JPH0622583A - Speed control circuit for brushless motor - Google Patents

Abstract

PURPOSE:To maintain a speed of a motor constant by smoothly controlling the speed of the motor. CONSTITUTION:A speed corrector 6 rotates a brushless motor 3 under no load to obtain a correction coefficient at its pole position so that a detected speed becomes constant and stores it. When it controls a speed of the motor 3 under real load, the corrector 6 multiplies a detected speed by the coefficient at its pole position to correct it. A speed controller 7 so applies a voltage command to a driving circuit 8 that the corrected detected speed becomes equal to a speed set by a switch 9. A driving circuit 8 applies a voltage according to a voltage command to the motor 3 to control the speed of the motor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor speed control circuit.

[0002]

2. Description of the Related Art In a conventional brushless motor, the speed is detected by the pulse width of a Hall element as a method of detecting the speed.

[0003]

However, since the relative position of the hall element is different for each brushless motor, the detection speed is not constant even if the brushless motor is rotated at a constant voltage. Therefore, the brushless motor speed control circuit that controls the speed of the brushless motor using this detected speed determines that the motor speed has changed each time the pulse of the Hall element is input, and adjusts the motor speed delicately each time. become.

Therefore, the motor speed cannot be kept constant, which causes vibrations and the like. The present invention has been made in view of the above problems, and an object thereof is to provide a speed control circuit for a brushless motor that can smoothly control the speed of the brushless motor and keep it constant. It is in.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 sequentially sets the stator coils of the brushless motor sequentially according to the outputs from a plurality of magnetic pole detectors for detecting the magnetic pole positions of the rotor of the brushless motor. In a brushless motor speed control circuit that controls the voltage applied to the stator coil based on the detected speed and the speed command obtained from the time when the magnetic pole position is changed by energizing, the magnetic pole position of the rotor and the detected speed at that position are detected by the magnetic pole. Of the rotor of the brushless motor, which is detected when the brushless motor makes one revolution by applying a constant voltage to the stator coil of the brushless motor in the no-load state and rotating the brushless motor. The magnetic pole position is set so that the detected speed becomes constant from the position and the detected speed corresponding to the magnetic pole position. That obtains a correction coefficient, when the speed control brushless motors with actual load, and correcting means for multiplying the correction coefficient at the magnetic pole located at the detection rate in the actual load,
Means for controlling the voltage applied to the stator coil of the brushless motor by using the corrected detection speed.

According to a second aspect of the present invention, the correction means according to the first aspect applies the constant voltage to the stator coil of the brushless motor with no load to rotate the brushless motor, and is detected when the brushless motor makes one revolution. The average of the respective detection speeds at the magnetic pole position of the rotor of the brushless motor is obtained, and the detection speed is multiplied by a correction coefficient so as to be equal to the average speed.

According to a third aspect of the invention, the correction means in the first aspect applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the brushless motor is detected when the brushless motor makes one revolution. An intermediate value of each detected speed at the magnetic pole position of the rotor is obtained, and the detected speed is multiplied by a correction coefficient so as to be equal to the intermediate value.

[0008]

According to the structure of the present invention, the brushless motor is rotated in an unloaded state to detect the magnetic pole position detected when the brushless motor makes one revolution and the detection speed at the magnetic pole position. The correction coefficient at the magnetic pole position is obtained so as to be constant, and when the speed of the brushless motor is controlled by the actual load, the detected speed at the actual load is multiplied by the correction coefficient at the magnetic pole position, and the correction coefficient is obtained. Since the detected speed is used to control the voltage applied to the stator coil of the brushless motor, the motor speed can be smoothly controlled and can be kept constant without speed fluctuation.

According to a second aspect of the present invention, the correction means applies a constant voltage to the stator coil of the brushless motor with no load to rotate the brushless motor, and the magnetic pole of the rotor of the brushless motor detected when the brushless motor makes one revolution. The detection speed is averaged at each position, and a correction coefficient is applied to the detection speed so as to be equal to the average speed. Therefore, the motor speed is smoothly controlled in the same manner as in claim 1,
In addition to being able to keep constant without speed fluctuation, speed control with high accuracy can be performed.

According to a third aspect of the present invention, the correction means applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the brushless motor is rotated once, and each of the magnetic pole positions of the rotor of the brushless motor is detected. Since the intermediate value of the detection speed is calculated and the correction coefficient is applied to the detection speed so that it becomes equal to the intermediate value, noise is added to the detection speed and the detection speed becomes a value that is considerably higher or smaller than the actual detection speed. Even if the value becomes a value, the detection speed including the noise is not used for the correction, and therefore the same speed control as when the correction is performed at the substantially true detection speed can be performed.

[0011]

The present invention will be described below with reference to the drawings. Figure 1
1 shows the configuration of a brushless motor speed control circuit according to an embodiment of the present invention. The load 1 in FIG. 1 is rotationally driven by a brushless motor 3 via a clutch 2. Clutch 2
Connects / disconnects the power of the brushless motor 3 to / from the load 1 by turning on / off the switch 9. The brushless motor 3 is a three-phase four-pole motor and has three Hall elements (not shown) as magnetic pole detectors. These Hall elements are three Hall element signals A, B, and C shown in FIG. Is output. The outputs of these Hall element signals A, B and C are inverted by the Hall element signal converter 4 and become inverted signals as shown in FIG.

The position / velocity detector 5 detects the magnetic pole position and the velocity at the magnetic pole position based on the three Hall element signals A, B, C and their inverted signals A ', B', C '. As shown in FIG. 4, six Hall element detection signals A, B, C, A ', B', C'are created, and speed detection is performed by these Hall element detection signals A, B, C, A ', B ', C'
To detect. That is, as shown in FIG. 5, the time from the fall of the Hall element detection signal to the fall of the next Hall element detection signal is detected, and the detection speed is determined by the time and the distance (pulse width) from the fall to the fall. Are seeking. The distance to the fall is always constant if the position accuracy of the Hall element is good, regardless of the rotation speed. For position detection, Hall element detection signals A, B, C,
Detect using A ', B', C '. That is, as shown in FIG. 6, six Hall element detection signals A, B, C, A ′, B ′,
It is decided by the combination of C'is "H" or "L". The numbers 1 to 6 in FIG. 6 indicate detection positions.

The speed correction unit 6 obtains a speed correction coefficient at the magnetic pole position from the position and the detected magnetic pole position of the speed detection unit 5 and the detected speed at the detected magnetic pole position, and applies the speed correction coefficient to the detected speed. The detected speed is corrected by and the corrected detected speed is output to the speed controller 7. By the way, when a constant voltage is applied to the stator coil of the brushless motor 3 to rotate the stator coil, the rotation speed of the brushless motor 3 becomes a constant speed. However, the actual detection speed detected by the brushless motor 3 varies as shown in FIG. 7 with respect to the ideal detection speed a. The reason is that, as shown in FIG. 8, there is a difference in the distance (pulse width) from the fall of the Hall element detection signals A, B, C, A ′, B ′, C ′ due to the position shift of the Hall element. Therefore, the detection speed is different. Even if the speed is controlled to a constant speed by using the detected speed having such a variation, the brushless motor 3 cannot actually be controlled to the constant speed.

As a method of this correction, the speed correction unit 6 of this embodiment employs a method of using the average value of the detected speeds.
That is, a constant voltage is applied to the stator coil of the brushless motor 3 in the unloaded state by disengaging the clutch 2 to rotate the brushless motor 3, and the average value of the detected speeds at the magnetic pole positions detected when the brushless motor 3 makes one rotation is corrected. The unit 6 calculates, finds and stores the correction coefficient at the magnetic pole position so as to be equal to the average value. Then, when the brushless motor 3 in the actual load state is rotated, the above-described correction coefficient previously obtained as described above from the magnetic pole position detected by the position and velocity detecting unit 5 and the detected velocity of the magnetic pole position from the detected velocity. The correction detection speed is set to the speed control unit 7
Output to.

The speed controller 7 determines whether or not the speed command value sent from the switch 9 and the input correction detected speed are equal, and sends a voltage command to the drive circuit 8 so that they are equal. The drive circuit 8 drives the brushless motor 3 by applying an applied voltage to the stator coil of the brushless motor 3 based on the voltage command sent from the speed control unit 7.

The position / speed detector 5, the speed corrector 6,
The speed control unit 7 is actually composed of a microcomputer. Next, the operation of the brushless motor speed control circuit of the present invention will be described. First, when the commander pushes the start button of the switch 9, the switch 9 disengages the clutch 2 so that the load is not connected to the brushless motor 3, and the switch 9 commands the speed control unit 7 to rotate the brushless motor 3. The speed control unit 7 uses the brushless motor 3
The command voltage is sent to the drive circuit 8 so that the voltage applied to the stator coil gradually increases until it reaches a certain value. The drive circuit 8 applies only the voltage commanded by the speed control unit 7 to the stator coil of the brushless motor 3. The brushless motor 3 is driven in an unloaded state, the rotation speed is gradually increased, and after the applied voltage reaches the above constant value, the brushless motor 3 rotates at a constant speed. The speed control unit 7 confirms that the brushless motor 3 is rotating at a constant voltage, and the speed control unit 7 notifies the switch 9 of this fact. The switch 9 is a speed correction unit 6
Is instructed to obtain the correction coefficient at the detected speed position. The speed correction unit 6 inputs the detected speed as it is to the speed control unit 7 until a command for obtaining the correction coefficient is input from the switch 9. When a command is issued to make a correction, the detected speed at the position corresponding to one rotation of the brushless motor 3 is stored, the average value thereof is taken, and the correction coefficient at the magnetic pole position is stored by the method described above.

Next, when the commander tries to move the load 1 from the switch 9 at a desired rotation speed, first, the clutch 2 is operated through the switch 9, and the brushless motor 3 is operated.
And load 1 are connected. After that, the speed controller 7 is instructed through the switch 9 to control the speed of the brushless motor 3 and to store the speed (set speed) desired by the commander. When the brushless motor 3 rotates with the load 1 connected, the Hall element detection signals A, B, C, A ′,
The position and speed detecting section 5 detects the magnetic pole position and the detected speed by B ′ and C ′. The speed correction unit 6 obtains the corrected detection speed by multiplying the detected speed by a correction coefficient corresponding to the magnetic pole position, and inputs the corrected detection speed to the speed control unit 7.
The speed control unit 7 gives a command voltage to the drive circuit 8 so that the corrected detection speed becomes the same speed as the set speed. Drive circuit 8
Applies the given command voltage to the stator coil of the brushless motor 3 to drive the brushless motor 3. By repeating this, speed control is performed.

In the above embodiment, the average value is used as the correction method, but an intermediate value of the detection speed may be used. That is, the detected speeds at 12 detection positions are stored in the speed correction unit 6, and the correction coefficient at each magnetic pole detection position is obtained so as to match the sixth detected speed from the largest, and speed control is performed. Other than that, the speed is controlled in the same manner as the above embodiment.

[0019]

According to the first aspect of the present invention, the brushless motor is rotated in an unloaded state to detect the magnetic pole position detected when the brushless motor makes one revolution and the detection speed at the magnetic pole position, and the detection is performed. Obtain the correction coefficient at the magnetic pole position so that the speed becomes constant.When controlling the speed of the brushless motor with the actual load, multiply the detected speed under the actual load by the correction coefficient at this magnetic pole position, and then multiply by this correction coefficient. Since the voltage applied to the stator coil of the brushless motor is controlled by using the detected speed thus obtained, the motor speed can be smoothly controlled and kept constant without speed fluctuation.

According to a second aspect of the invention, the correction means applies a constant voltage to the stator coil of the brushless motor with no load to rotate the brushless motor, and the magnetic pole of the rotor of the brushless motor detected when the brushless motor makes one revolution. The detection speed is averaged at each position, and a correction coefficient is applied to the detection speed so as to be equal to the average speed. Therefore, the motor speed is smoothly controlled in the same manner as in claim 1,
In addition to the fact that the speed can be kept constant without fluctuations, the speed can be controlled with high precision.

According to a third aspect of the present invention, the correction means applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the brushless motor is rotated once, and each of the magnetic pole positions of the rotor of the brushless motor is detected. Since the intermediate value of the detection speed is calculated and the correction coefficient is applied to the detection speed so that it becomes equal to the intermediate value, noise is added to the detection speed and the detection speed becomes a value that is considerably higher or smaller than the actual detection speed. Even if the value becomes a value, the detection speed including the noise is not used for correction, and therefore, there is an effect that the same speed control as that at the time of correction at a substantially true detection speed can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a brushless motor speed control circuit according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of the Hall element signal of the above.

FIG. 3 is a waveform diagram of a Hall element inversion signal of the above.

FIG. 4 is a waveform diagram of the Hall element detection signal of the above.

FIG. 5 is a waveform diagram for explaining the speed detection method of the above.

FIG. 6 is a waveform diagram for explaining the position detection method of the above.

FIG. 7 is a waveform diagram for explaining the detection speed at the same constant voltage.

FIG. 8 is a waveform diagram for explaining the difference in detection speed due to the displacement of the position of the Hall element.

[Explanation of symbols]

 1 load 2 clutch 3 brushless motor 4 hall element signal converter 5 position and speed detection unit 6 speed correction unit 7 speed control unit 8 drive circuit 9 switch

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[Procedure amendment]

[Submission date] November 9, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

However, since the relative positions of the Hall elements vary , the detection speed is not constant even if the brushless motor is rotated at a constant voltage.
Therefore, the brushless motor speed control circuit that controls the speed of the brushless motor using this detected speed determines that the motor speed has changed each time the pulse of the Hall element is input, and adjusts the motor speed delicately each time. become.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

According to a third aspect of the present invention, the correction means applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the brushless motor is rotated once, and each of the magnetic pole positions of the rotor of the brushless motor is detected. Since the intermediate value of the detection speed is calculated and the correction coefficient is applied to the detection speed so that it becomes equal to the intermediate value, noise is added to the detection speed and the detection speed becomes a value that is considerably higher or smaller than the actual detection speed. Even if the value becomes a value, the detection speed including the noise is not used for the correction, and therefore the speed can be controlled without being affected by the noise .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The position / velocity detector 5 detects the magnetic pole position and the velocity at the magnetic pole position based on the three Hall element signals A, B, C and their inverted signals A ', B', C '. As shown in FIG. 4, six Hall element detection signals A, B, C, A ', B', C'are created, and speed detection is performed by these Hall element detection signals A, B, C, A ', B ', C'
To detect. That is, as shown in FIG. 5, the time from the fall of the Hall element detection signal to the fall of the next Hall element detection signal is detected, and the detection speed is determined by the time and the distance (pulse width) from the fall to the fall. Are seeking. The distance to the fall is equal if the Hall element position accuracy is good regardless of the rotation speed. For position detection, Hall element detection signals A, B, C, A ', B',
Use C'to detect. That is, as shown in FIG. 6, the six Hall element detection signals A, B, C, A ′, B ′ and C ′ are “H”.
Or "L" combination. The numbers 1 to 6 in FIG. 6 indicate detection positions.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The speed correction unit 6 obtains a speed correction coefficient at the magnetic pole position from the position and the detected magnetic pole position of the speed detection unit 5 and the detected speed at the detected magnetic pole position, and applies the speed correction coefficient to the detected speed. The detected speed is corrected by and the corrected detected speed is output to the speed controller 7. By the way, when a constant voltage is applied to the stator coil of the brushless motor 3 to rotate the stator coil, the rotation speed of the brushless motor 3 becomes a constant speed. However, the actual detection speed detected by the brushless motor 3 varies as shown in FIG. 7 with respect to the ideal detection speed a. The reason is as shown in FIG. 8, the Hall element detects signal A by variations in the position of the Hall element <br/>, B, C, A ' , B',
This is because there is a difference in the distance (pulse width) from the trailing edge of C ′ to the trailing edge, which results in a different detection speed.
Even if the speed is controlled to a constant speed by using the detected speed having such a variation, the brushless motor 3 cannot actually be controlled to the constant speed.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

As a method of this correction, the speed correction unit 6 of this embodiment employs a method of using the average value of the detected speeds.
That is, a constant voltage is applied to the stator coil of the brushless motor 3 in the unloaded state by disengaging the clutch 2 to rotate the brushless motor 3, and the average value of the detected speeds at the magnetic pole positions detected when the brushless motor 3 makes one rotation is corrected. The unit 6 calculates and stores the correction coefficient at the magnetic pole position so that the detected speed becomes equal to the average value. Then, when the brushless motor 3 in the actual load state is rotated, the above-described correction coefficient previously obtained as described above from the magnetic pole position detected by the position and velocity detecting unit 5 and the detected velocity of the magnetic pole position from the detected velocity. The corrected detection speed is output to the speed controller 7.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

The invention according to claim 1 applies a constant voltage to the brushless motor in an unloaded state.
To detect the magnetic pole position detected when the brushless motor makes one revolution and the detected speed at that magnetic pole position, and find the correction coefficient at the magnetic pole position so that the detected speed is constant. When controlling the speed of the motor, the detection speed at the actual load is multiplied by the correction coefficient at this magnetic pole position, and the detection speed obtained by multiplying this correction coefficient is used to control the voltage applied to the stator coil of the brushless motor. Therefore, the motor speed can be smoothly controlled and can be kept constant without speed fluctuation.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

According to a third aspect of the present invention, the correction means applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the brushless motor is rotated once, and each of the magnetic pole positions of the rotor of the brushless motor is detected. Since the intermediate value of the detected speed is calculated and the correction coefficient is applied to the detected speed so that it becomes equal to the intermediate value, the detected speed is higher than the speed actually detected due to noise added to the detected speed.
There even is a small value or become large Kina value, without the use of detection rate including the noise to the correction, there is an effect that it is possible to speed control without affecting its order noise.

Claims (3)

[Claims] 1. A stator coil of a brushless motor is sequentially energized in accordance with outputs from a plurality of magnetic pole detectors for detecting the magnetic pole position of a rotor of a brushless motor, and the detected speed and speed command obtained from the time when the magnetic pole position changes In a brushless motor speed control circuit for controlling the voltage applied to the stator coil, means for detecting the magnetic pole position of the rotor and the detected speed at that position based on the output of the magnetic pole detector, and a stator of the brushless motor in the unloaded state. A constant voltage is applied to the coil to rotate the brushless motor, so that the detection speed becomes constant from the magnetic pole position of the rotor of the brushless motor detected when the brushless motor makes one revolution and the detection speed corresponding to the magnetic pole position. If you calculate the correction coefficient at the magnetic pole position and control the speed of the brushless motor with an actual load, In addition, a correction means for multiplying the detection speed at the actual load by a correction coefficient at the magnetic pole position, and means for controlling the voltage applied to the stator coil of the brushless motor by using the corrected detection speed are provided. Brushless motor speed control circuit. 2. The correction means applies a constant voltage to a stator coil of a brushless motor with no load to rotate the brushless motor, and each of the magnetic pole positions of the rotor of the brushless motor detected when the brushless motor makes one rotation. 2. An average of detection speeds is obtained, and a correction coefficient is applied to the detection speeds so as to be equal to the average speeds.
The brushless motor speed control circuit described. 3. The correction means applies a constant voltage to the brushless motor with no load to rotate the brushless motor, and the detected speed at each magnetic pole position of the rotor of the brushless motor detected when the brushless motor makes one rotation. 2. The brushless motor speed control circuit according to claim 1, wherein an intermediate value is obtained and the detected speed is multiplied by a correction coefficient so as to be equal to the intermediate value.