JP2520650B2 - Control device for synchronous motor for servo motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Utilization] The present invention relates to an improvement in a control device for a synchronous motor for a servo motor. In particular, the permanent magnet rotor of the synchronous motor is demagnetized even when the angular position detecting means of the synchronous motor or devices attached to it, such as the encoder that constitutes the controller of the synchronous motor for the servo motor, malfunctions or malfunctions. The present invention relates to a controller for a synchronous motor for a servo motor, which is improved so as to avoid the above.

[Conventional technology]

A synchronous motor is an electric motor in which a permanent magnet type rotor or a DC excitation type rotor rotates in synchronization with a rotating magnetic field generated by a stator. Therefore, it is essentially a constant speed variable torque type electric motor.

However, if the frequency corresponding to the speed required by the rotating body, the phase corresponding to the relative position of the stator / rotor, and the value corresponding to the acceleration (deceleration) are synchronized, If it is continuously supplied to the stator of the electric motor, the error based on the command issued by the control speed (the error based on the analog property of the electric motor main body) is extremely small, and it can function as a servo motor with extremely high accuracy. . In addition, the synchronous motor is brushless, does not generate noise, has a simple rotor structure, and is particularly robust when using a permanent magnet rotor, making it an extremely useful servo motor for intermittent use. It is suitable.

The above control (frequency corresponding to the speed required by the rotating body, phase corresponding to the relative relative position of the stator / rotor, and the current corresponding to the acceleration (deceleration) And control to supply to the stator of the synchronous motor)
It is known that this can be realized by using a combination of an accurate angular position detection means such as an encoder and a resolver and a logic circuit / micro analog circuit or a computer. Therefore, the synchronous motor is originally used as a microcomputer. It is an excellent servo motor for use in numerically controlled machine tools and the like.

An example of a conventional controller for a synchronous motor for a servo motor will be described with reference to the drawings.

The elements that make up the control device for the synchronous motor for servo motors described below can be realized using a microcomputer, etc., but must be configured with logic circuits and analog circuits that consist of individual elements. Of course, you can See FIG. 3. In the figure, M is a synchronous motor, which is used as a servo motor. T is an angular position detecting means driven by the synchronous motor M, and is composed of an encoder, a resolver and the like. Reference numeral A denotes an angular position calculating means, which reads a code signal given by an encoder, a resolver or the like to calculate the angular position θ of the synchronous motor M.

V is a speed calculation means, which calculates the angular speed α of the rotor of the synchronous motor M based on the output of the angular position calculation means A.

TC is a torque command calculation means, which compares the speed signal α given by the speed calculation means V with a speed command signal β given from the outside and outputs the deviation as a torque command γ.

P is a phase command calculation means, which calculates sin θ, sin (θ + 2/3 · π) corresponding to the angular position θ given by the angular position calculation means A.

PP is sin θ, sin (θ +
2/3 · π) and the torque command γ given by the torque command calculation means TC to calculate the three-phase torque command δ. That is, sin θ, sin (θ + 2/3 · π) is multiplied by γ to calculate δ ₁ = γ sin θ, δ ₂ = γ sin (θ + 2/3 · π), and the vector difference between them is calculated. Find δ ₃ = γ sin (θ + 4/3 · π). This three-phase torque command δ represents the frequency, phase, and torque that the synchronous motor controlled to realize the externally supplied speed command signal β seeks at that time. The above is the so-called speed control loop.

IC is a three-phase current command calculation means, and three-phase torque command δ
And the current i of the synchronous motor M to be controlled, the three-phase current command ε is calculated. That is, it constitutes a current control loop.

The PWM is a pulse width modulation type inverter, and the firing angle is controlled based on the three-phase current command ε to realize the operation according to the speed command signal β given from the outside. In the figure, it is shown that direct current is supplied, but it does not matter at all if a converter that is supplied with alternating current and rectifies this into direct current is built in.

[Problems to be solved by the invention]

As described above, the synchronous motor M is extremely excellent as a servo motor, but the following drawbacks are unavoidable.

With the above-mentioned control device, a rotating magnetic field having a phase corresponding to the angular position of the permanent magnets constituting the rotor should be given, but should the angular position detecting means fail or the angular position detecting means If the line connecting the angular position calculation means is broken, the angular position calculation means receives an incorrect angular position,
Since it will be controlled in response to this incorrect angular position,
The angular position of the rotor and the phase of the rotating magnetic field do not match, and in some cases a rotating magnetic field of a phase that demagnetizes the permanent magnets that make up the rotor may be applied. This is a serious problem because the permanent magnets that make up the rotor lose their function altogether when given for a short time.

An object of the present invention is to eliminate this drawback. In the control device for a synchronous motor for a servo motor having the above-mentioned configuration, the angular position detecting means should fail, or the angular position detecting means and the angular position calculating means should by any chance. An object of the present invention is to provide a controller for a synchronous motor for a servo motor, which is improved so as not to be demagnetized even if the line connecting to and is disconnected.

[Means for solving problems]

The above object can be achieved by adding the following means to the control device for a synchronous motor for a servo motor having the above configuration.

The added means is an angular position storage means (ME) for storing the angular position (θ) given by the angular position calculation means (A), and a temporal change of the value stored in the angular position storage means (ME). An angular position change calculation means (AV) that is sequentially calculated, and an emergency input that resets the input of the pulse width modulation type inverter (PWM) to zero when the value of the angular position change calculation means (AV) exceeds a predetermined value. Stop means (ES).

[Action]

It is not always easy to detect a case where the above-mentioned defect may occur (in the unlikely event that the angular position detecting means fails or the line connecting the angular position detecting means and the angular position calculating means is broken). Absent. However, if the angular position detecting means fails or the line connecting the angular position detecting means and the angular position calculating means is broken, the angular position signal provided by the angular position calculating means A is discontinuous. It should change to.
In other words, the angular position signal should jump rather than change gradually (gradual change). Therefore, the present invention takes advantage of this property, and as the means for monitoring the temporal change of the output signal of the angular position detecting means T or the angular position calculating means A, the angular position storing means ME, the angular position change calculating means AV, and the emergency stop means.
ES is added, and the output of the angular position change calculation means AV is a predetermined value (change value expected at maximum angular velocity)
If the above-mentioned defect is likely to occur (in the unlikely event that the angular position detecting means fails or the line connecting the angular position detecting means and the angular position calculating means is broken), By making a decision, the output of the pulse width modulation type inverter PWM is set to zero to prevent the generation of an erroneous rotating magnetic field.

〔Example〕

Hereinafter, a control device for a synchronous motor for a servo motor according to an embodiment of the present invention will be further described with reference to the drawings.

In FIG. 1, M is a synchronous motor, which is used as a servo motor. T is an angular position detecting means driven by the synchronous motor M, and is composed of an encoder, a resolver and the like. Reference numeral A denotes an angular position calculating means, which reads a code signal given by an encoder, a resolver or the like to calculate the angular position θ of the synchronous motor M.

V is a speed calculation means, which calculates the angular speed α of the rotor of the synchronous motor M based on the output of the angular position calculation means A.

TC is a torque command calculation means, which compares the speed signal α given by the speed calculation means V with a speed command signal β given from the outside and outputs the deviation as a torque command γ.

P is a phase command calculation means, which calculates sin θ, sin (θ + 2/3 · π) corresponding to the angular position θ given by the angular position calculation means A.

PP is sin θ, sin (θ +
2/3 · π) and the torque command γ given by the torque command calculation means TC to calculate the three-phase torque command δ. That is, sin θ, sin (θ + 2/3 · π) is multiplied by γ to calculate δ ₁ = γ sin θ, δ ₂ = γ sin (θ + 2/3 · π), and the vector difference between them is calculated. Find δ ₃ = γ sin (θ + 4/3 · π). This three-phase torque command δ represents the frequency, phase, and torque that the synchronous motor controlled to realize the externally supplied speed command signal β seeks at that time. The above is the so-called speed control loop.

IC is a three-phase current command calculation means, and three-phase torque command δ
And the current i of the synchronous motor M to be controlled, the three-phase current command ε is calculated. That is, it constitutes a current control loop.

The PWM is a pulse width modulation type inverter, and the firing angle is controlled based on the three-phase current command ε to realize the operation according to the speed command signal β given from the outside. In the figure, it is shown that direct current is supplied, but it does not matter at all if a comparator that is supplied with alternating current and rectifies this into direct current is built in.

ME is an angular position storage means according to the gist of the present invention, and the angular position θ of the rotor of the synchronous motor M given by the angular position calculation means A is given.
Are sequentially stored. A minimum of two storage elements is sufficient.

AV is an angular position change calculation means according to the gist of the present invention,
The time change of the angular position θ of the rotor of the synchronous motor M stored in the angular position storage means ME is calculated.

ES is an emergency stop means according to the gist of the present invention, and when the output of the angular position change calculation means AV exceeds a predetermined value (a change value expected at the maximum angular velocity),
It is judged that there is a possibility that a defect will occur (in the unlikely event that the angular position detecting means fails or the line connecting the angular position detecting means and the angular position calculating means is broken), and the pulse width is determined. An emergency stop command ζ that makes the output of the modulation type inverter PWM zero is given to the pulse width modulation type inverter PWM.

When the pulse width modulation type inverter PWM is given an emergency stop command ζ, it gives an OFF signal to all the energizing elements (power transistors, thyristors, etc.) to cut off the power supply to the synchronous motor M, and instantaneously Stop the outbreak.

As a result, in the unlikely event that the angular position detecting means fails, or the line connecting the angular position detecting means and the angular position calculating means is broken,
Otherwise, even when the rotating magnetic field of the demagnetization phase is applied, the demagnetization phase is prevented from occurring and the rotor of the synchronous motor M is not demagnetized.

Note that the control device for a synchronous motor for a servo motor according to the present invention can be configured with a logic circuit or an analog circuit including individual elements, but since it is easy to realize by using a microcomputer or the like, the present invention The operation of the functional element according to the gist of will be described with reference to a flowchart.

See FIG. 2. The output signals of the angular position calculation means A are sequentially stored in the angular position storage means ME (1). At least two storage elements are required.

The angular position change calculation means AV calculates the time change of the value stored in the angular position storage means ME. That is, the stored value of this time is subtracted from the stored value of the previous time in response to the clock signal (2).

When the time change exceeds a predetermined value (a change value expected at the maximum angular velocity), the emergency stop means ES may cause the defect (by any chance, the angular position detection means In case of failure or disconnection of the line connecting the angular position detecting means and the angular position calculating means)
And the emergency stop command ζ to set the output of the pulse width modulation type inverter PWM to zero.
Give to.

The angular position storage means ME according to the gist of the present invention can perform the same operation even if it stores the signal of the angular position detection means T.

〔The invention's effect〕

As described above, in the control device for a synchronous motor for a servo motor according to the present invention, the angular position storage means for storing the angular position given by the angular position calculation means and the temporal change of the value stored in the angular position storage means are described. Since the angular position change calculation means for sequentially calculating and the emergency stop means for making the input of the pulse width modulation type inverter zero when the value of the angular position change calculation means exceeds a predetermined value are added, 1.When the angular position detecting means fails or the line connecting the angular position detecting means and the angular position calculating means is broken, the output of the pulse width modulation type inverter is set to zero and the error occurs. Since the phase circuit magnetic field is not generated, the rotor of the synchronous motor is not demagnetized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a control device for a synchronous motor for a servo motor according to an embodiment of the present invention. FIG. 2 is a flowchart of the control device for the servomotor synchronous motor according to the embodiment of the present invention. Figure 3 shows
It is a block diagram of the control apparatus of the synchronous motor for servomotors which concerns on a prior art. T ... Angular position detecting means, A ... Angular position calculating means, V ...
Speed calculation means, TC ... torque command calculation means, P ... phase command calculation means, PP ... three-phase torque command calculation means, IC ...
Three-phase current command calculation means, PWM ... Pulse width modulation type inverter, ME ... Angular position storage means, AV ... Angular position change calculation means, ES ... Emergency stop means, θ ... Angular position of synchronous motor,
α: angular velocity of synchronous motor, β ... speed command signal, γ ...
... Torque command, δ ... Three-phase torque command, ε ... Three-phase current command, i ... Stator current of synchronous motor, ζ ... Emergency stop command.

Claims (1)

(57) [Claims] 1. An angular position detecting means (T) driven by a synchronous motor (M), and an angular position (θ) of the synchronous motor (M) is calculated based on an output of the angular position detecting means (T). Angular position calculating means (A), a speed calculating means (V) for calculating an angular speed (α) of the synchronous motor (M) based on an output of the angular position calculating means (A), and the speed calculating means (A). Torque command calculation means (TC) for calculating the torque command signal (γ) based on the speed signal (α) output from V) and the speed command signal (β) given from the outside.
A phase command calculation means (P) for calculating sin θ, sin (θ + 2/3 · π) corresponding to the position (θ) calculated by the angular position calculation means (A), and a phase command calculation means (P) Give sin θ, sin (θ + 2/3
.Pi.) And the three-phase torque command (.delta.) Based on the torque command signal (.gamma.) Given by the torque command calculation means (TC).
A three-phase torque command calculating means (PP), and a three-phase torque command (δ) given by the three-phase torque command calculating means (PP) and a current (i) of the synchronous motor (M). A three-phase current command calculating means (IC) for calculating a current command (ε) and a three-phase current command (ε) given by the three-phase current command calculating means (IC) are supplied to the synchronous motor (M). Pulse width modulation type inverter (PW
M) and a servomotor synchronous motor control device comprising: an angular position storage means (ME) for storing the angular position (θ) given by the angular position calculation means (A); An angular position change calculating means (AV) for sequentially calculating a temporal change of a value stored in (ME), and the pulse width modulation when the value of the angular position change calculating means (AV) exceeds a predetermined value. Type inverter (PW
A control device for a synchronous motor for a servo motor, comprising: an emergency stop means (ES) for making the input of (M) zero.