Fault detection device, power conversion device, storage medium storing a fault detection program, and current detector

Abstract

The present application provides a kind of fault detection device, comprising: acquisition part, the acquisition part respectively from first magnetic sensor and second magnetic sensor obtains the first detection value of the magnetic flux density increase with the increase of first phase current and the second detection value of the magnetic flux density increase with the increase of first phase current, and respectively from third magnetic sensor and fourth magnetic sensor obtains the third detection value of the magnetic flux density increase with the increase of second phase current and the fourth detection value of the magnetic flux density increase with the increase of second phase current;Estimation part, the estimation part is used to calculate the first estimation value of second phase current using first detection value and second detection value, the second estimation value of second phase current using third detection value, and the third estimation value of second phase current using fourth detection value;And detection part, the detection part detects the failure of any magnetic sensor in third magnetic sensor and fourth magnetic sensor based on first estimation value, second estimation value and third estimation value.

Description

TECHNICAL FIELD

[0001] The present application relates to a failure detection device, a power conversion device, a storage medium storing a failure detection program, and a current detector. BACKGROUND

[0002] In Patent Literature 1, there is described "a control device of a three-phase alternating-current motor that performs rotational control of a three-phase alternating-current motor based on a motor control current that is based on measured values of current sensors respectively provided in each phase of the three-phase alternating-current motor, and that improves durability particularly against failure of the current sensors".

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Laid-Open No. 2000-116176

[0006] Patent Literature 2: Japanese Patent Laid-Open No. 2000-275279

[0007] Patent Literature 3: Japanese Patent Laid-Open No. 2006-064462

[0008] Patent Literature 4: Japanese Patent Laid-Open No. 2012-122897 SUMMARY

[0009] A failure detection device is provided in a first aspect of the present application. The failure detection device includes an acquisition section that acquires a first detection value whose value increases in accordance with an increase in magnetic flux density generated by a first phase current from a first magnetic sensor and a second detection value whose value decreases in accordance with an increase in magnetic flux density generated by the first phase current from a second magnetic sensor, and acquires a third detection value whose value increases in accordance with an increase in magnetic flux density generated by a second phase current from a third magnetic sensor and a fourth detection value whose value decreases in accordance with an increase in magnetic flux density generated by the second phase current from a fourth magnetic sensor. The failure detection device includes an estimation section that calculates a first estimated value of the second phase current estimated using the first detection value and the second detection value, a second estimated value of the second phase current estimated using the third detection value, and a third estimated value of the second phase current estimated using the fourth detection value. The failure detection device can include a detection section that detects a failure of any of the third magnetic sensor and the fourth magnetic sensor based on the first estimated value, the second estimated value, and the third estimated value.

[0010] The detection section can detect a failure of any of the third magnetic sensor and the fourth magnetic sensor based on a difference between the first estimated value and the second estimated value and a difference between the first estimated value and the third estimated value.

[0011] The detection unit can detect a failure of any of the third magnetic sensor and the fourth magnetic sensor when only one of a difference between the first estimated value and the second estimated value and a difference between the first estimated value and the third estimated value does not satisfy the predetermined criterion.

[0012] The detection unit can detect a failure of the third magnetic sensor when the difference between the first estimated value and the second estimated value does not satisfy the predetermined criterion.

[0013] The detection unit can detect a failure of the fourth magnetic sensor when the difference between the first estimated value and the third estimated value does not satisfy the predetermined criterion.

[0014] The estimation unit can further calculate a fourth estimated value of the first phase current estimated using the third detection value and the fourth detection value, a fifth estimated value of the first phase current estimated using the first detection value, and a sixth estimated value of the first phase current estimated using the second detection value. The detection unit can further detect a failure of any of the first magnetic sensor and the second magnetic sensor based on the fourth estimated value, the fifth estimated value, and the sixth estimated value.

[0015] The detection unit can detect a failure of any of the first magnetic sensor and the second magnetic sensor based on a difference between the fourth estimated value and the fifth estimated value and a difference between the fourth estimated value and the sixth estimated value.

[0016] The detection unit can detect a failure of any of the first magnetic sensor and the second magnetic sensor when only one of a difference between the fourth estimated value and the fifth estimated value and a difference between the fourth estimated value and the sixth estimated value does not satisfy the predetermined criterion.

[0017] The detection unit can detect a failure of the first magnetic sensor when the difference between the fourth estimated value and the fifth estimated value does not satisfy the predetermined criterion.

[0018] The detection unit can detect a failure of the second magnetic sensor when the difference between the fourth estimated value and the fifth estimated value does not satisfy the predetermined criterion.

[0019] A second aspect of the present application provides a power conversion device. The power conversion device can include the failure detection device. The power conversion device can include an inverter circuit including a semiconductor switching element. The power conversion device can include a drive circuit that drives the semiconductor switching element. The power conversion device can include a control circuit that controls the drive circuit.

[0020] When a failure of any of the magnetic sensors is detected, the above-described control circuit can perform feedback control based on an estimated value calculated using a detection value from a magnetic sensor for which no failure is detected.

[0021] An arithmetic circuit can be mounted on a substrate on which the above-described control circuit is mounted, and the arithmetic circuit obtains an arithmetic result corresponding to a total of the magnitudes of the magnetic flux densities detected by the first magnetic sensor and the second magnetic sensor by using an operation using the above-described first detection value and the above-described second detection value.

[0022] The above-described arithmetic circuit can also obtain an arithmetic result corresponding to a total of the magnitudes of the magnetic flux densities detected by the third magnetic sensor and the fourth magnetic sensor by using an operation using the above-described third detection value and the above-described fourth detection value.

[0023] In a third aspect of the present application, a storage medium storing a failure detection program is provided. The above-described failure detection program can be executed by a computer. The above-described failure detection program causes the computer to function as an acquisition section that acquires a first detection value whose value increases in accordance with an increase in a magnetic flux density generated by a first phase current from a first magnetic sensor and a second detection value whose value decreases in accordance with an increase in the magnetic flux density generated by the first phase current from a second magnetic sensor, and acquires a third detection value whose value increases in accordance with an increase in a magnetic flux density generated by a second phase current from a third magnetic sensor and a fourth detection value whose value decreases in accordance with an increase in the magnetic flux density generated by the second phase current from a fourth magnetic sensor. The above-described failure detection program causes the computer to function as an estimation section that calculates a first estimated value of the second phase current estimated using the first detection value and the second detection value, a second estimated value of the second phase current estimated using the third detection value, and a third estimated value of the second phase current estimated using the fourth detection value. The above-described failure detection program causes the computer to function as a detection section that detects a failure of any of the third magnetic sensor and the fourth magnetic sensor based on the first estimated value, the second estimated value, and the third estimated value.

[0024] In a fourth aspect of the application, a current detector is provided. The current detector can include a first magnetic sensor that detects a first detection value that increases as a magnetic flux density generated by a current flowing through a conductor increases. The current detector can include a second magnetic sensor that detects a second detection value that decreases as the magnetic flux density generated by the current flowing through the conductor increases. The current detector can include an arithmetic circuit that obtains an arithmetic result corresponding to a sum of magnitudes of the magnetic flux densities detected by the first magnetic sensor and the second magnetic sensor, respectively, by using an arithmetic operation of the first detection value and the second detection value. The current detector can include an output section that outputs the first detection value, the second detection value, and the arithmetic result.

[0025] In addition, the summary of the application does not list all the features of the application. Furthermore, sub-combinations of these groups of features can also constitute the application. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 In FIG. 1, along with the power supply 10 and the motor 20, an example of a power conversion device 100 including the failure detection device 200 according to the embodiment is shown.

[0027] Figure 2 In FIG. 2, the structure of the current detector 170 and the conductor 140 are shown using the first phase current detector 170u as an example.

[0028] Figure 3 An example of a flow in which the failure detection device 200 according to the embodiment detects a failure of a magnetic sensor is shown.

[0029] Figure 4 A relationship between a magnetic sensor in which the failure detection device 200 according to the embodiment detects a failure and a current value used for feedback control is shown.

[0030] Figure 5 In FIG. 3, along with the power supply 10 and the motor 20, a modified example of the power conversion device 100' including the failure detection device 200 according to the embodiment is shown.

[0031] Figure 6 An example of a computer 9900 in which the entirety or a part of the aspects of the application can be embodied is shown. DETAILED DESCRIPTION

[0032] Hereinafter, the application will be described through embodiments of the application, but the following embodiments do not limit the application of the claims. Furthermore, the combinations of features described in the embodiments are not all necessary for the technical means to solve the technical problems of the application.

[0033] Figure 1 Together with the power supply 10 and the motor 20, one example of a power conversion device 100 including the failure detection device 200 according to the present embodiment is shown. In the power conversion device 100, the motor 20 is controlled by converting the power supplied from the power supply 10 and supplying it to the motor 20.

[0034] The power supply 10 is a power supply that supplies power for controlling the motor 20. The power supply 10 can be, for example, a 200V three-phase alternating current power supply. The power supply 10 supplies power to the motor 20 via the power conversion device 100.

[0035] The motor 20 is a machine that converts electric energy (power) into mechanical energy (power). The motor 20 converts the power supplied from the power supply 10 and converted by the power conversion device 100 into power.

[0036] The power conversion device 100 converts the power obtained from the power supply 10 and supplied to the motor 20 by controlling the voltage, frequency, and the like, so that the motor 20 operates at a desired rotational speed or torque. The power conversion device 100 includes a rectifier circuit 110, a filter capacitor 120, an inverter circuit 130, a conductor 140, a control circuit 150, a drive circuit 160, a current detector 170, and a failure detection device 200.

[0037] The rectifier circuit 110 has six diodes bridged, and rectifies the alternating current output of the power supply 10.

[0038] The filter capacitor 120 is connected between the direct current output terminals of the rectifier circuit 110, and filters the output of the rectifier circuit 110.

[0039] The inverter circuit 130 is connected between the DC output terminals of the rectifier circuit 110, and converts and supplies the output of the rectifier circuit 110 to the motor 20. The inverter circuit 130 can be, for example, a three-phase voltage control type inverter circuit that converts the DC voltage output from the rectifier circuit 110 into a three-phase AC voltage, and supplies it to the motor 20 that is a three-phase AC motor. At this time, the speed of the motor 20 can be changed by changing the output frequency of the inverter circuit 130. Such an inverter circuit 130 is configured, for example, by connecting first to third arm circuits in parallel. Each arm circuit includes 2 semiconductor switching elements composed of transistors connected in series, and diodes connected in anti-parallel between the emitters / collectors of the transistors that constitute these semiconductor switching elements, respectively. In addition, in the present drawing, a case where the semiconductor switching elements are IGBTs (Insulated Gate Bipolar Transistors) is shown as one example. However, it is not limited thereto. As the semiconductor switching elements, various switching elements such as transistors and MOS-FETs can be used. The connection points of the 2 semiconductor switching elements in each of such arm circuits constitute output points U, V, and W, respectively.

[0040] The conductors 140 are wirings through which U-phase current, V-phase current, and W-phase current (also referred to as "motor current") flow, and include a U-phase conductor 140u, a V-phase conductor 140v, and a W-phase conductor 140w (collectively referred to as "conductors 140"). One end of each of such three-phase conductors 140 is connected to an output point of the inverter circuit 130, and the other end is connected to an end portion of an exciting winding of the motor 20 composed of a three-phase induction motor. That is, one end of the U-phase conductor 140u is connected to the output point U, and the other end is connected to an end portion of a U-phase exciting winding in the motor 20. One end of the V-phase conductor 140v is connected to the output point V, and the other end is connected to an end portion of a V-phase exciting winding in the motor 20. One end of the W-phase conductor 140w is connected to the output point W, and the other end is connected to an end portion of a W-phase exciting winding in the motor 20.

[0041] The control circuit 150 supplies an instruction signal required to control the motor 20 to the drive circuit 160 in accordance with various physical quantities (current, voltage, rotational speed, etc.) measured, and controls the drive circuit 160.

[0042] The drive circuit 160 drives the gates of the transistors that constitute the semiconductor switching elements, respectively. The drive circuit 160 drives the gates of the transistors that constitute the semiconductor switching elements included in the inverter circuit 130, for example, based on a control signal from the control circuit 150, as one example, a PWM (Pulse Width Modulation) instruction signal.

[0043] In such a power conversion device 100, feedback control based on motor current is performed by feeding back the motor current. Therefore, in the power conversion device 100, the current detector 170 is provided on the conductor 140 through which the motor current flows.

[0044] The current detector 170 includes a pair of magnetic sensors that respectively detect values corresponding to magnetic flux densities generated by the current flowing through the conductor 140. Details of the current detector 170 will be described later. In the present embodiment, such a current detector 170 can be provided on at least two of the three-phase conductors 140. In the present drawing, a case where the U phase of the three-phase alternating current is defined as the "first phase" and the W phase is defined as the "second phase" is shown as one example. That is, the first-phase current detector 170u and the second-phase current detector 170w (collectively referred to as "current detectors 170") are respectively provided on the U-phase conductor 140u and the W-phase conductor 140w. However, it is not limited thereto. The current detectors 170 can be provided on the U-phase conductor 140u and the V-phase conductor 140v, or on the V-phase conductor 140v and the W-phase conductor 140w. Furthermore, in the above description, a case where the current detectors 170 are provided on only two of the three-phase conductors 140 is shown as one example, but a case where the current detectors 170 are provided on all of the three-phase conductors is not excluded. That is, the current detectors 170 can be provided on all of the U-phase conductor 140u, the V-phase conductor 140v, and the W-phase conductor 140w.

[0045] The failure detection device 200 acquires detection values from the magnetic sensors included in the current detector 170 and estimates the phase current. Then, the failure detection device 200 detects a failure of any of the magnetic sensors included in the current detector 170 based on the estimated value of the phase current.

[0046] The failure detection device 200 includes an acquisition unit 210, an estimation unit 220, and a detection unit 230. In addition, these modules are functionally separated modules, respectively, and can not necessarily coincide with the actual device structure. That is, in the present drawing, although shown as one module, it can not necessarily be constituted by one device. Furthermore, in the present drawing, although shown as modules, respectively, it can not necessarily be constituted by one device at a time. Furthermore, in the present drawing, the failure detection device 200 is shown as a module different from the control circuit 150 and the drive circuit 160, but part or all of the failure detection device 200 can be integrated with at least one of the control circuit 150 and the drive circuit 160. As one example, the control circuit 150 and the failure detection device 200 can be integrated, and these functions can be implemented by one CPU.

[0047] The acquisition section 210 acquires, from the first magnetic sensor and the second magnetic sensor, a first detection value whose value increases in accordance with an increase in the magnetic flux density generated by the first phase current (U-phase current) and a second detection value whose value decreases in accordance with an increase in the magnetic flux density generated by the first phase current, respectively. Here, the first magnetic sensor is one of the magnetic sensors included in the first phase current detector 170u, and the second magnetic sensor is the other magnetic sensor included in the first phase current detector 170u. Likewise, the acquisition section 210 acquires, from the third magnetic sensor and the fourth magnetic sensor, a third detection value whose value increases in accordance with an increase in the magnetic flux density generated by the second phase current (W-phase current) and a fourth detection value whose value decreases in accordance with an increase in the magnetic flux density generated by the second phase current, respectively. Here, the third magnetic sensor is one of the magnetic sensors included in the second phase current detector 170w, and the fourth magnetic sensor is the other magnetic sensor included in the second phase current detector 170w.

[0048] At this time, when the current detector 170 includes the operation circuit described later, the acquisition section 210 can acquire the first operation result and the second operation result at the same time. The acquisition section 210 provides the acquired first detection value, second detection value, third detection value, and fourth detection value, and the first operation result and the second operation result to the estimation section 220.

[0049] The estimation section 220 calculates a first estimation value of the second phase current using the first detection value and the second detection value, a second estimation value of the second phase current using the third detection value, and a third estimation value of the second phase current using the fourth detection value, respectively. Likewise, the estimation section 220 also calculates a fourth estimation value of the first phase current using the third detection value and the fourth detection value, a fifth estimation value of the first phase current using the first detection value, and a sixth estimation value of the first phase current using the second detection value, respectively. The estimation section 220 provides the calculated first estimation value, second estimation value, third estimation value, fourth estimation value, fifth estimation value, and sixth estimation value to the detection section 230.

[0050] The detection section 230 detects a failure of any of the third magnetic sensor and the fourth magnetic sensor based on the first estimation value, the second estimation value, and the third estimation value. Likewise, the detection section 230 also detects a failure of any of the first magnetic sensor and the second magnetic sensor based on the fourth estimation value, the fifth estimation value, and the sixth estimation value. Then, the detection section 230 provides the estimation value corresponding to the detection result to the control circuit 150. In correspondence therewith, the control circuit 150 performs feedback control based on the estimation value provided from the detection section 230. This will be described later.

[0051] Figure 2The structure of the current detector 170 and the conductor 140 are illustrated with the first phase current detector 170u as an example. The first phase current detector 170u includes a first magnetic sensor 171, a second magnetic sensor 172, a first operation circuit 175u, and a first output section 176u.

[0052] The first magnetic sensor 171 and the second magnetic sensor 172 are configured to be arranged at positions opposite each other with the U-phase conductor 140u interposed therebetween, and the first magnetic sensor 171 and the second magnetic sensor 172 constitute a pair of magnetic sensors.

[0053] In the first magnetic sensor 171, the direction of the magnetic flux generated by the first phase current flowing through the U-phase conductor 140u and the detection direction (axis) of the sensor can be substantially the same. That is, the first magnetic sensor 171 can detect a first detection value iu detl whose value increases as the magnetic flux density generated by the first phase current flowing through the U-phase conductor 140u increases. More preferably, the first magnetic sensor 171 can detect a first detection value iu detl whose value increases in proportion to the magnetic flux density generated by the first phase current flowing through the U-phase conductor 140u. The first magnetic sensor 171 supplies the detected first detection value iu detl to the first operation circuit 175u and the first output section 176u.

[0054] In the second magnetic sensor 172, the direction of the magnetic flux generated by the first phase current flowing through the U-phase conductor 140u and the detection direction (axis) of the sensor can be substantially opposite. That is, the second magnetic sensor 172 can detect a second detection value iu det2 whose value decreases as the magnetic flux density generated by the first phase current flowing through the conductor 140u increases. More preferably, the second magnetic sensor 172 can detect a second detection value iu det2 whose value decreases in proportion to the magnetic flux density generated by the first phase current flowing through the conductor 140u. The second magnetic sensor 172 supplies the detected second detection value iu det2 to the first operation circuit 175u and the first output section 176u.

[0055] Thus, the first magnetic sensor 171 and the second magnetic sensor 172 are configured to be arranged at positions opposite each other with the conductor 140 through which the object current flows interposed therebetween, and one detection direction is substantially the same as the direction of the magnetic flux generated by the object current, and the other detection direction is substantially opposite to the direction of the magnetic flux generated by the object current. That is, the first magnetic sensor 171 and the second magnetic sensor 172 are configured to be able to detect the first detection value iu detl and the second detection value iu det2, respectively, which are substantially the same in magnitude and different in polarity.

[0056] The first operation circuit 175u inputs the first detection value iu detl and the second detection value iu det2. Then, the first operation circuit 175u obtains the first operation result iu det corresponding to the sum of the magnitudes of the magnetic flux densities detected by the first magnetic sensor 171 and the second magnetic sensor 172 by performing a calculation using the first detection value iu detl and the second detection value iu det2. The first operation circuit 175u can be any circuit capable of obtaining such an operation result. As one example, the first operation circuit 175u can be a differential circuit, and can obtain the first operation result iu det by performing a differential operation using the first detection value iu detl and the second detection value iu det2. At this time, the first operation circuit 175u inputs the first detection value iu detl to the non-inverting input terminal of the differential circuit, and inputs the second detection value iu det2 to the inverting input terminal, and can obtain the first operation result iu det corresponding to approximately twice the first-phase current by setting the gain to 1. The first operation circuit 175u supplies the obtained first operation result iu det to the first output section 176u. Note that in the above description, the first operation circuit 175u sets the gain to 1 and obtains the first operation result iu det corresponding to approximately twice the first-phase current, but is not limited thereto. The first operation circuit 175u can obtain the first operation result iu det corresponding to approximately the same multiple of the first-phase current by adjusting the gain. Therefore, the above term "the first operation result iu det corresponding to the sum of the magnitudes of the magnetic flux densities detected by the first magnetic sensor 171 and the second magnetic sensor 172" is defined to include not only the operation result corresponding to the sum of the magnitudes of the magnetic flux densities detected by the first magnetic sensor 171 and the second magnetic sensor 172, but also the operation result after gain adjustment. Note that "sum" in the present specification means to calculate two or more values together, and the calculation can include addition, subtraction, multiplication, division, and other calculations.

[0057] The first output section 176u outputs the first detection value iu detl, the second detection value iu det2, and the first operation result iu det.

[0058] Further, although not described here, the second phase current detector 170w can also be configured in the same structure as the first phase current detector 170u. That is, the second phase current detector 170w can include a third magnetic sensor 173, a fourth magnetic sensor 174, a second arithmetic circuit 175w, and a second output section 176w. Here, the "first arithmetic circuit 175u" and the "second arithmetic circuit 175w" are collectively referred to as "arithmetic circuit 175". Further, the "first output section 176u" and the "second output section 176w" are collectively referred to as "output section 176". In this case, the third magnetic sensor 173 can detect a third detection value iwdetl whose value increases as the magnetic flux density generated by the second phase current flowing through the W phase conductor 140w increases. Similarly, the fourth magnetic sensor 174 can detect a fourth detection value iwdet2 whose value decreases as the magnetic flux density generated by the second phase current flowing through the W phase conductor 140w increases. Further, the second arithmetic circuit 175w performs calculation using the third detection value iwdetl and the fourth detection value iwdet2 to obtain a second arithmetic result iwdet corresponding to the total of the magnitudes of the magnetic flux densities detected by the third magnetic sensor 173 and the fourth magnetic sensor 174, respectively. Then, the second output section 176w can output the third detection value iwdetl, the fourth detection value iwdet2, and the second arithmetic result iwdet.

[0059] The failure detection device 200 according to the present embodiment acquires detection values from the current detectors 170 provided on the at least two phase conductors 140 and estimates phase currents, as described above. Then, the failure detection device 200 according to the present embodiment detects a failure of any magnetic sensor included in the current detectors 170 based on the estimated values of the phase currents. For this, a flow will be used for detailed description.

[0060] Figure 3 One example of a flow in which the failure detection device 200 according to the present embodiment detects a failure of a magnetic sensor is shown.

[0061] In step S310, the failure detection device 200 acquires the first to fourth detection values and the first to second operation results. For example, the acquisition section 210 acquires the first detection value iu detl and the second detection value iu det2 from the first magnetic sensor 171 and the second magnetic sensor 172 included in the first phase current detector 170u via the first output section 176u, respectively, the first detection value iu detl increasing as the magnetic flux density generated by the first phase current increases, the second detection value iu det2 decreasing as the magnetic flux density generated by the first phase current increases. Further, the acquisition section 210 acquires the first operation result iu det from the first operation circuit 175u included in the first phase current detector 170u via the first output section 176u.

[0062] Likewise, the acquisition section 210 acquires the third detection value iw detl and the fourth detection value iw det2 from the third magnetic sensor 173 and the fourth magnetic sensor 174 included in the second phase current detector 170w via the second output section 176w, respectively, the third detection value iw detl increasing as the magnetic flux density generated by the second phase current increases, the fourth detection value iw det2 decreasing as the magnetic flux density generated by the second phase current increases. Further, the acquisition section 210 acquires the second operation result iw det from the second operation circuit 175w included in the second phase current detector 170w via the second output section 176w.

[0063] In addition, the "acquisition" here is not limited to the case of acquiring directly from the current detector 170. The acquisition section 210 can acquire these detection values or operation results via other devices or networks and the like, for example, can acquire via various storage devices, and can acquire via user input, as well.

[0064] Further, in the above description, although the case where the acquisition section 210 acquires the first operation result iu det and the second operation result iw det from the first phase current detector 170u and the second phase current detector 170w, respectively, is shown as one example, it is not limited thereto. When at least one of the first operation result iu det and the second operation result iw det is not provided from the first phase current detector 170u and the second phase current detector 170w (for example, the case where the current detector 170 does not include the operation circuit 175, and the like), the acquisition section 210 can acquire at least one of the first operation result iu det and the second operation result iw det by performing the same operation as the operation circuit 175.

[0065] The acquisition unit 210 supplies the acquired first detection value iu detl, second detection value iu det2, third detection value iw detl, and fourth detection value iw det2, and first operation result iu det and second operation result iw det to the estimation unit 220.

[0066] In step S320, the fault detection device 200 calculates the first, second, and third estimation values of the second phase current. For example, the estimation unit 220 calculates the first estimation value iwest(U) of the second phase current using the first detection value iu detl and the second detection value iu det2, the second estimation value iwest(Wl) of the second phase current using the third detection value iw detl, and the third estimation value iwest(W2) of the second phase current using the fourth detection value iw det2. Details will be described using mathematical expressions.

[0067] Each current detector 170 detects not only the magnetic flux generated by the self phase current but also the magnetic flux generated by the other phase current. Here, the magnetic flux coupling parameter between the U phase and the V phase is Kuv, the magnetic flux coupling parameter between the V phase and the W phase is Kvw, and the magnetic flux coupling parameter between the W phase and the U phase is Kwu. Further, the U phase current is denoted by iu, the V phase current is denoted by iv, and the W phase current is denoted by iw. Here, assuming that iu + iv + iw = 0, the first detection value iu detl detected by the first magnetic sensor 171 included in the first phase current detector 170u is shown by the following expression.

[0068] [Expression 1]

[0069] iu detl = iu + Kuv iv + Kwu iw = iu + Kuv (-iu - iw) + K Kwu iw

[0070] = (1 - Kuv) iu + (Kwu - Kuv) iw

[0071] Further, the second detection value iu det2 detected by the second magnetic sensor 172 included in the first phase current detector 170u is shown by the following expression.

[0072] [Expression 2]

[0073] iu det2 = -iu + Kuv iv + Kwu iw = -iu + Kuv (-iu - iw) + Kwu iw

[0074] = (-1 - Kuv) iu + (Kwu - Kuv) iw

[0075] Therefore, the sum of the first detection value iu_det1 and the second detection value iu_det2 is shown by the following formula.

[0076] [Mathematical Expression 3]

[0077] iu_det1+iu_det2=-2·Kuv·iu+2·(Kwu-Kuv)·iw

[0078] Furthermore, the difference between the first detection value iu_det1 and the second detection value iu_det2 is shown by the following formula.

[0079] [Mathematical Expression 4]

[0080] iu_det1-iu_det2=2·iu

[0081] Here, (Mathematical Expression 4) is transformed into the following expression.

[0082]

Number 5

[0083]

[0084] Therefore, by substituting (Mathematical Formula 5) into (Mathematical Formula 3), as shown in the following formula, the estimation unit 220 can calculate the first estimated value iw_est(U) of the second phase current using the first detection value iu_det1 and the second detection value iu_det2 obtained from the first magnetic sensor 171 and the second magnetic sensor 172. That is, the estimation unit 220 can estimate the second phase current without using the third detection value iw_det1 and the fourth detection value iw_det2 obtained from the third magnetic sensor 173 and the fourth magnetic sensor 174.

[0085] [Mathematical Expression 6]

[0086]

[0087] Furthermore, the third detection value iw_det1 detected by the third magnetic sensor 173 contained in the second phase current detector 170w is shown by the following formula.

[0088] [Mathematical Expression 7]

[0089] iw_det1=Kwu·iu+Kvw·iv+iw=Kwu·iu+Kvw·(-iu-iw)+iw

[0090] =(Kwu-Kvw)·iu+(1-Kvw)·iw

[0091] Furthermore, the fourth detection value iw_det2 detected by the fourth magnetic sensor 174 contained in the second phase current detector 170w is shown by the following formula.

[0092] [Math. 8]

[0093] iw det2 = Kwu · iu + Kvw · iv - iw = Kwu · iu + Kvw · (-iu - iw) - iw

[0094] = (Kwu - Kvw) · iu + (-1 - Kvw) · iw

[0095] Here, by arranging iw in (Math. 7) as iw est(W1) as shown in the following equation, the estimation unit 220 can calculate the second estimated value iw est(W1) estimated for the second phase current using the third detection value iw det1 obtained from the third magnetic sensor 173. That is, the estimation unit 220 can estimate the second phase current without using the fourth detection value iw det2 acquired from the fourth magnetic sensor 174.

[0096] [Math. 9]

[0097]

[0098]

[0099] Similarly, by arranging iw in (Math. 8) as iw est(W2) as shown in the following equation, the estimation unit 220 can calculate the third estimated value iw est(W2) estimated for the second phase current using the fourth detection value iw det2 obtained from the fourth magnetic sensor 174. That is, the estimation unit 220 can estimate the second phase current without using the third detection value iw det1 acquired from the third magnetic sensor 173.

[0100] [Math. 10]

[0101]

[0102]

[0103] For example, the estimation unit 220 calculates the first estimated value iw est(U) estimated for the second phase current using the first detection value iu det1 and the second detection value iu det2, the second estimated value iw est(W1) estimated for the second phase current using the third detection value iw det1, and the third estimated value iw est(W2) estimated for the second phase current using the fourth detection value iw det2, respectively. The estimation unit 220 supplies the calculated first estimated value iw est(U), the second estimated value iw est(W1), and the third estimated value iw est(W2) to the detection unit 230.

[0104] In step S330, the failure detection device 200 determines whether only one of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) and the difference between the first estimated value iw_est(U) and the third estimated value iw_est(W2) does not satisfy the reference. For example, the detection section 230 determines whether the absolute value of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) exceeds a predetermined threshold value, and whether the absolute value of the difference between the first estimated value iw_est(U) and the third estimated value iw_est(W2) exceeds a predetermined threshold value. Then, when only one exceeds the threshold value, the detection section 230 determines that only the arbitrary one does not satisfy the reference (Yes). In this case, if either of the third detection value iw_detl used when the second estimated value iw_est(Wl) is calculated and the fourth detection value iw_det2 used when the third estimated value iw_est(W2) is calculated is an abnormal value, a failure of the arbitrary magnetic sensor of the third magnetic sensor 173 and the fourth magnetic sensor 174 that detected the third detection value iw_detl and the fourth detection value iw_det2 is detected. Thus, in a case where only the arbitrary one of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) and the difference between the first estimated value iw_est(U) and the third estimated value iw_est(W2) does not satisfy the predetermined reference, the detection section 230 detects a failure of the arbitrary magnetic sensor of the third magnetic sensor 173 and the fourth magnetic sensor 174. Then, the failure detection device 200 advances the process to step S335.

[0105] In step S335, the failure detection device 200 determines whether the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) does not satisfy the reference. For example, the detection section 230 determines whether the absolute value of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) exceeds a predetermined threshold value. Then, when the threshold value is exceeded, the detection section 230 determines that the difference between the first estimated value iw_est(U) and the second estimated value iw_est(Wl) does not satisfy the reference (Yes). Then, the failure detection device 200 advances the process to step S340.

[0106] In step S340, the failure detection device 200 detects a failure of the third magnetic sensor 173. For example, when the difference between the first estimated value iwest(U) and the third estimated value iwest(W2) satisfies the reference, and the difference between the first estimated value iwest(U) and the second estimated value iwest(Wl) does not satisfy the reference, it is estimated that the detection unit 230 regards the third detection value iwdetl used when calculating the second estimated value iwest(Wl) as an abnormal value, and detects a failure of the third magnetic sensor 173 that detected the third detection value iwdetl. That is, in a case where the difference between the first estimated value iwest(U) and the third estimated value iwest(W2) satisfies the reference, it is highly likely that the first detection value iudetl and the second detection value iudet2 used when calculating the first estimated value iwest(U) and the fourth detection value iwdet2 used when calculating the third estimated value iwest(W2) are normal values. In this case, only the case where the difference between the first estimated value iwest(U) and the second estimated value iwest(Wl) does not satisfy the reference means that it is highly likely that the third detection value iwdetl is an abnormal value. Therefore, in this case, the detection unit 230 detects a failure of the third magnetic sensor 173 that detected this third detection value iwdetl. Therefore, when the difference between the first estimated value iwest(U) and the second estimated value iwest(Wl) does not satisfy the predetermined reference, the detection unit 230 detects a failure of the third magnetic sensor 173.

[0107] On the other hand, in step S335, when the absolute value of the difference between the first estimated value iwest(U) and the second estimated value iwest(Wl) is equal to or less than a predetermined threshold value, the failure detection device 200 advances the process to step S350.

[0108] In step S350, the failure detection device 200 detects a failure of the fourth magnetic sensor 174. For example, when the difference between the first estimated value iwest(U) and the second estimated value iwest(Wl) satisfies the reference, and the difference between the first estimated value iwest(U) and the third estimated value iwest(W2) does not satisfy the reference, it is estimated that the detection unit 230 regards the fourth detection value iwdet2 used when calculating the third estimated value iwest(W2) as an abnormal value, and detects a failure of the fourth magnetic sensor 174 that detected this fourth detection value iwdet2. Therefore, when the difference between the first estimated value iwest(U) and the third estimated value iwest(W2) does not satisfy the predetermined reference, the detection unit 230 detects a failure of the fourth magnetic sensor 174.

[0109] Thus, the detection section 230 detects a failure of any of the third magnetic sensor 173 and the fourth magnetic sensor 174 on the basis of the first estimated value iw_est(U), the second estimated value iw_est(W1), and the third estimated value iw_est(W2). In more detail, the detection section 230 can detect a failure of any of the third magnetic sensor 173 and the fourth magnetic sensor 174 on the basis of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(W1) and the difference between the first estimated value iw_est(U) and the third estimated value iw_est(W2).

[0110] On the other hand, in step S330, when both the absolute value of the difference between the first estimated value iw_est(U) and the second estimated value iw_est(W1) and the absolute value of the difference between the first estimated value iw_est(U) and the third estimated value iw_est(W2) are below a predetermined threshold value, or both exceed the predetermined threshold value, the failure detection device 200 advances the process to step S360.

[0111] In step S360, the failure detection device 200 calculates a fourth estimated value, a fifth estimated value, and a sixth estimated value of the first phase current. For example, the estimation section 220 calculates the fourth estimated value iu_est(W) of the first phase current using the third detection value iw_det1 and the fourth detection value iw_det2, the fifth estimated value iu_est(U1) of the first phase current using the first detection value iu_det1, and the sixth estimated value iu_est(U2) of the first phase current using the second detection value iu_det2.

[0112] The third detection value iw_det1 detected by the third magnetic sensor 173 included in the second phase current detector 170u is shown by the following equation.

[0113] [Equation 11]

[0114] iw det1 = Kwu · iu + Kvw · iv + iw = Kwu · iu + Kvw · (-iu - iw) + iw

[0115] = (Kwu - Kvw) · iu + (1 - Kvw) · iw

[0116] Further, the fourth detection value iw_det2 detected by the fourth magnetic sensor 174 included in the second phase current detector 170w is shown by the following equation.

[0117] [Equation 12]

[0118] iw det2 = Kwu · iu + Kvw · iv - iw = Kwu · iu + Kvw · (-iu - iw) - iw

[0119] = (Kwu - Kvw) · iu + (-1 - Kvw) · iw

[0120] Therefore, the sum of the third detection value iwdetl and the fourth detection value iwdet2 is shown by the following equation.

[0121] [Math. 13]

[0122] iwdetl + iwdet2 = 2 · (Kwu - Kvw) · iu - 2 · Kvw · iw

[0123] Further, the difference between the third detection value iwdetl and the fourth detection value iwdet2 is shown by the following equation.

[0124] [Math. 14]

[0125] iwdetl - iwdet2 = 2 · iw

[0126] Here, (Math. 14) is transformed into the following equation.

[0127] [Math. 15]

[0128]

[0129] Then, by substituting (Math. 15) into (Math. 13), the estimation unit 220 can calculate the fourth estimated value iu_est(W) of the first phase current using the third detection value iwdetl and the fourth detection value iwdet2 acquired from the third magnetic sensor 173 and the fourth magnetic sensor 174, as shown in the following equation. That is, the estimation unit 220 can estimate the first phase current without using the first detection value iudetl and the second detection value iudet2 acquired from the first magnetic sensor 171 and the second magnetic sensor 172.

[0130] [Math. 16]

[0131]

[0132] Further, the first detection value iudetl detected by the first magnetic sensor 171 included in the first phase current detector 170u is shown by the following equation.

[0133] [Math. 17]

[0134] iudetl = iu + Kuv · iv + Kwu · iw = iu + Kuv · (-iu - iw) + Kwu · iw

[0135] = (1 - Kuv) · iu + (Kwu - Kuv) · iw

[0136] In addition, the second detection value iu_det2 detected by the second magnetic sensor 172 included in the first phase current detector 170u is shown by the following expression.

[0137] [Equation 18]

[0138] iu_det2 = -iu + Kuv iv + Kwu iw = -iu + Kuv (-iu - iw) + Kwu iw

[0139] = (-1 - Kuv) iu + (Kwu - Kuv) iw

[0140] Here, by arranging iu in (Equation 17) as iu_est(U1) as shown in the following expression, the estimation unit 220 can calculate the fifth estimated value iu_est(U1) that estimates the first phase current using the first detection value iu_det1 obtained from the first magnetic sensor 171. That is, the estimation unit 220 can estimate the first phase current without using the second detection value iu_det2 acquired from the second magnetic sensor 172.

[0141] [Equation 19]

[0142]

[0143]

[0144] Similarly, by arranging iu in (Equation 18) as iu_est(U2) as shown in the following expression, the estimation unit 220 can calculate the sixth estimated value iu_est(U2) that estimates the first phase current using the second detection value iu_det2 obtained from the second magnetic sensor 172. That is, the estimation unit 220 can estimate the first phase current without using the first detection value iu_det1 acquired from the first magnetic sensor 171.

[0145] [Equation 20]

[0146]

[0147]

[0148] Thus, the estimation section 220 calculates the fourth estimated value iu_est(W) of the first phase current using the third detection value iw_detl and the fourth detection value iw_det2, the fifth estimated value iu_est(Ul) of the first phase current using the first detection value iu_detl, and the sixth estimated value iu_est(U2) of the first phase current using the second detection value iu_det2, respectively. The estimation section 220 supplies the calculated fourth estimated value iu_est(W), the fifth estimated value iu_est(Ul), and the sixth estimated value iu_est(U2) to the detection section 230.

[0149] In step S370, the fault detection device 200 determines whether only one of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(Ul) and the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) does not satisfy the criterion. For example, the detection section 230 determines whether the absolute value of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(Ul) exceeds a predetermined threshold value, and whether the absolute value of the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) exceeds a predetermined threshold value. Then, when only one of them exceeds the threshold value, the detection section 230 determines that only one of them does not satisfy the criterion (Yes). In this case, if it is estimated that either the first detection value iu_detl used when the fifth estimated value iu_est(Ul) is calculated or the second detection value iu_det2 used when the sixth estimated value iu_est(U2) is calculated is an abnormal value, the fault of the arbitrary one of the first magnetic sensor 171 and the second magnetic sensor 172 that detected the first detection value iu_detl and the second detection value iu_det2 is detected. Thus, in the case where only one of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(Ul) and the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) does not satisfy the predetermined criterion, the detection section 230 detects the fault of the arbitrary one of the first magnetic sensor 171 and the second magnetic sensor 172. Then, the fault detection device 200 advances the process to step S375.

[0150] In step S375, the failure detection device 200 determines whether or not the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) does not satisfy the criterion. For example, the detection section 230 determines whether or not the absolute value of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) exceeds a predetermined threshold value. Then, when the threshold value is exceeded, the detection section 230 determines that the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) does not satisfy the criterion (Yes). Then, the failure detection device 200 advances the process to step S380.

[0151] In step S380, the failure detection device 200 detects a failure of the first magnetic sensor 171. For example, when the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) satisfies the criterion and the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) does not satisfy the criterion, the detection section 230 estimates that the first detection value iu_det1 used when the fifth estimated value iu_est(U1) is calculated is an abnormal value, and detects a failure of the first magnetic sensor 171 that detected this first detection value iu_det1. That is, in the case where the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) satisfies the criterion, the third detection value iw_det1 and the fourth detection value iw_det2 used when the fourth estimated value iu_est(W) is calculated, and the second detection value iu_det2 used when the sixth estimated value iu_est(U2) is calculated are normal values with a high probability. In this case, only the case where the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) does not satisfy the criterion means that the first detection value iu_det1 is an abnormal value with a high probability. Therefore, in this case, the detection section 230 detects a failure of the first magnetic sensor 171 that detected this first detection value iu_det1. Thus, when the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) does not satisfy the predetermined criterion, the detection section 230 detects a failure of the first magnetic sensor 171.

[0152] On the other hand, in step S375, when the absolute value of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) is equal to or less than a predetermined threshold value, the failure detection device 200 advances the process to step S390.

[0153] In step S390, the failure detection device 200 detects a failure of the second magnetic sensor 172. For example, when the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1) satisfies the reference, and the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) does not satisfy the reference, the detection unit 230 estimates that the second detection value iu_det2 used when the sixth estimated value iu_est(U2) is calculated is an abnormal value, and detects a failure of the second magnetic sensor 172 that detected this second detection value iu_det2. Thus, when the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) does not satisfy the predetermined reference, the detection unit 230 detects a failure of the second magnetic sensor 172.

[0154] On the other hand, in step S390, when both the absolute value of the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1), and the absolute value of the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2) are below a predetermined threshold, or when both exceed the predetermined threshold, the failure detection device 200 ends the flow without detecting a failure of any magnetic sensor.

[0155] Thus, the detection unit 230 detects a failure of any of the first magnetic sensor 171 and the second magnetic sensor 172 based on the fourth estimated value iu_est(W), the fifth estimated value iu_est(U1), and the sixth estimated value iu_est(U2). In more detail, the detection unit 230 can detect a failure of any of the first magnetic sensor 171 and the second magnetic sensor 172 based on the difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1), and the difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2).

[0156] The failure detection device 200 can determine a failure of any of the first magnetic sensor 171, the second magnetic sensor 172, the third magnetic sensor 173, and the fourth magnetic sensor 174, for example, by such a flow. Therefore, the power conversion device 100 can perform feedback control based on the detection result of such a failure detection device 200.

[0157] Figure 4The relationship between the magnetic sensor in which a failure is detected by the failure detection device 200 according to the present embodiment and the current value used for feedback control is shown. As shown in the present drawing, if the magnetic sensor in which a failure is detected is "none", that is, no failure is detected for any magnetic sensor, the iu shown in (mathematical expression 5) can be used as the U-phase current used for feedback control. That is, the value obtained by dividing the difference between the first detection value iu_det1 and the second detection value iu_det2 by 2, in other words, the value obtained by dividing the first operation result iu_det by 2 can be used. Similarly, the iw shown in (mathematical expression 15) can be used as the W-phase current used for feedback control. That is, the value obtained by dividing the difference between the third detection value iw_det1 and the fourth detection value iw_det2 by 2, in other words, the value obtained by dividing the second operation result iw_det by 2 can be used.

[0158] When the magnetic sensor in which a failure is detected is the "first magnetic sensor 171", it is not desirable to use the value calculated using the first detection value iu_det1 detected by the first magnetic sensor 171 for feedback control. Here, in this case, the sixth estimated value iu_est(U2) shown in (mathematical expression 20) can be used as the U-phase current used for feedback control. Similarly, when the magnetic sensor in which a failure is detected is the "second magnetic sensor 172", it is not desirable to use the value calculated using the second detection value iu_det2 detected by the second magnetic sensor 172 for feedback control. Therefore, in this case, the fifth estimated value iu_est(U1) shown in (mathematical expression 19) can be used as the U-phase current used for feedback control.

[0159] Further, when the magnetic sensor in which a failure is detected is the "third magnetic sensor 173", it is not desirable to use the value calculated using the third detection value iw_det1 detected by the third magnetic sensor 173 for feedback control. Therefore, in this case, the third estimated value iw_est(W2) shown in (mathematical expression 10) can be used as the W-phase current used for feedback control. Similarly, when the magnetic sensor in which a failure is detected is the "fourth magnetic sensor 174", it is not desirable to use the value calculated using the fourth detection value iw_det2 detected by the fourth magnetic sensor 174 for feedback control. Thus, in this case, the second estimated value iw_est(W1) shown in (mathematical expression 9) can be used as the W-phase current used for feedback control.

[0160] Therefore, when the detection unit 230 detects a failure of any magnetic sensor, the estimated value corresponding to the detection result can be supplied to the control circuit 150. In correspondence therewith, the control circuit 150 performs feedback control based on the estimated value supplied from the detection unit 230. Thus, when a failure of any magnetic sensor is detected, the control circuit 150 can perform feedback control based on the estimated value calculated using the detection value from the magnetic sensor in which no failure is detected.

[0161] Figure 5 In the middle of the power supply 10 and the motor 20, a modification example of the power conversion device 100' including the failure detection device 200 according to the present embodiment is shown. In Figure 5 In the middle of the power supply 10 and the motor 20, a modification example of the power conversion device 100' including the failure detection device 200 according to the present embodiment is shown. In Figure 1 The same reference numerals are attached to members having the same function and structure as those of the above-described embodiment, and the description is omitted except for the following different points. In the above-described embodiment, the case where the first phase current detector 170u and the second phase current detector 170w include the first operation circuit 175u and the second operation circuit 175w, respectively, is shown as one example. However, in the present modification example, the first phase current detector 170u' and the second phase current detector 170w' do not include the first operation circuit 175u and the second operation circuit 175w, and the power conversion device 100' is provided with the operation circuit 175'. In this case, the operation circuit 175' can perform the functions possessed by the first operation circuit 175u and the second operation circuit 175w.

[0162] At this time, for example, the control circuit 150 and the failure detection device 200 are integrated, and their functions are realized by one CPU, in which case, the operation circuit 175' can also be mounted on a substrate on which the CPU is mounted. Thus, the operation circuit 175' can also be mounted on a substrate on which the control circuit 150 is mounted, the operation circuit 175' obtaining, by operation using the first detection value iu detl and the second detection value iu det2, an operation result corresponding to the sum of the magnetic flux density magnitudes detected by the first magnetic sensor 171 and the second magnetic sensor 172, respectively, and obtaining, by operation using the third detection value iw detl and the fourth detection value iw det2, an operation result corresponding to the sum of the magnetic flux density magnitudes detected by the third magnetic sensor 173 and the fourth magnetic sensor 174, respectively.

[0163] In addition, in the above description, a case where the control circuit 150 and the failure detection device 200 are integrated and their functions are implemented by one CPU is described as one example. However, it is not limited thereto. The failure detection device 200 according to the present embodiment can be a computer such as a PC (personal computer), a tablet computer, a smartphone, a workstation, a server computer, or a general-purpose computer, which is configured separately from the power conversion device 100, or a computer system in which a plurality of computers are connected. Such a computer system is also a broad computer. In addition, the failure detection device 200 can be installed by a virtual computer environment in which one or a plurality of computers can be executed in a computer. Alternatively, the failure detection device 200 can also be a dedicated computer designed for failure detection, or a dedicated hardware implemented by a dedicated circuit. Furthermore, in a case where the failure detection device 200 can be connected to the Internet, the failure detection device 200 can be implemented by cloud computing.

[0164] Thus, the fault detection device 200 acquires the detection values from the magnetic sensors included in the current detector 170 and estimates the phase currents. Then, the fault detection device 200 detects a fault of any of the magnetic sensors included in the current detector 170 based on the estimated values of the phase currents. Thus, according to the fault detection device 200, even in a case where the current detector 170 is provided only for two phases of the three-phase alternating current, it is possible to detect a case where any of the magnetic sensors has a fault. In particular, the fault detection device 200 can detect a fault of any of the third magnetic sensor 173 and the fourth magnetic sensor 174 based on a difference between the first estimated value iwest(U) and the second estimated value iwest(W1), and a difference between the first estimated value iwest(U) and the third estimated value iwest(W2). Further, the fault detection device 200 can detect a fault of any of the first magnetic sensor 171 and the second magnetic sensor 172 based on a difference between the fourth estimated value iu_est(W) and the fifth estimated value iu_est(U1), and a difference between the fourth estimated value iu_est(W) and the sixth estimated value iu_est(U2). Thus, according to the fault detection device 200, it is possible to determine the magnetic sensor that has a fault. Further, in the present embodiment, the power conversion device 100 having such a fault detection device 200 is provided. Thus, even in the power conversion device 100 where a redundant current detection unit is required in order to ensure reliability, it is possible to achieve redundancy without providing the current detector 170 on all of the three phases. Therefore, according to such a power conversion device 100, it is possible to reduce the total volume of the current detector 170, to achieve downsizing, and to reduce costs. At this time, the arithmetic circuit 175 can be built in the current detector 170. According to such a current detector 170, it is possible to output not only the detection values detected by the pair of magnetic sensors respectively, but also an operation result obtained by using these detection values. Alternatively, the arithmetic circuit 175' can be built in the power conversion device 100, and such an arithmetic circuit 175' can be mounted on a substrate on which the control circuit 150 is mounted. According to such a power conversion device 100, even in a case where the current detector 170' that does not include the arithmetic circuit 175 is used, it is possible to obtain the same operation result as the arithmetic circuit 175 on the same substrate as the control circuit 150.

[0165] Various embodiments of the present application can be described in the general context of a flow diagram and block diagram, where each block represents a phase of the processes, and each block can represent a portion of a device that performs the operations. The specific stages and portions can be implemented with specialized circuits, programmable circuits provided with computer-readable commands stored on a computer-readable medium, and / or a processor provided with computer-readable commands stored on a computer-readable medium. The specialized circuits can include digital and / or analog hardware circuits, and can include integrated circuits (ICs) and / or discrete circuits. The programmable circuits can include reconfigurable hardware circuits, including memory elements such as logic AND, logic OR, logic XOR, logic NAND, logic NOR, and other logic operations, flip-flops, registers, field-programmable gate arrays (FPGAs), programmable logic arrays (PLAs), and the like.

[0166] The computer-readable medium can include any tangible device that can store commands, which, when executed by a suitable device, cause the device to perform a process. The computer-readable medium having stored therein the commands causes the computer-readable medium to have a product, which includes the commands executable to generate means for performing the operations specified in the flow diagram or the block diagram. As examples of the computer-readable medium, electronic storage media, magnetic storage media, optical storage media, electromagnetic storage media, semiconductor storage media, and the like can be included. As other examples of the computer-readable medium, a floppy disk, a flexible disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an electrically erasable programmable read-only memory (EEPROM), a static random access memory (SRAM), a compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a Blu-ray (RTM) disk, a memory stick, an integrated circuit card, and the like can be included.

[0167] The computer-readable commands can include assembly commands, instruction set architecture (ISA) commands, machine commands, machine-dependent commands, microcode, firmware commands, state-setting data, or any one of source code or object code that describes a set of operations to be performed on the processor, using any combination of one or more programming languages, such as an object oriented programming language, such as Smalltalk (registered trademark), JAVA (registered trademark), C++, and the like, and a conventional procedural programming language, such as the "C" programming language or similar programming languages.

[0168] The computer readable commands are provided to a processor or programmable circuit of a general purpose computer, a special purpose computer, or other programmable data processing apparatus to produce a machine, in order to cause an apparatus for performing the operations specified by the flowchart or block diagram to execute the computer readable commands. As examples of the processor, there are included a computer processor, a processing unit, a microprocessor, a digital signal processor, a controller, a microcontroller, and the like.

[0169] Figure 6 is an example that can embody the present application as a whole or in part. A program installed in the computer 9900 can function as or perform the operation associated with the apparatus or one or more parts of the apparatus related to the embodiments of the present application in the computer 9900, or can execute the operation or the one or more parts, and / or can execute or perform the process or the stage of the process related to the embodiments of the present application in the computer 9900. Such a program can perform the relevant specific operation in the computer 9900 by executing part or all of the corresponding operation in the blocks of the flowchart and the block diagram described in this specification by the CPU 9912.

[0170] The computer 9900 of the present embodiment includes the CPU 9912, the RAM 9914, the graphic controller 9916, and the display device 9918, which are connected to each other through the host controller 9910. The computer 9900 further includes the input / output units such as the communication interface 9922, the hard disk drive 9924, the DVD drive 9926, and the IC card drive, which are connected to the host controller 9910 via the input / output controller 9920. The computer further includes the legacy input / output units such as the ROM 9930 and the keyboard 9942, which are connected to the input / output controller 9920 via the input / output chip 9940.

[0171] The CPU 9912 acts in accordance with the programs stored in the ROM 9930 and the RAM 9914, thereby controlling the units. The graphic controller 9916 acquires the image data generated by the CPU 9912 in a frame buffer or the like provided in the RAM 9914 or in itself, and displays the image data on the display device 9918.

[0172] The communication interface 9922 communicates with other electronic devices via a network. The hard disk drive 9924 stores programs and data used by the CPU 9912 in the computer 9900. The DVD drive 9926 reads programs or data from the DVD-ROM 9901, and provides the programs or data to the hard disk drive 9924 via the RAM 9914. The IC card drive reads programs and data from an IC card, and / or writes programs and data to the IC card.

[0173] In this process, the ROM 9930 stores a boot program or the like executed by the computer 9900 at the time of activation, and / or a program dependent on the hardware of the computer 9900. The input / output chip 9940 can also connect various input / output units to the input / output controller 9920 via a parallel port, a serial port, a keyboard port, a mouse port, and the like.

[0174] The programs are provided from a computer-readable medium such as a DVD-ROM 9901 or an IC card. The programs are read out from the computer-readable medium, and examples of the computer-readable medium are installed in the hard disk drive 9924, the RAM 9914, or the ROM 9930, and executed by the CPU 9912. Information processing described in these programs is read into the computer 9900, and the programs are linked with the various types of hardware resources described above. The apparatus or method can also be configured to implement the operation or processing of information in accordance with the use of the computer 9900.

[0175] For example, in the case where communication is performed between the computer 9900 and an external device, the CPU 9912 executes a communication program loaded into the RAM 9914, and based on the processing described in the communication program, instructs the communication interface 9922 to perform communication processing. The communication interface 9922 reads transmission data stored in a transmission buffer processing area provided in a storage medium under the control of the CPU 9912, the RAM 9914, the hard disk drive 9924, the DVD-ROM 9901, or an IC card, and transmits the read transmission data to a network, or writes reception data received by the network into a reception buffer processing area provided in the storage medium, and the like.

[0176] The CPU 9912 can also cause all or a desired part of a file or a database stored in an external storage medium such as the hard disk drive 9924, the DVD drive 9926 (DVD-ROM 9901), an IC card, and the like to be read into the RAM 9914, and perform various types of processing on the data on the RAM 9914. Subsequently, the CPU 9912 writes the processed data back to the external storage medium.

[0177] Various types of programs, data, tables, and databases, and such various types of information can be stored to the storage medium, and information processing is accepted. The CPU 9912 can perform various types of processing on data read out from the RAM 9914, that is, various types of operations, information processing, condition determination, conditional branching, unconditional branching, search / replacement of information, and the like, specified by a command sequence of a program as described throughout the present disclosure, and write back the results to the RAM 9914. Further, the CPU 9912 can search for information in a file, a database, and the like, in the storage medium. For example, in a case where the storage medium stores attribute values of a first attribute each having an attribute value of a second attribute associated therewith, the CPU 9912 searches for an entry in which a condition of specifying the attribute value of the first attribute coincides from among the plurality of entries, reads the attribute value of the second attribute stored in the entry, and thereby acquires the attribute value of the second attribute associated with the first attribute that satisfies a condition set in advance.

[0178] The program or software module described above can be stored in a computer readable medium on or near the computer 9900. Further, a storage medium such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet can be used as the computer readable medium, and thereby the program can be provided to the computer 9900 via the network.

[0179] The above describes the present application using embodiments, but the technical scope of the present application is not limited to the scope described in the above embodiments. Various changes or improvements can be made to the above embodiments, as will be apparent to those skilled in the art. The embodiments to which such changes or improvements are applied are also included in the technical scope of the present application according to the recitations of the patent claims.

[0180] Note that the order of execution of each process of the actions, processes, steps, and stages, and the like, of the apparatuses, systems, programs, and methods shown in the claims, the specification, and the drawings can be implemented in any order as long as it is not specifically indicated as before, after, or the like, or the output of the previous process is used in the subsequent process. The order of the flow of actions in the claims, the specification, and the drawings is used for ease of explanation, but does not mean that it must be implemented in that order.

[0181] Label Explanation

[0182] 10 Power supply

[0183] 20 Motor

[0184] 100 Power conversion device

[0185] 110 Rectifier circuit

[0186] 120 filter capacitor

[0187] 130 inverter circuit

[0188] 140 conductor

[0189] 150 control circuit

[0190] 160 drive circuit

[0191] 170 current detector

[0192] 171 first magnetic sensor

[0193] 172 second magnetic sensor

[0194] 173 third magnetic sensor

[0195] 174 fourth magnetic sensor

[0196] 175 arithmetic circuit

[0197] 176 output section

[0198] 200 failure detection device

[0199] 210 acquisition section

[0200] 220 presumption section

[0201] 230 detection section

[0202] 9900 computer

[0203] 9901 DVD-ROM

[0204] 9910 main controller

[0205] 9912 CPU

[0206] 9914 RAM

[0207] 9916 graphics controller

[0208] 9918 display device

[0209] 9920 input / output controller

[0210] 9922 communication interface

[0211] 9924 hard disk drive

[0212] 9926 DVD drive

[0213] 9930 ROM

[0214] 9940 input / output chip

[0215] 9942 keyboard.

Claims

1. A fault detection apparatus, characterized by, comprises: an acquisition section that acquires a first detection value whose value increases as a magnetic flux density generated by a first phase current increases, and a second detection value whose value decreases as the magnetic flux density generated by the first phase current increases, from a first magnetic sensor and a second magnetic sensor, respectively, and acquires a third detection value whose value increases as a magnetic flux density generated by a second phase current increases, and a fourth detection value whose value decreases as the magnetic flux density generated by the second phase current increases, from a third magnetic sensor and a fourth magnetic sensor, respectively; an estimation section that calculates a first estimated value of the second phase current estimated using the first detection value and the second detection value, a second estimated value of the second phase current estimated using the third detection value, and a third estimated value of the second phase current estimated using the fourth detection value; and a detection section that detects a failure of any of the third magnetic sensor and the fourth magnetic sensor based on the first estimated value, the second estimated value, and the third estimated value.

2. The failure detection device according to claim 1, wherein the detection section detects the failure of any of the third magnetic sensor and the fourth magnetic sensor based on a difference between the first estimated value and the second estimated value, and a difference between the first estimated value and the third estimated value.

3. The failure detection device according to claim 2, wherein the detection section detects the failure of any of the third magnetic sensor and the fourth magnetic sensor when only one of the difference between the first estimated value and the second estimated value, and the difference between the first estimated value and the third estimated value does not satisfy a predetermined criterion.

4. The failure detection device according to claim 3, wherein the detection section detects a failure of the third magnetic sensor when the difference between the first estimated value and the second estimated value does not satisfy the predetermined criterion.

5. The failure detection device according to claim 3 or 4, wherein the detection section detects a failure of the fourth magnetic sensor when the difference between the first estimated value and the third estimated value does not satisfy the predetermined criterion.

6. The failure detection device according to any one of claims 1 to 5, wherein the estimation section further calculates a fourth estimated value of the first phase current estimated using the third detection value and the fourth detection value, a fifth estimated value of the first phase current estimated using the first detection value, and a sixth estimated value of the first phase current estimated using the second detection value, the detection section further detects a failure of any of the first magnetic sensor and the second magnetic sensor based on the fourth estimated value, the fifth estimated value, and the sixth estimated value.

7. The failure detection device according to claim 6, wherein the detection section detects the failure of any of the first magnetic sensor and the second magnetic sensor based on a difference between the fourth estimated value and the fifth estimated value, and a difference between the fourth estimated value and the sixth estimated value.

8. The failure detection device according to claim 7, wherein The detection section detects a failure of any of the first magnetic sensor and the second magnetic sensor when only one of a difference between the fourth estimated value and the fifth estimated value and a difference between the fourth estimated value and the sixth estimated value does not satisfy a predetermined criterion.

9. The failure detection device according to claim 8, wherein The detection section detects a failure of the first magnetic sensor when the difference between the fourth estimated value and the fifth estimated value does not satisfy the predetermined criterion.

10. The failure detection device according to claim 8 or 9, wherein The detection section detects a failure of the second magnetic sensor when the difference between the fourth estimated value and the fifth estimated value does not satisfy the predetermined criterion.

11. A power conversion device, characterized by, including: the failure detection device according to any one of claims 1 to 10; an inverter circuit including a semiconductor switching element; a drive circuit that drives the semiconductor switching element; and a control circuit that controls the drive circuit.

12. The power conversion device according to claim 11, wherein The control circuit performs feedback control based on an estimated value calculated using a detection value from a magnetic sensor in which no failure is detected when a failure of any of the magnetic sensors is detected.

13. The power conversion device according to claim 11 or 12, wherein An arithmetic circuit that obtains an arithmetic result corresponding to a total of magnitudes of magnetic flux densities detected by the first magnetic sensor and the second magnetic sensor, respectively, by arithmetic operation using the first detection value and the second detection value is mounted on a substrate on which the control circuit is mounted.

14. The power conversion device according to claim 13, wherein The arithmetic circuit also obtains an arithmetic result corresponding to a total of magnitudes of magnetic flux densities detected by the third magnetic sensor and the fourth magnetic sensor, respectively, by arithmetic operation using the third detection value and the fourth detection value.

15. A recording medium, characterized by The recording medium is executed by a computer and records a failure detection program, the computer functions as an acquisition section, an estimation section, and a detection section, The acquisition section acquires a first detection value whose value increases as a magnetic flux density generated by a first phase current increases and a second detection value whose value decreases as the magnetic flux density generated by the first phase current increases from a first magnetic sensor and a second magnetic sensor, respectively, and acquires a third detection value whose value increases as a magnetic flux density generated by a second phase current increases and a fourth detection value whose value decreases as the magnetic flux density generated by the second phase current increases from a third magnetic sensor and a fourth magnetic sensor, respectively; The estimation section calculates a first estimated value that estimates the second phase current using the first detection value and the second detection value, a second estimated value that estimates the second phase current using the third detection value, and a third estimated value that estimates the second phase current using the fourth detection value; and The detection section detects a failure of any of the third magnetic sensor and the fourth magnetic sensor based on the first estimated value, the second estimated value, and the third estimated value.

16. A current detector, comprising: comprising: a first magnetic sensor that detects a first detection value that increases as a magnetic flux density generated by a current flowing through a conductor increases; a second magnetic sensor that detects a second detection value that decreases as the magnetic flux density generated by the current flowing through the conductor increases; an arithmetic circuit that obtains an arithmetic result corresponding to a total of magnitudes of the magnetic flux densities detected by the first magnetic sensor and the second magnetic sensor, respectively, by using an arithmetic operation of the first detection value and the second detection value; and an output section that outputs the first detection value, the second detection value, and the arithmetic result. ​

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