JPS59103581A - Voltage/current type variable frequency inverter device - Google Patents

Abstract

PURPOSE:To stabilize the operation of an inverter device by connecting the output terminal of a converter to the input terminal of a lattice type filter, and connecting the output terminal of the filter to the input terminal of the inverter, thereby fully utilizing the both characteristics of a voltage type inverter and a current type inverter. CONSTITUTION:The output terminal of a converter 2 is connected to the input terminal of a lattice type filter which is composed of two reactors 3, 4 and two capacitors 5, 6, and the output terminal of this filter is connected to the input terminal of an inverter 7. According to this configuration, the terminal voltage becomes constant even under the abrupt load variation condition, and the circuit operation is stabilized even under the load opening and shortcircuiting conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inverter for supplying power to an inverter.

In recent years, with the advancement of power electronics technology,
Variable frequency inverter circuits have also been developed, but conventional inverter circuits include current-type inverters, which have a single actuator inserted in the DC circuit, and voltage-type inverters, which have one capacitor inserted in parallel with the DC circuit. Current-type inverters have the disadvantage of generating high voltage in the reactor when the load is opened, damaging circuit elements, while voltage-type inverters have the disadvantage of causing large current to flow and damaging circuit elements when the load is short-circuited. At the same time, current type inverters have constant current characteristics (1'1), and voltage type inverters have only constant voltage characteristics and cannot meet the demands of diversifying loads.

The present invention has characteristics and stability not found in conventional inverters In the embodiment of the present invention shown in FIG. 1, 1 is a three-phase AC power supply, and 2 is a thyrisk bridge converter, which is not necessarily a thyristor but may be a diode. Actors 3 and 4 have the same value, and both actors may be combined or may be individual actors that are not combined. 5 and 6 are conancers having the same value, and constitute a 3.4-ply actor and a lattice type filter. 7 is a three-phase inverter, tiger 'j'
; Written in Suk Inhak, it may also be Luka, Thyristor, or GTO Inverk.

Second, the function of Innopark may be PWM1 180° conduction type and 120° conduction type. 8 is an induction motor as an example of a load, but it may be a stationary load.

A characteristic example of the present invention will be explained in detail using the equivalent circuit shown in FIG. The compaq is isometrically replaced by a series circuit of the DC output voltage Es and the sirisk i' h. The impark and its load during steady operation are replaced by a resistor R''. In a steady state, the power supply current S is the reactor current L m = load current j-1. Capacitor c1
, C2 has been fully charged to Es with positive polarity on the ・ mark side,
There is no current flowing through the capacitor.

Figure 3 shows an equivalent circuit when the load resistance R' suddenly changes to R (R<R-), and at that moment, the reactor current or unchanged, the current Act of the capacitors C1 and C2, and the current C2 flow.j
-c, = Act, so Figure 3 becomes an easy-to-understand equivalent circuit of Figure 4, and the terminal voltage of both capacitors is
, e"t toss'-) t resistance R niha, eC+ +eC
Even if a voltage of t E+', Es is applied and the load changes suddenly, the terminal voltage hardly changes.

Figure 5 shows the equivalent circuit at the moment when the load is released from R''(R'-(capital)), and Figure 6 is a revised version of Figure 5 to make it easier to understand.k・-Lc, = ic・, and electric W:
(Current i 3 = L c · C · -2) · A current twice the load current before opening instantly flows into the power supply, but when the magnetic energy of reactors L+ and Lz disappears,
Engineering C. and Lc2 also disappear.

Figure 7 shows an equivalent circuit when the load is short-circuited, and the short-circuit current for both capacitors is <ic・→-ic, ) = 24 m, and at the moment of short circuit, a current that is twice the load current before short circuit flows. , thereafter, the oscillating current is multiplied by i. this period,
Power supply current js does not flow. If the gate of the sirisk Th (in the actual circuit, each sirisk of the converter) is turned off, even a permanent short circuit in the load will not affect the power supply. Leave the gate of Cyrisk Th on,
When ec1= ec, = Es/2, at that moment,
/LC・-1C・-〇, and the power supply current, Zs =, j
A short circuit current of n· will flow and increase rapidly. Follow-C1
Since the period of the power supply current χmiO in FIG. 8 is equal to 0, if the gate pulse of the SIRISK is removed during that period, damage to the circuit elements can be easily prevented even if the load is short-circuited.

As explained in the above-mentioned circuit, sudden load change 1
1! i is constructed with an impark device that has excellent features such as constant terminal voltage and stable circuit operation even when the load is open or short-circuited. , S''Vctor L・,L・
It is sufficient to increase the capacitor C., 'C2 to a relatively small capacity IJH, :. In order to strengthen the voltage type impark characteristic, it is sufficient to increase the capacitance of CI and C2 and to set Ll and L2 to relatively small values.

The voltage/current type variable frequency impark device of the present invention exhibits excellent functions as a speed control power source for induction motors, and at the same time exhibits extremely stable operation. It has advantages.

[Brief explanation of drawings]

Figure 1 is a circuit configuration diagram of the present invention, where 1 indicates the three-phase AC market condition, 2
is Cyrisk Converk, 3 and 1 are reactors, 5
and 6 are capacitors, 3 to 6 axle and capacitor constitute a lattice type filter, 7 is an inverter, and 8 is an induction motor as a load example. Figure 2 is the equivalent circuit of Figure 1, Figure 3 is the equivalent circuit when the load suddenly changes (R'→R), Figure 4 is the equivalent circuit expanded from Figure 3, and Figure 5 is the sudden load release (R
'→(3))11? The equivalent circuit of i, Fig. 6 is an expansion of Fig. 5 for easy understanding, and Fig. 7 shows the sudden load short circuit (R'
-= O) An equivalent circuit of lk5. FIG. 8 shows an equivalent circuit during a period when the power supply current does not flow during a short circuit, and FIG. 9 shows an equivalent circuit when the power supply current starts flowing during a short circuit. Figure 1 M Figure 2 Figure 3 L? Figure 4 2 Figure 5 1 Figure 6 Procedures Amendment 3. Person making the amendment 5, subject of amendment Application and specification

Claims (1)

[Claims] Connect the output terminal of the converter to the input terminal of a lattice type filter consisting of two glue handles and two capacitors, and connect the output terminal of the filter to the input terminal of the impark to obtain voltage type impark and current. A voltage/current type variable frequency impark device that takes advantage of both characteristics of type impark and operates stably.