JP2018050441A - Multiple AC motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC which can efficiently drive an AC motor over a wide range while ensuring fault tolerance as a drive system, mass production / standardization effect and low cost by the same with respect to a drive system for an AC motor. Provides an electric motor drive system. SOLUTION: An AC motor 1 composed of a rotor 1-1 and a stator having two independent three-phase windings 1-21 and 1-22 and two independent three-phase windings are individually used. In addition, in an AC motor drive system having a power converter 2 capable of supplying different three-phase powers, one of the two independent three-phase windings of the AC motor, 1-21, is the other independent three. The problem was solved by configuring two independent three-phase windings so as to have characteristics (low-speed large torque characteristics, high-speed low torque characteristics) different from those of the phase windings 1-22. [Selection diagram] Fig. 3

Description

The present invention provides efficient driving over a wide range of main drive AC motors (permanent magnet type synchronous motors, field winding type synchronous motors, synchronous reluctance motors, induction motors, etc.) such as battery electric vehicles, fuel cell electric vehicles, and hybrid electric vehicles. The present invention relates to an AC motor drive system for a wide range and efficient drive, represented by a required electric motor for home appliances.

In the present invention, a portion where an AC winding is provided in an AC motor is referred to as a “stator”. The “stator” in the present invention is synonymous with “armature” in a synchronous motor. There are Y-type and Δ-type in the three-phase winding applied to the stator. As is well known to those skilled in the art, when evaluated from a three-phase terminal, the characteristics of the Y-shaped winding and the characteristics of the Δ-shaped winding are equivalently converted to each other. In order to ensure the simplicity of the explanation, the technical explanation in this specification is made assuming a Y-shaped connection. This does not lose the generality of the present invention, as is evident from the existence of equivalent transformations.

In the present invention, one set of three-phase windings in which u-phase windings, v-phase windings, and w-phase windings are connected in a Y-shape or a Δ-shape equivalent to this is called a one-winding set. The “winding group” belongs to the broad term “winding”. However, since a plurality of independent winding groups are used in the present invention, a new “winding group” is used to clarify “independence”. Use terminology. Further, the term “winding” in a narrow sense is used as a general term for a plurality of “winding groups”.

In the present invention, a two-dimensional plane is taken as a polar coordinate, and three terms of angle, spatial position, and spatial phase are used synonymously. These units are “radians” or “degrees”. In the present invention, the positive direction of the angle, the spatial position, and the spatial phase may be defined as left-handed (counterclockwise) or right-handed (clockwise). However, in this specification, in order to maintain the simplicity of the description, the positive direction of the angle, the spatial position, and the spatial phase is defined as counterclockwise (counterclockwise), and the present invention will be described. Thus, the generality of the present invention is not lost.

In the present invention, a systematic device that supplies AC power to an AC motor is referred to as a power conversion device. Inverters, matrix converters, and the like have been put into practical use as power converters that are main equipment of power converters.

2. Description of the Related Art Conventionally, a drive system for an AC motor is known in which a stator has two independent three-phase winding sets, and a power converter is connected to each winding set independently. As this type of prior invention, there are, for example, Patent Documents 1 to 5 and Non-Patent Documents 1 and 2. Patent Documents 1 to 3 and Non-Patent Documents 1 and 2 are directed to synchronous motors, and Patent Documents 4 to 5 are directed to induction motors. As is well known to those skilled in the art, the essential difference between a synchronous motor and an induction motor is in the rotor, and the stator of both motors is the same. The present invention relates to a stator of an AC motor and a power conversion device that takes charge of generation and control of power to be supplied to the stator, regardless of the difference of the rotor. For this reason, hereinafter, the present invention will be described by taking a synchronous motor as an example.

Referring to Non-Patent Document 1, an outline of a conventional drive system for an AC motor (synchronous motor) is shown in FIG. 5 as an example in which the number of pole pairs Np is Np = 1. Reference numeral 1 denotes an AC motor (including a rotor and a stator), 1-1 denotes a rotor of the AC motor, 1-21 denotes a first winding set of the AC motor stator, and 1-22 denotes an AC motor stator. 2 shows a power converter, 2-21 shows a power converter for the first system, and 2-22 shows a power converter for the second system. In the figure, in order to clarify the distinction between the first winding group and the second winding group of the stator, the first winding group is indicated by a solid line and the second winding group is indicated by a broken line. Further, since the second winding set overlaps the first winding set in terms of the winding arrangement, the second winding set is intentionally shifted to the right and drawn in order to avoid overlapping in drawing. U, v, and w used for the display of the power converter terminal and the motor terminal indicate u-phase, v-phase, and w-phase terminals, respectively. Further, the legs 1 and 2 of each terminal mean belonging to the first system and the second system, respectively.

In this figure, without losing the generality of the system, using the Y connection as a representative of the three-phase connection, considering that "there is an equivalent relationship between the Y connection and the Δ connection in the three-phase connection". I'm drawing. The system has the following features as specified in the cited document.
(1) The stator has two independent three-phase winding sets. The neutral points of the first winding group and the second winding group are not connected to ensure independence.
(2) The power converter for supplying power to each winding group is capable of supplying different three-phase power individually to each winding group. It consists of a power converter for the system.
(3) The characteristics of the first winding group and the second winding group are the same. In particular, the number of turns that govern the winding characteristics is the same. As a result, the motor parameters corresponding to each winding set are the same.

The following two points are typical effects expected by the prior invention.
(1) Even when any one of the first winding group and the second winding group fails, the operation of the AC motor can be continued using the normal winding group. That is, it is possible to improve fault tolerance as a system against a fault.
(2) By configuring the power converter using two relatively small three-phase power converters, mass production effects and standardization effects can be obtained, and thus the power converter can be manufactured at low cost. can do.

There is a limit to the voltage of power supplied to the power converter. For this reason, when the electric motor drive system represented by FIG. 1 is used for an application requiring a wide range drive, the maximum speed that can be efficiently achieved is limited. Conventionally, current control called weak magnetic flux control and weak field control is known as a method for improving the drive speed. However, when this type of control is performed, the drive efficiency is significantly reduced.

Keiichiro Ban, Kazuyoshi Obayashi: “Electric drive for automobiles”, Japanese Patent Laid-Open No. 2000-41392 (1998-7-23) Takashi Torii: “Synchronous motor device for vehicles”, Japanese Patent Application Laid-Open No. 2003-174790 (2001-12-5) Hiroshi Kanazawa, Takashi Kobayashi, Noriaki Hino, Shinji Shirakawa, Keiichi Masuno, Masanori Tsuchiya: “Drive Power Generation System for Vehicles”, Japanese Patent Laid-Open No. 2006-33897 (2004-7-12) Hiroshi Okawa, Masahiko Nagata, Makoto Taniguchi: “Automotive Motor Device”, Japanese Patent Laid-Open No. 2007-295720 (2006-4-25) Hiroshi Okawa, Masahiko Nagata, Makoto Taniguchi: “Automotive Motor Device”, Japanese Patent Application Laid-Open No. 2012-80773 (2012-1-19)

Akira Satake, Hiroshi Kato, Satoshi Imai: “Modeling and non-interference control method of multi-winding permanent magnet motor”, Proceedings of the Institute of Electrical Engineers of Japan, I, pp. 199-202 (2005) Shinnaka Shinji: “Three-phase permanent magnet synchronous motor (double winding arrangement, dynamic mathematical model, vector simulator) with inverted double three-phase winding with 180 degree spatial phase difference”, 2016 IEEJ Industry Application Division Conference Proceedings, III, pp. 285-290 (2016)

The present invention has been made under the above-mentioned background, and its purpose is to maintain the main effects (ensurement of fault tolerance as a drive system, mass production / standardization effect, and inexpensiveness as a result) by the conventional system. Another object of the present invention is to provide an AC motor drive system capable of achieving efficient drive over a wide range, which has been impossible with conventional systems.

In order to achieve the above object, the invention of claim 1 includes a rotor and a stator having n independent three-phase windings (synonymous with a winding set), where n is an integer of 2 or more. An AC motor drive system having an AC motor and a power conversion device capable of individually supplying different three-phase power to n independent three-phase windings (synonymous with a winding group), the AC motor So that at least one of the n independent three-phase windings (synonymous with the winding set) has a winding-induced characteristic different from the other independent three-phase windings (synonymous with the winding set), Features n independent three-phase windings (synonymous with winding set)

A second aspect of the present invention is the AC motor drive system according to the first aspect, wherein the power converter is configured by using a plurality of relatively small-capacity three-phase power converters.

The invention according to claim 3 is the AC motor drive system according to claim 1, wherein the AC motor is a synchronous motor with n = 2.

The invention according to claim 4 is the AC motor drive system according to claim 3, wherein two independent three-phase windings (synonymous with a winding set) of the synchronous motor, and any one independent three-phase winding Two independent three-phase windings (synonymous with winding set) provide high speed low torque characteristics for the remaining one independent three-phase winding (synonymous with winding set). A phase winding (synonymous with a winding set) is constructed.

A fifth aspect of the present invention is the AC motor drive system according to the third aspect, wherein two independent three-phase windings (synonymous with a winding set) of the synchronous motor are arranged in a space in which the number of pole pairs is one. Alternatively, in a space where the number of pole pairs is 2, they are arranged so as to be alternately mixed with a spatial phase difference.

The effect of the present invention will be described. First, the effect of the invention of claim 1 will be described. In the present invention, n is about n = 2 to n = 4 from a practical viewpoint. Here, the case of n = 2 will be described as an example in order to ensure the simplicity of the description. The number of turns of the first winding group and the second winding group is set to be different so that a significant difference in characteristics due to the windings appears. An example of torque / speed characteristics in this case is shown in FIG. FIG. 1A is an example of characteristics when the number of turns is increased so that a low speed and large torque can be obtained. On the other hand, FIG. 1B shows an example of characteristics when the number of turns is reduced so that high speed and low torque can be obtained. This figure shows an example in which the characteristics due to the winding are approximately 2 to 1 in the relative ratio evaluation. In the torque / speed characteristic diagrams of FIGS. 1A and 1B, a region where high efficiency is obtained is schematically indicated by “mesh”.

In FIG. 1, attention should be paid to the following two points.
(1) FIG. 1 (a) shows characteristics when only the first winding set is energized and the second winding set is cut off from power transmission and reception. Similarly, FIG. 1B shows characteristics when only the second winding set is energized and the first winding set is cut off from power transmission and reception.
(2) In FIG. 1 (a) and FIG. 1 (b), the rotor is not changed at all. That is, the rotor in both figures is the same.

FIG. 2 is an example of characteristics when the first winding group that provides low speed and large torque and the first winding group that provides high speed and low torque are used together. In the figure, only the first winding set that provides the low speed and large torque characteristics is used in the speed region below the speed ω1, and the first winding set and the high speed and low torque that provides the low speed and large torque characteristics in the speed region from the speed ω1 to ω2. The characteristics are schematically shown in the case where the second winding group that provides the characteristics is used in combination and only the second winding group that provides the high-speed and low-torque characteristics is used at speeds higher than ω2. As clearly shown in the figure, the region (mesh) where high efficiency is obtained has been expanded to a wide range. FIG. 2 shows an example of characteristics when n = 2. n is increased to 3 and 4 and the number of turns of each winding set is sequentially changed, so that the characteristics due to the winding are sequentially changed, thereby making the torque / speed characteristics smoother. The speed region can be further expanded.

According to the first aspect of the present invention, the n independent three-phase winding sets of the AC motor can have different winding-derived characteristics, and the torque / speed characteristics of each winding set can be changed. . Moreover, the required three-phase power can be independently supplied to each winding set by the power conversion device. As a result, while maintaining the main effects of the previous system (ensurement of fault tolerance as a drive system, mass production / standardization effect, and low cost by this), it is possible to achieve efficient drive over a wide speed range. can get.

Next, the effect of the invention of claim 2 will be described. According to invention of Claim 2, a power converter device can be comprised now using several relatively small capacity | capacitance three-phase power converters. As a result, in the configuration of the power conversion device, the effect of mass production and the effect of standardization can be enhanced, and the effect that the manufacturing cost can be reduced is also enhanced.

Next, the effect of the invention of claim 3 will be described. In ordinary synchronous motors such as permanent magnet synchronous motors and synchronous reluctance motors, the field due to the rotor is constant. In order to perform a wide range and highly efficient drive in a synchronous motor having a constant field, weak flux control and weak field control that cause a reduction in efficiency are indispensable. According to the present invention, as clarified in the description of the effect of claim 1, torque / speed similar to the flux weakening control and the field weakening control can be maintained while maintaining high efficiency without performing the flux weakening control and the field weakening control. Characteristics can be obtained. As a result, according to the invention of claim 3, it is possible to obtain the effect that the effect of the invention of claim 1 can be enjoyed at the highest level. Note that n = 2 is the minimum number for obtaining this effect, and according to the present invention, the effect of claim 1 can be obtained with a minimum change in windings for a normal synchronous motor. be able to.

The effect of the invention of claim 4 has already been described as an example in the explanation of the effect of the invention of claim 1. That is, an effect that efficient driving can be achieved in a wide speed range can be obtained.

Next, the effect of the invention of claim 5 will be described. According to the invention of claim 5, the first winding group and the second winding group are mixed alternately with a spatial phase difference in a space where the number of pole pairs is 1 or in a space where the number of pole pairs is 2. become. As a result, when both winding sets are energized, the effect that the torque ripple caused by each other winding set can be reduced is obtained (see FIGS. 3 and 4 of the embodiment). In addition, when only one of the winding groups is energized, the average torque ripple can be made zero from the spatial viewpoint, and the eccentricity of the rotating rotor can be avoided. (See FIGS. 3 and 4 in the embodiment) As described above, according to the invention of claim 5, a new preferable effect can be obtained with respect to reduction of torque ripple and reduction of influence.

  “Torque / speed characteristics example of AC motor drive system with single power converter and single winding set”   “A diagram showing an example of torque / speed characteristics of an AC motor drive system according to the present invention”   "Figure showing the configuration of an AC motor drive system when the present invention is applied to a three-phase permanent magnet type synchronous motor"   "Figure showing the configuration of an AC motor drive system when the present invention is applied to a six-phase permanent magnet synchronous motor"   “A diagram showing an example configuration of an AC motor drive system including a permanent magnet synchronous motor having two independent winding sets and two independent power converters”

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

As an AC motor, a three-phase permanent magnet type synchronous motor having a permanent magnet on a rotor is selected, and an embodiment using the entire invention of claims 1 to 5 is shown in FIG. Reference numeral 1 denotes an AC motor (including a rotor and a stator), 1-1 denotes a rotor of the AC motor, 1-21 denotes a first winding set of the AC motor stator, and 1-22 denotes an AC motor stator. , 2 indicates a power converter, 2-1 indicates a first system power converter, and 2-2 indicates a second system power converter. In the figure, in order to clarify the distinction between the first winding set 1-21 and the second winding set 1-22 of the stator, the first winding set is a thick line, and the second winding set is a thin line. Is displayed.

The example embodiment of FIG. 3 is an example of n = 2. According to the invention of claim 1, the first winding group and the second winding group are independent, and the neutral points are not connected. As is apparent from the figure, these winding sets are three-phase windings. Each winding group is individually connected to a power converter that can supply different three-phase power. Furthermore, the winding-induced characteristics differ between the first winding group and the second winding group due to differences in the number of turns. In the figure showing an outline of the configuration of the system, the difference in characteristics due to the winding is conceptually expressed by the thickness of the line representing the winding.

The system according to the embodiment of FIG. 3 includes a power conversion device including n = 2 independent power converters corresponding to n = 2 according to the invention of claim 2.

The system in the embodiment of FIG. 3 is a synchronous motor (more specifically, a permanent magnet type synchronous motor) in which n = 2 according to the invention of claim 3 as an AC motor.

The system in the embodiment of FIG. 3 according to the invention of claim 4 is the first volume which provides particularly low speed and high torque characteristics in a synchronous motor (more specifically, a permanent magnet type synchronous motor) with n = 2. The wire set is represented by a thick line, and the second winding set that provides high speed and low torque is represented by a thin line.

The system in the embodiment shown in FIG. 3 is a synchronous motor (more specifically, a permanent magnet type synchronous motor) in which n = 2 according to the invention of claim 5, and in particular, the number of pole pairs Np is set to Np = 2. In the space, the first winding group and the second winding group are mixed and arranged having a spatial phase difference of π [rad]. More specifically, the u1 phase winding of the first winding set and the u2 phase winding of the second winding set have a spatial phase difference of π [rad]. Moreover, the first winding group and the second winding group are arranged in such a manner that the phase windings are alternately mixed like u1, v2, w1, u2.

As an AC motor, a six-phase permanent magnet type synchronous motor having a permanent magnet in the rotor is selected, and an embodiment using all the inventions of claims 1 to 5 is shown in FIG. In the figure, the meanings of the constituent elements indicated by using the numbered lead lines are the same as those in the embodiment shown in FIG. Further, in the same figure, as in FIG. 3, the first winding set is indicated by a bold line in order to clarify the distinction between the first winding set 1-21 and the second winding set 1-22 of the stator. The second winding set is indicated by a thin line. The embodiment shown in the figure is different from the embodiment shown in FIG. 3 that deals with a three-phase synchronous motor, and particularly requires attention to the point that it is an example for a six-phase synchronous motor.

The example embodiment of FIG. 4 is an example where n = 2. According to the invention of claim 1, the first winding group and the second winding group are independent, and the neutral points are not connected. As is apparent from the figure, these winding sets are three-phase windings. Each winding group is individually connected to a power converter that can supply different three-phase power. Furthermore, the winding-induced characteristics differ between the first winding group and the second winding group due to differences in the number of turns. In the figure showing an outline of the configuration of the system, the difference in characteristics due to the winding is conceptually expressed by the thickness of the line representing the winding.

The system according to the embodiment of FIG. 4 includes a power conversion device including n = 2 independent power converters corresponding to n = 2 in accordance with the invention of claim 2.

The system in the embodiment of FIG. 4 is a synchronous motor (more specifically, a permanent magnet type synchronous motor) in which n = 2 according to the invention of claim 3 as an AC motor.

The system in the embodiment of FIG. 4 is a high-winding that provides low-speed high-torque characteristics, particularly in a synchronous motor (more specifically, a permanent-magnet-type synchronous motor) with n = 2 according to the invention of claim 4. The first winding group of the number is represented by a thick line, and the second winding group having a low number of windings that provides high speed and low torque is represented by a thin line.

The system in the embodiment of FIG. 4 is a synchronous motor (more specifically, a permanent magnet type synchronous motor) in which n = 2 according to the invention of claim 5, and in particular, the number of pole pairs Np is set to Np = 1. In the space, the first winding group and the second winding group are mixed and arranged with a spatial phase difference of θ12 [rad]. More specifically, the u1 phase winding of the first winding set and the u2 phase winding of the second winding set have a spatial phase difference of θ12 [rad]. In addition, the first winding group and the second winding group are arranged in such a manner that the phase windings are alternately mixed like u1, u2, v1, and v2. Note that typical values of the spatial phase difference θ12 are π / 6 [rad] and π / 3 [rad].

In the embodiment example using FIGS. 3 and 4, an example in which n = 2 is shown. As will be readily understood by those skilled in the art from the foregoing description, the inventions of claims 1 and 2 are not limited to this, and can be applied without problems even when n is 2 or more. . It should be noted that, for those skilled in the art, when the number of pole pairs Np is selected as Np = 3, 4, 5, etc. by referring to the embodiment of the number of pole pairs Np = 2 in FIG. 3 and the number of pole pairs Np = 1 in FIG. Since this embodiment is easily understood, this description is omitted.

In the embodiment using FIGS. 3 and 4, an example in which a permanent magnet type synchronous motor having a permanent magnet in a rotor is used as an AC motor. The inventions of claims 1 and 2 are not limited to this, and a field winding type synchronous motor having a field winding instead of a permanent magnet in the rotor, and further having a field in the rotor. Not applicable to synchronous reluctance motors, induction motors, etc. The embodiment in this case is not substantially different from FIGS. 3 and 4. For this reason, further explanation is omitted.

The present invention is representative of main drive motors (permanent magnet type synchronous motors, field winding type synchronous motors, synchronous reluctance motors, induction motors, etc.) of battery electric vehicles, fuel cell electric vehicles, hybrid electric vehicles, high-speed electric motors for home appliances, etc. Therefore, the present invention is suitable for a drive system for an AC motor that requires efficient driving over a wide range.

1 AC Motor 1-1 AC Motor Rotor 1-21 AC Motor Stator First Winding Set 1-22 AC Motor Stator Second Winding Set 2 Power Converter 2-1 For First System Power converter 2-2 Second system power converter

Claims (5)

When n is an integer of 2 or more,
An AC motor including a rotor and a stator having n independent three-phase windings, and a power conversion device capable of supplying different three-phase powers individually to n independent three-phase windings An AC motor drive system,
N independent three-phase windings are configured such that at least one of the n independent three-phase windings of the AC motor has a winding-derived characteristic different from other independent three-phase windings AC motor drive system characterized by that. 2. The AC motor drive system according to claim 1, wherein the power converter is configured by using a plurality of relatively small capacity three-phase power converters. 2. The AC motor drive system according to claim 1, wherein the AC motor is a synchronous motor having n of 2. 4. The AC motor drive system according to claim 3, wherein the remaining one of the two independent three-phase windings of the synchronous motor is provided so as to provide a low-speed large torque characteristic to any one of the independent three-phase windings. An AC motor drive system comprising two independent three-phase windings so as to provide high-speed and low-torque characteristics to two independent three-phase windings. 4. The AC motor drive system according to claim 3, wherein two independent three-phase windings of the synchronous motor are spatially arranged in a space where the number of pole pairs is 1 or in a space where the number of pole pairs is 2. An AC motor drive system characterized by being arranged so as to be mixed alternately with a phase difference.

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