JP2007325471A - Control device of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a motor which can perform control coping with changes of the efficiency and the operation state of the motor without depending on the number of revolutions of the motor. <P>SOLUTION: In the control device of the motor which performs magnetic field control by changing a rotor phase difference which is a phase difference between double rotors 11, 12 of the motor 1, the control device comprises: a current command calculation part 50 which performs the energization control of the motor so that the output torque of the motor 1 reaches a torque command Tr_c according to the torque command Tr_c, a detected value Ke_s of an induction voltage constant of the motor 1, and the number of revolutions Nm; and a Ke-command calculation part 90 and a phase difference control part 80 which change rotor phase difference so that the induction voltage constant Ke of the motor 1 becomes small in a range where the efficiency of the motor 1 becomes higher than prescribed reference efficiency when performing the energization control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor control device that performs field control of a permanent magnet field type rotary motor by changing a phase difference between two rotors arranged concentrically.

  Conventionally, a first rotor and a second rotor are provided concentrically around a rotation shaft of a permanent magnet field type rotary electric motor, and the phase difference between the first rotor and the second rotor is changed according to the rotational speed. Thus, an electric motor that performs field weakening control is known (see, for example, Patent Document 1).

  In such a conventional electric motor, the first rotor and the second rotor are connected via a member that is displaced along the radial direction by the action of centrifugal force. In addition, when the electric motor is in a stopped state, the magnetic poles of the permanent magnets arranged in the first rotor and the permanent magnetic poles arranged in the second rotor are in the same direction, and the field magnetic flux is maximized. As the rotational speed increases, the phase difference between the first rotor and the second rotor increases due to centrifugal force, and the magnetic flux of the field decreases.

  Here, in FIG. 12, the vertical axis represents the output torque Tr and the horizontal axis represents the rotational speed N, and shows the region where the field weakening of the motor is required. In the figure, u represents the orthogonal line of the motor (field weakening). When the motor is operated without control, the phase voltage of the motor becomes equal to the power supply voltage by the combination of the rotation speed and the output torque). In the figure, X is a region that does not require field weakening, and Y is a region that requires field weakening.

As shown in FIG. 12, the region Y in which field weakening is required is determined by the rotational speed N of the motor and the output torque Tr. Therefore, in the field weakening control based only on the conventional rotational speed, the field weakening control is performed. There is a disadvantage that the amount is too large or too small. Further, there is an inconvenience that more flexible control corresponding to changes in the efficiency and operating state of the motor cannot be performed regardless of the rotation speed of the motor.
JP 2002-204541 A

  The present invention has been made in view of the above background, and an object of the present invention is to provide an electric motor control device capable of performing control corresponding to changes in the efficiency and operating state of the electric motor without depending on the rotational speed of the electric motor. And

  The present invention has been made to achieve the above object, and is a permanent magnet field type in which a first rotor and a second rotor each having a plurality of field magnets are arranged concentrically around a rotating shaft. The present invention relates to an electric motor control device that controls the operation of a rotary electric motor by performing field control for changing an induced voltage constant of the electric motor by changing a rotor phase difference that is a phase difference between the first rotor and the second rotor.

  In accordance with a predetermined target torque and an induced voltage constant of the motor, energization is performed to perform energization control for controlling an energization amount to the armature of the motor so that the output torque of the motor becomes the target torque. Control means, efficiency estimating means for estimating the efficiency of the electric motor when executing the energization control, and efficiency of the electric motor estimated by the efficiency estimating means when executing the energization control is a first limit. Rotor phase difference control means for performing induced voltage reduction control for changing the rotor phase difference so that the induced voltage constant of the electric motor is reduced within a range higher than the efficiency.

  According to the present invention, when the energization control is executed by the energization control unit, the rotor phase difference control unit is configured so that the efficiency of the electric motor is higher than the first reference efficiency. The rotor phase difference is changed so that the induced voltage constant of the electric motor becomes small. Thus, by reducing the induced voltage constant of the electric motor, it is possible to reduce the induced voltage generated in the armature that increases as the rotational speed of the electric motor increases. Therefore, when the rotational speed of the motor increases rapidly due to a change in the operating state of the motor or a failure of the drive circuit of the motor, an increase in induced voltage generated in the armature of the motor is suppressed, and the armature of the motor It is possible to prevent the inter-terminal voltage from exceeding the power supply voltage to disable control of the electric motor and damage to the drive circuit. As a result, it is possible to perform control that can respond to changes in the operating state of the motor while maintaining the efficiency of the motor at or above the first limit efficiency.

  In addition, a rotation speed detection means for detecting the rotation speed of the electric motor is provided, and the efficiency estimation means is based on the target torque, the rotation speed of the electric motor, and a power supply voltage of a drive circuit of the electric motor. It is characterized by estimating the efficiency of the electric motor when executing the control.

  In the present invention, the output torque of the electric motor is proportional to the energization amount to the electric motor and the induced voltage constant of the electric motor. Therefore, the greater the induced voltage constant of the motor, the higher the efficiency of the motor. Further, the induced voltage generated in the armature of the motor increases as the rotational speed of the motor increases. In this case, it is necessary to increase the voltage supplied to the electric motor in order to ensure the energization amount of the electric motor, but this reduces the efficiency of the electric motor. Thus, since the efficiency of the electric motor depends on the output torque, the induced voltage constant, and the rotational speed of the electric motor, the efficiency estimation means includes the rotational speed of the electric motor, the induced voltage constant of the electric motor, and the target torque. Therefore, the efficiency of the electric motor when executing the energization control can be estimated.

  The rotor phase difference control means includes a temperature detection means for detecting the temperature of the electric motor, and the rotor phase difference control means has an induced voltage reduction control and an efficiency of the induction motor that is higher than the first limit efficiency according to the temperature of the electric motor. The efficiency improvement control for changing the rotor phase difference is switched so as to be higher than the high second limiting efficiency.

  According to the present invention, the lower the temperature of the motor, the greater the margin until the temperature of the motor exceeds the operation compensation temperature range of the motor due to heat generation. Therefore, in this case, the control of the electric motor is controlled when the rotation speed of the electric motor increases rapidly by allowing an increase in heat generation due to a reduction in efficiency to some extent and reducing the induced voltage constant of the electric motor by the induced voltage reduction control. Can be prevented from becoming impossible.

  On the other hand, when the temperature of the electric motor increases, the margin until the temperature of the electric motor exceeds the guaranteed operating temperature range of the electric motor due to heat generation decreases. Therefore, in this case, the efficiency improvement control causes the efficiency of the motor to be equal to or higher than the second limit efficiency higher than the first limit efficiency, thereby reducing the heat generation of the motor and increasing the temperature. A decrease in performance of the electric motor can be suppressed.

  In addition, a rotor phase difference detection unit that detects the rotor phase difference is provided, and the energization control unit changes the target value of the rotor phase difference and the rotor when the rotor phase difference is changed by the rotor phase difference control unit. The amount of field weakening current applied to reduce the voltage across the terminals of the electric motor is controlled so that the difference from the detected value of the rotor phase difference by the phase difference detecting means decreases. .

  According to the present invention, it is possible to reduce the excess or deficiency of the field weakening of the armature, which may be caused by a response delay when changing the rotor phase difference.

  Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a DC brushless motor having a double rotor, FIG. 2 is a configuration diagram and an operation explanatory diagram of a mechanism for changing a phase difference between an outer rotor and an inner rotor of the DC brushless motor shown in FIG. And FIG. 4 is an explanatory diagram of the effect of changing the phase difference between the outer rotor and the inner rotor, FIG. 5 is a control block diagram of the motor control device, and FIG. 6 is a current vector selection range corresponding to current and voltage restrictions. FIG. 7 is an explanatory diagram of a change in the output range of the motor due to a difference in the induced voltage constant, FIG. 8 is an explanatory diagram regarding a process for calculating an induced voltage constant that minimizes the loss of the motor, and FIG. 9 is an efficiency of the motor And FIG. 10 is an explanatory diagram of a map for determining the induced voltage constant and a map for determining the phase difference of the double rotor. 1 is a flowchart of a process for controlling the phase difference between the double rotor the efficiency conditions corresponding to the temperature of the motor.

  Referring to FIG. 1, an electric motor 1 according to the present embodiment includes an inner rotor 11 (corresponding to a second rotor of the present invention) in which the fields of permanent magnets 11a and 11b are arranged at equal intervals along the circumferential direction. To the outer rotor 12 (corresponding to the first rotor of the present invention) in which the fields of the permanent magnets 12a and 12b are arranged at equal intervals along the circumferential direction, and to the inner rotor 11 and the outer rotor 12. A DC brushless motor including a stator 10 having an armature 10a for generating a rotating magnetic field. The electric motor 1 is used, for example, as a drive source for a hybrid vehicle or an electric vehicle, and operates as an electric motor and a generator when mounted on the hybrid vehicle.

  The inner rotor 11 and the outer rotor 12 are both arranged concentrically so that the rotating shaft is coaxial with the rotating shaft 2 of the electric motor 1. In the inner rotor 11, permanent magnets 11 a having the N pole as the rotating shaft 2 side and permanent magnets 11 b having the S pole as the rotating shaft 2 side are alternately arranged. Similarly, in the outer rotor 12, permanent magnets 12 a having the N pole as the rotating shaft 2 side and permanent magnets 12 b having the S pole as the rotating shaft 2 side are alternately arranged.

  Next, the electric motor 1 includes the planetary gear mechanism 30 shown in FIG. 2A in order to change the rotor phase difference that is the phase difference between the outer rotor 12 and the inner rotor 11. Referring to FIG. 2A, the planetary gear mechanism 30 is a single pinion type planetary gear mechanism disposed in the hollow portion on the inner peripheral side of the inner rotor 11, and is formed coaxially and integrally with the outer rotor 12. The first ring gear R1, the second ring gear R2 coaxially and integrally formed with the inner rotor 11, the first planetary gear 31 meshing with the first ring gear R1, and the second planetary gear meshing with the second ring gear R2. 32, the first planetary gear 31 and the first planetary gear 31 that are engaged with the second planetary gear 32, the sun gear S that is an idle gear, and the first planetary gear 31 that rotatably supports the first planetary gear 31 and is rotatably supported by the rotary shaft 2. C1 and the second planetary gear 32 are rotatably supported, and a second planetary carrier C2 fixed to the stator 10 is provided.

  In the planetary gear mechanism 30, the first ring gear R1 and the second ring gear R2 have substantially the same gear shape, and the first planetary gear 31 and the second planetary gear 32 have the substantially same gear shape. The rotating shaft 33 of the sun gear S is disposed coaxially with the rotating shaft 2 of the electric motor 1 and is rotatably supported by a bearing 34. As a result, the first planetary gear 31 and the second planetary gear 32 mesh with the sun gear S, and the outer rotor 12 and the inner rotor 11 rotate in synchronization.

  Further, the rotation shaft 35 of the first planetary carrier C1 is disposed coaxially with the rotation shaft 2 of the electric motor 1 and is connected to the actuator 25, and the second planetary carrier C2 is fixed to the stator 10.

  The actuator 25 rotates the first planetary carrier C1 in the normal rotation direction or the reverse rotation direction by hydraulic pressure or restricts the rotation of the first planetary carrier C1 around the rotation axis 2 according to a control signal input from the outside. When the first planetary carrier C1 is rotated by the actuator 25, the relative positional relationship (phase difference) between the outer rotor 12 and the inner rotor 11 changes.

  FIG. 2B shows the relationship among the rotational speeds of the first ring gear R1, the first planetary carrier C1, the sun gear S, the second planetary carrier C2, and the second ring gear R2 in the planetary gear mechanism 30. It is a figure and the vertical axis | shaft is set to the rotational speed Vr of each gear.

  In FIG. 2B, the speed of the second planetary carrier C2 fixed to the stator 10 is zero. Therefore, the second ring gear R2 and the inner rotor 11 are rotated in the forward direction (Vr> 0) at a speed corresponding to g2 with respect to the second ring gear R2, for example, with respect to the sun gear S rotating in the reverse direction (Vr <0). ) Will rotate.

  Here, when the actuator 25 is in an inoperative state (a state in which the first planetary carrier C1 is not rotated by the actuator 25), the rotational speed of the first planetary carrier C1 is zero. Therefore, the first ring gear R1 and the outer rotor 12 rotate in the opposite direction with respect to the rotating sun gear S at a speed corresponding to the gear ratio g1 of the sun gear S to the first ring gear R1. Since the gear ratio g1 and the gear ratio g2 are set to be substantially equal (g1≈g2), the inner rotor 11 and the outer rotor 12 rotate synchronously, and the phase difference between the inner rotor 11 and the outer rotor 12 is increased. Maintained constant.

  On the other hand, when the actuator 25 is in an operating state (a state in which the first planetary carrier C1 is rotated by the actuator 25), the first ring gear R1 and the outer rotor 12 are first with respect to the rotating sun gear S. The speed is increased or decreased by the amount of rotation of the first planetary carrier C1 with respect to the speed corresponding to the gear ratio g1 of the sun gear S to the ring gear R1, and rotates in the reverse direction. As a result, the phase difference between the outer rotor 12 and the inner rotor 11 changes.

  The actuator 25 has at least a mechanical angle β (degrees) = (180 / P) × g1 / (1 + g1) with respect to the gear ratio g1 of the sun gear S to the first ring gear R1 and the number of pole pairs P of the electric motor 1. The first planetary carrier C1 is configured to be rotatable in the forward rotation direction or the reverse rotation direction.

  Therefore, the phase difference between the outer rotor 12 and the inner rotor 11 can be changed to the advance side or the retard side at least in the range of 180 degrees in electrical angle, and the state of the electric motor 1 is the permanent magnet 12a of the outer rotor 12. , 12b and the permanent magnets 11a and 11b of the inner rotor 11 are arranged so that the same poles face each other, and the permanent magnets 12a and 12b of the outer rotor 12 and the permanent magnets 11a and 11b of the inner rotor 11 are different. It can be set as appropriate between the field-strengthened state in which the poles are arranged to face each other.

  FIG. 3 (a) shows a field strengthening state. Since the directions of the magnetic flux Q2 of the permanent magnets 12a and 12b of the outer rotor 12 and the magnetic flux Q1 of the permanent magnets 11a and 11b of the inner rotor 11 are the same, they are synthesized. The magnetic flux Q3 increases. On the other hand, FIG. 3B shows a field weakening state, and the directions of the magnetic flux Q2 of the permanent magnets 12a and 12b of the outer rotor 12 and the magnetic flux Q1 of the permanent magnets 11a and 11b of the inner rotor 11 are opposite. The synthesized magnetic flux Q3 becomes smaller.

  FIG. 4 is a graph comparing the induced voltages generated in the armature of the stator 10 when the motor 1 is operated at a predetermined rotational speed in the state of FIG. 3A and the state of FIG. The axis is set to the induced voltage (V), and the horizontal axis is set to the electrical angle (degrees). In the figure, a is the state of FIG. 3A (field strengthening state), and b is the state of FIG. 3B (field weakening state). From FIG. 4, it can be seen that the level of the induced voltage is significantly changed by changing the phase difference between the outer rotor 12 and the inner rotor 11.

  Thus, the induced voltage constant Ke of the electric motor 1 can be changed by changing the phase difference between the outer rotor 12 and the inner rotor 11 to increase or decrease the magnetic flux of the field. Thereby, compared with the case where the induced voltage constant Ke is constant, the operable region for the output torque and the rotation speed of the electric motor 1 can be expanded. Moreover, since the copper loss of the electric motor 1 is reduced by the general dq coordinate conversion for controlling the electric motor, compared to the case where the field weakening control is performed by energizing the armature on the d-axis (field axis) side, Efficiency when operating the electric motor 1 can be increased.

  Next, the motor control device of the present invention will be described with reference to FIGS. The motor control device (hereinafter simply referred to as control device) shown in FIG. 5 is an equivalent circuit based on a two-phase DC rotating coordinate system in which the motor 1 has a field direction as a d-axis and a direction orthogonal to the d-axis as a q-axis. The amount of current supplied to the motor 1 is controlled so that the target torque Tr_c given from the outside is output from the motor 1.

  The control device is an electronic unit including a CPU, a memory, and the like, and detects a torque command Tr_c, a rotational speed Nm of the electric motor 1, and a phase difference θd between the outer rotor 12 and the inner rotor 11 (hereinafter referred to as a rotor phase difference). Based on the calculated value Ke_s of the induced voltage constant Ke of the electric motor 1 according to the value θd_s, the command value of the energization amount (hereinafter referred to as d-axis current) of the d-axis side armature (hereinafter referred to as d-axis armature) Detected by current command calculation unit 50 and current sensors 61 and 62 for calculating Id_c and a command value Iq_c of an energization amount (hereinafter referred to as q-axis current) of a q-axis side armature (hereinafter referred to as q-axis armature). Based on the current detection signals Iu and Iw from which unnecessary components have been removed by the bandpass filter 57 and the rotor angle θm of the outer rotor 12 detected by the resolver 70, the detected value of the d-axis current by three-phase / dq conversion. Id_s and q-axis electricity The three-phase / dq conversion unit 56 for calculating the detected value Iq_s of the current, the d-axis current command value Id_c calculated by the subtractor 51 and the deviation ΔId of the detected value Id_s, and the q-axis current command calculated by the subtractor 52 The command value Vd_c of the voltage applied to the d-axis armature (hereinafter referred to as the d-axis voltage) and the voltage applied to the q-axis armature (hereinafter referred to as the q-axis voltage) so that the deviation ΔIq between the value Iq_c and the detected value Iq_s decreases. A current feedback control unit 53 that determines a command value Vq_c of the d-axis voltage, an rθ conversion unit 54 that converts the command value Vd_c of the d-axis voltage and the command value Vq_c of the q-axis voltage into components of magnitude r and angle θ, A PWM calculation unit 55 is provided that converts the component of the magnitude r and the angle θ into a three-phase (U, V, W) AC voltage by PWM control. The current command calculation unit 50 and the current feedback control unit 53 constitute an energization control unit of the present invention.

Further, the control device differentiates the rotor angle θm of the outer rotor 12 detected by the resolver 70 to calculate the rotational speed Nm per unit time of the electric motor 1, the torque command value Tr_c and the electric motor 1 The motor detected by the rotation speed Nm, the voltage Vdc of a power source (not shown) that supplies power to the drive circuit (included in the PWM calculation unit 55) of the motor 1 and the temperature sensor 72 (corresponding to the temperature detection means of the present invention) A Ke command calculation unit 90 for calculating a command value Ke_c of the induced voltage constant Ke based on the temperature Th 1 of the winding ₁ and the temperature Th _{2 of the} rotor magnet; a phase difference detector 26 for detecting the rotor phase difference θd; A Ke calculation unit 92 that converts the rotor phase difference θd into an induced voltage constant Ke, a subtractor 91 that calculates a deviation ΔKe between the command value Ke_c of the induced voltage constant and the detected value Ke_s, and the phase difference of the phase difference by the deviations ΔKe and Ke_s. Command And a phase difference control unit 80 to be output to the actuator 25 determines the Shitadi_c. The Ke command calculation unit 90, the phase difference control unit 80, the Ke calculation unit 92, and the subtractor 91 constitute the rotor phase difference control means of the present invention.

  Next, the Ke command calculation unit 90 calculates the command value Ke_c of the induced voltage constant in consideration of the efficiency of the electric motor 1, and the induction according to the concept of the efficiency of the electric motor 1 and the efficiency of the electric motor 1 as the premise thereof. A method for calculating the voltage constant command value Ke_c will be described with reference to FIGS.

First, when the upper limit value of the current that can be supplied to the electric motor 1 is I _am and the upper limit value of the voltage is V _am , the following expressions (1) and (2) are established.

  However, Ia: phase current, Id: d-axis current, Iq: q-axis current, Iam: upper limit value of current.

  However, Va: phase voltage, Vd: d-axis voltage, Vq: q-axis voltage, ω: angular velocity, Ld: inductance of d-axis armature, Ke: induced voltage constant, Ra: d-axis armature and q-axis armature Resistance, Vam: Upper limit value of voltage.

  Here, Vom = Vam−Ra · Iam is set, and the limit of the induced voltage Vo is set as in the following expression (3).

  However, Vo: induced voltage, Vom: limit value of induced voltage.

Here, the induced voltage constant Ke (i.e. magnetic flux density phi _a) maximum, intermediate, when varying the three stages of the minimum, the formula (1) and (3) to that shown in FIG. About 6 (a) FIG. 6 (c).

6A to 6C, the vertical axis is set to q-axis current (Iq), the horizontal axis is set to d-axis current (Id), and the above equation (1) is expressed as Ia = Ia ₁ , Ia ₂ (Ia ₂ <Ia ₁ ), and the above equation (3) is illustrated for ω = ω ₁ , ω ₂ , ω ₃ (ω ₁ <ω ₂ <ω ₃ ). 6A shows the case where the induced voltage constant Ke is maximum, FIG. 6B shows the case where the induced voltage constant Ke is intermediate, and FIG. 6C shows the case where the induced voltage constant Ke is minimum. Show.

When the induced voltage constant Ke in FIG. 6A is maximized, the d-axis current Id that can be selected when ω becomes ω ₂ and ω ₃ when the upper limit value Iam of the phase current Ia is set to Iam _2. And the range of the q-axis current Iq is lost. In contrast, when the induced voltage constant Ke shown in FIG. 6 (b) to an intermediate, then setting the upper limit Iam phase currents Ia to Iam _2, omega is elevated in Zuchu Sa ₁ when up to omega ₃ The d-axis current Id and the q-axis current Iq can be selected within the range.

Also, when minimizing the induced voltage constant Ke in FIG. 6 (c), by setting the limit value Iam phase currents Ia to Iam _2, and selectable q-axis current Iq when omega rises to omega ₃ The range of the d-axis current is expanded to the range of Sa _{2 in} the figure.

  Thus, the smaller the induced voltage constant Ke, the closer the center of the elliptic graph according to the above equation (3) in FIGS. 6A to 6C approaches the origin (Id = 0, Iq = 0), and the motor The selection range of the d-axis current Id and the q-axis current Iq when operating 1 at a high rotation speed is widened. Therefore, the controllable range in the high rotation range of the electric motor 1 can be expanded. However, since the magnetic flux density φa decreases as the induced voltage constant Ke decreases, the torque generated in the motor 1 when the same q-axis current Iq is supplied decreases, and the efficiency of the motor 1 decreases.

  Next, FIG. 7A to FIG. 7C show different specifications, and the electric motor in the case where the field control of the electric motor 1 is performed by switching the induced voltage constant Ke to three stages (maximum, intermediate, minimum) in the electric motor. 1 exemplifies an output range (selectable range of torque and rotational speed), the vertical axis is set to the output torque (Tr) of the electric motor 1, and the horizontal axis is set to the rotational speed (Nm) of the electric motor 1. ing.

  7A to 7C, ga is a boundary line of the output guarantee range of the electric motor 1, and a region G surrounded by ga, the Tr axis, and the Nm axis is the output guarantee range of the electric motor. Kl is a boundary line of the output range of the motor 1 when the induced voltage constant Ke is maximized, Km is a boundary line of the output range of the motor 1 when the induced voltage constant Ke is intermediate, and Ks is an induced voltage constant Ke. Is the boundary line of the output range of the electric motor 1 when

  In the example of FIG. 7A, the electric motor can be operated within the output guarantee range G regardless of whether the induced voltage constant Ke is set to the maximum, intermediate, or minimum. On the other hand, in the example of FIG. 7B, when the induced voltage constant Ke is set to the maximum, the motor can be operated with the output guarantee range G maintained, but the induced voltage constant Ke is set to the middle and When set to the minimum, the electric motor cannot be operated while maintaining the output guarantee range G due to insufficient torque.

  Further, in the example of FIG. 7C, when the induced voltage constant Ke is set to the maximum, the electric motor cannot be operated while maintaining the output guarantee range G in the high rotation range. Further, when the induced voltage constant Ke is set to the middle, the torque is insufficient in the low rotation range and the torque is insufficient in the high rotation range, so that the output guarantee range G is maintained and the electric motor cannot be operated. Further, when the induced voltage constant Ke is set to the minimum, the torque is insufficient in the low rotation range, and the electric motor cannot be operated while maintaining the output guarantee range G.

  As described above with reference to FIGS. 7A to 7C, since the output range of the motor changes according to the setting of the induced voltage constant Ke, the settable range of the induced voltage constant Ke is It is necessary to determine so that the output guarantee range of the electric motor is maintained.

  Next, with reference to FIGS. 8A to 8C, in the range of the induced voltage constant Ke that satisfies the limiting conditions of the phase current Ia and the phase voltage Va according to the above formulas (1) and (3), A process for determining the d-axis current Id and the q-axis current Iq that minimizes the loss of the electric motor will be described.

  8A is a d-axis equivalent circuit, where Ra and Rc are resistances of the d-axis armature, Ld is inductance of the d-axis armature, and ωLqIoq is applied to the d-axis armature by energization of the q-axis current Iq. The induced voltage generated is shown. FIG. 8B is a q-axis equivalent circuit, where Ra and Rc are resistances of the q-axis armature, Lq is the inductance of the q-axis armature, and ωLdIod is the q-axis electric machine due to the energization of the d-axis current Id. The induced voltage generated in the child is shown.

FIG. 8 (a), the in the equivalent circuit shown in FIG. 8 (b) calculating, first, the torque of the motor Tr, output P, copper loss W _c, iron loss W _i, the following expressions (4) to (7) can do.

  Where Tr: torque, Ld: inductance of d-axis armature, Lq: inductance of q-axis armature.

  P: Output of the motor.

  However, Wc: Copper loss of the electric motor.

  However, Wi: Iron loss of an electric motor.

Then, as shown in the following equation (8), when the loss W _{loss of the} motor is represented by the copper loss Wc in the equation (6) and the iron loss Wi in the equation (7), the angular velocity ω and the torque Iod that minimizes W _loss when Tr is given can be calculated by the following equation (9).

Where W _{loss is the loss of the} motor, Wc is the copper loss of the motor, and Wi is the iron loss of the motor.

  Further, Ioq can be calculated by substituting the set values of Iod and the induced voltage constant Ke calculated by the above equation (9) into the above equation (4). Then, Id can be calculated from the equivalent circuit of FIG. 8A by the following equation (10), and Iq can be calculated from the equivalent circuit of FIG. 8B by the following equation (11).

  When the induced voltage constant Ke is varied by changing the rotor phase difference, the maximum value of Ke is represented by Ke_max, and the induced voltage constant within the variable range is represented by Ke = k · Ke_max. K that minimizes the loss of the electric motor can be calculated.

From the above equation (12), the command value Ke_c of the induced voltage constant Ke when the angular velocity ω and the torque Tr of the motor are given can be obtained. FIG. 8C shows the above equation (8) with the vertical axis set to the loss W _loss and the horizontal axis set to the induced voltage constant Ke. In the example of Wl ₁ , the variable range of Ke ( Ke_ ₁ W _loss in Ke_ ₁ is the lower limit of ~Ke_ ₃₎ becomes the minimum. Further, W _loss is minimized in Ke_ ₂ in the example of Wl _2, W _loss is minimized in Ke_ ₃ in the example of Wl _3. In this way, the induced voltage constant Ke that minimizes the loss of the electric motor can be calculated.

  Next, when the induced voltage constant Ke is set to be large so that the loss of the motor is minimized and the efficiency is maximized, the rotational speed of the motor rapidly increases due to, for example, a failure of the transmission connected to the motor or a failure of the drive circuit. When it rises, the margin until the phase voltage Va of the motor exceeds the limit voltage Vam and becomes uncontrollable is reduced.

  Therefore, the control device performs control to ensure a margin for failure (abnormality) such as failure of the transmission connected to the electric motor or failure of the drive circuit.

  FIG. 9 shows “efficiency improvement control” for selecting the induced voltage constant Ke with emphasis on the efficiency of the motor and “induced voltage reduction control” for selecting the induced voltage constant Ke with emphasis on the margin of the motor against the failure. The procedure for setting the selection range of the induced voltage constant Ke when switching and executing is shown. In (i) to (v), the vertical axis is set to the torque Tr and the horizontal axis is set to the rotational speed Nm. Yes. Further, ga is a boundary line of the operation guarantee range of the electric motor.

(i) shows the output characteristics of the motor when the induced voltage constant Ke is set to the maximum, Kl is the boundary line of the output range of the motor, La ₁ is the boundary line of 90% efficiency, and Lb ₁ is 85% efficiency. The boundary line Lc ₁ is an 80% efficiency boundary line. Further, (ii) shows the output characteristic of the motor at the time of setting the induced voltage constant Ke in the middle, Km boundary line of the output range of the motor, La ₂ is 90% efficient boundary line, Lb ₂ Efficiency The 85% boundary line, Lc ₂ is the 80% efficiency boundary line. (Iii) shows the output characteristics of the motor when the induced voltage constant Ke is set to the minimum. Ks is the boundary line of the output range of the motor, La ₃ is the boundary line of 90% efficiency, and Lb ₃ is the efficiency. An 85% boundary line and Lc ₃ are 80% efficient boundary lines.

  From (i) to (iii), it can be seen that as the induced voltage constant Ke is decreased, the efficiency of the electric motor in the low rotation range decreases and the output torque of the electric motor in the high rotation range decreases.

  Next, (iv) is a combination of (i) to (iii), and the induced voltage constant Ke for maintaining the efficiency of the motor at 90% (corresponding to the first limit range of the present invention) or more. A selection pattern is shown.

In (iv), Ba ₁ is a range surrounded by the maximum time and the boundary line d ₁ of the intermediate time and Tr axis and Nm axis of boundary lines ga and the induced voltage constant Ke of the guaranteed operating range, in Ba ₁ is The maximum induced voltage constant Ke is selected. Ba ₂ is a range surrounded by the boundary line e ₁ , Km, Ks, and Nm axis between d ₁ and the induced voltage constant Ke at the intermediate and minimum times. In Ba ₂ , the intermediate induced voltage constant Ke is Selected. Ba ₃ is a range surrounded by the e ₁ , Ks, ga, and Nm axes, and the minimum induced voltage constant Ke is selected for Ba ₃ .

On the other hand, (v) combines (i) to (iii) to allow the efficiency of the motor to drop to 85% (corresponding to the first limiting efficiency of the present invention), and the induced voltage constant Ke This shows a selection pattern for making the size as small as possible. Figure Fa ₁ is a range surrounded by the maximum time and the boundary line d ₂ and Tr axis at intermediate and Nm axis of boundary lines ga and the induced voltage constant Ke of the guaranteed operating range, maximum induced in Fa ₁ A voltage constant Ke is selected.

Fa ₂ is a range surrounded by boundary lines e ₂ , K m, K s, ga and N m axes between d ₂ and the induced voltage constant Ke at the intermediate and minimum times. In Fa ₂ , the intermediate induced voltage constant Ke is obtained. Is selected. Further, Fa ₃ is a range surrounded by e ₂ , Ks, ga and Nm axis, and the minimum induced voltage constant Ke is selected for Fa ₃ .

Then, as shown in FIG. 10A, the control device maps a basic Ke map Bm ₁ that maps the selection diagram of FIG. 9 (iv) corresponding to the power supply voltages Vdc = V1, V2, V3,. , Bm ₂ , Bm ₃ ,..., And the fail corresponding Ke maps Fm ₁ , Fm ₂ , Fm ₃ respectively mapping the selection diagram of FIG. 9 (v) corresponding to the power supply voltages Vdc = V1, V2, V3,. ,... Are stored in a memory (not shown).

  Next, the execution procedure of the control process of the rotor phase difference θd by the control device will be described according to the flowchart shown in FIG.

STEP1 to STEP5 and STEP10 are processes by the Ke command calculation unit 90, and the Ke command calculation unit 90 acquires the torque command Tr_c, the rotation speed Nm of the electric motor 1, and the power supply voltage Vdc in STEP1. In subsequent STEP 2, the Ke command calculation unit 90 acquires the winding temperature Th ₁ of the electric motor ₁ and the rotor magnet temperature Th ₂ .

In STEP 3, the Ke command calculation unit 90 recognizes a margin for heat generation of the electric motor 1 by comparing the winding temperature Th ₁ of the electric motor ₁ and the temperature Th _{2 of the} rotor magnet with a preset reference temperature. . When the winding temperature Th 1 of the motor ₁ and the rotor magnet temperature Th ₂ are lower than the reference temperature, it is determined that the motor 1 can be operated with reduced efficiency, and the process branches to STEP 10. On the other hand, when the winding temperature Th 1 of the electric motor ₁ and the temperature Th _{2 of the} rotor magnet are lower than the reference temperature, it is determined that it is impossible to operate the motor 1 with reduced efficiency, and the process proceeds to STEP 4.

STEP 10 is a process for executing the above-described “induced voltage reduction control”, and the Ke command calculation unit 90 includes the fail-corresponding Ke maps Fm ₁ , Fm ₂ , Fm ₃ ,... Shown in FIG. Then, a fail corresponding Ke map corresponding to the power supply voltage Vdc acquired in STEP 1 is selected, and the induced voltage constant Ke is obtained by applying the torque command Tr_c and the rotational speed Nm to the map.

STEP 4 is a process for executing the above-described “efficiency improvement control”, and the Ke command calculation unit 90 includes the basic Ke maps Bm ₁ , Bm ₂ , Bm ₃ ,... Shown in FIG. The basic Ke map corresponding to the power supply voltage Vdc acquired in STEP 1 is selected, and the induced voltage constant Ke is obtained by applying the torque command Tr_c and the rotational speed Nm to the map.

  When the induced voltage constant Ke is set by the fail-corresponding Ke map and the basic Ke map, the efficiency of the electric motor 1 is estimated by the selection pattern of FIG. 9 described above. The configuration for performing this estimation is the present invention. It corresponds to the efficiency estimation means.

  Next, in STEP 5, the Ke command calculation unit 90 outputs Ke obtained in STEP 4 or STEP 10 as a command value Ke_c of the induced voltage constant.

  The next STEP 6 is processing by the phase difference control unit 80. Referring to FIG. 5, the phase difference control unit 80 calculates the command value Ke_c of the induced voltage constant Ke calculated by the subtracter 91 and the detected value Ke_s. The deviation ΔKe is added to Ke_s and applied to the conversion map of the rotor phase difference θd and the induced voltage constant Ke in FIG. Then, the phase difference control unit 80 outputs the rotor phase difference θd obtained from the conversion map to the actuator 25 as the rotor phase difference command value θd_c. Thereby, the rotor phase difference θd of the electric motor 1 is changed.

  In this case, “induced voltage reduction control” is executed by the processing of STEP10, STEP5, and STEP6, and “efficiency improvement control” is executed by the processing of STEP4, STEP5, and STEP6.

  In STEP 6, there is a certain time delay from when the rotor phase difference command value θd_c is output to the actuator 25 until the inner rotor actually moves to a position corresponding to θd_c. Accordingly, the field control unit 60 causes the adder 51 to correct the d-axis current so as to reduce the deviation between the rotor phase difference command value θd_c (corresponding to the target value of the rotor phase difference of the present invention) and the detected value θd_s. Add the value Id_e. Thereby, the excess and deficiency of the field due to the response delay of the actuator 25 can be reduced.

  When the temperature of the motor 1 is low and the margin for heat generation is large by the processing of FIG. 11 described above, “induced voltage reduction control” is performed to reduce the induced voltage constant Ke of the motor 1 by the “failure Ke map”. The Thus, when a failure such as a failure of the transmission connected to the motor 1 or a drive circuit of the motor 1 occurs and the rotational speed of the motor 1 increases rapidly, the induced voltage generated in the armature of the motor 1 is reduced. Since the degree of increase is reduced, it is possible to prevent the energization control of the electric motor 1 from being disabled due to the increase of the induced voltage, causing the phase voltage of the electric motor 1 to be equal to or higher than the power supply voltage.

  Further, when the temperature of the motor 1 is high and the margin for heat generation is low, the “efficiency improvement control” for increasing the induced voltage constant Ke of the motor 1 by the “basic Ke map” and improving the efficiency of the motor 1 is executed. . And since heat_generation | fever of the electric motor 1 by a heat loss is suppressed by this, the performance fall of the electric motor 1 by a temperature rise can be prevented.

  In the present embodiment, the rotor phase difference θd of the electric motor 1 is selected by switching to the maximum, middle, and minimum three stages. However, it is switched to two stages, four stages or more, or continuous instead of stepwise. Alternatively, the rotor phase difference θd may be changed.

  In the present embodiment, the temperature of the electric motor 1 is detected by the temperature sensor. However, the temperature of the electric motor 1 may be estimated and detected by an integrated value of the power supplied to the electric motor 1. In this case, the temperature change of the electric motor 1 can be detected with good responsiveness.

  Further, a future temperature change of the electric motor 1 may be predicted from the temperature change history of the electric motor 1, and “efficiency improvement control” and “induced voltage reduction control” may be switched based on the prediction result.

  In the present embodiment, the “induced voltage reduction control” and the “efficiency improvement control” are switched according to the temperature of the electric motor 1, but only the “induced voltage reduction control” is executed without performing such switching. Even if it is a case, the effect of this invention can be acquired.

  In the present embodiment, the motor control device according to the present invention has been illustrated by converting the motor 1 into an equivalent circuit based on the dq coordinate system, which is the rotation coordinate of the two-phase DC, but fixing the two-phase AC. The present invention can also be applied to the case where the circuit is converted into an equivalent circuit based on an αβ coordinate system, which is a coordinate system.

The block diagram of DC brushless motor provided with the double rotor. The block diagram of the mechanism and operation | movement explanatory drawing of a mechanism which change the phase difference of the outer side rotor and inner side rotor of DC brushless motor shown in FIG. Explanatory drawing of the effect by changing the phase difference of an outer side rotor and an inner side rotor. Explanatory drawing of the effect by changing the phase difference of an outer side rotor and an inner side rotor. The control block diagram of the control apparatus of an electric motor. Explanatory drawing of the selection range of the current vector corresponding to the restriction | limiting of an electric current and a voltage. Explanatory drawing of the change of the output range of an electric motor by the difference in an induced voltage constant. Explanatory drawing regarding the process which calculates the induced voltage constant from which the loss of an electric motor becomes the minimum. Explanatory drawing of the process which selects an induced voltage constant in consideration of the efficiency with respect to an electric motor, and the margin with respect to a failure. Explanatory drawing of the map for determining the map for determining the induced voltage constant, and the phase difference of a double rotor. The flowchart of the process which controls the phase difference of a double rotor by the efficiency conditions according to the temperature of an electric motor. Explanatory drawing of the necessity for the field weakening control in a drive side and a regeneration side.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Motor rotating shaft, 10 ... Stator, 11 ... Inner rotor, 11a, 11b ... Permanent magnet, 12 ... Outer rotor, 12a, 12b ... Permanent magnet, 25 ... Actuator, 30 ... Planetary gear mechanism, C1 ... first planetary carrier, C2 ... second planetary carrier, R1 ... first ring gear, R2 ... second ring gear, S ... sun gear, 31 ... first planetary gear, 32 ... second planetary gear, 33 ... sun gear rotation Axis 34, bearing 35, rotation axis of first planetary carrier 50 ... current command calculation unit 60 ... field control unit 72 ... temperature sensor 80 ... phase difference control unit 90 ... Ke command calculation unit 92 ... Ke Calculation unit

Claims (4)

The operation of a permanent magnet field-type rotary motor in which a first rotor and a second rotor having a plurality of fields by permanent magnets are arranged concentrically around the rotation shaft, the first rotor, the second rotor, A control device for an electric motor for controlling by performing field control for changing an induced voltage constant of the electric motor by changing a rotor phase difference that is a phase difference of
Energization control means for performing energization control for controlling the energization amount to the armature of the motor so that the output torque of the motor becomes the target torque according to a predetermined target torque and an induced voltage constant of the motor When,
Efficiency estimating means for estimating the efficiency of the electric motor when executing the energization control;
When executing the energization control, the rotor phase difference is set such that the induced voltage constant of the motor is reduced within a range in which the efficiency of the motor estimated by the efficiency estimating means is higher than the first limiting efficiency. And a rotor phase difference control means for performing induced voltage reduction control for changing the motor. A rotation speed detecting means for detecting the rotation speed of the electric motor;
The efficiency estimating means estimates the efficiency of the electric motor when executing the energization control based on the target torque, the rotational speed of the electric motor, and a power supply voltage of a driving circuit of the electric motor. The motor control device according to claim 1. Temperature detecting means for detecting the temperature of the electric motor,
The rotor phase difference control means is configured to control the induced voltage reduction control according to the temperature of the motor and the rotor position so that the efficiency of the induced motor is equal to or higher than a second limiting efficiency higher than the first limiting efficiency. 3. The motor control device according to claim 1, wherein the efficiency improvement control for changing the phase difference is switched. Rotor phase difference detection means for detecting the rotor phase difference,
The energization control unit reduces a difference between a target value of the rotor phase difference and a detected value of the rotor phase difference by the rotor phase difference detection unit when the rotor phase difference is changed by the rotor phase difference control unit. 4. The electric motor according to claim 1, wherein an amount of field weakening current for reducing a voltage between terminals of the electric machine of the electric motor is controlled. Control device.

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