JPS58130796A - Inverter device - Google Patents

Abstract

PURPOSE:To reduce noise which is produced from an AC motor by simultaneously operating a power reactor and a power inverter to control so as not to increase the high frequency component applied to the motor over the desired value. CONSTITUTION:When an output frequency is set by a speed instruction unit 8, a higher DC bus voltage is controlled by a power reactor controller 5. A PWM control signal 61 becomes the signal of the value which is matched to the voltage applied to a driven motor 4, the output voltage is detected to PWM-control a power inverter 3 so that the output voltage becomes a target value. When thus controlled, the peak value of the output voltage can be lowered, thereby improving the conductivity of the PWM control.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention consists of a controllable electric valve,
c An inverter device that drives the motive machine at a desired rotational speed! The purpose is to reduce the noise generated from the Kamikiden eJ Iso.

Generally, in order to drive an AC motor at variable speed with an inverter device, the voltage applied to the motor, that is, the output voltage of the inverter device, must change its frequency while keeping the relationship between its output frequency F and output voltage V constant. In this way, the optimum vl can be obtained.

Conventionally, PAM (PulseMψ11
Added M flute button function; pulse amplitude modulation) method 8
Fig. 1 shows the output voltage waveform of the PAM method, and Fig. 2 shows the output voltage waveform of the PWM method.

The PWM method performs full-wave rectification of the AC hexagonal power supply, converts the constant voltage DC power smoothed by a capacitor into the desired AC power by an inverter using a controllable electric valve, and at the same time converts the desired output frequency within one cycle to a very high level. It opens and closes at a high frequency to control the output voltage, and has frequency components such as the voltage spectrum shown in Figure 4. Also, P.A.
In the M method, the DC voltage is variably controlled by a forward converter, and the inverse converter only opens and closes a controllable electric valve to obtain the desired frequency, but does not perform a cheating operation. Therefore, harmonic components contained in the output voltage are The voltage spectrum is shown in FIG. 8.

By the way, the chirotsuba frequency in the PWM method is usually 1
．． OK) K to several KHz is often selected, and this harmonic component is added to the driven motor, becomes an excitation force, becomes the most unpleasant electromagnetic sound, and increases the noise generated from the motor. In this way, the PWM method starts from the driven motor
Although this method has the disadvantage of generating high voltage, since the output voltage is controlled by a very high-frequency cheat wave operation, the output voltage follows well when the output frequency is changed, making it possible to create a system with good responsiveness.

On the other hand, the PAM method generally uses a method to obtain a variable DC voltage by controlling the phase of a forward converter, and because a large capacity capacitor is connected for smoothing, the followability of the output voltage when changing the output frequency is poor. However, it has the disadvantage that it cannot be used in systems that require immediate response.

This invention was made in order to solve the above-mentioned drawbacks of the conventional inverter device, which suppresses electromagnetic noise generated from a driven motor, and provides an inverter device with good quick response. be.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, (1) is an AC power supply, (2) is a variable voltage forward converter using a phase controller, etc., and (3) is an inverter that can be controlled by PWM. The drive motor (4) is driven. (8) is a continuous character setting device, and the command value set by this speed setting device (8) is sent to the forward converter control signal 61) and the PWM control signal υ by the command divider (7). and each forward converter fltl1m
(5) and the PWM controller (6). At this time, the forward converter control signal phrase) is distributed so that it is higher than the DC bus voltage when operating in the PAM method, and the PW
The M control signal 1i is subjected to C fraction e to match the target output voltage.

Next, the operation of this device will be explained.

When the output frequency is set by the speed command device (8), the DC bus voltage is controlled to be higher by the forward converter controller (5). The PWM control signal - is a signal whose value corresponds to the voltage applied to the driven motor (4), and it detects the output voltage and controls the inverter (3) so that the output voltage reaches the target value.
WM control.

By controlling in this way, the peak value of the output voltage can be reduced to a low F, and the conductivity of PWM control can be improved.
As shown in Figure 6, this device is capable of reducing the harmonic content of the frequency component of the chip, reducing the noise generated from the motor, and maintaining the responsiveness of the control system. Effective at low frequencies below the vicinity.

As described above, the present invention includes a forward converter that outputs a variable voltage and an inverse converter that outputs a variable voltage variable frequency by 331 width modulation, and allows the forward converter and the inverse converter to act simultaneously. Therefore, the high frequency component applied to the AC motor is controlled so as not to increase beyond a desired value.

This has the effect of reducing noise generated from the electric motor.

[Brief explanation of the drawing]

1 to 4 are for explaining conventional inverter devices, and FIG. 1 is a graph showing the output voltage waveform of an inverter using the PAM method. Fig. 2 is a graph showing the output voltage waveform of an inverter using the PWM method, Fig. 8 is a graph showing the output voltage smoothing according to the PAM method, and Fig. 4 is a graph showing the output voltage spectrum I using the PWM method. FIG. Fifth
5 and 6 are for explaining one embodiment of the present invention, respectively. FIG. 5 is a block diagram showing an inverter device, and FIG. 6 is a graph diagram showing output voltage variation. In the figure, (1) is an AC power supply, (2) is a variable voltage progressive Pica, (3) is a u P WM inverse converter, (4) is
! AC tvJ machine, (5) is forward converter controller, (6) is P
WM controller, (7) is a command distributor, and (8) is a speed command device. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Procedural amendment (Liao II) Mr. Commissioner of the Japan Patent Office 1, Indication of the case Patent application Sho P7-779gff2
, Name of the invention Inverter device 3, Person making the amendment (contact number: 03 (213) 3421 Patent Department) 5, Subject of the amendment (1) Drawing 6, Contents of the amendment (1) Figures 3 and 4 of the drawing and Figure 6 is corrected as shown in the attached sheet. Figure 3, Figure 4, Figure 6

Claims (1)

[Claims] Controllable °...; In an inverter device that is equipped with a forward converter and an inverse converter consisting of a copying valve, and drives the electric motor at variable speed by changing the output voltage and output frequency for the motor, the above! llI! The converter is a converter that outputs a variable voltage, and the inverse converter is a converter that outputs a variable voltage and variable frequency by means of bias width modulation. An inverter 1L characterized by controlling the high frequency component applied to the i[@II machine so as not to increase beyond a predetermined value by operating the inverter 1L.