Drive control device for three-phase ac motor

Abstract

To provide a drive control device for a three-phase AC motor, in particular, a drive control device for a three-phase AC motor that can suppress fifth-order, seventh-order, eleventh-order, and thirteenth-order current ripples, which cannot be sufficiently suppressed by a basic drive control device.SOLUTION: The problem is solved by providing a driving control device with a disturbance suppression device that is arranged in the driving control device in a two-degree-of-freedom control system structure format in a broad sense and resonantly performs separation detection and separation suppression of a harmonic content of a specific order contained in a three-phase current, in addition to a basic current control device that controls a basic wave component of a three-phase current in accordance with a current command value.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a drive control device for a three-phase AC motor having a stator with three-phase windings. In particular, the present invention provides a drive control device for a three-phase AC motor that can independently and selectively suppress the 5th, 7th, 11th, and 13th current ripples that cannot be suppressed by a drive control device equipped only with a basic current control means.

[0002] The three-phase AC motor of the present invention refers to an AC motor having a stator with three-phase windings. This type of three-phase AC motor is roughly divided into three types: an induction motor, a synchronous motor, and an induction synchronous motor having a hybrid rotor that combines the rotors of an induction motor and a synchronous motor (see Non-Patent Document 1). Synchronous motors include a permanent magnet synchronous motor with a permanent magnet field rotor, a wound synchronous motor with a wound field rotor, a hybrid field synchronous motor with a rotor equipped with both a permanent magnet field and a wound field (see Non-Patent Document 1), and a synchronous reluctance motor with a rotor without a field. All of these three-phase AC motors have a stator with three-phase windings, and the difference between these three-phase AC motors lies in the rotor. [Background technology]

[0003] Three-phase AC motors can be driven by the same three-phase inverter due to the uniformity of their stators. Current control is at the core of driving these motors, and vector control is widely used for this. Vector control is based on current control of the detected three-phase current on a dq synchronous coordinate system synchronized with the rotor magnetic flux, etc. The purpose of current control is to make the stator current, converted into a two-phase current on the dq synchronous coordinate system, follow the command value without error by eliminating the effects of disturbances mixed into the fixed current. The basic current controller used for this purpose is a PI controller.

[0004] Disturbances that are mixed into the stator current are classified as temporary and persistent. It is the latter that is particularly important to eliminate. A typical example of the latter is a harmonic disturbance that has an integer multiple frequency of the fundamental frequency of the power supplied to the motor via the inverter. The main harmonic disturbances depend on the individual drive system including the inverter, but generally they are 5th negative-phase, 7th positive-phase, 11th negative-phase, and 13th positive-phase disturbances that are caused by the nonlinearity of the inverter, etc. In the dq synchronous coordinate system, these harmonic disturbances are respectively 6th negative-phase, 6th positive-phase, 12th negative-phase, and 12th positive-phase disturbances.

[0005] Regarding the elimination of harmonic disturbances, a PI controller as a basic current controller is ineffective, and various improvements have been attempted on the basic current controller on the dq synchronous coordinate system. The main improvement methods that have been reported so far can be roughly divided into a substitution current control method (see Patent Document 1, and Non-Patent Documents 1-4) in which a simple PI controller is replaced with a high-level current controller, and a multiple PI current control method (see Non-Patent Documents 5 and 6) in which a basic current controller (PI controller) is used in combination with multiple harmonic current controllers (PI controllers) dedicated to harmonic disturbances.

[0006] Known representative substitution current controllers used in the substitution current control method include a high-order current controller that changes a controller coefficient according to the frequency of a harmonic disturbance (see Patent Document 1 and Non-Patent Document 2), an Active Disturbance Rejection Controller (ADRC) (see Non-Patent Document 3), and a composite controller in which a variable coefficient secondary controller is arranged in parallel with an ADRC (see Non-Patent Document 4).

[0007] Substitution controllers are complex and have no resemblance to the original PI controller. It is also known that when using such controllers, control performance, such as response speed and stability, deteriorates as the fundamental frequency increases. Figure 12 shows ADRC, one of the substitution controllers. As is clear from the figure, ADRC is much more complex than a PI controller.

[0008] The multiple PI current control method multiplexes and arranges in parallel a PI controller corresponding to the fundamental component of the stator current, and PI controllers corresponding to the 5th, 7th, 11th, and 13th harmonic disturbances. Known multiple PI current control methods are the Yoshimoto method (see non-patent document (5)), which accompanies a vector rotator before and after the PI controller corresponding to the order, and the Zhang method (see non-patent document (6)), which replaces the PI controller accompanied by a vector rotator with a PI type D-module controller invented by Shinnaka. For reference, the core parts of the multiple PI control systems using the Yoshimoto method and the Zhang method are shown in Figures 13 and 14, respectively.

[0009] In the multiple PI current control method, all PI controllers, including the PI controller for the fundamental wave component and the PI controller for harmonic disturbances, which are arranged in the same manner in multiplex, form a current feedback loop for a single stator winding on an equal footing. Inevitably, all PI controllers affect the stability of the stator current control equally in terms of structure. In addition, each PI controller cannot be designed independently, and all controllers must be designed comprehensively. Unfortunately, however, it seems that it is very difficult to establish a controller design method for this purpose, and since the above-mentioned related literature, the multiple PI current control method does not seem to have been put to practical use. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Shinnaka Shinji: "Drive control device for synchronous motor", published patent application 2012-100510 (October 31, 2010) [Non-patent literature]

[0011] [Non-Patent Document 1] Shinji Shinnaka: "Detailed Explanation of Vector Control Technology of Synchronous Motors", ISBN 978-4-501-11820-4, Tokyo Denki University Press (2019) [Non-Patent Document 2] Shinji Shinnaka and Hideo Kishida: "Simple torque sensorless torque control for PMSM with quasi-perfect compensation of sixth-order torque ripple caused by induced voltage distortion", IEEJ Transactions on Electrical Engineering, Vol. 131, No. 8, pp. 1068-1077 (2011) [Non-Patent Document 3] efficient Active Disturbance Rejection Controller for Current Harmonics Suppression of IPMSM Drives,” IEEE Trans. Power Electron., Vol. 37, No. 9, pp. 10443-10454 (2022). [Non-Patent Document 4] Z. Wang, J. Zhao, L. Wang, M. Li, and Y. Hu: “Combined Vector Resonant and Active Disturbance Rejection Control for PMSLM Current Harmonic Suppression,” IEEE Trans. Ind. Informat., Vol. 16, No. 9,pp. 5691-5702 (2020) [Non-Patent Document 5] Kantaro Yoshimoto, Yasuhiko Kitajima, and Masahiro Tsukamoto: "Harmonic Current Control of IPM Motors", Proceedings of the 2003 National Convention of the Institute of Electrical Engineers of Japan, 4, pp.230-231(2003) [Non-Patent Document 6] Hiroshi Naga, Dai Takashima, Shinji Michiki and Muneaki Ishida, "Harmonic Current Control of PMSM by Multi-Voltage Control System Using D-Factor", Proceedings of the 2004 National Convention of the Institute of Electrical Engineers of Japan, 4, pp.199-200(2004) [Non-Patent Document 7] Shinji Shinnaka: "Vector Control Technology of Induction Motors", ISBN 978-4-501-11710-8, Tokyo Denki University Press (2015) [Non-Patent Document 8] Shinji Shinnaka: "Vector Control Technology of Permanent Magnet Synchronous Motors (Volume 1)", ISBN 978-4-88554-972-4, Dempa Shimbunsha (2008) Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made under the above background, and has the following objects. 1) Invent and develop a system structure in which the basic current controller, which is responsible for stator current control, and the disturbance suppressor, which is responsible for harmonic disturbance suppression, have mutually independent characteristics so that they do not substantially affect the main control performance of each other's equipment. 2) The mutually independent system structure allows the use of conventional PI controllers and their design methods without modification for the base current controller, without considering the presence of the disturbance suppressor. At the same time, the disturbance suppressor can be designed and constructed independently, without considering the presence of the base current controller. 3) The disturbance suppressor is given the functionality and performance to be able to suppress harmonic disturbances that exist outside the current control band specified by the basic current controller. 4) A simple and high-performance disturbance suppressor will be adopted for the independently designed and constructed disturbance suppressor. Based on this, the disturbance suppressor will be selectively designed and realized with a high degree of freedom according to the presence and strength of individual harmonic disturbances. [Means for solving the problem]

[0013] In order to achieve the above object, the invention of claim 1 is a drive control device for a three-phase AC motor having a stator with three-phase windings, comprising: means for detecting three-phase current flowing through the three-phase windings; fundamental current control means for controlling a fundamental wave component of the detected three-phase current in accordance with a current command value; disturbance suppression means that is arranged in the drive control device in a broadly defined two-degree-of-freedom control system structural form with respect to the fundamental current control means and resonantly separates, detects, and separates and suppresses harmonic components of a specific order contained in the detected three-phase current; overall voltage command generation means that additively combines a voltage command value derived from the fundamental current control means and a voltage command value derived from the disturbance suppression means to generate an overall voltage command value; and three-phase voltage application means that generates a three-phase voltage in accordance with the overall voltage command value for the three-phase AC motor and applies the voltage to the three-phase AC motor.

[0014] The invention of claim 2 is a drive control device for a three-phase AC motor according to claim 1, characterized in that the disturbance suppression means is configured using detection means capable of resonantly separating and detecting positive-phase harmonic components and negative-phase harmonic components.

[0015] The invention of claim 3 is a drive control device for a three-phase AC motor according to claim 1 or 2, wherein the disturbance suppression means is a phase compensator and an inverse D factor with gain only or a phase compensator and an inverse D factor with gain only. It is characterized by being constructed using only the inverse D factor.

[0016] The invention of claim 4 is a drive control device for a three-phase AC motor as described in claim 1, characterized in that the disturbance suppression means is configured on a three-phase uvw coordinate system, or on a two-phase coordinate system represented by an αβ fixed coordinate system or a dq synchronous coordinate system. Effect of the Invention

[0017] The effect of the invention of claim 1 will be explained. The invention of claim 1 is a basic drive control device for a three-phase AC motor, which includes a means for detecting a three-phase current flowing through a three-phase winding, a basic current control means for controlling a fundamental component of the detected three-phase current in accordance with a current command value, and a three-phase voltage application means for generating a three-phase voltage for the three-phase AC motor using a three-phase voltage command value that is an output of the basic current control means and applying the voltage to the three-phase AC motor, and further includes a new disturbance suppression means for detecting and suppressing a harmonic component of a specific order contained in the three-phase current. The main point of the invention of claim 1 is the disturbance suppression means. Therefore, the effect of the invention of claim 1 will be explained by focusing on the disturbance suppression means.

[0018] The disturbance suppression means in the invention of claim 1 is arranged in the drive control device in a broadly defined two-degree-of-freedom control system structure format with respect to the basic current control means. In consideration of this point, FIG. 1 illustrates one basic structure of a two-degree-of-freedom control system. In the figure, a control object with one input and one output is Gp(s), which is mixed with a disturbance n. The control objective of this control system is to make the response value y of the control object follow the command value y* while eliminating the influence of the disturbance. To achieve this, the control system employs a double loop structure consisting of an inner loop and an outer loop. The inner loop is a loop that processes the response value y itself with a compensator Gin(s) and feeds back the processed signal to the input terminal of the control object. The outer loop is a standard loop that processes the deviation (y*-y) between the command value and the response value with a controller and feeds back the output to the input terminal of the control object. In a two-degree-of-freedom control system having the structure shown in Figure 1, if the compensator can be responsible for 100% of the disturbance suppression function and the controller can be responsible for 100% of the response value tracking to the command value, then essentially, the two devices can be designed independently of each other.

[0019] The invention of claim 1 arranges a disturbance suppression means for detecting and suppressing a harmonic component of a specific order in a drive control device in a broadly defined two-degree-of-freedom control system structure format in relation to a fundamental current control means for making the fundamental component of a three-phase current follow a current command value. As a result, as will be described in detail in the embodiment example below, the disturbance suppression function can be 100% carried by the disturbance suppression means, and the follow-up function can be 100% carried by the fundamental current control means. Therefore, according to the invention of claim 1, the fundamental current control means and the disturbance suppression means can be designed independently of each other. As a result, the invention of claim 1 has the effect of solving problems 1) and 2).

[0020] As described above, according to the invention of claim 1, the disturbance suppression function can be entirely carried out by the disturbance suppression means, and the tracking function can be entirely carried out by the base current control means. As a result, the base current control means that is responsible for the tracking function can perform the disturbance suppression function without being influenced by the bandwidth of the specified base current control system. In turn, according to the invention of claim 1, the effect of being able to solve problem 3) can be obtained.

[0021] There are various methods for separating and detecting high frequency components contained in three-phase current, but separation and detection based on the resonance principle is the simplest and provides the best detection results. The disturbance suppression means according to the invention of claim 1 separates and detects specific order harmonic components contained in three-phase current in a resonant manner, and separates and suppresses them. In addition, the invention of claim 1 has the effect of solving the first problem of problem 4).

[0022] The effect of the invention of claim 2 will be explained. As explained in paragraph

[0004] , harmonic disturbances contained in a three-phase current can be separated by both the order and the phase sequence (positive phase, negative phase). If phase sequence information can be used in addition to order information of harmonic disturbances, it becomes possible to separate and detect harmonic components with higher accuracy. According to the invention of claim 2, it is possible to use a detection means capable of resonantly separating and detecting positive-phase harmonic components and negative-phase harmonic components. As a result, according to the invention of claim 2, it is possible to improve the accuracy of separating and detecting harmonic components, and further, it is possible to obtain the effect of the invention of claim 1, particularly the effect related to problem 4).

[0023] The effect of the invention of claim 3 will be explained. The gist of the invention of claim 3 is the inverse D-divisor. Prior to explaining the effect of the invention, the inverse D-divisor will be explained. The 3-row, 3-column (hereinafter abbreviated as 3×3) D-divisors Dt(s,ω0) and Dn(s,ω0) are defined as follows:

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[0024] The 2 × 2D divisor D(s, ω0) is defined as follows:

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[0025] The 3×3 inverse D-divisor Dt,-1(s,ω0) and the 2×2 inverse D-divisor D-1(s,ω0) are the inverse matrices of the D-divisors in equations (3) and (4), respectively. Here, we summarize the structural characteristics of the inverse D-divisor. Consider the following equations (6) and (7).

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[0026] As already explained, the main harmonic disturbances are the 5th negative phase, 7th positive phase, 11th negative phase, and 13th positive phase disturbances. When the fundamental frequency is ω1f, the sum of the 2×2 inverse D factors corresponding to these is given by the following equation.

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[0027] According to the invention of claim 3, a disturbance suppression means having required characteristics can be configured using "only an inverse D factor with gain" or "only a phase compensator and an inverse D factor with gain". Furthermore, according to the invention of claim 3, as shown in Figs. 2 and 3, while following the resonance principle, it is possible to accurately and very simply separate and detect harmonic disturbances using both the order and the phase sequence (positive phase, negative phase), and as a result, it is possible to simultaneously solve the first and second problems of problem 4). Furthermore, it is possible to further enhance the effects of the invention of claim 1 or claim 2. For the effect of the phase compensator, please refer to the related explanation of Fig. 5 below.

[0028] The effect of the invention of claim 4 will be explained. In the simple control system for the control target with one input and one output in FIG. 1, the compensator Gin(s) constituting the inner loop is arranged in only one place. The entire system consisting of a three-phase AC motor and its drive control device is much more complicated than the control system in FIG. 1. For this reason, there are many candidates for the specific arrangement of the disturbance suppression means. The invention of claim 4 limits the candidates for the arrangement to a three-phase uvw coordinate system, or a two-phase coordinate system represented by an αβ fixed coordinate system or a dq synchronous coordinate system. As a result, the invention of claim 4 has the effect of enabling the disturbance suppression means to be mounted more compactly. In turn, it has the effect of solving problems 1) to 4) in a more compact form, in other words, it has the effect of enhancing the effect of the invention of claim 1. [Brief description of the drawings]

[0029] [Figure 1] "Block diagram showing the conceptual configuration of a one-input, one-output, two-degree-of-freedom control system" [Diagram 2] "Diagram showing the implementation of 3x3 inverse D divisors and 2x2 inverse D divisors" [Diagram 3] "A diagram showing the main points of the frequency characteristics (amplitude characteristics) of the inverse D factor with gain" [Figure 4] "Block diagram showing the basic configuration of a drive control device in one embodiment" [Diagram 5] "Block diagram showing an example of a disturbance suppressor using the inverse D factor with gain" [Figure 6] "Block diagram showing the basic configuration of a drive control device in one embodiment" [Figure 7] "Block diagram showing the basic configuration of a drive control device in one embodiment" [Figure 8] "Block diagram showing the basic configuration of the drive control device in one experimental example" [Figure 9] "1. Waveform diagram showing an example of an experimental response" [Figure 10] "1. Waveform diagram showing an example of an experimental response" [Figure 11] "1. Waveform diagram showing an example of an experimental response" [Figure 12] "Block diagram showing the basic configuration of the conventional substitution controller (ADRC)" [Figure 13] "Block diagram showing one basic configuration example of a conventional multi-PI current control system" [Figure 14] "Block diagram showing one basic configuration example of a conventional multi-PI current control system" DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0030] A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 4 shows an example in which the drive control device of the present invention is applied to a three-phase AC motor. 1 indicates a three-phase AC motor, 2 indicates a three-phase inverter embodying a three-phase voltage application means, 3 indicates a current detector embodying a three-phase current detection means, 4a and 4b indicate a three-phase to two-phase converter and a two-phase to three-phase converter, respectively, 5a and 5b indicate vector rotators, 6 indicates a fundamental current controller that is the core of the fundamental current control means, 7 indicates a phase frequency generator that generates a cosine-sine signal used in the vector rotator and a fundamental frequency of the power supply, 8 indicates a disturbance suppressor that embodies the disturbance suppression means that is the core of the present invention, and 9 indicates a signal adder that embodies a total voltage command generation means. In FIG. 4, the fundamental current control means is composed of the fundamental current controller 9 and peripheral devices such as a vector rotator (4a, 4b, 5a, 5b, 7) that are essential for the operation of the fundamental current controller. Moreover, the devices 2 to 9, excluding the three-phase AC motor 1, constitute the drive control device. The detailed configuration of the phase frequency generator 7 in the figure differs depending on the type of three-phase AC motor. This detailed configuration is organized and published in texts such as Non-Patent Documents 1 and 7, is well known to those skilled in the art, and is not related to the core of the present invention. For this reason, a detailed description thereof will be omitted (see the related explanation in FIG. 8).

[0031] In this figure, to ensure simplicity, a 3×1 or 2×1 vector signal is represented by a single thick signal line. The following block diagram representations follow this same pattern. In this figure, when expressing the stator current and stator voltage vectors and the fundamental frequency ω1f, the suffix "1" is added to the corresponding symbols to indicate that these are physical quantities on the stator side. Similarly, the suffix "2" is added to the phase θ2f of the rotor magnetic flux, etc., which is a physical quantity on the rotor side, to indicate that it is a physical quantity on the rotor side. In addition, to clearly indicate the coordinate systems in which the stator current and stator voltage, which are vector signals, are defined, the suffixes r (dq synchronous coordinate system), s (αβ fixed coordinate system), and t (uvw coordinate system) are added to the corresponding symbols indicating these vector signals. Furthermore, the suffix "*" is added to the corresponding symbols for command values, such as the current command value and the voltage command value, to indicate that they are command values. Furthermore, the final voltage command value derived from the fundamental current controller is preceded by a dash symbol "'" to indicate that the command value is derived from the fundamental current controller.

[0032] The three-phase stator currents detected by the current detector 3 are converted into two-phase currents on an αβ fixed coordinate system by a three-phase to two-phase converter 4a, and then converted into two-phase currents on a dq synchronous coordinate system by a vector rotator 5a. The converted currents are converted into a control deviation from the command value and sent to a fundamental current controller 6. The fundamental current controller 6 generates two-phase voltage command values ​​on the dq synchronous coordinate system so that the control deviation becomes zero, in other words, so that the two-phase current i1r on the dq synchronous coordinate system follows the current command value i1r*. The two-phase voltage command values ​​on the dq synchronous coordinate system are sent to a vector rotator 5b. 5b converts the voltage command value on the dq synchronous coordinate system into a two-phase voltage command value v1s'* derived from the fundamental current controller of the αβ fixed coordinate system, and outputs it to a signal adder 9. The disturbance suppressor 8 processes the two-phase currents on the αβ fixed coordinate system while using the fundamental frequency ω1f, and generates a disturbance suppression auxiliary voltage command value (disturbance TIFF2025022650000010.tif8169The two voltage command values, the voltage command value from the fundamental wave current controller and the voltage command value from the disturbance suppressor, are added together to generate a two-phase total voltage command value v1s*, which is sent to the two-phase to three-phase converter 4b. The two-phase to three-phase converter 4b converts this command value into a three-phase total voltage command value and sends it to the three-phase inverter. The three-phase inverter generates a three-phase voltage according to the three-phase total voltage command value, applies it to the three-phase AC motor 1, and drives it.

[0033] In the signal adder 9, a two-phase overall voltage command value v1s* is additively synthesized from two types of voltage command values, the voltage command value derived from the fundamental wave current controller and the voltage command value derived from the disturbance suppressor, according to the following equation.

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[0034] As is already clear, the embodiment of Fig. 4 is based on claims 1 and 4, and is characterized in that the disturbance suppressor is configured on a two-phase αβ fixed coordinate system. This disturbance suppressor can be configured according to the following formula using only the 2x2 inverse D factor with gain based on the inventions of claims 2 and 3.

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[0035] K5, K7, K11, and K13 attached to the inverse D factor are disturbance suppressor gains that are left to the designer to select. These are selected individually and independently by the designer according to the following formulas, depending on the disturbance strength of the 5th negative phase, 7th positive phase, 11th negative phase, and 13th positive phase, respectively.

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[0036] The actual adjustment of the gain is summarized as follows. Generally, the suppression effect of harmonic disturbance improves with an increase in gain. At the same time, the fluctuation of the suppression transient response that occurs when the current command value changes suddenly also increases. In practice, each gain is selected in turn by repeating design trials and response confirmation for each gain individually, taking into consideration the strength of harmonic disturbance of each order and the required specifications of the drive system. Observation of the step response of the q-axis current is useful for response confirmation (see Figure 11 below). In the field of control system design, it is unavoidable to repeat design trials and response confirmation, although to different degrees. In this respect, the gain design of the disturbance suppressor is no exception. However, fortunately, the gains that depend on the order of harmonic disturbance are selected independently of each other and are single, so the design is easy even if the gain design is based on repeated design trials and response confirmation. EXAMPLES

[0037] Next, a second embodiment of the present invention will be described. A second example in which the drive control device of the present invention is applied to a three-phase AC motor is shown in Fig. 6. As is already clear, the embodiment of Fig. 6 is based on claims 1 and 4, and is characterized in that the disturbance suppressor is configured on a three-phase uvw coordinate system.

[0038] In the signal adder 9, a three-phase total voltage command value v1t* is additively synthesized from two types of voltage command values, the voltage command value from the fundamental wave current controller and the voltage command value from the disturbance suppressor, in accordance with the following equation, and is sent to the three-phase inverter.

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[0039] The disturbance suppressor may be configured according to the invention as defined in claims 2 and 3 in accordance with the following equation using a 3x3 inverse D factor with gain.

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[0040] Next, a third embodiment of the present invention will be described. A third example in which the drive control device of the present invention is applied to a three-phase AC motor is shown in Fig. 7. As is already clear, the embodiment of Fig. 7 is based on claims 1 and 4, and is characterized in that the disturbance suppressor is configured on a two-phase dq synchronous coordinate system.

[0041] In the signal adder 9, a two-phase overall voltage command value v1r* is additively synthesized from two types of voltage command values, that is, the voltage command value derived from the fundamental wave current controller and the voltage command value derived from the disturbance suppressor, according to the following equation.

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[0042] The disturbance suppressor may be configured according to the invention as defined in claims 2 and 3 in accordance with the following equation using a 2x2 inverse D factor with gain.

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[0043] In particular, when the 5th and 7th gains are set to the same value, and the 11th and 13th gains are set to the same value, as in the following equation:

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[0044] In the first and third embodiments, the disturbance suppressor is configured on the αβ fixed coordinate system and the dq synchronous coordinate system, which are representative two-phase coordinate systems. It should be noted that the two-phase coordinate system in which the disturbance suppressor of the present invention is configured is not limited to these two coordinate systems. Other two-phase coordinate systems are known to those skilled in the art, such as the γδ quasi-synchronous coordinate system, which is an estimated coordinate system of the dq synchronous coordinate system, the γδ current coordinate system in which the phase of the δ axis is the same as the phase of the stator current, and the γδ voltage coordinate system in which the phase of the δ axis is the same as the phase of the stator voltage. EXAMPLES

[0045] In the first to third embodiments, the disturbance suppressor is configured on the same coordinate system regardless of the order of the harmonic disturbance. Instead, it is noted that the configuration coordinate system of the disturbance suppressor may be changed according to the order of the harmonic disturbance. EXAMPLES

[0046] The above has presented an example that can be widely and generally applied to three-phase AC motors. Below, an example in which a three-phase induction motor, for which current ripple suppression is particularly important, is selected is presented along with the results of a numerical experiment. Figure 8 shows the schematic configuration of the experimental system. In terms of macroscopic form, this system is included in the system of Figure 4. A load device was attached to the test induction motor for the convenience of numerical experiments.

[0047] The harmonic disturbance caused by the nonlinearity of the inverter was modeled by adding the harmonic disturbance nh having the following negative and positive sequence components to an ideal inverter.

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[0048] The induction motor used in the test was that in Non-Patent Document 7 (page 101, table 4.1). The specific value of the PI gain of the basic current controller (PI controller) yielded a loop bandwidth of ωic = 2000 [rad / s], and was the same as that used in Non-Patent Document 7, without modification.

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[0049] Based on the above preparations, a numerical experiment was carried out as follows. The mechanical speed ω2m of the test induction motor was controlled by a connected load device and maintained constant at a value close to the rated speed ω2m=150 [rad / s]. As with Non-Patent Document 7, constant values ​​of 40 and 120 [A] close to the rated value were given as the d-axis current command value and the q-axis current command value. Under these conditions, taking into account the number of pole pairs Np=2 and the slip frequency ωs of the test induction motor, the four frequencies [rad / s] of the harmonic disturbance are given by the following equation.

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[0050] The results of the numerical experiment are shown in Figure 9. The meaning of the waveforms will be explained. The response including ripples is the response when the disturbance suppressor of the present invention is removed and only the basic current controller (PI controller) is used. The linear response is the response when the basic current controller and the disturbance suppressor of the present invention are used simultaneously. The waveforms are, from the top, the torque response, the q-axis current response, and the d-axis current response. Note that the torque response is provided for reference. This figure shows that "the disturbance suppressor of the present invention is capable of substantially complete and simultaneous suppression of harmonic disturbances existing outside the current loop as well as multiple harmonic disturbances."

[0051] We experimentally verified the effect that the disturbance suppressor of the present invention has on the stability of a current control system configured by a basic current controller. Selecting zero for the disturbance suppressor gain means removing the device. Conversely, increasing the gain means making the device more apparent. Based on this understanding, we carried out an experiment similar to that shown in Figure 9 using a huge suppressor gain that would not normally be selected. Specifically, the four gains were set to the following equations, which correspond to 60 times the values ​​in Figure 9.

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[0052] The effect of the disturbance suppressor of the present invention on the responsiveness of the current control system configured by the base current controller was experimentally verified. The step response was observed under the same conditions as in FIG. 9. The step response was such that the d-axis current command value was always given a constant value of 40 [A], while the q-axis current command value was initially given zero, and at a certain instant, a constant value of 120 [A] close to the rated value was given. FIG. 11 shows the result (response including ripple). In the figure, a step response (response without ripple) obtained under ideal conditions of "no harmonic disturbance" and "removal of the disturbance suppressor" is also shown as a reference for the responsiveness. It is confirmed that even when the disturbance suppressor is operated, the rise characteristic of the step change with respect to the command value, in other words, the responsiveness, is substantially equivalent to that under ideal conditions. This response means that "the insertion of the disturbance suppressor according to the present invention does not substantially affect the responsiveness of the feedback current control loop by the base current controller."

[0053] The numerical experiment results shown in Figures 9 to 11 support the fact that the present invention exhibits the effects described in the "Effects of the Invention" section, and in turn, solves the problems described in the "Problems that the Invention Aims to Solve." [Industrial Applicability]

[0054] The present invention is particularly suitable for applications that require high quality current response and torque response among applications using three-phase AC motors. [Explanation of symbols]

[0055] 1 Three-phase AC motor 2 Three-phase inverter 3 Current Detector 4a three phase two phase converter 4b Two-phase to three-phase converter 5a Vector Rotator 5b Vector Rotator 6 Fundamental Current Controller 7 Phase Frequency Generator 8 Disturbance suppressor 8a D-factor with gain 8b Phase compensator 9 Signal Adder

Claims

1. A drive control device for a three-phase AC motor having a stator with three-phase windings, comprising: A means for detecting three-phase currents flowing through the three-phase windings; a fundamental current control means for controlling a fundamental wave component of the detected three-phase current in accordance with a current command value; a disturbance suppression means that is arranged in the drive control device in a broadly defined two-degree-of-freedom control system structure format with respect to the fundamental current control means, and that resonantly separates and detects harmonic components of specific orders contained in the detected three-phase current, and separates and suppresses them; an overall voltage command generating means for additively combining a voltage command value derived from the basic current control means and a voltage command value derived from the disturbance suppression means to generate an overall voltage command value; a three-phase voltage application means for generating a three-phase voltage according to a total voltage command value for a three-phase AC motor and applying the three-phase voltage to the three-phase AC motor; A drive control device for a three-phase AC motor comprising:

2. 2. A drive control device for a three-phase AC motor according to claim 1, wherein said disturbance suppression means is constructed using detection means capable of resonantly separating and detecting positive-phase harmonic components and negative-phase harmonic components.

3. 3. A drive control device for a three-phase AC motor according to claim 1, wherein said disturbance suppression means is constructed using only an inverse D factor with gain or using only a phase compensator and an inverse D factor with gain.

4. 2. A drive control device for a three-phase AC motor according to claim 1, wherein said disturbance suppression means is configured on a three-phase uvw coordinate system, or on a two-phase coordinate system represented by an αβ fixed coordinate system or a dq synchronous coordinate system.

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