Abnormality detection device and abnormality detection method for synchronous reluctance motor

Abstract

An abnormality detection device (40) is applied to a sensorless control device (100) that performs control to detect rotor position by superimposing a high frequency current on a synchronous reluctance motor (1). The abnormality detection device (40) includes a calculation unit (41) that calculates a physical quantity representing an abnormal state of a rotor (1b) of the synchronous reluctance motor (1) on the basis of the current value of the motor current flowing through the synchronous reluctance motor (1), and a determination unit (42) that determines whether the rotor (1b) is abnormal on the basis of the physical quantity. The abnormality detection device (40) holds a threshold value determined on the basis of a physical quantity when the rotor (1b) is normal. The determination unit (42) determines whether or not there is an abnormality in the rotor (1b) by comparing the physical quantity calculated by the calculation unit (41) with the threshold value.

Description

Synchronous reluctance motor abnormality detection device and abnormality detection method

[0001] The present disclosure relates to an abnormality detection device and an abnormality detection method for a synchronous reluctance motor that utilizes rotor saliency.

[0002] The mainstream synchronous motors in recent years are interior permanent magnet synchronous motors and synchronous reluctance motors. Interior permanent magnet synchronous motors are motors that use both magnet torque and reluctance torque, while synchronous reluctance motors are motors that use only reluctance torque. Because reluctance torque is proportional to the salient pole ratio, motors that use reluctance torque require a rotor structure that ensures a sufficient salient pole ratio.

[0003] In the case of a synchronous reluctance motor, to ensure sufficient centrifugal force strength while maintaining a sufficient salient pole ratio, the rotor is provided with a magnetic path through which magnetic flux passes, air slits that form a magnetic barrier, and strength members that support the air slits. In other words, in a synchronous reluctance motor, there is a trade-off between the salient pole ratio and centrifugal force strength. For this reason, synchronous reluctance motors are designed to maximize the salient pole ratio while ensuring sufficient centrifugal force strength. However, this design does not take into account failures due to aging or unexpected failures. Therefore, in order to further improve safety, it is desirable to monitor the rotor condition and detect rotor abnormalities early in synchronous reluctance motors.

[0004] The following Patent Document 1 discloses a technology for detecting the presence or absence of a rotor abnormality based on components extracted by subtracting two waveforms of the same phase from each other in the current flowing through an AC motor.

[0005] Patent No. 4062939

[0006] However, when using the technology of Patent Document 1, the AC motor must rotate at a constant speed in order to subtract two current waveforms of the same phase. Therefore, it is difficult to detect rotor abnormalities when starting the AC motor using the technology of Patent Document 1. Furthermore, even when not starting, the rotation speed fluctuates slightly due to load pulsation. For this reason, the technology of Patent Document 1 may not be able to achieve sufficient detection accuracy.

[0007] The present disclosure has been made in consideration of the above, and aims to provide an abnormality detection device for a synchronous reluctance motor that can detect an abnormality in the rotor even when the synchronous reluctance motor is not rotating at a constant speed.

[0008] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides an abnormality detection device for a synchronous reluctance motor that is applicable to a sensorless control device that performs control to detect rotor position by superimposing a high-frequency current on the synchronous reluctance motor, and includes a calculation unit and a determination unit. The calculation unit calculates a physical quantity that represents an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor. The determination unit determines an abnormality of the rotor based on the physical quantity.

[0009] The synchronous reluctance motor abnormality detection device according to the present disclosure has the advantage of being able to detect an abnormality in the rotor even when the synchronous reluctance motor is not rotating at a constant speed.

[0010] 4 is a diagram showing a functional configuration of an abnormality detection device for a synchronous reluctance motor according to embodiment 1; FIG. 5 is a diagram showing an example of the configuration of a sensorless control device including an abnormality detection device according to embodiment 1; FIG. 6 is a diagram showing an example of the waveform of a high-frequency voltage output from the position estimation voltage generation unit of FIG. 2; FIG. 7 is a cross-sectional view used to explain the structure of a rotor core in a synchronous reluctance motor assumed in embodiment 1; FIG. 1 is a diagram showing an example of a coefficient value table used in high frequency boost control of the first embodiment. FIG. 2 is a diagram showing an example of a current vector locus when there is no abnormality in the rotor of the synchronous reluctance motor shown in FIG. 2. FIG. 3 is a diagram showing an example of a current vector locus when there is an abnormality in the rotor of the synchronous reluctance motor shown in FIG. 2.

[0011] An abnormality detection device and an abnormality detection method for a synchronous reluctance motor according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Hereinafter, the "abnormality detection device for a synchronous reluctance motor" and the "abnormality detection method for a synchronous reluctance motor" will be referred to simply as the "abnormality detection device" and the "abnormality detection method" as appropriate.

[0012] Embodiment 1. Fig. 1 is a diagram showing the functional configuration of an abnormality detection device 40 according to embodiment 1. Fig. 2 is a diagram showing an example configuration of a sensorless control device 100 including the abnormality detection device 40 according to embodiment 1. As shown in Fig. 1, the abnormality detection device 40 includes a calculation unit 41 and a determination unit 42. As shown in Fig. 2, the sensorless control device 100 includes a current detection unit 2, a voltage applicator 3, a position estimation unit 4, a current control unit 5, a DC power supply 12, an abnormality determiner 25, and a position estimation voltage generation unit 30. In Fig. 1, the calculation unit 41 is configured to include the functions of the high-frequency current amplitude calculation unit 7 shown in Fig. 2 and the calculation processing function of the abnormality determiner 25 shown in Fig. 2, and the determination unit 42 is configured to include the determination processing function of the abnormality determiner 25 shown in Fig. 2.

[0013] In Fig. 2, a synchronous reluctance motor 1 is a device driven by a sensorless control device 100. The synchronous reluctance motor 1 has a stator 1a and a rotor 1b arranged inside the stator 1a. The sensorless control device 100 is a control device that superimposes a high-frequency current on the synchronous reluctance motor 1 without using a speed sensor or a position sensor to detect the rotor position, which is position information of the rotor 1b. Note that in this paper, a reluctance-type synchronous reluctance motor is assumed as an example of the synchronous reluctance motor 1, but is not limited to this. The synchronous reluctance motor 1 may also be an interior permanent magnet synchronous reluctance motor.

[0014] The DC power supply 12 supplies DC power to the voltage applicator 3. When the synchronous reluctance motor 1 is a motor, the voltage applicator 3 applies a DC voltage V ｄｃ is used to generate an AC voltage for driving the motor, and the generated AC voltage is applied to the motor.

[0015] The current detector 2 detects the motor current i flowing between the voltage applicator 3 and the synchronous reluctance motor 1. ｕ , i ｖ , i ｗ Detect the motor current i ｕ , i ｖ , i ｗis the stator current flowing through each phase of the stator 1a, i.e., the u-phase, v-phase, and w-phase. A current detector is provided for each phase of the current detection unit 2. An example of a current detector is a current transformer. In FIG. 2, the current detection unit 2 detects all three-phase currents, but this is not limiting. The currents of any two of the three phases are detected, and the remaining phase is used as the motor current i ｕ , i ｖ , i ｗ Alternatively, instead of the current detector 2 in FIG. 2, a bus current flowing through a DC bus (not shown) connecting the voltage applicator 3 and the DC power supply 12 may be detected, and the motor current i ｕ , i ｖ , i ｗ may be calculated.

[0016] As shown in FIG. 1, the calculation unit 41 calculates the motor current i ｕ , i ｖ , i ｗ The calculation unit 41 receives the current value, which is the detected value or calculated value of the motor current i ｕ , i ｖ , i ｗ The determining unit 42 determines whether the rotor 1b of the synchronous reluctance motor 1 is abnormal based on the physical quantity calculated by the calculating unit 41, and outputs the determination result J ｄ Examples of the physical quantities calculated by the calculation unit 41 will be described later.

[0017] Returning to the explanation of FIG. 2, the position estimation unit 4 calculates the motor current i ｕ , i ｖ , i ｗ The estimated value θ of the rotor position, which is the position information of the rotor 1b, is calculated based on the current value of Ｌ The current control unit 5 calculates the motor current i ｕ , i ｖ , i ｗ The estimated value of the rotor position θ Ｌ Based on this, a first voltage command V is calculated, which is a command value of the synchronous reluctance motor voltage for driving the synchronous reluctance motor 1. ｕ ＊ , V ｖ＊ , V ｗ ＊ The position estimation voltage generator 30 generates a q-axis current command i ｑ ＊ Based on this, the first voltage command V ｕ ＊ , V ｖ ＊ , V ｗ ＊ High frequency voltage V ｕｈ , V ｖｈ , V ｗｈ Generates a high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ is a voltage for position estimation for estimating the rotor position. The current control unit 5 outputs the first voltage command V ｕ ＊ , V ｖ ＊ , V ｗ ＊ High frequency voltage V ｕｈ , V ｖｈ , V ｗｈ The superimposed voltage is expressed as a second voltage command V ｕｐ ＊ , V ｖｐ ＊ , V ｗｐ ＊ The voltage applicator 3 outputs the second voltage command V ｕｐ ＊ , V ｖｐ ＊ , V ｗｐ ＊ and applies a driving voltage to the synchronous reluctance motor 1. In this document, the voltage applicator 3 is assumed to be a two-level three-phase inverter, but is not limited to this. In this document, the voltage applicator 3 may be a three-level three-phase inverter, or a polyphase two-level or three-level inverter.

[0018] The current control unit 5 includes subtractors 13d and 13q, a d-axis current controller 14d, a q-axis current controller 14q, a first coordinate converter 15, a two-phase to three-phase converter 16, a second coordinate converter 17, a three-phase to two-phase converter 18, and adders 23u, 23v, and 23w.

[0019] The subtractor 13d subtracts the d-axis current command i ｄ ＊ and the d-axis current i output from the second coordinate converter 17. ｄ Deviation Δi ｄ The next stage d-axis current controller 14d calculates the deviation Δi ｄ By controlling the proportional integral so that ｄ ＊ The subtractor 13q calculates the q-axis current command i ｑ ＊ and the q-axis current i output from the second coordinate converter 17. ｑ Deviation Δi ｑ The next stage q-axis current controller 14q calculates the deviation Δi ｑ By performing proportional-integral control so that ｑ ＊ Calculate the d-axis current command i ｄ ＊ is the command value of the d-axis current for driving the synchronous reluctance motor 1, and the q-axis current command i ｑ ＊ is the command value of the q-axis current for driving the synchronous reluctance motor 1. The d-axis current command i ｄ ＊ and q-axis current command i ｑ ＊ are both given from outside the current control unit 5.

[0020] The first coordinate converter 15 converts the d-axis voltage command V output from the d-axis current controller 14d and the q-axis current controller 14q into ｄ ＊ and q-axis voltage command V ｑ ＊ is expressed as the voltage command V on the stationary two-axis coordinate system. α ＊ , V β ＊ The two-phase to three-phase converter 16 converts the voltage command V α ＊ , V β ＊ is converted into a first voltage command V, which is a drive voltage command in three-phase AC coordinates. ｕ ＊ , V ｖ ＊, V ｗ ＊ The processing of the first coordinate converter 15 uses the estimated value θ of the rotor position output from the position estimation unit 4. Ｌ is also used.

[0021] The three-phase to two-phase converter 18 converts the motor current i detected by the current detection unit 2 into ｕ , i ｖ , i ｗ The α-axis current i on the stationary two-axis coordinate system α and β-axis current i β The second coordinate converter 17 converts the α-axis current i output from the three-phase to two-phase converter 18 into α and β-axis current i β is the estimated value θ of the rotor position output from the position estimation unit 4. Ｌ The d-axis current i on the rotating coordinate system rotates in synchronization with ｄ and q-axis current i ｑ and outputs the converted values ​​to the subtractors 13d and 13q.

[0022] The first voltage command V output from the two-phase to three-phase converter 16 ｕ ＊ , V ｖ ＊ , V ｗ ＊ and the high frequency voltage V output from the position estimation voltage generator 30. ｕｈ , V ｖｈ , V ｗｈ The outputs of the adders 23u, 23v, and 23w are added together to form a second voltage command V ｕｐ ＊ , V ｖｐ ＊ , V ｗｐ ＊ Therefore, the second voltage command V ｕｐ ＊ , V ｖｐ ＊ , V ｗｐ ＊ , the first voltage command V ｕ ＊ , V ｖ ＊ , V ｗ ＊The high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ is superimposed. ｕｈ , V ｖｈ , V ｗｈ Details will be described later.

[0023] The position estimation unit 4 includes a high-frequency current amplitude calculation unit 7 and a position calculator 8. The high-frequency current amplitude calculation unit 7 includes current extractors 6u, 6v, and 6w, multipliers 9u, 9v, and 9w, integrators 10u, 10v, and 10w, and square root calculators 22u, 22v, and 22w. These components are provided corresponding to each phase.

[0024] As described above, the second voltage command V applied to the voltage applicator 3 ｕｐ ＊ , V ｖｐ ＊ , V ｗｐ ＊ is a first voltage command V output by the two-phase to three-phase converter 16. ｕ ＊ , V ｖ ＊ , V ｗ ＊ The high frequency voltage V output by the position estimation voltage generator 30 is ｕｈ , V ｖｈ , V ｗｈ Therefore, the motor current i detected by the current detection unit 2 ｕ , i ｖ , i ｗ is the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ High frequency current i with the same frequency component as ｕｈ , i ｖｈ , i ｗｈ Contains:

[0025] Therefore, each of the current extractors 6u, 6v, and 6w extracts the motor current i detected by the current detection unit 2. ｕ , i ｖ , i ｗ From the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ High frequency current i with the same frequency component asｕｈ , i ｖｈ , i ｗｈ The high frequency current i ｕｈ , i ｖｈ , i ｗｈ A band-pass filter or a notch filter can be used to extract the motor current i ｕ , i ｖ , i ｗ is input to the notch filter to generate the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ Then, the motor current i ｕ , i ｖ , i ｗ By subtracting each current after passing through the notch filter from ｕｈ , i ｖｈ , i ｗｈ can be extracted.

[0026] The multipliers 9u, 9v, and 9w multiply the high-frequency current i ｕｈ , i ｖｈ , i ｗｈ The integrators 10u, 10v, and 10w perform integration processing over a time Tn corresponding to one integration period, and output the integrated value by multiplying the calculated value by (2 / Tn). The square root calculators 22u, 22v, and 22w calculate the position estimation current amplitude I by calculating the square root of each output of the integrators 10u, 10v, and 10w. ｕｈ , I ｖｈ , I ｗｈ The position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ is output to the position calculator 8 and the abnormality determiner 25.

[0027] In addition, in the high frequency current amplitude calculation unit 7 of FIG. ｕｈ , i ｖｈ , i ｗｈ The position estimation current amplitude I is calculated by integrating the autocorrelation value of ｕｈ , I ｖｈ , I ｗｈ However, the present invention is not limited to this. ｕｈ , i ｖｈ, i ｗｈ The position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ may be generated.

[0028] The position calculator 8 calculates the position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ Based on this, the rotor position estimate θ Ｌ The estimated rotor position θ Ｌ A known method is used to calculate the value of , and a detailed description thereof will be omitted here. Note that the specific calculation procedure is disclosed in, for example, Japanese Patent No. 5324646, and the contents of this publication should be referred to.

[0029] The abnormality determiner 25 determines the position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ The abnormality determination process by the abnormality determiner 25 will be described in detail later.

[0030] Next, the high frequency voltage V output from the position estimation voltage generator 30 ｕｈ , V ｖｈ , V ｗｈ 3 shows the high frequency voltage V output from the position estimation voltage generator 30 in FIG. ｕｈ , V ｖｈ , V ｗｈ 3 is a diagram showing an example of a waveform of the voltage applicator 3. The waveform of the voltage applicator 3 is an example in which a PWM (Pulse Width Modulation) inverter for triangular wave comparison is provided.

[0031] The horizontal axis of Fig. 3 represents time. In Fig. 3, from the top, there are a triangular wave carrier, a u-phase high frequency voltage V ｕｈ , v-phase high frequency voltage V ｖｈ , w-phase high frequency voltage V ｗｈ The waveform of the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈWhen one period Tc is a half period of the triangular wave carrier, one period Th of the high frequency voltage V is six periods (=6 Tc). ｕｈ , V ｖｈ , V ｗｈ In order to achieve three-phase balance, the high-frequency voltage V is set to be shifted by two sections (=2·Tc) between each phase. Note that FIG. 3 is an example, and the present invention is not limited to this example. ｕｈ , V ｖｈ , V ｗｈ Any waveform may be used as long as it is a waveform that results in three-phase balance.

[0032] Returning to Fig. 2, the position estimation voltage generation unit 30 will be described. The position estimation voltage generation unit 30 includes a high frequency amplitude calculator 31 and a high frequency voltage generator 32. The high frequency amplitude calculator 31 receives a q-axis current command i ｑ ＊ The high frequency amplitude calculator 31 receives the q-axis current command i ｑ ＊ Based on this, the coefficient value W ｈ Select or calculate the coefficient value W ｈ is the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ The coefficient value W is a positive real value that is set to determine the voltage amplitude of ｈ The selection of the coefficient value W ｈ Alternatively, the coefficient value W can be calculated by function calculation without using a table. ｈ may be calculated.

[0033] q-axis current command i ｑ ＊ is an example of a physical quantity that is correlated with the magnetic saturation of the rotor 1b. If the physical quantity is correlated with the magnetic saturation of the rotor 1b, the q-axis current command i ｑ ＊ Other examples of physical quantities correlated with the magnetic saturation of the rotor 1b include the q-axis current i ｑ , q-axis voltage command V ｑ ＊ etc. In addition, the d-axis current command i ｄ ＊ , d-axis current i ｄ , d-axis voltage command Vｄ ＊ These may also be physical quantities correlated with the magnetic saturation of the rotor 1b.

[0034] The high frequency voltage generator 32 generates a coefficient value W ｈ Using the above-mentioned high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ The operation of the high frequency voltage generator 32 is explained using some equations shown below.

[0035] A mathematical expression representing the high frequency current will be derived to explain the operation of the high frequency voltage generator 32. First, the voltage equation of the synchronous motor on the αβ axes, which are stationary coordinates, is expressed by the following equation (1).

[0036]

[0037] In the above formula (1), i α , i β are the α-axis current and β-axis current mentioned above. α , V β represent the α-axis voltage and the β-axis voltage, respectively. Ｅ represent the stator resistance and the induced voltage coefficient, respectively. α , L β , L αβ , L ｄ , L ｑ represent the α-axis inductance, the β-axis inductance, the mutual inductance between the α and β axes, the d-axis inductance, and the q-axis inductance, respectively. ０ is defined by the fifth formula of the above formula (1), and L １ is defined by the sixth equation of the above equation (1), where p denotes a differential operator.

[0038] The above formula (1) is applicable to both synchronous reluctance motors and interior permanent magnet synchronous motors. In the case of a synchronous reluctance motor that does not use magnets, the induced voltage coefficient K Ｅ becomes zero, so the induced voltage coefficient K ＥIn addition, when only the high frequency components are considered in the above equation (1), the following equation (2) is obtained.

[0039]

[0040] In the above formula (2), V αｈ , V βｈ , i αｈ , i βｈ represent the high frequency components of the α-axis voltage, β-axis voltage, α-axis current, and β-axis current, respectively. Note that the transformation from equation (1) to equation (2) also holds true for a synchronous reluctance motor that does not use a magnet.

[0041] When the above equation (2) is solved for the current differential term, the following equation (3) is obtained.

[0042]

[0043] Also, the a-axis and β-axis voltage V α , V β is defined by the following equation (4).

[0044]

[0045] In the above formula (4), V ｈαβ represents the high frequency voltage amplitude on the αβ axis, and ω ｈ represents the angular frequency on the αβ axis. Note that angular frequency is also called "angular velocity."

[0046] When the above equation (4) is expressed on three-phase coordinates, the default high-frequency voltage V is expressed by the following equation (5): ｕｈ１ , V ｖｈ１ , V ｗｈ１ is obtained.

[0047]

[0048] The high frequency voltage generator 32 calculates the coefficient value W ｈ and the default high frequency voltage V ｕｈ１ , V ｖｈ１ , V ｗｈ１ The coefficient value W ｈ By multiplying by , the high frequency voltage V ｕｈ, V ｖｈ , V ｗｈ Generate.

[0049]

[0050] Next, the structure of the rotor core that constitutes the rotor 1b in the synchronous reluctance motor 1 will be described. FIG. 4 is a cross-sectional view used to explain the structure of a rotor core 50 in the synchronous reluctance motor 1 assumed in the first embodiment. In FIG. 4, the rotor core 50 is formed by laminating a plurality of electromagnetic steel sheets, which are plate materials. A shaft 51 is fitted to the inner diameter side of the rotor core 50. The rotor core 50 is formed of a laminated body in which core pieces 53, which are annular thin plates, are stacked. The core pieces 53 can be made by punching out electromagnetic steel sheets, which are thin steel plates, with a press machine. When the synchronous reluctance motor 1 is assembled, the lamination direction of the thin plates that constitute the rotor core 50 is the same as the axial direction of the shaft 51.

[0051] A rotor core 50, which is made up of multiple stacked core pieces 53, has multiple slits 52 that form magnetic barriers. The slits 52 are arc-shaped and convex toward the shaft hole into which the shaft 51 fits, and are formed from one d-axis side to the other d-axis side with the q-axis as the center. In the rotor core 50, the d-axis is an axis through which magnetic flux passes relatively easily, and the q-axis is an axis through which magnetic flux passes relatively less easily. The d-axis and q-axis are magnetically and electrically perpendicular to each other.

[0052] Slit groups 54 each consisting of a plurality of slits 52 are formed at intervals in the circumferential direction of the rotor core 50, the number of which corresponds to the number of poles. Fig. 4 shows an example in which the rotor 1b has four poles, and in Fig. 4, slit groups 54 for four poles are formed.

[0053] The rotor core 50 must be strong enough to withstand the centrifugal force generated when the synchronous reluctance motor 1 rotates. Therefore, a center rib 55a, which acts as a strength member, is formed in the slits 52. Furthermore, in addition to the center rib 55a, two side ribs 55b, which also act as strength members, are formed in each slit 52 except for the outermost periphery. The center rib 55a and the side ribs 55b can be formed by leaving the center rib 55a and the side ribs 55b unpunched when punching out the slits 52 from a thin steel plate. The arrangement of the center rib 55a and the side ribs 55b shown in FIG. 4 is merely an example, and the arrangement is not limited to this. Any arrangement may be used as long as the desired strength is obtained.

[0054] Furthermore, in the rotor core 50, annular portions 57 are formed as annular portions because no slits 52 are formed between each of the slit groups 54 and an edge portion 56 on the outer periphery of the rotor core 50. In the rotor core 50, the annular portions 57 also function as strength members. In this document, the center rib 55a, the side ribs 55b, the annular portions 57, and the like, which function as strength members, may be collectively referred to as "bridge portions."

[0055] In the fifth and sixth equations of the above-mentioned equation (1), the d-axis inductance L ｄ and the q-axis inductance L ｑ 5 is a diagram showing the change in inductance in a typical synchronous reluctance motor. The horizontal axis represents the rotor position, and the vertical axis represents the magnitude of the inductance.

[0056] In a typical synchronous reluctance motor, the inductance changes depending on the electrical angle. Specifically, as shown in Figure 5, the inductance exhibits two maximum and two minimum values ​​during one electrical rotation. The maximum inductance is the d-axis inductance L ｄ The minimum value of the inductance is the q-axis inductance L ｑ That is, the d-axis inductance L ｄ teeth 、 q-axis inductance L ｑHere, the d-axis inductance L ｄ q-axis inductance L ｑ If the ratio is defined as the salient pole ratio, then the salient pole ratio L ｑ / L ｄ is a value greater than 1. This is because the d-axis current i ｄ than the interlinkage flux due to the q-axis current i ｑ This is because the synchronous reluctance motor 1 is configured so that the interlinkage magnetic flux due to the synchronous motor 1 is larger than the interlinkage magnetic flux due to the synchronous motor 1 .

[0057] 6 is a diagram showing an example of a current vector locus when a high-frequency current flows through the synchronous reluctance motor 1 having the rotor core 50 shown in FIG. 6. The horizontal axis of FIG. 6 represents the d-axis current i ｄ The vertical axis represents the q-axis current i ｑ As shown in FIG. 6, the q-axis current i ｑ When is relatively large, the current vector locus becomes elliptical. On the other hand, when the q-axis current i ｑ When is small, as shown in the lower left, the current vector locus is not elliptical but is almost circular. The center of the current vector locus represents the fundamental wave current component of the current flowing through the synchronous reluctance motor 1, and the distance from the center of each plot of the current vector locus represents the high frequency current component of the current flowing through the synchronous reluctance motor 1. Therefore, the q-axis current i ｑ A region where is small means that the torque command given to the synchronous reluctance motor 1 is small.

[0058] When the current vector locus is elliptical, the rotor position can be detected based on the difference or ratio between the length of the major axis and the length of the minor axis of the ellipse. ｑ It can be seen that the greater the value of , the better the accuracy of rotor position detection. The reason for this will be further explained with reference to Figure 7. Figure 7 is a diagram showing the flow of magnetic flux generated by high-frequency current components when the fundamental wave current component is small, in rotor core 50 shown in Figure 4.

[0059] In FIG. 7, the solid arrow indicates the q-axis current i ｑ This represents the flow of magnetic flux that can be generated by the high-frequency current component contained in the d-axis current i. In this paper, this magnetic flux component is referred to as the "torque flux" for convenience. The dashed arrow indicates the d-axis current i ｄ This represents the flow of magnetic flux that can be generated by the high-frequency current components contained in the bridge section. In this paper, this magnetic flux component will be referred to as the "excitation magnetic flux" for convenience. As mentioned above, the rotor core 50 shown in Figure 4 has a structure with salient poles. Therefore, during steady-state operation when the fundamental wave current component is large, the bridge section of the rotor core 50 is fully magnetically saturated, and the q-axis magnetic flux indicated by the solid arrow becomes small. In contrast, when the fundamental wave current component is small, the degree of magnetic saturation in the bridge section is low, and the torque magnetic flux passing through the bridge section does not attenuate much. As a result, the torque magnetic flux passing through the bridge section becomes large, the difference with the excitation magnetic flux becomes small, and the saliency does not appear.

[0060] The sensorless control device 100 according to the first embodiment shown in FIG. 2 is configured to solve the problem of the saliency. Specifically, the sensorless control device 100 calculates the rotor position estimated value θ Ｌ If the desired detection accuracy is not obtained, the coefficient value W calculated by the high frequency amplitude calculator 31 ｈ is controlled in an increasing direction, and the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ In this paper, this control is referred to as "high frequency boost control" for convenience.

[0061] Considering the absence of high-frequency current, if the fundamental current is small, its magnetic flux component easily passes through the bridge section. Narrowing the bridge section width reduces the amount of magnetic flux passing through, but weakens the rotor core 50. Furthermore, increasing the fundamental current causes magnetic saturation in the bridge section. However, this method is undesirable from an operational standpoint, since it causes unnecessary current to flow, reducing efficiency and applying unnecessary torque to the synchronous reluctance motor 1. In contrast, increasing the high-frequency current can magnetically saturate the bridge section without changing the magnitude of the fundamental current. This makes it possible to solve the problem of fundamental current making it difficult for saliency to occur through control.

[0062] The specific processing is as described above, and the coefficient value W ｈ Calculate the default high frequency voltage V ｕｈ１ , V ｖｈ１ , V ｗｈ１ The coefficient value W ｈ By multiplying this, the high frequency voltage V ｕｈ , V ｖｈ , V ｗｈ Also, the coefficient value W ｈ A table can be used to calculate the coefficient value table used in the high frequency boost control of the first embodiment.

[0063] In FIG. 8, the coefficient value table has a table head containing the d-axis current command i ｄ ＊ Current value i ｄ１ ＊ , i ｄ２ ＊ , i ｄ３ ＊ , ..., i ｄＭ ＊ is displayed, and the settable q-axis current command i ｑ ＊ Current value i ｑ１ ＊ , i ｑ２ ＊ , i ｑ３ ＊ , ..., i ｑＮ＊ The current value i ｄ１ ＊ , i ｄ２ ＊ , i ｄ３ ＊ , ..., i ｄＭ ＊ The intervals between the current values ​​i do not need to be equal, but may be unequal. ｑ１ ＊ , i ｑ２ ＊ , i ｑ３ ＊ , ..., i ｑＮ ＊ The same is true for .

[0064] The coefficient value table contains the d-axis current command i ｄ ＊ and q-axis current command i ｑ ＊ The coefficient value W is determined by the relationship ｈ The value of (W ｈ１１ , W ｈ１２ , W ｈ１３ , ..., W ｈ１Ｍ , W ｈ２１ , W ｈ２２ , W ｈ２３ , ..., W ｈ２Ｍ , W ｈ３１ , W ｈ３２ , W ｈ３３ , ..., W ｈ３Ｍ , ..., W ｈＮ１ , W ｈＮ２ , W ｈＮ３ , ..., W ｈＮＭ ) is stored. ｑ１ ＊ , i ｑ２ ＊ , i ｑ３ ＊ , ..., i ｑＮ ＊ Gai ｑ１ ＊ <i ｑ２ ＊ <i ｑ３ ＊ <, ..., <i ｑＮ ＊ If W ｈ１１ , W ｈ２１ , W ｈ３１ , ..., W ｈＮ１ Betweenｈ１１ >W ｈ２１ >W ｈ３１ >, ..., >W ｈＮ１ That is, the coefficient value W ｈ is the q-axis current command i ｑ ＊ There is a negative correlation with the coefficient values ​​of other columns W ｈ The same applies to the current value i ｄ１ ＊ , i ｄ２ ＊ , i ｄ３ ＊ , ..., i ｄＭ ＊ Gai ｄ１ ＊ <i ｄ２ ＊ <i ｄ３ ＊ <, ..., <i ｄＭ ＊ If W ｈ１１ , W ｈ１２ , W ｈ１３ , ..., W ｈ１Ｍ Between ｈ１１ >W ｈ１２ >W ｈ１３ >, ..., >W ｈ１Ｍ That is, the coefficient value W ｈ is the d-axis current command i ｄ ＊ There is a negative correlation with the coefficient values ​​W ｈ The same is true.

[0065] The values ​​stored in the coefficient value table can be obtained by simulation. It is not necessary to obtain all the values ​​by simulation, but the values ​​may be obtained by calculation using interpolation, extrapolation, or interpolation of some simulation results.

[0066] Next, the coefficient value W in the high frequency boost control ｈ First, in the coefficient value table of FIG. 8, the part surrounded by a thick frame is set as the default. ｄ１ ＊ = 0. The high frequency amplitude calculator 31 calculates the q-axis current command i ｑ ＊Based on this, the coefficient value W ｈ For example, the q-axis current command i ｑ ＊ The value of "i ｑ３ ＊ ", then "W ｈ３１ ". q-axis current command i ｑ ＊ The value of "i ｑ２ ＊ " and "i ｑ３ ＊ ", it may be obtained by interpolation, or "i ｑ２ ＊ " and "i ｑ３ ＊ You may select one of the following.

[0067] In addition, as a physical quantity correlated with the magnetic saturation of the rotor 1b, the q-axis current command i ｑ ＊ In addition, the d-axis current command i ｄ ＊ In this case, the entire coefficient value table of FIG. 8 is used. For example, the q-axis current command i ｑ ＊ The value of "i ｑ３ ＊ " and the d-axis current command i ｄ ＊ The value of "i ｄ２ ＊ ", then "W ｈ３２ If the coefficient value is not in the coefficient value table, it goes without saying that it may be found by interpolation or the like.

[0068] Next, the concept of the abnormality detection process of the first embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a diagram showing an example of a current vector locus when there is no abnormality in the rotor 1b of the synchronous reluctance motor 1 shown in Fig. 2. Fig. 10 is a diagram showing an example of a current vector locus when there is an abnormality in the rotor 1b of the synchronous reluctance motor 1 shown in Fig. 2.

[0069] The horizontal axis of FIG. 9 is the d-axis current i ｄ The vertical axis represents the q-axis current i ｑ Also, on the left side of FIG. 9, the q-axis current i ｑ= 0 and d-axis current i ｄ As the current vector locus when ｈ But, W ｈ = 0.1, W ｈ = 0.3 and W ｈ 9 shows the case where the same three coefficient values ​​W ｈ Regarding the q-axis current i ｑ = 0 and d-axis current i ｄ The current vector locus when .gtoreq.0 is shown.

[0070] W ｈ When W = 0.1, the center rib 55a, side rib 55b and annular portion 57 of the rotor core 50 are not magnetically saturated, so the torque magnetic flux passing through these portions increases and saliency does not appear. As a result, the current vector locus is not a clear ellipse but is a locus close to a perfect circle. In contrast, when W ｈ = 0.3 and W ｈ When ρ = 0.5, the center rib 55 a, side rib 55 b, and annular portion 57 of the rotor core 50 are magnetically saturated by the high-frequency current, so the torque magnetic flux passing through these portions becomes smaller and saliency appears, and the current vector locus becomes a clear ellipse.

[0071] On the other hand, if there is an abnormality in the rotor 1b, the current vector locus will be different from that in normal operation. In Figure 10, the dashed line K1 indicates that the current vector locus has changed from a nearly perfect circle to an ellipse. The dashed-dotted line K2 indicates that the current vector locus has changed from a nearly perfect circle to an ellipse and that distortion has occurred in the current vector locus.

[0072] If a crack occurs in at least one of the center rib 55a, the side rib 55b, and the annular portion 57 of the rotor core 50, the magnetic flux passing through the cracked portion is blocked, so the inductance component of the portion becomes smaller and the portion becomes equivalent to a saturated state. Therefore, if a change in the current vector locus from normal can be detected, it becomes possible to determine whether there is an abnormality in the rotor 1b.

[0073] Fig. 11 is a block diagram showing an example of a hardware configuration for realizing the functions of abnormality detection device 40 according to embodiment 1. When realizing the functions of abnormality detection device 40 according to embodiment 1, the configuration can include a processor 400 that performs calculations, a memory 402 that stores programs read by processor 400, an interface 404 that inputs and outputs signals, and a display 406 that displays detection results, as shown in Fig. 11 .

[0074] The processor 400 is an example of a computing unit. The processor 400 may be a computing unit called a microprocessor, a microcomputer, a microcontroller, a central processing unit (CPU), or a digital signal processor (DSP). Examples of the memory 402 include non-volatile or volatile semiconductor memory such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), and electrically programmable read-only memory (EEPROM), as well as a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, and a digital versatile disk (DVD).

[0075] The memory 402 stores a program that executes the functions of the anomaly detection device 40 according to the first embodiment. The processor 400 exchanges necessary information via the interface 404, executes the program stored in the memory 402, and refers to the data stored in the memory 402, thereby performing the above-described processing. The results of calculations by the processor 400 can be stored in the memory 402. The results of processing by the processor 400 can also be displayed on the display 406. The display 406 may be provided external to the anomaly detection device 40.

[0076] Furthermore, when realizing the functions of the abnormality detection device 40 according to the first embodiment, the configuration shown in Fig. 12 may be used. Fig. 12 is a block diagram showing another example of a hardware configuration that realizes the functions of the abnormality detection device 40 according to the first embodiment. In Fig. 12, the processor 400 and memory 402 shown in Fig. 11 are replaced with a processing circuit 403.

[0077] The processing circuit 403 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information input to and output from the processing circuit 403 can be exchanged via an interface 404.

[0078] 13 is a diagram illustrating the determination process in the abnormality detection process according to the first embodiment. The left side of FIG. 13 shows the position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ The right side of FIG. 13 shows the waveform of the position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ In addition to the waveform of ｕｈ , I ｖｈ , I ｗｈ The waveform of the current for position estimation I is shown by a dashed line. The horizontal axis of FIG. 11 represents the rotor position over one electrical angle period in both the left and right diagrams. ｕｈ , I ｖｈ , I ｗｈ is the output of the high frequency current amplitude calculation unit 7 calculated by the square root calculators 22u, 22v, and 22w shown in FIG.

[0079] The position estimation current amplitude I obtained by the high frequency current amplitude calculation unit 7 ｕｈ , I ｖｈ , I ｗｈ As shown in FIG. ｈ This DC component I ｈchanges in half of one period of the rotor position, that is, in half the period of the rotor position.

[0080] The abnormality determiner 25 calculates the DC component I ｈ and the DC component I is calculated by averaging the calculated value over one period or half period of the rotor position. ｈ The time average value of is calculated and stored in memory 402.

[0081]

[0082] When an abnormality occurs in the rotor 1b, the DC component I ｈ In FIG. 10, the DC component I ｈ The change in the DC component I appears as a change in the center position of the ellipse. ｈ The time average value of the calculated DC component I ｈ The presence or absence of an abnormality in the rotor 1b is determined by comparing the time average value of the abnormality determiner 25 with the time average value in a normal state stored in the memory 402. The abnormality determiner 25 displays the determination result on the display 406. The determination result by the abnormality determiner 25 may be stored in the memory 402.

[0083] In addition, the DC component I ｈ is the motor current i ｕ , i ｖ , i ｗ and is an example of a physical quantity that indicates an abnormal state of the rotor 1b. In the determination process in the abnormality detection process of the first embodiment, the DC component I ｈ Other physical quantities that represent the abnormal state of the rotor 1b may be replaced by the motor current i ｕ , i ｖ , i ｗ or the AC component included in the motor current i ｕ , i ｖ , i ｗ It may be a strain component contained in

[0084] 14 is a flowchart showing the processing flow of the abnormality detection processing according to embodiment 1. The operation of FIG. 14 will be explained in association with the calculation unit 41 and the determination unit 42 which are components of the abnormality detection device 40 shown in FIG.

[0085] The calculation unit 41 calculates the motor current i ｕ , i ｖ , i ｗ Based on the position estimation current amplitude I ｕｈ , I ｖｈ , I ｗｈ (Step S11). The calculation unit 41 also calculates the DC component I ｈ (Step S12). Furthermore, the calculation unit 41 calculates the DC component I ｈ The DC component I ｈ The time average value of I ｈａ (Step S13). The determination unit 42 calculates the time average value I ｈａ is compared with a threshold value A (step S14). The threshold value A is the DC component I ｈ The time average value of I ｈａ The threshold value is determined based on the above and is stored in advance in the memory 402.

[0086] Time average value I ｈａ If the time average value I is less than the threshold value A (step S15, Yes), the determination unit 42 determines that the rotor 1b is normal (step S16). ｈａ is equal to or greater than threshold value A (step S15, No), the determination unit 42 determines that the rotor 1b is not normal (step S17). After the processes of steps S16 and S17, the determination unit 42 displays the determination result on the display 406 (step S18). When the process of step S18 is completed, the process returns to step S11, and the processes from step S11 are repeated.

[0087] In the determination process of step S15, the time average value I ｈａ is equal to the threshold value A, the result is determined as "No", but the result may be determined as "Yes". ｈａ If the threshold value A is equal to the threshold value B, the result may be either "Yes" or "No."

[0088] A supplementary note on the above processing flow is provided. The processing flow shown in FIG. 14 can be implemented, for example, at the start-up of the sensorless control device 100. At the start-up of the sensorless control device 100, the synchronous reluctance motor 1 is often accelerating, increasing its rotational speed, and the rotational speed of the synchronous reluctance motor 1 is not constant. As described above, in the prior art, the synchronous reluctance motor 1 must rotate at a constant speed. For this reason, in the prior art, it is difficult to detect an abnormality in the rotor 1b at the start-up of the sensorless control device 100. In contrast, in the abnormality detection device 40 according to the first embodiment, the synchronous reluctance motor 1 does not need to rotate at a constant speed, and therefore, it is possible to detect an abnormality in the rotor 1b at the start-up of the sensorless control device 100.

[0089] As described above, the abnormality detection device according to the first embodiment is applicable to a sensorless control device that performs control to detect the rotor position by superimposing a high-frequency current on a synchronous reluctance motor. The abnormality detection device according to the first embodiment can be configured to include a calculation unit that calculates a physical quantity representing an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor, and a determination unit that determines an abnormality in the rotor based on the physical quantity. The abnormality detection device holds a threshold value determined based on the physical quantity when the rotor is normal. The determination unit determines the presence or absence of an abnormality in the rotor by comparing the physical quantity calculated by the calculation unit with the threshold value. The abnormality detection device according to the first embodiment does not impose any restrictions on the rotational speed of the synchronous reluctance motor, and therefore can detect an abnormality in the rotor even if the synchronous reluctance motor is not rotating at a constant speed. Furthermore, the abnormality detection device according to the first embodiment can detect an abnormality in the rotor when the sensorless control device is started, thereby enabling prompt detection of an abnormality in the rotor.

[0090] Furthermore, the abnormality detection device according to the first embodiment can be configured by utilizing part of the function of an existing high frequency boost control, which allows the configuration of the abnormality detection device to be easily realized.

[0091] In the above process, the physical quantity representing the abnormal state of the rotor of the synchronous reluctance motor may be the DC component contained in the motor current, the AC component contained in the motor current, or the distortion component contained in the motor current. Regardless of the physical quantity, the position estimation current amplitude calculated during sensorless control can be used, making it possible to easily realize the configuration of the abnormality detection device.

[0092] The abnormality detection method according to the first embodiment can be applied to a sensorless control device that performs control to detect the rotor position by superimposing a high-frequency current on a synchronous reluctance motor. The abnormality detection method according to the first embodiment can be a process including a calculation step of calculating a physical quantity representing an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor, and a determination step of determining whether the rotor is abnormal based on the physical quantity. A device that performs this abnormality detection method holds a threshold value determined based on the physical quantity when the rotor is normal. In the determination step, the presence or absence of a rotor abnormality is determined by comparing the physical quantity calculated in the calculation step with the threshold value. The abnormality detection method according to the first embodiment does not restrict the rotational speed of the synchronous reluctance motor, so it is possible to detect a rotor abnormality even if the synchronous reluctance motor is not rotating at a constant speed. Furthermore, the abnormality detection method according to the first embodiment can detect a rotor abnormality when the control device that performs sensorless control is started, so it is possible to quickly detect a rotor abnormality.

[0093] Embodiment 2 An abnormality detection device 40 according to embodiment 2 has the same configuration as that of embodiment 1. In embodiment 2, the configuration of the abnormality detection device 40 is the same as that of Figures 1 and 2, and the configuration of the sensorless control device 100 is the same as that of Figure 2. In embodiment 2, a technique that can improve the detection accuracy of the abnormality detection method according to embodiment 1 will be described.

[0094] 14 is executed at startup of the sensorless control device 100, it is conceivable that the results of multiple abnormality determinations will vary. That is, it is conceivable that an abnormality will be detected in one cycle of rotor position detection, and not in another cycle of rotor position detection. In such a case, it is possible to perform an abnormality determination of the rotor 1b multiple times, and output the determination result only if the multiple determination results are the same. In this way, it is possible to reduce the probability of erroneously determining that the rotor 1b is abnormal when it is actually normal.

[0095] As explained with reference to FIG. 6, the q-axis current i ｑ When is small, the current vector locus is not elliptical but is almost circular. Also, as explained with reference to FIG. 10, when there is an abnormality in the rotor 1b, the current vector locus changes from a circle to an ellipse. Therefore, the q-axis current i ｑ The smaller the value of q-axis current command i is, the larger the change in the shape of the current vector locus is, and therefore the higher the accuracy of abnormality detection is. Therefore, in the second embodiment, when abnormality determination of the rotor 1b is performed multiple times and the multiple determination results vary, the q-axis current command i is applied by the current control unit 5. ｑ ＊ The current control unit 5 is instructed to reduce the q-axis current command i ｑ ＊ The smaller the σ, the greater the change in the shape of the current vector locus, which can improve the stability of the abnormality determination process, thereby improving the accuracy of abnormality detection.

[0096] As described above, in the abnormality detection device according to embodiment 2, the judgment unit judges the rotor for abnormality multiple times, and outputs a judgment result if all of the multiple judgment results are the same. By adding this processing to the abnormality detection device according to embodiment 1, it is possible to reduce the probability of erroneously judging that the rotor is abnormal when it is actually normal.

[0097] Furthermore, if the determination results vary during the multiple determination processes, the current control unit may be instructed to reduce the torque axis current command applied by the current control unit. This can improve the stability of the abnormality determination process and the accuracy of abnormality detection.

[0098] Furthermore, according to the anomaly detection method of the second embodiment, in the determination step, the rotor is determined to be abnormal multiple times, and if the multiple determination results are all the same, a determination result is output. By adding this process to the anomaly detection method of the first embodiment, it is possible to reduce the probability of erroneously determining that the rotor is abnormal when it is actually normal.

[0099] Furthermore, in the above-described multiple determination processes, if the determination results vary, a command step may be included in which the current control unit is instructed to reduce the torque axis current command applied by the current control unit. By adding such a command step, the stability of the abnormality determination process can be improved, and the detection accuracy of the abnormality can be improved.

[0100] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0101] 1 Synchronous reluctance motor, 1a Stator, 1b Rotor, 2 Current detection unit, 3 Voltage application unit, 4 Position estimation unit, 5 Current control unit, 6u, 6v, 6w Current extractor, 7 High frequency current amplitude calculation unit, 8 Position calculator, 9u, 9v, 9w Multiplier, 10u, 10v, 10w Integrator, 12 DC power supply, 13d, 13q Subtractor, 14d d-axis current controller, 14q q-axis current controller, 15 First coordinate converter, 16 Two-phase to three-phase converter, 17 Second coordinate converter, 18 Three-phase to two-phase converter, 22u, 22v, 22w Square root calculator, 23u, 23v, 23w Adder, 25 Abnormality determiner, 30 Position estimation voltage generation unit, 31 High frequency amplitude calculator, 32 High frequency voltage generator, 40 Abnormality detection device, 41 Calculation unit, 42 Determination unit, 50 Rotor core, 51 Shaft, 52 Slit, 53 Core fragment, 54 Slit group, 55a Center rib, 55b Side rib, 56 Edge portion, 57 Annular portion, 100 Sensorless control device, 400 Processor, 402 Memory, 403 Processing circuit, 404 Interface, 406 Display.

Claims

1. An abnormality detection device for a synchronous reluctance motor that is applied to a sensorless control device that performs control to detect a rotor position by superimposing a high-frequency current on the synchronous reluctance motor, a calculation unit that calculates a physical quantity that represents an abnormal state of the rotor, the physical quantity being correlated with magnetic saturation of the rotor of the synchronous reluctance motor, based on a current value of a motor current flowing through the synchronous reluctance motor; a determination unit for determining an abnormality of the rotor based on the physical quantity; An abnormality detection device for a synchronous reluctance motor comprising:

2. a threshold value determined based on the physical quantity when the rotor is normal is held; The determination unit determines the presence or absence of an abnormality in the rotor by comparing the physical quantity calculated by the calculation unit with a threshold value.

2. The abnormality detection device for a synchronous reluctance motor according to claim 1.

3. The physical quantity is a direct current component contained in the motor current.

3. The abnormality detection device for a synchronous reluctance motor according to claim 1 or 2.

4. The physical quantity is an AC component contained in the motor current.

3. The abnormality detection device for a synchronous reluctance motor according to claim 1 or 2.

5. The physical quantity is a distortion component contained in the motor current.

3. The abnormality detection device for a synchronous reluctance motor according to claim 1 or 2.

6. The determination unit performs an abnormality determination for the rotor a plurality of times, and outputs a determination result when the plurality of determination results are all the same.

6. The abnormality detection device for a synchronous reluctance motor according to claim 5.

7. the sensorless control device includes a current control unit that generates a voltage command for driving the synchronous reluctance motor based on a current value of the motor current and the estimated value of the rotor position, When the results of the multiple determinations vary, the torque axis current command given by the current control unit is instructed to be smaller.

7. The abnormality detection device for a synchronous reluctance motor according to claim 6.

8. A method for detecting an abnormality in a synchronous reluctance motor, which is applied to a sensorless control device that performs control to detect a rotor position by superimposing a high-frequency current on the synchronous reluctance motor, comprising: a calculation step of calculating a physical quantity that is correlated with magnetic saturation of the rotor of the synchronous reluctance motor and indicates an abnormal state of the rotor based on a current value of a motor current flowing through the synchronous reluctance motor; a determination step of determining an abnormality in the rotor based on the physical quantity; A method for detecting an abnormality in a synchronous reluctance motor, comprising:

9. In the determination step, the rotor abnormality determination is performed a plurality of times, and a determination result is output when the plurality of determination results are all the same.

9. The method for detecting an abnormality in a synchronous reluctance motor according to claim 8.

10. the sensorless control device includes a current control unit that generates a voltage command for driving the synchronous reluctance motor based on a current value of the motor current and the estimated value of the rotor position, The determining step includes a command step of commanding the current control unit to reduce the torque axis current command applied by the current control unit when the multiple determination results in the determining step vary.

10. The method for detecting an abnormality in a synchronous reluctance motor according to claim 9.