JPH0347439Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a DC brushless motor, and is capable of producing four The present invention relates to a DC brushless motor that can control the amplitude of current flowing through two stator windings, has a small number of parts, and can be easily constructed.

(Prior Art) FIGS. 2A and 2B respectively show a schematic front view of a general DC brushless motor and a positional relationship diagram between a stator coil and a Hall element. In the figure, a rotor 1 has eight poles magnetized on the bottom surface of a permanent magnet, and its shaft 2 is supported by a bearing 3. Stator coil L ₁ ~ L ₄
Coil L ₁ and coil L ₂ (coil L ₃ and coil L ₄ ) are provided on the top facing the magnetized surface of rotor 1.
For example, the phase difference is 3π/2 radians in electrical angle,
For example, the coil L ₂ and the coil L ₃ (the coil L ₄ and the coil L ₁ ) have a phase difference of 5π/2 radians in electrical angle. The Hall elements HG ₁ and HG ₂ are attached to the substrate 4 with a phase difference of, for example, π/2 radians in electrical angle. Note that the Hall element HG ₁ and the coil L ₄ have a phase difference of π radian in electrical angle.

FIG. 4 shows a circuit diagram of an example of a conventional drive circuit for a DC brushless motor having the configuration shown in FIGS. 2A and 2B. In the figure, when a current is passed through the current terminals of Hall elements HG ₁ and HG ₂ , as the rotor rotates, the output voltage e as shown in Figure 3 A' and B is generated from the voltage terminals, . ₁ ′, e ₃ ′, e ₂ , e ₄
is taken out, and the transistors Q ₅ ′ to Q ₈ have a voltage e ₁ ′,
It is conductive during the low level periods of e ₂ , e ₃ ', and e ₄ . Conduction of transistors Q ₅ ′ to Q ₈ causes transistors Q ₁ ′ to
Q ₄ is conductive and stator coils L ₁ to _{L 4} are connected to C in the same figure.
Coil currents i ₁ ′ to _{i 4} ′ as shown in ~F flow sequentially in a time-division manner with a phase difference of 90 degrees in electrical angle to rotate the rotor in one direction.

At this time, the coil currents i ₁ ' to i ₄ '
The amplitude of is controlled and the speed is controlled. That is, for example, transistor Q ₁ ' is turned on and current flows through coil L ₁ .
While i ₁ ' is flowing, the amplitude of current i ₁ ' is detected by resistor R ₁ , and the emitter currents of transistors Q ₁₁ and Q ₉ are determined by this detection voltage V ₁₁ and speed error signal voltage V _s . The controlled current i ₁ ' flowing through the coil L ₁ changes in response to the speed error signal. The currents i _{1 ′} , i ₃ ′ flowing through the coils L 1 , L ₃ are the transistors Q ₁₁ , Q ₉ ,
Currents i ₂ ′ and _{i 4} ′ flowing through coils _{L 2 and L 4 are} controlled by _transistor Q ₁₂ , _Q10 , _Q6 ,
Control is performed in the same way as in the above case using a negative feedback amplifier circuit consisting of Q ₈ , Q ₂ , Q ₄ , and resistor R ₂ .

(Problem to be solved by the invention) By the way, in this conventional circuit, the coil current i ₁ ′ ~
As a circuit for controlling i ₄ ', two systems are required: a negative feedback amplifier circuit corresponding to coils L ₁ and L ₃ and a negative feedback amplifier circuit corresponding to coils L ₂ and L ₄ as described above. In particular, the resistor R ₁ and the resistor
The resistance values of R ₂ and the base-emitter voltages of transistors Q ₁₁ and Q ₁₂ must be precisely matched. However,
In general, the characteristics of resistors, transistors, etc. tend to become ununiform due to changes in ambient temperature, aging, etc., and this is especially noticeable for resistors R ₁ and R ₂ through which large currents flow, resulting in torque ripple and It had the drawback of easily causing uneven rotation.

In addition, this conventional circuit requires two systems of the negative feedback amplifier circuits, and therefore has the disadvantage that the circuit is complicated and cannot be constructed at low cost.

(Means for Solving the Problems) In order to solve the above problems, the present invention detects a rotor including a permanent magnet and the rotational position of this rotor, and the output signal is approximately π(n+( The first and second Hall elements have a phase difference of 1/2)) radian (n is zero or an integer) and are electrically angular to each other by π.
First, second, third, and fourth phase stator windings arranged at a distance of (n+(1/2)) radians (n is zero or an integer) and having one end of each connected in common;
a first transistor whose collector and emitter are connected between the other end of the first phase stator winding and one end of the power supply; and the other end of the second phase stator winding and the power supply. a second transistor whose collector and emitter are connected between the other end of the transistor and the second transistor whose collector and emitter are connected between the other end of the third phase stator winding and one end of the power supply; a fourth transistor whose collector and emitter are connected between the other end of the stator winding of the fourth phase and the other end of the power supply; and the first hole said first according to the output signal of the element.
and a first transistor for controlling the collector-emitter of the third transistor into a saturated state and a cutoff state, respectively.
and a third circuit means, a first control means for controlling the saturation states of the first and third transistors according to a speed error signal based on a rotational error of the rotor, and an output of the second Hall element. second and fourth circuit means for respectively controlling the collector-emitter of the second and fourth transistors into a conductive state and a cut-off state according to a signal; and stator windings of the first to fourth phases. means for detecting a signal based on the total current flowing through the transistor, and impedance between the collector and emitter of the second and fourth transistors in the conductive state according to the signal based on the total current and the speed error signal; A direct current brushless electric motor is provided, characterized in that it is equipped with a second control means for controlling.

(Example) An example will be described with reference to FIG. 1 and the following figures.

FIG. 1 shows a circuit diagram of an embodiment of a DC brushless motor according to the present invention. In the figure, Hall elements HG ₁ ,
The mounting positions of HG ₂ and stator coils L ₁ to _{L 4} are as shown in FIGS. 2A and 2B. Coil L ₁
One end of the coil L ₂ , one end of the coil L ₃ , and one end of the coil L ₄ are respectively commonly connected to each other, the other end of the coil L ₁ is connected to the collector of the transistor Q 1, and the other end of the coil L ₂ is connected to the collector of the transistor Q ₁ . is connected to the collector of transistor _Q2 , the other end of coil _L3 is connected to the collector of transistor _Q3 , and the other end of coil _L4 is connected to the collector of transistor _Q4 . transistor
The base of Q ₁ is connected to the voltage terminal of Hall element HG ₁ through transistor Q ₅ , the base of transistor Q ₃ is connected to the voltage terminal of Hall element HG ₁ through transistor Q ₇ , and the base of transistor Q ₂ is connected to transistor Q ₆ through the voltage terminal of the Hall element HG ₂ , the base of the transistor Q ₄ is the transistor
They are respectively connected to the voltage terminals of Hall element HG ₂ via Q ₈ .

The emitters of the transistors Q ₁ and Q ₃ are connected to the positive terminal V ₁ of the power supply, and the emitters of the transistors Q ₅ and Q ₇ are connected in common and connected to the speed error signal input terminal 1 via the transistor Q ₂₀ . A transistor Q ₂₀ is connected to the negative terminal V ₂ of the power supply via a resistor R ₂₀ . The emitters of transistors Q ₆ and Q ₈ are connected in common to resistor R ₂₁ and transistor
Q ₂₁ is connected to the positive terminal V ₁ of the power supply through a resistor R ₂₂ , and the emitters of transistors Q ₂ and Q ₄ are connected to the negative terminal V ₂ of the power supply through a resistor R ₀ . R ₂₄ is connected to terminal 1 and the base of transistor Q ₂₁ via transistor Q ₂₂ , and further connected to the positive terminal V ₁ of the power supply via resistor R ₂₃ .

In the figure, when current is supplied to the current terminals of Hall elements HG ₁ and HG ₂ and the rotor is rotated,
Voltage terminal of Hall element HG ₁ , from Figure 3 A
From the voltages e ₁ and e ₃ shown in , and the voltage terminals of the Hall element HG ₂ , voltages e ₂ and e ₄ shown in FIG. Positive voltage period of voltage e ₁ (period of e ₁ > e ₃ , electrical angle π) Transistor Q ₅ , positive voltage period of voltage e ₃ (period of e ₃ > e ₁ ) Transistor Q ₇ , negative voltage of voltage e ₂ Period (period with e ₂ < e ₄ , electrical angle π) transistor
During the negative voltage period of the voltage _{e 4 (} e ₄ <e ₂ ), the transistor Q ₈ is turned on, and is turned off during the other periods. As a result, the transistors Q ₁ and Q ₃ are in a saturated state during the high level period of the voltages e ₁ and e ₃ and are in the cutoff state during the low level period, and the transistors Q ₂ and
Q ₄ is conductive during the low level period of output voltages e ₂ and e ₄ ,
The high level period is considered to be a cut-off state.

For example, 0 to π/2 as shown in FIG. 3 C to F.
During the period, transistors Q ₁ and Q ₄ are on and transistors Q ₂ and Q ₃ are off, so
The current from the positive terminal V ₁ of the power supply flows through the transistor Q ₁ ,
The current flows through the coils L ₁ and L ₄ , the transistor Q ₄ , and the resistor R ₀ to the negative terminal V ₂ of the power supply. That is, a current i ₁ flows through the coil L ₁ and a current I ₄ flows through the coil L ₄ . Next, π/
During the period from 2 to π, transistors Q ₁ and Q ₂ are on and transistors Q ₃ and Q ₄ are off, so the current from the positive terminal V ₁ of the power supply flows through transistor Q ₁ and coils L ₁ and L _2. , transistor Q ₂ , resistor
It flows through R ₀ to the negative terminal V ₂ of the power supply. That is, a current i ₁ flows through the coil L ₁ and a current i ₂ flows through the coil L ₂ . In other periods, the same operation is carried out, and the currents i ₁ to i ₄ as shown in C to F in the same figure are applied to each coil L ₁ to _{L 4} .
flows.

At this time, the saturation state and cutoff state, ie, switching, of the transistors Q ₁ and Q ₃ are performed by controlling the base currents of the transistors Q ₁ and Q ₃ by the transistors Q ₅ and Q ₇ , respectively.

Therefore, the base currents of transistors Q ₁ and Q ₃ need to be sufficiently large to bring them into saturation, but if they are too large, the transistors
The base current of Q ₁ and Q ₃ causes power loss in the power supply,
In addition, for example, the period during which current flows in the transistors Q ₁ and Q ₂ (flow angle) becomes larger than π radian in electrical angle, resulting in a decrease in torque and power loss. This is because the period (angle) during which any one of the coils L ₁ to L ₄ generates torque is in the range of π radians in terms of electrical angle, depending on the relative position of the coil and the rotor.

The base currents of transistors Q ₁ and Q ₃ are controlled to appropriate values. Therefore, _the currents of transistors Q ₁ and Q ₃ are connected to _the terminal 1
The collectors of transistors Q ₁ and Q ₃ are supplied with an incoming speed error signal V _s and whose conduction state is controlled by transistor Q ₂₀ .
Controls the amplitude of the emitter current.

On the other hand, transistors Q ₂ and Q ₄ are repeatedly turned on and off by transistors Q ₆ and Q ₈ which are controlled according to the output of voltages e ₂ and e ₄ , and their emitter currents are input to terminal 1. This is controlled by a transistor _Q22 whose conduction state is controlled by being supplied with the upcoming speed error signal _Vs. Transistor Q ₂₂ has a speed error signal applied to its base and a voltage corresponding to the amplitude of coil currents i ₁ to i ₄ applied to its emitter via resistor R ₂₄ , so that the amplitude of coil currents i ₁ to i ₄ depends on the speed error signal V _s and the current values of the coils L ₁ to _{L 4} .

In this case, the current values of the coil currents i ₁ to _{i 4} are controlled in accordance with the speed error signal, with almost no relation to the value of the DC current amplification factor h _fe of the transistors Q ₂ and Q ₄ .
As a result, there is less torque unevenness due to variations in current in each phase, and rotational unevenness is also reduced.

As mentioned above, as long as an appropriate base current is given, transistors Q ₁ and Q ₃ operate in a saturated state cut off except when switching the current, so their collector loss is greater than the collector loss of transistors Q ₂ and Q ₄ . It is possible to use small and relatively compact transistors.

By the way, the circuit that controls the coil currents i ₁ to _{i 4} includes transistors Q ₂₂ , Q ₂₁ , Q ₆ , Q ₈ ,
This is a negative feedback amplifier circuit composed of Q ₂ , Q ₄ , resistor R _{0 ,} etc., and is common to coils L ₁ , L ₃ and coils L ₂ , L ₄ . Therefore, unlike the conventional circuit that requires two systems of negative feedback amplifier circuits shown in Figure 2, it is not necessary that the characteristics of the resistors, transistors, etc. in each system be precisely matched, and the circuit is simple and inexpensive. Can be configured.

Note that in FIG. 4, the transistors Q ₂ and Q ₄ may be operated repeatedly in a saturated state and a cutoff state, and the emitter currents of the transistors Q ₁ and Q ₃ may be controlled by a speed error signal.

(Effect of the invention) As mentioned above, the DC brushless motor according to the invention has two stator windings connected in series to control the current.
Furthermore, since there is only one current control system based on the speed error signal instead of two systems as in the conventional system, the circuit configuration is simple, and there are advantages in that there is less adverse effect due to variations in element characteristics and less torque unevenness.

In addition to the above, two of the first to fourth transistors
The transistors can be used with relatively small allowable collector loss, and are therefore inexpensive.

Furthermore, during rotational operation, the 4-phase stator winding (coil)
Conventionally, two are connected in parallel to the power supply, but in this invention, two are connected in parallel to the power supply.
are connected in series, so in order to equalize the load on the power source of the conventional motor and the present invention, it is necessary to assume that the wire area factor (the ratio of the wire cross-sectional area of the coil per unit) of the coil is approximately equal. , the resistance value of one coil of the motor of the present invention is 1/4 times that of the conventional one,
The number of turns is 1/2 and the wire diameter is √2.

Here, since the back electromotive force generated in each coil is proportional to the number of turns, the back electromotive force generated in one coil of the motor of the present invention is 1/2 that of the conventional motor.
In this invention, two coils are connected in series,
Since they have a phase difference of π (n + (1/2)) radians in electrical angle, the back electromotive force is smaller than conventional ones, so the current supplied to the coil can be increased even during high-speed rotation, resulting in large torque. It has the following characteristics.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the DC brushless motor of the present invention, Figs. 2A and B are a schematic front view and a diagram of the positional relationship between the stator coil and the Hall element of a general DC brushless motor, and Fig. 3 Figures A to F are signal waveform diagrams for explaining the operation of the conventional and present DC brushless motors,
FIG. 4 is a circuit diagram of a conventional electric motor. 1...Speed error signal input terminal, HG ₁ , HG ₂ ...
...first and second Hall elements, L ₁ to _{L 4} ...first to
4th phase stator winding (coil), Q ₁ to Q ₄ ... 1st
~Fourth transistor, _Q5 ~ _Q8 ,...first to fourth circuit means (transistor), _Q20 , _Q22 ...first and second control means (transistor), _R0 , _R20
~ _R23 ...Resistance, _V1 , _V2 ...Power supply terminals, _Vs ...
...Speed error signal.

Claims (1)

[Claims for Utility Model Registration] A rotor including a permanent magnet, the rotational position of this rotor is detected, and the output signal is approximately π (n + (1/2)) radians in electrical angle (n is zero or an integer). ) are arranged at a distance of π (n + (1/2)) radians (n is zero or an integer) from each other in electrical angle, and one end of each is connected to a common connection. 1st, 2nd, 3rd, 4th
a stator winding of the first phase; a first transistor whose collector and emitter are connected between the other end of the stator winding of the first phase and one end of the power supply; and the stator of the second phase. a second transistor whose collector and emitter are connected between the other end of the winding and the other end of the power source; and between the other end of the third phase stator winding and one end of the power source. a third transistor, the collector and emitter of which are connected between the other end of the stator winding of the fourth phase and the other end of the power source; a transistor; first and third circuit means for respectively controlling collector-emitter regions of the first and third transistors into a saturated state and a cutoff state according to an output signal of the first Hall element; a first control means for controlling saturation states of the first and third transistors according to a speed error signal based on a rotational error of the rotor; second and fourth circuit means for controlling the collector-emitter of the transistor No. 4 into a conductive state and a cut-off state, respectively; and a signal based on the total current flowing through the stator windings of the first to fourth phases. a second control means for controlling the impedance between the collectors and emitters of the second and fourth transistors in the conductive state according to the signal based on the total current and the speed error signal; A DC brushless motor characterized by being equipped with.