JP2007166711A - Method and apparatus for driving/controlling brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a rotation relative to a fluctuation in a power supply voltage, regardless of the rotational state of a motor. <P>SOLUTION: A correction pattern is selected among a plurality of the correction patterns, by considering the duty of a drive pulse signal, calculated by a predetermined arithmetic expression as an index (S202-S210), and the duty of the drive pulse signal is corrected, based on the selected correction pattern, in response to the battery voltage applied to the brushless motor 51 (S212-S216). The rotation can be stabilized, by carrying a current to stator windings 52a-52c based on the corrected duty, regardless of the fluctuations in the power supply voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor, and more particularly, to an improvement in operation stability against fluctuations in power supply voltage.

Conventionally, as a brushless motor of this type and its drive control device, for example, based on a brushless motor including a rotor made of a permanent magnet and a fixed stator winding, and an induced voltage in the stator winding. It is known and well known that the rotation of the brushless motor can be controlled by detecting the rotor position and controlling the energization to the stator winding based on the rotor position (for example, Patent Document 1) reference).
By the way, such a brushless motor is used, for example, for driving a blower fan in an air conditioner of a vehicle. In particular, in a vehicle or the like, fluctuations in power supply voltage are unavoidable. It is necessary to set the rotation speed. For this reason, various drive control methods for stabilizing the rotation with respect to fluctuations in the power supply voltage have been proposed. For example, as a well-known measure, there is a method of correcting the duty of the PWM drive signal applied to the stator winding in accordance with the fluctuation amount of the power supply voltage (see, for example, Patent Document 1). ).

Japanese Patent Laid-Open No. 2001-103785 (page 3-6, FIGS. 1 to 7)

  However, the conventional correction of the PWM drive signal based on the fluctuation amount of the power supply voltage as described above is based on a single correction formula or a single correction map, and thus cannot always guarantee stable rotation. It was. That is, even if the power supply voltage fluctuates and the rotation speed fluctuates from the original rotation speed, the fluctuation in the rotation speed is not simply determined solely by the fluctuation amount of the power supply voltage. It also differs depending on the rotation state when the change occurs, that is, the driving state. However, conventionally, the correction is made only by the magnitude of the voltage fluctuation without considering such other factors. Therefore, the correction is not appropriate in various rotation states, and the correction is vigorous. It must be an average value. Therefore, depending on the rotation state, sufficient stabilization cannot always be achieved.

The present invention has been made in view of the above circumstances, and provides a drive control method and apparatus for a brushless motor capable of obtaining stable rotation against fluctuations in power supply voltage regardless of the rotation state of the motor. It is.
Another object of the present invention is to provide a drive control method and apparatus for a brushless motor capable of highly accurate rotation control.

In order to achieve the above object of the present invention, a brushless motor drive control method according to the present invention comprises:
A drive control method for a brushless motor that can control the rotational speed of the brushless motor by changing the duty of a drive pulse signal applied to the stator winding of the brushless motor,
A correction pattern is selected from a plurality of correction patterns using the duty of the drive pulse signal calculated by a predetermined arithmetic expression as an index, and the power supply voltage applied to the brushless motor is selected based on the selected correction pattern. The duty is corrected, and the correction result is used as the duty of the drive pulse signal to apply the drive pulse signal to the stator winding.
In order to achieve the above object of the present invention, a brushless motor drive control device according to the present invention comprises:
A brushless motor drive control device configured to be able to control the rotational speed of the brushless motor by changing the duty of the drive pulse signal applied to the stator winding of the brushless motor,
Storage means for storing a plurality of correction patterns;
Correction pattern selection means for selecting a correction pattern from among a plurality of correction patterns stored in the storage means, using the duty calculated by a predetermined arithmetic expression as an index;
Correction value determining means for determining a correction value according to a power supply voltage applied to the brushless motor based on the selected correction pattern;
Duty correction means for correcting the duty using the correction value determined by the correction value determination means;
And an energization control unit that controls energization of the brushless motor based on a correction result in the duty correction unit.

  According to the present invention, unlike the prior art, a plurality of factors are selected as factors causing the motor output fluctuation, and the output fluctuation can be compensated in consideration of the plurality of factors. In other words, it is possible to obtain a stable rotation state regardless of whether the output of the motor is low or not regardless of whether the output is low or high, and more reliable brushless motor drive control is possible. There is an effect.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of a brushless motor drive control device (hereinafter referred to as “this device”) according to an embodiment of the present invention will be described with reference to FIG.
The apparatus S includes a control unit (indicated as “CPU” in FIG. 1) 101, a drive circuit (indicated as “DRV” in FIG. 1) 102, and a position detection circuit (in FIG. 1, “SENS”). (Notation) 103 and the voltage input circuit 104.

The brushless motor 51 in the embodiment of the present invention is a so-called sensorless brushless motor having a known and well-known configuration, for example, for rotationally driving a blower fan (not shown) of a blower in a vehicle air conditioner. It is used. The position detection circuit 103 functions as a conventional sensor for detecting the rotational position of a rotor (not shown), and detects and controls the voltage induced in the stator windings 52a to 52c of the brushless motor 51. The unit 101 is configured to input at an appropriate level.
The control unit 101 uses a microcomputer having a known and well-known configuration, and various programs for controlling the drive of the brushless motor 51 in a storage area or storage element (not shown) in the microcomputer. Are stored, and they are executed as appropriate.

Specifically, the control unit 101 determines a rotor (not shown) position based on a detection signal from the position detection circuit 103, and determines the determined rotor position and a desired rotation speed signal input from the outside. Based on this, a control signal for the drive circuit 102 that outputs a drive pulse signal to the stator windings 52a to 52c of the brushless motor 51 is generated and output. Note that the drive control of the brushless motor 51 via the drive circuit 102 by the control unit 101 is specifically so-called PWM (Pulse Width Modulation) control, and is controlled by the drive circuit 102 according to the desired number of rotations. The duty of the output drive pulse signal is determined, and the drive pulse signal switching timing is controlled according to the detection signal from the position detection circuit 103 to control the energization of the stator windings 52a to 52c. ing.
In addition to the basic drive control of the brushless motor 51, the control unit 101 performs duty correction of the drive pulse signal as described later.

The final stage portion of the drive circuit 102 is a known or well-known switching circuit configured such that the peak value of the drive pulse signal applied to the stator windings 52a to 52 becomes the voltage value of the vehicle battery 1. It is structured.
The voltage of the vehicle battery 1 (hereinafter referred to as “battery voltage”) is read into the control unit 101 via the voltage input circuit 104. That is, the voltage input circuit 104 is for converting the analog voltage into a voltage signal having a level suitable for reading by the control unit 101. More specifically, for example, an analog / digital converter is suitable, but for example, a voltage dividing circuit constituted by a plurality of resistors for converting a battery voltage into an input level suitable for an input of the control unit 101. It may be something like

Next, an outline processing procedure of the drive control process which is a premise of the duty correction process executed by the control unit 101 in the above configuration will be described with reference to FIG.
The brushless motor 51 according to the embodiment of the present invention is PWM-controlled as outlined above, and the drive control process described below is a processing procedure therefor.
When the process is started, the target duty is calculated (see step S100 in FIG. 2). That is, the duty of the PWM drive pulse to be output from the drive circuit 102 is calculated by a predetermined arithmetic expression using the desired rotation speed, the detection signal from the position detection circuit 103, and the like.

Next, although details will be described later, a correction process for the target duty calculated in step S100 is performed (see step S200 in FIG. 2).
Then, the brushless motor 51 is driven through the drive circuit 102 with the corrected duty (see step S300 in FIG. 2).

FIG. 3 is a subroutine flowchart showing a more specific processing procedure of the duty correction processing in step S200 of FIG. 2, and will be described below with reference to FIG.
When the processing is started, it is determined whether or not the target duty calculated in step S100 described in FIG. 2 belongs to a predetermined low region (see step S202 in FIG. 3). When it is determined that the target duty belongs to a predetermined low region (in the case of YES), the correction pattern A is selected as a duty correction pattern for correcting the target duty (step in FIG. 3). (See S204).

Here, the duty correction pattern in the embodiment of the present invention will be described with reference to FIG.
In the embodiment of the present invention, as a duty correction pattern for correcting the target duty to an appropriate value according to the variation of the battery voltage, for example, as shown in FIG. Accordingly, there are three duty correction patterns A, B, and C (in FIG. 4, reference numerals A, B, and C are attached respectively). Here, the correction of the target duty in accordance with the fluctuation of the battery voltage is a case where the battery voltage is changed from the standard value and the motor output when the brushless motor 51 is driven with the target duty at a predetermined standard value. The target duty is corrected so that the motor output at is the same.

  The plurality of duty correction patterns are provided in this way when the target duty is corrected according to the voltage fluctuation of the vehicle battery 1, not only the voltage of the vehicle battery 1 but also the target duty to be corrected. This is due to the fact that a more appropriate correction value can be obtained by considering the size of.

In the embodiment of the present invention, the target duty is used as an index for selecting the three duty correction patterns A, B, and C, and the value is determined in three regions, that is, a low region, a middle region, and a high region. The duty correction pattern is selected depending on which of the areas it belongs to. Note that how to specifically define each of the above-described low region, medium region, and high region that divide the target duty depends on the operating characteristics of the brushless motor 51, the amount of correction required, and the like. However, it is preferable not to be determined uniquely, but to be determined based on data such as simulations and experiments in consideration of the specific conditions as described above.
Further, it is preferable that the duty correction pattern is used by being calculated or mapped and stored in a storage area of the control unit 101 or a storage element (not shown).

Here, it returns to description of FIG. 3 again. When it is determined in the previous step S202 that the target duty does not belong to the predetermined low region (in the case of NO), it is determined whether or not the target duty belongs to the predetermined middle region (step of FIG. 3). (See S206). In step S206, if it is determined that the target duty belongs to the predetermined middle region (in the case of YES), the correction pattern B is selected as the duty correction pattern (see step S208 in FIG. 3). ).
On the other hand, if it is determined in step S206 that the target duty does not belong to the predetermined middle region (in the case of NO), the target duty belongs to the predetermined high region, and the correction pattern C is used as the duty correction pattern. Is selected (see step S210 in FIG. 3).

Next, after any of steps S204, S208, and S210 is executed, the voltage of the vehicle battery 1 is read into the control unit 101 via the voltage input circuit 104 (see step S212 in FIG. 3).
Next, a correction duty that is a correction value of the target duty in the read voltage is determined using the duty correction pattern selected in any of steps S204, S208, and S210 (see step S214 in FIG. 3). It will progress to the process of step S216 to describe.

In step S216, an output duty, which is a duty used for driving the brushless motor 51, is finally obtained.
That is, the output duty is obtained by adding the correction due to the voltage fluctuation of the vehicle battery 1 to the target duty, and is obtained as output duty = target duty ± correction duty. Then, after step S216 is completed, a series of processing is terminated, and the driving of the brushless motor 51 in step S300 described above with reference to FIG. 2 is executed using this output duty.

  In the above-described embodiment, the storage unit is performed by the control unit 101, the correction pattern selection unit is performed by the control unit 101 by executing steps S202 to S210, and the correction value determining unit is performed by the control unit 101 in steps S212 and S214. Thus, the energization control means is realized by the execution of S216 by the control unit 101 and the drive circuit 102, respectively.

In the above-described embodiment, the three correction patterns are used. However, the number of correction patterns is not necessarily limited to three, and more correction patterns are used. By doing so, correction with higher accuracy becomes possible.
Furthermore, in the above-described embodiment, the correction pattern is selected depending on which region the target duty belongs to in advance, but a specific value is used as the reference value of the target duty for selecting the correction pattern. May be. That is, for example, when the target duty is the predetermined value K1%, the correction pattern A is performed, when the target duty is the predetermined value K2%, the correction pattern B is performed, and when the target duty is the predetermined value K3%, the correction pattern C is performed. In cases other than these predetermined target duties, the correction duty may be obtained by so-called interpolation calculation.
Furthermore, although the brushless motor 51 in the above-described embodiment is a sensorless motor, it is needless to say that the brushless motor 51 is not limited to this and may be configured using a sensor.

It is a block diagram which shows the schematic structural example of the drive control apparatus of the brushless motor in embodiment of this invention. 2 is a main flowchart showing a schematic processing procedure of drive control by the drive control device shown in FIG. 1. It is a subroutine flowchart which shows the more specific process sequence of the duty correction process shown by FIG. It is a characteristic diagram which shows the example of a correction pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle battery 51 ... Brushless motor 52a-52c ... Stator winding 101 ... Control part 102 ... Drive circuit 103 ... Position detection circuit 104 ... Voltage input circuit

Claims (9)

A drive control method for a brushless motor that can control the rotational speed of the brushless motor by changing the duty of a drive pulse signal applied to the stator winding of the brushless motor,
A correction pattern is selected from a plurality of correction patterns using the duty of the drive pulse signal calculated by a predetermined arithmetic expression as an index, and the power supply voltage applied to the brushless motor is selected based on the selected correction pattern. A drive control method for a brushless motor, wherein correction for the duty is performed, and a drive pulse signal is applied to the stator winding using the correction result as a duty of the drive pulse signal.   The correction pattern is for correcting the duty according to the fluctuation of the power supply voltage from a predetermined standard value of the power supply voltage so that the motor output at the time of the fluctuation is the same as the motor output at the standard value of the power supply voltage. The brushless motor drive control method according to claim 1, wherein:   The duty correction by the correction pattern is characterized in that the correction value for the power supply voltage obtained from the correction pattern is added to or subtracted from the duty of the drive pulse signal calculated by a predetermined arithmetic expression according to the polarity to obtain an output duty. The brushless motor drive control method according to claim 2. A brushless motor drive control device configured to be able to control the rotational speed of the brushless motor by changing the duty of the drive pulse signal applied to the stator winding of the brushless motor,
Storage means for storing a plurality of correction patterns;
Correction pattern selection means for selecting a correction pattern from among a plurality of correction patterns stored in the storage means, using the duty calculated by a predetermined arithmetic expression as an index;
Correction value determining means for determining a correction value according to the power supply voltage applied to the brushless motor based on the selected correction pattern;
Duty correction means for correcting the duty using the correction value determined by the correction value determination means;
A drive control device for a brushless motor, comprising: an energization control unit that performs energization control on the brushless motor based on a correction result in the duty correction unit.   The correction pattern is for correcting the duty according to the fluctuation of the power supply voltage from a predetermined standard value of the power supply voltage so that the motor output at the time of the fluctuation is the same as the motor output at the standard value of the power supply voltage. The drive control apparatus for a brushless motor according to claim 4, wherein   The correction in the duty correction means is performed by adding or subtracting the correction value for the power supply voltage obtained from the correction pattern to the duty of the drive pulse signal calculated by a predetermined arithmetic expression according to the polarity, to obtain a new duty. The drive control device for a brushless motor according to claim 5. A drive circuit that outputs a drive pulse signal based on a control signal from the outside to the stator winding of the brushless motor to control energization of the stator winding, and controls the duty of the drive pulse signal in the drive circuit, and PWM A brushless motor drive control device comprising a control unit configured to be capable of controlling the rotational speed of the brushless motor by control,
The controller is
Using the duty of the drive pulse calculated by a predetermined arithmetic expression as an index, a correction pattern is selected from a plurality of correction patterns stored in advance, and applied to the brushless motor based on the selected correction pattern A drive control device for a brushless motor, which is configured to correct the duty according to a power supply voltage.   The correction pattern is for correcting the duty according to the fluctuation of the power supply voltage from a predetermined standard value of the power supply voltage so that the motor output at the time of the fluctuation is the same as the motor output at the standard value of the power supply voltage. 8. The brushless motor drive control apparatus according to claim 7, wherein the drive control apparatus is a brushless motor.   The correction of the duty by the correction pattern is performed by adding or subtracting the correction value for the power supply voltage obtained from the correction pattern to the duty of the drive pulse calculated by a predetermined arithmetic expression according to the polarity, to obtain a new duty. The drive control apparatus for a brushless motor according to claim 8.

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