JP6024123B2 - Permanent magnet rotating electric machine - Google Patents

Description

The present invention relates to a permanent magnet type rotating electrical machine, and more particularly related to the Optimization for achieving realization of low loss Shitsuka.

As is well known, there are two types of permanent magnet type rotating electrical machines: surface magnet type (SPM type) and embedded magnet type (IPM type).
Here, in the IPM type rotating electrical machine, a plurality of permanent magnets are arranged and embedded in the circumferential direction in the core of the rotor facing the stator with a gap, and the magnetic flux generated from the permanent magnets is connected to the stator coil. In addition to the magnet torque generated according to the amount of flux linkage, this is a rotating electrical machine that uses the reluctance torque due to the saliency of the magnetic circuit in the rotor. It has been adopted.

  Next, as a configuration example of the IPM type rotating electrical machine, a schematic sectional view of a permanent magnet type rotating electrical machine in which the number of magnetic poles of the rotor is 4 and the number of coil slots of the stator is 12 slots (cross section perpendicular to the rotating shaft) Figure) is shown in FIG. In the figure, 1 is a stator, 2 is a rotor, 3 is a rotating shaft, and 4 is an enclosing frame. Further, 5 is a yoke of the stator core, 6 is teeth arranged along the inner peripheral side of the yoke 5, 7 is a coil slot formed between the teeth 6, and 8 is received in the coil slot 7 and stored in the teeth 6. A stator coil 9 is wound around the rotor core, 9 is a magnet slot arranged in the circumferential direction of the rotor core, and 10 is a permanent magnet fitted into the magnet slot 9. Two permanent magnets 10 (the same polarity) are combined in a V shape toward the center of the rotating shaft 3 as shown in the figure so that the permanent magnets 10 are alternately different in polarity between the magnetic poles adjacent in the circumferential direction. Has been placed.

  On the other hand, the loss generated during the operation of the IPM rotary electric machine is roughly divided into iron loss, copper loss, magnet loss, and mechanical loss. Of these, focusing on iron loss and copper loss, iron loss is mainly eddy current loss and hysteresis loss caused by the amount of magnetic flux in the magnetic steel sheet and changes thereof, and copper loss is in the coil slot 7 of the stator 1. This is a Joule loss that occurs in the stator coil 8 that is housed and wound around the teeth 6.

  Here, when attention is paid to the relationship between the opening area of the coil slot 7 formed in the core of the stator 1 and the loss, the copper loss is reduced when the sum of the opening area occupied by the coil slot 7 is increased for a similar body (thick conductor) However, the width of the magnetic path (teeth 6, yoke 5) through which the magnetic flux passes is reduced by the amount of the opening area of the coil slot 7 increased. The magnetic flux density increases and the iron loss increases.

  Since the amount of increase (decrease) in iron loss and the amount of increase (decrease) in copper loss generated in the permanent magnet type rotating electric machine varies depending on the opening area of the coil slot 7 formed in the stator core, the design of the fuselage In this case, there is an optimum opening area of the coil slot that minimizes the total loss of iron loss and copper loss.

  By the way, when considering the opening area of the coil slot formed in the stator core using parameters such as the outer diameter, inner diameter, and teeth width of the stator core that determine the shape of the fuselage, the coil that can be taken in the design of the fuselage The opening area of the slot is limited by the outer diameter C and the inner diameter D of the stator 1 in FIG. That is, when the inner diameter D of the stator 1 is made small so that the coil slot has a large opening area in the same body size, the warp dimension and surface area of the rotor 2 facing the inner peripheral side of the stator 1 with a gap g therebetween. Inevitably becomes smaller and the output torque of the rotating electrical machine decreases. To obtain a required output, the current flowing through the stator coil 8 is increased or the amount of the permanent magnet 10 provided on the rotor 2 is increased. It is necessary to increase the magnetic flux density and increase the ratio of the copper loss and the iron loss as a result. As a result, the optimum total area of the coil slot 7 depends on the inner diameter D of the stator core. Change.

  On the other hand, as a measure to reduce loss in permanent magnet type rotating electrical machines, measures that have been proposed to reduce iron loss by changing the shape of the stator core as described below or by devising the processing method of the electromagnetic steel sheet (For example, see Patent Document 1 and Patent Document 2).

  That is, in Patent Document 1, a slit extending in the width direction is provided to the yoke of the stator so as to reduce the magnetic saturation of the magnetic path by suppressing the bias of the magnetic flux flowing through the teeth to the yoke. ing.

  In Patent Document 2, teeth and coil slots are formed on a stator core that is a laminated body of electromagnetic steel sheets to form teeth and coil slots, and magnetic characteristics resulting from residual strain of the electromagnetic steel sheets associated with general punching processing. The iron loss is reduced by suppressing the decrease of the iron.

JP 2008-22631 A JP 2010-115095 A

  By the way, the above-mentioned Patent Document 1 and Patent Document 2 are intended to reduce the loss by paying attention to the iron loss among the various losses generated in the permanent magnet type rotating electrical machine. From the standpoint of simultaneously reducing the total loss, it is not necessarily an optimal measure.

  In recent years, the promotion of energy saving in rotating electrical machines has become an important theme, and the efficiency of permanent magnet rotating electrical machines has been raised as a goal in accordance with IEC standard 4IE class (super premium efficiency).

Accordingly, an object of the present invention is to focus on the relationship between the copper loss and the iron loss that change according to parameters such as the outer diameter and inner diameter of the stator and the opening area of the coil slot that determine the machine shape of the rotating electrical machine. one design when optimally define the feature dimensions of to provide a permanent magnet type rotary electric machine as a low loss Shitsuka can be easily achieved.

In order to achieve the above object, according to the present invention, a stator core is formed by forming a coil slot between a yoke, a plurality of teeth, and teeth, and encasing a coil in the coil slot. The rotor comprises a rotor facing the stator with a gap, and the rotor core is embedded with a plurality of permanent magnets corresponding to a predetermined number of poles arranged in the circumferential direction and inserted into magnet slots penetrating in the axial direction. In the permanent magnet type rotating electrical machine
An axial vertical Chokudan area calculated from the outer diameter of the stator A, the sum of the opening area of the coil slots formed in the stator core B, and the stator outer diameter C, and a stator inner diameter as D, After defining the design index E of the aircraft as E = (B / A) +1.2 (D / C),
The dimensions of the aircraft are set so that the value of the design index E is within the range of 0.94 ≦ E ≦ 1.02.

  As described above, the design index E = (A / B) +1.2 (D / C) that defines the outer diameter and inner diameter of the stator, the opening area of the coil slot, and the like as parameters in the new design of the permanent magnet type rotating electrical machine. ) Is designed to reduce the total loss of copper loss and iron loss with a compact body by designing the dimensions of the rotating electrical machine by setting the dimensions so that the value is within the range of 0.94 ≦ E ≦ 1.02. A high output permanent magnet type rotating electrical machine can be obtained.

1 is a schematic cross-sectional view of a permanent magnet type rotating electrical machine according to an embodiment of the present invention. For the permanent magnet type rotating electrical machine shown in FIG. 1, the interphase between which the total loss of copper loss and iron loss is analyzed and calculated using the inner diameter / outer diameter ratio of the stator core and the total coil slot area / machine cross-sectional area ratio as parameters. It is the figure which represented the relationship as a graph. It is a figure showing the correlation between a loss calculation result and a design index value about the design model of condition 1 in FIG. It is a figure showing the correlation between a loss calculation result and a design index value about the design model of condition 2 in FIG.

Hereinafter, a method of airframe design for achieving optimum efficiency of the permanent magnet type rotating electrical machine according to the present invention will be described.
First, for the IPM type permanent magnet type rotating electric machine shown in FIG. 1, the inventor changed the combination of the number of magnetic poles and the number of coil slots in various ways in order to find the optimum design condition that minimizes the total loss of copper loss and iron loss. Assuming a design model, the parameters of the outer diameter and inner diameter of the stator 1 and the total opening area of the coil slot 7 are analyzed as parameters, and the copper loss and iron loss in each design model are analyzed. Based on the calculation results The graph of the interphase relationship graphed like FIG. 2 was obtained.

In FIG. 2, the horizontal axis represents the inner diameter / outer diameter ratio of the stator 1, and the vertical axis represents the total area / machine cross-sectional area ratio of the coil slot 7, where the combination of the number of magnetic poles and the number of coil slots is changed. 1 to condition 4 (for example, condition 1 is the number of magnetic poles: 6, number of coil slots: 36, condition 2 is the number of magnetic poles: 8, and the number of coil slots: 48). Analyze the copper loss and iron loss generated by changing the area, and the stator inner diameter / outer diameter ratio and the total coil slot area / machine cross-sectional area ratio that minimize the calculated loss are shown in the figure. Plotted and graphed. Then, the correlations were respectively expressed by a linear approximation method to obtain the following expression (1).

y + 1.2x ≒ 1 ... (1)
However, y: Coil slot total area [mm2] / Aircraft cross-sectional area [mm2],
x: Stator inner diameter [mm] / Stator outer diameter [mm]
Machine cross-sectional area of rotating electrical machine = π × ((stator outer diameter) / 2) ²
Thus, based on the formula (1) obtained by the above method, y (ratio of the coil slot total area to the fuselage cross-sectional area) and x (external to the stator) so that the value of (y + 1.2x) is approximately 1. If the specification dimension of the ratio of the stator inner diameter to the diameter is specified, an optimally designed machine body that minimizes the total loss of copper loss and iron loss can be obtained.

  Further, the inventor defines y + 1.2x of the above formula as a design index E, and based on the loss calculation results obtained for the design models of the conditions 1 and 2, the calculated loss values shown in FIGS. The interrelationship with the value of the design index E was verified. FIG. 3 shows the verification result corresponding to the design condition 1 and FIG. 4 shows the verification result corresponding to the design condition 2. In either case, the dimensions of the aircraft are within the range of 0.94 ≦ E ≦ 1.02 It was confirmed that the total loss of copper loss and iron loss was sufficiently reduced. 3 and FIG. 4, the vertical axis loss [p. u] is expressed in a unit method (Per Unit unit system), and is normalized by a loss value that can sufficiently satisfy the IE4 class of the IEC standard even when iron loss, copper loss and other losses are taken into consideration.

  As is clear from the above description, y and x are defined so that the design index value E falls within the range of 0.94 ≦ E ≦ 1.02, that is, specifications such as stator inner diameter and coil slot total area are set. By designing the rotating electrical machine body, it is possible to obtain an optimally designed permanent magnet type rotating electrical machine that minimizes the loss. That is, as a design procedure when a permanent magnet type rotating electrical machine is newly designed, first, the core outer diameter C and inner diameter D of the stator 1 are determined according to desired basic specifications (output, rotational speed, etc.). Next, using the above mathematical formula (y + 1.2x≈1) as an index for design support, the circumferential width of the teeth 6, the opening width of the coil slot 7, and the diameter of the yoke 5 according to the predetermined number of magnetic poles and the number of coil slots. The total area of the coil slots is set by adjusting the direction width and the like so that the value of the design index E falls within the optimum range (0.94 ≦ E ≦ 1.02) defined in claim 1 of the present invention.

  As a result, it is possible to easily obtain a permanent magnet type rotating electrical machine having an optimal design that minimizes the total loss of copper loss and iron loss without taking much time and effort for new design of the airframe.

DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 3 Rotating shaft 5 Yoke 6 Teeth 7 Coil slot 8 Stator coil 9 Magnet slot 10 Permanent magnet

Claims (1)

A stator core is formed with a yoke, a plurality of teeth, and a coil slot formed between the teeth, and a stator that is wound with the coil placed in the coil slot, and a rotor that faces the stator with a gap therebetween. In the embedded permanent magnet type rotating electrical machine, in the rotor core, a plurality of permanent magnets corresponding to a predetermined number of poles are arranged in a circumferential direction and inserted into a magnet slot penetrating in the axial direction.
An axial vertical Chokudan area calculated from the outer diameter of the stator A, the sum of the opening area of the coil slots formed in the stator core B, and the stator outer diameter C, and a stator inner diameter as D, After defining the design index E of the aircraft as E = (B / A) +1.2 (D / C),
A permanent magnet type rotating electrical machine characterized in that the dimensions of the airframe are set so that the value of the design index E falls within a range of 0.94 ≦ E ≦ 1.02.