CONTROL DEVICE FOR ROTATING MACHINE

Abstract

A control device (1A) for a rotating machine includes a current detector (4) that detects stator currents flowing through a stator (7) of the rotating machine (3A); a position estimation device (6A) that calculates a rotor position estimate and a rotational speed estimate based on calculated flux linkages of the rotating machine (3A), wherein the rotor position estimate is an estimated position of a rotor (8) of the rotating machine (3A), and the rotational speed estimate is an estimated rotational speed; a control unit (5) that outputs stator voltage command values ​​based on the stator currents and the rotor position estimate to drive the rotating machine (3A); and a voltage application unit (2) that applies drive voltages to the rotating machine (3A) based on the stator voltage command values.The position estimation device (6A) updates the calculated flux linkages based on the stator voltage command values, the rotational speed estimation, and the most recently calculated flux linkages.

Description

Technical area

[0001] The present disclosure relates to a control device for a rotating machine with magnetic salient, more particularly, to a control device that controls a rotating machine whose inductance varies with a rotor position by obtaining rotor position information without using a position sensor that detects the rotor position. background

[0002] To drive a rotating machine to its full potential, rotor position information is necessary. For this purpose, a conventional rotating machine control device uses position information detected by a position sensor mounted on the rotating machine. However, position-sensorless drive technologies for rotating machines have been developed with the aim of further reducing the manufacturing costs of rotating machines, miniaturizing rotating machines, and improving the reliability of rotating machines.

[0003] Position sensorless control methods for rotating machines include a method for estimating a rotor position by applying high-frequency voltages to a rotating machine, and a method for estimating the rotor position from, for example, induced voltages or flux linkages without applying high-frequency voltages. Patent Literature 1 mentioned below discloses a method for estimating the rotor position based on flux linkages of a rotating machine.Specifically, the background section of Patent Literature 1 below discloses the technique of estimating the rotor position by performing control that converges estimates of the magnetic flux of the armature current, the flux linkages calculated based on a voltage equation for the rotating machine, to apparent magnetic fluxes of the armature current, the flux linkages being calculated using stator currents and inductances. List of citationsPatent literature

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-095135 Brief description of the inventionProblem to be solved by the invention

[0005] According to the aforementioned technique of Patent Literature 1, the flux linkages are calculated by a flux observer based on both the stator voltages and the stator currents. Therefore, one problem with the technique described in Patent Literature 1 is the complexity of the position estimation control design. For example, when the calculated flux linkages and the stator currents are used for rotor position estimation, the stator currents are used not only for rotor position estimation but also for flux linkage calculation, resulting in interference between the rotor position estimation and the flux linkage calculation. Therefore, highly sensitive and highly accurate rotor position estimation is difficult with the technique described in Patent Literature 1.

[0006] The present disclosure has been made in view of the foregoing, and an object of the present disclosure is to obtain a control device for a rotating machine capable of highly sensitive and highly accurate rotor position estimation while preventing interference between the flux linkage calculation and the position estimation calculation. Ways to solve the problem

[0007] To solve the above-mentioned problem and achieve the object, a rotating machine control device according to the present disclosure includes a current detector that detects stator currents flowing through a stator of the rotating machine, and a position estimator that calculates a rotor position estimate, which is an estimated position of a rotor of the rotating machine, and a rotation speed estimate, which is an estimated rotational speed, based on calculated flux linkages of the rotating machine. The rotating machine control device further includes a control unit that outputs stator voltage command values ​​based on the stator currents and the rotor position estimate for driving the rotating machine, and a voltage application unit that applies drive voltages to the rotating machine based on the stator voltage command values.The position estimator updates the calculated flux linkages based on stator voltage command values, the rotational speed estimate, and the most recently calculated flux linkages. Effect of the invention

[0008] The rotating machine control device according to the present disclosure has the effect of estimating the rotor position with high sensitivity and high accuracy while preventing interference between the flux linkage calculation and the position estimation calculation. Short description of the drawings Fig. 1 is a diagram illustrating an exemplary configuration of a control device for a rotating machine according to a first embodiment. Fig. 2 is a diagram illustrating a control method for converging a rotor position estimation error to zero in the first embodiment. Fig. 3 is a diagram illustrating an exemplary configuration of a control device for a rotating machine according to a second embodiment. Fig. 4 is a diagram illustrating a first exemplary hardware configuration of the rotating machine control device according to each of the first and second embodiments. Fig. 5 is a diagram illustrating a second exemplary hardware configuration of the rotating machine control device according to each of the first and second embodiments. Description of embodiments

[0009] With reference to the accompanying drawings, a detailed description is provided hereinafter in this specification of control devices for rotating machines according to embodiments of the present disclosure. First embodiment.

[0010] Fig. 1 is a diagram illustrating an exemplary configuration of a rotating machine control device according to a first embodiment. The rotating machine control device 1A according to the first embodiment is a control device that controls the operation of the rotating machine 3A. As shown in Fig. 1, the control device 1A includes a voltage application device 2, a current detector 4, a control unit 5, and a position estimator 6A. The current detector 4 is arranged between the voltage application unit 2 and the rotating machine 3A and detects stator currents i su , i sv and I sw flowing through a stator 7 of the rotating machine 3A. The voltage application unit 2 applies drive voltages to the rotating machine 3A according to stator voltage command values ​​v su *, v sv * and v sw* output from the control unit 5. Although not illustrated, a DC power supply, an inverter circuit, a pulse width modulation (PWM) unit, and others are included in the voltage application unit 2. The inverter circuit converts a DC voltage output from the DC power supply into AC voltages. The PWM unit generates PWM signals that drive switching elements of the inverter circuit.

[0011] The rotating machine 3A in the first embodiment is a rotating machine whose inductance includes a variable inductance component that varies with a rotor position, and whose rotor 8 does not include magnets. An example of this type of rotating machine 3A is a synchronous reluctance motor. A direction of the rotor 8 in which the inductance is maximized is defined as a d-axis in this document, and a direction of the rotor 8 in which the inductance is minimized is defined as a q-axis in this document. For the rotor position, the d-axis of the rotor 8 is used as a reference. Both the inverter circuit and the rotating machine 3A are configured to be three-phase in this document.

[0012] Using stator voltage command values ​​v sd * and v sq * in a rotating reference system and d- and q-axis currents i sd and i sqIn the rotating reference system, the position estimator 6A calculates a rotor position estimate θ^ r , which is an estimated position of the rotor 8. Based on the stator currents i su , i sv and i sw and the rotor position estimate θ^ r the control unit 5 generates the stator voltage command values ​​v su *, v sv * and v sw * to drive the rotating machine 3A and outputs it. Specifically, the control unit 5 uses the stator currents i su , i sv and i sw and the rotor position estimate θ^ r to set the stator voltage command values ​​v su *, v sv * and v sw * so that the rotating machine 3A can output a desired torque command value T*.

[0013] Next, a more detailed description of the operation of the control unit 5 is provided. As in Fig. 1, the control unit 5 includes a current command calculation unit 501, a three-phase to two-phase transformation unit 502, a rotating frame transformation unit 503, a dq current control unit 504, an inverse rotating frame transformation unit 505, and a two-phase to three-phase transformation unit 506.

[0014] The current command calculation unit 501 calculates the current command values ​​i sd * and i sq * in the rotating reference frame required for the rotating machine 3A to generate an output corresponding to the torque command value T*. The current command values ​​i sd * and i sq * in the two-phase rotating reference system are selected in this paper to minimize a root mean square current, that is, a copper loss of the rotating machine 3A for the torque.

[0015] The three-phase to two-phase transformation unit 502 performs a three-phase to two-phase transformation of the stator currents i su , i sv and i sw in a three-phase reference system to currents i sα and i sβ of a rotating machine in a two-phase stationary reference system, as expressed below by formula (1). Formula 1: [isαisβ]=23[1−12−12032−32]︸C32[isuisvisw]

[0016] In the first embodiment, a transformation matrix C 32 shown in the above formula (1) is used for the three-phase to two-phase transformation.

[0017] Using the rotor position estimate θ^ r the unit for transformation into a rotating reference system 503 performs a transformation into a rotating reference system of the currents i sα and i sβof the rotating machine in the two-phase stationary reference system to the currents i sd and i sq the d- and q-axes in the two-phase rotating reference system as expressed by formula (2) below. Formula 2: [isdisq]=[cos θr^sin θr^−sin θr^cos θr^]︸cdq(θr^)[isαisβ]

[0018] In the first embodiment, a transformation matrix C dq (θ^ r ), shown in the above formula (2), is used for the transformation into a rotating reference system.

[0019] The dq current control unit 504 performs a control that causes the currents i sd and i sq the d and q axes from the rotating frame transformation unit 503 that performed the rotating frame transformation with the current command values ​​i sd * and i sq* and calculates the stator voltage command values ​​v sd * and v sq * in the two-phase rotating reference system. For example, proportional-integral (PI) control is used for this current control.

[0020] Using the rotor position estimate θ^ r , which is calculated by the position estimator 6A, the rotating frame inverse transformation unit 505 performs a rotating frame inverse transformation of the stator voltage command values ​​v sd * and v sq * in the two-phase rotating reference system to stator voltage command values ​​v sα * and v sβ * in the two-phase reference system as expressed by formula (3) below. In the first embodiment, a transformation matrix C dq -1 (θ^ r), shown below in formula (3), is used for the inverse transformation into a rotating reference system. Formula 3: [vsα*vsβ*]=[cos θr^−sin θr^sin θr^cos θr^]︸Cdq1(θr^)[vsd*vsq*]

[0021] The two-phase to three-phase transformation unit 506 transforms the stator voltage command values ​​v sα * and v sβ * in the two-phase reference system to the stator voltage command values ​​v su *, v sv * and v sw * in the three-phase reference system as expressed by formula (4) below. Formula 4: [vsu*vsv*vsw*]=23[10−1232−12−32]︸C23[vsα*vsβ*]

[0022] In the first embodiment, a transformation matrix C 23 shown in the above formula (4) is used for the two-phase to three-phase transformation.

[0023] Next, a description will be provided of how the position estimator 6A estimates the rotor position, that is, the rotor position estimate θ^ r First, a model of the rotating machine 3A in the two-phase reference system is expressed by the following formulas (5) and (6). Formula 5: vsαβ=Rsisαβ+ddtψsαβ Formula 6: ψsαβ=[Lsavg+Lsvar cos(2θr)Lsvar sin(2θr)Lsvar sin(2θr)Lsavg+Lsvar cos(2θr)]isαβ

[0024] In the above formula (5), “v s αβ “ stands for stator voltages and “i s αβ “ for the stator currents. The superscript “ αβ " indicates that the values ​​are in the two-phase reference system. In the above formula (5), "R s “ stands for the winding resistance and “Ψ s αβ" for flux linkages of the rotating machine 3A, which can be expressed using a matrix as shown in the above formula (6). As already mentioned, the inductance of the rotating machine 3A varies with the rotor position. Accordingly, the inductance of the rotating machine 3A is divided into two components: a mean component and a variable component. "L savg “ represents the mean inductance component, which does not vary with the rotor position, while “L svar “ stands for the variable inductance component, which varies at twice the electrical angular frequency with which the rotor position changes. The average inductance component L savg and the variable inductance component L svar are expressed by the following formulas (7) and (8), respectively, where the d-axis inductance L sd and the q-axis inductance L sq be used. Formula 7: Lsavg=Lsd+Lsq2 Formula 8: Lsvar=Lsd−Lsq2

[0025] The transformation into a rotating reference system of the flux linkages Ψ s αβ from the above formula (6) based on the rotor position estimate θ^ r results in the following formula (9). Formula 9: ψsdq=Lsavgisdq+Lsvar[cos(2(θr−θr^))sin(2(θr−θr^))sin(2(θr−θr^))− cos(2(θr−θr^))]isdq

[0026] The superscript “ dq “ in the above formula (9) indicates that the values ​​are in the two-phase rotating reference system. In the above formula (9), the first term refers to the average inductance component L savg the inductance, which does not vary with the rotor position, and the second term refers to the variable inductance component L svarthe inductance, which varies at twice the electrical angular frequency with which the rotor position changes. Components caused by the variable inductance component L svar and the stator currents i s dq generated, as described in the second term, are referred to as the "flux linkage inductance variation components." In the first embodiment, the flux linkage inductance variation components are used in the rotor position estimation. Estimates of the flux linkage inductance variation components are denoted in this document by "Ψ ^ svar dq ” The estimates Ψ ^ svar dq the flux linkage inductance variation components can be derived from the second term of the above formula (9) and expressed by the following formula (10). Formula 10: ψ^svardq=Lsvar[cos(2(θr−θr^))sin(2(θr−θr^))sin(2(θr−θr^))− cos(2(θr−θr^))]isdq

[0027] As shown in the above formula (10), the estimates Ψ ^ svarl dq of the flux linkage inductance variation components using the rotor position estimate θ^ r and the stator currents i s dq It should be noted here that the rotating machine 3A in the first embodiment is the rotating synchronous reluctance machine with the rotor 8, which has no magnets, thus not allowing the use of the rotor flux in the rotor position estimation. Therefore, another method that does not use the rotor flux is required to obtain the estimates Ψ ^ svar dq to accurately calculate the flux linkage inductance variation components.

[0028] The above formula (10) is simplified here to the following formula (11) when the rotor position estimate θ ^ r a true rotor position θ r , that is, θ^ r ≈θ r . Formula 11: ψ^svardq=Lsvar[100−1]isdq

[0029] If there are calculated values ​​that can be used as references for the estimates Ψ ^ svar dq of the flux linkage inductance variation components, the rotor position can be estimated by using the estimates Ψ ^ svar dq and the calculated reference values ​​are compared. Accordingly, an approach described below is proposed.

[0030] First, applying the transformation to a rotating reference system based on the rotor position estimate θ^ raccording to the above formula (5), which is a voltage equation, the following formula (12). Formula 12: vsdq=vsdq=Rsisdq+ddtψsdq+ω^rJψsdq

[0031] In the above formula (12) “ω ^ r " for an estimated rotational velocity and is referred to in this document as "rotational velocity estimation." The rotational velocity estimate ω^ r is calculated by the position estimator 6A as described below. In the above formula (12), "J" represents a transformation matrix expressed by the following formula (13). Formula 13: J=[0−110]

[0032] Rearranging the above formula (12) yields the following formula (14). Formula 14: ddtψsdq=vsdq−Rsisdq−ω^rJψsdq

[0033] Theoretically, flux linkages Ψs dq can be calculated by integrating the above formula (14); however, unknown initial values ​​pose a problem. Furthermore, since the response of formula (14) itself is oscillatory, an observer is often used for stable calculation. From this point of view, a flux observer that calculates the flux linkages Ψ s dq calculated, based on the above formula (14) to represent the following formula (15). Voltage drops due to the winding resistance R s in the second term of formula (14) can be ignored when the rotation speed of the rotating machine 3A is above a certain level. Formula 15: ddtψs,calcdq=vsdq−Rsisdq−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0034] In the above formula (15) “Ψ s,calc dq “ for calculated values ​​of the flux linkages Ψ s dqand “H” stands for the feedback gain of the flux observer. “Ψ s,obj dq “ stands for setpoints to which the calculated flux linkages Ψ s,calc dq should converge and are required for the flux observer to achieve convergence. The following formula (16), which is derived by taking differentials of the flux linkages Ψ s dq , that is, the left side of the above formula (14), which represents a voltage equation, is set to zero, can be used to calculate the setpoints Ψ s,obj dq be used. Formula 16: ψs,objdq=[vsq−Rsisqω^r−vsd−Rsisdω^r]

[0035] Since the setpoints Ψ s,opj dq are calculated based on the voltage equation, the setpoints Ψ s,obj dqreferred to here as “voltage-based setpoints”. For the purpose of designing the sensitivity of the flux observer, transforming the above formula (15) such that the calculated flux linkages Ψ s,calc dq become variables, the following formula (17). Formula 17: ddtψs,calcdq=vsdq−RsLsavg2−Lsvar2[Lsavg−Lsvar cos(2(θr−θ^r))−Lsvar sin(2(θr−θ^r))−Lsvar sin(2(θr−θ^r))Lsavg+Lsvar cos(2(θr−θ^r))]ψs,calcdq−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0036] Since the true rotor position θ r is unknown here, the approximation, θ r ≈θ ^ r , the following formula (18). Formula 18: ddtψs,calcdq=vsdq−[RsLsd00RsLsq]ψs,calcdq−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0037] Using the above formula (18) and setting the feedback gain H of the flux observer, for example, to the formula (19) below, allows the sensitivity of convergence to be defined as ω obs is designed. Formula 19: H=[−RsLsd+ωobsω^r−ω^r−RsLsq+ωobs]

[0038] A summary of the above description is as follows. First, the flux observer of the first embodiment is represented by formulas (15), (16), and (19). In formulas (15) and (16), the voltage drop R s i s dq due to the winding resistance R s be ignored if the rotation speed is above the specified level. The stator voltage command values ​​v s dq * are called stator voltages v s dqused. From the above points of view, the flux observer in the first embodiment is used to calculate the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the rotational velocity estimate ω ^ r and the most recent calculated flux linkages Ψ s,calc dq The term “most recent” refers to their proximity in time and can, for example, refer to their proximity to the current time. In other words, the “most recent calculated flux linkages Ψ s,calc dq “ the latest values ​​under already calculated flux linkages Ψ s,calc dq The same meaning is used in subsequent descriptions.

[0039] A more detailed calculation method is explained as follows. The flux observer of the first embodiment calculates the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . “The products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages W s , calc dq ,, correspond to the third term in the above formula (15). “The quotients of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω ^ r “ correspond to the above formula (16).

[0040] A more detailed calculation method is explained as follows. The flux observer of the first embodiment calculates the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq and differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . The “differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω ^ r” correspond to the fourth and fifth terms in the above formula (15).

[0041] A more detailed calculation method is explained as follows. The flux observer of the first embodiment calculates the flux linkages Ψ s,calc dq based on first differences between the stator voltage command values ​​v s dq * and the products of the rotational velocity estimate ω ^ r and the most recent calculated flux linkages Ψ s,calc dq and second differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . The first differences correspond to the first and third terms of the above formula (15) and the above-mentioned second differences correspond to the fourth and fifth terms of the above formula (15). It should be noted that the first differences are based on the differentials of the flux linkages Ψs , as shown in the above formula (14), while the second differences are based on stationary values ​​of the flux linkages Ψ s as shown in the above formula (15). In other words, the flux observer of the first embodiment calculates the flux linkages Ψ s based on both the differentials and the stationary values ​​of the flux linkages Ψ s . Unlike the flux observer of the above-mentioned Patent Literature 1, the flux observer of the first embodiment does not use flux linkages calculated using the stator currents and inductances.

[0042] The calculation methods for the flux linkages Ψ s,calc dqaccording to the first embodiment have been described above. However, the signs of the terms in the above formula (15), which forms the basis of the calculation methods, may vary depending on the polarities of the stator voltages v s , the stator currents i s and the flux linkages Ψ s be reversed. Furthermore, depending on how the flux observer is configured, various modifications of the above formula (16) are possible. An essential point of the flux observer in the first embodiment is that components responsible for calculating the flux linkages Ψ s,calc dq are essential, the stator voltage command values ​​v s dq *, the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq From this point of view, the calculated flux linkages Ψ s,calc dqin the first embodiment by calculating new flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq updated.

[0043] Calculated values ​​of the flux linkage inductance variation components are given by “Ψ svar,calc dq “ . The flux linkage inductance variation components Ψ svar,calc dq can be calculated using the following formula (20), where the flux linkages Ψ calculated by the flux observer s,calc dq be used. Formula 20: ψsvar,calcdq=ψs,calcdq−Lsavgisdq

[0044] The above formula (20) can be derived from the relationships given by formulas (9) and (10).

[0045] For the flux linkage inductance variation components, estimation errors can be calculated from the calculated flux linkage inductance variation components Ψ using the following formula (21). svar,calc dq , which are expressed by the above formula (20), and the estimates of the flux linkage inductance variation components Ψ ^ svar dq , which are expressed by the above formula (11). Formula 21: ψ^svardq×ψsvar,calcdq=|ψ^svardq||ψsvar,calcdq|sin(2(θr−θ^r))

[0046] The above formula (21) can be expressed as the following formula (22) when the rotor position estimate θ^ r the true rotor position θ r that is, in the above formula (21) θ^ r ≈θ r . Formula 22: −(θr−θ^r)=12ψ^svardq×ψsvar,calcdq|ψ^svardq||ψ^svar,calcdq|

[0047] The above formula (22) is a formula that calculates a rotor position estimation error {-(θ^ r -θ r )}. Fig. 2 illustrates a control method for converging this estimation error {-(θ^ r -θ r )} tends to zero. Fig. 2 is a diagram showing the control method for converging the rotor position estimation error {-(θ^ r -θ r )} towards zero in the first embodiment. In the first embodiment, the position estimator 6A follows the Fig. 2. As shown in Fig. 2, the estimation error {-(θ^ r -θ r )} in particular, only be subjected to PI control and then further integrated to converge to zero. In this process, an input to an integrator, that is, the output from the PI control, is the rotational speed estimate ω^ rand an output of the integrator is the rotor position estimate θ^ r .

[0048] Next, the approach of the first embodiment and the technique described in Patent Literature 1 are compared. In Patent Literature 1, as described above, values ​​calculated from the stator currents and inductances are used as setpoints in the flux observer. These setpoints are referred to as the "current-based setpoints" in this document and are denoted by "Ψ s,obj dq '“ As already mentioned, the approach of the first embodiment uses the voltage-based setpoints Ψ s,obj dq .

[0049] The current-based setpoints W used in Patent Literature 1 s,obj dq ' can be calculated using the following formula (23). The following formula (23) can be calculated using the approximation, θ^ r ≈θ r, in the above formula (9) and using the relationships given by the above formulas (7) and (8). Formula 23: ψs,objdq'=[Lsd00Lsq]isdq

[0050] If the variable inductance component L svar as used in the first embodiment for position estimation, the flux linkages Ψ s in the rotating reference system based on the rotor position estimate θ^ r which includes the estimation error. For this calculation, the voltage equation, which refers to the stator voltages v s dq is used, as shown in the above formula (14). By comparing the calculated values ​​with the estimates of the flux linkage inductance variation component Ψ ^ svar dq , which are the estimates obtained using the rotor position estimate θ^ rand the stator currents i s dq as calculated in formulas (10) and (11), the estimation error {-(θ^ r -θ r )} can be extracted.

[0051] Meanwhile, if the calculated flux linkages Ψ s against the current-based setpoints W s,obj dq ' converge, which consists of the stator currents i s dq can be calculated as shown in the above formula (23), assuming that the rotor position estimate θ^ r is true, the estimation error {-(θ^ r -θ r)} cannot be extracted. In particular, when the flux linkage inductance variation components are calculated using the above formula (20) by using the calculated values ​​from the above formula (23), the flux linkage inductance variation components become equal to the estimates from the above formula (11). This means that the error in the rotor position estimation θ^ r , as expressed in the second term of the above formula (9), and variations in the flux linkages Ψ s due to the variable inductance component L svar be ignored. However, if the flux observer is designed to have a slow response speed to effect convergence to the current-based setpoints W s,obj dq ', the flux linkages Ψ s , which are calculated based on the voltage equation, slowly approach the current-based setpoints Ψ s,objdq ', thereby mitigating the effects. Meanwhile, designing for the slow response speed causes the flux linkages Ψ s , calculated based on the voltage equation represented by the above formula (14), are oscillating. Therefore, the response speed of the flux observer must be at least a certain value. Thus, the design of the control using the flux observer interferes with the design of the position estimation control, which leads to a problem with the technique described in Patent Literature 1 and makes stable and highly sensitive rotor position estimation difficult.

[0052] In contrast, the approach of the first embodiment involves calculating the flux linkages Ψ s based on the voltage equation using the stator voltages v sand causing the calculated flux linkages Ψ s against the voltage-based setpoints Ψ s,obj dq , which are given by formula (16), converge. Therefore, the approach of the first embodiment enables highly sensitive and highly accurate rotor position estimation by calculating the flux linkage inductance variation components, where the calculation of the position estimation includes the calculation of the flux linkages Ψ s does not bother.

[0053] In addition to Patent Literature 1, for example, Japanese Patent Laid-Open No. 2006-288083 (hereinafter referred to as "Patent Literature 2") discloses another conventional technique. The technique described in Patent Literature 2 uses the voltage-based set values ​​Ψ s,obj dqdirectly for the position estimation calculation without using a flux observer. A problem with this technique is that the sole use of the stationary values ​​of the flux linkages Ψ s to a time-consuming convergence of the calculated flux linkages Ψ s and also leads to a slow response in position estimation.

[0054] In contrast, the approach of the first embodiment uses not only the stationary values ​​of the flux linkages Ψ s , but also the differentials of the flux linkages Ψ s for the calculation of the flux linkages Ψ s . Therefore, the approach of the first embodiment enables the rotor position estimation by the highly sensitive calculation of the flux linkages Ψ s .

[0055] Yet another conventional technique is shown, for example, in Japanese Patent Application Laid-Open No. 2018-183005 (hereinafter referred to as “Patent Literature 3”). The technique described in Patent Literature 3 involves calculating the flux linkages Ψ s based on the voltage equation in the two-phase reference system, which is the stationary reference system. Rearranging the above formula (5) yields the following formula (24) for the differentials of the flux linkages Ψ s . Formula 24: ddtψsαβ=vsαβ−Rsisαβ

[0056] Since the parameters of the rotating machine 3A in the stationary reference system are alternating current, their stationary values ​​are zero. Furthermore, if initial values ​​of the flux linkages Ψ s are set to zero, the flux linkages Ψ sbe calculated by integration. In this case, the technique described in Patent Literature 3 applies a high-pass filter such as the one shown in Formula (25) below to remove a DC component and low-frequency components. Formula 25: ddtψsαβ=vsαβ−Rsisαβ−ωhpfψsαβ

[0057] In the above formula (25) “ω hpf " for a cutoff angular frequency of the high-pass filter. The use of the high-pass filter in Patent Literature 3 solves the problem of initial values. Furthermore, the use of the high-pass filter limits the drift of the integral caused by disturbances and other factors. However, since the parameters of the rotating machine 3A are alternating current, high rotation speeds and high frequencies of the parameters of the rotating machine 3A result in fewer sampling points for the control calculation. As a result, oscillations occur during the integration of the flux linkages Ψs This problematically causes the rotor position estimation using integration to become unstable. Another problem with the technique described in Patent Literature 3 is that the use of the high-pass filter to remove the low-frequency components that should ideally be included in the calculated values ​​results in reduced response speed and reduced accuracy, especially during transient behavior.

[0058] In contrast, the approach of the first embodiment allows the calculation of the flux linkages Ψ s in the rotating reference system using the flux observer and the voltage-based setpoints Ψ s,obj dqSince the parameters of the rotating machine 3A in the rotating reference frame are DC, the problem of sampling points is mitigated even at high rotation speeds. In addition, the use of the flux observer allows the flux linkages Ψ s against the voltage-based setpoints Ψ s,obj dq converge, eliminating the need to remove low-frequency components. Therefore, the approach of the first embodiment enables rotor position estimation through the highly accurate, highly sensitive, and highly stable calculation of the flux linkages Ψ s .

[0059] As described above, the rotating machine control device according to the first embodiment includes the current detector that detects the stator currents flowing through the stator of the rotating machine, and the position estimator that calculates the rotor position estimate and the rotational speed estimate based on the calculated flux linkages of the rotating machine. The position estimator updates the calculated flux linkages based on the stator voltage command values, the rotational speed estimate, and the most recently calculated flux linkages. This makes it possible to estimate the rotor position with high sensitivity and high accuracy.

[0060] The approach of the first embodiment can utilize flux linkage inductance variation components when calculating flux linkages. The flux linkage inductance variation components are the flux components generated by the variable inductance component and the stator currents. When the inductance of the rotating machine is divided into the mean component, which does not vary with the rotor position, and the variable component, which varies at twice the electrical angular frequency at which the rotor position changes, the variable inductance component refers to the latter component. Using this variable inductance component in rotor position estimation enables highly sensitive and highly accurate rotor position estimation, a remarkable effect that cannot be observed conventionally. Second embodiment.

[0061] Fig. 3 is a diagram illustrating an exemplary configuration of a control device for a rotating machine according to a second embodiment. Compared with the Fig. 1, in the configuration of the second embodiment, the control device 1B replaces the control device 1A, and the rotating machine 3B replaces the rotating machine 3A. Furthermore, the control device 1B has a position estimator 6B that replaces the position estimator 6A. The configuration is otherwise identical or equivalent to that of Fig. 1 and identical or equivalent components have the same reference numerals. In the second embodiment, descriptions of details identical or equivalent to those in the first embodiment are omitted where appropriate.

[0062] The rotating machine 3B in the second embodiment is a rotating machine whose inductance includes a variable inductance component that varies with a rotor position, and whose rotor 8 includes magnets. An example of this type of rotating machine 3B is an interior permanent magnet motor in which magnets are embedded in the rotor 8. In the second embodiment, an N-pole direction of the magnets of the rotor 8 is defined as a d-axis. For the rotor position, the d-axis of the rotor 8 is used as a reference. A q-axis is located in a direction that is electrically 90° ahead of the d-axis in a rotational direction. As in the first embodiment, both the inverter circuit and the rotating machine 3B are configured to be three-phase.

[0063] Next, a description will be provided of how the position estimator 6B estimates the rotor position, that is, the rotor position estimate θ^ r First, a model of the rotating machine 3B in a two-phase reference system is expressed by the following formulas (26) and (27). Formula 26: vsαβ=Rsisαβ+ddtψsαβ Formula 27: ψsαβ=[Lsavg+Lsvar cos(2θr)Lsvar sin(2θr)Lsvar sin(2θr)Lsavg+Lsvar cos(2θr)]isαβ+[cos θrsin θr]ψm

[0064] In the above formula (27) “Ψ m " for the flux linkage generated by the permanent magnets and is referred to in this document as "magnetic flux." The transformation into a rotating reference system of the flux linkages Ψ s αβ from the above formula (27) based on the rotor position estimate θ^ r gives the following formula (28). Formula 28: ψsdq=Lsavgisdq+Lsvar[cos(2(θr−θ^r))sin(2(θr−θ^r))sin(2(θr−θ^r))− cos(2(θr−θ^r))]isdq+[cos(θr−θ^r)sin(θr−θ^r)]ψm︸ψmdq

[0065] "Ψ m dq " in the third term of the above formula (28) stands for components of the magnetic flux Ψ m in a two-phase rotating reference system. In the above formula (28), the first term refers to the average inductance component L savg the inductance, which does not vary with the rotor position, and the second term refers to the variable inductance component L svar the inductance, which varies at twice the electrical angular frequency with which the rotor position changes. In the second embodiment, the q-axis component of the magnetic flux Ψ m , which is described in the third term, is used for rotor position estimation.

[0066] For reasons of safety, environmental protection, and cost, rotating machines with small magnetic flux and high reluctance torque (i.e., a large variable inductance component) have begun to gain ground in newer products, such as those for automobiles. Therefore, flux linkages based on the variable inductance component L svar , as described in the second term, must be accurately calculated for an accurate calculation of the magnetic flux in the third term.

[0067] Next, a description is provided of how the flux linkages are calculated in the second embodiment. First, applying the transformation to a rotating reference frame based on the rotor position estimate θ^ r according to the above formula (26), which is a voltage equation, followed by a rearrangement, the following formula (29). Formula 29: ddtψsdq=vsdq−Rsisdq−ω^rJψsdq

[0068] Theoretically, flux linkages Ψ s dq can be calculated by integrating the above formula (29); however, unknown initial values ​​pose a problem. Furthermore, since the response of formula (29) itself is oscillatory, an observer is often used for stable calculation. From this point of view, a flux observer that calculates the flux linkages Ψ s dq calculated, based on the above formula (29) to represent the following formula (30). Voltage drops due to the winding resistance R s in the second term of formula (29) can be ignored when a rotation speed of the rotating machine 3B is above a certain level. Formula 30: ddtψs,calcdq=vsdq−Rsisdq−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0069] The following formula (31), which is derived by taking differentials of the flux linkages Ψ s dq , that is, the left side of the above formula (29), which represents a voltage equation, is set to zero, can be used here for the calculation of the setpoints Ψ s,obj dq be used. Formula 31: ψs,objdq=[vsq−Rsisqω^r−vsd−Rsisdω^r]

[0070] Since the setpoints Ψ s,obj dq are calculated based on the voltage equation, the setpoints Ψ s,obj dq in the second embodiment also referred to as “voltage-based setpoints”. For the purpose of designing the sensitivity of the flux observer, transforming the above formula (30) such that the calculated flux linkages Ψ s,calc dq become variables, the following formula (32). Formula 32: ddtψs,calcdq=vsdq−RsLsavg2−Lsvar2[Lsavg−Lsvar cos(2(θr−θ^r))−Lsvar sin(2(θr−θ^r))−Lsvar sin(2(θr−θ^r))Lsavg−Lsvar cos(2(θr−θ^r))](ψs,calcdq−ψsindq)−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0071] Since the true rotor position θ r is unknown here, the approximation, θ r ≈θ ^ r , the following formula (33). Formula 33: ddtψs,calcdq=vsdq−[RsLsd00RsLsq]ψs,calcdq+[RsLsd00RsLsq]

[10] ψm−ω^rJψs,calcdq−H(ψs,calcdq−ψs,objdq)

[0072] Using the above formula (33) and setting the feedback gain H of the flux observer, for example, to the formula (34) below, allows the sensitivity of convergence to be defined as ω obs is designed. Formula 34: H=[−RsLsd+ωobs−ω^r−ω^r−RsLsq+ωobs]

[0073] A summary of the above description is as follows. First, the flux observer of the second embodiment is represented by formulas (30), (31), and (34). In formulas (30) and (31), the voltage drop R s i s dq due to the winding resistance R s be ignored if the rotation speed is above the specified level. The stator voltage command values ​​v s dq * are considered as the stator voltages v s dq used. From the above points of view, the flux observer in the second embodiment is used to calculate the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq to calculate.

[0074] A more detailed calculation method is explained as follows. The flux observer of the second embodiment calculates the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . “The products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq ” correspond to the third term in the above formula (30). “The quotients of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω ^ r ” correspond to the above formula (31).

[0075] A more detailed calculation method is explained as follows. The flux observer of the second embodiment calculates the flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq and differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . The “differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r “ correspond to the fourth and fifth terms in the above formula (30).

[0076] A more detailed calculation method is explained as follows. The flux observer of the second embodiment calculates the flux linkages Ψ s,calc dq based on first differences between the stator voltage command values ​​v s dq * and the products of the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq and second differences between the most recent calculated flux linkages Ψ s,calc dq and the quotient of the stator voltage command values ​​v s dq * by the rotational velocity estimate ω^ r . The first differences correspond to the first and third terms of the above formula (30) and the second differences correspond to the fourth and fifth terms of the above formula (30). It should be noted that the first differences are based on the differentials of the flux linkages Ψ s, as shown in the above formula (29), while the second differences are based on stationary values ​​of the flux linkages Ψ s as shown in the above formula (30). In other words, the flux observer of the second embodiment calculates the flux linkages Ψ s based on both the differentials and the stationary values ​​of the flux linkages Ψ s . Unlike the flux observer of the above-mentioned Patent Literature 1, the flux observer of the second embodiment does not use the flux linkages calculated using the stator currents and the inductances.

[0077] The calculation methods for the flux linkages Ψ s,calc dqaccording to the second embodiment have been described above. However, the signs of the terms in the above formula (30), which forms the basis of the calculation methods, may vary depending on the polarities of the stator voltages v s , the stator currents i s and the flux linkages Ψ s be reversed. Furthermore, depending on how the flux observer is configured, various modifications of the above formula (16) are possible. An essential point of the flux observer in the first embodiment is that components responsible for calculating the flux linkages Ψ s,calc dq are essential, the stator voltage command values ​​v s dq *, the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq From this point of view, the calculated flux linkages Ψ s,calc dqin the second embodiment by calculating new flux linkages Ψ s,calc dq based on the stator voltage command values ​​v s dq *, the rotational velocity estimate ω^ r and the most recent calculated flux linkages Ψ s,calc dq updated.

[0078] A calculated value of the q-axis component of the magnetic flux Ψ m dq , which is described in the third term of the above formula (28), is given by “Ψ mq,calc “ This value Ψ mq,calc can be calculated using the following formula (35), where the flux linkage Ψ calculated by the flux observer sq,calc is used. Formula 35: ψmq,calc=ψsq,calc−Lsqisq

[0079] The above formula (35) can be approximated by, θ^ r ≈θ r, in the above formula (28) and the relationships given by formulas (9) and (10).

[0080] The q-axis component in the third term of the above formula (28) corresponds to the calculated q-axis component Ψ mq,calc on the left side of the above formula (35) and can therefore be expressed by the following formula (36). Formula 36: ψm sin(θr−θ^r)=ψmq,calc

[0081] The use of the relationship, θ^ r ≈θ r , in the above formula (36) enables the above formula (36) to be expressed as the following formula (37). Formula 37: −(θ^r−θr)=ψmq,calcψm

[0082] The above formula (37) is a formula that calculates a rotor position estimation error {-(θ^ r -θ r )}. As in the first embodiment, the estimation error {{-(θ^ r -θ r)} is subjected to PI control and then integrated to converge to zero. This allows the rotor position to be estimated. In this case, too, one input to an integrator is the rotational speed estimate ω ^ r and an output of the integrator is the rotor position estimate θ ^ r .

[0083] Next, the approach of the second embodiment and the technique described in Patent Literature 1 are compared. When the technique described in Patent Literature 1 is applied to the second embodiment, the current-based setpoints W used in Patent Literature 1 can be s,obj dq ' can be expressed by the following formula (38). Formula 38: ψs,objdq'=[Lsd00Lsq]isdq+

[10] ψm

[0084] However, if the calculated flux linkages Ψ s against the current-based setpoints W s,obj dq' converge, which consists of the stator currents i s dq can be calculated as shown in the above formula (38), assuming that the rotor position estimate θ^ r is true, the q-axis component of the magnetic flux Ψ m , which is shown in the third term of the above formula (28) and which is used for position estimation, is not extracted. Furthermore, the error in the rotor position estimation θ^ r , as expressed in the second term of the above formula (28), and variations in the flux linkages Ψ s due to the variable inductance component L svar ignored. The effects are particularly noticeable for rotating machines with small magnetic flux Ψ m and a large variable inductance component L svarsignificant. Even the use of the measure to adjust the sensitivity of the flux observer, as described in the first embodiment, leads to a complexity in which the control design using the flux observer interferes with the control design of the position estimation, making stable and highly sensitive rotor position estimation difficult.

[0085] In contrast, the approach of the second embodiment involves calculating the flux linkages Ψ s based on the voltage equation using the stator voltages v s and causing the calculated flux linkages Ψ s against the voltage-based setpoints Ψ s,obj dq, which are given by formula (31), converge. Therefore, the approach of the second embodiment enables highly sensitive and highly accurate rotor position estimation by calculating the flux linkage inductance variation components, where the calculation of the position estimation includes the calculation of the flux linkages Ψ s does not bother.

[0086] As described in the first embodiment, the technique described in Patent Literature 2 uses what is referred to in this document as voltage-based setpoints Ψ s,obj dq directly for the position estimation calculation without using a flux observer. A problem with this technique is that the sole use of the stationary values ​​of the flux linkages Ψ s to a time-consuming convergence of the calculated flux linkages Ψ s and also leads to a slow response in position estimation.

[0087] In contrast, the approach of the second embodiment uses not only the stationary values ​​of the flux linkages Ψ s , but also the differentials of the flux linkages Ψ s for the calculation of the flux linkages Ψ s . Therefore, the approach of the second embodiment enables the rotor position estimation by the highly sensitive calculation of the flux linkages Ψ s .

[0088] As described above, even when the rotating machine includes permanent magnets, the position estimator included in the rotating machine control device according to the second embodiment updates the calculated flux linkages based on the stator voltage command values, the rotation speed estimate, and the most recently calculated flux linkages. This enables the rotor position to be estimated with high sensitivity and high accuracy even when the magnetic flux of the rotating machine is used for the rotor position estimation.

[0089] The functions of each of the rotating machine control devices 1A and 1B described in the first and second embodiments can be implemented with one processing circuit. The functions of the control device 1A or 1B relate to the functions of the control unit 5 and the position estimator 6A or 6B.

[0090] Fig. 4 is a diagram illustrating a first exemplary hardware configuration of the rotating machine control device according to each of the first and second embodiments. Fig. 5 is a diagram illustrating a second exemplary hardware configuration of the control device for the rotating machine according to each of the first and second embodiments. Fig. 4 and Fig. The rotating machine 3 illustrated in Figure 5 refers to either the rotating machine 3A described in the first embodiment or the rotating machine 3B described in the second embodiment. The processing circuit may be dedicated hardware, such as the one shown in Fig. 4 illustrated dedicated processing circuit 10, or can, as in Fig. 5, include a processor 11 and a memory 12 that stores programs that operate the processor 11.

[0091] The dedicated processing circuit 10, used as the dedicated hardware, corresponds to a single circuit, a compound circuit, a programmed processor, a programmed parallel processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of these. The functions of each of the control devices 1A and 1B can be implemented individually or jointly with the processing circuit.

[0092] When the processor 11 and the memory 12 are used, the functions of each of the control devices 1A and 1B are implemented using software, firmware, or a combination thereof. The software or firmware are described as programs and are stored in the memory 12. The processor 11 reads and executes the programs stored in the memory 12. These programs can be said to cause a computer to perform the steps and procedures performed by the processor 11. The memory 12 corresponds to a semiconductor memory, such as a random-access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) (registered trademark). The semiconductor memory can be either a non-volatile memory or a volatile memory.In addition to the semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a digital versatile disk (DVD), or another option may be used as the memory 12. The functions of each of the control devices 1A and 1B can be implemented partly with hardware and partly with software or firmware.

[0093] The voltage application unit 2 described in this document includes the three-phase inverter circuit. However, the voltage application unit 2 may include an inverter with a different number of phases. The voltage application unit 2 to be used may be any of various voltage application units including multi-level inverters, such as a three-level inverter and a five-level inverter.

[0094] While the stator currents i sfor the torque of each of the rotating machines 3A and 3B are set to minimize the root mean square of the current, the stator currents i s be adjusted to minimize flux linkages or maximize the efficiency of the voltage application unit 2 or each rotating machine 3A or 3B.

[0095] The above configurations illustrated in the embodiments are illustrative, may be combined with other well-known techniques, and may be partially omitted or changed without departing from the gist. List of reference symbols

[0096] 1A, 1B control device; 2 voltage application unit; 3, 3A, 3B rotating machine; 4 current detector; 5 control unit; 6A, 6B position estimator; 7 stator; 8 rotor; 10 dedicated processing circuit; 11 processor; 12 memory; 501 current command calculation unit; 502 three-phase to two-phase transformation unit; 503 rotating reference frame transformation unit; 504 dq current control unit; 505 rotating reference frame inverse transformation unit; 506 two-phase to three-phase transformation unit. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2009-095135

[0004] JP 2006-288083

[0053] JP 2018

[0055] JP 183005

[0055]

Claims

[1] A control device for a rotating machine, the control device comprising: a current detector for detecting stator currents flowing through a stator of the rotating machine; a position estimator for calculating a rotor position estimate and a rotational speed estimate based on calculated flux linkages of the rotating machine, wherein the rotor position estimate is an estimated position of a rotor of the rotating machine, wherein the rotational speed estimate is an estimated speed; a control unit for outputting stator voltage command values ​​based on the stator currents and the rotor position estimate for driving the rotating machine; and a voltage application unit for applying drive voltages to the rotating machine based on the stator voltage command values, wherein the position estimator updates the calculated flux linkages based on the stator voltage command values, the rotation speed estimate, and the most recent calculated flux linkages. [2] A control device for the rotating machine according to claim 1, wherein the position estimator updates the calculated flux linkages based on the stator voltage command values, products of the rotation speed estimate and the calculated flux linkages, which are the most recent, and quotients of the stator voltage command values ​​by the rotation speed estimate. [3] A control device for the rotating machine according to claim 1 or 2, wherein the position estimator updates the calculated flux linkages based on the stator voltage command values, the products of the rotation speed estimate and the most recent calculated flux linkages, and differences between the most recent calculated flux linkages and the quotients of the stator voltage command values ​​by the rotation speed estimate. [4] The control device for the rotating machine according to any one of claims 1 to 3, wherein the position estimating means updates the calculated flux linkages based on first differences between the stator voltage command values ​​and the products of the rotation speed estimation and the calculated flux linkages which are the most recent, and second differences between the calculated flux linkages which are the most recent and the quotient of the stator voltage command values ​​by the rotation speed estimation. [5] The rotating machine control device according to any one of claims 1 to 4, wherein the inductance of the rotating machine includes a variable inductance component that varies with a rotor position, the rotor position being a rotational position of the rotor. [6] The rotating machine control device according to claim 5, wherein the rotor of the rotating machine is permanent magnet-free. [7] A control device for the rotating machine according to claim 5, wherein the rotor of the rotating machine includes a permanent magnet. [8] A control device for the rotating machine according to any one of claims 5 to 7, wherein the position estimator estimates the rotor position based on flux linkage inductance variation components included in flux linkages of the rotating machine and generated by the variable inductance component and the stator currents. [9] A control device for the rotating machine according to claim 8, wherein the inductance of the rotating machine is divided into a mean component that does not vary with the rotor position and a variable component that varies at twice the electrical angular frequency with which the rotor position changes, and the flux linkage inductance variation components are magnetic fluxes generated by the stator currents and the variable component.

Images