JPH0728548B2 - Brushless DC motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor that reduces noise by overlapping energization by a predetermined conduction angle when energizing a plurality of stator coils. is there.

[Prior Art] Generally, a brushless DC motor is used for a motor that requires low noise, such as a fan motor, because the switching vibration noise generated when switching each phase of the stator coil during rotation is larger than that of the induction motor. In order to do so, it was required to reduce switching vibration noise. As a method for reducing such switching vibration noise, an overlap conduction method is known in which the conduction is overlapped by a predetermined conduction angle when switching each phase of the stator coil (for example, Sanyo Electric Technical Report VOL.18 No.2 1986.8). Pp. 130-132). That is, the conventional brushless DC motor of this type has a rotor (1) with a Hall IC (H ₁ ) (H ₂ ) (H ₃ ) as a magnetically sensitive element in principle as shown in FIGS. 4 and 5. The position of the main magnetic pole (2) is detected (rotational position is detected), and this detection signal is input to the microcomputer (3) to energize the stator coils (4r) (4s) (4t) by the microcomputer (3). The overlap conduction time during switching is calculated, the calculated time is added to the conduction time for switching the energization, and the switching transistors (Q ₁ ) (Q ₂ ) (Q ₃ ) (Q ₄ ) are based on this added output.
(Q ₅₎ to (Q ₆₎ on, was off control. (5) is a rotating shaft.

[Problems to be Solved by the Invention] However, in the conventional example shown in FIG. 4 and FIG.
There is a problem that an arithmetic circuit such as the microcomputer (3) is required to calculate the overlap conduction time when switching the energization of the stator coils (4r) (4s) (4t), which causes a cost increase.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a brushless DC motor that does not require an arithmetic circuit such as a microcomputer and can overlap predetermined conduction angle energization when switching energization of a stator coil. It is a thing.

[Means for Solving Problems] A brushless DC motor according to the present invention includes a rotor having a plurality of main magnetic poles and a plurality of auxiliary magnetic poles, and a main shaft pole for detecting a rotational position of the rotor for switching conduction angle. A main magnetic sensitive element that outputs a detection signal, a complementary magnetic sensitive element that detects the rotational position of the rotor by the complementary magnetic pole and outputs a detection signal for an overlapping conduction angle, the main magnetic sensitive element and the complementary magnetic sensitive element. A drive current having a predetermined conduction angle is sequentially switched and supplied to a plurality of stator coils based on a detection signal from the drive coil, and at least one of the energization switching times of the stator coil required for one rotation of the rotor is changed to the drive current. And a driving circuit for supplying a part of them in an overlapping manner,
The drive circuit outputs a conduction switching signal based on detection signals from the main magnetic sensitive element and the auxiliary magnetic sensitive element, and a drive current for the plurality of stator coils based on the output signal of the gate circuit. And a switching circuit for sequentially switching the above.

[Operation] The main magnetic sensitive element detects the rotational position of the rotor by the main magnetic pole and outputs the detection signal for the switching conduction angle. The complementary magnetic sensing element detects the rotational position of the rotor by the complementary magnetic pole, and outputs a detection signal for overlapping conduction angle. The drive circuit sequentially switches and supplies a drive current having a predetermined conduction angle to a plurality of stator coils based on the detection signal for the switching conduction angle and the detection signal for the overlapping conduction angle to supply a rotating magnetic field to rotate the rotor. While driving, a part of the driving current overlaps at least once for switching the energization of the stator coil required for rotation of the rotor. At this time, the gate circuit of the drive circuit outputs an energization switching signal based on the detection signals from the main magnetic sensitive element and the complementary magnetic sensitive element, and the switching circuit of the drive circuit outputs a plurality of stator coils based on the output signal of the gate circuit. The drive current of is sequentially switched. As described above, the drive current having a predetermined conduction angle is sequentially switched to the plurality of stator coils, and a part of the drive current overlaps at the time of switching. Is reduced and noise is reduced.

[Embodiment] FIGS. 1 and 2 show an embodiment of the present invention.
The same parts as those in FIGS. 4 and 5 are designated by the same reference numerals. Second
In the figure, (6) is a rotor, and this rotor (6) has a four-pole main magnetic pole (2) as a permanent magnet around the laminated core,
The 12-pole auxiliary pole (7) is formed by being attached or magnetized independently. As shown in FIG. 2, the auxiliary pole (7) is formed by arranging N poles and S poles, which are alternately divided into three equal parts, at positions corresponding to the four poles of the main magnetic pole (2). Has been done. In FIG. 1, (8) is a stator core, and stator coils (4r) (4s) (4t) having an electrical angle of 120 ° are arranged on the stator core (8). Further, on the stator core (8), a Hall IC (H ₁ ) as a main magnetically sensitive element that discriminates between the N pole and the S pole of the main magnetic pole (2) and outputs a detection signal for a switching conduction angle.
(H ₂ ) and (H ₃ ) are arranged with an electrical angle of 120 °, and a magnetic field sensitive sensor that discriminates between the north pole and the south pole of the auxiliary pole (7) and outputs a detection signal for overlapping conduction angle. Hall IC (H ₄ ) as an element A position that forms an electrical angle θ (for example, electrical angle 150 °, which is twice the geometrical angle 75 °) from the Hall IC (H ₃ ) toward the Hall IC (H ₂ ). It is arranged at the corresponding position. In FIG. 1 and FIG. 3 which will be described later, the main magnetic pole (2) and the auxiliary magnetic pole (7) are shown on the inner peripheral side and the outer peripheral side of the rotor (6) for convenience of description, but as shown in FIG. Has been formed. (10) is a drive circuit. This drive circuit (10)
Is a gate circuit (1 which outputs an energization switching signal based on a detection signal from the Hall IC (H ₁ ) (H ₂ ) (H ₃ ) (H ₄ ).
1) and a switching circuit (12) for switching the drive current of the stator coils (4r) (4s) (4t) based on the signal from the gate circuit (11).

The gate circuit (11) is the Hall IC (H ₁ ) (H ₂ )
NOR gates (13) (14) (15) (16) that function as inverters that invert the detection output of (H ₃ ) (H ₄ ) and the Hall ICs (H ₁ ) (H ₂ ) (H ₃ ) (H NOR gate (17) which outputs a conduction switching signal to the bases of the transistors (Q ₁ ) to (Q ₆ ) of the switching circuit (12) based on three outputs selected from the detection output of ₄ ) and its inverted output. (18),
(19) (20), (21) (22), (23) (24), (25)
It consists of (26), (27) and (28). Three transistors (Q ₁ ) (Q ₃ ) of the switching circuit (12)
The collector of (Q ₅ ) is connected to the common motor power supply terminal (30), and the emitters are the stator coils (4t) (4s) respectively.
It is connected to one end of (4r) and to the collectors of the remaining three transistors (Q ₂ ) (Q ₄ ) (Q ₆ ), and these transistors (Q ₂ ) (Q ₄ ) ( Q ₆ )
The emitter of is grounded. The stator coil (4
The other ends of t) (4s) and (4r) are connected by a circle.

Next, the operation of the above embodiment will be described with reference to FIG.
For convenience of explanation, when the rotor (6) is in the position shown in FIG. 1 is used as a reference (geometrical rotation angle = 0 °), the Hall IC
(H ₁ ) (H ₂ ) (H ₃ ) (H ₄ ) are the north poles of the rotor (6) (3rd
The shaded area in FIG. 3B) and the S pole (non-shaded area in FIG. 3B)
When it is determined that “1” (hatched portion in FIG. 3 (a)) and “0” (non-hatched portion in FIG. 3 (a)) are output, the transistors (Q ₁ ) to (Q ₆ ) are turned on. , The off state is represented by a shaded portion and a non-shaded portion (FIG. 3 (c)).

(B) Hall IC when the rotation angle of the rotor (6) is 0 °
Since the detection output of (H ₁ ) switches from “0” to “1” and the detection output of Hall ICs (H ₁ ) to (H ₄ ) is “1010”, the transistor (Q ₅ ) turns off. From "on" and the transistors (Q ₁ ) (Q ₄ ) are on. Therefore, the stator coil (4r) (4s) (4
A drive current in the “+”, “−”, and “+” directions is applied to t) for excitation, and the rotor (6) is rotated in the direction of the arrow. Here, the “+” direction of the drive current indicates a case where the drive current flows toward the point ◯ of the connection portion, and the “−” direction indicates a case where the drive current flows in the opposite direction. Therefore, the overlap conduction angle corresponding to the "on" time of the transistor (Q ₁ ) indicated by the cross-hatched portion in FIG. 3 (c) is 30 ° (geometric angle 15 ° is multiplied by the number of pole pairs (2)). Expressed in electrical angles.
The same applies hereinafter), and the drive current of the stator coil (4t) overlaps.

(B) When the rotor (6) rotates and the rotation angle reaches 15 °,
Since the detection output of Hall IC (H ₄ switches from “0” to “1” and the detection output of Hall ICs (H ₁ ) to (H ₄ ) is “1011”, the transistor (Q ₁ ) is "OFF". Therefore, "+" is added to the stator coil (4r) (4s).
A drive current in the "-" direction is supplied to excite and rotate the rotor (6) in the direction of the arrow. At this time, the drive current only flows from the stator coil (4r) to (4s), so that the drive current does not overlap.

(C) In the same manner, each time the rotation angle advances by 15 °, _one of the Hall ICs (H ₁ ) to (H ₄ ) will be displayed as shown in Fig. 3 (a).
One of the detection output is switched, the Hall IC (H ₁₎ detection output of ~ (H ₄₎ is "1001", "1000", since the switch ... to,
Transistors (Q ₁ ) to (Q ₆ ) as shown in FIG.
One of them switches from "off" to "on" or from "on" to "off". Therefore, two or three of the stator coils (4r) (4s) (4t) are excited and the rotor (6) rotates in the arrow direction as shown in FIG. 3 (b). At this time, the rotation angle is 30 ° to 45 °, 60 ° to 75 °
Driven by an overlapping conduction angle of 30 ° corresponding to the "on" time of one of the transistors (Q ₁ ) to (Q ₆ ) represented by the cross hatched area in Fig. 3 (c) corresponding to the range of °, ... The currents overlap.

(D) When the rotation angle reaches 180 ° (corresponding to the electrical angle of 360 °), the state returns to the state when the rotation angle of (a) is 0 °, and the energization switching is cycled once.

In the above embodiment, the Hall IC (H ₄ ) is replaced with the Hall IC (H ₃ )
From the Hall IC (H ₂ ) to the electrical angle θ of 150 ° (geometric angle of 75 °), the overlapping conduction angle was set to 30 °. The invention is not limited to this, and the overlapping conduction angle can be changed by changing the electrical angle θ. For example, electrical angle θ = 150 °
By setting + θa (| θa | <30 °), the overlap conduction angle can be changed to 30 ± θa. That is, θa = +
When it is set to 15 °, the detection output of Hall IC (H ₄ ) is the third
As shown in the figure (a) by the dotted line, and the states of the transistors (Q ₁ ) to (Q ₆ ) of the switching circuit (12) are also shown by the dotted line in the figure (c), the overlap conduction angle is 30. °
It becomes + 15 °. When θa = −15 °, the overlapping conduction angle is 30 ° −15 °. Also, by changing the ratio of the lengths of the N pole and the S pole of the auxiliary pole formed on the rotor along the rotation direction without changing the position of the Hall IC (H ₄ ) or by setting the electrical angle θ. The overlap conduction angle can be changed in combination with the change.

In the above embodiment, the auxiliary magnetic pole is composed of a predetermined number of magnetic poles in which different magnetic poles are alternately arranged at the positions corresponding to the respective main magnetic poles, and the number of magnetic poles is determined by the main magnetic pole when the rotor rotates once. The sensitive element outputs a detection signal for switching conduction angle, and the driving current is switched in all the energization switching, which is the same as the total number of switching (12 times in the above embodiment) for switching energization of the drive current flowing through the stator coil by this detection signal. I tried to make a part of the electric current overlap the predetermined conduction angle,
The present invention is not limited to this, and the detection signal for causing a part of the drive current to overlap may be output to the complementary magnetic sensing element at least once for switching the energization of the stator coil required for one rotation of the rotor. Good. For example, the auxiliary pole is formed by a predetermined number (for example, three) of magnetic poles in which different magnetic poles are alternately arranged only at a position corresponding to one of the plurality of main magnetic poles, and the stator required for one rotation of the rotor by the drive circuit. One of the coil energization switching circuits (for example, 12 times) (when three auxiliary poles of S, N and S poles are formed corresponding to only one S pole of the main pole) or three times ( If three auxiliary poles of N, S and N poles are formed corresponding to only one N pole of the main pole, a part of the driving current may be made to overlap.

In the above-described embodiment, the present invention is applied to the inner rotor type brushless DC motor, but it can also be applied to the outer rotor type or flat type brushless DC motor.

In the above embodiment, the brushless DC motor having three phases and four poles has been described, but it goes without saying that the number of phases and the number of poles are not limited to three phases and four poles.

[Advantages of the Invention] As described above, the brushless DC motor according to the present invention is
In addition to the main magnetic pole of the rotor, a supplementary magnetic pole is provided, and the main magnetic pole detects the rotational position of the rotor and outputs a detection signal for the switching conduction angle. And a complementary magnetic sensing element that outputs a detection signal for overlapping conduction angles is provided, and a drive current having a predetermined conduction angle is applied to a plurality of stator coils based on the detection signals from the main magnetic sensitive element and the complementary magnetic sensitive element. A drive circuit is provided that supplies the currents that are sequentially switched and supplies a part of the drive currents at the time of switching the energization, and the drive circuit is composed of a gate circuit and a switching circuit. Therefore, the structure of the drive circuit is simplified, the conventional microcomputer for calculating the overlap conduction time is not required, and the cost of the brushless DC motor can be reduced.

[Brief description of drawings]

1 and 2 show an embodiment of the brushless DC motor according to the present invention. FIG. 1 is a circuit connection diagram and FIG.
FIG. 4 is a perspective view of a rotor, FIG. 3 is a timing diagram for explaining the operation of the present invention, FIG. 4 is a circuit connection diagram of a conventional example, and FIG. 5 is a perspective view of a conventional rotor. (2) …… Main pole, (4r) (4s) (4t) …… Stator coil, (6) …… Rotor, (7) …… Complementary pole, (10)…
… Drive circuit, (H ₁ ) (H ₂ ) (H ₃ ) …… Hall IC (main magnetic sensitive element), (H ₄ ) …… Hall IC (complementary magnetic sensitive element),
(Q ₁ ) to (Q ₆ ) …… Transistor for switching.

Claims (2)

[Claims] 1. A rotor having a plurality of main magnetic poles and a plurality of auxiliary magnetic poles, a main magnetic sensitive element for detecting a rotational position of the rotor by the main magnetic pole, and outputting a detection signal for a switching conduction angle; A complementary magnetic sensing element that detects the rotational position of the rotor by a magnetic pole and outputs a detection signal for overlapping conduction angles,
A drive current having a predetermined conduction angle is sequentially switched and supplied to a plurality of stator coils based on detection signals from the main magnetically sensitive element and the supplementary magnetically sensitive element, and a stator coil required for one rotation of the rotor is supplied. And a drive circuit which supplies a part of the drive current in an overlapping manner at least once for switching the energization. The drive circuit is based on the detection signals from the main magnetic sensitive element and the supplementary magnetic sensitive element. A brushless DC motor, comprising: a gate circuit that outputs an energization switching signal by a switching circuit; and a switching circuit that sequentially switches drive currents of the plurality of stator coils based on an output signal of the gate circuit. 2. The auxiliary pole is composed of a predetermined number of magnetic poles in which different magnetic poles are alternately arranged at positions corresponding to respective main magnetic poles, and the number of magnetic poles is the total number of energization switching of the stator coil required for one rotation of the rotor. 3. The brushless DC motor according to claim 1, wherein the brushless DC motor has the same configuration as the above, and a part of the drive current is overlapped by a predetermined conduction angle in all switching of energization.