KR100312293B1 - Two-phase Bi-DC Motor with Single-Hole Element - Google Patents

Abstract

The present invention relates to a two-phase BLDC motor having a single Hall element. In particular, the rotor can be driven without a dead point while using a single position detection element, and the driving circuit is extremely simple, and the magnet is disposed efficiently. A BLDC motor with high efficiency and low torque ripple.

According to the present invention, a stator is formed of 2n coils and a plurality of coils connected by a two-phase driving method are arranged at equal intervals on a reduced phase support, an axis on which both ends are rotatably supported, and a stator and a predetermined direction in the axial direction. Supported on the shaft with an air gap and the same number of N pole and S pole magnets are alternately arranged on the reduction phase support, and 2n magnets form n N pole and S pole magnet pairs, respectively The magnet pairs are arranged at the same distance from each other, and the rotor whose ratio of distances from the center of the N pole magnets to the centers of the S pole magnets on both sides is set to 1: 1.4, so that the 2n N pole and S pole magnets can be detected. The magnetic poles of the rotor are detected by the magnetic flux generated from the 2n auxiliary magnets annularly disposed on the rotor with the same length as the magnetic poles corresponding to the respective N pole and S pole magnets and the rotating auxiliary magnets. A single hall element for generating a rotation position signal, and switching control means for alternately energizing the stator coils connected in a two-phase drive method in accordance with the rotation position signal.

Description

Two-Phase BCD Motor with Single Hall Element

The present invention relates to a two-phase brushless DC (BLDC) motor having a single Hall element, and in particular, the drive circuit is extremely simple because the rotor can be driven without a dead point while using a single position detection element. The present invention relates to a BLDC motor with high efficiency and low torque ripple due to an efficient magnet arrangement.

BLDC motors are generally classified into core type (or radial type) and coreless type (or axial type) having a cup (cylindrical) structure according to whether or not they have a stator core.

The core type BLDC motor has an inner magnet type composed of a cylindrical stator coiled with a coil and a rotor made of a cylindrical permanent magnet in order to have an electromagnet structure on a plurality of protrusions formed on the inner circumference, or a plurality of protrusions on which the stator is formed on the outer circumference. The coil is wound up and down in the upper and lower directions, and is classified into an external magnet type in which a rotor is formed of a cylindrical permanent magnet magnetized to a multipole.

Since the core type BLDC motor has a structure in which the magnetic circuit is symmetrical in the radial direction about the axis, it has the advantages of low vibration noise, suitable for low speed rotation, and good torque, whereas yoke during stator fabrication It has the disadvantage of high material loss and high capital investment in mass production. In addition, the structure of the stator and the rotor is complicated, the thinning is disadvantageous, there is a difficulty in increasing the efficiency and there is a problem that cogging torque occurs.

On the other hand, in the conventional coreless BLDC motor proposed to improve the disadvantages of the core type BLDC motor, a rotor composed of an annular magnet and a yoke is fixedly coupled to the rotating shaft, and a plurality of stator coils are provided on a printed circuit board (PCB). It has a structure in which a rotating shaft is coupled to a stator formed by winding through a bearing.

The coreless BLDC motor includes a magnetic body in the up / down direction having the same direction as the axial direction between a rotor composed of a plurality of sets of magnets integrally and a stator composed of a stator coil generating a plurality of sets of electromagnetic forces disposed thereunder. Since the circuit is formed, even if the buffer spring is inserted between the bearings due to the suction or repulsive force of the stator and the uneven magnetization of the stator, the vibration in the axial direction is structurally large.

In addition, this axial vibration causes resonance of the entire system during the motor-driven rotational drive, thereby increasing the rotational noise. Therefore, the efficiency of the entire motor at high speed is good in terms of no loss, while vibrating noise is synthesized in the rotational noise to cause abnormal noise.

As a result, the material loss can be minimized, mass production is good, and the thickness and size can be reduced compared to the core type BLDC motor, resulting in low cost and high efficiency, but it has a fatal flaw that the noise is generated by axial vibration during rotation. .

Accordingly, the present applicant has proposed a double rotor / stator type coreless BLDC motor capable of canceling axial vibrations generated at the time of rotor rotation and increasing torque by more than two times. The motor has a double stator structure in which a plurality of wound stator coils are mounted on left and right sides of a PCB in the middle of the first and second double rotors, thereby forming a magnetic circuit having a symmetrical structure with respect to the stator and the rotor rotation axis as a whole. Accordingly, the double rotor structure cancels the suction or repulsive force applied to the first and second rotors by the stator to minimize the axial vibration of the rotor.

On the other hand, the present applicant has proposed an improved invention which can achieve durability and reduction of production cost by constructing the stator of the above-described symmetrical double rotor / stator type coreless BLDC motor into a single body by insert molding. have. The above-described BLDC motor is briefly described below with reference to FIG. 1.

As shown in the drawing, the conventional BLDC motor has an outer circumferential portion 67 of the stator 51 extending up and down in the middle of the upper / lower cases 71A and 71B, and is coupled therebetween to form a cylindrical case.

The upper rotor 73A and the lower rotor 73B having a magnet-divided multipole arrangement structure with a predetermined air gap on the upper and lower portions of the stator 51 are rotated through the central bushings 75A and 75B. Fixedly coupled to

When the BLDC motor is driven in three phases, each of the rotors 73A and 73B alternates with 12 magnets 81A and 81B, that is, six disc-shaped N pole magnets 81A and six disc-shaped S pole magnets 81B. The circumferential portion is supported by a support 79 formed of a non-magnetic material such as PET, nylon 66 or PBT and integrally formed with the bushings 75A and 75B, and the annular magnet yokes 83A and 83B are integrally formed on the back surface. It is attached to form a magnetic circuit for the twelve magnets 81A and 81B.

On the other hand, a position detecting auxiliary magnet 85 is attached above the magnet yoke 83A of the upper rotor 73A, and the auxiliary magnet 85 is fixed to the inner circumference of the upper case 71A. Are arranged opposite to the three Hall elements (H1-H3) (89). In addition, one side of the control PCB 87 is provided with a female connector 91 to which the upper terminal 63 of the stator 51 is press-fitted.

Upper and lower bearings 93A and 93B are fixedly installed at the centers of the upper case 71A and the lower case 71B, and the rotary shafts 77 of the rotors 73A and 73B are provided through the bearings 93A and 93B. This is rotatably supported. In addition, the stator 51 is a nine square bobbin coil or bobbinless coil (55) (L1-L3) by the insert molding method (Insert molding) with the auxiliary printed circuit board (PCB) (57) by a resin insulating material It is shaped into a disc.

In the conventional three-phase drive BLDC motor, twelve N-type and S-type magnets 81A and 81B are disposed at equal intervals on the rotor, and the stator has nine coils 55 at equal intervals. If the rotor and the stator are shown in a plan view as shown in FIG.

The stator is connected to the y-wire method as shown in Fig. 4 after nine coils 55 are allocated to each of the u, v, w phases are connected in series, and by the three position detection Hall elements (H1-H3) When the position of the rotor is detected in sequence, the switching transistor 97 is driven by the three-phase logic IC 95 so that a current flows in two coils sequentially among the three-phase stator coils L1-L3 at predetermined angles. .

In other words, in the three-phase full-wave drive type BLDC motor, the three phase end points are connected to each other, and from the viewpoint of one phase, the current flows in one direction and then flows in the opposite direction and then turns off. .

Therefore, the three-phase full-wave driving method requires three Hall elements, three-phase logic ICs, and six switching transistors, resulting in a high circuit cost.

On the other hand, the two-phase full wave driving method requires two Hall elements and four switching transistors, and the two-phase half wave driving method requires two Hall elements and two switching transistors. However, in the two-phase half-wave driving method, there is a dead zone or dead point, so it is necessary to take special countermeasures to avoid this when the motor is started. Also, the organic electromotive force is low and the motor efficiency is low. Ripple also appears large.

Accordingly, the present invention has been made in view of the problems of the prior art, and its object is to drive the rotor without a dead point while using a single position detection element, so that the driving circuit is extremely simple and high efficiency due to the efficient magnet arrangement It is to provide a BLDC motor with small torque ripple.

1 is an axial sectional view showing a structure of a double rotor type BLDC motor to which the present invention can be applied;

2 is an explanatory diagram showing an arrangement relationship between a rotor and a stator in a conventional BLDC motor;

3 is a graph showing the organic electromotive force according to the electric angle in the three-phase drive motor,

4 is a switching driving circuit diagram of a conventional three-phase driving BLDC motor,

5 is an explanatory diagram showing an arrangement relationship between a rotor and a stator in a BLDC motor according to the present invention;

6 is a connection diagram of a two-phase driving stator coil applied to the present invention,

FIG. 7 is a graph showing the relationship between the rotor and the stator linearly according to the electric and mechanical angles to explain the electromagnetic force acting between the rotor and the stator when the rotor rotates in FIG.

8 is a graph showing the organic electromotive force according to the electric angle in the two-phase drive motor according to the present invention,

9 is a schematic plan view of the rotor showing the arrangement relationship between the magnet of the rotor and the auxiliary magnet for position detection according to the present invention;

10 is a switching driving circuit diagram for a two-phase BLDC motor using a single Hall element according to the present invention.

<Description of the symbols for the main parts of the drawings>

1A1-1A5: N pole magnet 1B1-1B5: S pole magnet

5A1-5A5: A phase coil 5B1-5B5: B phase coil

10: rotor 10A: rotor support

15A-15J: Auxiliary magnet 20: Hall element (H)

51: stator 55: coil

57: auxiliary PCB 59: stator body

63: connecting terminal 67: the stator outer peripheral

71A / 71B: Upper / Lower Case 73A / 73B: Upper / Lower Rotor

75A / 75B: Bushing 77: Shaft

79: support 81A, 81B: magnet

83A / 83B: magnet yoke 85: auxiliary magnet

87: control PCB 89: Hall element

91: connecting terminal 93A / 93B: upper / lower bearing

95: three-phase logic IC 97: switching transistor

In order to achieve the above object, the present invention consists of a stator is composed of 2n coils and a plurality of coils connected in a two-phase driving method is arranged at uniform intervals on the reducing phase support, and the shaft is rotatably supported at both ends; The shaft is supported on the shaft with a predetermined air gap in the axial direction, and the same number of N poles and S pole magnets as alternating coils of the stator are alternately disposed on the reducing support, and the 2 n magnets include n N poles and A pair of S pole magnets, each pair of magnets being arranged at the same distance from each other, and a rotor having a distance ratio from the center of the N pole magnets to the sides of the S pole magnets adjacent to each other set to 1: 1.4, and the 2n N 2n auxiliary magnets arranged in an annular shape on the rotor with the same length as each magnetic pole corresponding to each of the N and S pole magnets so as to detect the pole and S pole magnets, and the rotating auxiliary magnets. Is a switching control means for alternately energizing a single Hall element for detecting the magnetic pole of the rotor by the magnetic flux and generating a rotor position signal of the rotor, and a stator coil connected in a two-phase driving method according to the rotation position signal. It provides a two-phase half-wave drive type BCD motor, characterized in that configured.

Here, each of the auxiliary magnets is set from the middle of the N-pole and S-pole magnet pairs of the rotor to the intermediate point of the adjacent magnet pair, and each arc angle is 360 / 2n.

The rotation position signal generated from the Hall element is a square wave signal having a duty of 50%, and energization between the first phase coil and the second phase coil connected by the two-phase driving method is performed every 180 degrees.

The switching control means includes a first transistor for energizing the first phase coil connected by the two-phase driving method when the high level signal of the rotation position signal generated from the hall element is applied, and the low level signal of the rotation position signal. It may be configured as a second transistor for energizing the second phase coil connected in the two-phase driving method when is applied.

As described above, in the present invention, the number of magnets (number of poles) of the rotor and the number of coils of the stator are equal, but the intervals between the magnets are arranged at different intervals, and the two-phase half-wave driving method has a positive value of organic electromotive force. The switching drive is performed in the part, so that the rotor can be driven without dead point while using a single position detecting element such as a hall element, so that the drive circuit is extremely simple, and a high efficiency and low torque ripple motor can be obtained. do.

EXAMPLE

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

5 is an explanatory view showing the arrangement relationship between the rotor and the stator in the BLDC motor according to the present invention, Figure 6 is a connection diagram of the two-phase drive stator coil applied to the present invention, Figure 7 is a rotation of the rotor in Figure 5 In order to explain the electromagnetic force acting between the rotor and the stator in the graph, the graph of the rotor and the stator linearly according to the electric angle and the machine angle is shown. 9 is a schematic plan view of a rotor showing an arrangement relationship between a magnet of a rotor and a sensing magnet for position detection according to the present invention, and FIG. 10 is a two-phase BLDC motor using a single Hall element according to the present invention. Switching drive circuit diagram.

First, the motor of the new structure of the present invention is applied to any type of motor such as a BLDC motor having a single rotor / single stator or a double rotor / single stator or a BLDC motor having a double stator / single rotor structure if the two-phase half-wave driving method is used. . Therefore, if necessary, the present invention will be described with reference to a BLDC motor having a double rotor / single stator structure of FIG. 1.

First, Figure 5 shows the arrangement relationship between the rotor and the stator in the BLDC motor according to the present invention, the stator includes 2n stator coils (5A1-5A5, 5B1-5B5), the rotor is the same 2n rotors as the stator coil Magnets 1A1-1A5 and 1B1-1B5 (where n is a positive integer).

As shown in FIG. 9, the rotor 10 of the present invention has a structure in which a plurality of sets of N pole magnets and S pole magnets are alternately inserted into a support 10A made of a disk-shaped nonmagnetic material as a whole.

Here, when n is 5, the rotor magnet has five N-pole magnets 1A1-1A5 and five S-pole magnets 1B1-1B5 alternately arranged on the rotor support 10A, and the stator coil is shown in FIG. In this way, the wiring structure is connected by two-phase driving method, in which five A-phase coils 5A1-5A5 and five B-phase coils 5B1-5B5 are connected in series, and the other ends are connected in common, and a supply voltage is applied thereto. To achieve.

In this case, five A-phase coils 5A1-5A5 and five B-phase coils 5B1-5B5 are alternately arranged one by one as shown in FIG. 5, and in this case, bobbin type or bobbinless type as shown in FIG. 1 as necessary. The coil may be integrally molded in the form of a disk by a resin insulating material in an insert molding method or may be formed as a structure in which a coil is attached to a PCB substrate.

The stator coils 5A1-5A5, 5B1-5B5 are arranged on the same circumference at equal intervals, and in the ideal case, the distance between the coil and the coil is zero (0), and the rotor magnets 1A1-1A5, 1B1-1B5 Are arranged in opposing relations with two adjacent coils, but the arrangement intervals are not the same as described below.

A graph showing linearly the arrangement of the stator coils 5A1-5A5, 5B1-5B5 and the rotor magnets 1A1-1A5, 1B1-1B5 in FIG. 5 is shown in FIG. 7.

As shown in FIG. 7, the width of one side of the coil 5 wound is represented by two columns of the grid graph, and each of the coils 5A1 and 5B1 is represented by six spaces, and each magnet 1A1 and 1B1 indicated by hatching. The width of is set to 3 spaces. Here, in the ideal case, the distance between the coil 5A1 and the coil 5B1 is zero (0).

Since the coils 5A1 and 5B1 are fixed and the magnets 1A1 and 1B1 of the rotor move in the actual structure, the magnets 1A1 and 1B1 move to the right one by one as they proceed from positions 0 to 12.

In the case of a 10-pole, 10-coil motor, the electrical angle = mechanical angle × number of poles ÷ 2, so the distance between the stages in the position movement of the rotor magnets (1A1, 1B1) from rotor position 0 to position 12 is 30 degrees between the electrical angle and the machine. It is set at 6 degrees each. In this case, the spacing between each magnet is set differently by 2 and 4 spaces. Therefore, the ratio (X, Y) of the distance (X, Y) from either magnet center to the magnet centers on both sides is determined as 5: 7 = 1: 1.4.

This non-uniform arrangement of magnets is very different from the arrangement of magnets at even intervals of the conventional BLDC motor shown in FIG.

When the magnet of the rotor and the coil of the stator are disposed relative to each other and move relative to each other, an induced voltage (EMF) E having a relation as shown in Equation 1 below is obtained in the coil winding according to Fleming's right hand law. This organic electromotive force (E) is very important for understanding the characteristics of the motor.

[Equation 1]

E = Blv

Where B is the flux density of the magnet, l is the length of the coil leads lying in the magnetic flux, and v is the relative speed between the magnet and the coil leads.

In the above equation 1, when the motor rotates at a constant speed, the coil winding and the size of the magnet are constant, so the length (l) of the coil lead and the relative speed (v) between the magnet and the coil lead have a constant value. Depending on the location of the windings and how far the coil windings lie in the magnetic flux, the organic electromotive force (E) value is determined, which substantially means a change in the magnetic flux density (B) value.

On the other hand, the force (F) causing the rotational motion of the motor is generally defined by the relational expression as shown in Equation 2 according to Fleming's left-hand law.

[Equation 2]

F = Bil

Here, i is a current flowing through the coil lead.

As can be seen from Equation 2, the force (F) is directly affected by the magnetic flux density (B) value. However, since the magnetic flux density (B) value is changed according to the N and S poles of the magnet, the organic electromotive force (E) and force (F) values also change accordingly. The rotor can be rotated in a certain direction only by continuously changing or interrupting the current and then flowing it again.

Here, the time point for changing the flow direction of the current can be known through the organic electromotive force (E) curve. When the organic electromotive force E has a positive value and a negative value, the direction of the current flowing should be reversed.

The magnets of the rotor appear to alternate between the N and S poles. Generally, the magnets do not increase the value of the organic electromotive force (E) simply because the magnets overlap the coils unconditionally. In FIG. 7, for example, when the poles of the magnets 1A1 and 1B5 opposite to each other are positioned at both winding sections of the coil 5A1 as shown in the rotor positions 9 to 11, the value of the organic electromotive force E is reinforced. This is because the cross section of the two coils 5A1 windings is actually the cross section of one coil winding connected in a ring shape.

The organic electromotive force curve of the motor of the present invention obtained in consideration of all these situations is shown in FIG. 8. The two-phase (A- and B-phase) organic electromotive curves (A, B) of the present invention shown in FIG. 8 form a sinusoidal curve in which the positive and negative values are symmetrical because the arrangement of the magnets is asymmetric. It can be seen that the curve is asymmetrical from the general two-phase organic electromotive force curve.

In addition, in the conventional two-phase half-wave driving method, since there is a fire start area or a fire start point (dead point) at 90 degrees or 180 degrees, respectively, special measures must be taken to avoid this when the motor is started.

However, in the present invention, portions having positive values of the organic electromotive force curves A and B of the two phases are symmetrically staggered while occupying 210 degrees of 360 degrees of electric angles, respectively. Therefore, the stator coils L11: 5A1-5A5 and L12: 5B1- of each phase in the portion where the two-phase organic electromotive force curves A and B overlap, that is, the portions O1-O4 where the size of the organic electromotive force E becomes 1 The motor can be rotated in a constant direction by alternately switching the application of current to 5B5) using the switching drive circuit shown in FIG.

That is, in the two-phase half-wave driving method according to the present invention, only a portion having a positive value of organic electromotive force (A, B) hatched in FIG. 10 is energized so that there is no dead point as well as torque ripple. It can be seen that is less than the conventional two-phase half-wave driving method.

In the case of the general three-phase propagation driving method, the three end points of the u, v, and w phases are connected to each other, and from the viewpoint of one phase, the three processes of repeating the current flow in one direction and then in the opposite direction are repeated. In the case of single phase (half wave driving) as in the present invention, the current flows only in one direction.

In this case, in the present invention, only the portion having the positive value of the organic electromotive force (A, B) is energized so that the organic electromotive force is relatively large as compared with the conventional driving method, which indicates that the current flowing through the circuit is very high. It becomes small and proves that motor efficiency is high.

It is necessary to detect the correct switching position (O1-O4) for energizing switching to the A-phase and B-phase stator coils (L11: 5A1-5A5 and L12: 5B1-5B5). To this end, in the present invention, as shown in FIG. 9, auxiliary magnets 15A-15J are installed at equal intervals inside the main magnets 1A1-1A5 and 1B1-1B5 of the rotor 10, and corresponding stators or By arranging a single Hall element IC 20 (H) at the same circumferential position of the control PCB 87, an accurate switching point is obtained.

The arc angle θ of each of the auxiliary magnets 15A-15J is the middle of the adjacent magnet pairs from the middle of each of the N and S pole magnet pairs 1A1, 1B1 to 1A5, 1B5 located adjacent to each other of the rotor 10. Set to a point, the arc angle θ has 360 / 2n.

Accordingly, the Hall element IC 20 detects the stimulus of the auxiliary magnets 15A-15J and generates a constant pulse. In this case, since the interval between the N pole magnets 15A-15E and the S pole magnets 15F-15J of the auxiliary magnets 15A-15J is set to be different from that of the main magnets 1A1-1A5, 1B1-1B5, The generated pulse is a square wave pulse signal having a duty of 50%.

In the present invention, a single Hall element IC 20 is used. In this case, the current supplied to the stator coils L11 and L12 of each phase can be alternately applied using the switching driving circuit shown in FIG. When the switching drive circuit of the present invention detects the auxiliary magnets 15A-15J of the rotor 10 by the Hall element IC 20, a square wave pulse signal of a high level (H) is periodically output therefrom. It is applied to the transistor TR1. As a result, when the transistor TR1 is turned on, the stator coil L11 of the A phase is energized. After that, when the low level signal L is applied from the Hall element IC 20, the transistor TR1 is turned off, the transistor TR2 is turned on, and a current flows through the stator coil L12 of the B phase. As a result, the rotor 10 rotates by obtaining a continuous rotational force. In FIG. 10, the resistors R1-R4 are bias voltage setting resistors for the switching transistors TR1 and TR2.

Therefore, the switching driving circuit of the present invention has a very simple structure that does not require a logic IC as compared with the conventional switching driving circuit shown in FIG.

In addition, when the present invention is applied to, for example, a double rotor structure as shown in FIG. 1, the auxiliary magnet is attached to the back of the magnet yoke 83A using a rubber magnet without being embedded through the support of the rotor. It is also possible to install the Hall element 20 on the control PCB 87 opposed to this.

In the present invention, the rotor is composed of a plurality of N-type and S-type magnet pairs, and the distance with other magnet pairs is disposed at the same distance as twice the distance between the N-type and S-type magnets forming the magnet pair. In other words, since the two magnets are arranged at a predetermined distance, the organic electromotive force is high, and therefore, when the two-phase half-wave driving is adopted, the current consumption is small and high efficiency can be achieved.

In the present invention, the number of magnets of the magnet of the rotor, the coil of the stator, and the auxiliary magnets may be 2n, respectively, where n is determined as an appropriate value of 3 or more in proportion to the size of the motor determined according to the performance of the motor desired by the user. It is preferable to be.

As described above, in the present invention, the number of magnets (number of poles) of the rotor and the number of coils of the stator are equal, but the intervals between the magnets are arranged at different intervals, and the two-phase half-wave driving method has a positive value of organic electromotive force. The switching drive in the part allows the rotor to be driven without dead point while using a single position detection element, which makes the drive circuit extremely simple and provides a high efficiency and low torque ripple motor.

As described above, the principle of the present invention is a BLDC motor composed of a single rotor / single stator when adopting a two-phase half-wave driving method, a BLDC motor of the double rotor / single stator or a double stator / single rotor structure. Applicable to

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments and is not limited to the spirit of the present invention. Various changes and modifications can be made by those who have

Claims (5)

The first phase coil, the second phase coil, and the first reduced phase support, each of the first phase coil and the second phase coil are composed of n coils, and the first phase coil and the second phase coil are two phases. A n-pole and S-pole pair of magnets, the same number of stator coils as the stator coils, which are connected in a driving manner and arranged at equal intervals on the first reduced-phase support, the shafts rotatably supported at both ends, and the stator coils; a magnetic yoke for forming a magnetic circuit together with n-pole and n-pole magnets, n-pole and n-pole magnets, and n-pole and n-pole magnets alternately arranged It is composed of a two-ring-like support, is supported on the shaft with the stator and a predetermined air gap in the axial direction, and each of the N pole and S pole magnet pairs are arranged at the same distance from each other, at the first center of the N pole magnet The ratio of distances between the second pole and the third center of the south pole magnet adjacent to the north pole magnet is 1: 1.4. A rotor to be set, and 2n auxiliary magnets disposed annularly on the rotor with the same length as the magnetic poles corresponding to the respective N and S pole magnets so as to detect the 2 n N and S pole magnets; A single hall element for detecting the magnetic pole of the rotor by the magnetic flux generated from the rotating auxiliary magnet and generating the rotation position signal of the rotor, and alternately energizing the first and second phase coils according to the rotation position signal And a distance between the adjacent magnet pairs is set as twice the distance between the N pole and the S pole magnets constituting the magnet pair. 2. The two-phase half-wave according to claim 1, wherein each of the auxiliary magnets is set from the middle of the N pole and the S pole magnet pairs of the rotor to an intermediate point of the adjacent magnet pair, and each arc angle is 360 / 2n. Driven BCD motor. The two-phase half-wave drive type BCD motor of claim 2, wherein the auxiliary magnet is embedded in the support of the rotor or installed on the rear surface of the magnet yoke. The rotating position signal generated by the Hall element is a square wave signal having a duty of 50%, and the energization between the first phase coil and the second phase coil connected by the two-phase driving method is 180 degrees. Two-phase half-wave drive type BCD motor, characterized in that each made. The switching control means for energizing the first phase coil connected by the two-phase driving method when the high level signal of the rotation position signal generated from the hall element is applied. A two-phase half-wave driving type BCD motor comprising a first transistor and a second transistor for energizing a second phase coil connected by the two-phase driving method when a low level signal of a rotation position signal is applied. .