JPH0572197B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) This invention provides switching of the excitation phase using a signal of the induced voltage in the stator winding, which has been improved to effectively execute starting operation control. The present invention relates to a control device for a brushless motor.

(Prior Art) Brushless motors do not have brushes, commutators, etc., so they have a simple structure, and they do not generate sparks during operation, making them highly safe. Therefore, it is expected that its applications will be sufficiently wide-ranging compared to DC machines.

In this brushless motor, the excitation phase is switched by the induced voltage in the stator winding. Therefore, since the above-mentioned induced voltage is not generated at the time of startup, a rotating magnetic field is forcibly applied from the outside, and the induced voltage is reduced after the rotor reaches a predetermined rotational speed. This is detected and the excitation phase is switched. However, with such a starting means, it takes time for the rotational speed to rise, resulting in poor starting response.

FIG. 17 shows a schematic configuration for explaining the rotation control means of a conventional brushless motor. An armature coil 14 is wound around the armature coil 13 .
A rotor 13 is connected to the rotating shaft 12.
Rotating plate 1 for position detection so as to rotate coaxially with
5 is provided, and a detection element 16 is fixedly set at a position facing this rotary plate 15. In this case, a Hall element, a magnetoresistive element, etc. is used as the detection element 16, and the rotary plate 15 for position detection that faces this is a permanent one with a magnetic pole set at a specific rotation angle position. It is composed of a magnet and is configured to be able to detect a specific rotation angle position of the armature coil 14. In addition, the detection element 16
It is also possible to construct the rotating plate 15 by a slit plate or a reflector that transmits light at a specific rotational angle position.

That is, the relative positional relationship between the rotor 13 and the stator is detected by the position detection mechanism 17 including the rotary plate 15 and the detection element 16, and the position of the rotor 13 is detected at a predetermined position corresponding to the detected positional relationship. The motor 11 is driven and controlled by supplying an exciting current to the armature coil.

FIG. 18 shows a drive control circuit for the brushless motor 11 equipped with the position detection mechanism 17 configured as described above.
The switching elements of the three-phase inverter 18 are controlled to open and close according to the position detection signal of the rotor 13 detected by the rotor 13, and excitation current is distributed and supplied to the three-phase armature coils of the motor 11.

Therefore, in the case of such conventional brushless motor control means, the position detection mechanism 1 using a Hall element or the like for detecting the rotational angular position of the rotor 13 is used.
7 is required, and the configuration of the electric device becomes complicated. Further, in order to configure the position detection mechanism 17, a detection element such as a Hall element or a magnetoresistive element is used, and the range of use is inevitably limited due to the environmental resistance of such a detection element. It has become a state of affairs.

Therefore, Ninth
Ninth Annual Symposium “Incremental Motion Control Systems and Devices”
``incremental motion control systems snd
device”, published by Incremental Motion Control Systems Society.
PM Brushless Motor Drives (PM Brushless Motor
DRIVES) (page 305), the three-phase Y
A resistance circuit is provided that is connected in parallel to each of the armature coils set in the wiring, and fluctuations in potential difference between the neutral point of this resistance circuit and the neutral point of the armature coil are detected, and the inverter circuit Therefore, there is a device that switches and controls the excitation current to the armature coil in response to this potential difference variation.

When a rotating magnetic field is applied as a starting means in this case, a reverse rotational torque is generated at the beginning of starting depending on the relative positional relationship between the rotor and stator.
After the rotor starts rotating in the opposite direction, the following phenomenon occurs when the rotor changes its direction of rotation in the forward direction. When the rotational direction is reversed, vibrations occur and normal startup control cannot be performed.

In order to prevent such reverse rotation of the rotor at the beginning of startup, an excitation current is supplied to a specific phase of the armature coil for a predetermined period of time to fix the rotor in a fixed position at the time of startup. Thereafter, the inverter circuit switches the excitation current to the armature coil to rotate the rotor, thereby preventing the rotor from rotating in reverse and providing stable startup.

(Problem to be Solved by the Invention) However, in the conventional system described above, when the rotor is fixed in a fixed position by supplying exciting current to a specific phase of the armature coil, the rotor vibrates. There is a problem in that it later converges to a stable point, takes time to stabilize, and takes time to start the brushless motor.

Therefore, the object of the present invention is to perform smooth and quick startup control at the time of startup.

(Means for Solving the Problem) An armature coil connected to a three-phase Y connection, a resistance circuit connected to the Y connection in parallel with the armature coil, and a neutral of the armature coil. signal generating means for generating an excitation switching signal for switching and controlling the excitation current to the armature coil in response to fluctuations in potential difference between a neutral point of the armature coil and a neutral point of the resistor circuit; Correspondingly, an inverter circuit that switches and controls the excitation current to the armature coil; and a rotor that rotates by switching the excitation current to the armature coil by the inverter circuit and is made of a multi-pole permanent magnet; a first detection means for passing an excitation current through the armature coils of two phases and detecting the polarity of the induced voltage generated by the vibration of the rotor in the armature coil of the remaining one phase; a second detection means for detecting a starting position of the rotor from a specific polarity of the induced voltage by the means and an excitation switching signal of the signal generating means, and inputting a motor starting signal to the inverter circuit; The present invention is intended to be a control device for a brushless motor.

(Function) The position at which the rotor starts is detected from the polarity of the induced voltage of the 1-phase armature coil and the excitation switching signal of the 3-phase armature coil, and the armature coil is excited via the inverter circuit. Switch the current,
Start the motor.

(Example) The present invention will be described below with reference to an example shown in the drawings. FIG. 1 shows a control device for a brushless motor, in which a brushless motor 11 has an armature coil 1 and a rotor 13 made of two-pole permanent magnets.
4 is wrapped. This armature coil 14 includes U-phase, V-phase, and W-phase armature coils 14a,
14b and 14c are Y-connected.

Then, the DC power supply 19 is activated by a start switch 19a.
It is connected to a three-phase inverter circuit 20 via. This three-phase inverter circuit 20 includes three PNP type transistors 20a, 20b, each having an emitter connected to the positive side of a DC power supply 19.
20c, and three npn type transistors 20 each having an emitter connected to the negative electrode side of the DC power supply 19.
d, 20e, and 20f. and,
A U-phase armature coil 14a is connected between the transistors 20a and 20d, and the transistor 2
V-phase armature coil 14b between 0b and 20e
are connected, and further transistors 20c and 20f
A W-phase armature coil 14c is connected between the two. Further, between the three-phase inverter circuit 20 and the armature coil 14, the three-phase armature coil 14
The resistors 22a to 22a correspond to each phase of
A resistor circuit 22 in which 22c is Y-connected is connected. This resistance circuit 22 is used for detecting the position of the rotor 13.

Further, the voltage V _M at the neutral point of the resistance circuit 22 and the voltage V _N at the neutral point of the armature coil 14 are input to the differential amplifier 31 . The differential amplifier 31 detects the voltage V _NM between the neutral points. In addition, this detected voltage is input to the integrator 32, and the integrated output is input to the zero cross comparator 33.
Enter. Here, the differential amplifier 31 and the integrator 3
2 and the zero cross comparator 33 constitute a signal generating means. Then, the output of the zero cross comparator 33 is input to the ring counter circuit 35. This ring counter circuit 35 conducts energization (excitation pattern) of the transistors 20a to 20f of the three-phase inverter circuit 20 via the base drive circuit 36 according to the output of the zero cross comparator 33.
control. Further, the base drive circuit 36 amplifies the output of the ring counter circuit 35.

A comparator 41 serving as a first detection means is connected to both ends of the W-phase armature coil 14c. This comparator 41 detects the polarity of the induced voltage E _W generated as the rotor 13 vibrates. Also, the output of the comparator 41 is
D of the D flip-flop 42 which constitutes the detection means of
Input to terminal (data). The output of the zero cross comparator 33 is input to the CP terminal (clock pulse). Further, the initial state of the D flip-flop 42 is set to the reset circuit 43.
The output is preset to 1 level. Furthermore, the Q terminal (output) of the D flip-flop 42 is input to a start-up timer circuit 44.
Then, the reset circuit 43 and the start timer circuit 44
A starting circuit 40 is configured with the above. Further, the reset circuit 43 generates a reset signal in order to restart the brushless motor 11 when the start switch 19a is turned on and when the output signal of the zero cross comparator 33 is not obtained for a certain period of time, and the reset circuit 43 generates a reset signal to restart the brushless motor 11. It is output to the start timer circuit 44.
The start timer circuit 44 inputs a signal to the ring counter circuit 35 to set the ring counter circuit 35 to the initial excitation pattern in response to a reset signal from the reset circuit 43. At the same time, the timer runs
The fall of the output of D flip-flop 42,
Or when the timer ends, the ring counter circuit 35
A signal for advancing the excitation pattern by two steps is input to the ring counter circuit 35.

Here, each U phase from the inverter circuit 20, V
The terminal voltages of phase and W phase are Vu, Vv, Vw, respectively.
Each U of the armature coil 14 of the brushless motor 11
The induced voltages of phase, V phase, and W phase are Eu, Ev, Ew, the neutral point potential of the armature coil 14 is V _N , and the resistance circuit 22
Let _{the neutral point} potential _of Vu − Eu) + (Vv − Ev) + (Vw
−Ew)}. Further, the potential difference between the neutral points is V _NM = (1/3) (Eu+Ev+Ew), which is the sum of the induced voltages of each phase of the armature coil 14, and the voltage applied from the inverter 20 can be removed.

Here, the induced voltage of each phase of the armature coil 14 is
If Eu, Ev, and Ew are respectively 120 degree trapezoidal waves as shown in Figure 2 A to C, the potential difference V _NM obtained by the differential amplifier 31 has a frequency three times the induced voltage as shown in Figure 2 D. It becomes a triangular wave state. In such a voltage waveform state, the section where the armature coil 14 is energized is the section where each induced voltage is in a flat state (the section shown with diagonal lines in FIG. The switching point coincides with the peak point of the potential difference V _NM . However, it is difficult to accurately detect the peak point of the V _NM because the amplitude of the potential difference V _NM varies depending on the motor rotation speed. Furthermore, when a noise signal is present, it is difficult to accurately capture the peak point of V _NM .

Therefore, this potential difference V _NM is integrated by an integrator 32 to form an integrated waveform as shown in FIG. 4E, and its zero crossing point is detected. If this is done, the waveform will have an amplitude that does not change with respect to the number of revolutions of the motor, making it easy to detect when the motor rotates at low speed, and being resistant to noise. Also, since the induced voltage is proportional to the rate of change of the flux linkage, if the flux linkage of each phase of the armature coil 14 is φu, φv, and φw, then V _NM = (1/3) (Eu + Ev + Ew) = (1/3) {-k(φu/dt)-k(φu/dt)-k
(φw/dt)}, and the integral of the potential difference V _NM is ∫V _NM dt = - (k/3) (φu + φv + φw), and it can be detected with a constant amplitude from low speeds, regardless of the rotation speed of the brushless motor 11. .

The waveform obtained by the integrator 32 is then input to the zero cross comparator 33, which outputs the short waveform shown in FIG. 2F. This short waveform becomes an excitation switching signal and is input to the ring counter circuit 35. Also,
This ring counter circuit 35 sequentially generates drive signals for each of the transistors 20a to 20f of the three-phase inverter circuit 20 in synchronization with the rise and fall of the short waveform of the zero cross comparator 33. Here, in FIG. 2 G to L, each transistor 2
It shows energization signals of 0a to 20f. Further, the numbers in FIG. 2M indicate transistors that are conducting.

First, an excitation pattern of the armature coil 14 of the brushless motor 11 by making each transistor 20a to 20f of the three-phase inverter circuit 20 conductive will be shown. The excitation pattern is designed to supply current in both directions to any two of the three Y-connected phases (U phase, V phase, W phase), so six types of excitation patterns are used as shown in Figure 3 A to F. There's a pattern. [u] shown in the figure
-v] are transistors 20a and 2 in FIG.
0e is made conductive, current flows from U phase to V phase,
This indicates that the coil is excited, and the arrow on the coil section indicates the direction of the current. Here, as shown in FIG. 3 A to F, [u-v] → [u-w] → [v-w] →
[v-u] → [w-v] → [w-v] → [u-v]
If the excitation is switched in this order, a rotating magnetic field in a fixed direction will be generated. If this order is reversed, a rotating magnetic field in the opposite direction to that in the above case will be generated.

Hereinafter, a case will be described in which the excitation sequence shown in FIG. 3 is performed. The _zero- crossing point (zero-crossing comparator 33
When a rising or falling edge of the output is detected, this excitation pattern advances by one step. In other words, the excitation pattern [u-v] shifts one step to the excitation pattern [u-w], and from then on, every time a zero-crossing point is detected, [v-w] → [v-u ]→[w-u]... Proceed with excitation. The ring counter circuit 35 creates the excitation patterns shown in FIG. 2 G to L in synchronization with the zero-crossing points in this manner. Then, in response to the output of the ring counter circuit 35, each transistor 20a to 20 is connected as shown in FIG.
The brushless motor 11 can be operated by making the armature coil f conductive and generating a rotating magnetic field synchronized with the position of the rotor 13 in each of the armature coils 14a to 14c.

In FIG. 4, 13 is a two-pole rotor made of permanent magnets, 10a to 10c are three-phase stator teeth, 1
0 is the housing, 14a is the U-phase armature coil, 1
4b is a V-phase armature coil, and 14c is a W-phase armature coil. In this model, when the [u-v] excitation pattern shown in FIG. 3A is performed, north and south poles are set in armature coils 14a and 14b.

Before starting the motor 11, the rotor 13 is moved by the attraction force (detent torque) acting between the permanent magnet of the rotor 13 and the stator as shown in FIG.
It is always set to stand still in one of the six positions shown in ~F. Set the state shown in Fig. 4 [u-v] The stable point according to the excitation pattern to the origin p
Then, the rotor 13 comes to rest at positions of ±30 degrees, ±90 degrees, and ±150 degrees.

At the time of startup, if a specific [u-v] excitation pattern as shown in FIG.
150°). Then, as shown in FIG. 6, the vibration oscillates attenuated around the stable point and then converges. In this figure, only one side (-30°, -90°, -150°) is shown because it is symmetrical with respect to the stable point. Additionally, this figure shows the experimental results with time plotted on the horizontal axis and angle plotted on the vertical axis.

Therefore, in the present invention, when the rotor 1 passes through a position where the vibrating rotor 13 converges,
3 has a speed in the same direction as the desired direction of rotation, the inverter circuit 20 switches and controls the excitation current to the armature coil 14, thereby realizing smooth startup of the motor 11.

Hereinafter, starting of the brushless motor 11 will be explained. FIG. 7 shows the initial state of the rotor 13 at ±150° as shown in FIGS. 5E and F. In this FIG. 7, the rotor 13 is at a stable point,
And the point that has the same velocity component as the rotation direction is
In the figure, b ₁ , b ₂ ... b _o (starting point). Therefore, conventionally, the brushless motor 11 was started after positioning to point a, where the vibrations of the rotor 13 converge, but by starting at the points b ₁ , b _{2 .} . . b _o described above, the motor can be started. 11 can be started up. Furthermore, if the motor 11 is started at point _b in FIG. 7, the time required to start the motor 11 can be shortened the most. Therefore, detection of _one point b will be explained.

When starting the brushless motor 11, the U-phase and V-phase armature coils 14a and 14b are excited using a specific excitation pattern [u-v]. At this time,
As shown in FIG. 4, stator teeth 10a, 10b
are excited to the north and south poles, respectively, and the rotor 13 vibrates. This vibration of the rotor 13 generates an induced voltage Ew in the remaining W-phase winding. FIGS. 8A and 8B show the rotor 13 relative to time after the excitation current is applied to the U-phase and V-phase, respectively, when the rotor 13 is stopped at a position of ±150 degrees before starting. and the induced voltage Ew induced in the W phase.
It shows.

Furthermore, the principle of detection of _one point b will be explained in detail using the waveform model shown in FIG. If the induced voltage of each phase of the armature coil 14 is a 120 degree trapezoidal wave, then
Interlinkage magnetic flux φu, φv, φw of each phase of armature coil 14
is shown in Figure 9A. Here, the origin 0° is the stable point of the rotor 13 in the initial excitation pattern [uv], and the point where the rotor 13 passes through this point in the positive direction during vibration is the starting point _b1 . The induced voltage Ew of the W-phase armature coil 14c is as follows, where θ is the rotation angle of the rotor 13 with respect to the origin, Ew=-k(dφw/dt) =-k(dφw/dθ)・(dθ/dt) , rate of change of interlinkage magnetic flux of W phase (dφw/dθ)
and the rotational speed of the rotor 13. here,
dφw/dθ is shown in FIG. 9C.

Here, in order to detect the starting point b ₁ regardless of the rotational speed when the rotor 13 vibrates, focusing on the polarity of the induced voltage Ew generated in the W phase, we can find that when the rotor 13 vibrates in the positive direction, W phase induced voltage
The polarity of Ew is negative as shown in Figure 9D,
When the vibration is in the negative direction, the vibration becomes positive as shown in FIG. 9F.

In addition, the integral of the potential difference V _NM between the neutral points used to detect the position of the rotor 13 is ∫V _NM dt = - (3/k) (φu + φv + φw),
This waveform is shown in FIG. 9B. Then, the excitation switching signal shaped by the zero cross comparator 33 from the above integral waveform is shown in FIG. 9E when the rotor 13 vibrates in the positive direction, and in FIG.
Shown in Figure G.

In addition, since the brushless motor 11 whose rotor 13 is made of a permanent magnet has a detent torque, specific phase excitation (in this example [uv]
The position of the rotor 13 before the excitation pattern is
Since the six points shown in FIG. 5 are ±30°, ±90°, and ±150°, the range of the angle θ of the vibrating rotor 13 is -
150°<θ<150° is sufficient.

Figure 9 shows non-excited phases (W
polarity of induced voltage Ew of phase) and potential difference between neutral points
When the combination of excitation switching signals obtained from V _NM is focused on the pulse edge of the excitation switching signal, there are 10 points, , , , , , , in Fig. 9, and these combinations are shown in Fig. 10.

The starting point (the point passing through the stable point in the positive direction) to be detected in order to realize the vibration starting method is , and at this time, the polarity of the induced voltage Ew of the non-excited phase (W phase) is negative and This is the rise of the excitation switching signal due to the sexual point potential V _NM . The above combination is the only one among the combinations.

The above describes the polarity of the induced voltage generated in the armature coil, which is a non-excited phase, due to the vibration of the rotor 13 during specific phase excitation at startup, and the Y connection between the neutral point of the armature coil and the armature coil in parallel. By combining the pulse edges of the excitation switching signal obtained from the neutral point potential of the detected resistor, the starting point can be detected while the rotor 13 is vibrating.

Next, starting of the brushless motor 11 will be explained. In FIGS. 1 and 13, when the start switch 19a is closed, a reset signal from the reset circuit 43 is input to the start timer circuit 44.
This reset signal causes the start timer circuit 44 to set the ring counter circuit 35 to the initial excitation pattern [u
-v]. This signal causes the ring counter circuit 35 to conduct the transistors 20a and 20e via the base drive circuit 36. And these transistors 20a, 2
0e causes current to flow from the power source 19 to the U-phase armature coil 14a and the V-phase armature coil 14b. Further, as described above, the induced voltage Ew generated in the W-phase armature coil 14c due to the vibration of the rotor 13 is input to the comparator 41. When it is desired to rotate the rotor 13 in the right direction (in the direction of the arrow shown in FIG. 1), since the polarity of Ew shown in FIGS. 11C and 13D is negative, the D flip-flop 42 is (data) terminal, 0
The level is entered, and also the
The rising edge of the excitation switching signal, which is the output of the zero cross comparator 33 shown in FIG. Therefore, as shown in FIG. 11E, the Q terminal (output) of the D flip-flop 42 outputs the 0 level from the 1 level. The falling signal at this time is input to the starting timer circuit 35 as the starting point _b1 detection signal. This signal causes the output of the ring counter circuit 35 to fall, and the excitation pattern of the ring counter circuit 35 is advanced by two steps. That is, the excitation pattern [uv] shown in FIG. 12A is transferred to the excitation pattern [vw].

In other words, the ring counter circuit 35 controls the transistors 20b and 2 of the three-phase inverter circuit 20.
Makes 0f conductive. As a result, the rotor 13 rotates clockwise and moves toward the stable position of this excitation pattern, as shown in FIG. 12C. And the first
As shown in Figure 3E, the zero cross comparator 33
The ring counter circuit 35
changes the excitation pattern from [v-w] to [v-u]. Immediately after this excitation pattern switching, the state is as shown in FIG. 12D. And the first
As shown in Figure 3E, the zero cross comparator 33
According to the rise and fall (every 60 degrees) of The excitation pattern is changed sequentially.

Then, the rotor 13 is rotated to start the brushless motor 11.

Therefore, as shown in FIG. 13, the U-phase and V-phase of the armature coil 14 are excited to position the rotor 13, and at this time, the rotor 13 has a speed in the same direction as the rotation direction. The rotor 13 is immediately rotated via the 3-phase inverter circuit 20, and the brushless motor 11 is started. There is no need to allow time for 13 to settle at the convergence position, and responsiveness can be improved.

Furthermore, since the starting point _b1 of the brushless motor 11 is determined by detecting the polarity of the induced voltage generated in the W-phase armature coil 13c and the zero crossing point of the neutral point potential, the rotor 13 It is possible to reliably detect the point at which the convergent position passes through the convergence position with a speed in the same direction as the rotational direction.

In addition, in Fig. 14, the stopping position of the rotor 13 is at the closest +30° position to the stable position due to the initial excitation pattern [u-v], and due to load conditions etc. This is an example in which the rotor 13 moves to a stable point without vibrating even if the excitation pattern [u-v] is performed, and the starting point according to the present invention cannot be detected. In this case, since the rotor 13 has converged near the stable point, it can be considered to be at the starting point and can be started. Therefore, the start timer circuit 44 is initialized by the reset signal shown in FIG. 14B generated by turning on the start switch 19a shown in FIG. 14A, and starts measuring the time _T1 .
At this time, the output G of the start timer circuit 44 in FIG. 14 becomes 1 level, and the ring counter circuit 35 becomes the initial excitation pattern [u-v] H in FIG. 14. If the starting point detection signal is not obtained within a predetermined period T after the initial excitation [u-v] at starting, the timer for _T1 hours ends.
At point B in the figure, the output of the startup timer circuit 44 changes to 0 level. Next, a signal is generated to the ring counter circuit 35 to forcibly advance the excitation pattern by two steps [vw]. Then, the rotor 13 is rotated, and the excitation pattern is sequentially switched according to the displacement of the zero cross comparator 33 to start the brushless motor 11. Therefore, even if the rotor 13 does not vibrate and stops at a stable point, the brushless motor 11 can be reliably started.

In addition, in the other embodiment shown in FIG.
A microcomputer (MPU) 60 is used. The excitation switching signal, which is the output of the zero cross comparator 33, is sent to the microcomputer 6.
It is connected to an external interrupt terminal of 0 and an input port, and interrupts are performed at the rise and fall of the excitation switching signal. In addition, the comparator 41
The output and start switch 19a of the microcomputer 60 are connected to the input port of the microcomputer 60.
Furthermore, the output port of the microcomputer 60 is connected to the base drive circuit 36.

Here, the operation will be explained using the flowchart shown in FIGS. 16A and 16B. In step S1, input the state of the start switch 19a, and if the start switch is ON in step S2, proceed to step S4; if not, proceed to step 3, turn off all outputs to the base drive circuit, and proceed to step S2. Return to S1 and wait for the startup switch to be turned on. At step S4, a predetermined time _t1 is set by the start timer _T1 , and at the same time, at step S5, an initial excitation pattern [u-v] is input to the three-phase inverter circuit 20.
Then, in step S6, set the startup flag to 1,
Proceed to step S7 and enable interrupts here.
Then, the zero cross comparator 3 shown in FIG.
At the rising or falling edge of the output of 3, the MPU
An interrupt occurs at step S60, and the interrupt shown in FIG. 16B starts, and from the start flag 1, the process proceeds to step S61. In this step S61, when the output of the zero cross comparator 33 is at the 1 level, the step S62
When the output of the comparator 41 is at 0 level, the process advances to step S63. Also, step
In S63, the startup timer is set to T ₁ and the process proceeds to step S8. Here, since the startup timer is T ₁ ,
Then proceed to step S9. Further, if the output of the zero cross comparator 33 is not at the 1 level in step S61, or if the output of the comparator 41 is not at the 0 level in step S62, the start flag returns to 1. Then, in step S8, the startup timer is set to _T1.
The start flag 1 is executed until the start flag is reached. Also, the output of the zero cross comparator 33 is not at 1 level,
Even if the output of the comparator 41 is not at 0 level, if the start timer reaches _T1 , the step
Proceed to S9. In step S9, the start flag is set to 0, and the process proceeds to start flag 0 in FIG. 16B. Also,
Proceeding to step S10, the three-phase inverter circuit 20
is set to an excitation pattern (vw) that is two steps ahead of the initial excitation pattern [uv].Here, when the output of the zero cross comparator 33 is 0 in step S91, the activation flag is set in step S92. is set to 2, and in step S93, the three-phase inverter circuit 20 is set to an excitation pattern [v-w].
The excitation pattern [vu] is set one step further. Then, with the start flag 2, the excitation pattern of the three-phase inverter circuit 20 is sequentially advanced one step at a time. Therefore, the brushless motor 11 can be started. Further, after the [vw] excitation, the process proceeds to step S11, and in this step S11, a restart timer _T2 is set. Then, each time the excitation pattern advances one step in step S94,
At S95, the restart timer _T2 is set to the initial state _t2 . Further, in step S12, when the output of the zero cross comparator 33 does not become 0 and the excitation pattern does not advance sequentially, a predetermined time _t2 is counted, and if the restart timer _T2 becomes 0 (the brushless motor 11 If it is determined that the startup is not performed), the process advances to step S13. Then, in step S13, interrupts are disabled, and the process returns to step S1 for restarting.

In addition, in the embodiment described above, since the rotation direction of the rotor 13 is determined in the direction of the arrow as shown in FIG. When the polarity of Fig. 9 D is negative and the excitation switching signal Fig. 9 E rises), the motor 11 is started, but when the rotor 13 rotates in the opposite direction to the arrow direction , as shown in Fig. 9 (W-phase armature coil 1
The polarity of Figure 9F, which is the induced voltage Ew of 4c, is negative,
(at the falling edge of Fig. 9 F, which is the excitation switching signal)
All you have to do is detect it.

Further, although a three-phase, two-pole brushless motor is shown as an example, the number of poles of the permanent magnets of the rotor 13 may be an even number excluding a multiple of six.

In addition, although the startup timer circuit 44 is used in FIG. 1, the startup timer circuit 44 is not used;
The signal from reset circuit 43 and the signal from D flip-flop 42 may be input to ring counter circuit 35.

In the embodiment described above, the D flip-flop 42 is used, but for example, the RS flip-flop 42 is used.
Flop, JK flip/flop, etc., starting point b ₁
It suffices as long as it can detect.

Moreover, although the power transistors 20a to 20f are used in the three-phase inverter circuit 20, for example, thyristors, relays, etc. may be used.

(Effects of the Invention) As described above, in the present invention, when positioning the rotor at startup, the polarity of the induced voltage induced in the armature coil detected by the first detection means and the excitation switching signal Therefore, the second detection means detects the starting signal and changes the excitation current of the armature coil via the inverter circuit to start the motor. This has the excellent effect of eliminating the need for time and improving responsiveness.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a control circuit of a brushless motor according to an embodiment of the present invention, FIG. 2 is a diagram showing signal voltage states of various parts in the control circuit, and FIG. 3 is a diagram showing the electric motor at the time of starting the motor. A diagram explaining the excitation order for the child coils, FIG. 4 is a diagram showing a visual model of a three-phase brushless motor, FIG. 5 is a diagram showing an example of the state of the rotor's rest point before starting, Fig. 7 is a diagram showing the rotor vibration damping state, Fig. 8 A and B are waveform diagrams showing the rotor vibration state and induced voltage state, and Fig. 9 is the starting point in Figs. 7 and 8. Diagram 1 showing signals for detecting
Figure 0 shows the pulse edge of the excitation switching signal and the induced voltage.
Ew, FIG. 11 is an operation diagram for detecting the starting point, and FIG. 12 is a diagram explaining the starting order shown in correspondence with the visual model shown in FIG. 4.
FIG. 13 is an operation diagram showing startup of the brushless motor, FIG. 14 is an operation diagram showing startup of the brushless motor in a state where the rotor does not vibrate, and FIG. 15 is another embodiment of the brushless motor control device according to the present invention. The circuit diagrams illustrating the examples, FIGS.
17 is a flowchart showing the operation of the microcomputer in the figure, FIG. 17 is a diagram explaining the position detection mechanism of a conventional brushless motor, and FIG.
8 is a diagram showing a drive control circuit for the motor in FIG. 7. FIG. 11...Brushless motor, 13...Rotor,
14...armature coil, 20...3-phase inverter circuit, 22...resistance circuit.

Claims (1)

[Scope of Claims] 1. An armature coil connected to a three-phase Y connection, a resistance circuit connected to the Y connection in parallel with the armature coil, and a neutral point of the armature coil and the signal generating means for generating an excitation switching signal for switching and controlling the excitation current to the armature coil in response to fluctuations in potential difference between the resistor circuit and the neutral point; , an inverter circuit that switches and controls the excitation current to the armature coil; a rotor that rotates by switching the excitation current to the armature coil by the inverter circuit; and a rotor consisting of a multi-pole permanent magnet; a first detection means for passing an excitation current through the armature coil and detecting the polarity of an induced voltage generated by vibration of the rotor in the armature coil of the remaining one phase; and induced voltage by the first detection means. a second detection means for detecting a starting position of the rotor from a specific polarity of voltage and an excitation switching signal of the signal generating means and inputting a motor starting signal to the inverter circuit; Control device.