JPH04105585A - Dc brushless motor drive controller - Google Patents

Abstract

PURPOSE:To eliminate trouble such as oscillation of circuit by providing means for driving a motor synchronously at the time of starting, a counter electromotive force detecting means, and means for switching from driving through the starting means to driving through the counter electromotive force detecting means thereby effecting switching of driving after confirmation of the rotation of motor. CONSTITUTION:At first, a CPU 1 outputs a three-phase synchronous driving rotation signal which is then selected by a selector 2 and applied through a driver 3 onto a motor 3. The motor 4 is driven untill a predetermined rotational speed is reached. Driving of the motor is once turned OFF completely, before driving through counter electromotive force takes place, in order to prevent erroneous detection of the motor rotation due to a voltage induced by the driving current. At that time point, the CPU 1 takes in a digital output from an A/D converter 7 and makes a judgment whether the digital value is higher than or equal to a predetermined value.

Description

TECHNICAL FIELD The present invention relates to a DC brushless motor drive control device, and more particularly to a DC brushless motor drive control device that is used in a spindle motor of a magnetic disk device and does not use a position sensor.

BACKGROUND ART A drive control device for a DC brushless motor of this type has a configuration shown in a block diagram of FIG.

The figure shows an example of a three-phase motor, and the CPU
generates a three-phase synchronous rotation signal simulating the activation of the motor 4, and also generates a switching instruction signal 11 to the selector 2 when the rotational speed of the motor increases.

The selector 2 inputs the three-phase synchronous rotation signal from the CPU 1 and the motor position signal (three phases) obtained from the back electromotive force detection circuit 5, and outputs these three-phase signals in response to the switching instruction signal 11 from the CPUI. Derived alternatively.

The driver 3 outputs the signal derived from the selector 2 as a three-phase drive signal for the spindle motor 4. The back electromotive force detection circuit 5 detects the back electromotive force of each phase generated by the rotation of the spindle motor 4, and generates a position signal necessary for determining which phase of the motor should be excited. , this signal is manually input to the selector 2.

In such a configuration, selector 2 is set to C at startup.
It is controlled to select the three-phase synchronous rotation signal from the PUI. Therefore, the motor 4 is started and controlled by this synchronous rotation signal from the CPU 1, and when a certain rotation speed is reached, the CPU controls the selector 2 to select the position signal of the back electromotive force detection circuit 5 by the switching instruction signal 11. do. As a result, each phase of the motor 4 is sequentially excited to maintain synchronous rotation.

In such a conventional DC brushless motor drive control device that does not use a position sensor, it is not possible to detect whether the motor 4 is reliably rotating when switching from synchronous drive using the CPU to drive based on back electromotive force detection. Therefore, even if the motor is not rotating due to out-of-synchronization or the like, the drive is forcibly switched to drive based on back electromotive force detection. Therefore, there is a drawback that problems such as oscillation of the circuit occur.

OBJECTS OF THE INVENTION An object of the present invention is to provide a DC brushless motor drive control device that eliminates inconveniences such as circuit oscillation by switching to drive based on back electromotive force detection after confirming motor rotation.

Composition of the Invention According to the present invention, there is provided a drive control device for a DC brushless motor that does not use a position sensor, which includes a starting means for generating a drive signal for synchronously driving the motor at the time of starting, and a back electromotive force detection means that generates a position signal of the motor from the generated back electromotive force; and a back electromotive force detecting means that detects the magnitude of the back electromotive force and, when the magnitude of the back electromotive force reaches a predetermined value, detects the back electromotive force from driving by the starting means. A DC characterized in that it includes a switching means for switching to driving by the detection means.
A C brushless morph motion control device is obtained.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and parts equivalent to those in FIG. 8 are designated by the same reference numerals.

In this example, to the configuration shown in FIG. The configuration is such that the digital signal from the /D converter 7 is processed by the CPUI.

FIG. 2 is a processing flow showing the operation of the CPUI. First, the CPU sends out a three-phase synchronous drive rotation signal (step 21), and the selector 2 selects this signal and applies it to the motor 4 via the driver 3.

Thereby, the motor 4 is driven until it reaches a constant rotation speed. Then, before driving by the back electromotive force, the -degree drive is completely turned off (step 22).The reason for completely turning off the drive is to detect the motor rotation in a later step using the voltage generated by the drive current. This is to prevent malfunction.

At this point, the CPU takes in the digital output of the A/D converter 7, and determines whether this digital value is greater than or equal to a predetermined value (step 23). That is, it is determined whether there is a sufficient back electromotive force value (sine curve wave) of the A phase generated by the rotation of the motor 4, and whether this value is sufficient for driving by detecting the back electromotive force.

If it is not sufficient, it is determined that the motor does not rotate or is insufficient (step 24), so step 21,
22.23 will be repeated.

If it is determined in step 23 that it is sufficient, the CPU
switches the selector 2 using the switching instruction signal 11, supplies the position signal from the back electromotive force detection circuit 5 to the driver 3, and performs driving by the back electromotive force (step 25).
.

FIG. 3 is a block diagram of another embodiment of the present invention.
Parts equivalent to those in the figure are indicated by the same reference numerals.

To describe only the parts that are different from the embodiment shown in FIG.
After the phase back electromotive force is smoothed by the rectifying and smoothing circuit 6, in this example, it is compared with a predetermined reference level by a level comparator 8, and the comparison output is inputted to the CPUI.

FIG. 4 is a processing flow showing the operation of the CPUI in the embodiment of FIG. 3, and steps that are the same as those in the flow of FIG. 2 are indicated by the same reference numerals. Regarding step 33, which is different from the flow in FIG. 2, the CPU synchronous drive (step 21) is completely turned off (step 2
2), the output of comparator 8 becomes “H” (high)
It is determined whether the level has been reached (step 33).
.

In other words, when the smooth rectification level of the back electromotive force exceeds the reference level when the rotational speed of the motor 4 due to synchronous drive exceeds a certain value, the level comparator 8 outputs "H".
″ level output is now generated.

Therefore, the CPU should judge whether or not this "H" level is output from the level comparator 8 (step 33).
If so, an instruction signal 11 is generated to switch to driving by back electromotive force.

Incidentally, if the output of the comparator 8 is at the "L" (low) level, the motor is not rotating or is rotating insufficiently, so the synchronous drive is started again.

FIG. 5 is a block diagram of another embodiment of the present invention;
．． Parts that are equivalent to those in Figure 3 are designated by the same reference numerals. 1st
, 3. To describe only the parts that are different from the embodiment shown in FIG.
A comparator 9 compares the back electromotive forces of the phase and B phase, and the level change of this comparison output is monitored by the CPU.

6(a) shows the waveform of two manual inputs (A phase and B phase) of the comparator 9, and FIG. 6(b) shows the output waveform of the comparator 9. If the rotation of motor 4 is normal, comparator 9
The output waveform of is “H” and “L” as shown in Figure 6(b).
Repeat this at regular intervals.

Therefore, for a certain period of time, T Takeko's comparator output is
When the motor changes from "H" to "L" to "L" to "H", it is determined that the motor is rotating normally, and the selector 2 is switched by the switching instruction signal 11 to switch from synchronous startup. It switches to driving by back electromotive force.

The operation flow of the CPU in this case is shown in FIG. 7, and the determination process in step 43 is the process of monitoring the change in the comparator output level in FIG. 6(b). The other steps are the same as those in the case of FIG. 2.4.

In the above embodiments, the back electromotive force for detecting the rotation of the motor is the A phase or the A and B phases, but the present invention is not limited thereto. Moreover, it goes without saying that the motor is not limited to a three-phase motor.

Effects of the Invention As shown above, according to the present invention, when switching from synchronous drive to drive by back electromotive force, the rotation of the motor is checked and the switch is made only when the motor is rotating reliably, so that drive is disabled. This has the effect of preventing problems such as oscillation and oscillation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the blocks in FIG. 1, FIG. 3 is a block diagram of another embodiment of the present invention, and FIG. 5 is a block diagram showing another embodiment of the present invention, FIG. 6 is a time chart showing the operation of the blocks in FIG. 5, and FIG. 7 is a flowchart showing the operations of the blocks in FIG. 5. A flowchart showing the operation, FIG. 8 is a block diagram of a conventional DC brushless motor drive control device. Explanation of symbols of main parts 1... CPU 2... Selector 4... Motor 5... Back electromotive force detection circuit 7... A /D converter 8...Level converter 9...Comparator

Claims (2)

[Claims] (1) A drive control device for a DC brushless motor that does not use a position sensor, which includes a starting means for generating a drive signal for synchronously driving the motor at startup, and a counter electromotive force generated as the motor rotates. a back electromotive force detection means for generating a position signal of the motor; detecting the magnitude of the back electromotive force, and when the magnitude of the back electromotive force reaches a predetermined value, switching from driving by the starting means to driving by the back electromotive force detection means; A DC brushless motor drive control device comprising: switching means. (2) A drive control device for a DC brushless motor that does not use a position sensor, which includes a starting means for generating a drive signal for synchronously driving the motor at startup, and a counter electromotive force generated as the motor rotates. a back electromotive force detection means for generating a position signal of the motor; and detecting a change in the back electromotive force during a predetermined period, and when the change in the back electromotive force has undergone a predetermined change, driving by the starting means to be controlled by the back electromotive force detection means. 1. A DC brushless motor drive control device comprising: switching means for switching to drive.