JPH02206389A - Torque pulsation reducing method for reluctance motor - Google Patents

Abstract

PURPOSE:To perform torque control under such condition as pulsation of torque is reduced over a wide range by calculating such supply current, for each phase, as constant torque is produced according to a torque generation characteristic simply through measurement data for single phase of an n-phase reluctance motor. CONSTITUTION:A rotor position detection signal outputted from a rotor position sensor 4a incorporated in a three-phase reluctance motor 4 is fed to an operating section 1, where a read-out address is produced and fed to a pattern table 2. Exciting section for any one phase is split into such number of sections as corresponding to the number of phase. A current supply pattern for producing constant torque from a torque generation torque obtained from the measurement data is calculated for an independent section where only such phase as corresponding to any one section is excited, while a random supply current pattern is set for a complex section where the corresponding phase and other phases are excited simultaneously.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for reducing torque pulsation in a reluctance motor, and more specifically, the present invention relates to a method for reducing torque pulsation in a reluctance motor. The present invention relates to a novel method for reducing torque pulsation.

<Prior art and problems to be solved by the invention> Conventionally, as a mechanism for driving each axis of an industrial robot, a motor that rotates at high speed and a reduction mechanism with a large reduction ratio are generally used. , the shaft drive torque is increased.

However, when such a mechanism is adopted, the effects of backlash cannot be completely eliminated because the reduction mechanism is generally composed of multiple gears, and high positioning accuracy cannot be achieved. It is difficult to apply it to the necessary industrial robots.

In order to solve this problem, the adoption of a direct drive system that directly transmits the motor's rotational force to each axis is being considered, and it is possible to obtain a sufficiently large driving force when using the direct drive system. A reluctance motor is considered as a motor that can do this. This reluctance motor generates torque based on the difference between the energy supplied to the motor and the energy stored inside the motor. Specifically, since it is known that the mutual inductance of the three-phase reluctan smoke is significantly smaller than the self-inductance, the generated torque τ of the three-phase reluctan smoke is expressed as −(
1/2) (dLa/dem)ia2+ (1/2)
) (d L l) / dθm)iL+2+(1
/2) (dLe /dθm)ic2 (where, i is the current value, L is the self-inductance, subscripts a, b, and c are the phases, 0
m indicates the rotor position). However, pulsations occur in the generated torque due to the mechanical structure of the reluctance motor itself, so when incorporating it into an industrial robot, it is necessary to significantly reduce the pulsations in the generated torque. In order to achieve this, the supply current of each phase is controlled.
5PC-87-14°PP, 1-10.1987).

However, the torque control method described in JP-A-63-35194 completely ignores the effects of harmonics and magnetic saturation, and the torque control method described in ``Theoretical analysis of megatorque motor and its torque control method'' The control method completely ignores the effects of magnetic saturation, so even if it is actually incorporated into an industrial robot, there is a problem that it cannot effectively reduce torque pulsation, especially when it is necessary to obtain a large torque. be. In other words, the inductance changes greatly during one rotation of the reluctance motor, and this inductance change contains many harmonics, and the inductance change is affected by magnetic saturation, so supply that ignores these changes is difficult. Even if the current is controlled, it is impossible to control the generated torque over a wide range while significantly reducing pulsation.

In addition, if the actual measured value of the generated torque is obtained in advance and the supply current waveform is determined in response to changes in the rotor position, the effects of harmonics and magnetic saturation will be taken into account in the actual Δpl value, so pulsation will occur over a wide range. It is believed that it is possible to reduce the amount of torque generated while significantly reducing the amount of torque generated.

However, in order to obtain the actual measured value of the generated torque, it is necessary to calculate the Real A1
1j value would have to be obtained, and the capacity of the memo IJ to store a huge amount of actually measured values would become enormous, so it would be impossible to put this into practical use.

<Objective of the Invention> The present invention has been made in view of the above-mentioned problems, and is capable of controlling the generated torque while significantly reducing torque pulsation over a wide range.
The object of the present invention is to provide a method for reducing torque pulsation of a reluctance motor that can reduce the number of required actual measurement values by a wide range.

Means for Solving the Problem> In order to achieve the above object, the method for reducing torque pulsation of a 1-nolactance motor according to the present invention is such that each phase of a 1-nolactance motor has a phase difference of 2π/n electrical angle. In a control method for supplying current, the excitation section for any phase is divided into a number of sections based on the number of phases, and if any section or a single section where only the corresponding phase is excited, the excitation section is divided into sections based on the number of phases. A supply current pattern that keeps the generated torque constant is calculated based on the generated torque characteristics obtained, and an arbitrary supply current pattern is set as long as the corresponding F-th phase and other phases are excited at the same time. Alternatively, a supply current pattern that makes the generated torque constant when other phases are excited with an arbitrary supply current pattern is calculated based on the generated torque characteristics obtained from the measurement data, and a pattern in which the above supply current pattern is continuous. In this method, the supply current value of each phase is calculated based on the following, and the current of the calculated value is supplied to each phase.

Further, in a method for reducing torque pulsation of a reluctance motor according to another invention, an electrical angle of 2π is applied to each phase of an n-phase reluctance motor.
In a control method that supplies currents with different phases by /n, the excitation interval π for any phase is divided into m intervals (m is a natural number less than or equal to n), and only the phase to which any of the intervals corresponds is excited. If it is a single section where the phase is energized, the Nissl supply current pattern is calculated so that the generated torque is constant based on the measured data. A supply current pattern that makes the generated torque constant when an arbitrary supply current pattern is set or when other phases are excited with an arbitrary supply current pattern is calculated based on the generated torque characteristics obtained from 6PL constant data. , Calculate the supply current value of each phase based on a continuous pattern of the above supply current pattern,
This is a method of supplying a calculated value of current to each phase.

Further, a torque pulsation reduction method of still another invention is a control method for supplying currents having different phases by 2π/3 electrical angle to each phase of a three-phase reluctance motor, in which the excitation interval π for any phase is set to three. For the individual section where only the relevant phase is excited, a supply current pattern that keeps the generated torque constant is calculated based on the generated torque characteristics obtained from the measurement data, and the supply current pattern for the relevant phase and other phases is divided into For one of the composite sections where 1 and 2 are simultaneously excited, set the supply current pattern, and set the generated torque to a constant value when the other phase of the composite section is excited with an arbitrary supply current pattern. The supply current pattern to be apl
A method of calculating based on the generated torque characteristics obtained from constant data, calculating the supply current value of each phase based on a continuous pattern of the above supply current pattern, and supplying the calculated value of current to each phase. It is. In this case, it is preferable that the arbitrary supply current pattern be a function set to r.

In these cases, the generated torque characteristics may be those obtained by performing interpolation calculations based on discretely measured data.

Effect> With the torque pulsation reduction methods of the first and second inventions described above, even if the number of phases of the reluctance motor is n, the electrical angle for one phase is within the range of 0 to π or I to 2π. Apj constant data only in ? 7 should be set, harmonics,
A supply current pattern for one phase that keeps the generated torque constant can be calculated based on the generated torque characteristics that take into account the influence of magnetic saturation. For other phases, the above supply current pattern is changed to the number of phases n1. : It is only necessary to apply a phase difference by a predetermined electrical angle determined based on the electrical angle, that is, an integer multiple of the electrical angle 2π/n, and the torque control of the reluctance motor can be performed with torque pulsation being significantly reduced over the entire range. can be done.

In these cases, when calculating the supply current pattern, the excitation section may be divided into sections whose number is greater than the number of phases, and the supply current may be calculated for each section. If the number of sections is equal to or less than the number of sections, the calculation of the supply current for each section can be reduced. In the latter case, for example, if the number of phases is 3, the excitation section may be divided into three sections, and if the number of phases is 4, the excitation section may be divided into two sections. It turns out.

In the torque pulsation reduction method of still another invention, although the number of phases of the reluctance motor is three, the excitation section is divided into three sections for one phase.

Since only the corresponding phase is excited in the central section of the three divided sections, a supply current pattern that keeps the generated torque constant is calculated based on the generated torque characteristics obtained from the measured data. I can do something. Then, in the remaining sections, the corresponding phase and other phases are excited at the same time, so an arbitrary supply current pattern is set for the -/i section, and the other rivers are set at an arbitrary supply current pattern for the other sections. A supply current pattern that makes the generated torque constant when excited with the supplied current pattern can be calculated based on the generated torque characteristics obtained from the measurement data. As a result, if the above three OI-supply current patterns are made consecutive, a supply current pattern for the entire excitation section can be obtained, so for other phases, the obtained supply current pattern is phased by 2π/3 electrical angle. By applying these in different states, it is possible to perform torque control of the reluctance motor in a state where torque pulsation is significantly reduced over the entire range.

In the second case, if the arbitrary supply current pattern is a function set to T, for example, a -dimensional number, the supply current pattern can be calculated in the cylinder.

Even in the above-mentioned invention, if the generated torque characteristic can be calculated by performing an interpolation calculation based on discretely determined data, then j
all within the range that does not significantly reduce the accuracy of the data that can be
It is possible to reduce the amount of data.

That is, the generated torque r (0 m
, i a, i b, i c) (where, i is the current value, subscripts a, b, c are the phases, and 0m is the rotor position) is r (θm, i a, i b, i c) −ra(θm
, ia, ib, ic) + rb(θm, i a, ib, i
c) 10 re(0m, i a, i b+ i c), and although the mutual inductance of a reluctance motor is extremely small, ra(θtn, i
a, i b, i c)', r a(θffl, i
a, o, 0) rb(θm, ia, ilt, ic) rb(θm, o, i mu, o) re(θffi
, ia, i 13. i c): r c(θm,
O, O, ic), and as a result, the generated torque (θra, ia, ib, ic)
m r a (θi, ia, 0.0) 10 rb (θm, 0
．． i b, 0) + re(θa+, o, O, i
It can be approximated as c). Therefore, the necessary fruit 1
The 111 value is required only during one-phase excitation, and three-dimensional data can be converted into one-dimensional data.

If the number of pole pairs is p and the electrical angle is 00, the characteristics between each pole are equal, so r(θc, ia, i b, ic) - r(θc
+2nπ/p, ia, ib, 1c) (where n is any integer), and the necessary actual jPJ value only needs to be within the electrical angle range of 0 to 2π, and is 1/ of the number of data for the entire rotation range. can be reduced to p.

Also, since the characteristics between each phase are the same, rB(θe
, ia, ib, ic)=rb(θe-2y
r/3. ia, il), 1e)-re(θe +2yr
/3. ia, ib, ic), and the actual measurement values required are only for one phase, which can be reduced to 1/3.

Furthermore, if the characteristics of each phase are symmetrical, τ(θe,
i a, i b, i e) --τ(-θe, i
a, i b, ic), and the actual measurement values required are only for one symmetrical section, and can be reduced to 1/2.

Therefore, by considering these, the necessary actual Ap
The number of + values can be significantly reduced, and A#1
If fixed values are obtained discretely and intermediate values between the measured values are obtained by interpolation, the number of required actual measured values can be further reduced. Then, the required output torque τ*r*mr (θta, i a, i b
, i c) The supply current i of each point necessary to obtain
By determining a, i b, and i c based on the above-mentioned measured values, it is possible to perform torque control of the reluctance smorph with significantly less torque fluctuation, that is, with significantly less torque pulsation.

Although only the three-phase reluctance morph has been described in detail above, the same applies to a roughtance motor with any number of phases.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing embodiments.

FIG. 4 shows 11 for implementing the torque pulsation reduction method of the present invention.
It is a block diagram showing the electrical configuration of the lactance motor control device, and stores the generated torque pattern when the torque command value supplied from a host controller (not shown) is human power and current is supplied only to one of the phases. A calculation unit (1) calculates the supply current value for each phase by reading the supply current value from the pattern table (2) and performing predetermined calculations; A power converter (3) that exchanges the power into supplied power, and a three-phase reluctance motor (4) that rotates to generate a commanded torque by being supplied with the power converted by the power converter (3). -H, and supplies the rotor position detection signal output from the rotor position sensor (4a) incorporated in the three-phase reluctance motor (4) to the two-leg calculation unit (1), Arithmetic unit (1
) is read 1. Generate an address and use the pattern table (2)
).

Note that the pattern table (2) stores generated torque patterns that indicate changes in generated torque when current is supplied to only one of the phases based on actual measured values. A plurality of generated torque patterns corresponding to the case where the torque is changed are stored (see FIG. 5).

FIG. 1 is a flowchart showing an embodiment of the torque pulsation reduction method of the present invention, in which only each phase of the three-phase reluctance smoke is DC-excited in advance to operate the reluctance smorph, and the The generated torque pattern is determined and stored in the pattern table (2).

After the torque command value τ* and the rotor electrical angle θC are input manually in step (2), the polarity of the torque command value τ* is determined in step (2).

If it is determined that the torque command value τ* is negative, the section is determined according to the electrical angle θe in step (■).
Figure 2 (BD). And the electrical angle θe is 0 to π/3, π
/3~2π/3.2π/3~π, π~4 π/3.4
Sections from π/3 to 5π/3, 5π/3 to 2π (Fig. 2B
The supplied current corresponding to the electrical angle θC is determined in each step (2) to (phase) corresponding to which of the middle intervals (see middle intervals (2) to (2)) it belongs to.

For example, if the electrical angle θC is in the interval ■, the supply current ia corresponding to the electrical angle θe is determined in step ■ so that τ*-τa (θe, ia, o, 0). At this time, both supply currents i b and i c are set to O. Specifically, the supply current ia is determined as shown in FIG. 3A based on a plurality of generated torque patterns stored in a pattern table, but the generated torque patterns are only obtained discretely. So, for example,
When the electrical angle is θe and the supplied currents are ial and ia2, the generated torque is ra1 ra2, and r
If al<τ*kura2, the above supply current ia is ia (θc) −1al+ f(r*−ral)
/ (ra2- ral)l (i a2- i
al) can be obtained by performing the calculation. However, instead of the above linear interpolation calculation, a high-order interpolation calculation may be performed to improve the approximation accuracy.

Furthermore, if the electrical angle θe is in section I, each electrical angle θe; θe+2π/ Supply current i for 3
Find a, ic. At this time, the supply current ib is set to 0. However, the supply current i a that satisfies the above relationship,
Since there are many ic's, it is not possible to define them unambiguously. Therefore, specifically, for example, the pattern of the supply current ia in the section work is a linear pattern (as shown in FIG. 3B, in the case of θ-θ0, it is 1a-0,
In the case of 1a-II (however, 11 is r*-ra(θ
1. I 1°0.0)), and the supply current ie (see FIG. 3C) may be calculated based on the supply current ia in section I and the above relationship. In this case as well, interpolation calculations are of course performed as necessary.

Further, even if the electrical angle θe is in a range other than the above, the supply current 1a-ic can be determined in the same way.

Further, even if it is determined in step (2) that the torque command value τ* is greater than or equal to 0, the section is determined in step (2) according to the electrical angle θC (see FIG. 3C). Then, the supply currents ia - ic can be determined in the same manner in steps ① to [YES] corresponding to the determined sections.

Therefore, in step @, by supplying power based on the supply currents i a, i b, and i c obtained as described above, 3-citrus relactan smoke (4
) can be operated.

As is clear from the above explanation, the pattern of the supply current to the 3-citrus relactan smoke (4) is calculated so that the generated torque τ* is constant, taking into account the effects of harmonics and magnetic saturation. Therefore, torque control with significantly reduced torque pulsation is realized, and extremely high positioning accuracy can be achieved by using it as a drive source for direct drive of industrial robots.

Furthermore, since it is sufficient to store the actual measured values discretely in the pattern table (2), the number of required actual measured values can be significantly reduced.

Furthermore, since the torque actually generated becomes linear compared to the torque command value, the load on the host controller is reduced.

When the rotation direction of the three-phase reluctan smoke (4) is set to be reversed, a series of processes similar to those described above may be performed while the direction of increase in electrical angle is reversed.

The above describes the case where the actual measured value of the generated torque pattern is stored in the pattern table (2) and the supply current is calculated online. 2) It is also possible to store the supply current pattern. In this case, the calculation time in the arithmetic unit can be reduced by a large amount [1] compared to the case of the above embodiment. Figure 6A is the torque command value τ
The supply current pattern when * is negative, and B in the figure is the supply current pattern when the torque command value τ* is 0 or more, and the supply current can be calculated in the same manner as described in the above embodiment. However, as is clear from FIG. 3, for example, section 1. By calculating the current waveform only for section II, and for the supply current ia of section ■, moving the supply current ic of section I by i12 rows, the current waveform is calculated for section 1. II.

The waveform of the supply current ia for (2) can be obtained.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied, for example, to torque control of a reluctance smorph with a phase number of It is possible to set the current nozzle as a straight line, and furthermore, it is possible to set the supply current pattern in section I or section ■ to a function pattern other than a straight line. It is possible to calculate the pattern of supply currents i a and i c in section I by taking into account the constraint that minimizes Is possible.

<Effects of the Invention> As described above, the first invention allows harmonics,
A supply current pattern that keeps the generated torque constant can be calculated for each phase based on the generated torque characteristics that take into account the effects of magnetic saturation, and torque control can be performed with torque pulsation significantly reduced over a wide range. It has the unique effect of being able to

The second invention also provides a supply current pattern that keeps the generated torque constant based on the generated torque characteristics that take into account the effects of harmonics and magnetic saturation by simply obtaining measurement data for one phase of a 0-phase reluctance motor. Calculations can be made for each opening, and the unique effect is that torque control can be performed in a state where torque pulsations are significantly reduced over a wide range.

The third invention divides one phase of a three-phase reluctance motor into three electrical angle ranges of O to π or π to 2π, and for one divided section, the supply current of other phases is divided into three parts. The pattern is calculated without consideration, an arbitrary pattern is set for one of the remaining sections, and the pattern is calculated considering the set pattern for the other, so the calculation section is set within the electrical angle range of 2π/3. Moreover, it has the unique effect of being able to perform torque control in a state where torque pulsation is significantly reduced over a wide range.

The fourth aspect of the present invention has the unique effect that since any supply current pattern is a preset function, for example, a -order function, the supply current pattern can be easily calculated based on this function.

In the fifth invention, since the generated torque characteristic is obtained by performing interpolation calculation based on discretely measured data, n1 constant data can be obtained within a range where the accuracy of the data obtained by interpolation calculation does not decrease much. This has the unique effect of reducing the number of

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an embodiment of the torque pulsation reduction method of the present invention. FIG. 2 is a schematic diagram showing the current supply status of each phase in the electrical angle range of 0 to 2π. FIG. 4 is a schematic diagram illustrating the supply current pattern; FIG. 4 is a block diagram showing the electrical configuration of a reluctance motor control device implementing the torque pulsation reduction method of the present invention; FIG. 5 is a diagram illustrating the generated torque pattern; Figure 6 shows the supply current pattern. (1)...Arithmetic unit, (2)...Pattern table,
(4)...Three-phase reluctan smoke, (1) [n]
(110... section

Claims (5)

[Claims] 1. At each phase of an n-phase reluctance motor Supply current with different phases by a constant electrical angle In the control method that The number of excitation sections to be set is based on the number of phases. Divide into sections, and any section is applicable. If it is a single section where only the phase is excited, measurement is possible. Generated torque characteristics obtained from constant data Supply that keeps the generated torque constant based on Calculate the current pattern and select the appropriate phase and and other phases are excited at the same time. If so, set any supply current pattern or other phases with any supply current pattern. The generated torque is constant when excited by the The measured data shows the supply current pattern Based on the generated torque characteristics obtained by Continuously calculate the above supply current pattern. The power supply for each phase is determined based on the Calculate the current value and apply the calculated value of current to each Reluctor characterized by supplying the phase method for reducing torque pulsation in motors. 2. Power is applied to each phase of an n-phase reluctance motor. Provides currents with different phases by 2π/n air angles. In the control method that supplies m excitation intervals π (m is less than or equal to n) natural numbers), and any of the intervals A single section where only the corresponding phase is excited If so, the occurrence obtained from the measured data Constant generated torque based on torque characteristics Calculate the supply current pattern to phase and other phases are energized simultaneously For composite sections, any supply current pattern is possible. set the phase, or provide any other phase. Triggers occur when excited with the supply current pattern. The supply current pattern that keeps the torque constant is Generated torque characteristics obtained from measurement data The above supply current pattern is calculated based on each pattern based on a continuous pattern. Calculate the phase supply current value and calculate the calculated value It is characterized by supplying current to each phase of Reducing torque pulsation in reluctance motors Method. 3. 2 electrical angles for each phase of the 3-phase reluctance motor (4)
In a control method that supplies currents with different phases by π/3, the excitation interval π for any phase is divided into three intervals (I), (II), and (III).
For the individual section (II) where only the relevant phase is excited, a supply current pattern that keeps the generated torque constant is calculated based on the generated torque characteristics obtained from the measurement data, and the supply current pattern that keeps the generated torque constant is calculated. Set an arbitrary supply current pattern for one of the composite sections (I) and (III) where the phases are simultaneously excited, and set the generated torque when the other phase is excited with the arbitrary supply current pattern for the other compound section. The supply current pattern to be kept constant is calculated based on the generated torque characteristics obtained from the measurement data, the supply current value of each phase is calculated based on a continuous pattern of the above supply current pattern, and the calculated value is A method for reducing torque pulsation in a reluctance motor, characterized by supplying current to each phase. 4. Any supply current pattern can be set in advance. Claim 3, which is a function of Torque pulse of reluctance motor described in section dynamic reduction method. 5. A data whose supply current characteristics are measured discretely. to perform interpolation calculations based on the data. Claim 1 of the above claim obtained from Reluctan according to any of Item 4. Method for reducing torque pulsation in motors.