JPS60204287A - Operation controller of brushless motor - Google Patents

Abstract

PURPOSE:To eliminate an unstable operation by a noise signal by providing a DC bias circuit for shifting the level of an AC signal in a shaper for shaping a rotary position signal of a magnet rotor. CONSTITUTION:The rotary position of a magnet rotor 22 is detected, for example, by a Hall IC as detecting means 25 and the output becomes base control signals of two corresponding transistors of six transistors of a drive circuit 24 by a logic circuit 26. After the output of detecting means 25 is converted by an F/V converter 36, it is supplied as a PWM control signal to a rotating speed controller 37. A rectifier 28 which includes a DC bias circuit 32 is provided at the front stage of the converter 36, and the influence of the noise signal is removed by shifting the level of the AC signal by the bias circuit 32.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a speed control device for a brushless motor.

First Prior Art Conventionally, in low-output brushless motors, the rotational speed of the magnetic rotor is detected separately from the detection means for detecting the rotational position signal of the magnetic rotor, as disclosed in, for example, Japanese Utility Model Publication No. 56-28855. In addition to providing a detection means, it is desirable to generate a rotational speed signal using a one-rotation position signal for miniaturization.

In addition, in low-output brushless motors, when limiting the amount of current flowing through the stator coil, the voltage between the collector and emitter of the transistor connected in series with this coil is increased, but this method is not applicable to high-output brushless motors. The above-mentioned method cannot be used in the case of the crested ibis, since the energy loss caused by the transistor is large and it is necessary to use a transistor with a high withstand voltage. Therefore, it is conceivable to cause a current subjected to pulse width modulation (hereinafter referred to as pWM) to flow through the stator coil.

FIG. 1 is a block diagram of a brushless motor operation control device constructed in consideration of the above circumstances.

In this drawing, a brushless motor (11) includes a magnet rotor (2) and a multi-phase stator coil (3),
The rotational position of the magnet rotor (2) is detected by a detection means (4) consisting of a Hall E0 or the like. This detection signal (81) is as shown in FIG. 2 for the stator coil phase component), and the logic circuit (5) generates a control signal (82) for the transistor corresponding to the stator coil. This control signal is applied to one input terminal of the AND circuit (6), and when the input signal (S5) at the other input terminal is high, A
An ND output (S4) is applied to the drive circuit (7). This drive circuit has a transistor that controls energization of the stator coil (3), and this transistor is connected to an AND circuit (6).
energization is controlled by the output (84) of the magnet to generate a rotating magnetic field and rotate the magnet rotor (2).

The detection signal (Sl) of the rotational position is converted into a current-changing signal (85) shown in Fig. 3 in a switching circuit aυ consisting of a capacitor (8) and a resistor (9) (1G).This AC signal is F
/V converter circuit a2 converts the AC signal into a DC voltage according to the frequency, and the DC voltage is compared with a reference voltage in the rotation speed control circuit (13) and outputs an error signal. The PWM circuit receives the optical power and outputs it as a PWM output signal (si) corresponding to the error signal.
It is applied to the other input terminal of the D circuit (6). Therefore, AN
The output (Sa) of the D circuit (6) is the PWM output signal (sg
) is high, the signal corresponds to the control signal (S2), and the energization of the stator coil (3) is controlled by PWM.

Therefore, the AC signal (S5) which is the output of the regulator circuit Qll
Then, the clock signal in the PWM circuit I becomes a noise signal (S6
), and while the motor (1) is rotating, it does not intersect with the zero value line as shown in Figure 3, so there is no effect, but the rotational position detection when the motor (1) is locked, etc. When there is no signal (Sl), the output of the paper straightening circuit 1111 is only a noise signal (S6) as shown in FIG. 4, and depending on the frequency of this noise signal, a DC voltage is output from the F/V conversion circuit a2. Even when the restraint state is released, it is difficult to start the motor, and this also applies to the case where the PWM circuit is activated by light during power transmission, so it cannot function sufficiently as an operation control device. I will not do it.

(c) Purpose of the invention The present invention has been devised in view of this point.

The object of the present invention is to provide an operation control device that prevents malfunctions such as when a motor is locked.

B) Structure of the Invention In order to achieve the above object, the operation control device according to the present invention converts the rotational position signal of the magnet rotor into an alternating current signal in an alignment circuit, converts this alternating current signal into y7v, and converts it into an output. In the brushless motor operation control device that performs PWM control on a stator coil current, the alignment circuit is provided with a DC bias circuit that level-shifts the AC signal.

(E) Embodiment An embodiment of the present invention will be explained based on the drawings. FIG. 5 is a block diagram of a speed control device for a brushless motor. In this drawing, (21) is a brushless motor, which has a magnet rotor and a three-phase stator coil (toward), and the stator coil is star-connected. (to) is a drive circuit that includes a bridge circuit consisting of six transistors that connects one end of each stator coil to a power supply terminal and a ground terminal.

The rotational position of the magnet rotor (2) is detected by a detection means (2!9, for example, Hall E0), and a rotational position signal (Sl) shown in FIG. 2 is output for each stator coil (C). Each position signal (Sl) is determined by a logic circuit (to) when the pace control signal (si) of two corresponding transistors among the six transistors of the drive circuit (to) is high, an AND circuit circuit C The utility power (S4) is output and becomes a pace control signal for the transistor of the drive circuit (to).

@ is a rectifier circuit that converts the position detection signal (Sl) into an alternating current signal (87).
(1) and circle as the basic configuration, DC bias circuit r3
? I have been established. This DC bias circuit converts the DC voltage (a, VB) applied between the terminals into
The divided voltage is applied to the resistor C311 to shift the level of the AC signal (s y ) by t. In other words, the current signal that is the output of the shaping circuit when the DC bias circuit C3a is not present is the signal (85) shown in Figure @6, but in the case of the embodiment in which the DC bias circuit ω is provided, The AC signal (85) t-1 becomes the AC signal (87) shown in FIG. 6 whose level is shifted by the voltage (B) of the resistors (to) of the DC bias circuits e.

This AC signal (87) is input to the F/V conversion circuit (to), converted to a DC voltage according to the frequency of the AC signal (S7), and input to the 5 rotation speed control circuit C37). This circuit gain of 0 is, for example, a triangular reference voltage waveform (S8) with a minimum value of 2 volts and a maximum value of 6 volts, as shown in FIG.
When the DC voltage that is the output of the F/V conversion circuit (G) is 2 volts or less, the output of the PWM circuit (To) is a high signal (SS) without any modulation. When the voltage is greater than 2 volts, for example X volts, the output corresponding to the X volt period (7) within the triangular wave is PWM.
A signal (si) that is input to the circuit 1141 and has a duty depending on this input is output from the PWM circuit (141).

Therefore, until the output of the motor (211 is the F'/V conversion circuit (g)) reaches 2 volts, each stator coil is energized for the maximum period and rapidly reaches the predetermined rotation speed. When the rotation speed exceeds the rotation speed, PW
Under the M control, it rotates at a constant speed at the predetermined rotation speed.

And motor C! When υ is constrained, the rotational position detection signal (
81), and the clock signal in the PWM circuit (to) is superimposed on the level shift voltage (V) as a noise signal (S6), so there is no interference with the zero value line (
’@Refer to Figure 8). Therefore, there is no output from the F/V conversion circuit (to), and there is no malfunction due to the presence of the noise signal (S6). Even if the PWM circuit (to) is activated earlier than the drive circuit CD during engine start, and a noise signal (S6) is generated, the influence of the noise signal (S6) can be removed, and the motor ( 21) The starting certainty is improved compared to the conventional one. In the embodiment, the DC bias circuit c14
Accordingly, the level of the AC signal (S7) is shifted to the plus side, but the level may be shifted to the minus side.

(f) Effects of the Invention The brushless motor operation control device according to the present invention converts the rotational position signal of the magnet rotor into an alternating current signal using a regulating circuit, converts this current signal into F/V, and converts it into an output. In the operation control device for a planless motor that performs PWM control on a stator coil current using a motor, the adjustment circuit is provided with a DC bias circuit that level-shifts the AC signal, so that a rotational position signal is output. Even if a noise signal appears as the output of the adjustment circuit when the output is not set, the level is shifted, so that the frequency of this noise signal is T? /V conversion is not performed, and stable control can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional brushless motor operation control device, FIG. 182 is a rotational position signal waveform diagram, and 111! , 5
9 and 4 are output waveform diagrams of different states of the integer circuit in Fig. S1, IJ! 5 is a block diagram showing an embodiment of the brushless motor operation control device according to the present invention, '1jII6
8 and 8 are output waveform diagrams in different states of the adjustable circuit shown in FIG. 5, and FIG. 7 is a reference waveform diagram of the rotation speed control circuit. ■...Magnetic rotor, ■...Adjustable circuit, @...Stator coil, (To)...F/V conversion circuit, 0ri...
...DC bias circuit. Applicant Sanyo Electric Co., Ltd. Agent Patent Attorney Shizuo Sano

Claims (1)

[Claims] (1) A brushless motor operation control device that converts the rotational position signal of the magnet rotor into an alternating current signal in an adjustment circuit, converts this alternating current signal f:F/v, and uses the output to control the stator coil current using PWM control. An operation control device for a brushless motor, characterized in that the rectifier circuit is provided with a DC bias circuit for shifting the level of the SL multiplier signal.