JPS61285093A - Brushless motor - Google Patents

Abstract

PURPOSE:To dispose a plurality of position detectors at the center between phase approaching drive coils or of drive coil by combining the outputs of position detectors, and shifting the phases to obtain an output signal to the drive coils of the phases. CONSTITUTION:Position detectors A, B are disposed at the centers between phase approaching drive coils LA and LB of 3-phase drive coils LA-LC for rotatably energizing a rotor magnet and between the approaching drive coils LB and LC. The outputs of the detectors A, B are combined by phase shifters of amplifiers 15-17 and adders 18-20, the phase is shifted at 30 deg. of an electric angle, and then supplied through coil drive amplifiers 21-23 to drive coils LA-LC.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a system in which a position detector for detecting the position of a rotor magnet can be placed at the center between adjacent three-phase drive coils or at the center of a drive coil. Regarding brushless motors.

(Prior art) A rotor magnet magnetized to 2n (an integer greater than or equal to n minus 1) poles, a three-phase drive coil that rotationally biases this rotor magnet, and a position of the rotor magnet are detected.
It has a plurality of position detectors that generate substantially sinusoidal output signals with a phase difference of 20 degrees, and a drive circuit that amplifies the output signals of the position detectors and drives the drive coil with electricity. Brushless motors are known.

Figures 7 to 9 show conventional examples of such brushless motors, which have two position detectors and a three-phase drive coil, and are energized in an analog direction of 180 degrees. show. In FIGS. 7 and 9, two position detectors A and B are arranged opposite to the rotor magnet 1 which is magnetized to 2n poles, and each position detector A and B corresponds to the rotation of the rotor magnet 1. Accordingly, a substantially sinusoidal detection signal is output. By shifting the positions of the position detectors A and B, each output signal Ain and Bin
are set to have a phase difference of 120° as shown in FIG. 8(1). LA, LB, and LC are drive coils for each phase, and they are arranged at positions deviated by 30 degrees in electrical angle from the center between the drive coils that are close to each other in the position detectors A and BH1.

As shown in FIG. 7, the output signal Ain of the position detector A is amplified by a drive circuit consisting of a sensor amplifier 3 and a coil drive amplifier 7, and this drive circuit outputs a signal Aout corresponding to the signal Ain. The first phase drive coil LA is energized and driven. Similarly, the output signal Bind of the position detector B is amplified by a drive circuit consisting of a sensor amplifier 4 and a coil drive amplifier 8, and this drive circuit drives the second phase drive coil LB with a signal Bout corresponding to the signal Bin. It is designed to be powered by electricity. The outputs of each of the sensor amplifiers 3.4 are added by an adder 5 and then inverted by an inverting amplifier 6. This inverted output is amplified by a drive circuit consisting of a coil drive amplifier 9, and a signal corresponding to the inverted output is amplified by a drive circuit including a coil drive amplifier 9. (The 3rd phase drive coil LO is energized and driven when it is out.

According to the above conventional example, as shown in FIG. 8 (■), the output Aout of each drive amplifier 7.8.9,
Bout and Cout have a sine wave-like waveform that is out of phase with each other by 120 degrees in electrical angle, and these outputs drive the coils LA, LB, and LC of each phase, so
It has many advantages such as zero torque ripple, good wow and flutter characteristics, extremely low mechanical noise and electrical noise, and two-cell/three-phase drive capability.

(Problems to be Solved by the Invention) According to the above conventional example, although it has many advantages, as shown in FIG. Since it is necessary to dispose the position detector at an electrical angle of 30 degrees from the center of the drive coil, and the position detector cannot be disposed at the center between adjacent drive coils or at the center of each drive coil, the following problems occur.

■For small motors, etc., there may not be enough space to place a position detector, and even for non-small motors, there is little space to place a position detector, and if you forcefully place a position detector, the back emf waveform of each drive coil and the energization The phase with the waveform is shifted, efficiency decreases, and torque ripple increases.

■The position detector is affected by the magnetic field generated by the drive coil, and the output of the position detector may be distorted.

■It is difficult to obtain the position accuracy of the position detector.

■In the case of switching energization, in which the position detection signal is digitally processed, the phase of the position detection pulse can be shifted relatively easily, so in the case of 1200 switching energization, the position detector is placed at the center between the drive coils that are close to each other, or each drive It is possible to place a position detector at the center of the coil, but in the case of conventional analog energization in which the sine wave-like output waveform of the position detector is amplified to drive the drive coil, it is possible to place the position detector in the center of the coil. It cannot be placed in the center between the coils or in the center of each drive coil, and cannot be used in common with a 120° switching energization motor.

An object of the present invention is to solve the above-mentioned conventional problems by making it possible to arrange a position detector at the center between adjacent drive coils or at the center of each drive coil, as in the case of 120° switching energization. Our objective is to provide brushless motors with improved performance.

(Means for Solving the Problems) The present invention comprises a rotor magnet magnetized to 2n (n is an integer of 1 or more) poles, a three-phase drive coil that rotationally biases this rotor magnet, and a A plurality of position detectors that detect the position of the magnet and generate approximately sine wave-like output signals with a phase difference of 120 degrees, and a drive that amplifies the output signal of the position detectors and drives the drive coil by energizing it. a brushless motor having a circuit, wherein the drive circuit is provided with a phase shift circuit that synthesizes each output signal of the plurality of position detectors and shifts the phase by 30 degrees in electrical angle, and The phase shift circuit is characterized in that it is arranged at the center between the driving coils that are close to each other or at the center of the driving coil. °Shift.

This phase shift circuit makes it possible to extract three-phase substantially sinusoidal output signals whose phases are shifted by 120 degrees from each other, and the drive coils of each phase can be driven by these three-phase output signals. By providing the above-mentioned phase shift circuit, the position detector can be placed at the center between adjacent drive coils or at the center of the drive coils.

(Embodiment) FIGS. 1 to 3 show an example of a two-sensor, three-phase, 180° analog energization type brushless motor.

In FIGS. 1 and 3, three-phase drive coils LA, LB, and LCt face a rotor magnet magnetized to 2n (n is an integer greater than or equal to 1) poles and urge the rotor magnet 11 to rotate. are arranged, and the center between the mutual drive coils LA and LB, and the mutual drive coil LB,
At the center between the LOs, position detectors A and B each consisting of a magnetoresistive element, a Hall element, etc. are arranged so as to face the rotor magnet E1. Since the position detectors A and B are arranged in the above relationship, the rotor magnet 11
When rotates, the output signal Ain of each position detector A, B,
13 inches is 1 as shown in Figure 2 (I).
This becomes a substantially sinusoidal signal with a phase difference of 20°.

In FIG. 1, the output signal Ain of the position detector A is amplified by the sensor amplifier 13 to become the signal a, and the output signal Bin of the other position detector B is amplified by the sensor amplifier 14 to become the signal A. The signal is inverted and amplified twice by the signal a amplifier 15 to form a signal n. Also, the signal A is amplified twice by the amplifier 16 to become the signal 2b, and is inverted by the inverting amplifier 17 to become the signal 100.The signal a and the signal 100 are added by the adder 18 to become a+100. , is input to the coil drive amplifier 21. Signal a and signal 2 above
b is added by the adder 19 to become a + 2b, which is input to the coil drive amplifier 22. The above-mentioned signal bar and signal 100 are added by an adder 20 to become 2a+b, which is input to a coil drive amplifier 23. Each coil drive amplifier 21, 22, 23 receives a signal A corresponding to each of the above input signals.
Out, Bout, and Cout drive the p-phase drive coils [, A, LB, and LCt. As the rotor magnet 11 rotates, back electromotive voltage signals EA, EB,
El:O is obtained.

In FIG. 1, the circuit portion from the sensor amplifiers 13 and 14 to the coil drive amplifiers 21, 22, and 23 amplifies the output signals of the position detectors A and B to drive the drive coil LA,
It constitutes a drive circuit that drives LB and LO with electricity, and in this drive circuit, the circuit portion including amplifiers 15, 16, 17, adder 18, and 9 and 20 is the position detector A, Combine the H output signals and adjust the phase to 30 degrees in electrical angle.
Each signal (a+b
), (a+2b), (2a+b,), as shown in FIG. 2 (It), the output signals are approximately sinusoidal with a phase difference of 120', In addition, the position detector A shown in FIG.
, B's output signals Ain and Bin, the signal (a+b)
, (a + 2b) are shifted in phase by 30 degrees in electrical angle, and the third phase output signal (2a + b) is also the same as the conventional one, which is simply adding and inverting the output signals of two position detectors. The phase is shifted by 30 degrees in electrical angle with respect to the signal.

Each of the coil drive amplifiers 21, 22, and 23 generates the above-mentioned composite signal (a+b), which is a sine wave with a phase difference of 1200, (
a+2b), an output signal Aout according to (2a+b),
Bout, Cout, each phase coil LA, LB,
Since the IC is energized and driven, the rotor magnet 11 can be driven to rotate with zero torque ripple. Figure 2 ([1) shows each phase coil LA, LB, Lc.
The waveforms of the back electromotive voltages EA, EB, and EC are shown and have the same phase as the driving waveforms of the coil drive amplifiers 21, 22, and 23, and are sinusoidal.

This relationship will be explained in detail below. The phase relationship between the output signals Ain and Bin of the position detectors A and B in FIG. 1 and the phase relationship between the back electromotive voltages EA%EB and EC are as follows.

In order to rotate the motor efficiently, it is necessary that the energizing waveform to the coil and the back electromotive voltage waveform are in phase, so the output of the two position detectors Ain and 13in only needs to be in phase with the back electromotive voltage waveform. Three pressure sinusoidal coil energization waveforms must be synthesized. Position detector output Ain, gin
are synthesized as shown in Fig. 1, resulting in the coil energization waveform Aout, 3out, (::, out. Here, Ain = a = sin θ, B1n = b =
s in (θ-120°), and the coil energization waveform Ao
ut is Aout= Ain + Bln = a + b = sinθ-5in(θ-120°) = sinθ-(sinθ・C08120°−cosθ・
5in120°)=n(cos30°tSlnθ+5i
n30°"cos θ)=1'jsin(θ±30°),', Aout Q[EA. Also, the coil energization waveform Bout is Bout
= Ain + 2Bin = a + 2b = sin θ + 2 sin (θ-120°) = sin θ + 2
(sinθaCO3120°−cosθho5in12(
1°)'=sinθ-5inθ-(a c
o sθ=−convex cosθ=η5in(θ−90°),, Bout QCEB. In addition, the coil energization waveform (:out is Cout
= 2Ain + B1n = 2a + b = -2 sin θ - 5 in (θ - 120°) = f3 (c
os210'・sinθ-5in210°'cosθ)
=! /'3(Sinθ-cos210°-cosθ・5
in210°)=l'3sin(θ-210°),',CoutoCEC.

In this way, according to the above embodiment, the two position detectors A
By combining the output signals of ,B, it is possible to obtain a 3-accumulated pressure sinusoidal wave whose phase is shifted by 30° compared to the conventional 2-sensor, 3-phase, 180° analog energization type. It is possible to drive the drive coils by energizing them, and it is also possible to place a position detector at the center position between the drive coils, as shown in FIG. became.

Further, according to the present invention, as shown in FIG.
The two position detectors A and B can be moved 120 degrees in electrical angle from the arrangement position shown in FIG. 3 and placed at the center position of the drive coil. In this case, the three-phase drive coils LA, 'LB, and LC are arranged 240 degrees electrically apart from the arrangement position shown in Figure 3, and the coils I, B
Position detector 6. , position detector B is placed at the center of J-il LC. Then, the signal from the position detector A and the signal from the position detector B are combined and phase-shifted by a phase shift circuit similar to that of the above embodiment, and the drive coils of each phase are driven in accordance with this shifted signal. By doing so, it is possible to obtain the same results as in the above embodiment. Fig. 6 shows the placement position of the position detector in a conventional two-sensor, three-phase brushless motor with respect to a surface-facing slotless motor. , shows the relationship with the arrangement position of the position detector in each embodiment of the present invention described so far. In the embodiment of the present invention, two position detectors are mounted on the substrate 25, as indicated by A1 and B1, at the center between the respective drive coils LA, LB and at the center between the drive coil LBSLC.
or at the inner peripheral edge of the substrate 25 at the center between the drive coils I, A, and LB and between the drive coils LB and LC, as shown by A2 and B2. Furthermore, instead of these positions, it can also be placed in the center of the drive coil, as shown at A3, B3. On the other hand, conventionally, a
As shown in l, bl or a2, b2, it is necessary to shift the position detector by 30 degrees in electrical angle from the center between the matching drive coils, and the space in which to place the position detector is limited. It will be done.

By the way, the present applicant has developed a rotor magnet magnetized to 2n poles, a three-phase drive coil that rotationally urges this rotor magnet, and a phase difference of 120 degrees in electrical angle by detecting the rotational position of the rotor magnet. generates an output signal with 2
a synthesizer that adds the respective output signals of these two position detectors to synthesize a third phase signal, and a synthesizer that adds the output signals of these two position detectors to synthesize a third phase signal, and a The output voltages are each raised to a power, and the sum of the power results is set to an even number so that the sum of the power results is a constant value. We previously filed a patent application (Japanese Patent Application No. 58-201810) regarding a brushless motor equipped with means for controlling the two position detectors so that The present invention can also be applied to the invention related to the above application, and thereby,
It is possible to obtain the effect of correcting variations in position detectors.

The embodiments described so far are all of the two-sensor, three-phase type, and any shape may be used as long as it is the two-sensor, three-phase type. For example, it can be applied to cored, coreless, slotless, surface facing, circumferential facing, and other various forms.

The present invention is also applicable to a three-sensor, three-phase type brushless motor. Fig. 5 shows an embodiment thereof, and the output signals of the three position detectors A, B, and C can be applied to a sensor amplifier. After being amplified into signals a, b, and c by 31, 32, and 33, they are sent to inverting amplifiers 34, 35, and 36 and adders 37.
38.39 are synthesized and phase shifted, each signal of Aout=a+b Bout = b + c (::out = c + a) is taken out, and the drive coil of each phase is adjusted according to each of these signals. In this case as well, the phase of the combined signal is shifted by 30 degrees in electrical angle, so position detectors A, B, and C are positioned at the center between the drive coils or between the drive coils. can be placed in the center of

(Effects of the Invention) According to the present invention, a phase soft circuit is provided that synthesizes each output signal of a plurality of position detectors and shifts the phase by 30 degrees in electrical angle, and the phase shift circuit responds to the phase-shifted signal by Since the drive coils are driven by the drive coils, it is possible to arrange the position detector at the center position between the drive coils or at the center position of the drive coils. This derives the following effect.

■The placement space for the position detector is sufficiently large, and there is no need to forcefully place the position detector even in small motors, etc., so there is no phase shift between the back electromotive voltage waveform and the energization waveform, resulting in high efficiency and small torque ripple. Become.

■The position detector is hardly affected by the magnetic field generated by the drive coil.

■The positional accuracy of the position detector can be visually confirmed, making it easy to obtain positional accuracy.

(2) The location of the position detector is the same as in the case of the 120° switching energization method, allowing for common parts.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Fig. 2 is a waveform diagram showing signal waveforms of various parts in the above embodiment, and Fig. 3 is the arrangement relationship between the position detector and the drive coil in the above embodiment. FIG. 4 is a developed view showing another embodiment of the present invention according to FIG. 3, FIG. 5 is a circuit diagram showing still another embodiment of the present invention, and FIG. 6 is a position detection diagram. A plan view showing an example of the arrangement position of elements in the case of the present invention and in the conventional case,
Figure 7 is a circuit diagram showing an example of a conventional brushless motor, Figure 8 is a waveform diagram showing signal waveforms of various parts in the conventional example, and Figure 9 is the arrangement relationship between the position detector and drive coil in the example above. FIG. 11...Rotor magnet, LA, LB, LO
... Drive coil, A, B, C... Position detector,
15.16.17... Amplifier forming a phase shift circuit, 18.19.20... Adder forming a phase shift circuit, 21.22.23... Coil drive amplifier forming a drive circuit. (1 other person)

Claims (1)

[Claims] A rotor magnet magnetized to 2n (n is an integer of 1 or more) poles, a 3-phase drive coil that rotationally urges this rotor magnet, and a position of the rotor magnet is detected.
A brushless motor that has a plurality of position detectors that generate approximately sine wave-like output signals with a phase difference of 20 degrees, and a drive circuit that amplifies the output signals of the position detectors and drives the drive coil with current. The drive circuit is provided with a phase shift circuit that synthesizes the output signals of the plurality of position detectors and shifts the phase by 30 degrees in electrical angle, and the position detectors are connected between the drive coils adjacent to each other. A brushless motor characterized in that the brushless motor is arranged at the center of the drive coil or at the center of the drive coil.