JPH0442763A - Driving circuit of brushless motor - Google Patents

Abstract

PURPOSE:To perform smooth rotation control with quick response like a brush motor by providing a means, which switches the application voltage according to rotation control by pulse control and smoothes it, at the previous stage of a driver stage, which controls the current application of a stator coil. CONSTITUTION:A linear acceleration circuit 3 is provided at the previous stage 2 of a driver, which controls the timing of current application. When a transistor Q3 is turned on or turned off by a PWM control signal (to be exact, an inversion signal), driving power voltage +Vcc is switched with the pulse width of the PWM control signal. This switching waveform is smoothed with a capacitor C1 and becomes a smoothly changed waveform, and the excitation of the coil also is performed with smooth change. Accordingly, the same control as changing the supply voltage to a conventional brush motor by drop control control method is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive circuit for a brushless motor suitable for driving a tape wine goo or the like.

[Summary of the Invention] The present invention provides a linear accelerator circuit using pulse control in the front stage of the driver stage that supplies current to the stator fill in a drive circuit for a brushless motor in a tape winery, etc., to control the voltage applied to the driver stage. By controlling the rotation of a brushless motor smoothly and with high-speed response, it is possible to achieve rotation control equivalent to the drop control method of a motor with a planar blade, and it also improves the maintainability of the motor. .

[Prior Art] The process of producing a videotape includes the step of winding a long tape called a pancake onto the reel of a tape cassette. At this time, what rotates the reel is the tape wine goo. When rotating the reel of a tape cassette, mechanical play occurs when the reel is fitted onto the rotating shaft of the tape wine goo due to the structure of the rotating shaft of the reel. This play is caused by the tension of the tape when it is wound onto a reel.
This change in tension may cause the magnetic powder on the tape to fall off, which may cause the signal to blur or bleed out when the tape is used. For this reason, the tape winding motor needs to detect changes in tape tension due to backlash, etc., and use a servo system to control the tension to always be constant when winding the reel onto the tape, resulting in a high-speed response. What is required is something that can control rotation smoothly and smoothly.

Conventionally, a brushed DC (direct current) servo motor has been used as a motor satisfying such characteristics, and its rotation has been controlled by a drop control type driver circuit as shown in FIG. In this conventional example, the armature current of a motor 100 is controlled by a transistor 101, and a servo system control signal is applied to the base of this transistor 101 to lower the necessary voltage from the drive power supply voltage +Vcc. Controls rotation.

[Problems to be Solved by the Invention] However, since the tape winder according to the above-mentioned conventional technology uses a motor with a brush, there is a problem that maintenance is poor due to wear of the brush.

Therefore, it is possible to use a brushless motor, but in general, when controlling rotational torque in a brushless motor driver circuit, the control voltage of the switching element of each phase is used as a pulse signal, and the power supply voltage +Vcc is controlled with a pulse width. A PWM control method is used. Therefore, the control voltage (excitation pattern) of each phase applied to the stator fill of the brushless motor has an intermittent waveform that swings between +Vcc and QV as shown in FIG. For this reason, when viewed in detail, the rotation of the motor is no longer smooth due to repeated stops and rotations, and, expressed in an exaggerated manner, results in jerky movement similar to that of a stepping motor.

When used as a tape winder, such movements cause the tape tension to fluctuate greatly.
Unable to meet the requirements for a tape winder.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a brushless motor drive circuit that uses a brushless motor and can perform smooth rotational control with high-speed response like a motor with a plan. shall be.

[Means for Solving the Problems] The configuration of the brushless motor drive circuit of the present invention to achieve the above object is as follows: It is characterized by comprising means for switching and smoothing by pulse control in response to rotation control.

[Function] The present invention provides a driver stage that controls energization of a brushless motor by switching and smoothing the applied voltage by pulse control corresponding to rotation control, thereby eliminating the problem of sluggishness just like that of a brushed motor.

In the same way as the voltage applied to the motor using the control method,
By controlling the applied voltage of the brushless motor, equivalent high-speed response and smooth rotation control characteristics can be obtained.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In this embodiment, a case where a three-phase drive motor is used as the brushless motor will be described as an example. In the configuration of this embodiment, 1 is the three-phase drive brushless motor;
3 is a driver stage, and 3 is a linear accelerator circuit which is a means for smoothly controlling the voltage applied to the driver stage 2 in accordance with rotation control.

The brushless motor 1 has a U-phase coil IU and a V-phase coil 1.
The stator consists of a Y-connected three-phase coil with a 1° V and W-phase coil, and a rotor that is magnetized to multiple poles.
rotor), and each phase coil IU1v, 1. The timing of energization is controlled so that rotational force is always generated in the rotor. A circuit that controls this energization timing is provided in driver stage 2, which includes a set of transistors Q, , Q, and a set of transistors Q, , Q, connected in series between applied voltages +V and 0, respectively. set and transistor Q,
,Q,. Transistor QI.

The connection point of Q, is connected to the U-phase coil 1u of the brushless motor 1, the connection point of transistors Q, , Q, is connected to the V-phase coil 1v, and the connection point of transistors Q, , Q, is connected to the V-phase coil 1v.

The connection point of Q is connected to the W-phase coil 1v. The bases of these transistors Q, -Q are connected to the signals DB, U'BVB, V'B, and W that control the energization timing described above.
B and W'B are connected respectively.

The linear accelerator circuit 3 consists of npn) transistors Q, ,Q
, a bias resistor R, and a smoothing capacitor C8. Transistor Q7 has a drive power supply voltage +
VCC is connected, and a capacitor CI is connected between the emitter and Ov.
is connected, and a bias resistor R8 is connected between the collector and base.
is connected. The transistor Q has a collector connected to the base of the transistor Q, an emitter connected to Ov, and a PWM (pulse width modulation) control signal connected to the base. This PWM signal detects, for example, the rotational torque of a motor in a servo system, and its pulse width is controlled in a direction that corrects the rotational torque to the specified rotational torque in response to a deviation of the specified rotational torque. Output of linear accelerator circuit 3,
That is, transistor Q.

The output voltage from the emitter of is supplied to the driver stage 2 as an applied voltage +V.

The operation and effect of the embodiment configured as above will be described.

FIGS. 2(a) and 2(b) are explanatory diagrams of the control voltages of the coils of each phase U, V, and W of the brushless motor of this embodiment. Signals UB, U'B of driver stage 2.

Input points VB, V'B, WB, and W'H generally add a PWM control signal for rotation control in addition to a control voltage for energization timing to create an excitation pattern. Now input the control voltage just to create the excitation pattern. Then, the PWM control signal for rotation control is input to the linear accelerator circuit 3, and the driver stage 2
It is created by switching and smoothing the applied voltage +V. As a result, the U phase, ■ phase, and W phase of the brushless motor are
By switching between UB and U'B, a control voltage of +V as shown in Fig. 2 (a) is applied, and the rotor is rotated.
The rotational torque changes depending on the magnitude of +V.

In the operation of the linear accelerator circuit 3, the transistor Q
, is off, the transistor Q, through the resistor R,
A bias current flows through the base of Q7, turning on transistor Q7. Here, when transistor Q is controlled to be turned on, transistor Q.

The base of Q becomes low level, and transistor Q is turned off. Therefore, transistor Q.

is turned on/off by a PWM control signal (more precisely, an inverted signal).
When turned off, the driving power supply voltage +vcc is switched by the pulse width of the PWM control signal. This switching waveform is smoothed by the capacitor CI, resulting in a smoothly changing waveform as shown in FIG. 2(b), and the excitation of the coil is also performed with smooth changes. Therefore, control similar to changing the supply voltage of a conventional brushed motor using a drop control method is performed. That is, the rotation control of the brushless motor 1 is controlled by PW.
Even with M control, smooth continuous rotation and high-speed response,
And it can be done smoothly.

In addition, in the above embodiment, when the frequency of the PWM control signal is a high frequency of 20 KHz or more, if the components other than the transistors of the linear accelerator circuit 3 have sufficient interelectrode capacitance for smoothing, Optional. Further, the switching elements constituting the linear accelerator circuit 3 can be other than transistors, and the circuits that perform switching are not limited to the embodiments. As described above, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

[Effects of the Invention] As is clear from the above explanation, according to the brushless motor drive circuit of the present invention, it is possible to use the brushless motor for tape wind mites, etc., which was previously considered impossible, and It has the advantage of being able to reduce costs due to improved maintainability and PWM control.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2(a)
, (b) is an explanatory diagram of the control voltage of each phase coil of the brushless motor of the above embodiment, FIG. 3 is a driver circuit diagram of a tape winder of the conventional example, and FIG. 4 is a diagram of the control voltage of the brushed motor of the above conventional example. FIG. 1...Brushless motor, 1υ, 1v+lv...
・Stator coil, 2...Driver stage, 3...Linear accelerator circuit, Q, ,Q,...Transistor, CI・
...Smoothing capacitor. Figure 4

Claims (1)

[Claims] (1) A brushless motor characterized in that a means for switching and smoothing the applied voltage by pulse control in accordance with rotation control is provided at a stage before a driver stage that controls energization of a stator coil of the brushless motor. drive circuit.