TECHNICAL FIELD

The present invention relates to a rotating electric machine using permanent magnets.

BACKGROUND ART

A permanent magnet rotating electric machine, which is advantageous in downsizing and increase in output, is adopted in many cases as a rotating electric machine for industrial use and rotating electric machines for an electric vehicle and for a hybrid vehicle. Among the permanent magnet rotating electric machines described above, when the permanent magnet rotating electric machine has such a structure that permanent magnets are embedded in a rotor core, two kinds of torque can be obtained. Specifically, a magnet torque is generated by a magnet magnetic flux from the permanent magnets, and a reluctance torque is generated by a reluctance magnetic flux from a stator. A final torque of a motor is determined by a sum of the two kinds of torque.

However, the above-mentioned rotating electric machine having a general structure is characterized in that current phase angles β at which the above-mentioned two kinds of torque have peak values are different from each other. Specifically, the magnet torque has a positive peak value when β=0° is given, and the reluctance torque has a positive peak value when β=45° is given. Thus, a peak value of a total torque appears when β is larger than 0 degrees or when β is smaller than 45 degrees. Specifically, for current control of the motor, when a maximum torque is to be generated, the current phase angle is required to be set to a current phase angle β at which neither of the two kinds of torque has the peak value. Thus, a value of the maximum torque sometimes becomes smaller than a sum of the peak values of the two kinds of torque.

Meanwhile, there has been proposed a structure in which a rotor has through holes, each having a slit shape, for deviating a magnetic flux from permanent magnets toward a stator in a rotating direction of the rotor (for example, Patent Literature 1).

Further, there has been proposed a structure having slits in a core portion of a rotor, which is located on an outer periphery side of magnet insertion holes. The slits are drilled in a rotor magnetic pole center line direction only on a rotor reversing direction side of the rotor magnetic pole center line (for example, Patent Literature 2).

Further, there has been proposed a structure in which an air gap having a predetermined sectional shape is formed in a rotor at such a position as to have a delay phase with respect to a d axis, which corresponds to a magnetic flux direction of permanent magnets (for example, Patent Literature 3).

CITATION LIST

Patent Literature

Patent Literature 1 Japanese Unexamined Patent Application Publication No. H11-206046 A (Page 2 to 5, FIG. 2)

Patent Literature 2 Japanese Unexamined Patent Application Publication No. H11-178255 A (Page 2 to 4, FIG. 2)

Patent Literature 3 J Japanese Unexamined Patent Application Publication No. 2012-023904 A (Page 4 to 10, FIG. 2)

SUMMARY OF INVENTION

Technical Problem

In the structures disclosed in Patent Literatures 1 to 3, a positional relationship between a path of the magnet magnetic flux and a path of the reluctance magnetic flux is changed so that the current phase angle β at which the magnet torque has the peak value and the current phase angle β at which the reluctance torque has the peak value can be relatively set closer to each other. However, the air gap for localizing the magnet magnetic flux is present at a position of blocking the path of the reluctance magnetic flux, which leads to reduction of the reluctance torque itself. Thus, a final torque is sometimes reduced.

The present invention has an object to obtain a permanent magnet rotating electric machine capable of improving a total torque of a magnet torque and a reluctance torque.

Solution to Problem

According to the present invention, there is provided a permanent magnet rotating electric machine, including:a stator including a stator core and coils; anda rotor, which is arranged on an inner side of the stator with a gap being a micro-gap, and is rotatable,wherein the rotor includes:a rotor core;a plurality of magnets embedded in the rotor core; andmagnetic slits, each being formed in a core region of the rotor core, which is a region located between the magnets for forming one magnetic pole of the plurality of magnets and the gap, the magnetic slits being regions having a lower magnetic permeability than a magnetic permeability of the core region,wherein one of ends of each of the magnetic slits in a longitudinal direction of the magnetic slit, which is closer to an outer periphery of the rotor than another end, is positioned in a portion of the core region, which is located on the same direction side as a direction of a force in a circumferential direction of the rotor, the force being applied to the rotor by torque, with respect to a magnetic pole center of the one magnetic pole,wherein the another one of the ends of each of the magnetic slits, which is closer to a rotation axis center of the rotor, is positioned on the magnetic pole center or in a portion of the core region, which is located on a side opposite to the direction of the force in the circumferential direction, the force being applied by the torque, with respect to the magnetic pole center, andwherein an area of the portion of the core region, which is located on the same direction side as the direction of the force with respect to the magnetic slit, is smaller than an area of the portion of the core region, which is located on the side opposite to the direction of the force with respect to the magnetic slit.

Advantageous Effects of Invention

The permanent magnet rotating electric machine of the present invention is capable of improving a total torque of a magnet torque and a reluctance torque.

