JP3508560B2 - Commutation abnormality detection device, commutation abnormality detection method, motor drive control device, and motor drive control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus capable of detecting a commutation abnormality at the time of starting a sensorless motor and at the time of sensorless driving, and further driving the sensorless sensorless sensor. The present invention relates to a motor drive control method and apparatus.

[0002]

2. Description of the Related Art In sensorless driving of a motor, a counter electromotive force obtained from an exciting coil is detected by rotating a rotor, and the detected back electromotive force voltage crosses a neutral point voltage from a zero cross point, for example, a phase. Is realized by performing a commutation operation at a point shifted by 30 degrees.

Therefore, when the motor is stopped,
Since the back electromotive force cannot be obtained from the exciting coil and the sensorless drive cannot be performed, so-called forced commutation is performed to forcibly drive the rotor at the time of start-up where rotational drive is performed from the motor stopped state, and the predetermined value is set from the exciting coil. After the above counter electromotive force voltage is obtained, the sensorless drive is performed by shifting to the sensorless drive.

In order to surely shift the sensorless drive from the forced commutation, for example, Japanese Patent Laid-Open No. 4-2952.
According to the technique disclosed in Japanese Patent Publication No. 95, etc., the drive control of the motor is performed as a criterion for the control transition depending on whether or not the rotor rotation speed has reached a predetermined value.

By the way, the back electromotive force waveform of the open phase is usually as follows after the spike voltage disappears as shown by the dotted line in FIG.
The voltage rises from a voltage lower than the midpoint voltage and crosses the midpoint comparison reference voltage, but is detected, but when disturbance or a large load is input, the voltage range of the spike voltage expands, and after the spike voltage disappears Start rising from high voltage. In this case, since the midpoint detection point of the counter electromotive force to be originally detected is masked by the spike voltage, the original commutation point a cannot be grasped, and a commutation abnormality occurs in which the commutation point shifts. There was something that happened. Therefore, it has been expected that an excellent technique capable of detecting this commutation abnormality by applying the conventional technique or an improved version thereof will be developed.

[0006]

However, for example, each of the three-phase winding voltages is the power supply voltage, half the power supply voltage,
When the technique described in Japanese Patent Application Laid-Open No. 5-161388, which determines that the motor is in the stopped state when the state of being at the ground voltage continues for a certain period of time or more, only the stopped state due to the failure of the motor start control is applied. However, it was not possible to detect the commutation abnormality.

Further, the technique disclosed in Japanese Patent Laid-Open No. 5-236790 detects the duty ratio of the counter electromotive force, and when the duty ratio becomes approximately 50 (%), it is normal.
Conversely, if it does not reach approximately 50 (%), it is judged as abnormal rotation, but in a hybrid step motor or the like, the duty ratio may not reach approximately 50 (%) even during normal operation. It was difficult to detect commutation abnormalities.

The present invention has been made to solve such a conventional problem, and an object thereof is to provide means for detecting a commutation abnormality.

Another object of the present invention is to provide a means for controlling the drive of a motor which is driven without a sensor while detecting a commutation abnormality.

[0010]

In order to achieve the above object, the invention according to claim 1 is a device capable of detecting a commutation abnormality of a motor driven without a sensor, and a counter electromotive force output from the motor. A polarity discriminating means for discriminating the polarity of the electric power voltage, a commutation mode estimating means for estimating the commutation mode from the discrimination result, and a commutation mode determined in a predetermined order with reference to the reference voltage of the counter electromotive force voltage. Determining whether or not both the commutation mode estimated by the commutation mode estimation means and the commutation mode generated by the actual commutation mode generation means are coincident with each other. And a commutation mode comparison means for performing the commutation abnormality detection device.

As the reference voltage, the voltage at the middle point of the back electromotive force voltage, the neutral point voltage of the motor, and the motor terminal voltage are 3
It suffices to use a voltage or the like that is phase-synthesized.

According to the present invention, the polarity discriminating means discriminates the polarity of the counter electromotive force voltage outputted from the motor driven without the sensor, and the commutation mode estimating means judges the next commutation mode (for example, , The switching pattern of the transistors forming the inverter) is estimated (estimated commutation mode). On the other hand, the actual commutation mode generation means generates a commutation mode (actual commutation mode) determined in a predetermined order with reference to the reference voltage of the counter electromotive force voltage, and the commutation mode comparison means calculates the estimated commutation mode. Since it determines whether both the mode and the actual commutation mode match, if they match, it is detected that the commutation is normal, and in other cases, a commutation abnormality has occurred. It becomes possible to do.

Further, in the invention according to claim 2, when the commutation abnormality detecting device according to claim 1 and the commutation mode comparison means determine that both commutation modes match,
A commutation signal generating means for generating a commutation signal for the matched commutation mode; and an inverter means for generating a signal for driving the motor in a pattern according to the generated commutation signal. It is a motor drive control device.

According to the present invention, the commutation signal generating means is
When the actual commutation mode and the estimated commutation mode match, a commutation signal for this matched commutation mode is generated, and the inverter means drives the motor in a pattern according to the generated commutation signal. Since the signal for driving is generated, it is possible to perform the drive control of the motor that is driven without a sensor while detecting a commutation abnormality.

Further, in the invention according to claim 3, in claim 2, when the commutation mode comparison means determines that the two commutation modes do not match, the abnormality process is performed. It is characterized by having means.

According to the present invention, since the abnormal-time processing means performs the abnormal-time processing when the actual commutation mode and the estimated commutation mode do not match each other, the abnormal-time processing is performed. It is possible to let

Further, in the invention according to claim 4, in claim 3, the abnormal time processing means stops the driving of the motor or restarts after stopping the driving as the abnormal time processing. A motor drive control device comprising means for performing processing.

According to the present invention, since the abnormal time processing means performs the abnormal time processing of stopping the driving of the motor or restarting the motor after stopping the driving, when the commutation is abnormal, the motor is stopped or It is possible to automatically restart the motor after stopping it. According to a fifth aspect of the present invention, in any one of the second, third and fourth aspects, the motor is connected to a drive mechanism that moves a head carriage of the printer.

According to the present invention, since the motor is connected to the drive mechanism for moving the head carriage, the commutation abnormality can be detected, and the device for moving the head carriage by driving the motor can be realized. Become.

The invention according to claim 6 is the invention according to claim 2,
In any one of 3 and 4, the motor is connected to a paper feeding mechanism of the printer.

According to the present invention, since the motor is connected to the paper feeding mechanism of the printer, it is possible to realize a device which can detect a commutation abnormality and can feed the paper of the printer by driving the motor. .

The invention according to claim 7 is the invention according to claim 2,
In any one of 3, 4, 5 and 6, the motor is a three-phase hybrid step motor.

According to the present invention, by using a three-phase hybrid step motor as the motor, it is possible to detect a commutation abnormality of the three-phase hybrid step motor, and drive control of the three-phase hybrid step motor while detecting this. Is possible.

Further, it is another aspect of the present invention.
The invention according to claim 1 is a method for detecting a commutation abnormality of a motor that is driven without a sensor, and a step of determining the polarity of a back electromotive force voltage output from the motor, and estimating the commutation mode from this determination result. Whether the estimated commutation mode and the generated commutation mode are the same, and the step of generating a commutation mode determined in a predetermined order with reference to the reference voltage of the back electromotive force voltage. A commutation abnormality detection method comprising: a step of determining whether or not both are the same, and determining a commutation abnormality when the both do not match.

According to the present invention, the polarity of the counter electromotive force voltage output from the motor driven without a sensor is discriminated, and the estimated commutation mode estimated from the discrimination result and the reference voltage of the counter electromotive force voltage are referred to. Then, it is judged whether or not the two actual commutation modes, which are determined in a predetermined order, match, and if they match, the commutation is normal, and in other cases, the commutation abnormality occurs. It is possible to detect the occurrence.

The invention according to claim 9 is a drive control method for a motor that is driven without a sensor, wherein the step of determining the polarity of the back electromotive force voltage output from the motor and the commutation based on the determination result. Both the step of estimating the mode, the step of generating a commutation mode determined in a predetermined order with reference to the reference voltage of the counter electromotive force voltage, and both the estimated commutation mode and the generated commutation mode It is determined whether they match, if both do not match, a step of determining a commutation abnormality, and if it is determined that the commutation abnormality, stop driving the motor, or And a step of restarting after driving is stopped.

According to the present invention, the polarity of the counter electromotive force voltage output from the motor driven without a sensor is discriminated, and the estimated commutation mode estimated from the discrimination result and the reference voltage of the counter electromotive force voltage are referred to. Then, it is judged whether or not both of the actual commutation modes determined in a predetermined order match, and if they match, the commutation is normal, and in other cases, the commutation abnormality occurs. If it is determined that the commutation abnormality has occurred, the drive of the motor is stopped or the drive is stopped and then restarted. Can perform motor drive control that enables the motor to be automatically stopped or restarted after the motor is stopped.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a motor control device including a commutation abnormality detecting device according to an embodiment of the present invention.

This motor control device includes a polarity discriminating means 10 and an actual commutation mode generating means 30 which can input the back electromotive force voltage of each phase output from a three-phase hybrid step motor (HBM) 70. It has a commutation mode estimation unit 20, a commutation mode comparison unit 40 including an abnormal time processing unit 45, a commutation signal generation unit 50, and an inverter 60 that supplies a drive signal to the three-phase HBM 70.

A drive mechanism 80 for moving the carriage 90 of the printer is connected to the three-phase HBM 70,
By controlling the driving of the three-phase HBM 70, the movement of the carriage 90 is controlled.

Now, the configuration and operation of each component will be described.

The polarity discriminating means 10 is provided for each phase (A phase, B phase,
The polarity of the counter electromotive force voltage immediately before the detection of the midpoint voltage is determined at the moment when the midpoint voltage (an example of the reference voltage) of the counter electromotive force voltage is detected for each C phase). It is configured to output a "minus level" signal while outputting a "plus level" signal if the polarity is positive. For example, a comparator for comparison with the midpoint voltage or the output of this comparator. It can be realized by an operational amplifier or the like that outputs a positive level signal or a negative level signal according to the level.

The actual commutation mode generation means 30 refers to the polarity midpoint voltage of the back electromotive force voltage of each phase to determine the next commutation mode that is necessarily determined in a predetermined order from the current commutation mode. It is configured to generate and output, and can be realized by, for example, a microcomputer that performs a predetermined operation according to a combination of various logic circuits and a program.
The actual commutation mode generation means 30 also serves as a rotor position detection means for a sensorless motor that detects the rotor position from the back electromotive force voltage.

The commutation mode estimating means 20 is configured to estimate the commutation mode from the polarity discrimination result by the polarity discriminating means 10 by using a commutation mode estimation table 25 described later, for example, various logics. It can be realized by a microcomputer that performs a predetermined operation according to a combination of circuits and a program.

The commutation mode estimation table 25 is, for example, as shown in FIG. 4, and the detection phase, the polarity of the back electromotive force voltage immediately before the detection of the midpoint voltage output from the polarity discriminating means 10, and the later. Among the switching elements forming the inverter to be described, those which are to be conducted and the estimated commutation mode are described in association with each other. Thus, the midpoint voltage detection in the current detection phase output from the polarity determination means 10 is described. If the polarity signal of the immediately preceding back electromotive force voltage is determined, the next commutation mode is estimated using the commutation mode estimation table 25, and the estimated commutation mode is output.

For example, the detection phase is the A phase and the polarity discrimination means 10
The estimated commutation mode is “5” if the signal output from the device has a negative polarity.

The commutation mode comparison means 40 compares the actual commutation mode with the estimated commutation mode, and outputs a low-level commutation state detection signal indicating normal commutation if both match. , If both do not match, it is configured to output a high level commutation state detection signal indicating a commutation abnormality,
Furthermore, an abnormal time processing unit 45 that performs abnormal time processing when a commutation abnormality occurs is built in, and can be realized by, for example, a microcomputer that performs a predetermined operation according to a combination of various logic circuits and a program.

The abnormality processing performed by the abnormality processing unit 45 includes, for example, stopping the three-phase HBM 70 and the three-phase HBM.
Examples include restarting from the stop of 70.

The commutation signal generating means 50 drives the six switching elements of the inverter 60 corresponding to the actual commutation mode only when the commutation state detection signal is low and the commutation is normal. It is configured to generate a commutation signal, and can be realized by, for example, a microcomputer that performs a predetermined operation according to a combination of various logic circuits and a program.

Next, the more detailed structure and operation of the inverter 60 and the three-phase HBM 70 will be described with reference to FIGS.

This inverter 60 is so-called 120 °.
It is a conduction voltage type inverter, and has six FETs in which a freewheeling diode is individually connected in parallel with a power supply 61, three of which are upper (P-side) arms (AP and 62, BP and 63, CP).
And 64), and the remaining three are on the lower side (N side).
The arms (AN and 65, BN and 66, CN and 67) are configured. Further, the connection point between the FET (AP) and the FET (AN) is connected to the A-phase coil of the 3-phase HBM 70, and the FET
The connection point between (BP) and FET (BN) is a 3-phase HBM70.
Connected to the B-phase coil of, and further FET (CP) and F
The connection point with ET (CN) is connected with the C-phase coil of the 3-phase HBM 70. As the FET, one having a freewheeling diode may be used.

Further, the commutation signal generating means 50 is connected so that the corresponding commutation signal is applied to the gate terminal of each FET. Specifically, the coil is energized by either F of the upper arm and F of the lower arm energizing the coil of a phase other than the phase connected to this FET.
The motor can be drive-controlled by sequentially turning on and off (commutating) each FET so that the two FETs of ET are energized. The combination of the FETs in the conductive state is described as a mode number from "0" to "5" (corresponding to the commutation mode).

Then, the correspondence relationship among the electrical angles of the back electromotive force voltages of the A phase, the B phase and the C phase, the combination of the FETs in the conductive state, the open phase and the mode number is as shown in FIG. . Next, an outline of the operation of the device shown in FIG. 1 will be described with reference to the flowchart of FIG.

Now, assume that the drive control of the three-phase HBM 70 shifts from forced excitation to sensorless drive. First,
In step S500, the polarity determination means 10 determines the polarity of the back electromotive force voltage.

Next, in step S510, the commutation mode estimation means 20 outputs the estimated commutation mode, and
The actual commutation mode generation means 30 outputs the actual commutation mode.

Next, in step S520, the commutation mode comparison means 40 determines whether the estimated commutation mode and the actual commutation mode match. If they match (Yes)
, A commutation state detection signal indicating that the commutation is normal is output.

Then, in step S530, the commutation signal generating means 50 generates and outputs a commutation signal corresponding to this actual commutation mode. The respective FETs of the inverter 60 are turned on and off corresponding to this commutation signal and turned into a three-phase HB.
M70 is drive-controlled, and thus the carriage 90 is moved to a desired position by the action of the drive mechanism 80.

On the other hand, in step S520, when the commutation mode comparison means 40 determines that the estimated commutation mode and the actual commutation mode do not match (No), the commutation state indicating that the commutation is abnormal. Output the detection signal. Then, in step S540, the abnormality processing unit 45 performs the abnormality processing. More specifically, the abnormal time processing unit 45 uses the three-phase HB.
The commutation signal generation means 50 is controlled so as to stop the M70, or the commutation signal generation means 50 is controlled so that the three-phase HBM 70 is once stopped and then restarted.

Next, FIG. 6 shows a timing chart showing the operation during normal commutation.

Since the A-phase, B-phase, and C-phase terminal voltages are periodically output, the polarities of the voltages are alternately changed between positive and negative.

Therefore, the estimated commutation modes are "3, 4,
5, 0, 1, 2, ... ", and the actual commutation mode also changes to" 3, 4, 5, 0, 1, 2, ... ". Therefore, the estimated commutation mode and the actual commutation mode change. At the same time, a low level commutation state detection signal is output, and the commutation signal generation means 50
Switches each FET of the inverter 60 in the commutation mode corresponding to the mode number “3, 4, 5, 0, 1, 2, ...”. As a result, the carriage 90 moves to the drive mechanism 8
0 moves to the desired position.

On the other hand, FIG. 7 shows a timing chart showing the operation at the time of abnormal commutation. This case can be considered, for example, when the waveform of the back electromotive force voltage is not periodic due to disturbance or the like, and the midpoint voltage cannot be detected normally.

In the example shown in FIG. 7, it is assumed that the back electromotive force voltage is disturbed when the A phase is the open phase. Normally, if commutation is performed as it is, then the waveform of the back electromotive force voltage is broken line. And the phase relationship between the electrical angle of each phase and the commutation mode shown in FIG. 3 cannot be maintained.
A phenomenon such as motor step-out may occur.

In the embodiment of the present invention, when the waveform of the counter electromotive force voltage is disturbed, the counter electromotive force voltage changes from the positive to the negative at the midpoint voltage, so the polarity discriminating means 10 is used.
Outputs a positive level signal as a result of the A phase polarity determination. As a result, the commutation mode estimation means 20 refers to the commutation mode estimation table 25 and estimates that the mode to be next commutated is “2”. On the other hand, in the actual commutation mode generation means 30, since the commutation modes have changed in the order of “0, 1, 2, 3, 4”, the next actual commutation mode is assumed to be “5”. Therefore, the commutation mode comparison means 40 determines that the estimated commutation mode and the actual commutation mode do not match, and the commutation state detection signal changes from low level to high level. As a result, the commutation signal generating means 50 is controlled by the abnormal time processing unit 45 so as to output a signal to stop the motor or restart the stopped motor.

Therefore, it is possible to accurately detect the commutation abnormality even during sensorless drive transition in which an unexpected disturbance is likely to be mixed in the back electromotive force voltage and during sensorless steady drive other than the sensorless drive transition. Yes, if such commutation abnormality is detected, 3-phase H
Stop the BM70 and restart from the stop,
It is possible to perform sensorless drive transfer and sensorless steady drive in a normal commutation state.

As described above, according to the embodiment of the present invention, the polarity discriminating means 10 has the three-phase HBM 70.
The polarity of the back electromotive force voltage output from the device is determined, and the commutation mode estimation unit 20 estimates the next commutation mode from the determination result. On the other hand, the actual commutation mode generation means 30 generates an actual commutation mode determined in a predetermined order with reference to the midpoint voltage of the back electromotive force voltage, and the commutation mode comparison means 40 determines the estimated commutation mode. Since it is determined whether the actual commutation modes match, if they match, it is detected that the commutation is normal, and in other cases, the commutation abnormality occurs. Is possible.

When the actual commutation mode and the estimated commutation mode match, the commutation signal generating means 50 generates a commutation signal for the matched commutation mode, and the inverter 60 outputs the commutation signal. Since the signal for driving the three-phase HBM 70 is generated in a pattern according to the generated commutation signal, it is possible to control the drive of the motor that is driven without a sensor while detecting a commutation abnormality.

Further, since the abnormal time processing unit 45 performs the abnormal time processing in the case of a commutation abnormality in which the actual commutation mode and the estimated commutation mode do not match, the processing corresponding to the commutation abnormality is performed. In particular, if the abnormal-time process of stopping the driving of the three-phase HBM 70 or restarting the driving after stopping the driving is performed, the
It is possible to automatically stop the motor or restart the motor from the stop.

Further, since the three-phase HBM 70 is connected to the drive mechanism 80 for moving the carriage 90, a printer device or the like that moves the carriage 90 by driving the three-phase HBM 70 while being able to detect a commutation abnormality is realized. It becomes possible.

In particular, when the motor for moving the carriage 90 is driven in a commutation abnormal state, it is not possible to perform clean printing due to vibration, but according to the embodiment of the present invention, when a commutation abnormality occurs. Since the motor is immediately stopped and the motor is restarted, it is possible to realize a printer device that solves such a problem.

According to the description of the above-described embodiment, the drive mechanism 80 for moving the carriage 90 is connected to the three-phase HBM 70 as an example. 3-phase HBM for feed mechanism
One in which 70 is connected is also conceivable. According to this, it is possible to realize a printer device or the like that can detect a commutation abnormality and that feeds paper by driving the three-phase HBM 70.

In the embodiments of the present invention described above, a three-phase hybrid step motor has been described as an example of a sensorless driving motor, but the present invention can be driven by other types of sensorsless. It goes without saying that it can also be applied to a motor.

[0064]

As described above, according to the present invention,
It is possible to achieve an effect that it is possible to realize a means for detecting a commutation abnormality and a means for performing drive control of a motor driven without a sensor while detecting a commutation abnormality.

Further, in the prior art, it was possible that an abnormal state of commutation would continue and overcurrent would flow through the motor, causing damage to the motor. However, according to the present invention, immediately after the abnormality in commutation is detected. Since the motor is stopped at this time, it is possible to obtain an effect that damage to the motor can be prevented.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a motor control device including a commutation abnormality detection device according to an embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of an inverter circuit 60 and a three-phase HBM 70.

FIG. 3 is an explanatory diagram illustrating a relationship between a conduction state of a switching element included in the inverter circuit 60, an actual commutation mode, and a phase of a back electromotive force.

FIG. 4 is an explanatory diagram of a commutation mode estimation table 25.

FIG. 5 is a flowchart showing an operation of the motor control device according to the embodiment of the present invention.

FIG. 6 is a timing chart showing an operation during normal commutation.

FIG. 7 is a timing chart showing an operation when a commutation is abnormal.

FIG. 8 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

10 Polarity discrimination means 20 Commutation mode estimation means 25 Commutation mode estimation table 30 actual commutation mode generation means 40 Commutation mode comparison means 45 Abnormality processing unit 50 Commutation signal generation means 60 inverter 61 power supply 62, 63, 64, 65, 66, 67 Circulating diode 70 3-phase HBM 80 drive mechanism 90 carriage AP FET BP FET CP FET AN FET BN FET CN FET

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Tabata 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Co., Ltd. (56) Reference JP-A-2-111220 (JP, A) JP A 63-294289 (JP, A) JP 7-14793 (JP, A) JP 6-62593 (JP, A) JP 63-52687 (JP, A) JP 61-18387 (JP, A) JP 5-111285 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 6/18 H02P 6/12 H02P 8/00 303 H02P 8/38

Claims (9)

(57) [Claims] 1. A device capable of detecting a commutation abnormality of a motor driven without a sensor, comprising polarity determining means for determining a polarity of a back electromotive force voltage output from the motor, and a commutation mode based on the determination result. A commutation mode estimating means for estimating a commutation mode, an actual commutation mode generating means for generating a commutation mode determined in a predetermined order with reference to a reference voltage of the counter electromotive force voltage, and an estimation by the commutation mode estimating means. A commutation mode comparison means for determining whether or not both the commutation mode generated and the commutation mode generated by the actual commutation mode generation means match;
A commutation abnormality detection device comprising: 2. When the commutation abnormality detection device according to claim 1 and the commutation mode comparison means determine that both commutation modes match, the commutation mode for the matched commutation mode is determined. A motor drive control device comprising: a commutation signal generating means for generating a flow signal; and an inverter means for generating a signal for driving the motor in a pattern according to the generated commutation signal. 3. The abnormal condition processing unit according to claim 2, further comprising an abnormal condition processing unit that performs abnormal condition processing when the commutation mode comparison unit determines that the two commutation modes do not match. Motor drive control device. 4. The abnormal time processing means according to claim 3, wherein the abnormal time processing means is a means for stopping the drive of the motor or for restarting after stopping the drive as the abnormal time processing. A motor drive control device characterized by: 5. The motor drive control device according to claim 2, wherein the motor is connected to a drive mechanism that moves a head carriage of the printer. 6. The motor drive control device according to claim 2, wherein the motor is connected to a paper feeding mechanism of a printer. 7. The motor drive control device according to claim 2, wherein the motor is a three-phase hybrid step motor. 8. A method for detecting a commutation abnormality of a motor driven without a sensor, comprising the steps of determining the polarity of a back electromotive force voltage output from the motor, and estimating the commutation mode from the determination result. Whether the estimated commutation mode and the generated commutation mode are the same, and the step of generating a commutation mode determined in a predetermined order with reference to the reference voltage of the back electromotive force voltage. A commutation abnormality detection method, comprising the step of determining whether or not both are the same and determining that the two are not commutation abnormality. 9. A drive control method for a sensorless motor, comprising: determining the polarity of a back electromotive force voltage output from the motor; estimating a commutation mode from the determination result; Determine if the estimated commutation mode and the generated commutation mode both match the step of generating the commutation modes that are determined in a predetermined order with reference to the reference voltage of the back electromotive force voltage. However, if the two do not match, it is determined that there is an abnormality in commutation, and if it is determined that the commutation is abnormal, the drive of the motor is stopped, or the drive is stopped and then re-executed. And a step of starting the motor drive control method.