LATHE CONTROL DEVICE

Abstract

A control device (100) comprises: a current sensing unit (2) that detects a lathe current flowing through a lathe (1); a position estimation unit (4) that calculates an estimated value of a rotor position, which is position information of a rotor (1b), based on the lathe current; a current control unit (5) that generates a first voltage command, which is a command value of a lathe voltage for controlling the lathe (1), based on a detected value of the lathe current and an estimated value of the rotor position;a position estimation voltage generation unit (30) that generates a high-frequency voltage having a frequency higher than the first voltage command, wherein the high-frequency voltage is a position estimation voltage for estimating the rotor position based on a torque-shaft current command which is a physical quantity correlated with a magnetic saturation of the rotor (1b); and a voltage application device (3) that applies a control voltage to the lathe (1) based on a second voltage command in which the position estimation voltage is superimposed on the first voltage command.

Description

Area

[0001] The present disclosure relates to a lathe control device that performs control by obtaining rotor position information without using a position sensor that detects a rotor position. background

[0002] To control a lathe while utilizing the lathe's power, rotor position information is required. Therefore, a lathe has been controlled using position information acquired by a position sensor mounted on the lathe. On the other hand, in recent years, a method for performing position sensorless control of a lathe has been developed from the perspective of further reducing the manufacturing cost of the lathe, reducing the size of the lathe, and improving the reliability of the lathe.

[0003] In position sensorless control of a lathe, a method of estimating a lathe rotor position from an induced voltage of the lathe depending on a speed range and a method of estimating a lathe rotor position using saliency are used, in combination or separately. The former is used in a high-speed range in which an induced voltage necessary for position estimation can be sufficiently obtained, and the latter is used in a low-speed range in which a sufficient induced voltage cannot be obtained.

[0004] As for the latter, for example, Patent Literature 1 below discloses, as a conventional method for estimating a rotor position of a rotating machine using salience, a method in which a high-frequency voltage having a frequency higher than a fundamental frequency is superimposed on a control voltage, and the superimposed voltage is applied to a rotating machine. More specifically, in Patent Literature 1, a high-frequency current vector having an elliptic locus is separated into a positive-phase current vector and a mirror-phase current vector, and an intermediate angle between the two vectors is calculated, thereby detecting a rotor position. Citation listPatent literature

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2002-171799 Summary of the inventionProblem to be solved by the invention

[0006] However, even if the method of Patent Literature 1 is used in a case where a salience ratio of the rotary machine is structurally small, the locus of the high-frequency current vector does not have a clear elliptic shape depending on a rotary machine current, and thus there remains a problem that a detection accuracy of the rotor position decreases.

[0007] The present disclosure has been made in view of the above, and an object thereof is to provide a lathe control device capable of reducing a decrease in detection accuracy of a rotor position even in a case where a salience ratio of a lathe is structurally small. Means of solving the problem

[0008] To solve the above-described problem and achieve the object, a rotating machine control device according to the present disclosure includes a current detection unit, a position estimation unit, a current control unit, a position estimation voltage generation unit, and a voltage application unit. The current detection unit detects a rotating machine current flowing through a rotating machine. The position estimation unit calculates an estimated value of a rotor position, which is position information of a rotor of the rotating machine, based on the rotating machine current. The current control unit generates a first voltage command, which is a command value of a rotating machine voltage, for driving the rotating machine based on a detected value of the rotating machine current and an estimated value of the rotor position.The position estimation voltage generation unit generates a high-frequency voltage having a frequency higher than a first voltage command, the high-frequency voltage being a position estimation voltage for estimating the rotor position based on a physical quantity correlated with a magnetic saturation of the rotor. The voltage application device applies a control voltage to the

[0009] lathe based on a second voltage command in which the position estimation voltage is superimposed on the first voltage command. Effect of the invention

[0010] The lathe control device according to the present disclosure achieves an effect that it is possible to reduce a decrease in detection accuracy of a rotor position even in a case where a salience ratio of a lathe is structurally small. Short description of the drawings Fig. 1 is a diagram illustrating an exemplary configuration of a lathe control device according to a first embodiment. Fig. Figure 2 is a diagram illustrating examples of waveforms of high frequency voltages output from a position estimation voltage generating unit in Fig. 1 will be issued. Fig. 3 is a cross-sectional view used to explain a structure of a rotor core in a reluctance rotary machine adopted in the first embodiment. Fig. Figure 4 is a diagram illustrating an inductance change in a general reluctance lathe. Fig. Figure 5 is a diagram illustrating examples of current vector loci when a high-frequency current flows through a rotating machine having the Fig. 3 illustrated rotor core. Fig. Figure 6 shows a diagram that is used in the Fig. 3 illustrates a flow of a magnetic flux generated by a component of a high-frequency current when a component of a fundamental current is small. Fig. 7 is a diagram illustrating an example of a coefficient value table used in high-frequency boost control according to the first embodiment. Fig. 8 is a first diagram for explaining an effect of high frequency gain control according to the first embodiment. Fig. 9 is a second diagram for explaining the effect of the high frequency gain control according to the first embodiment. Fig. 10 is a diagram illustrating an exemplary configuration of a lathe control device according to a second embodiment. Fig. 11 is a diagram illustrating a first exemplary hardware configuration that realizes functions of the control devices according to the first embodiment and the second embodiment. Fig. 12 is a diagram illustrating a second exemplary hardware configuration that realizes the functions of the control devices according to the first embodiment and the second embodiment. Description of embodiments

[0011] Hereinafter, a lathe control device according to each embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. First embodiment.

[0012] Fig. Figure 1 is a diagram illustrating an exemplary configuration of a lathe control device (hereinafter, appropriately abbreviated as "control device") 100 according to a first embodiment. The control device 100 according to the first embodiment includes a current detection unit 2, a voltage application unit 3, a position estimation unit 4, a current control unit 5, a DC power supply 12, and a position estimation voltage generation unit 30. Fig. 1, the current control unit 5 is a control device of a current control system, and the position estimation unit 4 and the position estimation voltage generation unit 30 are control devices of a rotor position estimation system.

[0013] A lathe 1 is a device controlled by the control device 100. The lathe 1 includes a stator 1a and a rotor 1b arranged inside the stator 1a. In this description, a reluctance lathe is assumed as an example of the lathe 1, but it is not limited thereto. The lathe 1 could, for example, be a lathe with an internal permanent magnet.

[0014] The DC power supply 12 supplies a DC power to the voltage applying device 3. In a case where the rotary machine 1 is a motor, the voltage applying device 3 generates an AC voltage for driving the motor using a DC voltage V to be applied. dc and applies the generated alternating current voltage to the motor.

[0015] The current detection unit 2 detects rotary machine currents i u , i v and i w, which flow between the voltage application device 3 and the lathe 1. The lathe currents i u , i v and i w are stator currents flowing through each phase of the stator 1a, i.e. a u-phase, a v-phase and a w-phase.

[0016] A current detector is arranged in each phase of the current detection unit 2. An example of the current detector is a current transformer. In Fig. 1, the current detection unit 2 detects all currents in three phases, but there is no limitation to this. Currents of any two of the three phases could be detected, and a current of the remaining one phase could be obtained by calculation using the fact that the rotating machine currents i u , i v and i w in a three-phase equilibrium. Alternatively, instead of using the current detection unit 2 in Fig. 1, a bus current flowing through a DC bus connecting the voltage applying device 3 and the DC power supply 12 are detected and the rotary machine currents i u , i v and i w could be obtained by calculating the bus current.

[0017] The position estimation unit 4 calculates an estimated value θ L a rotor position, which is position information of the rotor 1b, based on the rotary machine currents i u , i v and i w . The current control unit 5 generates first voltage commands V u *, V v * and V w *, which are the command values ​​of lathe voltages for controlling the lathe 1, based on recorded values ​​of the lathe currents i u , i v and i w and the estimated value θ Lthe rotor position. The position estimation voltage generation unit 30 generates high-frequency voltages V uh , V vh and V wh , which have higher frequencies than the first voltage commands V u *, V v * and V w * based on a q-axis current command i q *. The high-frequency voltages V uh , V vh and V wh are position estimation voltages for estimating the rotor position. The current control unit 5 superimposes the first voltage commands V u *, V v * and V w * the high frequency voltages V uh , V vh and V wh and outputs the superimposed voltages to the voltage application device 3 as second voltage commands V up *, V vp * and V wp * The voltage application device 3 generates drive or control voltages based on the second voltage commands V up *, V vp * and V wp* and applies the control voltages to the lathe 1. In this description, the voltage application device 3 is assumed to be a three-phase inverter with two levels, but it is not limited to this. In this description, the voltage application device 3 could be a three-phase inverter with three levels, or it could be a multiphase inverter with two levels or three levels.

[0018] The current control unit 5 comprises subtractors 13d and 13q, a d-axis current control means 14d, a q-axis current control means 14q, a first coordinate converter 15, a two-phase to three-phase converter 16, a second coordinate converter 17, a three-phase to two-phase converter 18, and adding means 23u, 23v, and 23w.

[0019] The subtractor 13d calculates a deviation Δi d between a d-axis current command i d * and a d-axis current i d, which is output from the second coordinate converter 17. The d-axis current control device 14d of the next stage performs proportional integral control so that the deviation Δi d becomes zero, and thereby a d-axis voltage command V d * calculated. The subtractor 13q calculates a deviation Δi q between the q-axis current command i q * and a q-axis current i q , which is output from the second coordinate converter 17. The q-axis current controller 14q of the next stage performs proportional integral control so that the deviation Δi q becomes zero, and thereby a q-axis voltage command V q * calculated. The d-axis current command i d * is a command value of the d-axis current for driving the lathe 1, and the q-axis current command i q * is a command value of the q-axis current for driving the lathe 1. Both the d-axis current command id * as well as the q-axis current command i q * are provided from outside the power control unit 5.

[0020] The first coordinate converter 15 converts the d-axis voltage command V d * or the q-axis voltage command V q *, which are output by the d-axis current control device 14d and the q-axis current control device 14q, respectively, into voltage commands V α * and V β * on static biaxial coordinates. The two-phase to three-phase converter 16 converts the voltage commands V α * and V β *, which are output by the first coordinate converter 15, into first voltage commands V u *, V v * and V w *, which are the drive voltage commands of three-phase AC coordinates. The estimated value θ L the rotor position output from the position estimation unit 4 is used for an operation of the first coordinate converter 15.

[0021] The three-phase-two-phase converter 18 converts the rotary machine currents i u , i v , and i w , which are detected by the current detection unit 2, into an α-axis current i α and into a β-axis current i β on the static biaxial coordinates. The second coordinate converter 17 converts the α-axis current i α and the β-axis current i β output from the three-phase to two-phase converter 18 into the d-axis current i d and the q-axis current i q on rotation coordinates that are synchronous with the estimated value θ L the rotor position output from the position estimation unit 4 and outputs the d-axis current i d or the q-axis current i q to the subtraction devices 13d and 13q.

[0022] The first voltage commands V u *, V v * and V w* output from the two-phase to three-phase converter 16 and the high-frequency voltages V uh , V vh and V wh , which are output from the position estimation voltage generation unit 30, are added by the adders 23u, 23v, and 23w, respectively. Respective outputs of the adders 23u, 23v, and 23w are applied to the voltage application device 3 as the second voltage commands V up *, V vp * and V wp * is applied. Therefore, in the second voltage commands V up *, V vp * and V wp *, which are to be applied to the voltage application device 3, the high-frequency voltages V uh , V vh and V wh , which are position estimation voltage commands, the first voltage commands V u *, V v * and V w * superimposed. Details of the high-frequency voltages V uh , V vh and V wh will be described later.

[0023] The position estimation unit 4 comprises current extracting means 6u, 6v and 6w, a high-frequency current amplitude calculating unit 7 and a position calculating means 8. As described above, in the second voltage commands V up *, V vp * and V wp *, which are to be applied to the voltage application device 3, the high-frequency voltages V uh , V vh and V wh , which are output from the position estimation voltage generation unit 30, the first voltage commands V u *, V v * and V w * output from the two-phase to three-phase converter 16. Therefore, the rotary machine currents i u , i v and i w , which are detected by the current detection unit 2, high-frequency currents i uh , i vh and i wh , which have the same frequency components as the high-frequency voltages V uh , V vh and Vwh have.

[0024] Therefore, the current extractors 6u, 6v and 6w extract the high frequency currents i uh , i vh and i wh , which have the same frequency components as the high-frequency voltages V uh , V vh and V wh from the lathe currents i u , i v and i w , which are detected by the current detection unit 2. A bandpass filter or a notch filter could be used to extract the high-frequency currents i uh , i vh and i wh In a case where the notch filter is used, the lathe currents i u , i v and i w entered into the notch filter to obtain the same frequency components as those in the high frequency voltages V uh , V vh and V whto weaken or dampen. Then, after passing through the notch filter, the respective currents are separated from the lathe currents i u , i v and i w subtracted, and thus the high-frequency currents i uh , i vh and i wh be extracted.

[0025] The high-frequency current amplitude calculation unit 7 includes multipliers 9u, 9v, and 9w, integrators 10u, 10v, and 10w, and square root calculation devices 22u, 22v, and 22w. These components are provided for respective phases, respectively.

[0026] In the multipliers 9u, 9v and 9w, autocorrection values ​​are calculated by squaring the high frequency currents i uh , i vh and i whobtained. In each of the integrators 10u, 10v, and 10w, an integration operation is performed at a time Tn of an integration period, and an integral value thereof is multiplied by (2 / Tn), and the result is output. In the square root calculating means 22u, 22v, and 22w, square roots of the respective outputs of the integrators 10u, 10v, and 10w are calculated, thereby obtaining position estimation current amplitudes I uh , I vh and I wh receive.

[0027] In the high frequency current amplitude calculation unit 7 in Fig. 1 position estimation current amplitudes I uh , I vh and I wh by integrating the autocorrection values ​​of the high-frequency currents i uh , i vh and i wh and by calculating their square roots, although there is no limitation. The position estimation current amplitudes I uh , I vh and I whcould be obtained by adjusting the autocorrection values ​​of the high frequency currents i uh , i vh and i wh pass through a low-pass filter.

[0028] The position calculation device 8 calculates the estimated value θ L the rotor position based on the position estimation current amplitudes I uh , I vh and I wh , which are calculated by the high-frequency current amplitude calculation unit 7. A known method is used to calculate the estimated value θ L The rotor position is used, and a detailed description thereof will be omitted here. Note that a specific calculation procedure is disclosed, for example, in Japanese Patent No. 5324646, the publication of which is incorporated by reference.

[0029] Next, the high frequency voltages V uh , V vh and V whwhich are output from the position estimation voltage generation unit 30. Fig. Figure 2 is a diagram showing examples of waveforms of high frequency voltages V uh , V vh and V wh illustrated, which comes from the position estimation voltage generation unit 30 in Fig. 1. It can be seen that waveforms in Fig. 2 Examples are in a case where the voltage applying device 3 comprises a triangular wave comparing pulse width modulation (PWM) inverter.

[0030] The horizontal axis in Fig. 2 represents time. It also illustrates Fig. 2, from top to bottom, waveforms of a triangular carrier, the high-frequency voltage V uh the u-phase, the high-frequency voltage V vh the v-phase and the high-frequency voltage V whthe w-phase. If half a period Tc of the triangular carrier is defined as one section, one period Th of each of the high-frequency voltages V uh , V vh and V wh a signal in which one period comprises six sections (=6 ·Tc). In the examples in Fig. 2 are the high frequency voltages V uh , V vh and V wh adjusted to be offset by two sections (=2 ·Tc), each between the respective phases, to achieve three-phase equilibrium. It can be seen that Fig. 2 examples and that there is no limitation to the examples. Any waveform could be used as long as the high-frequency voltages V uh , V vh and V wh have waveforms that are in three-phase equilibrium.

[0031] Returning to Fig. 1, the position estimation voltage generation unit 30 will be described. The position estimation voltage generation unit 30 includes a high-frequency amplitude calculator 31 and a high-frequency voltage generator 32. The high-frequency amplitude calculator 31 receives an input of information about the q-axis current command i q *. The high-frequency amplitude calculation device 31 selects from a coefficient value W h based on the q-axis current command i q * or calculate it. The coefficient value W h is a positive real value that is set to detect voltage amplitudes of the high frequency voltages V uh , V vh and V wh A table in which the coefficient value W h can be used to determine the coefficient value W h Alternatively, the coefficient value W hcan be calculated by a function calculation without using the table.

[0032] In addition, the q-axis current command i q * an example of a physical quantity that correlates with a magnetic saturation of the rotor 1b. Any physical quantity that differs from the q-axis current command i q * could be used as long as the physical quantity correlates with the magnetic saturation of the rotor 1b. Other examples of the physical quantity that correlates with the magnetic saturation of the rotor 1b include the q-axis current i q and the q-axis voltage command V q *. The d-axis current command i d *, the d-axis current i d , the d-axis voltage command V d * and the like may also be physical quantities that correlate with the magnetic saturation of the rotor 1b.

[0033] The high-frequency voltage generator 32 generates the high-frequency voltages V uh , V vh and V wh described above, using the coefficient value W h . Operation of the high frequency voltage generator 32 will be described using the following several formulas.

[0034] When describing the operation of the high-frequency voltage generator 32, a formula representing a high-frequency current will be derived. First, a voltage equation of the rotating machine 1 on the αβ axes, which are static coordinates, is expressed by the following formula (1). Formula 1: [VαVβ]=[R+pLαpLαβpLαβR+plβ][iαiβ]+ωKε[−sin θcos θ]Lα=L0+L1cos(2θ)Lβ=L0−L1cos(2θ)Lαβ=L1sin(2θ)L0=Ld+Lq2L1=Ld−Lq2

[0035] In formula (1) above, i α and i β the α-axis current and the β-axis current, which are described above. V α and V βrepresent an α-axis stress and a β-axis stress, respectively. R and K E represent a stator resistance and an induced voltage coefficient, respectively. L α , L β , L αβ , L d and L q represent an α-axis inductance, a β-axis inductance, a mutual inductance between the αβ axes, a d-axis inductance, and a q-axis inductance, respectively. L0 is defined by the fifth formula of formula (1) above, and L1 is defined by a sixth formula of formula (1) above. p denotes a differential operator.

[0036] Formula (1) above is applicable in a case where the rotating machine 1 is a reluctance synchronous machine. In a case where the rotating machine 1 is a reluctance synchronous machine that does not include a magnet, the induced voltage coefficient K E in formula (1) above is zero, so that a second term of formula (1) above, which represents the induced stress coefficient KE can be omitted. In addition, if only high-frequency components are considered in the formula (1) above, the following formula (2) is obtained. Formula 2: [VαhVβh]=p[LαLαβLαβLβ][iαhiβh]

[0037] In formula (2) above, V αh , V βh , i αh and i βh High-frequency components of the α-axis voltage, β-axis voltage, α-axis current, and β-axis current, respectively. It should be noted that, regarding the transformation of formula (1) above into formula (2) above, a similar formula can be obtained for a synchronous reluctance motor that does not use magnets. Therefore, it is unnecessary to note that formula (2) above is not limited to a rotating machine with internal permanent magnets.

[0038] If the formula (2) above is solved for a current derivative term, the following formula (3) is obtained. Formula 3: p[iαhiβh]=1L02−L12{L0I−L1[cos(2θ)sin(2θ)sin(2θ)−cos(2θ)]}[VαhVβh]

[0039] High-frequency voltages V α and V β on the αβ-axes are defined by the following formula (4). Formula 4: [VαhVβh]=Vhαβ[cos(ωht)sin(ωht)]

[0040] In formula (4) above, V hαβ a high-frequency voltage amplitude on the αβ axes, and ω h represents an angular frequency on the αβ axes. The angular frequency is also called "angular velocity."

[0041] When formula (4) above is expressed in three-phase coordinates, standard high-frequency voltages V uh1 , V vh1 and V wh1 which are expressed by the following formula (5). Formula 5: [Vuh1Vvh1Vwh1]=Vhuvw[sin(ωht)sin(ωht−2π / 3)sin(ωht+2π / 3)]

[0042] When using the coefficient value W h , which is calculated by the high-frequency amplitude calculator 31, the high-frequency voltage generator 32 multiplies the standard high-frequency voltages V uh1 , V vh1 and V wh1 with the coefficient value W h , whereby the high-frequency voltages V uh , V vh and V wh which are expressed by the following formula (6). Formula 6: [VuhVvhVwh]=Wh[Vuh1Vvh1Vwh1]

[0043] Next, a structure of a rotor core constituting the rotor 1b in a reluctance synchronous machine will be described. Fig. Fig. 3 is a cross-sectional view used to explain a structure of a rotor core 50 in the reluctance rotary machine used in the first embodiment. Fig. 3, the rotor core 50 is formed by laminating a plurality of electromagnetic steel sheets, which are sheet materials. A shaft 51 is fitted into the rotor core 50 at its radially inner side. The rotor core 50 is formed from a laminate obtained by laminating a core segment 53, which is a thin ring sheet. The core segment 53 can be formed by punching an electromagnetic steel sheet, which is a thin steel sheet, with a press machine. In the lathe 1 that has been assembled, a laminating direction of the thin sheets constituting the rotor core 50 is the same as an axial direction of the shaft 51.

[0044] A plurality of slots 52 forming a flux barrier are formed in the rotor core 50, in which the plurality of core segments 53 are laminated. The slots 52 have an arc shape protruding toward a shaft hole into which the shaft 51 is fitted, and are formed from one d-axis side to another d-axis side with the q-axis as the center. In the rotor core 50, the d-axis is an axis through which magnetic flux passes relatively easily, and the q-axis is an axis through which magnetic flux passes relatively difficultly. The d-axis and the q-axis are magnetically and electrically orthogonal to each other.

[0045] Slot groups 54 each including the plurality of slots 52 are formed for the number of poles at intervals in a circumferential direction of the rotor core 50. Fig. 3 illustrates an example in which the rotor 1b comprises four poles, and in Fig. 3, the slot groups 54 are designed for four poles.

[0046] The rotor core 50 must be strong enough to withstand centrifugal force when the lathe 1 rotates. Therefore, a central rib 55a, which acts as a reinforcing member, is formed in the slot 52 located at an outermost edge. In addition to the central rib 55a, two side ribs 55b, which similarly act as reinforcing members, are formed in each of the slots 52, which are located at a portion different from the outermost edge. The central ribs 55a and the side ribs 55b can be formed by leaving portions corresponding to the central ribs 55a and the side ribs 55b unpunched when a thin steel sheet is punched to form the slots 52. The arrangements of the central ribs 55a and the side ribs 55b shown in Fig. The arrangements illustrated in Figure 3 are examples, and there is no limitation to these arrangements. Any arrangement could be used as long as the desired strength can be achieved through the structure.

[0047] Furthermore, in the rotor core 50, an annular portion where no slot is formed is provided between each slot group 54 and a peripheral portion 56 on an outer peripheral side of the rotor core 50. In this specification, this portion is referred to as the "annular portion." In the rotor core 50, the annular portion also functions as a reinforcing member. In this specification, the reinforcing members, such as the central ribs 55a, the side ribs 55b, and the annular portion, which function as the reinforcing members, may be collectively referred to as "bridge portions."

[0048] The fifth and sixth formulas of formula (1) above include the d-axis inductance L d and the q-axis inductance L q . Fig. Figure 4 shows a graph illustrating inductance variation in a general purpose reluctance rotary machine. The horizontal axis represents the rotor position, and the vertical axis represents the magnitude of an inductance.

[0049] In a general reluctance lathe, an inductance changes depending on an electrical angle. This means, more specifically, as in Fig. Figure 4 illustrates that there is a property where a maximum and a minimum value of the inductance appear twice per rotation of the electrical angle. The maximum value of the inductance is the d-axis inductance L d and the minimum value of the inductance is the q-axis inductance L q This means that the d-axis inductance L d greater than the q-axis inductance L q Here, if a ratio of the q-axis inductance L q to the d-axis inductance L dis defined as a salience ratio, a salience ratio L q / L d a value greater than 1. This is because the lathe 1 is set up in such a way that a magnetic flux linkage is created by the q-axis current i q greater than a magnetic flux connection through the d-axis current i d in the currents flowing through the lathe 1.

[0050] Fig. Fig. 5 is a diagram showing examples of current vector locus curves when a high frequency current flows through a rotating machine including the rotor core 50 arranged in Fig. 3 is illustrated. In Fig. 5, the horizontal axis represents the d-axis current i d and the vertical axis represents the q-axis current i q . As in Fig. 5, in a case where the q-axis current i qflowing through the rotating machine 1 is relatively large, current vector loci have an elliptical shape. On the other hand, in a case where the q-axis current i q flowing through the rotating machine 1 is small, as illustrated below left, the current vector loci do not have an elliptical shape, but are essentially circular. The center of each current vector locus represents a component of a fundamental current in the currents flowing through the rotating machine 1, and a distance from the center in each of the current vector locus diagrams represents a component of a high-frequency current in the currents flowing through the rotating machine 1. Therefore, an area where the q-axis current i q is small that a torque command to be given to the lathe 1 is small.

[0051] In a case where a current vector locus has an elliptic shape, the rotor position can be detected from a direction of a major axis and from a direction of a minor axis of the ellipse. On the other hand, in a case where the current vector locus does not have an elliptic shape, it is difficult to distinguish between the major axis and the minor axis, so that the rotor position cannot be accurately detected. One reason for this will be explained with reference to Fig. 6 are described. Fig. Figure 6 shows a diagram that is used in the Fig. 3 illustrates a flow of a magnetic flux generated by a component of a high-frequency current when a component of a fundamental current is small.

[0052] In Fig. 6, each solid arrow line indicates a flow of a magnetic flux that can be generated by a component of a high-frequency current contained in the q-axis current i q In this description, this magnetic flux component is also referred to as "torque magnetic flux" for simplicity. Broken arrow lines each indicate a magnetic flux that can be generated by a component of a high-frequency current contained in the d-axis current i d In this description, the magnetic flux component is also referred to as “excitation magnetic flux” for simplicity. As described above, the magnetic flux component Fig. The rotor core 50 illustrated in Figure 3 has a structure with saliency. Therefore, during steady-state operation where a component of the fundamental current is large, the bridge portion of the rotor core 50 is sufficiently magnetically saturated, so that a q-axis magnetic flux indicated by a solid arrow becomes small. On the other hand, in a case where the component of the fundamental current is small, the degree of magnetic saturation in the bridge portion is small, so that the torque magnetic flux passing through the bridge portion is not greatly attenuated. Therefore, the torque magnetic flux passing through the bridge portion increases, a difference in the excitation magnetic flux decreases, and thus, no saliency occurs.

[0053] The control device 100 according to the first embodiment shown in Fig. 1, which is described above, is arranged in such a way that the above-described problem regarding salience is solved. More specifically, this means that in a case where a desired detection accuracy with respect to the estimated value θ L the rotor position cannot be achieved, the control device 100 sets the coefficient value W h , which is calculated by the high-frequency amplitude calculation means 31, in such a direction that the coefficient value increases, and performs a control to increase the voltage amplitudes of the high-frequency voltages V uh , V vh and V wh For simplicity, this control is referred to as "high-frequency boost control" in this description.

[0054] Here, considering a case where there is no high-frequency current, in a case where the base current is small, its magnetic flux component simply passes through the bridge portion. As the width of the bridge portion is narrowed, the amount of magnetic flux passing therethrough decreases, but the strength of the rotor core 50 decreases. As the base current is increased, a portion where the bridge portion exists is magnetically saturated. However, in the case of this method, an unnecessary current is caused to flow, which impairs efficiency, and also provides unnecessary torque to the rotary machine 1, which is not preferable in terms of operation. On the other hand, as the high-frequency current is increased, the bridge portion may be magnetically saturated without changing the magnitude of the base current.Consequently, it is possible to overcome the property that the background current prevents the salience from occurring through control.

[0055] The specific processes are described above. The coefficient value W h is calculated by the high-frequency amplitude calculation device 31 and the standard high-frequency voltages V uh1 , V vh1 and V wh1 are calculated with the coefficient value W h multiplied and thereby the high frequency voltages V uh , V vh and V wh In addition, a table for calculating the coefficient value W h be used. Fig. 7 is a diagram illustrating an example of a coefficient value table used in the high-frequency gain control according to the first embodiment.

[0056] Fig. 7 illustrates in the coefficient value table above current values ​​i d1 *, id2 *, i d3 *,... and i dM * of the d-axis current command i d *, which can be set, and illustrates in the coefficient value table current values ​​i q1 *, i q2 *, i q3 *,... and i qN * of the q-axis current command i q *, which can be set. Increments, the intervals between the current values ​​i d1 *, i d2 *, i d3 *... and i dM * do not have to be even intervals and could be odd intervals. The same applies to the current values ​​i q1 *, i q2 *, i q3 * ... and i qN *.

[0057] The coefficient value table stores values ​​(W h11 , W h12 , W h13 , ..., W h1M , W h21 , W h22 , W h23 , ..., W h2M , W h31 , W h32 , W h33 , ..., W h3M , ... , W hN1 , W hN2 , W hN3 ... and WhNM ) of the coefficient value W h , which is determined by the relationship between the d-axis current command i d * and the q-axis current command i q * It can be seen that in a case where the current values ​​i q1 *, i q2 *, i q3 *, ... and i qN * a ratio of i q1 * q2 * q3 *<, ..., qN * fulfill, by W h11 , W h21 , W h31 , ... and W hN1 a ratio of W h11 >W h21 >W h31 >, ... ,>W hN1 is fulfilled. This means that the coefficient value W h a negative correlation with the q-axis current command i q * The same applies to the coefficient values ​​W h from other columns. In addition, in a case where the current values ​​i d1 *, i d2 *, i d3 *,... and i dM * a ratio of i d1 * d2 * d3 ​​​​​*<, ... , dM * fulfill, by W h11 , W h12 , W h13 , ... and W h1M a ratio of W h11 >W h12 >W h13 >,...,>W h1M This means that the coefficient value W h a negative correlation with the d-axis current command i d * The same applies to the coefficient values ​​W h from other lines.

[0058] The stored values ​​stored in the coefficient value table can be obtained through simulation. It should be noted that not all stored values ​​need to be obtained through simulation, and the stored values ​​can be obtained through an arithmetic operation using an interpolation operation, an extrapolation operation, or an interpolation operation of some simulation results.

[0059] Next, a selection of the coefficient value W h ​in the high-frequency gain control according to the first embodiment. First, in the coefficient value table in Fig. 7 a part surrounded by a bold frame is set as standard. Here i d1 *=0 is assumed. The high-frequency amplitude calculation device 31 selects the coefficient value W h in relation to the bold frame part of the coefficient value table in Fig. 7 based on the q-axis current command i q *. If a value of the q-axis current command i q * for example “i q3 *“ is “W h31 ” is selected. In a case where a value of the q-axis current command i q * a value between “i q2 *“ and “i q3 *”, the value could be obtained by the interpolation process or “i q2 *“ or “i q3 *“ could be selected.

[0060] In addition to the q-axis current command i q* the d-axis current command i d * be used as a physical quantity that correlates with the magnetic saturation of the rotor 1b. In this case, the entire coefficient value table in Fig. 7. When a value of the q-axis current command i q * for example “i q3 *“ and a value of the d-axis current command i d * "i d2 *“ is “W h32 " is selected. Needless to say, if the value is not in the coefficient value table, the value could be obtained by interpolation or the like.

[0061] Next, an effect of the high frequency gain control according to the first embodiment will be described with reference to FIG. Fig. 8 and Fig. 9 are described. Fig. 8 is a first diagram for explaining an effect of the high frequency gain control according to the first embodiment. Fig. 9 is a second diagram for explaining the effect of high frequency gain control according to the first embodiment.

[0062] In Fig. 8, the horizontal axis represents the d-axis current i d and the vertical axis represents the q-axis current i q . On the left side of the Fig. 8 are cases where the coefficient values ​​W h W h =0.1, W h =0.3 and W h =0.5, illustrated as current vector loci when for the q-axis current i q =0 and for the d-axis current i d =0. On the right side of the Fig. 8 are the current vector loci as above for the three coefficient values ​​W h illustrated when for the q-axis current i q =0 and for the d-axis current i d >0. The coefficient values ​​W h can be measured using the DC voltage V dcof the DC power supply 12 as a reference. It should be noted that the reference of the coefficient values ​​W h is not limited to this example, and the coefficient values ​​W h could be determined based on any reference.

[0063] In Fig. 9, a theoretical value of the rotor position is indicated by a dashed line and the estimated value θ L The rotor position is indicated by a solid line, along with waveforms of a u-phase current and a v-phase current. (a) A waveform is shown in an upper part when W h =0.1, and (b) is a waveform in a lower part when W h =0.3 applies.

[0064] According to Fig. 8 shows the current vector locus when W h =0.1, no elliptic shape, whereas any current vector locus, when W h =0.3 and W h=0.5, has an elliptical shape. It is also illustrated that this tendency is not influenced by the d-axis current i d depends.

[0065] The results above are consistent with the description above. For example, if W h =0.1, since the portions of the central ribs 55a and the side ribs 55b of the rotor core 50 are not magnetically saturated, the torque magnetic flux passing through the central ribs 55a and the side ribs 55b increases, preventing the salience from occurring. Consequently, the current vector locus does not have an elliptical shape. Consequently, the waveform of the estimated value θ L the rotor position is unstable, as in (a) the Fig. 9, and sufficient estimation accuracy cannot be obtained.

[0066] On the other hand, if W h =0.3 and W h=0.5, the portions of the central ribs 55a and the side ribs 55b of the rotor core 50 are magnetically saturated by the high-frequency current, and thus the torque magnetic flux flowing through the central ribs 55a and the side ribs 55b decreases, and salience occurs, so that the current vector loci each have an elliptical shape. Consequently, the waveform of the estimated value θ L the rotor position is stable, as in (b) of Fig. 9, and sufficient estimation accuracy can be obtained.

[0067] The control and its operation when the high frequency gain control according to the first embodiment is applied to the rotor core 50 having the Fig. 6 have been described above, but are not limited to this example, and can be applied to rotor cores with various structures. The high-frequency gain control according to the first embodiment can also be applied to a rotor core with an extremely small saliency ratio. For example, in a case where the saliency ratio of the rotor core is small, by selecting a larger coefficient value W h Depending on the degree of smallness and by adjusting the high frequency voltage amplitude, the rotor position can be detected.

[0068] However, increasing the coefficient value W h increasing the lathe current. Therefore, there is a trade-off between the operating efficiency of the lathe 1 and the estimation accuracy of the estimated value θ L . Therefore, it is desirable to use the coefficient value W has small as possible within a range that ensures the accuracy of the estimated value θ L For example, with regard to the example in Fig. 8 desirable W h =0.3. The use of a Fig. The table illustrated in Figure 7 allows to calculate such a coefficient value W h to select.

[0069] As described above, according to the lathe control device of the first embodiment, the current control unit generates the first voltage commands, which are command values ​​of the lathe voltages for driving the lathe, based on the detected values ​​of the lathe currents and the estimated value of the rotor position. Then, the position estimation voltage generation unit generates the high-frequency voltages with frequencies higher than the first voltage commands, the high-frequency voltages being position estimation voltages for estimating the rotor position based on the physical quantity correlated with the magnetic saturation of the rotor. Consequently, it is possible to reduce a decrease in detection accuracy of the rotor position even in a case where the salience ratio of the lathe is structurally low.

[0070] Furthermore, in the above configuration, the position estimation voltage generation unit includes the high-frequency amplitude calculator that calculates a coefficient value for determining voltage amplitudes of the high-frequency voltages based on a physical quantity that correlates with magnetic saturation. The high-frequency amplitude calculator generates the position estimation voltages using the coefficient value. Consequently, the configuration of the control device can be easily implemented.

[0071] In the above description, the physical quantity that correlates with the magnetic saturation of the rotor could be a torque-axis current command given to the current control unit, or it could be the torque-axis current command and an excitation-axis current command given to the current control unit. Since the torque-axis current command and the excitation-axis current command are parameters used within the control device, the configuration of the control device can be easily implemented.

[0072] According to the rotary machine control device of the first embodiment, in a case where a desired detection accuracy cannot be obtained with respect to the estimated value of the rotor position, the coefficient value for determining the voltage amplitudes is controlled in such a direction that the coefficient value is increased. Consequently, it is possible to set a coefficient value corresponding to a desired detection accuracy while reducing an increase in a high-frequency current.

[0073] According to the lathe control device of the first embodiment, the rotor position can be detected even when the torque axis current and the excitation axis current are zero. Consequently, it is possible to stably estimate the rotor position while increasing the operating efficiency of the lathe. Second embodiment.

[0074] Fig. Fig. 10 is a diagram illustrating an exemplary configuration of a lathe control device 100A according to a second embodiment. Comparing the control device 100A according to the second embodiment with the control device 100 shown in Fig. 1, the current control unit 5 is replaced by a current control unit 5A in Fig. 10. In the current control unit 5A, a basic current extracting device 11 is added to the configuration of the current control unit 5, which in Fig. 1. Other configurations are the same as or equivalent to those of the control device 100. The same or equivalent components are denoted by the same reference numerals, and redundant descriptions thereof will not be repeated.

[0075] As described above, since the high-frequency current includes a superimposed frequency component, and a sideband component is a disturbance to a power control system, it is desirable that the high-frequency current be sufficiently separated from a response frequency of the power control system. On the other hand, for the purpose of ensuring a calculation time and reducing noise, the superimposed frequency could be set to a lower frequency, and the response frequency and the superimposed frequency of the power control system could be set closer to each other, which has an adverse effect on the operations of the power control system. Furthermore, as described above, in an application where the rotation speed of the rotary machine is high, the sideband component is distributed over a wide area, which has an adverse effect on the operations of the power control system.

[0076] Therefore, in the second embodiment, the background current extracting means 11 is provided to remove or reduce the effect of the high-frequency currents caused by the application of the high-frequency voltages V uh , V vh and V wh As in Fig. 10, the fundamental current extracting device 11 is arranged between the current detecting unit 2 and the three-phase-to-two-phase converter 18, that is, in a preceding stage of the three-phase-to-two-phase converter 18.

[0077] The basic current extraction device 11 extracts basic currents i uf , i vf and i wf , which are obtained by removing or weakening from or in the lathe streams i u , i v and i w detected by the current detection unit 2 have the same frequency components as those of the high-frequency voltages V uh , V vh and V whA low-pass filter or a notch filter can be used to extract the fundamental currents i uf , i vf and i wf The three-phase-two-phase converter 18 performs the operation described in the first embodiment using the fundamental currents i uf , i vf and i wf as input signals. The subsequent operations are the same as those described in the first embodiment.

[0078] According to the control device 100A of the second embodiment, in a process performed by the current control unit 5A, which is a current control system, the superimposed frequency component and its sideband component in the high-frequency currents i uh , i vh and i wh sufficient from the lathe currents i u , i v and i wremoved, which are detected by the current detection unit 2. Consequently, it is possible to prevent an adverse effect on the current control system, such as deterioration of a response or instability.

[0079] As described above, according to the rotary machine control device of the second embodiment, the fundamental component extractor removes harmonic superimposed components included in detected values ​​of the rotary machine currents to extract fundamental components. Then, the current control unit generates the first voltage commands based on the outputs of the fundamental component extractor and the estimated value of the rotor position. Consequently, an effect of reliably preventing adverse effects on the current control system, such as response degradation or instability, is obtained.

[0080] Next, a hardware configuration of the control devices 100 and 100A according to the first embodiment and the second embodiment described above will be described with reference to FIG. Fig. 11 and Fig. 12 are described. Fig. 11 is a diagram illustrating a first exemplary hardware configuration that realizes the functions of the control devices 100 and 100A according to the first embodiment and the second embodiment. Fig. 12 is a diagram illustrating a second exemplary hardware configuration that realizes the functions of the control devices 100 and 100A according to the first embodiment and the second embodiment. The functions of the control devices 100 and 100A refer to the functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 included in the control devices 100 and 100A.

[0081] The functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 can be realized using one processing circuit. Fig. 11, the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 in the first embodiment and the second embodiment have been replaced with a dedicated processing circuit 40. In a case where dedicated hardware is used, the dedicated processing circuit 40 corresponds to a single circuit, a composite circuit, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. The functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 may each be realized by the processing circuit or may be realized jointly by the processing circuit.

[0082] In Fig.12, the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 in the configurations of the first embodiment and the second embodiment have been replaced by a processor 41 and a storage device 42. The processor 41 may be an arithmetic means such as an arithmetic device, a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). A non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable ROM (EPROM), or an electronic EPROM (EEPROM) (registered trademark) may be used as the storage device 42.

[0083] In a case where the processor 41 and the storage device 42 are used, the functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 are realized by software, firmware, or a combination thereof. The software or firmware is written as a program and stored in the storage device 42. The processor 41 reads and executes programs stored in the storage device 42. It can also be said that these programs cause a computer to execute procedures and processes of the functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30.As the storage device 42, for example, a non-volatile or volatile semiconductor memory such as a ROM, an EPROM or an EEPROM, a flexible disk, an optical disk, a compact disk or a DVD can be used.

[0084] Some of the functions of the position estimation unit 4, the current control units 5 and 5A, and the position estimation voltage generation unit 30 may be implemented by hardware, and other parts may be implemented by software or firmware. For example, the function of the position estimation voltage generation unit 30 may be implemented using dedicated hardware, and the functions of the position estimation unit 4 and the current control units 5 and 5A may be implemented using the processor 41 and the memory device 42.

[0085] The configurations described in the embodiments above are merely examples and can be combined with other known technologies, and the embodiments can be combined with each other, and part of the configurations can be omitted or modified without departing from the gist of the matter. List of reference symbols

[0086] 1 Lathe; 1a Stator; 1b Rotor; 2 Current detection unit; 3 Voltage application device; 4 Position estimation unit; 5, 5A Current control unit; 6u, 6v, 6w Current extraction device; 7 High-frequency current amplitude calculation unit; 8 Position calculation device; 9u, 9v, 9w Multiplication device; 10u, 10v, 10w Integration device; 11 Fundamental current extraction device; 12 DC power supply; 13d, 13q Subtraction device; 14d D-axis current control device; 14q Q-axis current control device; 15 First coordinate converter; 16 Two-phase-to-three-phase converter; 17 Second coordinate converter; 18 Three-phase-to-two-phase converter; 22u, 22v, 22w square root calculation means; 23u, 23v, 23w adding means; 30 position estimation voltage generation unit; 31 high-frequency amplitude calculation means; 32 high-frequency voltage generator; 40 dedicated processing circuit; 41 processor; 42 storage device; 50 rotor core; 51 shaft; 52 slot; 53 core segment;54 slot group; 55a central rib; 55b side rib; 56 edge portion; 100, 100A control device.; 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 2002-171799

[0005] JP 5324646

[0028]

Claims

[1] Lathe control device comprising: a current detection unit for detecting a lathe current flowing through a lathe; a position estimating unit for calculating an estimated value of a rotor position, which is position information of a rotor of the rotating machine, based on the rotating machine current; a current control unit for generating a first voltage command, which is a command value of a lathe voltage for driving the lathe, based on a detected value of the lathe current and an estimated value of the rotor position; a position estimation voltage generation unit for generating a high-frequency voltage having a frequency higher than the first voltage command, wherein the high-frequency voltage is a position estimation voltage for estimating the rotor position based on a physical quantity that correlates with a magnetic saturation of the rotor; and a voltage applying device for applying a control voltage to the lathe based on a second voltage command in which the position estimation voltage is superimposed on the first voltage command. [2] The lathe control device according to claim 1, wherein the physical quantity is a torque axis current command given to the current control unit. [3] The lathe control device according to claim 1, wherein the physical quantity is a torque-axis current command and an excitation-axis current command given to the current control unit. [4] Lathe control device according to one of claims 1 to 3, wherein the position estimation voltage generation unit a high-frequency amplitude calculating means for calculating a coefficient value for determining a voltage amplitude of the high-frequency voltage based on the physical quantity, and the position estimation voltage is generated by calculating the coefficient value. [5] The lathe control device according to claim 4, wherein the coefficient value has a negative correlation with the physical quantity. [6] A lathe control device according to claim 4 or 5, wherein in a case where a desired detection accuracy with respect to an estimated value of the rotor position is not available, the coefficient value is controlled in such a direction that the coefficient value increases. [7] Lathe control device according to one of claims 1 to 6, wherein the current control unit comprises a fundamental component extractor for removing a harmonic superimposed component included in a detected value of the rotary machine current to extract a fundamental component, and generates the first voltage command based on an output of the fundamental component extractor and an estimated value of the rotor position.

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