JPH0227919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor that generates force according to power supplied to a coil, and particularly to a motor that reduces unevenness in the generated force.

It is widely known that according to Fleming's law, the force generated by a motor is determined by the product of the magnetic flux generated by the field magnet and the current supplied to the coil.
Generally, the magnetic flux generated by a field magnet varies depending on the location. Therefore, when a constant current is passed through the coil, the force generated changes as the relative position between the magnet and the coil changes, causing unevenness in the force, which has been a problem. In particular, in brushless motors that are widely used in audio/visual equipment, it is desired to minimize the unevenness of the generated force in order to improve the performance of the equipment.

The applicant has addressed this problem by filing a patent application
No. 52-67671 proposes a motor with an iron core structure that generates uniform force. This proposal is extremely useful for motors with a slotted core structure. However, when a smooth iron core without a slot is used, such as in a slotless motor or a coreless motor, it is extremely difficult to obtain a uniform generated force.

The present invention was made in consideration of such points, and cancels local fluctuations in field magnetic flux by partially modulating the power (current or voltage) supplied to the coil in motors with various structures. death,
It is designed to generate a uniform force with little unevenness.

That is, the configuration of the present invention includes a field means including a field magnet attached to the rotor;
A multiphase coil, a power supply means for controlling the current supplied to the coil, a command signal for commanding the current supply to the coil, and a predetermined voltage value are compared, and a first voltage value is set according to the difference voltage between the two. a current conversion means for outputting a current signal; a similar current generation means for obtaining a second current signal and a third current signal proportional or substantially proportional to the first current signal using a current mirror; and a similar current generation means synchronized with the rotation of the magnet. the third current signal is input to a current input terminal, and the modulation signal is input to a voltage input terminal; a modulating means for obtaining a fourth current signal obtained by modulating the current signal of No. 3 by the modulation signal; and a synthesizing means for synthesizing the second current signal and the fourth current signal, the synthesizing means A current proportional or substantially proportional to the output signal is supplied to the coil by the power supply means, thereby achieving the intended purpose.

Hereinafter, this will be explained based on the illustrated embodiment, taking a brushless motor as an example. 1st
The figure is a circuit wiring diagram showing one embodiment of the present invention. In Fig. 1, 11 and 12 are DC power supplies;
3 is a field magnet attached to the rotor; 14, 15, and 16 are three-phase coils interlinked with the magnetic flux generated by the magnet 13; 17 is a command signal;
8 is a voltage source, 19 is a current converter (see Figure 2) that compares the voltage values of the command signal 17 and the voltage source 18 and outputs (sinks) a current _i1 corresponding to the difference, and is surrounded by a broken line. 20 is a similar current generator that responds to the output current i ₁ of the current converter 19 and generates currents (similar currents) i ₂ and i ₃ with fixed relative ratios, and 21 is a current that generates the modulation signal i ₄ a modulated signal generator including a source 48, 2
2 is a modulator which obtains an output signal i ₅ by modulating the similar current i ₃ in response to the modulation signal i ₄ ; 23 is a combiner which obtains a signal obtained by combining the similar current i ₂ and the modulation current i ₅ ; and 24 is a combiner. This is a power supply device that supplies current (or voltage) corresponding to the output signal of 23 to the coils 14, 15, and 16.

Next, its operation will be explained. Command signal 1
7 is a voltage signal that changes in accordance with the rotational speed of the magnet 13 (rotor rotational speed) obtained, for example, by a frequency generator and a speed-voltage converter, and when the speed is slow, the voltage value becomes small;
As the speed increases, the voltage value increases. The command signal 17 is input to the current converter 19, converted into a current corresponding to the difference from the voltage value of the voltage source 18, and outputted (current absorption).

FIG. 2 shows a specific circuit example of the current converter 19. Command signal 17 and voltage source 18 are applied to the base sides of transistors 101 and 102, respectively, forming a differential circuit, and the current of current source 105 is distributed to the respective collector sides according to the voltage difference between the two. The collector currents of transistors 101 and 102 are compared by a current mirror made up of transistors 106 and 107, and a current i ₁ corresponding to the difference current is output (sucked) via transistor 108.

The output current i ₁ of the current converter 19 is input to a similar current generator 20, which generates two currents i ₂ and i ₃ with fixed relative ratios that are proportional (or approximately proportional) to i ₁ .
Similar current generator 20 includes transistors 41 and 4
2, 43, 44 and resistors 45, 46, 47. Here, the relative ratio of the resistance values of resistors 45, 46, 47 is 2r:r:2r.
By setting the emitter area ratio of the transistors 42, 43, and 44 to 1/2r:1/r:1/2r, the currents i ₁ , i ₂ , and i ₃ are set to 1:2:1.

The current i ₃ is input to the modulator 22, and a current i ₅ modulated according to the modulation signal i ₄ of the modulation signal generator 21 is obtained. The modulation signal generator 21 is a magnet 13
A modulation signal _i4 synchronized with the rotation of is generated. The modulator 22 is composed of a differential circuit including transistors 49, 50 and diodes 51, 52, and bias resistors 53, 54, 55. Current i ₃ is input to the emitter side common connection terminal of transistors 49 and 50, and modulation signal i ₄ and a voltage signal for modulation by resistor 55 are input to the base terminal of transistor 49, which is the voltage input terminal of the differential circuit. has been done. As a result, the output current i ₅ is: when i ₄ = 0, i ₅ = i ₃ /2, when i ₄ = Max, i ₅ = 0, when 0 < i ₄ < Max, 0 < i ₅ < i ₃ /2. ing.

The similar current i ₂ and the modulated current i ₅ are combined by a combiner 23 consisting of a diode 56 and a resistor 57, and the voltage v across the resistor 57 is the combined value of both currents (i ₂ +
i ₅ ).

The power supply 24 includes three-phase coils 14, 15,
16, a current detector 34 consisting of a resistor 61 inserted in series in the current path between the coil and the power supply, and an output voltage of the current detector 34. Synthesizer 2
a controller (see Fig. 3) which receives the output voltage of 3 and outputs a current i ₆ in response to both voltage signals;
A position detector 37 consisting of Hall elements 69, 70, 71 that detects the magnetic flux generated by the magnet 13, and a position detector 37 that selects the drive transistor (therefore, the coil) to be energized in response to the output of the Hall elements 69, 70, 71. The selector 36 includes dynamic transistors 64, 65, and 66.

FIG. 3 shows a specific example of the configuration of the controller 35.
The output voltage of the synthesizer 23 is applied to the base side, and the detection signal of the current detector 34 is applied to the emitter side.
12, 113), and obtains an output current _i6 responsive to the base-emitter voltage of the transistor 111.

The output current i ₆ of the controller 35 becomes a common emitter current of the differential transistors 64 , 65 , 66 of the selector 36 , and the Hall elements 69 , 7 of the position detector 37
The output voltage of 0,71 is the differential transistor 64,6
The transistors 64, 65, and 66 distribute the emitter current _i6 to the collector side depending on the base voltage. That is,
The transistor with the lowest base voltage is the most active, and the other transistors are inactive. As a result, the transistor that is activated by the output of the position detector 37 is selected.

The collector currents of the transistors 64, 65, and 66 become the base currents of the drive transistors 31, 32, and 33, and are amplified and passed through the coils 14, 1.
Current (power) is supplied to 5 and 16. coil 1
The currents supplied to the transistors 4, 15, and 16 (currents flowing through the drive transistors 31, 32, and 33) are combined and detected by a current detector 34, and the output voltage thereof is input to a controller 35.

In this way, drive transistors 31, 32, 3
3, a current detector 34, and a controller 35 constitute a feedback loop (the selector 36 only performs switching and is not important in the feedback leap).
h The influence of inter-phase variation due to _FE variation etc. is reduced, and the current I ₀ supplied to the coils 14, 15, 16 is reliably set to a value corresponding to the output voltage of the combiner 23. Note that 62 is a capacitor for phase compensation (prevention of oscillation) of this feedback loop. Also,
A series circuit of capacitors 81, 83, 85 and resistors 82, 84, 86 connected in parallel to the coils 14, 15, 16 reduces the spike voltage caused by switching of the coil to be energized.

In the balanced state of this feedback loop, V _D56 + R ₅₇ · (i ₂ + i ₅ ) = V _BE111 + R ₆₁ · I ₀ (1) (see Figures 1 and 3). Here, V _D56 is the forward voltage of diode 56, V _BE111 is the base-emitter forward voltage of transistor 111, and R ₅₇
and R ₆₁ are the resistance values of resistors 57 and 61, respectively.

Normally, V _D56 = V _BE111 , so the current I ₀ supplied to the coil is I ₀ = (R ₅₇ /R ₆₁ )·(i ₂ +i ₅ ) (2). That is, the current I ₀ supplied to the coil is proportional to the composite value (i ₂ +i ₅ ) of the similar current i ₂ and the modulated current i ₅ .

In this way, if the current I ₀ supplied to the coil is changed in response to a modulation signal synchronized with the rotation of the motor, a uniform generated force can be obtained. Next, this will be explained with reference to the waveform diagram for explaining the operation in FIG. Figure 4a shows the magnetic flux density generated by the magnet 13 applied to the coils 14, 15, and 16, with the rotational position of the magnet 13 taken as the horizontal axis. change. In order to obtain connected rotational force in the same direction, in a brushless motor, the rotational position is detected by the position detector 37, and the coil to be energized is selected by the selector 36 and current is supplied. ing. The energized section is the fourth
It is written in the upper part of figure a. Now, if a constant current _I0 is supplied to the selected coil, according to Fleming's law, the generated force is proportional to the product of the magnetic flux density and the current, and it varies depending on the location as shown by the solid line in Figure 4a. will start to fluctuate significantly. This variation in generated force is caused by local changes in magnetic flux density, so it is inherent to the motor structure. Once the motor structure is determined, its waveform and rate of variation are also determined, and there is almost no variation during mass production. It's fleeting. Therefore, if the current _I0 supplied to the coil is changed in response to a signal synchronized with the rotation of the magnet as in the present invention, a uniform generated force can be obtained.

FIG. 4b shows the waveform of the current (modulation signal) i ₄ of the current source 48 of the modulation signal generator 21, which is a periodic signal synchronized with rotation corresponding to fluctuations in magnetic flux density. modulator 22 modulated by modulation signal i ₄
The output current i ₅ changes depending on the rotational position as shown in FIG. 4c. That is, when i ₄ = Max, i ₅
= 0, and as i ₄ becomes smaller than Max, i ₅
increases, and when i ₄ = 0, i ₅ becomes a similar current i ₃
It becomes 1/2 of Therefore, the composite current (i ₂ + i ₅ ) is the fourth
The result is as shown in Figure d. Supply current to the coil I ₀
is proportional to (i ₂ + i ₅ ) from equation (2), so its waveform is similar to (i ₂ + i ₅ ). Since the generated force is the product of the current I ₀ (Figure 4 d) and the magnetic flux density (solid line in Figure 4 a), the generated force of the motor of the present invention is as shown in Figure 4 e, and is uniform with little fluctuation. You can get a lot of power.

Here, the currents i ₂ and i ₃ are both generated by the similar current generator 20
Although its absolute value changes in response to the command signal 17, the relative ratio between i ₂ and i ₃ is always constant (i ₂ :i ₃ =1:2). Therefore, the command signal 17
_{Regardless of} the _{value of} This results in a changing current (the values of i ₂ and I ₀ change in response to the command signal 17). As a result, the unevenness of the generated force is significantly reduced whether a small current or a large current is supplied.

In this way, two current signals i ₂ and i ₃ with a fixed relative ratio are generated in response to the command signal 17, and one of the current signals i ₃ is synchronized with the rotation of the motor (corresponding to the rotational position of the motor). _{The modulated signal i 5 and} the current signal i ₂ are combined to generate a current I ₀ proportional to the combined current (i ₂ + i ₅ ).
If the power is supplied to the coil, the unevenness of the force generated by the motor can be easily reduced. In addition, since the rate of change (maximum value/minimum value) of the current _I0 supplied to the coil is less affected by the magnitude and waveform variations of the modulation signal _i4 , performance during mass production is stable (the unevenness of the generated force is small).

To explain this, the modulation signal i ₄ can be obtained by: (1) A dedicated detector (a multi-pole magnet is attached to the rotor and a Hall element is attached to the stator) for generating the modulation signal is provided.

(2) It is created by a method such as combining the output voltage signals of the Hall elements 69, 70, 71 of the position detector 37 of the power supply 24. Generally, the magnitude and waveform of the modulation signal _i4 vary considerably depending on the individual motors during mass production (for example, the sensitivity variations and installation variations of Hall elements are quite large). Therefore, if the output current of the current converter 19 is directly modulated by the modulation signal _i4 , there will be large variations in mass production, and it will not be possible to stably obtain a current signal with the required rate of change. However, as in the above-mentioned embodiment, two current signals i 2 and i 3 with a fixed relative ratio are generated in response to the command signal 17 by the similar current generator 20, and one of the current signals i ₂ and i ₃ is
i ₃ is modulated with a modulation signal i ₄ synchronized with the rotation of the motor, the modulated signal i ₅ and current signal i ₂ are combined, and a current proportional to the combined current (i ₂ + i ₅ ) is applied to the coil. If the configuration is configured such that the modulation signal i ₄ is supplied to the coil, the waveform of the current I ₀ supplied to the coil will be slightly affected by the variation in the modulation signal i 4 , but the rate of change will hardly change (the output current of the modulator 22 will be (Limited to a maximum of i ₃ /2 and a minimum of 0).
The result is a high-performance motor that is sufficiently stable even during mass production, with little unevenness in generated force.

Furthermore, as shown in the above-described embodiment, the power supply 24 receives the current detector 34 that detects the current supplied to the coil, the outputs of the current detector 34 and the combiner 23, and responds to both of them. If the configuration includes a controller 35 that obtains an output signal and a drive transistor that supplies a current to the coil according to the output of the controller 35, the current _I0 supplied to the coil is converted to the combiner 2.
A feedback loop having a value corresponding to the output signal No. 3 is formed, and the effect of reducing unevenness in the force generated by the motor of the present invention becomes stable.

Further, although the above-described embodiments have been described using a brushless motor as an example, the present invention is not limited to such a case, but can also be applied to a brushed motor. FIG. 5 shows a circuit connection diagram representing another embodiment of the present invention. In Fig. 5, 91 is a brush.
This is a driving force generating section of the motor to which current is supplied to the coil via the commutator, and 92 is a capacitor for ripple removal. In addition, the power supply 24
is one drive transistor 31 and current detector 34
and a controller 35, forming a feedback loop to ensure that the current I ₀ supplied to the coil responds to the output signal of the combiner 23. The other configurations and operations are the same as those of the embodiment shown in FIG. 1 described above, and their explanations will be omitted.

Further, the configuration is not limited to supplying current in one direction to the three-phase coils, but it is also possible to supply current in both directions (for example, the method described in Japanese Patent Publication No. 55-6938). Furthermore, the present invention is applicable not only to motors having three-phase coils but also to motors having multi-phase coils in general. In addition, various modifications are possible without changing the gist of the present invention.

As described above, according to the present invention, it is possible to significantly reduce the unevenness of the force generated by the a motor, and this can be easily configured using a similar current generation means using a current mirror, a modulation means using a differential circuit, etc., and the magnitude of the modulation signal is Because it is less susceptible to variations in the sheath waveform, it is possible to stably reduce the unevenness of generated force during mass production.Furthermore, the current supplied to the coil can be changed in an analog manner using an analog modulation signal, which reduces the generated force. Effects such as being able to sufficiently reduce unevenness can be obtained. Therefore, if a brushless motor for audio/visual equipment is constructed based on the present invention, a stable and high-performance device can be obtained.

[Brief explanation of drawings]

Fig. 1 is a circuit connection diagram representing an embodiment of the present invention, Fig. 2 is a diagram of a specific configuration example of a current converter, Fig. 3 is a diagram of a specific configuration example of a controller, and Fig. 4 is an operation diagram. The explanatory waveform diagram and FIG. 5 are circuit connection diagrams representing another embodiment of the present invention. 11, 12... DC power supply, 13... Magnet, 14, 15, 16... Coil, 17... Command signal, 19... Current converter, 20... Similar current generator, 21... Modulation signal generator , 22...Modulator, 23...Synthesizer, 24...Power supply, 3
1, 32, 33...drive transistor, 34...
Current detector, 35...controller, 36...selector,
37...Position detector.

Claims (1)

[Claims] 1 A field means consisting of a field magnet attached to a rotor, a multiphase coil, a power supply means for controlling the current supplied to the coil, and a command signal for commanding the current supply to the coil. a current converter that compares predetermined voltage values and outputs a first current signal according to the difference voltage between the two; and a current mirror that outputs a second current signal that is proportional or approximately proportional to the first current signal. a similar current generating means for obtaining a third current signal; a modulating signal generating means for obtaining a modulating signal that changes in synchronization with the rotation of the magnet; the third current signal is input to a current input terminal, and the modulating signal is a modulation means configured to include a differential circuit input to a voltage input terminal and obtains a fourth current signal obtained by modulating the third current signal with the modulation signal; Fourth
1. A motor comprising a synthesizing means for synthesizing current signals of the synthesizing means, the electric power supply means supplying a current proportional to or substantially proportional to an output signal of the synthesizing means to the coil.