JP4967375B2 - Current control device and current control method for synchronous machine - Google Patents

Description

  The present invention relates to a current control device and a current control method for a synchronous machine, and in particular, current control for a synchronous machine that can reduce both torque fluctuations, which are main causes of synchronous machine vibration, and radial nodal forces, which are main causes of noise. The present invention relates to a device and a current control method.

Conventionally, a synchronous motor control device and a current control method have been proposed in which the applied current of the synchronous motor is controlled to reduce the torque fluctuation of the synchronous motor (see, for example, Patent Document 1).
This applies the basic current (primary frequency current) as an applied current applied to each phase of a synchronous motor driven by n-phase alternating current as follows: K = 1 + Σ _{i = 1} k _2in · cos {2in (ωt + χ _2in )} Driving is performed by applying a current corrected by the correction coefficient K obtained in step (1). At this time, with respect to the coefficient _k2in , the polarity of the ratio of the 2-in order component to the average torque calculated by Fourier transforming the torque fluctuation waveform when the synchronous motor is controlled with a sine wave current is inverted. In other words, in this current control, when the basic current of each phase is I = Acos (ωt) + Bsin (ωt), the current I ′ superimposed with the high-order frequency current that reduces the 2 in-order component is expressed as I ′ = {Acos (ωt) + Bsin (ωt)} * {1 + qcos (2inωt) + rsin (2inωt)} is given by 2in calculated by Fourier transforming the torque fluctuation waveform when q is controlled by a sine wave current. The average torque of the 2-in-order component imaginary part calculated by Fourier transforming the torque fluctuation waveform when the synchronous motor is controlled by a sine wave current, assuming that the polarity of the ratio of the real component of the second-order component is inverted. This is equivalent to reversing the polarity of the ratio of the high-order frequency current that cancels out the high-order frequency current component with large torque fluctuation that occurs when the basic current is applied. It is intended to reduce torque fluctuations superimposed on the flow.
JP 2001-352791 A

  However, since the high-order frequency current component that reduces the torque fluctuation is different from the high-order frequency current component that reduces the radial nodal force, the high-order frequency intended to reduce the torque fluctuation as in the above-described Patent Literature 1 is different. In current control in which the basic current is corrected with a correction coefficient set based on the current component, there is a problem that the radial nodal force cannot be reduced even if it is effective in reducing torque fluctuation.

  The present invention has been made paying attention to this problem, and has an effect of reducing both torque fluctuation and radial nodal force, and a synchronous machine current control device and current control capable of reducing vibration and noise of the synchronous machine. It aims to provide a method.

For this reason, the current control device for a synchronous machine of the present invention reduces the torque fluctuation and the p-order component of the radial nodal force that appear when a basic current is applied to each phase coil of the synchronous machine. A current controller for a synchronous machine that performs correction by multiplying a correction coefficient that is set based on the p-order high-order frequency current component, wherein K = [1 + qcos (pωt) + rsin (pωt)] the resulting K given as the correction coefficient, the coefficient q of said correction factor K related to the amplitude value of the p-th order higher frequency current components, the r, first coefficient and radial nodes torque variation reduction Correction coefficient setting means for setting the correction coefficient K by setting based on the second coefficient for force reduction, and an applied current obtained by multiplying the basic current by the correction coefficient K set by the correction coefficient setting means. Driving the synchronous machine by controlling the application to each phase coil Characterized by being configured with a Gosuru drive control means.

Further, the current control method for a synchronous machine according to the present invention is configured to reduce the torque fluctuation and the p-order component of the radial nodal force that appear when a basic current is applied to each phase coil of the synchronous machine, This is a current control method for a synchronous machine which is corrected by multiplying a correction coefficient set based on a p-order high-order frequency current component, and is obtained by an equation of K = [1 + qcos (pωt) + rsin (pωt)]. Is given as the correction coefficient, and the coefficients q and r in the correction coefficient K related to the amplitude value of the p-th order higher-order frequency current component are expressed as the first coefficient for reducing torque fluctuation and the radial nodal force. A correction coefficient K is set based on the second coefficient for reduction, and an application current obtained by multiplying the set correction coefficient K by the basic current is applied to each phase coil to control the synchronous machine. It is characterized by drive control.

  According to the current control device and current control method for a synchronous machine of the present invention, when it is desired to reduce the torque fluctuation of the synchronous machine, the correction coefficient by the first coefficient for torque fluctuation reduction is selected to reduce the radial nodal force. In some cases, the basic current can be corrected by selecting a correction coefficient based on the second coefficient for reducing the radial nodal force, so that the radial nodal force that is the main factor of torque fluctuation and noise is the main factor of vibration of the synchronous machine. Both the vibration and noise of the synchronous machine can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a current controller for a synchronous machine according to the present invention, and shows an example applied to a drive system for a three-phase synchronous motor.
In FIG. 1, the current control device 10 according to the present embodiment includes a current value and a phase of a sine wave basic current of each phase based on a torque command value from a controller (not shown) and the rotation speed of the motor 30 detected by the rotation sensor 1. And a correction coefficient K for reducing torque fluctuation and radial nodal force appearing when a basic current (primary frequency current) is applied is set as described later, and the set correction coefficient K is set as follows. A current correction coefficient setting unit 11 serving as a correction coefficient setting unit that corrects the basic current by multiplying the basic current, a correction current value output from the current correction coefficient setting unit 11, and each phase detected by the current sensor 2 The comparison result with the actual current value is input via the three-phase / two-phase converter 12 and the voltage command value by feedback control based on the comparison result is input to the motor driver via the two-phase / 3-phase converter 14. It comprises a PI controller 13 as a drive control means for outputting to the bus 20.

The motor driver 20 applies an AC voltage having a predetermined frequency different in phase by 120 degrees to the coils of each phase via the PWM control unit 21 and the inverter 22 based on the input voltage command value. 30 is driven at a rotational speed corresponding to the frequency.
FIG. 2 and FIG. 3 show the structure of a three-phase synchronous motor with distributed winding of four pole pairs and 48 teeth, which tend to be frequently used to provide the characteristics of high output and low vibration as the motor 30.

The motor 30 includes a stator 40, a rotor 50, and a motor case 60 that houses them.
The rotor 50 is rotatably supported by bearings 61 and 62 provided on a motor case 60 with a rotary shaft 70 provided at the center of the rotor 50. Further, a laminated steel plate fixed by press-fitting with respect to the rotary shaft 70 is used as a base material, and eight permanent magnets 51 to 58 are arranged at substantially equal intervals in the circumferential direction as shown in FIG. And as shown in FIG. 2, it penetrates and is fixed to the axial direction. The permanent magnets 51 to 58 are magnetized in the thickness direction, and are arranged so that the N pole and S pole of adjacent magnets are opposite to each other as shown in FIG. When the rotor 50 is assembled to the motor case 60, the permanent magnets 51 to 58 form a magnetic path due to the relationship between the permanent magnets 51 to 58 of the rotor 50 and the electromagnet of the stator 40.

  The stator 40 uses a laminated steel plate fixed to the motor case 60 by press-fitting, bolting, or the like as a base material, and a total of 48 teeth (1 ) To (48). A coil 42 connected to the motor driver 20 is wound around a slot formed between the teeth (1) to (48). As shown in FIG. 3, the coil 42 is divided into three phases of a U-phase coil, a V-phase coil, and a W-phase coil, and the phases from the motor driver 20 are different from each other by a predetermined frequency of 120 degrees. A rotating magnetic field is generated in the stator 40 by applying an AC voltage.

In the current correction coefficient setting unit 11, the correction coefficient K is given by the following equation (1), and the values of the coefficients q and r in the correction coefficient K are used as the first coefficients q1 and r1 for torque fluctuation reduction and the radial direction. The correction coefficient K is set by selecting one of the second coefficients q2 and r2 for reducing the nodal force.
K = [1 + qcos (pωt) + rsin (pωt)] (1)
In addition, p shows the order of the high-order frequency current superimposed on the primary frequency current in order to reduce torque fluctuation and radial nodal force.

The coefficients q and r in the correction coefficient K are values determined in relation to the amplitude value of the superposed p-order high-order frequency current component, and F ¹ ₀ , F ² ₀ , and F ³ ₀ are set as the phase currents. When the torque fluctuation (or radial nodal force) of the direct current (DC) component is set to F _p ^real and the real part of the p-order component of the torque fluctuation (or radial nodal force) to be reduced is F _p ^real and the imaginary part is F _p ^imag The coefficients q and r are given by the following equation (2), for example.

q = −F _p ^real / (F ¹ ₀ + 2F ² ₀ + 3F ³ ₀ ), r = −F _p ^imag / (F ¹ ₀ + 2F ² ₀ + 3F ³ ₀ ) (2)
Here, it is shown that the torque and the radial nodal force depend only on the applied current value regardless of the rotational speed of the motor, and the higher order frequency current that reduces the torque fluctuation and the higher order frequency that reduces the radial nodal force. Indicates that the current is different. In other words, the higher-order frequency current component superimposed to reduce torque fluctuations and radial nodal forces depends on the current value, and the correction factor K in the correction coefficient K related to the amplitude value of this superimposed higher-order frequency current component It is shown that the coefficients q and r are different between the first coefficients q1 and r1 for reducing torque fluctuation and the second coefficients q2 and r2 for reducing the radial nodal force.

  The torque and radial nodal force were calculated using electromagnetic field analysis software (JMAG: manufactured by Japan Research Institute, Ltd.) for the above-described three-phase synchronous motor with distributed winding of 4 pole pairs and 48 teeth. FIG. 4 shows 1/4 of the two-dimensional model at the time of calculation. FIG. 5 shows the torque waveform when the applied current is 900 A and the rotational speed of the rotor 50 is 1500 rpm and 3000 rpm, and FIG. 6 shows the radial nodal force waveform of the tooth (1) (the outward direction of the stator 40). Was positive). As can be seen from FIGS. 5 and 6, the torque waveform and the radial nodal force waveform have the same results of 1500 rpm and 3000 rpm, and it can be seen that the torque and the radial nodal force substantially depend on the applied current value.

  Moreover, what carried out the Fourier conversion of the result of carrying out the Fourier transform of each waveform of 3000 rpm of FIG. 5, FIG. 6 is shown in FIG. 7, FIG. It can be seen from FIG. 7 that the torque fluctuation has an even order, particularly a multiple order of 6, and from FIG. 8, the radial nodal force has a large even order. FIG. 9 is a plot of 12th order components of torque fluctuation and radial nodal force on a complex plane. From FIG. 9, the 12th order component of torque fluctuation and the 12th order component of radial nodal force differ in phase by about 90 °. As a result, at the same high order frequency current, the 12th order component of torque fluctuation and the 12th order of radial nodal force. It can be seen that the next component cannot be reduced.

  FIG. 10 uses the coefficients q and r calculated from the equation (2) based on the high-order frequency current value with the 12th-order component of the radial nodal force as the reduction target for the U-phase current value at the basic current value 900A. The current value corrected by the correction coefficient K (broken line in the figure) and the original (uncorrected) current value (solid line in the figure) are shown. For the original U-phase current, higher-order frequency current components due to the correction coefficient K can be recognized at the peaks and valleys.

  FIG. 11 shows a radial nodal force (broken line in the figure) in the tooth (1) when the current corrected by superimposing the higher-order frequency current component of FIG. 10 is applied to each phase of the motor 30. The result of the Fourier transform is shown in decibels (dashed line in the figure). The solid line in FIG. 11 shows the original (uncorrected) waveform shown in FIG. 6, and the solid line in FIG. 12 shows the result of Fourier transform of the original (uncorrected) in FIG. 6 displayed in decibels. It is shown in FIG. 12 shows that the effect of reducing the 12th-order component by correction is just over 10 dB.

  On the other hand, FIG. 13 shows a torque waveform (broken line in the figure) when it is corrected with the same correction coefficient K, and FIG. 14 shows a result of the Fourier transform obtained by decibel display (broken line in the figure). The solid line in FIG. 13 shows the original (uncorrected) waveform shown in FIG. 5, and the solid line in FIG. 14 shows the result of Fourier transform of the original (uncorrected) in FIG. 5 displayed in decibels. It is shown in From FIG. 14, the twelfth order component having a reduction effect on the radial nodal force is slightly deteriorated. Therefore, the high-order frequency current value that reduces the torque fluctuation is different from the high-order frequency current value that reduces the radial nodal force, and the coefficient q in the correction coefficient K related to the amplitude value of the superposed high-order frequency current component is different. , R is different between the first coefficient q1, r1 for torque fluctuation reduction and the second coefficient q2, r2 for radial nodal force reduction.

  FIG. 15 shows the values of the first coefficient q1, r1 (solid line in the figure) for torque reduction and the p-order radial nodal force calculated based on the p-order frequency current component that reduces the p-order torque fluctuation. The relationship between the value of the second coefficient q2, r2 (the broken line in the figure) for radial reduction calculated based on the p-order frequency current component to be reduced and the basic current value is shown, and these first coefficients q1, It can be seen that r1 and the second coefficients q2 and r2 change corresponding to the basic current value.

Hereinafter, a setting example of the correction coefficient K by the current correction coefficient setting unit 11 of the current control device 10 illustrated in FIG. 1 will be described.
Based on the input torque command value and the rotational speed of the motor 30, the first coefficient q1, r1 and the second coefficient q2, r2 are selected and the correction coefficient K is set.
First, the case of the torque command value will be described.

For example, the correction coefficient K is set by switching the first coefficient q1, r1 and the second coefficient q2, r2 according to the basic current value proportional to the input torque command value. In this case, as shown in FIG.
A predetermined basic current value (for example, 1600 A) is set in advance as the switching current value, and in a region where the load is low below this current value, the first coefficients q1 and r1 are selected with emphasis on reducing torque fluctuations, and Ka = [ 1 + q1cos (pωt) + r1sin (pωt)] is set as a correction coefficient Ka for torque fluctuation reduction, and a current value corrected by multiplying the correction coefficient Ka by the basic current is applied to the motor 30. In the region where the torque command value is large and the current value is larger than the switching current value and the load is high, the second coefficients q2 and r2 are selected with emphasis on reducing the radial nodal force, and Kb = [1 + q1cos ( The correction coefficient Kb for reducing the radial nodal force is set as pωt) + r1sin (pωt)], and an application current corrected by multiplying the correction coefficient Kb by the basic current is applied to the motor 30. In FIG. 16, when the load increases from the low current side to the high current side, the state where the selected coefficients q and r are switched from the first coefficient q1 and r1 to the second coefficient q2 and r2 is indicated by an arrow. It is shown.

In addition, when the vibration of the motor 30 and noise discontinuity become a problem when the correction coefficient K is switched, the correction coefficient K may be switched smoothly.
For example, when switching between the first coefficients q1 and r1 and the second coefficients q2 and r2, the coefficients q and r are expressed by the following linear expression (3) in a predetermined switching region in the vicinity of the switching current value. Use the sum.

q = s * q1 + t * q2
r = s * r1 + t * r2 (3)
(However, the coefficients s and t are s + t = 1)
Then, one of the coefficients s and t is gradually increased and the other is gradually decreased, and the values of the coefficients q and r in the correction coefficient K are set to determine the correction coefficient K.

  For example, as shown by the arrow in FIG. 17, when shifting from the low current side to the high current side, 1600A to 2000A is used as the switching region, and in equation (3), by gradually decreasing the coefficient s and gradually increasing the coefficient t, The values of the coefficients q and r are gradually changed from the values of the first coefficients q1 and r1 before switching (solid lines in the figure) to the values of the second coefficients q2 and r2 after switching (broken lines in the figure). Thereby, the correction coefficient K can be switched smoothly, and the discontinuity in vibration and noise of the motor 30 can be suppressed.

  In FIG. 17, 1600A to 2000A is the switching region, and the predetermined current value (1600A) is the switching start point of the coefficients q and r. However, switching is started at the current value before the predetermined current value and switched at the predetermined current value (1600A). The switching region may be set so as to end, or the switching region may be set across the predetermined current value, and the switching may be started and ended before and after the predetermined current value.

  When the magnetic flux of the motor 30 is substantially saturated in the high load region, the amount of plus magnetic flux that should be caused by the superposition of the high-order frequency current with respect to the basic current is small, and the reduction effect by correction is greatly reduced. Therefore, above the current value at which the magnetic flux of the motor 30 is substantially saturated, the coefficients q and r should be set to q = r = 0 so that the basic current is not corrected and the high-order frequency current is not superimposed. Thereby, the power consumption by high-order frequency current superposition can be suppressed.

Next, the case of the motor rotation speed will be described.
As in the case of the current value described above, a predetermined rotational speed is determined in advance, and in the low rotational speed region below this rotational speed, the first coefficient q1, r1 is selected with emphasis on the reduction of torque fluctuation, and the torque fluctuation is reduced. The correction coefficient Ka described above is set, and the correction coefficient Ka is multiplied by the basic current for correction. Further, in a region where the rotational speed is higher than the predetermined rotational speed, the second coefficient q2 and r2 are selected with emphasis on the reduction of the radial nodal force, and the correction coefficient Kb for reducing the radial nodal force is set. The correction factor Kb is corrected by multiplying the basic current. Here, the predetermined rotation speed corresponds to a first predetermined rotation speed.

  In order to smoothly switch the correction coefficient K, the coefficients q and r are expressed by a linear sum of the expression (3) in a predetermined switching region including the predetermined rotation speed, and one of the coefficients s and t is expressed. The correction coefficient K is determined by gradually increasing and decreasing the other, and setting the values of the coefficients q and r in the correction coefficient K. For example, in the switching region indicated by the broken line in FIG. 18, when the coefficients q and r are represented by the expression (3), in other words, when the correction coefficient K is K = s * Ka + t * Kb, the low rotational speed With the coefficients s and t set to s = 1 and t = 0, the reduction in torque fluctuation is emphasized. On the high rotation speed side, the reduction in radial nodal force is emphasized with s = 0 and t = 1. When shifting to the high rotation side, the coefficient s is gradually decreased and the coefficient t is gradually increased in the switching region indicated by the dotted line in the figure, so that the correction coefficient K is smoothly switched. When shifting from the high rotation side to the low rotation side, the coefficient s is gradually increased and the coefficient t is gradually decreased in the switching region to smoothly switch the correction coefficient K.

FIG. 18 shows an example in which switching is started and ended across a predetermined rotational speed, but it goes without saying that the predetermined rotational speed may be used as the switching start point and end point of the correction coefficient K.
In the above-described example, an example has been described in which reduction of torque fluctuation is emphasized on the low rotation side, and reduction of radial nodal force is emphasized on the high rotation side. It may be set so that reduction of force is emphasized and reduction of torque fluctuation is emphasized on the high rotation side.

Further, either one of the torque fluctuation and the radial nodal force is reduced in a predetermined rotation speed region approximately centered on the second predetermined rotation speed, and the other is reduced outside the predetermined rotation speed region. The correction coefficient K may be switched and set.
For example, as shown in FIG. 19, in a predetermined rotational speed region A indicated by a dotted line in the figure which is predetermined with the predetermined rotational speed N as the second predetermined rotational speed approximately as a center, the coefficient s at K = s * Ka + t * Kb = 1, t = 0, the correction coefficient K is set to K = Ka to reduce the torque fluctuation, and in a rotational speed region other than the predetermined rotational speed region A, the coefficient s = 0, t = 1, and the correction coefficient K is set to K = Set to Kb to reduce radial nodal force.

  The correction coefficient K may be switched by changing the coefficients s and t from s = 0 → 1 and t = 1 → 0 when the rotation speed enters the predetermined rotation speed area A from outside the predetermined rotation speed area. In order to smoothly switch the coefficient K, when approaching the predetermined rotational speed N from the end of the predetermined rotational speed region A (dotted line in the figure), the coefficient s is gradually increased and the coefficient t is gradually decreased. When approaching the end of the region A (dotted line in the figure), the coefficient s is gradually decreased and the coefficient t is gradually increased, and the correction coefficient K is gradually switched from Ka to Kb and from Kb to Ka. Good.

The second predetermined rotational speed in this case is determined from the rotational direction (torsion) resonance frequency of the drive system of the motor 30. For example, in the case of a 4-pole motor, if the drive system resonance frequency is fn, the predetermined rotational speed N is N = (60 * fn) / (4 * p) = (15 * fn) / p.
Further, in the predetermined rotational speed region A, the radial nodal force is reduced by the correction coefficient Kb with the coefficient s = 0 and t = 1 at K = s * Ka + t * Kb, and the coefficient s = 1 at other than the predetermined rotational speed region A. The torque fluctuation may be reduced with the correction coefficient Ka at t = 0. Switching of the correction coefficient K can be performed in the same manner as when the torque fluctuation is reduced in the predetermined rotation speed region A described above. The second predetermined rotational speed N ′ in this case is determined from the resonance frequency of the structure including the motor case. For example, in the case of a four-pole motor, if the structure resonance frequency is fm, the predetermined rotational speed N ′ is N ′ = (60 * fm) / (4 * p) = (15 * fm) / p.

When the drive system resonance and the structure resonance are mixed, the correction coefficient K is K = Ka as described above in each predetermined rotation speed region including each predetermined rotation speed N and N ′ determined by the respective resonance frequencies. Alternatively, current correction may be performed using K = Kb.
When the torque fluctuation and the nodal force in the radial direction are reduced in the predetermined rotational speed region A set based on the drive system resonance and the structure resonance as described above, the correction coefficient K is used except in the predetermined rotational speed region A. Current correction may not be performed. This can avoid unnecessary power consumption.

Further, when the rotational speed of the motor becomes high, it becomes difficult to form a command signal to the inverter 22 of the PWM control unit 21 regarding the pth order. For this reason, it is preferable not to perform current correction by superimposing higher-order frequency currents at a rotational speed or more that hinders PWM control. Thereby, useless power consumption can be reduced.
In the above-described embodiment in which the correction coefficient K is set by switching the first coefficient and the second coefficient according to the basic current value, the coefficients q and r in the correction coefficient K are as shown in FIG. From the map showing the correspondence between the basic current value and the first coefficient q1, r1 and the second coefficient q2, r2, any one of the first coefficient q1, r1 and the second coefficient q2, r2 according to the basic current value. However, the data of the area where the first coefficients q1 and r1 and the second coefficients q2 and r2 are not selected is not necessary. Therefore, only the data of the necessary areas selected from the first coefficient q1, r1 and the second coefficient q2, r2 are combined with each other, and one coefficient q ′, r ′ data is associated with the basic current value and mapped. It is good to memorize and memorize.

  For example, taking FIG. 16 as an example, the first coefficients q1 and r1 are selected in a low load region where the switching current (1600A) is lower, and the second coefficients q1 and r1 are selected in a high load region where the switching current (1600A) is higher. In the high current region on the right side of the diagram with the switching current (1600 A) in FIG. 16 as the boundary, the first coefficient q1 and r1 data are not necessary, and in the low current region on the left side of the diagram, The coefficient q2 and r2 data of 2 is not necessary. Accordingly, the data of each unnecessary area is deleted, and the first coefficient q1 and r1 data selected in the low current area on the left side in the figure and the high current area on the right side in the figure with the switching current (1600A) in FIG. The coefficients q1 and q2 and the coefficients r1 and r2 of the second coefficient q2 and r2 data selected in the above are combined with each other, and the combined coefficients are the coefficients q ′ and r ′, and q ′ ( A map in which the coefficient data of the broken line in the figure and r ′ (solid line in the figure) is associated with the basic current value is created.

As a result, it is not necessary to select the first coefficients q1, r1 and the second coefficients q2, r2, and the values of the coefficients q ′ and r ′ can be directly read corresponding to the basic current value, and the correction coefficient K The setting process can be performed easily and quickly.
In the above-described embodiment, the p-order of the high-order frequency component has been narrowed down to one. However, when there are a plurality of orders to be reduced, the correction coefficient K is set to
K = [1+ {q ₁ cos (p ₁ ωt) + r ₁ sin (p ₁ ωt)} + {q ₂ cos (p ₂ ωt) + r ₂ sin (p ₂ ωt)}
+ {Q ₃ cos (p ₃ ωt) + r ₃ sin (p ₃ ωt)} +.
, P ₁ , p ₂ , p ₃ ,... For each of the first coefficient q1, r2 value for torque fluctuation reduction and the second coefficient q2, r2 for radial direction reduction. It is only necessary to superimpose them.

In addition, although this embodiment showed the example of the distributed winding 3 phase synchronous motor of 4 pole pairs 48 teeth as an example of a synchronous machine, it can apply similarly to the synchronous motor from which the number of pole pairs and the number of teeth differ. Furthermore, the present invention can be applied to a synchronous generator and a synchronous motor generator.
Moreover, although this embodiment showed the application example to the radial type synchronous machine with which a rotor and a stator are opposingly arranged to radial direction, for example, a rotor and a stator are opposingly arranged to an axial direction. It can also be applied to an axial type synchronous machine.

The block diagram which shows the outline of the drive system of the synchronous motor to which one Embodiment of the current control apparatus of the synchronous machine of this invention is applied. Sectional view showing the structure of a synchronous three-phase motor Overall view showing rotor and stator of motor shown in FIG. Calculation model diagram using electromagnetic analysis software Torque waveform diagram when the rotational speed is varied with the same current value Radial nodal force waveform diagram with different rotational speeds at the same current value The figure which shows the Fourier-transform result of the torque waveform of FIG. The figure which shows the Fourier-transform result of the radial nodal force waveform of FIG. A plot of the 12th order components of torque and radial nodal force on a complex plane U-phase current waveform diagram with and without superposition of higher-order frequency current for radial nodal force reduction Radial nodal force waveform diagram with and without superposition of high-order frequency current for radial nodal force reduction The figure which shows the Fourier-transform result of each radial direction nodal force waveform of FIG. Each torque waveform diagram with and without superposition of high-order frequency current for radial nodal force reduction The figure which shows the Fourier-transform result of each torque waveform of FIG. A map showing the correspondence between the first and second coefficients and the basic current value Example when switching the first coefficient and the second coefficient according to the basic current value Another example of switching between the first coefficient and the second coefficient according to the basic current value Example diagram when switching between the first coefficient and the second coefficient depending on the rotation speed Another example of switching between the first coefficient and the second coefficient depending on the rotation speed Map diagram of coefficient data obtained by combining only data of necessary areas selected for the first coefficient and the second coefficient

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Current control apparatus 11 Current correction coefficient setting part 13 PI control part 20 Motor driver 21 PWM control part 22 Inverter 30 Three-phase synchronous motor 40 Stator 42 Coil 50 Rotor 60 Motor case 70 Rotating shaft

Claims (11)

In order to reduce the p-order component of torque fluctuation and radial nodal force appearing when a basic current is applied to each phase coil of the synchronous machine, the basic current is set based on the p-order high-order frequency current component. A current controller for a synchronous machine that corrects by multiplying by a correction coefficient,
K = [1 + qcos (pωt) + rsin (pωt)] is obtained as the correction coefficient, and the coefficients q and r in the correction coefficient K related to the amplitude value of the p-order high-order frequency current component are given. and a correction factor setting means for setting a correction coefficient K to set based on the first coefficient and the second coefficient of the radial nodal force for reducing the torque variation reduction,
Drive control means for driving and controlling the synchronous machine by applying an application current obtained by multiplying the basic current by the correction coefficient K set by the correction coefficient setting means to each phase coil;
A current control device for a synchronous machine, comprising: 2. The current control device for a synchronous machine according to claim 1, wherein the correction coefficient setting means is configured to switch between the first coefficient and the second coefficient in accordance with a state quantity relating to the operation of the synchronous machine. 3. The current control device for a synchronous machine according to claim 1, wherein the correction coefficient setting means is configured to switch between the first coefficient and the second coefficient at a predetermined basic current value. Only the data of the respective necessary areas selected from the first and second coefficient data that change corresponding to the basic current value are combined with each other, and the combined data of the coefficients q and r are combined with the basic current. The current control device for a synchronous machine according to claim 3 , wherein the current control device is configured to store the values in correspondence with values. The current control device for a synchronous machine according to claim 1 or 2 , wherein the correction coefficient setting means is configured to switch the first coefficient and the second coefficient at a predetermined first predetermined rotation speed of the synchronous machine. . When the first coefficient is q1, r1 and the second coefficient is q2, r2, the correction coefficient setting means has a predetermined switching region between the first coefficient and the second coefficient,
q = s * q1 + t * q2
r = s * r1 + t * r2
(However, the coefficients s and t are s + t = 1)
The current control of the synchronous machine according to claim 1, wherein one of the coefficients s and t is gradually increased and the other is gradually decreased to set the coefficients q and r in the correction coefficient K. apparatus. The correction coefficient setting means has a predetermined rotation speed region about a predetermined second predetermined rotation speed as a center when the first coefficient is q1, r1 and the second coefficient is q2, r2. In
q = s * q1 + t * q2
r = s * r1 + t * r2
(However, the coefficients s and t are s + t = 1)
The coefficient q in the correction coefficient K is gradually increased by gradually increasing one of the coefficients s and t between the predetermined rotational speed region end and the second predetermined rotational speed. The current control device for a synchronous machine according to claim 1, wherein r is set. The current control device for a synchronous machine according to claim 7 , wherein the second predetermined rotation speed is determined based on a rotation direction resonance frequency of a drive system. The current control device for a synchronous machine according to claim 7 , wherein the second predetermined rotation speed is determined based on a resonance frequency of the structure of the synchronous machine. The correction coefficient setting means corrects the basic current by setting the coefficients s and t to s = 0 and t = 0 in a rotation speed region other than the predetermined rotation speed region having the second predetermined rotation speed as a center. The current control device for a synchronous machine according to any one of claims 7 to 9 , wherein the current control device is not configured. In order to reduce the p-order component of torque fluctuation and radial nodal force appearing when a basic current is applied to each phase coil of the synchronous machine, the basic current is set based on the p-order high-order frequency current component. A current control method for a synchronous machine that corrects by multiplying a correction coefficient,
K = [1 + qcos (pωt) + rsin (pωt)] is obtained as the correction coefficient, and the coefficients q and r in the correction coefficient K related to the amplitude value of the p-order high-order frequency current component are given. and sets the correction coefficient K set based on the first coefficient and the second coefficient of the radial nodal force for reducing the torque variation reduction,
A synchronous machine current control method, wherein the synchronous machine is driven and controlled by applying an application current obtained by multiplying the basic current by the set correction coefficient K to each phase coil.

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