JPS5812578A - Inverter device - Google Patents

Abstract

PURPOSE:To stably continue the operation of an inverter device even when an AC power source is instantaneously interrupted by supplying the charged energy of a condenser to a self-excited inverter when the AC power source is instantaneously interrupted. CONSTITUTION:When an AC power source 10 is normal, the power supply to a load 18 is performed through a variable DC converter 12, a smoothing circuit 14 and a self-excited inverter 16. At this time, a capacitor 34 is charged from the power source 10 to a constant voltage through a diode rectifier 36 and a resistor 38 in an instantaneous power interruption compensating circuit 30. When the power source 10 is instantaneously interrupted, the power supply to the inverter 16 and the load 18 is switched from the power source 10 side to the compensating circuit 30.

Description

[Detailed Description of the Invention] The present invention relates to an inverter device that converts power from an AC power source to AC power of another frequency, and in particular, is capable of continuing stable operation even in the event of a momentary power outage of the AC power source. Regarding inverter equipment equipped with instantaneous power failure compensator'
There is C.

This type of inverter device is widely used in the field of variable speed control of AC motors. First, when this type of inverter device is composed of many thyristors,
Generally, due to a short power outage of the AC power source (referred to as a momentary power outage), the inverter device itself will fail in commutation, and the inverter device will not be able to continue operating even if the AC power source is subsequently powered on. Therefore, when such an inverter device is used in a winding twin in a delicate industry, the threads are cut and the operation is stopped.

From this point of view, conventional inverter devices of this type are provided with an instantaneous power failure compensation circuit. FIG. 1 shows an inverter device to which a conventional instantaneous power failure compensation circuit is added.

That is, in FIG. 1, reference numeral 10 indicates an AC power source;
/J is a variable DC converter, /4t is a smoothing circuit, /bu is a self-excited inverter, and it is a load. A momentary power failure compensation circuit-2 is installed in the DC intermediate circuit of the inverter circuit configured in this way.
Connect 0 and get nine. In addition, the conventional instantaneous power failure compensation circuit KO.

It consists of a capacitor J- and a diode connected in series, and a resistor JA connected in parallel with the diode. in this way! In the conventional inverter device, when the AC power supply 10 is in a normal state, the self-excited inverter /4 is operated by the power supplied from the AC power supply IO through the variable DC converter l and the smoothing circuit NO. .

For example, AC power is supplied to load /I of an AC motor section.

Note that when the load/1 is an AC motor, in order to control its speed, p frequency control is performed by the self-excited inverter 74,
A variable DC converter controls the terminal voltage in proportion to the frequency.

On the other hand, in the instantaneous power failure compensation circuit Ko0, the capacitor JJ is charged with the substantially self-excited inverter/4ol input voltage value Vdot via the resistor Ko4.

In such a state, if a momentary power outage occurs in the AC power supply IO, the self-excited inverter 14 will no longer be able to operate with the power from the AC power supply IQ.

At this time, the capacitor of the instantaneous power failure compensation circuit KO, 22
is charged with a predetermined energy, and this charged energy is discharged via the diode. Therefore, due to the operation of such instantaneous power failure compensation circuit -〇,
Self-excited inverter/1 and load it can continue to operate even during a power outage period of AC power supply 10.

Although not shown in the drawings, it is assumed that the control circuit of the inverter device is configured to be able to continue stable operation at all times even in the event of a momentary power outage of the AC power supply 10.

However, in the inverter device, when the AC motor is set to negative IFJ/r, the output frequency and output voltage of the automatic inverter /j are controlled for the purpose of controlling the speed of the AC motor. That is, in the inverter device shown in FIG. 1, the output voltage of the inverter is controlled by controlling the DC input voltage vdo of the i1 excitation inverter/J. So, for example, when an AC motor is operated at low speed,
The DC input voltage Vda of the automatic inverter l is the motor speed f.
The voltage is low corresponding to K.

As a result, the capacitor Jλ constituting the 1.14 o'clock power failure compensation circuit O is charged to a low voltage. By the way, the amount of energy charged in the capacitor JJ is proportional to the square of the charging pressure, so when the motor is operated at low speed, the charging energy of the capacitor JJ becomes extremely low. Therefore, in such a photoelectric state of the capacitor t-1, if a momentary power outage occurs in the AC power source IO, the capacitor t-1 will supply energy for a sufficient time compared to when the AC motor is operated at ^ speed. As a result, the operating time of the self-excited inverter due to the charging energy becomes considerably shorter. In other words, the lower the speed of the AC motor being operated, the more this phenomenon becomes more serious. Such problems can be solved, for example, by increasing the capacity of the capacitor, but this has the disadvantage of making the device uneconomical.

Therefore, the inventor of the present invention has conducted extensive studies in order to overcome all the problems of the conventional instantaneous power outage compensation system described above, and as a result, has found that A capacitor is charged with the highest electrical energy through a DC current converter and a resistor, and the charging energy of this capacitor is transferred to a self-excited inverter and load via a DC-DC converter when there is a momentary power outage in the AC power supply. Better to discharge as proper DC input power.

We have found a method that can solve the above problems.

Accordingly, an object of the present invention is to provide an inverter device equipped with an instantaneous power failure compensation circuit that has a simple configuration, can be manufactured at low cost, and can achieve economical operation by increasing the utilization rate of the capacitor. .

In order to achieve the above object, the present invention provides a variable voltage inverter device including a variable direct current converter, a smoothing circuit, and a self-excited inverter, which rectifies AC power source power and charges it with predetermined electrical energy. The present invention is characterized in that it is provided with a momentary power failure compensation circuit that supplies charging energy of the capacitor to a self-excited inverter when an AC power source experiences a momentary power failure.

In the inverter device described in M, the time a power failure compensation circuit is as follows:
A diode rectifier connected to an AC power supply and this luxury t1
1t, @'iI and directly connected to 1j with good resistance! I
A series circuit consisting of a resistor and a resistor is composed of a capacitor connected to the Pil K, and a DC-DC converter connected between the terminals of this capacitor and connected to the power input terminal of the self-excited inverter. It is suitable if In this case, it is preferable to configure the DC-vILflt converter with a single transistor transistor.

Further, it is preferable that the DC-DC converter is configured to operate based on a detection output signal of a detector that detects a momentary power outage of AC power m.

Next, an example of an inverter device according to the present invention! ,
A detailed description will be given below with reference to the accompanying drawings. For convenience of explanation, the same reference numerals are given to the same components as those of the conventional device shown in FIG. 1, and detailed explanation thereof will be omitted.

FIG. J is a circuit diagram showing an actual inverter device srs according to the present invention. In other words, in one real nine example circuit,
The basic configuration of the inverter device is completely the same as the conventional device. However, in one aspect of the present invention, the instantaneous power failure compensation circuit 30 connected to the DC intermediate circuit of the inverter device is improved. In other words, in one practical example,
DC-DC conversion for DC intermediate circuit of inverter equipment! +J
λ is connected, and Contin-9'71 is connected to this DC-DC converter JJ.

This capacitor 34I- is connected to the AC power supply 10, and a series circuit of nine diodes 1lfi circuit 74 and a resistor Jt is connected in parallel.

Next, the operation of the inverter device according to the present invention constructed as described above will be explained in detail.

First, when the AC power supply IQ is normal, power is supplied to the load it via the variable DC converter/co, the smoothing circuit 14I-, and the self-excited inverter/j. At this time, in the instantaneous power failure compensation circuit 30, the capacitor tJ da is
is charged to a constant voltage vdaoK through a diode rectifier J1 and a resistor Jl. The DC-DC converter JJ is in a stopped state when the AC power supply io is normal. In this case, the DC-DC converter J[lambda] is preferably a highly efficient and economical converter such as one transistor, for example, one transistor.

Next, when a 10K11 hour power outage occurs in the AC power supply 1, the power supply to the automatic inverter 11 and the load 11 is switched from the AC power supply 10@ to the In time power outage compensation circuit JO.

That is, a momentary power outage of the AC power supply ioo is detected by a power outage detection unit (not shown), and the operation of the DC-DC converter 153- is started based on the output signal of this detector. At this time, DC-DC converter J operates to generate a DC output voltage that allows automatic inverter /4 and load /I to operate stably. 1E, the DC output voltage of this DC-DC converter J- is generally the voltage of the self-excited inverter 7 immediately before a power outage.
It is selected so that the DC input voltage value is equal to 4. However, depending on the wait of the load/l, it is preferable to control the DC voltage so that it becomes the optimum DC voltage for continued operation of the load.

In this way, the automatic inverter 14 and the load /102111! by the instantaneous power failure compensation circuit 10! In the switching state, when the AC power supply IO is restored normally, the power supply to the self-excited inverter /l and the load it is resumed from the AC power supply 10I111.
It's done well. At the same time, the DC-DC converter 3.2 stops operating.

As is clear from the embodiments described above, according to the present invention,
Charging of the capacitor that makes up the instantaneous power failure compensation circuit 1! The voltage is always constant regardless of the operating state of the inverter device, and the maximum charging energy can be 118 tons, so the capacitor can be used most economically. Furthermore, by using a capable power transistor as a power semiconductor element, the DC-DC converter can be manufactured at low cost, and the entire inverter device can be constructed economically. The inverter device of the present invention is smaller and more economical than conventional devices. Therefore, the inverter device of the present invention is suitable for use in applications that require stable operation of winding lines in the textile industry, for example. It can be applied very effectively.

Although the preferred embodiment of the present invention has been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 91 is a circuit diagram of an inverter device equipped with a conventional instantaneous power failure compensation circuit, and FIG. 1 is a circuit diagram showing an embodiment of the inverter device according to the present invention.

Claims (4)

[Claims] (1) In a variable frequency variable voltage inverter device equipped with a variable DC converter, a smoothing circuit, and a self-excited inverter,
It has a capacitor that rectifies AC power and charges it with a predetermined amount of electrical energy. An inverter device comprising a momentary power failure compensation circuit that supplies charging energy of the capacitor to an automatic inverter when an AC power source experiences a momentary power failure. (2) 4? In the inverter device according to claim sg1, the instantaneous power failure compensation circuit includes a diode rectifier connected to an AC power supply, a resistor connected in series with the rectifier, and a circuit connected in parallel to the series circuit of the rectifier and the resistor. An inverter device consisting of a nine capacitor connected to the capacitor, and a DC-DC converter connected between the terminals of the capacitor and a DC power input terminal of a self-excited inverter. (3) The inverter device according to claim 1, wherein the DC-DC converter of the instantaneous power outage compensation circuit is constituted by a transistor square collar. (4) In the device described in the claim WA 菖子评dan or 菖薖J, the drift-to-DC converter of the instantaneous power failure compensation circuit is capable of handling this state when there is a momentary power failure in the AC power supply. An inverter device configured to operate based on a detection output signal of a detector.