JPH0352562A - Composite induction heating power device - Google Patents

Abstract

PURPOSE:To produce power capable of changing over frequency during the operation at a low cost by preparing only a set of power supplies having maximum frequency necessary for heating, combining them with a cyclo converter to control, and generating free required frequency. CONSTITUTION:Maximum frequency (f) necessary for heating is generated by a high frequency power supply 1. A heat coil 5 is connected to the high frequency power supply 1 through a cyclo converter 6 and, at the same time, matching capacitors 4a and 4b are connected. The cyclo converter 6 is such that thyristor switches S11 and S12 are connected to feeders l1 and l2 in series and that thyristor switches S21 and S22 and intersected with the feeders l1 and l2 to connect, the ignition of the thyristor switches is controlled by a control section which is not illustrated, and the maximum frequency (f) is kept as it is or reduced to supply to the heat coil 5. Simultaneously, a switch S3 of the matching capacitor 4a is also changed-over. According to the constitution, frequency can be changed over during the operation.

Description

[Detailed Description of the Invention] A. INDUSTRIAL APPLICATION FIELD The present invention relates to a composite induction heating power supply device that is effective for use in an induction heating device.

B7 Summary of the Invention The present invention provides an induction heating power supply device that supplies power at a predetermined frequency from an AC power source to a heating coil, which uses a cycloconverter as a frequency control means to be supplied to the heating coil, thereby achieving low cost and high performance. Get an efficient power supply.

C. In conventional induction heating, it may be necessary to repeatedly heat the object by changing the frequency depending on the shape of the object to be heated, such as during hardening.

When heating with several different frequencies, a power source for each frequency is generally used. For example, 2 of lOKHz and lKHz
When heating at different frequencies, as shown in Figure 5,
Prepare 10KHz and IKHz power supplies and use them by switching with a SIRISK switch.

Figure 5 shows an example of a conventional composite induction heating power supply device, in which 1 is a 10KHz power supply, 2 is an IKHz power supply, and Sl
-83 is a thyrisk switch formed by connecting thyristors 3 in antiparallel, 4a and 4b are matching capacitors, and 5 is a heating coil, which are connected as shown in the figure.

D. Problems to be Solved by the Invention Conventional power supplies require as many power supplies as the number of frequency types required for heating, making the power supply expensive and requiring a down period due to the time it takes to start the inverter when switching. This required a reduction in operating efficiency.

The present invention solves the above-mentioned problems, and its purpose is to:
An object of the present invention is to provide a composite induction heating power supply device that is inexpensive and has high operational efficiency by effectively utilizing a cycloconverter.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a heating power supply device that supplies power at a predetermined frequency from an AC power source to a heating coil. A composite induction heating power supply device is constructed using a cycloconverter as a frequency control means.

F. For the working power source, only one type of power source with the highest frequency required for heating is prepared, and the frequency is varied by combining it with a cycloconverter. That is, the high frequency power supply set (1) is combined with a cycloconverter, and the output frequency is arbitrarily switched by controlling the cycloconverter. In addition, the matching capacitor is switched in conjunction with a si-risk switch in response to the frequency switching of the power supply.

G. EXAMPLES Examples of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 2 shows a schematic configuration of a composite induction heating power supply device according to an embodiment of the present invention, and the same members or corresponding parts as those in FIG. 5 are given the same reference numerals.

In the current device shown in FIG. 2, the power source is, for example, 10
A KHz power source 1 is used, a cycloconverter 6 is connected to the power source 1, a heating coil 5 is connected to the cycloconverter 1, and matching capacitors 4a and 4b are connected. In addition, the matching capacitor 4a is connected to the cycloconverter 6 via the cycloconverter 2c.

As shown in FIG. 1, the cycloconverter 6 includes cycloswitches Sll, SI2, S21 . The sirisk switch Sll is connected to one terminal 1a of the power supply I.
and one terminal 5a of the heating coil 5.

The thyrisk switch S12 is connected between the other terminal tb of the power source 1 and the other terminal 5b of the heating coil 5.

Further, the SIRISK switch S21 is connected between the connection point J1 between the power supply terminal 1a and the SIRISK switch Sll, and the connection point J2 between the SIRISK switch Sll, the SIRISK switch S12, and the matching capacitor 4a. The thyrisk switch S22 is connected between the connection point J3 between the thyrisk switch Sll and the thyrisk switch S3 and the connection point J4 between the power supply terminal 1b and the thyrisk switch SI2.

Thyristor Sll, SI2. S22 and S3 are the third
As shown in FIG. 3(A), two thyristors 3 may be connected in antiparallel to each other, and as shown in FIG. 3(B), one
It may also be configured by connecting several thyristors 3.

In the composite induction heating power supply device having the above configuration, the cycloconverter 6 only needs to multiply the frequency, as shown in FIG.
) FIG. 41(B) shows the operating waveform when the fundamental frequency is reduced to unity.

10 Heating coil 5 from power supply 1 through cycloconverter 6
In order to supply a current having a current waveform as shown in FIG. 4(B), the following operation is performed.

(1) Turn on the sirisk switches Sll and SI2,
No current is passed through the heating coil 5 in the direction shown by the arrow AI in the loop of power supply I→Sirisk switch Sll→heating coil 5 and current R1.

(2) Turn on the sirisk switches S22 and S21,
A current is caused to flow through the heating coil 5 in the direction of arrow AI in the loop of power supply l - thyrisk switch S22 -> connection point J3 - heating coil 5 - connection point J2 - thyrisk switch S21 - power supply 1.

(3) Turn on the sirisk switches S12 and Sll,
A current is passed through the heating coil 5 in the direction of arrow A2 in the loop of power supply 1 → Cyrisk switch S12 → heating coil 5 → Cyrisk switch Sll → power supply 1.

(4) Turn on the cyrisk switches S21 and S22,
Power supply l - Cyrisk switch S2 + = connection point J2 - heating coil 5 - connection point J3 → Cylisk switch S22 → connection point J4 → power supply l loop, arrow A2 to heating coil 5
A current is passed in the direction shown.

The output frequency can be changed by changing the periods of the above items (1) to (4). Furthermore, when changing the frequency, it is necessary to switch the matching capacitors 4a and 4b at the same time, so the matching capacitor changeover switch S3 is switched at the same time.

H. Effects of the Invention The present invention is as described above, and by using a simple cycloconverter, one type of power source can be used by switching to any frequency. That is, it is possible to obtain an inexpensive induction heating power supply device for combined heating of different frequencies. Further, frequency switching can be reduced to any value that is an integral multiple, and is particularly effective for multistage frequency switching. Furthermore, since frequency switching can be performed continuously during power supply operation, it is optimal for applications where short-term heating switching is repeated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a composite induction heating power supply device according to an embodiment of the present invention, FIG. 2 is a schematic structural diagram of the device of FIG. 1,
Figure 3 (A) is a wiring diagram showing an example of the configuration of the Cyrisk switch, Figure 3 (B) is a wiring diagram showing another example of the configuration of the Cyrisk switch, and Figure 4 (A) is the basic current waveform of the power supply. Figure 4 (B) is a current waveform diagram supplied to the heating coil, Figure 5
The figure is a block diagram showing a schematic configuration of a conventional composite induction heating power supply device. ■...Power supply, 3...Sirisk, 4a, 4b...
Matching capacitor, 5... Heating coil, 6... Cyclo converter, 7... Diode, Sll, Sl2, S21
, S3...Sirisk switch. 2 other people Old Figure 1 High Frequency IIS 4a. 4b Matching condenser 5...Heating coil Fig. 2 Fig. 3 (A) (B) 3 Fig. 4 1 Fig. 5 Conventional example 4b

Claims (1)

[Claims] (1) A heating power supply device that supplies power at a predetermined frequency to a heating coil from an AC power supply, characterized in that a cycloconverter is used as a power frequency control means for obtaining a predetermined frequency to be supplied to the heating coil. Induction heating power supply.