JPH0433586A - Brushless motor driver - Google Patents

Abstract

PURPOSE:To obtain a commutation signal without requiring a magnetic sensor for directly detecting the pole position of a rotor by outputting a frequency signal output signal corresponding to a frequency signal generating section and a phase detection output signal corresponding to a phase detection signal generating section having different signal width from that of the frequency output signal. CONSTITUTION:An inverter circuit in a drive circuit 22 functions as an externally excited inverter circuit based on a pulse signal PO fed from an oscillation circuit 20. Upon start of a brushless motor, a magnetic sensor 13 generates a frequency signal output signal FG and a phase detection signal output signal PG having double period (signal width). When the speed of the brushless motor exceeds a predetermined value, the inverter circuit in the drive circuit 22 functions as a self-excited inverter circuit employing pulse signals PGa, FGa for commutation to sustain operation of the brushless motor as a synchronous motor. A commutation signal generating circuit 21 is reset every time when the pulse signal PGa is provided to correct the commutation phase.

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 detection element for detecting the position of a rotor pole is installed in the stator part in electrical angle. A plurality of logic converters are arranged at intervals of 60 degrees or 120 degrees, and the logic converter determines the timing of energization of the stator coil of the stator based on the position detection signals from these Hall elements. It is common to have an inverter circuit as a drive circuit that energizes the stator coil using the resulting commutation signal.

In addition, in this type of brushless motor, a frequency power generation conductor pattern is formed in the stator part, and a frequency power generation permanent magnet is attached to the rotor part in correspondence with this frequency power generation conductor pattern, so that the frequency power generation conductor pattern is A frequency generator is provided in which a frequency power generation signal is obtained from a frequency power generation conductor pattern, and the speed of the frequency generator is controlled based on the frequency power generation signal obtained from the frequency power generation conductor pattern. In addition, a phase detection signal generator is provided in which a permanent magnet for phase detection signals is attached to the rotor section, and a magnetic sensor for this phase detection signal is attached to the stator section to obtain a phase detection signal of a specific phase of the rotor. Based on the phase detection signal obtained from the sensor, the beginning of the tape, switching of the rotary head, etc. are controlled.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, for example, in the case of a three-phase brushless motor, it is necessary to use three Hall elements as magnetic sensors, and moreover, the number of wires is limited. A total of 11 wires are required: three power wires for the stator coil, two power wires for the Hall elements, and two output wires for each Hall element. For this reason, the structure inside the brushless morph becomes complicated, resulting in a large size and weight, and the overall cost becomes high.

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

[Structure of the Invention] (Means for Solving the Problems) A brushless motor drive device of the present invention is provided with an oscillation means for generating a synchronous rotation signal, and generates a frequency signal related to the number of magnetic poles according to the rotation of the rotor. A signal generating means is provided to generate a phase detection signal of a specific phase, and a drive circuit is provided to sequentially energize the stator coils of multiple phases, and a commutation signal is generated by counting the applied signals. A commutation signal generation circuit is provided for supplying a current signal to the drive circuit, and the commutation signal generation circuit is supplied with a synchronous rotation signal from the oscillation means at startup and then given a frequency signal from the signal generation means. A switching circuit is provided for switching to a frequency signal, and the commutation signal generation circuit is configured to be reset and correct the commutation phase every time a phase detection signal from the signal generation means is applied after the commutation signal generation circuit is switched to a frequency signal. and the signal generating means outputs a frequency signal output signal corresponding to the frequency signal generation section and a phase detection signal output signal corresponding to the phase detection signal generation section and having a signal width different from the output signal. The feature is that it has a configuration that includes a detection element.

(Function) According to the brushless motor drive device of the present invention, at startup, the synchronous rotation signal from the oscillation means is given to the commutation signal generation circuit, and the brushless motor is started as a synchronous motor via the drive circuit. Thereafter, the frequency signal from the signal generation means is applied to the commutation signal generation circuit, and the brushless motor continues to rotate as a synchronous motor via the drive circuit, and the commutation signal generation circuit is further supplied with the phase detection signal. It is reset each time the commutation phase is corrected to the specified phase, so that even if there are load fluctuations, the brushless motor will rotate stably without causing tax adjustment. .

Since the frequency signal output signal and the phase detection signal output signal from the detection element of the signal generating means have different signal widths, the frequency signal and the phase detection signal can be reliably separated, resulting in reliability. This also improves manufacturability.

(Embodiment) Hereinafter, an 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 the drawings.

First, the configuration of the brushless motor 1 will be described according to FIG. 2 is a frame, to which a printed wiring board 3 is attached. Further, a stator 4 is fixed to the frame 2 below the printed wiring board 3, and the stator 4 is connected to the stator core 5 for a plurality of phases, for example, three phases.
It is constructed by winding stator coils 6 of each phase. Further, a shaft 8 of a rotor 7 is inserted and supported in the center of the frame 2, and a rotor yoke 9 in the shape of a short cylinder with a bottom is fixed to the lower end of the shaft 8.

A permanent magnet 10 is attached to the rotor yoke 9 so that its inner peripheral surface corresponds to the outer peripheral surface of the stator core 5. The inner peripheral surface of this permanent magnet 10 has a plurality of poles, for example, an N pole and an S pole.
Eight field magnetic poles with alternating poles are magnetized. Further, on the outer circumferential surface of the permanent magnet 10, there is formed a frequency signal magnetized part 11, which is a frequency signal generating part, which is magnetized into, for example, 40 poles with alternating N and S poles. For example, five pairs of N and S poles are magnetized to have twice the width of the other poles, and are formed in the phase detection signal magnetized section 12, which is a phase detection signal generation section. and,
The printed wiring board 3 includes the frequency signal magnetization section 1.
1 and the phase detection signal magnetized part 12, a magnetic sensor 13 consisting of a detection element, for example a Hall element, is mounted on a holder 13a.
It has been taken through [J].

Now, the electrical configuration will be described with reference to FIG. The output terminal of the magnetic sensor 13 is connected to the input terminal of a waveform shaping circuit 14, the output terminal of this waveform shaping circuit 14 is connected to the input terminal of an integrating circuit 15, and the output terminal of this integrating circuit 15 and the waveform shaping circuit] The output terminals of 4 are connected to each input terminal of the pulse separation circuit 16, thereby forming a signal generating means 17. In this case, the pulse separation circuit 16
outputs a pulse signal FGa, which is a frequency signal, and a pulse signal PGa, which is a phase detection signal, in accordance with input signals, as will be described later.

The two output terminals of the pulse separation circuit 16 are connected to the two input terminals Ia and Ib of the switching circuit 18, respectively.
The other output terminal is connected to one input terminal of a speed detection pulse signal generation circuit which operates as described below.

An oscillation circuit 20 is an oscillation means, and its output terminal is connected to the input terminal 1c of the switching circuit 18. This oscillation circuit 20 starts an oscillation operation when a motor switch (not shown) is turned on, and generates a pulse signal PO which is a signal for synchronous rotation.
It is designed to output . Further, the output terminal 0 of the switching circuit 18 is connected to the input terminal of a commutation signal generation circuit 21 consisting of a pulse counter, a logic circuit, etc. 22
is a drive circuit, which includes an inverter circuit formed by bridge-connecting six transistors, which are semiconductor switching elements, and whose input terminal is connected to the output terminal of the commutation signal generation circuit 21. There is. and,
The output terminal of the drive circuit 22 is connected to the three-phase stator coil 6 of the brushless motor 1.

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

Next, the operation of this embodiment will be explained with reference to FIG. 3.

When a motor switch (not shown) is turned on, the oscillation circuit 20 first oscillates at about 10 Hz and outputs a pulse signal PO. As a result, the switching circuit 18, which operates as described later, provides the pulse signal PO to the commutation signal generation circuit 21. The commutation signal generation circuit 21 counts and logically processes this pulse signal PO to produce the output signals in FIGS. 3(h), (i) and (j).
), the output signals φa, φb and φ are commutated signals.
C and give them to the drive circuit 22. The drive circuit 22 turns on and off the transistors of the inverter circuit based on these output signals φa, φb, and φC, thereby generating 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 22 operates as a separately excited inverter circuit to start the brushless motor 1 as a synchronous motor. When the brushless motor is started, the frequency signal magnetizing section 11 and the phase detection signal magnetizing section 12 of the permanent magnet 10 are rotated together with the rotor 7, so the magnetic sensor 13 is activated as shown in FIG. ) generates an output signal as shown in That is, the magnetic sensor 13 generates a positive (+) and a negative (-) frequency signal output signal FG when the frequency signal magnetized part corresponds to 1 and -10=, and generates a magnetized part for the phase detection signal. When corresponding to section 12, the positive (+) period (signal width) is twice that of the output signal FG.
and a negative (-) phase detection signal output signal PG, which are supplied to the waveform shaping circuit 14.

As shown in FIG. 3(b), this waveform shaping circuit 14 outputs a zero-crossing pulse signal ZP that rises and falls at the zero-crossing point on the positive side of the Okayama force signals FG and PG of the magnetic sensor 13. It is given to the integrating circuit 15. Based on the zero-crossing pulse signal ZP of the waveform shaping circuit 14, the integrating circuit 15 outputs an integral output signal IS as shown in FIG.
Give to 6. The pulse separation circuit 16 outputs an integral output signal is
A comparison pulse signal CP is obtained as shown in FIG. 3(d) by comparing the reference level signal RI with the reference level signal RI.Furthermore, in synchronization with the fall of this comparison pulse signal CP, a comparison pulse signal CP is obtained as shown in FIG. 3(e). As shown in the figure, a pulse signal PGa with a constant width is output. In this case, a dummy pulse PGa' is formed before one pulse of the pulse signal PGa, and the dummy pulse PGa' is formed before one pulse of the pulse signal PGa.
The next pulse of Ga' indicates the reference position at which the rotor 7 starts rotating. Further, the pulse separation circuit 16 outputs a pulse signal FGa of a constant width in synchronization with the rise of the zero-cross pulse signal ZP from the waveform shaping circuit 14, as shown in FIG. 3(f). And pulse separation circuit]
Pulse signals PGa and FGa from 6 are applied to a switching circuit 18. The switching circuit 18 compares the frequencies of the pulse signal PO and the combined signal of the pulse signals PGa and FGa. If high, the pulse signal PO is sent to the commutation signal generation circuit 2.
1, and conversely, when the frequency of the composite signal of the pulse signals PGa and FGa is higher than the frequency of the pulse signal PO, the pulse signals PGa and FGa are supplied to the commutation signal generation circuit 21. . Therefore, when the brushless motor 1 is initially started, the pulse signal PO is
However, when the frequency of the composite signal of the pulse signals PGa and FGa becomes higher than the frequency of the pulse signal Po, that is, when the brushless motor 1 reaches a predetermined speed or higher, the pulse signal PGa and F
Ga is now supplied to the commutation signal generation circuit 21 via the switching circuit 18. As a result, commutation signal generation circuit 2
1 outputs the output signals φa, φb, and φC based on the pulse signals PGa and FGa in the same manner as described above, and the drive circuit 22 outputs the output voltages φ1. Outputs φ2 and φ3. Therefore, the inverter circuit of the drive circuit 22 operates as a self-excited inverter circuit using pulse signals PGa and FGa for commutation, and continues operating the brushless motor 1 as a synchronous motor. Then, the commutation signal generation circuit 21 generates a pulse signal PG
It is reset every time a is given, and the pulse signal PGa
and output signals φa, φb such that the reference phase of the three-phase stator coil 6 is always commutated based on FGa.
and φC. Therefore, the drive circuit 22 is controlled to six stable states for commutation,
The brushless motor 1 is operated in a steady state.

Note that the pulse signals FGa and P from the pulse separation circuit 16
Ga is also supplied to the speed detection pulse signal generation circuit 19, and this speed detection pulse signal generation circuit 1
9 divides the frequency of the synthesized pulse signals FGa and PGa by 2 and outputs equally spaced speed detection pulse signals VG as shown in FIG. 3(g). This speed detection pulse signal VG is given to an external control section (not shown), and the external control section calculates the actual speed of the brushless motor 1 by counting the speed detection pulse signal VG with a counter. dummy pulse P
Dummy pulse VG' corresponding to Ga' is not counted. Then, the external control section performs, for example, proportional-integral-derivative control based on the actual speed obtained from the speed detection pulse signal VG and the speed command value, and sends a speed command signal to the drive circuit for making the brushless motor 1 rotate at a constant speed. 22, and the drive circuit 22 drives the brushless motor 1 to rotate at a constant speed according to the speed command value.

Furthermore, since the speed detection pulse signal VG includes the dummy pulse VG', it can be determined that the pulse VGa following the dummy pulse VG' corresponds to the phase detection signal. Therefore, the speed detection pulse signal VG includes information on both the frequency signal and the phase detection signal. 2. Then, the external control section controls the beginning j7 of the tape based on the pulse VGa indicating this phase detection signal, and also controls the speed detection pulse signal V using this pulse VGa as a reference.
By counting G, the position of the rotor 7 is determined every 180 degree rotation, and based on this, the switching of the rotary head is controlled.

According to this embodiment, the following effects can be obtained. That is, at startup, the brushless motor 1 is started as a synchronous motor by operating the inverter circuit of the C drive circuit 22 as a separately excited inverter circuit based on the pulse signal PO from the oscillation circuit 20, and thereafter, the lower stage of signal generation Pulse signals PGa and F from 17
By operating the inverter circuit of the drive circuit 22 as a self-excited inverter circuit based on Ga, the brushless motor 1 continues to operate as a synchronous motor. There is no need to use a detection element, which makes the structure simpler, smaller and lighter, and can be done at a lower cost overall.

Furthermore, the brushless motor] receives pulse signals PGa and FG.
After switching to operation based on a, commutation signal generation circuit 2
1 is reset every time the pulse signal PGa is applied, so the commutation signal generation circuit 2]
Every time Ga is applied, the commutation phase is always corrected to become the reference phase at the set reference position,
Therefore, even if the brushless motor 1 is in a steady operating state and the load fluctuates [2], step-out will not occur. Furthermore, in the permanent magnet of the signal generating means 17], the magnetic pole widths of the N and S poles of the phase detection signal magnetized section 12 for generating the pulse signal PGa are set to 0 for generating the pulse signal F G a. Since the magnetic pole width of the N and S poles of the frequency signal magnetized section 1 is set to twice the width of the pulse signal F
It is possible to reliably separate Ga and PGa, improving reliability and, for example, compared to separating the pulse signals FGa and PGa by changing the magnetization lubricant. 5. Easy control of magnetization and improved productivity. Then, the pulse signal PGa+FGa and the speed detection pulse signal V G 4. Since the output signals can be output at the zero cross point of the output signals PG and FG, they are not affected by the magnetization variation of the permanent magnet 10, and the accuracy of each signal can be improved, making it possible to improve the accuracy of the brushless motor. It is possible to eliminate rotational unevenness in step 1.

In the second embodiment, the commutation signal generation circuit 21 receives a pulse signal P when the brushless motor 1 reaches a predetermined rotational speed.
However, for example, when a certain period of time has elapsed after the oscillation circuit 20 started the oscillation operation, the pulse signals PGa and FGa are applied instead of O.
(7 may also be used).

Further, in the above embodiment, the magneto-electric signal generating means 17 consisting of a combination of the permanent magnet 10 and the magnetic sensor 13 is used, but instead, the light from the light emitting element is transmitted to the transmitting part or the reflecting part so that the transmitting part L< is the transparent part, avoiding reflection.
Alternatively, a photoelectric signal generating means may be used in which the reflected light is received by a light receiving element.

In addition, the present invention is not limited to the embodiments shown in the drawings, for example, it can be applied to a two-phase brushless motor, etc., and the present invention can be appropriately modified and carried out without departing from the scope of the invention. Of course you can get it.

[Effects of the Invention] According to the brushless motor drive device of the present invention, the brushless motor is started and operated steadily based on the synchronous rotation signal from the oscillation means, the frequency signal and the phase detection signal from the signal generation means. Therefore, there is no need for a position detection element that directly detects the position of the rotor's magnetic poles, which simplifies the configuration, makes it possible to reduce the size and weight, and overall, it can be done at low cost. Since the signal widths of the output signal for the frequency signal and the output signal for the phase detection signal from the detection element are made different, it is easy to separate the frequency signal and the phase detection signal, and reliability can be improved. At the same time, it has the excellent effect of improving manufacturability.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with Fig. 1 being a block diagram showing the electrical configuration, Fig. 2 being a side view showing the left half of the brushless motor in cross section, and Fig. 3 showing various parts for explaining the operation. 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, 1
0 is a permanent magnet, 11 is a magnetized part for frequency signals (a generation part for frequency signals), 12 is a magnetized part for phase detection signals (a generation part for phase detection signals), 13 is a magnetic sensor (detection element), ]6 7 is a pulse separation circuit,] 7 is a signal generation means, 18 is a switching circuit, 20 is an oscillation circuit (oscillation means), 21 is a commutation signal generation circuit, and 22 is a drive circuit. Applicant Toshiba Corporation Agent Patent Attorney Tsuyoshi Sato

Claims (1)

[Claims] 1. In a brushless motor equipped with a permanent magnet type rotor having multiple poles and a stator having multiple phases of stator coils, an oscillation means for generating a signal for synchronous rotation, and an oscillation means related to the number of magnetic poles according to the rotation of the rotor. a signal generating means for generating a frequency signal and a phase detection signal of a specific phase; a drive circuit for sequentially energizing the stator coils of the plurality of phases; a commutation signal generation circuit for supplying a commutation signal to the drive circuit; and a commutation signal generation circuit for supplying a synchronous rotation signal from the oscillation means at startup to the commutation signal generation circuit and thereafter supplying a frequency signal from the signal generation means. and a switching circuit for switching to a frequency signal, and the commutation signal generation circuit is reset to correct the commutation phase every time a phase detection signal from the signal generation means is applied after the commutation signal generation circuit is switched to a frequency signal. The signal generation means is configured to generate a frequency signal output signal corresponding to the frequency signal generation section, and a phase detection signal output signal corresponding to the phase detection signal generation section, which has a different signal width from the output signal. A brushless motor drive device characterized by having a detection element that outputs.