JP2005304204A - Permanent magnet synchronous motor and drive apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a permanent magnet synchronous motor for inhibit an increase in a manufacturing cost, suppressing a magnetic flux short in a rotor and adjusting the quantity of magnetization. <P>SOLUTION: The rotor 2 comprises first and second rotor cores 2a, 2b fixedly disposed along a shaft 3. A permanent magnet 8a is mounted to the first rotor core 2a. A permanent magnet 8b is mounted to the second rotor core 2b. The permanent magnets 8a, 8b have different coercivities/permeabilities. The permanent magnet 8a has high coercivity and low permeability. The permanent magnet 8b has low coercivity and high permeability. Since the permanent magnets having the different coercivities/permeabilities are separated in a magnetic circuit, they do not interfere with each other, and the motor having the high efficiency and wide operating range is achieved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a permanent magnet type synchronous motor having a plurality of permanent magnets having different coercive force and magnetic permeability and a driving device.

  Conventionally, as a synchronous motor using a plurality of permanent magnets having different coercive force and magnetic permeability, an alnico magnet having a constant coercive force is arranged in the interpole portion of the rotor so that the amount of magnetization of the alnico magnet can be varied. Thus, there has been disclosed an attempt to expand the operating frequency range and increase the efficiency (for example, Patent Document 1).

Japanese Patent No. 3167535

  However, in the conventional permanent magnet type synchronous motor with variable magnetizing amount, a plurality of types of magnets having different coercive forces are arranged in the same cross-sectional circuit, so that the magnetic flux is short-circuited or the magnetic resistance is increased in the rotor. There was a problem that it was not possible to draw out the high efficiency and wide range of performance that was the feature of this motor.

  In addition, since the variable amount of magnetization cannot be changed after the core design of the rotor, there is a problem that a dedicated core design suited to the application is required and the cost increases greatly.

  The present invention has been made in view of the above, and provides a permanent magnet type synchronous motor capable of adjusting the amount of magnetization while suppressing magnetic flux short-circuiting in the rotor without increasing the manufacturing cost. With the goal.

  Another object of the present invention is to obtain a permanent magnet type synchronous motor drive device suitable for drive control of a permanent magnet type synchronous motor in which the magnetic flux of the permanent magnet is variable.

  In order to achieve the above-described object, the present invention provides a permanent magnet synchronous motor having two or more types of permanent magnets having different holding forces in the rotor, wherein the rotor is one or more planes orthogonal to the rotation axis. It is characterized by comprising a plurality of rotor cores divided by 1 and each rotor core having a different kind of permanent magnet attached thereto.

  According to the present invention, with such a rotor structure, the amount of magnetization of the permanent magnet having low coercive force characteristics can be varied by the current flowing through the stator winding. Since the permanent magnets having different coercive forces and magnetic permeability are separated from each other in a magnetic circuit, there is little interference between the magnetic characteristics, and a motor with high efficiency and a wide operating range can be realized. In addition, it is possible to divert the rotor core of a conventional permanent magnet type synchronous motor using a single type of permanent magnet, and there is an effect that the cost for introduction and manufacturing can be reduced.

  According to the present invention, it is possible to obtain a permanent magnet type synchronous motor capable of adjusting the amount of magnetization while suppressing magnetic flux short-circuiting in the rotor without increasing the manufacturing cost.

  Exemplary embodiments of a permanent magnet type synchronous motor and a driving apparatus according to the present invention will be explained below in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view conceptually showing the configuration of a permanent magnet type synchronous motor according to an embodiment of the permanent magnet type synchronous motor according to the present invention. FIG. 2 is a perspective view conceptually showing a configuration example (No. 1) of the rotor of the permanent magnet type synchronous motor shown in FIG.

  In FIG. 1, a rotor 2 is fixed to a shaft 3 and rotatably arranged inside a stator 1. In the stator 1, a stator winding 5 is provided on a stator core 4. The rotor 2 includes a rotor core 6 and permanent magnets 8. That is, for example, four void portions 7 are provided in a rectangular shape along the shaft 3 around the outer periphery of the rotor core 6 of the rotor 2, and the permanent magnets 8 are mounted in the respective void portions 7. Yes. In this embodiment, the shape of the permanent magnet 8 is assumed to be a rectangular plate for convenience of explanation.

  The rotor core 6 constituting the rotor 2 has a structure that is divided by one or more planes orthogonal to the rotation axis (shaft 3). The length along the rotation axis (shaft 3) of each divided rotor core, that is, the interval between the divided planes may be different, but it is more convenient for component management to be the same.

  In FIG. 2, the structural example divided into 2 by one plane orthogonal to a rotating shaft is shown. That is, the rotor 2 includes a first rotor core 2 a and a second rotor core 2 b that are fixedly disposed along the shaft 3. The joint 9 between the two may be directly bonded, but a non-magnetic material or a gap may be inserted.

  A permanent magnet 8a is attached to the first rotor core 2a. A permanent magnet 8b is attached to the second rotor core 2b. The permanent magnets 8a and 8b have characteristics that are different from each other in coercive force and magnetic permeability. Here, the permanent magnet 8a has a high coercive force / low magnetic permeability characteristic (for example, a rare earth magnet), and the permanent magnet 8b has a low coercive force / high magnetic permeability characteristic (for example, an alnico magnet). In FIG. 2, the permanent magnets 8a and 8b have different sizes, but may have the same size.

  Next, the operation of the permanent magnet type synchronous motor according to the first embodiment configured as described above will be described with reference to FIGS. FIG. 3 is a diagram showing the relationship between the stator magnetic flux d-axis component of the permanent magnet type synchronous motor having the rotor having the structure shown in FIG. 2 and the magnetic flux of the permanent magnet. FIG. 4 is a cross-sectional view illustrating a magnetic flux path in the permanent magnet type synchronous motor disclosed in Patent Document 1.

  In the permanent magnet type synchronous motor having the rotor having the structure shown in FIG. 2, the amount of magnetization of a permanent magnet having a low coercive force characteristic (hereinafter referred to as “low coercive force permanent magnet”) is determined by the current flowing through the stator winding 5. It becomes possible to vary. That is, in FIG. 3, when the d-axis component of the rotating magnetic flux generated from the stator 1 is controlled to gradually increase in the negative direction (the direction of arrow A), the low coercivity permanent magnet 10 Since the magnetomotive force in the opposite direction increases, the magnetic force of the magnet decreases.

  When the d-axis component of the rotating magnetic flux generated from the stator 1 is controlled so as to gradually increase in the positive direction (the direction of the arrow B), the low coercive force permanent magnet 10 has the same direction as the magnetic flux of the magnet. As the magnetomotive force increases, the magnetic force of the magnet increases.

  On the other hand, the high coercivity permanent magnet (hereinafter referred to as “high coercivity permanent magnet”) 11 has a coercivity sufficiently higher than that of the stator magnetic flux. Even if the amount of magnetization is changed, the magnet magnetic force is kept constant. As a result, the magnet magnetic flux 12 of the entire rotor 2 is the sum of the two types of permanent magnet magnetic flux, and can be changed as indicated by the bold line. Thus, the magnetic flux of the rotor 2 can be controlled as if it were a winding type synchronous motor.

  Next, with reference to FIG. 4, the difference in characteristics between the present invention and the technique disclosed in Patent Document 1 due to the difference in the arrangement structure of the permanent magnets arranged in the rotor will be described. In the permanent magnet arrangement structure disclosed in Patent Document 1, a plurality of types of permanent magnets are mixed in one plane perpendicular to the rotation axis of the rotor, and the permanent magnet having a low coercive force characteristic is arranged on the rotor center side. It is a structure. On the other hand, the permanent magnet arrangement structure according to the present invention is a structure in which only one type of permanent magnet is arranged in one plane orthogonal to the rotation axis of the rotor, as shown in FIG. In FIG. 4, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  4, in the permanent magnet type synchronous motor disclosed in Patent Document 1, the magnetic flux generated by the high coercivity permanent magnet 8a in the rotor 2 generates torque by creating a closed magnetic path indicated by a solid line arrow. However, a part of the magnetic flux is short-circuited by forming a closed magnetic path indicated by a dotted arrow through the interpolar part. Since the short-circuited magnetic flux does not generate torque, it causes a reduction in the efficiency of the motor and a reduction in the operating range. The short-circuit magnetic flux increases as the permeability between the poles increases.

  In the permanent magnet type synchronous motor disclosed in Patent Document 1, a low coercivity permanent magnet 8b for changing the magnetic flux is inserted between the rotor poles, and the inserted magnet is an Alnico magnet or an FeCrCo magnet. In some cases, the magnetic permeability is high, so that the short-circuit magnetic flux becomes large and the motor output may be reduced.

  At this time, in order to reduce the short-circuit magnetic flux, it is effective to make the magnet between the poles small and make it a gap. However, this reduces the permanent magnet 8b having a low coercive force. There arises a problem that the variable amount of the magnetic flux variable becomes small.

  Further, in the permanent magnet type synchronous motor disclosed in Patent Document 1, the magnetization variable amount is determined by the area ratio of the interpole magnets. Therefore, after the shape of the rotor core is determined, the magnetization variable amount is There is a problem that it can hardly be changed.

  On the other hand, in the present invention, the low coercive force magnet and the high coercive force magnet are arranged separately in the rotor axial direction, so in the example shown in FIG. 2, they are divided and arranged without changing the shape of the rotor core. It is possible to manipulate the magnetization variable amount by the ratio between the thickness of the two rotor cores and the length along the rotation axis of the two types of magnets. Therefore, the degree of freedom after designing the rotor core shape is increased. In addition, the shape of the gap portion can be optimally designed without being restricted by the variable amount of magnetization. Therefore, a permanent magnet type synchronous motor with higher output, high efficiency and wide operating range can be obtained.

  Further, in FIG. 1, if a nonmagnetic material or a gap is inserted into the mechanical joint 9, a short circuit of magnetic flux between the rotor cores 2a and 2b is reduced, which is more effective. If the sectional shapes (thickness and length in the illustrated example) of the permanent magnets 8a and 8b are the same, only one type of rotor core is required. Furthermore, in the manufacturing method, since the magnet assembling process can be performed after the shaft inserting process as in the past, there is an effect that the cost for development and manufacturing can be reduced.

  Although FIG. 2 shows the case where the rotor core is divided into two, in this invention, the rotor core can be divided into an arbitrary number. FIG. 5 is a perspective view conceptually showing a configuration example (No. 2) of the rotor of the permanent magnet type synchronous motor shown in FIG. FIG. 5 shows a configuration when the number of divisions of the rotor core is three. In the case of three divisions, as shown in FIG. 5, the low coercivity permanent magnet 8b is arranged at the center in the axial direction, and the low coercivity permanent magnets 8a, 8a are arranged outside thereof. With such an arrangement, magnetic imbalance of the rotor-stator gap in the axial direction can be suppressed, so that the load applied to the rotating shaft can be reduced as compared with the case of two divisions, and reliability is improved. And the efficiency can be further increased.

  In the first embodiment, only the rotor structure has been described. However, as apparent from the above description, the stator structure is not particularly restricted, and thus the stator is distributed and concentrated. It is possible to apply a rotor having a divided configuration according to the present invention regardless of whether it is a winding.

  As described above, according to this embodiment, as a method of arranging two or more types of permanent magnets having different coercive force / permeability in the rotor, two or more rotations divided by a plane orthogonal to the rotation axis Since one kind is arranged in each of the child cores, permanent magnets having different coercive force / permeability can be separated from each other in a magnetic circuit manner. Therefore, there is little interference between the respective magnetic characteristics, and a motor with high efficiency and wide operating range can be realized.

  Since the rotor magnetic flux can be easily controlled with a smaller motor current, the motor current can be reduced and the current capacity of the drive device can be reduced. Therefore, a highly efficient and low cost driving device can be obtained.

  At this time, if the number of divisions is 3 or more, a permanent magnet having a low holding force characteristic can be arranged near the center and a permanent magnet having a high holding force characteristic can be arranged on the outer side. It is possible to suppress the magnetic imbalance of the gap between the children. Therefore, the load applied to the rotating shaft can be reduced as compared with the case of two divisions, and the reliability and efficiency can be further increased.

  Moreover, since the cross-sectional shape of each permanent magnet can be made the same, in this case, only one type of rotor core needs to be prepared regardless of the number of divisions, and in addition, a single type of permanent magnet was used. Since the rotor core of a conventional permanent magnet type synchronous motor can be used, there is an effect that the cost for development and manufacturing can be reduced.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing a configuration of a permanent magnet type synchronous motor driving device according to an embodiment of the permanent magnet type synchronous motor driving device according to the present invention. In the second embodiment, a configuration example of a drive device that variably controls the magnetic flux of the permanent magnet mounted on the permanent magnet type synchronous motor described in the first embodiment is shown.

  In FIG. 6, reference numeral 20 denotes a permanent magnet type synchronous motor that is the permanent magnet magnetic flux variable type described in the first embodiment. The driving device for the permanent magnet type synchronous motor 20 includes an inverter 21 that is a driving power source and a control unit 22 that controls the inverter 21.

  The control unit 22 includes a current detector 23 that detects a current supplied from the inverter 21 to the permanent magnet type synchronous motor 20, a position detector 24 that detects a rotational position of the rotor of the permanent magnet type synchronous motor 20, A current coordinate conversion unit 25, a voltage coordinate conversion unit 26, a magnetic flux estimation unit 27, a speed control unit 28, a current control unit 29, and a speed calculation unit 30, which are various calculation / control units based on the detection values of the detector It has.

  Next, the operation of the permanent magnet type synchronous motor driving apparatus configured as described above will be described with reference to FIGS. FIG. 7 is a diagram for explaining the controllability of the permanent magnet type synchronous motor driving device shown in FIG.

  In FIG. 6, the control unit 26 drives the inverter 21 to output an alternating voltage. The permanent magnet type synchronous motor 20 is supplied with a drive current and rotates. The current detector 23 detects motor phase current information and outputs it to the voltage coordinate conversion unit 26. The position detector 24 detects the rotational position and outputs position information θ to the current coordinate conversion unit 25, the voltage coordinate conversion unit 26, and the speed calculation unit 30.

  The current coordinate conversion unit 26 generates current information Id and Iq on the rotation coordinate system (d axis-q axis) from the motor phase current information and the position information θ, and outputs the current information Id and Iq to the magnetic flux estimation unit 27 and the current control unit 29. To do. Further, the speed calculation unit 30 calculates the angular speed ω from the time change of the position information θ and outputs it to the magnetic flux estimation unit 27 and the speed control unit 28. The magnetic flux estimator 27 includes a d-axis component Vd and a q-axis component Vq of the voltage command currently output by the current controller 29, current information Id and Iq from the current coordinate converter 26, and a speed calculator 30. The estimated magnetic flux φh is calculated from the angular velocity ω, and is output to the speed control unit 28 and the current control unit 29.

The magnetic flux estimating unit 27 estimates the magnetic flux as follows, for example. The voltage equation of the permanent magnet type synchronous motor 20 is expressed by equation (1).

In Expression (1), Ld is d-axis inductance. Lq is a q-axis inductance. R is a winding resistance. φ is the magnetic flux. ω is the angular velocity. p is a differential operator (= d / dt). Ld, Lq, and R are motor constants that do not depend on the magnetic flux, and can be treated as known constants in calculation. Vd, Vq, Id, Iq, and ω are known variables as described above. That is, since variables other than the magnetic flux φ in the equation (1) are known, the estimated value φh of the magnetic flux φ is obtained by the equation (2) obtained by solving the equation (1) for the magnetic flux φ.

  Next, the speed control unit 28 obtains a speed deviation from the speed command ω * given from the outside and the angular speed ω from the speed calculation unit 30 and multiplies it by the estimated magnetic flux φh to control the torque current command. Iq * is obtained and supplied to the current control unit 29.

  The current control unit 29 calculates voltage command values Vd, Vq from the torque current command Iq * from the speed control unit 28, the excitation current command Id * given from the outside, and the current information Id, Iq from the voltage coordinate conversion unit 26. Is output to the voltage coordinate conversion unit 25 and the magnetic flux estimation unit 27. The voltage coordinate conversion unit 25 converts the voltage command values Vd and Vq into AC voltage information in a stationary coordinate system, and outputs it to the inverter 21. Thereby, the output AC voltage of the inverter 21 is changed and controlled.

  By sequentially performing the above operations, even when the magnetic flux of the permanent magnet type synchronous motor 20 changes, the control gain of the speed control and the current control changes according to the change of the magnetic flux so that the response of the control system does not change. Controlled. That is, controllability equivalent to that of a conventional magnetic flux fixed type permanent magnet motor can be obtained. Hereinafter, the controllability of the drive device that operates as described above will be described with reference to FIG. In FIG. 7, the speed response waveform when acceleration / deceleration control of the permanent magnet type synchronous motor 20 is performed is shown in comparison with the speed response waveform obtained by the permanent magnet type synchronous motor disclosed in Patent Document 1. .

  In FIG. 7, when the permanent magnet type synchronous motor is accelerated, it is energized with a leading phase, so that the magnet magnetic flux is reduced. That is, the torque constant decreases. Therefore, in the permanent magnet type synchronous motor disclosed in Patent Document 1, since magnetic flux estimation is not performed, an insufficient response occurs during acceleration as indicated by reference numeral (3). On the other hand, since current is applied with a delayed phase during deceleration, the magnetic flux increases and the torque constant increases, and the speed response becomes over-responsive as indicated by reference numeral (3).

  On the other hand, when the permanent magnet type synchronous motor 20 is driven by the speed command based on the magnetic flux estimation indicated by the symbol (1), as shown by the symbol (2), the control gain is set according to the magnetic flux that changes due to acceleration / deceleration. Since the correction is made, good acceleration / deceleration operation can be realized without insufficient response and overresponse.

  In the second embodiment, the drive device having the position detector has been described. However, a drive device having no position detector but having a position estimation unit can be configured. Moreover, although the case where the control gain of vector control was adjusted was mentioned as a use of magnetic flux estimation, it is not restricted to this, As a use which adjusts the V / F pattern of V / F control, and the motor constant of maximum torque control Is also applicable. By applying to these, high efficiency and controllability improvement of the drive device is realized.

Embodiment 3 FIG.
FIG. 8 is a flowchart for explaining the operation of the permanent magnet type synchronous motor driving apparatus according to another embodiment of the present invention. In the second embodiment, the case where the permanent magnet type synchronous motor is driven and controlled based on the detection of the magnet magnetic flux has been described. However, in the third embodiment, the magnet magnetic flux is variably controlled in the configuration shown in FIG. A case where the drive of the magnet type synchronous motor is controlled will be described.

  In the third embodiment, although not shown in FIG. 6, the control unit 22 includes means for controlling the excitation current command Id * to be given to the current control unit 29 according to the procedure shown in FIG. 8. The excitation current command Id * is an operation amount for controlling the magnetic flux of the low-coercivity permanent magnet 8b provided in the permanent magnet magnetic flux variable type permanent magnet synchronous motor 20 according to the present invention. The excitation current command Id * The magnetic flux of the permanent magnet 8b having a low coercive force characteristic can be increased or decreased in accordance with the increase or decrease of. However, the magnetic flux of the magnet varies within a predetermined range depending on the composition and shape.

  Here, the maximum value of the total magnetic flux of the permanent magnet 8a having the high coercive force characteristic and the permanent magnet 8b having the low coercive force characteristic is defined as Φmax and the minimum value is defined as Φmin. A method of controlling the excitation current command Id * will be described along the lines.

  In FIG. 8, the control unit 22 first determines the operating state of the permanent magnet type synchronous motor 20 (step ST1). When it is detected that the operation is started (starting up) (step ST1: Yes), the excitation current command value Id * is temporarily increased (step ST6). As a result, control to increase the drive current output from the inverter 21 is performed, and the permanent magnet 8b having a low coercive force characteristic is magnetized toward the maximum magnetization amount. When the permanent magnet 8b having a low coercive force characteristic can be set to the maximum magnetization amount, a voltage for controlling the rotation of the permanent magnet type synchronous motor 20 is generated in the inverter 21. As a result, the torque constant at the time of startup is maximized, so that an increase in startup torque and a reduction in startup current are achieved.

  When the permanent magnet type synchronous motor 20 is in an operating state (in operation) (step ST1: No), the control unit 22 determines the input voltage to the inverter 21 and the output voltage to the permanent magnet type synchronous motor 20. The estimated magnetic flux Φh is detected, and whether or not the input voltage to the inverter 21 is equal to or lower than the output voltage (step ST2), and whether or not the output voltage to the permanent magnet type synchronous motor 20 exceeds the input voltage (step ST3). ), Whether the estimated magnetic flux Φh indicates the maximum magnetization amount (step ST4) and whether the estimated magnetic flux Φh indicates the minimum magnetization amount (step ST5) are determined.

  As a result of the determination, the control unit 22 determines that demagnetization is possible when input voltage <output voltage (step ST2: Yes) and Φh> Φmin (step ST5: No), and temporarily determines the excitation current command value. Id * is lowered to demagnetize the permanent magnet 8b having a low coercive force characteristic (step ST7). Thereby, the output voltage to the permanent magnet type synchronous motor 20 decreases until it balances with the input voltage to the inverter 21. As a result, the steady current value flowing to the permanent magnet type synchronous motor 20 after demagnetization is reduced, so that an efficient operation state is obtained.

  On the other hand, as a result of the determination, when the input voltage> the output voltage (step ST3: Yes) and Φh <Φmax (step ST4: No), the control unit 22 determines that magnetization is possible, and temporarily determines an excitation current command. The value Id * is increased to magnetize the permanent magnet 8b having a low coercive force characteristic (step ST6). As a result, the output voltage to the permanent magnet type synchronous motor 20 rises until it balances with the input voltage to the inverter 21. As a result, the steady current value that flows in the permanent magnet type synchronous motor 20 after the completion of magnetization decreases, resulting in an efficient operating state.

  As described above, according to the third embodiment, the permanent magnet type synchronous motor drive device is more specific when the drive device starts operation according to the situation such as the load, the power supply, and the operation command. Depending on the situation and the situation where the output voltage generation state of the inverter has recovered from the voltage saturation state, it is possible to generate a drive current that increases the residual magnetic flux density of the permanent magnet type synchronous motor and to perform drive control.

  As described above, the permanent magnet type synchronous motor and the driving apparatus according to the present invention are used in motor inverters such as air conditioners, refrigerator compressors, refrigerators, elevators and the like in which permanent magnet type synchronous motors are currently used. It is useful for applying and saving energy. In addition, it is useful for reducing the cost, increasing the efficiency, and reducing the size by eliminating the field winding by applying it to a motor for a starter / alternator for automobiles that currently use a wound synchronous motor.

1 is a sectional view conceptually showing the structure of a permanent magnet type synchronous motor according to an embodiment of the present invention. FIG. 2 is a perspective view conceptually showing a configuration example (No. 1) of a rotor of the permanent magnet type synchronous motor shown in FIG. 1. It is the figure which showed the relationship between the stator magnetic flux d-axis component of a permanent magnet type synchronous motor which has a rotor of the structure shown in FIG. 2, and the magnetic flux of a permanent magnet. It is sectional drawing explaining the magnetic flux path | route in the permanent magnet type synchronous motor disclosed by patent document 1. FIG. FIG. 3 is a perspective view conceptually showing a configuration example (No. 2) of the rotor of the permanent magnet type synchronous motor shown in FIG. 1. 1 is a block diagram showing a configuration of a permanent magnet type synchronous motor driving device according to an embodiment of a permanent magnet type synchronous motor driving device according to the present invention; FIG. It is a figure explaining the controllability of the permanent magnet type synchronous motor drive device shown in FIG. It is a flowchart explaining the operation | movement of the permanent magnet type synchronous motor drive device by other embodiment of the permanent magnet type synchronous motor drive device concerning this invention.

Explanation of symbols

1 Stator,
2 rotors,
2a, 2b divided rotor core,
3 shaft,
4 Stator core,
5 Stator winding,
6 Rotor core,
7 voids,
8 Permanent magnet,
8a Permanent magnet with high holding force characteristics,
8b Permanent magnet with low holding power characteristics,
9 joints,
20 Permanent magnet type synchronous motor,
21 inverter,
22 control unit,
23 Current detector,
24 position detector,
25 Current coordinate converter,
26 Voltage coordinate converter,
27 Magnetic flux estimation unit,
28 Speed controller,
29 Current controller,
30 Speed calculator.

Claims (8)

In a permanent magnet type synchronous motor having two or more kinds of permanent magnets having different holding forces in a rotor,
The rotor includes a plurality of rotor cores divided by one or more planes orthogonal to the rotation axis,
Each of the rotor cores is mounted with a different kind of permanent magnet.
A permanent magnet type synchronous motor.   When the plurality of rotor cores is 3 or more, the rotor core disposed near the center is provided with a permanent magnet having a low holding force characteristic, and the rotor core disposed on both sides sandwiching the vicinity of the center The permanent magnet type synchronous motor according to claim 1, wherein a permanent magnet having a high holding force characteristic is mounted.   3. The permanent magnet type synchronous motor according to claim 1, wherein a nonmagnetic material or a gap is inserted in each joint portion of the plurality of rotor cores. 4. An inverter that supplies a drive current to the permanent magnet type synchronous motor according to any one of claims 1 to 3, and a control unit that determines the drive current output by the inverter,
The control means includes
The maximum current value that can be output from the inverter is equal to or greater than the value that can increase the permanent magnet with the smallest holding force among the permanent magnets of the permanent magnet type synchronous motor, and the permanent magnet with the largest holding force is reduced. Configuration to control to be less than the magnetizable value,
A permanent magnet type synchronous motor driving device comprising: The control means includes
Means for measuring the induced voltage during operation of the permanent magnet type synchronous motor;
Means for estimating the magnetic flux of the permanent magnet provided in the permanent magnet type synchronous motor based on the measured induced voltage;
Means for issuing an operation command according to the estimated magnetic flux of the permanent magnet to the inverter;
The permanent magnet type synchronous motor driving apparatus according to claim 4, wherein   The control means includes means for causing the inverter to generate a drive current that increases the residual magnetic flux density of the permanent magnet type synchronous motor in accordance with the situation of a load, a power supply, an operation command, and the like. The permanent magnet type synchronous motor driving device according to claim 4 or 5.   The permanent magnet type synchronous motor drive device according to claim 6, wherein the situation is a situation when the drive device starts operation. The permanent magnet type synchronous motor driving apparatus according to claim 6, wherein the state is a state in which an output voltage generation state of the inverter has recovered from a voltage saturation state.

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