JP5544738B2 - Permanent magnet rotating electric machine - Google Patents

Description

  The present invention relates to a permanent magnet type rotating electric machine having a permanent magnet in a rotor.

  In a permanent magnet type rotating electrical machine having a permanent magnet in the rotor, a negative d-axis current is passed through the stator coil in order to prevent the induced voltage generated in the stator coil from becoming excessive in the high rotation region and exceeding the voltage limit value. In general, so-called field-weakening control that generates a demagnetizing action by an armature reaction and obtains an equivalent field-weakening effect is generally performed. However, in general magnetic flux weakening control, the demagnetization of the permanent magnet is caused by the direct application of the demagnetizing field to the permanent magnet itself due to the armature reaction. It is necessary to use a high coercive force type that uses a large amount of rare metal as a high cost, and problems such as the fact that it cannot be used to the performance limit without realizing a wide driving range are pointed out. Various improvement techniques for avoiding such problems have been studied. For example, in Patent Document 1 below, a magnetic wedge formed of a dust core having a high resistance, high magnetic permeability, and high saturation magnetic flux density is attached to a status lot. A technique for reducing the main magnetic flux linked to the stator coil by passing a large number of the short circuit is described.

JP-A-8-172742

  However, the conventional technique described in Patent Document 1 is a configuration in which the main magnetic flux is reduced by passing the magnetic flux through a magnetic wedge formed by a dust core and short-circuiting it. There is a problem that magnetic flux is easily short-circuited even in the rotation region, and the performance in the low rotation region is degraded.

  The present invention was devised in view of the problems of the prior art as described above, and effectively suppresses the induction voltage generated in the stator coil from becoming excessive in the high rotation region, and from the low rotation region. An object of the present invention is to provide a permanent magnet type rotating electrical machine that enables high-efficiency operation in a wide range of operation over a high rotation range.

  The permanent magnet type rotating electrical machine according to the present invention is provided with a current-carrying member made of a magnetic material in a magnetic circuit having a leakage magnetic flux different from the main magnetic flux, and by supplying a current to the current-carrying member, the magnetic resistance of the magnetic circuit of the leakage magnetic flux The above-described problem is solved by changing the main magnetic flux amount to be changed.

  According to the permanent magnet type rotating electrical machine according to the present invention, the amount of main magnetic flux linked to the stator coil can be reduced or increased by controlling the energization current to the energization member provided in the magnetic circuit of the leakage magnetic flux. In addition, it is possible to achieve high-efficiency operation in a wide range of operation from the low rotation region to the high rotation region while effectively suppressing an excessive induction voltage generated in the stator coil in the high rotation region.

It is a figure which shows the simple magnetic circuit model for demonstrating the basic principle of this invention. It is a graph which shows the relationship between the direction and magnitude | size of the energization current to a coil, and the amount of main magnetic fluxes. It is a figure which shows the result of having verified the relationship between the direction and magnitude | size of the energization current to a coil, and the amount of main magnetic fluxes by FEM analysis. It is sectional drawing of the permanent magnet type rotary electric machine which concerns on 1st Embodiment. FIG. 5 is a partial development view of the rotor showing a structure in which a magnetic body having a low saturation magnetic flux density is disposed around the end of the permanent magnet of the rotor. FIG. 4 is a partial development view of a motor showing a structure in which an opening for reducing the volume of a core material is provided around the end of a permanent magnet of a rotor. It is sectional drawing which expands and shows a part of permanent magnet type rotary electric machine which concerns on 2nd Embodiment.

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

[Principle explanation]
First, the principle of the present invention will be described. In the permanent magnet type rotating electrical machine to which the present invention is applied, the induced voltage generated in the stator coil increases as the rotation speed increases. Therefore, in order to prevent the terminal voltage from exceeding the voltage limit value, Therefore, it is necessary to reduce the amount of main magnetic flux interlinked. On the other hand, when operating at a low rotation, increasing the amount of main magnetic flux as much as possible leads to an improvement in operating efficiency. Therefore, it is required to increase the amount of main magnetic flux in the low rotation region. The present invention is basically realized by controlling the main magnetic flux amount by changing the magnetic resistance in the magnetic circuit of the leakage magnetic flux, for each operation region required for the permanent magnet type rotating electric machine as described above. . That is, by providing a current-carrying member made of a magnetic material in the magnetic circuit of the leakage magnetic flux, and controlling the current supply to this current-carrying member, the magnetic resistance in the magnetic circuit of the leakage magnetic flux is reduced and the leakage magnetic flux is increased during high rotation, The amount of main magnetic flux linked to the stator coil is reduced. On the other hand, at the time of low rotation, the magnetic resistance in the magnetic circuit of the leakage flux is increased to reduce the leakage flux so that the main magnetic flux amount can be secured. Hereinafter, such a basic principle will be described using a simple magnetic circuit model.

  FIG. 1 is a diagram showing a simple magnetic circuit model having a configuration in which a permanent magnet 101 is embedded in a C-shaped core 100 and coils 102 made of a magnetic material having a high magnetic permeability are disposed on both left and right ends of the permanent magnet 101. . In the simple magnetic circuit model shown in FIG. 1, the permanent magnet 101 generates an upward magnetic field in the drawing, and the magnetic flux that flows through the C-shaped core 100 and passes through the gap G is the main magnetic flux, and the end of the permanent magnet 101. The magnetic flux short-circuited at the part is the leakage flux.

In such a simple magnetic circuit model, it is assumed that a current is applied to the coils 102 arranged at the left and right ends of the permanent magnet 101 in the direction shown in FIG. At this time, in the regions on the left and right sides of the permanent magnet 101 serving as a magnetic circuit for leakage flux, the directions of the short-circuit magnetic flux of the permanent magnet 101 and the magnetic flux generated by energization of the coil 102 are opposite to each other and cancel each other. The magnetic flux is extremely small and the magnetic resistance is low. Therefore, as a result, although the magnetic flux is small (not saturated), the short-circuit magnetic flux of the permanent magnet 101 is large, and the main magnetic flux φ1 is relatively reduced. This is expressed by the following formula (1).

R _mc is the magnetic resistance [Wb / A] of the core 100 constituting the main magnetic circuit, R _{mc_leak} is the magnetic resistance [Wb / A] in the magnetic circuit of leakage magnetic flux, and R _mm is the magnetic resistance [Wb of the permanent magnet 101]. / a], t is the thickness of the permanent magnet 101 [m], M is the magnetizing force of the permanent magnet 101 [T], _{H c} is the inner core 100 magnetic field intensity [a / _{m], H} m is the internal permanent magnet 101 , B _c is the magnetic flux density [T] inside the core 100, B _m is the magnetic flux density [T] inside the permanent magnet 101, μ is the magnetic permeability [H / m] of the core 100, μ ₀ is the vacuum permeability [H / m], N is the number of turns of the coil 102, and I is the energization current [A] to the coil 102.

On the other hand, when a current is applied to the coils 102 arranged at the left and right ends of the permanent magnet 101 in the direction shown in FIG. 1B, the coils 102 are connected to the coils 102 at the left and right ends of the permanent magnet 101 serving as a magnetic circuit for leakage flux. The direction of the magnetic flux generated by energization is the same as the short-circuit magnetic flux of the permanent magnet 101, and the magnetic resistance is high. Therefore, the short-circuit magnetic flux of the permanent magnet 101 is reduced, and the main magnetic flux φ2 is relatively increased. This is expressed by the following equation (2), which shows a state where the magnetic circuit of the leakage magnetic flux is magnetically saturated.

In summary, the relationship of the main magnetic flux φ with respect to the energization current I to the coil 102 as shown in FIG. 2 is obtained. Here, the main magnetic flux φ1 in the state where the magnetic circuit of the leakage magnetic flux shown in the equation (1) is not magnetically saturated, and the main magnetic flux in the state where the magnetic circuit of the magnetic flux of leakage shown in the equation (2) is magnetically saturated. The ratio with φ2 is expressed by the following formula (3).

Further, when the relationship between the energization current I to the coil 102 and the main magnetic flux φ is verified by a finite element method (FEM) analysis, the relationship shown in FIG. 3 is obtained.

From the above results, it can be seen that the main magnetic flux φ changes according to the energization current I to the coil 102, and the main magnetic flux φ changes significantly especially when the energization current I is near zero. That is, the coil 102 made of a magnetic material having a high magnetic permeability is disposed in the magnetic circuit of the short-circuit magnetic flux (leakage magnetic flux) of the permanent magnet 101 that generates a magnetic field, and the energization current I to the coil 102 is controlled. Thus, the main magnetic flux φ can be appropriately controlled. If such a function (field adjustment function) is applied to a permanent magnet type rotating electrical machine, it is possible to effectively suppress excessive induced voltage generated in the stator coil in the high rotation region, while effectively rotating from the low rotation region to high rotation. High-efficiency operation can be realized in a wide range of operation areas.

[First Embodiment]
FIG. 4 is a view showing an example of a permanent magnet type rotating electrical machine to which the present invention is applied, and is a cross-sectional view in a direction perpendicular to the rotation axis direction of the permanent magnet type rotating electrical machine.

  The permanent magnet type rotating electric machine shown in FIG. 4 includes a stator 1 having a ring-shaped cross section and a rotor 2 disposed on the inner peripheral side of the stator 1 via an air gap. The stator 1 is formed by laminating electromagnetic steel plates, for example, and has a plurality of salient pole portions (stator teeth) protruding toward the rotor 2 side. The gap between the salient pole portions of the stator 1 is called a slot, and the stator coil 3 is wound around the slot. On the other hand, the rotor 2 is formed, for example, by laminating electromagnetic steel plates around a rotation axis, and a plurality of permanent magnets 4 are embedded therein at equal intervals in the circumferential direction. 4 is configured as a 12-pole concentrated winding motor, and the number of permanent magnets 4 is twelve. Each permanent magnet 4 is magnetized in the direction of the arrow in the figure.

  In such a permanent magnet type rotating electrical machine, the rotor 2 rotates due to the interaction between the rotating magnetic field generated by energizing the stator coil 3 with an alternating current and the magnetic field generated by the permanent magnet 4 of the rotor 2, thereby generating torque. generate.

  Here, in particular, in the permanent magnet type rotating electric machine according to the present embodiment, the coils 5 made of a magnetic material having a high magnetic permeability are provided so as to be adjacent to both ends of each permanent magnet 4 of the rotor 2. Specifically, the coil 5 made of this magnetic material is wound around a surface orthogonal to the magnetization direction of each permanent magnet 4 so as to surround each permanent magnet 4 of the rotor 2. The current flows in a direction perpendicular to the paper surface. As the coil 5 disposed at both ends of the permanent magnet 4, for example, a coil with a coating using Al or Fe as a main material can be considered. In addition, the magnetic material which comprises the coil 5 is not specifically limited to Al or Fe, What is necessary is just a material with a magnetic permeability higher than the laminated steel plate which comprises the core of the rotor 2. FIG.

  In the permanent magnet type rotating electrical machine of the present embodiment configured as described above, the magnetic field generated by the permanent magnet 4 of the rotor 2 passes through the salient pole part of the stator 1 from the core of the rotor 2 and is chained to the stator coil 3. The main magnetic flux to be exchanged and the leakage magnetic flux (short-circuit magnetic flux) that is short-circuited at the end of the permanent magnet 4 and does not become the main magnetic flux. The coils 5 disposed at both ends of the permanent magnet 4 are provided in a magnetic circuit of leakage magnetic flux that is short-circuited from the end of the permanent magnet 4. Here, if a current is supplied to the coil 5 in the direction in which a magnetic flux having the same direction as the leakage magnetic flux is generated as described with reference to the model of FIG. 1B, the leakage occurs according to the magnitude of the current. By increasing the magnetic resistance of the magnetic circuit of the magnetic flux, the leakage magnetic flux can be reduced, and the amount of the main magnetic flux can be relatively increased. On the other hand, when a current is passed through the coil 5 in a direction that generates a magnetic flux opposite to the leakage magnetic flux as described with reference to the model of FIG. The magnetic resistance of the magnetic circuit can be lowered to increase the leakage magnetic flux, and the amount of main magnetic flux can be relatively reduced. As described above, in the permanent magnet type rotating electrical machine of the present embodiment, the direction and magnitude of the energization current to be passed through the coils 5 arranged at both ends of the permanent magnet 4 are controlled according to the operating point of the permanent magnet type rotating electrical machine. By doing so, it is possible to realize high-efficiency operation in a wide range of operation from the low rotation range to the high rotation range.

  In the permanent magnet type rotating electrical machine of the present embodiment, when the main magnetic flux amount interlinked with the stator coil 3 is reduced during operation in the high rotation region, the demagnetizing field is not directly applied to the permanent magnet 4. However, since the amount of main magnetic flux is relatively reduced by increasing the leakage magnetic flux, the operating point on the demagnetization curve of the permanent magnet 4 is stable, and the demagnetization resistance is greatly improved. In addition, if a significantly improved demagnetization resistance is taken into account, it becomes possible to perform conventional general flux-weakening control in combination with the main magnetic flux control by energizing the coil 5. By carrying out in cooperation, it becomes possible to realize more efficient driving.

By the way, the field adjustment function by energizing the coil 5 as described above has such a characteristic that the amount of main magnetic flux greatly changes between when the magnetic circuit of the leakage magnetic flux is not magnetically saturated and when it is magnetically saturated. As described above, the structure of the magnetic body around the permanent magnet 4 is determined, so that it can operate more effectively. Here, the rate of change of the main magnetic flux amount between when the magnetic circuit of the leakage magnetic flux is not magnetically saturated and when it is magnetically saturated is expressed by the above equation (3). From this equation (3), the coil 5 In a state where no current is supplied to the magnetic field, the magnetic resistance R _{mc_leak} of the magnetic circuit for leakage magnetic flux (the magnetic circuit through which the short-circuit magnetic flux at both ends of the permanent magnet 4 flows) is the magnetic resistance R _{mc of the} main magnetic circuit through which the main magnetic flux flows. By determining the configuration of the magnetic body around the permanent magnet 4 so as to satisfy the following relationship (R _{mc_leak} ≦ R _mc ), the field adjustment function by energizing the coil 5 is more effective. It becomes possible to act on.

FIG. 5 is a diagram showing an example of a specific method for satisfying the relationship of R _{mc_leak} ≦ R _mc , and is a partial development view of the rotor 2. In the example shown in FIG. 5, a magnetic body 6 having a saturation magnetic flux density lower than that of the core material (magnetic steel plate) constituting the main magnetic circuit is arranged around the end of the permanent magnet 4 of the rotor 2, A magnetic circuit (a magnetic circuit through which a short-circuit magnetic flux at both ends of the permanent magnet 4 flows) is configured by the coil 5 and the magnetic body 6. As a result, the relationship of R _{mc_leak} ≦ R _mc is satisfied in a state where no current is supplied to the coil 5, and the field adjustment function by applying current to the coil 5 can be more effectively applied. It becomes.

FIG. 6 is a diagram showing another example of a specific method for satisfying the relationship of Rmc_leak ≦ Rmc, and is a partial development view of the rotor 2. In the example shown in FIG. 6, an opening 7 is provided around the end of the permanent magnet 4 of the rotor 2 to constitute a magnetic circuit for leakage magnetic flux (a magnetic circuit through which a short-circuit magnetic flux at both ends of the permanent magnet 4 flows). The volume of is reduced. Thus, by reducing the volume of the core material constituting the magnetic circuit of the leakage magnetic flux, it is possible to satisfy the relationship of Rmc_leak ≦ Rmc in a state where no current is supplied to the coil 5. It is possible to make the field adjustment function by energizing 5 more effective.

  As described above in detail with specific examples, according to the permanent magnet type rotating electrical machine of the present embodiment, the coil 5 made of a magnetic material having a high magnetic permeability disposed at the end of the permanent magnet 4 of the rotor 2. By controlling the direction and magnitude of the current to be applied to the magnetic flux and changing the magnetic resistance of the magnetic circuit of the leakage magnetic flux to control the amount of main magnetic flux, it can be used in a wide range of operation from the low rotation range to the high rotation range. Highly efficient operation can be realized. In addition, since a demagnetizing field is not directly applied to the permanent magnet 4 of the rotor 2 and the same effect as the flux-weakening control can be obtained by controlling the energization of the coil 5, the demagnetization resistance of the permanent magnet 4 can be improved. Performance degradation due to demagnetization can be effectively suppressed.

Further, according to the permanent magnet type rotating electrical machine of the present embodiment, the magnetic resistance R _{mc_leak} of the magnetic circuit of leakage magnetic flux and the magnetic resistance of the main magnetic circuit through which the main magnetic flux flows in a state where no current is supplied to the coil 5. as the R _mc satisfies the relationship _R mc_leak ≦ R _mc, since the magnetic material around the permanent magnet 4 is configured, thereby very effectively act the functions of the field adjustment by energization of the coil 5 Can do. In particular, the energization current to the coil 5 required when increasing the main magnetic flux can be reduced, which is effective for reducing the slip ring capacity and reducing the loss for energizing the coil 5.

[Second Embodiment]
Next, an example in which the present invention is applied to a permanent magnet type rotating electrical machine having a so-called V-shaped arrangement structure will be described. FIG. 7 is an enlarged view showing a part of the permanent magnet type rotating electrical machine of the present embodiment, and is a cross-sectional view in a direction perpendicular to the rotation axis direction of the permanent magnet type rotating electrical machine.

  In the permanent magnet type rotating electrical machine shown in FIG. 7, the permanent magnet 4 of the rotor 2 has a configuration in which two magnets 4a and 4b forming the same pole are arranged in a V shape. In the permanent magnet type rotating electric machine having such a V-shaped arrangement structure, when the volume of the core of the rotor 2 at the bottom portion of the V shape is increased, the strength is improved but the main magnetic flux is reduced. If the volume of the core of the rotor 2 in this part is reduced, there is a trade-off that the main magnetic flux increases but the strength decreases.

  Therefore, in the present embodiment, the coil 5 made of a magnetic material having a high magnetic permeability similar to that of the first embodiment is provided between the V-shaped bottom side ends of the two magnets 4a and 4b arranged in a V shape. The amount of main magnetic flux can be controlled by controlling the direction and direction of the current supplied to the coil 5. With such a configuration, the main magnetic flux is adjusted according to the operating region of the permanent magnet type rotating electrical machine while ensuring a volume sufficient to ensure the mechanical strength as the volume of the core of the rotor 2 at the bottom portion of the V-shape. Can do.

  As described above, according to the permanent magnet type rotating electrical machine of the present embodiment, a magnetic material having a high magnetic permeability is used between the ends of the V-shaped bottom portions of two magnets 4a and 4b having the same polarity arranged in a V shape. Since the coil 5 is wound, the amount of main magnetic flux can be controlled by controlling the direction and magnitude of the current flowing through the coil 5, while ensuring the core strength of the rotor 2, and the low rotation region. High-efficiency operation can be realized in a wide range of operation from the high rotation range to the high rotation range.

  The embodiment described above is merely an example of application of the present invention, and the technical scope of the present invention is not intended to be limited to the contents disclosed as the above-described embodiment. . That is, the technical scope of the present invention is not limited to the specific technical matters disclosed in the above-described embodiments, but includes various modifications, changes, alternative techniques, and the like that can be easily derived from this disclosure. For example, in the embodiment described above, the coil 5 made of a magnetic material is provided in the magnetic circuit of the leakage magnetic flux. However, instead of the coil 5, a magnetic material having a laminated structure is provided, and the magnetic material having the laminated structure is provided. It is good also as a structure which controls the amount of main magnetic fluxes by controlling the direction and magnitude | size of the electric current to supply.

DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 3 Stator coil 4 Permanent magnet 5 Coil 6 Magnetic body 7 Opening part

Claims (7)

A rotor with permanent magnets;
A stator arranged to face the rotor via a gap;
A stator coil wound in a slot of the stator;
A current-carrying member made of a magnetic material provided in a magnetic circuit of a leakage magnetic flux different from the main magnetic flux interlinking with the stator coil,
The permanent magnet is embedded in the rotor;
The energization member is a coil wound around a surface orthogonal to the magnetization direction of the permanent magnet so as to surround the permanent magnet,
When the rotor is driven at a high speed, the coil is energized so that the magnetic resistance in the magnetic circuit for leakage flux is small. When the rotor is driven at a low speed, the magnetic resistance in the magnetic circuit for leakage flux is The permanent magnet type rotating electrical machine is characterized in that the coil is energized so as to be large . A rotor having a V-shaped permanent magnet in which two magnets forming the same pole are arranged in a V-shape;
A stator arranged to face the rotor via a gap;
A stator coil wound in a slot of the stator;
A current-carrying member made of a magnetic material provided in a magnetic circuit of a leakage magnetic flux different from the main magnetic flux interlinking with the stator coil,
The permanent magnet is embedded in the rotor;
The current-carrying member is a coil wound between ends that are V-shaped bottom portions of two magnets arranged in a V-shape,
When the rotor is driven at a high speed, the coil is energized so that the magnetic resistance in the magnetic circuit for leakage flux is small. When the rotor is driven at a low speed, the magnetic resistance in the magnetic circuit for leakage flux is Energize the coil so that the
Permanent magnet type rotating electrical machine characterized by 3. The permanent magnet type rotating electrical machine according to claim 1 , wherein the energizing member is made of a magnetic body having a higher magnetic permeability than a magnetic body constituting the main magnetic circuit through which the main magnetic flux flows . The permanent magnet type rotating electric machine according to any one of claims 1 to 3, wherein the leakage magnetic flux is a short-circuit magnetic flux of the permanent magnet. When the magnetic resistance of the magnetic circuit through which the short-circuit magnetic flux of the permanent magnet flows is Rmc_leak and the magnetic resistance of the main magnetic circuit through which the main magnetic flux flows is Rmc, the relationship of Rmc_leak ≦ Rmc in a state where the energization member is not energized permanent magnet rotating electrical machine according to claim 4, characterized by satisfying the. The magnetic material having a saturation magnetic flux density lower than that of the magnetic material constituting the main magnetic circuit is disposed around the end of the permanent magnet to satisfy the relationship of Rmc_leak ≦ Rmc. 5. The permanent magnet type rotating electric machine according to 5. An opening for reducing the volume of the magnetic material constituting the magnetic circuit through which the short-circuit magnetic flux of the permanent magnet flows is provided around the end of the permanent magnet to satisfy the relationship of Rmc_leak ≦ Rmc. The permanent magnet type rotating electrical machine according to claim 5 .

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