JP2016140201A - Motor driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driving apparatus of which a common mode voltage in a motor winding is reduced without using a large filter circuit, which has a small noise terminal voltage and is small-sized one.SOLUTION: A motor driving apparatus comprises: a converter 4 that converts an AC current from a power source 2 to a DC current; an inverter 6 that converts the AC current from the converter to the DC current; and a three-phase AC motor 7 that is driven by the inverter. Further, the motor driving apparatus comprises: a comb-shaped conductor 11 that is formed by arranging a plurality of conductors which is mounted between an iron core 8 of the three-phase AC motor and the winding 10 wound on the iron core and is extended in a direction crossing to the winding in parallel while having a predetermined space, and by covering the external surface of conductors and the space with an insulator; and a first electric wiring 13 that electrically connects the comb-shaped conductor to a potential neutral point Pa of a DC power supply line 5e between the converter and the inverter.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a motor drive device that reduces noise.

  Conventionally, as an example of this type of motor drive device, there is one described in Patent Document 1. This is intended to reduce common mode noise by inserting a filter component at the output and / or input of the inverter.

JP 2005-130575 A

  In general, in a motor driving apparatus that drives a motor by an inverter so that variable speed control is possible, a ground voltage (common mode voltage) in a motor winding wound around a stator core (iron core) of the motor greatly varies. The common mode voltage is expressed by the following formula 1.

  Further, since the stator core and the motor winding wound around the stator core are close to each other, the stray capacitance between them is very large.

  For this reason, the conduction noise propagated by the large fluctuation of the common mode voltage and the large stray capacitance is increased, the noise terminal voltage and the radiation electric field are easily increased, and the EMC (Electromagnetic Compatibility) regulation value is set. Often exceeded.

  In the above conventional example, in order to reduce the fluctuation of the common mode voltage in the motor winding and put it within the EMC regulation value, a filter circuit composed of components such as a choke coil and a capacitor is inserted in the output part of the inverter. Yes.

  However, there is a problem that the size of the filter circuit component is increased in order to be within the EMC regulation value, and as a result, the apparatus size is increased.

  The problem to be solved by the present invention is to provide a small motor driving device that reduces the common mode voltage in the motor winding without using a large filter circuit, and has a small noise terminal voltage.

  The motor drive device according to the embodiment includes a converter that converts alternating current from a power source into direct current, an inverter that converts direct current from the converter into alternating current, and a motor driven by the inverter. In addition, a plurality of conductors that are interposed between the motor iron core and the winding wound around the iron core and extend in a direction intersecting the winding are arranged in parallel with a required gap. Comb conductors formed by covering the outer surfaces and gaps of these conductors with an insulator, and a first electrical wiring for electrically connecting the comb conductor to a potential neutral point of a DC power supply line between the converter and the inverter; Are provided.

1 is an electronic circuit diagram of a motor drive device according to a first embodiment. The top view of the stator core (iron core) which concerns on 1st Embodiment. FIG. 3 is a plan development view of the comb-shaped conductor shown in FIGS. 1 and 2. FIG. 3 is a schematic view when the comb-shaped conductors shown in FIGS. 1 and 2 are respectively disposed on two adjacent teeth of a stator core (iron core). VV sectional view taken on the line of FIG. FIG. 3 is an equivalent circuit diagram illustrating a distribution of stray capacitance generated between the motor winding and the stator core (iron core) according to the first embodiment. The equivalent circuit diagram which shows distribution of the stray capacitance which generate | occur | produces between the motor winding concerning a conventional motor drive device, and a stator core (iron core). The electronic circuit diagram of the motor drive device concerning a 2nd embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent part in several drawing.

  (First embodiment)

  FIG. 1 is an electronic circuit diagram showing the overall configuration of the motor drive device according to the first embodiment. As shown in FIG. 1, the motor driving device 1 has a converter 4 connected to, for example, R, S, T terminals of a three-phase AC power supply 2 via a noise filter 3.

  The noise filter 3 is a filter that removes or reduces noise generated by internal circuits such as the converter 4 and the inverter 6 of the motor drive device. The converter 4 generates a three-phase alternating current from which noise is removed or reduced by the noise filter 3. Convert (rectify) into direct current.

  The converter 4 is configured by a diode bridge circuit (not shown), for example, and the DC output side thereof is connected to the inverter 6 via the DC link unit 5.

  DC link unit 5 has DC reactor 5a, rectifying capacitor 5b, and smoothing capacitor series circuit 5e that connects first smoothing capacitor 5c and second smoothing capacitor 5d in series, and smoothes the DC output of converter 4 Then, DC power is supplied to the inverter 6.

  The inverter 6 has a plurality of three-phase switching elements (not shown) and a plurality of free-wheeling diodes, and the DC power supplied from the converter 4 via the DC link unit 5 is converted into the required three-phase by switching the switching elements. This is converted into AC power, and this three-phase AC power is supplied to the three-phase AC motor 7. That is, the inverter 6 receives an operation command signal from a control unit (not shown) and controls the operation frequency and applied voltage of the three-phase AC motor 7 to control the rotation speed per unit time of the three-phase AC motor 7. To do.

  The inverter 6 includes a bridge circuit of switching elements such as six IGBTs (Insulated Gate Bipolar Transistors).

  As shown in FIG. 2, the three-phase AC motor 7 includes an iron core 8 that is a stator core and a rotor 9 made of, for example, a ferromagnetic permanent magnet, and is configured as a three-phase synchronous motor.

  The iron core 8 is formed in an annular shape by laminating, for example, silicon steel plates, and for example, six teeth 8a, 8a,... Projecting toward the annular center side are arranged at a predetermined equal interval in the circumferential direction. .

  As shown in FIGS. 2 and 5, a plurality of layers of motor windings 10 are wound on the outer surface of each tooth 8a as a winding such as a concentrated winding in a direction orthogonal to the protruding direction of each tooth 8a.

  Then, on the outer surface of each tooth 8a, a comb-shaped conductor 11 bent in, for example, a U shape is interposed between the tooth 8a and the motor winding 10. As shown in the developed plan view of FIG. 3, the comb-shaped conductor 11 is integrally coupled to a pair of left and right side portions 11A and 11B attached to the left and right side outer surfaces of each tooth 8a, and the side portions 11A and 11B. And a central portion 11C attached to the outer surface of the upper surface of each tooth 8a.

  As shown in FIGS. 3 and 4, the comb-shaped conductor 11 includes a pair of left and right side surface portions 11 </ b> A and 11 </ b> B and a central portion 11 </ b> C extending in a direction orthogonal to the winding direction of the motor winding 10. .. Are arranged in parallel with a required gap in the horizontal direction in FIG. 3, and the length of each conductor 11d in the central portion 11C depends on the shape of each tooth 8a. Thus, it is formed to be slightly longer than the length of each conductor 11d of the pair of left and right side portions 11A, 11B. Further, the width of each conductor 11d itself is, for example, 1 mm, and the gap between adjacent conductors 11d, 11d,... Is, for example, 5 mm.

  The central portion 11C and the conductors 11d of the pair of side portions 11A and 11B are flexible and extend in the lateral direction in FIG. 3 at one end portion (upper end portion in FIG. 3) located on the base side of each tooth 8a. Are electrically connected by connecting lines 11e, 11f, and 11g having a shape of a comb.

  For example, rectangular flat connectors 11h and 11i are respectively connected to the left and right ends of the connecting line 11g of the central portion 11C. As shown in FIG. 4, the pair of left and right connectors 11h and 11i are electrically connected to each other in the circumferential direction via a connection line 11j. Thereby, all the comb-shaped conductors 11, 11,... Are electrically connected to each other. As shown in FIG. 2, one or more external terminals 12 are electrically connected to the required connectors 11h and 11i.

  .., The gaps between these conductors 11 d, 11 d,... And the outer surfaces of the connecting lines 11 e, 11 f, 11 g are, for example, FPC (Flexible Printed Circuit). ) Or FFC (Flexible Flat Cable) or the like, and is integrally covered with a flexible synthetic resin electrical insulator 11k to form a single sheet or film.

  That is, the comb-shaped conductor 11 integrally covers the respective conductors 11d, the outer peripheral edge thereof, and the gaps between the plurality of conductors 11d, 11d,.

  Further, as shown in FIG. 3, the comb-shaped conductor 11 is formed with mountain-folded fold lines 11l and 11m extending in the vertical direction in the figure at the left and right side ends in the figure of the central part 11C. , 11m, and then folded in a mountain shape to form a U shape.

  The comb-shaped conductor 11 thus formed in a U-shape is attached to each tooth 8a by being pushed and fitted from the U-shaped opening to each tooth 8a from below.

  Then, as shown in FIG. 5, for example, a plurality of layers of the above-described motor winding 10 are wound on each comb-shaped conductor 11.

  As shown in FIG. 1, the comb-shaped conductor 11 is connected to the external terminal 12 via the first electric wiring 13, and the potential neutrality of the smoothing capacitor series circuit 5 e which is an example of the DC power supply line of the DC link unit 5. Point Pa is connected.

  The potential neutral point Pa is a point where, for example, the other end of each of the capacitor 5c having one end connected to the P side wiring of the DC link unit 5 and the capacitor 5d having one end connected to the N side wiring of the DC link unit 5 is connected. is there.

  On the other hand, the three-phase AC motor 7 has an iron core 8 as a stator core electrically connected to a ground terminal 15 via a common line (earth line) 14. An EMC regulated noise terminal voltage is measured between the ground terminal 15 and each AC power supply terminal. In FIG. 1, a two-dot chain arrow indicates an example of a propagation path of a conduction noise current in a conventional motor driving device or the like that does not include the comb-shaped conductor 11.

  FIG. 6 shows an example of an equivalent circuit having first, second, and third stray capacitances C1, C2, and C3 obtained by using, for example, an analysis program by a commercially available two-dimensional finite element method.

  As shown in FIG. 6, in the present embodiment, since the comb-shaped conductor 11 is interposed between the motor winding 10 and the iron core 8, the comb-shaped conductor 11 is interposed between the motor winding 10 and the iron core 8. A series circuit in which the first and second stray capacitances C1 and C2 generated before and after are connected in series, and a circuit of the third stray capacitance C3 generated directly between the motor winding 10 and the iron core 8 are provided. A parallel circuit connected in parallel is formed.

  That is, when the comb-shaped conductor 11 is not provided as shown in FIG. 7, the stray capacitance between the motor winding 10 and the iron core 8 is the fourth stray capacitance generated between the motor winding 10 and the iron core 8. If only the comb conductor 11 is provided as in the present embodiment, the first and second stray capacitances C1 and C2 are generated before and after the comb conductor 11, and the first and second stray capacitances C1 and C2 are generated. A series circuit in which the second stray capacitances C1 and C2 are connected in series is connected in parallel to the circuit of the third stray capacitance C3.

  Note that the electrostatic capacitance of the first stray capacitance C1 becomes relatively large as the gap between the comb-shaped conductor 11 and the motor winding 10 becomes smaller than the gap between the comb-shaped conductor 11 and the iron core 8.

  Since the first stray capacitance C1 is larger than the third stray capacitance C3, the noise current flowing into the motor winding 10 flows to the comb-shaped conductor 11 via the first stray capacitance C1. To the potential neutral point Pa of the capacitor series circuit 5e through the first electric wiring 13.

  For this reason, the noise current flowing to the high impedance common line 14 side through the iron core 8 is reduced by the amount diverted from the comb-shaped conductor 11 to the first electric wiring 13 side. The noise terminal voltage measured at

  As a result, the noise terminal voltage measured at the ground terminal 15 of the common line 14 is lowered. As a result, the noise terminal voltage can be effectively reduced.

  Further, the plurality of conductors 11d of the comb-shaped conductor 11 are not formed on a single flat plate or the like, and a gap is formed between the plurality of conductors 11d, 11d,..., And an insulator 11k is formed in these gaps. Since it is filled and insulated, eddy current can be greatly reduced.

  For this reason, it can prevent that a magnetic field becomes weak with an eddy current and motor performance falls.

  Further, since the first stray capacitance C1 can be made larger than the third stray capacitance C3 by inserting the comb-shaped conductor 11, even if the impedances of the first electric wiring 13 and the common line 14 are the same. Noise can be reduced, but the lower the impedance, the better. For this reason, if the impedance is made lower than that of the common line 14 by using a low-impedance wiring or a short wiring for the first electrical wiring 13, further noise reduction is possible.

(Second Embodiment)
FIG. 8 is an electronic circuit diagram of a motor drive device 1A according to the second embodiment. This motor drive device 1A is mainly provided with a noise filter 3 having a ground capacitor 3a, and is characterized in that the first electric wiring 13 is replaced with a second electric wiring 23.

  The second electrical wiring 23 has one end connected to the comb-shaped conductor 11 and the other end connected to one end of the ground filter 3a. One end of the ground filter 3 a is connected to the connection portion 16 of the common line 14. The input side of the ground filter 3a is connected to the three-phase AC wirings 4a, 4a,.

  In FIG. 8, reference numeral 3c denotes an interphase capacitor on the input side of the noise filter 3 connected to the R, S, and T terminals of the three-phase AC power supply 2, 3d is the same, common mode choke, 3e is the same, and output side. This is an interphase capacitor.

  In the second embodiment, the smoothing capacitor series circuit 5e that is the DC power supply line according to the first embodiment is omitted. Since the configuration other than the above is the same as that of the first embodiment, a redundant description thereof will be omitted.

  Also with this motor driving device 1A, the noise current flowing into the motor winding 10 passes through the first stray capacitance C1, the comb-shaped conductor 11, and the second electric wiring 23 to one end of the grounding capacitor 3a on the connection portion 16 side. Returned and connected to the common line 14 at the connection 16. The connection portions 16 and 17 are often connected by a conductor having a parasitic inductance component such as a lead wire.

  For this reason, the noise current flowing from the iron core 8 to the ground terminal 15 on the common line 14 side is reduced by the amount of noise current flowing from the comb-shaped conductor 11 to the second electric wiring 23 side. In addition, since the impedance of the ground capacitor 3a is lower in the high frequency band than the impedance between the connection portions 16 and 17, the conduction noise current is more likely to pass through the ground capacitor 3a than to flow through the common line 14.

  Therefore, almost as in the first embodiment, the conduction noise current flows more to the second electric wiring 23 side than the common line 14.

  Accordingly, the conduction noise current flowing into the common line 14 side is reduced, so that the noise terminal voltage measured between the ground terminal 15 of the common line 14 and each AC power supply terminal is reduced.

  As a result, similar to the first embodiment, it is possible to reduce conduction noise and to prevent deterioration of motor performance due to eddy current.

  Further, also in the second electric wiring 23, by forming the impedance of the wiring itself lower than the impedance of the common line 14 by a method such as using a short wiring like the first electric wiring 13 described above, Further noise reduction effect can be obtained.

  In addition, although the said embodiment demonstrated the case where the six teeth 8a of the iron core (stator core) 8 were provided, this invention is not limited to this.

  Further, the number and width of the conductors 11d, the size and number of the gaps between the conductors 11d, the shape of the comb-shaped conductor 11, and the like of the comb-shaped conductor 11 are not limited to the above embodiment. For example, the comb-shaped conductor 11 may be formed in a square shape so as to cover the bottom surface of the teeth 8a of the iron core 8.

  Furthermore, although the case where the three-phase alternating current motor 7 was used was demonstrated in the said embodiment, a single phase may be sufficient as long as it is a motor.

  While various embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the present invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the present invention. These embodiments and modifications thereof are included in the scope and gist of the present invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,1A ... Motor drive device, 2 ... Three-phase AC power supply, 3 ... Noise filter, 3a ... Grounding capacitor, 4 ... Converter, 4a ... Three-phase AC wiring, 5 ... DC link part, 5e ... Smoothing capacitor series circuit ( DC power line), 6 ... inverter, 7 ... three-phase AC motor, 8 ... iron core, 10 ... motor winding (winding), 11 ... comb conductor, 11d ... conductor, 11k ... insulator, 12 ... external terminal, 13 DESCRIPTION OF SYMBOLS 1st electrical wiring, 14 ... Common line, 15 ... Ground terminal, 16, 17 ... Connection part, 23 ... 2nd electrical wiring, C1-C3 ... 1st-3rd stray capacitance, Pa ... Potential neutrality point.

Claims (4)

In a motor drive device comprising: a converter that converts alternating current from a power source into direct current; an inverter that converts direct current from the converter into alternating current; and a motor driven by the inverter.
A plurality of conductors, which are interposed between the iron core of the motor and a winding wound around the iron core and extend in a direction intersecting the winding, are arranged in parallel with a required gap therebetween. A comb-shaped conductor formed by covering an outer surface and a gap of these conductors with an insulator;
A first electrical wiring that electrically connects the comb-shaped conductor to a potential neutral point of a DC power source line between the converter and the inverter;
The motor drive device characterized by comprising. In a motor drive device comprising: a converter that converts alternating current from a power source into direct current; an inverter that converts direct current from the converter into alternating current; and a motor driven by the inverter.
A plurality of conductors, which are interposed between the iron core of the motor and a winding wound around the iron core and extend in a direction intersecting the winding, are arranged in parallel with a required gap therebetween. A comb-shaped conductor formed by covering an outer surface and a gap of these conductors with an insulator;
A filter that has a grounding capacitor connected to the AC wiring on the input side of the converter and a connection connected to a common line that grounds the motor, and that reduces AC noise of the motor drive device;
A second electrical wiring connecting the comb-shaped conductor to the connection portion side of the ground capacitor;
The motor drive device characterized by comprising. 2. The motor driving apparatus according to claim 1, wherein the impedance of the first electric wiring is set to be smaller than the impedance of a common line connected from the motor to a power supply ground. 3. The motor driving apparatus according to claim 2, wherein the impedance of the second electric wiring is set to be smaller than the impedance of the common line.

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