JPH03169292A - Torque detection method for synchronous motor - Google Patents

Abstract

PURPOSE:To improve the reliability of detection by performing a vector product operation on the basis of a field flux vector and armature current vector and by detecting the generated torque of a synchronous motor by means of an instantaneous value. CONSTITUTION:A d-axis field flux signal and q-axis field flux signal are generated on the basis of a rotation angle detector 11 for detecting the magnetic pole angle of the revolving field rotor 1F of a synchronous motor SM. A d-axis armature ampere-turn signal and q-axis armature ampere-turn signal are generated on the basis of the output of a current detector 13 for detecting the armature current of the synchronous motor SM. Also, the value of the d-axis field flux signal and that of the q-axis armature ampere-turn signal are multiplied by a multiplier 18, and the value of the q-axis field flux signal and that of the d-axis armature ampere-turn signal are multiplied by a multiplier 19. Both multiplied values are added by an adder 20 for the purpose of performing a torque detection. Thus, the generated torque of the synchronous motor can accurately be detected with a high reliability without any mechanical torque transfer means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a torque detection method for detecting the torque generated by a synchronous electric motor by vector calculation.

[Conventional technology]

Torque detection of synchronous motors, etc. has conventionally been carried out using torque pickup via a joint 3 between the motor shaft of a three-phase synchronous motor (SM) 1 and the load shaft of a load (LOAD) 2, as shown in FIG. 4, for example. 4, or through a mechanical torque detection means, such as by using a load cell 5 as shown in FIG. 6 is an amplification means for amplifying the detection signal.

Torque detection using the torque pickup 4 described above is to detect torsional torque between the load shaft and the motor shaft in addition to the torque pickup 4, and torque detection using the load cell 5 is to detect the torsion torque between the load shaft and the motor shaft in addition to the torque pickup 4. It is stopped by a shaft 7 so as to be rotatable in the direction of the arrow, and the reaction torque is transferred to a load cell 5.
be detected in addition to.

[Problem to be solved by the invention]

Torque detection using the torque pickup 4, load cell 5, etc. requires mechanical transmission means for transmitting torque in addition to these, so extra space is required.
Since it is mechanically complex, there is an economical problem in that it is expensive, and detection errors are likely to occur due to play, resonance, and pulsating torque of this mechanical transmission means. In robots and the like, there is a problem in that it impairs the motion performance of the robot, and when using the torque pull-up 4, it cannot be used in a high-speed electric motor system.

The present invention was made in order to solve the above-mentioned conventional problems, and it is possible to accurately and reliably transfer the torque generated by a synchronous motor, which is often used as an AC servo motor, without using mechanical torque transmission means. An object of the present invention is to provide a method for detecting the torque of a synchronous motor.

[Means to solve the problem]

In order to achieve the above object, the present invention detects a d-axis field east signal and a q-axis field flux signal based on a rotation angle signal sent out by a rotation angle detector that detects the magnetic pole angle of a rotating field rotor of a synchronous motor. A d-axis armature ampere turn signal and a q-axis armature ampere turn signal are generated based on the output of a current detector that detects the armature current of the synchronous motor, and the value of the d-axis field flux signal and q A structure in which torque is detected by multiplying the value of the shaft armature ampere turn signal, multiplying the value of the q-axis field magnetic flux signal and the value of the d-axis armature ampere turn signal, and adding the above product values. It was something like that.

[Effect]

In the present invention, vector cross product calculation is performed based on the field east vector and the armature current vector, and the torque generated by the synchronous motor is detected as an instantaneous value.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, 10 is a control circuit, which together with a rotation angle detector 11 and a synchronous motor SM constitutes a brushless synchronous motor. Three-phase AC power is supplied to lines IU, IV, and IW.

The rotation angle detector l1 is, for example, an encoder or a resolver, and is a detector that detects the rotation angle of the magnetic poles N and S of the rotating field rotor IF, and is synchronized with the rotating field rotor IF of the synchronous motor SM. The rotation angle signal (pulse signal)
Send θ. 13 is the armature winding IU of the synchronous motor SM
, IV, and IW (hereinafter collectively referred to as ia) are current detectors (one phase is shown). Reference numeral 14 denotes a torque calculator, which includes a field east setting device 15, a magnetic flux vector calculator 16, a three-phase/two-phase converter 17, multipliers I8 and 19, and an adder 20.

This control circuit 10 is a control circuit that controls the speed or torque of the synchronous motor SM to a value commanded by a speed command S" or a torque command T", and after converting the power of an AC power supply AC to DC, a variable voltage/variable It has a power converter that converts the frequency into three-phase alternating current, and its control device, and the control device takes in the rotation angle signal θ and generates a phase signal whose phase matches the rotation angle signal θ. , controls the power converter so that the instantaneous value of the current ia output by the power converter becomes a three-phase AC having a phase based on the rotation angle θ, and performs feedback control to make the current ia follow the command value. .

The field east setter 15 of the torque calculator 14 inputs the rotation angle signal θ to the magnetic flux vector calculator 16, and sets the field rotor I.
A two-phase vector signal of the rotating field flux 41F on a stationary orthogonal coordinate system (d-axis and q-axis shown in FIG. 3) having the origin at the rotation center of F is generated.

(It)dF-ΦF cosθ・・・・・・・・・・・・
・(11(1)qF−=ΦFsinθ・・・・・・・・・
...(2) However, ΦF: Maximum amplitude of field flux θ - ωt, ω: Angular velocity 3-phase 2-phase converter 15 manually inputs the output of current detector l2 and converts the electric machine set on the above coordinate system. The following two-phase vector signal of the child ampere turn (rotation vector) I[{A'' is generated.

π BIdA=N−IA cos (ωt +
+ψ) ・− (3)2 π nlqA=N−I A sjn ((L) t +
+ψ) ... (4) 2 However, N・IIA one-man: armature ampere turn ■A
: Armature current vector 1A : Maximum amplitude of armature current N : Number of turns of armature winding ψ : Phase difference angle Now, when considering an ideal lossless synchronous motor, let N be the number of turns of armature winding IA. , armature ampere turn IH
Since A" = NXII^, the generated torque T1 of the synchronous motor SM is T"-II{^"X@F" - (MFXIHqA-4
+qFXIHdAπ 1ΦF −f{A cos ωt −sin
(ωt+ +ψ)2 π ΦF −1{A sin ωt −cos (
ωt+ +ψ)2 π =ΦF −HAsin (+ψ)2 1ΦF−HAcos ψ1ΦF −N・■ACOS
ψ・ ・ ・ ・ ・ ・ ・ ・ ・ (5) l
・The multiplier 17 of the rk calculator 14 is r @dPX IHq
AJ is calculated, and the multiplier 18 calculates r@qFXI[{dJ, and the outputs of both multipliers are added by the adder l9, so
The output of this adder 19 provides an instantaneous value T of the torque generated by the synchronous motor SM.

In this way, in this embodiment, the output of the rotation angle detector 11 is signal-processed to produce the field east vector (!I) dF, ◇qF, and the output of the current detector 13 is signal-processed to generate the electrical equipment. Since the child ampere turn vectors n{dA and If{qA are generated and torque is detected by calculating the cross product of these vectors,
Since the conventional mechanical transmission means described above is not required and the synchronous motor SM is directly detected, torque can be detected with extremely high precision compared to the conventional method.

Furthermore, since this detected value is an instantaneous torque value, it can be used as a feedback value for a high-speed response control system using the synchronous motor SM.

Furthermore, since the torque calculator 14 is composed of an electronic circuit and does not require a mechanical transmission means as described above, it can be made inexpensively and compactly, and requires only a small installation space.

Furthermore, since the torque calculator is of a stationary type and does not require a mechanical transmission means as described above, it can be used to detect the torque of the synchronous motor SM even if it is a high-speed machine. Unlike Sopu, it is not restricted by rotational speed.

〔Effect of the invention〕

As explained above, the present invention is designed to detect the generated torque of the synchronous motor by processing the output signal of the rotation angle detector and the output signal of the current detector of the Brass synchronous motor and performing a hexle calculation. Therefore, unlike when using a conventional torque detector, there is no need for a mechanical transmission means for transmitting the generated torque to the torque detector, so there is no detection error caused by this mechanical transmission means, and therefore, In addition to being able to perform extremely high-precision torque detection, since it is a stationary type, the range of use is not restricted by the rotational speed of the synchronous motor, and the advantage is that these effects can be obtained at a low cost. be.

[Brief explanation of the drawing]

Fig. 1 is a block configuration diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing the main parts of the above embodiment, and Fig. 3 is a diagram showing the field flux of the synchronous motor and the d and q axes of the armature ampere turn. The Hector diagram, FIGS. 4 and 5 are diagrams for explaining the conventional torque detection method. 1 - synchronous motor, IA - armature winding, IF - rotation field loke, 12 - current detector, 13 - rotation angle detector, 1 4
-Torque calculator, 15-・Field east setting device, 16-3 phase/
Two-phase converter, 17 - magnetic flux vector calculator, l8, l9 - multiplier, 20 - adder.

Claims (1)

[Claims] Generating a d-axis field flux signal and a q-axis field flux signal based on a rotation angle signal sent out by a rotation angle detector that detects a magnetic pole angle of a rotating field rotor of a synchronous motor and the magnetic flux generated by the magnetic pole,
A d-axis armature ampere turn signal and a q-axis armature ampere turn signal are generated based on the output of a current detector that detects the armature current of the synchronous motor, and the value of the d-axis field flux signal and the q-axis armature ampere are calculated. Synchronization characterized in that torque detection is performed by multiplying the value of the turn signal, multiplying the value of the q-axis field flux signal and the value of the d-axis armature ampere turn signal, and adding both of the multiplied values. Electric motor torque detection method.