JP3107384B2 - Drive device for brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a drive device for a brushless motor having a permanent magnet type rotor.

(Prior Art) For example, as a drive device for a brushless motor for driving a rotary head of a VTR, a magnetic sensor such as a Hall element, which is a position detecting element for detecting the position of a pole of a rotor in a stator portion, is electrically driven. A plurality of logic converters are arranged at intervals of 60 degrees or 120 degrees, and a logic conversion unit that determines the timing of energizing the stator coil of the stator based on the position detection signals from these Hall elements is provided. In general, an inverter circuit is provided as a drive circuit that energizes the stator coil according to the resulting commutation signal.

In this type of brushless motor, a frequency power generation conductor pattern is formed on a stator portion, and a frequency power generation permanent magnet is attached to the rotor portion corresponding to the frequency power generation conductor pattern, and the frequency generation permanent magnet is mounted in accordance with the rotation of the rotor. A frequency generator that obtains a frequency power generation signal from the frequency power generation conductor pattern is provided, and the speed is controlled based on the frequency power generation signal obtained from the frequency power generation conductor pattern of the frequency power generator. In addition, a phase detection signal generator is provided in which a phase detection signal permanent magnet is attached to the rotor portion, and a phase detection signal magnetic sensor is attached to the stator portion to obtain a phase detection signal of a specific phase of the rotor. Based on the phase detection signal obtained from the sensor, control such as cueing of the tape and switching of the head is performed.

(Problems to be Solved by the Invention) However, in the above-described conventional configuration, for example, in the case of a three-phase brushless motor, it is necessary to use three Hall elements as a magnetic sensor, and furthermore, the number of wirings is reduced. Requires three power lines for the stator coil, two power lines for the Hall elements, and two output lines for each Hall element, for a total of eleven. For this reason, the structure inside the brushless motor is complicated, and there is a problem that the size and weight are increased, and the cost is generally high.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brushless motor driving device that can obtain a commutation signal without using a magnetic sensor that directly detects the position of a pole of a rotor. .

[Structure of the Invention] (Means for Solving the Problems) A brushless motor driving device according to the present invention includes a permanent magnet type rotor having a plurality of field magnetic poles and a stator having a plurality of phase stator coils. In the brushless motor, an oscillating means for generating a signal for synchronous rotation, a frequency signal generating means for generating a frequency signal related to the number of magnetic poles in accordance with the rotation of the rotor, and a magnetic signal in response to the rotation of the rotor Phase detection signal generation means for generating a phase detection signal corresponding to the phase, and a commutation signal generation means for generating a commutation signal supplied to the stator coil based on the synchronous rotation signal and the frequency signal, At the time of startup, the commutation signal is generated based on the synchronous rotation signal, and the commutation signal is generated while the commutation signal is generated based on the frequency signal. A commutation signal generating means for correcting the commutation phase of the commutation phase by the phase detection signal; It is characterized by having it.

Further, the brushless motor driving device of the present invention is provided with an oscillating means for generating a signal for synchronous rotation, generates a frequency signal related to the number of magnetic poles and generates a phase detection signal of a specific phase according to the rotation of the rotor. A signal generating means is provided, and a drive circuit for sequentially energizing the plural-phase stator coils is provided, and a given signal is counted to generate a commutation signal. A switching circuit for switching the commutation signal generation circuit to a synchronous rotation signal from the oscillating means at the start-up, and a frequency signal from the signal generation means. The circuit is configured such that after switching to a frequency signal, the circuit is reset every time a phase detection signal is supplied from the signal generating means to correct a commutation phase. A signal generating means, a permanent magnet consisting of a magnetized portion for frequency signals formed in multiple poles and a magnetized portion for phase detection signal formed in the opposite polarity, and each magnetized portion of this permanent magnet. And a magnetic sensor for generating positive and negative output signals in response.

In addition, it is preferable to obtain speed detection signals at equal intervals in accordance with an output signal from the magnetized portion for the frequency signal of the permanent magnet in the magnetic sensor.

The signal generating means is formed by forming a frequency signal magnetized portion having N poles and S poles formed in multiple poles, and predetermined S poles and N poles having a higher magnetized level than others. A permanent magnet comprising a magnetized part for phase detection signal, a magnetic sensor for generating positive and negative output signals according to each magnetized part of the permanent magnet, and a zero-cross signal at the zero-cross point when the output signal of the magnetic sensor is zero. And a zero-cross detection circuit that generates

Further, the external control unit controls the speed of a motor drive unit including an oscillating unit, a signal generation unit, a drive circuit, a commutation signal generation circuit, and a switching circuit. On the other hand, it is preferable that the speed detection signal including the frequency signal and the phase detection signal is transmitted by one signal line.

Further, between the motor drive unit and the external control unit, a signal line for a speed detection signal, a command line for giving a speed command signal based on the speed detection signal from the signal line to the motor drive unit, It is preferable that the external control unit is connected to a power supply line for positive potential for supplying DC power to the motor control unit and a power supply line for ground.

(Operation) According to the brushless motor driving device of the present invention, the synchronous rotation signal from the oscillating means is given to the commutation signal generating circuit at the time of startup, and the brushless motor is started up as a synchronous motor via the driving circuit. Thereafter, the frequency signal from the signal generating means is supplied to the commutation signal generation circuit, the brushless motor continues to rotate as a synchronous motor via the drive circuit, and the commutation signal generation circuit receives the phase detection signal. The commutation phase is reset each time it is reset, so that the commutation phase becomes the predetermined phase.Therefore, after that, even if there is a load change, the brushless motor can be rotated stably without step-out. Become. Furthermore, the magnetizing part for the frequency signal and the magnetizing part for the phase detection in the permanent magnet are magnetized with different numbers of poles, so that the magnetizing of the permanent magnet is stabilized and the magnetizing accuracy is improved. In addition, the output signal of the magnetic sensor can be made sufficiently large, and the S / N ratio can be improved.

Further, when the speed detection signal is obtained from the magnetized portion for the frequency signal of the permanent magnet, the accuracy of the speed detection signal can be improved even if the levels of the N pole and the S pole are different.

When a zero-cross detection circuit is provided as a signal generation unit, there is no influence from the variation in magnetization of the permanent magnet.

Further, when the speed of the motor drive unit is controlled from the external control unit, the speed detection signal includes information of both the frequency signal and the phase detection signal, so that only one signal line is required. There are advantages.

In addition, when DC power is supplied from the external control unit to the motor drive unit, the connection between them is made up of a signal line, a command line, a positive potential power line, and a ground power line. There is an advantage that only four are required.

(Embodiment) Hereinafter, a first embodiment in which the present invention is applied to a drive motor for driving a rotary head of a VTR will be described with reference to FIGS. 1 to 4.

First, according to FIGS.
Will be described. Reference numeral 2 denotes a frame on which a printed wiring board 3 is mounted. Also, frame 2
, A stator 4 is fixed below the printed circuit board 3, and the stator 4 is configured by winding a plurality of phases, for example, three-phase stator coils 6 around a stator core 5. Further, a shaft 8 of a rotor 7 is inserted and supported in the center of the frame 2, and a short bottomed cylindrical yoke 9 is fixed to a lower end of the shaft 8.
A permanent magnet 10 is mounted on the rotor yoke 9 such that an inner peripheral surface thereof corresponds to an outer peripheral surface of the stator core 5. On the inner peripheral surface of the permanent magnet 10, a plurality of poles, for example, eight magnetic poles for the field, in which N poles and S poles alternate, are magnetized. Also, permanent magnet
As shown in FIG. 3, an N-pole frequency signal magnetizing portion 11 having a number of poles is magnetized on the outer peripheral surface of the pole 10 so as to have a large number of poles. The S-pole phase detection signal magnetizing section 12 is magnetized, and the total number of poles is set to 24 poles. And the printed wiring board 3
A magnetic sensor 13 made up of a Hall element is attached to the magnetized portions 11 and 12 in correspondence with the magnetized portions 11 and 12.

Referring now to FIG. The output terminal of the magnetic sensor 13 is connected to the input terminal of the signal generation circuit 15 via the waveform shaping circuit 14, thereby forming the signal generation means 16. In this case, the signal generation circuit 15 outputs a pulse signal FGa serving as a frequency signal, a pulse signal PGa serving as a phase detection signal, and a speed detection pulse VG serving as a speed detection signal in accordance with an input signal as described later. I have. The two output terminals of the signal generating circuit 15 are connected to the two input terminals Ia and Ib of the switching circuit 17, respectively. Reference numeral 18 denotes an oscillating circuit as oscillating means having an oscillating capacitor 18a, and its output terminal is connected to the input terminal Ic of the switching circuit 17. The oscillation circuit 18 starts an oscillation operation when a motor switch (not shown) is turned on, and outputs a pulse signal PO as a synchronous rotation signal. Further, the switching circuit 17
Is connected to an input terminal of a commutation signal generation circuit 19 composed of a pulse counter, a logic circuit and the like. 20
Is a drive circuit, which is configured to include an inverter circuit formed by bridging six transistors as switching elements, the input terminal of which is connected to the output terminal of the commutation signal generation circuit 19. . And the drive circuit
The output terminals 20 are connected to the three-phase stator coils 6 of the brushless motor 1.

The various elements and circuits denoted by reference numerals 13 to 20 are formed on the printed wiring board 3 and provided with a motor driving unit.
An external control unit 22 for controlling speed and the like from the outside is provided for this. And
The motor drive unit 21 includes a power terminal 23 for a positive potential (12 V) of a DC power supply, a power terminal 24 for a ground (G), and a signal terminal.
25 and a command terminal 26, and the external control unit 22 has terminals 27 corresponding to these terminals 23 to 26.
And 30 are provided. Further, the terminals 23 to 26 and the terminals 27 to 30 are connected by lines 31 to 34, respectively. Accordingly, the DC power supply voltage of 12 V applied between the positive potential power supply terminal 27 and the ground power supply terminal 28 of the external control unit 22 is applied to the motor drive unit 21 via the positive potential power supply line 31 and the ground power supply line 32. Are supplied to the positive potential power supply terminal 23 and the ground power supply terminal 24, and are supplied to each element and circuit of the motor drive unit 21 therefrom.

Although the drive device shown in FIG. 1 is shown in a block diagram for each function, it is actually constituted mainly by a microcomputer.

Next, the operation of this embodiment will be described with reference to FIG.

When a motor switch (not shown) is turned on, the oscillation circuit 18 first oscillates at about 10 Hz to output a pulse signal PO. Thereby, the switching circuit 17 to be described later supplies the pulse signal PO to the commutation signal generation circuit 19. The commutation signal generation circuit 19 counts and logically processes the pulse signal PO and outputs the output signals φa, φb and φc as commutation signals as shown in FIGS. 4 (e), (f) and (g). Then, these are given to the drive circuit 20. The drive circuit 20 outputs these output signals φ
By turning on and off the transistors of the inverter circuit based on a, φb and φc, output voltages φ1, φ2 and φ3 are output and applied to the stator coil 6. As a result, the inverter circuit of the drive circuit 20 operates as a separately-excited inverter circuit and starts the brushless motor 1 as a synchronous motor. When the brushless motor 1 is started, the magnetized portions 11 and 12 of the permanent magnet 10 are also rotated together with the rotor 7 thereof, so that the magnetic sensor 13 generates an output signal as shown in FIG. . That is, the magnetic sensor 13 generates a positive (+) output signal FG when it corresponds to the frequency signal magnetizing unit 11 (N pole) and corresponds to the phase detection signal magnetizing unit 12 (S pole). Sometimes a negative (-) output signal
PG is generated, and this is supplied to the waveform shaping circuit 14. In this waveform shaping circuit 14, the magnetic sensor 13
The positive output signal FG and the negative output signal PG of the
L ⁺ and L ^- compared to output a positive pulse signal and a negative pulse signal and provides them to the signal generating circuit 15. And
The signal generation circuit 15 outputs a pulse signal PGa as shown in FIG. 4 (b) based on the negative pulse signal of the waveform shaping circuit 14, and shown in FIG. 4 (c) based on the positive pulse signal. The pulse signal PGa is output as described above. In this case, the pulse signal P
A dummy pulse PGa 'is formed before one pulse of Ga, and one pulse of the pulse signal PGa indicates a reference position at which the rotor 7 starts rotating. Further, the signal generation circuit 15 outputs the pulse signal PGa (including PGa ').
And FGa are synthesized and frequency-divided to output equally-spaced speed detection pulses VG as shown in FIG. 4 (d). Then, the pulse signals PGa and FGa from the signal generation circuit 15 are supplied to the switching circuit 17. The switching circuit 17 includes a pulse signal PO and a pulse signal.
It compares the frequency with PGa and FGa, and the pulse signal PO
When the frequency of the pulse signal PGa is higher than the frequency of the pulse signals PGa and FGa, the pulse signal PO is supplied to the commutation signal generation circuit 19; conversely, when the frequency of the pulse signal PGa and FGa is higher than the frequency of the pulse signal PO, Supplies the pulse signals PGa and FGa to the commutation signal generation circuit 19. Therefore,
When the brushless motor 1 is started, the pulse signal PO is supplied to the commutation signal generation circuit 19 via the switching circuit 17, but when the frequency of the pulse signals PGa and FGa becomes higher than the frequency of the pulse signal PO, that is, the brushless motor When 1 becomes equal to or higher than the predetermined speed, the pulse signals PGa and FGa are supplied to the commutation signal generation circuit 19 via the switching circuit 17. As a result, the commutation signal generation circuit 19 outputs the pulse signals PGa and FGa.
And output signals φa, φb and φc in the same manner as described above, and the drive circuit 20 outputs the output voltages φ1, φ2
And φ3 are output. Accordingly, the inverter circuit of the drive circuit 20 operates as a self-excited inverter circuit using the pulse signals PGa and FGa for commutation, and the brushless motor 1 continues to operate as a synchronous motor. Then, the commutation signal generation circuit 19 is reset every time the pulse signal PGa is given, so that the reference phase of the three-phase stator coils 6 always becomes the commutation phase based on the pulse signals PGa and FGa. Correction so that the output signals φa, φb and φc are output. Therefore, the drive circuit 20 is controlled in six stable states for commutation, and the brushless motor 1 is in a steady operation state.

On the other hand, the speed detection pulse output from the signal generation circuit 15
VG is added between the signal terminal 25 and the ground power supply terminal 24, and further, the signal terminal 29 of the external control unit 22 and the ground power supply terminal via the signal wire 33 and the ground power wire 32.
Supplied between 28 and. The external control unit 22 calculates the actual speed of the brushless motor 1 by counting the speed detection pulse VG by a counter. In this case, the dummy pulse V corresponding to the dummy pulse PGa 'is calculated.
G 'does not count. Then, the external control unit 22 issues a speed command signal VS for performing, for example, proportional integral differentiation control based on the actual speed and the speed command value obtained from the speed detection pulse VG to make the brushless motor 1 rotate at a constant speed. Is output between the power supply terminal 30 and the ground power supply terminal 28. Then, the speed command signal VS is applied between the command terminal 26 and the ground terminal 24 of the motor drive unit 21 via the command line 34 and the ground power supply line 32, and then given to the drive circuit 20. As a result, the drive circuit 20 drives the brushless motor 1 to rotate at a constant speed according to the speed command value.

Since the speed detection pulse VG includes the dummy pulse VG ', it can be determined that the pulse VGa next to the dummy pulse VG' corresponds to the phase detection signal.
Therefore, the speed detection pulse VG includes information on both the frequency signal and the phase detection signal.

According to this embodiment, the following effects can be obtained. That is, at the time of starting, the brushless motor 1 is started as a synchronous motor by operating the inverter circuit of the drive circuit 20 as a separately-excited inverter circuit based on the pulse signal PO from the oscillation circuit 18, and thereafter, the signal from the signal generating means 16 Since the brushless motor 1 is operated as a synchronous motor by operating the inverter circuit of the drive circuit 20 as a self-excited inverter circuit based on the pulse signals PGa and FGa, the position of the magnetic pole of the rotor 7 differs from the conventional one. It is not necessary to use a position detecting element for directly detecting the, the structure can be simplified, the size can be reduced, and the cost can be reduced as a whole.
Further, after the brushless motor 1 is switched to the operation based on the pulse signals PGa and FGa, the commutation signal generation circuit 19 is reset every time the pulse signal PGa is supplied. Each time the pulse signal PGa is supplied, that is, at the set reference position, the commutation phase is always corrected so as to become the reference phase. Therefore, even if the brushless motor 1 enters a steady operation state and the load fluctuates, There is no step-out. In addition, the permanent magnet 10 of the signal generating means 16 causes the frequency signal magnetizing section 11 for generating the pulse signal FGa and the phase detection signal magnetizing section 12 for generating the pulse signal PGa to have N polarities different from each other. Since the poles and the S pole are formed, the magnetization of each of the magnetized portions 11 and 12 is stabilized, and the magnetization accuracy can be improved.
The output signals FG and PG of the magnetic sensor 13 can be made sufficiently large, the S / N ratio can be improved, and the waveform shaping circuit 14 can be constituted by only a comparator without an amplifier.

By the way, when the speed detection pulse VG is a weak signal, sharing the ground power supply line 32 when transmitting the signal to the external control unit 22 deteriorates the S / N ratio and makes it difficult to determine the signal. Therefore, a dedicated ground line is usually used. However, in the present embodiment, as described above, the magnetizing units 11 and 12 for generating the pulse signals FGa and PGa are formed to have different polarities of N pole and S pole, and the output signals FG and Since the PG is made sufficiently large, the level of the speed detection pulse VG obtained therefrom can also be made sufficiently high. Therefore, when transmitting this speed detection pulse VG to the external control unit 22, the power supply line 32 for ground is used. Can be shared, and the number of connection lines can be reduced accordingly. Further, since the speed detection pulse VG has the dummy pulse VG ', it includes information of both the frequency signal and the phase detection signal, and therefore transmits the frequency signal and the phase detection signal to the external control unit 22. Therefore, one signal line 33 can be used without using a dedicated signal line, and the number of connection lines can be further reduced.

As a result, according to the present embodiment, as shown in FIG.
The motor drive unit 21 and the external control unit 22 need only be connected by a minimum of four connection lines of a power supply line for positive potential 31, a power supply line for ground 32, a signal line 33, and a command line. There is an advantage.

FIG. 5 shows a second embodiment of the present invention. Hereinafter, the same parts as those in FIG. 4 of the above embodiment are denoted by the same reference numerals, and only different parts will be described.

That is, the speed detection pulse VG shown in FIG. 5D is shifted from the speed detection pulse VG shown in FIG. 4D by one pulse. Specifically, the dummy pulse PGa 'in the pulse signal PGa shown in FIG.
Is output as the dummy pulse VGa 'in the speed detection pulse VG of FIG. 5D, and when the next pulse of the dummy pulse PGa' in the pulse signal PGa is output, FIG. The next pulse in the pulse signal FGa shown in FIG. Therefore, all of the speed detection pulses VG shown in FIG. 5D except for the dummy pulse VGa ′ are pulse signals FGa based on the frequency signal magnetizing section 11.
And the magnetized parts 11 and 1 of the permanent magnet 10
The accuracy of the speed detection pulse VG can be improved even if there is a difference in the magnetization level between the N and S poles.

FIGS. 6 to 8 show a third embodiment of the present invention. The same parts as those of the above embodiment are denoted by the same reference numerals, and only different parts will be described below.

That is, in FIG. 6, reference numeral 35 denotes a permanent magnet which replaces the permanent magnet 10, and its inner peripheral surface is magnetized to eight magnetic poles for the field like the permanent magnet 10. On the outer peripheral surface of the permanent magnet 35, a frequency signal magnetized portion 35 magnetized to 48 poles in which N poles and S poles are alternately formed, of which, for example, 5 pairs of N pole and S pole Are magnetized more strongly than the others and are formed on the magnetized portion 37 for the phase detection signal.

Reference is now made to FIG. Numeral 38 is a signal generating means which replaces the signal generating means 16, which connects the magnetic sensor 13 to the input terminals of the phase signal detecting circuit 39 and the zero cross detecting circuit 40, and connects these output terminals to the waveform shaping circuits 41 and 42, respectively. The input terminal of the mix discriminating circuit 43 is connected to the input terminal Ia and the input terminal Ib of the switching circuit 14.

When the brushless motor 1 is started, the magnetized portion 36 of the permanent magnet 35 is also rotated together with the rotor 7 of the brushless motor 1, so that the magnetic sensor 13 has the magnetized portion as shown in FIG. Each time the 36 magnetic poles correspond, a positive (+) or negative (-) output signal FG corresponding to the rotation speed is generated.
Generates an output signal PG having a higher level than the output signal FG. Then, since the output signal PG is given to the phase signal detection circuit 39, the phase signal detection circuit 39
PG is compared with the reference level l ⁺ to output a detection pulse SP as shown in FIG. 8 (b), which is supplied to the mix discriminating circuit 43 via the waveform shaping circuit 41. Also, output signals PG and FG
Is a waveform shaping circuit 42 provided to the zero-cross detection circuit 40.
8 (c) from the waveform shaping circuit 42.
As shown in FIG. 7, a zero-cross pulse ZP, which is a zero-cross signal having a constant width rising at the zero-cross point of the output signals PG and FG, is output. Then, the zero cross pulse ZP is also supplied to the mix discrimination circuit 43. When the detection pulse SP is given, the mix discriminating circuit 43 receives the next zero-cross pulse.
ZP is output as a pulse signal PGa as a phase detection signal as shown in FIG. 8D, and a zero-cross pulse ZP located between the pulses of the pulse signal PGa is output as shown in FIG. 8E. The pulse signal FGa is output as a frequency signal, and these pulse signals PGa and FGa are combined and frequency-divided to output a speed detection pulse VG as shown in FIG. 8 (f). Subsequent operations are the same as in the first embodiment.

Therefore, according to the third embodiment, not only the same effects as in the first embodiment can be obtained, but also the pulses PGa and FGa and the speed detection lug VG can be output at the zero-cross point. It is possible to improve the accuracy of each signal without being affected by the magnetization variation of 35, and it is possible to eliminate the rotation unevenness of the brushless motor 1.

In the above embodiment, the fact that the brushless motor 1 has reached the predetermined rotational speed is determined by comparing the frequency of the pulse signal PO with the frequency of the pulse signal FGa, and the pulse signal given to the commutation signal generation circuit 19 is determined. Although it is switched between PO and PGa, FGa, the frequency of the pulse signal FGa is equivalent to the period of the zero-cross pulse ZP.
May be determined to determine that the rotation speed of the brushless motor 1 has reached a predetermined value. Further, when a certain time has elapsed since the oscillation circuit 18 started the oscillating operation, it is considered that the rotation speed of the motor 1 has become a predetermined value, and the pulse signals PGa and PGa are replaced with the pulse signals PO. To the commutation signal generation circuit.

In addition, the present invention is not limited to the embodiment described above and shown in the drawings. For example, the present invention can be applied to two sets of brushless motors and can be appropriately modified and implemented without departing from the gist. Of course.

[Effects of the Invention] As will be clear from the above description, the present invention has the following effects.

According to the brushless motor driving device of the first aspect, the brushless motor is started up based on the synchronous rotation signal from the oscillating means, the frequency signal and the phase detection signal from the signal generating means, and the steady operation is performed. In addition, a position detecting element for directly detecting the position of the magnetic pole of the rotor is not required, so that the configuration can be simplified, the size and weight can be reduced, and the cost can be reduced as a whole. According to the brushless motor drive device of the present invention, the frequency signal magnetized portion and the phase detection magnetized portion of the permanent magnet are magnetized to have different numbers of poles, so that the permanent magnet is magnetized. , The magnetization accuracy is improved, the output signal of the magnetic sensor can be made sufficiently large, and the S / N ratio can be improved.

According to the brushless motor driving device of the third aspect, the speed detection signal is obtained from the frequency signal magnetized portion side of the permanent magnet, so that the speed detection signal is obtained even if the levels of the N pole and the S pole are different. Accuracy can be improved.

According to the brushless motor driving device of the fourth aspect, since the zero-cross detection circuit is provided as the signal generating means, there is no influence from the variation in magnetization of the permanent magnet.

According to the brushless motor drive device of the fifth aspect, when speed control is performed on the motor drive unit from the external control unit, the speed control signal includes information of both the frequency signal and the phase detection signal. There is an advantage that only one signal line is required.

According to the brushless motor drive device of the sixth aspect, when DC power is supplied from the external control unit to the motor drive unit, the ground power supply line can be shared for transmitting the speed detection signal. There is an advantage that only four lines for signal, signal line, power supply for positive potential and power supply line for ground are required.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 show a first embodiment of the present invention.
FIG. 2 is a block diagram showing an electric configuration, FIG. 2 is a side view showing a cross section of the left half of the brushless motor, FIG. 3 is a diagram showing a magnetized state of a permanent magnet, and FIG. FIG. 5 is a signal waveform diagram of each part, FIG. 5 is a diagram corresponding to FIG. 4 showing a second embodiment of the present invention, and FIGS. 6, 7, and 8 are third embodiments of the present invention. 2, FIG. 1 and FIG. 4 corresponding to FIG. In the drawing, 1 is a brushless motor, 3 is a printed wiring board, 4 is a stator, 6 is a stator coil, 7 is a rotor,
10 is a permanent magnet, 11 is a magnetized part for frequency signal, 12 is a magnetized part for phase detection signal, 13 is a magnetic sensor, 15 is a signal generation circuit, 16
Is a signal generation means, 17 is a switching circuit, 18 is an oscillation circuit (oscillation means), 19 is a commutation signal generation circuit, 20 is a drive circuit, 21 is a motor drive section, 22 is an external control section, 31 is a power supply for positive potential Line, 32 is a ground power supply line, 33 is a signal line, 34 is a command line, 35 is a permanent magnet, 36 is a frequency signal magnetized section, 37 is a phase detection signal magnetized section, and 38 is a signal generating means. , 39 is a phase signal detection circuit,
26 is a zero cross detection circuit, and 43 is a mix discrimination circuit.

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-164088 (JP, A)

Claims (6)

(57) [Claims] 1. A brushless motor comprising: a permanent magnet rotor having a plurality of magnetic poles for a field; and a stator having a plurality of stator coils, comprising: an oscillating means for generating a signal for synchronous rotation; Frequency signal generating means for generating a frequency signal related to the number of magnetic poles in response to rotation; phase detection signal generating means for generating a phase detection signal corresponding to the phase of the magnetic pole in response to rotation of the rotor; A commutation signal generating means for generating a commutation signal to be supplied to the stator coil based on the rotation signal and the frequency signal, wherein the commutation signal is generated based on the synchronous rotation signal at the time of start-up; When the frequency is equal to or higher than a predetermined value, the commutation signal is generated based on the frequency, and the commutation signal based on the frequency signal is generated. A commutation signal generating means for correcting a commutation phase of the commutation signal by the phase detection signal; and a commutation signal output from the commutation signal generation means sequentially energized to the plurality of phase stator coils. And a driving circuit for driving the brushless motor. 2. A brushless motor having a permanent magnet rotor having a plurality of magnetic poles for a field and a stator having a plurality of sets of stator coils, comprising: an oscillating means for generating a signal for synchronous rotation; Signal generating means for generating a frequency signal related to the number of magnetic poles in accordance with the rotation and generating a phase detection signal corresponding to the phase of the magnetic poles of the rotor; and a drive circuit for sequentially energizing the plural-phase stator coils A commutation signal generating circuit that counts applied signals to generate a commutation signal and supplies the commutation signal to the driving circuit; A switching circuit for supplying a frequency signal from the signal generating means, and then switching the commutation signal to a frequency signal. After that, each time the phase detection signal from the signal generating means is applied, the signal is reset and the commutation phase is corrected, and the signal generating means includes a multi-pole magnetized frequency signal. And a permanent magnet consisting of a phase detection signal magnetized portion having a polarity opposite to that of the frequency signal magnetic pole portion corresponding to the phase of the magnetic poles of the rotor, and a positive magnet corresponding to each magnetized portion of the permanent magnet. And a magnetic sensor for generating a negative output signal. 3. The brushless motor according to claim 2, wherein a speed detection signal at an equal interval is obtained in accordance with an output signal from the frequency signal magnetized portion of the permanent magnet in the magnetic sensor. Drive. 4. A brushless motor including a permanent magnet rotor having a plurality of magnetic poles for a field and a stator having a plurality of stator coils, wherein: an oscillating means for generating a signal for synchronous rotation; Signal generating means for generating a frequency signal related to the number of magnetic poles in accordance with the rotation and generating a phase detection signal corresponding to the phase of the magnetic poles of the rotor; and a drive circuit for sequentially energizing the plural-phase stator coils A commutation signal generating circuit that counts applied signals to generate a commutation signal and supplies the commutation signal to the driving circuit; A switching circuit for supplying a frequency signal from the signal generating means, and then switching the commutation signal to a frequency signal. Then, each time the phase detection signal from the signal generating means is given, the signal is reset and the commutation phase is corrected, and the signal generating means has an N pole and an S pole formed in multiple poles. The predetermined S pole and N of the frequency signal magnetic pole portion correspond to the phase of the frequency signal magnetized portion and the magnetic pole of the rotor.
A permanent magnet consisting of a magnetized portion for phase detection signal formed by setting the poles to have a higher magnetized level than the others, and a magnet for generating positive and negative output signals according to each magnetized portion of the permanent magnet A drive device for a brushless motor, comprising: a sensor; and a zero-cross detection circuit that generates a zero-cross signal at a zero-cross point of an output signal of the magnetic sensor. 5. An external control unit controls the speed of a motor drive unit including an oscillating unit, a signal generation unit, a drive circuit, a commutation signal generation circuit, and a switching circuit. The speed detection signal including the frequency signal and the phase detection signal is transmitted to the control unit through a single signal line.
5. The brushless motor driving device according to 3 or 4. 6. A signal line for a speed detection signal and a command line for giving a speed command signal based on a speed detection signal from the signal line to the motor drive unit, between the motor drive unit and the external control unit. 6. The brushless motor driving device according to claim 5, wherein the line is connected to a positive potential power line and a ground power line for supplying DC power from the external control unit to the motor driving unit.