JPS59139886A - Brushless motor - Google Patents

Abstract

PURPOSE:To eliminate the unnecessary torque loss and abnormal vibration of a brushless motor by controlling via a switching mode power source the collector vs. emitter voltage of an output transistor to become the prescribed current amplification factor capable of being predetermined by a resistor. CONSTITUTION:Assume that the only transistors Q3, Q4 of output transistors Q1-Q3 are conducted by the positional relation between a rotor 1 and an armature winding 3. Since the hFE of the Q4 varies in response to the collector vs. emitter voltage, the collector vs. emitter operation voltage of the Q4 when the loop gain of a negative feedback loop via a differential amplifier 20, a low pass filter 21, a position signal converter 5, Q3, windings L1, L3, Q4, and resistor 13 are sufficiently high are automatically determined, the hFE becomes constant, and the current amplification factor is maintained constantly. On the other hand, the Q3 is similarly operated to automatically determine the collector vs. emitter operation voltage of the Q3 when the loop gain of the negative feedback loop via a differential amplifier 24, a low pass filter 25, a switching mode power source 26, Q3, windings L1, L3, Q4, and resistor 13 is sufficiently high, and the hFE of the Q3 and the current amplification factor become constant.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a tape recorder and a record player.

This invention relates to a brushless motor that can be used in video tape recorders and the like.

Conventional Structure and Problems Brushless motors, in which armature current is switched by transistors and generated torque is controlled by command input, are widely used in the above-mentioned industrial fields. A conventional example of a typical configuration using an 8-phase Wa child winding is shown in FIG.

In FIG. 1, the rotational positions of the multi-pole magnetized permanent magnet rotor (1) and the respective windings L1 to L8 of the armature winding (3) are detected by a position detector (2), and a position signal is detected. The signal is transmitted to the switching circuits (5) and (7). Position signal switching circuit (5)
(7) each has an 8-differential configuration, and each collector is connected to the base of each transistor Q1 to QB*Q4 to Q6 of the corresponding output transistor * (tl) (8). Output transistor B ¥ (6) (8
), their emitters are connected in common, their collectors are connected to their corresponding phases in a push-pull configuration, and one end of the corresponding phase of the armature winding (3) is connected to each other. What is the common emitter of output transistor Sen (6)? # (connected to 10, output transistor group (8
) are grounded through a resistor (to). The voltage at the ungrounded terminal θ→ of the resistor (to) is applied to the inverting input (-) of the current output type differential amplifier (4),
Torque command voltage (A) is applied to the non-inverting input (+) of the differential amplifier circuit (4), and the output of the differential amplifier circuit (4) is applied to the position signal switching circuit (7) in a current mirror format. Ru. The other ends of the armature windings (3) are commonly connected and connected to the inverting input (2) of the differential amplifier circuit (9), and the non-inverting input (11) of the differential amplifier circuit (9) is connected to the voltage divider OQ. The voltage T of the power supply αQ is applied by the voltage T of the power supply αQ. Differential amplifier circuit (9)
The output is a current mirror type position signal switching circuit (5)
is applied to.

The operation of FIG. 1 will now be explained assuming that transistors Q and Q4 are in a conductive state. The armature current is tonister Q
8→Winding Ll) Winding -→Transistor Q4→Resistance 0 The voltage at terminal α→ is compared with the torque command input voltage (2), and the negative feedback circuit makes the error zero. controlled by. As a result, the flow rate m is controlled by the torque command voltage (g), and therefore the torque generated by the motor is controlled by the torque command voltage α. On the other hand, winding L
I, L2. The common connection point of L8 is maintained at the power supply type voltage T by a negative feedback circuit formed by a differential amplifier circuit (9). Therefore, the potential of the armature winding (3) changes around the value of 7 of the power supply voltage, and since transistors Qa-Q4 operate with almost the same collector-emitter voltage, the torque command voltage or motor rotation speed By increasing winding L1@L8
If the voltage across transistors Q8 and Q increases
4 reaches saturation to approximately the same extent, and the utilization rate of the power supply voltage is improved.

This power supply voltage is set sufficiently high so as not to saturate the transistor Q8 or Q4 in order to obtain the generated torque necessary for starting and rotating the motor.

Here, between the collector and emitter of transistors Q8 and Q4, there is a voltage drop of 0 resistor from the power supply voltage, and a voltage drop between the windings Ll and L
A voltage is applied that is the sum of the voltage drop due to the DC resistance of No. 8 and the back electromotive force of winding L8 due to the rotation of the motor. However, when the armature current is small or the motor rotation speed is low, Transistor Qa - Collector of Q4
The emitter voltage is high, and the power consumption of the transistors Qa-Q4 is large, which is disadvantageous in that power loss is large.

Also, if the power supply voltage is lowered, transistor Q8 or Q
4ti' becomes saturated 1', and at that time, the transistor Q1. Since the base current also flows through Q2-Qs or Q6, an armature current that is harmful to the torque generated by the motor flows, causing problems such as torque loss or abnormal vibration.

The above-mentioned inconveniences are major drawbacks in reducing the size and power consumption of equipment in which brushless motors are used.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the prior art described above.
The present invention provides a brushless motor that stably prevents saturation of an output transistor, reduces power consumption of the output transistor, and eliminates unnecessary torque loss and abnormality.

Composition of the Invention The brush toss motor of the present invention includes a multi-pole magnetized permanent magnet rotor, a multi-phase armature winding whose one end is connected in common, and
a position detector that detects the rotational position of the rotor and the armature winding; a pair of push-pull output transistors in a number equal to the number of phases connected to each phase of the armature winding;
a switching mode power supply with a variable output voltage inserted in series in the current path of the armature winding; a first current detection means for detecting the current of the armature winding; and an output of the first current detection means. a first amplifier that amplifies the difference between the signal and the motor torque command input signal; and an output of the first amplifier is switched according to the output of the position detector, and one transistor group of the output transistor pair is used for the military aircraft. a first position signal switching means for determining the energized phase of the child winding; a second current detection means for outputting a signal according to the base current of the one transistor group; and the first and second current detection means. a second amplifier for amplifying the difference between the respective output signals of the means;
a second position signal switching means that switches the output of the second amplifier according to the output of the position detector and determines the energization phase of the armature winding by the other transistor group of the output transistor pair; eighth current detection means for outputting a signal according to the base current of the transistor group of nu;
an eighth amplifier for amplifying the difference between the respective output signals of the first and eighth current detection means, the ratio of the base current of the one transistor group to the current flowing through the first current detection means; controlling the conduction state of the other transistor group by the second amplifier so as to keep it constant;
The output voltage of the switching mode power supply is controlled by the output signal of the eighth amplifier so that the ratio of the base current of the other transistor group and the current flowing to the first current detection means is also maintained at a constant value ζ. It is configured to generate torque according to the command input signal, and by suppressing the power loss of the output transistor to the necessary minimum and preventing saturation, it is possible to eliminate unnecessary torque loss and abnormal vibration. It is possible.

DESCRIPTION OF EXAMPLES Hereinafter, embodiments of the present invention will be described based on the drawings. Figure 2 shows its constituent factors.

The permanent magnet rotor (1) is magnetized to 8tai, and the 8-phase staggered rotor winding (3) is composed of windings Lt, L2°, L8, which are commonly connected at one end.

The rotational positions of the rotor (1) and armature winding (3) are detected by a position detector (2), and applied to position signal switching circuits # (6) and (7) as an 8-set model number. Position signal switching circuit (
5) has an 8-differential configuration using NPN transistors and drives the output transistor group (6). Position signal switching circuit (7
) has an 8-differential configuration using PNP) transistors and drives the output transistor group (8). Output transistor n (6
) is a PNP) transistor Q1゜Q whose emitters are commonly connected to the output terminals of the switching mode power supply (to)
2. The output transistor group (8) consists of NPN transistors Q4*Qs#Q6 whose emitters are commonly connected to the current detection resistor Ql. Transistors Ql and Q4. Q2 and Q5-Q8 and Q6 each have a common collector winding L8. L2. It is connected to L-ri. Two current output terminals #O by current mirror
The non-inverting input (10) of the differential amplifier circuit (4) having 1) is connected to the supply terminal of the torque command voltage (T), and the inverting input (-) is connected to the resistor (to) and the output transistor group (8). Connected to the common emitter connection point α◆. Output terminal α
The output terminal (to) is connected to the common emitter of the position signal switching circuit (7), and the output terminal (to) is connected to the non-inverting input (+) of the differential amplifier (e) together with a resistor whose one end is grounded.

The inverting input (-) of the differential amplifier) is connected to the connection point O◆ between the resistor 03 and the transistor group (8), and the output is connected to the low-pass filter υ and the current mirror transistor Qta.
It is connected to the emitter of the position signal switching circuit (5) via p Q18. Transistor QI4 forms a current mirror together with transistor Q15C1a, and transistors Q18 . Q14 outputs an equal current.

The collector of transistor Q14 is transistor Qta.
e Continued to a common base of Q10. The emitters of the transistors Q16'JI7 are commonly connected to the power supply 0Q, and the transistor Q17 is diode-connected to form a current mirror. The collector of the transistor Q16) is grounded through the resistor) and connected to the non-inverting input (10) of the differential amplifier.The inverting input (-) of the differential amplifier is connected to the resistor). Connected to the connection point σ4 with the transistor group (8), and the output is sent to the filter)
is connected to the control terminal of the switching mode power supply (to). The wt source terminal of the switching mode power supply) is connected to the power supply αQ.

Next, the operation shown in FIG. 2 will be explained. The armature mold flow is
Switching mode power supply (A) → Output transistor group (
6) Flows through the path of 1st winding (3) → output transistor R(8)-e resistor), differential amplifier circuit (4) 2-position switching circuit (7), output transistor group (8), and resistor The differential input of the differential amplifier circuit (4) is controlled to be zero by the negative feedback loop constituted by 03. Now, the rotor (
It is assumed that among the output transistors Q1 to Q6, only transistors Q8 and Q4 are in a conductive state due to the positional relationship between 1) and the armature winding (a). Only the emitter current of the transistor Q4 flows through the resistor 03. The pace current I4 of the transistor Q4 is connected to the current output terminal O of the differential amplifier circuit (4).
A current of the same magnitude is also supplied from the current output terminal to the resistor I. Resistance (6) and resistance a'
The ttO value and the flowing current value are respectively R1[1,R
17 and l1ls 117, the input voltage V20 of the differential amplifier (to the differential amplifier) is Vmo='Rt7°'17-Rl11'118°"
-==---(1). Also, the current amplification factor hFl] of the transistor Q4 is I4'''117, so the equation (1) becomes as follows.The held of the transistor Q4 changes with the collector-emitter voltage Voff as shown in FIG. Therefore, the differential amplifier (e), low-pass filter ←]), position signal switching circuit (5), output transistor Q8, and winding.

When the loop gain of the negative feedback loop consisting of L8, output transistor Q4, and resistor (c) is sufficiently high, the input f
'll Transistor Q so that the voltage Vg o is zero
The collector-emitter operating voltage of 4 is automatically determined.

Therefore, it follows from equation (3). Since the right side of equation (4) is constant, the hpm of transistor q is constant. When the torque command voltage changes, the emitter current of transistor Q4 also changes, and from FIG. 8, the collector-emitter voltage of transistor Q4 also changes automatically. In other words, since the collector-emitter voltage of transistor Q4 is automatically controlled according to the emitter current so that the current amplification factor is kept constant, winding L1. L8
The potential across both ends of the armature is determined according to the armature current, resulting in stable operation.

The collector-emitter voltage of transistor Q8 decreases due to an increase in the armature winding back electromotive force as the motor rotation speed increases, or an increase in the armature winding DC voltage drop as the armature current increases. As shown in FIG. 8, when the collector-emitter voltage of the transistor decreases, the current amplification factor also decreases, so the base current of transistor Q8 increases compared to the collector current. The base current Ia of the transistor Q3 is supplied from the transistor Q1B via the position signal switching circuit (5), and its magnitude is equal to the collector current of the transistor Q14. It is applied to the resistor () through the transistor Q17°Q16.Therefore, if the current value of (lower paper) is I2□, then it is 122-18°...
・・・・・・・・・・・・ (5).

On the other hand, the collector current ios of transistor Q8 flows through winding L1. The collector current of transistor Q4 increases through L8, and the current amplification factor 11FF of transistor Q4 is expressed by the formula (4
), so it becomes .

Therefore, from equation (6) becomes.

The input voltage Vat of the differential amplifier is as follows: V24""R2□・IS R11l・11B・
・・・・・・・・・・・・ (8) and formula (7) #
(8) From now on.

Transistor Qa (17) h, Il' improves with the collector-emitter voltage as shown in Figure 8, like transistor Q4, so it can be used as a differential amplifier (c), low-pass filter), switching mode power supply ( e), output transistor Q8, winding L 171tF L @s When the loop gain of the negative feedback loop consisting of output transistor Q8 and resistor (2) is sufficiently high, the output voltage of transistor Q8 is set so that the input voltage Vl becomes zero. Collector-emitter operating voltage is automatically determined. Therefore, it follows from equation (9). Since the right side of equation Q0 is constant, h of transistor QJI
ail' is constant 1 (nah.

Here, the output voltage of the switching mode power supply (E) changes depending on the level of the control input, that is, the output voltage of the differential amplifier (C).

When the torque command 111EEIE(c) changes, the emitter current of the transistor Q4 and also the emitter current of the transistor Q8 change, and as shown in FIG. 8, the collector-emitter voltage of the transistor Q8°Q4 also changes automatically.

This voltage is determined by the characteristics of the transistor QB=Q4, and is the minimum voltage required to cause a predetermined emitter current to flow.

Furthermore, since the current amplification factor is automatically determined according to element variations and transistor temperature changes and is kept constant, the transistor Qs j-' Q4 maintains an operating state with the lowest power consumption without saturation. The output voltage of the switching mode power supply (switching mode power supply) is the voltage between the collector and emitter of transistor Q8, the voltage drop due to the winding, the DC resistance of L8, the voltage between the collector and emitter of transistor Q4, the voltage drop across the resistor, and It is equal to the sum of the motor back electromotive voltages, and the difference from the power supply al is the internal loss of the switching mode power supply. However, since it is a switching mode power supply, the power efficiency related to voltage conversion is sufficiently high, and the power loss due to changes in armature current or motor rotation speed is lower than in a case where a series control type power supply is used. much smaller. Also, the filter) is a low-pass filter that improves the stability of the negative feedback loop that includes the differential amplifier.

FIG. 4 shows one embodiment of a variable output voltage switching mode power supply. The collector of the switching transistor Q1B, whose emitter is connected to the power supply terminal (2), is connected to the output terminal via the coil (2). Diode (a)
has a cathode connected to the collector of transistor Q1g, and an anode grounded. The output terminal 3θ is grounded via a smoothing capacitor. The inverting input (-) of the comparator (to) is connected to the output terminal (), and the non-inverting input (+
) is connected to the control terminal (c). The output of the comparator) is applied to the control circuit 0η and further applied to the base of the switching transistor QsB. The control circuit 0 controls the switching state of the transistor Q1a, and the output voltage is fed back to the comparator (to) through a smoothing circuit composed of a diode), a coil), and a capacitor (2).

The negative feedback loop operates so that the difference between the voltage applied to the control terminal (to) and the output voltage becomes zero, and the output voltage follows the voltage at the control terminal (to).

In the above embodiment, as the motor rotates, the rotor (1
) and the rotational position of the armature winding (3) and which of the transistors Q1 to Q6 is turned on changes, the operating potential of the transistors Q1 to Q6 corresponds to the winding current with the same operation as described above. and change stably.

Although the above embodiment has been described for the case of 8 phases, the present invention is not necessarily limited to 8 phases, and various modifications (for example, position signal switching circuit (5)) may be made without changing the gist of the present invention.
Alternatively, insert a current amplification circuit on the output side of (7) and increase the value of the resistance α force or resistance by the amount corresponding to the amplification factor, or connect the current output terminal (c) to the It goes without saying that there are many applications in which the current mirror transistor Q1s*Ql4 ratio is set to a value other than 1 and the value of the resistor α'I) is changed.

Further, there are various systems for switching mode power supplies, but it is clear that the gist of the present invention is not impaired by these systems.

As described in detail, the brushless motor of the present invention controls the power of the output transistor by controlling the collector-emitter voltage of the output transistor with a switching mode power supply so that the current amplification factor is always constant and can be predetermined with a resistor. By suppressing loss to the necessary minimum and preventing saturation of the output transistor, unnecessary torque loss and abnormal vibration can be eliminated. In addition, the collector-emitter operating voltage of the output transistor may vary due to element variations.
Since it automatically follows the operating current or transistor temperature, extremely stable operation can be achieved. Therefore, it is particularly effective in reducing the size and power consumption of equipment using brushless motors.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional example of a brushless motor, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 8 is a graph showing the relationship between collector-emitter voltage and current amplification factor of a transistor, and Fig. 4 1 is a configuration diagram of an embodiment of a switching mode power supply. (1)...rotor, (2)...position detector, (3)
... Armature winding, (4) ... Differential amplifier circuit, (5)
(7)...Position signal switching circuit, (6)(8)...
Output transistor group (to 11aη) ---resistance, OQ
...torque command voltage, wire (c)...differential amplifier, Q
◇)...Filter, N)...Switching mode power supply, ■...Comparator, 0υ...Control circuit, @...Output terminal, N)...Control terminal, Be...Power supply Terminal agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. Detecting a multi-pole magnetized permanent magnet rotor, a multi-phase armature winding whose one end is commonly connected, and the rotational position of the rotor and the armature winding. a position detector, push-pull output transistor pairs of a number equal to the number of phases connected to each phase of the armature winding, and inserted in series in the current path of the child winding. a switching mode power supply with a variable output voltage, a first current detection means for detecting a current in the armature winding, and a difference between an output signal of the first current detection means and a motor torque command input signal.゛[ru 1st
and a first position signal that switches the output of the first amplifier according to the output of the position detector and determines the energizing phase of the armature winding by one transistor group of the output transistor pair. a switching means, a second current detecting means for outputting a signal corresponding to the base current of the one transistor group, and amplifying and reproducing the difference between the respective output signals of the first and second current detecting means. a second amplifier, and the output of the second amplifier is switched according to the output of the position detector, and the energization phase of the armature winding by the other transistor group of the output transistor pair is determined 1°@2 a position signal switching means, an eighth current detecting means for outputting a signal corresponding to the base current of the other transistor group, and amplifying the difference between the respective output signals of the first and eighth current detecting means. an eighth amplifier, the conduction state of the other transistor group is controlled by the second amplifier so as to maintain a constant ratio between the base current of the one transistor group and the current flowing to the first current detection means. and controlling the output voltage of the switching mode m source by the output signal of the eighth amplifier so that the ratio of the base current of the other transistor group and the current flowing to the first current detection means is also kept constant. The brushless smoke generates torque according to the torque command input signal. 2. A first current mirror and a first resistor are used as the second current detection means, a current output type differential amplifier is used as the first amplifier, and the current output is detected by the first current mirror. Claim 1 characterized in that the voltage across the first resistor is distributed between a position signal switch and the first resistor, and the voltage across the first resistor is connected to the output of the second current detecting means. Brushless motor as described in section. 8. As the eighth current detection means, a second current mirror and a second resistor are used, a current output type differential amplifier is used as the second amplifier, and the current output is detected by the second current mirror. 2 position signal switching devices and the second resistor, and the heavy pressure across the second resistor is used as the output of the eighth current detecting means. Brushless motor as described. 4. The switching mode power supply includes a power supply terminal, an output terminal, and a control terminal, and outputs a voltage corresponding to the output voltage of the eighth amplifier applied to the control terminal. Brushless motor as described in Range 1.