JPH0496683A - Rotation controller for motor - Google Patents

Abstract

PURPOSE:To suppress pulsation of a motor due to ripple of power supply voltage by providing means for detecting the ripple of voltage and means for correcting the pulse width to be employed in the control of a switching means. CONSTITUTION:When the rectified and smoothed voltage outputted from a rectifying/smoothing section 10 is high or low due to the ripple of voltage, a rotation controller 1a lengthens or shortens the high level interval of a PWM signal by an amount of D2 thus lengthening or shortening the duty of the PWM signal(i.e., ON interval of a transistor Tr is shortened or lengthened). When the voltage has no ripple, high level interval of the PWM signal is held, as it is, at the value of D(i.e., 50% duty is maintained).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a rotation control device for a motor such as a DC brushless motor that is rotated by pwMIQ control of a blower, etc. The present invention relates to a motor rotation control device that can suppress motor pulsation.

[Prior art]

8l: An example of a circuit diagram of the rotation control device for the motor is shown.

This rotation control device 1 is mainly composed of a drive circuit for driving and controlling a transistor T, and a control section 2 consisting of a microcomputer CPU, etc.
, a rotation detector 4 such as a Tachozier Flake, etc., which detects the rotation speed of the motor 3; a detection signal from a position detector 6, such as a Hall element, which detects the rotation angle of, for example, an 8-pole magnetized rotor 5 of the motor 3; 7. Position detection circuit for waveform shaping. Commercial electric power tA8 is used to apply a rotating magnetic field to the rotor 5 of the motor 3.
A motor driving section 12 (an example of a switching means), which includes the transistor T, etc., which switches and applies a smoothed voltage from a rectifying and smoothing section 10 that rectifies and smoothes the voltage to the winding 11 of the motor 3, is connected.

This rotation control device 1 uses rotation control signals UVWX, Y, and Z to rotate the motor 3 at a set rotation speed.
is output from the microcomputer CPU based on the rotor position detection signal from the position detection circuit 7, and modulates the width of the pulse given to the drive circuit based on the motor rotation detection signal from the rotation detector 4. A PWM signal is output from the microcomputer CPU.

Then, the rotation control signals U, V, and W are pulse width modulated by the PWM signal via the OR circuit 14 of the control section 2 and are applied to the drive circuit D1, and the pulse width modulated U, V are applied to the drive circuit D1. , W and the rotation control signals X, Y, and Z, the drive circuit controls switching of the transistor T of the motor drive unit 12.

In this way, in this rotation control device 1 for the motor 3,
The rectified and smoothed voltage from the rectified and smoothed section 10 is pulse width modulated by the motor drive section 12 and applied to the motor 3 (
(so-called PWM control) to control the rotational torque of the motor 3.

That is, when the set rotational speed of the motor 3 is large, the ON period of the transistor T is equal to the PW as shown in FIG.
When the set rotation speed of the motor 3 is small, the ON period of the transistor T1 is shortened (that is, the duty of the PWM signal is made small). ), the rotational torque of the motor 3 is increased or decreased.

By the way, the rectifying and smoothing section 1 rectifies and smoothes the commercial power source 8.
The output smoothed voltage 1 usually includes power supply ripple fluctuations of the commercial power supply 8 and does not become a perfect DC voltage.

Therefore, the pulse width modulated voltage applied to the motor 3 by the motor drive unit 12 also includes the power supply ripple fluctuation.

[Problem to be solved by the invention]

Therefore, in the conventional motor rotation control device 1,
The power supply ripple fluctuation disturbs the rotation control function of the motor 3, resulting in a problem that the motor 3 pulsates.

Accordingly, one object of the present invention is to provide a second motor rotation control device capable of suppressing motor pulsation caused by the power supply ripple voltage fluctuation.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a motor rotation control system in which a rectified and smoothed voltage is pulse-width-modulated by a switching means and applied to the motor, and the rotation of the motor is controlled. The apparatus includes ripple detection means for detecting ripple voltage fluctuations in the rectified and smoothed voltage, and pulse width modification means for modifying a pulse width for controlling switching of the switching means based on a detection signal from the ripple detection means. The present invention is configured as a motor rotation control device characterized by:

[Operation] In this motor rotation control device, the pulse width for controlling switching of the switching means is modified by the pulse width modification means based on a detection signal from the ripple detection means for detecting ripple voltage fluctuations in the rectified and smoothed voltage.

As mentioned above, in this rotation control device, the pulse width is corrected according to the ripple voltage fluctuation of the rectified and smoothed voltage.
The rotation control function of the motor is not disturbed by the ripple voltage fluctuation.

Therefore, this rotation control device can suppress motor pulsation due to 1 ripple voltage fluctuation.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to two accompanying drawings to provide an understanding of the present invention.

The following examples are examples of embodying the present invention.
It is not intended to limit the technical scope of the present invention.

Here, FIG. 1 is a circuit diagram showing a motor rotation control device according to an embodiment of the present invention, FIG. 2 is a flowchart showing an example of rotation control processing of the rotation control device, and FIGS.
The figures are time charts showing examples of output signal waveforms of each part of the rotation control device, respectively, and Fig. 5 (al, (bl,
(C) is a time chart showing an enlarged part of the corrected PWM signal of the same rotation control device. FIG. 6 shows an example of a correction value for correcting the pulse width of the PWM signal of the same rotation control device. The list diagram, Figure 7, shows the electrical connection of the rotation control device.
It is an explanatory graph showing an example of the relationship between i-ripple fluctuation and the duty of the corrected PWM signal.

In addition, elements common to the conventional motor rotation control device shown in FIG. do.

Rotation control bag 21 of this motor 3. As shown in FIG. 1, a voltage dividing circuit 15 comprising a resistor RIR2 for detecting ripple voltage fluctuations in the rectified and smoothed voltage of the rectified and smoothed section 10 is provided at the output stage of the rectified and smoothed section 10. Additionally, a peak hold circuit 16 is connected to the control section 2 for detecting the amplitude Δ■ (FIG. 3) of the ripple voltage fluctuation based on the output voltage of the voltage dividing circuit 15.

Furthermore, in this single rotation control device, a phase detection circuit 17 that shapes the voltage waveform of the commercial power source 8 in order to detect the phase of the ripple voltage fluctuation is connected to the control section 2S.

Therefore, this rotation control device 1. Now, the above rectifying and smoothing part l
It is possible to detect the amplitude Δ■ of the 'J y pull fluctuation of the output smoothed voltage of O, and also its phase.

The peak hold circuit 16, phase detection circuit 17, etc. that realize the function of detecting the ripple voltage fluctuation of the rectified and smoothed voltage described above are examples of the ripple detection means.

In the rotation control device 11 of the motor 3, the pulse width of the PWM signal is modified as described later based on the ripple detection signals from the peak hold circuit 16 and the phase detection circuit 17, and the modified PWM signal and the U ,
Based on the V, W, X, Y, and Z signals, the rectified and smoothed voltage from the rectified and smoothed section 10 is pulse-width-modulated and applied to the motor 3, so that the rotational torque of the motor 3 is controlled.

Next, referring to FIG. 2, the rotation control device 1 for this motor 3 will be described.
．． Regarding the rotation control processing procedure of steps SL, S2.・
... will be explained in order.

Based on the rotor position detection signal from the phase detection circuit 7, the Uv, w, x, y, z for rotating the motor 3 at a set rotation speed\2 (for example, 1500 rpm)
Then, for example, a PWM signal with a duty of 50% is output, and the motor 3 starts rotating.

Then, the actual rotation speed N1 is determined based on the motor rotation detection signal from the rotation detector 4 (S1), and the difference ΔN=N2-N1 from the set rotation speed N2 is determined (S2).

Then, the set rotation speed N2 and the actual rotation speed N1 are set.
If they match and ΔN is "0" (S3), the duty of the PWM signal is not changed as in the conventional case.

For example, when the actual rotation speed N1 is 1500 rpm.

When it matches the set rotation speed N2 (1500 rpm), the duty of the PWM signal remains at 50% (high level and low level periods are both 250μ5ec) as shown in Figure 3. .

Note that the set rotation speed N2 is 12QQr.
An example of a PWM signal similar to the above when it is pm (duty is about 33.4%, that is, the period of low level output to turn on the transistor T is about 33.4%)
is shown for reference.

In addition, 5 if the actual rotation speed Nl is, for example, 1400 rpm or 1600 rpm, the set rotation speed N2 (
(S4
), the duty is, for example, 60%, as in the past.
(That is, the low level period of the PWM signal that turns on the transistor T1 is set to be <long) (S5) or 40% (S6).

In this embodiment, in S3, the duty of the PWM signal is 50% as described above (for example, as shown in FIG. 3, the high level period of the PWM signal is 250μ5ec).
We will explain the case where it is left as is.

Rotation control device 1 for this motor 3. Now, unlike before,
The duty of the PWM signal left at 50% is further modified as shown below.

That is, this rotation control device 1. Then, the peak hold circuit 16 detects the amplitude Δ■ (FIG. 3) of the ripple voltage fluctuation of the rectified and smoothed voltage of the rectified and smoothed section 10 (S
7). Furthermore, the control unit 2
[For example, the PWM signal shown in FIG.
Correction value ΔDi (i=L
2n)] is read from the same memory, and the phase of the ripple voltage fluctuation is detected by the phase detection circuit 17 (S8).

Then, based on the correction value ΔDi obtained above and the phase of the detected ripple voltage fluctuation, the above P
The high level period of the WM signal is the corrected high level period D.
i (t) (S9).

Di(t)−D+ΔD 1sin ((+)t)
・=(1) ω−2πf For example, when the frequency of the commercial power source 8 is 507, the above correction value ΔD
The high level period of the PWM signal, where i is ΔD2 shown in FIG. 6, is corrected to the corrected high level period D 2 (t) shown below.

D2ft)=D+ΔD2sin (100rt L
) -(2) The third bacterium has a duty of 5 before the above correction.
0% PWM signal, U, V, W, X,
The Y and Z signals and the output signal of the drive circuit D1 are shown.

Also, Fig. 5(a), ■1. (C) shows a part of the PWM signal corrected by (2) 2 above, and t=5mse shown in A, B, and C of FIG. 3 above, respectively.
This corresponds to the vicinity of the PWM signal of c, t=10 msec and t, -15 m5ec.

As can be seen from these figures, in this rotation control device 1, when the rectifying and smoothing voltage of the rectifying and smoothing section 10 is high (see A in Fig. 3 and Fig. 5 (a)) or low (see Fig. 3A and Fig. 5(a)) due to ripple voltage fluctuations, (See Figure 3C and Figure 5(C)),
The high-level period of the PWM signal is lengthened or shortened by ΔD2, and the duty of the PWM signal is made smaller or larger (that is, the on-period of the transistor T is shortened or lengthened).

Furthermore, when there is no ripple voltage fluctuation (see Figure 3B and Figure 5(b)), the value of D remains unchanged (that is, the duty remains 50%) during the high level period of the PWM signal. be done.

FIG. 7 shows the relationship between the above-mentioned ripple voltage fluctuation and the duty of the corrected PWM signal using a % formula. That is, in this rotation control device 11, the above-mentioned ripple voltage fluctuation is large or 1 point as shown by the solid line. As shown by the chain line, when the voltage is small, the duty of the PWM signal is adjusted to a larger or smaller width, and the duty of the PWM signal is corrected to cancel out the ripple voltage fluctuation.

As described above, this rotation control device 1. Well then.

Since the duty of the PWM signal (that is, the pulse width of the PWM signal) is corrected according to the ripple voltage fluctuation of the rectified and smoothed voltage, the rotation control function of the motor 3 is not disturbed by the ripple voltage fluctuation. 3 pulsation is suppressed.

I! modifies the pulse width of the PWM signal in response to the above-mentioned ripple voltage fluctuation. The means for realizing this function is an example of a pulse width modifying means.

Therefore, by using this rotation control device 14, it is possible to stabilize the rotation of the motor of the blower, which rotates at a low speed and where it is difficult to stabilize the amount of air blown due to ripple voltage fluctuations.

Further, since this rotation control device 11 has the above-mentioned functions, the capacitance of the capacitor C (FIG. 1) of the rectifying and smoothing section 10 can also be reduced.

〔Effect of the invention〕

According to the present invention, in a motor rotation control device in which a rectified and smoothed voltage is pulse-width-modulated by a switching means and applied to the motor, and the rotation of the motor is controlled, ripple detection means detects ripple voltage fluctuations in the rectified and smoothed voltage. and based on the detection signal from the ripple detection means,
There is provided a motor rotation control device characterized by comprising pulse width modifying means for modifying the pulse width for controlling switching of the switching means.

Therefore, with this motor rotation control device, it is possible to suppress motor pulsation due to power supply ripple voltage fluctuations.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a motor rotation control device according to an embodiment of the present invention, FIG. 2 is a flowchart showing an example of rotation control processing of the rotation control device, and FIGS. 3 and 4 are the same. A time chart showing an example of the output signal waveform of each part of the rotation control device, and FIGS. 5(a), (b), and (C) each show an enlarged part of the corrected PWM signal of the rotation control device. The time chart, Fig. 6 is a list showing an example of correction values for correcting the pulse width of the PWM signal of the rotation control device, and Fig. 7 shows the power supply ripple fluctuation of the rotation control device and the corrected PWM signal. An explanatory graph showing an example of the relationship with duty, Fig. 8 is a circuit diagram showing an example of a conventional motor rotation control device, and Fig. 9 is an on-period of the transistor T of the rotation control device and the motor rotation speed. It is an explanatory graph showing an example of the relationship. [Explanation of symbols] One... Rotation control device 2... Control section 3... Motor 10... Rectification smoothing section 12... Motor drive section 15... Voltage dividing circuit 16... Peak Hold circuit 17...phase detection circuit (switching means)

Claims (1)

[Claims] 1. A motor rotation control device in which a rectified and smoothed voltage is pulse-width-modulated by a switching means and applied to the motor, and the rotation of the motor is controlled. Based on a ripple detection means to detect and a detection signal from the ripple detection means. A rotation control device for a motor, comprising: pulse width modification means for modifying a pulse width for controlling switching of the switching means.