JPH06103993B2 - Sensorless brushless motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sensorless brushless motor in which a drive magnetic pole position detector is omitted.

(Prior Art) In recent years, brushless motors have been widely used. In this brushless motor, a so-called sensorless type brushless motor in which a drive magnetic pole position detector such as a Hall element is omitted is known.

FIG. 10 is a block diagram showing an example of a conventional sensorless brushless motor. FIG. 10 (A) is an overall view and FIG. 10 (B).
FIG. 3 is a detailed view of the oscillation starting circuit of FIG. 2A, FIG. 2 is a waveform diagram for explaining the operation of the motor of FIGS. 1, 8 and 10 during steady rotation, and FIG. FIG. 11 is a waveform diagram illustrating an operation at the time of starting the motors of FIGS. 1, 8 and 10.

As shown in FIG. 10 (A), a four-pole drive magnetic pole 2a formed on a disk-shaped drive magnet 2 arranged on the rotor, and a four-phase drive coil 3 opposed to this drive magnetic pole 2a arranged on the stator. And constitute the motor section.

In addition, a ring-shaped member arranged on the outer periphery of the drive magnet 2
A frequency generator for rotation speed detection, which includes a 32 pole FG magnetic pole 4a formed on the FG magnet 4 and an FC head 5 which is a magnetoelectric conversion element for generating a rotation speed detection signal facing the FG magnetic pole 4a arranged on this stator. (Hereinafter abbreviated as FG),
Also, a single-pole PG magnetic pole 6a formed on the PG magnet 6 arranged near the outer periphery of the rotor, and a PG head 7 which is a magnetoelectric conversion element for generating a rotational position detection signal arranged on the stator.
Pulse generator for detecting rotational position with and (hereinafter abbreviated as PG)
Are configured.

Then, with the rotation of the rotor, the PG head 7 shows the rotation angle of the PG magnetic pole 6a facing the PG head 7 once for each rotation of the rotor, as shown in FIG. 2 (A). Such a PG output a is generated, and this PG output a is supplied to the waveform shaping circuit 8a as shown in FIG. The waveform shaping circuit 8a waveform-shapes the PG output a into an index signal c as shown in FIG. 2 (C), and the index signal c is as shown in FIG. 10 (A).
11 and a constant speed / constant phase control circuit 12.

On the other hand, the FG head 5 produces an FG output b as shown in FIG. 2 (B) having a frequency proportional to the rotation speed of 16 cycles per revolution of the rotor. It is supplied to the waveform shaping circuit 8b as shown in FIG.
In the waveform shaping circuit 8b, the FG output b is shaped into a rectangular wave as shown in FIG. 2 (D) and becomes an FG signal d. The FG signal d is confirmed to start as shown in FIG. 10 (A). Circuit 10,
It is supplied to the FG frequency dividing circuit 11 and the constant speed / constant phase control circuit 12.

When this rotor is stopped, the switch SW1 is closed and the switch SW2 is opened by the action of this start confirmation circuit 10,
The drive signal e-2 generated by the oscillation starting circuit 69 is supplied to the brushless motor drive circuit 13. Based on the drive signal e-2, the brushless motor drive circuit 13 causes the
The drive magnet 2 is rotationally driven by switching and supplying a drive current to the phase drive coil 3.

Then, based on the FG signal d, it is confirmed that the rotor has reached a predetermined number of revolutions by the action of the start confirmation circuit 10, and the switch SW1 is opened and the switch SW2 is closed, whereby the FG frequency divider circuit The output of 11 is supplied to this brushless motor drive circuit 13. In the FG frequency dividing circuit 11, the FG signal d is frequency-divided at a predetermined frequency division ratio (1/2 in this example), and is set by the index signal c to become position information in the rotation direction. Figure 2 (E)
The drive signal e-1 as shown in is generated. Based on this drive signal e-1, in the brushless motor drive circuit 13, four-phase phase current signals f-1, g- as shown in FIGS. 2 (F), (G), (H), and (I). 1, h−1, i−1 are created, and by switching and flowing the drive current through the four-phase drive coil 3, the drive magnet 2 and thus the rotor are rotationally driven.

Further, in the constant speed / constant phase control circuit 12, a constant speed / constant phase control signal which is a signal for controlling the rotor to a constant speed / constant phase is generated based on the FG signal d and the index signal c. It is supplied to the brushless motor drive circuit 13. In this brushless motor drive circuit 13,
Based on the constant speed / constant phase control signal, the drive coil 3
By adjusting the drive current flowing through the motor, a loop for negatively feeding back the speed and the phase is formed in the motor as described above, so that the rotor is controlled to the constant speed / constant phase.

The above is a description of the operation of the conventional sensorless brushless motor 61 during steady rotation. Next, the operation of the motor 61 during startup will be described in more detail with reference to FIG. 10 (B) and FIG. To do.

The period Td of the drive signal e-1 output from the FG frequency divider circuit 11 at the time of steady rotation has substantially the same value as shown in FIG. The period Td of the drive signal e-2 output from the oscillation starting circuit 69 gradually changes from a large value to a small value as shown in FIG.

As shown in FIG. 10 (B), the oscillation starting circuit 69 is composed of a time table value storage circuit 16, a time table value reading circuit 17, a time table value / time data conversion circuit 19, a drive signal generating circuit 20, and the like. ing. The timetable value storage circuit 16 stores a timetable value which is standard start-up data when the motor 61 is started. This timetable value is obtained when the rotor is started by the rotor start-up torque characteristic which is the difference between the start-up torque characteristic of the motor 61 alone and the start-up load torque characteristic of the load driven by the motor 61. Is the standard data of the period Td of the drive signal e-2 with respect to the time from the start of activation to the reaching of a predetermined rotation speed. This data is converted into, for example, digital data, and each is from the start of activation. ROM with addresses in time order
Remembered in.

Then, at start-up, this timetable value is sequentially read by the timetable value reading circuit 17 in the order of the addresses and supplied to the timetable value / time data conversion circuit 19. In this timetable value / time data conversion circuit 19, this timetable value is converted into time data representing the cycle Td at the time of startup, and this time data is supplied to the drive signal generation circuit 20. In the drive signal generation circuit 20, the drive signal e-2 whose period Td changes according to the rising data is generated by the time data as shown in FIG. 3 (A). Based on the drive signal e-2 having the predetermined rotor start-up period Td, the brushless motor drive circuit 13
Four-phase phase current signals f-2, g-2, h-2, i-2 as shown in FIGS. (B), (C), (D), and (E) are generated, and as described above, The rotor is activated.

(Problems to be Solved by the Invention) In the conventional sensorless type brushless motor 61 having the above-described configuration, at the time of starting, the rotational speed of the rotor generally follows the drive signal e-2 at the time of starting. However, this startup may fail due to variations in the startup torque characteristics of the motor 61 alone and the load driven by the motor 61.

FIG. 11 is a graph for explaining changes in the rotor starting characteristics with respect to changes in the cycle Td of the drive signal of the motor in FIG.
The vertical axis represents the rotor rotation speed, and the horizontal axis represents time.

As shown in the figure, the drive signal e- at the time of start-up relative to the above-mentioned rotor start-up torque characteristic of the motor 61 is given.
If the period Td of 2 is too small, the rotor cannot stop following the drive signal e-2 and stops.
If is too large, the overshoot becomes large and the phases are out of phase, causing the machine to stop.

The above-mentioned timetable value of the motor 61 is a standard type, but it is relatively the same as that of FIG. 11 due to variations in the starting torque characteristics of the motor 61 and the load driven by the motor 61. Since a situation may occur, there is a problem that the startup may fail due to variations in the startup torque characteristics of the motor 61 alone and the load driven by the motor 61.

The present invention has been made in view of the above points, and an object thereof is to provide a highly reliable sensorless brushless motor that does not fail in starting.

(Means for Solving the Problems) A sensorless brushless motor according to the present invention is a motor unit including a multi-pole drive magnetic pole provided in a rotor and a multi-phase drive coil disposed opposite the drive magnetic pole provided in a stator. And a rotation speed and / or position detection means for generating a rotation speed and / or position detection signal corresponding to the rotation speed and / or position of the rotor arranged in the motor section, and the rotation speed and / or position detection Drive signal generating means for generating a drive signal of a pulse which becomes drive current switching information according to the signal, and a brushless motor for rotationally driving the rotor by switching the drive current to the multiphase drive coils based on the drive signal. At the time of starting the drive circuit and the motor, a predetermined period whose cycle changes with respect to the time from the start of starting the rotor until the predetermined rotation speed is reached, An oscillation starter circuit that outputs a drive signal having a rotor start-up cycle, and the drive signal from the oscillator circuit is supplied to the brushless motor drive circuit at the time of start-up, and the drive is performed after the predetermined rotation speed is reached. In a sensorless brushless motor comprising a start confirmation circuit for switching and supplying the drive signal from the signal generating means to the brushless motor drive circuit, in the oscillation start circuit, the start torque generated by this motor and / or this motor is The starting torque and the load torque are detected according to a starting torque for detecting a substitute characteristic value representing a fluctuation of the load torque at the time of starting the driven load and converting it into an electric signal and / or a detection signal of the load torque fluctuation detecting means. Of the rotor start-up torque characteristic based on the difference between the rotor start-up frequency and the rotor start-up frequency characteristic based on the rotor start-up cycle. Is obtained by configured with a starting characteristic adjusting means for adjusting the rotor start-up characteristics determined.

Also, in the sensorless brushless motor of the present invention, in the above motor, the oscillation starting circuit starts the starting when the detection signal of the starting torque and / or load torque fluctuation detecting means exceeds a preset allowable range. It is configured to include an abnormal signal output unit that outputs an abnormal signal while stopping.

Further, in the sensorless brushless motor of the present invention, in the above motor, the starting characteristic adjusting means is a rotor start-up cycle correcting means for correcting the rotor start-up cycle.

In the sensorless brushless motor of the present invention, in the above motor, the starting characteristic adjusting means is a starting current controlling means for controlling the driving current at the time of starting.

(Embodiment) The sensorless brushless motor of the present invention is a start-up torque fluctuation detection in which the oscillation start-up circuit 69 described above detects a substitute characteristic value representing a change in start-up torque generated by this motor and converts it into an electric signal. Means and / or the starting torque and the load torque according to the output of the load torque fluctuation detecting means for detecting the substitute characteristic value representing the fluctuation of the load torque at the time of starting the load driven by this motor and converting it into an electric signal. The start-up characteristic adjusting means for adjusting the rotor start-up characteristic of the motor, which is determined by the rotor start-up torque characteristic based on the difference between the rotor start-up frequency and the rotor start-up frequency characteristic based on the rotor start-up cycle described above, is added. Is surely performed.

When the starting torque fluctuation detecting means detects the power supply voltage and the ambient temperature, when the load torque fluctuation detecting means detects the cumulative number of times of starting and the rotor starting time,
Each of the execution characteristics adjusting means is a rotor start-up cycle correcting means for correcting the rotor start-up cycle Td and a start-up current control means for controlling the drive current from the brushless motor / motor drive circuit. An example will be described below.

The first embodiment of the present invention is a case where the starting torque fluctuation detecting means detects the power supply voltage which is a factor that changes the starting torque as a substitute characteristic instead of the starting torque which is difficult to be directly detected. The starting characteristic adjusting means is the rotor start-up period correcting means.

FIG. 1 is a block diagram showing first to fourth embodiments of a sensorless type brushless motor of the present invention. FIG. 1 (A) is an overall view, and FIG. 1 (B) is the oscillation start of FIG. 1 (A). It is a detailed view of a circuit.

As shown in the drawing, the motors of the first to fourth embodiments of the present invention
1, 21, 31, 41 are the oscillation starting circuits 9, 29, 39, 49 for converting the time table value reading circuit 17 and the time table value / time data in the oscillation starting circuit 69 of the motor 61 of the conventional example described above. A starting torque and / or load torque fluctuation detecting means 14, 24, 34, 44, a voltage comparing circuit 15, and a time table value multiplying circuit 18 are added to the circuit 19. Therefore, the same parts as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

The oscillation starting circuit 9 in the sensorless brushless motor 1 according to the first embodiment of the present invention detects fluctuations in the power supply voltage, and corrects the above-mentioned timetable value accordingly. Alternatively, the load torque fluctuation detecting means is the power supply voltage fluctuation detecting circuit 14 in this case.

When the permissible fluctuation range of the power supply voltage of the motor 1 is, for example, the rated power supply voltage ± 10%, the starting torque generated by the motor 1 also changes ± 10%. Therefore, the fluctuation of the power supply voltage is caused by the power supply voltage fluctuation detection circuit 14 Detect with. The power supply voltage fluctuation detection circuit 14 outputs a power supply voltage detection signal of a voltage proportional to the power supply voltage due to a voltage drop of a resistor connected between the power supply line and the ground. Is supplied to the voltage comparison circuit 15. In the voltage comparison circuit 15, the power supply voltage detection signal is compared with a predetermined reference voltage to be converted into a correction coefficient linked to the power supply voltage. This correction coefficient is, for example, 1.0 when the power supply voltage is equal to the rated voltage, and the rated voltage +1
0.9 at 0%, 1.1 at rated voltage -10%,
It is supplied to the time table value multiplication circuit 18.

In the time table value multiplication circuit 18, the correction coefficient is multiplied by the time table value from the time table value storage circuit 16 and the time table value reading circuit 17, and this time table value is multiplied. Correction for fluctuations in power supply voltage is performed. Based on the corrected time table value, the time table value / time data conversion circuit 19 and the drive signal generation circuit 20 generate the drive signal e-2 at the start-up, as described above. The above-mentioned predetermined rotor start-up period Td of the drive signal e-2 at the time of starting and the frequency f which is the reciprocal of this period Td are
As described above, since it is linked to the fluctuation of the power supply voltage, even if the power supply voltage fluctuates, the rotor follows the start-up frequency f to increase its rotation speed, and reliable start-up is performed.

FIG. 4 is a graph for explaining the correction of the rise of the frequency f of the drive signal in the motor of the first embodiment shown in FIG. 1 against the fluctuation of the power supply voltage, the vertical axis being the frequency f of the drive signal and the horizontal axis being the horizontal axis. Is time.

As shown in the figure, when there is no fluctuation in the power supply voltage and the rated voltage is maintained, the rotor of the motor 1 starts without any problems according to the standard start-up characteristic of the frequency f based on the timetable value described above, and the power supply voltage is + 10%. In case of, this motor 1
Since the starting torque generated by is increased by 10% and the start-up of this rotor is accelerated, the start-up characteristic of this frequency f is also corrected 10% earlier to match the start-up curve of this rotor. Similarly, when the power supply voltage is -10%, the rising characteristic of this frequency f is also corrected 10% later,
Since the rising curve of the rotor is matched, the above-mentioned reliable start-up is performed.

Next, the case where the starting torque fluctuation detecting means detects the ambient temperature which is a factor that changes the starting torque as a substitute characteristic, and the case where the starting characteristic adjusting means is the rotor startup cycle correcting means. A second embodiment of the present invention will be described.

Oscillation starting circuit in the motor 21 of the second embodiment of the present invention
29 is for detecting the fluctuation of the ambient temperature, thereby correcting the timetable value described above, the starting torque and / or load torque fluctuation detection means is the ambient temperature fluctuation detection circuit 24 in this case, Since this ambient temperature fluctuation detecting circuit 24 is different from that of the first embodiment, the description of the same parts as those of the first embodiment will be omitted.

The permissible fluctuation range of the ambient temperature of the motor 21 is, for example, 20 ° C.
At ± 20 ° C, the starting torque generated by this motor 21 is
When the material of the driving magnet 2 is Nd-Fe-B and the material of the driving coil 3 is copper wire, the temperature coefficient of these materials causes Since the starting torque at 0 ° C. is 1 and it is about −20% at 40 ° C., the fluctuation of the ambient temperature is detected by the ambient temperature fluctuation detecting circuit 24.

The ambient temperature detection circuit 24 outputs an ambient temperature detection signal having a voltage substantially proportional to the ambient temperature, for example, by the terminal voltage of a thermistor connected between the power supply line and the ground. Is converted into a correction coefficient linked to the ambient temperature in the voltage comparison circuit 15 as in the case of the first embodiment. This correction coefficient is, for example, 1.0 when the ambient temperature is 20 ° C., 0.9 when the ambient temperature is 0 ° C., 1.1 when the ambient temperature is 20 ° C., and is supplied to the time table value multiplication circuit 18, and the first conventional example described above. In the same manner as in the above case, the time table value is corrected for this ambient temperature fluctuation.

Then, as in the case of the first embodiment described above, the predetermined rotor start-up period Td and the frequency f of the drive signal e-2 at the time of starting are linked to the fluctuation of the ambient temperature as described above. Therefore, even if the ambient temperature fluctuates, the rotor follows the start-up frequency f to increase its rotation speed, and reliable starting is performed.

FIG. 5 is a graph for explaining the correction of the rising characteristic of the frequency f of the drive signal in the motor of the second embodiment shown in FIG. 1 against the ambient temperature fluctuation.

As shown in the figure, when the ambient temperature is 20 ° C., which is the standard temperature, the rotor of the motor 21 starts without any problems according to the standard start-up characteristic of the frequency f based on the above-mentioned time table value, and the ambient temperature becomes 0. In the case of ° C, the starting torque generated by the motor 21 is increased by about 10% and the start-up of the rotor is accelerated, so that the start-up characteristic of the frequency f is also increased.
Correct 10% early to match the rising curve of this rotor. Similarly, when the ambient temperature is 40 ° C., the rising characteristic of the frequency f is also corrected 10% later to match the rising curve of the rotor.
The above-mentioned reliable activation is performed.

Next, the load torque fluctuation detecting means detects the cumulative number of times of starting representing the fluctuation of the load torque as a substitute characteristic instead of the load torque which is difficult to directly detect, and the starting characteristic adjusting means A third embodiment of the present invention, which is the case of the rotor start-up period correction means, will be described.

Oscillation starting circuit in the motor 31 of the third embodiment of the present invention
39 detects the change in the cumulative number of times of start-up and corrects the above-mentioned timetable value accordingly, so that the starting torque and / or load torque fluctuation detecting means is the cumulative number-of-starts detection circuit 34 in this case. Since the cumulative number-of-starts detection circuit 34 is different from that of the first embodiment, the description of the same parts as those of the first embodiment will be omitted.

In the case where the motor 31 is, for example, a spindle motor of a small hard disk drive, the magnetic head for information recording / reproduction of the small hard disk drive floats above the surface of the hard disk during steady rotation, and when starting / stopping In the case of the method of contacting the surface of the hard disk, the magnetic head polishes the surface of the hard disk each time this start and stop is repeated, and the surface becomes gradually mirrored to increase the friction resistance. The fluctuation of the load torque is roughly proportional to the cumulative number of startups. If the allowable range of the cumulative number of starts of the motor 31 is, for example, 20,000 times, the increase of the load torque at the time of starting the cumulative number of times of 20,000 is, for example, +20 of the initial value.
%, Fluctuations in load torque at the time of starting are detected by detecting the total number of times of starting by the total number of times of starting detecting circuit 34.

The cumulative number-of-starts detection circuit 34 is composed of, for example, a one-chip microcomputer circuit including a ROM and a RAM, stores the cumulative number of starts from the beginning, and detects a cumulative number-of-starts detection signal of a voltage proportional to the cumulative number of starts. This cumulative activation frequency detection signal is converted into a correction coefficient linked to this cumulative activation frequency in the voltage comparison circuit 15 as in the case of the first embodiment described above. This correction coefficient is, for example, 0 if this cumulative number of starts is the first.
When it is 9, 10,000 times, it is 1.0, and when it is 20,000 times, it becomes 1.1, and it is supplied to the time table value multiplication circuit 18,
As in the case of the conventional example, the timetable value is corrected with respect to this cumulative number of times of activation.

Then, as in the case of the first embodiment described above, the predetermined rotor start-up period Td and frequency f of the drive signal e-2 at the time of starting are linked to the change in the cumulative number of starting times as described above. Therefore, even if the cumulative number of starts changes and the load torque changes, the rotor follows the start-up frequency f to increase its rotation speed, and reliable start is performed.

FIG. 6 is a graph for explaining the correction of the rise characteristic of the frequency f of the drive signal in the motor of the third embodiment of FIG.

As shown in the figure, when the cumulative number of starts is the first time (first time), the load torque is the smallest and the rotor of the motor 31 rises fastest. It is corrected to the eyes and matched with the rising curve of this rotor. Similarly, when the total number of startups is 20,000, this load torque is the largest and the startup of this rotor is delayed, so the startup characteristics of this frequency f are also corrected to 10% late, and the startup curve of this rotor is corrected. Since the above is matched, the above-mentioned reliable activation is performed.

Next, the starting torque and load torque fluctuation detecting means,
A fourth embodiment of the present invention, which is a case where the rotor starting time representing variations of the starting torque and the load torque is detected as a substitute characteristic, and the starting characteristic adjusting means is the rotor start-up period correcting means. Will be described.

Oscillation start-up circuit in the motor 41 of the fourth embodiment of the present invention
49 detects the fluctuation of the rotor starting time, which is the time until the rotor reaches a predetermined number of revolutions, and corrects the above-mentioned timetable value by this, and therefore the starting torque and / or load torque fluctuation In this case, the detecting means is the rotor starting time detecting circuit 44. Since this rotor starting time detecting circuit 44 is different from the case of the first embodiment described above, the same parts as those of the first embodiment will not be described. The description is omitted.

If the motor 41 is, for example, a spindle motor of a small hard disk drive, the predetermined number of times is 500 rpm.
In this case, the rotor start time detection circuit 44 detects the time from when the rotor starts to reach 500 rpm as the rotor start time.

When the permissible range of the rotor starting time, which represents the fluctuation of the starting torque generated by the motor 41 and the load torque at the time of starting the load to be driven, is, for example, 1 to 2 seconds, the starting torque within the permissible range is maximum. In contrast to the case where the rotor starting time is 1 second with the minimum load torque, the difference between the two torques when the starting torque is the minimum and the load torque is maximum with the rotor starting time is 2 seconds. If the fluctuation range is, for example, 20%, the fluctuation of the rotor starting torque is detected by detecting the rotor starting time by the rotor starting time detecting circuit 44.

The rotor startup time detection circuit 44 is composed of, for example, a counter circuit provided with a counter that is reset by a startup signal, and outputs a rotor startup time detection signal having a voltage proportional to the rotor startup time. The detection signal is converted into a correction coefficient linked to the rotor starting time in the comparison circuit 15 as in the case of the first embodiment. This correction coefficient is, for example, 0 in the first start-up trial and when the rotor start-up time is 1 second.
It is 1.0 for 9 and 1.5 seconds, and 1.1 for 2 seconds, and is supplied to the time table value multiplication circuit 18, and the time table value with respect to this rotor starting time is supplied to the time table value multiplication circuit 18, as in the case of the first conventional example. Correction is performed.

Then, as in the case of the first embodiment described above, the predetermined rotor start-up period Td and frequency f of the drive signal e-2 at the time of startup are linked to this rotor startup time as described above. Therefore, even if the starting torque and the load torque described above fluctuate and the rotor starting time fluctuates, the rotor follows the start-up frequency f to increase its rotation speed, and reliable starting is performed.

FIG. 7 is a graph for explaining the correction of the rising characteristic of the frequency f of the drive signal in the motor of the fourth embodiment of FIG.

As shown in the figure, in the case of the first start-up trial, the start-up characteristic of the frequency f is tried 10% earlier, and when the rotor start-up time happens to be 1 second, the start-up is performed as it is.
If the rotor start-up time is longer than this, the start-up is temporarily stopped and the start-up confirmation circuit 10 sets the FG
After confirming that the rotor is completely stopped by the signal d, the start-up is started again. At this time, if the rotor starting time is 1.5 seconds from the rotor starting time detected at the first trial, the rotor starting time is 2 seconds according to the standard start-up characteristic of the frequency f.
In the case of seconds, the rising characteristic of the frequency f is corrected 10% later to match the rising curve of the rotor, so that the above-mentioned reliable starting is performed. In the above-described first to fourth embodiments of the present invention, as described above, an example in which the timetable value is corrected according to the single detection signal of the starting torque and / or load torque fluctuation detecting means will be described. However, it goes without saying that this correction may be performed in accordance with the detection signals of two or more of the starting torque and / or load torque fluctuation detecting means.

Further, in the first to fourth embodiments, when the detection signal of the starting torque and / or load torque fluctuation detecting means exceeds the above-mentioned preset allowable range in the voltage comparison of the voltage comparison circuit 15, For example, in the case of an abnormal state such as an overload, if there is a risk that the motor and the device driven by the motor will fail if they are started as they are, an abnormal signal (for example, 0) output from the voltage comparison circuit 15 causes The time table value multiplication circuit 18 stops the activation by setting the time table value to 0, and outputs the abnormal signal to the outside as an alarm by the abnormal output terminal 15a output from the voltage comparison circuit 15. I can do it.

Next, a description will be given of a fifth embodiment of the present invention, in which the starting torque fluctuation detecting means detects the power supply voltage and the starting characteristic adjusting means is the starting current control means.

FIG. 8 is a block diagram showing a fifth embodiment of the sensorless type brushless motor of the present invention, FIG.
FIG. 2B is a detailed diagram of the oscillation starting circuit of FIG.

As shown in the figure, the motor 51 of the fifth embodiment of the present invention is
The oscillation starting circuit 59 is the same as the motor 1 of the first embodiment.
The function of the time table value multiplication circuit 18 of the oscillation starting circuit 9 is replaced by a starting current control circuit 58.
The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

This oscillation starting circuit 59 in the motor 51 of the fifth embodiment of the present invention is activated at the time of starting according to the power supply voltage detection signal of the power supply voltage fluctuation detecting circuit 14 which is the above-mentioned starting torque and / or load torque fluctuation detecting means. The starting current, which is the driving current flowing through the driving coil 3, is corrected.

As described above, the correction coefficient linked to the power supply voltage output from the voltage comparison circuit 15 is 1.0 when the power supply voltage is the rated voltage, 0.9 when the power supply voltage is + 10%, and -10% when the rated voltage is -10%. In case of 1.1, the starting current control circuit 5
Supplied to 8.

In this start-up current control circuit 58, the standard rotor start-up period Td and frequency f based on the above-mentioned time table value are used.
The start-up drive signal e-2 controls the start-up current output from the brushless motor drive circuit 13 according to the correction coefficient. Therefore, since the starting current is linked to the fluctuation of the power source voltage as described above, even if the power source voltage fluctuates, the rotor follows the start-up frequency f to increase its rotation speed, A reliable start is performed.

FIG. 9 is a graph for explaining the correction of the power supply voltage variation of the rotor starting characteristic in the motor of FIG. 8, where the vertical axis is the rotor rotation speed and the horizontal axis is time.

As shown in the figure, when there is no fluctuation in the power supply voltage and the rated voltage is maintained, the above-mentioned timetable value is matched with the above-mentioned rise curve of the rotor due to the rated starting torque of the motor 51. According to the characteristics, this rotor will start without any problems, and if the power supply voltage is + 10%, the starting torque generated by this motor 51 will remain unchanged.
Since it increases by 10%, the starting current control circuit 58 reduces the starting current by 10% based on the above-mentioned correction coefficient to match the standard rotor startup characteristic. Similarly, when the power supply voltage is -10%, the start-up current is increased by 10% so that the start-up current is controlled to match the standard rotor start-up characteristic, and the above-mentioned reliable start-up is performed.

The fifth embodiment described above is a case where the starting current control circuit 58 controls the starting current by linking to the fluctuation of the power supply voltage, but it may be combined with the above other starting torque and / or load torque fluctuation detection fluctuation. Can be done.

Further, each of the above-described embodiments describes an example of a so-called FG count time sensorless brushless motor that obtains the switching timing of the drive current by dividing the FG signal from the FG by the FG divider circuit 11. However, the present invention is not limited to this, and the aforesaid FG, PG, FG frequency divider circuit 11 and the like are omitted, and this counter electromotive force waveform induced in the drive coil 3 by the rotation of the drive electromagnetic 2a is used to drive this drive. The present invention can also be applied to a sensorless brushless motor having a so-called back electromotive force waveform detection time, which is used to obtain the current switching timing.

(Effects of the Invention) The sensorless brushless motor of the present invention having the above-described configuration is reliably started in a short time without starting failure, so that the reliability of the motor is improved.

Further, when the starting torque and / or the load torque is abnormal, this starting is stopped and an abnormal signal is output. Therefore, it is possible to quickly perform the abnormal processing.

Further, since the above-described functions are achieved by adding a small number of elements to the conventional configuration, the function-to-cost ratio is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first to fourth embodiments of the sensorless brushless motor of the present invention, and FIG. 2 is a waveform for explaining the operation of the motors of FIGS. 1, 8 and 10 during steady rotation. FIG. 3 is a waveform diagram for explaining the operation of the motor of FIGS. 1, 8 and 10 at the time of starting, and FIG. 4 is the frequency f of the drive signal in the motor of the first embodiment of FIG. FIG. 5 is a graph for explaining the correction of the start-up characteristic with respect to the fluctuation of the power supply voltage, and FIG. 5 is a graph for explaining the correction of the start-up characteristic of the frequency f of the drive signal in the motor of the second embodiment of FIG. FIG. 6 is a graph for explaining the correction of the rising characteristic of the frequency f of the drive signal in the motor of the third embodiment of FIG.
The frequency f of the drive signal in the motor of the fourth embodiment in the figure
FIG. 8 is a graph for explaining the correction of the start-up characteristics of the rotor against fluctuations in the starting time of the rotor, FIG. 8 is a block diagram showing the fifth embodiment of the sensorless brushless motor of the present invention, and FIG. 9 is the starting of the rotor in the motor of FIG. FIG. 10 is a graph for explaining the correction of the characteristic to the power supply voltage fluctuation, FIG. 10 is a block diagram showing an example of a conventional sensorless brushless motor, and FIG.
The figure is a graph for explaining changes in the rotor starting characteristics with respect to changes in the cycle Td of the drive signal of the motor shown in FIG. 1,21,31,41,51,61 …… Sensorless brushless motor, 2a …… Drive magnetic pole, 3 …… Drive coil, 4a …… FG magnetic pole, 5 …… FG head, 6a …… PG magnetic pole, 7 ... ... PG head,
9,29,39,49,59,69 …… Oscillation start circuit, 10 …… Start confirmation circuit, 11 …… FG divider circuit, 13 …… Brushless motor drive circuit, 14 …… Power supply voltage fluctuation detection circuit (start Torque and / or load torque fluctuation detecting means), 24 ... Ambient temperature fluctuation detecting circuit (starting torque and / or load torque fluctuation detecting means), 34 ... Cumulative starting frequency detection circuit (starting torque and / or
Or load torque fluctuation detecting means), 44 ... Rotor starting time detecting circuit (starting torque and / or load torque fluctuation detecting means), 15 ... Voltage comparison circuit (abnormal signal output means), 15a
…… Abnormal signal output terminal (abnormal signal output means), 18 …… Time table value multiplication circuit (rotor start cycle correction means, start characteristic adjustment means), 58 …… Starting current control circuit (starting current control means, starting characteristics) Adjusting means).

Claims (4)

[Claims] 1. A motor unit comprising a multi-pole drive magnetic pole provided in a rotor and a multi-phase drive coil arranged opposite to the drive magnetic pole provided in a stator, and rotation of the rotor arranged in the motor unit. Rotational speed and / or position detection means for generating a rotational speed and / or position detection signal according to speed and / or position, and driving of pulses serving as drive current switching information according to the rotational speed and / or position detection signal Drive signal generating means for generating a signal, a brushless motor drive circuit for rotationally driving the rotor by switching drive currents to the multi-phase drive coils based on the drive signal, and a rotor of the rotor when the motor is started. An oscillation start circuit that outputs a drive signal having a predetermined rotor start-up cycle, the cycle of which has changed with respect to the time from the start of start-up to reaching a predetermined rotation speed, At the time of starting, the drive signal from the oscillation starting circuit is supplied to the brushless motor drive circuit, and after reaching the predetermined rotation speed, the drive signal from the drive signal generating means is supplied to the brushless motor drive circuit. In a sensorless brushless motor including a start confirmation circuit that is switched and supplied, the oscillation start circuit is a substitute characteristic that represents a change in a start torque generated by the motor and / or a load torque at the time of starting a load driven by the motor. Depending on the detection signal of the starting torque and / or the load torque fluctuation detecting means for detecting the value and converting it into an electric signal,
A starting characteristic adjusting means for adjusting a rotor starting characteristic determined by a rotor starting torque characteristic based on a difference between the starting torque and the load torque and a rotor starting frequency characteristic based on the rotor starting cycle. A sensorless brushless motor. 2. The oscillation start-up circuit stops the start-up and outputs an abnormal signal when the detection signal of the start-up torque and / or load torque fluctuation detection means exceeds a preset allowable range. The sensorless brushless motor according to claim 1, further comprising signal output means. 3. The sensorless brushless motor according to claim 1, wherein the starting characteristic adjusting means is a rotor start-up cycle correcting means for correcting the rotor start-up cycle. . 4. The sensorless brushless motor according to claim 1, wherein the starting characteristic adjusting means is a starting current controlling means for controlling the drive current at the time of starting. .