JPH02179294A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To enhance an efficiency and to largely reduce a current consumption by calculating a separated signal in response to a pole, and combining it to obtain 3-phase full-wave driving signals with el phase deviation of 120 deg.. CONSTITUTION:An O pole (which does not generate a magnetic flux due to nonmagnetization, cutout, etc.) is provided in width of approx. 1/3 of the width of the pole at the center of a position detecting magnet 1b having the same number of poles as that of a driving magnet 1a. N-O-N poles are disposed corresponding to the N-poles of the driving magnet 1a, and S-O-S poles are disposed corresponding to the S-poles of the driving magnet 1a. After the output of a magnetic detector 11 for detecting the magnetic flux of the position detecting magnet 1b is applied to an amplifier 12, the upper and lower sides of the output waveform are shaped through a waveform shaper 13 having threshold characteristics. A signal in which el phases are deviated at 120 deg. is obtained by calculating by a signal processor 4, outputs to a driving circuit 15 to drive with 3-phase full-wave 180 deg. el phase.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a brushless DC motor that enables three-phase full-wave drive with one magnetic detection element.

Conventional technology In recent years, small DC motors have been used not only in the acoustic field (but also in the information and
Its excellent controllability has also been recognized in the industrial field, and its applications are rapidly expanding. Among these, brushless DC motors have the advantage of having no contact parts such as brushes and commutators, and have a long life, so their use as industrial motors where reliability is particularly important is expanding.

Under these circumstances, the drive method of small axial fans has been switched from alternating current to direct current in recent years, and the number of direct current axial fans using brushless direct current motors is increasing.

DC axial fans are required to have a drive circuit housed in a limited space and to be low cost. In order to achieve these things, we have adopted a two-phase half-wave drive type, which can be driven by a single magnetic detection element and has simple wiring, from among various types.

The conventional two-phase half-wave drive system used in DC axial fans will be briefly explained using drawings.

FIG. 7(a) shows a drive circuit of the most common two-phase half-wave drive system, in which output transistors 53 and 54 are connected in series to A-phase and B-phase drive coils 51 and 52, respectively. FIG. 7(b) shows the magnetization distribution of the rotor magnet 55, which consists of a drive section 55a and a position detection section 55b. FIG. 7(C) shows the induced voltage waveform generated in each phase 51, 52 of the drive coil, and FIG. 7(d) shows the magnetic flux distribution of the position detecting portion 55b of the rotor magnet 55. The magnetic flux of the position detecting section 55b of the rotor magnet 55 is detected by a position detecting element (not shown), and the output is used to detect the A phase and B phase.
The output transistors 53 and 54 of each phase can be turned on alternately every 180°el to rotate the rotor, but the rotor stops at the point at which no induced voltage is generated (dead center = Ov) in Fig. 7(C). This motor cannot be started automatically when the Therefore, to compensate for this, for example, the drive coil 51.5 is designed to stop at a point other than the point where the induced voltage becomes OV.
Reluctance is provided by making the gap between the stator core (not shown) around which magnet 2 is wound and the rotor magnet 55 uneven. In this way, you will always have starting torque at startup,
It can rotate normally.

Next, FIG. 8 shows a diagram in which the magnetization distribution of the magnet has been devised in order to solve the above-mentioned problem at startup.

(Special Publication No. 43-8771).

That is, FIG. 8(a) shows a drive circuit, in which an output transistor 3.degree. 64 is connected to the A-phase and B-phase drive coils 61, 62, and the configuration is the same as that of FIG. 7(a).

FIG. 8(b) shows the magnetization distribution of the rotor magnet 65, in which a drive part 65a having an O pole (non-magnetized part) between the N and S poles and a position detection part magnetized by N and S. Consists of 65b.

FIG. 8(C) shows the induced voltage waveform generated in each phase of the coil, and FIG. 8(d) shows the position detection section 65b of the rotor magnet 65.
represents the magnetic flux distribution. If the magnetization distribution of the rotor magnet 65 and the shape of the stator core are appropriately selected, Fig. 8(C)
The induced voltage waveform can be expanded to 180°e1 or more as shown in FIG.

In this way, the magnetic flux of the position detecting section 65b is detected by a position detecting element (not shown), and the output transforms the output transistors 1.62 of the A phase and B phase alternately every 180''e1. Even when rotating, there is always an induced voltage, so there is no dead center.

Therefore, the dead point problem at startup does not occur.

Problems to be Solved by the Invention As explained above, the two-phase half-wave drive system has the advantage of a simple structure, but on the other hand, it is extremely inefficient as a motor. Therefore, it has drawbacks such as high current consumption, large magnets and windings, and heavy weight.

As a method for driving two or more phases with one magnetic detection element, a three-phase half-wave drive method as shown in FIG. 9 can be considered.

FIG. 9(a) shows a drive circuit, in which output transistors are connected to drive coils 71, 72, and 73 of A, B, and C phases. 4,7
5.76 are connected in series. Figure 9 (b
) shows the magnetization distribution of the rotor magnet 77, which is composed of a drive section 77a that is magnetized to N and S, and a position detection section 77b that has an O pole (non-magnetized section) between the N and S poles. Figure 9 (C
) is the induced voltage waveform generated in each phase of the coil, Figure 9(d)
9 represents the magnetic flux distribution of the position detecting portion 77b of the rotor magnet 77, and FIG. 9(e) represents the motor drive signal. As shown in FIG. 9(b), the position detecting section 77b is magnetized so that it becomes N-0-3, and as shown in FIG. 9(d), the output of the position detecting element has threads on the e side and the By providing a shoulder and processing it with logic, a ternary signal as shown in FIG. 9(e) is obtained. This ternary signal turns the A-phase, B-phase, and C-phase output transistors 74°75.76 in FIG. 9(a) to 1.
By sequentially conducting every 20''el, it is possible to perform a drive without dead center. However, even this method is still a step away in terms of efficiency.

The present invention realizes a motor drive system capable of three-phase full-wave drive with a single magnetic detection element, and has a simple wiring structure and high efficiency (
It is an object of the present invention to provide a brushless DC motor that can greatly reduce current consumption.

Means for Solving the Problems The present invention arranges N-0-N poles (0 is a non-magnetized part) corresponding to the N poles of a multipolar magnetized driving magnet part and the driving magnet part, 5 corresponding to the S pole of the drive magnet part
- A position detection magnet section with an O-S pole arranged, one magnetic detection element that is arranged opposite to this position detection magnet section and outputs a position signal, and an output signal from the position detection element. an amplification circuit that amplifies the width; a waveform shaping circuit that separates the amplified position signal corresponding to the magnetic pole;
It is equipped with a signal processing circuit that synthesizes the separated signals to generate a three-phase full-wave drive signal, and a three-phase full-wave drive circuit that drives a three-phase coil based on the signal from this signal processing circuit. .

Effect According to the above configuration, when the output of the magnetic detection element is applied to the amplifier and then waveform-shaped through a waveform-shaping circuit having threshold characteristics on the upper and lower sides of the output waveform, the output waveform is shaped according to the magnetic pole. Separated signals are obtained, and by processing these signals in a signal processing circuit and combining them, 1
A three-phase full-wave drive signal with a 20°e1 phase shift is obtained,
Based on this signal, the drive circuit can be operated to perform three-phase full-wave drive.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a pattern diagram of magnetization distribution when a ring-shaped rotor magnet is developed, FIG. 2 is a sectional view showing the configuration of a brushless morph, and FIG. 3 is a sectional view showing the rotor portion of FIG. 2. In the figure, 1 is a ring-shaped rotor magnet fixed to the inner surface of the rotor frame 2, 3 is a support base equipped with a bearing 5 on the inner circumference that supports the rotor shaft 4, and a drive coil 6 on the outer circumference via the stator core. , 7 is a magnetic detection element provided opposite to the position detection section 1b of the rotor magnet 1, and 8 is a circuit board. In the above configuration, except for the magnetization distribution of the rotor magnet 1 and one magnetic detection element 7, the motor has a normal two-pole, three-phase, three-coil motor structure. One of the structural features of the present invention is the magnetization distribution of the rotor magnet 1. That is, as shown in FIG. 1, an O pole (not magnetized or notched) is placed in the center of the position detection magnet part 1b, which has the same number of magnetic poles as the drive magnet part 1a, with a width of about 1/3 of the magnetic poles. A part that does not generate magnetic flux) is provided, an N-0N pole is arranged corresponding to the N pole of the driving magnet part 1a, and a 5-O-S pole is arranged corresponding to the S pole of the driving magnet part 1a. ing. Such a magnetic pole distribution can be easily achieved by devising a magnetizing yoke or by providing a notch using a plastic magnet or a rubber magnet.

The signal waveform in FIG. 4 and the block diagram in FIG. I will explain using

The output waveform of the magnetic detection element 11, such as a Hall element, which detects the magnetic flux of the position detection magnet part 1b is as shown in FIG. 4(a). After this output is applied to an amplifier 12, the output waveform is shaped through a waveform shaping circuit 13 having threshold characteristics on the upper and lower sides, respectively, as shown in FIG. 4(C).

A waveform as shown in FIG. 4(d) is obtained. These waveforms and the waveform of FIG. 4(b) obtained by further amplifying FIG. 4(a) are subjected to arithmetic processing in the signal processing circuit 14. That is, Fig. 4 (
When the positive side of b) and the inverted signal of Fig. 4(C) are processed by the signal processing circuit 14, Fig. 4(e) and Fig. 4(g) are obtained.
get. Similarly, when the signal processing circuit 14 processes the negative side inverted signal in FIG. 4(b) and the inverted signal in FIG. 4(d), the result is shown in FIG. 4(g) and FIG. 4(h). get.

Of the four signals obtained as described above, Figure 4 (
Figure 4 (i) is obtained by calculating e) and Figure 4 (1'0) using a NOR circuit, and similarly Figure 4 (f) and Figure 4 (g) are calculated using a NOR circuit. After processing, Fig. 4(j) is obtained. Next, Fig. 4(e) and Fig. 4(f) are combined to obtain Fig. 4(ri), and in the same way, Fig. 4(g) and Fig. 4(f) are combined. Figure 4 (i
4(1) can be obtained from ), and FIG. 4(Ill) can be obtained from FIG. 4(h) and FIG. 4U). Figure 4(k)
.

Further, by driving with six signals shown in FIG. 4(e) to (D), three-phase aftereffect 120 DEG EL driving can be performed.

Among the circuit configurations that perform the series of operations described above, the signal processing circuit 14 will be described based on one embodiment. As shown in FIG. 25 and 26 and the first
logic gates 28 and 29 whose input terminals and output terminals are cross-coupled connected to each other; and a logic gate 2 whose output terminal is connected to a second input terminal of the logic gate 25.
3, a logic gate 27 whose output terminal is connected to the second input terminal of the logic gate 28, and a logic gate 30 whose first input terminal is supplied with the output of the gate pair of the logic gates 28 and 29. a first gate of the logic gate 23;
The output of the pair of gates formed by the logic gates 21 and 22 is supplied to the input terminal of the logic gate 27, the output of the pair of gates formed by the logic gates 25 and 26 is supplied to the first input terminal of the logic gate 27, and the output of the pair of gates formed by the logic gates 25 and 26 is supplied to the first input terminal of the logic gate 27. The second input terminal, the second input terminal of the logic gate 26, the second input terminal of the logic gate 29, and the second input terminal of the logic gate 30 are connected and sufficiently amplified by the amplification circuit 12. The output signal (first signal) is supplied to the second output signal of the logic gate 21.
The input terminal of the waveform shaping circuit 13 is connected to the second input terminal of the logic gate 23 and the second input terminal of the logic gate 27 via the inverter 24. ) is supplied, and the logic gate 2
1 to 30 constitute a sequential circuit, a first output signal and a second output signal ordered are outputted to the output terminal of the logic gate 30 and the output terminal of the logic gate 25, respectively. At this time, if the positive side signal of FIG. 4(b) is supplied to the first signal and the inverted signal of FIG. 4(C) is supplied to the second signal, the first output signal is ), the second output signal shown in FIG. 4(f) is output. Similarly, if the first signal is supplied with the negative-side inverted signal of FIG. 4(b), and the second signal is supplied with the inverted signal of FIG. 4(d), the first output signal is Figure (g), the second output signal is Figure 4 ().
I) is output.

Furthermore, as mentioned above, using a NOR circuit, the result shown in FIG. 4(e)
4(i) is obtained from FIG. 4(i), and similarly, FIG. 4(D) is obtained from FIG. 4(f) and FIG. 4(g).

In the case of the invention of Japanese Patent Application No. 61-268001 filed by the present applicant, a frequency dividing circuit was used, so it was necessary to synchronize the signal between the rotor position and the drive signal at the time of startup.
Although a separate startup circuit is added, in the present invention, an initialization pulse is applied to the first input terminal of the logic gate 22, the first input terminal of the logic gate 26, and the first input terminal of the logic gate 28 when the power is turned on. Just supply it. If this is done, the rotation will be reversed at startup for one section each from O to the point where the upper threshold is exceeded and from O to the point where the lower threshold is exceeded in Figure 4(a). As soon as the motor passes through this section, it enters the forward rotation mode, and after that, the three-phase full-wave drive as described above can be performed.

Effects of the Invention As is clear from the above description, according to the present invention, a three-phase full-wave drive motor with higher volumetric efficiency and current efficiency than conventional two-phase half-wave drive and three-phase half-wave drive motors is capable of magnetic detection. This was realized by combining the structure of a single element and a position detection magnet. The high current effect means that the current capacity of the equipment is small, leading to energy savings and cost reductions.In addition, 3-phase full-wave drive motors can be used with 2-phase half-wave drive and 3-phase full-wave drive. Since the torque ripple is smaller than that of a motor, vibration and noise levels are also lower.

The present invention has a great effect in that a highly effective three-phase full-wave drive motor can be realized using only one magnetic detection element.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a pattern diagram of the landing time distribution when the ring-shaped magnet of the present invention is developed, Fig. 2 is a cross-sectional view showing the configuration of a brushless morph embodiment of the present invention, and Fig. 3 is a diagram of the distribution of landing times when the ring-shaped magnet of the present invention is developed. A sectional view showing the rotor part of the invention, FIG. 4 is an output waveform diagram of the signal processing of the invention,
Fig. 5 is a block diagram of the circuit configuration of an embodiment of the present invention, Fig. 6 is a circuit diagram of a signal processing circuit, Fig. 7 is an explanatory diagram of a conventional two-phase half-wave drive system, and Fig. 8 is a conventional example. FIG. 9 is an explanatory diagram of another two-phase half-wave drive system as an example, and FIG. 9 is an explanatory diagram of a conventional three-phase half-wave drive system. 1... Rotor magnet, 1a... Drive magnet section, 1b... Position detection magnet section, 5... Coil, 7, 11... ...Magnetic detection element, 12... Magnifier, 13...
Waveform shaping circuit, 14... Signal processing circuit, 15.
...Drive circuit. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] It has a multi-pole magnetized driving magnet part and the same number of magnetic poles as the driving magnet part, and has N-O-N corresponding to the N pole of this driving magnet part, and S- corresponding to the S pole of this driving magnet part. O-S
(O is a part that is not magnetized or does not effectively generate magnetic flux) and is magnetized almost equally in the shape of a position detection magnet part, which is placed opposite to this position detection magnet part, and is placed opposite to the position detection magnet part, and is placed opposite to this position detection magnet part, and receives a position signal. One magnetic detection element to output, an amplification circuit that amplifies the signal from this position detection element, a waveform shaping circuit that separates the amplified position signal corresponding to the magnetic pole, and the separated part. A brushless direct current motor comprising: a signal processing circuit that synthesizes signals for three-phase full-wave driving to create a three-phase full-wave driving signal; and a three-phase full-wave driving circuit that drives a three-phase coil based on the signal from the signal processing circuit.