JPS5925589A - Dc motor - Google Patents

Abstract

PURPOSE:To obtain the commutatorless DC motor generating small base current loss at low current conducting time by a method wherein the base current of a driving switching transistor is increased or decreased corresponding to the detected value of a motor coil supply current. CONSTITUTION:The switching transistor 51 of a voltage converter 12 performs ON, OFF action by the duty corresponded to a speed detecting signal Vd. The common emitter current of a selector 11 is supplied by a base current supplier 10, and the base current supplier 10 detects the coil supply current Ia according to the voltage drop of a current detecting resistor 21. The voltage drop thereof is converted into a current i2 by a transistor 22, the emitter follower transistor 24 of a constant current source 23 and a resistor 25. The current i2 is synthesized with the current I3 of a constant current source 26, inverted and amplified by a current mirror (diodes 28, 29, resistors 27, 30, and transistors 31, 32) to be made as the current i4, and is made as the base current of the driving transistors 7-9 selected by the selector 11.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a DC motor, and in particular to one that efficiently utilizes the power supplied from a power source.

Conventional configuration and its problems Traditionally, for example, when speed control was applied to a DC motor, a transistor or the like was used to reduce and control the voltage from a DC source with a constant output voltage, and the voltage was adjusted to match the speed of the motor. The driving voltage was supplied to the coil.

In such a configuration, the power supplied by the DC power supply is the sum of the effective power consumption in the coil and the collector loss of the transistor.

In a normal DC motor, the ratio (power efficiency) of the effective power consumption in line with the power supplied by the 'flL source is small, 10~
It was about 30%. In particular, DC motors with a wide variable speed range and multi-speed switching, and DC motors for take-up with a wide variable range of driving force, are significantly less efficient when operating at low speeds or with low driving force. .

In order to eliminate such drawbacks, the applicant has filed a patent application filed in 1973.
No. 4-17375 describes a power-efficient DC motor that uses a switching type single redundant pressure ash exchanger that can extract DC voltage from a rotary output, using an electronic commutator type DC motor as an example. It explains. by the way,
In such an electronic commutator type DC motor, current and voltage are passed through the coil and drive transistor. supplying. Each drive transistor turns on and off in response to the position of the motor movable part (rotor). Now, if we consider speed control, at the motor start-up acceleration stage,
The output voltage of the MiJ voltage converter increases, and it is necessary to supply a large current to the coil, and the base current of the drive transistor must be increased. On the other hand, in a state controlled at a predetermined speed (constant speed rotation control state), M
f /EE The output voltage of the father converter is the required value in response to the load torque and back electromotive force (proportional to the motor rotation speed), and the current supplied to the coil of the drive transistor is compared with that during startup and acceleration. Otherwise, the value will be quite small (for example, with two people starting the special vehicle, it will be about 250 mA during constant speed control).

Therefore, the base current required during constant speed control is significantly smaller than the base current of the drive transistor required during large current at startup. As a result, if the base current that enables large current energization at startup (required to increase the starting torque) is constantly supplied to the drive transistor, then when small current is energized during constant speed rotation, This is undesirable as it causes significant power loss.

In the above cited example, the drive transistor is configured by two transistors connected in Darlington, and the base rI
The absolute value of the flow value itself is made small. However, in this configuration, the saturation voltage when on is VCE (sat) (Darlington) = VBE+
VCE (sat) and normal transistor saturation voltage VC
Both E (sa linear 01 to 0.6 V (depending on the current flow) and VBE*0.7 V become large, and the power loss in the Darlington-connected drive transistor becomes large, which is not preferable.

Purpose of the Invention The present invention takes such points into consideration by detecting the current supplied to the coil and increasing or decreasing the base current of the drive transistor in response to the detected value (the drive transistor is turned on or off). (operation), which reduces the pace current loss when water is flowing at low 'f'.

The purpose is to provide a child commutator type DC motor.

Structure of the Invention In order to achieve the above object, the present invention includes a field means having a plurality of magnetic poles, a plurality of coils, and a plurality of field means that operate on and off to switch the current path to the coil. a drive transistor, a position detection means for detecting the entire position of the motor movable part, and a selection means for selecting the drive transistor to be turned on in response to the output of the position detection means;
(2) base current supply means for supplying a base current when the drive transistor is turned on; The configuration is such that the MiJ drive transistor current is reduced in response to the output of the detection means.

Furthermore, the present invention includes a switching type voltage converting means having a switching transistor that obtains a variable output DC voltage from a DC power supply, and the base current supplying means converts the base current when the driving transistor is turned on and the switching transistor of the voltage converting means. The base current supply means is configured with a current detection means for detecting the current supplied to the coil, and supplies the base current of the drive transistor in response to the output of the current detection means. The switching transistor is configured to change the base current of the switching transistor.

DESCRIPTION OF EMBODIMENTS The present invention will be described below based on illustrated embodiments. FIG. 1 is an electrical circuit diagram representing one example of the present invention. In Fig. 1, (1) is a DC power supply, (2) is a field magnet (field means) having a plurality of magnetic poles attached to the motor movable part (loaf), (31 (4) (
5) is a three-phase coil that interlinks with the magnetic flux of magnet (2), (6) is a position extractor that detects the position of the motor moving part,
(7) (8) (9) is the coil (3) (4) (5
), the part OI surrounded by the broken line is the base current supplier that supplies the base current when the drive transistor is on, and σ is the output of the position detector (6). A selector (2) selects a drive transistor that is turned on in response to a DC power supply l and a coil (3
)(4) (This is a switching voltage converter inserted between It is a vessel.

Next, its operation will be explained. Magnet (2) (
The rotational speed of the motor moving part) is detected by the speed detector 0, and the voltage signal Vd corresponding to the detected speed is sent to the voltage converter (b).
The comparator (input to the 4th oscillator 141 of the vehicle pressure detector (6)) generates a sawtooth wave signal of a predetermined frequency (about 50KH2). The voltage signal Vd and the sawtooth wave signal are compared by a comparator (4 units), and the transistor hi is turned on and off at a duty corresponding to the voltage signal Vd, that is, the speed detection signal Vd.

When the transistor 131 is on, the constant current source (bypasses the current 1, transistor t411) +49
1 is turned off, switching transistor (1) Il
Assuming that the base current of is zero, the switching transistor Q
liI) off. When transistor (43 is off), constant current source (4 x 9d current 1 is diode (resistance t47) @0), transistor i4 to 119
) is supplied to a current mirror consisting of a current mirror proportional to 11 (
The current increased by about 40 times) is drawn into the collector side of the transistor +411119). Is this collector N current at a pace that requires a switching transistor? It becomes a U current and turns on the switching transistor (51). That is, the switching transistor Iri is turned on and off at an on-time ratio (duty) corresponding to the speed detection signal Vd.

When the switching transistor Gll is turned on, the voltage Vs (20V) of the DC current s (1) is output and rVikiV
s), inductance element → via capacitor →
and coils (3), (4), and (5). When the switching transistor 卯υ turns off, the flywheel diode tia becomes conductive, supplying the energy stored between the inductance elements to the load side. As a result, the output voltage VM of the dragon pressure summer converter (6) is smoothed by the diode, the inductance element 1531, and the capacitor (incorporated), and the output voltage VM of the dragon pressure summer converter (6) is a value corresponding to the on-time ratio of the switching transistor υ (speed detection signal Vd). corresponding value).

The position detector (6) uses all elements that sense the magnetic flux of the magnet (2) and a circuit that shapes and synthesizes their outputs to generate a +1
A digital voltage signal corresponding to the position of the movable part of the motor is applied to the base terminal of each transistor of the selector aυ.

Selector (b) transistor +31 (34) 43F
The emitters of O transistors are commonly connected, and the transistor with the lowest base potential is active, while the other transistors are inactive. As a result, the input current (common emitter current) of the selector (b) becomes the collector current of the active transistor, and the collector currents of the other transistors become zero. Each collector current of transistor 7 +33) 48 flQ of selector (2) is connected to drive transistor (7) (8
) The base current of (9) and the drive transistor (7
) (8) On/off control of (9).

The common emitter current of the selector Qυ is determined by the bake current supply (l
t3. The base current supply device 00 detects the current Ia supplied to the coil by the voltage drop across a resistor υ (current detection means) inserted in series in the current path. The m pressure drop is the emitter follower of the transistor (2) and the constant current source (2) and the transistor (24).
and resistor (24) is converted into current 12.

The forward voltage (approximately 0.7 V) between the base and emitter of the transistor (22) and the
The voltage drops of It changes in proportion to fI/l (emitter current of the drive transistor).

Here, 几 = 1000 - 几, and 12 is Ia
It becomes 1/1ooo of , which is sufficiently small (normally, 几 and 几 are set to 100 times or more of ■). Also, fLl
The maximum value of the voltage drop in R1 may be about 0.1 V, and the power loss associated with detection is small (as the current decreases, the power loss in R1 becomes significantly smaller).

The current 12 is synthesized with the collector sludge of the transistor (24) (the current amplification of the transistor is large), the current of the constant current source &
f ”, t −)” (2Q f20), resistance FC+27
) Hl) The current is inverted and amplified by the run transistor a◇aa), and the output current i4 becomes the base current of the drive transistor selected by the selector (6). Resistance Q7) and (3
0), respectively, the output current i4 (base current of the drive transistor) becomes (the voltage drop of the diode 08! (29+) and the transistor (3υ
The voltage drop between the base and emitter of □□□ cancels out).

That is, the base current i4 of the drive transistor that is turned on does not become large when the current Ia supplied to the coil is large, and becomes small when the current Ia supplied to the coil is /J·. Here, if R, = 40・melon, i4 is (it
+ I3) (usually R, is 10 times of ■t)
(set to more than double).

In the embodiment of the invention shown in FIG. 1, the base current i4 of the drive transistor is supplied to the coil. Since it is changed according to the current Ia, the pace t in the constant speed control state
〃Flow loss is significantly reduced.

To explain this, in the motor startup/acceleration stage, the output Vd of the speed detector a3 is small, the on-time ratio of the switching transistor becomes large, and the output voltage VM of the voltage converter (6) is fully increased, and the coil (3
) (4) Increase the current supplied to (5). In order to increase the current to the coil, a drive transistor (7
) (s) (9) It is necessary to increase the conduction current Ia when on (9), and therefore, it is necessary to increase the base WW current. Now, assuming that there are two people supplying current Ia to the coil, and assuming that the current amplification degree 11FE when the drive transistor is on is 25, the base current is 2 A/25 = 8.
It is necessary to supply a current of 0 mA or more. Here, the current supplied to the coil in the constant speed control state is 250 mA (
(corresponding to the load torque), only z5omA/2s = 10mA is required as the base current of the drive transistor (7) (81(9)) when it is on.

At this time, the base Yd flow (
80mA or more), 80+n
A -10mA = 70mA loss (70mAX 2
0V=14W).

In this embodiment, the base current supply device 00 changes the base current when the drive transistor is turned on in response to the γα current Ia to the coil, and supplies a sufficiently large base current (80 mA or more) even during start-up acceleration. At the same time, in the constant speed control state, the base? I am trying to minimize the flow. That is, if Ia = 2A, then i, = 2
A/1000 = 2mA, I3 = 0.1m
If A, then i2 + I3 = 2.1mA9, and the base current of the drive transistor (7) (8) (9) is 14 = 40・(i2+I5.l = 84mA) (the drive transistor (4) is fully turned on).

Also, when Ia = 250mA (C constant speed rotation state), 12 = 0.25mA, and i2 + J, = 0
．． Since there are 35m people, i = 14mA (the required base sludge is xomA, so the drive transistor (7)
(8) (9) performs one on/off operation). Therefore,
84mA-14mA: 70mA base current loss (
70mA x 20V = 1.4W) is reduced.

Note that when starting and accelerating the motor when the output voltage VM of the pressure converter OZ is zero (current Ia supplied to the coil is zero), the output Vd of the speed detector Q9 becomes small and p
1 The on-time ratio of a switching transistor/transistor increases, increasing its output voltage. The initial base current of the transistor selected by the selector α is the value (i, =: 40-f) corresponding to the current 3 of the constant current source.
3 = 4 mA), the current flowing through the drive transistor is Ia = IIFE-A4:= 100 mA, and although it is not completely turned on (saturated), the current flowing through the drive transistor Ia increases the current i of the p-pace current supply 0Q. , flows, further increases the current Ia, and operates to completely turn on the drive transistor. That is, transient positive feedback occurs and the drive transistor is turned on.

In order to operate such positive feedback operation stably and to reduce base current loss, it is desirable to set as follows.

■ Even when the current supplied to the coil is zero, a predetermined small base current is supplied to the drive transistor (
drive transistor selected by selector (6)).

■ AI is the conversion gain when the base current of the drive transistor is 14 from the current Ia in the pace 1g current supply device 00.
(In Figure 1, A, = (几1/J(2)・(几, /melon)
), and the current amplification degree of the drive transistor is A,
When (A,: 1 + hIFE), the total product A1
° Bring A2 closer to 1. In reality, since the current amplification degree A2 of the drive transistor tends to fluctuate, o8≦AI'A
It is preferable that 2≦10 (3).

(If A1 and A2 are too small, the drive transistor will not turn on sufficiently during large current operation, resulting in a small maximum value of the coil current. Also, if A1 and A2 are too large, the drive transistor will have excessive In addition, in the embodiment shown in FIG. 1, the drive transistor is turned on (
When the base current i4 is saturated), the increase in the base current i4 directly becomes the increase in the current Ia, and positive feedback occurs due to the base current itself. In order to prevent excessive base current from occurring due to such positive feedback, it is necessary to make the aforementioned AI smaller than 1 (the drive transistor is fully saturated, so the increase in It is preferable to set the current amplification degree to A221), A, ≦0.5 (4).

In addition, in the series circuit of the example, the coil (3) (4) (51 is connected in parallel with the resistor @υsteel (60) (4)
(5) This reduces the spike voltage that occurs in (5).

FIG. 2 shows an electrical circuit diagram representing another embodiment of the invention. In this embodiment, the base current when the switching transistor (51) of the voltage converter (a) in the figure '1fJ1 is turned on is also simplified in response to the current Ia supplied to the coil, thereby reducing the base current loss. ing. Base current supply (]0
) If the value of the resistance υ of transistor H is R, then the tg current is 15 = (11, l/Ra) ・Ia
-=-(5).The current I of the constant current source (73),
This added current (i5+I6) is inverted by the transistor (74) (c), and the voltage converter (6)
current mirror (diode (45) decoy, resistor t47
)H, )syndistor f4Q kg)K, and becomes the base current of the switching transistor H. Letting the values of resistance 0ηl5(2) be R and R, respectively, 17=()chi/R7)・(i,+I.) ・・
...(6). Here, R5=1000・
R4,16 = 0.1 mA, I too.

= 40-1 is also set to 7, and the current amplification degree of the switching transistor circle is set to 25, the base current loss of the switching transistor (51) is reduced (constant speed (rotational collateral condition). j- That is, when Ia =: 2A, i5 = 2mA, and since 9, I, 2 is 0.1mA, A
6 +I622. ], mA, and the base current when the switching transistor υ is on (the required base n1 bit is 2 A-/25 = 80
mA). Marco, Ia = 250mA (at constant speed rotation)
When, i, = 0.25mA, i5+][,
= 0.35mA, so i, = 14mA (Required base mδIL is 250mA/25 = ]
OmA).

'Also, the conversion gain from Ia to i is B, (B1-(
几/R6)・(R,'R,)), and the jd current amplification degree of the switching transistor t51) is 131・B, Ki1......(7
) o8≦B, −E2≦10 (8). Furthermore, even when Ia is 20, it is important to supply a small base current to the switching transistor I0.

Note that since there is no direct transmission from one base current of the switching transistor furnace υ to the current Ta, there is no need to consider the limitations of Bl itself. In addition, drive transistors (7
) (8) The method of reducing pace current loss in (9) is the same as the embodiment shown in the ex diagram, and its explanation will be omitted.

In addition, in the above-mentioned embodiment, an example was shown in which a three-phase coil was used, but the present invention is not limited to such a case, and generally,
A DC motor having multiple coils can be constructed. Further, various known configurations can be adopted for the speed detector, position detector (6), etc. Further, the present invention is not limited to a rotary type DC motor, but can also be configured as a linear type DC motor in which the movable part of the motor moves in a straight line.In addition, various modifications can be made without changing the gist of the present invention.

Effects of the Invention As is clear from the above description, the DC motor of the present invention has a configuration with high force efficiency. Therefore, if the present invention is configured as a DC motor for audio and video equipment using dry batteries as a power source, equipment with low power consumption and long battery life can be realized.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing one embodiment of the present invention, and FIG. 2 is an electric circuit diagram showing another embodiment of the present invention. (1)...DC power supply, (2)...Magnet, (3
) (4) (5)...Coil, (6)...Position detector, (7) (8) (o)...Drive transistor, θQ...Pace current supply device, Oυ... Selector, ■
... Pressure exchanger, 0... Speed detector, υ... Resistor for current detection, (4υ... Oscillation RL (4a... Comparator, (5υ... Switching transistor substitute) People Yoshihiro Morimoto

Claims (1)

[Claims] 1. Field means having a plurality of magnetic poles, a plurality of coils, a plurality of drive transistors that operate on and off to switch the current path to the coils, and a motor movable part position detection means for detecting the position of the drive transistor; selection means for selecting the drive transistor to be turned on in response to the output of the position detection means; and base current supply means for supplying a base current when the drive transistor is turned on. A, the base current supply means includes a current detection means for detecting the current supplied to the coil, and the base current supply means is configured to include a current detection means for detecting the current supplied to the coil, and controls the pace current of the front i8 drive transistor in response to the output of the 'fjt current detection means. A convenient DC motor. 2. Field means having a plurality of magnetic poles, a plurality of coils, a plurality of drive transistors that operate on and off to switch the current path to the coils, and a position for detecting the position of the motor movable part. a detection means, a selection means for selecting the driving transistor that is turned on in response to the output of the position detection means, and a switching type voltage conversion means having a switching transistor that obtains a DC voltage of an adjustable output from a DC power supply; The pace current when the drive transistor is turned on and ? and base current supply means for supplying a pace warm current when the switching transistor is turned on, the base current supply means comprising current detection means for detecting the current supplied to the coil, A DC motor in which the base current of the drive transistor and the base current of the switching transistor are adjusted in response to the output of the current detection means.