JP2005253155A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which can reduce the vibration of a stator by offsetting it by the electromagnetic force generated by a high frequency current. <P>SOLUTION: In a motor which is equipped with a rotor having eight pieces of magnets and a stator having forty eight pieces of teeth 1, 2, 3, 4, 5, a motor control current where an AC current AC<SB>-</SB>H of high frequency having frequency of the eighth rotation is superposed on an AC current for generation of a rotating field is supplied to the coil of the stator, and exciting force KP<SB>-</SB>48 having the forty eighth rotation degree applied to each tooth 1, 2, 3, 4, 5... is offset by electromotive force EMF<SB>-</SB>FT. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric motor, and more particularly to an electric motor capable of suppressing vibration of a stator.

  Patent Document 1 discloses a method of adding a series of harmonic currents to a basic rectangular current as a method of reducing torque ripple of an electric motor. That is, Patent Document 1 generates a torque component that is equal to and opposite to an unprocessed torque ripple waveform by a series of harmonic currents, and reduces the torque ripple generated by the basic rectangular current by the generated torque component. .

Patent Document 1 discloses that vibration can be reduced by reducing the torque ripple.
Japanese Patent Laid-Open No. 2002-119096 JP 2002-252947 A

  However, since Patent Document 1 determines the harmonic current to be added to the basic rectangular current so as to reduce the torque ripple, it is difficult to reduce the vibration of the stator caused by supplying an alternating current to the stator of the motor. There is a problem.

  Therefore, the present invention has been made to solve such a problem, and an object thereof is to provide an electric motor capable of reducing the vibration of the stator.

  Another object of the present invention is to provide an electric motor capable of suppressing the vibration of the stator.

  According to this invention, the electric motor includes a rotor, a stator, and a control device. The rotor includes a ferromagnetic member and has n (n is a natural number) rotor magnetic pole portions. The stator includes m teeth that are integer multiples of n and s coils that are provided corresponding to the s (s is plural) phase and are wound around the m teeth. The control unit generates a motor control current in which a high-frequency current is superimposed on an alternating current for generating a rotating magnetic field, supplies the motor control current to each of the s coils, and controls the rotor to rotate with respect to the stator. The high-frequency current is generated by an alternating current and is an alternating current for generating an electromagnetic force in the opposite direction to the excitation force applied to the stator with the ferromagnetic member of the rotor.

  Preferably, the high frequency current is an alternating current having a frequency of the order of rotation k determined by k = (m / s) / 2.

  Preferably, the control unit supplies a motor control current to each of the s coils by a pulse width modulation method.

  Preferably, the rotor includes a rotor core having a cylindrical surface surrounding the rotation axis. The m teeth and the s coils are arranged to face the cylindrical surface of the rotor core.

  Preferably, each of the n rotor magnetic pole portions includes a ferromagnetic member constituting a rotor core and a magnet.

  Preferably, the magnet is embedded in the ferromagnetic member from the rotational axis direction of the rotor and is magnetized in the radial direction of the rotor.

  Preferably, the magnet is disposed on the cylindrical surface and is magnetized in the radial direction of the rotor.

  Preferably, each of the n rotor magnetic pole portions is composed of only a ferromagnetic member constituting the rotor core.

  Preferably, each of the n rotor magnetic pole portions is made of a ferromagnetic material having magnetic salient pole characteristics in the radial direction of the rotor.

  According to the present invention, in an electric motor including a rotor having n (n is a natural number) rotor magnetic pole portions and a stator having m teeth that are integer multiples of n, an alternating current for generating a rotating magnetic field is provided. A motor control current in which a high-frequency current is superimposed on the current is supplied to each of the s coils. This high-frequency current is generated by an alternating current for generating a rotating magnetic field, and an electromagnetic force in the opposite direction to the excitation force applied to the stator is generated between the rotor and the ferromagnetic member. AC current. Then, the excitation force applied to the stator is weakened by the electromagnetic force generated by the high frequency current.

  Therefore, according to the present invention, the vibration of the stator can be reduced.

  In the electric motor according to the present invention, the motor control current obtained by superimposing the high-frequency current having the frequency k (= (m / s) / 2) of the frequency of the alternating current on the alternating current for generating the rotating magnetic field is superimposed. Supplied to the stator coil. Then, the excitation force applied to the m teeth generated by the alternating current for generating the rotating magnetic field is canceled by the electromagnetic force generated by the high frequency current.

  Therefore, according to the present invention, the vibration of the stator can be suppressed.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a sectional view of an electric motor according to an embodiment of the present invention. Referring to FIG. 1, an electric motor 100 according to an embodiment of the present invention includes a control device 10, a three-phase cable 20, a shaft 30, a rotor 40, and a stator 50.

  The rotor 40 includes a rotor core 41 and a magnet 42. Stator 50 includes a stator coil 51 and a stator core 52.

  The control device 10 receives a torque command value TR to be output from the electric motor 100 from an ECU (Electrical Control Unit) provided outside the electric motor 100, and outputs the torque specified by the received torque command value TR. A motor control current MCTLI for suppressing the vibration of the stator 50 is generated by a method described later, and the generated motor control current MCTLI is supplied to the stator coil 51 of the stator 50 via the three-phase cable 20.

  The three-phase cable 20 connects the control device 10 and the stator coil 51. The three-phase cable 20 includes a U-phase cable 21, a V-phase cable 22, and a W-phase cable 23. The shaft 30 is inserted into the rotor core 41 of the rotor 40 from the rotation axis direction DR <b> 1 and is connected to the rotor core 41. The rotor core 41 has a structure in which a plurality of electromagnetic steel plates are laminated in the rotation axis direction DR1. The magnet 42 is inserted into the rotor core 41 from the rotation axis direction DR1.

  The stator core 52 of the stator 50 has a structure in which a plurality of electromagnetic steel plates are laminated in the rotation axis direction DR1. The stator coil 51 is wound around the stator core 52. Stator coil 51 includes a U-phase coil, a V-phase coil, and a W-phase coil, and the terminals of these three coils are connected to three-phase cable 20.

  FIG. 2 is a plan view of the stator 50 as viewed from the direction A shown in FIG. Referring to FIG. 2, stator core 52 has a hollow cylindrical shape and has 48 teeth 1 arranged in the circumferential direction on the inner peripheral surface. Coils 510 to 517 constitute a U-phase coil, coils 520 to 527 constitute a V-phase coil, and coils 530 to 537 constitute a W-phase coil. Each of coils 510-517, 520-527, 530-537 has a substantially arc shape. Coils 510 to 517 are arranged on the outermost periphery. The coils 520 to 527 are arranged inside the coils 510 to 517 at positions shifted by a certain distance in the circumferential direction with respect to the coils 510 to 517, respectively. The coils 530 to 537 are arranged inside the coils 520 to 527 at positions shifted from the coils 520 to 527 by a certain distance in the circumferential direction.

  Each of coils 510-517, 520-527, 530-537 is wound in series around each of a plurality of corresponding teeth. For example, coil 510 corresponds to teeth 1-5. The coil 510 is formed by winding a predetermined number of times around the teeth 1 to 5 from the outer periphery.

  The coils 511 to 517, 520 to 527, and 530 to 537 are also wound around the corresponding teeth and formed in the same manner as the coil 510.

  Coils 510 to 513 are connected in series, and one end is terminal U1 and the other end is neutral point UN1. Coils 514 to 517 are connected in series, and one end is terminal U2 and the other end is neutral point UN2.

  Coils 520 to 523 are connected in series, and one end is terminal V1 and the other end is neutral point VN1. Coils 524 to 527 are connected in series, and one end is terminal V2 and the other end is neutral point VN2.

  Coils 530 to 533 are connected in series, and one end is terminal W1 and the other end is neutral point WN1. Coils 534 to 537 are connected in series, and one end is terminal W2 and the other end is neutral point WN2.

  Neutral points UU1, UN2, VN1, VN2, WN1, WN2 are commonly connected to one point, terminals U1, U2 are connected to U-phase cable 21 of three-phase cable 20, and terminals V1, V2 are connected to V-phase. Connected to the cable 22, the terminals W 1 and W 2 are connected to the W-phase cable 23.

  FIG. 3 is a plan view of the rotor 40 and the stator 50 viewed from the direction A shown in FIG. Referring to FIG. 3, rotor 40 is arranged on the inner peripheral side of stator 50. Then, eight magnets 42 are arranged along the circumferential direction DR2. The magnets 42A, 42C, 42E, and 42G are arranged so that the outer peripheral side of the rotor core 41 is an N pole, and the magnets 42B, 42D, 42F, and 42H are arranged so that the outer peripheral side of the rotor core 41 is an S pole. Thus, the eight magnets 42 are magnetized in the radial direction DR3 of the rotor 40, and are arranged in the circumferential direction DR2 so that the polarity of the magnets is reversed between adjacent magnets. And the coils 510-517, 520-527, 531-537 shown in FIG. 2 are arrange | positioned facing the eight magnets 42 (42A-42H).

  The stator core 52 includes 48 teeth 1, which are determined to be 6 times (integer multiple) the number of magnets 42 (42 </ b> A to 42 </ b> H) included in the rotor 40.

  4 is a perspective view of the rotor 40 shown in FIG. Referring to FIG. 4, the rotor core 41 of the rotor 40 has a substantially cylindrical shape and has a cylindrical surface 41A. The magnet 42 is embedded in the rotor core 41 from the rotation axis direction DR1. Accordingly, the rotor 40 is made of IPM (Interior Permanent Magnet).

  FIG. 5 is a relationship diagram between the excitation force gain and the rotation order component. In FIG. 5, the vertical axis represents the excitation force gain, and the horizontal axis represents the rotational order component of the excitation force. The excitation force is a force that attempts to vibrate the tooth 1 applied to the tooth 1 by supplying an alternating current to the stator coil 51 of the stator 50.

  Referring to FIG. 5, in electric motor 100, rotor 40 includes eight magnets 42, so an exciting force having a rotational order that is an integral multiple of eight is generated. That is, an excitation force having rotation orders of the 8th order, 16th order, 24th order, 32nd order, 40th order, 48th order and 56th order is generated. Among these, the excitation force gain having the largest excitation force having the eighth order of rotation has the largest excitation force gain, and the excitation force gain decreases as the rotation order increases.

  FIG. 6 is a diagram illustrating the relationship between the teeth 1, 2, 3, 4, 5,... Of the stator core 52 and the excitation force. In FIG. 6, the teeth are represented by a development view. Referring to FIG. 6, the excitation force having the 48th rotation order changes with time as excitation forces KP1, KP2, and KP3. Further, the exciting force having the eighth order of rotation changes with time as the exciting forces KP4, KP5, KP6.

  In this case, each of the excitation forces KP1, KP2, KP3 has a component applied to each of the teeth 1, 2, 3, 4, 5,. And the exciting force applied to each of the teeth 1, 2, 3, 4, 5,... Is in the same direction. The excitation force KP1 applies a positive excitation force to the teeth 1, 2, 3, 4, 5,..., And the excitation force KP3 is the teeth 1, 2, 3, 4, 5,. Apply negative excitation force to. The excitation force KP2 is a transition process from the excitation force KP1 to the excitation force KP3, and the teeth 1, 2, 3, 4, 5,. Apply force mixed with vibration. The mixed force is applied to each tooth in the same direction and the same magnitude.

  On the other hand, each of the excitation forces KP4, KP5, and KP6 has a component that is applied in the reverse direction for every three teeth. For example, the excitation force KP4 includes a component CP1 that applies a negative force to the teeth 3, 4, and 5, and a component CP2 that applies a positive force to the three teeth adjacent to the teeth 3, 4, and 5.

  FIG. 7 is a conceptual diagram of an excitation force having an eighth order of rotation applied to the stator core 52. FIG. 8 is a conceptual diagram of an excitation force having a 48th order of rotation applied to the stator core 52. Referring to FIG. 7, the excitation force KP_8 having the eighth order of rotation has a component applied in the reverse direction for every three teeth as described above, and therefore periodically changes in the circumferential direction DR2 of the stator core 52. To do. And the excitation force KP_8 has components SS1 to SS16. As a result, the stator core 52 is pulled in the outer circumferential direction by the components SS1, SS3, SS5, SS7, SS9, SS11, SS13, SS15, and the inner circumferential direction by the components SS2, SS4, SS6, SS8, SS10, SS12, SS14, SS16. To be drawn to. Components SS1, SS3, SS5, and SS7 cancel each other with components SS9, SS11, SS13, and SS15, and components SS2, SS4, SS6, and SS8 cancel each other with components SS10, SS12, SS14, and SS16, respectively.

  Therefore, the stator core 52 is not vibrated by the excitation force KP_8 having the eighth order of rotation.

  Referring to FIG. 8, the excitation force KP_48 having the 48th rotation order is applied to each of the teeth 1, 2, 3, 4, 5,... In the same direction as described above. Therefore, the stator core 52 is vibrated in the radial direction DR3.

  Therefore, among the exciting forces having the 8th order, 16th order, 24th order, 32nd order, 40th order, 48th order, and 56th order shown in FIG. 5, the exciting force for vibrating the stator core 52 is the 48th order. Excitation force KP_48 having a rotation order of.

  Therefore, control device 10 generates motor control current MCTLI so as to suppress vibration of stator core 52 due to excitation force KP_48 having the 48th order of rotation.

  FIG. 9 is a waveform diagram of an alternating current. Referring to FIG. 9, stator coil 51 is supplied with an alternating current AC for generating a rotating magnetic field. In this case, the alternating current AC_U is supplied to the U-phase coil (coils 510 to 517 shown in FIG. 2), the alternating current AC_V is supplied to the V-phase coil (coils 520 to 527 shown in FIG. 2), and the alternating current AC_W. Is supplied to a W-phase coil (coils 530 to 537 shown in FIG. 2). The alternating currents AC_U, AC_V, and AC_W are shifted from each other by a phase of 120 degrees.

  The high-frequency AC current AC_H is an AC current for generating a force that cancels the excitation force KP_48 having the 48th rotation order. The alternating current AC_H includes alternating currents AC_HU, AC_HV, and AC_HW. The alternating currents AC_HU, AC_HV, and AC_HW are shifted from each other by a phase of 120 degrees. The alternating current AC_HU has a component for one cycle in the half cycle T / 2 of the alternating current AC_U. Therefore, the frequency of the alternating current AC_H is twice the frequency of the alternating current AC. That is, since the alternating current AC has a rotation fourth-order frequency, the alternating current AC_H has a rotation eighth-order frequency.

  The alternating currents AC_HU, AC_HV, and AC_HW are superimposed on the alternating currents AC_U, AC_V, and AC_W, respectively. As a result, a motor control current MCTLI composed of motor control currents MCTLI_U, MCTLI_V, and MCTLI_W is generated.

  FIG. 10 is a conceptual diagram for explaining that the 48th-order excitation force KP_48 is canceled by the high-frequency AC current AC_H. 10, 48th-order excitation force KP_48 is applied to teeth 1, 2, 3, 4, 5,... In the same direction. When the alternating current AC_H is superimposed on the alternating current AC, an electromagnetic force EMF_F is generated. The electromagnetic force EMF_F is an electromagnetic force on the rotor core 41 (made of an electromagnetic steel plate) of the rotor 40 that is generated when the alternating current AC_H flows through the stator coil 51. The electromagnetic force EMF_F includes a U-phase electromagnetic force EMF_FU, a V-phase electromagnetic force EMF_FV, and a W-phase electromagnetic force EMF_FW. The U-phase electromagnetic force EMF_FU, the V-phase electromagnetic force EMF_FV, and the W-phase electromagnetic force EMF_FW are generated when the AC currents AC_HU, AC_HV, and AC_HW flow, respectively.

  The electromagnetic force applied to the electromagnetic steel sheet constituting the rotor core 41 becomes an attractive force on both the positive side and the negative side of the AC current AC_H (consisting of three AC currents AC_HU, AC_HV, and AC_HW) flowing through the stator coil 51. Each of the electromagnetic force EMF_FU, the V-phase electromagnetic force EMF_FV, and the W-phase electromagnetic force EMF_FW changes periodically so that the same force is applied every three teeth. The V-phase electromagnetic force EMF_FV is out of phase with the U-phase electromagnetic force EMF_FU by two teeth, and the W-phase electromagnetic force EMF_FW is out of phase with the V-phase electromagnetic force EMF_FV by two teeth. The U-phase electromagnetic force EMF_FU is out of phase with the W-phase electromagnetic force EMF_FW by two teeth.

  As a result, the electromagnetic force EMF_FT obtained by adding the U-phase electromagnetic force EMF_FU, the V-phase electromagnetic force EMF_FV, and the W-phase electromagnetic force EMF_FW is one of the teeth 1, 2, 3, 4, 5,. Are applied from the same direction. The electromagnetic force EMF_FT is a force in the opposite direction to the excitation force KP_48 having the 48th order of rotation, and cancels the excitation force KP_48.

  That is, since the electromagnetic force consisting of the attractive force (electromagnetic force EMF_FU, EMF_FV, EMF_FW, respectively) is generated on the plus side and the minus side of each of the AC currents AC_HU, AC_HV, AC_HW, the AC current consists of three AC currents AC_HU, AC_HV, AC_HW. The alternating current AC_H generates an electromagnetic force EMF_FT having a frequency of 8 × 2 × 3 = 48th order obtained by multiplying the rotation 8th order frequency, which is the frequency of the alternating current AC_H, by 2 and 3.

  This “2” is a frequency determining factor of the electromagnetic force EMF_FT caused by the generation of the electromagnetic force on the positive side and the negative side of the AC current AC_H, and “3” is the three-phase AC current AC_HU, AC_HV. , AC_HW is a frequency determining factor of the electromagnetic force EMF_FT caused by the generation of the electromagnetic force.

  FIG. 11 is a conceptual diagram for explaining the influence of the electromagnetic force generated by the high-frequency alternating current AC_H on the magnet 42 of the rotor 40. Referring to FIG. 11, when alternating current AC_H is superimposed on alternating current AC, electromagnetic force EMF_M is generated. The electromagnetic force EMF_M is an electromagnetic force with respect to the magnet 42 of the rotor 40 that is generated when the alternating current AC_H flows through the stator coil 51. The electromagnetic force EMF_M includes a U-phase electromagnetic force EMF_MU, a V-phase electromagnetic force EMF_MV, and a W-phase electromagnetic force EMF_MW. The U-phase electromagnetic force EMF_MU, the V-phase electromagnetic force EMF_MV, and the W-phase electromagnetic force EMF_MW are generated when the AC currents AC_HU, AC_HV, and AC_HW flow, respectively.

  Each of the U-phase electromagnetic force EMF_MU, the V-phase electromagnetic force EMF_MV, and the W-phase electromagnetic force EMF_MW has a maximum point on the S pole side and a maximum point on the N pole side. The electromagnetic force EMF_MU, the V-phase electromagnetic force EMF_MV, and the W-phase electromagnetic force EMF_MW are shifted from each other by two teeth, so the U-phase electromagnetic force EMF_MU, the V-phase electromagnetic force EMF_MV, and the W-phase electromagnetic force The electromagnetic force EMF_MT obtained by adding the force EMF_MW becomes zero. That is, no force is exerted on the magnet 42 of the rotor 40 by flowing a high-frequency AC current AC_H.

  Therefore, by superimposing the high-frequency AC current AC_H on the AC current AC, only the electromagnetic force EMF_FT that cancels the excitation force KP_48 having the 48th rotation order is generated between the rotor core 41 and the rotor core 41. As a result, the vibration of the stator core 52 can be suppressed.

  As described above, in the present invention, the electromagnetic force EMF_FT in the opposite direction to the excitation force KP_48 having the 48th order of rotation is generated between the rotor core 41 by superimposing the high-frequency alternating current AC_H on the alternating current AC. Then, the generated electromagnetic force EMF_FT cancels the excitation force KP_48 having the 48th rotation order.

  FIG. 12 is a circuit diagram and a functional block diagram of the control device 10 shown in FIG. Referring to FIG. 12, control device 10 includes a battery B, a capacitor C1, an inverter 11, a voltage sensor 12, a current sensor 13, a motor control phase voltage calculation unit 14, and an inverter PWM signal conversion unit. 15 and the like.

  Capacitor C1 is connected between positive bus LN1 and negative bus LN2 of battery B. Inverter 11 includes a U-phase arm 31, a V-phase arm 32, and a W-phase arm 33. U-phase arm 31, V-phase arm 32, and W-phase arm 33 are provided in parallel between positive bus LN1 and negative bus LN2.

  The U-phase arm 31 includes NPN transistors Q1 and Q2 connected in series, the V-phase arm 32 includes NPN transistors Q3 and Q4 connected in series, and the W-phase arm 33 includes NPN transistors Q5 and Q5 connected in series. Consists of Q6. In addition, diodes D1 to D6 that flow current from the emitter side to the collector side are connected between the collectors and emitters of the NPN transistors Q1 to Q6, respectively.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of stator coil 51 via three-phase cable 20. That is, the other end of the U-phase coil is at the midpoint of the NPN transistors Q1 and Q2 via the U-phase cable 21, and the other end of the V-phase coil is at the midpoint of the NPN transistors Q3 and Q4 via the V-phase cable 22. The other end of the W-phase coil is connected to an intermediate point between NPN transistors Q5 and Q6 via a W-phase cable 23, respectively.

  The battery B is composed of a secondary battery such as nickel metal hydride or lithium ion. Capacitor C1 smoothes the DC voltage from battery B and supplies the smoothed DC voltage to inverter 11.

  The inverter 11 converts the DC voltage supplied from the capacitor C1 into an AC voltage based on the signal PWM from the inverter PWM signal conversion unit 15 and converts the DC voltage supplied from the capacitor C1 into a U-phase coil, a V-phase coil, and a W-phase coil. Control currents MCTLI_U, MCTLI_V, and MCTLI_W are supplied.

  The voltage sensor 12 detects the voltage Vm across the capacitor C1 and outputs the detected voltage Vm to the motor control phase voltage calculator 14. Current sensor 13 is installed in U-phase cable 21, V-phase cable 22, and W-phase cable 33, detects motor current MCRT flowing through stator coil 51, and uses the detected motor current MCRT as motor control phase voltage calculation unit 14. Output to.

  Motor control phase voltage calculator 14 receives torque command value TR from the external ECU, voltage Vm from voltage sensor 12, and motor current MCRT from current sensor 13. Then, the motor control phase voltage calculation unit 14 calculates a voltage to be applied to each phase coil of the stator coil 51 based on these input signals, and the calculated result is the inverter PWM signal conversion unit 15. To supply.

  The inverter PWM signal conversion unit 15 converts the motor control current MCTLI shown in FIG. 9 into the U-phase coil, the V-phase coil, and the W-phase of the stator coil 51 based on the calculation result supplied from the motor control phase voltage calculation unit 14. A signal PWM for flowing through the coil is generated, and the generated signal PWM is output to the inverter 11.

  FIG. 13 is a diagram for explaining the generation of the signal PWM. Referring to FIG. 13, when an alternating current AC_U for generating a rotating magnetic field is passed through the U-phase coil of stator coil 51 by the pulse width modulation method, signal PWM0 is generated.

  Then, a signal PWMU for causing the motor control current MCTLI_U, in which the high-frequency AC current AC_HU is superimposed on the AC current AC_U, to flow through the U-phase coil of the stator coil 51 by the pulse width modulation method is generated based on the signal PWM0.

  That is, in the period T1, the signal PWM0 causes the current component AC_U1 of the alternating current AC_U to flow through the components PWM0_1 and PWM0_2. In this period T1, the motor control current MCTLI_U has a current component MCTLI_U1. This current component MCTLI_U1 is smaller than the current component AC_U1.

  Therefore, in order to realize the current component MCTLI_U1, the on-duties D1 and D2 of the component PWM0_1 may be reduced.

  Therefore, a component PWM1_1 having an on-duty D3 smaller than the on-duty D1 and a component PWM1_2 having an on-duty D4 smaller than the on-duty D2 are generated. Similarly, in other periods, each component is generated based on the component of the signal PWM0 to generate the signal PWMU1. Then, the signal PWMU1 is inverted to generate the signal PWMU2. This signal PWMU1 is a signal for turning on / off the upper arm (NPN transistors Q1, Q3, Q5) of the inverter 11 in order to flow the motor control current MCTLI_U to the U-phase coil of the stator coil 51, and the signal PWMU2 is a motor control signal. This is a signal for turning on / off the lower arm (NPN transistors Q2, Q4, Q6) of the inverter 11 in order to allow the current MCTLI_U to flow through the U-phase coil of the stator coil 51.

  Thereby, a signal PWMU composed of the signals PWMU1 and PWMU2 is generated.

  Signals PWMV and PWMW for flowing motor control currents MCTLI_V and MCTLI_W to the V-phase coil and W-phase coil of stator coil 51 are also generated by the same method as described above.

  Referring to FIG. 12 again, inverter PWM signal conversion unit 15 generates signal PWM0 based on the calculation result from motor control phase voltage calculation unit 14, and generates high-frequency signal based on the generated signal PWM0. The signals PWMU, PWMV, and PWMW for superimposing the alternating current AC_H on the alternating current AC are generated. Then, the inverter PWM signal conversion unit 15 outputs a signal PWM including the signals PWMU, PWMV, and PWMW to the inverter 11.

  As a result, the NPN transistors Q1 to Q6 of the inverter 11 are subjected to switching control, and the inverter 11 passes motor control currents MCTLI_U, MCTLI_V, and MCTLI_W to the U-phase coil, V-phase coil, and W-phase coil of the stator coil 51, respectively.

  As a result, the excitation force KP_48 having a 48th-order rotational order applied to the stator core 52 is offset by the electromagnetic force EMF_FT generated by the high-frequency AC current AC_H, and the vibration of the stator core 52 is suppressed.

  FIG. 14 is another perspective view of the rotor. The electric motor 100 according to the present invention may include a rotor 40A shown in FIG. 14 instead of the rotor 40 shown in FIG. Referring to FIG. 14, rotor 40 </ b> A includes a rotor core 60 and a magnet 61.

  The rotor core 60 is produced by laminating a plurality of electromagnetic steel plates in the rotation axis direction DR1. The rotor core 60 has a substantially cylindrical shape and is fixed to the shaft 30. The eight magnets 61 are arranged on the cylindrical surface 60A of the rotor core 60 at a predetermined interval along the circumferential direction DR2. Each magnet 61 is magnetized in the radial direction DR3.

  As described above, the rotor 40A is made by arranging eight magnets on the cylindrical surface 60A of the rotor core 60, and thus is made of SPM (Surface Permanent Magnet).

  Even when the rotor 40A is used, the vibration of the stator core 52 can be suppressed by superimposing the high-frequency alternating current AC_H on the alternating current AC.

  FIG. 15 is still another perspective view of the rotor. The electric motor 100 according to the present invention may include a rotor 40B shown in FIG. 15 instead of the rotor 40 shown in FIG. Referring to FIG. 15, rotor 40 </ b> B includes a rotor core 70. The rotor core 70 has voids 71 to 74 therein.

  The gaps 71 and 72 are provided between the gap 73 and the gap 74 on the inner peripheral side of the cylindrical surface 70A of the rotor core 70 along the rotation axis direction DR1. The gaps 71 and 72 have a substantially U shape with respect to the cylindrical surface 70A (the outer peripheral surface of the rotor core 70), and are disposed near the cylindrical surface 70A.

  The gaps 73 and 74 are provided substantially parallel to the cylindrical end faces 70B and 70C from the cylindrical surface 70A toward the inner peripheral side, and are connected to the gaps 71 and 72 provided in the rotation axis direction DR1. The gap 73 is formed at a position away from the cylindrical end face 70B in the direction of the cylinder end face 70C by a predetermined distance, and the gap 74 is formed at a position away from the cylinder end face 70C in the direction of the cylinder end face 70B by a predetermined distance. Is done. As a result, the gaps 71 and 72 are provided between the gap 73 and the gap 74 in the rotation axis direction DR1, and do not reach the cylindrical end faces 70B and 70C. That is, a region where the air gaps 71 to 74 are not formed exists below the cylindrical end surface 70B, and a region where the air gaps 71 to 74 are not formed exists above the cylindrical end surface 70C.

  The air gaps 71 and 72 are provided in order to realize salient pole characteristics in the radial direction DR3. That is, the inductance when the magnetic flux crosses the gaps 71 and 72 in the radial direction DR3 is Lq (= inductance in the q-axis direction), and the area where the gaps 71 and 72 are not formed in the circumferential direction DR2 (that is, a substantially U-shape). In order to realize a magnetic characteristic such that Ld> Lq, where Ld (= inductance in the d-axis direction) is an inductance when a magnetic flux passes through the gaps 71 and 72 having a shape (between the gaps 71 and 72). 71, 72 are provided.

  The air gaps 71 and 72 prevent the magnetic flux in the radial direction DR3 from being short-circuited, and the region where the air gaps 71 and 72 are not provided allows the magnetic flux to pass in the radial direction DR3, so that magnetic characteristics satisfying Ld> Lq are obtained. It is done.

  Further, the gaps 73 and 74 are provided to prevent the magnetic flux in the radial direction DR3 from leaking.

  As described above, in the rotor 40B, magnetic salient pole characteristics are obtained in the radial direction DR3. Therefore, the plurality of gaps 71 to 74 arranged at predetermined intervals in the circumferential direction DR2 are magnetized in the radial direction DR3. Performs the same function as a magnet. A magnetic pole portion that realizes salient pole characteristics without using a magnet is referred to as “SynR (Synchronous Reluctance)”.

  Therefore, the rotor 40B is made of SynR.

  In the rotor 40B, the rotor core 70 is formed by laminating a plurality of electromagnetic steel plates in the rotation axis direction DR1. Since the rotor core 70 does not include a magnet and is made only of an electromagnetic steel plate, an electromagnetic force for canceling the excitation force KP_48 having a 48th-order rotational order by superimposing the high-frequency AC current AC_H on the AC current AC. A force EMF_FT is generated.

  Therefore, even when the rotor 40B is used, the vibration of the stator core 52 can be suppressed by superimposing the high-frequency alternating current AC_H on the alternating current AC.

  In the above, in the electric motor 100 including the rotor 40 having eight rotor magnetic pole portions (magnets 42) and the stator core 52 having 48 teeth, the rotation current 8 (= (48/3) / 2) It has been described that the vibration of the stator core 52 is suppressed by superimposing the high-frequency AC current AC_H having the following frequency. However, the present invention is not limited to this, and n (n is A rotor having a natural number) magnetic pole portions, a stator core having m teeth that are integer multiples of n, and s (s is a natural number) phase are provided corresponding to the phase and wound around m teeth. In the electric motor including the s stator coils thus formed, the alternating current AC for generating the rotating magnetic field is converted into a high-frequency alternating current A having a frequency of rotation k (= (m / s) / 2). By superimposing _H, as long as to suppress the vibration of the stator core.

  In the above description, the motor control current MCTLI is generated by the pulse width modulation method. However, the present invention is not limited to this, and the motor control current MCTLI may be generated by a method other than the pulse width modulation method. . For example, an inverter that generates AC current AC and an inverter that generates high-frequency AC current AC_H are provided, and motor control current MCTLI is generated by synthesizing AC current AC and high-frequency AC current AC_H generated by each inverter. You may make it do.

  Furthermore, in the above description, an electric motor including a three-phase coil has been described. However, the present invention is not limited to this, and the electric motor may generally include a plurality of coils corresponding to a plurality of phases.

  Furthermore, the electric motor according to the present invention generates an electromagnetic force generated by an alternating current AC for generating a rotating magnetic field and applied in the opposite direction to the excitation force applied to the stator 50. What is necessary is just to reduce the vibration of the stator core by superimposing the high-frequency current to be generated with the electromagnetic steel sheet on the alternating current AC. That is, the electric motor according to the present invention is not limited to superimposing the high-frequency current for canceling the excitation force generated by the alternating current AC for generating the rotating magnetic field on the alternating current AC, but for generating the rotating magnetic field. What is necessary is just to superimpose on the alternating current AC the high frequency current for reducing the excitation force generated by the alternating current AC. Thereby, the vibration of the stator can be reduced.

  The magnet 42 or the magnet 61 constitutes a “rotor magnetic pole part”.

  The gaps 71 to 74 also constitute “rotor magnetic pole portions”.

  Further, the inverter 11, the motor control phase voltage calculation unit 14, and the inverter PWM signal conversion unit 15 generate a motor control current in which a high-frequency current is superimposed on an AC current for generating a rotating magnetic field, and the s coils A “control unit” is provided that controls the rotor to rotate with respect to the stator. In this case, the high-frequency current is an alternating current that is generated by an alternating current and generates an electromagnetic force in the opposite direction to the excitation force applied to the stator with the ferromagnetic member of the rotor.

  Furthermore, the inverter 11, the motor control phase voltage calculation unit 14, and the inverter PWM signal conversion unit 15 set the rotation k (= (m / s) / 2) order frequency to the alternating current AC for generating the rotating magnetic field. A motor control current MCTLI on which the high-frequency current AC_H is superposed is supplied to each of the s coils to constitute a “control unit” that controls the rotor to rotate relative to the stator.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to an electric motor capable of reducing stator vibration. The present invention is also applied to an electric motor capable of suppressing stator vibration.

It is sectional drawing of the electric motor by embodiment of this invention. It is a top view of the stator seen from the A direction shown in FIG. It is a top view of the rotor and stator seen from the A direction shown in FIG. It is a perspective view of the rotor shown in FIG. FIG. 6 is a relationship diagram between an excitation force gain and a rotation order component. It is a figure which shows the relationship between the teeth of a stator core, and an excitation force. It is a conceptual diagram of the exciting force which has the 8th rotation order added to a stator core. It is a conceptual diagram of the exciting force which has the 48th rotation order added to a stator core. It is a waveform diagram of an alternating current. It is a conceptual diagram for demonstrating cancellation of the 48th-order excitation force KP_48 with the high frequency alternating current AC_H. It is a conceptual diagram for demonstrating the influence with respect to the magnet of the rotor of the electromagnetic force which generate | occur | produces with the high frequency alternating current AC_H. FIG. 2 is a circuit diagram and a functional block diagram of the control device shown in FIG. 1. It is a figure for demonstrating the production | generation of signal PWM. It is another perspective view of a rotor. It is another perspective view of a rotor.

Explanation of symbols

  1 to 5 teeth, 10 control device, 11 inverter, 12 voltage sensor, 13 current sensor, 14 motor control phase voltage calculation unit, 15 inverter PWM signal conversion unit, 20 three-phase cable, 21 U phase cable, 22 V phase Cable, 23 W phase cable, 30 shaft, 31 U phase arm, 32 V phase arm, 33 W phase arm, 40, 40A, 40B rotor, 41, 60, 70 rotor core, 41A, 60A cylindrical surface, 42, 42A to 42H , 61 Magnet, 50 Stator, 51 Stator coil, 52 Stator core, 71-74 Air gap, 100 Electric motor, 510-517, 520-527, 530-537 Coil, U1, U2, V1, V2, W1, W2 terminal, UN1, UN2, VN1, VN2, WN1, WN2 Neutral point, B battery , C1 capacitor, LN1 positive bus, LN2 negative bus, Q1 to Q6 NPN transistor, D1 to D6 diode.

Claims (9)

A rotor including a ferromagnetic member and having n (n is a natural number) rotor magnetic pole portions;
A stator having m teeth which is an integer multiple of n and s coils provided corresponding to s (s is a plurality) phases and wound around the m teeth;
A control unit that generates a motor control current in which a high-frequency current is superimposed on an alternating current for generating a rotating magnetic field, supplies the motor control current to each of the s coils, and controls the rotor to rotate relative to the stator; With
The high-frequency current is generated by the alternating current and is an alternating current for generating an electromagnetic force in a direction opposite to the excitation force applied to the stator with the ferromagnetic member of the rotor. .   The electric motor according to claim 1, wherein the high-frequency current is an alternating current having a rotation k-th order frequency determined by k = (m / s) / 2.   The electric motor according to claim 1, wherein the control unit supplies the motor control current to each of the s coils by a pulse width modulation method. The rotor includes a rotor core having a cylindrical surface surrounding a rotation axis;
4. The electric motor according to claim 1, wherein the m teeth and the s coils are arranged to face the cylindrical surface of the rotor core. 5.   5. The electric motor according to claim 4, wherein each of the n rotor magnetic pole portions includes the ferromagnetic member constituting the rotor core and a magnet.   The electric motor according to claim 5, wherein the magnet is embedded in the ferromagnetic member from a rotation axis direction of the rotor and is magnetized in a radial direction of the rotor.   The electric motor according to claim 5, wherein the magnet is disposed on the cylindrical surface and is magnetized in a radial direction of the rotor.   5. The electric motor according to claim 4, wherein each of the n rotor magnetic pole portions includes only the ferromagnetic member constituting the rotor core.   9. The electric motor according to claim 8, wherein each of the n rotor magnetic pole portions is made of a ferromagnetic material having a magnetic salient pole characteristic in a radial direction of the rotor.

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