AC rotating machine control device

Abstract

Provided is a device for controlling an AC rotary machine which makes it possible to determine demagnetization of a rotor magnet without using the impedance characteristics of the AC rotary machine. The control device (30) for an AC rotary machine uses m sets of voltage command values (Vqo), the voltage values (Iq) of m sets of armature windings, the resistance value (Ra) of the armature windings, and a rotational angular velocity (ω) as a basis to estimate interlinkage flux linked to the armature windings and determines whether demagnetization of a magnet is occurring on the basis of the result of comparing the estimated value of interlinkage flux and a demagnetization determination value (Thφ).

Description

[Technical Field]

[0001] The present application relates to a control device for an AC rotating machine. [Background technology]

[0002] The motor drive device disclosed in Patent Document 1 calculates a reference q-axis voltage value when demagnetization has not occurred based on the rotational angular velocity, the flux linkage caused by the permanent magnet when demagnetization has not occurred, the d-axis inductance, the d-axis current value, the resistance value of the armature winding, and the q-axis current value, and estimates the amount of demagnetization by comparing the reference q-axis voltage value with the actual q-axis voltage value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-51892 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 requires the use of d-axis inductance. The d-axis inductance fluctuates due to magnetic saturation. Therefore, if the accuracy of the d-axis inductance setting deteriorates, the accuracy of calculating the reference q-axis voltage value deteriorates, and the accuracy of demagnetization determination deteriorates. Furthermore, if two or more sets of armature windings are provided on the stator, the mutual inductance between the sets must also be set with precision. Furthermore, if a field winding is provided on the rotor, the inductance of the field winding must also be set with precision. In other words, the technology of Patent Document 1 will result in erroneous determination if the inductance characteristics of the AC rotating machine are not set with precision.

[0005] Therefore, an object of the present application is to provide a control device for an AC rotating machine that can determine demagnetization of a rotor magnet without using the inductance characteristics of the AC rotating machine. [Means for solving the problem]

[0006] The control device for an AC rotating machine according to the present application is a control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set, thereby applying a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature winding, the resistance value of the armature winding, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with 、 the flux linkage estimation unit uses a q-axis voltage command value as the voltage command value, uses a q-axis current value as the current value, and estimates a d-axis flux linkage that links with the armature winding as the flux linkage estimate value; The d-axis is set in the direction of the north pole of the magnet, and the q-axis is set in a direction that is 90 electrical degrees ahead of the d-axis, The flux linkage estimation unit, assuming that the q-axis voltage command value is Vqo, the q-axis current value is Iq, the resistance value is Ra, the rotational angular velocity is ω, and the d-axis flux linkage is φd, φd=(Vqo-Ra×Iq) / ω The d-axis interlinkage magnetic flux is estimated using the calculation formula: the flux linkage estimation unit estimates the flux linkage of the d axis on the larger side using a minimum value of a preset resistance value fluctuation range as the resistance value, and estimates the flux linkage of the d axis on the smaller side using a maximum value of the preset resistance value fluctuation range as the resistance value, The demagnetization determination unit determines that demagnetization has not occurred when the estimated value of the interlinkage magnetic flux of the smaller d-axis is greater than the demagnetization determination value, and determines that demagnetization has occurred when the estimated value of the interlinkage magnetic flux of the larger d-axis is smaller than the demagnetization determination value. It is something. [Effects of the Invention]

[0007] According to the control device for an AC rotating machine according to the present application, it is possible to indirectly estimate the armature flux linkage based on the m sets of voltage command values, the m sets of armature winding current values, the armature winding resistance values, and the rotational angular velocity using a voltage equation, without directly estimating the armature flux linkage due to the magnet and the armature reaction flux due to the d-axis current using the inductance characteristics of the AC rotating machine. Therefore, it is possible to estimate the armature flux linkage without using the inductance characteristics of the AC rotating machine. Then, it is possible to determine whether demagnetization of the magnet has occurred based on the comparison result between the estimated armature flux linkage value and the demagnetization determination value. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an AC rotary machine and a control device for the AC rotary machine according to a first embodiment. [Figure 2] 1 is a schematic block diagram of a control device according to a first embodiment. [Figure 3] 2 is a hardware configuration diagram of a control device according to the first embodiment. FIG. [Figure 4] 4 is a time chart illustrating the behavior of ringing according to the first embodiment. [Figure 5] 1 is a schematic block diagram of a control device including a winding temperature acquisition unit according to a first embodiment. [Figure 6] 5 is a diagram illustrating the range of variation of the interlinkage magnetic flux when a fixed resistance value is used according to the first embodiment. FIG. [Figure 7] 5 is a diagram illustrating the range of variation of the interlinkage magnetic flux when a variable resistance value is used according to the first embodiment. FIG. [Figure 8] 5A and 5B are diagrams illustrating demagnetization determination using one estimated value and one determination value according to the first embodiment. [Figure 9] 5A and 5B are diagrams illustrating demagnetization determination when one estimated value and two determination values ​​are used according to the first embodiment. [Figure 10] 5 is a diagram illustrating demagnetization determination using two estimated values ​​and one determination value according to the first embodiment. FIG. [Figure 11]5A and 5B are diagrams illustrating demagnetization determination when two estimated values ​​and two determination values ​​are used according to the first embodiment. [Figure 12] FIG. 4 is a diagram illustrating operating points at which estimated values ​​vary according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. First Embodiment A control device 30 for an AC rotating machine according to a first embodiment (hereinafter simply referred to as the control device 30) will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of an AC rotating machine 1, a power converter, and the control device 30 according to the present embodiment.

[0010] 1-1. AC rotating machine 1 The AC rotating machine 1 includes a stator 18 and a rotor 14. The stator 18 is provided with m sets of armature windings (m is a natural number equal to or greater than 1). In this embodiment, m is set to 2, and a first set of three-phase armature windings and a second set of three-phase armature windings are provided. The stator 18 is provided with a first set of three-phase armature windings Cu1, Cv1, Cw1 of U1 phase, V1 phase, and W1 phase, and a second set of three-phase armature windings Cu2, Cv2, Cw2 of U2 phase, V2 phase, and W2 phase. The three-phase armature windings of each set may be star-connected or delta-connected.

[0011] A magnet is provided on the rotor 14. In this embodiment, a field winding 7 is provided on the rotor 14. A permanent magnet 12 is also provided on the rotor 14. Demagnetization of the permanent magnet 12 is determined by a demagnetization determination described later.

[0012] Rotor 14 is provided with a rotation sensor 15 that detects the rotation angle (rotation angle) of rotor 14. An output signal from rotation sensor 15 is input to control device 30. Various types of sensors such as a Hall element, a resolver, or an encoder are used as rotation sensor 15. It may also be configured not to provide rotation sensor 15, but to estimate the rotation angle (magnetic pole position) based on current information or the like obtained by superimposing harmonic components on a current command value (described later) (so-called sensorless method).

[0013] 1-2.Inverter The power converters include a first inverter 4a and a second inverter 4b. The first inverter 4a converts power between the DC power source 2 and the first set of three-phase armature windings. The second inverter 4b converts power between the DC power source 2 and the second set of three-phase armature windings.

[0014] The first inverter 4a has three sets of series circuits (legs) corresponding to each of the three phases, each of which has a high-potential side switching element SP1 connected to the high-potential side of the DC power supply 2 and a low-potential side switching element SN1 connected to the low-potential side of the DC power supply 2. The connection point between the two switching elements in the series circuit for each phase is connected to the winding of the corresponding phase.

[0015] Specifically, in the U1-phase series circuit, the U1-phase high-side switching element SPu1 and the U1-phase low-side switching element SNu1 are connected in series, and the junction of the two switching elements is connected to the U1-phase armature winding Cu1. In the V1-phase series circuit, the V1-phase high-side switching element SPv1 and the V1-phase low-side switching element SNv1 are connected in series, and the junction of the two switching elements is connected to the V1-phase armature winding Cv1. In the W1-phase series circuit, the W1-phase high-side switching element SPw1 and the W1-phase low-side switching element SNw1 are connected in series, and the junction of the two switching elements is connected to the W1-phase armature winding Cw1.

[0016] The second inverter 4b has three sets of series circuits (legs) corresponding to each of the three phases, each set having a high-potential side switching element SP2 connected to the high-potential side of the DC power supply 2 and a low-potential side switching element SN2 connected to the low-potential side of the DC power supply 2. The connection point between the two switching elements in the series circuit for each phase is connected to the winding of the corresponding phase.

[0017] Specifically, in the U2-phase series circuit, the U2-phase high-side switching element SPu2 and the U2-phase low-side switching element SNu2 are connected in series, and the junction of the two switching elements is connected to the U2-phase armature winding Cu2. In the V2-phase series circuit, the V2-phase high-side switching element SPv2 and the V2-phase low-side switching element SNv2 are connected in series, and the junction of the two switching elements is connected to the V2-phase armature winding Cv2. In the W2-phase series circuit, the W2-phase high-side switching element SPw2 and the W2-phase low-side switching element SNw2 are connected in series, and the junction of the two switching elements is connected to the W2-phase armature winding Cw2.

[0018] The first set of inverters 4a and the second set of inverters 4b are connected to one DC power source 2. One smoothing capacitor 3 is connected in parallel to the DC power source 2. Note that each of the first set of inverters 4a and 4b may be provided with a smoothing capacitor.

[0019] The switching elements may be IGBTs (Insulated Gate Bipolar Transistors) with diodes connected in anti-parallel, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), bipolar transistors with diodes connected in anti-parallel, or the like. The gate terminals of the switching elements are connected to the control device 30 via gate drive circuits or the like. Each switching element of the first inverter group 4a is turned on or off by a switching signal for the first group output from the control device 30. Each switching element of the second inverter group 4b is turned on or off by a switching signal for the second group output from the control device 30.

[0020] The DC power supply 2 outputs a DC voltage Vdc to the first and second inverters 4a and 4b. The DC power supply 2 may be any device that outputs the DC voltage Vdc, such as a battery, a DC-DC converter, a diode rectifier, or a PWM rectifier.

[0021] A first set of armature current sensors 5a and a second set of armature current sensors 5b are provided to detect currents flowing through the first and second sets of armature windings of each phase. The first and second sets of armature current sensors 5a, 5b are current sensors such as shunt resistors or Hall elements. Output signals from the first and second sets of armature current sensors 5a, 5b are input to the control device 30.

[0022] In this embodiment, each set of armature current sensors 5a, 5b is provided on an electric wire connecting the series circuit of switching elements of each phase and the winding of each phase. Note that each set of armature current sensors 5a, 5b may be connected in series to the series circuit of switching elements of each phase. Alternatively, each set of current sensors may be provided on an electric wire connecting each set of inverters 4a, 4b and DC power supply 2, and the current of the winding of each phase of each set may be detected by the well-known "one bus shunt system."

[0023] 1-3. Converter 9 A converter 9 is provided as a power converter. The converter 9 has switching elements and performs power conversion between the DC power supply 2 and the field winding 7. In this embodiment, the converter 9 is an H-bridge circuit provided with two sets of series circuits, each set having a high-side switching element SP connected to the high-side of the DC power supply 2 and a low-side switching element SN connected to the low-side of the DC power supply 2. A connection point between the high-side switching element SP1 and the low-side switching element SN1 in a first set of series circuits 28 is connected to one end of the field winding 7, and a connection point between the high-side switching element SP2 and the low-side switching element SN2 in a second set of series circuits 29 is connected to the other end of the field winding 7.

[0024] The switching elements of the converter 9 may be IGBTs with diodes connected in anti-parallel, bipolar transistors with diodes connected in anti-parallel, MOSFETs, etc. The gate terminals of the switching elements are connected to the control device 30 via gate drive circuits, etc. Thus, the switching elements are turned on or off by switching signals output from the control device 30.

[0025] The converter 9 may have other configurations, such as replacing the low-potential side switching element SN1 of the first series circuit 28 with a diode, or replacing the high-potential side switching element SP2 of the second series circuit 29 with a diode.

[0026] The field current sensor 6 is a current detection circuit that detects the field current value If, ​​which is the current flowing through the field winding 7. In this embodiment, the field current sensor 6 is provided on the electric wire connecting the field winding 7 and the converter 9. The field current sensor 6 may also be provided at another location where the field current value If can be detected. An output signal from the field current sensor 6 is input to the control device 30. The field current sensor 6 is a current sensor such as a Hall element or a shunt resistor.

[0027] 1-4.Control device 30 The control device 30 controls the AC rotating machine 1 via a power converter (in this example, the first and second inverters 4a, 4b, and the converter 9). As shown in FIG. 2, the control device 30 includes functional units such as a rotation detection unit 31, a current detection unit 32, a voltage command value calculation unit 33, a switching control unit 34, a flux linkage estimation unit 35, and a demagnetization determination unit 36. Each function of the control device 30 is realized by a processing circuit included in the control device 30. Specifically, as shown in FIG. 3, the control device 30 includes, as processing circuits, an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 that exchanges data with the arithmetic processing device 90, an input circuit 92 that inputs external signals to the arithmetic processing device 90, an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside, and a communication circuit 94 that communicates data with an external device.

[0028] The arithmetic processing device 90 may be an application specific integrated circuit (ASIC), an integrated circuit (IC), a digital signal processor (DSP), a field programmable gate array (FPGA), various logic circuits, various signal processing circuits, etc. Furthermore, a plurality of the same or different types of arithmetic processing devices 90 may be provided, with each device performing a different process. The storage device 91 may include a random access memory (RAM) configured to be able to read and write data from the arithmetic processing device 90, and a read only memory (ROM) configured to be able to read data from the arithmetic processing device 90. The input circuit 92 is connected to various sensors, such as the rotation sensor 15, the sets of armature current sensors 5a and 5b, and the field current sensor 6, and includes an analog-to-digital (A / D) converter that inputs output signals from these sensors to the arithmetic processing device 90. The output circuit 93 is connected to electrical loads such as gate drive circuits that turn on and off the switching elements of the first and second inverters 4a, 4b and converter 9, and includes drive circuits that output control signals from the arithmetic processing device 90 to these electrical loads. The communication circuit 94 communicates with external devices.

[0029] The functions of the control units 31 to 36 and the like provided in the control device 30 are realized by the arithmetic processing device 90 executing software (programs) stored in a storage device 91 such as a ROM, and working in cooperation with other hardware of the control device 30 such as the storage device 91, an input circuit 92, and an output circuit 93. Various setting data used by the control units 31 to 36 and the like is stored in the storage device 91 such as a ROM as part of the software (programs). Each function of the control device 30 will be described in detail below.

[0030] 1-4-1. Rotation detection unit 31 The rotation detection unit 31 detects the magnetic pole position θ (rotor rotation angle θ) and rotation angular velocity ω of the rotor in electrical angle. In this embodiment, the rotation detection unit 31 detects the magnetic pole position θ (rotation angle θ) and rotation angular velocity ω in electrical angle based on the output signal of the rotation sensor 15. The electrical angle is the angle obtained by multiplying the mechanical angle of the rotor 14 by the number of pole pairs of the magnet.

[0031] The magnetic pole position θ is set to the orientation of the north pole of the magnets (electromagnets and permanent magnets in this example) provided on the rotor. In this embodiment, the magnetic pole position θ (rotation angle θ) is the position (angle) of the magnetic pole (north pole) in electrical angle with the first set of U1-phase armature windings as the reference. If a phase difference is provided between the first set of armature windings and the second set of armature windings, the phase difference is taken into consideration when calculating the magnetic pole position θ (rotation angle θ) for each set.

[0032] In addition, the rotation detection unit 31 may be configured to estimate the rotation angle (magnetic pole position) without using a rotation sensor based on current information obtained by superimposing harmonic components on the current command value (so-called sensorless method).

[0033] 1-4-2. Current detection unit 32 Current detection unit 32 detects winding currents Ius1, Ivs1, and Iws1 flowing through the first set of three-phase armature windings based on output signals from first set of armature current sensors 5a. Current detection unit 32 also detects winding currents Ius2, Ivs2, and Iws2 flowing through the second set of three-phase armature windings based on output signals from second set of armature current sensors 5b. For each set, winding currents of two phases may be detected, and the winding current of the remaining phase may be calculated based on the detected values ​​of the winding currents of the two phases.

[0034] Further, the current detection unit 32 detects the field current value Ifs, which is the current flowing through the field winding 7, based on the output signal of the field current sensor 6.

[0035] 1-4-3. Voltage command value calculation unit 33 The voltage command value calculation unit 33 calculates a voltage command value for each set.

[0036] The voltage command value calculation unit 33 calculates a d-axis current command value Ido and a q-axis current command value Iqo for each pair using various known methods. For example, the voltage command value calculation unit 33 uses known vector control to calculate the d-axis and q-axis current command values ​​Ido and Iqo for each pair based on the torque command value, the rotational angular velocity ω, etc. The d-axis and q-axis current command values ​​of the first pair are Ido1 and Iqo1, and the d-axis and q-axis current command values ​​of the second pair are Ido2 and Iqo2. The torque command values ​​may be calculated within the control device 30 or may be transmitted from an external control device. The d-axis is defined in the direction of the north pole of the magnet, and the q-axis is defined in a direction 90 electrical degrees ahead of the d-axis.

[0037] The voltage command value calculation unit 33 converts the three-phase current detection values ​​Ius, Ivs, and Iws for each set into a d-axis current detection value Ids and a q-axis current detection value Iqs by performing a known three-phase to two-phase transformation and a rotational coordinate transformation based on the magnetic pole position θ. The d-axis and q-axis current detection values ​​of the first set are designated Ids1 and Iqs1, and the d-axis and q-axis current detection values ​​of the second set are designated Ids2 and Iqs2.

[0038] The voltage command value calculation unit 33 performs known current feedback control based on the d-axis and q-axis current command values ​​Ido, Iqo and the d-axis and q-axis current detection values ​​Ids, Iqs for each pair to calculate a d-axis voltage command value Vdo and a q-axis voltage command value Vqo. The d-axis and q-axis voltage command values ​​for the first pair are designated Vdo1 and Vqo1, and the d-axis and q-axis voltage command values ​​for the second pair are designated Vdo2 and Vqo2. Note that the voltage command value calculation unit 33 may also calculate the d-axis voltage command value Vdo and the q-axis voltage command value Vqo for each pair by known feedforward control based on the d-axis and q-axis current command values ​​Ido and Iqo.

[0039] Then, for each set, the voltage command value calculation unit 33 performs a known fixed coordinate transformation and a two-phase to three-phase transformation on the d-axis and q-axis voltage command values ​​Vdo, Vqo based on the magnetic pole position θ to calculate three-phase voltage command values ​​Vuo, Vvo, Vwo. The three-phase voltage command values ​​of the first set are designated Vuo1, Vvo1, Vwo1, and the three-phase voltage command values ​​of the second set are designated Vuo2, Vvo2, Vwo2. Known modulation such as space vector modulation or two-phase modulation may be applied to the three-phase voltage command values ​​of each set.

[0040] Note that the voltage command values ​​for the three phases of each set may be calculated using other known control methods such as V / f control. When V / f control is performed, the current detection value is not required, so there is no need to provide a current sensor.

[0041] 1-4-4. Switching control unit 34 The switching control unit 34 turns on and off the switching elements of the inverters of each group based on the voltage command value, thereby applying a voltage to the armature winding. In this embodiment, the switching control unit 34 generates switching signals for each group that turn on and off the multiple switching elements of the inverters of each group based on the three-phase voltage command values ​​Vuo, Vvo, and Vwo. The switching control unit 34 uses well-known carrier comparison PWM or space vector PWM.

[0042] When carrier comparison PWM is used, the switching control unit 34 compares the carrier wave with each of the three-phase voltage command values ​​Vuo, Vvo, and Vwo for each set, and generates switching signals that turn on and off multiple switching elements based on the comparison results.

[0043] When space vector PWM is used, the switching control unit 34 generates a voltage command vector from three-phase voltage command values ​​Vuo, Vvo, and Vwo, determines the output time distribution of seven basic voltage vectors in a PWM period based on the voltage command vector, and generates switching signals that turn on and off each switching element in a PWM period based on the output time distribution of the seven basic voltage vectors.

[0044] <On / off control of converter 9> The switching control unit 34 turns on and off switching elements included in the converter 9 to apply a voltage to the field winding 7. In the present embodiment, the switching control unit 34 sets a field current command value Ifo based on the torque command value, the rotational angular velocity ω, etc., changes the field voltage command value Vfo so that the field current detection value Ifs approaches the field current command value Ifo, and performs on / off control of a plurality of switching elements of the converter 9 by PWM control based on the field voltage command value Vfo. Note that when feedforward control or control using an estimated value of the field current is performed, the field current detection value Ifs does not need to be used.

[0045] 1-4-5. Flux linkage estimation unit 35 and demagnetization determination unit 36 <Principle of Estimating Interlinkage Magnetic Flux> First, the principle of estimating flux linkage according to the present application will be described. The voltage equation of the AC rotating machine 1 of this embodiment is shown in the following equation. Here, as will be described later, in order to take into account the average values ​​of two sets of d- and q-axis current values ​​and the average values ​​of two sets of d- and q-axis voltage values, an equation using the sum of two sets of d- and q-axis current values ​​and the sum of two sets of d- and q-axis voltage values ​​has been derived in advance.

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[0046] where ω is the rotational angular velocity in electrical angles, Ra is the resistance of the armature winding, s is the Laplace operator, Ld is the self-inductance on the d-axis, Lq is the self-inductance on the q-axis, Md is the mutual inductance on the d-axis between pairs of armature windings, Mq is the mutual inductance on the q-axis between pairs of armature windings, Lmd is the mutual inductance between the armature winding and field winding, Rf is the resistance of the field winding, Lf is the inductance of the field winding, and φf0 is the flux linkage caused by the permanent magnet. Note that the inductances Ld and Lq, resistance Ra, and mutual inductances Md and Mq of each pair of armature windings are the same.

[0047] In this embodiment, as shown in the following equation, the armature flux linkage φa that links with the armature winding is the sum of the field winding flux linkage φf that corresponds to the field current value If due to the field winding, and the flux linkage φf0 due to the permanent magnet.

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[0048] Because the voltage that can be applied to each armature winding is equal to or less than the DC voltage Vdc, the condition under which the dq-axis current can be stably controlled to the desired value is given by the following equation: Therefore, by determining the field current during magnetic flux estimation control in consideration of the voltage saturation condition in equation (3), the dq-axis current can be output according to the command value, and the magnetic flux can be estimated with high accuracy.

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[0049] In the steady state, the term of the Laplace operator s in equation (1) becomes 0, so equation (1) becomes:

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[0050] From equation (4), the armature interlinkage magnetic flux φa can be expressed as follows:

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[0051] Furthermore, the dq-axis currents from two or more sets of armature windings can cause ringing even in steady state due to interference between the currents flowing through each armature. As an example, Figure 4 shows the waveforms of ringing from two sets of armature windings. The detected current value of the first set of armature winding and the detected current value of the second set of armature winding can ring in opposite phases, centered around the current command value of each set. This is due to mutual interference between the armature windings of the sets.

[0052] Furthermore, the detected current values ​​may differ for each armature winding due to sensor errors, and the voltage command value calculated based on the detected current values ​​containing sensor errors may also differ.

[0053] In this way, even if there is a difference between the sets of dq-axis current values ​​flowing through the armature windings and the dq-axis voltage command values ​​calculated based on them, it is necessary to perform demagnetization judgment with high accuracy.

[0054] Therefore, it is conceivable to use the average value of two sets of d- and q-axis current values ​​and the average value of two sets of d- and q-axis voltage command values ​​to calculate the armature flux linkage φa. Taking this into consideration, equations (1) to (5) are derived in advance as equations that use the total value of the two sets.

[0055] As a result, in an AC rotating machine having two or more sets of armature windings, by using the average value of all sets of voltage command values ​​and the average value of all sets of current values, it is possible to make each variable used in the calculation of the armature flux linkage φa more constant, and also to reduce the influence of sensor error for each armature winding, thereby making it possible to reduce the calculation error of the armature flux linkage φa.

[0056] In this embodiment, since two sets of armature windings are provided, the average value Vqave of the q-axis voltage value, the average value Idave of the d-axis current value, and the average value Iqave of the q-axis current value used in calculating the armature flux linkage φa are given by equations (6) to (8). The armature flux linkage φa is calculated using each average value with equation (9), which is a modification of equation (5).

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[0057] The second term in the numerator of equation (9) is the armature reaction flux generated by the d-axis current value Id. The armature reaction flux is a variable term that changes depending on the magnetic saturation characteristics. In other words, to accurately calculate the armature reaction flux, map data showing changes in the d-axis inductance Ld and the d-axis mutual inductance Md is required. If the accuracy of these inductances deteriorates, the accuracy of the calculation of the armature flux linkage φa using equation (9) deteriorates, and the accuracy of the demagnetization determination also deteriorates.

[0058] Therefore, equation (9) is transformed into the following equation. φd is the d-axis armature flux linkage that links with the armature winding, which is the sum of the armature flux linkage φa and the armature reaction flux due to the d-axis current. In other words, equation (9) is transformed into an equation for calculating the d-axis armature flux linkage φd. In the center side of equation (10), the armature flux linkage φa fluctuates due to demagnetization, and the d-axis inductance Ld and the d-axis mutual inductance Md fluctuate due to magnetic saturation. Therefore, as shown on the right side of equation (10), we consider indirectly estimating the d-axis armature flux linkage φd based on the average value Vqave of the q-axis voltage, the armature winding resistance Ra, the average value Iqave of the q-axis current, and the rotational angular velocity ω.

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[0059] In addition, in a steady state, the d-axis armature flux linkage φd calculated by the right-hand side of equation (10) can be considered constant because the changes in the d-axis inductance Ld and the d-axis mutual inductance Md are small. Furthermore, because the resistance value Ra is also taken into account, it can also handle cases where the resistance value Ra changes due to temperature changes. The rotational angular velocity ω is also taken into account. Therefore, the d-axis armature flux linkage φd can be indirectly estimated using the voltage equation from the right-hand side of equation (10).

[0060] The demagnetization judgment value Thφ can also be set using the right side of equation (10). That is, in a steady state at a certain operating point when demagnetization has not occurred, the demagnetization judgment value can be set based on the armature flux linkage φd of the d axis calculated using the right side of equation (10). The method for setting the demagnetization judgment value will be described later.

[0061] Unlike this embodiment, even when one set of armature windings is provided, it is possible to derive equations for the armature flux linkage φa and the d-axis armature flux linkage φd based on the voltage equations in the same way. Because the mutual inductance Md on the d-axis is zero, substituting Md=0 into equations (9) and (10) yields the following equation for one set of armature windings. Therefore, even in the case of one set of armature windings, the d-axis armature flux linkage φd can be estimated using an equation similar to the right-hand side of equation (10) for the case of two sets, as shown on the right-hand side of equation (12).

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[0062] Unlike this embodiment, even when three sets of armature windings are provided, the calculation expressions for the armature flux linkage φa and the d-axis armature flux linkage φd can be derived similarly based on the voltage equations, as shown in the following expressions. Therefore, even in the case of three sets, the d-axis armature flux linkage φd can be estimated using an expression similar to the right-hand side of expression (10) in the case of two sets, as shown on the right-hand side of expression (14). The same applies to four or more sets.

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[0063] <Estimation of magnetic flux linkage and demagnetization judgment> Therefore, a flux linkage estimation unit 35 estimates the armature flux linkage that links with the armature windings based on m sets of voltage command values, m sets of armature winding current values, armature winding resistance value Ra, and rotational angular velocity ω. The current detection value or current command value is used as the current value of each set of armature winding. A demagnetization determination unit 36 ​​determines whether demagnetization of the magnet is occurring based on the result of comparing the flux linkage estimate value with the demagnetization determination value.

[0064] According to this configuration, the armature flux linkage can be indirectly estimated using the voltage equation without directly estimating the armature flux linkage φa and the armature reaction flux due to the d-axis current using the d-axis inductance, the mutual inductance between the sets, and the inductance of the field winding. Therefore, the armature flux linkage can be estimated without providing map data or the like to accurately calculate the inductances Ld and Md. Then, based on the comparison result between the estimated armature flux linkage value and the demagnetization determination value, it can be determined whether demagnetization of the magnet has occurred.

[0065] In this embodiment, the demagnetization of the permanent magnets 12 provided in the rotor 14 is determined.

[0066] The demagnetization determination unit 36 ​​transmits the result of the demagnetization determination to an external control device or the like. A user can determine whether or not maintenance of the AC rotating machine 1 is necessary based on the result of the determination of the occurrence of demagnetization. The demagnetization determination unit 36 ​​may determine the degree of demagnetization based on the result of comparing the estimated value of the flux linkage with the demagnetization determination value. For example, the demagnetization determination unit 36 ​​determines that the degree of demagnetization is greater as the degree of decrease in the estimated value of the flux linkage from the demagnetization determination value increases.

[0067] In this embodiment, the flux linkage estimation unit 35 uses the average value of the m sets of voltage command values ​​as the m sets of voltage command values, and uses the average value of the m sets of current values ​​as the m sets of current values.

[0068] According to this configuration, by using the average value, as described above, it is possible to cancel the influence of ringing in the current values ​​of each set that occurs due to mutual interference between the armature windings of the sets, thereby improving the accuracy of estimating the armature flux linkage. Furthermore, even if an error occurs in the current sensor, the influence of the error can be reduced.

[0069] In this embodiment, the flux linkage estimation unit 35 uses the q-axis voltage command value Vqo as the voltage command value, uses the q-axis current value Iq as the current value, and estimates the d-axis armature flux linkage φd that links with the armature winding as the estimated value of the armature flux linkage.

[0070] As shown in the following equation, the flux linkage estimation unit 35 estimates the d-axis armature flux linkage φd based on the average value Vqoave of the first and second sets of q-axis voltage command values ​​Vqo1 and Vqo2, the average value Iqave of the first and second sets of q-axis current values ​​Iq1 and Iq2, the resistance value Ra of the armature winding, and the rotational angular velocity ω. As the q-axis current value of each set, the q-axis current detection value Iqs or the q-axis current command value Iqo of each set is used. Note that when one set of armature windings is provided, the right-hand side of equation (12) is used.

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[0071] (1) How to determine the resistance value Ra (1-1) Estimation of φd Estimation of the d-axis armature flux linkage φd (hereinafter simply referred to as φd) will be described with a focus on the resistance value Ra. The resistance value Ra changes depending on the winding temperature. The method of determining demagnetization differs depending on whether the resistance value Ra is made variable according to the winding temperature or is a fixed value. Below, we will explain both the case where the resistance value Ra is made variable and the case where it is made fixed.

[0072] (1-1-1) When Ra is set to a fixed value First, a case will be described in which the resistance value Ra used to estimate the d-axis armature flux linkage φd (hereinafter simply referred to as φd) is set to a fixed value. In this case, an error occurs between the actual resistance value Ra and the fixed resistance value Ra, which affects the estimation accuracy of φd.

[0073] Therefore, the fluctuation range of the resistance value is determined in advance, and the fixed resistance value Ra is determined taking into consideration the tolerance and detection rate of demagnetization judgment. Therefore, the maximum value Ra_max and minimum value Ra_min of the fluctuation range of the resistance value are obtained in advance and reflected in the estimated value of φd.

[0074] At the same operating point, such as the rotational angular velocity ω and the q-axis current value Iq (or torque command value), the q-axis current value Iq is constant regardless of the resistance value Ra, so the second term of equation (17) depends on the magnitude of the resistance value Ra. Therefore, using the maximum resistance value Ra_max and the minimum resistance value Ra_min, the second term of equation (17) can be expressed as Ra_max×Iq and Ra_min×Iq, respectively. Ra_max×Iq and Ra_min×Iq indicate the maximum and minimum values ​​of Ra×Iq at each operating point.

[0075] In the following, for ease of explanation, let ω = 1 and consider the numerator of equation (17). From the numerator of equation (17), it can be seen that the larger Vq is and the smaller Ra × Iq ​​is, the larger the estimated value of φd becomes. Therefore, by setting Ra to Ra_min, the estimated value of φd during actual operation becomes larger, making it less likely that demagnetization has occurred, and false positives can be reduced. Note that a false positive is an erroneous determination that something that is not demagnetized is demagnetized.

[0076] Conversely, the smaller Vq is and the larger Ra × Iq ​​is, the smaller the estimated value of φd becomes, so if you want to calculate a smaller estimated value of φd during actual operation, by setting Ra to Ra_max, the estimated value of φd during actual operation becomes smaller, making it easier to determine that demagnetization has occurred and reducing false negatives. Note that a false negative is an erroneous determination that something that is demagnetized is not demagnetized.

[0077] It is also possible to estimate two φd values ​​using both Ra_max and Ra_min for Ra used as the estimated value of φd, and use the two estimated values ​​of φd for demagnetization judgment. When two estimated values ​​of φd are used, it is possible to increase the degree of freedom in demagnetization judgment. A demagnetization judgment method using the estimated results of two φd will be described later in sections (2) and (3).

[0078] (1-1-2) When Ra is set to a variable value Next, a case will be described in which the resistance value Ra used to estimate φd varies depending on the winding temperature. In this case, as shown in FIG. 5 , a winding temperature acquisition unit 37 is provided to detect or estimate the winding temperature of the armature winding. To detect the winding temperature, a temperature sensor is attached to the armature winding, and the output signal of the temperature sensor is input to the control device 30, and the winding temperature acquisition unit 37 detects the winding temperature. To estimate the winding temperature, the winding temperature acquisition unit 37 estimates the winding temperature using an estimation model, such as a thermal model, based on operating conditions such as current values. The flux linkage estimation unit 35 then references characteristic data that defines a relationship between the winding temperature and the resistance value Ra in advance, and estimates the resistance value Ra based on the detected or estimated winding temperature. The flux linkage estimation unit 35 then estimates φd using the estimated resistance value Ra. Therefore, using a highly accurate resistance value Ra, assuming no error in the values ​​detected by each sensor, allows for more accurate estimation of φd than using a fixed resistance value Ra.

[0079] (1-2) Setting the demagnetization threshold Thφ Next, a method for setting the demagnetization judgment value Thφ will be described. As with the estimated value of φd, calculation of the d-axis armature flux linkage φdth for judgment value setting (hereinafter also referred to as φdth for judgment value setting) will be described assuming that the resistance value Ra is a fixed value or a variable value.

[0080] As with the estimation of φd, making the resistance value Ra variable increases the accuracy of setting the demagnetization determination value Thφ. Therefore, if the winding temperature acquisition unit 37 is provided and the winding temperature can be acquired, it is better to use the variable resistance value Ra also in setting the demagnetization determination value Thφ.

[0081] (1-2-1) When Ra is set to a fixed value FIG. 6 illustrates the parameters used to estimate φd at a certain operating point, such as the rotational angular velocity ω and the q-axis current value Iq (or torque command value) when demagnetization is not occurring. Ra_max×Iq, Ra_min×Iq, and Vqo_max and Vqo_min represent the maximum and minimum values ​​of the fluctuation range of Ra×Iq and the fluctuation range of the q-axis voltage command value Vqo at a certain operating point, obtained in advance verification. The maximum estimated value of φd, φd_max_ass, and the minimum estimated value of φd, φd_min_ass, which are obtained by combining these four values, are expressed by the following equations. Here, as mentioned above, ω is set to 1 for ease of explanation.

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[0082] However, if there is no error in the sensor detection values ​​and no demagnetization, Ra and Vqo at a certain operating point are proportional, and Vq increases as Ra increases. Therefore, when Ra × Iq ​​is maximum, Vq is also maximum, and conversely, when Ra × Iq ​​is minimum, Vq is also minimum. Therefore, if the estimated value of φd when Ra_min is used to estimate φd is φd_min, and the estimated value of φd when Ra_max is used to estimate φd is φd_max, the following relationship holds:

number

[0083] Therefore, whether Ra_min or Ra_max is used to estimate φd, the estimated value of φd when demagnetization has not occurred falls within the range from φd_min_ass to φd_max_ass, as shown in the following equation. Therefore, if the estimated value of φd falls outside the range from φd_min_ass to φd_max_ass, it can be determined that demagnetization has occurred. For example, the demagnetization determination unit 36 ​​can determine that demagnetization has occurred if the estimated value of φd is smaller than a demagnetization determination value Thφ that is preset in φd_min_ass. In this way, φd_max_ass and φd_min_ass can be used as a single index for the demagnetization determination value Thφ.

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[0084] (1-2-2) When Ra is a variable value As described above, consider the case where the resistance value Ra is made variable in accordance with the winding temperature acquired by the winding temperature acquisition unit 37. As described above, if there is no error in the values ​​detected by the sensors and no demagnetization occurs, Ra and Vqo at a certain operating point are proportional to each other, and when Ra×Iq is maximum, Vqo is also maximum, and conversely, when Ra×Iq is minimum, Vqo is also minimum.

[0085] FIG. 7 shows a case where φd is estimated using an estimated resistance value Ra that is varied according to the winding temperature. When there is no error in the sensor detection values, the estimated φd fluctuates little relative to changes in the resistance value Ra. The maximum and minimum values ​​φd_maxerr and φd_minerr of the estimated φd due to errors in the sensor detection values ​​when demagnetization does not occur are shown, but the fluctuation range is small. Therefore, the fluctuation range is smaller than the maximum and minimum values ​​φd_max and φd_min of the estimated φd when a fixed resistance value Ra is used. The demagnetization determination value Thφ may be preset to a value smaller than the minimum value φd_minerr of the estimated φd that takes into account errors in the sensor detection values. That is, the demagnetization determination unit 36 ​​determines that demagnetization has occurred when the estimated φd is smaller than the demagnetization determination value Thφ, which is preset to a value smaller than φd_minerr. Estimating φd using a variable resistance value Ra in this way improves the accuracy of demagnetization determination. Furthermore, the demagnetization determination value Thφ can be set to a value that allows for detection of minute demagnetization.

[0086] (2) Number of estimated values ​​of φd and number of Thφ The method for performing demagnetization determination using one estimated value of φd and one demagnetization determination value Thφ has been described above. Below, a method for performing demagnetization determination using multiple estimated values ​​of φd and / or multiple demagnetization determination values ​​Thφ will be described.

[0087] (2-1) Number of estimated values ​​of φd As explained in (1-2-2), when a variable resistance value Ra according to the winding temperature is used, the estimation accuracy of φd is high, so there is little need to estimate multiple φd values. Below, we will explain a method for estimating multiple φd values ​​when a fixed resistance value Ra is used.

[0088] As explained in (1-1-1), when a fixed resistance value Ra is used, it is possible to estimate two values ​​φd_max and φd_min using the variation ranges Ra_min and Ra_max for Ra. When φd_max is estimated using Ra_min, φd_max becomes larger, which can reduce false positives. On the other hand, when φd_min is estimated using Ra_max, φd_min becomes smaller, which can reduce false negatives.

[0089] (2-2) Number of Thφ It is also conceivable that a plurality of demagnetization determination values ​​Thφ may be set in correspondence with φd_max corresponding to Ra_min and φd_min corresponding to Ra_max.

[0090] (3) Number of estimated values ​​of φd and number of Thφ and combination method Taking into consideration the tolerance and detection rate of demagnetization determination, a plurality of demagnetization determination methods can be considered by setting the number of estimated values ​​of φd and the number of demagnetization determination values ​​Thφ and the combination method.

[0091] (3-1) Using one estimated value of φd and one Thφ FIG. 8 shows demagnetization determination using one estimated value of φd and one demagnetization determination value Thφ.

[0092] <Pattern 1> The demagnetization determination unit 36 ​​determines that demagnetization has not occurred when the estimated value of φd is greater than the demagnetization determination value Thφ. <Pattern 2> The demagnetization determination unit 36 ​​determines that demagnetization has occurred when the estimated value of φd is smaller than the demagnetization determination value Thφ.

[0093] As will be explained below, the resistance value Ra used to estimate φd may be a fixed value or a variable value, and the resistance value Ra used to set the demagnetization determination value Thφ may be a fixed value or a variable value.

[0094] (3-1-1) When Ra for estimating φd is a fixed value and Ra for setting Thφ is a fixed value For example, the fixed resistance value Ra used to estimate φd is preset to any value within the resistance fluctuation range from Ra_min to Ra_max. The demagnetization determination value Thφ is preset to a value that takes into account the fluctuation range of the estimated value of φd due to fluctuations in the resistance value and errors in the detected values ​​of each sensor, so as to appropriately reduce the occurrence of false positives and false negatives.

[0095] The demagnetization determination value Thφ is set in advance at each operating point. For example, it is set at an operating point of the rotational angular velocity ω and the q-axis current command value Iqo. The demagnetization determination value Thφ is set in advance at each operating point of the rotational angular velocity ω and the q-axis current command value Iqo. For example, the demagnetization determination unit 36 ​​refers to map data in which the relationship between the rotational angular velocity ω, the q-axis current command value Iqo, and the demagnetization determination value Thφ is set in advance, and calculates the demagnetization determination value Thφ corresponding to the current rotational angular velocity ω and the current q-axis current value Iq (in this example, the average value Iqave of the q-axis current value).

[0096] Alternatively, the demagnetization determination unit 36 ​​may use the following equation to calculate the d-axis armature flux linkage φdth for setting a judgment value based on the rotational angular velocity ω and the q-axis current value Iq (Iqave in this example), the q-axis voltage command value Vqoth for setting a judgment value, and the fixed resistance value Rath for setting a judgment value, and set the demagnetization determination value Thφ by subtracting the offset value Δφ from the d-axis armature flux linkage φdth for setting a judgment value.

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[0097] Here, Vqoth is a q-axis voltage command value for setting a judgment value, and is set in advance to the q-axis voltage command value Vqo when demagnetization has not occurred. The q-axis voltage command value Vqoth for setting a judgment value is set in advance for each operating point. For example, the demagnetization determination unit 36 ​​refers to map data in which the relationship between the rotational angular velocity ω, the q-axis current value Iq, and the q-axis voltage command value Vqoth for setting a judgment value is set in advance, and calculates the q-axis voltage command value Vqoth for setting a judgment value that corresponds to the current rotational angular velocity ω and the q-axis current value Iq. The offset value Δφ and the fixed resistance value Rath are set in advance to appropriately reduce the occurrence of false positives and false negatives, taking into account fluctuations in the resistance values ​​and the fluctuation range of the estimated value of φd due to errors in the values ​​detected by each sensor.

[0098] Alternatively, the demagnetization determination value Thφ may be set to a value corresponding to the above-mentioned φd_min_ass. In this case, the demagnetization determination unit 36 ​​sets the demagnetization determination value Thφ using a preset minimum value Vqo_min of the fluctuation range of the q-axis voltage command value when demagnetization does not occur as the q-axis voltage command value Vqoth for setting the determination value, and a preset maximum value Ra_max of the fluctuation range of the resistance value as the fixed resistance value Rath for setting the determination value. The minimum value Vqo_min of the fluctuation range of the q-axis voltage command value when demagnetization does not occur is set in advance for each operating point (rotational angular velocity ω and q-axis current value Iq). In this case, the demagnetization determination value Thφ is set using equations (23) and (24), and the offset value Δφ is set to 0.

[0099] Alternatively, the demagnetization determination value Thφ may be set to a value corresponding to the above-mentioned φd_max_ass. In this case, the demagnetization determination unit 36 ​​sets the demagnetization determination value Thφ using a maximum value Vqo_max of the fluctuation range of the q-axis voltage command value when demagnetization has not occurred as the q-axis voltage command value Vqoth for setting the determination value, and using a minimum value Ra_min of the fluctuation range of the resistance value set in advance as the fixed resistance value Rath for setting the determination value. The maximum value Vqo_max of the fluctuation range of the q-axis voltage command value when demagnetization has not occurred is set in advance for each operating point (rotational angular velocity ω and q-axis current value Iq). In this case, the demagnetization determination value Thφ is set using equations (23) and (24), and the offset value Δφ is set to 0.

[0100] (3-1-2) When Ra for estimating φd is a fixed value and Ra for setting Thφ is a variable value In this case, by using a variable resistance value Ra to set the demagnetization determination value Thφ, it is possible to prevent the demagnetization determination value Thφ from fluctuating in response to fluctuations in the resistance value. However, because a fixed resistance value Ra is used to estimate φd, the estimated value of φd fluctuates due to fluctuations in the resistance value and errors in the values ​​detected by each sensor. Therefore, as in (3-1-1), it is necessary to set the demagnetization determination value Thφ taking into account the fluctuation range of the estimated value of φd, and therefore there is little advantage to using a variable resistance value Ra. Therefore, a description thereof will be omitted.

[0101] (3-1-3) When Ra for estimating φd is a variable value and Ra for setting Thφ is a fixed value In this case, as described above, fluctuations in the estimated value of φd due to fluctuations in the resistance value are reduced, thereby improving the estimation accuracy of φd. Therefore, the demagnetization determination value Thφ is preset to a value that takes into account the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor and that appropriately reduces the occurrence of false positives and false negatives. For example, the demagnetization determination value Thφ may be preset to a value smaller than the minimum value φd_minerr of the estimated value of φd that takes into account errors in the detected values ​​of each sensor. Estimating φd using a variable resistance value Ra can improve the accuracy of demagnetization determination. Furthermore, it is possible to set the demagnetization determination value Thφ so that minute demagnetization can be detected. As in (3-1-1), the demagnetization determination value Thφ is preset at each operating point.

[0102] (3-1-4) When Ra for estimating φd is a variable value and Ra for setting Thφ is a variable value In this case, for example, using the following equation, the demagnetization determination unit 36 ​​calculates the d-axis armature flux linkage φdth for setting the determination value based on the rotational angular velocity ω, the q-axis current value Iq (Iqave in this example), the q-axis voltage command value Vqoth for setting the determination value, and the resistance value Ra estimated in accordance with the winding temperature acquired by the winding temperature acquisition unit 37, and sets the demagnetization determination value Thφ by subtracting the offset value Δφ from the d-axis armature flux linkage φdth for setting the determination value.

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[0103] Here, Vqoth is a q-axis voltage command value for setting the judgment value, and is set in advance to the q-axis voltage command value Vqo when demagnetization has not occurred. As with equation (23) in (3-1-1), the q-axis voltage command value Vqoth for setting the judgment value is set in advance at each operating point. The offset value Δφ is set so that the estimated value of φd and the demagnetization judgment value Thφ do not become too close when demagnetization has not occurred. In addition, the offset value Δφ is set in advance to a value that appropriately reduces the occurrence of false positives and false negatives, taking into account the range of fluctuation in the estimated value of φd due to errors in the detected values ​​of each sensor.

[0104] (3-2) Using one estimate of φd and two estimates of Thφ FIG. 9 shows demagnetization determination using one estimated value of φd and two demagnetization determination values ​​Thφ.

[0105] The demagnetization determination unit 36 ​​uses a larger demagnetization determination value ThφH and a smaller demagnetization determination value ThφL that is smaller than the larger demagnetization determination value ThφH. By using the two demagnetization determination values ​​ThφH and ThφL, the occurrence of false positives and false negatives can be individually adjusted.

[0106] <Pattern 1> The demagnetization determination unit 36 ​​determines that demagnetization has not occurred when the estimated value of φd is larger than the larger demagnetization determination value ThφH. <Pattern 2> When the estimated value of φd falls between the smaller demagnetization determination value ThφL and the larger demagnetization determination value ThφH, the demagnetization determination unit 36 ​​may determine that demagnetization has occurred, or may determine that demagnetization has not occurred. For example, when the occurrence of false positives is suppressed, it is determined that demagnetization has not occurred. When the occurrence of false negatives is suppressed, it is determined that demagnetization has occurred. <Pattern 3> The demagnetization determination unit 36 ​​determines that demagnetization has occurred when the estimated value of φd is smaller than the smaller demagnetization determination value ThφL.

[0107] As will be explained below, the resistance value Ra used to estimate φd may be a fixed value or a variable value, and the resistance value Ra used to set the demagnetization determination value Thφ may be a fixed value or a variable value.

[0108] (3-2-1) When Ra for estimating φd is a fixed value, and Ra for setting ThφH and ThφL is a fixed value The difference from (3-1-1) when one demagnetization judgment value is provided is that by providing two demagnetization judgment values, the demagnetization judgment value can be changed according to the demagnetization detection level, increasing the degree of freedom in demagnetization judgment.

[0109] For example, the smaller demagnetization determination value ThφL is set corresponding to the maximum value Ra_max of the resistance value fluctuation range. For example, the demagnetization determination unit 36 ​​sets the smaller demagnetization determination value ThφL using the following equation. The demagnetization determination unit 36 ​​sets the larger demagnetization determination value ThφH by adding an offset value ΔφH to the smaller demagnetization determination value ThφL. Here, the offset value ΔφH is set in advance to a value that appropriately reduces the occurrence of false positives and false negatives, taking into account the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor. The other parameters are the same as those described above, so their description will be omitted.

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[0110] Alternatively, the larger demagnetization determination value ThφH is set corresponding to the minimum value Ra_min of the resistance value fluctuation range. For example, the demagnetization determination unit 36 ​​sets the larger demagnetization determination value ThφH using the following equation. The demagnetization determination unit 36 ​​subtracts an offset value ΔφL from the larger demagnetization determination value ThφH to set the smaller demagnetization determination value ThφL. Here, the offset value ΔφL is set in advance to a value that appropriately reduces the occurrence of false positives and false negatives, taking into account the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor. The other parameters are the same as those described above, so their description will be omitted.

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[0111] Alternatively, the smaller demagnetization determination value ThφL is set corresponding to the maximum value Ra_max of the resistance value fluctuation range, and the larger demagnetization determination value ThφH is set corresponding to the minimum value Ra_min of the resistance value fluctuation range. For example, Equations (27) and (29) are used.

[0112] (3-2-2) When Ra for estimating φd is a variable value and Ra for setting ThφH and ThφL is a fixed value In this case, as explained in (3-1-3), fluctuations in the estimated value of φd due to fluctuations in the resistance value are reduced, thereby improving the accuracy of φd estimation. Therefore, ThφH and ThφL are set in advance to values ​​that take into account the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor, and that appropriately reduce the occurrence of false positives and false negatives. For example, ThφL may be set corresponding to the minimum value φd_minerr of the estimated value of φd taking into account errors in the detected values ​​of each sensor. ThφH may be set corresponding to the maximum value φd_maxerr of the estimated value of φd taking into account errors in the detected values ​​of each sensor. As in (3-1-1), ThφH and ThφL are set in advance at each operating point.

[0113] (3-2-3) When Ra for estimating φd is a variable value, and Ra for setting ThφH and ThφL is a variable value In this case, for example, using the following equation, which is similar to equation (25) in (3-1-4), the demagnetization determination unit 36 ​​calculates the d-axis armature flux linkage φdth for setting the determination value based on the resistance value Ra estimated in accordance with the winding temperature acquired by the winding temperature acquisition unit 37, subtracts an offset value ΔφL from the d-axis armature flux linkage φdth for setting the determination value to set ThφL, and adds an offset value ΔφH to the d-axis armature flux linkage φdth for setting the determination value to set ThφH.

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[0114] The parameters in equation (31) are the same as those in equation (25), and therefore will not be described here. The offset value ΔφL is set in consideration of the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor, and the occurrence of false negatives. The offset value ΔφH is set in consideration of the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor, and the occurrence of false positives. By adjusting ΔφL and ΔφH, the occurrence of false positives and false negatives can be adjusted individually. ΔφL may be set to 0, or ΔφH may be set to 0.

[0115] (3-3) Using two estimates of φd and one Thφ Fig. 10 shows demagnetization determination using two estimated values ​​of φd and one demagnetization determination value Thφ. Here, the region where demagnetization may not occur is an error region that occurs mainly between the actual resistance value and the fixed resistance value, and is the range of fluctuation of the estimated value of φd when demagnetization has not occurred. The region where demagnetization may occur is the range of fluctuation of the estimated value of φd that may change depending on the degree of demagnetization.

[0116] The flux linkage estimation unit 35 estimates an estimated value φdH of the armature flux linkage on the larger d-axis and an estimated value φdL of the armature flux linkage on the smaller d-axis.

[0117] <Pattern 1> The demagnetization determination unit 36 ​​determines that demagnetization has not occurred when the estimated value φdL of the smaller interlinkage magnetic flux is greater than the demagnetization determination value Thφ. <Pattern 2> When the demagnetization determination value Thφ is between the estimated value φdL of the smaller side interlinkage magnetic flux and the estimated value φdH of the larger side interlinkage magnetic flux, the demagnetization determination unit 36 ​​may determine that demagnetization has occurred, or may determine that demagnetization has not occurred. For example, when the occurrence of false positives is suppressed, it is determined that demagnetization has not occurred. When the occurrence of false negatives is suppressed, it is determined that demagnetization has occurred. <Pattern 3> The demagnetization determination unit 36 ​​determines that demagnetization has occurred when the estimated value φdH of the larger interlinkage magnetic flux is smaller than the demagnetization determination value Thφ.

[0118] As will be explained below, the resistance value Ra used to estimate φd may be a fixed value or a variable value, and the resistance value Ra used to set the demagnetization determination value Thφ may be a fixed value or a variable value.

[0119] (3-3-1) When Ra for estimating φdH and φdL is a fixed value, and Ra for setting Thφ is a fixed value For example, using the following equation corresponding to equation (17), the flux linkage estimation unit 35 estimates the estimated value φdH of the armature flux linkage on the larger d-axis by using the minimum value Ra_min of the preset resistance fluctuation range.

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[0120] Using the following equation corresponding to equation (17), the flux linkage estimation unit 35 estimates an estimated value φdL of the armature flux linkage on the smaller d-axis using a maximum value Ra_max in a preset resistance fluctuation range.

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[0121] According to this configuration, if φdH estimated using the minimum value Ra_min of the resistance fluctuation range falls below Thφ, it can be accurately determined that demagnetization has occurred, taking into account the fluctuations in the resistance value. If φdL estimated using the maximum value Ra_max of the resistance fluctuation range exceeds Thφ, it can be accurately determined that demagnetization has not occurred, taking into account the fluctuations in the resistance value. The demagnetization determination value Thφ is preset to a value that takes into account the fluctuation range of the estimated value of φd due to errors in the detected values ​​of each sensor and that appropriately reduces the occurrence of false positives and false negatives. As in (3-1-1), the demagnetization determination value Thφ is preset for each operating point.

[0122] Alternatively, if the demagnetization judgment value Thφ is set corresponding to the maximum value Ra_max(φd_min) or φd_minerr of the resistance value fluctuation range, if φdH estimated using Ra_min is below the demagnetization judgment value Thφ, it can be reliably determined that demagnetization has occurred, and the occurrence of false negatives can be suppressed.

[0123] Alternatively, if the demagnetization judgment value Thφ is set corresponding to the minimum value Ra_min(φd_max) or φd_maxerr of the resistance value fluctuation range, if φdL estimated using Ra_max exceeds the demagnetization judgment value Thφ, it can be determined with certainty that demagnetization has not occurred, and the occurrence of false positives can be suppressed.

[0124] Furthermore, in the <Pattern 2> region where it is not possible to determine whether demagnetization has occurred, in order to minimize the occurrence of false positives, it is sufficient to compare only φdH with Thφ to determine demagnetization, and in order to minimize the occurrence of false negatives, it is sufficient to compare only φdL with Thφ to determine demagnetization.

[0125] (3-3-2) When Ra for estimating φdH and φdL is a variable value and Ra for setting Thφ is a fixed value When the estimation Ra is a variable value, the accuracy of the estimated value of φd increases and there is no need to provide multiple estimated values ​​of φd, so the explanation will be omitted.

[0126] (3-3-3) When Ra for estimating φdH and φdL is a variable value, and Ra for setting Thφ is a variable value Similarly, when the estimation Ra is a variable value, the accuracy of the estimated value of φd increases and there is no need to provide multiple estimated values ​​of φd, so the explanation will be omitted.

[0127] (3-4) Using two estimated values ​​of φd and two Thφ 11 shows demagnetization determination using two estimated values ​​of φd and two demagnetization determination values ​​Thφ. Flux linkage estimation unit 35 estimates an estimated value φdH of the armature flux linkage on the larger d-axis and an estimated value φdL of the armature flux linkage on the smaller d-axis. Demagnetization determination unit 36 ​​uses the larger demagnetization determination value ThφH and the smaller demagnetization determination value ThφL.

[0128] <Pattern 1> The demagnetization determination unit 36 ​​determines that demagnetization has not occurred when the estimated value φdH of the larger side interlinkage magnetic flux and the estimated value φdL of the smaller side interlinkage magnetic flux are greater than the larger side demagnetization determination value ThφH.

[0129] <Pattern 2> When the estimated value φdH of the larger side interlinkage magnetic flux is larger than the larger side demagnetization judgment value ThφH and the estimated value φdL of the smaller side interlinkage magnetic flux is between the estimated value φdL of the smaller side interlinkage magnetic flux and the estimated value φdH of the larger side interlinkage magnetic flux, the demagnetization judgment unit 36 ​​may determine that demagnetization has occurred when the larger side demagnetization judgment value ThφH is used for the demagnetization judgment, or may determine that demagnetization has not occurred, or when the smaller side demagnetization judgment value ThφL is used for the demagnetization judgment, the demagnetization judgment unit 36 ​​may determine that demagnetization has not occurred.

[0130] <Pattern 3> When the estimated value φdH of the larger side interlinkage magnetic flux is larger than the larger side demagnetization judgment value ThφH and the estimated value φdL of the smaller side interlinkage magnetic flux is smaller than the estimated value φdL of the smaller side interlinkage magnetic flux, the demagnetization judgment unit 36 ​​may determine that demagnetization has occurred or that demagnetization has not occurred if the larger side demagnetization judgment value ThφH is used for demagnetization judgment, or may determine that demagnetization has occurred or that demagnetization has not occurred if the smaller side demagnetization judgment value ThφL is used for demagnetization judgment.

[0131] <Pattern 4> When the estimated value φdH of the larger side interlinkage magnetic flux and the estimated value φdL of the smaller side interlinkage magnetic flux are between the estimated value φdL of the smaller side interlinkage magnetic flux and the estimated value φdH of the larger side interlinkage magnetic flux, the demagnetization judgment unit 36 ​​determines that demagnetization has occurred if the larger side demagnetization judgment value ThφH is used for the demagnetization judgment, or determines that demagnetization has not occurred if the smaller side demagnetization judgment value ThφL is used for the demagnetization judgment.

[0132] <Pattern 5> When the estimated value φdH of the larger side interlinkage magnetic flux is between the estimated value φdL of the smaller side interlinkage magnetic flux and the estimated value φdH of the larger side interlinkage magnetic flux, and when the estimated value φdL of the smaller side interlinkage magnetic flux is smaller than the estimated value φdL of the smaller side interlinkage magnetic flux, the demagnetization judgment unit 36 ​​determines that demagnetization has occurred if the larger side demagnetization judgment value ThφH is used for demagnetization judgment, or may determine that demagnetization has occurred or not if the smaller side demagnetization judgment value ThφL is used for demagnetization judgment.

[0133] <Pattern 6> The demagnetization determination unit 36 ​​determines that demagnetization has occurred when the estimated value φdH of the larger side interlinkage magnetic flux and the estimated value φdL of the smaller side interlinkage magnetic flux are smaller than the smaller side demagnetization determination value ThφL.

[0134] As will be explained below, the resistance value Ra used to estimate φd may be a fixed value or a variable value, and the resistance value Ra used to set the demagnetization determination value Thφ may be a fixed value or a variable value.

[0135] (3-4-1) When Ra for estimating φdH and φdL is a fixed value, and Ra for setting ThφH and ThφL is a fixed value As in (3-3-1), the flux linkage estimation unit 35 uses the formula (34) to estimate the estimated value φdH of the armature flux linkage on the larger d-axis by using the minimum value Ra_min of the preset resistance variation range.Furthermore, the flux linkage estimation unit 35 uses the formula (35) to estimate the estimated value φdL of the armature flux linkage on the smaller d-axis by using the maximum value Ra_max of the preset resistance variation range.

[0136] As in (3-2-1), using equations (27) and (28), the smaller demagnetization judgment value ThφL is set corresponding to the maximum value Ra_max of the resistance value fluctuation range, and the larger demagnetization judgment value ThφH is set by adding an offset value ΔφH to the smaller demagnetization judgment value ThφL.

[0137] When ThφH and ThφL are set in this manner, in <Pattern 3> and <Pattern 5>, which were previously indefinite, the demagnetization judgment unit 36 ​​can uniquely determine that demagnetization has definitely occurred if the estimated value φdL of the smaller side interlinkage magnetic flux is smaller than the smaller side demagnetization judgment value ThφL.

[0138] Alternatively, similar to (3-2-1), using equations (29) and (30), the larger demagnetization judgment value ThφH may be set corresponding to the minimum value Ra_min of the resistance value fluctuation range, and the smaller demagnetization judgment value ThφL may be set by subtracting the offset value ΔφL from the larger demagnetization judgment value ThφH.

[0139] When ThφH and ThφL are set in this manner, in <Pattern 2> and <Pattern 3> where the judgment results were indeterminate, the demagnetization judgment unit 36 ​​can uniquely judge that demagnetization has not occurred if the estimated value φdH of the larger side interlinkage magnetic flux is larger than the larger side demagnetization judgment value ThφH.

[0140] Alternatively, similar to (3-2-1), the smaller demagnetization judgment value ThφL may be set corresponding to the maximum value Ra_max of the resistance value fluctuation range using equations (27) and (28), and the larger demagnetization judgment value ThφH may be set corresponding to the minimum value Ra_min of the resistance value fluctuation range using equations (29) and (30).

[0141] When ThφH and ThφL are set in this manner, it can be determined that demagnetization has definitely occurred if the estimated value φdL of the smaller interlinkage magnetic flux is lower than the smaller demagnetization judgment value ThφL in <Pattern 3> and <Pattern 5>, where the judgment result was indeterminate. Also, it can be determined that demagnetization has definitely not occurred if the estimated value φdH of the larger interlinkage magnetic flux is higher than the larger demagnetization judgment value ThφH in <Pattern 2> and <Pattern 3>, where the judgment result was indeterminate.

[0142] <Correction of Thφ using rotational angular velocity ω> As explained using Equation (17) and Equation (23), the estimated value of φd changes inversely proportional to the rotational angular velocity ω, and the demagnetization determination value Thφ changes inversely proportionally to the rotational angular velocity ω. Therefore, in a region where the rotational angular velocity ω is low, even a slight fluctuation in the rotational angular velocity ω causes the estimated value of φd and the demagnetization determination value Thφ to fluctuate significantly. Therefore, in a low rotational velocity region, an unexpected estimated value of φd and a demagnetization determination value Thφ may be calculated, leading to an erroneous determination that demagnetization has occurred. Therefore, to prevent an easy determination that demagnetization has occurred, the demagnetization determination unit 36 ​​may correct the demagnetization determination value Thφ based on the rotational angular velocity ω. When the rotational angular velocity ω is in a predetermined low rotational velocity region, the demagnetization determination unit 36 ​​decreases and corrects the demagnetization determination value Thφ. For example, the demagnetization determination unit 36 ​​multiplies each demagnetization determination value Thφ calculated using Equation (23), Equation (24), etc. by a correction coefficient and sets the resulting value as the corrected demagnetization determination value Thφ. When the rotational angular velocity ω is in the low rotation region, the correction coefficient is set to less than 1, and when the rotational angular velocity ω is not in the low rotation region or the high rotation region, the correction coefficient is set to 1.

[0143] On the other hand, in a high rotational speed region where the rotational angular velocity ω is high, the maximum output torque is low, which tends to reduce the q-axis current value Iq. As a result, the estimated value of φd and the demagnetization determination value Thφ become smaller, and the amount of fluctuation between them often becomes smaller. To reduce false negatives in such a high rotational speed region, the demagnetization determination unit 36 ​​increases the demagnetization determination value Thφ when the rotational angular velocity ω is in a predetermined high rotational speed region. For example, the demagnetization determination unit 36 ​​multiplies each demagnetization determination value Thφ calculated using equations (23) and (24), etc., by a correction coefficient and sets the resulting value as the corrected demagnetization determination value Thφ. When the rotational angular velocity ω is in the high rotational speed region, the correction coefficient is set to be greater than 1. When the rotational angular velocity ω is not in the high rotational speed region or the low rotational speed region, the correction coefficient is set to 1. Note that either the correction for the low rotational speed region or the correction for the high rotational speed region may be performed.

[0144] <Switching between performing and not performing demagnetization judgment according to the operating point> The demagnetization determination unit 36 ​​determines whether or not to perform a demagnetization determination based on the rotational angular velocity ω, the voltage command value, and the current value, and if it is determined that a demagnetization determination should be performed, it determines whether or not demagnetization has occurred, and if it is determined that a demagnetization determination should not be performed, it does not determine whether or not demagnetization has occurred.

[0145] As shown in FIG. 12, for example, at a certain operating point, the estimated value of φd may fluctuate periodically. At this operating point, the estimated value of φd may not be constant and may oscillate around the demagnetization determination value Thφ. At such an operating point, the accuracy of the demagnetization determination decreases, so it is better not to perform the demagnetization determination. Therefore, by setting an operating point at which the accuracy of the demagnetization determination decreases as an operating point at which the demagnetization determination is not performed, the accuracy of the demagnetization determination can be improved. At an operating point at which the estimated value of φd increases, the difference with the demagnetization determination value Thφ increases, reducing the possibility of erroneous determination and improving the accuracy of the demagnetization determination. Therefore, by setting an operating point at which the accuracy of the demagnetization determination improves as an operating point at which the demagnetization determination is performed, the accuracy of the demagnetization determination can be improved.

[0146] <Changes in demagnetization judgment value Thφ due to field current value If> The demagnetization determination unit 36 ​​may change the demagnetization determination value Thφ based on the field current value If. In this embodiment, as shown in equation (2), the armature flux linkage φa changes depending on the field current value If, ​​and as shown in equation (10), the armature flux linkage φd on the d-axis changes depending on the armature flux linkage φa which changes depending on the field current value If.

[0147] As can be seen from equation (10), when the field current value If changes and the d-axis armature flux linkage φd changes, the d-axis voltage command value Vqo and the d-axis current value Iq change automatically, and therefore the estimated value of φd and the demagnetization determination value Thφ also change automatically in response to the changes in the d-axis voltage command value Vqo and the d-axis current value Iq. Therefore, basically, the accuracy of the demagnetization determination can be maintained even if the field current value If changes.

[0148] In detail, in this embodiment, the q-axis current command value Iqo is set based on the rotational angular velocity ω and the torque command value, and the field current command value Ifo is set based on the rotational angular velocity ω and the torque command value. Therefore, the q-axis current value Iq, the field current value If, ​​and the rotational angular velocity ω correspond uniquely to one another, and the q-axis voltage command value Vqo also corresponds uniquely to the q-axis current value Iq, the field current value If, ​​and the rotational angular velocity ω. Therefore, the q-axis voltage command value Vqoth for setting a judgment value, which is set in advance for each operating point of the rotational angular velocity ω and the q-axis current value Iq (or torque command value), also corresponds uniquely to the q-axis current value Iq, the field current value If, ​​and the rotational angular velocity ω. In other words, the field current value If and the q-axis voltage command value Vqoth for setting a judgment value correspond uniquely to one another via the reference parameters of the rotational angular velocity ω and the q-axis current value Iq (or torque command value). Therefore, even if the field current value If changes, the accuracy of the demagnetization judgment can be maintained.

[0149] However, unlike the present embodiment, when the field current value If and the q-axis voltage command value Vqoth for setting the judgment value do not uniquely correspond via a reference parameter, it is necessary to change the demagnetization judgment value Thφ in accordance with changes in the field current value If in order to maintain judgment accuracy.

[0150] Therefore, the demagnetization determination unit 36 ​​corrects the demagnetization determination value Thφ based on the field current value If. For example, a reference field current value If0 when the q-axis voltage command value Vqoth for setting the determination value is set is set in advance for each operating point of the rotational angular velocity ω and the q-axis current value Iq (or torque command value). As shown in the following equation, the demagnetization determination unit 36 ​​adds a value obtained by multiplying the fluctuation amount ΔIf (=If-If0) of the field current value obtained by subtracting the reference field current value If0 corresponding to the current operating point from the current field current value If by the inductance Lf of the field winding to the reference demagnetization determination value Thφ set using the q-axis voltage command value Vqoth for setting the determination value according to equations (23) and (24), etc., to correct the demagnetization determination value Thφ. Here, the field current value If is the field current detection value Ifs or the field current command value Ifo.

number

[0151] <Other embodiments> In the above embodiment, the rotor 14 is provided with the permanent magnets 12 and the field winding 7. However, the rotor 14 may not be provided with the field winding 7, but may be provided with the permanent magnets 12.

[0152] In each of the above embodiments, two sets of armature windings are provided, but one set or three or more sets of armature windings may be provided.

[0153] In the above embodiments, each set is provided with a three-phase armature winding. However, each set may be provided with armature windings of multiple phases other than three (for example, two or four phases).

[0154] Although exemplary embodiments are described in this application, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes modifying, adding, or omitting at least one component. [Explanation of symbols]

[0155] 1 AC rotating machine, 7 field winding, 12 permanent magnet, 30 AC rotating machine control device, 31 rotation detection unit, 32 current detection unit, 33 voltage command value calculation unit, 34 switching control unit, 35 flux linkage estimation unit, 36 demagnetization judgment unit, 37 winding temperature acquisition unit, Iq q-axis current value, Ra resistance value, Ra_max maximum value of resistance value fluctuation range, Ra_min minimum value of resistance value fluctuation range, Rath resistance value for judgment value setting, Thφ demagnetization judgment value, ThφH large side demagnetization judgment value, ThφL small side demagnetization judgment value, Vqo q-axis voltage command value, Vqo_max maximum value of q-axis voltage command value fluctuation range, Vqo_min minimum value of q-axis voltage command value fluctuation range, Vqoth q-axis voltage command value for judgment value setting, φd d-axis armature flux linkage estimation value, φdH Estimated value of the armature flux linkage on the larger d-axis, φdL Estimated value of the armature flux linkage on the smaller d-axis, φdth Armature flux linkage on the d-axis for setting the judgment value, ω Rotational angular velocity

Claims

1. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with the flux linkage estimation unit uses a q-axis voltage command value as the voltage command value, uses a q-axis current value as the current value, and estimates a d-axis flux linkage that links with the armature winding as the flux linkage estimate value; The d-axis is set in the direction of the north pole of the magnet, and the q-axis is set in a direction that is 90 electrical degrees ahead of the d-axis. The flux linkage estimation unit, assuming that the q-axis voltage command value is Vqo, the q-axis current value is Iq, the resistance value is Ra, the rotational angular velocity is ω, and the d-axis flux linkage is φd, φd=(Vqo-Ra×Iq) / ω The d-axis interlinkage magnetic flux is estimated using the calculation formula: the flux linkage estimation unit estimates the flux linkage of the d-axis on the larger side by using a minimum value of a preset resistance value fluctuation range as the resistance value, and estimates the flux linkage of the d-axis on the smaller side by using a maximum value of the preset resistance value fluctuation range as the resistance value, The demagnetization determination unit determines that demagnetization has not occurred when the estimated value of the flux linkage of the smaller d-axis is greater than the demagnetization determination value, and determines that demagnetization has occurred when the estimated value of the flux linkage of the larger d-axis is smaller than the demagnetization determination value.

2. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with the flux linkage estimation unit uses a q-axis voltage command value as the voltage command value, uses a q-axis current value as the current value, and estimates a d-axis flux linkage that links with the armature winding as the flux linkage estimate value; The d-axis is set in the direction of the north pole of the magnet, and the q-axis is set in a direction that is 90 electrical degrees ahead of the d-axis. The flux linkage estimation unit, assuming that the q-axis voltage command value is Vqo, the q-axis current value is Iq, the resistance value is Ra, the rotational angular velocity is ω, and the d-axis flux linkage is φd, φd=(Vqo-Ra×Iq) / ω The d-axis interlinkage magnetic flux is estimated using the calculation formula: the flux linkage estimation unit estimates the flux linkage of the d-axis on the larger side by using a minimum value of a preset resistance value fluctuation range as the resistance value, and estimates the flux linkage of the d-axis on the smaller side by using a maximum value of the preset resistance value fluctuation range as the resistance value, the demagnetization determination unit sets a larger demagnetization determination value and a smaller demagnetization determination value that is smaller than the larger demagnetization determination value, a control device for an AC rotating machine that determines that demagnetization has not occurred when the estimated value of the flux linkage on the smaller d-axis is greater than the demagnetization determination value on the larger side, and determines that demagnetization has occurred when the estimated value of the flux linkage on the larger side is smaller than the demagnetization determination value on the smaller side.

3. The demagnetization determination unit A smaller demagnetization determination value corresponding to a maximum value of a preset fluctuation range of the resistance value and a larger demagnetization determination value having a value larger than the smaller demagnetization determination value are set, or a larger demagnetization determination value corresponding to a minimum value of a preset resistance value fluctuation range, and a smaller demagnetization determination value corresponding to a maximum value of a preset resistance value fluctuation range, 3. The control device for an AC rotating machine according to claim 2, wherein it is determined that demagnetization has occurred when the estimated value of the smaller side interlinkage magnetic flux is smaller than the smaller side demagnetization determination value.

4. The demagnetization determination unit A larger demagnetization determination value corresponding to a minimum value of a preset fluctuation range of the resistance value and a smaller demagnetization determination value having a value smaller than the larger demagnetization determination value are set, or a larger demagnetization determination value corresponding to a minimum value of a preset resistance value fluctuation range, and a smaller demagnetization determination value corresponding to a maximum value of a preset resistance value fluctuation range, 3. The control device for an AC rotating machine according to claim 2, wherein it is determined that no demagnetization has occurred when the estimated value of the larger side interlinkage magnetic flux is larger than the larger side demagnetization determination value.

5. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with the flux linkage estimation unit uses a q-axis voltage command value as the voltage command value, uses a q-axis current value as the current value, and estimates a d-axis flux linkage that links with the armature winding as the flux linkage estimate value; The d-axis is set in the direction of the north pole of the magnet, and the q-axis is set in a direction that is 90 electrical degrees ahead of the d-axis. the demagnetization determination unit calculates a d-axis flux linkage for setting a determination value based on the q-axis voltage command value for setting a determination value, the q-axis current value, the resistance value for setting a determination value, and the rotational angular velocity, and sets the demagnetization determination value based on the calculated d-axis flux linkage for setting a determination value.

6. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with the flux linkage estimation unit uses a q-axis voltage command value as the voltage command value, uses a q-axis current value as the current value, and estimates a d-axis flux linkage that links with the armature winding as the flux linkage estimate value; The d-axis is set in the direction of the north pole of the magnet, and the q-axis is set in a direction that is 90 electrical degrees ahead of the d-axis. the demagnetization determination unit defines the voltage command value on the q axis for setting a determination value as Vqoth, the current value on the q axis as Iq, the resistance value for setting a determination value as Rath, the rotational angular velocity as ω, and a d axis interlinkage magnetic flux for setting a determination value that interlinks with the armature winding as φdth, φdth=(Vqoth-Rath×Iq) / ω and sets the demagnetization judgment value based on the calculated d-axis interlinkage magnetic flux for setting the judgment value.

7. the demagnetization determination unit calculates a d-axis flux linkage for setting the determination value using a minimum value of a preset resistance value variation range as the resistance value for setting the determination value, and sets the demagnetization determination value based on the d-axis flux linkage for setting the determination value; 6. The control device for an AC rotating machine according to claim 5, wherein when the estimated value of the flux linkage is larger than the demagnetization determination value, it is determined that demagnetization has not occurred, and when the estimated value of the flux linkage is smaller than the demagnetization determination value, it is determined that demagnetization has occurred.

8. the demagnetization determination unit calculates a d-axis flux linkage for setting the determination value using a maximum value of a preset resistance value variation range as the resistance value for setting the determination value, and sets the demagnetization determination value based on the d-axis flux linkage for setting the determination value; 6. The control device for an AC rotating machine according to claim 5, wherein when the estimated value of the flux linkage is larger than the demagnetization determination value, it is determined that demagnetization has not occurred, and when the estimated value of the flux linkage is smaller than the demagnetization determination value, it is determined that demagnetization has occurred.

9. a winding temperature acquisition unit that detects or estimates the temperature of the armature winding, the demagnetization determination unit estimates the resistance value based on an acquired value of the temperature of the armature winding, calculates a d-axis flux linkage for setting the determination value using the estimated resistance value as the resistance value for setting the determination value, and sets the demagnetization determination value based on the calculated d-axis flux linkage for setting the determination value; 6. The control device for an AC rotating machine according to claim 5, wherein when the estimated value of the flux linkage is larger than the demagnetization determination value, it is determined that demagnetization has not occurred, and when the estimated value of the flux linkage is smaller than the demagnetization determination value, it is determined that demagnetization has occurred.

10. The demagnetization determination unit A larger side d-axis flux linkage for setting the judgment value is calculated using a minimum value of a preset resistance value variation range as the resistance value for setting the judgment value, and the larger side d-axis flux linkage for setting the judgment value is set as the larger side demagnetization judgment value, and a value smaller than the larger side demagnetization judgment value is set as the smaller side demagnetization judgment value, or a minimum value of a preset resistance value variation range is used as the resistance value for setting the judgment value to calculate a larger d-axis flux linkage for setting the judgment value, and the larger d-axis flux linkage for setting the judgment value is set as the larger demagnetization judgment value; a maximum value of a preset resistance value variation range is used as the resistance value for setting the judgment value to calculate a smaller d-axis flux linkage for setting the judgment value, and the smaller d-axis flux linkage for setting the judgment value is set as the smaller demagnetization judgment value; or a maximum value of a preset resistance value fluctuation range is used as the resistance value for setting the judgment value, a smaller d-axis interlinkage magnetic flux for setting the judgment value is calculated, the smaller d-axis interlinkage magnetic flux for setting the judgment value is set as the smaller demagnetization judgment value, and a value larger than the smaller demagnetization judgment value is set as the larger demagnetization judgment value, 6. The control device for an AC rotating machine according to claim 5, wherein when the estimated value of the flux linkage is larger than the larger demagnetization determination value, it is determined that demagnetization has not occurred, and when the estimated value of the flux linkage is smaller than the smaller demagnetization determination value, it is determined that demagnetization has occurred.

11. a winding temperature acquisition unit that detects or estimates the temperature of the armature winding, the demagnetization determination unit estimates the resistance value based on an acquired value of the temperature of the armature winding, calculates a d-axis flux linkage for setting the determination value using the estimated resistance value as the resistance value for setting the determination value, and sets a larger demagnetization determination value and a smaller demagnetization determination value that is smaller than the larger demagnetization determination value based on the calculated d-axis flux linkage for setting the determination value; 6. The control device for an AC rotating machine according to claim 5, wherein when the estimated value of the flux linkage is larger than the larger demagnetization determination value, it is determined that demagnetization has not occurred, and when the estimated value of the flux linkage is smaller than the smaller demagnetization determination value, it is determined that demagnetization has occurred.

12. 6. The control device for an AC rotating machine according to claim 5, wherein the demagnetization determination unit calculates the d-axis flux linkage for setting the judgment value by using a preset q-axis voltage command value when demagnetization has not occurred as the q-axis voltage command value for setting the judgment value.

13. 8. The control device for an AC rotating machine according to claim 7, wherein the demagnetization determination unit calculates the d-axis flux linkage for setting the judgment value by using, as the q-axis voltage command value for setting the judgment value, a maximum value within a predetermined fluctuation range of the q-axis voltage command value when demagnetization does not occur.

14. 9. The control device for an AC rotating machine according to claim 8, wherein the demagnetization determination unit calculates the d-axis flux linkage for setting the judgment value by using, as the q-axis voltage command value for setting the judgment value, a minimum value of a preset fluctuation range of the q-axis voltage command value when demagnetization does not occur.

15. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with The demagnetization determination unit is a control device for an AC rotating machine that corrects the demagnetization determination value based on the rotational angular velocity.

16. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with The demagnetization determination unit determines whether or not to perform a demagnetization determination based on the rotational angular velocity, the voltage command value, and the current value, and, when it determines that the demagnetization determination should be performed, determines whether or not demagnetization of the magnet has occurred.

17. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with the rotor has a field winding; the switching control unit turns on and off a switching element for the field winding included in the power converter to apply a voltage to the field winding; The demagnetization determination unit is a control device for an AC rotating machine that corrects the demagnetization determination value based on a field current value, which is a current value flowing through the field winding.

18. A control device for an AC rotating machine that controls, via a power converter, an AC rotating machine having a rotor provided with a magnet and a stator provided with m sets of armature windings (m is a natural number equal to or greater than 1), a rotation detection unit that detects a rotation angular velocity in electrical angle of the rotor; a voltage command value calculation unit that calculates a voltage command value for each set; a switching control unit that turns on and off a switching element included in the power converter based on the voltage command value for each set to apply a voltage to the armature winding; a flux linkage estimation unit that estimates flux linkage that links with the armature winding based on the m sets of voltage command values, the m sets of current values ​​of the armature windings, the resistance values ​​of the armature windings, and the rotational angular velocity; a demagnetization determination unit that determines whether demagnetization of the magnet has occurred based on a comparison result between the estimated value of the interlinkage magnetic flux and a demagnetization determination value; Equipped with m is a natural number equal to or greater than 2, the voltage command value calculation unit calculates a d-axis voltage command value and a q-axis voltage command value for each set, and calculates a d-axis current detection value, a q-axis current detection value, a d-axis current command value, and a q-axis current command value for each set; the flux linkage estimation unit uses, as the m sets of voltage command values, average values ​​obtained by averaging current m sets of q-axis voltage command values, and uses, as the m sets of current values, average values ​​obtained by averaging current m sets of q-axis current detection values ​​or q-axis current command values, and estimates a d-axis flux linkage as the flux linkage.

19. the rotor has a field winding; the switching control unit turns on and off a switching element for the field winding included in the power converter to apply a voltage to the field winding; 20. The control device for an AC rotating machine according to claim 1, wherein the estimated value of the flux linkage estimated by the flux linkage estimator includes a flux linkage generated by the field winding.

20. a winding temperature acquisition unit that detects or estimates the temperature of the armature winding, 20. The control device for an AC rotating machine according to claim 5 or 18, wherein the flux linkage estimation unit estimates the resistance value based on an acquired value of the temperature of the armature winding, and estimates the flux linkage using the estimated resistance value as the resistance value.

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