JPH03173387A - Controller for synchronous motor - Google Patents

Abstract

PURPOSE:To permit control with a high reliability without employing any mechanical torque transmitting means by a method wherein the outer-product operation of a vector is effected based on the vector of magnetic field flux and the vector of armature current to detect the generating torque of a synchro nous motor, compare it with a torque commanding value and detect a difference between both values. CONSTITUTION:A magnetic flux vector operator 17 produces the rotary field flux vectors PHIdF, PHIqF of a static orthogonal coordinate system having (d) axis and (q) axis having an original point at the rotary center of a magnetic field rotor 1F based on a magnetic flux PHIF, set by a magnetic flux setter 16, and a position feedback signal thetaf. A 3-phase/2-phase converter 18 produces armature ampareturn vectors 1HdA and 1HqA set on the coordinates based on the outputs of current detectors 15A, 15B. A multiplier 19 operates PHIdFX1 HqA and another multiplier 20 operates PHIqFX1HdA while both outputs are added in an adder 21 to obtain the instantaneous value T of the generating torque of a motor. An error amplifier 22 amplifies a torque command To from a torque commander 102 and the difference T of a detecting torque T to input them into a controller 100 and control the torque with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device that controls the torque of a synchronous motor to be constant.

[Conventional technology]

AC using synchronous motors for tension control and robot control
Although servo motors have come into widespread use, torque detection for synchronous motors has conventionally been performed using the motor shaft and load (L) of a three-phase synchronous motor (SM) 1, as shown in Fig. 4.
This is done through a mechanical torque detection means, such as by connecting a torque pickup 4 to the load shaft of the OAD) 2 via a joint 3, or by using a load cell 5 as shown in FIG. ing. 6 is an amplification means for amplifying the detection signal.

Torque detection using the torque pickup 4 involves detecting torsional torque between the load shaft and the motor shaft in addition to the torque pickup 4, and the load cell 5
In torque detection using the motor stator, the motor stator is rotatably stopped by the shaft 7 in the direction of the arrow, and the reaction torque is applied to the load cell 5 for detection.

[Problems to be Solved by the Invention] When trying to detect torque using the torque pick amplifier 4, load cell 5, etc. and compare the detected torque value with a torque command value to control the torque of the synchronous motor, other than these may be used. Since this requires a mechanical transmission means to transmit torque, it requires additional space and is mechanically complex, resulting in an economical problem in terms of cost. , resonance, and detection errors due to pulsating torque are likely to occur.In addition, this mechanical transmission means is a cause of inhibiting the motion performance of robots, etc., and when using the torque pickup 4, it is difficult to use in high-speed motor systems. The problem was that it could not be used.

The present invention has been made in order to solve the above-mentioned conventional problems, and is to control the torque generated by a synchronous motor to a torque command value accurately and with high reliability without using mechanical torque transmission means. An object of the present invention is to provide a control device for a synchronous motor that can perform the following functions.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a signal input terminal for inputting a rotation angle signal of a rotor of a synchronous motor, a value of the rotation angle signal and the above synchronization set in a magnetic flux setting device. A magnetic flux vector calculator that generates a d-axis field flux signal and a q-axis field flux signal based on the magnetic flux values generated by the magnetic poles of the rotor of the electric motor, a current detector, and a current detector that detects the armature current of the synchronous motor. a three-sum/two-phase converter that generates a d-axis armature ampere-turn signal and a q-axis armature ampere-turn signal based on the output of the device, the value of the d-axis field flux signal and the value of the q-axis armature ampere-turn signal; a first multiplier that multiplies the value of the q-axis field flux signal and the value of the d-axis armature ampere turn signal, an adder that adds both of the multiplied values, and the addition. The motor is equipped with an error amplifier that compares the output of the motor with a torque command value and amplifies the deviation, and the torque value detected in this structure is fed back to the control device of the synchronous motor to perform constant torque control. .

[Operation] In the present invention, vector cross product calculation is performed based on the field flux vector and armature current vector, the generated torque (instantaneous value) of the synchronous motor is detected, and this detected torque value is compared with the torque command value. Since the deviation of the torque generated by the synchronous motor with respect to the torque command is detected, the mechanical transmission means described above is not required.

It has an input terminal for inputting the rotation angle signal of the magnetic pole of the synchronous motor, and since the control device always receives the output of the rotation angle detector that detects the magnetic pole angle of the synchronous motor, this rotation angle signal can be extracted. Simply apply the torque to the above input terminal to perform torque detection without changing the internals of the conventional control device.
By detecting the torque deviation, the torque generated by the synchronous motor can be made to follow the torque command value with high precision.

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

In FIGS. 1 and 2, 100 is a control device, which includes a position controller 101, a torque command device 102, a rotation angle detector 11, and a rotating field type synchronous motor SM.
The rotation angle detector 11, which constitutes a servo motor and supplies three-phase AC power to the armature winding 10.1 of the synchronous motor SM and IW through the three-phase power supply line 12, is a field rotor (permanent magnet). This is a detector that detects the rotation angle of the IF lIN, S, and rotates in synchronization with the synchronous motor SMO field (■ rotor IF) and sends out a rotation angle signal (pulse signal) θ.

13 is a torque compensator, and its case 13A has current input terminals 14A, 14B and signal input terminals 14C, 14.
D, has a signal output terminal 14E, and inside the case 13A,
As shown in FIG. 2, current detectors 15A, 15B, magnetic flux setter 16, magnetic flux vector calculator 17, 3-phase/2-phase converter 18, multiplier 19, 20, adder 21, error amplifier 22
It is equipped with

The control device 100 is a control circuit that controls the speed or torque of the synchronous motor SM to a value commanded by a speed command SO or a torque command TO, and has three phases (R phase, S phase, T phase).
Converter AC/D converts power from AC power supply to DC
It is equipped with a power converter consisting of an inverter DC/AC that converts the DC power converted into C into three-phase AC with variable voltage and variable frequency. C0NT is a main controller consisting of a microcomputer, which inputs the three-phase output current (iu, iv, iw) of the inverter DC/AC as a feed bank,
The output frequency and output current of the impeller DC/AC are controlled by the phytobank through the PWM controller PWM. The PWM controller PWM performs PWM based on the command from the main controller C0NT.
A signal is generated to control the switching elements of the inverter DC/AC to 0N10FF. C0UNT is a counter that takes in the rotation angle detection signal θ and calculates the phase of the three-phase alternating current sent out by the inverter DC/AC. )+1 device C0NT, positioning controller 10
It receives a positioning pulse from 1, calculates the corresponding phase, and provides it to the main controller C0NT. The main controller C0NT generates a current control command of a corresponding frequency based on the torque command To, and also generates a positioning control command based on a phase corresponding to the positioning pulse, and provides the generated current control command to the PWM controller PWM.

BR is a braking resistor that discharges the energy of a smoothing capacitor (not shown) between the converter AC/DC and the inverter DC/AC to prevent overvoltage of the capacitor during regenerative braking of the synchronous motor SM. It is a resistance to The positioning controller 101 receives a position feedback signal (consisting of a positive phase signal A, a negative phase signal B, and 5 quasi-component signals) θf from the control device 100, calculates the deviation between the feedback value and the positioning set value, and calculates the deviation between the feedback value and the positioning set value. Send positioning pulses. In addition, T.B.
I to TB5, CNI, and CN2 are terminals provided in the case 100A of the control device 100.

The magnetic flux setter 16 of the torque compensator 13 is a setter that sets the value of the magnetic flux ΦF generated by the permanent magnet IF, and sets the value of the magnetic flux ΦF measured at room temperature as the reference magnetic flux.

The magnetic flux vector calculator 17 inputs the magnetic flux ΦF and the above-mentioned position feedback signal θf through the input terminal 14C, and creates a stationary orthogonal coordinate system (third
A two-phase vector signal of the rotating field magnetic flux ΦF" on the d-axis and q-axis shown in the figure is generated.

Since this position feedback signal is the same signal as the rotation angle signal θ which is the output of the rotation angle detector 11, the two-phase vector signal is expressed by the following equations (11 and (2)).

+11) dF=ΦF cosθ・・・・・・・・・・・・
・(1) 11qF=ΦFsinθ・・・・・・・・・
...(2) However, θ=ωt, ω: The angular velocity three-phase two-phase converter 18 inputs the outputs of the current detectors 14A and 14B, and converts the armature ampere turn (rotation vector) set on the above coordinate system. If(A''), the following two-phase vector signal is generated.

1t(dA=N・IAcos(ω1+ −+ψ)・
・(3) 1)(qA=NiA sin (ωt+−1,000ψ)・・・・・・・(4) HA: Armature current vector lA; Maximum amplitude of armature current N: Armature winding Number of turns ψ: Phase difference angle Now, assume that the synchronous motor SM is a lossless motor. Since the armature ampere turn IHA = NX[I^, the generated torque Tゝ of the synchronous motor SM is T'' = IHA
"X@F" -1dFXHqA-ΦqFXIHd
Aπ = ΦF −HA cos ωt −5in (ωt+
+ψ)π =ΦF −HA sin ωt −cos (ωt+
+ψ)π =ΦF-HAsin(+ψ) =ΦF-HAcosφ=ΦF-NIAcosψ(5) Multiplier 19 of torque compensator 13 calculates r@dFXIHqJ, multiplier 20 calculates reqFX old dAJ, and multiplies both Since the outputs of the adders are added by the adder 21, the output of the adder 21 is the instantaneous value T of the torque generated by the synchronous motor SM.
give. The generation of torque compensator 13, N・IIA = [
HA: The armature ampere turn error amplifier 22 amplifies the deviation ΔT-To-T between the torque command To given from the external torque command device 102 and this detected torque T, and outputs the amplified difference ΔT-To-T to the main controller through the speed command input terminal of the control device 100. C0N
Enter T.

As described above, in this embodiment, the position feedback signal, which is the same signal as the output of the rotation angle detector 11, is processed to create the field flux vectors @dF, ΦqF, and the current detectors 15A, 15
The output of B is signal-processed and the armature ampere turn vector IIdA, ! (Since torque is detected by creating qA and calculating the cross product of these vectors, the conventional mechanical transmission means described above is not required, and the torque generated by the synchronous motor SM is directly detected, so it is faster than conventional methods.) , it is possible to perform highly accurate torque detection, compare this detected torque value with the value of the torque command TO of the torque command device 102, and input the deviation ΔT to the control device 100.
The main controller C0NT can control the torque of the synchronous motor SM with high precision.

The torque compensator 13 of this embodiment only needs to input the rotation angle signal θ to the input terminal 14C and detect the armature current with the current detectors 15A and 15B.
- Since the control device 1°O of the AC servo motor always takes in the rotation angle signal θ and controls the phase of the armature current, it can be connected without changing the inside of the control device 100, and can be connected to the AC servo motor. This has the advantage that the torque control accuracy of the system can be significantly improved.

Further, since the torque compensator 13 is constituted by 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.

Further, since the torque compensator 13 is of a stationary type and does not require a mechanical transmission means as described above, even if the synchronous motor SM is a high-speed machine, it can be used in its torque control system, and the torque Unlike when using a pickup, there is no restriction due to rotational speed.

In the above embodiment, the position feedback signal from the control device 100 is input to the signal input terminal 14c of the torque compensator 13, but it goes without saying that the output of the rotation angle detector 11 may also be input directly. be.

〔Effect of the invention〕

As explained above, the present invention simply connects the output signal of the rotation angle detector of the synchronous motor and captures the armature current of the synchronous motor with the current detector, and uses vector calculation to generate a torque command for the generated torque of the synchronous motor. It is extremely suitable for the torque control system of synchronous motors because it can detect deviations from There is no detection error caused by the transmission means, and the deviation can be detected with extremely high precision.Since it is a stationary type, the range of use is not restricted by the rotational speed of the synchronous motor, and these There is an advantage that the effect can be obtained at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an AC servo motor provided with an embodiment of the present invention, FIG. 2 is a block configuration diagram showing the above embodiment,
FIG. 3 is a d- and q-axis vector diagram of the field flux of a synchronous motor and armature ampere turns, and FIGS. 4 and 5 are diagrams showing conventional torque detectors. l...Synchronous motor, IA-armature winding, IF-rotating field rotor, 11--rotation angle detector, 13--torque compensator, 14A, 14 B-current input terminal, 14C
, 14D--signal input terminal, 14E--signal output terminal, 15A, 15B--current detector, 16--magnetic flux setting device, 17--magnetic flux vector calculator, 18--3-phase/2-phase converter , 19.2o-multiplier, 21-adder, 22-error amplifier, 100-control device, 101...-positioning controller, 102...-torque command device.

Claims (1)

[Claims] A signal input terminal for inputting a rotation angle signal of the rotor of the synchronous motor, and a d-axis field magnetic flux signal based on the value of the rotation angle signal and the magnetic flux value generated by the magnetic pole of the rotor of the synchronous motor set in the magnetic flux setting device. and a magnetic flux vector calculator that generates a q-axis field flux signal, a current detector, and a d-axis armature ampere turn signal and a q-axis armature ampere based on the output of the current detector that detects the armature current of the synchronous motor. a three-phase/two-phase converter that generates a turn signal; a first multiplier that multiplies the value of the d-axis field flux signal by the value of the q-axis armature ampere turn signal; A second multiplier that multiplies the value of the shaft armature ampere turn signal, an adder that adds both of the multiplied values, and an error amplifier that compares the output of the adder with the torque command value and amplifies the deviation. A control device for a synchronous motor, characterized in that the torque value detected in the configuration is fed back to the control device for the synchronous motor to perform constant torque control.