JP6544105B2 - Magnet temperature estimation system, motor, and magnet temperature estimation method - Google Patents

Description

  The present invention relates to a magnet temperature estimation system, a motor, and a magnet temperature estimation method.

  As one of synchronous motors, a permanent magnet type motor provided with a permanent magnet in a rotor is known. In such a permanent magnet type motor, a coil provided on the stator generates a rotating magnetic field when power is applied, and the rotating magnetic field acts on the permanent magnet, whereby the rotor is in the stator. Rotate.

  Generally, the higher the rotational speed of the motor, the higher the temperature of the permanent magnet provided on the rotor. In addition, it is known that a permanent magnet irreversibly demagnetizes and loses a magnetic force when a certain upper limit temperature is exceeded. Therefore, it is necessary to measure the temperature of the permanent magnet and to limit the rotational speed of the motor so that the permanent magnet does not reach the upper limit temperature.

  However, using a temperature sensor to measure the temperature of the permanent magnet makes it difficult to miniaturize the motor because the temperature sensor needs to be incorporated into the rotor. Therefore, a method of estimating the temperature of a permanent magnet without using a temperature sensor has been studied. For example, Patent Document 1 discloses a method of estimating the temperature of a permanent magnet using a current applied to a motor and an induced voltage generated in a stator.

JP, 2007-6613, A

  The method disclosed in Patent Document 1 has a problem in that the estimation accuracy of the temperature of the permanent magnet is deteriorated because the induced voltage decreases when the rotational speed of the motor is low.

  The present invention has been made in view of the above problems, and an object thereof is to provide a magnet temperature estimation system, a motor, and a motor capable of improving the estimation accuracy of the temperature of a permanent magnet provided in a rotor of a motor. , And a method of estimating the magnet temperature.

  The magnet temperature estimation system of the present invention includes a motor including a stator including a coil and a rotor including a permanent magnet, and a magnet temperature estimation device for estimating the temperature of the permanent magnet. The rotor is provided in the vicinity of the permanent magnet and has a temperature sensitive magnetic material whose permeability changes in accordance with its own temperature. The magnet temperature estimation device is a power supply unit that applies to the coil an AC power of a driving frequency for driving the rotor to rotate, and a superimposing unit that superimposes AC power of a measurement frequency different from the driving frequency on the AC power of the driving frequency And a temperature estimation unit which measures the impedance based on the AC power at the measurement frequency and estimates the temperature of the permanent magnet according to the measured impedance.

  According to the invention, it is known that the impedance at the measuring frequency measured by the magnet temperature estimation device is correlated with the temperature of the permanent magnet. Therefore, the temperature of the permanent magnet can be estimated by measuring the impedance at the measurement frequency.

  In addition, the temperature-sensitive magnetic material of the rotor increases in temperature and changes in permeability when the temperature of the rotor rises during rotation of the motor, so the amount of magnetic flux between the permanent magnet and the coil of the stator Changes. Therefore, the inductance component in the impedance of the harmonic component changes. Here, since the temperature sensitive magnetic substance has a large amount of change in permeability with temperature, the amount of change in impedance at the measurement frequency per unit temperature becomes large, and the correlation between the impedance at the measurement frequency and the temperature of the permanent magnet Becomes noticeable. Therefore, since the magnet temperature estimation device can estimate the temperature of the permanent magnet with high accuracy, the estimation accuracy of the temperature of the permanent magnet can be improved.

FIG. 1 is a schematic configuration diagram of a magnet temperature estimation system according to a first embodiment. FIG. 2 is a cross-sectional view of the motor. FIG. 3 is a schematic configuration view of a permanent magnet. FIG. 4 is a diagram showing the temperature characteristics of the temperature sensitive magnetic substance. FIG. 5 is a system configuration diagram of the magnet temperature estimation device. FIG. 6 is a diagram showing an equivalent circuit obtained by modeling a motor. FIG. 7 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm in a general motor. FIG. 8 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm in the motor of this embodiment. FIG. 9 is a cross-sectional view of a part of the motor of the second embodiment. FIG. 10 is a cross-sectional view of a part of the motor of the third embodiment. FIG. 11 is a diagram for explaining the circulation of the temperature sensitive magnetic substance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment
A magnet temperature estimation system according to a first embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a magnet temperature estimation system according to a first embodiment.

  The magnet temperature estimation system 100 includes a motor 1 and a magnet temperature estimation device 2.

  The motor 1 is a permanent magnet type rotary synchronous machine (PMSM: Permanent Magnet Synchronous Motor) operating in three phases. The motor 1 is composed of a hollow cylindrical stator 11 and a rotor 12 rotatably provided in the hollow portion of the stator 11.

  The stator 11 includes a coil, and generates a rotating magnetic field at a predetermined timing when AC power of a predetermined drive frequency is supplied to the coil.

  The rotor 12 is provided with a permanent magnet. The rotating magnetic field generated by the coil of the stator 11 acts on the permanent magnet, whereby the coil and the permanent magnet are attracted or repelled to generate a rotational driving force, and the rotor 12 rotates in the stator 11 .

  The magnet temperature estimation device 2 supplies AC power of the drive frequency to the motor 1 and estimates the temperature of the permanent magnet provided in the rotor 12 of the motor 1.

  Next, with reference to FIG. 2, the detailed configuration of the motor 1 will be described.

  FIG. 2 is a cross-sectional view of the motor 1.

  In the stator 11 of the motor 1, a plurality of slots 21 penetrating in the axial direction of the stator 11 are formed at equal intervals in the circumferential direction of the stator 11. By forming the plurality of slots 21 in the stator 11 in this manner, the teeth 22 are formed between the adjacent slots 21. And the coil 23 is provided so that the teeth 22 may be wound.

  In the rotor 12, an axially extending space 24 is formed, and a permanent magnet 25 is inserted into the space 24. The permanent magnets 25 form a pair so as to substantially face each other, and the paired permanent magnets 25 are provided at equal intervals in the circumferential direction. The substantially opposing permanent magnets 25 are arranged such that the opposing surfaces have the same polarity. In addition, the substantially opposing permanent magnets 25 and the neighboring permanent magnets 25 that are substantially opposing are disposed such that the polarities of the opposing surfaces thereof are different. Specifically, as shown in FIG. 2, when the permanent magnet 25A and the permanent magnet 25D substantially opposite to the permanent magnet 25A and the permanent magnet 25B substantially opposite to each other are provided, the permanent magnet 25A and the permanent magnet are provided. If the opposing surface of 25B is an N pole, the opposing surfaces of the permanent magnet 25C and the permanent magnet 25D become an S pole.

  The coil 23 generates a rotating magnetic field when AC power is applied from the magnet temperature estimation device 2 (not shown in FIG. 2). Since the direction of the rotating magnetic field by the coil 23 changes in accordance with the phase of the applied AC power, the coil 23 and the permanent magnet 25 of the rotor 12 alternately repeat attraction and repulsion to generate a rotational driving force. The rotor 12 rotates in the stator 11.

  In the rotor 12, a temperature sensitive magnetic body 26 is provided in the vicinity of the permanent magnet 25. In the present embodiment, the temperature sensitive magnetic body 26 is provided at a position facing the stator 11 between a pair of substantially facing permanent magnets 25 which is a path of the magnetic flux of the permanent magnet 25. The temperature-sensitive magnetic body 26 is a member whose permeability changes in accordance with its own temperature. Specifically, the temperature sensitive magnetic substance 26 is a liquid ferric colloid, a solid iron-based alloy, or the like. The temperature characteristics of the temperature-sensitive magnetic body 26 will be described later with reference to FIG. When the temperature-sensitive magnetic body 26 is a liquid, a flow path or the like that can be enclosed in the rotor 12 is provided, and the temperature-sensitive magnetic body 26 is sealed in the flow path or the like.

  Next, with reference to FIG. 3, the detailed configuration of the permanent magnet 25 will be described.

  FIG. 3 is a schematic view of the permanent magnet 25. As shown in FIG. The vertical direction in FIG. 3 indicates the axial direction of the rotor 12, that is, the direction toward the paper surface in FIG. Further, a direction parallel to the magnetic flux in FIG. 3 is referred to as a magnetic flux direction, and a lateral direction in FIG. 3 orthogonal to the magnetic flux direction is referred to as a radial direction of the rotor 12.

  The permanent magnet 25 is composed of a plurality of magnet members 31 stacked in the axial direction of the rotor 12. For example, in the case where the motor 1 is used for an electric automobile or the like for which high efficiency operation is required, the permanent magnet 25 is often configured by a plurality of magnet members 31. When the coil 23 generates a rotating magnetic field according to the applied alternating current, an eddy current is generated on the surface of the permanent magnet 25 of the rotor 12 to generate a loss. Therefore, by configuring the permanent magnet 25 with a plurality of magnet members 31, the surface area can be reduced as compared to the case where the permanent magnet 25 is configured with a single magnet member. By doing this, the path of the eddy current is shortened, and the loss due to the eddy current can be reduced.

  FIG. 4 is a graph showing the temperature characteristics of the temperature-sensitive magnetic body 26, in which the temperature is shown on the horizontal axis and the magnetic permeability is shown on the vertical axis. As shown in this figure, when the temperature rises, the temperature-sensitive magnetic body 26 has a small magnetic permeability and it becomes difficult to transmit the magnetic flux. Therefore, as the temperature increases, the amount of magnetic flux between the permanent magnet 25 and the coil 23 of the rotor 12 decreases.

  Next, the magnet temperature estimation device 2 will be described with reference to FIG.

  FIG. 5 is a system configuration diagram of the magnet temperature estimation device 2. Note that the two diagonal lines and the three diagonal lines attached to the input and output lines of each configuration indicate that the values input and output in each configuration are two-dimensional and three-dimensional vectors, respectively.

  As shown in FIG. 5, the magnet temperature estimation device 2 includes a power supply unit 51, an overlapping unit 52, and a magnet temperature estimation unit 53.

Power supply unit 51 outputs to motor 1 three-phase voltages vu, vv and vw which are AC powers of the drive frequency (fundamental wave) according to torque command value Tr ^* input from a controller (not shown) or the like. Thus, the motor 1 is driven to rotate.

In order to estimate the temperature of the permanent magnet 25, harmonic current command values idsc ^* and iqsc ^* of the measurement frequency, which are harmonics higher in frequency than the drive frequency of the fundamental wave, are input to the superimposing unit 52. Then, the superimposing unit 52 outputs harmonic voltage command values vdsc ^* and vqsc ^* according to the input to the power supply unit 51, so that the power of the harmonic component of the AC power supplied to the motor 1 by the power supply unit 51. Is superimposed.

The magnet temperature estimation unit 53 obtains the impedance at the measurement frequency using the input harmonic current command values idsc ^* , iqsc ^* , and the harmonic voltage command values vdsc ^* and vqsc ^*, and uses the obtained impedance for permanent The magnet temperature Tm of the magnet 25 is estimated.

The harmonic current command values idsc ^* and iqsc ^* are command values for supplying the motor 1 with the power of the harmonics used to estimate the temperature of the permanent magnet 25 as described above. The frequencies of the harmonic current command values idsc ^* and iqsc ^* are constant without being changed during the rotation of the motor 1. Further, in the present embodiment, the harmonic current command value iqsc ^* of the q-axis component is set to zero and the harmonic current command value idsc of the d-axis component so as not to cause the motor 1 to generate rotational torque by the command value of the harmonic component. It is assumed that only ^* is changed and input to the magnet temperature estimation device 2. Further, the amplitude of the harmonic current command value is smaller than the amplitude of the fundamental current command value in order to reduce the influence on the motor 1.

  Hereinafter, detailed configurations of the power supply unit 51, the superimposing unit 52, and the magnet temperature estimating unit 53 will be described.

  Power supply unit 51 includes power control unit 510, subtractor 511, current control unit 512, adder 513, coordinate conversion unit 514, power conversion unit 515, current detection unit 516, coordinate conversion unit 517, and band stop filter 518. Equipped with

In power supply unit 51, torque command value Tr ^* of motor 1 is input to power control unit 510, and harmonic voltage command values vdsc ^* and vqsc ^* from resonance control unit 522 of superposition unit 52 are The signal is input to the adder 513. Then, power conversion unit 515 outputs three-phase voltages vu, vv, vw to motor 1 in accordance with these inputs.

Electric power control unit 510 causes motor 1 to generate a desired torque using a table stored in advance from torque command value Tr ^* and estimated temperature Tm of permanent magnet 25 from magnet temperature estimation unit 53. The fundamental wave current command values idsf ^* and iqsf ^* are obtained and output to the subtractor 511. Power control unit 510 may calculate the fundamental wave current command value in accordance with the rotational speed of motor 1 or the magnitude of DC power from a battery (not shown) serving as a drive source of motor 1.

The frequencies of the fundamental wave current command values idsf ^* and iqsf ^* change according to the rotational speed at which the motor 1 is rotated. The fundamental wave current command values idsf ^* and iqsf ^* are represented using rotational coordinate axes (dq axes).

  Here, when the rotational speed of the motor 1 is fast, the magnetic flux of the permanent magnet 25 which alternates the coil 23 increases, so a large counter electromotive force is generated in the stator 11. Therefore, in addition to the current that generates the rotational driving force, a current called field weakening current is applied to the motor 1 to generate a magnetic flux in the opposite direction to the magnetic flux of the permanent magnet 25 and cause the stator 11 to It is carried out to reduce the back electromotive force generated.

  In the present embodiment, as shown in FIG. 2, since the temperature sensitive magnetic body 26 is provided on the rotor 12, as shown in FIG. 4, the magnetic flux of the permanent magnet 25 alternating the coil 23 is sensed as shown in FIG. It changes according to the temperature of the temperature-sensitive magnetic body 26. Further, since the temperature sensitive magnetic body 26 is provided in the vicinity of the permanent magnet 25, the temperatures of the permanent magnet 25 and the temperature sensitive magnetic body 26 can be regarded as the same.

Therefore, the power control unit 510 takes into consideration the torque command value Tr ^* , the temperature of the temperature sensitive magnetic body 26, and the field weakening current according to the change of the magnetic permeability of the temperature sensitive magnetic body 26, which are obtained in advance by design. The corresponding relationship with the current command value stored is stored in the table. Power control unit 510 obtains fundamental wave current command values idsf ^* and iqsf ^* from the torque command value Tr ^* and the estimated temperature Tm of permanent magnet 25 using a table indicating the correspondence relationship stored in advance. it can.

The subtractor 511 subtracts the fundamental wave detection current values idsf and iqsf from the fundamental wave current command values idsf ^* and iqsf ^* , and outputs the subtraction results to the current control unit 512. The fundamental wave detection current values idsf and iqsf are fundamental wave components of the detection value of the current applied to the motor 1.

The current control unit 512 is proportional such that the subtraction results of the subtractor 511 approach zero, that is, the deviations between the fundamental current command values idsf ^* and iqsf ^* and the fundamental current detection values idsf and iqsf disappear. Integral control is performed, and the first voltage command values vd0 ^* and vq0 ^* are output to the adder 513.

The adder 513 adds the harmonic voltage command values vdsc ^* and vqsc ^* output from the resonance control unit 522 of the superimposing unit 52 to the first voltage command values vd0 ^* and vq0 ^* output from the current control unit 512. . Then, the adder 513 outputs the second voltage command values vds ^* and vqs ^{* on} which the harmonic components are superimposed to the coordinate conversion unit 514.

The coordinate conversion unit 514 converts the second voltage command values vds ^* and vqs ^* output from the adder 513 from rotational coordinates (dq axis) to three-phase coordinates (uvw phase), and converts the three-phase voltage The command values vu ^* , vv ^* , vw ^* are calculated. Then, coordinate conversion unit 514 outputs the calculated three-phase voltage command values vu ^* , vv ^* and vw ^* to power conversion unit 515.

The power conversion unit 515 includes, for example, a power conversion circuit configured of a converter and an inverter. In addition, DC power is supplied to the power conversion unit 515 from a battery (not shown). Power conversion unit 515 converts the DC power from the battery into three-phase voltages vu, vv, vw, which are alternating currents, by controlling the inverters according to three-phase voltage command values vu ^* , vv ^* , vw ^* . Output to motor 1 Note that a voltage inverter or a current inverter can be used as the inverter.

  Current detection unit 516 is configured using, for example, a Hall element, and when three-phase voltages vu, vv, vw are applied to motor 1, three-phase current iu flowing from magnet temperature estimation device 2 to motor 1 Detect iv and iw. The current detection unit 516 outputs the detected three-phase currents iu, iv, iw to the coordinate conversion unit 517.

  The coordinate conversion unit 517 performs coordinate conversion from three-phase coordinates to rotational coordinates on the three-phase currents iu, iv, and iw detected by the current detection unit 516 to obtain detection currents ids and iqs. Then, the coordinate conversion unit 517 outputs the obtained detection currents ids and iqs to the band stop filter 518 and the band pass filter 523 of the superimposing unit 52.

  The band stop filter 518 cuts the signal of the frequency band of the superimposed harmonics. Thereby, the band stop filter 518 outputs the fundamental wave detection current values idsf and iqsf obtained by cutting the harmonic components of the detection currents ids and iqs to the subtractor 511.

The superposition unit 52 includes a subtractor 521, a resonance control unit 522, and a band pass filter 523. The superimposing unit 52 adds the harmonic voltage command values vdsc ^* and vqsc ^* to the adder 513 and the magnet temperature estimation unit of the power supply unit 51 according to the input of the harmonic current command values idsc ^* and iqsc ^* to the subtractor 521. Output to 53.

  The band pass filter 523 passes only signals in the harmonic frequency band. Accordingly, the band pass filter 523 outputs the harmonic detection current values idsc and iqsc obtained by cutting the fundamental wave components of the detection currents ids and iqs output from the coordinate conversion unit 517 to the subtractor 521.

The harmonic current command values idsc ^* and iqsc ^* are input to the subtractor 521, and the harmonic detection current values idsc and iqsc from the band pass filter 523 are feedback input. Subtractor 521, the harmonic current command value IDSC ^*, harmonics detection current value IDSC, the Iqsc subtracted from Iqsc ^*, and outputs the subtraction result to the resonance controller 522.

The resonance control unit 522 generates harmonic voltage command values vdsc ^* and vqsc ^* such that the output from the subtractor 521 approaches zero. The resonance control unit 522 then outputs the harmonic voltage command values vdsc ^* and vqsc ^* to the adder 513 of the power supply unit 51 and the temperature estimation unit 531 of the magnet temperature estimation unit 53.

The resonance control unit 522 can arbitrarily set the amplitude of the harmonic voltage command value and the output interval of the harmonic voltage command value. The harmonic voltage command value vqsc ^* of the q-axis component is used to control the rotational torque of the motor 1. Therefore, so as not to affect the rotation torque of the motor 1, the resonance control section 522 outputs zero as the harmonic voltage command value of q-axis component Vqsc ^*, harmonic voltage command values of the d-axis component Vdsc ^* only Changes and outputs.

In the present embodiment, the resonance control unit 522 outputs the harmonic voltage command value vdsc ^* by a Pulsating vector injection method. Specifically, resonance control unit 522 alternately applies positive and negative signs to harmonic voltage command value vdsc ^* and outputs the same. By doing this, in the second voltage command values vds ^* and vqs ^* outputted from the adder 513 as command values to the motor 1, the lead and delay of the harmonic voltage command value vdsc ^{* in} the d-axis direction Will occur alternately.

The magnet temperature estimating unit 53, the harmonic current command value IDSC ^*, with Iqsc ^* is input, the harmonic voltage instruction value vdsc from the resonance control unit 522 of the superimposing unit 52 ^*, vqsc ^* is input. As described above, the harmonic current command value iqsc ^* of the q-axis component and the harmonic voltage command value vqsc ^* are zero. The magnet temperature estimation unit 53 estimates the temperature of the permanent magnet 25 according to the impedance measured using the harmonic voltage command value and the harmonic current command value.

The magnet temperature estimation unit 53 has a band pass filter (not shown) according to the frequency of the harmonic to be superimposed, and the harmonic voltage command value vdsc ^* applied by the pulsating vector injection method is obtained ^. Extract either positive or negative values. The magnet temperature estimation unit 53 can calculate the impedance Zh of the harmonic component using the inputted harmonic current command value idsc ^* and the harmonic voltage command value vdsc ^* that has passed through the band pass filter.

  Here, it is known that the real part Rd of the impedance Zh of the harmonic component has a correlation with the temperature of the permanent magnet 25 of the stator 11. Therefore, the magnet temperature estimation unit 53 stores in advance a table indicating the correlation between the real part Rd of the harmonic impedance and the temperature of the permanent magnet 25, and stores it as the calculated real part Rd of the harmonic impedance. The temperature of the permanent magnet 25 can be estimated using a table showing the correlation.

  Here, the correlation between the real part Rd of the harmonic impedance measured by the magnet temperature estimation unit 53 and the temperature of the permanent magnet 25 will be described with reference to FIG.

  FIG. 6 is a diagram showing an equivalent circuit obtained by modeling a general motor whose magnet temperature is estimated by the magnet temperature estimation device 2. FIG. 6 (a) shows the configuration of the motor, and FIG. 6 (b) shows a magnetic flux circuit equivalent to the motor of FIG. 6 (a). It is assumed that the temperature sensitive magnetic body 26 is not provided on the rotor 12 of the motor 1 in this figure.

  In this figure, harmonic components of the three-phase voltages vu, vv, vw output from the power conversion unit 515 shown in FIG. 5 are applied to the coil 23 as the harmonic voltage Vh. The harmonic component of the current applied to the coil 23 is shown as a harmonic current Ih. The harmonic current Ih is a harmonic component of the three-phase current iu, iv, iw detected by the current detection unit 516 in FIG.

  Referring to FIG. 6, when harmonic voltage Vh is applied to coil 23 from magnet temperature estimation device 2 (not shown in FIG. 6), a rotating magnetic field having a harmonic component between coil 23 and permanent magnet 25. Occurs. On the other hand, on the surface of the permanent magnet 25, an eddy current is generated in accordance with the harmonic component of the rotating magnetic field generated by the coil 23. Therefore, the permanent magnet 25 has an inductance component. Thus, when the motor 1 is rotating, the stator 11 and the rotor 12 constitute a magnetic flux circuit.

  Here, it is assumed that the coil 23 has a resistance component Rc and an inductance component Lc.

  The permanent magnet 25 has a resistance component Rm and an inductance component Lm. The resistance component Rm of the permanent magnet 25 can be expressed as Rm (Tm) because it changes according to the magnet temperature Tm. Further, since the inductance component Lm of the permanent magnet 25 changes in accordance with the magnet temperature Tm and the harmonic current value Ih, it can be expressed as Lm (Tm, Ih).

  Here, the harmonic impedance Zh is calculated from the harmonic voltage Vh and the harmonic current value Ih using the relationship of Zh = Vh / Ih. In such a case, the real part Rd of the harmonic impedance Zh is expressed by equation (1).

  Here, M is a mutual inductance, and ω is an angular frequency of the harmonic voltage Vh. The mutual inductance M is shown as M (Tm, Ih) because it changes according to the magnet temperature Tm and the harmonic current value Ih. According to the equation (1), the real part Rd of the harmonic impedance has a correlation as shown in FIG. 7 with the magnet temperature Tm which is the temperature of the permanent magnet 25.

  FIG. 7 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm in the motor in which the temperature-sensitive magnetic body 26 is not provided on the rotor 12 as shown in FIG. . The horizontal axis indicates the magnet temperature Tm, and the vertical axis indicates the real part Rd of the harmonic impedance. FIG. 7 shows a correlation in which the real part Rd of the harmonic impedance increases as the magnet temperature Tm increases. Therefore, the magnet temperature estimation unit 53 can estimate the magnet temperature Tm by using the calculated real part Rd of the harmonic impedance and the correlation as shown in FIG. 7.

  Next, as in the present embodiment, a motor in which the rotor 12 includes the temperature sensitive magnetic body 26 will be described. As shown in FIG. 4, the temperature-sensitive magnetic body 26 has its permeability decreased as its temperature rises. Further, as shown in FIG. 2, the temperature sensitive magnetic body 26 is provided between the permanent magnet 25 and the coil 23 of the stator 11. Therefore, when the temperature of the permanent magnet 25 rises and the temperature of the temperature-sensitive magnetic body 26 rises, the magnetic flux between the permanent magnet 25 and the coil 23 of the stator 11 decreases, so the inductance component of the permanent magnet 25 decreases. Lm of becomes smaller. Therefore, the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm, which is obtained by the equation (1), is as shown in FIG.

  FIG. 8 is a view showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm when the temperature sensitive magnetic body 26 is provided on the rotor 12. The horizontal axis indicates the magnet temperature Tm, and the vertical axis indicates the real part Rd of the harmonic impedance. Here, when comparing FIG. 8 in which the temperature sensitive magnetic body 26 is provided with FIG. 7 in which the temperature sensitive magnetic body 26 is not provided, the amount of change per unit temperature of the real part Rd of the harmonic impedance Is larger when the temperature sensitive magnetic body 26 as shown in FIG. 8 is provided. This is because the inductance component Lm of the permanent magnet 25 included in the denominator of the second term in the equation (1) decreases as the temperature rises.

  Therefore, the magnet temperature estimation unit 53 of FIG. 5 can accurately estimate the magnet temperature Tm of the permanent magnet 25 by using the correlation of FIG. 8.

  The following effects can be obtained by the magnet temperature estimation system of the first embodiment.

  According to the magnet temperature estimation system 100 of the first embodiment, in the magnet temperature estimation device 2, the superimposing unit 52 superimposes the power of the harmonic on the power of the fundamental wave supplied from the power supply unit 51 to the motor 1 . Then, the magnet temperature estimation unit 53 measures the impedance Zh of the harmonic component.

  Here, it is known that the real part Rd of the harmonic impedance has a correlation with the temperature of the permanent magnet 25 as shown in the equation (1). Therefore, the magnet temperature estimation unit 53 measures the real part Rd of the harmonic impedance, and uses the measured real part Rd of the harmonic impedance and the table indicating the correlation stored in advance, thereby The temperature can be estimated.

  In the present embodiment, the rotor 12 includes the temperature sensitive magnetic body 26 so that the amount of magnetic flux between the permanent magnet 25 and the coil 23 of the stator 11 corresponds to the temperature of the temperature sensitive magnetic body 26. Change. Therefore, the inductance component Lm of the permanent magnet 25 is affected by the temperature characteristic of the temperature sensitive magnetic body 26. Therefore, the real part Rd of the harmonic impedance represented by the equation (1) has a large amount of change per unit temperature as shown in FIG. 8, so the magnet temperature estimation unit 53 estimates the magnet temperature of the permanent magnet 25. Accuracy can be improved.

  Further, according to the magnet temperature estimation system 100 of the first embodiment, the temperature sensitive magnetic body 26 is provided between the permanent magnet 25 and the coil 23 of the stator 11. Therefore, when the temperature of the temperature sensitive magnetic body 26 rises and the magnetic permeability of the temperature sensitive magnetic body 26 decreases, the amount of magnetic flux between the permanent magnet 25 and the coil 23 of the stator 11 decreases.

  Here, when the rotational speed of the motor 1 is fast, alternating of the magnetic flux of the permanent magnet 25 is frequently performed in the coil 23 of the stator 11, so the back electromotive force generated in the coil 23 becomes large. It will pass. Therefore, it is necessary to apply a field weakening current to the coil 23 of the stator 11 in order to generate a magnetic field in the direction opposite to the direction of the magnetic field of the permanent magnet 25 that generates a back electromotive force.

  However, when the rotational speed of the motor 1 is high, the temperature of the rotor 12 rises, so the temperature of the temperature-sensitive magnetic body 26 rises and the permeability decreases. As the magnetic permeability of the temperature-sensitive magnetic body 26 decreases as described above, the magnetic flux of the permanent magnet 25 alternating with the coil 23 of the stator 11 decreases. Therefore, the back electromotive force is reduced, and the induced power in the coil 23 of the stator 11 is reduced without applying the large field weakening field power, so that the heat generation in the stator 11 is suppressed, and the operation of the motor 1 is performed. Efficiency can be improved.

Further, according to the magnet temperature estimation system 100 of the first embodiment, the power control unit 510 responds to the torque command value Tr ^* and the estimated temperature Tm of the permanent magnet 25 estimated by the magnet temperature estimation unit 53, Fundamental wave current command values idsf ^* and iqsf ^* which are command values to the motor 1 are obtained. By using the estimated temperature Tm of the permanent magnet 25 to calculate the command value of the motor 1 in the power control unit 510, the field weakening current corresponding to the change in the magnetic permeability of the temperature sensitive magnetic body 26 is taken into consideration. Since the command value can be obtained, the operating efficiency of the motor 1 can be improved.

  Further, according to the magnet temperature estimation system 100 of the first embodiment, the temperature sensitive magnetic body 26 may be enclosed in a sealable flow path or the like provided in the rotor 12. In this way, the temperature sensitive magnetic body 26 can be filled without gaps, so that the possibility of the formation of an air layer or the like that generates magnetic flux resistance is reduced as compared with the solid temperature sensitive magnetic body 26. it can. Therefore, the rotation efficiency of the motor 1 can be improved by suppressing the increase of the magnetic resistance.

Second Embodiment
In the first embodiment, an example in which the temperature sensitive magnetic body 26 is provided between the permanent magnet 25 and the rotor 12 has been described, but in the second embodiment, the temperature sensitive magnetic body 26 is the rotor 12. An example provided at another place of will be described.

  FIG. 9 is a cross-sectional view of a part of the motor 1 according to the second embodiment.

  According to FIG. 9, permanent magnet 25 is inserted into space 24 provided in rotor 12. In the space 24, the temperature sensitive magnetic body 26 is disposed in the space between the stator 11 and the radial surface of the permanent magnet 25 shown in FIG. 3. Such an air gap between the radial surface of the permanent magnet 25 and the stator 11 is provided to prevent a short circuit of the magnetic flux from the surface of the N pole of the permanent magnet 25 to the surface of the S pole. The temperature sensitive magnetic body 26 is provided in an air gap which prevents such a short circuit of the magnetic flux.

  The following effects can be obtained by the magnet temperature estimation system of the second embodiment.

  According to the magnet temperature estimation system 100 of the second embodiment, it is provided in the air gap that prevents the short circuit of the magnetic flux of the permanent magnet 25. In general, the permanent magnet 25 generates a very large amount of magnetic flux in a cryogenic state. Therefore, when the motor 1 is used in a cryogenic state, the amount of magnetic flux between the permanent magnet 25 and the coil 23 of the rotor 12 becomes very large, and the stator is rotated with the rotation of the motor 1. The excitation power generated by the coil 23 of 11 may exceed the upper limit allowable in design.

  However, in the extremely low temperature state, the magnetic permeability of the temperature-sensitive magnetic body 26 is increased to easily pass the magnetic flux, so that a part of the magnetic flux of the permanent magnet 25 is short-circuited by the air gap. Therefore, the amount of magnetic flux between the permanent magnet 25 and the coil 23 of the stator 11 is reduced, so that the generated excitation power is reduced, and the motor 1 can be safely driven.

Third Embodiment
In the first and second embodiments, an example in which the temperature sensitive magnetic substance 26 is always in the same place has been described, but the present invention is not limited to this. In the third embodiment, an example in which a heat pump in which the temperature-sensitive magnetic body 26 flows in a flow path provided in the rotor 12 will be described.

  FIG. 10 is a top view of a portion of the motor 1 of the third embodiment.

  In the present embodiment, the temperature sensitive magnetic body 26 is a fluid. A circulation path 1001 is formed in the rotor 12, and a temperature sensitive magnetic body 26 is provided in the circulation path 1001. Further, on the surface of the permanent magnet 25, it is assumed that the end surface on the side of the stator 11 in the radial direction shown in FIG. 3 has the highest temperature when the motor 1 rotates. The temperature distribution in the rotor 12 at the time of such rotation of the motor 1 can be determined by design.

  FIG. 11 is a diagram for explaining the circulation of the temperature sensitive magnetic substance 26. As shown in FIG. The surface N of the permanent magnet 25 shown in this figure is the surface of the N pole, and the surface S is the surface of the S pole. The permanent magnet 25 generates a magnetic flux from the surface N toward the surface S.

  Here, in the area A in the vicinity of the end face on the side of the stator 11 in the radial direction where the temperature is highest during operation of the motor 1 among the surfaces of the permanent magnet 25, from the N pole as shown by the arrow by the permanent magnet 25. A magnetic flux toward the S pole is generated.

  Here, during the operation of the motor 1, the temperature sensitive magnetic substance 26 present in the region A of the circulation path 1001 has a low magnetic permeability because it is high in temperature, and is susceptible to the influence of the magnetic flux. Therefore, the temperature sensitive magnetic substance 26 in the region A receives a force along the direction of the magnetic flux of the permanent magnet 25 indicated by the arrow in the figure, and moves in that direction. On the other hand, since the temperature sensitive magnetic substance 26 present outside the region A of the circulation path 1001 has a low temperature, the magnetic permeability is high and it is hard to be influenced by the magnetic flux. Therefore, as compared with the temperature-sensitive magnetic material 26 in the region A, the temperature-sensitive magnetic material 26 in regions other than the region A is less susceptible to the force by the magnetic flux of the permanent magnet 25. Thus, the temperature sensitive magnetic body 26 in the region A receives a force along the direction of the magnetic flux of the permanent magnet 25, and the temperature sensitive magnetic body 26 other than the region A is hard to receive the force by the permanent magnet 25, The temperature sensitive magnetic substance 26 circulates in the circulation path 1001.

  In addition, the shape of the circulation path 1001 of this embodiment is an example, Comprising: Another shape may be sufficient. For example, the circulation path 1001 may be provided with the permanent magnet 25 spirally in the axial direction of the rotor 12. In such a case, if it is assumed that the circumferential end surface of the permanent magnet 25 has the highest temperature when the motor 1 rotates, the temperature sensitivity in a plurality of locations of the circulation path 1001 of the circumferential end surface of the permanent magnet 25 A force in the magnetic flux direction of the permanent magnet 25 acts on the magnetic body 26.

  The following effects can be obtained by the magnet temperature estimation system of the third embodiment.

  According to the magnet temperature estimation system of the third embodiment, the temperature sensitive magnetic body 26 is provided in the circulation passage 1001 formed in the rotor 12. As shown in FIG. 11, in the area A near the place where the temperature of the surface of the permanent magnet 25 is highest while the motor 1 is operating, the circulation path 1001 extends in the direction of the magnetic flux of the permanent magnet 25. It is formed to exist.

  Here, in the vicinity of the place where the temperature in the circulation path 1001 is the highest, the temperature sensitive magnetic body 26 receives a force in the direction of the magnetic flux of the permanent magnet 25 because the temperature sensitive magnetic body 26 is high in temperature and low in magnetic permeability. On the other hand, at other places in the circulation path 1001, the temperature sensitive magnetic body 26 has high permeability, so that it is hard to receive force by the magnetic flux of the permanent magnet 25 as compared with the place where the temperature is the highest. Therefore, in the circulation path 1001, the temperature-sensitive magnetic body 26 receives a force along the direction of the magnetic flux of the permanent magnet 25 only in the region A where the temperature of the permanent magnet 25 is the highest.

  When the temperature sensitive magnetic body 26 receives such a force, the temperature sensitive magnetic body 26 circulates in the circulation path 1001, so that the stator of the permanent magnet 25 in the radial direction has the highest temperature when the motor 1 is operated. The surface on the 11 side can be cooled. Therefore, it is suppressed that the permanent magnet 25 becomes high temperature and the amount of magnetic flux decreases when the motor 1 rotates, and the operation efficiency of the motor 1 can be improved.

  As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent. Moreover, the said embodiment can be combined suitably.

100 Magnet Temperature Estimation System 1 Motor 11 Stator 12 Rotor 2 Magnet Temperature Estimation Device 21 Slot 22 Teeth 23 Coil 24 Space 25, 25A, 25B, 25C, 25D Permanent Magnet 31 Magnet Member 51 Power Supply Part 511 Subtractor 512 Current Control 513 Adder 514 Coordinate conversion unit 515 Power conversion unit 516 Current detection unit 517 Coordinate conversion unit 518 Band stop filter 52 Superimposition unit 521 Subtractor 522 Resonance control unit 523 Band pass filter 53 Magnet temperature estimation unit

Claims (8)

What is claimed is: 1. A magnet temperature estimation system comprising: a motor comprising a stator comprising a coil; and a rotor comprising a permanent magnet, and a magnet temperature estimation device for estimating the temperature of the permanent magnet,
The rotor is
It has a temperature-sensitive magnetic material provided in the vicinity of the permanent magnet and whose permeability changes in accordance with its own temperature,
The magnet temperature estimation device
A power supply unit that applies to the coil an AC power of a drive frequency that rotationally drives the rotor;
A superimposing unit that superimposes AC power of a measurement frequency different from the drive frequency on the AC power of the drive frequency;
A temperature estimation unit configured to measure an impedance based on the AC power at the measurement frequency and estimate a temperature of the permanent magnet according to the measured impedance;
Magnet temperature estimation system characterized in that. The magnet temperature estimation system according to claim 1,
The temperature sensitive magnetic substance is provided in a path of magnetic flux generated by the permanent magnet.
Magnet temperature estimation system characterized in that. The magnet temperature estimation system according to claim 1,
The rotor is provided with an air gap for preventing a short circuit of the magnetic flux of the permanent magnet,
The temperature sensitive magnetic material is provided in the air gap,
Magnet temperature estimation system characterized in that. The magnet temperature estimation system according to any one of claims 1 to 3, wherein
The magnet temperature estimation device further includes a power control unit that controls AC power of a drive frequency applied to the coil by the power supply unit according to the temperature of the permanent magnet estimated by the temperature estimation unit. ,
Magnet temperature estimation system characterized in that. The magnet temperature estimation system according to any one of claims 1 to 4, wherein
The temperature sensitive magnetic body is a fluid,
Magnet temperature estimation system characterized in that. The magnet temperature estimation system according to claim 1,
The temperature sensitive magnetic substance is a fluid,
The rotor has a circulation path in which the temperature sensitive magnetic material circulates around the permanent magnet,
A part of the circulation path is provided in the vicinity of the place where the temperature of the permanent magnet is the highest while the motor is in operation, and extends in the direction of the magnetic flux of the permanent magnet.
Magnet temperature estimation system characterized in that. The drive frequency having a stator provided with a coil and a rotor provided with a permanent magnet, wherein AC power of a measurement frequency different in frequency from the drive frequency for rotationally driving the rotor is superimposed by the magnet temperature estimation device AC power is applied, and the temperature of the permanent magnet is estimated according to the impedance measured based on the AC power at the measurement frequency,
The rotor is
It has a temperature-sensitive magnetic material provided in the vicinity of the permanent magnet and whose magnetic permeability changes according to its own temperature,
A motor characterized by It is comprised by the stator provided with a coil, and the rotor provided with a permanent magnet, The said rotor is provided in the vicinity of the said permanent magnet, and has the temperature sensitive magnetic body from which the magnetic permeability changes according to its temperature. A motor temperature estimation method for estimating the temperature of the permanent magnet in a motor, comprising:
A power supply step of applying to the coil an AC power of a drive frequency for rotationally driving the rotor;
Superimposing the AC power of the measurement frequency different from the drive frequency to the AC power of the drive frequency;
Measuring an impedance based on the AC power at the measurement frequency, and estimating a temperature of the permanent magnet according to the measured impedance.
A magnet temperature estimation method characterized by

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