JPS58186388A - Dc motor - Google Patents

Abstract

PURPOSE:To improve the efficiency of a DC motor by varying the output current of current supplying means in response to the output of speed detecting means, and increasing or decreasing the base current of a drive transistor, thereby reducing the base loss at the small current flowing time. CONSTITUTION:The rotating speed of a rotor 2 is detected by a detector 13, to control ON or OFF of a transistor 22 of a voltage converter 10, thereby exciting drive coils 3-5 connected in series with drive transistors 7-9. The signal of a position detector 6 for the rotor 2 is applied to the base of transistors 34-36 of a distributor 11, the common emitter is connected to a current supply unit which varies the output current by the signal of the detector 13, and the drive transistors 7-9 are controlled by the distributor 11. Accordingly, the base currents of the transistors 7-9 can be varied in response to the output of the detector 13, and the base current loss at the constantly rotating time can be largely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor, and more particularly to an electronic commutator type (brushless type) DC motor that efficiently utilizes electric power supplied from a power source.

Conventionally, when controlling the speed of a DC motor, for example, a transistor or other device was used to reduce and control the voltage from a DC power supply with a constant output voltage, and supply a drive voltage corresponding to the speed of the motor to the drive windings. .

In such a configuration, the power supplied by the DC power supply is the sum of the effective power consumption in the drive winding and the collector loss of the transistor. In a normal DC motor, the collector loss of the transistor is quite large, and the ratio of the effective power consumption to the power supplied by the power supply (power efficiency) is about 10X to 30%. In particular, DC motors with a wide variable speed range that can be switched in multiple stages, and DC motors for winding with a wide variable range of driving force, have significantly poor efficiency during low speed and low driving force operations.

In order to eliminate such drawbacks, the applicant has filed a patent application filed in 1973.
No. 4-17375 describes a DC motor with high power efficiency using a switching type voltage converter capable of extracting a variable output DC voltage, taking an electronic commutator type DC motor as an example. Incidentally, in such an electronic commutator type DC motor, current and voltage are supplied to the drive winding via a drive transistor.

Each drive transistor is turned off in response to the position of the motor rotor. Now, considering the case where speed control is performed, the output voltage of the voltage converter increases during the startup and acceleration stages of the motor, and it is necessary to supply a large current to the drive winding.

The base current of the drive transistor must be increased. On the other hand, in a state where the speed is controlled at a predetermined speed (constant speed rotation control state), the output voltage of the voltage converter becomes the required value in response to the load torque and the back electromotive force (proportional to the motor rotation speed). The current supplied to the drive winding of the drive transistor is a fairly small value compared to that during startup and acceleration (for example, when the starting special is 2A and constant speed control is 250
(about mA). Therefore, compared to the base current of the drive transistor that is required at the high current during start-up.

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

In the above-mentioned example, the driving transistor is constituted by two transistors connected in a Darlington connection, and the absolute value of the pace current value itself is made small. However, in such a configuration, the saturation voltage when on is VCE (sat) (darlint y) = Vnx + Vcz (
sat) and the normal transistor saturation voltage vcg(sat
, ) ”O-1 to 0-6V (conduct current!) 4Viv *o, yv also become large, and the power loss in the Darlington-connected drive transistor becomes large, which is not preferable.

In consideration of such points, the present invention increases or decreases the base current of the drive transistor according to the direction of the command means (for example, speed detection means) (the drive transistor operates on and off) & small current conduction operation. The present invention provides an electronic commutator type DC motor with reduced base current loss during operation. below.

The present invention will be explained based on illustrated embodiments.

FIG. 1 shows an electric circuit representing one embodiment of the present invention.

In the figure, lr/i DC power supply, 2 is motor movement part (
Magnet for the field attached to the rotor)% 3,
4.5 is a three-phase drive winding that interlinks with the magnetic flux of magnet 2; 6 is a position detector s7 that detects the position of the motor moving part;
．． a, 9 is a group of drive transistors that switch the current path to the windings 3, 4゜6;
tri DC power supply 1 and drive winding May 4. A switching voltage converter is inserted between tsO, 11 is a distributor that controls the energization of the drive transistors 7, 8, 9 in response to the output of the position detector 6, and 12 is a distributor that supplies current to the distributor 11. It is a current supply device.

b13Fi also detects the rotation speed of magnet 2.

It is a speed detector that obtains a voltage signal corresponding to the speed.
The output voltage Vd commands the output voltage Vc of the voltage converter 1°. That is, in this embodiment, the rotation detector 13 constitutes a command means.

Next, its operation will be explained. The rotational speed of the magnet 2 (motor moving part) is detected by the speed detector 13, and a command voltage signal Vd corresponding to the detected speed is input to the switching controller 21 of the voltage converter 1o. The switching controller 21 is composed of, for example, a sawtooth wave oscillator and a comparator (a variety of known configurations can be used), and generates a pulse signal with a duty ratio corresponding to the input voltage to turn on and off the switching transistor 22. Control. Inductor element 24. Smoothed by a capacitor 26 and a flywheel diode 23, the output voltage Vc of the voltage converter 1o is connected to the switching transistor 2.
The value corresponds to the on-time ratio of 2, that is, the value corresponds to the output voltage Vd of the speed detector 13.

The position detector 6 is composed of a Hall element that senses the magnetic flux of the magnet 2 and a circuit that shapes and synthesizes its output, and sends a digital voltage signal according to the position of the motor movement section to each transistor of the distributor 11. 34, 35, and 36 base terminals.

The emitters of the transistors 34, 35, and 36 of the distributor 11 are commonly connected, and the transistor with the lowest base potential is activated, and the other transistors are inactive. As a result, the divider 110 input current (common emitter current) becomes the collector current of the active transistor, and the collector current of the other transistors becomes zero. The collector currents of the transistors 34, 35, and 36 of the distributor 11 are connected to the base currents of the drive transistors 7.8 and 9, respectively, and control the on/off of the drive transistors 7.8.9'i.

The common emitter current of divider 11 is supplied by current supply 12 . The current supply device 12 detects the output voltage Vd of the speed detector 13 using a resistor 27, and when the voltage value Vd increases, the current supplied to the distributor 11 increases (therefore, the base current of the drive transistor increases).
, when the voltage value Vd becomes smaller, the current supplied to the distributor 11 is reduced (therefore, the base current of the drive transistor becomes smaller). In other words, as ■d increases, the resistance 2
The voltage across transistor 28 and resistor 2 increases.
9 current increases. Transistor 2B, 30. Resistors 29 and 31 form a current mirror circuit, increasing the collector current of transistor 30, which is reversed by transistors 32 and 33 and becomes the supply current to divider 11. When the output voltage Vd of the speed detector 13 is small, the current from the current source 26 is mainly supplied to the distributor 11.

In this way, if the output voltage vd of the speed detector 13 is detected and the base current of the drive transistor is changed according to the detected value, sufficient base current will be provided to the drive transistor even during large current operation during startup e acceleration. In addition to being able to supply
The base current during small current operation in the constant speed rotation control state can also be reduced, and the base current loss during constant speed rotation is significantly reduced.

The reason for this is that when the rotation speed of the magnet 2 is slow in the startup/acceleration stage, the output voltage vd of the speed detector 13 is large, and the switching controller 21 increases the on-time ratio of the switching transistor 22. , the output voltage Vc of the voltage converter 10 is increased, a large current is supplied to the drive winding, and a large acceleration torque is obtained. Now, assuming that the winding resistance is r = 100b and the maximum value of vc is 19V, the drive transistor 7.8.9 will have a voltage of 18V at startup.
/10n: 1.8A current (saturation voltage is 1■)
. At this time, the DC amplification factor of the drive transistor, Σ, is 4
0, the base current required at startup is 1.9A/4
0=45mA. Output voltage Vd of speed detector 13
If it is thick, the current of the resistor 27 becomes large, and the current supply device 1
2 to supply a large base current (50 mA degree) to the drive transistor selected by the position detector 6 and the distributor 11.

As a result, a large current is applied to the drive transistor to turn it on (saturated operation), and the current is supplied to the corresponding drive winding, thereby generating a large cutting edge speed torque through interaction with the magnet 2.

When the blade speed n of the magnet 2 reaches a predetermined rotational speed, the output voltage Vd of the speed detector 13 becomes small.

The switching controller 21 reduces the on-time ratio of the switching transistor 220, reduces the output voltage Vce of the voltage converter 1o, and reaches a constant speed rotation control state.

I1. Ignoring the back electromotive force as small, VC=3V
Then, the current flowing through the drive transistor is 2.5V/1
0Ω: 250mA (saturation voltage is 0.6v)
. Therefore, the base current required to turn on the drive transistor is 250 / 40: 6.25 mA, and if a base current of about 8 mA is supplied with a small margin of L(7), the drive transistor will surely turn on (saturated operation). ). In other words, the base current of the drive transistor is 45 mA required at startup, but only 8.25 mA is required when constant speed rotation is controlled with light load torque, a difference of 3.
It may be reduced by 8.75 mA. Speed detector 13
When the output voltage Vd of becomes smaller, the current R flowing through the resistor 27,
When the current supply voltage is small, the output current of the current supply device 12, that is, the pace current of the driving transistor becomes small. I1. Base current at startup: 22.5 mA, half of 45 mA
If i becomes smaller, tl- then 22.5mAX2
Loss of 0V==0.45W is reduced.

'! Assuming that the current is reduced to 11.25 mA, which is a quarter of 45 mA, then 33.75 mA x 2
0 V: Loss of 0.675 W is reduced. As a result, the drive transistor can be turned on and off reliably.

The pace current loss is significantly reduced.

FIG. 2 shows an electrical circuit diagram representing another embodiment of the invention. In this embodiment, one end (
Collector terminal) is connected in common.

a first drive transistor 14°15.16 whose respective output terminal (emitter terminal) is connected to a drive winding 3,4°5;
A second drive transistor whose one end (emitter terminal) is commonly connected to the negative terminal of the voltage converter 10, and whose output terminal (collector terminal) is connected to each output terminal of the first drive transistor 14° 15.16. 7, 8. 9'i is provided, the current path of the drive winding M3゜4.6 is switched on both the positive and negative sides, and current is constantly supplied to the two drive windings, thereby improving the utilization efficiency of the winding. It comes out.

Next, its operation will be explained. The rotational speed of the magnet 2 is detected by a speed detector 13, and a voltage signal Vd corresponding to the rotational speed is output. Depending on the output voltage Vd of the speed detector 13, the switching controller 2 of the voltage converter 1o
1 fully controls the on-time ratio of the switching transistor 22, and the diode 23 . Inductor element 24. The output voltage Vc is controlled by smoothing with a capacitor 26.

The output voltage ■c of the voltage converter 1o is the first drive transistor 14, 15, 16 and the second drive transistor 7.
．． 8.9 and the drive winding N$3.4°6 is stamped.

The rotational position of the magnet 2 is detected by a position detector e, and digital voltage signals (six signals) corresponding to the detected position are input to the distributor 11. The distributor 11 includes a first differential circuit 61, a second differential circuit 62, and current mirror circuits 63, 64,
66, the transistors 41, 42, 43, 34, of the first and second differential circuits 61, 62;
The output voltage of the position detector 6 is applied to each of the pace terminals 36 and 36, respectively.

First differential circuit 61//i transistor 41, 42°4
1 depending on the pace voltage of 3 (output voltage of position detector 6)
The transistors become active and distribute the common emitter current (output current of the current supply device 12) to the collector side. The collector current is current mirror circuit 63, 64, 65
The current becomes the base current of the first drive transistors 14, 15, and 16 through the base current, and one first drive transistor corresponding to the output of the 1-position detector 6 is always turned on.

Further, the second differential circuit 62 includes transistors 34, 35, .
One transistor becomes active in response to the pace voltage of 36 (output type of position detector 6), and the common emitter current (
The output current of the current supply device 12) is distributed to the collector side.

Its collector current is the second drive transistor 7.8.9
, and the second base current according to the output of the position detector 6.
One drive transistor is always on.

The common emitter current of the first and second differential circuits 61 , 62 of the distributor 11 is supplied by a current supplier 12 .

The current detector 12 detects the output voltage vd of the speed detector 13 using a resistor 27, and when the voltage value vd becomes large, it increases the current supplied to the distributor 11 and increases the current supplied to the first and second drive transistors. Increase the current and increase the voltage value v
As d becomes smaller, the current supplied to the divider 11 is reduced to reduce the base currents to the first and second drive transistors.

As a result, sufficient base current is supplied to the first and second drive transistors VC even during high current operation during startup and 7717 speed, and the base current is lower than the minimum required during low current operation during constant speed rotation control. The current loss is reduced to a slightly higher level, significantly reducing pace current loss.

In the above-mentioned embodiment, an example was shown in which a three-phase drive winding M was used, but the present invention is not limited to such a case, and can generally constitute a DC motor having a plurality of phase drive windings a.

Further, the connection is not limited to a star-shaped connection, but may be a ring-shaped connection. Furthermore, 1 position detector6. The speed detector 13 and the switching controller 21 can adopt various known configurations.

Also, 5 distributors 11. Current supply device 12. It is also possible to implement an integrated circuit (IC) on a silicon chip, including the drive transistors 7* st s (and 14, 15, 16).

Further, the command means for commanding the output voltage Vc of the voltage converter 1o and the output current of the current supply device 12 is not limited to the speed detector as in the above-mentioned embodiment, but may be other than the speed detector according to the membership fee. Method (Tarie is a tape tension detector)
Needless to say, it is possible to employ

As is clear from the above description, the DC water pump of the present invention is an electronic commutator type DC motor with good power efficiency. Therefore, if a DC motor for audio/visual equipment using dry batteries as a power source is constructed based on the present invention, equipment with low power consumption and long battery life can be realized.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing one embodiment of the invention, and FIG. 2 is an electrical circuit diagram showing another embodiment of the invention. 1...DC power supply, 2...Magnet*
``t'e6... Drive winding, 6...
Position detector %7.8.9... Drive transistor (or second drive transistor), 10...
Voltage converter, 11...Distributor. 12... Current supply device, 13... Speed detector, 14°15.16... First drive transistor, 21... Switching controller.

Claims (1)

[Claims for Claims] DC motor (1) Field means includes a plurality of phase drive winding shafts, a position detection means for detecting the position of one motor moving part, and a drive transistor for switching the current path to the drive windings. a distributing means for controlling on/off energization of the front η pin drive transistor group in response to the output of the position detecting means, and a switching type voltage converting means for obtaining a variable output DC voltage from the DC power supply. comprising current supply means for supplying current to the distribution means, and command means for commanding the output voltage of the voltage converter means,
A direct current motor characterized in that the output current of the current supply means is changed in accordance with the output of the command means, and the base current of the drive transistor is changed by valving the distribution means. (2) The direct current motor according to claim 1, wherein the command means is constituted by speed detection means for detecting the rotational speed of the motor driver.