JP2007195321A - Brushless motor controller and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make operation control of a brushless motor insusceptible to disturbance. <P>SOLUTION: The brushless motor controller judges whether a position detection signal outputted from a sensor 5 for detecting the rotary position of the rotor of a brushless motor 4 is normal or abnormal using a sensor abnormality detection means 30. If the position detection signal is abnormal, a conduction inhibit timer 46 is actuated and inertial rotation of the rotor of a brushless motor 4 is carried out until a sensor signal mask time elapses. When abnormality of the position detection signal is detected a predetermined number of times continuously, a decision is made that the position sensor 5 is faulty. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor control apparatus including a brushless motor, and a brushless motor control method.

When rotating the brushless motor, it is necessary to switch energization in accordance with the rotational position of the rotor. Since the rotation position of the rotor can be detected by a position detection sensor (for example, a hall element), when the position detection signal output from the hall element is taken into the control device and processing is performed, the energization switching is performed at a timing according to the rotation position. Can be implemented. Here, in the conventional brushless motor control device, the rotation speed and the rotation position are detected by detecting the rising edge and the falling edge of the position detection signal, but if the noise is added to the position detection signal, the rotation is detected. Since the child position cannot be detected correctly, a filter is provided between the Hall element and the control circuit to remove noise contained in the Hall element position detection signal (see, for example, Patent Document 1).
JP 2000-78881 A

Here, since the characteristics of the filter are determined so as to remove noise of a preset size, when noise that is larger (longer duration) than the noise assumed by the filter occurs, Noise could not be removed. In this case, the control circuit determines that the Hall element has failed to prevent malfunction, and stops the brushless motor. However, in reality, a large noise may occur accidentally regardless of the failure of the Hall element, such as a momentary power interruption. In such a case, after the cause of the occurrence of the noise has been eliminated, the operation of the brushless motor can be continued, but it is erroneously determined that the Hall element has failed.
The present invention has been made in view of such circumstances, and it is a main object of the present invention to make it less susceptible to disturbances when controlling the operation of a brushless motor.

The invention according to claim 1 of the present invention for solving the above-mentioned problems is a brushless motor having a rotor and a stator, an inverter circuit for sequentially supplying a drive signal to the brushless motor, and a command signal to the inverter circuit Drive signal output unit that sequentially generates a position detection sensor that detects a rotational position of the rotor and generates a position detection signal, and a plurality of position information memories that store the position detection signal output from the position detection sensor The position detection signals stored in the plurality of position information memories are determined, and when the position detection signals coincide with each other, the position information determination determination means for determining the position detection signal and the position information determination determination means It is determined whether the position detection signal is a predetermined normal signal or an abnormal signal. If the position detection signal is an abnormal signal, a command signal is sent to the drive signal output unit. Sensor abnormality detecting means for stopping liveness, and when the sensor abnormality detecting means determines that the position detection signal is an abnormal signal, the position detection signals are taken in the plurality of position information memories for a predetermined time. A brushless motor control device comprising a prohibiting timer means.
This brushless motor control device checks whether the position detection signal determined using a plurality of position information memories is normal or abnormal, and if it is determined to be abnormal, the timer means is activated for a predetermined time. During this period, the capture of the position detection signal is prohibited. For this reason, the drive signals generated based on the position detection signal cannot be sequentially generated, and the energization to the brushless motor is stopped while the timer means is activated.

According to a second aspect of the present invention, in the brushless motor control device according to the first aspect of the present invention, when the predetermined time elapses, the timer means receives the position detection signal from the rotor position detection sensor. It is characterized by being permitted to take in.
In this brushless motor control device, the time to stop energization is managed by the timer means, and when a time interval longer than the duration of noise due to a momentary power interruption or the like passes, the acquisition of the position detection signal is started again.

According to a third aspect of the present invention, a drive signal is sequentially supplied from an inverter circuit to a brushless motor having a rotor and a stator based on a command signal generated by a drive signal output unit, and the rotational position of the rotor is detected. A control method of a brushless motor control device that outputs a sensor and controls the drive signal output unit based on a position detection signal generated by the position detection sensor, wherein the position detection signal is a predetermined normal signal. Determining whether the signal is an abnormal signal, and stopping the generation of the command signal when the drive signal output unit determines that the signal is abnormal, and detecting the position when the position detection signal is determined to be abnormal. A step of prohibiting the acquisition of the position detection signal from the sensor for a predetermined time, and the position detection from the position detection sensor when the predetermined time has elapsed. And a control method for a brushless motor, comprising the steps of permitting the signal capture, the.
In this brushless motor control method, it is checked whether the position detection signal acquired from the position information sensor is normal or abnormal, and if it is determined to be abnormal, the timer means is activated and the brushless motor is not energized. Like that. When a time interval longer than the duration of noise due to a momentary power interruption or the like has passed, the timer means restarts taking in the position detection signal and resumes drive signal switching control.

  According to the present invention, since the position detection signal is not acquired while the timer means is in operation, when noise having a relatively long duration occurs, such as noise generated when the power supply is momentarily interrupted. The position detection signal can be prevented from being acquired while such noise is occurring. For this reason, since it becomes easy to distinguish between noise that occurs accidentally such as a momentary power interruption and a signal at the time of failure of the position detection sensor, the accuracy of failure determination of the position detection signal can be improved.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a brushless motor control device 1 includes a power source 2, an inverter circuit 3 that converts a DC current from the power source 2 into a three-phase AC current, and a brushless motor that is an electric motor supplied with current from the inverter circuit 3. The motor 4, a position detection sensor 5 that detects the rotational position of the rotor of the brushless motor 4, and a control unit 6 that controls the rotation of the brushless motor 4.

  The brushless motor 4 includes a stator and a rotor as main components. A stator is formed by winding three stator windings U, V, and W around the stator. The stator windings U, V, W are connected by so-called delta connection or star connection. The rotor includes a rotation shaft and a permanent magnet in which a plurality of magnetic poles (N pole and S pole) are arranged along the circumferential direction of the rotation shaft. The brushless motor 4 may be an inner rotor type or an outer rotor type.

  As the position detection sensors 5, for example, a Hall IC (Integrated Circuit) including a Hall element and an electronic circuit is used, and three position detection sensors 5 are arranged at predetermined positions where the rotation position of the rotor can be detected. An example of the position detection signal output from these position detection sensors 5 is shown in FIG. In FIG. 2, the horizontal axis represents an electrical angle, and the outputs of three position detection sensors are arranged in the vertical direction. The output of each position detection sensor is periodically switched between a high level (H) and a low level (L). The rotational position of the rotor can be specified by a combination of these three signal levels.

Next, the configuration of the control unit 6 shown in FIG. 1 will be described. Details of processing in each unit of the control unit 6 will be described later.
The control unit 6 includes a position information first memory 11 that stores a position detection signal output from the position detection sensor 5, a position information second memory 12, and a position information third memory 13. The position information first memory 11 is connected to the change position information continuity determination unit 14 and the position information confirmation determination unit 15. The output of the change position information continuity determination unit 14 is connected to the drive signal output unit 16. The drive signal output unit 16 is connected to the inverter circuit 3 in a controllable manner.
The position information confirmation determination means 15 is connected to the position information first memory 11, and is also connected to the position information second memory 12 and the position information third memory 13. The position information confirmation determination unit 15 is composed of a position information confirmation determination unit 21 and a position information memory 22 at the time of confirmation, each of which is connected in series with each other to confirm the position detection signal and the confirmed position detection signal. Memory is possible. The position information confirmation determination unit 21 can control writing of the memories 11 to 13. The output of the fixed position information memory 22 is connected to the fixed position information normality determination unit 31 of the sensor abnormality detection means 30.

The sensor abnormality detection means 30 has a fixed position information normality determination unit 31, and the fixed position information normality determination unit 31 includes a startup position information determination determination unit 32 and a fixed position information continuity determination unit 33. The fixed position information identity determination unit 35 and the sensor abnormality detection unit 34 are connected in series. Furthermore, the output of the fixed position information normality determination unit 31 can be directly input to the sensor abnormality detection unit 34.
The output of the sensor abnormality detection unit 30 is connected to the drive signal output unit 16, the normal sensor count unit 36, and the sensor failure determination unit 40. The drive signal output unit 16 is connected to the outputs of the activation position information determination unit 32, the determination position information identity determination unit 35, and the sensor abnormality detection unit 34. Further, the output of the fixed position information continuity determination unit 33 is also connected through the sensor normal number counting unit 36. The output of the sensor abnormality detection unit 34 is also connected to the sensor abnormality number counting unit 41 of the sensor failure determination means 40.

  In the sensor abnormality determination means 40, a sensor abnormality frequency counting unit 41 and a sensor failure determination unit 42 are connected in series. The output of the sensor abnormality frequency count unit 41 is connected to the sensor normal frequency count unit 36 via the sensor normal frequency reset unit 43. Conversely, a signal is input from the sensor normal number count unit 36 to the sensor abnormal number count unit 41 via the sensor abnormal number reset unit 44. The output of the sensor failure determination unit 42 is connected to a sensor failure determination unit 45 and an energization prohibition timer 46 that is a timer means. The output of the energization prohibition timer 46 can control the writing of the memories 11 to 13. In this embodiment, the position detection signal of the position detection sensor 5 is masked so that data is not input to the memories 11 to 13.

Next, the operation of this embodiment will be described.
When the brushless motor 4 is rotated, the drive signal output unit 16 sequentially generates command signals. This command signal is supplied to the inverter circuit 3. In the inverter circuit 3, a drive signal corresponding to the command signal is supplied to the brushless motor 4. Specifically, a current is supplied to a predetermined stator winding, and the rotor is rotated by exciting a coil formed of the stator winding. When the rotor rotates, the three position detection sensors 5 output position detection signals corresponding to changes in the magnetic poles of the rotor. The position detection signal is first input to the position information first memory 11. The position information first memory 11 stores the position detection signal and outputs the position detection signal to the change-time position information continuity determination unit 14 to execute update processing of the command signal (and a drive signal associated therewith). The change position information continuity determination unit 14 determines the continuity between the position detection signal input this time and the position detection signal that has already been determined last time. For example, when energization is switched in the order of stage 0, stage 1, stage 2, stage 3, stage 4, and stage 5 as shown in FIG. 2, it corresponds to stage 1 next to the position detection signal corresponding to stage 0. If a position detection signal is input, it is considered that continuity has been established. The drive signal output unit 16 outputs a command signal corresponding to the rotational position to the inverter circuit 3. If continuity is denied, for example, if a position detection signal corresponding to stage 5 is input next to a position detection signal corresponding to stage 0 in FIG. 2, the command signal is not updated.

Further, after the position detection signal is stored in the position information first memory 11, the position information is detected in the position information second memory 12 and the position information third memory 13 every time a predetermined time interval (for example, several tens of μs) elapses. The position detection signal output from the position detection sensor 5 is captured and stored in the signal. The position detection signals stored in each of the three memories 11 to 13 are sent to the position information confirmation determination means 15. The position information confirmation determination unit 21 determines whether or not three position detection signals acquired at a predetermined time interval (for example, ts in FIG. 2) match. For example, if noise occurs at the timing when the position information second memory 12 captures the position detection signal after the position information first memory 11 captures the position detection signal, the position detection signals of the two memories 11 and 12 become inconsistent. . At this time, the position information confirmation determination unit 21 outputs a command signal so that each of the memories 11 to 13 receives the position detection signal again. As a result, the position detection signal is taken again from the position information first memory 11 in order. Thereby, noise less than the time interval ts in FIG. 2 is removed at this stage.
When the position detection signals of the memories 11 to 13 coincide with each other, the position detection signal (position information at the time of determination) is stored in the position information memory 22 at the time of determination, and the position detection signal is detected by the sensor abnormality detection means 30. To the position information normality determination unit 31 at the time of confirmation.

  The fixed position information normality determination unit 31 determines whether the position detection signal is normal. For example, when the position detection signal of the U-phase position detection sensor 5 in the stage 3 of FIG. 2 becomes a signal tb as indicated by a two-dot chain line, the signal levels of the three position detection sensors 5 are during normal operation. Then, when the position detection signal cannot occur, a command signal is output to the sensor abnormality detection unit 34. On the other hand, when it is determined that the position detection signal is normal, the position detection signal is output to the startup position information determination unit 32. The starting position information confirmation determination unit 32 determines whether or not the rotational position of the rotor when the brushless motor 4 is activated is confirmed. When the rotational position at the time of activation is not confirmed, the rotational position at the time of activation is confirmed. In this case, the drive signal output unit 16 starts energization control using the position detection signal acquired from the determined position information normality determination unit 31. On the other hand, when the brushless motor 4 is already rotating, since the rotational position at the time of activation is fixed, a position detection signal is output to the fixed position information continuity determination unit 33.

The fixed position information continuity determination unit 33 determines the continuity of the position detection signal. For example, when the energization is switched in the order of stage 0, stage 1,..., Stage 5 as shown in FIG. 2 in order to rotate the motor once, for example, next to the position detection signal corresponding to stage 0. If a position detection signal corresponding to stage 1 is input, it is considered that continuity has been established.
On the other hand, for example, if a position detection signal corresponding to stage 5 is input next to a position detection signal corresponding to stage 0 in FIG. 2, the continuity is denied because the order is different from the order described above. If continuity is denied, the determined position information identity determination unit 35 compares the previously detected position detection signal with the previously determined position detection signal. If the two position detection signals match, it is assumed that the noise is only in the middle of the same phase, and that the identity is established.

  When the continuity or identity of the position detection signal is confirmed, the position detection signal is regarded as normal. When the continuity and identity of the position detection signal are denied, and when a position detection signal that cannot occur during normal operation is detected, the position detection signal is regarded as abnormal. As a case where the position detection signal is regarded as abnormal, for example, noise having a duration longer than the time interval ts (see FIG. 2) for fetching the position detection signal into the three memories 11 to 13 is generated, and noise is generated. There are cases where the position detection signal has been confirmed.

In this embodiment, operation control and failure determination are performed as shown in the flowchart of FIG. 3 based on the check result of whether the position detection signal is normal or abnormal.
As described above, the position detection signal is checked by each of the memories 11 to 13, the position information confirmation determination unit 15, and the sensor abnormality detection unit 30 (step S101). If the position detection signal is normal ( In step S101, the motor drive output is made (step S102). That is, the drive signal output unit 16 updates the command signal at a suitable timing and continuously rotates the rotor of the brushless motor 4. At this time, the sensor normal number counting unit 36 increments the sensor normal counter (step S103), and then makes a determination to return to the normal sensor state (step S104). That is, if the count value of the sensor normal counter is less than the normal determination threshold value prepared in advance, it is determined that the normal state has not yet been determined (No in step S104), and the process returns to step S101. In contrast, if the count value has reached the normal determination threshold, the sensor abnormality frequency reset unit 44 resets the sensor abnormality counter of the sensor abnormality frequency counter 41 (step S105), and the process returns to step S101.

  On the other hand, when the position detection signal is checked, if it is regarded as an abnormal signal (No in step S101), a command signal is output from the sensor abnormality detection unit 34 to the drive signal output unit 16 to drive the motor. The output is stopped (step S106). Further, the sensor normal counter of the sensor normal number counting unit 36 is reset from the sensor abnormal number counting unit 41 through the sensor normal number reset unit 43 (step S107). Thereafter, the sensor abnormality frequency counting unit 41 increments the sensor abnormality counter by one (step S108).

Next, the sensor failure determination unit 42 determines whether the sensor failure is confirmed (step S109). That is, if the count value of the sensor abnormality frequency counting unit 41 is less than a prepared failure determination threshold value, a failure is not determined at this stage (No in step S109), and the energization prohibit timer 46 is started. (Step S110). During this time, even if the position detection sensor 5 outputs a position detection signal, the position detection signal is not stored in each of the memories 11 to 13, so that the position detection signal is masked. When the position detection signal is masked, the drive signal output unit 16 stops outputting the command signal, and the output to the brushless motor 4 is stopped (step S111). The energization prohibit timer 46 stops the output of the command signal of the drive signal output unit 16 until a preset time (sensor signal mask time) elapses (No in step S112). During this time, the brushless motor 4 continues to rotate with inertia. When the energization prohibit timer 46 reaches the sensor signal mask time, the process returns to step S101.
On the other hand, when the sensor failure determination unit 42 determines a sensor failure in step S109, if the count value of the sensor abnormality counter of the sensor abnormality number counting unit 41 has reached the failure determination threshold value (Yes in step S109). The sensor failure determination unit 45 determines that the position detection sensor 5 has failed (step S113).

  Here, while the position detection sensor 5 outputs a normal signal with correct continuity, the sensor abnormality counter (sensor abnormality number counting unit 41) does not change. When the position detection sensor 5 outputs an abnormal signal for some reason or loses continuity, the sensor normal counter (sensor normal number counting unit 36) is reset, while the sensor abnormal counter is incremented. When the position detection signal is abnormal only once due to accidental noise, the normal operation is performed thereafter, and the sensor normal counter is gradually incremented. If the sensor abnormality does not occur until the sensor normal counter reaches the normal determination threshold, it is considered that the abnormality that occurred first is not a failure of the position detection sensor 5 (at this time, the sensor abnormality counter is reset). .

  When a sensor abnormality occurs continuously, the sensor normal counter is reset each time, while the sensor abnormality counter is incremented. If the sensor abnormality counter reaches the failure determination threshold before the sensor normal counter reaches the normal determination threshold, it is considered that the position detection sensor 5 has failed. Similarly to the above, even when the sensor abnormality counter is counting up, when the sensor normal counter reaches the normal determination threshold, the brushless motor 4 can be rotated without any trouble, and therefore, it is regarded as not a sensor failure.

  The threshold value for normal determination of the sensor normal counter is set to a value sufficient to reliably detect that the sensor has returned to the normal state. A sufficient threshold value is set for the sensor abnormality counter failure determination threshold so that noise is not erroneously detected as a sensor failure. As the threshold value of each counter, a value larger than a value corresponding to one rotation of the rotor is used, such as a value corresponding to 24 stages in FIG.

  Further, when a sensor abnormality is detected, the energization prohibit timer 46 prevents the position detection signal from being input for a predetermined time. As a result, the current is not supplied to the brushless motor 4 with an incorrect drive signal due to the rise or fall of the position detection signal due to noise. For this reason, the sensor signal masking time of the energization prohibition timer 46 is longer than the general instantaneous interruption time of the power supply 2 and is used so long as the rotor of the brushless motor 4 can continue to rotate by inertia. As a result, an incorrect drive signal is generated due to the rise or fall of the position detection signal due to noise, and current based on the incorrect drive signal is not supplied to the brushless motor 4.

  According to this embodiment, when a sensor abnormality is detected, the energization of the brushless motor 4 is stopped while the energization prohibit timer 46 is operating, so that the rotor is in a free-run state, and noise is generated. The sensor failure is not immediately determined when the error occurs. For this reason, although it is longer than a normal noise like the momentary interruption of the power supply 2, when it is not a sensor failure, a misjudgment can be prevented and the reliability of the brushless motor 4 can be improved.

  In addition, this invention is not limited to embodiment, It is possible to apply in the range which does not deviate from the main point.

It is a block diagram which shows the structure of the brushless motor control apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the output of a position detection sensor. It is a flowchart explaining the process of a brushless motor control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor control apparatus 3 Inverter circuit 4 Brushless motor 5 Position detection signal 6 Control part 11 Position information 1st memory 12 Position information 2nd memory 13 Position information 3rd memory 15 Position information confirmation determination means 16 Drive signal output part 30 Sensor abnormality Detection means 46 Energization prohibition timer (timer means)

Claims (3)

A brushless motor having a rotor and a stator;
An inverter circuit for sequentially supplying drive signals to the brushless motor;
A drive signal output section for sequentially generating command signals to the inverter circuit;
A position detection sensor that detects a rotational position of the rotor and generates a position detection signal;
A plurality of position information memories for storing position detection signals output from the position detection sensors;
Position information determination determination means for determining position detection signals stored in a plurality of position information memories and determining the position detection signals when the position detection signals coincide with each other;
It is determined whether the position detection signal determined by the position information determination determination means is a predetermined normal signal or an abnormal signal, and if it is an abnormal signal, a command signal is generated in the drive signal output unit Sensor abnormality detection means for stopping
Timer means for prohibiting capturing of position detection signals in the plurality of position information memories for a predetermined time when the sensor abnormality detection means determines that the position detection signal is an abnormal signal;
A brushless motor control device comprising:   The timer means is configured to permit the plurality of position information memories to receive position detection signals from the rotor position detection sensor when a predetermined time has elapsed. The brushless motor control device described in 1. A drive signal is sequentially supplied from an inverter circuit based on a command signal generated by a drive signal output unit to a brushless motor having a rotor and a stator, and a rotational position of the rotor is output by a position detection sensor, thereby detecting the position. A control method of a brushless motor control device for controlling the drive signal output unit based on a position detection signal generated by a sensor,
Determining whether the position detection signal is a predetermined normal signal or an abnormal signal, and stopping the generation of the command signal in the drive signal output unit when it is determined as an abnormal signal;
When it is determined that the position detection signal is abnormal, the step of prohibiting the capture of the position detection signal from the position detection sensor for a predetermined time;
Allowing a position detection signal to be taken in from the position detection sensor when a predetermined time has elapsed;
A method for controlling a brushless motor, comprising:

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