JP2545797B2 - Brushless motor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a two-phase brushless motor device.

[Outline of Invention]

The present invention provides a position detecting element by forming a pulse signal similar to the output signal of the position detecting element from the induced voltage induced in the first and second stator coils when the rotor magnet rotates. Instead, two-phase bidirectional energization is performed.

[Conventional technology]

In the conventional two-phase bidirectional energization type brushless motor,
Two Hall elements are used to detect the rotor magnet position.
They are arranged with a phase difference of ° (electrical angle), and the drive current is controlled based on a predetermined timing formed from the output signal of this Hall element. However, the provision of the Hall element causes an increase in component cost, an increase in the number of wirings, and complicated adjustment of the mounting position. Further, the need for a space for mounting the hall element has hindered the miniaturization of the brushless motor.

Therefore, for example, Japanese Patent Laid-Open Nos. 56-33953 and 58
As shown in Japanese Patent No. 172994, a brushless motor that does not require a position detection element has been proposed. In these prior arts, the timing of energization switching (phase switching) is defined based on the level relationship of the three-phase induced voltages induced in the stator coil by the rotor magnet. That is,
Since it is necessary to use the induced voltage that is not affected by the voltage generated by the drive current, the timing control of the current-carrying section of one phase is performed by controlling the level of the induced voltage of the stator coils of the other two phases that are not energized. It is based on the relationship becoming a predetermined level relationship.

[Problems to be solved by the invention]

The brushless motor shown in the prior art is a one-way energization system that supplies a driving current to each stator coil in only one direction in order to detect a mutual level relationship of induced voltages. Therefore, the utilization efficiency of the coil is lower than that of the bidirectional energization method, and it is difficult to realize a compact and high-power brushless motor.

Therefore, an object of the present invention is to provide a bidirectional energization type brushless motor device which does not require a position detecting element.

[Means for solving problems]

According to the present invention, the first and second stator coils La and Lb and the first and second stator coils La and Lb, which are arranged with a phase difference of 90 degrees in electrical angle, are provided with a predetermined gap. A brushless motor having a rotor magnet 23 disposed therein, and the rotor magnet 23 when the rotor magnet 23 rotates.
According to the first and second stator coils La and Lb, the zero cross points of the induced induced voltages Ea and Eb having the phases corresponding to the rotation phase of the rotor magnet 23 and the corresponding edges to the zero cross points are respectively generated. The first pulse signal generating means for generating the two pulse signals Pa, Pb and the first and second pulse signals Pa, Pb output from the first pulse signal generating means are each approximately 45 in electrical angle. Second pulse signal generating means for generating third and fourth pulse signals Ha and Hb delayed by a degree,
Based on the third and fourth pulse signals Ha, Hb from the second pulse signal generating means, the first and second stator coils La,
Drive currents are applied to the first and second stator coils La and Lb in periods other than the range of about 90 degrees in electrical angle centered on the zero-cross points of the induced voltages induced in Lb. Drive pulse signals P1 to P8 for forming different drive pulse signals and switching control is performed by the drive pulse signals P1 to P8 from the drive pulse signal generation means, and drive currents are supplied to the first and second stator coils La and Lb. A brushless motor device comprising: a switching circuit 1 for energizing both directions in both directions; and a start pulse signal generating means for supplying a start pulse signal to a second pulse signal generating means when the brushless motor is started.

[Action]

The zero-cross point of the induced voltage is detected during the period when the drive current is not supplied. By delaying the detected pulse signals Pa and Pb having an edge at the zero-cross point by 45 degrees in the D flip-flops 3 and 4, pulse signals Ha and Hb equivalent to the output signal of the position detection element are formed. The switching transistor is driven based on the pulse signals Ha and Hb, and bidirectional energization is performed. The timing of switching drive is defined by detecting the zero-cross point of the induced voltage. In the vicinity of the zero cross point of the induced voltage, the drive current does not flow in the stator coil, and the timing is accurately detected from the induced voltage of one stator coil. Further, since the rotor magnet 23 is stationary at the time of startup, no induced voltage is generated. Therefore, the drive current is forcibly generated by the start pulse.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, La and Lb represent stator coils arranged so as to have a phase difference of 90 ° in electrical angle. An example of a flat-opposed brushless motor to which the present invention can be applied will be described with reference to FIGS. 4 to 7.

In FIG. 4, reference numeral 21 denotes a rotary shaft, and a rotor yoke 22, a rotor magnet 23, and a back yoke 24 that rotate together with the rotary shaft 21 are provided. Rotor magnet
As shown in FIG. 5, 23 is magnetized with 8 poles. Reference numerals 25 and 26 denote bearings, and 27 denotes a sleeve for disposing the bearing and the stator. Screw on sleeve 27
The stator coils La and Lb are attached by 28 and 29. The stator coils La and Lb are laminated and, for example, the stator coil La has the configuration shown in FIG.

The stator coil La is composed of eight coils La1 to La8 formed so as to have a distribution of 45 ° in mechanical angle. Since the winding directions of these coils La1 to La8 are aligned so that the energization directions are the same as those of the adjacent coils in the radial direction, the sides for torque generation are combined to form eight sides. The other stator coil Lb has the same structure as the stator coil La (not shown), and is arranged below the stator coil La.
However, a phase difference of 90 ° in electrical angle (22.5 ° in mechanical angle) is provided between the stator coils La and Lb. In the conventional brushless motor, the position detection elements 30a and 30b shown by the two-dot chain line in FIG. 6 are required.

The stator coil has a structure shown in FIG.
As shown in, the stator coil La consisting of coils La1 and La2
The stator coil Lb including the coils Lb1 and Lb2 may be arranged in the same plane. Further, in the present invention, the rotor magnet is not limited to the 8-pole magnetized but may be the 6-pole magnetized rotor magnet. At the time of this 6-pole magnetization, as shown in FIG. 7B, the coils La1, La2, L each having a distribution of 120 ° in mechanical angle are provided.
A stator coil composed of b1 and Lb2 is used. Further, the present invention can be applied not only to the plane facing type but also to the cylinder facing type brushless motor.

The stator coils La and Lb of the above brushless motor are first
As shown in the figure, it is connected to the switching circuit 1. As will be described later, the switching circuit 1 is composed of switching transistors, and ON / OFF of the switching transistors is controlled by drive pulses P1 to P8 from the drive pulse generation logic 2. Further, the switching circuit 1 is provided with a level comparator, and the level comparator compares the levels of the induced voltages Ea and Eb induced in the stator coils La and Lb with the common potential, and the induced voltage is equal to the common potential. The switching circuit 1 generates pulse signals Pa and Pb which become “H” (high level) when the level is higher than the level and “L” (low level) when the levels are opposite.

The pulse signals Pa and Pb from the switching circuit 1 are supplied to the D flip-flops 3 and 4 as respective data inputs, and are also supplied to the EX-OR gate (exclusive OR gate) 5. The output signal of the EX-OR gate 5 is supplied to the mono-multi 6, and the output signal on the negation side of the mono-multi 6 is supplied as a clock input to the D flip-flops 3 and 4. At the output terminal of the mono-multi 6, the period is'L 'from the rising edge of the output signal of the EX-OR gate 5 to T,
50% pulse signal is obtained. This time T is set equal to the period of 45 ° (electrical angle) during steady rotation.

The activation pulse from the activation pulse generation circuit 7 is supplied to the set terminal and the reset terminal of each of the D flip-flops 3 and 4. The starting pulse from the starting pulse generating circuit 7 is supplied to the set terminals and the reset terminals of the D flip-flops 3 and 4 when the motor is started, that is, for a predetermined time (for example, 0.1 sec) from the start. The output signals of the D flip-flops 3 and 4 become high level when a start pulse is supplied to the set terminals, and the output signals become low level when a start pulse is supplied to the reset terminals.
The activation pulse generation circuit 7 is composed of a logic circuit or a microprocessor.

In the D flip-flops 3 and 4, the pulse signals Pa and Pb are delayed by the time T, respectively, and the pulse signals Ha and Hb are output from the D flip-flops 3 and 4. The pulse signals Ha and Ha are supplied to the drive pulse generation logic 2. In the drive pulse generation logic 2, drive pulses P1 to P8 synchronized with the pulse signals Ha and Hb are formed.

FIG. 2 shows an example of the switching circuit 1. The switching circuit 1 is provided with four pairs of PNP transistors and NPN transistors. PNP transistor 11,13,15,
The emitter of 17 is connected to a power supply terminal 10 to which a positive DC voltage is supplied, and the emitters of NPN transistors 12, 14, 16 and 18 are grounded. Drive pulses P1, P3, P5, and P7 are supplied to the bases of PNP transistors 11, 13, 15, and 17, respectively, and NPN transistor 1
Drive pulses P2, P4, P6, and P8 are supplied to the bases of 2, 14, 16, and 18, respectively.

Collector of PNP transistor 11 and NPN transistor 12
Collectors are commonly connected and the common connection point is the stator coil
Connected to one end of La. The collector of the PNP transistor 13 and the collector of the NPN transistor 14 are commonly connected, and the common connection point is connected to the other end of the stator coil La. The collector of the PNP transistor 15 and the collector of the NPN transistor 16 are commonly connected, and the common connection point is connected to one end of the stator coil Lb. PNP transistor 17 collector and NPN
The collectors of the transistors 18 are commonly connected, and the common connection point is connected to the other end of the stator coil Lb.

PNP transistors 11, 13, 15, 17 are turned on while drive pulses P1, P3, P5, P7 are each'L ', and NPN transistor 12 while drive pulses P2, P4, P6, P8 are each'H'. , 14,16,18 turns on.
Depending on the ON / OFF state of this switching transistor,
The current path of the drive current flowing through the stator coils La, La is defined.

In addition, both ends of the stator coil La are level comparators 19
, And both ends of the stator coil Lb are connected to the input terminal of the level comparator 20. A pulse signal Pa is obtained from the level comparator 19, and a pulse signal Pb is obtained from the level comparator 20.

FIG. 3 shows the waveform of each part of one embodiment of the present invention. FIG. 3A shows induced voltage waveforms induced in the stator coils La and Lb, respectively, when the rotor magnet has a steady rotation speed. This induced voltage waveform is induced by the sine-wave magnetized rotor magnet 23 and does not include the voltage component generated by the drive current. In FIG. 3A, the solid line waveform shows the waveform of the induced voltage Ea induced in the stator coil La, and the broken line waveform the induced voltage in the stator coil Lb.
The waveform of Eb is shown. These induced voltages Ea and Eb have a phase corresponding to the rotation phase of the rotor magnet 23 and have a phase difference of 90 ° with each other.

From the level comparators 19 and 20, pulse signals Pa and Pb having edges that coincide with the zero-cross points of the induced voltages Ea and Eb, respectively.
(FIG. 3B) is obtained. These pulse signals Pa and Pb are EX-O
It is supplied to the R gate 5 and is supplied by the EX-OR gate 5 to FIG. 3C.
The pulse signal shown in is formed. This pulse signal is 90
The level reverses every °. The mono-multi 6 is triggered by this pulse signal, and as shown in FIG. 3D, a pulse signal whose level is inverted every period T corresponding to 45 ° is obtained at the negative output terminal of the mono-multi 6.

In the D flip-flops 3 and 4, the pulse signals Pa and Pb are delayed by the time T by the output pulse signal of the monomulti 6, respectively, and the pulse signals Ha and Hb shown in FIG. 3E are formed. These pulse signals Ha and Hb are drive pulse generation logic 2
Drive pulses P1 to P8 are obtained from the drive pulse generation logic 2.

FIG. 3F shows drive pulses P1 to P8. The drive pulses P1 and P4 turn on the transistors 11 and 14 while the induced voltage Ea is at a high level in the positive direction, and a current flows through the stator coil La. Next, the drive pulses P5 and P8 turn on the transistors 15 and 18 while the induced voltage Eb is at a high level in the positive direction, and a current flows through the stator coil Lb. Next, the induced voltage
During a period in which Ea is at a high level in the negative direction, the drive pulses P2 and P3 turn on the transistors 12 and 13, and a current flows through the stator coil La. Next, in the period in which the induced voltage Eb is in the negative direction at a high level, the drive pulses P6 and P7 drive the transistors 16 and 17
Turns on, and a current flows through the stator coil Lb. In this way, a drive current sequentially flows through the stator coil, and bidirectional energization is performed. The range (± 90 °) around the respective zero-cross points of the induced voltages Ea and Eb shown in FIG. 3A is a period in which the drive current does not flow through the corresponding stator coil. Therefore, the rotational phase of the rotor magnet 23 can be accurately detected from the zero cross point. Further, the pulse signals Ha and Hb respectively obtained from the D flip-flops 3 and 4 are signals equivalent to the output signal of the Hall element for position detection in the conventional brushless motor.

Further, since the induced voltage Ea, Eb is not generated when the rotor magnet 23 is stationary, at the time of starting, a starting pulse for forming a two-phase pulse signal similar to the pulse signals Ha, Hb for a predetermined time. It is generated from the start pulse generation circuit 7. By this start-up pulse, the rotor magnet 23 is forcibly pulled into a predetermined rotation phase, and the rotation direction is set to a predetermined direction.

〔The invention's effect〕

According to the present invention, the drive signal can be formed without providing a magnetic or optical position detecting element. Therefore, various problems caused by providing the position detection element (increased cost of parts, increased number of wires, complicated adjustment of mounting position, securing mounting space for position detection element)
Can be solved. Further, since the present invention is a bidirectional energization system, a small size and high output brushless motor is realized according to the present invention. Further, according to the present invention, since the drive current does not flow near the zero cross of the induced voltage, there is an effect that the position of the rotor magnet can be accurately detected.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a connection diagram of an example of a switching circuit in the embodiment of the present invention, and FIG. 3 is a waveform of each part used for explaining the operation of the embodiment of the present invention. FIG. 4 is a cross-sectional view of an example of a brushless motor to which the present invention can be applied, FIG. 5 is a plan view of an example of a rotor magnet, and FIGS. 6 and 7 are plan views used to explain a rotating determinator coil, respectively. Is. Description of main symbols in the drawings La, Lb: Stator coil, 1: Switching circuit, 2: Drive pulse generation logic, 3,4: D flip-flop, 6: Monomulti, 7: Start pulse generation circuit, 23: Rotation Child magnet, 19,
20: Level comparator ,.

Claims (1)

(57) [Claims] 1. A first and a second stator coil arranged with a phase difference of 90 degrees in electrical angle and a rotor magnet arranged with a predetermined gap between the first and the second coil. A brushless motor having: and a generated induced voltage having a phase corresponding to the rotation phase of the rotor magnet to each of the first and second stator coils by the rotor magnet when the rotor magnet rotates. First pulse signal generating means for generating first and second pulse signals each having an edge corresponding to a zero-cross point, and first and second pulse signals output from the first pulse signal generating means. On the other hand, second pulse signal generating means for generating third and fourth pulse signals respectively delayed by an electrical angle of about 45 degrees, and third and fourth pulse signals from the second pulse signal generating means. The first and second electric coils around the zero-crossing points of the induced voltages respectively induced in the first and second stator coils based on the signal Drive pulse signal generating means for forming a drive pulse signal for supplying a drive current to each of the stator coils, and switching control by the drive pulse signal from the drive pulse signal generating means. A brushless circuit comprising: a switching circuit for supplying a drive current to the stator coil in both directions; and a start pulse signal generating means for supplying a start pulse signal to the second pulse signal generating means when the brushless motor is started. Motor device.