JP3114937B2 - Motor control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor control device, and more particularly to a control device for a synchronous AC servomotor used for a machine tool or the like.

[Conventional technology]

In general, in a synchronous AC servomotor including a rotor having a permanent magnet and an armature having three-phase windings, a sinusoidal current having the same phase or the opposite phase as the motor field (or back electromotive force) is applied to the motor. It is necessary to energize the armature winding of the motor. For this purpose, for example, as shown in Japanese Patent Application Laid-Open No. 2-97293, a magnetic pole sensor for detecting the polarity switching position of the field provided in the motor and an encoder are used. A current command generator RO that generates a current command in phase or opposite phase to magnetism (or back electromotive force)
M is equipped. In the current command generator ROM, the required sine wave current command data is stored in a table in advance and stored in a storage element, and the rotor rotation angle is detected based on the signal CS from the magnetic pole sensor and the signal EC from the encoder. The current command of the storage element is searched from the rotor rotation angle.

At this time, the signal CS from the magnetic pole sensor is used to match the phase of the field command (or back electromotive force) with the phase of the current command.

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, a phase difference occurs between the current command and the field (or back electromotive force) during a period immediately before the power is turned on and before the detection of the magnetic pole sensor signal CS, so that the starting torque is reduced and the motor efficiency is reduced. Had led to a decline.

In the method of directly searching for sine wave command data using a high-resolution absolute value encoder, the encoder itself is expensive and is not common.

The present invention is intended to improve the reduction in motor performance that occurs at the time of starting or the like without using an expensive high-resolution absolute value encoder.

[Means for solving the problem]

A motor control device according to the present invention is a motor magnetic field pole position detecting device for a motor having a rotor having a magnetic field and an armature having a three-phase winding disposed with the rotor and an air gap. It has an edge detection circuit for detecting an output change, a ROM storing sine data, and an up / down counter that operates upon receiving an output of the edge detection circuit and an output of an encoder for detecting a change in the rotor shaft angle of the motor. Then, in the motor control device in which the CS signal of the magnetic pole position detecting device is connected to the upper address of the ROM and the output of the up / down counter is connected to the lower address of the ROM, the current value of the motor is converted to a digital value. An A / D converter for conversion and an initial value setting circuit for the up / down counter are provided. During the period until the edge detection signal of the CS signal is output and the motor current corresponding to the initial value of the set counter, the initial value setting circuit is operated to increase the value of the up / down counter. ROM determined by the value of the up / down counter obtained by the above and the CS signal input to the upper address
And the value of the up-down counter is updated so as to minimize the difference.

〔Example〕

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

In FIG. 1, CS is an input terminal of a CS signal (magnetic pole position detection signal) provided on a rotor shaft of a motor, 10 is an edge detection circuit of CS signal, 30 is an up / down counter, 40 is an initial value setting circuit, Reference numeral 50 denotes a ROM storing signature data, and EC denotes an input terminal for an EC signal (encoder signal).

The basic configuration of the motor control device shown in FIG. 1 includes a commutation sensor (CS) for detecting the magnetic pole position of the field on the rotor shaft of the motor, and an encoder (EC) for finely detecting the position of the rotor shaft. The CS signal is connected to the upper address AdH of the ROM 50, and the output of the up / down counter 30 is connected to the lower address AdL. For example, in the case of a three-phase rectangular wave signal having a phase difference of 120 degrees, the CS signal changes every time the rotor rotates 60 degrees. This change is detected by the edge detection circuit 10 and sent to the up / down counter 30.The minute change in the section of 60 degrees is counted by the input pulse from the EC 30 by the counter 30 and RO
By inputting to the lower address of M50, it is output as ICOM from the ROM 50.

Since this motor is a three-phase motor, three position detectors CSu, CSv, and CSw are provided to generate the CS signal, and this output is output every 60 degrees obtained by dividing the electrical angle 360 degrees into six equal parts. The sine wave output from the ROM 50 is updated every time the CS signal is input.

Therefore, if the zero cross point of the induced voltage of the motor corresponding to the edge detection signal 10 is adjusted with respect to the ROM 50 in which the sign data is stored, the induced voltage and the generated sine wave voltage are synchronized at each edge detection. Synchronous operation.

Since such a motor control device is configured to obtain a sine wave signal from the CS signal and the EC signal, the sine wave signal cannot be obtained because the rotor does not rotate immediately after the power is supplied to the device, but As shown in FIG. 1, since the CS signal is connected to the upper address of the ROM 50, a CS signal corresponding to the rotor position at that time is output from the ROM 50, and according to the output of the ROM corresponding to the CS signal. As a result, an armature current flows through the motor, and the motor can rotate. However, since the phase of the field and the phase of the armature voltage are not the same, the operation is performed in a state where the current value is large and the generated torque is small and the efficiency is low.

The motor shown in FIG. 1 is a synchronous motor, in which the rotation of the rotor field and the rotation field generated in the three-phase stator rotate in synchronization, and the burden torque is controlled by the rotation field and the rotor field. It is known that the armature current is also proportional to the phase angle between the rotor field and the rotor field.
It is also known that the armature current is minimized when the phase angle between the rotation field of the armature and the rotor field is minimum.

In the present invention, as shown in FIGS. 1 and 2, in order to eliminate the above-mentioned low efficiency state and to match the phase of the field and the phase of the armature voltage to achieve a normal operation state, as shown in FIGS. An A / D converter for A / D converting the current iman and an initial value setting circuit 40 for the up / down counter 30 are provided.
To the median of 60 degrees divided by the CS signal, that is, set to an intermediate value between +30 degrees and -30 degrees, and initialize the RO
An output ICOM corresponding to this initial value is output from M50, an armature current is caused to flow according to this output, and this current is accepted as an initial current.

Next, an armature current flows according to the ICOM output from the ROM 50 by the CS signal input to the upper address of the ROM 50, and a digital signal imd obtained by A / D converting a value iman obtained by detecting the current is obtained. The initial value setting circuit 40 accepts the current value and compares it with the initial current value if there is no signal from the edge detection circuit 10 of the CS signal as the current current value, and the current value is larger than the current value of the initial value. In this case, the value of the up / down counter 30 is updated in a decreasing direction, and when there is no edge detection signal again, the next current value is taken in as the current current value.
The current value is compared with the previous current value, and if the current value is smaller than the previous current value, the value of the up / down counter 30 is repeatedly adjusted so as to increase.If the current value matches the previous current value, the initial value is set. Complete the settings.

The sine wave signal from the ROM 50 is read by the output of the up / down counter 30, and the up / down counter
When the value of 30 increases, the phase of the sine wave signal advances, and when the value decreases, the phase lags.If the value of this up-down counter 30 is adjusted so that the armature current value decreases, the current value is minimized. When the difference between the current value and the previous current value disappears, the phase of the field and the armature voltage match, and synchronous operation becomes possible.

When the edge signal is detected by the edge signal detection circuit 10, since the phases of the field and the armature voltage match, the initial value setting ends without comparing the current.

〔The invention's effect〕

Since the motor control device according to the present invention is configured as described above, the phase of the field and the phase of the armature voltage do not match immediately after power-on, and the content of the ROM 50 storing the sine wave signal is read. The contents of the up / down counter 30
The armature current is controlled to a minimum so that the phase matches the phase of the field so that synchronous operation is possible. Since the initial value setting is completed before the rotor rotates, the response is extremely fast. There is a great benefit.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motor control device according to the present invention.
The figure is a flowchart of the initial value setting. 10 ... Detector circuit, 20 ... Converter, 30 ... Counter, 40 ...
... Initial value setting circuit, 50 ... ROM.

Claims (1)

(57) [Claims] An output change of a magnetic field pole position detecting device of a motor having a rotor having a magnetic field and an armature having a three-phase winding disposed with an air gap between the rotor and the rotor. An edge detection circuit for detecting, a ROM storing sine data, and an up / down counter that operates by receiving an output of the edge detection circuit and an output of an encoder for detecting a change in the rotor shaft angle of the motor, A motor control device that connects the CS signal of the magnetic pole position detecting device to the upper address of the ROM and connects the output of the up / down counter to the lower address of the ROM converts the current value of the motor into a digital value. / D converter and an initial value setting circuit for the up / down counter, and a counter temporarily set in the up / down counter by an initialization signal from the initial value setting circuit immediately after startup. The motor current corresponding to the initial value of and the period until the edge detection signal of the CS signal is output, by the initial value setting circuit, to increase the value of the up-down counter, obtained by the operation Comparing the value of the up / down counter with the motor current corresponding to the output of the ROM determined by the CS signal input to the upper address, and updating the value of the up / down counter so that the difference is minimized. A motor control device characterized by the above-mentioned.