JP3951195B2 - Control device and starting method of synchronous motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus and a method of starting a synchronous motor, in particular, it relates to a control device and how to start the synchronous motor to operate in a vacuum vessel.
[0002]
[Prior art]
The synchronous motor is driven by detecting the magnetic pole position with a position detector such as an encoder or resolver and controlling the phase of the current applied in synchronization with the magnetic pole position. Therefore, it is necessary to obtain the positional relationship between the position detected by the position detector and the magnetic pole position, that is, the initial phase correction amount.
When an absolute value type such as an absolute encoder is used as the position detector, the relationship between the absolute position by the detector and the magnetic pole position (initial phase correction amount) as disclosed in JP-A-6-197586, for example, By storing in advance in the non-volatile memory, the synchronous motor can be driven with a correct initial phase correction amount from the time of power-on.
However, when a relative value type is used as the position detector, the position of the magnetic pole is not known when the power is turned on, and thus the synchronous motor cannot be driven with a correct initial phase correction amount.
Therefore, conventionally, a magnetic pole position detector, a so-called pole sensor, is provided separately from the position sensor.
[0003]
As methods that do not use the pole sensor, there are methods disclosed in Japanese Patent Application Laid-Open Nos. 61-92187, 62-31385, and 7-322678. In these conventional methods, driving is performed while sequentially updating the initial phase correction amount, the polarity of the generated torque is determined, and the initial phase correction amount is converged to the optimum initial phase correction amount. As the determination method of the generated torque polarity, the judgment is made from the speed feedback polarity in Japanese Patent Laid-Open No. 61-92187, and from the polarity of acceleration in Japanese Patent Laid-Open Publication Nos. 62-31385 and 7-322678.
However, these conventional techniques have the following problems.
In JP-A-6-197586, an expensive absolute value type position detector is required.
Further, the combination of the relative value type position detector and the pole sensor also causes an increase in size and cost. In particular, in order to apply to a linear motor, a pole sensor that only covers the entire stroke is required.
Compared to these, JP-A-61-92187, JP-A-62-31385, and JP-A-7-322678 are very effective. However, the determination is made while detecting the actual movement of the synchronous motor. When the moving body is at the stroke end, the moving body is in contact with the stopper, so that it cannot move in the direction of the stopper and the torque polarity cannot be correctly determined. Such a situation can occur sufficiently due to, for example, an operation error or a program error. If a correct initial phase correction amount cannot be detected and an attempt is made to drive with an incorrect initial phase correction amount, the motor may run out of control and the motor itself and other devices may be damaged.
In particular, when the electric motor operating in the vacuum chamber falls into such a state, the vacuum chamber is returned to atmospheric pressure, the moving body is moved to be movable in both directions, and the vacuum chamber is again in a vacuum state. Time and effort.
[0004]
On the other hand, when the synchronous motor does not perform normal commutation control due to some abnormality, the reference time for determination with respect to the positive / negative change time of the induced voltage is set from the set rotational speed, and the determination reference time and the positive / negative change time of the induced voltage are set. Comparing the change time with the one that recognizes an abnormality when it is out of the range of the reference time for determination, and the reference time for determination with respect to the change time of the energization signal from the set rotational speed, Japanese Patent Laid-Open No. 6-253580 discloses that a signal is compared with a signal change time and recognized as abnormal when the change time is out of the reference time range for determination.
However, the method described in JP-A-6-253580 has the following problems.
(1) It is necessary to set a target speed, or to detect the rotation speed and the time to reach the set speed, and the algorithm is complicated.
(2) The time to reach the target speed is inaccurate because it is affected by the initial rotational speed.
(3) If the field pole position of the rotor cannot be specified, it cannot be driven in a specific direction.
[0005]
[Problems to be solved by the invention]
Resolving object of the present invention, without driving the moving body in the wrong initial phase correction amount, even in every stroke position, also the operating environment is a vacuum, accurate and optimum initial phase correction amount The present invention provides a control device for a synchronous motor that can be driven by a motor and a starting method thereof .
[0006]
[Means for Solving the Problems]
Control system for a synchronous motor of the present invention to solve the problems above SL includes means for driving the synchronous motor vector control by controlling synchronously the phase of the driving current of the synchronous motor magnetic pole position, wherein A position detection sensor for detecting a linear position or a rotational position of the synchronous motor, a limit switch for detecting that the moving part of the synchronous motor has reached a movable limit, and an initial phase correction amount of the drive current when the synchronous motor is started In the control apparatus for a synchronous motor having an initial phase correction amount detecting means for converging to an optimal initial phase correction amount by determining the polarity of the generated torque while driving while sequentially updating, the moving unit moves the position of the limit switch There is provided means for storing an optimum initial phase correction amount at the time.
In addition, the method for starting a synchronous motor according to the present invention for solving the above-described problem is the above-described method for starting a control apparatus for a synchronous motor, wherein the limit sensor detects the initial phase correction amount at the time of detection. When it is detected that the moving part is at the stroke end, the value stored in the initial phase correction amount storage means is used as the initial phase correction amount, and when it is detected that it is not at the stroke end. Performs the initial phase correction amount detection process. By the above means, even when the moving part is at the stroke end and cannot move freely, it can be driven with the optimum initial phase correction amount stored in the initial phase correction amount storage means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
FIG. 1 is a block diagram of a first embodiment in which the synchronous motor control device of the present invention is applied to a linear motor. In the figure, reference numeral 1 denotes a CPU that outputs current commands ^* u, ^* v, ^* w through a D / A converter 2. Reference numeral 3 denotes a power amplifier that supplies currents U, V, and W proportional to the current commands ^* u, ^* v, and ^* w to the synchronous linear motor 6. Reference _numeral 4 denotes a non-volatile memory that stores initial phase correction amounts θ _e (+) and θ _e (−). A counter 5 counts position pulses from an incremental linear encoder (not shown). A moving unit 7 is driven by the linear motor 6. Reference numerals 81 and 82 denote a + side stopper and a − side stopper that prevent the moving unit 7 from moving by a predetermined stroke or more, respectively. Reference numerals 91 and 92 respectively denote a + side limit sensor and a − side limit sensor that detect that the moving unit is at the stroke end.
The nonvolatile memory 4 includes an optimal initial phase correction value θ _e (+) when the moving unit 7 is at the positive stroke end and an optimal initial phase correction value θ _e (− when the moving unit 7 is at the negative stroke end. ) Is measured and stored in advance. Further, the CPU 1 executes a position control algorithm, vector control of the motor currents U, V, and W, and an initial phase correction amount detection process described in Japanese Patent Laid-Open No. 61-92187.
[0009]
In the initial phase correction amount detection process described in Japanese Patent Laid-Open No. 61-92187, when the current phase correction amount δ is obtained, two correction amounts γ ₁ and γ ₂ (where γ ₁ < When the correction torque (γ) within the range where δ <γ ₂ ) is set to the lower limit value and the upper limit value, respectively, is given to check the polarity of the generated torque, and when the polarity of the generated torque is the correction value (γ ₁ ) If different from the polarity of the generated torque is updated correction amount (gamma ₂₎ the correction amount (gamma), the correction amount in the case that is different from the polarity of the torque generated when the correction amount (γ ₂₎ (γ _The process of updating ₁ ) with the correction amount (γ) is repeated a predetermined number of times, and the final value of the correction amount (γ) thus obtained is used as the estimated value of the correction amount δ.
[0010]
FIG. 2 shows a flowchart of a method for starting a synchronous motor according to the present invention, where an initial phase correction amount δ is determined.
In FIG. 2, in steps 21 and 22, it is determined whether or not the moving part is at the stroke end. For the determination, signals from the + side limit sensor 91 and the − side limit sensor 92 are used. If it is determined that the moving unit is at the + side stroke end, the initial phase correction amount δ is determined to be θ _e (+) in step 24 and the process ends. If it is determined that the moving unit is at the − side stroke end, the initial phase correction amount δ is determined to be θ _e (−) in step 25 and the process ends. If it is determined that none of them is present, the initial phase correction amount detection process is executed in step 23.
That is, when the moving part is at the stroke end and cannot move in both directions, the optimum initial phase correction amounts θ _e (+) and θ _e (−) at that position are used. Since the optimum initial phase correction amount determined in the phase correction amount detection process is used, it can be activated at any position.
[0011]
Next, a second embodiment of the present invention will be described.
FIG. 3 is a conceptual block diagram, and FIGS. 4 and 5 are flowcharts.
The CPU 11 inputs the position data of the counter 18 and executes an algorithm to be described later, and then sends the U-phase current command and the V-phase current command to the 2-3-phase conversion circuit 14 through the D / A converter 12 and the D / A converter 13. Output to. The 2-3 phase conversion circuit 14 converts the two-phase U-phase current command and the V-phase current command into three-phase current commands I _u , I _v , and I _w and outputs them to the power amplifier 15. The power amplifier 15 supplies a current corresponding to the command to the synchronous motor 16 and drives it. The encoder 17 outputs an AB pulse according to the position of the moving element of the synchronous motor 16. The counter 18 counts AB pulses and outputs position data.
In this embodiment, the incremental encoder 17 is used as the position detector. However, since the pole sensor is not used, the position x detected by the detector and the field pole position of the synchronous motor are detected when the motor control device is turned on. It is independent of φ. Therefore, if the field pole position θ obtained from the position x detected by the detector is the phase ρ of the current applied without adding the offset amount γ, the phase ρ of the applied current is the field pole position φ of the synchronous motor. There is no guarantee that | δ | <90 °. Furthermore, even if an offset γ is added such that ρ = θ + γ, it is not known what value γ should be, so the same is true.
[0012]
FIG. 4 is a flowchart. Step 101 gives a thrust command to be driven. Step 102 provides an initial setting of the current phase offset. For example, γ = 0 °. Step 103 is a subprogram presented in FIG. 5, and detects the acceleration of the synchronous motor. Step 104 determines the presence or absence of acceleration. If the acceleration is detected, the synchronous motor is operating normally, and the process ends. If the acceleration cannot be detected, the process proceeds to step 105.
In step 105, the current phase is updated.
In the synchronous motor, the generated electromagnetic force T is given by the following equation.
T = kicos (φ−γ) (1)
Here, k is the electromagnetic force constant, i is the magnitude of the applied current, and φ is the actual field pole position of the synchronous motor. If no acceleration is detected in step 103 and step 104, either the generated electromagnetic force | T | is smaller than the sum F of friction, external force or the like, or the synchronous motor cannot be driven due to some abnormality. Therefore, the phase offset amount is updated to γ such that | T |> F, for example, γ = γ + 90 °.
In step 106, acceleration is detected from the subprogram presented in FIG. In step 107, when the acceleration is detected, the synchronous motor is normally driven, and the process ends. If no acceleration is detected, the process proceeds to step 108. In step 108, a signal for cutting off the synchronous motor is output.
[0013]
FIG. 3 is a flowchart of a subprogram for detecting acceleration. Step 201 initializes the time for holding the thrust command. For example, t = 0. In step 202, thrust is calculated based on the set phase of the applied current. In step 203, the presence or absence of acceleration is determined. The acceleration can be obtained by second-order differentiation of the position. If acceleration can be detected, control is returned to the main program. If the acceleration cannot be detected, the process proceeds to step 204.
In step 204, the time is determined. It is determined whether or not the time t _max can be given without changing the thrust. If it is less than the available time t _max , the process proceeds to step 205. In step 205, the time is updated. For example, t = t + Δt
And Δt is a control sampling time.
If the time t _max that can be given is exceeded, the control is returned to the main program assuming that the acceleration could not be detected.
Although the description has been given with respect to the direct acting synchronous motor, the same can be said for the rotary synchronous motor by replacing the generated thrust with the generated torque, the thrust constant with the torque constant, and the thrust command with the torque command.
[0014]
【The invention's effect】
As described above, according to the present invention, it is possible to determine the accurate initial phase correction amount at any position, it is possible to prevent the runaway of the synchronous motor, Ru can prevent damage to the equipment.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a control apparatus for a synchronous motor according to the present invention;
FIG. 2 is a flowchart of a method for starting a synchronous motor according to the present invention.
FIG. 3 is a block diagram showing a second embodiment of the present invention.
FIG. 4 is a flowchart of a main program showing a second embodiment of the present invention.
FIG. 5 is a flowchart of a subprogram showing a second embodiment of the present invention.
[Explanation of symbols]
1 CPU, 2 DA converter, 3 power amplifier, 4 non-volatile memory, 5 counter, 6 linear motor, 7 moving part, 81 + side stopper, 82-side stopper, 91 + side limit sensor, 92-side limit sensor, 11 CPU, 12, 13 D / A converter, 14 2-3 phase conversion circuit, 15 inverter, 16 synchronous motor, 17 encoder, 18 counter

Claims (2)

  Means for driving the synchronous motor by vector control by controlling the phase of the driving current of the synchronous motor in synchronization with the magnetic pole position, a position detection sensor for detecting a linear position or a rotational position of the synchronous motor, and the synchronous motor A limit switch that detects that the moving part of the motor has reached the movable limit, and an optimum initial value by determining the polarity of the generated torque while driving while sequentially updating the initial phase correction amount of the drive current when starting the synchronous motor In a control apparatus for a synchronous motor having an initial phase correction amount detecting means for converging on a phase correction amount, the apparatus includes a means for storing an optimal initial phase correction amount when the moving unit is at the position of the limit switch. A control device for a synchronous motor as a feature.   2. The method for starting a synchronous motor control device according to claim 1, wherein when the initial phase correction amount at the time of startup is detected, the limit sensor detects that the moving unit is at the stroke end. The value stored in the initial phase correction amount storage means is used as the initial phase correction amount, and when it is detected that there is no stroke end, the initial phase correction amount detection process is executed. To start the synchronous motor.

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