JPH01318578A - Drive circuit for brushless motor - Google Patents

Abstract

PURPOSE:To obtain an easily designable high efficiency brushless motor having excellent starting performance by providing a hysteresis characteristic to a circuit for processing output signal from a rotor position detector. CONSTITUTION:When a motor is started, output from a rotor position detector 3 is fed to signal processing circuits OP1, OP2 having hysteresis characteristics H1, H2 and the output signal from OP2 is inverted through OP3 and fed to switching circuits Q1, Q2. Since the electrical power conduction angle of the motor increases by theta1+theta2+theta3+theta4 due to the hysteresis characteristics H1, H2, synthetic output torque T1+T2 as shown one the drawing is obtained and positive starting torque is produced over the entire rotary angle with no dead point, thus improving the starting performance. Furthermore, since the length of gap at the stator core salient pole section of a cored brushless motor is made constant, profile designing is facilitated and the efficiency is improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a drive circuit for a brushless motor.

[1 Summary of the Invention] The present invention provides a detector for detecting the position of a rotor, a signal processing circuit for processing an output signal of this detector, and a switching system for obtaining this output and passing a current through an armature coil. In a brushless motor drive circuit equipped with a circuit, the signal processing circuit is provided with hysteresis characteristics to control the energization angle of the motor, thereby improving motor startability, motor efficiency, and ease of motor design. It is the one that carries out the transformation.

[Conventional technology]

First, as a conventional problem, there is the problem of the motor's non-starting point, that is, the dead point, and this will be explained.

The principle of a brushless motor with one rotor position detector is shown in FIG. 11 [al to tel].

That is, FIG. 11 [al indicates a drive circuit.

In FIG. 11fbl, the rotor position detector H3 detects the north pole, excites the armature coil 24', creates the south pole, and rotates the rotor 1 in the CCW direction as shown by arrow a. 1st
In Figure 1 tel, the detector H3 has no magnetic field, and L+4
Although no current flows through L24' and L24', rotor 1 is CC due to inertia.
Continue turning in the W direction. In FIG. 11+dl, the detector H3 detects the south pole, and excites L and 4 to create the south pole and rotate the rotor 1 in the CCW direction.

As described above, the rotor 1 rotates continuously. The generated torque at this time is as shown in FIG. 11 (el), and a dead center 6 occurs.

This is due to the position where no torque appears during rotation, as shown in Figure 11 (C1).At this dead center, the motor could not be started, which was a problem.Therefore, this was improved and implemented as before. Figure 12 (at ~ (C
There is 1. FIG.
The dead center 6 is eliminated by generating the non-excitation torque (B) shown in the figure and combining this with the exciting torque (A).

[Problem to be solved by the invention]

However, in this conventional method (FIG. 12), the length of the gap 7 of the salient pole portion of the stator iron core 5 is changed to eliminate the dead center, so the efficiency of the motor is sacrificed ( (The length of the gap portion 7 becomes larger), and in order to reverse the rotation direction, it is necessary to turn the stator core 5 upside down.Since the shape of the salient pole portion of the stator core 5 is complicated, it is difficult to design and evaluate it. However, it has disadvantages such as requiring a lot of time.

[Means to solve the problem]

The present invention eliminates the disadvantages of the brushless morph, such as poor efficiency, difficulty in reverse rotation, and difficulty in designing the shape of the salient pole portion of the stator core, and achieves good starting performance and easy design. The purpose is to provide a drive circuit for creating an efficient brushless morph. Therefore, in the present invention, the energization angle of the motor can be freely controlled by providing a hysteresis characteristic to the signal processing circuit that processes the output signal of the position generator of the rotor of the brushless morph.

[Effect]

The operation of the present invention will be explained with reference to FIGS. 1 to 7. The brushless morph permanent magnet rotor 1 is generally magnetized in a sinusoidal manner as shown in FIG. On the other hand, as a position detector 3 for the rotor 1, there is a Hall element which is of a magneto-electric conversion type and is currently commonly used. First, the circuit shown in FIG. 4 is provided at the time of starting the motor.

Then, the hysteresis characteristics H6 and H, as shown in FIG.
is added to the signal processing circuit ○P and OP2 having
The output signal of P2 is inverted at OP and sent to the coil 'R? A
is applied to switching circuits Q1 and C2 for flowing . Due to the hysteresis characteristics H and Hz, the 1ifI electrical angle of the morph increases by 01 + θ2 + θ3 + θ in electrical angle, so the composite output torque T, 10T, becomes as shown in Figure 5, and the total rotation angle is A positive starting torque is generated over the period of time and no dead center occurs.On the other hand, when the motor starts up and reaches a certain rotation speed, the circuit shown in Figure 6 is applied.The output signal of the position detector is shown in Figure 4. Similarly, the signal processing circuit op,
It is applied to switching circuits Q3 and C4 via opz and opx.

At this time, the energization angle of the motor is θ1 +θ2+
Since it decreases by θ3+θ4, the composite output torque 'r3+
Tm is as shown in FIG. 7, and the efficiency is 2π.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure is a sectional view of a brushless morph of an outer rotor in which a stator is a ferrous core 5 of 4 poles and 4 coils. The output signal of the position detector 3 that detects the position of the permanent magnet rotor 1 is
After adding 1° to the signal processing circuits OP and OPz to OP of FIG. 4 or FIG. 6, the switching circuit Q4.0
The two feet are transmitted to Q, , Q, , and by passing current through the armature coil 4, the stator iron core 5 is magnetized, and a rotational torque is generated in the permanent magnet rotor 1, causing it to rotate.

FIG. 8 is a sectional view of a two-pole, two-coil iron-core brushless motor according to another embodiment of the present invention, and the drive circuit and other components are the same as those in FIGS. 2 to 7.

Figures 9 and 10 are examples of flat type ironless core brushless morphs with 4 poles and 2 coils, including a permanent magnet rotor (Figure 9) and a stator (
(FIG. 10), and the drive circuit and other components are the same as those in FIGS. 2 to 7.

〔Effect of the invention〕

As described above, the present invention includes a detector that detects the position of the rotor, a signal processing circuit that processes the output signal of this detector, and a switching circuit that causes current to flow through the armature coil based on the signal obtained from the detector. In the brushless morph drive circuit, the seed signal processing circuit has hysteresis characteristics, making it possible to control the energization angle of the motor. For example, by increasing the conduction angle from 2π (electrical angle),
This eliminates the dead center of the brushless morph and improves start-up performance. Further, since the gap length of the stator iron core salient pole portion of the iron core brushless smoke can be made constant, the shape design is easy and efficient.

Furthermore, when reversing the rotation direction, there is no need to turn over the stator core, and this can be done by selecting a drive circuit. or,
During rotation, the motor efficiency can be significantly improved by reducing the current conduction angle from 2π (electrical angle).

[Brief explanation of the drawing]

1 to 7 are detailed explanations of the present invention, and FIG.
FIG. 2 is a diagram showing the magnetization polarity of the rotor, and FIG. 3 is a diagram showing the signal processing circuit. Output characteristic diagram, Figure 4 is a circuit diagram showing the state at startup, Figure 5
The figure is a waveform diagram of each part showing the process of generating a composite torque in a starting state, FIG. 6 is a circuit diagram in a rotating state, and FIG. 7 is a waveform diagram of each part in a rotating state. FIG. 8 is a sectional view of another embodiment of the present invention, FIG. 9 is a plan view of a rotor of another embodiment of the present invention, and FIG. 10 is a plan view of a stator applied to FIG. 9. be. Fig. 11 is a drawing explaining the conventional problems, fat is a circuit diagram, (b) to fdl are plan views showing the state of the rotor, (el is a characteristic diagram showing the generated torque and dead center, the 12th , is an explanatory diagram of an improved conventional motor, (al is a sectional view, Tbl is a circuit diagram, (C1 is a characteristic diagram where a composite torque is generated. Yoke 3...Position detector 4.4'...Armature coil 5...Stator core or higher Output 1 now 4
Figure 1 ￥52 Figure 3 Figure 1 of the present invention
West view of the example of t Hakuma. a) Turning diagram Figure 12 (b) Special 4 raw map of the match battle turf Figure 12 (C) Conventional improved 3rd bill rs rice cake side diagram and circuit diagram and mark 4 raw diagram 2nd figure

Claims (1)

[Claims] A detector that detects the position of the rotor, a signal processing circuit that processes the output signal of the detector, and a switching circuit that obtains the output signal of the signal processing circuit and causes a current to flow through the armature coil. In the brushless motor drive circuit,
A drive circuit for a brushless motor, characterized in that the signal processing circuit has a hysteresis characteristic.