JPS6081789A - Electromagnetic induction heater - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (a) Industrial application field The present invention is directed to a tortoise-magnetic induction heating device with a load detection function.
Regarding.

(b) In conventional technology (2), in magnetic induction heating equipment, the load placed on the heating coil that generates an alternating magnetic field becomes part of the load in the circuit of the electromagnetic induction heating equipment. The operating state of the circuit changes greatly depending on the quality, shape, etc., and depending on the load, overcurrent may flow and circuit elements may fail, or operating the device with no load may waste power. .

For this reason, the operating state of the circuit is detected and the device is operated and heated only when an appropriate load is placed, and when the load is inappropriate or there is no load, the device is stopped operating and heating is stopped. The situation is disturbing.

(c) Purpose The present invention has been made in view of the above-mentioned points, and provides an electromagnetic induction heating device equipped with a load detection function.

B) Structure of the Invention The present invention provides a direct current coil (3), a switching element (4), which is connected in parallel between the source (2), and an induction heating coil (3), a switching element (4), and the switching element (4), respectively. A also varies depending on the load of the high frequency inverter circuit (1) consisting of a resonant capacitor (5) and a damper diode (6).
Heating coil (3) K flowing current IL d■L/dt=0
At point A, the voltage between the terminals of the resonant capacitor (5) is =
By detecting point B where the value becomes 0, and electrically detecting the time lag between these pixels A and H, it is determined whether the load is suitable or unsuitable.If the load is unsuitable, the high frequency inverter circuit f1 ) is configured to stop the operation.

(E) Embodiment An embodiment of the present invention will be explained based on the drawings. Figure 1 is a circuit diagram of a high frequency inverter circuit H, in which an induction heating coil (3) and a switching element (4) are connected in series between a DC power source (2), and each switching element (4) is Resonant capacitor (5) and damper diode (6) in parallel
) are connected. In addition, (the force is f]).

Figure 2 shows the product frequency inverter circuit (1) shown in Figure 1.
In the equivalent circuit, the inductance L of the induction heating coil (3) when a load is applied to the induction heating coil (3).

The resistance R is illustrated with equal constraints.

FIG. 3 is a diagram showing the values of inductance L and resistance H of the induction heating coil (3) for various loads, and FIG. 4 is a diagram showing the operation of the high frequency inverter circuit (1) shown in FIG. 1 for various loads. FIG.

FIG. 5 is a diagram showing an embodiment of the electromagnetic induction heating device according to the present invention, in which (1) is a high frequency inverter circuit, (7) is a load, and (8) is a drive that sends drive pulses to the high frequency inverter circuit H. circuit, (9) is a flip-flop circuit, (1
0) is a release circuit that issues a reset signal to the flip-flop circuit (9). Note that (1) is a diode.

Then, α1) detects the point A of the induction heating coil (3) vc flowing current ■, where d1L/old=0, and the voltage signal V
1 (tz is the reference level v, ly
A comparator that compares r + with the voltage No. 43 ■ from the differentiator 01), (13) is the % between the terminals of the resonant capacitor (5): I-T: vc and the voltage No. 43 ■, □ from the differentiator 01). A comparator that compares, (1a) is a comparison? It is a pulse generator that generates a pulse at point B when the output from the output end of the resonant capacitor (5) reaches a high level VC/, that is, when the voltage across the terminals of the resonant capacitor (5) becomes VC=OK. (1
5) is a NAND circuit, and (16) is a diode.

The operation of the electromagnetic induction heating device according to the present invention W having the above configuration will be described. The high frequency inverter circuit (
The operating waveform of 1) is as shown in Fig. 4, but when the force is appropriate, the output from the output terminal of the load (comparator 02, as shown in Fig. 6 (a) Ic not shown) is Since the high level region and the pulse 2 from the pulse generator (161) do not overlap, the output from the NAND circuit (161) remains at a high level and the flip-flop circuit (9) is not set.

Therefore, the diode (1) of the flip-flop circuit (9)
The side 61 is at a high level, and the drive pulse from the drive circuit (8) is output to the high frequency inverter circuit (1), so that the inverter circuit (1) continues to operate.

If the load (7) is unsuitable, the output V! from the output terminal of the comparator (12) as shown in FIG.
' is high level and 7. area and pulse generator (
14) Since the 11 pulses are 11, a NAND circuit (
1! The output from Il becomes low level and the flip-flop circuit (9) is sent to the flip-flop circuit (9).
diode (IrillllI becomes low level).

Therefore, the Wakimachi pulse from the drive circuit (8) is not output to the inverter circuit (1), and the inverter circuit (1) does not continue to operate.

(f) Effects As described above, the electromagnetic induction heating device according to the present invention has the operating waveform of the high frequency inverter circuit (1), that is, the current flowing through the induction heating coil (3). , and resonant capacitor (5)
The voltage between the terminals of ■. Changes due to the presence or absence of load (7), particle quality, shape, etc. are detected. In other words, the load (if the force is appropriate, it will flow to the induction heating coil (3)? 11. Flow ■).

Point A and the resonant capacitor (5) where dIL/d of is 20
The voltage between the terminals of ■ Point B, which is c-0, is -q (If they do not match, the inverter circuit (1) continues to operate, and if the load (7) is inappropriate, these should match -10. This causes the operation of the inverter circuit (1) to be stopped.

Therefore, the present invention provides a simple circuit with τ11. With training guidance, 1. This is to realize the GL West.

[Brief explanation of the drawing]

Figure 1 is the circuit diagram of the high frequency inverter circuit, Figure 2 is the circuit diagram of the high frequency inverter circuit.
Figure 3 is a diagram showing the inductance and resistance values of the induction heating coil for various loads. Figure 4 is an operating waveform diagram of the high frequency inverter circuit shown in Figure 1 for various loads. , FIG. 5 is a diagram showing an embodiment of the electromagnetic induction heating device according to the present invention, and FIG. 6 is an operation waveform chart of the high frequency inverter circuit when the load is suitable and unsuitable. (1)...High frequency inverter circuit, (3)...Induction heating coil, (5)...Resonant capacitor. Figure 36 (a) Direct + 'i Physical Jutsu Unai・1・i～member

Claims (1)

[Claims] m dIL/ of the current II flowing through the induction heating coil of a high-frequency inverter circuit consisting of an induction heating coil connected in series between a DC power source, a switching element, a resonant capacitor, and a damper diode connected in parallel to the switching element, respectively. By detecting the point where dt=0 and the point where the voltage between the terminals of the resonant capacitor becomes VC20, and electrically detecting the time tj9 deviation of these image points, it is possible to determine whether the load is suitable or not. In the case of a suitable load, the operation of the inverter circuit is stopped. ! ! I-device.