JPS59156180A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To suppress motor sound and vibration by varying the amplitude value of the output signal of conversion signal generating means varying in response to a position detection signal in cooperation with an exciting current value, thereby smoothly converting the exciting current. CONSTITUTION:When a command signal V1 (which is proportional to i1) is large to supply large exciting current Ij like at the starting or accelerating time of a motor, the amplitude WPP (which is proportional to i6) of the output signals (d)-(f) of conversion signal generator 19 varying in response to the output signals (a)-(c) of a position detector 18 is reduced to smooth the current conversion, thereby preventing the motor sound and vibration. Further, when the command signal V1 is small like the stable state of the speed control of the motor to supply small exciting current Ij, the amplitude WPP of the output signals (d)- (f) of a conversion signal generator 19 is increased to reduce the angle width of current conversion, thereby preventing the supply of te exciting current to unnecessary phase to prevent the torque pulsation sand the efficiency decrease.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brushless DC motor in which the excitation current to a coil is switched by a transistor.

Conventional configuration and problems Brushless DC motors detect the rotational position of the roller l (motor moving part) and switch the excitation current to multiphase coils according to the detected output, thereby achieving a specified force direction. The rotor is driven to rotate. The excitation current to the coil is switched by controlling activation/inactivation of a plurality of output transistors. Conventionally, switching the excitation current has caused the following problems.

(1) When viewed from each coil, since a rapid pulse current flows, an electromagnetic force is generated in a pulsed manner due to the current and the magnetic flux of the rotor magnet. As a result, the coil vibrates due to the reaction of the pulsed electromagnetic force, causing coil squeal and core vibration. In other words, motor noise and motor vibration were a problem. In particular, in a planar opposed motor in which a circular or fan-shaped air-core coil is arranged opposite to the magnetic pole of a flat magnet, it is difficult to suppress the vibration of the coil because the coil is loosely fixed.

(2) A spike voltage is generated due to the inductance of each coil and the sudden surge current. The voltage is generated in a direction that interrupts the flow of the pulse current, transiently saturates the output transistor completely at the beginning of the current flow, and causes pulsations in the excitation current. The pulsations in the excitation current result in pulsations in the electromagnetic force, causing motor noise and motor vibration.

OBJECTS OF THE INVENTION The present invention takes these points into consideration and provides a bluntless DC motor in which excitation current is switched smoothly and motor noise and vibrations are suppressed.

Structure of the Invention The branless DC motor of the present invention comprises: a motor movable part having a field magnet; A multiphase coil interlinked with the magnetic flux of the magnet, a plurality of output transistors that supply excitation current to the coil, a position detection means for detecting the position of the motor movable part, and an output signal of the position detection means. a switching signal generating means for obtaining an output signal that changes in response to a change in output signal; a command signal generating means; activating the output transistor corresponding to the output signal of the switching signal generating means; distribution means for supplying an excitation current to the coil in response to the switching signal generation means; , the output transistor is configured to control activation/deactivation of the preceding output transistor by the output of the selection means, and to change the amplitude value of the output signal of the switching signal generation means in conjunction with the value of the excitation current. 1.Explanation of an Embodiment Fig. 1 shows an embodiment of the present invention. This shows the city air circuit diagram. In Figure 1, αη is the rotor (motor moving part)
The field magnet attached to 9, Q21 u3 circle is the 3-phase coil installed in the stator, u! '1ltl
G (17) i”j 3-phase coil t, 121 C1
a (14) K Output transistor that supplies the excitation current I,,I,,I, θυ is a Hall element (71) that senses the magnetic flux of the magnet (lυ) 17a (position detector consisting of a wire, 01 is a position detector (g) Output signal (al
(bl (signal for switching the current path in response to cl) (dl'(el (f) 'c A switching signal generator that outputs a signal V, which commands the magnitude of the excitation type piot. The command signal generator to obtain, Qυ is the switching signal (dl (e) (f)
This is a distributor that distributes and controls the face of the output transistor (IEQ) according to the output transistors. Also, (4) and (2) are DC power supplies, respectively.

Next, its operation will be explained. The speed detector 11 of the command signal generating means is, for example, a generator of the same wave number and
It is composed of a voltage converter, and when the rotation speed of the motor is slow, the output is shifted to a smaller value, and when the rotation speed reaches a predetermined value, the initial voltage is increased. The output of the speed detector ('31+) is input to the current converter diagram, where it is compared with a predetermined voltage level due to the resistance Z, and an output current it is determined according to the difference voltage between the two.
(sink current) is obtained.

FIG. 2 shows a specific configuration example of a current converter diagram.

The input voltage is a differential transistor (104X105X106
) (107) and the resistor (102X103), and depending on the voltage difference, the current of the constant current source (101) ■1
1 is distributed to the collector side. Collector current 112 and It
s is compared by 1-transistor (108X109)', and the difference current '+3'l□ is outputted through the current mirror (transistor (1, 1, 0Xiil)), and the current 1. aspirate.

The output 11 of the current converter S・1) is the output of the transistor g0(
361 (41), is input to a current mirror circuit of resistors [381+391 times 2, and a current proportional to i is +2. +
5 is output from the collector side of transistors (371 and (41)) (resistance f38) +391 [If 42 are equal, 12=i6=i, % current 12 is the resistance (
40) into the command signal V1. That is, if the value of the resistance is R4o, then V,=R4°-12=R4o・1.・・・・・・
・・・・・・・・・・・・ (1).

The output current 15 (i5=i,) of the transistor (41) of the switching signal generator (19) is the diode +43++4
Pine, transistor (46), resistance t+4) (471(
7) It is reversed by the current mirror and becomes current i4.

When i3 is small, it is i4-'3, and when i3 is large, it is vD45/'R47 in i4. Here (,y,
n 45-O, 7V is the forward voltage of the diode (45), R47 is the value of the resistor), and the resistance diagram and (47
) are assumed to be equal. Current I of constant current source (48)
Current mirror with 5 input (transistor +49)
(50 order, resistance φυ) A current i4 is caused to flow through the resistor so.
As a result, the output current 16(l″j
l.

16=I5-i4. Here, I5 is made larger than vD45/R47.

Current i6 is supplied as a common emitter current of the transistors. On the base side of each transistor, there is a Hall element (71) for the position detector) @f:!
The output of I (al (bl (c)) is applied. The Hall element (7υ (73σ4) detects the magnetic flux of magnet αυ, and as the magnet αD rotates, it outputs a three-phase analog signal (at (bl (cl) (See Fig. 4, 9)) Normally, the magnetic field detection sensitivity of the Hall element is small, and the amplitude value of its output voltage is 50 mVP.

That's about it. Output (at) of Hall element <7υf■ (c)
(bl' (according to the relative voltage difference of cl, transistor 67)) The common emitter current i6 is reversed by the collector current 17 of each collector current register Gη by the current mirror of the transistor (61). q, resistance (
A signal for switching the current path (switching signal) (d) is obtained at 6→. At $54, a switching signal (el) is generated by the transistor's collector current 18, and a switching signal (fl) is generated by the transistor's collector current (i).
(See Figure 4 (b)). Switching signal (di (el (f'
The common potential of l is given by a resistor (b) and a transistor. Moreover, the switching signal (dl (el (f
The amplitude value W9 of ) is determined by the current i6 and the value of the resistor 01... (the resistance values are equal), and becomes WPPkiR62°i6.v/P, the output i of the Iti current converter (34),
It changes depending on the value, but when 11 is small, it is about 200mV.
, t + is approximately 100 mV. In other words, the switching signal (
The amplitude value of di (el (f)) is changed.

The command signal (1) is applied to the normal input terminal of the current controller (6υ) of the distributor (C), and is compared with the output (2) of the current detector (C) applied to its inverted input terminal, and the difference between the two is calculated. Current i, corresponding to . Output.

FIG. 13 shows a specific example of the configuration of the current controller (c).

According to the input voltage difference, the current 1.4 of the constant current source (121) is distributed to the collector chambers ai, 5 and 116, and its and '+6
The difference current '+6'15 is compared with the transistor (128X129)
) and amplified with 1. Output via current mirror of transistor (132x1331 resistor (134x135),
Current 'to' is flowing out.

Output current i of current controller 01). is the common emitter current of the selector. An output voltage (d) (el (fl)) of the switching signal generator Q9 is applied to each base terminal of the differential transistor (c) of the selector (b).

The switching signals (d) (e) (f) are the three-phase analog voltage corresponding to the rotational position of the magnet αυ (Hall element (i'l) < 7 (c) output signal (a) (bl (c)) The differential transistor (c) (c) (c) (c) operates differentially according to the base voltage difference, and distributes the common emic current to each collector current.

As a result, the collector current of the differential transistor with the lowest base voltage is the largest, and the collector currents of the other differential transistors have values corresponding to their base voltage differences. The relational expression is i=i+i+i ・・・・・・・・・・・・・・・
・・・・・・・・・・・・ (4) Ink
t m d e=VT#n(i7xk) ・・・・・・・・・
・・・・・・・・・・・・・・・・・・ (5) e-f
=VT7? n(irr/ip)・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (6) f-d-V
, /? n(ik/1ffl)・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (7) Here 1. ik, i, and fuku are differential transistors 0φ (
F) (C) collector current, VT = 14T/q
(k: Boltzmann constant, T: absolute temperature, q: amount of electron charge). In other words, due to the analog change in the switching signal (d) (el (f)) caused by the rotation of the magnet (6), the collector current of the differential transistor (see J&I) changes. 11.1z, Fuku is (4
) to (7).

Each collector current ik, l of the transistor Zeng (c)
,, iIT+ is the output transistor (15) uti u
Each Vane current of the force is increased by the current amplified excitation current I.
,,Ih,I, are output and supplied to the coil output 0304J. Combined excitation current I to coil (2) +130
, =I, +I, +1 , is the resistance of the current x output wheel (c)
is detected as a voltage drop V2 (ignoring the base current of the output transistor), and is input to the current controller 6v.

As a result, a feedback loop is formed by the current controller 8υ, the selector θ, the output transistor U:))40η, and the current detector QF1, and the loop is connected to the coil @U■H (7) 'J
JJ Whetstone 1. J pM I is set to a value corresponding to the command signal V.

In reality, control is applied so that the Vl shown in the figure and ■2 are equal, I, = Ig + Ih + I, = V, /R8, ... Song...
...Song/Song (8). Here, R87 is the resistance (c)
Calculate with the value of .

In addition, the capacitor (C)'' is attached for phase compensation (to prevent oscillation) of the feedback loop mentioned above. Also, the resistor 0119 connected in parallel to the coil (C13 (14)) and the capacitor (A) - ( The series circuit (g) is intended to reduce the spike voltage caused by switching of the energizing path.

Now, assuming that the current amplification degrees of output transistors aa and aa (17) are equal, ■g-hFF'ik ・・・・・・・・・・-
・・・・・・・・・・・・・・・ (9) Ih-h
Oh, ・・・・・・・・・・・・・・・・・・・・・
...
...becomes an α sword. (9) From the ~0υ formula to 1 +Iz,
Find llIn, substitute it into equations (5) to (7), and transform the equation to get I, /I, = exp((de-e)/VT) ---
---Song-----0311 "11/Ih=exp((e-f)lVT) ---
-= (13Jg/I, =exp((fd)/'VT
) −−・=−−Q4J. That is, the current 1.' according to the differential voltage of the switching signal (di (el (f))
, Ih, I, are supplied to the coil U aa (14) of each phase. Also, according to equation (8), the composite excitation current I, = I,
+I, +I.

is a value corresponding to command signal ■1.

Figures 4(a) to 4(f) show waveform diagrams of various parts as the magnet αυ rotates. Figure 4C (a) shows the waveform of the output signal (al tbl (cl) of the position detector), and Figure 4 (B) shows the switching signal (d) of the switching signal generator ().
(e) The waveform of (f) is shown, and Fig. 4 (c) shows the excitation current I,
1. ．． I.

The waveform of the composite excitation current I is shown in FIG.

Excitation current for each phase I,, I5. I is the switching signal (al
(el (Switches smoothly in response to gentle changes in fl.

The angular width Z in exchange for 9J (current value is from 90% of 1.
The angular width at 0%) is the switching signal (d) tel (f
) and the amplitude value WPP. That is, when W and P are thick, Z becomes small, and when C and WP are small, Z becomes large. If Z becomes small, the excitation current I, , I, , I, to the coil will have a parnu-like rise and fall, which will induce coil vibration and cause motor noise and motor vibration. 1, the spike voltage will also increase. On the other hand, when Z is large, excitation current is supplied to coils of unnecessary phases, resulting in pulsation of the power and a decrease in efficiency.

Therefore, in this embodiment, the command signal V, (proportional to i) is larger than that at the time of starting and accelerating the motor, and the excitation is large.
fL style 1. When supplying the νJ switching signal generator, the amplitude value wPP (proportional to i6) of the output signals (d), (e), and (f) of the νJ switching signal generator is made small to smooth the current switching and prevent motor noise and vibration. In addition, when the command signal V1 is small and a small excitation current ■ is supplied, such as in a stable state of motor speed control, the output signal (dl
(El .

FIG. 5 shows an electric circuit diagram showing another embodiment of the present invention. In this example, each output transistor (10θ()μη
Insert the current source (201X202) (203) between the base 7 and the emitter (between the base and one side terminal of the power supply) and connect it to the output of the differential transistor ring (c) ■ of the selector gauze. + I z + 1 m, the output transistor of the phase whose current value is relatively small is surely turned off. Current source (201X, 202X20
3) the current value of the current controller width) of the output current l,. (common emitter current of the six selectors) (by setting the current value to about 1/15 of 110), it is possible to reliably turn off the excitation current to unnecessary phases and to switch the excitation current. does not have a negative impact on

In addition, in this embodiment, the current converter l of the command signal generator
A capacitor (205) and a resistor (204) are connected to the output side of 34).
) to form a low-Pane filter, the command signal ■1. and the switching signal (di (el (f)) are made to change slowly.
,Ih,I.

The sudden change in voltage is eliminated, and the generation of spike voltage is suppressed. °The capacitor (205) is connected between the collector side of the transistor (41) and the power supply terminal to configure a low-pane filter, and the switching signal (di (el (
It is also possible to prevent only sudden changes in fl.

The overall operation of the embodiment shown in FIG. 5 is similar to the operation shown in FIG. 1 described by Mil, and the explanation thereof will be omitted.

In addition, in each of the above-mentioned embodiments, the oral transmission speed of the motor is controlled, but the invention is not limited to such a case, and the output torque of the motor may be controlled. Also,
It goes without saying that the invention is not limited to the rotary type Gracilene DC motor, and the movable part of the motor may move in a straight line. In addition, various modifications are possible without changing the gist of the present invention.

Effects of the Invention [0023] The rassless DC motor of the present invention has smooth switching of current paths and significantly reduces motor noise and motor vibration.

Therefore, if a capstan motor or cylinder motor for a video tape recorder is configured based on the present invention, the noise and vibration during play or special playback will be reduced, resulting in a high-performance, high-quality device. what

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a specific configuration example of a current converter, and FIG. 3 is a diagram showing a specific configuration example of a current controller. Figure 4 (a) ~
(f) is a waveform diagram for explaining the operation of the embodiment of the present invention, and FIG. 5 is an electric circuit diagram showing another embodiment of the present invention. Ko...Magnet for field, 0203H...Coil, αυaa 07)...Output transistor, 9th grade...
・Position detection HM, osu... switching signal generator, (4)・
...Command signal outage occurs a8. (2υ...Distributor, (2) Threat...DC power supply, 131)...Speed detector, (31j
・-・Current converter, however υ...Current controller fee g4H person Yoshihiro Morimoto Figure 2 Figure 3 Figure 4 View angle

Claims (1)

[Claims] 1. A motor movable part having a magnetic field magnet, a multiphase coil that intersects with the magnetic flux of the magnet, a plurality of output transistors that supply excitation current to the coil, and a position of the motor movable part. a position detection means for detecting the
activating the switching signal generating means for generating an output signal that changes in response to the output signal of the position detecting means, the command signal generating means, and the output transistor corresponding to the output signal of the switching signal generating means; , a distribution means (1ii+) for supplying an excitation current to the coil in response to the output 1 symbol of the command signal generation means Bi+, and a metal fitting (1ii+), and the distribution means MiJ transmits the output signal of the The differential transistor applied to A brushless DC motor configured to change the excitation current in conjunction with the value of the excitation current.