Rotating electric machine of the permanent magnet type

Abstract

Rotating electric machine of the permanent magnet type, comprising the following: a rotor (20) comprising several equally spaced magnetic poles; and a stator (10) comprising several teeth and several armature windings (12), wherein: the rotor (20) comprises permanent magnets (22) which are inserted into openings P which are provided at equal intervals in the circumferential direction within an outer circumferential surface of a rotor iron core (21); the stator (10) comprises a stator iron core (11) with N teeth and a cylindrical shape, on which the multiple armature windings (12) are provided for generating a rotating magnetic field to rotate the rotor, the stator iron core (11) being divided in the circumferential direction into N stator blocks; and a setting such that 0.6 < La / (πD / N - Lb) < 1.0 is satisfied, wherein La is a gap in the circumferential direction between distal end sections of the stator iron core (11) adjacent to each other in the circumferential direction, Lb is a size of each of the multiple teeth in the circumferential direction, and D is an inner diameter dimension of the stator iron core (11), and P and N are set such that P / (greatest common divisor of P and N) is an odd number; and wherein the size Lb of each of the multiple teeth of the stator (10) in the circumferential direction is set such that 0.57 ≥ Lb / (πD / N) is satisfied.

Description

Technical area

[0001] The present invention relates to a permanent magnet type rotating electric machine capable of detecting a position of a rotor in a sensorless manner (capable of rotation sensorless driving). Technical background

[0002] In recent years, increased reliability, reduced costs, and miniaturization have been demanded for permanent magnet-type rotating electrical machines such as permanent magnet motors. To meet these demands, sensorless drive technologies have been developed that can operate without a rotation sensing device such as an optical encoder or resolver.

[0003] As one of the rotation sensorless drive methods for the permanent magnet type rotating electric machine, a high-frequency superposition method is proposed, which enables estimation of magnetic pole positions of a motor even when the motor is not rotating (see, for example, Patent Document 1). The high-frequency superposition method involves applying a voltage-independent high-frequency voltage to generate torque to the armature windings of the motor, and using a difference between a d-axis current and a q-axis current caused by a dependence (salience or saliency) of the motor's inductance on a rotor position to detect the rotor position.

[0004] Furthermore, as a motor applied to the high-frequency superposition method, namely, a motor for a rotation sensorless drive that utilizes the dependence (salience) of the motor's inductance on the rotor position, an internal magnet motor with salience is used (see, for example, Patent Document 2). In the internal magnet motor, permanent magnets are embedded in a rotor iron core, and a stator iron core is integrally structured and has an aperture shape, enabling detection of an initial magnetic pole position when a power supply is turned on. Quotation listPatent literature [PS 1] WO 2009 / 040 965 A1 [PS 2] JP 2004- 56 871 A Summary of the inventionTechnical problems

[0005] The high-frequency superposition method disclosed in Patent Document 1 involves performing rotor position detection under the assumption that the permanent magnet-type rotating electric machine has an ideal inductance distribution, specifically, that an elliptical trajectory drawn by the d-axis current and the q-axis current does not change depending on the load and the rotor position. However, an actual permanent magnet-type rotating electric machine does not have an ideal inductance distribution, thus the magnetic pole position estimation error is large, and it has a problem that high-precision position control cannot be performed.

[0006] In addition, in order to realize the rotation sensorless drive technology capable of eliminating a rotation detection device for a motor such as the optical encoder or the resolver, the position detection for a rotor must be performed not only when the power supply is turned on but also when the motor is driven (in a load state where a motor load current is supplied).

[0007] However, as disclosed in Patent Document 2, if the stator iron core is structured integrally, a magnetic saturation state inside the iron core tends to change depending on the load current of the motor. Therefore, there is also a problem that the magnitude of the inductance of the motor changes depending on the load current, causing an increase in the position detection error or a dropout during sensorless driving, and the structure cannot be applied to positioning control. Further prior art is known from the following published patent applications: DE 10 2007 006 095 A1, DE 697 35 741 T2, DE 11 2006 000 063 T5, and US Pat. No. 6,034,460 A.

[0008] The present invention is intended to solve the above-mentioned problems and has as an object to obtain a permanent magnet type rotating electric machine capable of highly accurately detecting a position of a rotor during sensorless driving. Solution to the problems

[0009] A permanent magnet type rotating electric machine according to the present invention includes a rotor including a plurality of equally spaced magnetic poles, and a stator including a plurality of teeth and a plurality of armature windings. A high-frequency voltage, which differs in frequency and amplitude from voltages for generating torque, is applied to the armature windings. A magnetic pole position of the rotor is estimated using a current trajectory of a measured high-frequency current. When a dq transformation is applied to the measured high-frequency current, a current trajectory forms an ellipse on a d- and q-axes. Angle change ranges of a major axis of the ellipse with respect to a load current and a rotor position are adjusted to obtain a predetermined position estimation resolution. Advantageous effects of the invention

[0010] In the permanent magnet type rotating electric machine according to the present invention, when the dq transformation is applied to the high frequency current measured when the high frequency voltage is applied, the current trajectory forms the ellipse on the d and q axes, and the angular change ranges of the major axis of the ellipse with respect to the load current and the rotor position are adjusted so that the predetermined position estimation resolution is obtained.

[0011] Accordingly, it is possible to obtain the permanent magnet type rotating electric machine capable of highly accurately detecting the position of the rotor during sensorless driving. Short description of the drawings Fig. 1 is an explanatory diagram showing a magnetic pole position detection method during sensorless driving of a general permanent magnet type rotating electric machine. Fig. Figure 2 is an explanatory diagram showing an ideal inductance distribution with respect to a rotor position of a permanent magnet type rotating electric machine. Fig. Figure 3 is an explanatory diagram showing a current trajectory on a d- and q-axis when a driving voltage superimposed with a high-frequency voltage is applied to a permanent magnet type rotating electric machine with the ideal inductance distribution. Fig. 4 is an explanatory diagram showing an actual inductance distribution with respect to the rotor position of an actual permanent magnet type rotating electric machine. Fig. Figure 5 is an explanatory diagram showing a current trajectory on a d- and q-axis when the driving voltages superimposed with a high-frequency voltage are applied to the permanent magnet type rotating electric machine having the actual inductance distribution. Fig. 6 is an explanatory diagram showing a current trajectory after offset processing for DC components of a d-axis current, and a q-axis current is applied to the current trajectory at the d- and q-axes when the driving voltages on which the high-frequency voltage is superimposed are applied to the permanent magnet type rotating electric machine having the actual inductance distribution. Fig. 7 is an explanatory diagram showing a representative example of an investigation result of an application of a permanent magnet type rotating electric machine to a rotation sensorless drive by means of a magnetic field analysis using shapes of a rotor and a stator as parameters. Fig. 8 is a cross-sectional view illustrating a structure of a permanent magnet type rotating electric machine according to a first embodiment of the present invention. Fig. 9 is an explanatory diagram showing a relationship between a slot opening ratio and a phase shift between a main axis in a no-load state and a main axis in a loaded state having a current trajectory ellipse in the permanent magnet type rotating electric machine according to the first embodiment of the present invention. Fig. 10 is an explanatory diagram showing a relationship between the slot opening ratio and a salience ratio of the rotating electric machine corresponding to a ratio of a minor axis to the major axis of the current trajectory ellipse, and a relationship between the slot opening ratio and a change in the major axis of the current trajectory ellipse with respect to the rotor position in the permanent magnet type rotating electric machine according to the first embodiment of the present invention. Fig. 11 is an explanatory diagram illustrating a relationship between a tooth width ratio and the salience ratio of the rotating electric machine corresponding to the ratio of the minor axis to the major axis of the current trajectory ellipse, and a relationship between the tooth width ratio and the change of the major axis of the current trajectory ellipse with respect to the rotor position in the permanent magnet type rotating electric machine according to the first embodiment of the present invention. Fig. 12 is a cross-sectional view illustrating a structure of a permanent magnet type rotating electric machine according to a second embodiment of the present invention. Description of the embodiments

[0012] A description will now be given of a permanent magnet type rotating electric machine according to preferred embodiments of the present invention with reference to the drawings, in which the same or corresponding components are designated by the same reference numerals. First embodiment

[0013] Now, with reference to Fig. 1 a description of a detection method for magnetic pole positions of a permanent magnet type rotating electrical machine during sensorless driving. Fig. Figure 1 is a general explanatory diagram showing the detection method for the magnetic pole positions of the permanent magnet type rotating electrical machine. Fig. 1, to detect the magnetic pole positions, a drive voltage superimposed with a high-frequency voltage is applied to the permanent magnet type rotating electric machine, and magnetic pole positions are estimated by processing a current waveform of a current measured in each of the phases.

[0014] Fig. Figure 2 then shows an ideal inductance distribution with respect to a rotor position of the permanent magnet type rotating electrical machine. In Fig. 2, the ideal inductance distribution has an ideal sine waveform with two oscillation components spanning 360 degrees, and has a shape in which neither phase shift nor distortion occurs, even when a load current magnitude changes. Therefore, the current waveform with respect to the rotor position when the high-frequency voltage is applied is also an ideal sine waveform with two oscillation components spanning 360 degrees.

[0015] If the drive voltages for detecting magnetic pole positions, on which the high-frequency voltage is superimposed, are applied to the rotating electrical machine of the permanent magnet type with the ideal inductance distribution as in Fig. 2 and the measured current is converted into coordinates with respect to the d- and q-axis, a Fig. 3 is obtained. In other words, the current trajectory changes depending on a change in the inductance with respect to the rotor position and thus forms an elliptical trajectory with respect to the d- and q-axes. It should be noted that in Fig. 3 a ratio of the minor axis to the major axis of the ellipse represents a salience ratio.

[0016] Furthermore, in the permanent magnet type rotating electric machine with the ideal inductance distribution, neither phase shift nor distortion in the inductance distribution occurs due to the load current. Thus, when the load current is applied, an elliptical trajectory is drawn that is shifted in the q-axis direction, which is the driving current direction. After offset processing is applied to the q-axis current corresponding to the driving current, the current trajectories are the same elliptical trajectories in both the no-load and loaded states.

[0017] It should be noted that, as described above, an actual permanent magnet type rotating electric machine does not have an ideal inductance distribution and therefore the estimation error of the magnetic pole position is so large that positioning control cannot be performed with high accuracy. Fig. 4 then shows an actual inductance distribution obtained as a result of an investigation of the rotor position of the actual permanent magnet type rotating electric machine.

[0018] In Fig. 4, the actual inductance distribution includes the high frequency component (distortion component), and thus it is clear that the actual inductance distribution has a different shape from the ideal sine waveform, and the amplitude of the inductance distribution decreases depending on the magnitude of the supplied current, thereby causing the phase shift.

[0019] In addition, if the inductance distribution with respect to the rotor position of the permanent magnet type rotating electrical machine is as shown in Fig. 4 and the measured high frequency current is converted into coordinates with respect to the d and q axes, the Fig. 5 is generated. In other words, the current trajectory of the high-frequency current changes depending on a change in the inductance and therefore forms an elliptical trajectory with respect to the d- and q-axes.

[0020] In addition, Fig. 6 shows a current trajectory after the offset processing corresponding to the drive current to focus on the change in the elliptical shape resulting from the load current. Fig. From Figure 6, it can be understood that the inductance of an actual permanent magnet rotating electric machine does not have a sine waveform, the ellipse is tilted even in the no-load state (the major axis of the ellipse rotates), and the gradient of the ellipse continues to change under the load state. As a result, the error in estimating the magnetic pole positions of an actual permanent magnet rotating electric machine is large, and positioning control cannot be performed with high accuracy.

[0021] In a permanent magnet type rotating electrical machine, in which the high frequency voltage different in frequency and amplitude from the voltages for generating torque is applied to the armature windings to measure magnetic pole positions of the rotor using the current trajectory of the high frequency current to highly accurately estimate the magnetic pole positions to perform high precision positioning control, the inductance distribution must be the ideal sinusoidal distribution regardless of the load current and the rotor position.

[0022] However, the actual inductance distribution does not have a sine waveform, and phase shift occurs due to a load, making it difficult to generate the inductance distribution in a perfect sine waveform. Therefore, according to the first embodiment of the present invention, based on the aforementioned sensorless drive theory, motor performance conditions (current response conditions) required for the rotation sensorless drive were set forth.

[0023] In other words, as a result of magnetic field analysis for the permanent magnet type rotating electric machine and simulation for the rotation sensorless drive, it was found that the following conditions 1 to 3 as current response conditions required for the rotation sensorless drive must be satisfied simultaneously.

[0024] Specifically, when a high-frequency voltage different in frequency and amplitude from the voltages for generating torque is applied to the armature windings and the measured high-frequency current is dq-converted, the current trajectory has the elliptic shape on the d- and q-axes (Condition 1), an angular change range of the major axis of the ellipse with respect to the load current is reduced so that a predetermined position estimation resolution is achieved (Condition 2), and an angular change range of the major axis of the ellipse with respect to the rotor position is reduced so that the predetermined position estimation resolution is achieved (Condition 3).

[0025] First, condition 1 (the current trajectory of the high-frequency current on the d- and q-axis has an elliptic shape) depends on a performance of a current sensor to be used, but considering that an error of a normal sensor is about ±3%, a ratio of the minor axis to the major axis of the ellipse (salience ratio of the motor) must be equal to or more than 6%.

[0026] If the ratio of the minor axis to the major axis of the ellipse (motor salience ratio) is 5% or less, the difference in current on the d- and q-axes will be inconspicuous in error, and position estimation cannot be performed. Forming the current trajectory in an elliptical shape means that the inductance distribution contains a fundamental wave component, which corresponds to the condition that the permanent magnet rotating electric machine has salience.

[0027] Then, regarding condition 2 (reduction of the angular change range of the major axis of the ellipse with respect to the load current), as a result of the magnetic field analysis for the permanent magnet type rotating electric machine and the simulation for the rotation sensorless drive, it was found that the angular change range by the load current is proportional to the number of pole pairs of the motor and inversely proportional to the resolution of the magnetic pole position detection and a torque ripple ratio of the motor.

[0028] When the gradient angle of the ellipse changes due to the load current, a correction corresponding to the change is made by means of a closed-loop control. For example, if the difference in the change amount of the gradient angle of the ellipse between the no-load state and the rated load state is L degrees, the correction amount Δθ of the gradient of the ellipse is represented as Δθ = L x q-axis current.

[0029] On the other hand, in a permanent magnet-type rotating electrical machine, even when a sinusoidal current is supplied, the presence of a harmonic component of an induced voltage causes torque ripple to occur. Therefore, even if the load torque is constant, if torque ripple exists, a current component to compensate for the torque ripple component is superimposed on the q-axis current to perform constant speed control.

[0030] For example, in a permanent magnet-type rotating electric machine with a torque ripple width B (±B / 2), the q-axis current also varies by ±B / 2 during constant speed holding, resulting in a position error. Therefore, the position error must be set to fall within the range of a magnetic pole position detection resolution A, and a setting condition can be expressed by Equation (1). H×W / 2≤360 / A×number of pole pairs

[0031] Thus, a change range H of the gradient of the ellipse between the no-load state and the rated load state required to achieve the target magnetic pole position detection resolution A must have a value represented by equation (2). H≤360 / A×number of pole pairs / B / 2=360 / A / B×number of pole pairs

[0032] The above description assumes that the correction is performed in proportion to the magnitude of the q-axis current. However, the magnitude of a control gain also affects the correction, and if the control gain cannot be increased sufficiently, the correction cannot be performed. As a result, there was a case where the target magnetic pole position detection resolution could not be obtained within the change range H satisfying Equation (2). According to a result of a past study by the present inventors, for a general correction gain, the change range of the gradient of the ellipse between the no-load state and the rated load state must be approximately equal to or less than 1 / 3 of Equation (2).

[0033] Then, regarding Condition 3 (reduction of the angular change range of the major axis of the ellipse with respect to the rotor position), the magnetic field analysis for the permanent magnet rotating electric machine and the simulation for the rotation sensorless drive revealed that the angular change range of the rotor position is proportional to the number of pole pairs of the motor and inversely proportional to the resolution of the magnetic pole position detection. When the change range of the major axis of the current trajectory ellipse with respect to the rotor position is S degrees, Equation (3) is satisfied. A≤360 / S / 2×number of pole pairs

[0034] Thus, in order to obtain the target magnetic pole position detection resolution A, the change range S of the major axis of the current trajectory ellipse with respect to the rotor position must have a value represented by equation (4). S≤360 / 2×number of pole pairs / A=360 / A×number of pole pairs

[0035] Current response conditions of the motor suitable for rotation sensorless drive have been described. When the target resolution of the rotation sensorless drive is equal to or greater than 200 pulses / revolution, the motor torque ripple range is 0.1 (10%), and the number of pole pairs is 5, the specific current response conditions are as follows. In other words, the motor must be designed so that the change range H of the gradient of the ellipse between the no-load state and the rated load state satisfies H ≤ 360 / 200 / 0.1 x 5 / 3 = 30 degrees, and the change range S of the major axis of the current trajectory ellipse with respect to the rotor position satisfies S ≤ 360 / 200 x 5 = 9 degrees.

[0036] In the design of the permanent magnet type rotating electrical machine, while magnetic structures to increase torque and reduce cogging torque and torque ripple are carefully studied, magnetic structures to reduce the changes caused by load current and rotor position by making the inductance distribution closer to the sine waveform are hardly studied.

[0037] In particular, the inductance distribution becomes non-sinusoidal due to the formation of higher harmonic wave components caused by magnetic saturation and the slots, and thus, a magnetic structure for optimizing the inductance distribution was unknown. Therefore, a permanent magnet type rotating electrical machine that simultaneously meets all conditions 1 to 3 and is suitable for rotation sensorless drive was investigated with regard to the rotor and stator shapes using magnetic analysis. Fig. Figure 7 shows a representative example of a magnetic analysis result.

[0038] Out of Fig. 7, it becomes clear that an IPM structure must be chosen to satisfy condition 1. On the other hand, it becomes clear that an SPM structure with 10 poles and 12 slots can be chosen to satisfy conditions 2 and 3. However, the SPM structure cannot ensure the saliency defined in condition 1 and thus cannot be applied to the rotary sensorless drive.

[0039] Then, in addition to the rotor structure and the number of poles and slots, a slot opening ratio was considered, and a magnetic field analysis was conducted. As a result, it was found that a permanent magnet type rotating electric machine that simultaneously satisfies all of Conditions 1 to 3 must have an IPM structure, 10 poles, 12 slots, and a slot opening ratio equal to or greater than 0.6. A detailed description of a structure of the permanent magnet type rotating electric machine according to the first embodiment of the present invention will now be given.

[0040] Fig. 8 is a cross-sectional view illustrating a structure of the permanent magnet type rotating electric machine according to the first embodiment of the present invention. Fig. 8, the permanent magnet type rotating electrical machine comprises a stator 10 and a rotor 20. The stator 10 includes a stator iron core 11 and armature windings 12, and the rotor 20 includes a rotor iron core 21 and permanent magnets 22. The permanent magnets 22 are inserted into 10 holes provided within an outer peripheral surface of the rotor iron core 21 at an equal interval in the circumferential direction.

[0041] The stator iron core 11, having cylindrical teeth on which armature windings 12 for generating rotating magnetic fields for rotating the rotor 20 are provided, is divided into N stator blocks in the circumferential direction. Here, when a gap in the circumferential direction between circumferentially adjacent distal ends of the stator iron core 11 is represented as La, a tooth size in the circumferential direction is represented as Lb, and an inner diameter dimension of the stator iron core 11 is represented as D, the gap La in the circumferential direction between the distal ends of the stator iron core 11 is set to satisfy Equation (5). 0.6 <La / (πD / N−Lb)<1,0

[0042] This shows Fig. Figure 9 shows a relationship calculated by magnetic field analysis between the slot opening ratio and a phase shift (phase shift at inductance) between the main axis in the no-load state and the main axis in the loaded state of the current trajectory ellipse. Furthermore, Fig. Figure 10 shows a calculated relationship between the slot opening ratio and the salience ratio of the rotating electrical machine, which corresponds to a relationship between the minor axis and the major axis of the current trajectory ellipse, and a calculated relationship between the slot opening ratio and the change in the major axis of the current trajectory ellipse with respect to the rotor position. It should be noted that the slot opening ratio is a value represented by Equation (6). La / (πD / N−Lb)

[0043] Out of Fig. 9 and Fig. 10, it is clear that an optimal slot opening ratio is equal to or more than 0.6 in order to reduce the phase shift between the no-load major axis and the loaded major axis of the current trajectory ellipse, and to reduce the variation of the major axis of the current trajectory ellipse with respect to the rotor position, while the ratio of the minor axis to the major axis of the current trajectory ellipse should be equal to or more than 1.06. This is because slot leakage flux can be reduced by increasing the slot opening ratio, and thus a change in the magnetic saturation state inside the stator iron core 11 caused by the load current and the rotor position can be restricted.

[0044] The lower limit of the slot opening ratio is set to 0.6, but an even larger slot opening ratio can increase the ratio of the minor axis to the major axis of the current trajectory ellipse, reduce the phase shift between the main axis in the no-load state and the main axis in the loaded state of the current trajectory ellipse, and reduce the change of the major axis to the current trajectory ellipse with respect to the rotor position. Therefore, as the slot opening ratio approaches 1.0, the motor becomes more suitable for rotation sensorless drive.

[0045] Furthermore, the size Lb of the tooth in the circumferential direction is set so that equation (7) is satisfied when D is the inner diameter dimension of the stator iron core 11 and N is the number of pitches in the circumferential direction of the stator blocks. 0.57≥Lb / (πD / N)

[0046] This shows Fig. 11 shows a relationship between the tooth width ratio and the salience ratio of the rotating electrical machine, which corresponds to the relationship between the minor axis and the major axis of the current trajectory ellipse, and a relationship between the tooth width ratio and the change in the major axis of the current trajectory ellipse with respect to the rotor position, which are calculated by magnetic field analysis. It should be noted that the tooth width ratio is set to correspond to a value represented by Equation (8). Lb / (πD / N)

[0047] Out of Fig. 11, it is clear that even when the tooth width ratio changes, the change in the major axis of the current trajectory ellipse with respect to the rotor position hardly changes, but the ratio of the minor axis to the major axis of the current trajectory ellipse abruptly increases at a point where the tooth width ratio becomes equal to or less than 0.57. This is because the reduction in the tooth width ratio can limit the change caused by the load current and the rotor position under the state of magnetic saturation inside the rotor iron core 11, and it is clear that as the tooth width ratio decreases, the motor becomes more suitable for rotation sensorless driving.

[0048] Furthermore, punching the iron core generates machining deformation and residual stress, thus deteriorating magnetic properties. Therefore, according to the first embodiment of the present invention, the stator iron core 11 is divided in the circumferential direction to also reduce the magnetic properties at divided portions of the stator 10, thereby stably magnetically saturating the iron core. This design can also limit the change in the magnetic saturation state inside the stator iron core 11 caused by the load current and the rotor position.

[0049] As described above, the stable magnetic saturation of the iron core can restrict the change in the state of magnetic saturation inside the stator iron core 11, can reduce the phase shift between the main axis in the no-load state and the main axis in the loaded state of the current trajectory ellipse, and can reduce the change of the main axis of the current trajectory ellipse with respect to the rotor position.

[0050] Furthermore, if P is the number of magnetic poles of the permanent magnet rotating electric machine and N is the number of slots, P and N are set such that P / (the greatest common factor of P and N) is an odd number. As a result, the variation of the major axis of the current trajectory ellipse with respect to the rotor position can be reduced. Furthermore, electrolytic corrosion of a bearing can be cited as a failure factor of the permanent magnet rotating electric machine, but the above-mentioned adjustment of P and N can prevent the generation of voltage on a shaft, making the motor more suitable for rotation sensorless drive. Furthermore, the position dependence of the inductance can be reduced.

[0051] As described above, according to the first embodiment, in the case where the high-frequency current measured when the high-frequency voltage is applied is dq-converted, the current trajectory forms the elliptic shape on the d- and q-axes, and the angular change ranges of the major axis of the ellipse are adjusted with respect to the load current and the rotor position so that the predetermined position estimation resolution is obtained.

[0052] Therefore, a permanent magnet type rotating electric machine can be provided in which the position of the rotor can be detected with high accuracy during sensorless driving. Second embodiment

[0053] Fig. 12 is a cross-sectional view illustrating a structure of a permanent magnet type rotating electric machine according to a second embodiment of the present invention. Fig.12, when R0 is an outer radius of the rotor 20 and R1 is a radius of curvature of a surface of the rotor 20, R0 and R1 are set so that R0 > R1 is satisfied.

[0054] As a result, the magnetomotive force of a high-frequency magnetic flux of the rotor 20 can be reduced, and the variation of the major axis of the current trajectory ellipse with respect to the rotor position can be reduced. According to the second embodiment of the present invention, compared to the rotor shape according to the first embodiment, which has the relationship R0 = R1, the variation of the major axis of the current trajectory ellipse with respect to the rotor position can be reduced by approximately 75%. Furthermore, the position dependence of the inductance can be further reduced.

[0055] The permanent magnet-type rotating electric machines according to the first and second embodiments enable the estimation of the magnetic pole position without a motor rotation detection device such as an optical encoder or resolver. Therefore, the number of components and error factors can be reduced. As a result, high reliability and low cost can be achieved. It should be noted that the optical encoder and resolver can be used in combination. List of reference symbols 10 Stator 11 Stator iron core 12 Armature winding 20 rotors 21 Rotor iron core 22 permanent magnet

Claims

[1] Rotating electrical machine of the permanent magnet type, comprising: a rotor (20) comprising a plurality of equally spaced magnetic poles; and a stator (10) comprising a plurality of teeth and a plurality of armature windings (12), wherein: the rotor (20) comprises permanent magnets (22) inserted into P openings provided within an outer peripheral surface of a rotor iron core (21) at an equal distance in the circumferential direction; the stator (10) comprises a stator iron core (11) having N teeth and a cylindrical shape, on which the plurality of armature windings (12) for generating a rotating magnetic field to rotate the rotor are provided, wherein the stator iron core (11) is divided into N stator blocks in the circumferential direction; and an adjustment is made so that 0.6 < La / (πD / N - Lb) < 1.0 is satisfied, where La is a gap in the circumferential direction between distal end portions of the stator iron core (11) adjacent to each other in the circumferential direction, Lb is a size of each of the plurality of teeth in the circumferential direction, and D is an inner diameter dimension of the stator iron core (11), and P and N are set so that P / (greatest common divisor of P and N) is an odd number; and wherein the size Lb of each of the plurality of teeth of the stator (10) in the circumferential direction is set so that 0.57 ≥ Lb / (πD / N) is satisfied. [2] A permanent magnet type rotating electric machine according to claim 1, wherein R0 and R1 are set to satisfy R0 > R1, where R0 is an outer radius of the rotor (20) and R1 is a radius of curvature of a surface of the rotor (20). [3] A permanent magnet type rotating electric machine according to claim 1 or 2, wherein positioning control is performed without using a rotation detecting device.

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