JPS5812285A - Induction heating cooking device - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to induction heating cooking, and more specifically, the present invention relates to induction heating cooking. Regarding induction heating cooking, which starts from a low input state, then decreases the frequency and increases the input, while at the same time stabilizing it at an appropriate frequency value for running in all directions, which is set according to the type of load. .

In an induction heating cooker that employs an on/off control method in which the inverter repeatedly oscillates and stops at an appropriate rate during this period, for example, 1 second is 1 cycle V, the input adjustment is as follows: 1.2. --9'; Move the slide lever of the slide switch marked with a scale of 10. For example, if the position of the slide lever is "5", the high frequency inverter 1 circuit will run for 1.0.5 seconds. The oscillation continues and then stops for the next 0.5 seconds. Repeat this and input 509
Get 6.

In this way, from "1", that is, input 10%, to "10
” In other words, it can be adjusted linearly with input 100961. e
In the case of , the oscillation waste wave number of the inverter circuit is set to a constant value, and usually that value is a value that provides a maximum input of, for example, 1300W.

In an induction heating cooker with such an operation method, a startup sound is generated when the inverter circuit starts oscillating. When the on/off control period is 1 second, this occurs every second, so it becomes an annoying noise when the user is busy. Cooking pots made of several types of materials, such as stainless steel, have a high power input.For example, if an enameled pot is set to receive an input of 110W, if you place the above special steel on it, it will produce approximately 1800W
There is a problem in that the input of the switch destroys the input switch I switching element that constitutes the inverter circuit. The origin of f-zero is
In addition to adding an input compensation function to prevent such input fluctuations due to differences in load materials and obtain a stable input value, when the oscillation of the inverter #circuit starts, the oscillation IIJll wave number is kept high, but it is By starting from the input state and increasing the input by gradually lowering the frequency to a predetermined value, the above-mentioned noise generation can also be prevented.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In Figure 1, (1) is the power supply terminal into which the alternating current power supply for helmets is input, (:) is the rectifier circuit consisting of a diode r pull V, (8) is the check coil, and (4) is the , filter capacitor, flat? Since there is almost no II effect, a pulsating voltage produced by full-wave rectification of alternating current appears at that terminal.

(6) A conductive heating coil, (6) is this coil (s
) The resonant capacitor (7) connected in series is a switching element connected in parallel with the resonant capacitor (6), and a gate control switch (hereinafter abbreviated as GC8) is used. (a) #i, GOS (IK) tL, anti-parallel MK connected diodes), and the circuit shown by the dotted line in the figure constitutes a high frequency invert # circuit.

(b) is a cooking pot made of iron-based metal. ttaV
oon is the terminal voltage of the line μm capacitor (4), and the voltage of several volts generated in the constant voltage power supply circuit is applied via the diode so, and the rectifier circuit ( 2) Only near Ov of the pulsating waveform voltage from 2), the number of man-hours V
Draw the waveform raised to a constant voltage of 1/%A, vo
csti, GO8ff) f) 7/-F terminal voltage 0
The ring is a GO8 drive circuit that applies an on or on pulse to the gate of the GOS (?) and causes the high frequency inverter circuit to oscillate at a predetermined oscillation frequency, for example, about 25 KHz.The on pulse is a positive signal, and the on pulse is a negative signal. Output. Alternatively, it is possible to generate an on-pulse in this drive circuit 04.
This is an off-pulse generation circuit that operates to generate on-pulses in both cases, and both generate high-frequency pulses of approximately 251 Hg. The inverter is an on/off control circuit that outputs an on signal and an off signal that determine the oscillation period and stop period of the high frequency inverter circuit (2). oI is a slide switch that changes the ratio of the oscillation continuation period and stop period, the ring is a starting circuit that emits an inverter circuit starting signal in synchronization with the oscillation start signal from the on/off control circuit (b), and - is a rectifier circuit. ) The current flowing through the AC power supply twin in the previous stage is detected by the current lance and ring. This is an input compensation circuit that operates to reduce the load "bO" when

FIG. 2 shows a specific circuit of the main part of the present invention.

The on-pulse generation circuit consists of a 2-even Nant's gate @-, a flip g1 flow 111, a Nant's gate, and a comparator.
A starting signal emitted from the starting wheel is input to the Nant gate wheel via an inverter, and its output is given to the drive circuit as a GCSCS scene pulse. A voltage Vcon is input to one terminal of the Nant gate, and a voltage VGC8 is input to the θ side signal input terminal.

' The off-pulse generation circuit has a time constant consisting of a comparison #@% resistor and a capacitor 4! [Circuit ■, which controls the charging and discharging of this time constant circuit) run is inserted in parallel to the time constant circuit axis of 5 steps # (2), resistor @@ and capacitor), and capacitor ■. The output of the time constant circuit axis is input to the e-side base weight input terminal of the comparative remote control, which includes the series circuit of the resistor (2) and the transistor (above), and the transistor so that controls opening and closing of the run sister, and the e-side signal input. The output of the time constant circuit is given to the terminal, and the output is input to the Nant Gate@. ) The Run Sister is controlled to open and close by the output of the Nandt gate (2). The transistor I- is made conductive by an on signal issued from the on/off control circuit (b), and is closed by an off signal.

The transistor (2) has the collector output of the F-Tungister wheel added to its base, and is in an off state when the transistor is on #a, and is in an on state when the transistor (2) is in an off state. The resistor, conductor 1411) and diode constitute an initial state setting circuit, the output of which is input to the Nantes gate (support).

The input compensation circuit includes a comparator, and the input current detected by the current transformer mK is inputted to the third side signal input terminal after being converted to a DC voltage via the rectifier circuit and the smoothing capacitor. A reference voltage adjusted by dividing the constant voltage culm with a resistor is applied to the e-side reference input terminal of this comparator, and its output is sent to the off-pair A/A via the resistor. given to the time constant circuit axis in the pulse generation circuit (to),
Change the time constant.

Next, the operation of the above configuration will be explained based on FIGS. 5 and 6.

Immediately after the power is turned on, the output of the initial state setting circuit changes from the L (low) state to the H (high) state after a predetermined time delay. Since the output is H, the inputs of the four Nant gates are H, H, L,
The inputs of the Nando game M1 are H, H, H.

When an on signal is output from the on/off control circuit (2) and a start signal is output from the start circuit at the same time, the start signal causes the inverter output to increase (Nando game) (2) output changes to HK), and the drive circuit. An on-pulse is input to rJ4 to start oscillation. GC from this! 5(f) K gate on signal is added. (by L conversion of Nantes gate output)
, NAND game) 4 output is HKfJ), transistor ■
cut off. Condan as a result? A current of charge flows through the resistor (2), and the pressure of the charge increases, causing Pep to rise. When this voltage level p reaches the reference voltage level p on the e side of the comparator, the output of the comparator II goes from H to LKI', and from this, the output of the Nant gate 4 changes from L to H, and again. The output of the gate changes from H to L. As a result, the drive circuit axis outputs a negative signal to GOf3 to turn off 008(n).
(1>t)'l-). GC8 (f) be done. When the voltage vecs drops by 1 near Ov, the comparator (2) output changes from L to H. The H-level signal of Nant is converted into a pulse by a capacitor and inputted to the Nant gate shaft as an H-level on-pulse. Therefore, the input to the Nant gate axis is H, H%, so the output is L.P The output of the Nant gate axis is changed from L to H.

The driving surface wr so provides the KjEO signal to turn on the GO811. This kind of on-on pulse K] High frequency in/--#
The circuit trout continues to oscillate while the ON signal is being issued from the beginning of the ON/OFF control circuit.

Subsequently, when the ON signal from the ON/OFF control circuit is cut off, the output of the Nant gate shaft is fixed at H level A/,
Nantes gate (2) output 4t LK is fixed. As a result, oscillation of the high frequency inverter circuit is prohibited.

Next, the λ force adjustment function will be explained. The period from when GC8ffl is turned on until it is turned off is due to the time constant I.
It is determined by the time constant of the k circuit and the e-side reference Vpefi/ of the comparator. When the on/off control circuit is emitting an off signal, the transistor ■ is off, therefore F hun vX
-1 is on, so is the resistance Is conductive? It will be connected in parallel to @, and the output rep of the time constant circuit - will be determined by the resistor -〇1@@-. Let Inaiko-Pep be VLI. When the on/off control circuit 4 changes to the on signal, the F langis I@ turns on, the transistor □ sister turns off, and the resistor □ becomes in the ON state. As a result, the output level of the time constant circuit is determined by the resistor s11@axis and becomes a value 4 higher than the previous value. Let's call this level the V Seal.

An on signal is issued from the on/off control circuit (b), and the above voltage level is directly connected to the resistor@m@m and capacitor t.
The voltage level μVLI is calculated by dividing the time constant determined by llllK by 4.
gradually changes from to Vm. The above time constant is approximately 595w5c
That's about it. From this, at the start of one oscillation, e@reference Vbeμ of the comparison separation is vL lepeμ, so the comparator - changes from H to L.
The time to change to υ, that is, the off-pulse output time, is early.
However, the oscillation frequency of the inverter # circuit increases and the input supplied to the load decreases.The input gradually increases from this low input state, and after about 50 cycles, a steady oscillation state is reached. I wonder. Figure 4 shows the on signal and the reference level 4VLt.
, which shows the relationship between V and summer.'
KH! However, when the above-mentioned adjustment function works, the initial frequency of oscillation starts at 55 KHk, and then decreases and becomes constant at about 1 in 25.

Next, the operation of the human power compensation circuit (2) will be explained. When the input current rises above a predetermined value, the current transformer IIK senses that the large input current μ exceeds the e-side base rate level of the comparator, and its output changes from H-bh to LK. 251. The e-side base level of the comparator is a low level Vbs determined by the resistor @ axis 1, and the output timing of the off pulse output from the comparator (2) is advanced and the inverter! The oscillation frequency of the circuit increases, and therefore the input to the load decreases.
As shown in FIG. 5, the operating period is around the beater value of the power supply voltage VQOn, and changes depending on the input difference depending on the type of cooking pot.

Figure 6 shows the signal waveform of the comparator e-side reference pin N when both the input adjustment functions of the input compensation circuit and the off-pulse generation circuit operate, and for reference, the case where only the input adjustment function operates. (dotted line waveform), input compensation circuit (2)
In this case, when both are working, after the oscillation starts, the input adjustment function is first activated, starting from a high frequency state U < low input state, and gradually increasing As the frequency decreases (input increases) and reaches the frequency set by the input compensation circuit @, this frequency K11lli is maintained thereafter, the input is made constant, and any further excessive human power supply is prevented.

- To give an example from a dormitory experience, if a stainless steel pot is placed on a cooker that is adjusted to input about 1300W (at this time frequency of 25KHz) to the enamel pot, the conventional power consumption would be about 1800W.
The input of W is input, but due to the function of the input compensation circuit (K), the frequency is increased to 1 in 29, and this frequency value is approximately 1.
Compatible with 300WK. When the input adjustment function operates simultaneously with such an input compensation circuit, the oscillation frequency initially starts from 1 at 53, then gradually decreases and stabilizes at about 29 K.

Starting from a state where the input is lowered, it gradually increases to the steady oscillation frequency or, if the input compensation circuit is in operation, it is guaranteed to match the set frequency, so depending on the material of the pot. Therefore, the input power does not fluctuate, and a stable input can always be made. (9) The generation of undesirable noise at intervals of about 1 second, which conventionally occurs at the start of oscillation, is also prevented. 1. The low input period at the beginning of oscillation is a short period of several tens of wams, so there is no risk of the total input decreasing.
``Providing an input compensation circuit has been known in the past, but such an input compensation circuit detects the current flowing at that time by applying human power to the load.'' Therefore, there is no guarantee that a large current will flow once. However, according to the present invention, at the initial stage of oscillation, the input is started from a low input state, and then the input compensation circuit operates.

Such problems never occur.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a main circuit diagram, and FIGS. 3 to 6 are signal waveform diagrams for explaining the operation. )...High frequency inverter circuit, 0←...
Drive circuit, (A) -...On/(Luss generation time B, O groan-...Off pulse generation circuit, first......On/off control circuit, Ql--Start circuit, (2 )...-Human power compensation circuit. Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 6 O□

Claims (1)

[Claims] 1. A series circuit of an induction heating coil and a resonant capacitor, including a switching element connected in parallel with the above resonant capacitor? A high-frequency inverter circuit, the above-mentioned switching element, a switching element pivot circuit that applies high-frequency on/off pulses to the circuit and causes it to oscillate, an on-pulse generation circuit that provides a signal to turn on the switching element to the skeleton drive circuit, and a switching element for the above-mentioned drive circuit. an off-pulse generation circuit that provides a signal to turn off the high-frequency inverter circuit, an on/off control circuit that performs input control by varying the ratio of the oscillation period and stop period of the high-frequency inverter circuit, and an on/off control circuit that detects the input current to the high-frequency inverter circuit and It is equipped with an input compensation circuit that determines the input to the inverter and controls the oscillation frequency of the high frequency inverter circuit in order to keep this input constant regardless of the material and size of the load, and the off-pulse generating circuit controls the on/off control. It is provided with an input adjustment function that advances the off-pulse generation timing only at the beginning of the generation of the on-signal output from the control circuit, raises the oscillation frequency of the high-frequency inverter circuit, and then dissipates the frequency (1k), and the above. An induction heating controller characterized in that the frequency after extinction is configured to match the oscillation frequency set by the input compensation circuit.