JPS62221894A - Brushless motor - Google Patents

Abstract

PURPOSE:To make phase switching of each current smooth, by distributing torque command signals at the output ratio of a plurality of the rotary position signals of a permanent magnet rotor, amplifying the signals, and conducting stator windings. CONSTITUTION:A rotary-position-signal operating circuit 9 outputs multiphases of the rotary position signals of a permanent magnet rotor 1. Said rotary position signal is inputted in a distributing circuit 22. In the distributing circuit 22, the torque command signals of a motor are distributed at the output ratio of the rotary-position-signal operating circuit 9. A stator-winding driving circuit 6 sequentially supplies the currents in accordance with the outputs of the distributing circuit 22 to a plurality of stator windings 2a-2c.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a brushless electric motor.

BACKGROUND OF THE INVENTION In recent years, brushless motors that are configured to sequentially switch the energized phase of a stator winding using a semiconductor (for example, a transistor) according to the output of a rotor position detector (for example, a Hall element) have been used in audio and video equipment. It is applied. However, rotor position detectors are not inexpensive and often have structural limitations because they must be installed inside the motor. Therefore, brushless motors that do not use such a rotor position detector at all have been actively proposed.

Japanese Unexamined Patent Publication No. 55-160993 (hereinafter abbreviated as Document 1) discloses a brushless motor technology that does not use any position detector such as a Hall element.

Hereinafter, a conventional example thereof will be explained using the drawings.

FIG. 3 is a block diagram representing the concept of the conventional example described above.

In FIG. 3, 1 is a permanent magnet rotor 2a.

2b and 2c are stator windings. 9 is a position signal calculation circuit, and 3a, 3b, 3c are stator windings 2a, 3c, respectively.
2b, 2c is a rectifier circuit for extracting the non-energized region of the back electromotive force (particularly the part above +cc in this case), and 4a, 4b.

4C is a discharge type voltage-current conversion circuit that converts the half-wave rectified waveform of the back electromotive force obtained by the rectifier circuits 3a, 3b, and 3c into current, and 5a, 5b, and 5c are the rectifier circuits 3a, respectively.
, 3b, 3c, an attraction type voltage-current conversion circuit that converts the half-wave rectified waveform of the back electromotive force obtained in 3c into a current, lla, llb
, llc are voltage-current conversion circuits 4b and 50.4C, respectively.
and 5a, and is a time-integrating capacitor charged and discharged by 4a and 5b. 12 is a bias power supply that provides an appropriate DC voltage. Reference numeral 16 designates a differential comparator circuit for sequentially switching the driving current of the stator winding in accordance with the trust signal appearing in the form of voltage in the capacitor, and here, it is made up of three differential transistors 17a, 17b, and 17c with a common emitter. It is configured. 18 is a stator winding drive current command circuit, 6 is a stator winding drive circuit, and current amplification transistors 7a, 7
b.

7C and stator winding drive transistors 8a and 8b.

It is composed of 8C. Current amplification transistor 1a
, 7b, 7c are provided with three differential transistors 17a constituting the differential comparison circuit 16.

The collector outputs of 17b and 17C are connected to the collectors of stator winding drive transistors 8a, 8b, and 8c.
Fixed pre-winding windings L'R2a, 2b, and 2c are connected to each other. The differential comparison circuit 16 includes three differential transistors 17a
, 17b, and 17c, and select the largest human input signal.When the base input of transistor 17a is large, stator winding 2a is energized through transistor 8a, and transistor 17b is energized. When the base input is large, the stator winding 2b is energized through the transistor 8b, and when the base input of the transistor 17c is large, the stator winding 2C is energized through the transistor 8C.

FIG. 4 is a signal waveform diagram for explaining the operation of the conventional example shown in FIG.

14a, 14b, and 14c in FIG. 4 show the temporal transition of the voltage waveforms of the stator windings 2a, 2b, and 2c, respectively, and the portions above +vcc are caused by the rotation of the permanent magnet rotor. In the generated back electromotive force waveform, in the portion below +VC6, in addition to the back electromotive force waveform, there is a voltage drop due to the winding drive current and winding resistance (only the waveform 14a is particularly shaded).

Part 4) is the voltage waveform of the time integrating capacitor lla, and serves as a position signal for driving the fixed prewinding wA2a. The position signal shown in FIG. 4 (bl) is the position signal calculation circuit 9
can be obtained as follows. In FIG. 3, the back electromotive force waveform 14b of the stator winding 2b is half-wave rectified by the rectifier circuit 3b to +V. The waveform of the C-leat portion is taken out, and converted into a current by the voltage-current conversion circuit 4b to charge the time-integrating capacitor lla. Furthermore, stator winding 2C
The back electromotive force waveform 14c is half-wave rectified by the rectifier circuit 3C, and the waveform above +■cc is extracted, and this is converted into a current by the voltage-current converter B5C, and the time-integrating capacitor lla
discharge. Then, as described above, the voltage waveform shown in FIG. 4 1dl is obtained, which becomes a position signal for driving the stator winding 2a. Similarly, Fig. 4(C) shows the time integrating capacitor ll.
The voltage waveform of b is the position signal for driving the stator winding 2b, and 1dl in FIG. 4 is the voltage waveform of the time integrating capacitor l.
It is a voltage waveform of lc and serves as a position signal for driving fixed prewinding and v12C. Figure 4 1dl is the same figure (bl,
(C1, (In response to the position signal shown in dl, the stator winding 2a
, 2b.

This shows the current waveform flowing through 2C, and 15a in the figure
, 15b, 15c are stators S&?, respectively. 12a,
2b and 2c are shown.

Problems to be Solved by the Invention However, according to the configuration of the brushless motor shown in Document 1, the obtained rotor position signal has a mountain-shaped waveform, which is transmitted by a group of differential transistors having a common emitter. If differential switching is performed by differentially switching the stator winding drive current, the stator winding drive current can be switched extremely stably, but the drive current flowing through the stator winding has a rectangular waveform with a conduction width of approximately 120° (electrical angle).

Therefore, a filter including a relatively large capacitor is required at the current-carrying terminal of the stator winding in order to reduce the voltage spikes caused by switching. Furthermore, since the current flowing through the stator windings is abruptly turned on and off, it has the disadvantage of easily generating vibration and noise, and this tendency becomes more pronounced as the motor is used at higher speeds.

In view of the above-mentioned problems, the present invention is a brushless motor that does not use any position detector such as a Hall element, and has a filter circuit including a large capacitor as required for the brushless motor shown in Document 1. The purpose of the present invention is to provide a brushless electric motor that does not require brushing and has low vibration and low noise even during high-speed rotation.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a rotational position signal calculation circuit that outputs rotational position signals of multiple phases of a permanent magnet rotor, and a rotational position signal calculation circuit that outputs a rotational position signal of a plurality of phases of a permanent magnet rotor, and a rotational position signal calculation circuit that outputs a torque command signal of an electric motor. It is composed of a distribution circuit that distributes the output ratio of the arithmetic circuit, and a stator winding drive circuit that sequentially supplies a plurality of stator windings with a current according to the output of the distribution circuit.

Function: According to the present invention, each current applied to the plurality of stator windings is distributed according to the output ratio of the rotational position signal using the above-described configuration.

As a result, the phase switching of each current flowing through the plurality of stator windings is performed extremely smoothly, which makes it possible to reduce the spike-like voltage caused by phase switching as seen in conventional examples. There is no need to connect a filter circuit containing a large capacitor to the current-carrying terminals of the stator winding.

Further, the current flowing through the stator winding is not turned on and off abruptly as in the conventional example, and phase switching is performed smoothly, so that the motor can be driven with very little vibration and noise.

Embodiment FIG. 1 is a block diagram showing an embodiment of the brushless electric motor of the present invention. This will be explained below with reference to the drawings.

In FIG. 1, reference numeral 9 denotes a rotational position signal calculation circuit which calculates a rotational position signal of the permanent magnet rotor 1 and outputs a three-phase position signal. Components having the same functions as those in FIG. 3 are given the same numbers and redundant explanations will be omitted.

20a, 20b, and 20c are integration prohibition command circuits. The integration prohibition command circuit 20a prohibits the operation of the discharge type voltage-current conversion circuit 4a according to the output of the rectifier circuit 3a. In the embodiment shown in FIG. 1, a switch 26 is connected in series to the output of the discharge type voltage-current conversion circuit 4a.
a is turned on and off by the output of the integration prohibition command circuit 20a.

Similarly, the integration prohibition command circuits 20b and 20c inhibit the operation of the discharge type voltage-current conversion circuits 4b and 4c according to the outputs of the rectifier circuits 3b and 3c, respectively. The switches 26b and 26c connected in series to the outputs of the integration prohibition command circuits 20b and 2
It is configured to turn on and off with an output of 0c. 27a.

Clamp diodes 27b and 27C are connected in parallel to the time-integrating capacitors lla, llb, and Ilc to prevent the time-integrating capacitors from being over-discharged.

22 is a distribution circuit that distributes the output of the stator winding drive current command circuit 18 of the motor into the output ratio of the three-phase position signals obtained by the position signal calculation circuit 9. In the embodiment shown in FIG. 1, the distribution circuit 22 includes voltage-current conversion circuits 21a, 21b, and 21c for converting position signals obtained as voltage values to time-integrating capacitors lla, llb, and llc into currents, and voltage-current conversion circuits 21a, 21b, and 21c. Diodes 24a, 24b, 24c connected in series to the respective outputs of circuits 21a, 2lb, 21c and emitters are commonly connected, and each base is connected to diode 2.
4a.

Transistor 2 connected to the anodes of 24b and 24c
3a, 23b, 23c, and a bias power supply 25 that provides an appropriate DC voltage. Stator winding 2a according to each output of distribution circuit 22.

Drive currents are supplied to 2b and 2c, respectively.

FIG. 2 is a signal waveform diagram for explaining the operation of the brushless motor of the present invention.

28a, 28b, and 28c in FIG. By doing so, the stator windings 2a, 2
b, the back electromotive force induced in 2c, the part below +Vo is the voltage drop due to the winding drive current and winding resistance in addition to the back electromotive force (only the waveform of 28a is particularly shaded) can be seen.

FIG. 2 fb), (cl, (dl) indicate the outputs of the charging prohibition command circuits 20a, 20b, and 20c, respectively, and the voltage waveforms 28a of the stator windings 2a, 2b, and 2c.

28b and 28c each output an H level at a portion above +VCC.

Charging prohibition command circuit 20 a, 20 b, 20
When the output of c is at H level, the switch 2 connected in series to each output of the discharge type voltage-current conversion circuits 4a, 4b, and 4c
6a, 26b, and 26c are in an open state.

! 21Hel, tf), (gl indicates the voltage waveforms obtained at the time integration capacitors lla, llb, and Ilc, respectively. This is the calculation output of the rotational position signal calculation circuit 22, and becomes a three-phase rotational position signal. The rotational position signal shown in FIG. 2+el is obtained by the rotational position signal calculation circuit 22 as follows. In FIG. The waveform above 10V.C is extracted and converted into a current by the voltage-current conversion circuit 4b, and the switch 2
6b to charge the time integration capacitor lla. However, the switch 26b causes the back electromotive force waveform 28a of the stator winding 2a to change to +Vc due to the output of the charging prohibition command circuit 20b.
The part above +VCC is open, and charging to the time-integrating capacitor tta is prohibited, and the back electromotive force waveform 28a of the stator winding 2a becomes conductive in the part below +VCC, and the time-integrating capacitor lla is in a conductive state. Start charging. Therefore, the voltage across the time-integrating capacitor lla starts to increase from the time when the back electromotive force waveform 28a of the identifier winding 2a becomes below +CC. Furthermore, the back electromotive force waveform 28C of the stator winding 2C is half-wave rectified by the rectifier circuit 3C and +V0
Extract the waveform above ゜ and convert it to the voltage-current conversion circuit 5.
C is converted into a current to discharge the time integration capacitor lla. Therefore, until the magnitude of the back electromotive force waveforms 2b and 20 become equal, the charging current to the time integrating capacitor lla is larger than the discharging current, so the voltage across the time integrating capacitor lla increases, and the back electromotive force waveform 2b and 2
0 become equal, the discharge current to the time-integrating capacitor lla becomes larger than the charging ft'1ffl, so the voltage across the time-integrating capacitor lla continues to decrease, and finally the voltage across the time-integrating capacitor lla continues to decrease. The clamping diodes connected in parallel are turned on and fixed at the diode on-voltage -vD. As a result, a voltage waveform shown in FIG. 2 fbl is obtained, which becomes a position signal for driving the stator winding 2a. Similarly, FIG. 2 [fl is the voltage waveform of the time-integrating capacitor llb, which is a rotational position signal for driving the stator winding 2b, and FIG. 2 +gl is the voltage waveform of the time-integrating capacitor 1) c. This becomes a rotational position signal for driving the stator winding 2C.

Figure 2 (hl shows the drive current waveforms flowing through the stator windings 2a, 2b, 2c in response to the rotational position signals shown in Figures 2(e), (f), and (g)); Middle school 29a.

29b and 29C are stator windings 2a and 2b, respectively.

The waveform of the drive current flowing through 2C is shown.

The drive current waveform shown in FIG. 2 (hl) is obtained by the distribution circuit 22 and the stator winding drive circuit 6 in the following manner.

In FIG. 1, three-phase rotational position signals (time integration capacitor 1) obtained by rotational position signal calculation circuit 9 a,
1 l b, 1) voltage waveform of c) as “pale”
If pb and epo are used, the three-phase rotational position signal ep a +
ep b + ep c are three-phase rotational position signals e by voltage-current conversion circuits 21a, 21b, and 21c, respectively.
'pa, 'p proportional to the size of pa, epb, epo
b, 'pc, and diodes 24a, 2, respectively.
Electricity is applied to the anode sides of 4b and 24c. diode 2
Transistors 23 a, 23 b, whose bases are connected to the anode terminals of 4 a, 24 b, and 24 c, respectively;
Assuming that the current amplification factor of 23c is sufficiently large and the base current can be ignored, the voltage-current conversion circuits 21a and 2
1b.

Currents 'pa and 'pH+'pc outputted from 21c are diodes 24a and 24b, respectively.

24c, and the voltage across the diode is ■3°V,,V
o occurs. Voltage V8. V,, Vo and current 'pa+
The following relationship holds between 'pb+'pc.

However, I5j reverse cutoff current: Borckmann's constant 1゛: absolute temperature Therefore, if the voltage of the DC bias power supply 25 is Eo, the transistors 23a and 23b.

Voltage ■Ba applied to the base of 23c, ■8. .

■BC is vBa-■, 10E, respectively.・・・・・・(4
)V8. =V, +Eo −・・−(51
"5c=v. 10E. (6
).

If the collector currents of the transistors 23a, 23b, and 23c are IB, and the common emitter potential of the transistors 23a, 23b, and 23c is V and 3, respectively, then in FIG.
During the period A (see FIG. 2 (hl)) in which the drive current supplied to the stator winding 2a is smoothly switched to the stator winding 2a, the following relationship holds true.

However, ■5': Reverse direction cut-off current Therefore, +41. +61. +71. ia and i from +81 formula. The ratio of is found to be iCkT.

In addition, fil, (The ratio of 'pa and 'pc is calculated from equation 31.

Therefore, from the formula (91, +30) 'c'pc The relationship holds true.

That is, if the command current of the drive current command circuit 18 is 10, then in period A, the current arc, io, is the command current I. The rotation position signal. Pa. It is a value distributed according to the ratio of pc. Note that during period A, the transistor 23b is in an off state and i B −
It is 0.

Next, in period B shown in FIG. 2 (hl), the output current 'pc to the voltage-current conversion circuit 2 also becomes zero, and the voltage-current conversion circuit 2
Since only the output current 'pa of the transistor 1a exists, only the transistor 23a among the transistors 23a, 23b, and 23c is turned on, and its collector current i is the command current I of the drive current command circuit 18. is equal to

Similarly, the transistors 23a and 23b.

The respective collector currents ia, ib of 23G.

ic is the command current I of the drive current command circuit 18. are the rotational position signals epa, e obtained by the rotational position signal calculation circuit 9.
It is distributed in the output ratio of pb l epC.

Furthermore, the relationship ta, i, 1o=Io (b) always holds true.

The three-phase output t8. of the distribution circuit 22 obtained by the method described above. 'b+ ICs are respectively input to the fixed prewinding drive circuit 6, and current amplification transistors 7a, 7b, 7
c and stator winding drive transistors 8a, 8b, and 8c, respectively, to linearly amplify the three-phase stator windings 2a, 2.
A drive current is supplied to b and 2c. As a result, Figure 2 (
Trapezoidal stator winding drive current 29 as shown in hl
a.

29b and 29c are respective stator windings 2a.

2b and 2c.

Effects of the Invention As described above, the present invention distributes the torque command signal of the electric motor so that it becomes the output ratio of the rotational position signals of multiple phases of the permanent magnet rotor, linearly amplifies it, and fixes the multiple phases. By energizing the child winding, phase switching of each current flowing to the stator winding is performed extremely smoothly.
An object of the present invention is to provide a brushless electric motor that generates extremely little vibration and noise during driving.

Furthermore, in the present invention, since the rotational position signal of the permanent magnet rotor is obtained by processing the back electromotive force generated in each of the stator windings of multiple phases in a position signal calculation circuit, rotor position signals such as Hall elements are obtained. There is no need to provide a detector inside the motor, and the motor itself can be constructed at low cost and in a small size.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a brushless motor according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation of the brushless motor of the present invention, and FIGS. 3 and 4 are conventional brushless motors. FIG. 2 is a circuit configuration diagram and a signal waveform diagram of a brush motor. 1...Permanent magnet rotor, 'la, 2b, 2
C... Stator winding, 6... Winding drive circuit, 9... Position signal calculation circuit, 22...
- Distribution circuit, 18... Drive current command circuit.

Claims (5)

[Claims] (1) A plurality of stator windings, a rotational position signal calculation circuit that outputs rotational position signals of multiple phases of the permanent magnet rotor, a command signal generation circuit that generates a torque command signal for the electric motor, and the torque command signal and a stator winding drive circuit that supplies a drive current to a plurality of stator windings according to the output of the distribution circuit, A brushless electric motor characterized in that the drive currents applied to the child windings are distributed to the output ratio of the rotational position signal. (2) The position signal calculation circuit is a calculation circuit that individually extracts all or a part of the non-energized area of the back electromotive force generated in each of the plurality of stator windings and temporally adds and integrates and subtracts and integrates them. A brushless electric motor according to claim (1), comprising: (3) The position signal calculation circuit individually extracts all or part of the non-energized region of the back electromotive force generated in each of the plurality of stator windings, and prohibits addition and integration in response to this. A brushless electric motor according to claim (2), comprising: (4) The position signal calculation circuit includes a rectifier circuit that individually extracts all or a part of the non-energized region of the back electromotive force generated in each of the plurality of stator windings, and converts the output of the rectifier circuit into a current. A discharge-type voltage-current conversion circuit converts the output of the rectifier circuit into a current, a suction-type voltage-current conversion circuit converts the output of the rectifier circuit into a current, and the discharge-type voltage-current conversion circuit and the suction-type voltage-current conversion circuit charge and discharge the battery. A brushless electric motor according to claim 1, comprising a time integrating capacitor. (5) The distribution circuit includes a voltage-current conversion circuit that converts rotational position signals of multiple phases into currents, and a plurality of diodes in which the outputs of the voltage-current conversion circuit are respectively connected to anode terminals and the cathode terminals are commonly connected. The brushless motor according to claim 1, wherein the brushless motor is constituted by a plurality of transistors, each of which has anode terminals connected to its base and whose emitters are commonly connected.