JP2830145B2 - Initial Magnetic Pole Alignment Method for Synchronous AC Servomotor - Google Patents

Description

The present invention relates to a method for aligning an initial magnetic pole in a synchronous AC servomotor.

[Conventional technology]

In a synchronous AC servomotor, it is necessary to know the magnetic pole position in order to determine the phase of each phase winding current. One method of detecting the magnetic pole position is to provide a magnetic pole position sensor in addition to the position detector and to detect the magnetic pole position on a circuit using the output of the magnetic pole position sensor, A method is known in which a moving element or a magnetic pole is moved to a stable point corresponding to the flow when the flow is performed.

The above stable point will be described with reference to FIG. now,
When the magnetic pole pitch of the stator is τ, the magnetic flux φ is If the position of the α winding of the mover is X and the position of the β winding is X−τ / 4 in the state where
When the winding current Iβ has the following relationship,
It is stable at this point.

Now, if, at the position X _1, the alpha-phase alpha '= I _0, the beta-phase beta' =
When a current of 0 flows, the mover moves in the direction of the arrow shown in the figure, and
= Τ / 4 stabilizes. That is, α phase and β phase respectively
When flow I _0, 0 of the current, the moving element is maximum, moved by ± tau / 2 reaching the stable point.

FIG. 4 is a block diagram showing a conventional control device for a two-phase AC servomotor, where 1 is a two-phase AC servomotor,
2 is a stator (magnetic pole), 3 is a moving element, 3α is an α winding, 3β
Is a β winding, 4 is a position detector (encoder), and 5 is a speed detector.

10 sends the torque command voltage V ^* _T sly error amplifier (speed controller), 11 is an amplitude setter delivering a current amplitude command I _0, 12 is [pi / 2 phase shifter 13 the phase calculator, 14 Function generator for generating a two-phase sine wave with unit amplitude, 15α, 15β
Is a multiplier, 16α and 16β are current controllers, 17α and 17β are current transformers CT, SW1 is a changeover switch, and SW2 to SW4 are switches.

When performing initial magnetic pole alignment for moving the movable element 3 to the above-mentioned stable point, the switch SW2 is turned on, the switches SW3 and SW4 are turned off, and the changeover switch SW1 is turned on, ie, the amplitude setting unit 12. Function generator 14 sends a sin value of the sin value and β phase current Iβ of α phase currents I.alpha, respectively and the current amplitude command I ₀ multipliers 15Arufa, calculated by 15β by α phase current command I.alpha ^* and β The phase current command Iβ ^* is sent to the current controllers 16α and 16β, and the current controllers 16α and 16β perform feedback control of the α-phase current Iα and the β-phase current Iβ.

When the mover 3 moves to the above stable point and stops, the mode switching command is switched to the normal operation mode command, the changeover switch SW1 is switched to the side, the switch SW2 is turned off, and the switch SW3 is turned off.
Turn on SW4. As a result, the function generator 14
And the phase data corresponding to τ / 4 are given, and the α-phase current Iα and β-phase current Iβ are changed to currents α and β during normal operation shown in FIG. After the initial magnetic pole alignment is completed, the function generator 14 calculates the current phase based on the position pulse sent from the position detector 4.
And generates a function of a two-phase sine wave of unit amplitude having a phase that changes in accordance with the position change of the moving element 3.

[Problems to be solved by the invention]

This initial magnetic pole alignment has the advantage of not having to use the magnetic pole position sensor described above. However, when the magnetic pole position pitch is large, the required movement amount of the moving element 3 to the stable point becomes large and it takes time. In addition, in the case of an air-floating linear servomotor having a small moving friction loss, for example, there is a problem that it is difficult to smoothly stop at the stable point.

The present invention has been made to solve the above problems,
It is an object of the present invention to provide an initial magnetic pole alignment method for a synchronous AC servomotor that can perform magnetic pole alignment with a smaller amount of movement as compared with the related art and can smoothly stop at a stable point.

[Means for solving the problem]

In order to achieve the above object, the present invention supplies a current based on a predetermined current pattern to each phase winding of the mover and moves the mover to a stable point determined by the pattern to perform initial magnetic pole alignment. Each phase of the current pattern, corresponding to the amount of movement of the mover calculated based on the output of the position detector, and changed in a direction different from the traveling direction during normal operation, In item 2, the phase of the current pattern is further corrected by the moving speed of the moving element.

[Action]

According to the present invention, a current having a phase that changes in the opposite phase is supplied to each phase of the mover in accordance with the amount of movement. The child reaches a stable point. Further, since the phase is corrected in proportion to the speed of the moving element, it is possible to suppress vibration when stopping at a stable point.

〔Example〕

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

In FIG. 1, reference numeral 21 denotes a phase calculator,
In addition to the normal function of the phase calculator 13 shown in the figure, the movement distance ΔX
And is in phase opposition to the direction of movement, and
The ratio of the amount of phase change to the amount of position change is calculated by the phase calculator 13.
The calculated phase data is output to the function generator 14 with the ratio set to be larger than that in the normal operation. Reference numeral 22 denotes a phase corrector (phase shifter). When the speed detector 8 outputs the signal via the switch SW5, a speed feedback (signal) is input, and a speed-dependent phase shift amount is calculated and output. The switch SW5 is a switch that is turned on during initial magnetic pole alignment. Other configurations are the same as those in FIG. 4, and the same components are denoted by the same reference numerals.

In the present embodiment, the initial magnetic pole alignment is performed by changing the phase of the α-phase current Iα and the β-phase current Iβ in a direction opposite to the moving direction according to the moving distance of the moving element 3. That is, in the waveform diagram of FIG. Currents α ′ and β ′ represented by α winding 3α and β winding 3β
Respectively. In FIG. 2, a position X ″ represents an α-phase current Iα and a β-phase current Iβ when the movable element 3 is at the position X.
Are set to currents α and β, respectively, and the currents α ″ and β ″ indicate currents for moving element 3 to make position X a stable point.

The phase calculator 21 shown in FIG. 1 calculates the moving distance ΔX from the position pulse sent from the position detector 8, and calculates the moving distance ΔX.
The phase [−2πKΔX / τ] that changes in proportion to X is obtained, and is given to the function generator 14.

As shown by the above equations (4) and (5), when the phases of the α-phase current Iα and the β-phase current Iβ are changed in proportion to the moving amount ΔX of the moving element 3, the force acting on the moving element 3 F is Becomes The above stable point is a condition Therefore, solving this equation (7), Therefore, the moving element 3 reaches the stable point with a moving amount of 1 / (1 + K) as compared with the conventional case where the current phase is fixed.

FIG. 3 is a block diagram showing the control system of the embodiment at this time.

By the way, since the system represented by this block diagram becomes vibrating near the above-mentioned stable point, vibration is long for a moving element having a small moving friction such as a moving element of an air-floating linear AC servomotor. continue.

For this reason, in the present embodiment, the phase corrector 21 is provided and α
The phases of the phase current Iα and the β-phase current Iβ are corrected by the velocity feedback amount (K _V × v, v is the velocity of the movable element) of the movable element 3 as shown by the following equation.

At this time, the force F acting on the mover 3 is Becomes When this is first-order approximated, Here, assuming that v = Δ and K _T = φ ₀ I ₀ , the equation of motion is as follows, where M is the mass of the mover 3. Becomes It is understood that the second term (K _T K _V Δ) on the right side of this equation is a tamping term.

Accordingly, even when the movable element 3 reaches the vicinity of the stable point, the vibration is suppressed, and the movable element 3 reaches the stable point more smoothly than in the related art.

When the mode switching command is switched to the normal operation mode command after the movable element 3 reaches the above-mentioned stable point, the switching switch
SW1 switches to the speed controller 10 side, switch 5 opens,
When the switches SW2 and SW4 are closed, the torque command IT ^* from the speed controller 10 is given to the multipliers 15α and 15β as current amplitude values, and the phase data corresponding to the phase difference τ / 4 from the phase shifter 12 is a function. Generator 14 and at the same time
21 is switched to the function that the phase calculator 13 had,
Phase data is output in which the direction of change in the current phase is the direction of change during normal operation (the same direction as the moving direction of the moving element 3).
That is, in FIG. 2, .DELTA.X is made very small, and currents .alpha. 'And .beta.' Having a phase which gives a stable point to the point at which this small movement has occurred are caused to change by .pi. / 2 by the output of the phase shifter 12. The currents [α] and [β] at the phase during the normal operation are obtained.

Although the above embodiment has been described in connection with a two-phase AC servomotor, the present invention can be applied to an N-phase AC servomotor to obtain the same effect. In this case, the magnetic pole movement type may be used.

〔The invention's effect〕

As described above, the present invention employs a configuration in which a current having a phase that changes according to the moving amount of the moving element is supplied to each phase to move the moving element to a stable point, so that the moving amount is smaller than in the related art. In addition, since the stable point can be smoothly reached, it is very suitable for use in a motor having a large magnetic pole pitch.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the above embodiment, FIG. 3 is a block diagram of the above embodiment, and FIG. FIG. 5 is a block diagram showing a servomotor control device, FIG. 5 is a waveform diagram for explaining conventional initial magnetic pole alignment, and FIG. 6 is a waveform diagram for explaining a transition operation to a normal operation in the conventional device. . 2 ... stator poles, 3 ... mover, 3α, 3β ... winding, 4 ... position detector, 5 ... speed detector, 10 ... speed controller, 11 ... amplitude setting device, 12 …… Phase shifter, 14 …… Function generator, 16α, 16β …… Current controller, 21… Phase calculator, 22 …… Phase corrector.

Claims (2)

(57) [Claims] After performing initial magnetic pole positioning, a stator magnetic pole position is detected based on an output of a position detector for detecting a position of a mover having a multi-phase winding, and a current phase of each phase current is determined. In the synchronous AC servo motor, the initial magnetic pole alignment is performed by supplying a current based on a predetermined current pattern to each phase winding and moving the mover to a stable point determined by the pattern. The phase of the current for obtaining the stable point is changed in a direction corresponding to the movement amount of the mover calculated based on the output of the position detector and in a direction different from the phase traveling direction during normal operation. Initial magnetic pole alignment method for synchronous AC servomotors. 2. The method according to claim 1, wherein a current phase that changes in accordance with a moving amount of the moving element is corrected by a moving speed of the moving element. .