplied to connect an inverter and a motor. The voltage measurement unit 2 measures the voltage generated at both ends of the connection unit 11. The current measurement unit 3 measures the current flowing through the connection unit 11. The calculating part 4 calculates | requires the contact resistance of the connection part 11 in time other than the time vicinity when voltage or an electric current becomes zero, and detects the contact abnormality in the connection part 11 based on the contact resistance.
[Selection] Figure 1

Description

  The present invention relates to a contact abnormality detection device that detects an abnormality in a contact state at a connection portion arranged in a path through which an alternating current is supplied.

  Patent Document 1 listed below discloses an abnormality detection device that detects an abnormality in the contact state of an electrical device. The abnormality detection device described in Patent Document 1 converts a current flowing in a power supply line to an electric device into a voltage, and compares it with a voltage when the electric device is operating normally, thereby causing a disconnection or a contact failure. Detects abnormal contact.

JP 2000-182163 A

  However, since it is difficult to detect a slight increase / decrease in contact resistance only by detecting only the current as in the abnormality detection device described in Patent Document 1, it is arranged in a path through which an alternating current is supplied. It is difficult to accurately detect an abnormality in the contact state at the connected portion. As a method for measuring a minute contact resistance, a four-terminal method is known. However, when the four-terminal method is applied to the measurement of AC voltage and AC current, when the current is small or when the contact resistance is calculated near the time when the voltage and current are zero, the contact at the connection due to the influence of noise. It may be difficult to accurately detect an abnormal state. For example, when the voltage is increased due to the influence of noise when the current is small, the obtained contact resistance is significantly increased from the original value, and as a result, it is difficult to accurately detect an abnormality in the contact state at the connection portion. Become.

  An object of the present invention is to provide a contact abnormality detection device capable of obtaining a contact resistance of a connection portion arranged in a path to which an alternating current is supplied and detecting a contact state abnormality in the connection portion with higher accuracy. That is.

  The present invention is a contact abnormality detection device for detecting an abnormality in a contact state at a connection portion connecting a motor and an inverter that supplies an alternating current to the motor, and measures voltage at both ends of the connection portion. A current measuring means for measuring a current flowing through the connecting portion, and information indicating a rotation angle of the motor rotated by an alternating current supplied from the inverter to obtain the voltage or the period of the current, and the voltage Based on the voltage measured by the measuring means and the current measured by the current measuring means, in a time zone other than the time zone determined based on the period around the time when the voltage or the current becomes zero By detecting the contact resistance of the connection portion and comparing the contact resistance with a predetermined resistance threshold, an abnormality in the contact state at the connection portion is detected. And calculating means, a contact abnormality detection apparatus characterized by having a.

  Further, in the contact abnormality detection device according to the present invention, the calculation means obtains the contact resistance of the connection part in a time zone in which the absolute value of the current measured by the current measurement means is equal to or greater than a predetermined current threshold. It is characterized by that.

  According to the present invention, the period of the voltage or current is obtained from the rotation angle of the motor, and the contact resistance of the connection part in the time zone other than the time zone determined based on the period around the time when the voltage or current becomes zero is obtained. By detecting a contact abnormality in the connection part based on the contact resistance, it is possible to detect the abnormality of the contact state in the connection part with less accuracy by being hardly affected by noise.

1 is a block diagram illustrating a contact abnormality detection device according to a first embodiment of the present invention. It is a graph which shows the time change of an electric current, a voltage, and contact resistance. It is a flowchart which shows the operation | movement by the contact abnormality detection apparatus which concerns on 1st Embodiment. It is a graph which shows the time change of an electric current and a voltage. It is a block diagram which shows the contact abnormality detection apparatus which concerns on 2nd Embodiment of this invention. It is a graph which shows the time change of an electric current, a voltage, and contact resistance. It is a graph which shows the time change of contact resistance. It is a graph which shows the time change of contact resistance. It is a block diagram which shows the contact abnormality detection apparatus which concerns on 3rd Embodiment of this invention. It is a graph which shows the time change of an electric current. It is a figure which shows the modification of the contact abnormality detection apparatus which concerns on 3rd Embodiment.

  With reference to FIGS. 1-4, the contact abnormality detection apparatus which concerns on 1st Embodiment of this invention is demonstrated. FIG. 1 is a block diagram showing a contact abnormality detection device according to the first embodiment of the present invention. FIG. 2 is a graph showing temporal changes in current, voltage, and contact resistance. FIG. 3 is a flowchart showing the operation of the contact abnormality detection device according to the first embodiment. FIG. 4 is a graph showing temporal changes in current and voltage.

  The contact abnormality detection device 1 according to the first embodiment detects an abnormality in a contact state at a connection portion that connects a power supply unit that supplies an alternating current and an electric load. As an example, as shown in FIG. 1, the contact abnormality detection device 1 detects an abnormality in the contact state at the connection portion 11 that connects the inverter 7 and the motor 8. The connection part 11 is a connector which connects the inverter 7 and the motor 8 as an example.

  Based on the control of the control unit 10, the inverter 7 converts DC power supplied from the battery 6, which is a DC power supply, into AC power and outputs the AC power to the motor 8. The motor 8 is connected to the inverter 7 via the connection portion 11. The alternating current output from the inverter 7 is supplied to the motor 8 via the connection portion 11. The motor 8 rotates based on the alternating current supplied from the inverter 7. The motor 8 corresponds to an example of an electric load, and the inverter 7 corresponds to an example of a power supply unit.

  The contact abnormality detection device 1 includes a voltage measurement unit 2, a current measurement unit 3, and a calculation unit 4. The contact abnormality detection device 1 measures the contact resistance of the connection part 11 and detects an abnormality of the contact state in the connection part 11 based on the contact resistance. The voltage measurement unit 2 measures the voltage V generated at both ends of the connection unit 11 and outputs voltage data indicating the voltage V to the calculation unit 4. The current measurement unit 3 measures the current I flowing through the connection unit 11 and outputs current data indicating the current I to the calculation unit 4. The rotation angle detection unit 9 detects the rotation angle θ of the motor 8 and outputs rotation angle data indicating the rotation angle θ to the calculation unit 4. The rotation angle detector 9 is a resolver provided in the motor 8, for example.

The calculation unit 4 obtains the contact resistance R (= V / I) of the connection unit 11 based on the voltage V measured by the voltage measurement unit 2 and the current I measured by the current measurement unit 3. FIG. 2 shows temporal changes in the current I, the voltage V, and the contact resistance R. In FIG. 2, the horizontal axis indicates time t, and the vertical axis indicates current I, voltage V, and contact resistance R, respectively. The calculation unit 4 obtains the period T of the waveform of the voltage V or current I based on the voltage V, current I, or rotation angle θ. As an example, the calculation unit 4 obtains the period T based on the rotation angle θ of the motor. The calculation unit 4 may obtain the period T of the waveform of the current I based on the current I measured by the current measurement unit 3, or may calculate the voltage V based on the voltage V measured by the voltage measurement unit 2. The period T of the waveform may be obtained. And the calculating part 4 calculates | requires the time when the electric current I or the voltage V becomes zero. For example, the calculation unit 4 obtains the time when the current I becomes zero based on the waveform of the current I. Alternatively, the calculation unit 4 may obtain the time when the voltage V becomes zero based on the waveform of the voltage V. Since the contact resistance R is a minute value (for example, several mΩ or less), the voltage V generated at both ends of the connection portion 11 when the current I flows through the connection portion 11 is a minute value. Accordingly, the time when the current I is zero can be obtained with higher accuracy than when the voltage V is used. Therefore, it is preferable to obtain the time when the current I is zero based on the waveform of the current I. Here, the time when the current I or the voltage V becomes zero is referred to as a “zero cross point”. Hereinafter, as an example, the time point when the current I becomes zero will be described as a zero cross point. The calculation unit 4 obtains the contact resistance R at a time other than the time near the time when the current I or the voltage V becomes zero (zero cross point). The calculation unit 4 obtains the contact resistance R in a time zone other than the time zone (± αT) with the zero cross point as the center. As the coefficient α, for example, an arbitrary value such as 0.1 is used. Information indicating the coefficient α may be set in advance in the calculation unit 4, or the operator may input the coefficient α using an input device (not shown). Referring to FIG. 2, when the time when the current I becomes zero (I = 0) is defined as time t ₀ (zero cross point), the calculation unit 4 calculates “t ₀ + αT ≦ time t ≦ t ₀ + ( The contact resistance R in the time zone D that satisfies the condition of “1 / 2−α) T” is obtained. That is, the calculation unit 4 obtains the contact resistance R in the time zone D without obtaining the contact resistance R in the time zone (2αT) centered on the time t ₀ . Note that, as shown in FIG. 2, the calculation unit 4 may obtain the contact resistance R when the absolute value of the current I becomes equal to or greater than a preset threshold value I _th1 .

Further, the calculation unit 4 detects an abnormality in the contact state at the connection unit 11 based on the contact resistance R, and outputs information indicating the detection result to the control unit 10. For example, the calculation unit 4 detects a contact abnormality when the contact resistance R is equal to or greater than a preset threshold value _Rth .

  The control unit 10 receives information indicating the detection result from the calculation unit 4 and performs control according to the detection result. When a contact abnormality is detected, the control unit 10 controls the battery 6 and the inverter 7, for example, to cut off the current supply to the motor 8 or to reduce the current supplied to the motor 8. To do.

Next, a series of operations by the contact abnormality detection device 1 will be described with reference to the flowchart of FIG. First, the current measurement unit 3 measures the current I flowing through the connection unit 11, the voltage measurement unit 2 measures the voltage V generated at both ends of the connection unit 11, and the rotation angle detection unit 9 determines the rotation angle θ of the motor 8. Detect (step S01). The computing unit 4 compares the absolute value of the current I with the threshold value I _th1 (step S02). When the absolute value of the current I is equal to or greater than the threshold value I _th1 (step S02, Yes), the process proceeds to step S03. In step S03, the calculation unit 4 obtains the period T of the waveform of the voltage V or the current I based on the voltage V, the current I, or the rotation angle θ. When the time t satisfies the condition of “t ₀ + αT ≦ time t ≦ t ₀ + (1 / 2−α) T” (step S04, Yes), the calculation unit 4 calculates the contact resistance R (step S04). S05). That is, the calculation unit 4 obtains the contact resistance R in the time zone D other than the time zone (2αT) centered on the time t ₀ (zero cross point) at which the current I becomes zero. Calculation unit 4 compares the contact resistance R and the threshold value R _th (step S06). If the contact resistance R becomes the threshold value R _th or more (step S06, Yes), the arithmetic unit 4 outputs information indicating the contact abnormality (detection result) to the control unit 10 (step S07). When the control unit 10 receives information indicating a contact abnormality from the calculation unit 4, for example, the control unit 10 performs control for cutting off the current supply to the motor 8 or reducing the current supplied to the motor 8. On the other hand, when the contact resistance R is less than the threshold value R _th (step S06, No), the process returns to step S01, and the processes from step S01 to step S06 described above are repeated.

  As described above, according to the contact abnormality detection device 1 according to the first embodiment, by obtaining the contact resistance R in the time zone D other than the vicinity of the zero cross point, it is difficult to be affected by noise, and the contact at the connection portion 11 is made. It becomes possible to detect an abnormal state with higher accuracy. That is, since the contact resistance R has a very small value (for example, several mΩ or less), the voltage V generated at both ends of the connecting portion 11 when the current I flows through the connecting portion 11 has a very small value. For this reason, the contact resistance R obtained in the time zone near the zero crossing point of the voltage V and the current I is particularly susceptible to noise and may be a value significantly different from the original value. For example, as shown in FIGS. 2 and 4, when the voltage V increases due to the influence of noise when the current I is sufficiently small, the contact resistance R becomes significantly larger than the original value. As a result, it is difficult to accurately detect an abnormality in the contact state at the connecting portion 11. As shown in FIG. 2, in the time zone (2αT), it can be seen that the contact resistance R is greatly increased from the original value due to the influence of noise. On the other hand, since it is difficult to be affected by noise in the time zone D, the contact resistance R does not increase significantly unless a contact abnormality occurs. Since the contact abnormality detection device 1 according to the first embodiment obtains the contact resistance R in the time zone D other than the vicinity of the zero cross point, the contact abnormality detection device 1 is less susceptible to noise, and the contact state abnormality in the connection portion 11 is further increased. It becomes possible to detect with high accuracy.

Note that the processing in step S02 may not be performed. That is, the calculation unit 4 may obtain the contact resistance R in the time zone D without comparing the current I with the threshold value _th1 .

The arithmetic unit 4, without using the period T, on the basis of the time t _0, may be obtained contact resistance R in a time zone other than the time zone before and after the time t _0. Note that the period T changes every moment by the operation of the motor 8. Accordingly, since the period T is obtained as described above, the time zone D is determined using the period T, and the contact resistance R is obtained, the process according to the actual operation of the motor 8 can be performed. preferable.

  Further, the calculation unit 4 may obtain the contact resistance R at all times and detect an abnormality in the contact state at the connection unit 11 based on the contact resistance R in the time zone D. That is, the contact abnormality detection device 1 according to the first embodiment may detect a contact state abnormality in the connection portion 11 by obtaining the contact resistance R in the time zone D, or obtain the contact resistance R in all times. The abnormality of the contact state in the connecting portion 11 may be detected based on the contact resistance R in the time zone D out of all the times.

  The calculation unit 4 is realized by, for example, cooperation between hardware resources and software. Specifically, the function of the calculation unit 4 is realized by reading a calculation program recorded on a recording medium into a main memory and executing it by a CPU (Central Processing Unit). Moreover, the control part 10 is implement | achieved by cooperation with a hardware resource and software, for example, for example, is an electronic control unit (ECU: Electronic Control Unit). Specifically, the function of the control unit 10 is realized by reading a control program recorded on a recording medium into the main memory and executing it by the CPU. The arithmetic program and the control program can be provided by being recorded on a computer-readable recording medium, or can be provided by communication as a data signal. However, the calculation unit 4 and the control unit 10 may be realized by hardware. Moreover, the calculating part 4 and the control part 10 may be physically implement | achieved by one apparatus, and may be implement | achieved by the some apparatus. In addition, the calculation unit 4 may be included in the control unit 10.

  Next, a contact abnormality detection device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram showing a contact abnormality detection device according to the second embodiment of the present invention. FIG. 6 is a graph showing temporal changes in current, voltage, and contact resistance. 7 and 8 are graphs showing changes in contact resistance with time.

  In the first embodiment described above, the rotation angle θ of the motor 8 is obtained and the time zone for detecting the contact abnormality of the connecting portion 11 is determined. However, in the second embodiment, threshold processing is performed without using the rotation angle θ. Go and detect contact anomalies.

  The contact abnormality detection device 20 according to the second embodiment includes a voltage measurement unit 2, a current measurement unit 3, and a calculation unit 21. Since the functions of the voltage measurement unit 2, the current measurement unit 3, and the control unit 10 are the same as those in the first embodiment, description thereof is omitted.

Based on the voltage V measured by the voltage measurement unit 2 and the current I measured by the current measurement unit 3, the calculation unit 21 obtains the contact resistance R (= V / I) of the connection unit 11. FIG. 6 shows temporal changes in the current I, the voltage V, and the contact resistance R. In FIG. 6, the horizontal axis indicates time t, and the vertical axis indicates current I, voltage V, and contact resistance R, respectively. As shown in FIG. 6, the calculation unit 21 calculates the contact resistance R when the absolute value of the current I becomes equal to or greater than a preset threshold value _th2 . Thus, the calculating part 21 calculates | requires the contact resistance R in the time slot | zone D other than the zero crossing point vicinity by performing a threshold value process. And the calculating part 21 detects the contact abnormality of the connection part 11 by comparing the contact resistance R and threshold value _Rth .

  As described above, according to the contact abnormality detection device 20 according to the second embodiment, the threshold resistance process is performed to obtain the contact resistance R in the time zone D other than the vicinity of the zero cross point, thereby making it less susceptible to noise. It is possible to detect an abnormality in the contact state at the connecting portion 11.

FIG. 7 shows a graph of contact resistance R that has not been subjected to threshold processing and a graph of contact resistance R that has undergone threshold processing. A graph 100 is a graph showing the contact resistance R that is not subjected to the threshold processing using the threshold _th2 . A graph 110 is a graph showing the contact resistance R subjected to the threshold processing using the threshold _th2 . When the threshold processing is not performed, as shown in the graph 100, the contact resistance R is influenced by noise and becomes a value significantly different from the original value. On the other hand, when the threshold processing is performed, as shown in the graph 110, it can be seen that the influence of noise is removed.

In addition, the calculating part 21 calculates _| requires the contact resistance R in all the time, and may detect the abnormality of the contact state in the connection part 11 based on the contact resistance R in the time slot _| zone D when the electric current I becomes more than threshold value _th2. .

  In addition, the calculation unit 21 may obtain a moving average value of the contact resistance R. For example, the computing unit 21 obtains the contact resistance R in all time zones and obtains a moving average value of the contact resistance R. In this case, the calculation unit 4 detects an abnormality in the contact state at the connection unit 11 based on the moving average value of the contact resistance R. FIG. 8 shows a graph of the contact resistance R not subjected to the moving average process and a graph of the contact resistance R subjected to the moving average process. The graph 200 is a graph showing the contact resistance R that has not been subjected to the moving average process. A graph 210 is a graph showing the contact resistance R subjected to the moving average process. When the moving average processing is not performed, as shown in the graph 200, the contact resistance R is affected by noise and becomes a value significantly different from the original value. On the other hand, when the moving average process is performed, as shown in the graph 210, it can be seen that the influence of noise is removed.

  Next, a contact abnormality detection device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a block diagram showing a contact abnormality detection device according to the third embodiment of the present invention. FIG. 10 is a graph showing changes in current over time. FIG. 11 is a diagram illustrating a modification of the contact abnormality detection device according to the third embodiment.

  In 3rd Embodiment, connection part 11u, 11v, 11w is arrange | positioned in the path | route through which the three-phase alternating current between the inverter 7 mounted in the vehicle and the motor 8 flows. The contact abnormality detection device 30 according to the third embodiment measures the contact resistance of the connection portions 11u, 11v, and 11w, and detects an abnormality in the contact state at the connection portions 11u, 11v, and 11w. Hereinafter, the connection units 11u, 11v, and 11w may be referred to as the connection unit 11 as a representative.

  A motor 8 shown in FIG. 9 is a three-phase AC synchronous motor, and includes a stator and a rotor each having three coils of U phase, V phase, and W phase. One end of each of the three coils of the U phase, V phase, and W phase is connected to each other at the midpoint, and the other end is connected to the inverter 7 via the connecting portion 11.

  The connecting portion 11 u is disposed between the U-phase coil of the motor 8 and the inverter 7. The connecting portion 11v is disposed between the V-phase coil of the motor 8 and the inverter 7. The connecting portion 11 w is disposed between the W-phase coil of the motor 8 and the inverter 7.

The contact abnormality detection device 30 includes voltage measurement units 2u, 2v, and 2w and a calculation unit 31. The voltage measurement unit 2u measures the voltage V _u generated at both ends of the connection unit 11u and outputs voltage data indicating the voltage V _u to the calculation unit 31. The voltage measurement unit 2v measures the voltage V _v generated at both ends of the connection unit 11v, and outputs voltage data indicating the voltage V _v to the calculation unit 31. The voltage measurement unit 2 _w measures the voltage V _w generated at both ends of the connection unit 11 _w and outputs voltage data indicating the voltage V _w to the calculation unit 31. Hereinafter, the voltage measuring units 2u, 2v, and 2w may be referred to as the voltage measuring unit 2 as a representative. Further, the voltages V _u , V _v , and V _w may be referred to as voltage V as a representative.

The control unit 10 controls the operation of the motor 8 by controlling the operation of the inverter 7 based on the driving operation command, the vehicle speed, and the like. For example, the control unit 10 controls the output torque of the motor 8 by controlling the current supplied from the inverter 7 to the motor 8. Here, the current supplied to the U-phase coil of the motor 8 is the current I _u , the current supplied to the V-phase coil is the current I _v, and the current supplied to the W-phase coil is the current I _w . To do. The control unit 10 outputs a current command value I ^* for supplying current to each phase to the inverter 7 to control the operation of the inverter 7. Control unit 10 outputs a current command value for each phase to inverter 7. Specifically, the control unit 10 supplies the inverter 7 with the current command value I _u ^* for the U-phase coil, the current command value I _v ^* for the V-phase coil, and the current command value I _w ^* for the W-phase coil. To control the operation of the inverter 7. In the three-phase alternating current, the currents I _u , I _v and I _w are 120 ° out of phase with each other. Hereinafter, the currents I _u , I _v , and I _w may be referred to as current I. In addition, the current command values I _u ^* , I _v ^* , and I _w ^* may be referred to as current command values I ^* . The control unit 10 outputs the current command value I ^* to the calculation unit 31.

The calculating part 31 calculates | requires the contact resistance R based on the electric current of the phase from which the value becomes maximum in each time among the electric currents of three phases, and the voltage of the phase. With reference to FIG. 10, the process by the calculating part 31 is demonstrated. In FIG. 10, the horizontal axis indicates time, and the vertical axis indicates current. The calculation unit 31 compares the current command values I _u ^* , I _v ^* , and I _w ^* at each time, and measures the current command value I ^{* of the} phase having the maximum value at each time and the voltage measurement unit 2. The contact resistance R (= V / I ^* ) is obtained based on the voltage V of the phase. For example, when the value of the U-phase current command value I _u ^* is larger than the V-phase current command value I _v ^* and the W-phase current command value I _w ^* , the calculation unit 31 may Based on the value I _u ^* and the U-phase voltage V _u measured by the voltage measurement unit 2 _u , the contact resistance R _u of the connection unit 11 _u is obtained. Similarly, when the value of the V-phase current command value I _v ^* is larger than the U-phase current command value I _u ^* and the W-phase current command value I _w ^* , the calculation unit 31 calculates the V-phase current command value I _v ^*. Based on the command value I _v ^* and the V-phase voltage V _v measured by the voltage measurement unit 2v, the contact resistance R _v of the connection unit 11v is obtained. Similarly, when the value of the W-phase current command value I _w ^* is larger than the U-phase current command value I _u ^* and the V-phase current command value I _v ^* , the calculation unit 31 calculates the W-phase current command value I _w ^*. a command value I _w ^*, based on the voltage V _w which is measured by the voltage measuring unit 2w, obtaining the contact resistance R _w of the connecting portion 11 w. As shown in FIG. 10, in the three-phase alternating current, the currents I _u , I _v , and I _w are 120 ° out of phase with each other, so that the contact resistance R of the same phase is obtained every 240 °. Hereinafter, the contact resistances R _u , R _v , and R _w may be referred to as contact resistances R as representatives.

Calculating unit 31, similarly to the first embodiment described above, by comparing the contact resistance R and the threshold value R _th, when the contact resistance R becomes the threshold value R _th or more, the connection portion 11u, 11v, the 11w Detect contact abnormality that occurs in either.

  As described above, according to the contact abnormality detection device 30 according to the third embodiment, the contact resistance R is determined based on the phase current having the maximum value at each time among the three-phase currents and the voltage of the phase. By obtaining, the contact resistance R in a time zone other than near the zero cross point can be obtained. As a result, it becomes difficult to be affected by noise, and it is possible to detect a contact state abnormality in the connecting portion 11 with higher accuracy.

  As a modification, the contact abnormality detection device 30 may individually detect contact abnormality of the connection units 11u, 11v, and 11w. For example, the first embodiment may be applied to the third embodiment, or the second embodiment may be applied to the third embodiment to individually detect contact abnormalities of the connecting portions 11u, 11v, and 11w.

A case where the first embodiment is applied to the third embodiment will be described. In this case, the rotation angle θ of the motor 8 is detected by the rotation angle detector 9 shown in FIG. The computing unit 31 obtains the period T of the waveform of the voltage V or the current I based on the voltage V, the current I, or the rotation angle θ. As an example, the calculation unit 31 obtains the period T of the waveform of the current I _u based on the current command value I _u ^* , obtains the period T of the waveform of the current I _v based on the current command value I _v ^*, and The period T of the waveform of the current I _w is obtained based on the value I _w ^* . The calculating unit 31 obtains a time (zero cross point) when the current command value I _u ^* is zero. The arithmetic unit 31 calculates the contact resistance R _u at times other than the vicinity of the current command value I _u ^* is zero time (zero-cross point). Like the first embodiment, the arithmetic unit 31, around a zero-crossing point, obtaining the contact resistance R _u in a time zone other than the time zone (± αT). As in the first embodiment, the calculation unit 31 may obtain the contact resistance R _u when the current command value I _u ^* is equal to or greater than the threshold value I _th1 . Based on the contact resistance R _u , the calculation unit 31 detects a contact state abnormality in the connection unit 11 _u and outputs information indicating the detection result to the control unit 10. As for the V phase and the W phase, similarly to the U phase, the calculation unit 31 calculates contact resistances R _v and R _w , respectively. Based on the contact resistances R _v and R _w , the calculation unit 31 detects the contact abnormality of each of the connection units 11 _v and 11 w and outputs information indicating the detection result of each phase to the control unit 10.

  As described above, the contact resistances of the connection portions 11u, 11v, and 11w can be individually detected by obtaining the contact resistances of the connection portions 11u, 11v, and 11w of the respective phases.

Similarly to the second embodiment, the calculation unit 31 may individually obtain the contact resistances of the connection units 11u, 11v, and 11w of each phase by performing threshold processing using the threshold value I _th2 . As a result, it is possible to individually detect contact abnormality in each of the connection portions 11u, 11v, and 11w.

Further, in the third embodiment, the connection portions 11u, 11v, 11w of the respective phases using the currents I _u , I _v , I _w actually measured without using the current command value I ^* as the current of each phase. The contact resistance may be obtained. In this case, as in the first embodiment and the second embodiment, the current measurement unit 3 is provided in the contact abnormality detection device 30, and the currents I _u and I _v flowing through the connection units 11 of each phase by the current measurement unit 3. , _Iw is measured.

  FIG. 11 shows an example in which the current measurement unit 3 is mounted on the contact abnormality detection device 30. The inverter 7 and the motor 8 are connected by fitting the connector 40 on the inverter side and the connector 50 on the motor side. The connector 40 on the inverter 7 side is provided with a voltage connector 41, and the connector 50 on the motor 8 side is provided with a voltage connector 51. When the connector 40 and the connector 50 are fitted, the voltage connector 41 and the voltage connector 51 are connected, and current is supplied from the inverter 7 to the motor 8 via the connector 40 and the connector 50.

Current measuring unit 3u measures the current I _u flowing through the coil of the U phase of the motor 8, a current measuring unit 3v measures the current I _v flowing through the V phase of the motor 8, a current measuring unit 3w, the motor 8 to measure the of W current flowing to the phase I _w. As described above, the voltage measurement unit 2 measures the voltages V _u , V _v , and V _w of each phase. Although not shown in FIG. 11, a contact abnormality in the connectors 40 and 50 can be detected by the arithmetic unit. Moreover, the control part 10 is ECU as an example as mentioned above.

  1, 20, 30 Contact abnormality detection device, 2, 2u, 2v, 2w Voltage measurement unit, 3, 3u, 3v, 3w Current measurement unit, 4, 21, 31 operation unit, 6 battery, 7 inverter, 8 motor, 9 Rotation angle detection unit, 10 control unit, 11, 11u, 11v, 11w connection unit, 40, 50 connector, 41, 51 voltage connector.

Claims (2)

A contact abnormality detection device that detects an abnormality in a contact state at a connection portion that connects a motor and an inverter that supplies an alternating current to the motor,
Voltage measuring means for measuring the voltage at both ends of the connecting portion;
Current measuring means for measuring a current flowing through the connecting portion;
Receiving information indicating the rotation angle of the motor rotated by the alternating current supplied from the inverter, the voltage or the period of the current is obtained, and the voltage measured by the voltage measuring means and the current measuring means are measured. Based on the current, the contact resistance of the connecting portion in a time zone other than the time zone determined based on the period around the time when the voltage or the current becomes zero is obtained, and the contact resistance and the predetermined resistance An arithmetic means for detecting a contact state abnormality in the connection portion by comparing the threshold value;
A contact abnormality detection device characterized by comprising: The contact abnormality detection device according to claim 1,
The calculation means obtains the contact resistance of the connection portion in a time zone in which the absolute value of the current measured by the current measurement means is equal to or greater than a predetermined current threshold.
The contact abnormality detection apparatus characterized by the above-mentioned.

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