JPS5854748B2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impark device capable of high frequency operation.

In recent years, induction heating devices using inverter devices have come to be used for industrial heating.

This induction heating device is often used to heat a relatively surface layer of a member to be heated.

It is known that in order to heat the surface layer of the member to be heated, if the operating frequency of the impark device is set to a high frequency, it becomes possible to heat only the surface layer of the member.

However, the conventional impark device could only operate up to an operating frequency of about 3 KHz due to the characteristics of the semiconductor element (Silisk).

For this reason, it has been difficult to operate the induction heating device at high frequencies.

As a means to solve this problem, a time-sharing inverter device was developed, but this device uses semiconductor elements (SIRISK).
The disadvantage is that an extremely large number of

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an impark device capable of operating a load at high frequencies.

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

FIG. 1 is a circuit diagram of an embodiment of the present invention, in which 1 is a forward converter, and an electrolytic capacitor is connected between the positive and negative outputs of this forward converter 1.
are connected according to the polarity shown.

3 is a commutation reactor, one end of which is connected to the positive output end of the forward conversion device 1, and the other end is connected to the anode side of the first thyristor 4.

The cathode side of this first cylisk 4 is connected to the first cylisk 4 connected in series. It is connected to one end of the second commutating capacitors 5a and 5b, and the other end is connected to the negative output end of the forward converter 1.

6 is a second thyristor, and the anode side of this second thyristor 6 is connected to the cathode side of the first thyristor 4.

The cathode side of the second thyristor 6 is the first inductor 7
It is connected to one end of the load 8 via.

The other end of the load 8 is connected to a common connection point 9 between the first and second commutating capacitors 5a and 5b.

10 is a third thyristor, and the anode side of this third thyristor 10 is connected to a common connection point 12 between the first inductance 7 and the load 8 via a second inductance 11.

The cathode side of the third thyristor 10 is connected to the negative output terminal of the forward conversion device 1.

13.14 is the 1st. These diodes 13 and 14 are diodes for charging the second commutating capacitors 5a and 5b to (E-ΔE) volts as described later. It is connected to the third thyristor 6.10 according to the illustrated polarity.

Next, the operation of the above embodiment will be described with reference to FIG.

Assume now that the electrolytic capacitor 2 is charged to E volts as shown in the polarity.

Here, when the first thyristor 4 is fired by a firing signal from a firing circuit (not shown), the voltage E volts of the electrolytic capacitor 2 is influenced by the commutating reactor 3 and the first thyristor 4 is turned on. The second commutating capacitors 5a and 5b are each charged to a voltage of E volts.

That is, 1st. Between the second commutation capacitor 5a and Sb is +
Charged to 2E volts.

Mode 1 in FIG. 2 is a waveform showing a state in which the first commutating capacitor 5a is charged.

Next, when the second thyristor 6 is ignited, the charge in the first commutating capacitor 5a is discharged as indicated by an arrow 15 in the figure.

This discharge flow passes through the load 8 and the first commutating capacitor 5
a is charged with the opposite polarity to the polarity shown, but the diode 13
Therefore, the charged voltage charges the first commutating capacitor 5a again as shown in the polarity shown.

The charging voltage at this time suffers from a △E volt loss due to power being supplied to the load 8 etc. (mode 2 in Figure 2), and the charging voltage of the first commutating capacitor 5a becomes E-△E. Become a bolt.

In addition, in FIG. 2, ST is the period during which the inverter is not operating, +e se + i is the voltage of the load 8,
Indicates current.

After the end of this rest period ST, when the third cylisk 10 is ignited, the charge in the second commutation capacitor 5b is discharged as shown by the arrow 16 in the figure.

This discharge flow passes through the load 8 and the second commutating capacitor 5
b is charged to a polarity opposite to that shown, but the voltage charged by the diode 14 charges the second commutation capacitor 5b again with the polarity shown.

At this time, the charge voltage suffers a loss as described above, and the second
The charging voltage of the commutating capacitor 5b becomes E-ΔE volts.

When the third thyristor 10 is ignited, the polarity when the charge of the second commutation capacitor 5b is discharged through the load 8 is determined by the second thyristor 6 as shown in mode 3 in FIG. The polarity is opposite to that in the case of ignition.

Thereafter, the inverter is operated repeatedly in the order of modes 1, 2, and pause 3.

As described above, the first thyristor 4 is
However, the load 8 can operate at a frequency three times that of the first thyristor 4.

That is, the commutation margin time of the first thyristor 4 is expressed as a percentage of the period determined by the load frequency, and the commutation margin time of the second thyristor 6 is expressed as T6 shown in FIG. 2, the commutation margin time of the third thyristor 10. becomes TIO in the same figure.

Therefore, sufficient commutation time is provided for a considerable high frequency impark device, and high frequency induction heating of the load becomes possible.

As described above, according to the present invention, since an inverter can be configured with at least three control switching elements, it is possible to simplify the circuit, thereby improving the reliability of the circuit. .

Further, according to the present invention, the load can operate at a frequency three times the operating frequency of the first control switching element, so if the operating frequency of the switching element is set to 3 KHz, the load operates at 9 KHz, and the induction heating device This is a very convenient advantage.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram for explaining one embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the above embodiment. 1... Forward conversion device, 2... Electrolytic capacitor, 3... Commutation reactor, 4...
1st Cyrisk, 5a, 5b... 1st. 2nd commutation capacitor, 6°10...2nd. 3rd silicon risk, 8...Load, 13.14...Diode.

Claims (1)

[Claims] 1 A charging element connected between the positive and negative outputs of the forward conversion device,
a first control switching element connected to the positive side of the charging element via a commutation reactor; and a first control switching element connected between the first control switching element and the load of the charging element for igniting the first control switching element. The charge of the charging element is discharged, and the series-connected first. A series circuit of a second commutating capacitor, and a second commutating capacitor connected in the forward direction in parallel with this series circuit. a third control switching element; diodes connected to each of the third control switching elements separately and in antiparallel to each element; It is connected to the common connection point of the third control switching element and the midpoint of the series circuit of the capacitors, and when the second control switching element is ignited, the discharge current of the first commutation capacitor flows and the third control switching element When ignited, the discharge current of the second commutation capacitor flows into the first commutating capacitor.
An inverter device comprising a load inserted in an electrical circuit that flows in the opposite direction to the discharge current of a commutating capacitor.