Power Conversion Device

Abstract

To provide a power conversion device in which an abnormality in a current detector and an AC current abnormality that is caused by a component other than the current detector are detected and distinguished from each other.SOLUTION: A power conversion device includes at least one of a converter 21, an inverter 31, and an AC converter. The power conversion device includes a plurality of current detectors 26, 27, 28, 34, 35, 36 that detect AC currents in respective phases between an AC power source 1 and the power conversion device 100 or between the power conversion device and a load device 4, and an abnormality determinator 71, 72 that determines an abnormality in the plurality of current detectors and an AC current abnormality that is caused by a component other than the current detectors. The abnormality determinator includes an AC current detector abnormality determination unit that determines an abnormality in the detected current values in the plurality of phases detected by the plurality of current detectors, an AC current estimation unit that calculates an estimated current values at the current detectors on the basis of a determination result obtained by the AC current detector abnormality determination unit, and an AC current abnormality determination unit that determines an abnormality in the detected current values in the plurality of phases detected by the current detectors on the basis of an output from the AC current estimation unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] Conventionally, there is known a power conversion device that converts power from an AC power source into power with variable voltage and variable frequency. The power conversion device includes a current detector that measures the current flowing between the power source and the power conversion device, and controls the current to be a predetermined value. The power conversion device also includes a current detector that measures the current flowing between the power conversion device and a load device, and controls the current to be a predetermined value. Current detectors that detect the current flowing between a power conversion device and an electric motor, or between a power conversion device and a power source, are essential for controlling the current in the power conversion device. Therefore, an abnormality in a current detector can cause the system to operate unstable, and in the worst case, can lead to an unplanned shutdown of the system.

[0003] Furthermore, electric motors in power conversion equipment are essential for driving factory equipment, etc. As damage to the coating of the stator winding in an electric motor progresses, insulation deterioration causes a winding short circuit (layer short, layer short, inter-layer short) between adjacent windings. Because the winding resistance value of the phase where the layer short occurs is smaller than the winding resistance values ​​of the other phases, an excessive current continues to flow in the phase where the layer short occurs. If an excessive current continues to flow through the phase where a layer short occurs, the insulation deterioration will accelerate, which may cause a further layer short in the phase where the layer short occurred, eventually resulting in burnout or a ground fault, which may cause the motor to stop. Therefore, it is important to detect the occurrence of a layer short in the early stages.

[0004] The following method is known as a technique for checking the soundness of a current detector that detects a current flowing between a power conversion device and an electric motor. For example, Patent Document 1 discloses a method and technology for detecting the current of each phase flowing between a power conversion device and an electric motor, and determining the phase in which an abnormality has occurred by comparing the effective current value of each phase with the effective current value of the other phases. Furthermore, for example, Patent Documents 2 and 3 disclose techniques for detecting layer shorts in the stator winding of an electric motor. Patent Document 2 discloses a method and technology for detecting layer shorts by detecting each phase current of an electric motor, calculating the current ratio between each phase, and comparing each current ratio between each phase with a reference value. Patent Document 3 discloses a method and technology for calculating a motor operation state value based on each phase voltage from each phase current of an electric motor, and determining an inter-layer short circuit based on the motor operation state value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3737370 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-14151 [Patent Document 3] Patent No. 5462121 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology described in Patent Document 1 can determine the phase of a current detector in which an abnormality has occurred when a balanced three-phase load is connected. However, when a layer short occurs, a large amount of current flows through the phase in which the layer short has occurred, which has a small load, resulting in a discrepancy in the three-phase current effective values. This poses a problem in that there is a risk of falsely detecting an abnormality in the current detector even when the current detector is normal.

[0007] Furthermore, the technology described in Patent Document 2 can determine the occurrence of a layer short circuit when the current detector is normal. However, if an abnormality occurs in the current detector, the detected current values ​​between the phases will not match even when no layer short circuit has occurred. Therefore, there is a problem that a layer short circuit may be erroneously detected when no layer short circuit has occurred.

[0008] Furthermore, the technology described in Patent Document 3 makes it possible to determine whether a layer short circuit has occurred when the current detector is normal. However, if an abnormality occurs in the current detector, the detection signal of the abnormal current detector is used for motor control, and the motor operation state value changes due to the current detector abnormality even when no layer short circuit has occurred. Therefore, there is a problem that a layer short circuit may be erroneously detected when no layer short circuit has occurred.

[0009] As described above, the techniques of Patent Documents 1 to 3 do not disclose a technique for distinguishing between an abnormality in an AC current detector and an AC current abnormality caused by something other than the AC current detector.

[0010] The present invention has been made in consideration of the above circumstances, and has as its objective (purpose) to provide a power conversion device that can distinguish between abnormalities in a current detector and AC current abnormalities caused by factors other than the current detector and detect them. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention is configured as follows. That is, the power conversion device of the present invention is a power conversion device having at least one of a converter that converts AC to DC, an inverter that converts DC to AC, or an AC converter that converts AC to AC, and is characterized in that it comprises a plurality of current detectors that detect, for each phase, a multi-phase AC current flowing between an AC power source and the power conversion device, or between the power conversion device and a load device, and an abnormality determiner that determines abnormalities in the multiple current detectors and abnormalities in the AC current caused by factors other than the current detectors, and the abnormality determiner comprises an AC current detector abnormality determination unit that determines abnormalities in the multi-phase current detection values ​​detected by the multiple current detectors, an AC current estimation unit that calculates current estimates of the current detectors based on the determination results of the AC current detector abnormality determination unit, and an AC current abnormality determination unit that determines abnormalities in the multi-phase current detection values ​​detected by the multiple current detectors based on the output of the AC current estimation unit.

[0012] Other means will be described in the description of the preferred embodiment of the invention. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a power conversion device that can distinguish between an abnormality in a current detector and an AC current abnormality caused by something other than the current detector and detect the abnormality. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing an example of a circuit configuration of a power conversion device according to a first embodiment of the present invention, and an example of a connection configuration with an AC power source and an electric motor. [Figure 2A] 2 is a diagram showing a specific example of the configuration of a converter power conversion unit of the power conversion device according to the first embodiment of the present invention. FIG. [Figure 2B] 2 is a diagram showing a specific configuration example of an inverter power conversion unit of the power conversion device according to the first embodiment of the present invention. FIG. [Figure 3A] 3 is a diagram showing a detailed block configuration of a converter-side abnormality determiner in the power conversion device according to the first embodiment of the present invention. FIG. [Figure 3B]3 is a diagram showing a detailed block configuration of an inverter-side abnormality determiner in the power conversion device according to the first embodiment of the present invention. FIG. [Figure 4] 3C is a flowchart showing an example of an abnormality determination process in the inverter-side abnormality determiner of FIG. 3B. [Figure 5] 3B is a block diagram showing details of an example of a converter-side AC current detector abnormality determination unit in FIG. 3A. FIG. [Figure 6] 3C is a block diagram showing details of an example of an inverter-side AC current detector abnormality determination unit in FIG. 3B. FIG. [Figure 7] FIG. 2 is a block diagram illustrating various processes in an abnormality degree calculation unit. [Figure 8] 7 is a flowchart showing an example of an abnormality determination process in an inverter-side AC current detector abnormality determination unit shown in FIG. 6. [Figure 9] 3 is a diagram illustrating an example of the configuration of an inverter-side AC current estimator in an inverter-side abnormality determiner in the power conversion device according to the first embodiment of the present invention. FIG. [Figure 10] FIG. 4 is a diagram illustrating a second configuration example of the inverter-side AC current estimator in the inverter-side abnormality determiner in the power conversion device according to the first embodiment of the present invention. [Figure 11] 2 is a diagram illustrating an example of the configuration of an inverter-side AC current abnormality determination unit in the power conversion device according to the first embodiment of the present invention. FIG. [Figure 12] 12 is a flowchart showing an example of an abnormality determination process in an inverter-side AC current abnormality determination unit shown in FIG. [Figure 13] FIG. 10 is a diagram illustrating another example of the configuration of the inverter-side AC current abnormality determination unit. [Figure 14] 14 is a flowchart showing an example of an abnormality determination process in the inverter-side AC current detector abnormality determination unit shown in FIG. [Figure 15] FIG. 4 is a diagram illustrating an example of the configuration of a power conversion device according to a second embodiment of the present invention. [Figure 16] FIG. 1 is a diagram showing an example of a configuration in which three-phase AC power from an AC power supply is supplied to an electric motor, which is a three-phase load, via an AC-AC power converter. [Figure 17] FIG. 10 is a diagram illustrating an example of the configuration of an AC current detector abnormality determination unit of a power conversion device according to a third embodiment of the present invention. [Figure 18] FIG. 10 is a diagram illustrating a configuration example of an inverter power conversion unit of a power conversion device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, modes for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the drawings as appropriate. The embodiments described below are merely examples for explaining the present invention, and have been omitted or simplified as appropriate for clarity of explanation. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the invention. When there are multiple components having the same or similar functions, they may be described using the same reference numerals with different subscripts. Furthermore, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted in the description.

[0016] First Embodiment: Power Conversion Device A power conversion device according to a first embodiment of the present invention will be described with reference to FIGS. The following description not only describes the power conversion device but also describes a method for detecting an abnormality in the power conversion device.

[0017] FIG. 1 is a diagram showing an example of a circuit configuration of a power conversion device 100 according to a first embodiment of the present invention, and an example of a connection configuration with an AC power source 1 and an electric motor 4. As shown in FIG. In FIG. 1, the power conversion device 100 includes a converter unit 2, an inverter unit 3, a converter control device 5, and an inverter control device 6. The power conversion device 100 receives AC power from an AC power supply 1, converts the AC power by a converter unit 2 and an inverter unit 3, and outputs the converted AC power to an electric motor 4. The power conversion device 100 also includes a converter-side abnormality determiner 71 , an inverter-side abnormality determiner 72 , and a display 73 .

[0018] A converter unit (also called a converter) 2 receives AC power from an AC power source 1 and converts it into DC power. An inverter unit (also called an inverter) 3 converts the DC power output by the converter unit 2 into AC power of a desired voltage and frequency. The converted AC power drives the electric motor 4. The electric motor 4 is provided with a speed detector 7. The converter control device 5 controls the converter unit 2. The inverter control device 6 controls the inverter unit 3.

[0019] <Converter Unit 2> In FIG. 1, the converter unit 2 includes a converter power conversion section 21. As shown in FIG. 1, the converter unit 2 includes a converter power conversion section 21 corresponding to three phases (R phase, S phase, and T phase), a P wiring 40, a C wiring 41, an N wiring 42, a converter P-side smoothing capacitor 22 (smoothing capacitor), a converter N-side smoothing capacitor 23 (smoothing capacitor), a converter P-side DC voltage detector 24, a converter N-side DC voltage detector 25, an R-phase current detector 26, an S-phase current detector 27, and a T-phase current detector 28. The U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36 detect the currents flowing in the R phase, the S phase, and the T phase, respectively, of the three phases (R phase, S phase, and T phase) input from the AC power supply 1 to the converter power conversion unit 21. The specific configuration of converter power conversion unit 21 corresponding to three phases (R phase, S phase, T phase) will be described later with reference to FIG. 2A.

[0020] The converter unit 2 is a so-called three-level converter that converts AC power input to the converter power conversion section 21 into DC power with a positive potential (first potential) level, a neutral point (zero) potential (second potential) level, and a negative potential (third potential) level. The positive potential level is connected by a P wiring 40, the neutral point potential level is connected by a C wiring 41, and the negative potential level is connected by an N wiring 42.

[0021] Converter P-side smoothing capacitor 22 suppresses fluctuations in the DC voltage between P wiring 40 and C wiring 41. The converter N-side smoothing capacitor 23 suppresses fluctuations in the DC voltage between the C wiring 41 and the N wiring 42. The converter P-side DC voltage detector 24 measures the voltage across the terminals of the converter P-side smoothing capacitor 22 . The converter N-side DC voltage detector 25 measures the voltage across the terminals of the converter N-side smoothing capacitor 23 .

[0022] Next, the specific configurations of the three converter power conversion units 21R, 21S, and 21T that make up the converter power conversion unit 21 will be described. FIG. 2A is a diagram showing a specific example of the configuration of the converter power conversion unit 21 in the power conversion device according to the first embodiment of the present invention. In FIG. 2A, the converter power conversion units 21R, 21S, and 21T for the R phase, S phase, and T phase, each corresponding to one phase, are each configured as a converter that converts AC to DC using a plurality of IGBTs (Insulated Gate Bipolar Transistors) and a plurality of diodes. Converter power conversion units 21R, 21S, and 21T convert the three-phase AC power (voltage) into DC power (voltage), respectively, and supply it to P wiring (positive potential) 40, C wiring (neutral point potential) 41, and N wiring (negative potential) 42. In FIG. 2A, the control circuits that control the multiple IGBTs that configure the converters in converter power conversion units 21R, 21S, and 21T are omitted.

[0023] Each of the converter power conversion units 21R, 21S, and 21T is configured with four transistors, each of which is an IGBT (Insulated Gate Bipolar Transistor), and six diodes. The four transistors (first to fourth transistors) are connected in series between a P wiring 40 and an N wiring 42. The first to fourth transistors are connected to anti-parallel diodes (first to fourth diodes), respectively. If the first to fourth transistors have parasitic diodes, the parasitic diodes may also serve as the anti-parallel diodes (first to fourth diodes).

[0024] The collector of the first transistor is connected to the P wiring 40. The emitter of the fourth transistor is connected to the N wiring 42. The fifth diode and the sixth diode are connected in series, and the cathode of the fifth diode is connected to the connection point between the first transistor and the second transistor. The anode of the sixth diode is connected to the connection point between the third transistor and the fourth transistor. The connection point between the anode of the fifth diode and the cathode of the sixth diode is connected to the C wiring 41. Furthermore, the plurality of transistors of the converter power conversion units 21R, 21S, and 21T are controlled in an integrated manner by the converter control device 5.

[0025] As shown in FIG. 2A, the R-phase power line is connected to the connection point between the second transistor and the third transistor of converter power conversion section 21R. The S-phase power line is connected to the connection point between the second and third transistors of converter power conversion section 21S. The T-phase power line is connected to the connection point between the second and third transistors of converter power conversion unit 21T. However, P wiring 40, C wiring 41, and N wiring 42, which are DC power lines of converter power conversion units 21R, 21S, and 21T, are shared by converter power conversion units 21R, 21S, and 21T.

[0026] As described above, the R phase, S phase, and T phase of the three-phase AC power supply 1 are input separately to the corresponding converter power conversion units 21R, 21S, and 21T, but the DC power converted by the converter power conversion units 21R, 21S, and 21T is shared and used. That is, three-phase AC power (voltage) of R phase, S phase, and T phase is converted into one DC power (voltage). The three converter power conversion units 21R, 21S, and 21T are collectively controlled by converter control device 5 (FIG. 1).

[0027] As described above, the converter unit 2 is provided with the R-phase current detector 26, the S-phase current detector 27, and the T-phase current detector 28, which detect the currents flowing through the R-phase, S-phase, and T-phase of the three-phase AC. R ,I S ,I T This signal is input to the converter control device 5 via the converter-side abnormality determiner 71. Signals of voltage detection values ​​detected by the DC voltage detectors 24 and 25 are input to the converter control device 5. The converter control device 5 will be described later.

[0028] <Inverter Unit 3> In FIG. 1, the inverter unit 3 includes an inverter power conversion section 31. As shown in FIG. 1, the inverter unit 3 includes an inverter power conversion section 31 corresponding to three phases (U phase, V phase, and W phase), a P wiring 40, a C wiring 41, an N wiring 42, an inverter P-side smoothing capacitor 32 (smoothing capacitor), an inverter N-side smoothing capacitor 33 (smoothing capacitor), a U-phase current detector 34, a V-phase current detector 35, and a W-phase current detector 36. The specific configuration of inverter power conversion unit 31 corresponding to three phases (U phase, V phase, W phase) will be described later with reference to FIG. 2B.

[0029] The inverter unit 3 is a so-called three-level inverter that converts DC power having a positive potential (first potential) level, a neutral (zero) potential (second potential) level, and a negative potential (third potential) level into AC power for the electric motor 4. The positive potential levels of the inverter unit 3 and the converter unit 2 are connected by a P wiring 40, the neutral point potential levels are connected by a C wiring 41, and the negative potential levels are connected by an N wiring 42. The inverter P-side smoothing capacitor 32 suppresses fluctuations in the DC voltage between the P wiring 40 and the C wiring 41. The inverter N-side smoothing capacitor 33 suppresses fluctuations in the DC voltage between the C wiring 41 and the N wiring 42.

[0030] In addition, U-phase current detector 34, V-phase current detector 35, and W-phase current detector 36 detect the currents flowing in the U-phase, V-phase, and W-phase, respectively, of the three phases (U-phase, V-phase, and W-phase) output by inverter power conversion unit 31.

[0031] Next, the specific configuration of the three inverter power conversion units 31R, 31S, and 31T that make up inverter power conversion unit 31 will be described. FIG. 2B is a diagram showing a specific example of the configuration of the inverter power conversion unit 31 in the power conversion device according to the first embodiment of the present invention. In FIG. 2B, inverter power conversion units 31U, 31V, and 31W for the U phase, V phase, and W phase, each corresponding to one phase, are each configured as a converter that converts AC to DC using a plurality of IGBTs (Insulated Gate Bipolar Transistors) and a plurality of diodes.

[0032] Each of inverter power conversion units 31U, 31V, and 31W is configured with four IGBT transistors and six diodes. The configuration of inverter power conversion units 31U, 31V, and 31W, which includes four IGBT transistors and six diodes, is substantially the same as the configuration of converter power conversion units 21R, 21S, and 21T, which includes four transistors and six diodes, shown in Fig. 2A. Therefore, a redundant description will be omitted here. The plurality of transistors are controlled in an integrated manner by an inverter control device 6.

[0033] While the three converter power conversion units 21R, 21S, and 21T generate DC power (voltage) from three-phase AC power (voltage), the three inverter power conversion units 31U, 31V, and 31W generate three-phase (U-phase, V-phase, and W-phase) AC power (voltage) from the DC power (voltage). Note that the three-phase AC power (voltage) of the R-phase, S-phase, and T-phase has different voltages and frequencies from the three-phase AC power (voltage) of the U-phase, V-phase, and W-phase.

[0034] As shown in FIG. 1, three inverter power conversion sections 31U, 31V, and 31W of converter power conversion section 21 are controlled in an integrated manner by inverter control device 6. As described above, the inverter unit 3 is provided with a U-phase current detector 34, a V-phase current detector 35, and a W-phase current detector 36, which detect the currents flowing in the U-phase, V-phase, and W-phase of the three-phase AC. Current detection value I detected by current detectors 34, 35, and 36 U ,I V ,I W This signal is input to the inverter control device 6 via the inverter-side abnormality determiner 72. The inverter-side abnormality determiner 72 and the inverter control device 6 will be described later. The outputs of inverter power conversion units 31U, 31V, 31W are outputs of power conversion device 100. The output of power conversion device 100 is directly connected to electric motor 4, which is a three-phase electric motor.

[0035] Converter Control Device 5 In FIG. 1, the converter control device 5 is configured to include a DC voltage command generator 51, a DC voltage controller 52, a current controller 53, and a pulse generator . The DC voltage command generator 51 generates a DC voltage command value indicating the voltage value of the DC voltage to be output from the converter unit 2 , and outputs the DC voltage command value to the DC voltage controller 52 . The DC voltage controller 52 receives as input a DC voltage command value from the DC voltage command generator 51, the terminal voltage of the converter P-side smoothing capacitor 22 detected by the DC voltage detector 24, and the terminal voltage of the converter N-side smoothing capacitor 23 detected by the DC voltage detector 25.

[0036] The DC voltage controller 52 calculates a converter output current command value based on the DC voltage command value from the DC voltage command generator 51 and the inter-terminal voltage values ​​from the DC voltage detectors 24 and 25, and outputs the calculation result to the current controller 53. Specifically, the DC voltage controller 52 calculates the converter output current command value so that the sum of the DC voltage detection values ​​input from the DC voltage detectors 24 and 25 matches the DC voltage command value.

[0037] The current controller 53 receives the converter output current command value from the DC voltage controller 52 and the current detection value I detected by the current detectors 26, 27, and 28. R ,I S ,I T The estimated value of I RH ,I SH ,I TH is input from the converter side abnormality determiner 71. The current controller 53 calculates a converter voltage command value so that the estimated value of the current detection value corresponding to the converter output current output from the current detectors 26, 27, and 28 matches the converter output current command value input from the DC voltage controller 52, and outputs the converter voltage command value to the pulse generator 54.

[0038] The pulse generator 54 generates pulse signals for controlling the on / off of each switching element of the converter power conversion units 21R, 21S, and 21T based on the input converter voltage command value, and outputs the generated pulse signals to the converter power conversion unit 21. Specifically, the pulse generator 54 generates an on / off control pulse signal so that the output voltage from the converter power conversion units 21R, 21S, and 21T coincides with the converter output voltage command value input from the current controller 53.

[0039] As described above, the converter control device 5 performs the various calculation processes described above in the converter unit 2 so that the DC power converted from the AC power has a desired value, and outputs signals to control the converter power conversion sections 21R, 21S, and 21T.

[0040] Inverter control device 6 In FIG. 1, the inverter control device 6 is configured to include a speed command generator 61, a speed controller 62, a current controller 63, and a pulse generator 64. The speed command generator 61 outputs a speed command value indicating the speed at which the electric motor 4 is to operate to the speed controller 62 . The speed controller 62 receives the speed command value from the speed command generator 61 and the speed detection value of the electric motor 4 detected by the speed detector 7 .

[0041] The speed controller 62 calculates an inverter output current command value so that the speed detection value input from the speed detector 7 provided in association with the electric motor 4 matches the speed command value input from the speed command generator 61, and outputs the inverter output current command value to the current controller 63. The current controller 63 receives the inverter output current detection value (current detection value I) from the current detectors 34, 35, and 36 that detect the three-phase AC output current input from the inverter side abnormality judger 72. U ,I V ,I W ) estimate I RH ,I SH ,I THThen, the inverter output current command value from the speed controller 62 is input. The current controller 63 detects the inverter output current I U ,I V ,I W The estimated value of I RH ,I SH ,I TH The inverter voltage command value is calculated so that the inverter output current command value coincides with the inverter output current command value. The inverter voltage command value is then output to the pulse generator 64.

[0042] Pulse generator 64 generates a pulse signal for controlling the on / off of each switching element of inverter power conversion units 31U, 31V, 31W based on the input inverter output voltage command value. Specifically, pulse generator 64 generates a pulse signal for on / off control so that the output voltage from inverter power conversion unit 31 coincides with the inverter output voltage command value input from current controller 63 .

[0043] As described above, the inverter control device 6 controls the inverter power conversion sections 31U, 31V, 31W in the inverter unit 3 so that the output torque and speed of the electric motor 4 satisfy desired characteristics.

[0044] <Configuration Related to Abnormality Determination in Power Conversion Device 100> In FIG. 1, the power conversion device 100 includes a converter-side abnormality determiner 71, an inverter-side abnormality determiner 72, and a display 73 as components related to abnormality determination. The display 73 receives the output signal of the converter-side abnormality determiner 71 and the output signal of the inverter-side abnormality determiner 72 . The display unit 73 is configured with a display device capable of displaying information, such as a liquid crystal display, and displays the determination information of the converter-side abnormality determiner 71 and the inverter-side abnormality determiner 72, as well as various other information.

[0045] Although detailed description will be given later, the converter side abnormality determiner 71 detects the current detection value I R ,I S ,I T Based on this, it is determined whether or not there is an abnormality in the current detectors 26, 27, 28 or in the AC current (for example, AC power supply 1) caused by something other than the current detectors 26, 27, 28.

[0046] The inverter-side abnormality determiner 72 also detects the current detection values ​​I U ,I V ,I W Based on this, it is determined whether or not there is an abnormality in the current detectors 34, 35, 36 or in the AC current caused by something other than the current detectors 34, 35, 36 (for example, the electric motor 4). The processing of the converter-side abnormality determiner 71 and the inverter-side abnormality determiner 72 is implemented by, for example, a processor (not shown) executing a program stored in a memory.

[0047] <Converter-side abnormality judgement device 71> FIG. 3A is a diagram showing a detailed block configuration of the converter-side abnormality determiner 71 in the power conversion device according to the first embodiment of the present invention. 3A, the converter-side abnormality determiner 71 includes a converter-side AC current detector abnormality determiner 711, a converter-side AC current estimator 712, and a converter-side AC current abnormality determiner 713. The current detection values ​​I detected by the R-phase current detector 26, the S-phase current detector 27, and the T-phase current detector 28 are R ,I S ,I T is input to the converter-side AC current detector abnormality determination unit 711 and the converter-side AC current estimation unit 712, respectively.

[0048] The converter-side AC current detector abnormality determination unit 711 diagnoses abnormalities in the R-phase current detector 26, the S-phase current detector 27, and the T-phase current detector 28. Then, the current detector abnormality information is output to the converter-side AC current estimation unit 712 and the display unit 73. The converter side AC current estimation unit 712 estimates the current detection value I R ,I S ,I T and the abnormality information of the current detector input from the converter-side AC current detector abnormality determination unit 711. Then, the estimated AC current estimated value I RH ,I SH ,I TH is output to the converter-side AC current abnormality determination unit 713 and the converter control device 5. The converter side AC current abnormality determination unit 713 determines the AC current estimated value I RH ,I SH ,I TH Based on this, an abnormality in the AC current is determined and output to the display 73.

[0049] FIG. 3B is a diagram showing a detailed block configuration of the inverter-side abnormality determiner 72 in the power conversion device according to the first embodiment of the present invention. 3B, the inverter-side abnormality determiner 72 includes an inverter-side AC current detector abnormality determiner 721, an inverter-side AC current estimator 722, and an inverter-side AC current abnormality determiner 723. The current detection values ​​I detected by the U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36 are U ,I V ,I W is input to the inverter-side AC current detector abnormality determination unit 721 and the inverter-side AC current estimation unit 722, respectively.

[0050] The inverter-side AC current detector abnormality determination unit 721 diagnoses abnormalities in the U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36. Then, the inverter-side AC current estimation unit 722 and the display unit 73 output abnormality information of the current detectors. The inverter side AC current estimation unit 722 estimates the current detection value I U ,IV ,I W and the abnormality information of the current detector input from the inverter side AC current detector abnormality determination unit 721. Then, the estimated AC current estimated value I UH ,I VH ,I WH to the inverter side AC current abnormality determination unit 723 and the inverter control device 6. The inverter side AC current abnormality determination unit 723 outputs the AC current estimated value I UH ,I VH ,I WH Based on this, an abnormality in the AC current is determined and output to the display 73.

[0051] Details of the converter side AC current detector abnormality judgment unit 711, converter side AC current estimation unit 712, converter side AC current abnormality judgment unit 713, inverter side AC current detector abnormality judgment unit 721, inverter side AC current estimation unit 722, and inverter side AC current abnormality judgment unit 723 will be described later.

[0052] 《Display 73》 Returning to Figure 1, the display (information presentation unit) 73 is a display device capable of displaying information, such as an LCD display, and displays information from the converter side abnormality judger 71 and the inverter side abnormality judger 72, as well as various other information.

[0053] <Abnormality Determination Processing in Inverter-Side Abnormality Determinator 72> FIG. 4 is a flowchart showing an example of the abnormality determination process in the inverter-side abnormality determiner 72 of FIG. 3B. The procedure for the abnormality determination process will be described below with reference to the flowchart of FIG.

[0054] Since the converter-side abnormality judger 71 shown in FIG. 3A and the inverter-side abnormality judger 72 shown in FIG. 3B have similar configurations, the detailed explanation of each process in the converter-side abnormality judger 71 and the inverter-side abnormality judger 72 will be given below using the inverter-side abnormality judger 72 as a representative. Furthermore, although a detailed explanation will be omitted, the abnormality judgment related to converter-side abnormality judger 71 can also be explained in a similar manner by replacing current detectors 34 to 36 with current detectors 26 to 28, replacing inverter-side AC current detector abnormality judgement unit 721, inverter-side AC current estimation unit 722, and inverter-side AC current abnormality judgement unit 723 with converter-side AC current detector abnormality judgement unit 711, converter-side AC current estimation unit 712, and converter-side AC current abnormality judgement unit 713, respectively, replacing inverter control device 6 with converter control device 5, replacing motor 4 with AC power supply 1, and replacing suffixes U, V, and W with R, S, and T.

[0055] Step S101 In FIG. 4, when the abnormality determination process in the inverter-side abnormality determiner 72 is initiated (started), the process proceeds to step S101. In step S101, the inverter-side abnormality determiner 72 determines the current detection value I U , I V , I W Determine whether all of are zero. The inverter side abnormality judgement device 72 detects the current I U , I V , I W If it is determined that all of the above are zero (Yes), the process proceeds to step S102. On the other hand, the current detection value I U , I V , I W If at least one of these is not zero (No), the process proceeds from step S101 to step S103.

[0056] Step S102 If the process proceeds from step S101 to step S102, it is determined in step S102 that there is an abnormality in inverter power conversion units 31U, 31V, 31W. Then, the inverter side abnormality judger 72 outputs a command to the display 73 to cause the display 73 to display information indicating that there is an abnormality in the inverter power conversion units 31U, 31V, 31W (for example, a display saying "Power conversion unit abnormality"). When the process of step S102 is completed, the process proceeds to step S113, which will be described later.

[0057] <Step S103> In step S103, the inverter-side abnormality determiner 72 determines the current detection value I output from the current detectors 34, 35, and 36. U , I V , I W Determine whether any of the outputs is continuously zero (or a value close to zero). In step S103, the detected current value I U , I V , I W If it is determined that either of the above is continuously zero (Yes), the process proceeds to step S104. On the other hand, in step S103, the current detection value I U , I V , I W If it is determined that none of the values ​​are continuously zero (No), the process proceeds to step S105.

[0058] Step S104 If the answer to step S103 is Yes, it is determined that an abnormality such as a break or looseness has occurred in the current detection loop (wiring for current detection) used by the current detectors 34, 35, and 36 to perform current detection. If the process proceeds from step S103 to step S104, in step S104, a command is output to the display 73 to cause the display 73 to display information indicating that there is an abnormality in the current detection loop (for example, a display saying "Current Detection Loop"). When the process of step S104 is completed, the process proceeds to step S113, which will be described later.

[0059] Step S105 In step S105, the inverter-side abnormality determiner 72 diagnoses whether or not there is an abnormality in the current detector. An example of a method for detecting an abnormality in the current detector in step S105 will be described in detail later with reference to FIGS. If inverter-side abnormality determiner 72 determines that all of current detectors 34, 35, and 36 are normal (Yes), the process proceeds to step S110. On the other hand, if it is determined that at least one of the current detectors 34, 35, 36 is abnormal (No), the process proceeds from step S105 to step S106.

[0060] Step S106 When the process proceeds from step S105 to step S106, the inverter-side abnormality determiner 72 switches the operation so that the detected current value is replaced with the estimated current value to eliminate the influence of the current detector abnormality, and then allows a predetermined time to elapse. After a predetermined time has elapsed, the process proceeds to step S107. Details of step S106 will be described later with reference to FIGS.

[0061] Step S107 In step S107, inverter-side abnormality determiner 72 diagnoses whether the current phase difference is within a predetermined range using a current estimated value obtained by switching the operation so as to eliminate the influence of the current detector abnormality. An example of a method for detecting a current phase difference will be described in detail later with reference to FIGS. If the inverter-side abnormality determiner 72 determines that the current phase difference is within the predetermined range (Yes), the process proceeds to step S108. On the other hand, if it is determined that the current phase difference is outside the predetermined range (No), the process proceeds from step S107 to step S109. As will be described later with reference to FIGS. 13 and 14, in step S107, the current amplitude may be used instead of the current phase difference to determine whether the current amplitude is within a predetermined range.

[0062] Step S108 In step S108, inverter-side abnormality determiner 72 determines that the current detector is abnormal and that the AC current is normal. Then, the control unit 73 outputs a command to the display unit 73 to display information indicating this determination (for example, a message saying "current detector is abnormal and AC current is normal"). When the process of step S108 is completed, the process proceeds to step S113, which will be described later.

[0063] Step S109 In step S109, the inverter-side abnormality determiner 72 determines that both the current detector and the AC current are abnormal. Then, the control unit 73 outputs a command to the display unit 73 to display information indicating this determination (for example, a message saying "current detector abnormal and AC current abnormal"). When the process of step S109 is completed, the process proceeds to step S113, which will be described later.

[0064] <Step S110> In step S110, the inverter-side abnormality determiner 72 diagnoses whether the current phase difference is within a predetermined range. An example of a method for detecting a current phase difference will be described in detail later with reference to FIGS. If the inverter-side abnormality determiner 72 determines that the current phase difference is within the predetermined range (Yes), the process proceeds to step S111. On the other hand, if it is determined that the current phase difference is outside the predetermined range (No), the process proceeds from step S110 to step S111. As will be described later with reference to FIGS. 13 and 14, in step S110, the current amplitude may be used instead of the current phase difference to determine whether the current amplitude is within a predetermined range.

[0065] Step S111 In step S111, the inverter-side abnormality determiner 72 determines that the current detector is normal and that the AC current is normal, and ends the series of flow processes for abnormality determination processing (END). In this case, the display 73 does not indicate that the current detector and AC current are normal. However, if information indicating that the current detector and AC current are normal (for example, a message stating "current detector normal and AC current normal") is to be displayed on the display 73, a display command may be output to the display 73.

[0066] <Step S112> In step S112, the inverter-side abnormality judger 72 outputs a command to cause the display 73 to display information indicating that the current detector is normal and the AC current is abnormal (for example, a message stating "Current detector normal and AC current abnormal"). When the process of step S112 is completed, the process proceeds to step S113.

[0067] <Step S113> In step S113, the next process is executed following steps S102, S104, S108, S109, and S112. In step S113, the inverter-side abnormality determiner 72 outputs to the display 73 a command to display information prompting the user to perform an inspection (for example, a message saying "Please inspect and replace the abnormal part") on the display 73. Then, the series of abnormality determination processes is ended.

[0068] <Supplementary explanation regarding the effect of the invention through the judgment process in the flowchart> Next, a supplementary explanation will be given regarding the effect of the invention achieved by the determination process in the flowchart of FIG. If at least one of the current detectors 34, 35, and 36 is abnormal, the inverter control device 6 is controlled using the signal of the abnormal current detector, and therefore the pulse output to the pulse generator 64 includes the influence of the abnormal current detector. Therefore, the currents of the current detectors 34, 35, and 36 include the influence of the current detector abnormality, and it is not possible to distinguish between an abnormality in the current detector and an AC current abnormality caused by something other than the current detector.

[0069] 4, if the current detector is diagnosed as abnormal, operation is switched to eliminate the influence of the current detector abnormality in step S106. By switching operation in this way, the inverter control device 6 is controlled in a state where the influence of the signal from the abnormal current detector is eliminated. Furthermore, by switching the operation, the influence of current detector abnormality on the currents of the current detectors 34, 35, 36 is eliminated, so that it is possible to determine in step S107 whether or not there is an AC current abnormality caused by something other than the current detectors.

[0070] <Example of the configuration of the converter-side AC current detector abnormality determination unit 711 and the inverter-side AC current detector abnormality determination unit 721 in step S105> The converter side AC current detector abnormality determination unit 711 and the inverter side AC current detector abnormality determination unit 721 preferably use a determination method that utilizes Kirchhoff's current law. That is, according to Kirchhoff's current law, the sum of the true values ​​of the three-phase AC current is 0, so if the sum of the detected values ​​of the AC current detector is 0, the AC current detector is normal, and if it is not 0, the AC current detector is abnormal. Next, an example of the converter-side AC current detector abnormality determining unit 711 and the inverter-side AC current detector abnormality determining unit 721 will be described.

[0071] <<Converter-Side AC Current Detector Abnormality Determination Unit 711>> FIG. 5 is a block diagram showing details of an example of the converter-side AC current detector abnormality determination unit 711 in FIG. 3A. In FIG. 5, converter side AC current detector abnormality determination unit 711 includes adder 7111 (first addition unit), multipliers 7112R, 7112S, 7112T (first multiplication unit), and filters 7113R, 7113S, 7113T (first filters). Furthermore, converter-side AC current detector abnormality determination unit 711 includes multipliers 7114R, 7114S, and 7114T (third multiplication units), an adder 7115 (third addition unit), and a filter 7116 (third filter). In addition, the converter side AC current detector abnormality determination unit 711 includes multipliers 7114CR, 7114CS, 7114CT (second multiplication unit), an adder 7115C (second addition unit), a filter 7116C (second filter), and an abnormality degree calculation unit 7117.

[0072] The current detection value I detected by the R-phase current detector 26 R are input to the adder 7111 and the multipliers 7112R, 7114R, 7114CT, and 7114CS, respectively. The current detection value I detected by the S-phase current detector 27 S are input to the adder 7111, and the multipliers 7112S, 7114S, 7114CT, and 7114CR. The current detection value I detected by the T-phase current detector 28 T are input to the adder 7111, and the multipliers 7112T, 7114T, 7114CR, and 7114CS, respectively.

[0073] The adder 7111 calculates the current detection value I R ,I S ,I T Sum of I C0 (=I R +I S +I T ) is calculated. The calculated sum I C0 are input to each of multipliers 7112R, 7112S, and 7112T.

[0074] The multiplier 7112R multiplies the current detection value I R and Sum I C0 Product D R Calculate. The multiplier 7112S multiplies the current detection value I S and Sum I C0 Product D S Calculate. The multiplier 7112T multiplies the current detection value I T and Sum I C0 Product D T Calculate. The product D output from the multipliers 7112R, 7112S, and 7112T R ,D S ,DT are input to the filters 7113R, 7113S, and 7113T of the corresponding phases, respectively.

[0075] The filter 7113R has a product D R By reducing or eliminating the AC component from the DC current product F R Output. It should be noted that filters 7113R, 7113S, 7113T, 7116 and 7116C in converter side AC current detector abnormality determination unit 711 reduce or remove AC components contained in the input signal, but hereinafter will be simply referred to as "removing". The filter 7113S has a product D S By removing the AC component from S Output. The filter 7113T has a product D T By removing the AC component from T Output. DC current product F output from filters 7113R, 7113S, and 7113T R ,F S ,F T is input to the abnormality degree calculation unit 7117.

[0076] The first and second input terminals of the multiplier 7114R are connected to the current detection value I R are input, and the product of these inputs, i.e., the current detection value I R Squared I R 2 is output from multiplier 7114R. The first and second input terminals of the multiplier 7114S are connected to the current detection value I S are input, and the product of these inputs, i.e., the current detection value I S Squared I S 2 is output from multiplier 7114S. The first and second input terminals of the multiplier 7114T are connected to the current detection value I T are input, and the product of these inputs, i.e., the current detection value I T Squared I T 2is output from multiplier 7114S.

[0077] The squared I output from multipliers 7114R, 7114S, and 7114T R 2 ,I S 2 ,I T 2 is input to adder 7115. Adder 7115 adds three squares of I R 2 ,I S 2 ,I T 2 The sum of (I R 2 +I S 2 +I T 2 ) is output. The output of adder 7115 (I R 2 +I S 2 +I T 2 ) is input to filter 7116. The filter 7116 is a summation (I R 2 +I S 2 +I T 2 ) and remove the AC component from the sum (I R 2 +I S 2 +I T 2 ) is the DC component of the squared current sum H C is output to the abnormality degree calculation unit 7117.

[0078] Current detection value I R ,I S The multiplier 7114CT receives the inputs I R I S Output. Current detection value I S ,I T The multiplier 7114CR receives these inputs and calculates their product I S I T Output. Current detection value I T ,I R The multiplier 7114CS receives these inputs and calculates their product I T I R Output. The product I output from the multipliers 7114CR, 7114CS, and 7114CT S I T ,I T I R ,I R I S are input to adder 7115C.

[0079] The adder 7115C generates the three products I S I T ,I T I R ,I R I S The sum of (I S I T +I T I R +I R I S ) is output. The output of adder 7115C (I S I T +I T I R +I R I S ) is input to filter 7116C. The filter 7116C is a summation (I S I T +I T I R +I R I S ) and remove the AC component from the sum (I S I T +I T I R +I R I S ) is the DC component of the alternating current product sum K C is output to the abnormality determination unit 7117.

[0080] The abnormality degree calculation unit 7117 calculates the sum of the products of various input currents (F R ,F S ,F T ,H C,K C ) and determines whether or not there is an abnormality in the current detectors 26, 27, 28. Details of the comprehensive determination of abnormality by the abnormality degree calculation unit 7117 correspond to the comprehensive determination of abnormality by the abnormality degree calculation unit 7217 provided in the inverter-side AC current detector abnormality determination unit 721, which will be described later, and therefore this description also applies to the comprehensive determination of abnormality by the abnormality degree calculation unit 7217.

[0081] Inverter-Side AC Current Detector Abnormality Determination Unit 721 FIG. 6 is a block diagram showing details of an example of inverter-side AC current detector abnormality determination unit 721 in FIG. 3B. 6, inverter-side AC current detector abnormality determination unit 721 includes an adder 7211 (first addition unit), multipliers 7212U, 7212V, and 7212W (first multiplication units), and filters 7213U, 7213V, and 7213W (first filters). Moreover, the inverter-side AC current detector abnormality determination unit 721 includes multipliers 7214U, 7214V, and 7214W (third multiplication units), an adder 7215 (third addition unit), and a filter 7216 (third filter). In addition, the inverter side AC current detector abnormality determination unit 721 includes multipliers 7214CU, 7214CV, 7214CW (second multiplication unit), an adder 7215C (second addition unit), a filter 7216C (second filter), and an abnormality degree calculation unit 7217.

[0082] The current detection value I detected by the U-phase current detector 34 U are input to the adder 7211 and the multipliers 7212U, 7214U, 7214CV, and 7214CW, respectively. The current detection value I detected by the V-phase current detector 35 V are input to the adder 7211 and the multipliers 7212V, 7214V, 7214CW, and 7214CU, respectively. The current detection value I detected by the W-phase current detector 36 W are input to the adder 7211 and the multipliers 7212W, 7214W, 7214CU, and 7214CV, respectively.

[0083] The adder 7211 calculates the current detection value I U ,I V ,I W Sum of I I0 (=I U +I V +I W ) is calculated. The calculated sum I I0 are input to each of multipliers 7212U, 7212V, and 7212W. The multiplier 7212U multiplies the current detection value I U and Sum I I0 Product D U Calculate. The multiplier 7212V multiplies the current detection value I V and Sum I I0 Product D V Calculate. The multiplier 7212W multiplies the current detection value I W and Sum I I0 Product D W Calculate. The product D output from the multipliers 7212U, 7212V, and 7212W U ,D V ,D W are input to the filters 7213U, 7213V, and 7213W of the corresponding phases, respectively.

[0084] The filter 7213U is a product D U By reducing or eliminating the AC component from the DC current product F U It should be noted that the filters 7213U, 7213V, 7213W, 7216, and 7216C in the inverter-side AC current detector abnormality determination unit 721 reduce or remove AC components contained in the input signal, but hereinafter this will simply be referred to as "removing." The filter 7213V has a product D V By removing the AC component from V Output. The filter 7213W has a product D W By removing the AC component from W Output. DC current product F output from filters 7213U, 7213V, and 7213WU ,F V ,F W is input to the abnormality degree calculation unit 7217.

[0085] The first and second input terminals of the multiplier 7214U are connected to the current detection value I U are input, and the product of these inputs, i.e., the current detection value I U Squared I U 2 is output from multiplier 7214U. The first and second input terminals of the multiplier 7214V are connected to the current detection value I V are input, and the product of these inputs, i.e., the current detection value I V Squared I V 2 is output from multiplier 7214V. The first and second input terminals of the multiplier 7214W are connected to the current detection value I W are input, and the product of these inputs, i.e., the current detection value I W Squared I W 2 is output from multiplier 7214W.

[0086] The squared I output from multipliers 7214U, 7214V, and 7214W U 2 ,I V 2 ,I W 2 are input to adder 7215. Adder 7215 adds three squares of I U 2 ,I V 2 ,I W 2 The sum of (I U 2 +I V 2 +I W 2 ) is output. The output of adder 7215 (I U 2 +I V 2 +I W2 ) is input to filter 7216. The filter 7216 is a summation (I U 2 +I V 2 +I W 2 ) and remove the AC component from the sum (I U 2 +I V 2 +I W 2 ) is the DC component of the squared current sum H I is output to the abnormality degree calculation unit 7217.

[0087] Current detection value I U ,I V The multiplier 7214CW, which receives the inputs I U I V Output. Current detection value I V ,I W The multiplier 7214CU, which receives inputs I V I W Output. Current detection value I W ,I U The multiplier 7214CV, which receives inputs I W I U Output. The product I output from multipliers 7214CU, 7214CV, and 7214CW V I W ,I W I U ,I U I V are input to adder 7215C.

[0088] The adder 7215C generates the three products I V I W ,I W I U ,I U I V The sum of (I V I W +I W I U +I U IV ) is output. The output of adder 7215C (I V I W +I W I U +I U I V ) is input to filter 7216C. The filter 7216C is a summation (I U I V +I V I W +I W I U ) and remove the AC component from the sum (I U I V +I V I W +I W I U ) is the DC component of the alternating current product sum K I is output to the abnormality degree calculation unit 7217.

[0089] The abnormality degree calculation unit 7217 calculates the input F U ,F V ,F W ,H I ,K I Based on this, it is determined whether or not there is an abnormality in the current detectors 34, 35, and 36. Details of the abnormality determination in the abnormality degree calculation unit 7217 will be described later.

[0090] <Details of the processes in converter-side AC current detector abnormality determination unit 711 and inverter-side AC current detector abnormality determination unit 721 in step S105> The processing of each component in converter-side AC current detector abnormality determination unit 711 and inverter-side AC current detector abnormality determination unit 721 shown in FIGS. 5 and 6 will be described in detail.

[0091] Current detection value I of current detectors 26, 27, and 28 on the converter side R ,I S ,I T and the true value of the current I RT ,I ST ,I TT The relationship between these can be expressed by the following equations (1) to (3).R , G S , G T represents the detection gain in the current detectors 26, 27, and 28. I R =I RT ×G R …(1) I S =I ST ×G S …(2) I T =I TT ×G T …(3)

[0092] Similarly, the current detection value I of the current detectors 34, 35, and 36 on the inverter side U ,I V ,I W and the true value of the current I UT ,I VT ,I WT The relationship between these can be expressed by the following equations (4) to (6). U ,G V ,G W represents the detection gain in the current detectors 34, 35, and 36. I U =I UT ×G U …(4) I V =I VT ×G V …(5) I W =I WT ×G W …(6)

[0093] In addition, the true value of the current actually flowing, I RT ,I ST ,I TT and I UT ,I VT ,I WT Regarding this, the following equations (7) and (8) hold true according to Kirchhoff's current law. I RT +I ST +I TT =0 …(7) I UT +I VT +I WT =0 …(8)

[0094] <<Explanation of various quantities related to current detectors 34, 35, and 36>> First, before describing the operation of the inverter-side abnormality determiner 72 to determine abnormality, various quantities relating to abnormalities in the current detectors 34, 35, and 36 will be described. The converter-side AC current detector abnormality judgment unit 711 shown in Fig. 5 and the inverter-side AC current detector abnormality judgment unit 721 shown in Fig. 6 have similar configurations. Therefore, in the following, detailed explanations of the processes in the AC current detector abnormality judgment units 711 and 721 will be given using the inverter-side AC current detector abnormality judgment unit 721 as a representative. Although not explained further, the relational expressions related to the converter-side AC current detector abnormality judgment unit 711 can be similarly explained by replacing the subscripts U, V, and W with R, S, and T in the relational expressions related to the inverter-side AC current detector abnormality judgment unit 721 described below.

[0095] Current true value I of U phase, V phase, and W phase UT ,I VT ,I WT For example, if the waveform of the true current is a sine wave and the amplitude of the true current is I IA When the phase difference between the sinusoidal waveforms of the true current values ​​of the phases is 2π / 3 (radians), it is expressed by the following equations (9) to (11). I UT =I IA ×cos(ωt) …(9) I VT =I IA ×cos(ωt-2π / 3) …(10) I WT =I IA ×cos(ωt-4π / 3) …(11) However, I IA is the current amplitude as mentioned above, t is time, and ω=2πf is the angular frequency (f is frequency).

[0096] Furthermore, from equations (4) to (6) and equations (9) to (11), the current detection values ​​I U ,I V ,IW is expressed by equations (12) to (14). I U =G U I IA ×cos(ωt) …(12) I V =G V I IA ×cos(ωt-2π / 3) …(13) I W =G W I IA ×cos(ωt-4π / 3) …(14)

[0097] When all of the current detectors 34, 35, and 36 are normal, the detection gain G U ,G V ,G W The value of is 1, and the detected values ​​I of the current detectors 34, 35, and 36 U ,I V ,I W and the true value I UT ,I VT ,I WT is equal to On the other hand, if the current detectors 34, 35, and 36 are abnormal (for example, if a detection gain abnormality occurs), the detected value I U ,I V ,I W and the true value I UT ,I VT ,I WT Therefore, the detection gain G U ,G V ,G W The value of will be other than 1 (for example, 0.9 or 1.1). Whether the current detectors 34, 35, and 36 are normal or abnormal depends on the detection gain G U ,G V ,G W It can be determined by the value of

[0098] <Absolute abnormality level A U ,A V ,A W Introduction of > Here, the absolute abnormality degree A is used as information indicating the absolute abnormality degree of the current detectors 34, 35, and 36. U ,A V,A W Introduce. [Definition] Absolute abnormality level A U ,A V ,A W is the detection gain G U ,G V ,G W are defined so that the following equations (15) to (17) hold. G U =1+A U …(15) G V =1+A V …(16) G W =1+A W …(17)

[0099] Absolute abnormality level A U ,A V ,A W If is 0, the corresponding detection gain G U ,G V ,G W becomes 1, which indicates that the current detectors 34, 35, and 36 are normal. On the other hand, absolute abnormality level A U ,A V ,A W If is a value other than 0, the corresponding detection gain G U ,G V ,G W becomes a value other than 1, which indicates that the current detectors 34, 35, and 36 are abnormal. Therefore, the absolute abnormality A U ,A V ,A W is information that indicates the degree of abnormality, with the further away from 0 these values ​​are, the greater the impact of the abnormality.

[0100] Absolute abnormality level A U ,A V ,A W Using the above equations (12) to (14), the current detection value I U ,I V ,I W is expressed by the following equations (18) to (20). I U =(1+AU )×I IA ×cos(ωt) …(18) I V =(1+A V )×I IA ×cos(ωt-2π / 3) …(19) I W =(1+A W )×I IA ×cos(ωt-4π / 3) …(20) Here, if the U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36 are all normal, G U =G V =G W =1, the following equation (21) holds. G U +G V +G W =3 …(21)

[0101] On the other hand, if one of the U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36 is abnormal, U ≠ 1 and G V =G W =1", "G V ≠ 1 and G U =G W =1" and "G W ≠ 1 and G U =G V = 1", so equation (21) does not hold and G U +G V +G W ≠3.

[0102] Furthermore, if two or three of the U-phase current detector 34, the V-phase current detector 35, and the W-phase current detector 36 are abnormal, U +G V +G W =3 or G U +G V +G W ≠ 3. Note that G U +G V +G W= 3 is true when the deviations from 1 in the detection gain of the abnormal current detector cancel each other out. If the deviations do not cancel each other out, G U +G V +G W ≠3.

[0103] <Relative detection gain G U0 ,G V0 ,G W0 Introduction of > Here, the relative detection gain G is set so that the sum of the gains is always 3. U0 ,G V0 ,G W0 and variable B I will be newly introduced. [Definition] Relative detection gain G U0 ,G V0 ,G W0 and variable B I is defined as a quantity that is set so that the following equations (22), (23) to (25) hold. G U0 +G V0 +G W0 =3 …(22) I U =G U0 B I ×cos(ωt) …(23) I V =G V0 B I ×cos(ωt-2π / 3) …(24) I W =G W0 B I ×cos(ωt-4π / 3) …(25)

[0104] Comparing equations (23) to (25) and equations (12) to (14), the detection gain G U ,G V ,G W and the relative detection gain G U0 ,G V0 ,G W0 The following equations (26) to (28) hold between G U0 B I =G U IIA …(26) G V0 B I =G V I IA …(27) G W0 B I =G W I IA …(28)

[0105] From equations (26) to (28) and equation (22), the variable B I is the detection gain G U ,G V ,G W , and the current amplitude I IA Using this, it is expressed by the following equation (29). B I =(G U +G V +G W )×I IA / (G U0 +G V0 +G W0 ) =(G U +G V +G W )×I IA / 3 …(29)

[0106] <Relative Anomaly A U0 ,A V0 ,A W0 Introduction of > Here, the relative abnormality degree A of the current detectors 34, 35, and 36 U0 ,A V0 ,A W0 Introduce. [Definition] Relative anomaly level A U0 ,A V0 ,A W0 is defined as a quantity that is set so that the following equations (30) to (32) hold. G U0 =1+A U0 …(30) G V0 =1+A V0 …(31) G W0 =1+A W0 …(32)

[0107] The above-mentioned relative anomaly degree A U0 ,A V0 ,A W0 Using this, the above-mentioned equations (23) to (25) can be expressed by the following equations (33) to (35). I U =(1+A U0 )×B I ×cos(ωt) …(33) I V =(1+A V0 )×B I ×cos(ωt-2π / 3) …(34) I W =(1+A W0 )×B I ×cos(ωt-4π / 3) …(35) Furthermore, from equation (22) and equations (30) to (32), the relative abnormality degree A U0 ,A V0 ,A W0 The following equation (36) holds for the sum of A U0 +A V0 +A W0 =0 …(36) Therefore, the relative anomaly A U0 ,A V0 ,A W0 is the absolute abnormality level A, which indicates the degree of abnormality. U , A V , A W is normalized so that equation (36) holds.

[0108] On the other hand, absolute abnormality level A U ,A V ,A W Regarding the current detectors 34, 35, and 36, if all of them are normal (G U =G V =G W =1) is obtained from equations (15) to (17) and (21) as follows: A U +A V +A W = 0, but if one or more of the current detectors 34, 35, and 36 are abnormal, A U +A V +AW =0 or A U +A V +A W ≠0.

[0109] <Operation of inverter-side AC current detector abnormality determination unit 721> As described above, converter-side AC current detector abnormality judgment unit 711 shown in Fig. 5 and inverter-side AC current detector abnormality judgment unit 721 shown in Fig. 6 have similar configurations. Therefore, the operations of converter-side AC current detector abnormality judgment unit 711 and inverter-side AC current detector abnormality judgment unit 721 will be described using inverter-side AC current detector abnormality judgment unit 721 in Fig. 6 as a representative. The following describes the operation of the inverter side AC current detector abnormality judgment unit 721, but by replacing the suffixes U, V, and W with R, S, and T, the operation of the converter side AC current detector abnormality judgment unit 711 can be similarly described.

[0110] When the currents shown in the above equations (9) to (11) are flowing, the respective outputs I I0 ,D U ,D V ,D W ,F U ,F V ,F W ,I U 2 +I V 2 +I W 2 ,H I ,I U I V +I V I W +I W I U and K. I This article explains: In the following description, it is assumed that the detected current values ​​in the above equations (12) to (14) do not contain a DC component (offset component). If the detected current value contains a DC component (offset component), for example, I U ,IV ,I W A filter (not shown) is used to remove or reduce the DC component contained in the detected current value I U ,I V ,I W Instead of I U ,I V ,I W Alternatively, the output of a filter (fourth filter) (not shown) that removes or reduces the DC component contained in the signal may be used.

[0111] First, the sum I output from the adder 7211 in Figure 6 I0 (=I U +I V +I W ) is expressed by the following equation (37). I I0 =I U +I V +I W = B I ×(A U0 ×cos(ωt)+A V0 ×cos(ωt-2π / 3) +A W0 ×cos(ωt-4π / 3)) …(37)

[0112] Output D of multipliers 7212U, 7212V, and 7212W U ,D V ,D W are expressed by the following equations (38) to (40). In the equations (38) to (40), the symbol √(X) represents X 1 / 2 The notation and meaning of the symbol √(X) are the same in other equations.

[0113] D U =(I U +I V +I W )×I U = 1 / 2 × B I 2 A U0 ×(1+A U0 )×(1+cos(2ωt)) -1 / 4×B I 2 AV0 ×(1+A U0 )×(1+cos(2ωt)-√(3)×sin(2ωt)) -1 / 4×B I 2 A W0 ×(1+A U0 )×(1+cos(2ωt)+√(3)×sin(2ωt)) …(38)

[0114] D V =(I U +I V +I W )×I V =-1 / 4×B I 2 A U0 ×(1+A V0 )×(1+cos(2ωt)-√(3)×sin(2ωt)) +1 / 2×B I 2 A V0 ×(1+A V0 )×(1+cos(2ωt-4π / 3)) -1 / 4×B I 2 A W0 ×(1+A V0 )×(1-2×cos(2ωt)) …(39)

[0115] D W =(I U +I V +I W )×I W =-1 / 4×B I 2 A U0 ×(1+A W0 )×(1+cos(2ωt)+√(3)×sin(2ωt)) -1 / 4×B I 2 A V0 ×(1+A W0 )×(1-2×cos(2ωt)) +1 / 2×B I 2 A W0 ×(1+A W0)×(1+cos(2ωt-8π / 3)) …(40)

[0116] The filters 7213U, 7213V, and 7213W are U , D V , D W Filtering is performed to remove the AC components contained in the U , D V , D W F, which is the DC component of U ,F V ,F W It should be noted that, from equations (38) to (40), in an ideal case where no pulsation is included, if the 2ω component, which is twice the fundamental frequency ω, can be removed, a DC component can be output. Therefore, the minimum performance required of filters 7213U, 7213V, and 7213W is to remove the 2ω component. D represented by equations (38) to (40) U , D V , D W When a filter process is performed to remove the AC component, that is, when the periodic change of the trigonometric function is removed, the output F of the filters 7213U, 7213V, and 7213W is U ,F V ,F W is expressed by the following equations (41) to (43).

[0117] F U = 1 / 4 × B I2 ×(2A U0 -A V0 -A W0 )×(1+A U0 ) …(41) F V = 1 / 4 × B I2 ×(2A V0 -A W0 -A U0 )×(1+A V0 ) …(42) F W = 1 / 4 × B I2 ×(2A W0 -A U0 -A V0 )×(1+A W0 ) …(43) Furthermore, by substituting the above-mentioned equation (36) into equations (41) to (43) and rearranging them, the output F of the filters 7213U, 7213V, and 7213W is obtained as follows: U ,F V ,F W is expressed by the following equations (44) to (46). F U =3 / 4×B I 2 A U0 ×(1+A U0 ) …(44) F V =3 / 4×B I 2 A V0 ×(1+A V0 ) …(45) F W =3 / 4×B I 2 A W0 ×(1+A W0 ) …(46)

[0118] The output of adder 7215 (I U 2 +I V 2 +I W 2 ) is expressed by the following equation (47). I U 2 +I V 2 +I W 2 =B I 2 ×(1+A U0 ) 2 ×(1+cos(2ωt)) / 2 +B I 2 ×(1+A V0 ) 2 ×(1+cos(2ωt-4π / 3)) / 2 +B I 2 ×(1+A W0 ) 2 ×(1+cos(2ωt-8π / 3)) / 2 …(47)

[0119] The filter 7216 receives the input I U 2 +I V 2 +I W 2 The AC components contained in these are filtered to be removed, and I U 2 +I V 2 +I W 2 H, which is the DC component of I Output. I represented by the above formula (47) U 2 +I V 2 +I W 2 When a filter process is performed to remove the AC component, that is, when the periodic change of the trigonometric function is removed, the output H of the filter 726 of the second system is I is expressed by the following equation (48): Note that the above equation (36) was used in the calculation process. H I =3 / 2×B I 2 +1 / 2×B I 2 ×(A U0 2 +A V0 2 +A W0 2 ) …(48)

[0120] The output of adder 7215C (I U I V +I V I W +I W I U ) is expressed by the following equation (49). I U I V +I V I W +I W I U =-1 / 4×B I 2 ×(1+A U0 )×(1+A V0)×(1+cos(2ωt)-√(3)×sin(2ωt)) -1 / 4×B I 2 ×(1+A V0 )×(1+A W0 )×(1+2×cos(2ωt)) -1 / 4×B I 2 ×(1+A W0 )×(1+A U0 )×(1+cos(2ωt)+√(3)×sin(2ωt)) …(49)

[0121] The filter 7216C is U I V +I V I W +I W I U The AC components contained in these are filtered to be removed, and I U I V +I V I W +I W I U K is the DC component of I Output. I represented by the above formula (49) U I V +I V I W +I W I U When a filter process is performed to remove the AC component, that is, the periodic change of the trigonometric function is removed, the output K of the filter 7216C is I is expressed by the following equation (50): Note that the above equation (36) was used in the calculation process. K I =-3 / 4×B I 2 -1 / 4×B I 2 ×(A U0 A V0 +A V0 A W0 +A W0 A U0 ) …(50)

[0122] <Processing in the abnormality degree calculation unit 7217> In the abnormality determination process in the abnormality degree calculation unit 7217 of the inverter-side AC current detector abnormality determination unit 721 shown in FIG. 6, the normalized abnormality degree calculation value A U0C0 ,A V0C0 ,A W0C0 is used. FIG. 7 is a block diagram for explaining various processes in the abnormality degree calculation unit 7217. The abnormality degree calculation unit 7217 calculates the normalized abnormality degree calculation value A U0C0 ,A V0C0 , AW0C0 The calculator 72171 to 72175 performs calculations related to the above. The abnormality degree calculation unit 7217 calculates the DC component F output from the filters 7213U, 7213V, 7213W, 7216, and 7216C. U ,F V ,F W ,H I ,K I Based on this, the normalized abnormality calculation value A U0C0 ,A V0C0 ,A W0C0 Calculate. Next, the equations (53), (57) to (59), and (61) to (63) expressed in the calculation units 72171 to 72175 will be explained.

[0123] 《Arithmetic unit 72171》 The aforementioned H I Equation (48) for K I By rearranging the equations (50) for each of the above using the above equation (36), the following equations (51) and (52) are obtained. 2×H I =3×B I 2 +2×B I 2 ×(A V0 2 +A W0 2 +A V0 A W0 ) …(51) 8×K I =-6×B I 2 +2×BI 2 ×(A V0 2 +A W0 2 +A V0 A W0 ) …(52) From equations (51) and (52), the relative anomaly degree A U0 ,A V0 ,A W0 Eliminating this gives the following equation (53). B I 2 =(2H I -8K I ) / 9 …(53) That is, the calculation unit 72171 calculates the DC component H I ,K I From equation (53), B I 2 Calculate.

[0124] 《Calculation section 72172~72174》 By rearranging the above equations (44) to (46), the relative anomaly degree A is obtained as shown in the following equations (54) to (56). U0 ,A V0 ,A W0 We obtain quadratic equations for 3B I 2 A U0 2 +3B I 2 A U0 -4F U =0 …(54) 3B I 2 A V0 2 +3B I 2 A V0 -4F V =0 …(55) 3B I 2 A W0 2 +3B I 2 A W0 -4F W=0 …(56)

[0125] Apply the quadratic equation formula to each of equations (54) to (56) and the solution obtained is A. U0C ,A V0C ,A W0C Then, A U0C ,A V0C ,A W0C is given by the following equations (57) to (59). A U0C =(-3B I 2 +√(9B I 4 +48B I 2 F U )) / (6B I 2 ) …(57) A V0C =(-3B I 2 +√(9B I 4 +48B I 2 F V )) / (6B I 2 ) …(58) A W0C =(-3B I 2 +√(9B I 4 +48B I 2 F W )) / (6B I 2 ) …(59) A calculated using equations (57) to (59) U0C ,A V0C ,A W0C (Relative anomaly A U0 ,A V0 ,A W0 Here, the calculated value of the abnormality degree is called the calculated abnormality degree value. As mentioned above (for example, equations (33) to (35)), it is assumed that the current is a sinusoidal current, so the calculated abnormality value A calculated by equations (57) to (59) U0C ,A V0C ,A W0Crepresents the degree of abnormality of the U, V, and W phases in an ideal state without current pulsation.

[0126] In FIG. 7, the calculation unit 72172 calculates the DC component F U and B calculated by the calculation unit 72171 I 2 Based on this, the abnormality degree calculation value A, which represents the degree of abnormality of the U phase, is calculated using equation (57). U0C Calculate. The calculation unit 72173 calculates the DC component F V and B I 2 Based on this, the abnormality degree calculation value A, which represents the degree of abnormality of the V phase, is calculated using equation (58). V0C Calculate. The calculation unit 72174 calculates the DC component F W and B I 2 Based on this, the abnormality degree calculation value A, which represents the degree of abnormality of the W phase, is calculated using equation (59). W0C Calculate.

[0127] In the formula for solving a quadratic equation, the sign immediately before √ can be positive or negative, but in equations (57) to (59) it is positive. For example, if the abnormality level is zero, the right side of equation (57) must be zero. If the abnormality level is zero, F calculated by equation (44) U If the sign immediately before the square root in equation (57) is negative, then the numerator on the right side of equation (57) will be F U If you substitute =0, (-3B I 2 -√(9B I 4 )), and the right-hand side of equation (57) does not become zero. On the other hand, if the sign immediately before the √ in equation (57) is positive, then the numerator of the right-hand side of equation (57) will contain F U If you substitute =0, (-3B I 2 +√(9B I 4 )), and the right-hand side of equation (57) becomes zero.

[0128] <When a layer short occurs and three-phase current becomes unbalanced> The inverter-side AC current detector abnormality determination unit 721 calculates the abnormality and the degree of abnormality of the current detectors 34, 35, and 36 on the assumption that the three-phase currents are balanced. Therefore, for example, if damage progresses to the coating of the stator winding of an electric motor, which is a three-phase load, and a layer short occurs, a large amount of current will flow to the phase where the layer short occurred, which has a smaller load, causing an imbalance in the three-phase current. As a result, the amplitudes of the true current values ​​in the above equations (9) to (11) do not match for each phase, and the phase differences of each phase in the equations (9) to (11) also become values ​​other than 2π / 3 (radians).

[0129] However, when the AC current detector is normal and a three-phase imbalance occurs, the output of adder 7211 becomes 0 when inverter-side AC current detector abnormality determination unit 721 shown in FIG. 6 is used. Therefore, the output F of the filters 7213U, 7213V, and 7213W U ,F V ,F W becomes 0, and A calculated by equations (57) to (59) U0C ,A V0C ,A W0C also becomes 0. That is, even if the amplitudes of the true current values ​​of the respective phases do not match, the current detector (AC current detector) is not erroneously diagnosed as being abnormal.

[0130] Furthermore, even when both an abnormality in the AC current detector and three-phase imbalance occur simultaneously, the configuration of the inverter side AC current detector abnormality judgment unit 721 in Figure 6, which includes the adder 7211, multipliers 7212U, 7212V, 7212W, and filters 7213U, 7213V, 7213W, reduces the error resulting from three-phase imbalance included in the degree of current detector abnormality calculated by equations (57) to (59). Therefore, even if the assumptions in the above formulas (9) to (11) are incorrect, the configuration shown in FIG. 6 can detect the degree of abnormality with a small error.

[0131] 《Arithmetic unit 72175》 The abnormality degree calculation value A, which is an input signal of the calculation unit 72175 (first calculation unit) shown in FIG. U0C ,A V0C ,A W0C represents the degree of abnormality of the U, V, and W phases in an ideal state where there is no current pulsation. Therefore, if the current waveform does not contain a pulsating component, the calculated abnormality value A U0C ,A V0C ,A W0C The sum of these is the relative anomaly A U0 ,A V0 ,A W0 is zero as in the case of In other words, if the current waveform does not contain pulsating components, A U0C +A V0C +A W0C On the other hand, if the current waveform contains pulsating components, A U0C +A V0C +A W0C >0.

[0132] <Normalized anomaly calculation value A U0C0 ,AV 0C0 ,A W0C0 Introduction of > Therefore, the normalized anomaly calculation value A such that the following equation (60) holds true U0C0 ,A V0C0 ,A W0C0 will be newly introduced. [Definition] Normalized anomaly calculation value A U0C0 ,A V0C0 ,A W0C0 is defined as a quantity that is set so that the following equations (60) to (63) hold. A U0C0 +A V0C0 +A W0C0 =0 …(60) A U0C0 =A U0C -(A U0C +A V0C +A W0C ) / 3 …(61) A V0C0 =A V0C -(A U0C +A V0C +A W0C ) / 3 …(62) AW0C0 =A W0C -(A U0C +A V0C +A W0C ) / 3 …(63)

[0133] The second term on the right side of each of equations (61) to (63) is the calculated anomaly value A to satisfy equation (60). U0C ,A V0C ,A W0C It can be considered as a correction term for The current waveform contains pulsating components. U0C +A V0C +A W0C Even if the normalized anomaly calculation value A U0C0 ,A V0C0 ,A W0C0 If so, A U0C0 +AV 0C0 +A W0C0 =0 is true.

[0134] The calculation unit 72175 (first calculation unit) in FIG. 7 calculates the abnormality degree calculation value A U0C ,A V0C ,A W0C Based on this, the normalized anomaly calculation value A U0C0 ,A V0C0 ,A W0C0 Calculate.

[0135] In addition, when the current flowing through the current detector has a variable frequency due to reasons such as a variable operating frequency of the motor 4, it is desirable that the inverter-side AC current detector abnormality judgment unit 721 varies the time constant (or cutoff frequency) of the filter used in Figure 6 according to the operating frequency so that the AC component contained in the filter input can be largely removed even when the operating frequency of the motor 4 is low.

[0136] 1, a speed command is input from the speed command generator 61 to the inverter-side AC current detector abnormality determination unit 721 as information on the operating frequency (speed information). In addition, instead of the speed command, a speed detection value of the electric motor 4 detected by the speed detector 7 may be used. Alternatively, the time constant of the filter may be preset so as to significantly reduce the AC component contained in the filter input even during low-speed operation. Furthermore, when the operating frequency of the electric motor 4 is extremely low, the time constant of the filter becomes extremely large, so when the operating frequency of the electric motor 4 is low, the abnormality determination described below may not be performed.

[0137] <Abnormality Determination Processing in Inverter-Side AC Current Detector Abnormality Determination Unit 721> Fig. 8 is a flowchart showing an example of the abnormality determination process in the inverter-side AC current detector abnormality determination unit 721 shown in Fig. 6. The procedure of the abnormality determination process will be described below with reference to the flowchart in Fig. 8.

[0138] Step S1001 When the abnormality determination process in the inverter-side AC current detector abnormality determination unit 721 is initiated (started), the process proceeds to step S1001. In step S1001, the inverter side AC current detector abnormality determination unit 721 performs the calculation processing by the above-mentioned calculation units 72171 to 72175 to obtain the normalized abnormality degree calculation value A U0C0 ,A V0C0 ,A W0C0 Calculate.

[0139] Step S1002 Step S1002 is a step for determining whether or not all of the current detectors 34 to 36 are normal. In step S1002, the inverter-side AC current detector abnormality determination unit 721 calculates the calculated normalized abnormality degree A U0C0 ,A V0C0 ,A W0C0 Regarding |A U0C0 |,|A V0C0 |,|A W0C0 It is determined whether the maximum value among | is greater than a predetermined value α (for example, 3%).

[0140] That is, it is determined whether or not the formula (64) is satisfied. Note that MAX(a, b, c) represents the maximum value among the values ​​a, b, and c. MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |) > Predetermined value α …(64)

[0141] If it is determined in step S1002 that the formula (64) is true (Yes), the process proceeds from step S1002 to step S1003. On the other hand, if it is determined in step S1002 that the formula (64) does not hold (No), that is, |A U0C0 |,|A V0C0 |,|A W0C0 If all of | are equal to or smaller than the predetermined value α, the process proceeds from step S1002 to step S1011. The process of step S1011 will be described later.

[0142] Step S1003 In step S1003, the inverter-side AC current detector abnormality determination unit 721 determines whether or not the following equation (65) is established. ([MAX]-2×[MIN]) / [MAX] > Predetermined value β …(65) In equation (65), [MAX] is MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |), and [MIN] is MIN(|A U0C0 |,|A V0C0 |,|A W0C0 |). Note that MIN(a, b, c) represents the smallest value among the values ​​a, b, and c. The predetermined value β is a value set in advance (for example, 50%).

[0143] If it is determined in step S1003 that the formula (65) is true (Yes), the process proceeds from step S1003 to step S1004. On the other hand, if it is determined that the formula (65) does not hold (No), the process proceeds from step S1003 to step S1005. As will be described in detail later, equation (65) is an equation used to determine whether only one of the three current detectors 34 to 36 is abnormal. If equation (65) is not true (No), only one is abnormal; if equation (65) is true (Yes), two or three are determined to be abnormal.

[0144] The predetermined values ​​α and β may be either constant or variable. For example, in principle, when the current is 0, the degree of abnormality of the current detector cannot be seen, making it difficult to diagnose the abnormality. In order to avoid misjudgment when the current value is small, the detected current value I U ,I V ,I W The predetermined values ​​α and β may be made variable depending on the magnitude of the

[0145] Furthermore, the equation (65) in step S1003 is composed of three elements (A U0C0 ,A V0C0 ,A W0C0 ) can be classified into two elements with high similarity and one element with low similarity to those two elements. Equation (65) is an example of a determination method, and instead of using equation (65), a similar determination may be made using, for example, any clustering analysis method.

[0146] Step S1004 In step S1004, inverter-side AC current detector abnormality determination unit 721 determines that two or more of current detectors 34, 35, and 36 are abnormal. In step S1004, a command may be output to the display 73 to cause the display 73 to display information indicating that multiple current detectors are abnormal (for example, a message saying "Multiple current detectors abnormal"). When the processing in step S1004 is completed, the process proceeds to step S1012.

[0147] In addition, if the average value of the abnormality degrees of the multiple current detectors 34, 35, and 36 is 0, that is, the relative abnormality degree A U0 ,A V0 ,AW0 The average value of the calculated values ​​is 0 (i.e., (A U0C +A V0C +A W0C ) / 3=0), then, from equations (61) to (63), A U0C0 =A U0C , A U0C0 =A U0C , A U0C0 =A U0C is obtained. Therefore, the estimated abnormality value A of the current detector U1 ,A V1 ,A W1 is the calculated normalized anomaly value A U0C0 ,A V0C0 ,A W0C0 Using A U1 =A U0C0 ,A V1 =A V0C0 ,A W1 =A W0C0 It can be expressed as follows.

[0148] Or, relative anomaly A U0 ,A V0 ,A W0 The average of the calculated values ​​J(t) = (A U0C +A V0C +A W0C ) / 3, and the estimated abnormality value A of the current detector U1 ,A V1 ,A W1 can be expressed as the following formula: A U1 (t)=(A U0C0 (t)+1)×J(t)-1 A V1 (t)=(A V0C0 (t)+1)×J(t)-1 A W1 (t)=(A W0C0 (t)+1)×J(t)-1

[0149] However, in calculating the above J(t), for example, under the same operating conditions as in step S1005, a physical quantity B corresponding to the product of the average value of the detection gains of the plurality of current detectors and the current amplitude when all the current detectors are normal is used. I(t1) is stored in advance, and B in step S1004 I By comparing with (t), J(t)=B I (t) / B I (t1) It can be calculated as follows.

[0150] Step S1005 In step S1005, the inverter-side AC current detector abnormality determination unit 721 determines whether MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |) is |A U0C0 Determine whether it is equal to |. That is, it is determined whether the following equation (66) holds. MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |)=|A U0C0 | ...(66) If it is determined in step S1005 that the formula (66) is true (Yes), the process proceeds from step S1005 to step S1006. On the other hand, if it is determined that the formula (66) does not hold (No), the process proceeds from step S1005 to step S1007.

[0151] Step S1006 In step S1006, the inverter-side AC current detector abnormality determination unit 721 determines that the U-phase current detector 34 is abnormal. In step S1006, a command may be output to the display 73 to display information indicating that the U-phase current detector 34 is abnormal (for example, a message saying "U-phase current detector abnormal"). When the processing in step S1006 is completed, the process proceeds to step S1012.

[0152] The estimated value A of the degree of abnormality of the V-phase current detector 35 and the W-phase current detector 36 V1 ,A W1 A V1 =A W1 = 0, the estimated value A of the degree of abnormality of the U-phase current detector 34U1 can be calculated using the following equation (67). A U1 =(3×A U0C0 ) / (2-A U0C0 ) …(67)

[0153] Equation (67) can be estimated, for example, as follows: From the above-mentioned equations (26) and (29), the following equation (67a) is obtained. G U =G U0 ×(G U +G V +G W ) / 3 …(67a) Equation (67a) expresses the absolute anomaly A U ,A V ,A W and relative anomaly A U0 When expressed using the formula, the following formula (67b) is obtained. 1+A U =(1+A U0 )×(A U +A V +A W +3) / 3 …(67b)

[0154] Also, A V =A W = 0, the following equation (67c) is obtained: 1+A U =(1+A U0 )×(A U +3) / 3 A U =(3×A U0 ) / (2-A U0 ) …(67c) The relative anomaly A on the right side of equation (67c) U0 Instead of the normalized anomaly calculation value A U0C0 The absolute anomaly A U is the estimated value, the above equation (67) is obtained.

[0155] Step S1007 In step S1007, the inverter side AC current detector abnormality determination unit 721 determines whether |A U0C0 |,|AV0C0 |,|A W0C0 The largest of | is |A V0C0 |, that is, whether the following equation (68) holds. MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |)=|A V0C0 | ...(68) If it is determined in step S1007 that equation (68) holds (Yes), the process proceeds from step S1007 to step S1008. On the other hand, if it is determined that equation (68) does not hold (No), the process proceeds from step S1007 to step S1009.

[0156] Step S1008 In step S1008, the inverter-side AC current detector abnormality determination unit 721 determines that the V-phase current detector 35 is abnormal. In step S1008, a command may be output to the display 73 to cause the display 73 to display information indicating that the V-phase current detector 35 is abnormal (for example, a message saying "V-phase current detector abnormal"). When the processing of step S1008 is completed, the process proceeds to step S1012.

[0157] The estimated value A of the degree of abnormality of the U-phase current detector 34 and the W-phase current detector 36 U1 ,A W1 A U1 =A W1 = 0, the estimated value A of the degree of abnormality of the V-phase current detector 35 V1 can be calculated using the following equation (69): Equation (69) can be obtained in the same manner as in the case of equation (67) above. A V1 =(3×A V0C0 ) / (2-A V0C0 ) …(69)

[0158] Step S1009 In step S1009, the inverter side AC current detector abnormality determination unit 721 determines whether |A U0C0 |,|A V0C0 |,|AW0C0 The largest of | is |A W0C0 |, that is, whether the following equation (70) holds. MAX(|A U0C0 |,|A V0C0 |,|A W0C0 |)=|A W0C0 | ...(70) If it is determined in step S1009 that the formula (70) is true (Yes), the process proceeds from step S1009 to step S1010.

[0159] On the other hand, if it is determined that the formula (70) does not hold (No), the process proceeds from step S1009 to step S1011. However, from equations (66), (68), and (70), if equations (66) and (68) do not hold, equation (70) holds, and therefore step S1009 is Yes. Therefore, if the result of S1007 is No, the process may proceed to step S1010 without performing the process of step S1009.

[0160] <Step S1010> In step S1010, inverter-side AC current detector abnormality determination unit 721 determines that there is an abnormality in W-phase current detector 36. Also, in step S1010, a command may be output to display device 73 to display information indicating that there is an abnormality in W-phase current detector 36 (for example, "W-phase current detector abnormality"). When the processing of step S1010 is completed, the process proceeds to step S1012. The estimated value A of the degree of abnormality of the U-phase current detector 34 and the V-phase current detector 35 U1 ,A V1 A U1 =A V1 = 0, the estimated value A of the degree of abnormality of the W-phase current detector 36 W1 is expressed by the following equation (71): The equation (71) can be calculated in the same manner as in the case of the above equation (67). A W1 =(3×A W0C0 ) / (2-A W0C0 ) …(71)

[0161] Step S1011 In step S1011, inverter-side AC current detector abnormality determination unit 721 determines that all of the U-phase current detector 34, V-phase current detector 35, and W-phase current detector 36 are normal. Then, proceed to step S1012.

[0162] Step S1012 In step S1012, the next process is executed following steps S1004, S1006, S1008, S1010, and S1011. In step S1012, the abnormality determination unit 727 determines the estimated abnormality level of the current detector (for example, A U1 ,A V1 ,A W1 ) and current detector abnormality determination information (U-phase current detector abnormality determination information, V-phase current detector abnormality determination information, W-phase current detector abnormality determination information) to the inverter-side AC current estimation unit 722. Then, the series of abnormality determination processes is ended.

[0163] In the above flowchart, the operation and effect have been explained using the configuration of the inverter-side abnormality determiner 72 as an example, but the converter-side abnormality determiner 71 also produces substantially the same operation and effect.

[0164] <Another Method of Converter-Side AC Current Detector Abnormality Determination Unit 711 and Inverter-Side AC Current Detector Abnormality Determination Unit 721 in Step S105> As described above, it is desirable that the converter side AC current detector abnormality determination unit 711 and the inverter side AC current detector abnormality determination unit 721 use a determination method that utilizes Kirchhoff's current law. That is, according to Kirchhoff's current law, the sum of the true values ​​of the three-phase AC currents is 0, so if the sum of the detected values ​​of the AC current detector (output of adder 7211) is 0, the AC current detector is normal. Also, a method is desirable in which the AC current detector is diagnosed as abnormal if the output of adder 7211 is not 0.

[0165] For example, in FIG. 6, the abnormality of the current detectors 34, 35, and 36 may be determined based on the outputs of the current detectors 34, 35, and 36 and the adder 7211. First, when the output of adder 7211 exceeds a predetermined value, the phase of current detector 34, the phase of current detector 35, the phase of current detector 36, and the phase of the output of adder 7211 are calculated by, for example, Fourier transform.

[0166] Next, the phase difference between the phase of adder 7211 and current detector 34, the phase difference between the phase of adder 7211 and current detector 35, and the phase difference between the phase of adder 7211 and current detector 36 are calculated, and among these phase difference calculations, the one whose phase difference is closest to 0 (radians) or π (radians) is selected.

[0167] If the phase difference between the phase of the adder 7211 and the current detector 34 is closest to 0 (radian) or π (radian), the current detector 34 is diagnosed as abnormal. If the phase difference between the phase of the adder 7211 and the current detector 35 is closest to 0 (radian) or π (radian), the current detector 35 is diagnosed as abnormal. If the phase difference between the phase of the adder 7211 and the current detector 36 is closest to 0 (radian) or π (radian), the current detector 36 can be diagnosed as abnormal.

[0168] <First Example of Inverter-Side AC Current Estimation Unit 722 in Step S106> A first example of the inverter-side AC current estimating unit 722 in step S106 will be described with reference to FIG. Fig. 9 is a diagram showing an example of the configuration of the inverter-side AC current estimator 722 in the inverter-side abnormality determinator 72 in the power conversion device according to the first embodiment of the present invention. The inverter-side abnormality determinator 72 in Fig. 9 generally corresponds to the inverter-side abnormality determinator 72 in Fig. 3B.

[0169] 9, an inverter-side AC current estimation unit 722 estimates current detection values ​​I from a plurality of current detectors 34, 35, and 36 corresponding to the U-phase, V-phase, and W-phase of a three-phase AC. U ,I V ,I W Based on this, the current detection value that should be detected when the current detector showing an abnormality is normal is estimated. The method for estimating the actual current detection value in the inverter side AC current estimation unit 722 utilizes the relationship shown in the above equation (8), that is, the relationship that if each current detector is in a normal state, the combined current value obtained by adding the current detection values ​​of the inverter side current detectors 34, 35, and 36 is zero. Because this composite current value is zero, if one of the current detectors is abnormal, the accurate current detection value of the abnormal current detector can be estimated by subtracting the sum of the current detection values ​​of the two healthy current detectors from zero.

[0170] <Configuration Example of Inverter-Side AC Current Estimation Unit 722> Next, an example of a specific configuration and operation of the inverter-side AC current estimation unit 722 will be described. As described above, FIG. 9 is a block diagram showing an example of a partial configuration including the inverter-side AC current estimation unit 722, and shows the relationship between the inverter-side AC current estimation unit 722, the inverter-side AC current detector abnormality determination unit 721, and the inverter control device 6. 9, the inverter side AC current estimation unit 722 and the inverter side AC current detector abnormality determination unit 721 receive the current detection value I U ,I V ,I W is entered.

[0171] The inverter-side AC current detector abnormality determination unit 721 determines whether an abnormality has occurred in any of the current detectors 34, 35, and 36 based on the flowchart of FIG. When inverter-side AC current detector abnormality determination unit 721 determines that any of current detectors 34, 35, 36 is abnormal, it outputs abnormality information indicating the abnormal current detector to inverter-side AC current estimation unit 722. For example, if it is determined that the U-phase current detector 34 is abnormal, U-phase current detector abnormality determination information indicating that the U-phase current detector 34 is abnormal is output.

[0172] When the U-phase current detector abnormality determination information is input, the inverter side AC current estimation unit 722 estimates the current detection value I of the V-phase current detector 35. V and the current detection value I of the W-phase current detector 36 W The sum of these is subtracted from zero to obtain the estimated value I that is estimated to be detected when the U-phase current detector 34 is normal. UH Calculate. And the calculated estimate I UH is input to the selection unit 722 a of the inverter side AC current estimation unit 722 .

[0173] Current detection value I of U-phase current detector 34 U and estimate-I V -I W When the U-phase current detector abnormality determination information is input, the selection unit 722a receives the estimated value -I V -I W Select and output. Furthermore, when there is no input of U-phase current detector abnormality determination information, the selection unit 722a selects the current detection value I U Select and output. When the U-phase current detector abnormality determination information is input, the inverter side AC current estimation unit 722 calculates the current detection value I VH =I V ,I WH =I W and the estimated value I UH =-I V -I W is output to the inverter control device 6. On the other hand, if the U-phase current detector abnormality determination information is not input, the inverter side AC current estimation unit 722 calculates the current detection value I UH =I U ,IVH =I V ,I WH =I W is output to the inverter control device 6.

[0174] With this configuration, even if there is an abnormality in the U-phase current detector 34, the current detection value I U Instead, a suitable estimate I UH can be output. As a result, the current detection value I V ,I W and the estimated value I UH Based on this, for example, it is possible to perform "make do" by temporarily continuing the driving operation. If there is an abnormality in the V-phase current detector 35 or the W-phase current detector 36, the same processing operation is performed, and the current detection value I V Instead of I, we use a suitable estimate VH Or, the current detection value I W Instead of I, we use a suitable estimate WH will be output. In addition, the operation may be continued based on the current detection value of the current detector that is not determined to be abnormal and the current detection value estimated by the AC current estimation unit, or the operation may be continued based on multiple current detection values ​​estimated by the AC current estimation unit instead of the current detection value of the current detector.

[0175] <Configuration example of converter-side AC current estimation unit 712> The converter-side AC current estimation unit 712 may also be configured in the same manner as the inverter-side AC current estimation unit 722, except that the U phase, V phase, and W phase are replaced with the R phase, the S phase, and the T phase in the converter-side AC current estimation unit 712. The converter side AC current estimation unit 712 estimates the current detection values ​​I from the plurality of current detectors 26, 27, and 28 corresponding to the R phase, S phase, and T phase of the three-phase AC. R ,I S ,I T Based on this, the current detection value that should be detected when the current detector showing an abnormality is normal is estimated. The method for estimating the actual current detection value is the same as that used by inverter-side AC current estimator 722 .

[0176] <Second Example of Inverter-Side AC Current Estimation Unit 722 in Step S106> A second example of the inverter-side AC current estimating unit 722 in step S106 will be described with reference to FIG. FIG. 10 is a diagram showing a second configuration example of the inverter-side AC current estimator 722 in the inverter-side abnormality determiner 72 in the power conversion device according to the first embodiment of the present invention. In a second configuration example of the inverter-side AC current estimating section 722, the configuration of the inverter-side AC current estimating section 722 is replaced with the configuration shown in FIG.

[0177] Then, the estimated value of the degree of abnormality of each current detector is input as abnormality degree information output from the inverter-side AC current detector abnormality determination unit 721 to the inverter-side AC current estimation unit 722 . The estimated value of the abnormality degree is, for example, the estimated value A U1 ,A V1 ,A W1 is used. The inverter side AC current estimation unit 722 estimates the input current detection value I U ,I V ,I W and the estimate of absolute anomaly A U1 ,A V1 ,A W1 Based on this, the estimated value I of the AC current is calculated as the current detection value when the current detectors 34, 35, and 36 are assumed to be normal. UH ,I VH ,I WH is calculated using the following equations (72) to (74).

[0178] I UH =I U ×(1+A U1 ) …(72) I VH =I V ×(1+A V1 ) …(73) IWH =I W ×(1+A W1 ) …(74) Then, the inverter side AC current estimation unit 722 calculates the estimated AC current value I UH ,I VH ,I WH is output to the inverter control device 6.

[0179] The converter side AC current estimating unit 712 may be configured by replacing the U phase with the R phase, the V phase with the S phase, and the W phase with the T phase in the above description. That is, the converter side AC current estimation unit 712 estimates the input current detection value I R ,I S ,I T and the estimated anomaly value A R1 ,A S1 ,A T1 Based on this, the estimated value of AC current I RH ,I SH ,I TH Calculate the estimated value I RH ,I SH ,I TH is output to the converter control device 5.

[0180] <First Example of Inverter-Side AC Current Abnormality Determination Unit 723 in Steps S107 and S110> In steps S107 and S110 in FIG. 4, the inverter-side AC current abnormality determination unit 723 calculates the estimated AC current value I UH ,I VH ,I WH The phase difference is detected. In step S110, the signal is not switched in the inverter side AC current estimation unit 722 (FIG. 9). UH =I U ,I VH =I V ,I WH =I W is. The estimated AC current I UH ,I VH ,I WHis defined as the following equations (75) to (77) using the amplitude and phase difference.

[0181] I UH =I U0 ×cos(ωt) …(75) I VH =I V0 ×cos(ωt-θ UV ) …(76) I WH =I W0 ×cos(ωt-θ UV -θ VW ) …(77)

[0182] In the above equations (75) to (77), I U0 ,I V0 ,I W0 are the estimated AC current values ​​I UH ,I VH ,I WH is the current amplitude of θ UV I UH and I VH is the phase difference between VW I VH and I WH is the phase difference. I WH and I UH The phase difference is θ WU Then, θ UV ≒θ VW ≒θ WU ≈2π / 3, the following equation (78) holds. θ WU =2π-θ UV -θ VW …(78) Phase difference θ UV ,θ VW ,θ WU An example of a simple method for determining is described below.

[0183] FIG. 11 is a diagram showing an example of the configuration of the inverter-side AC current abnormality determination unit 723. As shown in FIG. FIG. 11 shows an example of a simple method for determining the phase difference. In Figure 11, the inverter side AC current abnormality judgment unit 723 is configured with multipliers 7231 (7231U, 7231V, 7231W), multipliers 7232 (7232CU, 7232CV, 7232CW), filters 7233 (7233U, 7233V, 7233W), filters 7234 (7234CU, 7234CV, 7234CW), and a phase difference calculation unit 7235.

[0184] Estimated AC current I UH ,I VH ,I WH When is defined as in the above equations (75) to (77), the outputs of the multipliers 7231U, 7231V, and 7131W are expressed by the following equations (79) to (81). I UH 2 =1 / 2×I U0 2 (1+cos(2ωt)) …(79) I VH 2 =1 / 2×I V0 2 (1+cos(2ωt-2θ UV )) …(80) I WH 2 =1 / 2×I W0 2 (1+cos(2ωt-2θ UV -2θ VW )) …(81)

[0185] I expressed by equations (79) to (81) UH 2 , I VH 2 , I WH 2 When a filter process is performed to remove high frequency components, that is, when the periodic changes of the trigonometric functions are removed, the output F of the filters 7233U, 7233V, and 7233W is UU ,F VV ,F WW is expressed by the following equations (82) to (84). F UU =1 / 2×I U0 2 …(82) FVV =1 / 2×I V0 2 …(83) F WW =1 / 2×I W0 2 …(84)

[0186] Also, the estimated AC current I UH ,I VH ,I WH When is defined as in the above-mentioned equations (75) to (77), the outputs of the multipliers 7232CU, 7232CV, and 7232CW are expressed by the following equations (85) to (87). I UH I VH =1 / 2×I U0 I V0 (cos(2ωt-θ UV ) +cos(θ UV )) …(85) I VH I WH =1 / 2×I V0 I W0 (cos(2ωt-2θ UV -θ VW ) +cos(θ UV )) …(86) I WH I UH =1 / 2×I W0 I U0 (cos(2ωt-θ UV -θ VW ) +cos(θ UV +θ VW )) …(87)

[0187] I expressed by equations (85) to (87) UH I VH , I VH I WH , I WH I UH When a filter process is performed to remove high frequency components, that is, when the periodic changes of the trigonometric functions are removed, the output F of the filters 7234CU, 7234CV, and 7234CW is UV ,F VW ,F WU is expressed by the following equations (88) to (90). F UV =1 / 2×I U0 I V0 ×cos(θ UV ) …(88) F VW =1 / 2×I V0 I W0 ×cos(θ VW ) …(89) F WU =1 / 2×I W0 I U0 ×cos(θ WU ) …(90)

[0188] Therefore, from equations (82) to (84) and equations (88) to (90), cos(θ UV ),cos(θ VW ),cos(θ WU ) is the output of the filters 7233 and 7234 and is expressed as in the following equations (91) to (93). cos(θ UV )= F UV / √(F UU ×F VV ) …(91) cos(θ VW )= F VW / √(F VV ×F WW ) …(92) cos(θ WU )= F WU / √(F WW ×F UU ) …(93)

[0189] The phase difference is expressed by the following equations (94) to (96). θ UV =acos(F UV / √(F UU ×F VV )) …(94) θ VW =acos(F VW / √(F VV ×F WW )) …(95) θ WU =acos(F WU / √(F WW ×F UU)) …(96)

[0190] As described above (for example, equations (75) to (77)), the estimated value I UH ,I VH ,I WH is assumed to be a sinusoidal current, the phase difference θ calculated by equations (94) to (96) UV ,θ VW ,θ WU represents the phase difference between the U phase, V phase, and W phase in an ideal state where there is no current pulsation. Estimated AC current I UH ,I VH ,I WH If pulsating components are included in θ, which is calculated from equations (94) to (96), UV ,θ VW ,θ WU θ is calculated using UV ,θ VW ,θ WU is θ UV +θ VW +θ WU ≠2π.

[0191] Therefore, the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 will be newly introduced. θ DIF =(θ UV +θ VW +θ WU -2π) / 3…(97) θ UV1 =θ UV -θ DIF …(98) θ VW1 =θ VW -θ DIF …(99) θ WU1 =θ WU -θ DIF …(100)

[0192] I UH +I VH +I WH If θ = 0, UV1 ,θ VW1,θ WU1 θ out of VW1 If is smallest, then I UH The amplitude of θ is the largest WU1 If is smallest, then I VH The amplitude of θ is the largest UV1 If is smallest, then I WH has the largest amplitude. Therefore, the phase difference θ UV1 ,θ VW1 ,θ WU1 By comparing these, it is possible to detect the phase in which a layer short circuit may have occurred, i.e., the phase in which the current amplitude is the largest.

[0193] <Abnormality Determination Processing in Inverter-Side AC Current Abnormality Determination Unit 723> Fig. 12 is a flowchart showing an example of the abnormality determination process in the inverter-side AC current abnormality determination unit 723 shown in Fig. 11. The procedure of the abnormality determination process will be described below with reference to the flowchart of Fig. 12.

[0194] Step S2001 When the abnormality determination process in the inverter-side AC current abnormality determination unit 723 is started, the process proceeds to step S2001. In step S2001, the inverter-side AC current abnormality determination unit 723 calculates the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 Calculate.

[0195] Step S2002 Step S2002 is a step for determining whether or not all currents are normal. The inverter-side AC current abnormality determination unit 723 determines whether or not the calculated normalized phase difference θ UV1 ,θ VW1 ,θ WU1 With respect to θ UV1 ,θ VW1 ,θ WU1 It is determined whether the minimum value within is smaller than a predetermined value γ1 (for example, 0.98×2π / 3). That is, it is determined whether or not the formula (101) is true. Note that MIN(a, b, c) represents the smallest value among the values ​​a, b, and c. MIN(θ UV1 ,θ VW1 ,θ WU1 ) < predetermined value γ1 …(101)

[0196] If it is determined in step S2002 that the formula (101) is true (Yes), the process proceeds from step S2002 to step S2003. On the other hand, if it is determined in step S2002 that the formula (101) does not hold (No), that is, the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 If all of these are equal to or greater than the predetermined value γ1, the process proceeds from step S2002 to step S2009. The processing in step S2009 will be described later.

[0197] Step S2003 In step S2003, the inverter-side AC current abnormality determination unit 723 calculates the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 In this case, MIN(θ UV1 ,θ VW1 ,θ WU1 ) is θ VW1 Determine whether it is equal to That is, it is determined whether the following equation (102) holds. MIN(θ UV1 ,θ VW1 ,θ WU1 )=θ VW1 …(102) If it is determined in step S2003 that the formula (102) is true (Yes), the process proceeds from step S2003 to step S2004. On the other hand, if it is determined that the formula (102) does not hold (No), the process proceeds from step S2003 to step S2005.

[0198] Step S2004 In step S2004, the inverter-side AC current abnormality determination unit 723 determines that the U-phase current is the maximum. In step S2004, a command may be output to the display 73 to cause the display 73 to display information indicating that the U-phase current is at its maximum (for example, a display saying "U-phase current maximum"). In step S2004, since the U-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the U-phase circuit will progress. When the processing in step S2004 is completed, the process proceeds to step S2010.

[0199] "Step S2005" In step S2005, the inverter-side AC current abnormality determination unit 723 calculates MIN(θ UV1 ,θ VW1 ,θ WU1 ) is θ WU1 That is, it is determined whether the following equation (103) holds. MIN(θ UV1 ,θ VW1 ,θ WU1 )=θ WU1 …(103) If it is determined in step S2005 that the formula (103) is true (Yes), the process proceeds from step S2005 to step S2006. On the other hand, if it is determined that the formula (103) does not hold (No), the process proceeds from step S2005 to step S2007.

[0200] "Step S2006" In step S2006, the inverter-side AC current abnormality determination unit 723 determines that the V-phase current is the maximum. In step S2006, a command may be output to the display 73 to cause the display 73 to display information indicating that the V-phase current is at its maximum (for example, a message saying "V-phase current maximum"). In step S2006, since the V-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the V-phase circuit will progress. When the processing in step S2006 is completed, the process proceeds to step S2010.

[0201] "Step S2007" In step S2007, the inverter-side AC current abnormality determination unit 723 calculates MIN(θ UV1 ,θ VW1 ,θ WU1 ) is θ UV1 That is, it is determined whether the following equation (104) holds. MIN(θ UV1 ,θ VW1 ,θ WU1 )=θ UV1 …(104)

[0202] If it is determined in step S2007 that the formula (104) is true (Yes), the process proceeds from step S2007 to step S2008. On the other hand, if it is determined that the formula (104) does not hold (No), the process proceeds from step S2007 to step S2009. However, from equations (102), (103), and (104), if equations (102) and (103) do not hold, equation (104) holds, and so step S2007 becomes (Yes). Therefore, if S2005 is (No), the process may proceed to step S2008 without performing the process of step S2007.

[0203] "Step S2008" In step S2008, the inverter-side AC current abnormality determination unit 723 determines that the W-phase current is the maximum. In step S2008, a command may be output to the display 73 to cause the display 73 to display information indicating that the W-phase current is at its maximum (for example, a display saying "W-phase current maximum"). In step S2008, since the W-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the W-phase circuit will progress. When the processing in step S2008 is completed, the process proceeds to step S2010.

[0204] "Step S2009" In step S2009, inverter-side AC current abnormality determination unit 723 determines that the three-phase currents are balanced and normal.

[0205] "Step S2010" In step S2010, the next process is executed following steps S2004, S2006, S2008, and S2010. In step S2010, the inverter-side AC current abnormality determination unit 723 calculates the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 Current abnormality determination information (U-phase current maximum, V-phase current maximum, W-phase current maximum, three-phase current balance) is output to the display 73. Then, the series of abnormality determination processes ends.

[0206] Although the above description has been given of the effects of the inverter-side AC current abnormality determining unit 723, the converter-side AC current abnormality determining unit 713 also provides the same effects.

[0207] Furthermore, the inverter-side AC current abnormality judgment unit 723 and the converter-side AC current abnormality judgment unit 713 are represented as AC current abnormality judgment units (713, 723) as a common configuration, and the configuration of a power conversion device having an AC current abnormality judgment unit that operates according to the flowchart shown in FIG. 12 can be outlined as follows: That is, "the AC current abnormality determination unit in the power conversion device calculates a normalized phase difference of the AC current of a plurality of phases, and if the minimum value of the plurality of normalized phase differences is greater than a predetermined value, determines that the current of each phase is normal, and if the minimum value of the plurality of normalized phase differences is smaller than the predetermined value, compares the minimum value of the plurality of normalized phase differences with the normalized phase difference of each phase in order, and if the minimum value of the plurality of normalized phase differences is equal to the normalized phase difference of a predetermined phase, determines that the amplitude of the current of that phase is maximum and determines that there is a high risk of a layer short circuit occurring in that phase."

[0208] <Second Example of Inverter-Side AC Current Abnormality Determination Unit 723 in Steps S107 and S110> In steps S107 and S110 in FIG. 4, the inverter-side AC current abnormality determination unit 723 calculates the estimated AC current value I UH ,I VH ,I WH Instead of the phase difference, the amplitude may be detected. That is, the amplitude I U0 ,I V0 ,I W0 may be detected.

[0209] Figure 13 shows the amplitude (I U0 ,I V0 ,I W0 Here is an example of a simple method for finding FIG. 13 is a diagram showing another example of the configuration of the inverter-side AC current abnormality determination unit 723. In FIG. 13, inverter-side AC current abnormality determination unit 723 includes multipliers 7231 (7231U, 7231V, 7231W), filters 7233 (7233U, 7233V, 7233W), and an amplitude calculation unit 7236. That is, the multipliers 7232 (7232CU, 7232CV, 7232CW) and filters 7234 (7234CU, 7234CV, 7234CW) in FIG. 11 are removed.

[0210] Estimated AC current I UH ,I VH ,I WH When is defined as in the above equations (75) to (77), from the above equations (82) to (84), the amplitude I U0 ,I V0 ,I W0 The estimated value of I U1 ,I V1 ,I W1 is expressed by equations (105) to (107). I U1 =√(2F UU ) …(105) I V1 =√(2F VV ) …(106) I W1 =√(2F WW ) …(107) Amplitude estimate (Amplitude estimate) I U1 ,I V1 ,I W1 I U1 If is maximum, I UH has the largest amplitude, and I V1 If is maximum, I VH has the largest amplitude, and I W1 If is maximum, I WH has the largest amplitude. Therefore, the estimated amplitude I U1 ,I V1 ,I W1 By comparing these, it is possible to detect the phase in which the current amplitude is the largest and in which a layer short circuit may have occurred.

[0211] <Abnormality Determination Processing in Inverter-Side AC Current Abnormality Determination Unit 723> Fig. 14 is a flowchart showing an example of the abnormality determination process in the inverter-side AC current detector abnormality determination unit 723 shown in Fig. 13. The procedure of the abnormality determination process will be described below with reference to the flowchart of Fig. 14.

[0212] Step S3001 When the abnormality determination process in inverter-side AC current abnormality determination unit 723 is started, the process proceeds to step S3001. In step S3001, the inverter-side AC current abnormality determination unit 723 calculates the amplitude estimation value I U1 ,I V1 ,I W1 Calculate.

[0213] <Step S3002> Step S3002 is a step for determining whether all currents are normal or not. The inverter-side AC current abnormality determination unit 723 determines whether the calculated amplitude estimated value I U1 ,I V1 ,I W1 Regarding I U1 ,I V1 ,IW1 The maximum value within the range is a predetermined value γ2 (for example, 1.05 × (I U1 +I V1 +I W1 ) / 3). That is, it is determined whether or not the following formula (108) holds: Note that MAX(a, b, c) represents the maximum value among the values ​​a, b, and c. MAX(I U1 ,I V1 ,I W1 ) > Predetermined value γ1…(108)

[0214] If it is determined in step S3002 that the formula (108) is true (Yes), the process proceeds from step S3002 to step S3003. On the other hand, if it is determined in step S3002 that the equation (108) does not hold (No), that is, the amplitude estimation value I U1 ,I V1 ,I W1 If all of these are equal to or less than the predetermined value γ2, the process proceeds from step S3002 to step S3009. The processing in step S3009 will be described later.

[0215] <Step S3003> In step S3003, the inverter-side AC current abnormality determination unit 723 calculates MAX(I U1 ,I V1 ,I W1 ) but I U1 That is, it is determined whether or not the formula (102) holds. MAX(I U1 ,I V1 ,I W1 )=I U1 …(109) If it is determined in step S3003 that the formula (109) is true (Yes), the process proceeds from step S3003 to step S3004. On the other hand, if it is determined that the formula (109) does not hold (No), the process proceeds from step S3003 to step S3005.

[0216] <Step S3004> In step S3004, the inverter-side AC current abnormality determination unit 723 determines that the U-phase current is the maximum. In step S3004, a command may be output to the display 73 to cause the display 73 to display information indicating that the U-phase current is at its maximum (for example, a display saying "U-phase current maximum"). In step S3004, since the U-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the U-phase circuit will progress. When the processing in step S3004 is completed, the process proceeds to step S3010.

[0217] <Step S3005> In step S3005, the inverter-side AC current abnormality determination unit 723 calculates MAX(I U1 ,I V1 ,I W1 ) but I V1 That is, it is determined whether or not the formula (103) holds. MAX(I U1 ,I V1 ,I W1 )=I V1 …(110) If it is determined in step S3005 that the formula (110) is true (Yes), the process proceeds from step S3005 to step S3006. On the other hand, if it is determined that the formula (110) does not hold (No), the process proceeds from step S3005 to step S3007.

[0218] <Step S3006> In step S3006, the inverter-side AC current abnormality determination unit 723 determines that the V-phase current is the maximum. In step S3006, a command may be output to the display 73 to cause the display 73 to display information indicating that the V-phase current is at its maximum (for example, a display saying "V-phase current maximum"). In step S3006, since the V-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the V-phase circuit will progress. When the processing in step S3006 is completed, the process proceeds to step S3010.

[0219] <Step S3007> In step S3007, the inverter-side AC current abnormality determination unit 723 calculates MAX(I U1 ,I V1 ,I W1 ) but I W1 That is, it is determined whether or not the formula (111) holds. MAX(I U1 ,I V1 ,I W1 )=I W1 …(111)

[0220] If it is determined in step S3007 that the formula (104) is true (Yes), the process proceeds from step S3007 to step S3008. On the other hand, if it is determined that equation (111) does not hold (No), the process proceeds from step S3007 to step S3009. However, from equations (109), (110), and (111), if equations (109) and (110) do not hold, equation (111) holds, and so step S3007 results in Yes. Therefore, if S3005 is No, the process may proceed to step S3008 without performing the processing of step S3007.

[0221] <Step S3008> In step S3008, the inverter-side AC current abnormality determination unit 723 determines that the W-phase current is the maximum. In step S3008, a command may be output to the display 73 to cause the display 73 to display information indicating that the W-phase current is at its maximum (for example, a display saying "W-phase current maximum"). In step S3008, since the W-phase current is at its maximum, it may be determined that there is a possibility that a layer short circuit in the W-phase circuit will progress. When the processing in step S3008 is completed, the process proceeds to step S3010.

[0222] <Step S3009> In step S3009, inverter-side AC current abnormality determination unit 723 determines that the three-phase currents are balanced and normal.

[0223] <Step S3010> In step S3010, the next process is executed following steps S3004, S3006, S3008, and S3010. In step S3010, the inverter-side AC current abnormality determination unit 723 calculates the amplitude estimated value I U1 ,I V1 ,I W1 Current abnormality determination information (U-phase current maximum, V-phase current maximum, W-phase current maximum, three-phase current balance) is output to the display 73. Then, the series of abnormality determination processes is ended.

[0224] Although the above description has been given of the effects of the inverter-side AC current abnormality determining unit 723, the converter-side AC current abnormality determining unit 713 also provides the same effects.

[0225] The above steps S3001 to S3010 are a "second example of the inverter-side AC current abnormality determination unit 723 in steps S107 and S110 in FIG. 4," and in steps S107 and S110 in FIG. 4, the AC current abnormality determination unit 723 determines the estimated AC current value I UH ,I VH ,I WH 10 is a flowchart for the case where the amplitude is detected instead of the phase difference.

[0226] Furthermore, the inverter-side AC current abnormality judgment unit 723 and the converter-side AC current abnormality judgment unit 713 are represented as AC current abnormality judgment units (713, 723) as a common configuration, and the configuration of a power conversion device having an AC current abnormality judgment unit that operates according to the flowchart shown in FIG. 14 can be outlined as follows: That is, "the AC current abnormality determination unit in the power conversion device detects the amplitudes of the AC currents of a plurality of phases, calculates an amplitude estimation value for each phase from the detected amplitudes, and determines that the current of each phase is normal if the maximum value of the plurality of amplitude estimation values ​​is smaller than or equal to a predetermined value; if the maximum value of the plurality of amplitude estimation values ​​is larger than the predetermined value, compares the maximum value of the plurality of amplitude estimation values ​​with the amplitude estimation value of each phase in turn; if the maximum value of the plurality of amplitude estimation values ​​is equal to the amplitude estimation value of a predetermined phase, determines that the amplitude of the current of that phase is at its maximum, and determines that there is a possibility that a layer short circuit of that phase will progress."

[0227] <Other Implementation Methods for the Inverter-Side AC Current Anomaly Determination Unit 723 in Steps S107 and S110> In FIG. 11, the normalized phase difference θ UV1 ,θ VW1 ,θ WU1 Instead of calculating I UH ,I VH ,I WH is Fourier transformed with respect to frequency ω, and the phase difference estimate θ is calculated based on the Fourier transformed current phase components of each phase. UV ,θ VW ,θ WU may be calculated. Also, in Fig. 13, the amplitude estimate I U1 ,I V1 ,I W1 Instead of calculating the estimated AC current, I UH ,I VH ,I WH The effective current value may be calculated and used to determine whether an abnormality has occurred. Also, in Figure 13, the amplitude estimate I U1 ,I V1 ,I W1 Instead of calculating the estimated AC current I UH ,I VH ,I WH may be subjected to a Fourier transform to calculate the magnitude of the amplitude of each phase with respect to the frequency ω, and the magnitude of the amplitude of each phase may be used to determine whether an abnormality has occurred.

[0228] <Effects of the first embodiment> According to the present invention, it is possible to provide a power conversion device that can distinguish between an abnormality in a current detector and an AC current abnormality caused by something other than the current detector and detect the abnormality. Furthermore, even if a layer short occurs in an electric motor, which is a three-phase load, the current detector will not be mistakenly diagnosed as having an abnormality. Furthermore, even if an abnormality in the AC current detector and a three-phase imbalance occur simultaneously, the degree of abnormality can be detected with little error.

[0229] Second Embodiment: Power Conversion Device A power conversion device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 15 is a diagram showing an example of the configuration of a power conversion device 102 according to the second embodiment of the present invention. 15, the same components as those in the power conversion device 100 according to the first embodiment shown in Fig. 1 are denoted by the same reference numerals. In the power conversion device 101, the three-level converter unit 2 and inverter unit 3 in the power conversion device 100 shown in Fig. 1 are replaced with a two-level converter unit 2B and inverter unit 3B shown in Fig. 15.

[0230] 《2-level converter unit 2B》 In the power conversion device 101 of FIG. 15, the converter unit 2B and the inverter unit 3B are two levels, and therefore the circuits of each of the converter unit 2B and the inverter unit 3B are simplified. For example, the number of transistors is reduced, and the C wiring (41) of the neutral point (zero) potential in Fig. 1 is no longer necessary, leaving only the P wiring 40 of positive potential and the N wiring 42 of negative potential. Because there is no C wiring 41 in Fig. 1, the DC voltage detector that detects the DC voltage is composed of one DC voltage detector 29 that detects the potential between the electrodes of smoothing capacitors 22 and 23 on the converter side.

[0231] In FIG. 15, converter power conversion sections 21BR, 21BS, and 21BT in converter unit 2B are configured with two transistors each made up of an IGBT and two diodes. The two transistors are connected in series, with the collector of the first transistor connected to a P wiring 40 and the emitter of the second transistor connected to an N wiring 42. A diode is connected in antiparallel to each of the two transistors.

[0232] In Figure 15, converter power conversion unit 21B is shown as a representative of three converter power conversion units (21BR, 21BS, 21BT), but just as converter power conversion unit 21 (Figure 1) and inverter power conversion unit 31 (Figure 1) in power conversion device 100 of the first embodiment are actually composed of three converter power conversion units (21R, 21S, 21T) corresponding to the R phase, S phase, and T phase of three-phase AC, and three inverter power conversion units (31U, 31V, 31W) corresponding to the U phase, V phase, and W phase of three-phase AC, as shown in Figures 2A and 2B, converter power conversion unit 21B and inverter power conversion unit 31B in Figure 15 are shown in a simplified manner for three units.

[0233] Furthermore, the P wiring 40 and N wiring 42, which are DC power lines for the three converter power conversion units (21BR, 21BS, 21BT), are shared by the converter power conversion units (21BR, 21BS, 21BT). That is, the three-phase AC power (voltage) of the R phase, S phase, and T phase is converted into a single common DC power (voltage). The three converter power conversion units (21BR, 21BS, 21BT) are controlled in an integrated manner by a converter control device 5.

[0234] The converter unit 2B is provided with an R-phase current detector 26, an S-phase current detector 27, and a T-phase current detector 28, which detect currents flowing in the R-phase, S-phase, and T-phase of the three-phase AC, respectively. 15 are a direct representation of the smoothing capacitors 22 and 23 in the converter unit 2 shown in Fig. 1. However, since there is no C wiring 41 (neutral point potential), the smoothing capacitors 22 and 23 may be combined into a single capacitor. As shown in FIG. 15, when smoothing capacitor 22 and smoothing capacitor 23 are connected in series, the capacitance of the integrated capacitor decreases, but the withstand voltage across the integrated capacitor increases.

[0235] 《Two-level inverter unit 3B》 In Fig. 15, the inverter unit 3B is a two-level inverter unit that replaces the three-level inverter unit 3 in Fig. 1. The configuration of the two-level inverter unit 3B is a common modification and configuration to the two-level converter unit 2B in Fig. 15, so duplicated explanations will be omitted.

[0236] Power Conversion Device 101 In the power conversion device 101 shown in Figure 15, the configuration other than the converter unit 2B and the inverter unit 3B is generally the same as that of the power conversion device 100 of the first embodiment shown in Figure 1, so duplicated explanations will be omitted as appropriate.

[0237] As described above, the power conversion device 101 includes a two-level converter unit 2B and an inverter unit 3B. Although the current pulsation differs depending on whether the conversion method is 3-level or 2-level (pulse waveform), in the power conversion device 101, the converter-side abnormality judger 71 performs processing similar to that in the first embodiment based on the current detection values ​​of the current detectors 26, 27, and 28. It is then possible to appropriately determine whether or not there is an abnormality in the current detectors 26, 27, 28 or in the AC current (eg, AC power supply 1) caused by something other than the current detectors 26, 27, 28.

[0238] Furthermore, the inverter-side abnormality judger 72 performs processing similar to that in the first embodiment based on the current detection values ​​of the current detectors 34, 35, and 36, thereby making it possible to appropriately judge whether or not there is an abnormality in the current detectors 34, 35, and 36 or in the AC current (e.g., motor 4) caused by a source other than the current detectors 34, 35, and 36. Furthermore, as described above, in the second embodiment, even when the power conversion device 101 is equipped with a two-level converter unit 2B and an inverter unit 3B, it is possible to appropriately determine abnormalities in AC current caused by the current detectors 34, 35, 36 and by components other than the current detectors 34, 35, 36. Furthermore, by providing the converter unit 2B and the inverter unit 3B with two levels, the circuit configurations of the converter unit 2B and the inverter unit 3B can be simplified.

[0239] <Effects of the second embodiment> The power conversion device 101 of the second embodiment is configured to include a two-level converter unit 2B and an inverter unit 3B, which simplifies the circuit configuration and provides the effects of reducing costs and size.

[0240] <Supplementary Notes on the First and Second Embodiments> In the first and second embodiments described above, the abnormality determination of the current detector in the power conversion device interposed between the AC power supply 1 and the electric motor 4 as a load has been described. However, the present invention is not limited to such a configuration, and for example, an AC converter (e.g., a transformer) that converts AC into AC voltage may be provided between the AC power supply 1 and the converter unit 2. Alternatively, an AC converter (for example, a transformer) that converts AC voltage into AC voltage may be provided between the inverter unit 3 and the electric motor 4. The present invention can also be applied to current detectors arranged in all phases (e.g., three phases) between the power converter (converter unit 2) and the power source, or between the power converter (inverter unit 3) and the load (motor 4) in the above configuration, and to determining abnormalities in AC current caused by factors other than the current detectors.

[0241] <About abnormality detection in a configuration without a DC / AC power conversion device> In the first and second embodiments, the abnormality determination of the current detectors 26 to 28 and 34 to 36 that detect the currents of the respective phases of the three-phase AC wiring of the power converter has been described. However, the abnormality determination methods described in the first and second embodiments are not limited to application to current detectors provided in power conversion devices that convert direct current to alternating current. An example of abnormality determination in a configuration that does not include this DC / AC power conversion device will be described with reference to FIG.

[0242] FIG. 16 is a diagram showing an example of a configuration in which three-phase AC power from an AC power supply 1 is supplied to an electric motor 4, which is a three-phase load, via an AC-AC power converter 9. In FIG. 16, a U-phase current detector 34, a V-phase current detector 35, and a W-phase current detector 36 are provided on the three-phase AC wiring that is input to the electric motor 4. The AC-AC power converter 9 is controlled by an AC-AC power converter control device 8 . Current detection value I detected by current detectors 34, 35, and 36 U , I V , I W is input to the abnormality determiner 72. The abnormality determiner 72 is a device that determines whether there is an abnormality in the current detectors 34, 35, and 36, and has the same configuration and function as the inverter-side abnormality determiner 72 described in the first embodiment.

[0243] The electric motor 4 may be star-connected or delta-connected. Furthermore, in FIG. 16, the electric motor 4, which is a three-phase load, is shown as an example of the load, but the load is not limited to an electric motor. 1, 15 and 16 show the case of three-phase AC, but the invention is not limited to three phases and may be multi-phase other than three phases.

[0244] Third Embodiment An abnormality in the AC current detector is determined based on the abnormality probability calculation unit (7117 (FIG. 5) and 7217 (FIG. 6)) of the power conversion device in the first embodiment described above. In the third embodiment, a configuration and method for determining an abnormality in association with the operating conditions of the AC power supply or the load device (electric motor) will be described.

[0245] FIG. 17 is a diagram showing an example of the configuration of an AC current detector abnormality determination unit 731 of a power conversion device according to the third embodiment of the present invention. In FIG. 17, the AC current detector abnormality judgment unit (converter side AC current detector abnormality judgment unit 711, inverter side AC current detector abnormality judgment unit 721), which is a higher level than the abnormality degree calculation unit (7117, 7217) described in FIGS. 5 and 6, further takes into account the operating status of the AC power source 1 or the electric motor (load device) 4 to judge an abnormality in the current detector.

[0246] 17, AC current detector abnormality determination unit 731 includes converter side AC current detector abnormality determination unit 711 (FIGS. 17, 3A, 5), inverter side AC current detector abnormality determination unit 721 (FIGS. 17, 3B, 6), second calculation unit 7311, operating condition determination unit 7313 (including memory unit 7312), and abnormality determination unit 7315 (including third calculation unit 7314). As described above, operating condition determination unit 7313 includes internal memory unit 7312. Furthermore, abnormality determination unit 7315 includes internal third calculation unit 7314.

[0247] The AC current detector abnormality determination unit 731 receives the current detection values ​​I of the R phase, S phase, and T phase detected by the current detector on the converter unit 2 side. R ,I S ,I T Also, the current detection values ​​I of the U, V, and W phases detected by the current detector on the inverter unit 3 side are U ,I V ,I W is being entered. In addition, the operating condition S1 of the AC power supply 1 and the operating condition S2 of the load device (electric motor) 4 are input to the AC current detector abnormality determination unit 731. For convenience of notation, in Fig. 17, the operating conditions S1 and S2 are shown together on a single signal line.

[0248] In explaining the configuration, operation, and function of the AC current detector abnormality judgment unit 731 above, although there is some overlap with the converter side AC current detector abnormality judgment unit 711 and the inverter side AC current detector abnormality judgment unit 721, the configuration will be summarized and described again below.

[0249] <<Converter-Side AC Current Detector Abnormality Determination Unit 711>> The converter-side AC current detector abnormality determination unit 711 has been explained in the power conversion device 100 of the first embodiment, but since the explanation is extensive and some overlaps, it will be summarized below from the viewpoint of configuration and function. The converter-side AC current detector abnormality determination unit 711 is composed of <1A> to <10A> as follows.

[0250] <1A> Current detection values ​​(I R ,I S ,I T ) first summation I C0 A first addition unit 7111 calculates: <2A> First Sum I C0 and the current detection value (I R ,I S ,I T ) and the first product (D R ,D S ,D T ) for each of the multiple phases. <3A> Multiple first products (D R ,D S ,D T ) and a first filter (7113R, 7113S, 7113T) for reducing or removing the AC components contained in the <4A> The second product (I R I S,I S I T ,I T I R ) and the second multiplication unit (7114CT, 7114CR, 7114CS) respectively.

[0251] <5A> Multiple second products (I R I S ,I S I T ,I T I R A second adding unit 7115C that calculates a second sum for <6A> A second filter 7116C that reduces or removes AC components from the second summation. <7A> Current detection value squared (I R 2 ,I S 2 ,I T 2 ) for each phase. <8A> Multiple squares (I R 2 ,I S 2 ,I T 2 a third adding unit 7115 that calculates a third sum for <9A> A third filter 7116 that reduces or removes the AC component contained in the third summation.

[0252] <10A> Output of the first filter (7113R, 7113S, 7113T) (F R ,F S ,F T ), the output of the second filter 7116C (H C ) and the output of the third filter 7116 (K C ), and generates the abnormality degrees of the plurality of current detectors based on the output (F R ,F S ,F T ) and the output of the second filter 7116C (H C) and an abnormality degree calculation unit 7117 that calculates the degree of abnormality based on the calculated value and determines whether the current detector is abnormal based on the degree of abnormality.

[0253] Inverter-Side AC Current Detector Abnormality Determination Unit 721 The inverter-side AC current detector abnormality determination unit 721 has also been described in the power conversion device 100 of the first embodiment, but since the description is extensive and some overlapping, it will be summarized below from the viewpoint of configuration and function. The inverter-side AC current detector abnormality determination unit 721 is composed of <1B> to <10B> as follows.

[0254] <1B> Current detection values ​​(I U ,I V ,I W ) first summation I I0 A first addition unit 7211 calculates: <2B> First Sum I I0 and the current detection value (I U ,I V ,I W ) and the first product (D U ,D V ,D W ) for each of the multiple phases. <3B> Multiple first products (D U ,D V ,D W ) and a first filter (7213U, 7213V, 7213W) that reduces or removes the AC components contained in the <4B> The second product (I U I V ,I V I W ,I W I U The second multiplication unit (7214CW, 7214CU, 7214CV) calculates the respective

[0255] <5B> Multiple second products (I U I V ,I V IW ,I W I U A second adding unit 7215C that calculates a second sum for <6B> A second filter 7216C that reduces or removes AC components contained in the second summation. <7B> Square of the detected current value (I U 2 ,I V 2 ,I W 2 ) for each phase. <8B> Multiple squares (I U 2 ,I V 2 ,I W 2 a third adding unit 7215 that calculates a third sum for <9B> A third filter 7216 that reduces or removes AC components contained in the third summation.

[0256] <10B> Output of the first filter (7213U, 7213V, 7213W) (F U ,F V ,F W ), the output of the second filter 7216C (H I ) and the output of the third filter 7216 (K I ), and generates the abnormality degrees of the plurality of current detectors based on the output (F U ,F V ,F W ) and the output of the second filter 7216C (H I ) and an abnormality degree calculation unit 7217 that calculates the abnormality degree based on the above and determines whether the current detector is abnormal based on the abnormality degree.

[0257] <Supplementary Information Regarding Converter-Side AC Current Detector Abnormality Determination Unit 711 and Inverter-Side AC Current Detector Abnormality Determination Unit 721> As described above, the configurations <1A> to <10A> of the converter side AC current detector abnormality judgment unit 711 and the configurations <1B> to <10B> of the inverter side AC current detector abnormality judgment unit 721 have been explained. As can be seen from Figures 5 and 6, although there are differences in the input signals and output signals to each unit, the converter side AC current detector abnormality judgment unit 711 and the inverter side AC current detector abnormality judgment unit 721 have the same configuration. Therefore, the converter-side AC current detector abnormality determination unit 711 and the inverter-side AC current detector abnormality determination unit 721 may also be referred to as "AC current detector abnormality determination unit" as appropriate.

[0258] <<AC Current Detector Abnormality Determination Unit 731>> Referring again to FIG. 17, the AC current detector abnormality determination unit 731 will be described in its entirety. In FIG. 17, the output signals of the converter side AC current detector abnormality judgment unit 711 and the inverter side AC current detector abnormality judgment unit 721 are each represented by a single signal line, but in reality, multiple signals can be output during the calculation process.

[0259] For example, in the inverter side AC current detector abnormality determination unit 721, the detection gain (G U ,G V ,G W ) can be extracted as a signal. Similarly, the detection gain (G R ,G S ,G T ) can also be extracted as a signal. In addition, the inverter side AC current detector abnormality determination unit 721 determines the detection gain (G U ,G V ,G W ) and the current amplitude (I U ,I V ,I W Similarly, in the converter side AC current detector abnormality determination unit 711, the detection gain (GR ,G S ,G T ) and the current amplitude (I R ,I S ,I T ) and the signal (third product) can also be extracted.

[0260] In addition, in the inverter-side AC current detector abnormality determination unit 721, the second filter 7216C outputs a second product (I U I V ,I V I W ,I W I U ) is also available as an output signal from a second adder 7215C that calculates a second summation of I U 2 ,I V 2 ,I W 2 ) can also be extracted. Similarly, in the converter-side AC current detector abnormality determination unit 711, the second filter 7116C outputs a second product (I R I S ,I S I T ,I T I R ) is also available as an output signal from a second adder 7115C that calculates a second summation of I R 2 ,I S 2 ,I T 2 ) can also be extracted as an output signal from the third adder 7115.

[0261] In addition, in the inverter side AC current detector abnormality determination unit 721, as an output from the first filters (7213U, 7213V, 7213W), a first sum II0 and the current detection value (I U ,I V ,I W ) and the first product (D U ,D V ,D W ) for each of the multiple phases, the output signal of the first multiplication unit (7212U, 7212V, 7212W) can also be taken out. Similarly, in the converter side AC current detector abnormality determination unit 711, the first filters (7113R, 7113S, 7113T) output a first sum I in which the AC components are reduced or removed. C0 and the current detection value (I R ,I S ,I T ) and the first product (D R ,D S ,D T ) for each of the multiple phases, the output signal of the first multiplication unit (7112R, 7112S, 7112T) can also be taken out.

[0262] In FIG. 17, the second calculation unit 7311 receives the output (K C ) and the output from the third filter 7116 (H C ), (third sum (I R 2 ,I S 2 ,I T 2 )) are input. Then, second calculation unit 7311 calculates a physical quantity equivalent to the product of the average value of the detection gains of the multiple current detectors and the current amplitude, based on the output of second filter 7116C on the converter side and the output of the third filter.

[0263] 17 receives the output (K I ) and the output from the third filter 7216 (H I ), (third sum (I U 2 ,I V2 ,I W 2 )) are input. Then, second calculation unit 7311 calculates a physical quantity equivalent to the product of the average value of the detection gains of the multiple current detectors and the current amplitude, based on the output of second filter 7216C on the inverter side and the output of the third filter. In the second calculation unit 7311, calculations on the converter side and the inverter side are carried out separately and independently.

[0264] 17, the output signal of second calculation unit 7311 is input to storage unit 7312. The output signal of second calculation unit 7311 may be a calculation result on the converter side or a calculation result on the inverter side, and these are handled separately. Further, other input signals to the storage unit 7312 are a signal S1 and a signal S2. The signal S1 indicates the operating conditions on the AC power source 1 (FIG. 1) side, and the signal S2 indicates the operating conditions on the electric motor 4 (FIG. 1) side. In principle, when the calculation result on the converter side is input to the storage unit 7312, the signal S1 becomes valid, and when the calculation result on the inverter side is input, the signal S2 becomes valid. In the storage unit 7312, the third product of the average value of the detection gain and the current amplitude is stored in association with the operating conditions of the AC power supply 1 or the electric motor (load device) 4. The operating condition determination unit 7313, which is equipped with a memory unit 7312, determines the operating conditions of the AC power supply 1 or the electric motor (load device) 4 based on the stored information in the memory unit 7312, outputs an output signal of the operating conditions, and inputs it to the third calculation unit 7314.

[0265] The third calculation unit 7314 receives a signal from the operating condition determination unit 7313 (storage unit 7312). In addition, a third product (converter side, inverter side) of the average value of the detection gain and the current amplitude when multiple current detectors are normal is input from the converter side AC current detector abnormality judgment unit 711 and the inverter side AC current detector abnormality judgment unit 721. Furthermore, if necessary, the outputs from the first filters (7113R, 7113S, 7113T), (7213U, 7213V, 7213W), the second filter 7116C (K C ),7216C(K I ), the output from the third filter 7116 (H C ),7216(H I ) are input to the third calculation unit 7314. The third calculation unit 7314 calculates absolute abnormality degrees representing the absolute quantities of multiple degrees of abnormality based on the third product, the physical quantity calculated by the second calculation unit under the same operating conditions as the third product, the output of the first filter, the output of the second filter, and the output of the third filter.

[0266] An abnormality determination unit 7315 including a third calculation unit 7314 determines whether or not there is an abnormality in the plurality of current detectors based on the calculation results of the third calculation unit 7314.

[0267] <Effects of the third embodiment> In the power conversion device of the third embodiment, an operating condition judgment unit 7313 having a memory unit 7312 is provided, and the operating conditions of the AC power source 1 or the electric motor (load device) 4 are incorporated into the abnormality judgment, so that the abnormality of the current detector can be accurately judged in accordance with the actual situation.

[0268] Fourth Embodiment In the power conversion device of the first embodiment, as shown in FIG. 1, an example is shown in which current detectors (26, 27, 28, 34, 35, 36) are used on three-phase wiring to detect the current of the AC power supply 1 or the electric motor (load device) 4. In the power conversion device 103 of the fourth embodiment, a method of using a shunt resistor in the inverter power conversion unit for current detection will be described.

[0269] FIG. 18 is a diagram showing an example of the configuration of an inverter power conversion unit 31B of a power conversion device 103 according to the fourth embodiment of the present invention. 18, in inverter power conversion section 31B in inverter unit (3) of power conversion device 103, the configuration of the plurality of IGBTs and capacitors that constitute the inverter is the same as that in FIG. The difference is that shunt resistors 34B, 35B, and 36B for measuring AC current are provided on the N wiring 42 side of each inverter power conversion section (31U, 31V, 31W), respectively, forming a three-shunt circuit configuration that serves as a current detector.

[0270] When the inverter power conversion unit (31U, 31V, 31W) operates and AC current flows through each of the shunt resistors 34B, 35B, 36B, each of the shunt resistors 34B, 35B, 36B detects and measures the AC current of the U phase, V phase, and W phase of the three-phase AC, respectively. In this way, the arrangement of the current detector is not limited to between the inverter unit and the motor 4, which increases the degree of freedom in terms of the configuration and arrangement of the inverter unit. In addition, in some cases, a reduction in manufacturing costs can be expected. Moreover, shunt resistors 34B, 35B, and 36B may be provided on the P wiring 40 side to detect AC current. 2B and 1 except for the shunt resistors 34B, 35B, and 36B, and therefore a duplicated description will be omitted.

[0271] Furthermore, in FIG. 18, a configuration example is shown in which a shunt resistor is provided in the inverter power conversion section 31B, but the three converter power conversion sections (21R, 21S, 21T: FIG. 2A) of the converter unit 2 in FIG. 1 may also be provided with shunt resistor current detectors instead of the current detectors 26, 27, 28.

[0272] <Effects of the Fourth Embodiment> The use of shunt resistors (34B, 35B, 36B) has the effect of broadening the options for the installation location of the current measuring device (current detector), and in some cases, it is expected to reduce manufacturing costs.

[0273] Other Embodiments The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the above-described embodiments are merely examples for the purpose of explaining the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to those including all of the configurations described above. Furthermore, it is possible to replace part of the configuration of one embodiment with part of the configuration of another embodiment, and it is also possible to add, delete, or replace part or all of the configuration of another embodiment with the configuration of one embodiment.

[0274] <<Prevention and response to abnormalities caused by display on display 73>> As described above, in the first embodiment, the display (information presentation unit) 73 shown in FIG. 1 mainly displays judgment information regarding abnormalities based on the output signals of the converter-side abnormality judger 71 and the inverter-side abnormality judger 72. However, the information is not limited to the information on the determination of whether or not an abnormality is detected at the time of detection. For example, information on the degree of abnormality of the current detector and information on the phase difference may be displayed on the display 73. As a result, it is possible to grasp the signs of an abnormality in advance, and to prevent the occurrence of an abnormality or to prepare in advance for a response when an abnormality does occur.

[0275] Furthermore, the occurrence of an abnormality may be predicted as follows. The time-series data history of the abnormality degree is stored, and based on the stored history, the period from the present time until the abnormality degree exceeds a preset threshold value for abnormality determination (for example, a predetermined value α), i.e., the period until the occurrence of an abnormality, is predicted. The prediction result may then be displayed on the display 73. As a result, it is possible to detect signs of an abnormality in advance, and to prevent the occurrence of an abnormality or to prepare in advance for a response when an abnormality does occur.

[0276] <<Location of current detector and abnormality detector>> In the first embodiment, the converter-side abnormality determiner 71 determines whether the current detectors 26, 27, and 28 are abnormal, and the inverter-side abnormality determiner 72 determines whether the current detectors 34, 35, and 36 are abnormal. However, it is not essential to provide the detector on both the converter side and the inverter side as described above. Depending on the situation, the detector may be provided on either the converter side or the inverter side. Even in this case, the abnormality determination method described in the above embodiment can be applied.

[0277] Transistor In the above-described power conversion devices 100 to 103, the transistors constituting the converter power conversion section and the inverter power conversion section have been described as being IGBTs (Insulated Gate Bipolar Transistors). However, the transistor is not limited to an IGBT, and may be a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) or a superjunction MOSFET.

[0278] <<Number of power converter levels>> In the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 15, a three-level converter or a two-level converter is shown as an example. However, the number of levels of the level converter is not limited to 3 or 2. The abnormality detection process for the current detector in the present invention can also be applied to abnormality detection for current detectors arranged in all phases between the power converter and the power source or between the power converter and the load in any multi-level converter (for example, 5 levels or 7 levels).

[0279] Software and hardware processing The processing performed by the converter-side abnormality judger 71, inverter-side abnormality judger 72, converter-side AC current estimation unit 712, and inverter-side AC current estimation unit 722 is preferably performed by software in which a processor (not shown) executes a program stored in a memory. However, these configurations are not limited to software processing, and some or all of the processing may be performed by hardware circuits.

[0280] <<Conversion target of power conversion device>> In the first embodiment shown in FIG. 1, a power converter (converter unit 2) that converts AC to DC, or a power converter (inverter unit 3) that converts DC to AC is shown as an example, but the present invention is not limited to these. For example, an AC converter (eg, a transformer, AC-AC power converter) that converts AC to AC may be provided between the power source and the load. Alternatively, an AC converter (for example, a transformer) that converts AC voltage into AC voltage may be provided between the power source and the power converter (converter unit 2). Alternatively, an AC converter (for example, a transformer) that converts AC voltage into AC voltage may be provided between the power converter (inverter unit 3) and the load (electric motor 4). The present invention can also be applied to determining whether or not there is an abnormality in current detectors arranged in all phases (for example, three phases) between the power converter and the power source or between the power converter and the load in the above configuration.

[0281] <<Change filter settings>> 5 or 6, the first filter, second filter, and third filter are provided in the AC current detector abnormality determination unit (711, 721), but it is also effective to make it possible to change the filter settings of at least one of these filters, which has the effect of making it easier to respond to desired characteristics and environments. For example, as described above, when the current flowing through the current detector has a variable frequency due to reasons such as the variable operating frequency of the motor 4, it is desirable that the inverter-side AC current detector abnormality determination unit 721 varies the time constant (or cutoff frequency) of the filter used in FIG. 6 according to the operating frequency so that the AC component contained in the filter input can be largely removed even when the operating frequency of the motor 4 is low.

[0282] The Fourth Filter In Figure 5 or Figure 6, the first filter, second filter, and third filter are provided in the AC current detector abnormality judgment unit (711, 721), but there is also a method of further providing a fourth filter that removes or reduces the DC component contained in the current detection value for at least one of the multiple current detectors. This has the effect of making it easier to adapt to desired characteristics and environments. [Explanation of symbols]

[0283] 1 AC power supply 100, 101, 102, 103 Power conversion device 2 Converter unit (converter) 21, 21R, 21S, 21T Converter power conversion section 22, 23, 32, 33 Smoothing capacitor (capacitor) 26, 27, 28, 34, 35, 36 Current detector 3 Inverter unit (inverter) 31, 31B, 31U, 31V, 31W inverter power conversion section 34B, 35B, 36B Shunt resistor (current detector) 4 Electric motor (load device) 40P wiring (wiring) 41 C wiring (wiring) 42 N wiring (wiring) 5 Converter control device 51 DC voltage command generator 52 DC voltage controller 53 Current Controller 54 Pulse Generator 6 Inverter control device 61 Speed ​​command generator 62 Speed ​​Controller 63 Current Controller 64 Pulse Generator 71 Converter side abnormality judgement device (abnormality judgement device) 72 Inverter side abnormality judger (abnormality judger) 73 Display (information presentation section) 711 Converter side AC current detector abnormality judgment unit (AC current detector abnormality judgment unit) 712 Converter side AC current estimation unit (AC current estimation unit) 713 Converter side AC current abnormality judgment unit (AC current abnormality judgment unit) 721 Inverter side AC current detector abnormality judgment unit (AC current detector abnormality judgment unit) 722 inverter side AC current estimation unit (AC current estimation unit) 723 Inverter side AC current abnormality judgment unit (AC current abnormality judgment unit) 731 AC current detector abnormality judgment unit 7111, 7211 adder, first adder 7115C, 7215C adder, second adder 7115,7215 adder, third adder 7112R, 7112S, 7112T, 7212U, 7212V, 7212W Multiplier, First Multiplication Unit 7114CR, 7114CS, 7114CT, 7214CU, 7214CV, 7214CW Multiplier, Second Multiplication Unit 7114R, 7114S, 7114T, 7214U, 7214V, 7214W Multiplier, third multiplication unit 7113R, 7113S, 7113T, 7213U, 7213V, 7213W Filter, First Filter 7116C, 7216C filter, second filter 7116,7216 filters, third filter 7117,7217 Abnormality calculation part 72175 First Calculation Unit 7311 Second Calculation Unit 7312 Storage section 7313 Operation condition judgment unit 7314 Third Calculation Unit 7315 Abnormality judgment unit

Claims

1. A power conversion device including at least one of a converter that converts AC to DC, an inverter that converts DC to AC, or an AC converter that converts AC to AC, a plurality of current detectors that detect, for each phase, a plurality of phases of AC current flowing between an AC power source and the power conversion device or between the power conversion device and a load device; an abnormality determiner that determines whether an abnormality in a plurality of current detectors is present or whether an abnormality in AC current is due to a cause other than the current detectors; Equipped with The abnormality determiner an AC current detector abnormality determination unit that determines abnormality in current detection values ​​of multiple phases detected by the multiple current detectors; an AC current estimation unit that calculates a current estimation value of the current detector based on a determination result of the AC current detector abnormality determination unit; an AC current abnormality determination unit that determines abnormality in current detection values ​​of multiple phases detected by the multiple current detectors based on an output of the AC current estimation unit; Equipped with A power conversion device characterized by:

2. In claim 1, the abnormality determiner is composed of a converter-side abnormality determiner arranged on the AC power supply side and an inverter-side abnormality determiner arranged on the load device side, the AC current detector abnormality determination unit is composed of a converter-side AC current detector abnormality determination unit provided in the converter-side abnormality determiner, and an inverter-side AC current detector abnormality determination unit provided in the inverter-side abnormality determiner, the AC current estimation unit is composed of a converter-side AC current estimation unit provided in the converter-side abnormality determiner and an inverter-side AC current estimation unit provided in the inverter-side abnormality determiner, the AC current abnormality determination unit is composed of a converter-side AC current abnormality determination unit provided in the converter-side abnormality determiner, and an inverter-side AC current abnormality determination unit provided in the inverter-side abnormality determiner; A power conversion device characterized by:

3. In claim 1, The abnormality determiner the AC current detector abnormality determination unit determines whether or not there is an abnormality in the current detector, when the AC current detector abnormality determination unit detects an abnormality in the current detector, the output of the AC current estimation unit is switched to a predetermined estimated value, and after a predetermined time has elapsed, the AC current abnormality determination unit determines whether or not there is an AC current abnormality caused by something other than the current detector; When an abnormality is detected by the determination of the AC current abnormality determination unit, the AC current abnormality determination unit diagnoses that the AC current detector is abnormal and that the AC current is abnormal due to something other than the AC current detector, If the AC current abnormality determination unit does not detect an abnormality, it diagnoses that the AC current detector is abnormal and that the AC current caused by something other than the AC current detector is normal; When the AC current detector abnormality determination unit does not detect an abnormality in the current detector, the output of the AC current estimation unit is not switched, and the AC current abnormality determination unit determines that the abnormality is caused by something other than the AC current detector, When the AC current abnormality determination unit detects an abnormality in the AC current, it diagnoses that the AC current detector is normal and that the AC current abnormality is caused by something other than the AC current detector, If the AC current abnormality determination unit does not detect an abnormality in the AC current, it diagnoses that the AC current detector is normal and that the AC current caused by a factor other than the AC current detector is normal. A power conversion device characterized by:

4. In claim 1, The AC current detector abnormality determination unit a first adder that calculates a first sum of current detection values ​​of a plurality of phases detected by the plurality of current detectors; a first multiplication unit that calculates a first product, which is a product of the first sum and the current detection value, for each of the plurality of phases; a first filter that reduces or removes AC components included in each of the first products; a second multiplication unit that calculates second products that are products of the two current detection values ​​of different phases; a second adder that calculates a second sum of the second products; a second filter that reduces or removes AC components included in the second summation; a third multiplication unit that calculates the square of the current detection value for each phase; a third adder that calculates a third sum of squares of the plurality of current detection values; a third filter that reduces or removes AC components included in the third summation; an abnormality degree calculation unit that generates abnormality degrees for each of the plurality of current detectors based on the output of the first filter, the output of the second filter, and the output of the third filter, and determines whether the current detector is abnormal based on the abnormality degrees; Equipped with A power conversion device characterized by:

5. In claim 4, a first calculation unit that calculates a plurality of relative abnormality degrees based on an output of the first filter, an output of the second filter, and an output of the third filter, the relative abnormality degrees being set so that a sum of the relative abnormality degrees for a plurality of phases is always zero; The AC current detector abnormality determination unit determining that at least one of the current detectors is abnormal when the maximum value among the absolute values ​​of the plurality of relative abnormality degrees is greater than a preset abnormality determination threshold value; A power conversion device characterized by:

6. In claim 5, The AC current detector abnormality determination unit determining whether the plurality of relative abnormality degrees can be classified into two elements having a high degree of similarity and one element having a low degree of similarity to the two elements; If classification is possible, it is determined that only one of the plurality of current detectors is abnormal; If classification is not possible, it is determined that two or more of the current detectors are abnormal. A power conversion device characterized by:

7. In claim 4, a storage unit that stores a third product of an average value of detection gains and a current amplitude when the plurality of current detectors are normal, in association with an operating condition of the AC power supply or the load device; a second calculation unit that calculates a physical quantity corresponding to the product of an average value of detection gains of the plurality of current detectors and a current amplitude based on outputs of the second filter and the third filter; a third calculation unit that calculates absolute degrees of abnormality that represent absolute amounts of the plurality of degrees of abnormality based on the third product, the physical quantity calculated by the second calculation unit under the same operating conditions as the operating conditions, the output of the first filter, the output of the second filter, and the output of the third filter; and an abnormality determination unit that includes the third calculation unit and reflects the calculation result of the third calculation unit; Equipped with the abnormality determination unit determines abnormalities in the current detectors based on the absolute abnormality degrees. A power conversion device characterized by:

8. In claim 1, The AC current detector abnormality determination unit a first adder that calculates a first sum of current detection values ​​of a plurality of phases detected by the plurality of current detectors; determining whether the current detector has an abnormality based on the phase of the first sum and the phases of the current detection values ​​of the multiple phases detected by the multiple current detectors; A power conversion device characterized by:

9. In claim 1, when the AC current anomaly determination unit determines an anomaly in the current detector, the AC current estimation unit estimates a current detection value that would occur if the current detector determined to be abnormal were normal, based on a current detection value of the current detector that is not determined to be abnormal; continuing the operation based on the current detection value of the current detector that is not determined to be abnormal and the current detection value estimated by the AC current estimation unit; A power conversion device characterized by:

10. In claim 4, when the AC current anomaly determination unit determines an anomaly in the current detector, the AC current estimation unit estimates current detection values ​​that would be obtained if the current detector were normal, based on the relative anomaly degrees or absolute anomaly degrees of the current detectors and the current detection values ​​of the current detectors; continuing the operation based on a plurality of current detection values ​​estimated by the AC current estimation unit instead of the current detection value of the current detector; A power conversion device characterized by:

11. In claim 1, The AC current abnormality determination unit Calculating at least one of an effective value, an amplitude, or a phase difference of the output of the AC current estimation unit; comparing at least one of the effective value, the amplitude, or the phase difference with a predetermined value; determining whether the AC current is normal or abnormal due to causes other than the current detector; A power conversion device characterized by:

12. In claim 1, The AC current abnormality determination unit Calculating a normalized phase difference between the AC currents of the multiple phases; If the minimum value of the plurality of normalized phase differences is greater than a predetermined value, the current of each phase is determined to be normal; If the minimum value of the plurality of normalized phase differences is smaller than a predetermined value, the minimum value of the plurality of normalized phase differences is compared with the normalized phase difference of each phase in turn; If the minimum value of the plurality of normalized phase differences is equal to the normalized phase difference of a predetermined phase, it is determined that the amplitude of the current of the phase is maximum, and that the risk of occurrence of a layer short circuit or three-phase imbalance of the phase is high. A power conversion device characterized by:

13. In claim 1, The AC current abnormality determination unit Detecting amplitudes of AC currents of a plurality of phases and calculating amplitude estimates for each phase from the detected amplitudes; If the maximum value of the plurality of amplitude estimates is smaller than or equal to a predetermined value, the current of each phase is determined to be normal; If the maximum value of the plurality of amplitude estimation values ​​is greater than a predetermined value, the maximum value of the plurality of amplitude estimation values ​​is compared in order with the amplitude estimation value of each phase, and if the maximum value of the plurality of amplitude estimation values ​​is equal to the amplitude estimation value of a predetermined phase, it is determined that the amplitude of the current of that phase is maximum, and that there is a high risk of a layer short circuit or a three-phase imbalance occurring in that phase. A power conversion device characterized by:

14. In claim 4, changing a filter setting of at least one of the first filter, the second filter, and the third filter in accordance with a frequency of an AC current flowing through the plurality of current detectors; A power conversion device characterized by:

15. In claim 4, a fourth filter for removing or reducing a DC component included in the current detection value for at least one of the plurality of current detectors; an output of the fourth filter is used instead of the current detection value; A power conversion device characterized by:

16. In claim 1, an information presentation unit that presents abnormality information; The abnormality determiner Generate a history of multiple abnormality levels, predicting a period until an abnormality occurs in the current detector based on the history; causing the information presenting unit to present the prediction result as the abnormality information; A power conversion device characterized by:

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