JP2016201912A - Motor drive device and control method for motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive device and a control method for motor drive device, capable of suppressing increase of processing load at calculation for rotor position estimation, and suppressing increase of processing load at high revolution.SOLUTION: In a motor drive device, a brushless motor 11 has a three-phase motor structure, a Hall sensor 12 detects a signal of flux change at an operation of the brushless motor 11, a control part 13 obtains rotor revolution of the brushless motor 11 based on the signal of flux change, calculates a plurality of predetermined electric angles according to the change of rotor revolution, selects one predetermined electric angle within the plurality of the predetermined electric angles, causes a gate driver 14 to output a PWM signal for switching energization timing for each phase of the brushless motor 11 with the selected predetermined electric angle, and the inverter 15 supplies a voltage to a stator coil of the brushless motor 11 by sinusoidally changing the voltage, based on the PWM signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor drive device and a method for controlling the motor drive device.

  The sine wave drive that changes the stator coil voltage of the motor into a sine wave has lower noise and vibration than the rectangular wave drive that changes into a square wave. In order to perform sine wave drive, an expensive absolute angle sensor (such as a resolver) is required. When an absolute angle sensor is not used, for example, when a hall sensor is used, the rotor sensor is energized by estimating the rotor position every time the hall sensor output interval elapses (the time corresponding to the sampling timing for reading the resolver output value). By switching the timing, sine wave drive can be performed with reduced accuracy.

Japanese Patent Laid-Open No. 9-121583

However, in this case, there is a problem that the calculation for estimating the rotor position from the set time becomes complicated and the processing load increases. In addition, there is a problem that a calculation error of the rotor position estimation becomes large. In addition, in order to reduce the error, there is a problem that the memory capacity to be used increases if high resolution map data (SIN, COS, etc.) is held.
In addition, when the energization timing is switched by estimating the rotor position, there is a problem that the energization timing switching time interval becomes shorter as the rotor speed increases (the higher the rotation speed), and the processing load at high rotation increases. It was.

  The present invention has been made in consideration of the above circumstances, and a motor drive device and a motor drive device control method capable of suppressing an increase in processing load in calculation for estimating the rotor position and an increase in processing load at high rotation The purpose is to provide.

  In order to solve the above-described problem, a motor driving device according to an embodiment is a motor driving device including a brushless motor, a hall sensor, a control unit, a gate driver, and an inverter, and the brushless motor is a three-phase motor. A motor structure, wherein the Hall sensor detects a magnetic flux change signal during operation of the brushless motor, and the control unit obtains a rotor rotational speed of the brushless motor based on the magnetic flux change signal, A plurality of predetermined electrical angles are calculated according to a change in the rotor rotational speed, one predetermined electrical angle is selected from the plurality of predetermined electrical angles, and each of the brushless motors is selected with the selected predetermined electrical angle. The gate driver outputs a PWM signal for switching the energization timing to the phase, and the inverter is configured to generate the brushless signal based on the PWM signal. The voltage supply to the over data of the stator coil, and supplies varied sinusoidally, characterized in that.

  In the motor drive device according to the embodiment, the plurality of predetermined electrical angles are two, that is, a first predetermined electrical angle and a second predetermined electrical angle, and the electrical interval is an edge interval time of the Hall sensor. There are two predetermined numbers for dividing the rotation time of 60 degrees in angle, the first predetermined number and the second predetermined number, and the second predetermined number is smaller than the first predetermined number. When the rotor rotational speed is less than a preset rotor rotational speed, the control unit sets the first predetermined electrical angle, the electrical angle 60 degrees rotation time, and the first predetermined electrical speed. The rotor signal is calculated by dividing the PWM signal every time the first predetermined electrical angle elapses from the electrical angle 60 degree rotation time, and the rotor rotational speed is set in advance. If it is above, the second predetermined electrical angle is rotated by 60 electrical degrees. And the PWM signal is changed each time the second predetermined electrical angle elapses from the rotation time of the electrical angle of 60 degrees. .

  In the motor drive device according to the embodiment, the control unit includes a table that stores trigonometric function values used for generating the PWM signal.

  Further, the control method of the motor drive device of the embodiment is a control method of a motor drive device including a brushless motor having a three-phase motor structure, a hall sensor, a control unit, a gate driver, and an inverter, The hall sensor detects a magnetic flux change signal during operation of the brushless motor, and the control unit obtains the rotor rotational speed of the brushless motor based on the magnetic flux change signal, and the rotor rotational speed. A plurality of predetermined electrical angles are calculated in response to a change in a plurality of predetermined electrical angles, a predetermined electrical angle is selected from the plurality of predetermined electrical angles, and each phase of the brushless motor is selected at the selected predetermined electrical angle. An output step for causing the gate driver to output a PWM signal for switching energization timing, and the inverter is configured to output the brush signal based on the PWM signal. The voltage supply to the motor stator coils, characterized in that it comprises a supply step of supplying varied sinusoidally.

  According to the present invention, the control unit calculates the rotor rotation speed based on the magnetic flux change signal, calculates a plurality of predetermined electrical angles according to the change in the rotor rotation speed, and outputs the plurality of predetermined electrical angles. One predetermined electrical angle is selected, and a PWM signal for switching the energization timing to each phase of the brushless motor is output to the gate driver at the selected predetermined electrical angle. The inverter supplies the voltage supplied to the stator coil of the brushless motor in a sine wave shape based on the PWM signal. As a result, it is possible to provide a motor drive device and a control method for the motor drive device that can suppress an increase in processing load in calculation for estimating the rotor position and an increase in processing load during high rotation.

1 is a diagram illustrating a configuration of a motor driving device 1. FIG. 3 is a flowchart in the operation of the motor drive device 1. 3 is a timing chart showing the operation of the motor drive device 1. 3 is a timing chart showing the operation of the motor drive device 1.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of the motor driving device 1. The motor drive device 1 shown in FIG. 1 includes a brushless motor 11, a hall sensor 12, a control unit 13, a gate driver 14, an inverter 15, and a DC power supply 16.

The brushless motor 11 is a motor having a three-phase motor structure. The brushless motor 11 includes a stator around which a U-phase stator coil, a V-phase stator coil, and a W-phase stator coil, which are three-phase armature windings, and a permanent magnet rotor having a plurality of magnetic poles.
In addition, a hall sensor 12 is attached to the brushless motor 11 in the vicinity of the permanent magnet rotor. The hall sensor 12 includes three U-phase hall sensors, a V-phase hall sensor, and a W-phase hall sensor that detect a magnetic flux change signal during operation of the brushless motor. The U-phase Hall sensor detects switching of the magnetic poles of the permanent magnet rotor, and outputs a U-phase Hall sensor signal, which is a binary signal of high (H) or low (L), to the control unit 13 as a result of the detection. The V-phase Hall sensor detects the switching of the magnetic poles of the permanent magnet rotor, and outputs the detected result to the control unit 13 as a V-phase Hall sensor signal that is a binary signal of H or L. The W-phase hall sensor detects the switching of the magnetic poles of the permanent magnet rotor, and outputs the detected result to the control unit 13 as a W-phase hall sensor signal that is a binary signal of H or L.

The control unit 13 obtains the rotor rotational speed of the brushless motor 11 based on the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal, and performs a plurality of predetermined electrical operations according to the change in the rotor rotational speed. An angle is calculated, one predetermined electrical angle is selected from the plurality of predetermined electrical angles, and a PWM signal for switching the energization timing to each phase of the brushless motor 11 at the selected predetermined electrical angle is sent to the gate driver 14 Output.
The inverter 15 supplies the voltage supplied to the stator coil of the brushless motor 11 in a sine wave shape based on the PWM signal.
The DC power supply 16 supplies a DC voltage for the inverter 15 to supply a voltage to the stator coil of the brushless motor 11.

Here, energization timing will be described. Conventionally, for example, in the case of a 6-pole 9-slot three-phase brushless motor, when the 180-degree sine wave drive is performed, the energization timing T is fixed, and thus the electrical angle θ has to be calculated therefrom. The energization timing T is obtained by the equation T = electrical angle 60 degree rotation time ÷ 60 × electrical angle θ. Here, the electrical angle 60 degree rotation time is, for example, the time between the time when the U-phase Hall sensor signal changes from L to H and the time when the W-phase Hall sensor changes from H to L. For example, when the electrical angle 60 ° rotation time is 1.11 ms, the rotor rotation speed is found to be 3000 rpm. Therefore, if the electrical angle of 60 ° rotation time = 1.11 ms and T = 0.1 ms are substituted into the above formula, the electrical angle θ when the rotor rotational speed is 3000 rpm is 5.4 °. In addition, when the electrical angle 60 ° rotation time is 3.33 ms, the rotation speed of the rotor is found to be 1000 rpm. Therefore, if the electrical angle of 60 ° rotation time = 3.33 ms and T = 0.1 ms are substituted into the above equation, the electrical angle θ when the rotor rotation speed is 1000 rpm is 1.8 °. Thus, if the energization timing T is fixed, the electrical angle θ must be calculated from the energization timing T according to the rotational speed of the rotor. For this reason, conventionally, there has been a problem that the calculation for estimating the rotor position (electrical angle θ) from the energization timing T becomes complicated and the processing load in the calculation for estimating the rotor position increases.
Also, if sin and cos map data is held at a resolution of 1 degree, 360 data of 0 to 359 degrees is required at the minimum, and calculation errors of 0.4 degrees and 0.2 degrees occur. For example, if the resolution is set to 0.1 degree, 3600 pieces of data that is ten times larger are required.

Therefore, in the present embodiment, the energization timing T is not a fixed timing as in the prior art, but a plurality of predetermined electrical angles obtained by dividing the electrical angle 60 ° rotation time by a predetermined number are calculated, and a plurality of predetermined electrical angles are calculated. One predetermined electrical angle is selected from the electrical angles, and the selected predetermined electrical angle is changed. That is, if the electrical angle θ is fixed to a predetermined electrical angle (the first predetermined electrical angle and the second predetermined electrical angle), the energization timing T can be determined according to the rotational speed of the rotor.
For example, when the electrical angle 60 degree rotation time is 3.33 ms, the number of rotations of the rotor is obtained as 1000 rpm from the Hall sensor signal. At this time, in order to set the energization timing to 0.555 ms, the first predetermined electrical angle (θ = 10 degrees) may be obtained by dividing the 60-degree electrical angle rotation time by the first predetermined number. Further, when the electrical angle 60 ° rotation time is 1.11 ms, the rotation speed of the rotor is determined to be 3000 rpm from the Hall sensor signal. At this time, in order to set the energization timing to 0.222 ms, the electrical angle 60 degree rotation time may be divided by the second predetermined number 5 to obtain the second predetermined electrical angle (θ = 12 degrees).
As described above, in the present embodiment, the energization timing T is calculated as a plurality of predetermined electrical angles obtained by dividing the electrical angle 60 degree rotation time by a predetermined number, and one predetermined predetermined angle is calculated from the plurality of predetermined electrical angles. An electrical angle is selected, and the selected predetermined electrical angle is changed.

Here, there are a plurality of predetermined electrical angles because the predetermined electrical angle (second predetermined electrical angle) at the time of high rotation of the rotor is changed to the predetermined electrical angle (first predetermined electrical angle) at the time of low rotation. The reason is to suppress the increase in the processing load at the time of high rotation.
For this reason, the control part 13 calculates | requires the rotor rotational speed of the brushless motor 11 based on a U-phase Hall sensor signal, a V-phase Hall sensor signal, and a W-phase Hall sensor signal, and according to the change of a rotor rotational speed, several A gate signal is generated by calculating a predetermined electrical angle, selecting one predetermined electrical angle from a plurality of predetermined electrical angles, and switching the energization timing to each phase of the brushless motor 11 at the selected predetermined electrical angle. 14 to output. Whether the controller 13 selects a predetermined electrical angle from among a plurality of predetermined electrical angles is whether the calculated rotor rotational speed is less than a preset rotor rotational speed (eg, 3000 rpm). It is determined by judging. That is, when the rotor rotational speed is less than the preset rotor rotational speed, the control unit 13 sets the first predetermined electrical angle among the predetermined electrical angles, the electrical angle 60 degrees rotation time, and the first predetermined electrical angle. The PWM signal is changed every time the first predetermined electrical angle elapses from the electrical angle 60-degree rotation time. On the other hand, when the rotor rotational speed is equal to or higher than the rotor rotational speed set in advance, the control unit 13 sets the second predetermined electrical angle among the predetermined electrical angles, sets the electrical angle 60 degrees rotation time to the second predetermined speed. The PWM signal is changed every time the second predetermined electrical angle elapses from the electrical angle 60 degree rotation time.
Therefore, there are two predetermined electrical angles, ie, a first predetermined electrical angle and a second predetermined electrical angle. Further, there are two predetermined numbers for dividing the rotation time of the electrical angle of 60 degrees that is the edge interval time of the Hall sensor, the first predetermined number and the second predetermined number, and the second predetermined number is The value is smaller than the first predetermined number. In the present embodiment, two predetermined electrical angles are described as an example of a plurality of predetermined electrical angles, but there may be three or more predetermined electrical angles.

Hereinafter, first, the controller 13 determines how the predetermined electrical angles (the first predetermined electrical angle and the second predetermined electrical angle) are determined, and every time the predetermined electrical angle elapses from the electrical angle 60 degree rotation time. Whether the PWM signal is changed will be described with reference to FIG. FIG. 2 is a flowchart in the operation of the motor drive device 1.
The controller 13 determines the level of the hall sensor signal (U-phase hall sensor signal, V-phase hall sensor signal, W-phase hall sensor signal) (step ST1).
The control unit 13 determines magnetic pole position = 0, magnetic pole position = 60, magnetic pole position = 120, magnetic pole position = 180, magnetic pole position = 240, and magnetic pole position = 300 from the level of the Hall sensor signal.
The magnetic pole position = 0 means that the electrical angle θ is in the range of 0 to 60 degrees.
The control unit 13 determines that the magnetic pole position = 0 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are H, L, and H, respectively.
The magnetic pole position = 60 means that the electrical angle θ is in the range of 60 degrees to 120 degrees.
The control unit 13 determines that the magnetic pole position is 60 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are H, L, and L, respectively.
The magnetic pole position = 120 means that the electrical angle θ is in the range of 120 degrees to 180 degrees.
The control unit 13 determines that the magnetic pole position is 120 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are H, H, and L, respectively.
The magnetic pole position = 180 is an electric angle θ in a range of 180 degrees to 240 degrees.
The control unit 13 determines that the magnetic pole position is 180 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are L, H, and L, respectively.
The magnetic pole position = 240 means that the electrical angle θ is in the range of 240 degrees to 300 degrees.
The control unit 13 determines that the magnetic pole position is 240 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are L, H, and H, respectively.
The magnetic pole position = 300 is an electric angle θ in the range of 300 degrees to 360 degrees.
The controller 13 determines that the magnetic pole position is 300 when the U-phase Hall sensor signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal are L, L, and H, respectively.

The controller 13 acquires the sensor edge interval time (step ST2).
When magnetic pole position = 0, the control unit 13 acquires the sensor edge interval time (electrical angle 60 ° rotation time) from the hall sensor signals (U-phase hall sensor signal, V-phase hall sensor signal, and W-phase hall sensor signal). To do.
The control unit 13 acquires the sensor edge interval time at the magnetic pole position = 0 from the time between the time when the U-phase hall sensor signal changes from L to H and the time when the W-phase hall sensor changes from H to L. .
The control unit 13 acquires the sensor edge interval time at the magnetic pole position = 60 from the time between the time when the W-phase hall sensor signal changes from H to L and the time when the V-phase hall sensor changes from L to H. .
The control unit 13 acquires the sensor edge interval time at the magnetic pole position = 120 from the time between the time when the V-phase hall sensor signal changes from L to H and the time when the U-phase hall sensor changes from H to L. .
The control unit 13 acquires the sensor edge interval time at the magnetic pole position = 180 from the time between the time when the U-phase hall sensor signal changes from H to L and the time when the W-phase hall sensor changes from L to H. .
The control unit 13 acquires the sensor edge interval time at the magnetic pole position = 240 from the time between the time when the W-phase hall sensor signal changes from L to H and the time when the V-phase hall sensor changes from H to L. .
The control unit 13 acquires the sensor edge interval time at magnetic pole position = 300 from the time between the time when the V-phase hall sensor signal changes from H to L and the time when the U-phase hall sensor changes from L to H. .

The controller 13 calculates the electrical angle X degree rotation time based on the sensor edge interval time (step ST3). Here, when the controller 13 calculates the electrical angle X degrees rotation time (predetermined electrical angle), the sensor edge interval time (electrical angle 60 degrees rotation time) is, for example, a divisor of 60 (predetermined number). The electrical angle X degree rotation time is calculated by dividing by.
The controller 13 estimates and corrects the Hall sensor signal interval (electrical angle X degree rotation time) from the previous electric angle 60 degree rotation time. In addition, in order to correct the mounting variation of the Hall sensor 12, it is preferable to correct by estimating from the moving average result of the electrical angle X degree rotation time.

The control unit 13 starts the operation of the energization switching timer, and performs an interrupt process every time the electrical angle X degrees rotation time has elapsed (step ST4). At this time, the control unit 13 updates the timer with the time calculated by the latest sensor edge interval time.
The control unit 13 determines the first electrical angle X at the next magnetic pole position (i + 1) × 60 after the magnetic pole position i × 60 (i = 0, 1, 2, 3, 4, 5) determined in step ST1. The operation of the energization switching timer is started in the degree rotation time.
The control unit 13 performs dq three-phase conversion (PWM duty calculation) (step ST5).
For this calculation, an electrical angle θ = (i + 1) × 60 degrees is used for calculation based on the magnetic pole position of the Hall sensor 12.
The controller 13 outputs the PWM duty (step ST6). The control unit 13 outputs the calculated PWM duty (PWM command signal) to the gate driver 14 and causes the gate driver 14 to output a PWM signal.
The controller 13 starts the operation of the energization switching timer during the j (j = 2 to 60 / X) th electrical angle X degree rotation time at the magnetic pole position (i + 1) (step ST4).
The controller 13 performs a process of adding the magnetic pole position by X degrees (step ST7).
This is because it is estimated that the electrical angle has been rotated by X degrees in order to generate an interrupt every electrical angle X degrees rotation time.
The controller 13 performs dq three-phase conversion (PWM duty calculation) (step ST8).
Since this calculation is based on the magnetic pole position of the Hall sensor 12, an electrical angle θ = (i + 1) × 60 + (j−1) × X degrees is used.
The control unit 13 outputs the PWM duty (step ST9). The control unit 13 outputs the calculated PWM duty to the gate driver 14 and causes the gate driver 14 to output a PWM signal.
In this way, after the magnetic pole position detection at the magnetic pole position (i + 1) is completed, the control unit 13 returns to step 2 and shifts to the magnetic pole position detection at the magnetic pole position (i + 2). That is, the control unit 13 updates the magnetic pole position recognition when the hall sensor 12 is switched. At this time, the absolute position (electrical angle θ) is updated even when the rotor is accelerated or decelerated.

Here, the dq three-phase conversion (PWM duty calculation) performed by the control unit 13 will be described.
The inverter 15 supplies the voltage supplied to the stator coil of the brushless motor 11 in a sine wave shape based on the PWM signal. Therefore, the control unit 13 determines the PWM duty (PWM command signal) so that the voltages (U-phase voltage, V-phase voltage, W-phase voltage) that the inverter 15 supplies to the stator coil are expressed by the following equations. Perform the calculation.
Vu = (√2 / 3) × (Vd × cos θ−Vq × sin θ)
Vv = (√2 / 3) × {Vd × cos (θ-2π / 3) −Vq × sin (θ-2π / 3)}
Vw = −Vu−Vv
Vd and Vq are command voltages input from the outside of the control unit 13, Vd indicates a d-axis voltage, and Vq indicates a q-axis voltage.
The PWM duty (duty) is a ratio of the level of each Vu, Vv, Vw to the voltage level of the DC power supply 16, for example, 12V. Therefore, the control unit 13 calculates the duty (ratio of the time during which the PWM command signal is H with respect to the electrical angle X degree rotation time) based on the above formula, and the PWM command signal 6 which is a digital signal having this duty. The book is output to the gate driver 14.
When driving the upper FET constituting the inverter 15, the gate driver 14 boosts the level of three PWM command signals that are digital signals to generate a PWM signal, and drives the gate of the FET. Further, when driving the lower FET constituting the inverter 15, the gate driver 14 generates a PWM signal with the level of three PWM command signals that are digital signals, and drives the gate of the FET.
Thereby, the control part 13 makes the gate driver 14 output the PWM signal which switches the energization timing to each phase of the brushless motor 11 by electrical angle X degree rotation time. The inverter 15 supplies the voltage supplied to the stator coil of the brushless motor 11 in a sine wave shape based on the PWM signal.

In the present embodiment, the command voltage input from the outside of the control unit 13 is the q-axis voltage Vq, and the d-axis voltage Vd is always 0. In addition, what is necessary is just to implement using a Hall sensor signal when performing advance angle control.
That is, the voltages (U-phase voltage, V-phase voltage, and W-phase voltage) that the inverter 15 supplies to the stator coil are expressed by the following equations.
Vu = (√2 / 3) × (−Vq × sin θ)
Vv = (√2 / 3) × {−Vq × sin (θ−2π / 3)}
Vw = −Vu−Vv
Thus, the table for storing the trigonometric function values used by the control unit 13 for generating the PWM signal is (360 degrees / electrical angle X degrees) = (60 degrees / predetermined number) × 6 sin θ as map data. You may memorize it beforehand. In this way, a calculation error as in the prior art does not occur, and an increase in memory capacity to be used can be suppressed.
Further, by performing the processing shown in FIG. 2 for electrical angles of 0 degrees to 360 degrees, that is, by performing the energization timing at a predetermined electrical angle divided into (360 degrees / electrical angle X) times, the brushless motor 11 It becomes possible to change the stator coil voltage in a sine wave shape. That is, according to the motor drive device 1, the rotor position can be accurately estimated using the Hall sensor 12 that is less expensive than the resolver and the control unit 13 that has a simple circuit configuration, and the stator coil voltage of the brushless motor 11 can be estimated. The motor can be driven appropriately by changing the sine wave shape.

FIG. 3 is a timing chart showing the operation of the motor drive device 1.
In FIG. 3, when the electrical angle X degrees rotation time is set to the electrical angle 10 degrees rotation time (first predetermined angle), the U phase voltage, the V phase voltage, the W phase voltage level changes, and the U phase Hall sensor The level change of the signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal is shown with the electrical angle θ as the horizontal axis.
In the electrical angle θ = 0 ° to 360 °, a dashed line is drawn in the vertical direction every 60 °. Between each of these dashed-dotted lines, the sensor edge interval (electrical angle 60 degree rotation time) is shown.
In the case of FIG. 3, the rotational speed of the rotor calculated based on the electrical angle of 60 ° rotation time of 3.33 ms is 1000 rpm, and of these, the electrical angle of θ = 0 ° to 60 ° indicates the electrical angle of 60 ° rotation time. Is divided by 6 (the first predetermined number), T1 = 0.555 ms is the electrical angle 10 ° rotation time indicated by the electrical angle θ = 60 degrees to 120 degrees. The dq three-phase transformation is performed six times for every rotation time of electrical angle 10 degrees indicated by electrical angle θ = 60 degrees to 120 degrees. Thereby, the level change of each of the U-phase voltage, the V-phase voltage, and the W-phase voltage in the electrical angle θ = 60 degrees to 120 degrees is obtained. The dq three-phase conversion is performed 36 times, whereby the stator coil voltage of the brushless motor 11 is changed in a sine wave shape.

FIG. 4 is a timing chart showing the operation of the motor drive device 1.
In FIG. 4, when the electrical angle X degrees rotation time is set to the electrical angle 12 degrees rotation time (second predetermined angle), the level change of each of the U phase voltage, V phase voltage, and W phase voltage, U phase Hall sensor The level change of the signal, the V-phase Hall sensor signal, and the W-phase Hall sensor signal is shown with the electrical angle θ as the horizontal axis.
In the electrical angle θ = 0 ° to 360 °, a dashed line is drawn in the vertical direction every 60 °. Between each of these dashed-dotted lines, the sensor edge interval (electrical angle 60 degree rotation time) is shown.
In the case of FIG. 4, the rotational speed of the rotor calculated based on the electrical angle of 60 ° rotation time of 1.11 ms is 3000 rpm, and of these, the electrical angle of θ = 0 ° to 60 ° indicates the electrical angle of 60 ° rotation time. T2 = 0.222 ms, which is a value obtained by dividing by 5 (second predetermined number), is an electrical angle 12 degree rotation time indicated by an electrical angle θ = 60 degrees to 120 degrees. The dq three-phase conversion is performed five times for every 12 electrical degrees rotation time indicated by electrical angle θ = 60 degrees to 120 degrees. Thereby, the level change of each of the U-phase voltage, the V-phase voltage, and the W-phase voltage in the electrical angle θ = 60 degrees to 120 degrees is obtained. By performing this dq three-phase conversion 30 times, the stator coil voltage of the brushless motor 11 is changed into a sine wave.

As shown in FIGS. 3 and 4, the electrical angle 60 ° rotation time is 1.11 ms when the rotor rotation speed is 3000 rpm, and 3.33 ms when the rotor rotation speed is 1000 rpm.
Here, the electrical angle 10 degrees rotation time (first predetermined angle) when the energization timing is switched at an electrical angle of 10 degrees is T1, and the electrical angle 12 degrees rotation time when the energization timing is switched at an electrical angle of 12 degrees. Is T2 (second predetermined angle), when the rotor rotational speed is 3000 rpm, T1 = 0.185 ms, T2 = 0.222 ms (see FIG. 4), and when the rotor rotational speed is 1000 rpm, T1 = 0. 555 ms (see FIG. 3), T2 = 0.666 ms.
If the energization timing is switched every 10 degrees at 3000 rpm, T1 = 0.185 ms, and the processing load becomes larger than at 1000 rpm.
Therefore, at 3000 rpm, the processing load can be reduced by switching the energization every 12 degrees of electrical angle and setting T2 = 0.222 ms.
Further, when switching the energization at an electrical angle of 12 degrees at 1000 rpm, T2 = 0.666 ms, the resolution is lowered, and the controllability may be lowered.
Therefore, at 1000 rpm, the energization is switched every 10 degrees of electrical angle and T1 = 0.555 ms, so that the controllability in the low rotation range can be prevented.
As described above, the control unit 13 calculates a plurality of predetermined electrical angles according to the change in the rotor rotational speed, selects one predetermined electrical angle from the plurality of predetermined electrical angles, and selects the selected predetermined angle. The gate driver is made to output the PWM signal which switches the energization timing to each phase of a brushless motor with an electrical angle. Which one of the plurality of predetermined electrical angles is selected is determined by determining whether or not the calculated rotor rotational speed is less than a preset rotor rotational speed (3000 rpm in the above description). Is determined by That is, when the rotor rotational speed is less than the preset rotor rotational speed, the controller 13 sets 10 degrees (first predetermined electrical angle) out of the predetermined electrical angles, and sets the electrical angle 60 degrees rotation time to 6 degrees. Calculated by dividing by (first predetermined number). On the other hand, when the rotor rotational speed is equal to or higher than the preset rotor rotational speed, the control unit 13 sets 12 degrees (second predetermined electrical angle) out of the predetermined electrical angles and sets the electrical angle 60 degrees rotation time to 5 degrees. Calculated by dividing by (second predetermined number). Therefore, by using the first predetermined electrical angle at the time of low rotation and using the second predetermined electrical angle at the time of high rotation, the processing load in the high rotation range is reduced without degrading the controllability in the low rotation range. It can be reduced.

  As described above, according to the embodiment of the present invention, the control unit 13 obtains the rotor rotational speed based on the magnetic flux change signal, and according to the change in the rotor rotational speed, the electrical angle 10 degrees rotation time and the electrical angle. 12 degrees rotation time (a plurality of predetermined electrical angles) is calculated, one predetermined electrical angle is selected from the plurality of predetermined electrical angles, and the electrical angle is 12 degrees rotation time (the selected predetermined electrical angle). The gate driver 14 is made to output the PWM signal which switches the energization timing to each phase of the motor 11. The inverter 15 supplies the voltage supplied to the stator coil of the brushless motor 11 in a sine wave shape based on the PWM signal. As a result, it is possible to provide a motor driving device 1 and a method for controlling the motor driving device 1 that can suppress an increase in the processing load in the calculation for estimating the rotor position and an increase in the processing load at the time of high rotation.

  As mentioned above, although embodiment of this invention was described, the motor drive device of this invention is not limited only to the above-mentioned example of illustration, A various change can be added in the range which does not deviate from the summary of this invention. Of course.

DESCRIPTION OF SYMBOLS 1 Motor drive device 11 Brushless motor 12 Hall sensor 13 Control part 14 Gate driver 15 Inverter 16 DC power supply

Claims (4)

A motor drive device comprising a brushless motor, a hall sensor, a control unit, a gate driver, and an inverter,
The brushless motor has a three-phase motor structure,
The Hall sensor detects a magnetic flux change signal during operation of the brushless motor,
The control unit obtains the rotor rotational speed of the brushless motor based on the magnetic flux change signal, calculates a plurality of predetermined electrical angles according to the change in the rotor rotational speed, and the plurality of predetermined electrical angles. Selecting one predetermined electrical angle from, causing the gate driver to output a PWM signal for switching the energization timing to each phase of the brushless motor at the selected predetermined electrical angle,
Based on the PWM signal, the inverter supplies a voltage supply to the stator coil of the brushless motor in a sine wave form.
The motor drive device characterized by the above-mentioned. There are two of the plurality of predetermined electrical angles, a first predetermined electrical angle and a second predetermined electrical angle,
There are two predetermined numbers for dividing the electrical angle 60 degree rotation time which is the edge interval time of the Hall sensor, a first predetermined number and a second predetermined number,
The second predetermined number is smaller than the first predetermined number;
The controller is
When the rotor rotational speed is less than a preset rotor rotational speed, the first predetermined electrical angle is calculated by dividing the electrical angle 60 degree rotation time by the first predetermined number; The PWM signal is changed every time the first predetermined electrical angle elapses from the electrical angle rotation time of 60 degrees,
When the rotor rotational speed is equal to or higher than a preset rotor rotational speed, the second predetermined electrical angle is calculated by dividing the electrical angle 60 degree rotation time by the second predetermined number; The PWM signal is changed every time the second predetermined electrical angle elapses from the electrical angle rotation time of 60 degrees.
The motor driving apparatus according to claim 1. The control unit includes a table that stores trigonometric function values used for generating the PWM signal.
The motor drive device according to claim 1 or 2, wherein the motor drive device is provided. A control method of a motor drive device comprising a brushless motor having a three-phase motor structure, a hall sensor, a control unit, a gate driver, and an inverter,
The hall sensor detects a magnetic flux change signal during operation of the brushless motor; and
The control unit obtains the rotor rotational speed of the brushless motor based on the magnetic flux change signal, calculates a plurality of predetermined electrical angles according to the change in the rotor rotational speed, and the plurality of predetermined electrical angles. An output step of outputting a PWM signal for switching the energization timing to each phase of the brushless motor at the selected predetermined electrical angle from the gate driver;
A supply step in which the inverter supplies the voltage supply to the stator coil of the brushless motor in a sine wave form based on the PWM signal; and
A method for controlling a motor drive device comprising:

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