JPH04236154A - Three-phase half-wave driver for oscillation type brushless motor - Google Patents

Abstract

PURPOSE:To produce oscillation without modifying the structure of motor unit by modifying the conduction timing in a brushless motor employed as an oscillation source for pager, for example. CONSTITUTION:A reference phase detecting means 7 compares an induced voltage with a power supply voltage and produces reference phase pulses Puo, Pvo, Pwo by detecting the rotor position as a phase. A reference phase pulse shift circuit 6 produces conduction switching signals OUTu, OUTv, 0UTw, which are lagged behind a normal conduction switching signal, based on thus produced reference phase pulses Pou, Pvo, Pwo. A difference is set between the torques generated at the time of starting conduction and at the time of ending conduction by modifying the conduction timing of stator winding. Variation of rotational speed takes place in the rotor due to variation of torque at the time of switching the conduction winding thus causing oscillation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase half-wave drive device for a brushless motor used as a vibration source in pagers and the like.

0002

2. Description of the Related Art In today's information society, the demand for pagers, such as pagers, as portable communication devices is increasing year by year. However, since the pager is a notification device that uses sound, the sound could be transmitted to people other than the specified person, and could even be a nuisance. Therefore, methods have been proposed that notify only specific people by generating vibrations, and some of these methods use small DC motors as the vibration generation source.

Conventionally, there are two types of devices using a DC motor as a means for generating vibrations, and these will be explained below with reference to the drawings.

A first conventional example has a structure in which a weight 41 is fixed to a rotating shaft 42 of a motor 40, as shown in FIG. Further, the weight 41 is fixed eccentrically with respect to the rotating shaft as shown in FIG. The operation of the motor configured as described above will be explained below. First, when the motor 40 rotates, the weight 41 attached to the rotating shaft 42 rotates while generating an eccentric load. At this time, a shift occurs between the rotation center of the motor 40 and the rotation center of the center of gravity of the weight 41, causing the motor to vibrate in the radial direction.

A second conventional example is one in which the shape of the rotor 51 is modified as shown in FIG. In this conventional example, when the rotor 51 rotates, it generates an eccentric load due to its own deformation, causing vibrations in the motor.

[0006] The above two methods are common in that they mechanically generate an eccentric load on the rotating part to make the rotation unbalanced and generate vibration.

[0007]

[Problems to be Solved by the Invention] However, in the conventional configuration as described above, the weight part is attached externally, which impedes the reduction in size and weight of the motor body, and the use of deformed parts. Therefore, the number of processing steps increases,
This has the problem of being complicated.

The present invention solves the above-mentioned conventional problems, and instead of generating vibrations by the mechanical motor structure as described above, vibrations are generated by energizing the stator windings of a brushless motor. The object of the present invention is to provide a three-phase half-wave drive device that can perform the following steps.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the three-phase half-wave drive device for a brushless motor of the present invention detects the rotational phase of the rotor before the stator winding energization switching circuit. The device has a three-phase half-wave drive circuit configuration having an energization switching pulse changing means for shifting the phase reference pulse obtained by the means.

0010

[Operation] With the above-described structure, the present invention can detect the position of the rotor magnet and, based on this signal, create an energization timing that is delayed from the original energization timing. However, by setting the energization angle to the drive coils arranged at 120 degrees electrical angle to each other at 120 degrees, which is the same as normal, the torque received by the rotor at the start and end of energization was adjusted to the normal energization timing. There is a difference in the torque at the start of energization and at the end of energization.

[0011] Therefore, the moment the energization is switched, the torque received by the rotor changes, and the rotational speed of the rotor also changes.

[0012]By cyclically switching the drive current with such energization timing, the torque received by the rotor is intentionally changed when the current-carrying winding is switched, thereby creating fluctuations in the rotational speed of the rotor and generating vibrations. be.

[0013]

[Embodiment] Fig. 1 is a circuit configuration diagram of a three-phase half-wave drive device for a brushless motor according to an embodiment of the present invention, and Fig. 2 is a diagram showing the operating signal waveform of the brushless motor and the torque waveform received by the rotor at this time. It is. Since the method of generating the energization switching signal differs depending on the direction of rotation of the motor, forward rotation will be explained here.

In FIG. 1, Eu, Ev, and Ew are the induced voltages generated in the stator winding of the motor due to the rotation of the motor, and in FIG. 2, Cu, Cv, and Cw are the results of comparing the induced voltage with the power supply voltage Vcc. Yes, Puo, Pvo, Pw
o is the pulse that detected the rise of Cu, Cv, and Cw, respectively; Pu, Pv, and Pw are Pwo and Pw, respectively.
This is the same as uo and Pvo.

Furthermore, OUTu, OUTv, and OUTw are signals that become high level when pulses Pu, Pv, and Pw are generated, respectively, and become low level when another pulse is generated.

Next, the individual signals will be explained. As the motor rotates, three-phase induced voltages Eu and E swing around the power supply voltage Vcc as shown in Figure 2 in the stator winding of the motor.
v, Ew are generated.

[0017] Cu, Cv, and Cw are U phase, V phase, and Cw, respectively.
The comparator 8 shown in FIG.
This is a rectangular wave signal generated by comparing the signals a, 8b, and 8c with the power supply voltage Vcc.

The rising edges of the rectangular wave signals Cu, Cv, and Cw are detected by differentiating circuits 9a, 9b, and 9c, and reference phase pulses Puo, Pvo, and Pwo are output.

The reference phase pulse is the timing at which the induced voltage of the motor intersects with the power supply voltage Vcc, and indicates the reference phase of the rotation of the rotor.

The reference phase pulses Puo, Pvo, and Pwo are input to the reference phase pulse shift circuit 6 and are shifted to U-phase, V-phase, and
The current switching pulses are shifted to W-phase energization switching pulses Pu, Pv, and Pw.

[0021]

[Table 1]

The energization switching pulses Pu, Pv, and Pw are input to the energization switching circuit 5. The energization switching circuit 5 is composed of flip-flops 10a, 10b, and 10c. P
When u is input to the energization switching circuit 5, the flip-flop 1
0a is set. Next, when Pv is input, flip-flop 10b is set and flip-flop 10a is reset. Further, when Pw is input, the flip-flop 10c is set and the flip-flop 10b is reset. Similarly, this operation is repeated and the energization switching circuit 5 outputs three-phase energization switching signals OUTu, OUTv, and OUTw.

Po is a signal that is output every time the induced voltages Eu, Ev, Ew interlink with the power supply voltage Vcc, that is, every 120 degrees in electrical angle, and therefore the energization switching signal OUTu
, OUTv, and OUTw are also signals output every 120 degrees in electrical angle.

The energization switching signals OUTu, OUTv, OUTw of each phase generated as described above are power-amplified by the energization switching signal amplifying circuit 4, and are then applied to the driving transistors 1a, 1.
b, 1c to the base of the motor stator winding 2a.
, 2b, and 2c, the motor continues to rotate.

Next, the energization timing under these conditions and the torque received by the rotor at that time will be explained. FIG. 3 shows the appropriate timing of the induced voltage and the energization switching signal in three-phase half-wave drive, and the torque waveform that the rotor receives at this time.

At this time, the torque Td applied to the rotor is expressed by the following equation, where the torque constant of the motor is Kt.

[0027]

[Math 1]

Therefore, when the current i is kept constant, Td changes only depending on the electrical angle θ. At this time, the mechanical angle at which the rotor magnet rotates by exactly one magnetized pair of magnets corresponds to an electrical angle θ=360°. Further, the torque becomes maximum when the electrical angle θ=90°, that is, the mechanical angle is rotated by exactly 1/2 the magnetized pole of the magnet, and the magnitude of the torque at this time can be expressed as the following equation.

[0029]

[Math 2]

In addition, since the energization angle to the stator winding is 120°, when the energization start angle is set as θ', the torque Tdbgn received by the rotor at the start of energization, the torque Tdend received by the rotor at the end of energization, and Tdbgn. Tden
The difference Tdsub in d is expressed by the following equation.

[0031]

[Math 3]

[0032]

[Math 4]

[0033]

[Math 5]

As can be seen from a comparison between FIGS. 2 and 3, the energization switching signals OUTu, OUTv, and OUTw in the embodiment have energization timings that are delayed by 30 degrees in electrical angle than the appropriate energization timings.

As can be seen from FIG. 2 and (Equation 3) and (Equation 4), for a certain winding at an appropriate timing, Tdb
Start energizing when gn=0.5Tdmax,
An operation is performed in which energization is terminated when Tdend=0.5Tdmax. On the other hand, the energization timing in the example is Tdbgn=0.866T
When dmax is reached, energization is started and Tdend=0.
The energization is switched at a time that is significantly different from the appropriate timing, such as terminating the energization when the

Therefore, when appropriate energization switching is performed, the fluctuation Tdsu of the torque received by the rotor when switching the energized winding is
While b is 0, in the example, the rotor is 0.866Tdmax in the rotational direction at the moment of switching the energized winding.
This will result in a difference in torque.

As expressed by equation (1), the torque received by the rotor changes sequentially as the rotor rotates while the winding is energized, but this change is smooth. In this embodiment, the change in torque that occurs when the energization is switched is rapid, and as a result, the rotation of the rotor changes due to the torque fluctuation at the moment when the energization is switched.

[0038] Further, such rotational speed fluctuations occur every time the energized winding is switched, and therefore the rotation of the rotor causes regular rotational speed fluctuations.

As a result, the rotor generates vibration in the direction of rotation. As described above, according to this embodiment, by changing the timing of energization to the stator windings, it is possible to generate vibrations in the motor without using mechanical means that have been conventionally required.

[0040]

Effects of the Invention The present invention provides an energization switching pulse changing means for changing the reference signal for the energization timing to the stator windings from an appropriate one, thereby delaying the energization timing from the appropriate one. Vibrations that were previously generated mechanically can now be generated electrically. Therefore, there is no need for specially added parts or deformation of parts, the structure of the motor and the shapes of the parts can be simplified, and the motor can be made lighter, thinner, shorter and smaller.

Furthermore, as mentioned above, the part that generates vibrations in the motor is a three-phase half-wave drive device external to the motor, so if it is designed as a brushless motor, it may have a flat or cylindrical shape. It is possible to generate vibrations without any vibration.

[Brief explanation of the drawing]

FIG. 1: Three brushless motors in an embodiment of the present invention
Circuit configuration diagram of phase and half wave drive device

[Fig. 2] Current flow and torque waveform diagram for induced voltage in the embodiment of the present invention

[Figure 3] Current flow and torque waveform diagram for induced voltage of a normal brushless motor

[Figure 4] Structural diagram of a conventional vibration type motor

[Figure 5] Structural development diagram of another conventional vibration type motor

[Explanation of symbols]

1a, 1b, 1c drive transistors 2a, 2b, 2
c Stator winding 3 Power supply terminal 4 Energization switching signal amplification circuit 5 Energization switching circuit 6 Reference phase pulse shift circuit 7 Reference phase detection means 40 Flat type motor 41 Weight 42 Rotating shaft 50 Vibration type flat motor 51 Rotor

Claims (1)

[Claims] 1. 3n (n is a natural number of 1 or more) three-phase stator windings, three drive transistors connected to the stator windings, and reference phase detection means for rotor rotation; A three-phase half-wave drive device for a brushless motor, comprising an energization switching pulse changing means that changes the energization section to the three-phase stator winding, and an energization signal switching circuit that switches the energization switching pulse to the drive transistor.