JPH1118471A - Controller for synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a motor stably and efficiently by calculating a phase compensation amount with reference to a rotor speed calculated from a rotor position, determining a code from the polarity of a torque command value and then determining a phase compensation amount being applied to the rotor position. SOLUTION: A current command value SIC is subjected to phase distribution through a phase distributor 7 before a phase U current command SIUC and a phase V current command SIVC are delivered to an amplifier 8 (in the case of three-phase, the command values are produced for only two phases because the command value for one remaining phase is determined automatically). A drive current is applied from the amplifier 8 to a motor 9. The motor 9 is fixed with a rotor position detector 10, producing a rotor position SP. The rotor position SP is converted through a differentiator 11 into a rotor speed SPD, which is delivered to the field current operating section 15 in a current command value operating section 15, the gain-correcting section 13 in a correcting section 12 and a phase-correcting section 14, in order to calculate a correction value applied to the motor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a synchronous motor used in machine tools, industrial machines, electric vehicles, etc., and more particularly to a control device for improving control characteristics of a synchronous motor.

[0002]

2. Description of the Related Art A conventional control block diagram is represented by three phases (U, V,
FIG. 8 shows an example of control in (W phase). The speed command value SVC is instructed by the host controller, and the subtracter 1 calculates the difference DIF from the rotor speed SPD. The DIF outputs the armature current command value STC to the current command calculation unit 5 by the PI controller 2. The field current calculation unit 81 outputs a field current command value SFC to the current command calculation unit 5 according to the field current pattern with reference to the rotor speed SPD. The current command calculation unit 5 refers to the rotor position SP (mechanical angle) and converts it into an electrical angle, and then converts the armature current command value STC and the field current command value SFC
To obtain a current command value SIC. (The phase difference between the armature current command value STC and the field current command value SFC is π / 2 [rad] in electrical angle.) Then, the phase difference (2π) / 3 between the U-phase current command value SIUC and it or (4π)
A V-phase current command value SIVC of / 3 [rad] is calculated.
If two of the three phases are determined, the current of the remaining W phase (SIW
C) is not shown because it is determined. The current command value of each phase is applied as a three-phase current to the motor 9 via the amplifier 8 to rotate the rotor of the motor 9. A rotor position SP is obtained by a detector 10 as rotor position detecting means attached to the rotor, and a current command calculator 5 and a differentiator 12
Will be fed back. Differentiator 12 has rotor position SP
Is differentiated and output to the subtractor 1 and the field current calculator 81 as the rotor speed SPD. As can be seen from the above operation, the current command value SIC (after phase distribution, SIUC, SIV
C) is the field current command value SFC and the armature current command value STC
Is made by vector addition. In addition, when controlling, the induced voltage according to the rotor speed and the field of the rotor (Id component in a vector diagram; in the case of a permanent magnet, it can be regarded as equivalent to flowing a fixed field current component). Occur between the stator winding terminals.

[0003]

When a conventional control device is used, the rotor speed, the field of the rotor (Id component in a vector diagram; a fixed field current component also flows in the case of a permanent magnet). An induced voltage corresponding to the stator winding terminals is generated between the stator winding terminals. Therefore, if the rotation speed becomes higher than the base rotation speed (the rotation speed in a region where field weakening is not performed), the terminal The inter-voltage exceeds the power supply voltage, and the efficiency of power injection from the control device (particularly, the amplifier) is reduced. As a result, the actual current does not follow both the amplitude and the phase with respect to the large current command value. In particular, in the case of vector control in which the reluctance motor is operated separately for the field current and the armature current, the delay in phase means that the phase is delayed by π / 2 from the armature current component of the actually flowing combined current. As the ratio of the magnetic current component increases, there is no effect even though the field weakening control is performed, and the armature current component decreases, so that there is a problem that a desired torque cannot be obtained. . When the number of turns of the winding is large (for example, when the base rotation speed is designed to be low), the winding inductance increases. As a result, when the rotation speed increases, the frequency of the current for controlling increases. Z = R + j
ωL (R: winding resistance, ω: angular frequency, L: winding inductance) also increases. For this reason, the voltage drop due to the winding increases and the voltage used effectively decreases, which may also cause a phase delay. In addition, an increase in the winding inductance means that the current response time constant (t = L / R
sec) becomes longer, and it becomes impossible to respond to a change in a current command having a high frequency at the time of high rotation. This also causes a phase delay and a delay in following the amplitude. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a synchronous motor control device capable of realizing stable and efficient motor control with a simple configuration.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synchronous motor control device for obtaining a rotating torque of a rotor by a field obtained from a permanent magnet or a stator winding and an armature current of the stator. A control device comprising: a means for detecting a rotor position of the electric motor; and a current command calculation unit for calculating a current command from the rotor position and a torque command value in order to supply a current to the motor. Means for calculating a rotor speed from the rotor position and calculating a phase compensation amount with reference to the rotor speed, wherein the sign is determined based on the polarity of the torque command value, and then the phase compensation amount is added to the rotor position. And a means for calculating the rotor speed from the rotor position and calculating the gain compensation amount by referring to the rotor speed, and determining the sign based on the polarity of the torque command value. ,torque A gain compensation calculation unit for calculating the gain compensation amount to be multiplied by the command value, and a phase compensation calculation unit and a gain compensation calculation unit including a function pattern that can be set from outside the control device and has a rotor speed as a parameter; Is achieved by According to the present invention, an efficient control device is obtained by calculating the correction value of the phase and gain of the current applied to the electric motor based on the rotor speed and adding the correction value to the current command value. In addition, an advantage that stable control can be performed is obtained.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Unless otherwise specified, those having the same symbols and numbers have the same functions and performances. FIG. 1 is a specific example of the embodiment of the present invention. The speed command value SVC is instructed from the host controller, and the difference DIF from the rotor speed SPD is calculated by the subtractor 1. Deviation DIF is PI
The controller 2 outputs the torque command value STC to the current command calculation unit 4. The current command calculation unit 4 includes an armature current calculation unit 5 and a field current calculation unit 15, and the armature current calculation unit 5 corrects the rotor position SP and the phase correction value SAC by using an adder 16. With reference to the rear rotor position SPC,
Armature current command value SIQ is output to adder 6 from torque command STC. Further, the field current calculation unit 15 outputs the field current command value SID to the adder 6 with reference to the rotor speed SPD and the corrected rotor position SPC. The adder 6 performs a vector operation on the armature current command value SIQ and the field current command value SID, generates a current command value SIC, and outputs it to the phase distributor 7. Note that the armature current command value SIQ and the field current command value S
The phase of the ID is shifted by π / 2 in electrical angle. Current command value S
The IC is phase-divided by the phase distributor 7, and the U-phase current command value SIU
The C and V phase current command values SIVC are output to the amplifier 8 (in the case of three phases, if the other two phases are determined, the remaining one phase is determined, so that only two phase command values are created. Not limited, W-phase current command SIWC (not shown)
May be commanded). A drive current is applied to the motor 9 from the amplifier 8. A detector 10 for detecting a rotor position is attached to the electric motor 9, and outputs a rotor position SP. The rotor position SP is determined by the differentiator 11 to obtain the rotor speed S.
It is converted to PD and output to the field current calculator 15 in the current command value calculator 4, the gain corrector 13 and the phase corrector 14 of the corrector 12.

FIG. 2 shows an example of a function pattern of the correction unit 12. The correction section 12 includes a gain compensation operation section 13 for correcting a gain (amplitude) and a phase compensation operation section 14 for correcting a current phase. The gain compensation calculation unit 13 uses the rotor speed SPD as a parameter to set the gain correction coefficient S
A function pattern (a) for outputting GC is set. The phase compensation calculation unit sets a function pattern (b) that outputs the phase correction value SAC using the rotor speed SPD as a parameter. The setting of the function pattern is not limited to the method set from the outside, but may be stored in advance in the controller internal memory as a function expression or a data map.

FIG. 1A shows a function pattern for outputting a gain correction coefficient SGC with respect to the rotor speed SPD. At low rotation speed, the correction coefficient is 1.0 and the gain is not corrected. In order to correct a decrease in gain due to a response delay, SGC> 1.0. This function pattern can be set to SGC <1.0 (gain reduction) depending on the method of use, and can be set arbitrarily according to the desired control method. Figure (b) shows the rotor speed SP
This is a function pattern that outputs a phase correction value SAC to D. The phase correction value at low rotation takes a small value. However, in order to correct the phase lag at high rotation, the phase correction value increases as the rotor speed SPD increases. The pattern is set such that the value SAC increases. This function pattern can also be set arbitrarily, and when a motor that does not cause a phase delay is used, the phase correction value can be set to 0 (that is, a flat function).

FIG. 3 shows a basic conceptual diagram of the present control (control by vector operation). Field current command SID (I
d) 31 with a phase of π / 2 or (3/2) π
[Rad] A vector of the shifted armature current SIQ (Iq) 32 is synthesized to calculate a current command SIC (Io) 33. The current that actually flows is the combined current SIC (Io) 33. Next, FIGS. 4 to 6 illustrate problems (related to phase delay and amplitude reduction of current) of the conventional control device. FIG. 4 illustrates a problem caused by a phase delay with reference to a vector diagram. In the present control method, the motor is driven by instructing the amplifier the combined current Io obtained by performing a vector operation of the field current command Id (d-axis current component) and the armature current component Iq (q-axis current component) as shown in FIG. As described in the above. Assuming that the actual current when a phase delay of Δθ is generated with respect to the current command (synthetic current) Io is Ires42, the apparent field current component Idr44 increases by ΔId with respect to the command value, and the armature current component Iqr46 becomes It will decrease by ΔIq. An increase in the field current component means that the voltage between the terminals increases.In particular, when performing the field weakening control, the field weakening effect is lost even though the field weakening is performed. I will. In addition, a decrease in the armature current component causes a decrease in output torque, which causes a problem that the motor to be controlled does not operate as desired.

FIG. 5 shows a specific example of a waveform when an analog (continuous) current command 51 under control is given. When the control is performed at a low speed, the actual current 52 flows almost as instructed, and it has been experimentally confirmed that the delay time Δt ≒ 0. When the control is performed at a high speed, a phase delay Δθ occurs with respect to the command value as shown in FIG. 5, and the amplitude is also reduced.

FIG. 6 shows a specific example of a waveform when a digital (discrete) current command 61 being controlled by a microprocessor is given. (A) shows the current command 61 and the actual current waveform 62 at the time of low rotation, and (b) shows the current command 63 and the actual current waveform 64 at the time of high rotation. Although the current command is expressed in digital form, the actual current is expressed in analog form in the amplifier, and the waveform is also expressed in analog form (however, the present invention is not limited to this combination). In the low-speed rotation of (a), the sine wave can be expressed smoothly because the sampling number of the current command value 61 is large. For this reason, the actual current 62 substantially follows the analog command (however, strictly speaking, the following delay occurs with respect to a step-like waveform (including a high frequency component) generated at the time of sampling). Although there is no problem with the command value). At the time of the high-speed rotation in (b), the current command value 63 has a step-like shape as shown in the figure, but is almost close to a rectangular wave. This is because the frequency of the current is close to the control frequency, so that the processing time of the microprocessor is limited, and the number of samplings representing a sine wave is reduced. For a high-frequency waveform such as a square wave, a time constant due to inductance (t = L / R; L is a winding inductance and R is a winding resistance), a time constant specific to an amplifier or a controller, etc. For this reason, the actual current waveform 64 has a larger delay than the actual control. In the case of the waveform of this example, the electric angle is delayed by about π / 4, the armature current component of the actual current is almost zero, and the field current component is larger than the command. The induced voltage exceeds the power supply voltage and falls into an uncontrollable state.

FIG. 7 shows a waveform of current control during high rotation (digital) according to the present invention. 4 shows a current waveform when the phase and gain of a current command during high-speed rotation are corrected. Waveform 73
Is a current command value that the user actually wants to flow, and a waveform 74 is a response waveform (phase lag and amplitude reduction have occurred) to the current command value in the related art. A waveform 71 is a current command value when the phase / gain correction is performed according to the present invention, and a waveform 72 is a response to the command value. It can be seen that the current waveform 73 actually desired to flow and the corrected actual current waveform 72 substantially coincide in both amplitude and phase. In this way, by correcting the phase and the gain with respect to the rotation speed,
The control device can control the field current component and the armature current component as designed, and can avoid a problem such as inability to control.

[0012]

As described above, according to the control apparatus for a synchronous motor shown in the present invention, since the correction unit including the gain and phase compensation calculation unit that changes with reference to the rotor speed is provided, the motor winding The phase delay and amplitude reduction of the actual current with respect to the current command generated at the time of high-speed rotation caused by the inductance, amplifier, and controller of the motor are reduced, and the control can be performed by the current of the current phase and amplitude that should actually flow. Problems such as being disabled have decreased. further,
Non-linear torque characteristics such as torque decrease due to phase lag can be controlled like a motor having good linearity characteristics. The present invention is not limited to the embodiment of the present invention shown in FIGS. 1 to 6 described above, and the following modifications may be made without departing from the gist of the present invention. (1) In the present embodiment, the control method in which the field current command and the armature current command are vector-operated to be a current command has been described. After determining whether the operation angle is positive or negative, the operation angle (signed) is shifted from the axis corresponding to the q-axis of the vector control, which is also effective in a method of performing control equivalent to the vector control. (2) In the present embodiment, the motor having the rotor has been described, but the present invention may be applied to a linear motor having a structure having a mover.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a control device for a synchronous motor of the present invention.

FIG. 2 is an example of a function pattern of a correction unit provided in the control device for a synchronous motor of the present invention.

FIG. 3 is a vector diagram of current calculation of the synchronous motor control device of the present invention.

FIG. 4 is a vector diagram showing an example of a current command and an actual current according to the related art.

FIG. 5 is an explanatory diagram showing an example of a current command and an actual current waveform in the case of a conventional analog waveform.

FIG. 6 is an explanatory diagram showing an example of a current command and an actual current waveform in the case of a digital waveform according to the related art ((a) at low speed, (b) at high speed).

FIG. 7 is a comparative explanatory diagram showing an example of a current command and an actual current waveform in the case of the present invention and the prior art.

FIG. 8 is an example of a control block diagram of a conventional synchronous motor.

[Explanation of symbols]

Reference Signs List 1 subtractor, 2 PI controller, 3 adder, 4 current command calculator, 5 armature current calculator, 6 adder, 7 phase distributor, 8 amplifier, 9 motor, 10 detector, 11
Differentiator, 12 correction unit, 13 gain compensation calculation unit, 1
4 phase compensation calculation unit, 15 field current calculation unit, 16 adder, 21 function patterns, 22 function patterns, 31
Field current command vector, 32 armature current command vector, 33 combined current command vector, 41 combined current command vector, 42 combined actual current vector, 43 field current command vector, 44 field actual current vector, 45 armature current command Vector, 46 armature actual current vector, 51
Analog current command waveform, 52 analog actual current waveform,
61 Digital current command waveform, 62 Actual current waveform, 63
Digital current command waveform, 64 actual current waveform, 71 corrected digital current command waveform, 72 corrected actual current waveform,
73 digital current command waveform before correction, 74 actual current waveform before correction, 81 field current command calculation unit.

Claims (3)

[Claims] 1. A control device for a synchronous motor that obtains a rotating torque of a rotor by a field obtained from a permanent magnet or a stator winding and an armature current of a stator, wherein a rotor position of the motor is provided. And a current command calculating unit for calculating a current command from the rotor position and a torque command value in order to pass a current through the motor, wherein a rotor speed is calculated from the rotor position. And a means for calculating a phase compensation amount with reference to the rotor speed, and a phase compensation calculation unit for calculating the phase compensation amount added to the rotor position. 2. The synchronous motor control device according to claim 1, further comprising: means for calculating a rotor speed from a rotor position and calculating a gain compensation amount with reference to the rotor speed. A control device for a synchronous motor, comprising: a gain compensation calculation unit that calculates the gain compensation amount to be multiplied by. 3. The synchronous motor control device according to claim 1, further comprising a phase compensation operation unit and a gain compensation operation unit having a function pattern that can be set from outside the control device and has a rotor speed as a parameter. A control device for a synchronous motor.