JPH07123771A - Speed controller for dc brushless motor - Google Patents

Abstract

PURPOSE:To provide a driver for a DC brushless motor in which an erroneous operation of an oscillating state of a pole position detection signal is prevented and which obtains effective starting characteristics. CONSTITUTION:After a signal from a pole detecting element 2 is once detected at a change of a level, a new level change is ignored while a certain predetermined time is elapsed, and the signal is input as a pole detection signal to a phase distributor 3 through a signal holder 4 having a function of holding the previous level to decide an energizing timing of a coil. As a result, even if the signal of the element 2 becomes unstable, the detection signal regarding the phase distribution becomes stable, thereby effectively starting a motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed controller for a DC brushless motor, which uses a signal from a magnetic pole position detecting element such as a Hall element or a Hall IC as a magnetic pole position detecting signal of a rotor magnet of a motor.

[0002]

2. Description of the Related Art A DC brushless motor detects the magnetic pole position of a rotor magnet by a magnetic pole position detecting element such as a Hall element or a Hall IC instead of a brush, and determines the timing of energizing a motor coil based on the detection signal. FIG. 1 shows a configuration of a magnetic pole detection section using a Hall IC and a timing example of each signal for driving the. The position of the rotor magnet 1 is detected by the magnetic pole position detecting element 2, and the signal levels of the three phases are input to the phase distributor 3 to determine the timing of energizing the coils according to the magnetic pole position (phase distribution). Driving a DC brushless motor.

[0003]

In the actual motor, the mounting position of the rotor magnet 1 and the magnetic pole position detecting element 2 are used.
Since there is a distortion of the magnetic flux distribution around the Hall signal element due to the displacement of the mounting position of the motor and the influence of the magnetic flux generated from the coil of the motor, the switching timing of the magnetic flux detection signal is slightly displaced compared to the ideal case. Cause Therefore, at the moment when the motor starts to move from the stopped state, the magnetic flux detection signal becomes an oscillating state as shown in FIG. 2 depending on the position of the rotor magnet 1 and the energization state of the coil, and the energization of the motor coil occurs. There was a problem that the timing was wrong and the motor did not start.

The object of the present invention is to prevent the malfunction caused by the oscillation state of the magnetic pole detection signal. It is an object of the present invention to provide a drive device for a DC brushless motor that can obtain a reliable starting characteristic.

[0005]

Means for Solving the Problems The magnetic pole detection signal becomes oscillating when the motor is started when the position of the rotor magnet 1 is at the moment when the magnetic pole detection signal is switched. At the next moment, when the magnetic pole detection level should originally be stable according to the rotation direction of the motor, erroneous detection occurs due to the magnetic flux distortion in the surroundings, and the position of the rotor magnet 1 is deviated due to the improper energization of the motor coil.
It is caused by the repetition of returning to the place just before.

Therefore, once the change in the level of the magnetic pole position detection signal is detected, if the new signal is not accepted until a certain period of time elapses, the above-mentioned problem does not occur. At this time, even if the level at which the change is initially detected is different from what it should be and the rotor magnet 1 moves in the opposite direction, the rotor magnet 1
Since the position of is changed, the magnetic pole detection signal does not become oscillating, and the motor rotates in the normal direction from the next moment.

As described above, according to the present invention, the detection signal is held for a certain period of time after the change of the magnetic pole position is detected, and a new magnetic pole position detection signal input during that period is ignored. This prevents the magnetic pole detection signal from becoming oscillating.

[0008]

The operation of the present invention will be described with reference to FIG. FIG. 3 shows only the U phase in the magnetic pole position detection signal having three phases.

Once the magnetic pole position signal detects a level change, it is input to the phase distributor 3 via a signal holder 4 having a function of holding the level for a certain period of time. By doing so, even if the magnetic pole position detection signal initially becomes unstable in level, a signal of a stable level is supplied to the phase distributor 3 and the motor coil is energized. It will not continue in an oscillatory state. Since inertial force acts when the motor starts to rotate, the rotor magnet tries to keep rotating in a certain direction, so that the level of the magnetic pole position detection signal does not become unstable and the motor can be reliably started.

[0010]

EXAMPLE FIG. 4 shows an example of the present invention.

The drive control is performed by the program of the microcomputer 5, and the phase distribution processing is performed by interrupting the rising and falling edges of the magnetic pole detection signal. In the phase distribution processing routine, the time elapsed since the previous processing is monitored by a timer, and if a fixed time has not elapsed since the previous processing was performed, no processing is performed and the interrupt returns.
Thus, once the level change of the magnetic pole detection signal is detected, the output is held until a certain period of time elapses after the phase distribution signal corresponding to the signal is output. In this way, after detecting the level change of the magnetic pole detection signal once,
It is possible to ignore the new magnetic pole position detection signal input until the fixed time has elapsed.

The present embodiment is based on a program of a microcomputer, but the timer output triggered by a change in the level of the magnetic pole position signal is used as the enable signal of the holding circuit for the magnetic pole position detection signal. It is possible to realize the operation of.

[0013]

According to the present invention, it is possible to provide a drive device for a DC brushless motor which can obtain a reliable starting characteristic while preventing an erroneous operation in which the magnetic pole position detection signal becomes oscillating.

Further, although the present invention takes into consideration a countermeasure against the situation where the magnetic pole detection signal becomes unstable due to the distortion of the magnetic flux distribution in the surroundings, the same is caused by noise due to a large current at the time of starting the motor. The same effect can be obtained even when the magnetic pole position signal becomes unstable.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration and signal timing of a magnetic pole position detector.

FIG. 2 is a diagram showing an oscillating state of a magnetic pole position detection signal.

FIG. 3 is an explanatory diagram of an operation of the present invention.

FIG. 4 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotor magnet, 2 ... Magnetic pole position detection element, 3 ... Phase distribution part, 4 ... Signal holding part, 5 ... Microcomputer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location 8938-5H H02P 6/02 351 K

Claims (1)

[Claims] 1. In a speed controller for a DC brushless motor which uses a Hall element signal or a Hall IC signal as a magnetic pole position detection position signal, a change in magnetic pole position is prevented in order to prevent malfunction due to incorrect detection of the magnetic pole position detection signal. DC brushless motor characterized by driving the motor by holding the detection signal for a certain period of time after detecting the current and ignoring a new magnetic pole position detection signal input during the certain period of time. Speed control device.