JP2010130870A - Winding field type motor, and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variations in motor torque caused by variations in field current. <P>SOLUTION: One side terminals of field windings 7, 8 are connected to slip rings 11a, 11b, respectively. The other side terminals of the field windings 7, 8 are connected to a slip ring 11c. Brushes 12a, 12b, 12c slide along the slip rings 11a, 11b, 11c, respectively. The brush 12c is connected to a positive electrode of a DC power supply 22 whose negative electrode is grounded. The brush 12a is connected to a drain of a driving element 23 whose source is grounded. The brush 12b is connected to a drain of a driving element 24 whose source is grounded. Drive signal input terminals 25, 26 turn on/off the driving elements 23, 24 or perform PWM current control of them to drive the field windings 7, 8, individually. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a field winding type motor having a field winding type rotor and a control method thereof.

In the field winding type motor having the field winding type rotor, when the field weakening control is performed, the current of the field winding is reduced (for example, Patent Document 1). Further, in the case of a Landell type motor having a pair of Landel type rotors, two rotor windings are connected in series or in parallel, and a field current is supplied from a pair of slip rings (for example, Patent Documents). 2).
JP-A-11-31498 JP 2002-171731 A

  However, in the above-described conventional field winding type motor, when field weakening control is performed, even if two field windings are provided, the field current is reduced at the same time because two field windings are provided. The magnetic flux at that time is in a non-saturated region, and there is a problem that the motor torque varies greatly due to fluctuations in the amount of magnetic flux caused by variations in the field current.

  In order to solve the above problems, the present invention provides a field winding type motor including a field winding type rotor, a plurality of field windings, a slip ring for supplying a current to each field winding, and a field winding. A magnetic current control circuit.

  According to the present invention, since the field current can be controlled for each field winding, when performing field-weakening control, while exciting one field winding in the saturation region, By exciting or stopping energization in the saturation region, there is an effect that variation in motor torque due to variation in field current can be suppressed.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating the structure of an embodiment of a field winding type motor 1 having a field winding type rotor according to the present invention. FIG. 2 is a connection diagram showing an example of a field current control circuit of the field winding type motor 1 of FIG. FIG. 3 is a diagram showing the relationship between the field current and the generated torque. 4 to 7 are diagrams showing various energization patterns at the time of field weakening control in the embodiment.

  In FIG. 1, a field winding type motor 1 having a field winding type rotor includes a housing 1, a stator core 3 fixed to the housing, and a stator winding 4 wound around the stator core 3. With. The field winding type motor 1 includes Landel-type rotor cores 5 and 6 disposed in the axial direction of the motor, and field windings 7 and 8 wound around the rotor cores 5 and 6, respectively. .

  The rotor cores 5 and 6 are fixed to a common shaft 9 and rotate together. The shaft 9 is pivotally supported on the housing 1 by bearings 10a and 10b. Three slip rings 11 a, 11 b, 11 c are provided integrally with the shaft 9 on the right side of the shaft 9 in the drawing. Brushes 12a, 12b, and 12c that are in contact with the slip rings 11a, 11b, and 11c while sliding are provided.

  The brushes 12a, 12b, and 12c are arranged so as to be slidable up and down in a cylindrical brush holder 13 fixed to the housing 1, and are urged toward the slip ring side (downward in the figure) by a coil spring 14, respectively. .

  Leaders 15 are drawn from the brushes 12a, 12b, and 12c. The lead wire 15 is connected to a field electric current control circuit (not shown) and can supply a field current independently of the field windings 7 and 8. Further, a rotation sensor 16 that detects the rotational position of the shaft 9 is provided at the right end of the shaft 9 in the drawing. A signal line 17 is drawn from the rotation sensor 16 and connected to, for example, a field electric current control circuit and an inverter not shown in the figure.

  In FIG. 1, the field winding type motor 1 including the field winding type rotor having the two field windings 7 and 8 has been described. However, the number of field windings in the present invention is two. It is not limited and may be an integer N of 3 or more. In this case, the number of slip rings and brushes is N + 1. In the embodiment, the field windings 7 and 8 are wound around the rotor cores 5 and 6, and a field magnetic flux is generated by energizing the field windings 7 and 8. However, the rotor includes a structure that generates a field magnetic flux by using a permanent magnet that assists the magnetic flux.

  In FIG. 2, the three-phase stator winding 4 is driven from an inverter 20. One terminal of each of field windings 7 and 8 is connected to slip rings 11a and 11b, respectively. The other terminals of the field windings 7 and 8 are commonly connected to the slip ring 11c.

  Further, a field current control circuit 21 including a DC power supply 22, drive elements 23 and 24 using, for example, MOS-FETs, and drive signal input terminals 25 and 26 is provided.

  The brush 12c that slides on the slip ring 11c is connected to the positive electrode of the DC power supply 22 whose negative electrode is grounded. The brush 12a that slides on the slip ring 11a is connected to the drain of the drive element 23, and the source of the drive element 23 is grounded. Similarly, the brush 12b that slides on the slip ring 11b is connected to the drain of the drive element 24, and the source of the drive element 24 is grounded. The gates of the drive elements 23 and 24 are connected to drive signal input terminals 25 and 26, respectively.

  The field current control circuit 21 can individually turn on / off the drive elements 23 and 24 or perform PWM current control using the drive signal input terminals 25 and 26 arranged individually. Therefore, the field current control circuit 21 can supply the field current to the field windings 7 and 8 individually. In FIG. 2, the example having two field windings 7 and 8 has been described as in FIG. 1, but the number of field windings may be an integer N of 3 or more. In this case, the number of drive elements is N.

  Next, drive control of the field winding by the field current control circuit 21 of the present embodiment will be described.

Generally, the generated torque of the motor is expressed by the following equation (1).
T = Pn × {φa × Iq + (Ld−Lq) × Id × Iq} (1)
Here, T: torque, Pn: number of pole pairs, φa: number of flux linkages, Ld: d-axis inductance, Lq: q-axis inductance, Id: d-axis current, Iq: q-axis current.

In the case of the field winding type motor 1 applied to the present invention, since the magnetic flux of the field can be controlled by the field current If, if φa = φa ′ × If, the equation (1) is expressed by the equation (2) Can be rewritten.
T = Pn × {φa ′ × If × Iq + (Ld−Lq) × Id × Iq} (2)

If the second term representing the reluctance torque is ignored at this time, Equation (2) becomes Equation (3), and assuming that the q-axis current Iq of the armature is constant, the torque T is proportional to the field current If.
T = Pn × φa ′ × If × Iq (3)
T∝If (4)

  On the other hand, when the motor is driven, if the induced voltage by the motor becomes high to some extent, the rotation speed is limited by the fact that no further armature current can flow, so that high rotation is possible by field-weakening control.

  However, field weakening control by reducing the field current is, for example, in the case of the magnetic flux characteristics as shown in FIG. 3, if the field current is reduced, the slope of the field current-flux characteristic graph becomes larger. The variation greatly affects the generated magnetic flux, that is, the torque.

  FIG. 3 is a diagram illustrating a relationship example between the field current and the induced voltage. Here, since the induced voltage is proportional to the field magnetic flux and the torque, the induced voltage on the vertical axis can be read as the torque of the motor. In FIG. 3, in the non-saturated region where the field current If is 3.0 [A], the induced voltage is 43 [V]. When the field current If fluctuates by 3.0 [A] ± 0.2 [A], the induced voltage fluctuates from 41 to 44 [V], and the fluctuation rate is about 4.6%. . In contrast, in the saturation region where the field current If is 7.0 [A], the induced voltage is 66 [V]. When the field current If fluctuates by 7.0 [A] ± 0.2 [A], the induced voltage fluctuates from 65.5 to 66.5 [V], and the fluctuation rate is about 0. 75%. Thus, the same field current variation of ± 0.2 [A] is about 4.6% of torque variation in the non-saturation region, and about 0.75% variation of torque in the saturation region. It becomes. As described above, the torque variation due to the variation in the field current of the same magnitude is much larger in the non-saturated region than in the saturated region.

  As described in Patent Document 1, since the d-axis current Id and the field current If of the armature are mutually induced due to the structure, not only the accuracy of the current control of the field current If but also a sudden torque fluctuation When the change of the d-axis current Id of the armature is large, the field current If also tends to fluctuate accordingly. As described above, in the conventional example, when field-weakening control is performed, the two field windings are energized in the non-saturated region according to the current-flux characteristics of the field windings, so that the torque fluctuation is large.

  In the present invention, in a motor having a plurality of field windings, energization control is performed for each field winding. Therefore, use of a non-saturated region of the field current-flux characteristics in which torque fluctuation is large with respect to changes in the field current. Can be reduced to stabilize the torque.

  In this embodiment, the magnetic flux of one rotor core can be used in the saturation region by passing a rated current through one of the field windings. At this time, the current of the other field winding can be made substantially zero, for example, and the magnetic flux linked by the other rotor core can be made zero. As a result, the generated torque can generate a torque equivalent to that in the field-weakening control in which the two field windings are driven with a small current. That is, the torque variation can be reduced while maintaining the torque.

  Next, with reference to FIGS. 4 to 7, the energization pattern of the field winding at the time of field weakening control in this embodiment will be described.

  The first energization pattern in FIG. 4 is an energization pattern at the time of field weakening control similar to a conventional motor. In this case, the field current If1 of one field winding and the field current If2 of the other field winding are simultaneously reduced from the rated value IM in the saturation region. However, the first energization pattern does not have the effect of the present invention.

  In the second energization pattern of FIG. 5, when the field weakening control is performed while the field current If1 of one field winding is reduced, the field current If2 of the other field winding has a rated value IM in the saturation region. It is a case of maintaining. From the start of the field weakening control to the time ta, the field current If2 decreases the field current If1 while maintaining the rated value IM in the saturation region. At this time, since the field current If2 is the rated value IM in the saturation region, the torque variation due to the variations in the field currents If1 and If2 has an effect of being smaller than that of the first energization pattern. After the field current If1 becomes 0 at time ta, control is performed to reduce the field current If2.

  FIG. 6 is a modified example of the second energization pattern of FIG. 5 and includes three field windings. From the start of the field weakening control until time ta, the field currents If2 and If3 of the second and third field windings decrease the rated value IM in the saturation region while decreasing the field current If1 of the first field winding. maintain. After the field current If1 of the first field winding becomes zero at time ta, the second field winding is maintained while maintaining the field current If3 of the third field winding at the rated value IM in the saturation region. Control is performed to reduce the field current If2. After the field current If2 of the second field winding becomes 0 at time tb, control is performed to reduce the field current If3 of the third field winding. The same applies to the case where there are four or more field windings, and control is performed to reduce the field current of each field winding to 0 while maintaining the field currents of the other field windings. Even if the number of field windings is three or more, torque fluctuations during field weakening control can be suppressed.

  FIG. 7 is a diagram illustrating the third energization pattern. In the third energization pattern, first, the field current If1 of the first field winding and the field current If2 of the second field winding are simultaneously started to decrease simultaneously from the rated value IM in the saturation region. It is assumed that the field current If2 at the time td when the field current If1 reaches the current value I1 is the current value I2. At this time, the field current If1 is increased to the rated value IM in the saturation region, and the field current If2 is set to zero. Thereafter, control is performed to reduce the field current If1 while maintaining the field current If2 at zero. Also in this third energization pattern, since one field current is used in the vicinity of the saturation region, there is an effect that the torque variation due to the field current variation can be reduced.

  The first to third energization patterns described above can be optimally set according to torque performance, torque variation, thermal performance, and the like according to each motor design.

  Although not shown, in the present embodiment, a temperature sensor for detecting the temperature of each field winding is provided, and the current of each field winding can be controlled based on the detection value of the temperature sensor. . That is, the temperature of the motor increases due to continuous operation. If the temperature rises excessively, the protection function is activated, and output is limited or stopped. The temperature protection function is achieved by detecting the temperature of each field winding with a temperature sensor, reducing the current of the field winding with the highest temperature, and increasing the current of the field winding with the lowest temperature. It is also possible to run the motor as long as possible before it is activated.

It is sectional drawing explaining the structure of the Example of the field winding type motor which concerns on this invention. FIG. 2 is a connection diagram illustrating a connection between the field winding type motor of FIG. 1 and a field current control circuit example. It is a figure which shows the example of a relationship between a field current and an induced voltage (soot generation | occurrence | production magnetic flux∝torque). It is a figure which shows the 1st electricity supply pattern of the field weakening control in an Example. It is a figure which shows the 2nd electricity supply pattern of field weakening control in an Example. It is a figure which shows the modification of a 2nd electricity supply pattern. It is a figure which shows the 3rd electricity supply pattern of field weakening control in an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Field winding type motor, 2 ... Housing, 3 ... Stator core, 4 ... Stator winding, 5 ... Rotor core, 6 ... Rotor core, 7 ... Field winding, 8 ... Field winding , 9 ... shaft, 10a, 10b ... bearing, 11a, 11b, 11c ... slip ring, 12a, 12b, 12c ... brush, 13 ... brush holder, 14 ... coil spring, 15 ... lead wire, 16 ... rotation sensor, 17 ... signal Line 20, inverter 21, field current control circuit 22, DC power supply 23, 24 drive element 25, 26 drive signal input terminal

Claims (2)

In a field winding type motor equipped with a field winding type rotor,
A plurality of field windings;
A slip ring for supplying current to each field winding;
A field current control circuit for supplying current to each field winding;
A field winding type motor characterized by comprising: It is a control method of the field winding type motor according to claim 1,
A field winding type motor control method comprising: supplying a current to be sequentially reduced to a first field winding and supplying a saturation current to a second field winding during field weakening control.

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