JP5412922B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor in which alternating magnetic flux flows in each magnetic circuit by controlling energization to a plurality of stator windings wound with a magnetic body as a core.

  For example, Patent Document 1 discloses an electric motor configured to reduce cogging torque and torque unevenness. In this electric motor, the armature core is formed by forming ten teeth formed in a substantially T shape with a base portion and a claw portion on the outer diameter of a ring-shaped boss portion. A notch groove is formed on the outer periphery of each claw so as to be asymmetric with respect to each other so that the teeth facing the magnetic pole ends of each permanent magnet are asymmetric with each other.

JP 2003-47184 A

  However, in the method disclosed in Patent Document 1, the loss of the entire motor is increased by generating a harmonic component (slot harmonic component) of the magnetic flux in the magnetic circuit formed by the magnetic bodies constituting the stator and the rotor. There is a problem of end up. Therefore, there is a disadvantage that the efficiency of the electric motor is reduced.

  This invention is made | formed in view of this situation, The objective is to suppress the efficiency fall of an electric motor by suppressing the harmonic component of magnetic flux.

In order to solve such a problem, the present invention includes a harmonic magnetic flux suppression element that suppresses a harmonic magnetic flux having a predetermined cutoff frequency or higher in the magnetic flux flowing through each of the magnetic circuits. In this case, each magnetic circuit is configured so that the magnetic properties of the magnetic bodies forming the magnetic circuit are asymmetric with respect to each of the stator windings. The stator includes a plurality of teeth for stator winding corresponding to n (n: natural number) times the number of phases. In addition, each of the magnetic circuits corresponding to the same phase has different magnetic characteristics of the magnetic bodies constituting the magnetic circuit. Each of the plurality of teeth is wound with a filter winding. The harmonic suppression element is configured by n closed circuits in which filter windings corresponding to the same phase are connected in parallel.

  According to the present invention, the magnetic characteristics of the magnetic bodies forming the magnetic circuit correspond to each of the stator windings in an asymmetric relationship with each other. The component (slot harmonic component) can be suppressed. Therefore, an increase in the loss of the entire motor can be suppressed, and a decrease in efficiency of the motor can be suppressed.

FIG. 2 is a developed plan view schematically showing the structure of the electric motor 10 according to the first embodiment. Circuit configuration diagram including electric motor 10 and power converter 30 Explanatory drawing which shows the spectrum of the magnetic flux linked to the core part of the U-W phase in the electric motor 10 which has the stator teeth 11a concerning 1st Embodiment. Explanatory drawing showing vector sum of flux linkage of each phase including phase information Plane expansion view schematically showing the structure of the electric motor 10 according to the second embodiment. Circuit configuration diagram including electric motor 10 and power converter 30

  FIG. 1 is a developed plan view schematically showing the structure of the electric motor 10 according to the first embodiment of the present invention. The electric motor 10 according to the present embodiment is a permanent magnet type synchronous motor, and is configured as a radial gap inner rotor type. The electric motor 10 includes a stator (stator) 11 having a ring-shaped cross section, and a rotor (movable element) 12 connected to a shaft (not shown). The rotor 12 has an air gap on the inner peripheral side of the stator 11. Is arranged through.

  The stator 11 is configured by, for example, laminating a plurality of magnetic electromagnetic steel plates in the axial direction, and includes a plurality of stator teeth 11a and a substantially ring-shaped back yoke 11b. The plurality of stator teeth 11a are arranged at equal intervals on the inner peripheral side of the back yoke 11b, and the individual stator teeth 11a are projected to the rotor 12 side. The back yoke 11b connects the individual stator teeth 11a on the base end side.

  The stator 11 is housed inside the stator case by fitting it into a cylindrical stator case (not shown) using a method such as shrink fitting. Thereby, the stator 11 is fixedly held by the stator case in a state where an external force is generally applied from the outer peripheral side in the entire circumferential direction.

  In this embodiment, the stator 11 includes stator teeth 11a for stator winding corresponding to nine phases (three phases × 3), and each stator tooth 11a is provided with an insulator (insulating member) 13 (not shown). Each of the stator windings 13 is wound. The nine stator windings 13 include three stator windings 13 corresponding to the U1, V1 and W1 phases, three stator windings 13 corresponding to the U2, V2 and W2 phases, U3 phase and V3. And three stator windings 13 corresponding to the W3 phase. In each of the three sets of U phase to W phase (U1 phase to W1 phase, U2 phase to W2 phase, U3 phase to W3 phase), the sum of the currents respectively supplied to the three stator windings 13 in the same set is It becomes zero.

  On the other hand, the rotor 12 is formed, for example, by laminating a plurality of magnetic steel sheets made of magnetic material around the shaft in the axial direction. A plurality of permanent magnets 15 are embedded in the rotor 12 at equal intervals along the circumferential direction.

  This electric motor 10 is based on an interaction between a magnetic field generated by supplying nine-phase AC power to a corresponding phase stator winding 13 from a power converter 30 described later and a magnetic field generated by a permanent magnet of a rotor. To drive. Specifically, in the electric motor 10, a magnetic circuit is constituted by a permanent magnet 15 embedded in the rotor 12, a magnetic body (electromagnetic steel plate) constituting the rotor 12 itself, and a magnetic body (electromagnetic steel plate) constituting the stator 11. Is formed. Then, the magnet magnetic flux from the permanent magnet 15 and the alternating magnetic flux generated by energizing the stator winding 13 by inverter control flow through this magnetic circuit, thereby generating torque due to electromagnetic force, which is connected to the rotor 12 and this. Rotated shaft rotates.

  As one of the features of the present embodiment, the three stator teeth 11a around which the three-phase stator windings 13 having a current sum of zero are wound have their tip shapes (shapes of tip portions protruding toward the rotor 12). Are formed in the same shape. Specifically, the tips of the stator teeth 11a around which the U1-phase, V1-phase, and W1-phase stator windings 13 are wound are formed in the same shape, and the U2-phase, V2-phase, and W2-phase stator windings are formed. The tip shape of each stator tooth 11a around which the wire 13 is wound is also formed in the same shape. The tip shapes of the stator teeth 11a around which the stator windings 13 of the U3-phase, V3-phase, and W3-phase are wound are also formed in the same shape.

  For example, the tip shape of normal stator teeth is a flange shape having a protruding portion that protrudes outward in the entire periphery. In the present embodiment, the tip shape of each stator tooth 11a corresponding to the U1 phase, the V1 phase, and the W1 phase corresponds to one side surface portion (the right side in the drawing) of the pair of side surface portions extending in the axial direction. The protruding part to be cut has a cut-out shape. On the other hand, the tip shape of each stator tooth 11a corresponding to the U2 phase, the V2 phase, and the W2 phase is a flange shape having a protruding portion that protrudes outward on the entire periphery. Further, the tip shape of each stator tooth 11a corresponding to the U3 phase, the V3 phase, and the W3 phase has a protruding portion corresponding to the other side surface portion (left side in the drawing) of the pair of side surface portions extending in the axial direction. The shape is cut out.

  On the other hand, the tip shapes of the individual stator teeth 11a are set so as to have different shapes (asymmetric) with respect to those corresponding to the same phase. As described above, the tips of the stator teeth 11a corresponding to the U1, U2, and U3 phases are formed to have different shapes, and the stator teeth corresponding to the V1, V2, and V3 phases are formed. The tip shape of 11a is also formed to have different shapes. Further, the tip shapes of the stator teeth 11a corresponding to the W1, W2, and W3 phases are also formed to have different shapes. Due to the asymmetry of the shape, the magnetic characteristics of the magnetic body (stator teeth 11a) on which the magnetic circuit is formed are set to be different from each other corresponding to the same phase.

  In the present embodiment, filter windings 14, which are separate from the stator windings 13, are wound around the individual stator teeth 11 a. The filter winding 14 has a function as a harmonic magnetic flux suppressing element that suppresses the harmonic magnetic flux in the magnetic flux flowing through the magnetic circuit, and details thereof will be described later.

  FIG. 2 is a circuit configuration diagram including the electric motor 10 and the power converter 30. The power converter 30 is connected to the power source 20, converts DC power from the power source 20 into nine-phase AC power, and supplies the converted nine-phase AC power to the electric motor 10. The power converter 30 includes three three-phase inverters 31 to 33 each outputting three-phase AC power including a U phase, a V phase, and a W phase. The input sides of the individual three-phase inverters 31 to 33 are connected to the power source 20 via the positive and negative DC buses, and the three three-phase inverters 31 to 33 are connected in series. The output side of the first three-phase inverter 31 is connected to the three stator windings 13 corresponding to the U1, V1, and W1 phases, and the output side of the second three-phase inverter 32 is the U2 phase, V2 phase. , W is connected to three stator windings 13 corresponding to the W2 phase. The output side of the third three-phase inverter 33 is connected to three stator windings 13 corresponding to the U3 phase, the V3 phase, and the W3 phase. Each of the three-phase inverters 31 to 33 converts the DC power from the power source 20 into three-phase (U-phase, V-phase, W-phase) AC power whose current sum is zero, and the converted three-phase inverter AC power is supplied to each corresponding stator winding 13.

  Each of the three-phase inverters 31 to 33 includes a switch corresponding to the upper arm between the DC bus on the positive electrode side and the output terminals corresponding to the three phases, and the DC bus on the negative electrode side and the three-phase inverter. A switch corresponding to the lower arm is provided between each output terminal corresponding to. Each switch is mainly composed of a semiconductor switch capable of controlling conduction in one direction (for example, a switching element such as a transistor such as an IGBT), and a reflux diode is connected in reverse parallel to each semiconductor switch. Yes.

  The open / close state of the individual switches corresponding to the upper and lower arms is controlled by a control device (not shown) by a control method such as PWM wave voltage drive. The PWM wave voltage drive generates a PWM wave voltage from DC power and applies it to the electric motor 10. Specifically, PWM control is performed based on a carrier voltage and a sine wave control voltage, and a duty command value for PWM control is set. This is a driving method in which an equivalent sine wave AC voltage is applied to the motor 10 by calculation. When the power converter 30 is controlled by this PWM wave voltage drive, the phase of the PWM carrier is offset by 40 degrees in the three three-phase inverters 31 to 33.

  Hereinafter, the harmonic magnetic flux suppressing element which is one of the features of the present embodiment will be described. The harmonic magnetic flux suppressing element is configured by a filter winding 14 wound around each stator tooth 11a. Specifically, the harmonic magnetic flux suppressing element is configured by a closed circuit in which the filter windings 14 are connected in parallel for each of the three filter windings 14. Since this embodiment, which is a nine-phase motor 10, includes nine filter windings 14, harmonic suppression elements corresponding to three closed circuits are formed. In each closed circuit, each filter winding 14 is connected in series with a resistance element for adjusting a cutoff frequency and for cooling.

  In the present embodiment, the tip shapes of the individual stator teeth 11a are different from each other in the same phase, and the three filter windings 14 constituting the individual closed circuits are respectively output from the three three-phase inverters 31 to 33. It is determined according to the current of each phase. Specifically, in one closed circuit, three filter windings 14 are connected so that in-phase currents having different carrier phases pass through the closed circuit, in other words, filter windings corresponding to the in-phase. Each of the lines 14 is connected in parallel. In the present embodiment, the first closed circuit is configured by connecting three filter windings 14 corresponding to the U phase so that the U1 phase current, the U2 phase current, and the U3 phase current pass through the closed circuit. The The second closed circuit is configured by connecting three filter windings 14 corresponding to the V phase such that the V1 phase current, the V2 phase current, and the V3 phase current pass through the closed circuit. The third closed circuit is configured by connecting three filter windings 14 corresponding to the W phase so that the W1 phase current, the W2 phase current, and the W3 phase current pass through the closed circuit.

  The harmonic magnetic flux suppression element constituted by such a closed circuit has a predetermined cutoff frequency or more out of the magnetic flux flowing through the magnetic circuit, that is, the magnetic flux in the magnetic flux path, when a circulating current is induced in the closed circuit. Suppresses the passage of alternating magnetic flux of higher harmonics. In other words, in the electric motor 10, a harmonic alternating magnetic flux higher than the cutoff frequency determined by the closed circuit characteristics (resistive element) in the magnetic flux flowing through the magnetic circuit is closed by the three filter windings 14. Passage is suppressed by the circuit. Attenuation of the harmonic alternating magnetic flux reduces the distortion rate of the waveform of the magnetic flux flowing through the magnetic circuit, thereby increasing the fundamental component ratio. The energy of the harmonic alternating magnetic flux is consumed as local iron loss (eddy current loss and hysteresis loss) in the harmonic magnetic flux suppressing element. Thereby, an iron loss will be reduced.

  As described above, the harmonic magnetic flux suppressing element has a function of reducing the iron loss of the magnetic circuit by suppressing the passage of an alternating magnetic flux having a predetermined cutoff frequency or higher. Here, if the cutoff frequency by the harmonic magnetic flux suppressing element is excessively small, not only the alternating magnetic flux of the harmonics but also the fundamental wave component contributing to the torque of the electric motor 10 is reduced. On the other hand, if the cutoff frequency by the harmonic magnetic flux suppressing element is excessively large, the original function of reducing the iron loss of the magnetic circuit cannot be achieved. For this reason, it is desirable for the harmonic magnetic flux suppressing element to obtain an optimum cutoff frequency characteristic according to the performance and application of the electric motor 10.

  As described above, in the present embodiment, the electric motor 10 includes the harmonic magnetic flux suppressing element that suppresses the harmonic magnetic flux having a frequency equal to or higher than the predetermined cutoff frequency in each of the magnetic fluxes flowing through the plurality of magnetic circuits. In addition, each of the magnetic circuits is configured such that the magnetic properties of the magnetic bodies on which the magnetic circuit is formed are asymmetric with respect to each other. Specifically, each of the stator teeth 11a corresponds to the same phase, and the magnetic characteristics of the stator teeth 11a in which the shapes of the tip portions are different from each other in the rotation direction of the rotor 12 and a magnetic circuit is formed are: Those corresponding to the same phase are different from each other. The harmonic suppression element is configured by three closed circuits in which the filter windings 14 corresponding to the same phase are connected in parallel.

  In the electric motor 10, when PWM wave voltage driving is performed using the power converter 30 as a driving method, the core harmonics of the stator 11, the rotor 12, the permanent magnet 15, and the like formed of electromagnetic steel plates have slot harmonic components. In addition, a carrier harmonic component resulting from PWM wave voltage drive is contained, which causes an increase in iron loss.

  FIG. 3 is an explanatory diagram showing a spectrum of magnetic flux interlinked with the core portion of the U to W phase in the electric motor 10 having the stator teeth 11a according to the present embodiment. In an electric motor having stator teeth with symmetrical tip shapes, the spectra of magnetic fluxes interlinking with U-phase, V-phase, and W-phase stator teeth are substantially the same. Since the U-phase, V-phase, and W-phase are 120 degrees out of phase, no induced voltage difference occurs in the closed circuit composed of the three filter windings 14, so that the closed circuit (harmonic magnetic flux suppression element) The current does not flow and the harmonic magnetic flux cannot be suppressed. However, according to the present embodiment, the tip shape of the stator teeth 11a is asymmetric. Thereby, an amplitude difference and a phase difference can be generated in the slot harmonic component in each phase. As a result, as shown in FIG. 3, the interlinkage magnetic flux spectrum of each phase can be made different. FIG. 4 is an explanatory diagram showing the vector sum of the interlinkage magnetic flux of each phase including the phase information. Here, in the same figure, square plots indicate vector sums for motors having symmetrical stator teeth, and rhombus plots indicate vector sums for motor 10 having asymmetric stator teeth 11a. As can be seen from the figure, in the electric motor 10 having the asymmetric stator teeth 11a, the vector sum has a finite value. Thereby, in the case of the asymmetric stator teeth 11a, a circulating current is induced in the closed circuit which is a harmonic magnetic flux suppressing element, and the harmonic component (slot harmonic component) of the magnetic flux in the magnetic circuit can be suppressed. Therefore, an increase in the loss of the entire motor can be suppressed, and a decrease in efficiency of the motor 10 can be suppressed.

  Further, in the present embodiment, each of the stator windings 13 is energized through three three-phase inverters 31 to 33 that are PWM wave voltage driven using three types of PWM carriers having different phases. According to such a configuration, in addition to the slot harmonic component, the carrier harmonic component can also be suppressed, so that the efficiency reduction of the electric motor 10 can be further suppressed.

(Second Embodiment)
Hereinafter, the electric motor 10 concerning the 2nd Embodiment of this invention is demonstrated. The electric motor 10 according to the second embodiment differs from that of the first embodiment in the circuit configuration of the pattern of the tip shape of the stator teeth 11a and the harmonic magnetic flux suppressing element. The description of the configuration common to the first embodiment will be omitted, and the following description will focus on the differences.

  FIG. 5 is a developed plan view schematically showing the structure of the electric motor 10 according to the second embodiment of the present invention. In the present embodiment, the tip shapes of the individual stator teeth 11a are formed in the same shape for those corresponding to the same phase. Specifically, the tip shapes of the stator teeth 11a around which three sets of U-phase (U1-phase to U3-phase) stator windings 13 are wound are set to the same shape, and three sets of V-phase (V1-phase) are set. The tip shape of the stator teeth 11a around which the (V3 phase) stator winding 13 is wound is also set to the same shape. The tip shapes of the stator teeth 11a around which the three sets of W-phase (W1-phase to W3-phase) stator windings 13 are wound are also set to the same shape.

  On the other hand, the tip shape of each stator tooth 11a is set to have a different shape (asymmetric) for each phase. For example, the tip shape of normal stator teeth is a flange shape having a protruding portion that protrudes outward in the entire periphery. In the present embodiment, each of the tip shapes of the stator teeth 11a corresponding to the three sets of U phases is a protrusion corresponding to one side surface portion (the right side in the drawing) of the pair of side surface portions extending in the axial direction. The part is cut out. On the other hand, each of the tip shapes of the stator teeth 11a corresponding to the three sets of V phases has a flange shape having a protruding portion that protrudes outward in the entire periphery. In addition, each of the tip shapes of the stator teeth 11a corresponding to the three sets of W phases has a protruding portion corresponding to the other side surface portion (the left side in the drawing) of the pair of side surface portions extending in the axial direction. The shape is missing. Thereby, the magnetic characteristics of the magnetic body (stator teeth 11a) on which the magnetic circuit is formed are made different for each phase.

  Hereinafter, the harmonic magnetic flux suppressing element of this embodiment will be described. The harmonic magnetic flux suppressing element is configured by a filter winding 14 wound around each stator tooth 11a. Specifically, the harmonic magnetic flux suppressing element is configured by a closed circuit in which the filter windings 14 are connected in series for each of the three filter windings 14. In the present embodiment, which is the nine-phase electric motor 10, since nine filter windings 14 are provided, harmonic suppression elements corresponding to three closed circuits are formed. Each closed circuit is provided with one resistance element for adjusting the cutoff frequency and for cooling.

  In this embodiment in which the tip shapes of the individual stator teeth 11a are different from each other, the three filter windings 14 constituting the individual closed circuits are supplied with currents of respective phases output from the three three-phase inverters 31 to 33, respectively. Will be decided accordingly. Specifically, in one set of closed circuits, three filter windings 14 are connected so that U-phase current, V-phase current, and W-phase current having different carrier phases pass through the closed circuit, In other words, each of the filter windings 14 corresponding to each phase is connected in series. In the present embodiment, the first closed circuit includes three filter windings 14 corresponding to the U1, V2, and W3 phases so that the U1 phase current, the V2 phase current, and the W3 phase current pass through the closed circuit. It is comprised by connecting. The second closed circuit connects three filter windings 14 corresponding to the U2-phase, V3-phase, and W1-phase so that the U2-phase current, the V3-phase current, and the W1-phase current pass through the closed circuit. Composed. The third closed circuit connects three filter windings 14 corresponding to the U3 phase, the V1 phase, and the W2 phase so that the U3 phase current, the V1 phase current, and the W2 phase current pass through the closed circuit. It is constituted by.

  As described above, in the present embodiment, the electric motor 10 includes the harmonic magnetic flux suppressing element that suppresses the harmonic magnetic flux having a frequency equal to or higher than the predetermined cutoff frequency in each of the magnetic fluxes flowing through the plurality of magnetic circuits. In addition, each of the magnetic circuits is configured such that the magnetic properties of the magnetic bodies on which the magnetic circuit is formed are asymmetric with respect to each other. Specifically, in each of the stator teeth 11a, the shape of the tip is different in the rotation direction of the rotor 12 for each phase, and the magnetic characteristics of the stator teeth 11a in which the magnetic circuit is formed are different for each phase. Yes. Further, the harmonic magnetic flux suppressing element is configured by three closed circuits in which filter windings corresponding to the respective phases are connected in series.

  According to this configuration, similarly to the first embodiment, the circulating current is induced in the closed circuit that is the harmonic magnetic flux suppression element, and the harmonic component (slot harmonic component) of the magnetic flux in the magnetic circuit can be suppressed. it can. Therefore, an increase in the loss of the entire motor can be suppressed, and a decrease in efficiency of the motor 10 can be suppressed.

  Moreover, according to this embodiment, the winding which comprises the closed circuit which is a harmonic magnetic flux suppression element can be shortened compared with the method shown in 1st Embodiment. In addition, since only one resistive element constituting the closed circuit is provided in each closed circuit, the structure can be simplified.

  Note that the method of changing the tip shape of the stator teeth 11a is not limited to the above-described embodiment. In the present embodiment, the length of the flange portion at the tip of the stator teeth 11a (the length corresponding to the rotation direction of the rotor 12) is changed, but the position of this flange portion may be offset. . Moreover, you may notch a flange part in a different form.

  In the present embodiment, the magnetic properties of the magnetic bodies on which the magnetic circuit is formed are asymmetric with each other by changing the tip shape of the stator teeth 11a. Is not limited to this. For example, the shape of the stator teeth 11a are all the same, and the conductivity, hysteresis characteristics, plate thickness, saturation magnetic flux density, and permeability of the magnetic body (part of the stator 11 and part of the rotor) constituting the magnetic circuit. May be different from each other. For example, when the conductivity and thickness of the laminated steel plates constituting the stator 11 are changed, the eddy current characteristics when the magnetic flux alternates change, and a phase difference can be given by the frequency of the interlinking magnetic flux. Further, even when the saturation magnetic flux density and the magnetic permeability are changed, the change in the frequency component ratio due to the saturation can be generated.

DESCRIPTION OF SYMBOLS 10 ... Electric motor 11 ... Stator 11a ... Stator teeth 11b ... Back yoke 12 ... Rotor 13 ... Stator winding 14 ... Filter winding 15 ... Permanent magnet 20 ... Power source 30 ... Power converters 31-33 ... Three-phase inverter

Claims (8)

In an electric motor in which an alternating magnetic flux flows in each magnetic circuit by controlling energization to a plurality of stator windings wound with the magnetic body as a core by forming a magnetic circuit with a magnetic body constituting the stator and the rotor,
A harmonic flux suppression element that suppresses harmonic flux above a predetermined cutoff frequency in the magnetic flux flowing through each of the magnetic circuits,
Each of the magnetic circuits corresponds to each of the stator windings, and the magnetic characteristics of the magnetic body forming the magnetic circuit are configured asymmetrically .
The stator includes a plurality of teeth for stator winding corresponding to n (n: natural number) times the number of phases,
For each of the magnetic circuits corresponding to the same phase, the magnetic properties of the magnetic bodies constituting the magnetic circuit are different from each other,
Each of the plurality of teeth is wound with a filter winding,
The harmonic suppression element is constituted by n closed circuits in which the filter windings corresponding to the same phase are connected in parallel . 2. The electric motor according to claim 1 , wherein the teeth corresponding to the same phase are different from each other in a shape of a tip portion facing the rotor in a rotation direction of the rotor. Wherein, respectively that of the magnetic circuit, for each other corresponds to the phase, the conductivity of the magnetic body where the magnetic circuit is formed, the hysteresis characteristic, the sheet thickness, different at least one saturated magnetic flux density and permeability from each other The electric motor according to claim 1 or 2 . In an electric motor in which an alternating magnetic flux flows in each magnetic circuit by controlling energization to a plurality of stator windings wound with the magnetic body as a core by forming a magnetic circuit with a magnetic body constituting the stator and the rotor,
A harmonic flux suppression element that suppresses harmonic flux above a predetermined cutoff frequency in the magnetic flux flowing through each of the magnetic circuits,
Each of the magnetic circuits corresponds to each of the stator windings, and the magnetic characteristics of the magnetic body forming the magnetic circuit are configured asymmetrically.
The stator includes a plurality of teeth for stator winding corresponding to n (n: natural number) times the number of phases,
Each of the magnetic circuits, for each phase, Ri magnetic properties of the magnetic material in which the magnetic circuit is formed Do different,
Each of the plurality of teeth is wound with a filter winding,
The harmonic suppression element includes an n number of closed circuits in which filter windings corresponding to each phase are connected in series . 5. The electric motor according to claim 4 , wherein each of the teeth has a different shape of a tip portion facing the rotor in a rotation direction of the rotor for each phase. 5. The magnetic circuit according to claim 4 , wherein at least one of conductivity, hysteresis characteristics, plate thickness, saturation magnetic flux density, and magnetic permeability of the magnetic material in which the magnetic circuit is formed is different for each phase. 5. The electric motor described in 5 . Each of the stator windings, any one of claim 1, characterized in that the phase is energized via n multiphase inverters PWM wave voltage driving with different n types of PWM carrier 6 The electric motor described in one item. In an electric motor in which an alternating magnetic flux flows in each magnetic circuit by controlling energization to a plurality of stator windings wound with the magnetic body as a core by forming a magnetic circuit with a magnetic body constituting the stator and the rotor,
A harmonic flux suppression element that suppresses harmonic flux above a predetermined cutoff frequency in the magnetic flux flowing through each of the magnetic circuits,
Each of the magnetic circuits corresponds to each of the stator windings, and the magnetic characteristics of the magnetic body forming the magnetic circuit are configured asymmetrically.
The stator includes a plurality of teeth for stator winding corresponding to n (n: natural number) times the number of phases,
For each of the magnetic circuits corresponding to the same phase, the magnetic properties of the magnetic bodies constituting the magnetic circuit are different from each other,
Each of the stator windings is energized through n number of multiphase inverters driven by PWM wave voltage using n types of PWM carriers having different phases.

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