JP6834073B2 - Multiple AC motor drive system - Google Patents

Description

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

In the present invention, the portion of the AC motor in which the AC winding is applied 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 description, the technical description in this specification assumes a Y-shaped connection. As evidenced by the existence of the equivalent transformation, this does not lose the generality of the invention.

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 the characteristics thereof is referred to as a one-winding set. The "winding set" belongs to the "winding set" in a broad sense, but in the present invention, since a plurality of independent winding sets are used, a new "winding set" is used to show "independence". Use the term. In addition, the term "winding" in a narrow sense is used as a general term for a plurality of "winding sets".

In the present invention, a two-dimensional plane is grasped in polar coordinates, and the three terms of angle, spatial position, and spatial phase are used synonymously. These units are "radians" or "degrees". The angle, the spatial position, and the positive direction of the spatial phase in the present invention may be defined as either left-handed (counterclockwise) or right-handed (clockwise). However, in the present 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 left-handed (counterclockwise), and the present invention will be described. This does not lose the generality of the present invention.

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, which are the main devices of power converters.

As a drive system for an AC motor, conventionally, a stator is known to have two independent three-phase winding sets, and a power converter is independently connected to each winding set. Prior inventions of this type include, for example, Patent Documents 1 to 5 and Non-Patent Documents 1 to 2. Patent Documents 1 to 3 and Non-Patent Documents 1 to 2 are intended for synchronous motors, and Patent Documents 4 to 5 are intended for induction motors. As is well known to those skilled in the art, the essential difference between a synchronous motor and an induction motor lies in the rotor, and the stators of both motors are the same. The present invention relates to a stator of an AC motor and a power conversion device responsible for generating and controlling electric power to be supplied to the stator, regardless of the difference in rotors. Therefore, the present invention will be described below by taking a synchronous motor as an example.

With reference to Non-Patent Document 1, the outline of the drive system for the conventional AC motor (synchronous motor) is shown in FIG. 5 by taking the case where the pole logarithm Np is Np = 1. 1 is an AC motor (including a rotor and a stator), 1-1 is an AC motor rotor, 1-21 is the first winding set of an AC motor stator, and 1-22 is an AC motor stator. 2 is a power converter, 2-21 is a power converter for the first system, and 2-22 is a power converter for the second system. In the figure, in order to clarify the distinction between the first winding set and the second winding set of the stator, the first winding set is shown by a solid line and the second winding set is shown by a broken line. Further, since the second winding set overlaps with the first winding set due to the winding arrangement, the second winding set is intentionally shifted to the right for drawing in order to avoid duplication in drawing. The u, v, and w used for displaying the power converter terminal and the motor terminal indicate that they are u-phase, v-phase, and w-phase terminals, respectively. Further, the legs 1 and 2 of each terminal mean that they belong to the first system and the second system, respectively.

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

The typical effects expected by the above-mentioned prior invention are the following two points.
(1) Even if any one of the first winding set and the second winding set fails, the operation of the AC motor can be continued by using the normal winding set. That is, the failure resistance of the system against failures can be improved.
(2) By configuring the power converter using two relatively small-capacity three-phase power converters, mass production effects and standardization effects can be obtained, and by extension, power converters can be manufactured at low cost. can do.

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

Keiichiro Ban, Kazuyoshi Obayashi: "Electric Drive Device for Automobiles", Japanese Patent Application 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: "Vehicle Drive Power Generation System", Japanese Patent Application Laid-Open No. 2006-33897 (2004-7-12) Hiroshi Okawa, Masahiko Nagata, Makoto Taniguchi: "In-vehicle motor device", Japanese Patent Application Laid-Open No. 2007-295720 (2006-4-25) Hiroshi Okawa, Masahiko Nagata, Makoto Taniguchi: "In-vehicle motor device", Japanese Patent Application Laid-Open No. 2012-80773 (2012-1-19)

Akira Satake, Hiroshi Kato, Akira Imai: "Modeling and Non-Interference Control Method of Multi-Wound Permanent Magnet Motor", Proceedings of the IEEJ Industrial Application Division, I, pp. 199-202 (2005) Shinji Shinnaka: "Three-phase permanent magnet synchronous motor with inverse double three-phase winding with 180 degree spatial phase difference (double winding arrangement, dynamic mathematical model, vector simulator)", 2016 Institute of Electrical Engineers of Japan industry Proceedings of the Applied Division Conference, III, pp. 285-290 (2016)

The present invention has been made under the above background, and an object of the present invention is to maintain the main effects of the conventional system (ensuring failure resistance as a drive system, mass production / standardization effect, and ensuring low cost). The purpose is to provide an AC motor drive system that can achieve efficient drive over a wide range, which was not possible with conventional systems.

In order to achieve the above object, the invention of claim 1 comprises a rotor and a stator having n independent three-phase windings (synonymous with winding set), where n is an integer of 2 or more. This is an AC motor drive system having a power converter capable of individually supplying different three-phase powers to an AC motor and n independent three-phase windings (synonymous with a winding set). So that at least one of the n independent three-phase windings (synonymous with winding set) has winding-derived characteristics different from other independent three-phase windings (synonymous with winding set). It is characterized by forming n independent three-phase windings (synonymous with winding set).

The invention of claim 2 is the AC motor drive system according to claim 1, wherein the power converter is configured by using a plurality of three-phase power converters having a relatively small capacity.

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

The invention of claim 4 is the AC motor drive system according to claim 3, wherein any one of the two independent three-phase windings (synonymous with the winding set) of the synchronous motor is used. Two independent three to provide high speed, low torque characteristics to the remaining one independent three-phase winding (synonymous with winding assembly), just as it provides low speed, high torque characteristics to the wire (synonymous with winding assembly). It is characterized by forming a phase winding (synonymous with a winding set).

The invention of claim 5 is the AC motor drive system according to claim 3, in a space in which two independent three-phase windings (synonymous with a winding set) of the synchronous motor have a pole pair number of 1. Or, 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. From a practical point of view, n in the present invention is about n = 2 to n = 4. Here, in order to ensure the simplicity of the explanation, the case of n = 2 will be described as an example. The number of turns of the first winding set and the second winding set shall be different so as to cause a significant difference in characteristics due to the winding. 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 large low-speed torque can be obtained. On the other hand, FIG. 1B is an example of characteristics when the number of turns is reduced so that high-speed and low torque can be obtained. The figure shows an example in which the characteristics caused by winding are approximately 2: 1 in the relative ratio evaluation. In the torque / velocity characteristic diagrams of FIGS. 1A and 1B, the region where high efficiency can be obtained is roughly shown by a “mesh”.

In FIG. 1, attention should be paid to the following two points.
(1) FIG. 1 (a) shows the characteristics when only the first winding set is energized and the second winding set is cut off for power transmission / reception. Similarly, FIG. 1B shows a characteristic when only the second winding set is energized and the first winding set is cut off from power transmission / reception.
(2) In FIGS. 1 (a) and 1 (b), no change is made to the rotor. That is, the rotors in both figures are the same.

FIG. 2 is an example of characteristics when the first winding set that brings about low-speed large torque and the first winding set that brings about high-speed low torque are used in combination. In the figure, only the first winding set that provides low-speed large torque characteristics is used in the speed range of speed ω1 or less, and the first winding set and high-speed low torque that provide low-speed large torque characteristics in the speed range of speeds ω1 to ω2 are used. The characteristics when the second winding set which brings the characteristic is used together and only the second winding set which brings the high speed and low torque characteristic is used at the speed of ω2 or higher are schematically shown. As is clearly shown in the figure, the area (mesh) where high efficiency can be obtained is expanded over a wide range. FIG. 2 is an example of one characteristic when n = 2. By increasing n to 3 and 4 and sequentially changing the number of turns of each winding set to sequentially change the characteristics caused by windings, the torque / speed characteristics can be made smoother. , The speed range can be expanded further.

According to the invention of claim 1, it is possible to give the n independent three-phase winding sets of the AC motor different winding-derived characteristics, and to change the torque / speed characteristics of each winding set alone. .. Moreover, the power converter device can independently supply the required three-phase power to each winding set. As a result, while maintaining the main effects of the conventional system (securing failure resistance as a drive system, mass production / normalization effect and ensuring low cost), the effect of achieving efficient drive over a wide speed range can be achieved. can get.

Next, the effect of the invention of claim 2 will be described. According to the invention of claim 2, the power converter can be configured by using a plurality of three-phase power converters having a relatively small capacity. 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 of reducing the manufacturing cost can be enhanced.

Next, the effect of the invention of claim 3 will be described. In a normal synchronous motor such as a permanent magnet type synchronous motor and a synchronous reluctance motor, the field caused by the rotor is constant. In order to drive a synchronous motor having a constant field with high efficiency over a wide range, weak magnetic flux control and weak field control that cause a decrease in efficiency are indispensable. According to the present invention, as clarified in the description of the effect of claim 1, the torque / speed similar to the weakening magnetic flux control and the weakening field control is performed while maintaining high efficiency without performing the weakening magnetic flux control and the weakening field control. The characteristics can be obtained. As a result, according to the invention of claim 3, the effect that the effect of the invention of claim 1 can be enjoyed at the highest level can be obtained. It should be noted that n = 2 is the minimum number for obtaining this effect, and according to the present invention, there is also an effect that the effect of claim 1 can be enjoyed with the minimum winding change with respect to a normal synchronous motor. be able to.

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

Next, the effect of the invention of claim 5 will be described. According to the invention of claim 5, the first winding set and the second winding set are alternately mixed with a spatial phase difference in the space where the number of pole pairs is 1 or in the space where the number of pole pairs is 2. become. As a result, when both winding sets are energized, the effect of canceling out torque ripple caused by the mutual winding sets can be obtained (see FIGS. 3 and 4 of the embodiment). Further, when only one of the winding sets is energized, the average torque ripple can be set to zero from a spatial point of view, and the eccentricity of the rotating rotor can be avoided. (See FIGS. 3 and 4 of 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.

"Figure showing example of torque / speed characteristics of AC motor drive system when single power converter and single winding set are used" "Figure showing example of torque / speed characteristics of AC motor drive system according to the present invention" "Figure showing configuration of AC motor drive system when this invention is applied to three-phase permanent magnet type synchronous motor" "Figure showing configuration of AC motor drive system when this invention is applied to six-phase permanent magnet type synchronous motor" "A diagram showing a configuration example of an AC motor drive system including a permanent magnet type 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 the AC motor, a three-phase permanent magnet type synchronous motor having a permanent magnet in the rotor was selected, and an example of an embodiment using all the inventions of claims 1 to 5 is shown in FIG. 1 is an AC motor (including a rotor and a stator), 1-1 is an AC motor rotor, 1-21 is the first winding set of an AC motor stator, and 1-22 is an AC motor stator. 2 indicates a power converter, 2-1 indicates a power converter for the first system, and 2-2 indicates a power converter for the second system. In the figure, in order to clarify the distinction between the first winding group 1-21 and the second winding group 1-22 of the stator, the first winding group is a thick wire and the second winding group is a thin wire. It is displayed with.

The embodiment of FIG. 3 is an example of n = 2. According to the invention of claim 1, the first winding set and the second winding set are independent, and the neutral points are not connected. As is clear from the figure, these winding sets are three-phase windings. Further, a power conversion device capable of supplying different three-phase powers is individually connected to each winding set. Furthermore, the characteristics caused by winding differ between the first winding set and the second winding set due to differences in the number of turns and the like. In the figure showing the outline of the system configuration, the difference in characteristics caused by the winding is conceptually expressed by the thickness of the line expressing the winding.

According to the invention of claim 2, the system according to the embodiment of FIG. 3 includes a power conversion device including n = 2 independent power converters corresponding to n = 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 in accordance with the invention of claim 3 as an AC motor.

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

In the system according to the embodiment of FIG. 3, in accordance with the invention of claim 5, in a synchronous motor having n = 2 (more specifically, a permanent magnet type synchronous motor), in particular, the pole pair number Np is set to Np = 2. In space, the first winding set and the second winding set are mixed and arranged with 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, in the first winding set and the second winding set, the phase windings are arranged so as to be alternately mixed like u1, v2, w1, and u2.

As the AC motor, a six-phase permanent magnet type synchronous motor provided with a permanent magnet in the rotor was selected, and an example of an embodiment using all the inventions of claims 1 to 5 is shown in FIG. The meanings of the components shown by the numbered leader lines in the figure are the same as those in the embodiment of FIG. Further, in the figure, as in FIG. 3, in order to clarify the distinction between the first winding group 1-21 and the second winding group 1-22 of the stator, the first winding group is drawn with a thick line. , The second winding set is indicated by a thin line. It should be noted that the embodiment of the figure is different from the embodiment of FIG. 3 in which the three-phase synchronous motor is dealt with, and is an example of the six-phase synchronous motor.

The embodiment of FIG. 4 is an example of n = 2. According to the invention of claim 1, the first winding set and the second winding set are independent, and the neutral points are not connected. As is clear from the figure, these winding sets are three-phase windings. Further, a power conversion device capable of supplying different three-phase powers is individually connected to each winding set. Furthermore, the characteristics caused by winding differ between the first winding set and the second winding set due to differences in the number of turns and the like. In the figure showing the outline of the system configuration, the difference in characteristics caused by the winding is conceptually expressed by the thickness of the line expressing the winding.

According to the invention of claim 2, the system according to the embodiment of FIG. 4 includes a power conversion device including n = 2 independent power converters corresponding to n = 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 in accordance with the invention of claim 3 as an AC motor.

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

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

In the embodiment using FIGS. 3 and 4, an example in which n = 2 is shown. As will be easily understood by those skilled in the art by the above description, the inventions of claims 1 and 2 are not limited to this, and can be applied without any problem even when n is 2 or more. .. In addition, when a person skilled in the art selects the pole logarithm Np as Np = 3, 4, 5, etc. by referring to the embodiment of the pole logarithm Np = 2 in FIG. 3 and the pole logarithm Np = 1 in FIG. Since the embodiment of the above is easily understood, this description will be omitted.

In the embodiment using FIGS. 3 and 4, an example in which a permanent magnet type synchronous motor having a permanent magnet in the rotor is used as the AC motor is shown. 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. It also applies to synchronous reluctance motors, induction motors, etc. The embodiment in this case is not substantially different from FIGS. 3 and 4. Therefore, further description will be omitted.

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

1 AC motor 1-1 Rotor of AC motor 1-21 1st winding set of stator of AC motor 1-22 2nd winding set of stator of AC motor 2 Power converter 2-1 For 1st system Power converter 2-2 Power converter for 2nd system

Claims (4)

When n is an integer of 2 or more,
Synchronous motor consisting of a single rotor and a single stator with n independent (and thus no neutral point connections to each other ) three-phase windings and n independent three-phase windings, individually and simultaneously In addition, a pole-to-number invariant synchronous motor drive system having a power converter capable of supplying different non-zero three-phase currents
The n independent three-phase windings are configured such that at least one of the n independent three-phase windings of the synchronous motor has winding-derived characteristics different from the other independent three-phase windings. A synchronous motor drive system with an invariant pole logarithmic feature. The pole-to-number-invariant synchronous 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. Synchronous motor drive system. The independent three-phase winding system according to claim 1, wherein n in the synchronous motor is 2, and any one of the two independent three-phase windings of the synchronous motor is used. Two independent three-phase windings are configured to provide high speed, low torque characteristics to the remaining one independent three-phase winding so as to provide low speed, high torque characteristics. Synchronous motor drive system. The synchronous motor drive system according to claim 1, wherein n in the synchronous motor is 2, and two independent three-phase windings of the synchronous motor are arranged in a space having a pole pair of 1. Alternatively, a synchronous motor drive system having an invariant number of pole pairs, characterized in that they are arranged so as to be alternately mixed with a spatial phase difference in a space having a pole pair number of 2.

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