JPS5925588A - Dc motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

Conventional configuration and its problems Traditionally, for example, when speed control is applied to a DC motor, a transistor or the like is used to reduce and control the voltage from a DC power supply with a constant output voltage, and the drive voltage is adjusted to match the motor speed. Even if I supplied it to the coil.

In such a configuration, the power supplied by the one-page 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 of effective power consumption to power supply (power efficiency) is small, 10 to 80
It was about %. In particular, DC motors with a wide variable speed range and multi-stage speed switching, and DC motors for winding with a wide variable range of driving force have been particularly bad.

In order to eliminate such drawbacks, the applicant has filed a patent application filed in 1973.
In No. 7-84564, a variable output DC converter, a power efficient '[P commutator type (brushless type)] using a switching type voltage converter that can output voltage.
1 uses a flow motor. In a DC motor having such a configuration, current is supplied to the coil through the switching transistor of the voltage converter.

Now, if we consider the case of speed control, during the startup and acceleration stages of the motor, it is necessary to supply a large current to the coil with a large output voltage of the voltage converter, and the switching transistor of the voltage converter also needs to be large. In order to supply current, the base current during on-state must be increased. Ten thousand,
State controlled at a predetermined speed (constant speed rotation control state)
In this case, the output voltage of the voltage converter is a predetermined value that responds to the load torque and back electromotive force (proportional to the motor rotation speed), and the current supplied to the coil is a very small value compared to that during startup and acceleration. (-For example, when the starting special condition is 2A, the output is about 250mA during constant speed control). Therefore, the base current (when on) required during constant speed control is significantly smaller than the base current (when on) of the switching transistor that is required at the time of large current at startup. As a result, if a base current is given to the switching transistor that enables large current conduction (required to increase the starting torque) at startup, when a small m current is conducted during constant speed rotation, This is not desirable as it causes a large amount of power loss.

Purpose of the Invention The present invention takes such points into consideration and increases or decreases the base current when the switching transistor of the voltage converter is turned on in response to the current supplied to the coil (the switching transistor operates on and off). It is an object of the present invention to provide a commutator type DC motor that reduces base current loss in a steady state (such as when rotating at a constant speed).

Structure of the Invention In order to achieve the above object, the present invention provides a position detecting means for detecting the position of a movable part of a motor, a field means having a plurality of magnetic poles, a plurality of coils, and a current to the coil. a group of drive transistors for switching paths, a selection means for selecting the drive transistor to be activated in response to the output of the position detection means, a current detection means for detecting the current supplied to the coil, and a command signal generation means. , current control means for controlling the energizing current of the drive transistor according to the output of the current detection means and the output of the command signal generation means, and a variable output from the DC source inserted between the DC power supply and the coil. a switching type voltage conversion means for obtaining a DC voltage of , and an operation detection control for detecting the operating voltage of the drive transistor when it is energized and changing the on-time ratio of the switching transistor of the voltage conversion means in accordance with the detection signal. and base current modifying means for changing the base current when the switching transistor of the voltage converting means is turned on in accordance with the output of the current detecting means.

DESCRIPTION OF EMBODIMENTS The present invention will be described below based on illustrated embodiments. FIG. 1 is an electrical circuit representing one embodiment of the present invention. In Figure 1, (1) is a DC power supply, (2) is a field magnet (field means) having multiple magnetic poles, (3H
4H5) is an 8-phase coil that interlinks with the magnetic flux of magnet (2), (6) (7) (8) is coil (3) (4)
(5) a drive transistor that switches the current path to (9);
01) is a position detector that detects the position of the motor movable part; 00 is a selector that selects drive transistors (6), (7), and (8) to be activated in response to the output of the position detector (9);
is a current detector that detects the supply current a to the coils (3) (4) (5), and 02 is the command signal ■1 and current detector 0
A current controller that compares the output v2 of 1) and outputs a current according to the difference, a switching type voltage converter that obtains a variable output DC voltage VM from a DC power supply (1),
4) Operation detection that detects the operating voltage of the driving transistors (6), (7), and (8) when they are energized, and changes the on-time ratio of the switching transistor 0) of the voltage converter α east according to the detection signal. Controller, 09 is current detector 01
) according to the output ■2 of the switching transistor (→
OQ is a speed detector (command signal generation means) that obtains a command signal v1 corresponding to the rotational speed of the magnet (2).

First, the normal rotational drive operation will be explained.

In response to the rotational speed of the magnet (2), the speed detector CI
(The output of 'N changes, and - is applied as a command signal ■1 to the normal rotation input terminal of the current control device O2. The output voltage v2 of the current detector 0υ is applied to the inversion input terminal of the current controller 0Q. A current corresponding to the difference between ■1 and ■2 is output from the current controller α, and is supplied as a common emitter current of the selector αQ consisting of the differential transistor QH.Current controller (2) is composed of, for example, a differential voltage amplifier and a voltage/current converter.The transistor 0I of the selector uO
Each base terminal has a Hall element (2) of the position detector (9).
The output voltages of (and) are applied respectively. Hall element (c) 1:3110 senses the magnetic flux of magnet (2) and generates an analog voltage signal according to its rotational position. The transistors θ11, Q42, and GI31 distribute a common emitter current to each collector stream according to the difference in their base voltages, and the collector current of the transistor with the lowest base voltage is the steepest, and the collector currents of the other transistors are zero. . Transistor G41) G13 C4
Each collector current of 3 is a drive transistor (6) (7)
Each base (8), current, and current are amplified and supplied to coils (3), (4), and (5). Coil (3)
(4) The supply current Ia to (5) is detected as a voltage drop v2 (at the resistance of the current detector αυ), and the current controller 0
Color is entered.

As a result, the current controller (1z1 selector 011j, F,
! The first feedback loop is configured by the g-dynamic transistors (6) (7) (8) and the current detector αυ, and the current supplied to the coils (3) (4) (5) reliably corresponds to the command signal vl. It is regarded as a first class value. As a result, the influence of hFE variations in transistors (6), (7), and (8) is significantly reduced. Sweet, magnet (2)
The output voltage of the Hall element (G) changes with the rotation of the drive transistor (6), (7), and (8) so that current is supplied to the corresponding coil. To go.

Note that the capacitor is attached to compensate for the phase of the feedback loop mentioned above (to prevent oscillation). Also, coil (3)
(4) Resistor (c) connected in parallel with (5) (
/471θ@ and the capacitor) The four wheels reduce the spike voltage caused by switching the current path.

Next, the operations of the voltage converter a3 and the operation detection controller α will be explained. Voltage converter (13 is DC W'IP
From the positive terminal (Ve=20V) of (1) to the coil (3)
(4) A switching transistor 6→ is inserted in the power supply circuit leading to the common connection terminal in (5) with its emitter-collector path connected in series. The output voltage VM changes in relation to the on-time ratio (the ratio of the on-time to one cycle of on-off) of the switching transistor 02. When this switching transistor (to) is on, Vi'': Vs, and the DC source (1) supplies current to the load side through the inductance element (b).When the switching transistor (0 seconds) is off,
When the flywheel diode is turned on, the energy stored in the inductance element (b) is supplied to the load side. As a result, the output voltage VM of the voltage converter QJ has a value corresponding to the duty of the on time of the switching transistor C, 32. The output m pressure VM on the voltage converter side is 8
phase coils (3) (4) (5) and drive transistors (6) (7) (8).
2) The drive transistors that become active are sequentially switched as the motor rotates.

The operation detection controller 0 detects the operating voltage (collector-emitter voltage in this case) of the drive transistor in the energized state, and this will be further explained. The current 1 of the constant current source is supplied to the resistance ring and the diode junction, and a reference voltage signal of a predetermined voltage value is supplied from the common connection terminal (emitter terminal in this example) of the drive transistors (6) (7) (8). v3r = 1.4 + R65·11- (1) is generated. Here, 1.4V is the voltage drop across the diode ring, and R65 is the value of the resistance. Detection transistor (61) (Each emitter side of a2H is DC connected to the reference potential point (signal ■3 point) as a reference terminal, and each base terminal is connected to the drive transistor (61) as a detection terminal.
6) It is connected to each output terminal (collector terminal) of (7) and (8) in a DC manner. As a result, the operating voltage of the drive transistors (6), (7), and (8) is set to the above-mentioned reference voltage V3.
r, ]: Rimo emitter-base forward voltage "D" 0.
When the voltage becomes smaller than 7V, the corresponding detection transistor becomes conductive and part of the current 1 is shunted to the collector side.

Since the operating voltage of the activated drive transistor is lower than the operating voltage of other drive transistors, the detection transistor (f'il) ta tJ is used to adjust the operating voltage of the drive transistor when energized to the reference voltage V3r mentioned above. are compared, and a collector current corresponding to the difference is output. Each detection transistor (61) l>51'x'?
The output current is inverted and amplified by a current mirror of a synthesizer (collector sides are commonly connected), a diode, and a transistor (70, resistor 11 (7)), and a current 13 is output.

The output current 13 of the motion detection controller αa is converted into a voltage by the resistor ■ of the voltage converter θ→, and the predetermined frequency (
It is compared with a triangular wave signal of about 50 KHz) by a comparator so as to turn the transistor (c) on and off.

When the transistor (c) is on, the transistor (to) is off, and the base current IB of the switching transistor (a) is zero, υ, and the switching transistor (
2) is turned off. When the transistor (C) is off, the current of the constant current source @, the current F and the base current corrector (Iυ output 16 consists of the diode @ (A), the resistor (C) 6υ, and the transistor (4) (to) A current proportional to (16+I7) (approximately 40 times) is supplied to the current mirror and is sucked from the collector side of transistor (A) (to), and the base current IB of transistor (A) is supplied to the switching transistor. 62 is turned on. That is, the on-time ratio of the switching transistor 04 is determined by the output current 13 of the operation detection controller 04),
The output −1 voltage VM of the voltage converter 04 changes accordingly.

Accordingly, a second feedback loop is formed by the operation detection controller QC controller, the pressure transducer 0, and the coils (3), (4), and (5), and the operating voltage of the aforementioned drive transistor (when energized) is detected, and its operating voltage is set to a predetermined value within the active region (a value corresponding to the reference voltage v3r).

This will be further explained. Now, if we consider the case where the output V of the speed detector θQ increases a little in a stepwise manner, the current Ia supplied to the coil increases in response due to the operation of the first feedback loop (as the output V of the m current detector θυ increases). Output v2
increase the current factor a so that it becomes equal to the command voltage v1). An increase in current Ia increases the voltage drop across the coil, causing the transiently energized drive transistor (6) (7)
(8) The operating voltage becomes smaller. The reduction in operating voltage is due to the output current 12 of the detection transistor (6) 1t i8 kl
is increased, and the output current 13 of the motion detection controller 04) is increased. Due to the increase in i3, the resistance of Hayabusa and pressure transducer OQ (
When the voltage drop of the transistor (c) is large, the on-time ratio of the transistor (c) becomes small. Therefore, the on-time ratio of the switching transistor 04 increases, and the output voltage VM of the voltage converter 04 also increases. Therefore, the operating voltage of the drive transistors (6), (7), and (8) when energized also increases, and its value is suppressed to a relatively small predetermined value within the active region or its vicinity.

Next, the operation of the base current corrector OQ will be explained. The voltage drop V2=RbiIa of the current detector 0υ, (where R is the value of the resistor) is the constant current, the emitter follower of the current source 2, and the transistor (
) and is converted into a current 16 by the resistance diagram. In other words, between the base and emitter of transistor 6υ and 111Q
The directional voltage (approximately 0.7 V) cancels out, and the voltage drop across the resistor becomes equal to the voltage drop across the resistor. If the value of resistance (to) is R2, R2□ i5'= R4・Ia
”・(2)R.

1s-().Ia Mountain (3) 2 The emitter 3 current 15 of the transistor (A) changes in response to the current Ia supplied to the coil. The current i5 is the collector current of the transistor C, and is inverted by the current mirror of the transistor C, and is converted to the voltage converter 0.
Outputs current 16 (-15) to
Assuming that FE is sufficiently large, the reduction in transfer gain due to base current is ignored). Here, R2-1000-R+ is 1/01000 of is fly a, which is sufficiently small (usually, R2 is set to 100 times or more of R1).

The current 16 is combined with the current T7 of the constant current source
).

It is inverted and amplified by the resistor (C) Oυ) and becomes the base current IB of the switching transistor (when the transistor (C) is off). If the resistance (5) and Oυ are respectively set as otlR3+R4, then the base current of switching transistor 0 is IB l 1°... (4) I
B=()・(i6+F) 4 (The voltage drop of the diode @(A) and the voltage drop between the base, emitter, and lid of the transistor (■) cancel each other out by 1).

In other words, the base current of the switching transistor 0→ changes in response to the output V2 of the current detector 01), and the current Ia supplied to the coil becomes larger at times. Supply current Ia force to the coil X7
It becomes smaller when it is Js. Here, R3=40・R
If it is 4, 1B is 40 times (16+F) (usually set to 10 times or more of R31 and R4).

In the embodiment of the present invention shown in FIG. Base current loss in the speed control state is small. This will be further explained. During the motor startup/acceleration stage, when the output V of the speed detector θQ is large, the first feedback loop operates to increase the current a supplied to the coil, and the second feedback loop operates to increase the current when energized. The output voltage vM of the voltage saturation circuit is increased so that the iQ+operation tl pressure of the drive transistor becomes a predetermined value (the first and second feedback loops operate simultaneously, and vM
, engineering a increases to its maximum value). In order to increase the small current to the coil, it is necessary to increase the conduction current (collector current) when the switching transistor C3 is turned on, and therefore, it is necessary to increase its base current.

Now, if the current supplied to the coil is 1a = 2A, and the current amplification degree hFF when the switching transistor 0 is on is 25, then its base current is 2A//'25=
It is necessary to supply a current of 80 mA or more.

Here, the current supplied to the coil in the constant speed control state is 2
Assuming that it is 50mA (corresponding to the load torque),
Only 250/25=10 mA is required as the base current when the six switching transistors are turned on. At this time, if it is assumed that the current (80 mA or more) required at the time of startup and acceleration is flowed at that time, 8
0mA -10mA = 70mA loss (70rr+
AX 20'V = equivalent to 1.4W).

In this embodiment, the output V2 of the current detector 01) is R, ・
The output 16 of the base current corrector aO changes in response to the voltage change a, and the switching transistor 6a of the pressure converter αQ changes.
By changing the base current IB of
In the constant speed control state, the base violet 1 flow is made small. In other words, at the start-up/acceleration stage, engineering a =
If it is 2A, then i6 = LB = 2A/1000 = 2mA,
If l7 = 0.1 mA, -: b + I7 = 2.1 mA 4-, and the base current of the six switching transistors is JB =: 40 ・(i6 + engineering y) = s4 mA (switching transistor cp is sufficiently (turns on)
. i, when a = 250mA (constant speed rotation state), it is 16-0.25mA, i6 + l7 = 0.8
Since it is 5 mA, it becomes:=14 mA (since the required base current is 10 mA, the switching transistor (a) operates on and off).

Therefore, the base current loss of 84 mA - 14 mA = 70 mA (equivalent to 70 mA x 20 V = 1.4 V/) is reduced.

In addition, when starting and accelerating the motor from a state where the output voltage VM of the voltage converter θ→ is zero and the supply voltage to the coil; When it becomes larger than the initial base current of the switching transistor G2, the value corresponding to the current ■7 of the constant current source (c) (IB=4047 = 4 mA), the switching transistor (a) becomes completely on. However, the output voltage VM of the voltage converter θ4 becomes slightly larger. V
As M increases, the flow Ia supplied to the coil increases. (Operation of the first feedback loop) Since the operating voltage of the drive transistor is small, the output current i3 of the operation detection controller θ is large, and the m1 ratio when the switching transistor ζ3 is turned on is small. . As the supply current a to the coil increases, the base current corrector αe
The switching transistor C has a large output 16.
When the base m flow of +→ becomes weaker, the switch leg transistor 0→ performs a complete on/off operation. As a result, the command signal V! The on-time ratio of the switching transistor 6'4 of the voltage converter α□□□ is controlled so that the current ■8 corresponding to the current ■8 is supplied to the coil, and the operating voltage of the drive transistor when energized is set to a predetermined value.
In fact, the current value is slightly larger than the base current of the six switching transistors, which is the necessary value to guarantee on/off operation. In other words, transient positive feedback occurs and (VM, engineering a -) i6' IB → VM,
Ia) The output voltage VM of the voltage converter θ and the current supplied to the coil a become larger.

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

(2) A predetermined small base current is supplied to the switching transistor (a) even when the current supplied to the coil 8 is zero (base current when on).

■ The conversion gain at the coil current a at the current detector 0υ to the output 16f of the base current corrector Q0 is set to Al (Al-R1/R2 in Figure 1), and from 16 at the voltage converter 03 to the switching transistor 0. The transfer gain from the base uffi to the switching transistor is A2 (A2= R3/R4), and the current amplification degree from the switching transistor is A3 (A3=
hFE), the total product AI-12·A3 approaches 1.

In reality, since the current amplification degree A3 of the switching transistor 0 is likely to fluctuate, 0.8≦A1・A2・A3≦10
...(5), It is preferable that (A1・A2
- If A3 is too small, the maximum value of the output voltage VM of the voltage converter αQ becomes small because zero switching transistors are not turned on sufficiently during large current operation. Also, A
If 1, A2, and A3 are too large, excessive base current will be supplied to the switching transistor (a), reducing the effect of reducing base current loss).

In addition, in the above-mentioned embodiment, an example was shown in which an 8-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. -!
In addition, various known configurations can be adopted for the speed detector Qllj, the position 1u detector (9) 9 selector θQ, the current controller 09, etc. Furthermore, not only a rotary type DC motor but also a linear type DC motor in which the motor movable part moves in a straight line can be configured. In addition, various modifications are possible 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 highly efficient configuration. Therefore, if a DC motor for audio and video equipment using a dry battery as a 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 representing an embodiment of the present invention. (1)...DC m source, (2)...Magnet, (3
)(4) (5)...Coil, (6) (7) (8
)...Drive transistor, (9)...Position detector,
01...Selector, 01)...Current detector, @...
Current controller, 03... Voltage converter, Q4)... Operation detection controller, OQ... Base current modifier, OQ...
Speed detector, (21)...Oscillator, @...Comparator, 0...Switching transistor. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. Position detection means for detecting the position of the motor movable part;
a field means having a plurality of magnetic poles; a plurality of coils;
a drive resistor group for switching a current path to the coil; a selection means for selecting the drive transistor to be activated in response to the output of the position detection means; and a current detection means for detecting the current supplied to the coil. , a command signal generation means, a current control means for controlling the current flowing through the drive transistor according to the output of the current detection means and the output of the command signal generation means, and the A switching type voltage conversion means that obtains a variable output DC voltage from a DC power supply, and an operating cylinder when the drive transistor is energized: detects the pressure, and adjusts the on-time of the switching transistor of the voltage conversion means according to the detection signal. operation detection control means for changing the ratio; and a base t! for changing the base current when the switching transistor of the voltage conversion means is turned on in accordance with the output of the current detection means. A DC motor equipped with a current correction means.