JPS6226274B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for a commutatorless DC motor.

Conventionally, in this type of drive device, as shown in FIGS. 1 and 2, there is a stator coil L _A of a first phase A in which coils 1 and 2 are connected in series, and coils 3 and 4.
The stator coil L of the second phase B connected in series with
_B forms a two-phase stator coil. These coils 1, 2, 3, and 4 are arranged on a concentric circle centered on a rotation axis (not shown) on the surface of the stator yoke 5. Corresponding to the surface of the stator yoke 5, as shown by the two-dot chain line, a rotor magnet 6 magnetized into ten poles is rotatably arranged so that the magnetic flux distribution becomes a sinusoidal wave.

On the other hand, Hall elements 7 and 8 for detecting the magnetic pole position of the rotor magnet 6 are also arranged on concentric circles centered on the rotation axis (not shown) on the surface of the stator yoke 5, corresponding to each phase A and B. has been done.

The stator coils L _A and L _B are arranged so that their phases differ from each other by an odd multiple of 90 degrees in electrical angle, and the Hall elements 7 and 8 also correspond to the stator coils L _A and L _{B of phases A and B} , respectively. and the magnetic poles of the rotor magnets 6 are placed at a position where the magnetic poles of the rotor magnets 6 are detected, at a distance of 90 electrical angles from each other.
゜Arranged at positions with different phases.

Next, to explain the drive circuit, one phase A
Output terminals 7a, 7b of the Hall element 7 corresponding to are connected to input terminals 9a, 9b of the amplifier 9.
The output terminals 9c and 9d are the input terminal 10 of the output circuit 10.
a, 10b. Output ends 10c and 10d of the output circuit 10 are connected to the stator coil _LA . As for the other phase B, same as one phase A,
The Hall element 8, the amplifier 11, the output circuit 12, and the stator coil L _B have the same circuit configuration.

Input terminals 7c, 7d, 8c of Hall elements 7, 8,
8d are connected in series and further grounded via the current controller 13. And a power generation coil 14 of a frequency generator that detects the rotational speed of the rotor magnet 6.
are the input terminals 15a, 15 of the frequency-voltage converter 15
The output terminal 15c of the frequency-voltage converter 15 is connected to the input terminal 16a of the low-pass filter 16, and the output terminal 16b of the low-pass filter is connected to the control input terminal 13a of the current controller 13.

To explain the operation of the conventional example with the above configuration, the change in the position of the magnetic pole due to the rotation of the rotor magnet 6 is detected by the Hall elements 7, 8, and the output voltage of the Hall elements 7, 8 is proportional to the change in the position of the magnetic pole. The resulting sinusoidal voltage is amplified by amplifiers 9 and 11, the output control circuits 10 and 12 are controlled by the outputs of amplifiers 9 and 11, and sinusoidal current is passed back and forth through the stator coils _LA and _LB. The rotor magnet 6 is urged to rotate. The rotational speed control is detected by the power generation coil 14.
The frequency proportional to the rotational speed obtained by the frequency −
After converting into voltage with the voltage converter 15, high frequency components are removed with the low pass filter 16 and the Hall elements 7, 8 are controlled by controlling the current controller 13.
This is done by increasing/decreasing the input current of , changing the output voltages of the Hall elements 7 and 8, and controlling the amount of current flowing through the stator coils _LA and _LB.

Considering the operating conditions of the electric motor, when the motor is used at low speed or under light load, the amount of current applied to the stator coils L _A and L _B may be small.

In the conventional drive device, the Hall element 7,
By controlling the input current of 8, stator coils L _A and L _B
Since the amount of current supplied to the Hall element is controlled, as mentioned above, the input current of the Hall element is small in low speed rotation and light load conditions, so the output voltage is also small, and the amplifier circuits 9 and 11 have an offset voltage. Therefore, if the input voltage to the amplifiers 9 and 11 is small, the offset voltage cannot be ignored. Therefore, the output voltage V _H of the Hall elements 7 and 8 shown in FIG.
As the offset voltage V _OFF of _the amplifiers 9 _and 11 shown in _FIG . It had been used as an amplifier. Therefore, stator coils L _A , L _B
The current flowing through the shaft did not correspond to the output voltage of the Hall element, and accurate rotational speed control could not be obtained.

The present invention provides a drive device for a non-commutated DC motor that can obtain stable rotation by ignoring errors caused by the offset voltage of the amplifier circuit, etc., and is shown in FIGS. 4 and 5. An embodiment of the present invention will be described with reference to FIG. 1. First, the stator coils L _A and L _B and magnetically sensitive elements, such as Hall elements 7 and 8, have the structure shown in FIG. 1 as in the conventional example. In one phase C, the output terminals 7a and 7b of the Hall element 7 are the input terminals 17a and 1 of the amplifier 17.
7b, and the output terminal 17c,1 of the amplifier 17
7d is the input terminal 18a of the slice circuits 18 and 19;
19a, and the output terminals 18b, 19b of the slice circuits 18, 19 are connected to the input terminal 20 of the output circuit 20.
a, 20b, and the output terminal 2 of the output circuit 20
0c and 20d are connected to both ends of the stator coil _LA . The other phase D also includes a Hall element 8 and an amplifier 2.
1. The configuration is similar to that of one phase C between the slice circuits 22 and 23, the output circuit 24, and the stator coil _LB. Input terminals 7c, 7d, 8c, and 8d of the Hall elements 7 and 8 are connected in series between the power supply +V _CC and ground via resistors R ₁ and R ₂ .
The generating coil 14 of the frequency generator is connected to the input ends 25a and 25b of the frequency-voltage converter 25, and the output end 25c of the frequency-voltage converter 25 is connected to the input end 26a of the low-pass filter 26. The output end 26b is the control input end 18c of the low-pass filters 18, 19, 22, 23,
It is connected to 19c, 22c, and 23c.

Next, the operation of this circuit will be explained for one phase C. A sufficient input current is passed through the Hall element 7, and a sufficient output voltage V _H (as shown in Fig. 5a) is generated to the extent that the offset voltage of the amplifier 17 can be ignored. ) is obtained between the output ends 7a and 7b of the Hall element. and Figure 5b
As shown in FIG. 5c, the output voltage V _C of the Hall element 7 amplified by the amplifier 17 is sliced by slice circuits 18 and 19 to a certain level V _D as shown in FIG. 5c. This slice level V _D is determined by the rotor magnet 6 by the power generation coil 14 of the frequency generator.
It is controlled by a speed control signal according to the rotation speed of the motor, and when the rotation speed becomes faster, the level becomes lower, and when the rotation speed becomes slower, the level becomes higher. The output circuit 20 is driven by the waveform V _E sliced at a certain level V _D in this way, and a current proportional to the waveform V _E flows through the stator coil _LA . Also, the output waveform V _F of the slice circuits 22 and 23 of the other phase D is shifted by 90 degrees from that of the other phase, as shown in FIG. 5d.

As described above, in the present invention, the input currents of the Hall elements 7 and 8 are not controlled, and a sufficiently large constant current is always passed to obtain a sufficiently large sinusoidal output voltage.
Therefore, even when driving an electric motor under light load or at low speed, the output voltage of the Hall element is sufficiently large, so
The offset voltage of amplifiers 17, 21 as shown in FIG. 3b is negligible. The speed adjustment is performed by slicing circuits 18, 19, 22, and 23 within the sinusoidal waveform of the output voltage amplified by the amplifiers 17 and 21 at a level corresponding to the rotation speed. Also provides stable rotation.

An embodiment embodying the above invention will now be described with reference to FIGS. 6 and 7. As shown in FIG. 1, stator coils L _A , L _B , Hall elements 7,
The two-phase non-commutator DC motor in which 8 is arranged has one phase drive circuit E corresponding to the stator coil L _A and the Hall element 7, and the other phase drive circuit E corresponding to the stator coil L _B and the Hall element 8. A drive circuit F is provided. Since drive circuits E and F have similar configurations, circuit parts common to both drive circuits E and F will be explained first.

Transistors Q ₁ and Q ₂ constitute a differential amplifier of the amplifier circuit α. And Zener diode D _Z1 ,
a constant current circuit β consisting of transistors Q ₃ and Q ₄ ;
Due to the current mirror circuit consisting of transistors Q ₄ and Q ₅ , transistor Q ₅ is connected to transistors Q ₁ and Q ₂
It becomes a constant current source connected to the common emitter of. The bases of the transistors Q ₁ and Q ₂ are connected to the output terminals 7a and 7b of the Hall element 7, respectively, so that between the collectors H and I of the transistors Q ₁ and Q ₂ , there is a connection between the output terminals 7a and 7b of the Hall element 7. A sinusoidal voltage proportional to the differential voltage V _G is generated. The bases J and K of the transistors Q ₆ and Q ₇ are connected in series with the diodes D ₁ and D ₂ and D ₃ and D ₄ , respectively, with respect to the connection points H and I, so both are connected at the connection points. It is higher than H and I by twice the forward voltage of the diode, and the voltage between the connection points H and I is also generated between the connection points J and K. Also, since the connection points L and M are connected to the bases and emitters of transistors Q ₈ and Q ₉ , respectively, from the connection points H and I, both are higher than the connection points H and I by the forward voltage of the diode. Therefore, _a voltage V I is generated between the connection points L and M that is proportional to the voltage between the connection points H and I, that is, the sinusoidal voltage V _G generated between the output terminals 7a and 7b of the Hall element 7. . and hall element 7
When the voltage at output terminal 7a is higher than that at output terminal 7b, transistors _Q6 and _Q9 are conductive;
When the voltage at a is lower than the output terminal 7b, the transistors Q ₇ and Q ₈ are conductive, so the resistance R ₃ between the connection points L and M is proportional to the voltage V _I , that is, the output terminal of the Hall element 7. A sinusoidal current I _A proportional to the voltage V _G generated between 7a and 7b flows in both directions. Then, transistors Q ₁₀ and Q ₁₁ are made conductive alternately. Also, transistors Q ₁₂ and Q ₁₃ with output voltage γ
constitute current mirror circuits 27 and 28, respectively,
Input terminals 27a of current mirror circuits 27 and 28,
28a are connected to the collectors of transistors Q ₈ and Q ₉ , respectively. And the voltage V _G between the output terminals 7a and 7b of the Hall element 7 is applied to the transistors Q ₁₂ and Q ₁₃ .
This allows a sinusoidal collector current proportional to to flow.

On the other hand, the collectors of transistors Q ₁₀ and Q ₁₁ are connected to the bases of transistors Q ₁₄ and Q ₁₅ of slice circuit δ via diodes D ₁ and D ₂ , respectively, and the collectors of transistors Q 14 and Q 15 are connected to the bases of transistors Q ₁₄ and Q ₁₅ of slice circuit δ. Connected to the bases of transistors Q ₁₆ and Q ₁₇ . Furthermore, the emitters of transistors Q ₁₄ and Q ₁₅ are connected to transistors Q ₁₈ and Q ₁₉ of the other phase F (one phase E
This corresponds to the transistors Q ₁₄ and Q ₁₅ . ) and is connected to the collector of transistor Q ₂₀ via a resistor. The emitter of the transistor Q ₂₀ is grounded via a resistor R ₄ , and the base is connected to the output of the generator coil 14 of the frequency generator via a frequency-voltage converter 25 , a low-pass filter 26 , and an inverting circuit 29 . Transistors Q ₁₂ , Q ₁₃ , Q ₁₆ , and Q ₁₇ constitute a bridge circuit, and a coil 2,
A stator coil _LA consisting of 3 is connected. The common emitters of transistors Q ₁₂ and Q ₁₃ are connected via a resistor R ₅ to a current mirror circuit 27,
The common emitters of transistors Q ₂₁ and Q ₂₂ on the input side of 28 are connected to the emitter of transistor Q ₂₀ via a resistor R ₆ . Further, resistors R ₇ and R ₈ of the other phase F corresponding to resistors R ₅ and R ₆ are also connected to the emitter of transistor Q ₂₀ . The base of the transistor Q ₂₀ is connected to a voltage that is inversely proportional to the output frequency of the generator coil 14 of the frequency generator, that is, the rotation speed of the rotor magnet 6 is detected as a frequency by the generator coil 14, and converted into a frequency by the frequency-voltage converter 25. A proportional voltage is applied, harmonic components are removed by a low-pass filter 26, and inverted by an inverting circuit 29, and a voltage inversely proportional to the rotation speed is applied. Further, the resistor _R4 functions as a detection resistor for the current flowing through the stator coils L _A and L _B of each phase, and provides negative feedback of the current value.

Therefore, when the rotational speed increases, the current supplied to the stator coils L _A and L _B tends to be reduced, and the collector current of the transistor Q ₂₀ is reduced. When the collector current of transistor Q ₂₀ decreases, the base currents of transistors Q ₁₆ and Q ₁₇ also decrease. That is, the collector currents of transistors Q ₁₆ and Q ₁₇ are sliced by a certain value depending on the base current. To explain this with reference to the waveforms shown in FIG. 7, the output voltage V _G of the Hall element ₇ shown in FIG.
A sinusoidal current I _A shown in is obtained. Since it is sliced at a certain level by the slicing circuit δ, the maximum value I _B of the current flowing through the stator coil L _A
When sliced, the current I C is sliced at a certain _level as shown by the solid line within the range of the current I _B. Become. Note that in this embodiment, the transistor _Q20 that determines the slice level is common to each phase E and F, so the transistor of one phase E
Q ₁₄ , Q ₁₅ and the other phase F transistor Q ₁₈ ,
Since the sum of the currents flowing through Q ₁₉ is controlled to be constant, when the current is switched in either phase E or F, the waveform of the current flowing through stator coil L _A is shown in Figure 7c and stator coil L _B. A part of the waveform partially protrudes, as shown in the protrusion ε shown in FIG. However, since the current change due to this is small, stator coil L
_A and _LB do not generate mechanical noise that occurs when switching the current direction.

As described above, in the present invention, in the drive device for a non-commutated DC motor, the amplifier is connected between the amplifier that amplifies the output voltage of the Hall element and the output circuit that supplies current to the stator coil at a level corresponding to the speed control signal. Since a slicing circuit is provided to slice the sinusoidal output of the Hall element, a sufficient input current can be passed through the Hall element to obtain a large output voltage.

Therefore, since the output voltage of the Hall element which is sufficiently larger than the offset voltage of the amplifier can be input to the amplifier, the offset voltage can be ignored in the drive device of the present invention.

Therefore, no error due to the offset voltage occurs in the current flowing through the stator coil, so that stable and smooth rotation can be obtained in the commutatorless DC motor.

Furthermore, even when the direction of the current flowing through the stator coil changes, it does not change abruptly but gradually in a sinusoidal manner, so the stator coil does not vibrate and generate noise.

In the embodiment of the present invention, a two-phase 10-pole non-commutator DC motor has been described, but it goes without saying that the number of phases and the number of poles can be freely selected.

[Brief explanation of the drawing]

Figure 1 is a layout diagram showing the positions of the stator coil and Hall element, Figure 2 is a block diagram showing a conventional drive circuit, Figure 3 a is a conventional Hall element output waveform diagram, and b is the offset voltage of the amplifier. Waveform diagram, c
4 is a block diagram showing the drive circuit of the non-commutated DC motor of the present invention, and 5 is an output waveform diagram of the amplifier.
Figure a is a Hall element output waveform diagram of the present invention, b is an output waveform diagram of the amplifier, c is an output waveform diagram of the slice circuit, d is an output waveform diagram of the output circuit, and Fig. 6 is a specific diagram of the drive device of the present invention. A circuit diagram showing an example, FIG. 7a is a Hall element output waveform diagram of a circuit diagram showing a specific example, b is a current waveform diagram proportional to the Hall element output, and c is a current flowing through the stator coil of one phase. Waveform diagram d shows a current waveform diagram flowing through the stator coil of the other phase. 7, 8... Hall element, 17, 21... Amplifier, 18, 19, 22, 23... Slice circuit,
20, 24... Output circuit, L _A , L _B ... Stator coil.

Claims (1)

[Claims] 1 A rotor magnet magnetized with multiple magnetic poles,
a plurality of stator coils arranged correspondingly to the rotor magnet; a magnetically sensitive element that detects the magnetic pole position of the rotor magnet; and an amplifier circuit that amplifies the output of the magnetically sensitive element to obtain a sinusoidal output signal. , a slicing circuit that slices the sinusoidal output of the amplifier circuit at a level according to a speed control signal;
an output circuit that supplies a current to the stator coil according to the output of the slice circuit, and a current that provides an output voltage sufficiently larger than an offset voltage of the amplifier circuit is input to the magnetically sensitive element. A drive device for a non-commutated DC motor.