CN111030518A

CN111030518A - Motor drive control device, motor, and blower

Info

Publication number: CN111030518A
Application number: CN201910933337.0A
Authority: CN
Inventors: 原八十八; 望月亮吾
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2018-10-05
Filing date: 2019-09-27
Publication date: 2020-04-17
Also published as: JP2020061815A

Abstract

The invention provides a motor drive control device, a motor and an air supply device. The motor drive control device includes: a drive control unit that switches an energization mode for a phase winding of a motor unit to which an alternating-current voltage is applied in a predetermined order, generates a rotating magnetic field, and controls the motor unit; a voltage detection unit that detects a voltage of the phase winding; and a position information generating unit that generates rotational direction position information of a rotational direction of the rotor of the motor unit based on a detection result of the voltage detecting unit. The drive control unit generates the rotating magnetic field and performs forced rectification for forcibly rotating and driving the rotor during a start-up operation of the motor unit, and when the rotational direction position information is out of synchronization with the rotation of the rotating magnetic field, generates the rotating magnetic field having a different start phase and repeats the performing of the forced rectification.

Description

Motor drive control device, motor, and blower

Technical Field

The invention relates to a motor drive control device, a motor and a blower.

Background

A conventional motor is disclosed in Japanese patent laid-open publication No. Hei 4-304190. The motor is of a sensorless control system, and includes a CPU, a current control circuit, a rotor position detection unit, a rotor, and a motor coil. The current control circuit applies a current to the motor coil according to a current control signal output from the CPU and generates a rotating magnetic field. Thus, the rotor is rotationally driven. The rotor position detection unit detects a rotational position of the rotor based on an induced voltage generated in the motor coil.

When the motor is started, the motor coil is excited, and the rotor is forcibly started. At this time, when the rotor position detecting unit does not detect the rotation of the rotor, the rotor position detecting unit increases the starting current to re-excite the motor coil and repeats the starting process of the rotor.

However, according to the motor disclosed in Japanese patent application laid-open No. Hei 4-304190, there is a problem that the starting current increases to increase the power consumption during the starting operation.

Disclosure of Invention

The invention aims to provide a motor drive control device capable of reducing power consumption during starting operation, and a motor and an air supply device using the same.

The motor drive control device according to the exemplary embodiment of the present invention includes: a drive control unit that switches an energization pattern of a phase winding of a motor unit to which an alternating-current voltage is applied in a predetermined order and generates a rotating magnetic field; a voltage detection unit that detects a voltage of the phase winding; and a position information generating unit that generates rotational direction position information in a rotational direction of a rotor of the motor unit based on a detection result of the voltage detecting unit, wherein the drive control unit generates the rotational magnetic field and performs forced rectification for forcibly rotationally driving the rotor during a start-up operation of the motor unit, and generates the rotational magnetic field having a different start phase and repeats the execution of the forced rectification when the rotational direction position information is not synchronized with rotation of the rotational magnetic field.

The motor according to the exemplary embodiment of the present invention includes the motor driving device.

The air blowing device according to the illustrated embodiment of the present invention includes the motor and an impeller having blades rotatable about a central axis extending in the vertical direction.

According to the present invention, it is possible to provide a motor drive control device, a motor, and an air blowing device that can reduce power consumption during a start-up operation.

Drawings

The above and other features, elements, steps, features and advantages of the present invention will be more clearly understood from the following description of preferred embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 is a block diagram showing an example of an air blowing device.

Fig. 2 is a flowchart for explaining an example of drive control of the motor unit.

Fig. 3 is a graph showing an example of a terminal voltage detected from an electrical angle of a rotor in the sensorless control of the motor unit.

Fig. 4 is a flowchart for explaining an example of the starting operation of the motor unit.

Detailed Description

The illustrated embodiments of the present disclosure are described with reference to the following drawings.

In the present description, the direction parallel to the rotation center axis CA of the motor unit 1 and the blades 111 in the air blowing device 100 is referred to as the "axial direction".

The U-phase winding 12U, the V-phase winding 12V, and the W-phase winding 12W of the stator 11 of the motor unit 1 are referred to as the phase windings 12, respectively or collectively. In the three-phase alternating voltage, the phase that is energized by the phase winding 12 is referred to as an energized phase, and the phase that is not energized by the phase winding 12 is referred to as an unenergized phase. In addition, a combination of 2 energized phase windings 12 is referred to as an energization pattern. The U-phase voltage, the V-phase voltage, and the W-phase voltage of the three-phase ac voltage, respectively or collectively, will be referred to as the phase voltages.

(1, Structure of Ventilation device)

Fig. 1 is a block diagram showing an example of an air blowing device 100. The blower 100 is an axial fan that generates an airflow flowing from one side to the other side in the axial direction in the present embodiment. However, the air blower 100 is not limited to this example, and may be a centrifugal fan that sends air taken in from the axial direction to the radial outside.

As shown in fig. 1, the blower 100 includes an impeller 110 and a motor 120. The impeller 110 has blades 111 rotatable about a central axis CA extending in the vertical direction. The motor 120 drives and rotates the impeller 110, thereby rotating the blades 111. Further, blower 100 is connected to dc power supply 200. The dc power supply 200 is a power source of the blower device 100. As shown in fig. 1, a positive output terminal on the high voltage side of the dc power supply 200 is connected to an inverter 3, described later, of the motor 120. The negative output terminal of the low voltage side of the dc power supply 200 is grounded. As a result, as will be described later, the blower device 100 can reduce power consumption during the startup operation.

(2, structural elements of the Motor)

Next, each component of the motor 120 will be described. The motor 120 includes a motor unit 1, an inverter 3, and a motor drive control device 4. That is, the motor 120 includes the motor drive control device 4. This can reduce the power consumption during the startup operation as described later.

The motor 1 is applied with a three-phase ac voltage. Specifically, the motor 1 is a three-phase brushless DC motor (BLD motor), and a three-phase ac voltage is applied from the inverter 3. The motor unit 1 includes a rotor 10 and a stator 11. The rotor 10 is provided with permanent magnets. The stator 11 is provided with a U-phase winding 12U, a V-phase winding 12V, and a W-phase winding 12W. In the present embodiment, the

phase windings

12u, 12v, and 12w are Y-connected around the point 12 c. In each of the

phase windings

12u, 12v, and 12w, the opposite side ends of the point 12c are connected to

terminals

13u, 13v, and 13w of the motor unit 1, respectively. The

phase windings

12u, 12v, and 12w are not limited to this example, and may be connected in a delta (delta) manner.

The inverter 3 outputs the three-phase ac voltage to the motor unit 1. The inverter 3 has

upper arm switches

31u, 31v, 31w and

lower arm switches

32u, 32v, 32 w. The upper arm switches 31u, 31v, and 31w and the

lower arm switches

32u, 32v, and 32w form a bridge circuit that generates a three-phase ac voltage to be output to the motor unit 1. The bridge circuit includes a U-phase arm connecting the high-voltage upper arm switch 31U and the low-voltage lower arm switch 32U in series, a V-phase arm connecting the high-voltage upper arm switch 31V and the low-voltage lower arm switch 32V in series, and a W-phase arm connecting the high-voltage upper arm switch 31W and the low-voltage lower arm switch 32W in series. The arms are connected in parallel with each other. The high-voltage-side end of each arm is connected to the high-voltage-side terminal of the dc power supply 200. Therefore, each arm is applied with a direct-current voltage from the direct-current power supply 200. The low-voltage side end of each arm is grounded via a current detection resistor 3 a.

The

upper arm switches

31u, 31v, and 31w and the

lower arm switches

32u, 32v, and 32w include switching elements and diodes, respectively. As the switching element, for example, an FET (field effect transistor), an IGBT (insulated gate bipolar transistor), or the like is used. The diode is connected in parallel with the switching element, with a direction from the low voltage side to the high voltage side of the dc power supply 200 being a forward direction. In other words, the anode of the diode is connected to the low-voltage side end of the switching element, and the cathode is connected to the high-voltage side end of the switching element. The diode functions as a free wheel diode (freewheeling diode). In addition, the diode may be a body diode built in the FET, or may be externally attached to the switching element.

The motor drive control device 4 controls the driving of the motor unit 1. More specifically, the motor drive control device 4 performs PWM (Pulse Width Modulation) control on the inverter 3, and controls the driving of the motor unit 1 via the inverter 3. Further, the motor drive control device 4 detects a current flowing from the low-voltage side end of the bridge circuit of the inverter 3 to the current detection resistor 3a, and controls a current value I flowing from the inverter 3 to the motor unit 1 based on the detection result.

(3, structural elements of the Motor drive control device)

The motor drive control device 4 includes a drive control unit 41, a voltage detection unit 44, and a position information generation unit 46. As shown in fig. 1, the motor drive control device 4 includes a drive control unit 41, a current detection unit 42, a storage unit 43, a voltage detection unit 44, a determination unit 45, a position information generation unit 46, and a rotation speed detection unit 47.

The drive control unit 41 controls the driving of the motor unit 1 by switching the energization pattern of the phase winding 12 of the motor unit 1 to which the ac voltage is applied and generating a rotating magnetic field in a predetermined order. The drive control unit 41 controls the driving of the motor unit 1 to which the three-phase ac voltage is applied, and switches the energization pattern to the phase winding 12 of the motor unit 1 in a predetermined sequence n. In addition, n is a positive integer. For example, the drive control unit 41 sensorless controls the drive of the motor unit 1 using a program and information stored in the storage unit 43. Specifically, the drive control unit 41 controls the

upper arm switches

31u, 31v, and 31w or the

lower arm switches

32u, 32v, and 32w of the inverter 3 by PWM pulses. Thus, the drive control unit 41 can control the drive of the motor unit 1 using the inverter 3 that outputs the three-phase ac voltage.

The current detection unit 42 detects a current flowing through a current detection resistor 3a connected between the bridge circuit of the inverter 3 and the ground GND, and detects the current value as a current value I flowing through the motor unit 1.

The motor drive control device 4 has a nonvolatile storage unit. That is, the storage unit 43 is a nonvolatile storage medium that maintains storage even when power supply is stopped. The storage unit 43 stores information used by each component of the motor drive control device 4, and particularly stores a program and control information used by the drive control unit 41. For example, the storage unit 43 stores the start phase of the rotating magnetic field generated in the implementation of the forced rectification described later and the number of times of implementation of the forced rectification.

The voltage detection unit 44 detects the voltage of the phase winding 12. The voltage detection unit 44 detects, as an induced voltage generated in the phase winding 12, a terminal voltage of the terminal 13 connected to the phase winding 12 to which current is not supplied, among the terminal voltages Vu, Vv, Vw. Specifically, when current is passed between terminals 13v and 13w of motor unit 1, voltage detection unit 44 detects terminal voltage Vu at terminal 13U as the U-phase voltage of U-phase winding 12U. When current is passed between terminals 13w and 13u of motor unit 1, voltage detection unit 44 detects terminal voltage Vv at terminal 13V as the V-phase voltage of V-phase winding 12V. When current is passed between

terminals

13u and 13v of motor unit 1, voltage detector 44 detects terminal voltage Vw of terminal 13W as W-phase voltage of W-phase winding 12W

The determination unit 45 performs various determinations. The position information generating unit 46 generates rotational direction position information in the rotational direction of the rotor 10 of the motor unit 1 based on the detection result of the voltage detecting unit 44.

The rotation speed detecting unit 47 detects the rotation speed of the rotor 10 of the motor unit 1 based on the rotational direction position information.

(4, example of drive control of Motor portion)

Next, an example of a drive control process of the motor unit 1 by the motor drive control device 4 will be described. Fig. 2 is a flowchart for explaining an example of drive control of the motor unit 1. Fig. 3 is a graph showing an example of terminal voltages Vu, Vv, Vw detected from the rotational direction position of the rotor 10 in the sensorless control of the motor unit 1. In fig. 3, the curves for the terminal voltages Vu, Vv, Vw represent the terminal voltages at the time of non-energization.

At the start time point of fig. 2, the rotor 10 of the motor unit 1 stops or rotates at a low speed. Therefore, since the induced voltage necessary for generating the rotational direction position information is generated in each of the

phase windings

12u, 12v, and 12w, the drive control unit 41 performs the starting operation of the motor unit 1 (step S1). In the state before the start operation, the rotor 10 is stopped or rotated at a low speed, and therefore the position information generating unit 46 cannot generate the rotational direction position information of the rotor 10. In contrast, in the starting operation, the rotor 10 of the motor unit 1 is forcibly rotated by the forced rectification.

In the forced commutation, the energization mode is switched every predetermined energization period, and 2 of the three phase windings 12 of the motor portion 1 are energized and excited. The combination of 2 phase windings 12 is switched in a predetermined order. Thereby, a rotating magnetic field having a constant rotation speed is generated. In addition, in each energization mode, the remaining one phase winding 12 is not energized. For example, if the energized phase is a U-phase and a V-phase, the non-energized phase is a W-phase.

Next, the drive control unit 41 performs a synchronous operation of the motor unit 1 to accelerate the rotation of the rotor 10 (step S2). In the synchronous operation, the position information generating unit 46 generates the rotational direction position information based on, for example, an inspection result at a timing when the phase voltage of the non-energized phase is equal to the virtual neutral point voltage Vn and an inspection result of an increasing/decreasing tendency of the phase voltage of the non-energized phase at the timing in each energization mode.

For example, if the virtual neutral point voltage Vn is 3V when the excitation is performed as shown in fig. 3, the rotational direction position of the rotor 10 is detected as an electrical angle 0deg (or 360deg) at a point where the terminal voltage Vu increases to 3V when the U phase is the non-energized phase. Further, at the point where the terminal voltage Vu decreases to 3V, the rotational direction position of the rotor 10 is detected to be the electrical angle 180 deg.

When the V phase is the non-energized phase, the rotational direction position of the rotor 10 is detected as the electrical angle 120deg at a point where the terminal voltage Vv increases to 3V. Further, at the point where the terminal voltage Vv decreases to 3V, the rotational direction position of the rotor 10 is detected as an electrical angle 300 deg.

When the W phase is the non-energized phase, the rotational direction position of the rotor 10 is detected as the electrical angle 60deg at a point where the terminal voltage Vw decreases to 3V. Further, at the point where the terminal voltage Vw increases to 3V, the rotational direction position of the rotor 10 is detected as the electrical angle 240 deg.

During the synchronous operation, the drive control unit 41 switches the energization pattern based on the rotational direction position information for each energization period corresponding to the rotational speed of the rotor 10 detected by the rotational speed detection unit 47, and accelerates the rotation of the rotor 10.

When the rotation speed is equal to or greater than the predetermined number, the drive control unit 41 performs the steady control operation of the motor unit 1 (step S3). In the steady control operation, the rotor 10 rotates at a desired rotation speed, and the energization mode is switched according to the drive information and the rotational direction position information of the motor unit 1. Thereby, the motor unit 1 is driven. Then, if the driving of the motor unit 1 is stopped (yes at step S4), the drive control process of fig. 2 is ended.

(5, example of starting operation of Motor portion)

Next, an example of the starting operation of the motor unit will be described. Fig. 4 is a flowchart for explaining an example of the starting operation of the motor unit 1. If the start-up operation is started, the drive control unit 41 performs initial processing in step S100, and the process proceeds to step S101. The initial processing short-circuits the

terminals

13u, 13v, 13w of the motor unit 1 and performs short-circuit braking. Thereby, the rotor 10 is stopped. The number m of times of performing forced rectification stored in the storage unit 43 in the previous startup operation is reset, and the storage m is equal to 0.

In step S101, the drive control unit 41 generates a rotating magnetic field during the start-up operation of the motor unit 1 and performs forced rectification for forcibly rotating the drive rotor 10. In the implementation of forced commutation, the rotating magnetic field rotates at a constant rotational speed. That is, the rotating magnetic field that is forcibly rectified switches the energization mode a plurality of times during a constant energization period, so that the electrical angle rotates 60deg at a time at a constant rotational speed. In addition, the excitation phase of the rotating magnetic field is switched in order of the first excitation phase, the second excitation phase, and the third excitation phase every time the electrical angle is deviated from 120 deg. The rotating magnetic field of the forced rectification was switched to the energization mode 12 times and rotated 2 times. Thus, the period of time for implementing forced commutation can be shortened, and the success rate of starting the rotor can be improved. When each energization period of the energization mode is set to 12.8ms, the period for implementing 1-time forced rectification is set to 12.8 × 12 to 153.6 ms.

When the starting electrical angle is set to 0deg, the starting phase of the rotating magnetic field is the first excitation phase. By the rotation of the rotating magnetic field, the electrical angle is changed in the order of 0deg, 60deg, 120deg, 180deg, 240deg, 300deg, 360deg, 60deg, 120deg, 180deg, 240deg, 300 deg. In addition, 360deg is the same electrical angle as 0 deg.

Immediately after the forced commutation is started, the position information generating unit 46 generates rotational direction position information of the rotational direction of the rotor 10. When the forced rectification is completed, the number of times m of the forced rectification is added to 1, and m is stored in the storage unit 43 as 1, and the process proceeds to step S102.

In step S102, the determination unit 45 determines whether or not the rotational direction position information is synchronized with the rotation of the rotating magnetic field. When the rotational direction position information is synchronized with the rotation of the rotating magnetic field (yes in step S102), the motor unit 1 determines that the start is normal, and proceeds to step S103. The determination in step S102 can be made by determining whether or not the rotor 10 is rotating at a predetermined rotation speed with respect to a rotating magnetic field rotating at a constant rotation speed.

In step S103, the start phase of the rotating magnetic field of the forced rectification performed before is stored in the storage unit 43. That is, when the rotational direction position information is synchronized with the rotation of the rotating magnetic field, the start phase of the forced rectification is stored in the storage unit 43. After the start phase is stored in the storage unit 43, the startup operation is ended. After the start-up operation is ended, the synchronous operation of step S2 of fig. 2 is started.

On the other hand, when the rotation direction position information and the rotation of the rotating magnetic field are not synchronized (no in step S102), the motor unit 1 determines that the normal start-up is not performed, and proceeds to step S104.

In the startup operation, an upper limit value of the number of times forced rectification is performed is determined in advance. In the present embodiment, the number of times of execution is 3. That is, in step S104, it is determined whether the number m of times of performing the forced rectification stored in the storage unit 43 reaches 3 times. In the startup operation, the upper limit value of the number of times of implementation of forced rectification is predetermined to be 3 times. If the number of times of forced rectification has not reached 3 times (no in step S104), the process proceeds to step S105. By limiting the number of times of execution in this way, for example, when the start-up is not possible for another reason, it is possible to suppress the consumption of time and power. In particular, when the electrical angle is changed by 120deg each time the forced commutation is performed, the electrical angle is changed to 360 degrees by 3 times to 1 cycle, so that there is a high possibility of other causes when the start-up is not possible even if the forced commutation is performed 3 times, and the consumption of time and power can be suppressed.

In step S105, the starting phase of the rotating magnetic field of the next forced rectification is changed and the process returns to step S101. Specifically, the starting electrical angle of the rotating magnetic field is changed to 120deg, and the second excitation phase becomes the starting phase. That is, in the start-up operation, when the rotational direction position information and the rotation of the rotating magnetic field are out of synchronization, the starting electrical angle of the rotating magnetic field is shifted by 120deg, and the forced rectification is performed next time.

Thus, in the second forced commutation in step S101, the electrical angle is changed in the order of 120deg, 180deg, 240deg, 300deg, 360deg, 60deg, 120deg, 180deg, 240deg, 300deg, 360deg, and 60deg by the rotation of the rotating magnetic field. In addition, 360deg is the same electrical angle as 0 deg.

When the second forced commutation is completed, the number of times m of the forced commutation is added to 1, and m is stored in the storage unit 43 as 2, and when it is determined that the motor unit 1 is not normally started in step S102, the process proceeds from step S104 to step S105, as in the case after the first forced commutation.

In step S105, the start phase of the rotating magnetic field to be forcibly rectified next time is changed, and the process returns to step S101. Specifically, the starting electrical angle of the rotating magnetic field was changed to 240deg, and the third excitation phase was the starting phase.

Thus, in the third forced commutation in step S101, the electrical angle is changed in the order of 240deg, 300deg, 360deg, 60deg, 120deg, 180deg, 240deg, 300deg, 360deg, 60deg, 120deg, and 180deg by the rotation of the rotating magnetic field. In addition, 360deg is the same electrical angle as 0 deg.

In the start-up operation, normally, the rotor 10 is stopped or rotated at a low speed before the phase energization is started. Therefore, a relatively large driving force is required at the time of the phase energization. In addition, in the relative angle of the starting phase and the rotor 10, the driving force generated by the rotor 10 may be relatively small. When the driving of the motor unit 1 is stopped, the rotor 10 is located at a rotational direction position where the rotor is likely to stop. If the relative angle matches the rotational direction position, the starting success rate of the rotor 10 decreases. In the present embodiment, when the rotational direction position information and the rotation of the rotating magnetic field are not synchronized (no in step S102), the rotating magnetic field having a different start phase is generated and the forced rectification is repeated. Thus, any one of the start phases coincides with the excitation phase in which the rotor generates a large driving force. Therefore, an optimal starting phase can be found and the success rate of starting the rotor 10 is improved.

In the forced commutation, the energization periods of the energization patterns are all the same, and the rotating magnetic field rotates at a constant rotation speed. Thus, it is not necessary to make the conduction period of the start phase, in which a large driving force is necessary, longer than the subsequent conduction period. Therefore, the power consumption at the time of the startup operation can be reduced.

In the start-up operation, only the forced rectification is performed without performing the dc excitation for positioning the rotor 10. Thus, the power consumption at the time of the startup operation can be reduced.

If the third forced commutation is finished, the number m of times of forced commutation is increased by 1 and stored in the storage unit 43 as m equal to 3.

When the rotational direction position information and the rotation of the rotating magnetic field are not synchronized in the third forced commutation (no in step S102), it is determined in step S104 that the number m of times of forced commutation has reached 3 times (yes in step S04). At this time, the startup operation is ended, and the synchronous operation of fig. 2 is not started. That is, when the rotating magnetic field is generated in the U-phase, V-phase, and W-phase starting phases and the motor unit 1 is not normally started, it is determined that the motor unit 1 is not normally started due to factors other than the shortage of the driving force. In this way, when the rotor 10 is not rotating due to something other than a shortage of the driving force, it is possible to prevent the start-up operation from being stopped early and wasteful power consumption from occurring.

In the next startup operation, in step S101, the same rotating magnetic field of the previous starting phase stored in the storage unit 43 is generated and forced rectification is performed. That is, when the rotational direction position information is synchronized with the rotation of the rotating magnetic field in the startup operation, the rotating magnetic field of the same start phase as the previous one is generated and forced rectification is performed in the next startup operation. This can improve the starting success rate of the rotor 10 in the first forced commutation in the starting operation. Therefore, the start-up time of the motor unit 1 can be shortened.

(6, others)

The above description of the exemplary embodiments is provided in the present disclosure. In addition, the scope of the invention is not limited by this disclosure. The present disclosure can be implemented with various modifications without departing from the scope of the invention. In addition, the matters described in the present disclosure can be arbitrarily combined as appropriate within a range not inconsistent with each other.

In the present embodiment, in the second forced commutation, the second excitation is set as the start phase by deviating 120deg from the start electrical angle of the first forced commutation, but the third excitation may be set as the start phase by deviating-120 deg (240deg) from the start electrical angle of the first forced commutation. In addition, the starting phase of the first forced commutation may be set to the second excitation phase or the third excitation phase. When the first excitation phase is set as the start phase, the start electrical angle may be set to 60 deg.

The present invention can be used for a motor drive control device, a motor, and an air blower, for example, in which a motor unit is sensorless controlled.

Claims

1. A motor drive control device is provided with:

a drive control unit that controls driving of the motor unit by switching an energization pattern of a phase winding of the motor unit to which an alternating-current voltage is applied in a predetermined order and generating a rotating magnetic field;

a voltage detection unit that detects a voltage of the phase winding; and

a position information generating unit that generates rotational direction position information in a rotational direction of a rotor of the motor unit based on a detection result of the voltage detecting unit,

it is characterized in that the preparation method is characterized in that,

the drive control unit generates the rotating magnetic field and performs forced rectification for forcibly rotating and driving the rotor during a start-up operation of the motor unit, and when the rotational direction position information is not synchronized with rotation of the rotating magnetic field, generates the rotating magnetic field having a different starting phase and repeats the forced rectification.

2. The motor drive control device according to claim 1,

the motor section is applied with a three-phase ac voltage,

when the rotational direction position information is not synchronized with the rotation of the rotating magnetic field, the starting electrical angle of the rotating magnetic field is shifted by 120deg, and the forced rectification is performed next time.

3. The motor drive control device according to claim 1 or 2,

in the forced rectification, the rotating magnetic field rotates at a constant rotation speed.

4. The motor drive control device according to any one of claims 1 to 3,

in the start-up operation, when the rotational direction position information is synchronized with the rotation of the rotating magnetic field, the rotating magnetic field of the same starting phase as the previous one is generated and the forced rectification is performed in the next start-up operation.

5. The motor drive control device according to claim 4,

the motor drive control device includes a nonvolatile storage unit,

and storing the start phase of the forced rectification in the storage unit when the rotational direction position information is synchronized with the rotation of the rotating magnetic field.

6. The motor drive control device according to any one of claims 1 to 5,

in the start-up operation, an upper limit value of the number of times of implementation of the forced rectification is determined in advance.

7. The motor drive control device according to claim 6,

the number of the above-mentioned implementations is 3.

8. An electric motor, characterized in that,

the motor includes the motor drive control device according to any one of claims 1 to 7.

9. An air supply device is characterized in that,

the air blower includes:

the motor of claim 8; and

an impeller having blades rotatable about a central axis extending in a vertical direction.