JPS5910187A - Brushless motor - Google Patents

Abstract

PURPOSE:To smoothly switch the transistor of an output unit in a brushless motor by respectively inputting the outputs of a plurality of Hall elements for detecting the position of the motor to differential circuits, combining the outputs of the differential circuits to botain signal which varies in tertiary values. CONSTITUTION:The outputs of position detecting Hall elements P1-P3 are inputted to differential circuits DF1-DF3 which are connected to the output sides of the collectors of TrQ19-Q21 which form a current mirror circuit for a transistor TrQ22, and detection signals S1-S3 from the collectors of the TrQ1-Q3 are applied to the TrQ7-Q12 of a sorter. For instance, the TrQ1, Q4 are together turned ON in the range of 0 deg.-120 deg. of the rotating angle of the rotor in the operation of the circuit DF1, but the flowed out current from the TrQ19 merely satisfies only one of constant-current source currents I1, I2, insufficient current is accordingly supplied through the TrQ9, Q13 from the power source +B2, thereby turning the TrQ9, Q3 ON. The collector voltage of the TrQ19 becomes relatively high in this range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to brushless motors, and particularly to improvements in drive circuits.

[Technical background of the invention]

BACKGROUND ART Conventionally, so-called brushless motors, which are designed to have no contact points, are known among direct current motors, especially small ones. This brushless electric motor has a plurality of coils arranged along the rotational direction, for example as a stator, and these coils are sequentially excited by detecting the rotational position of the rotor by optical or magnetic means without contact. The rotor is driven to rotate.

Figure 1 is a circuit diagram showing an example of a conventional electric motor of this type.
1 + p21 p3 is used for magnetic detection. And each Hall element PI + "2 + P
3, a driving voltage is applied from a power supply (not shown) to each of them. Three sets of differential circuits DF, , DF2, and DF3 consisting of NPN transistors Ql-Qs have their respective emitters commonly connected, and provide the detection output of the Hall element PI v P2 + p3 between the spaces. There is. And each differential circuit DF, , DF
, , the commonly connected emitters of DF3 are connected to the first . Second
．． It is connected to the reference potential via each third constant current source Il + I2 + I3. In addition, each differential circuit DF'l
, DF2 +DF3, the collectors of the transistors Q+-Q6 are connected to the DC power source 1B1 via resistors R and -R6.

And each differential circuit DF, , DF2. The collectors of transistors Q2, Q4, and Qe of DF3 are respectively allocated to NPN transistors Qt + Qs +
Q9 and PNP transistor Q+o + Q++ +
It is connected to the base connected to common port 1 of Q10. Is this part an NPN transistor Q? , Qs ,
Qe and PNP) Rannostar Q+o +Q++ +
Each pair of Q10's are connected in a complementary symmetrical manner, and their bases and emitters are commonly connected. Each emitter is connected to a reference DC power supply V.

Then, an output section is provided consisting of three complementary pairs of PNP transistors Q1B + Q14 + QI+, , NPN transistors Q1g + Q10 + Q+s.

and each PNP) transistor Q13 + Q10 +
Connect the emitters of Q+s to the DC power supply B2 in common,
Also, each NPN transistor Qtg + Q10 +
The emitters of Qtg are commonly connected to a DC power supply -B2. And the portion to be photographed is each NPN l-transistor Q7 in the section.
The collectors of +Qs and Q9 are connected to the bases of each PNP transistor Q+3 + Q10 + Qls in the output section. Roughly divided into each PNP) transistor Q
The collector of +o + Q++ + Q10 is connected to the base of each NPN transformer Q+a + Q10 + Q+s of the output section. Then, PNP transistors Q+3~qu and NPN h in the output section, and Lannostar Q16~
Connect one end of the stator coil "l + "2 + "3 of the motor to the common connection point of the collector of Q + 8, respectively,
The other end is connected in common.

Then, the rotational position of the rotor (not shown) is determined by the Hall element Pl.
+ P2 r P3 is detected, and this detection output is sent to each differential circuit DF, , DF2 . Amplify with DF3. And these differential circuits DFI, DF2. The output of DF3 is divided by the NPN transistor Q7, Qs +Q.
Any one of 9 that can be given the highest voltage and PN
Any one of the P transistors Q+o + Q++ + Q10 that does not provide the lowest voltage is turned on. And the corresponding PNP transistor Q+3+Q in the output section
10 + Q+1. Any one of the NPN transistors Q16 + Q+y + Qts is turned on. And stator coil “I +”2
+L3 are selectively excited to rotate a rotor (not shown).

[Problems with conventional technology]

However, in such a case, each differential circuit INF,
, DF2. Since the output of lNF3 changes to the output it and 2 fi6 noise, the transistors Q+3 to Q+s in the output section are instantaneously switched from one state of ON and OFF to the other state. For this reason, the transistors Q+s to Qts in the output section needed to have high voltage resistance that could withstand back-extension and force, and there were also problems such as uneven rotation due to variations in the characteristics of the transistors in this transient state. .

[Purpose of the invention]

The present invention was made in view of the above circumstances, and it is possible to change the output of a differential circuit given the output of the Hall element into three values, thereby making it possible to smoothly switch the transistors in the output section. The purpose is to provide a brushless electric motor.

[Summary of the invention]

That is, the present invention is characterized in that the outputs of several Hall elements are input to differential circuits, and the outputs of the respective differential circuits are combined to obtain a signal that changes into three values.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to a circuit diagram shown in FIG. 2, in which the same parts as in FIG. 1 are given the same reference numerals. That is, each differential circuit DFl.

DF2. DF3 transistor Q+ + Q3 + Q
5 collectors respectively PNP) transistor Q19
Connected to the collector of 1Q20+Q21. And this PNP transistor Q19 + Q20 + Q21
A PNP transistor Q22. has a common base and emitter. The commonly connected emitters are connected to the power source B1. Further, the base and collector of the transistor Q22 are commonly connected to a reference potential through constant current sources I, .about.I3, and iI4, which are equal to each other.

In other words, for transistor Q22, transistor Q+
9 + Q20 + Q21 each constitute a current mirror circuit, and a current equal to the current of the constant current source I4 flows through each transistor Q+e + Q20 + Q21.

Here, each of the above Hall elements P] + B2 + Ps is,
The rotor is arranged at equal intervals at an angle of 120° with respect to the rotational axis of the rotor (not shown), and the stator coils are similarly arranged at equal intervals at an angle of 120°. It is pivoted on a rotating shaft. In addition, the transistor Ql of each differential circuit DF, , DF, , DF3
+ Q3 + Detection signal S from the collector of Qs
1. B2. B3 is obtained, and 90 parts of each transistor Q7 are obtained.
~I try to give it to Q+2.

With such a configuration, for example, the differential circuits DF, , DF2 . The bases of the transistors Q+, Qs, and Qs of DF3 are connected to the Hall elements P1+p and lB3's detection signals (shown in (a)).
, (b), (c)) are given.

For example, considering the operation of the differential circuit DFl, both transistors QB and Q4 are turned on when the rotation angle of the rotor is in the range of 0° to 120°.

However, the current flowing out of the transistor Qze only fills one of the constant current sources II+12. Therefore, the shortage of the city's first class transistor is allocated to the transistor Q9.
and power supply element B2 via the transistor Q+s of the output section.
, and turns on each of the transistors Q 9 + Q 13 . Therefore, within this rotation angle range, the collector potential of one transistor Q+o (FIG. 3(d)) becomes relatively high. Further, when the rotation angle is between 120° and 180°, the transistor Q+ is turned on and the transistor Q4 is turned off. Therefore, the output tube of the transistor Q19 passes through the transistor Q1, and no current flows into or out of the transistor Q1. Therefore, the vibration υ is the transistor Q
e + Q Ix and output transistor Q+5+
Q+s is kept OFF. Furthermore, the rotation angle is 180
In the range from ° to 300 °, the transistor Ql + Q
4 are both turned off. Therefore, the output current of the transistor Q19 flows into the source -B2 via the transistor Q12 in the output section and the transistor Qts in the output section, turning on both transistors Q12+Q+6. Therefore, in this rotation angle range, the collector potential of transistor Q+9 is relatively low. and rotation angle 300°~3
At 60°, transistor Ql is turned off and transistor Q4il''j is turned on. Therefore, transistor Q+
The output current of 9 flows through the transistor Q4, and no current flows into or out of the distribution section or the output section.

However, in the range of rotation angles of 3000 to 360 degrees and 120 degrees to 180 degrees, the collector potential of transistor Q+o takes an intermediate value. Note that the transistor Q 26 *Q2
+ collector potential (shown in Figure 3 (e), (f))
similarly changes into three values, and at the intermediate value, the corresponding transistors of the distribution section and the output section are kept OFF. Therefore, each transistor Q13 to Qts in the output section
is inverted from the ON or OFF state to the OFF or ON state, respectively, after a neutral period in which no current flows in or out when a voltage of the above intermediate value is applied. Therefore, the switching operation can be performed smoothly, thereby preventing rotational unevenness due to variations in the characteristics of the transistors.

According to the above embodiment, as is clear from the waveform diagram shown in FIG. 3, the differential circuit DPI + DF2 is applied to the detection signal of the Hall element Pl + P2 + P3.

Detection signal of DF3, i.e. transistor Q+9~Q2
+7 ruqta city pressure has a leading phase of 30°.

Therefore, in the conventional configuration shown in FIG. 1, where the hole kr is located directly above the stator coil, which causes the inconvenience of increasing the thickness of the coil portion, in the above embodiment, the position of the pole element is changed by 30°. There is an advantage that the coil portion can be placed at a position that is delayed.

〔Effect of the invention〕

As described above, according to the present invention, the output of the differential circuit given the output of the magnetoelectric conversion element can be changed into three values,
The force 5 allows smooth switching of the transistor in the output section.

The detection position of the Hall element and the phase of the output signal are set at -30°.
There is an advantage that the Hall element can be placed offset from directly above the coil.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of a conventional brushless motor, Figure 2 is a circuit diagram showing an example of a conventional brushless motor.
The figure is a circuit diagram showing one embodiment of the present invention, and FIG. 3 is a waveform diagram explaining the operation of the above embodiment. DF, ~DF3...differential circuit, p, -p3...Hall element, Q7~Q12...tranzoster (distribution is part)
, Q+3 to Q+s... Transoster (output section), L1
~L3...Stator coil.

Claims (1)

[Claims] The rotational position of the rotor is detected by a plurality of magnetoelectric transducers, and the stator coil is selectively excited by the detection output to drive the rotor. a differential circuit consisting of a pair of transistors to which the detection output of the magnetoelectric conversion element is applied between the bases; a current source connecting one transistor of each differential circuit and the other transistor of the adjacent differential circuit in parallel; and an output section that excites the stator coil under selective switching control based on the output of each differential circuit.