JPS60220594A - 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 (a) Industrial Application Field: The present invention relates to an induction heating cooker that uses both frequency control and duty control to adjust the output during operation of the induction heating cooker.

(b) The conventional induction lrn heat cooker converts direct vAE power into alternating current rfL using a frequency conversion circuit, and flows this alternating current into an induction heating coil in the frequency conversion circuit to generate an alternating magnetic field. This is for induction heating of cooking utensils made of ferrous metal that are placed in close proximity to the ferrous metal.

In order to adjust the heating output given to cooking utensils, this type of induction heating cooker is used, for example, in Japanese Patent Publication No. 55-159.
557, it has been conventionally practiced to control the operating frequency and the tute ratio during operation of the J-type 1 wave number conversion circuit.

By the way, in order to widen the adjustment range of the output in such an induction heating cooker, a method of controlling the operating frequency and operating duty ratio 1jυ of the frequency conversion circuit at the same time has been proposed.
It has been f.

However, the operation amount S of the output operation knob and the operation of the frequency conversion circuit □ The period T of the frequency is changed in a proportional relationship as shown in Fig. 2, and the operation amount S of the output operation knob and the duty D of the operation period of the frequency conversion circuit. When is changed in a proportional relationship as shown in Figure 3,
The heating output P is approximately proportional to the square of the manipulated variable S as shown in FIG.

Therefore, when setting a high output, the output change ΔP with respect to the operation l change ΔS becomes large, which causes the problem that the output setting becomes difficult to adjust.

(c) Purpose of the Invention The invention was made in view of these points.C1
The purpose is to make the output change in response to the change in the operation amount of the output operation knob substantially constant over the entire output adjustment range.

(d) Structure of the Invention The present invention adopts a structure in which the amount of change in the output due to frequency control within the oscillation duty period is reduced as the output reaches a high output region in response to changes in the operation of the output operation means.

(B) Embodiment FIG. 1 shows a circuit diagram showing an embodiment of the induction heating cooker of the present invention, and (1) shows a DC power source (2) made by full-wave rectification of AC.
), the DC power supply (2) generates a high-frequency current at an ultrasonic frequency from the voltage;
A heating coil (3), a switching transistor (
5), this switching transistor (5) is composed of a flyholder and an diode (6) connected in antiparallel. (7) is the above switching transistor (
5') (7) By controlling ON and OFF, the above frequency Fi,
The drive circuit (8) that drives the conversion circuit (1) detects the voltage of the switching voltage switch (5) and outputs a signal when this voltage reaches a predetermined level. Detection circuit (9-pin cell) - signal receiving circuit 71-1, which acts to stop the frequency conversion circuit (1) when receiving the reset signal.

(10) shows a frequency control circuit connected to the centrifugal circuit (9) and the resonant voltage detection circuit (8), in which the current signal supplied to the heating coil (3) is detected by a current transformer ( (not shown), a first comparator (11) that can be input to the e input terminal via the terminal (S) connected to this current l lance;
1) - Output operation means (12) for setting the set signal level to the input terminal, a holding capacitor (13) for holding the average voltage of the output of this first humparator (11), and the above-mentioned reset circuit (9) A transistor (14) that discharges this holding capacitor (1), a second comparator (15) that inputs the terminal voltage of this holding capacitor (13) to its input terminal, and a Comparator (15) ■ Input terminal Fk! □ Swollen resistance (t6
) and: A time constant circuit (18) consisting of two circuits (17)
), a sostar (19) that discharges the capacitor (17) based on the signal from the resonance voltage detection circuit (8).
Consists of.

Here, the output operating means (12) -C has a characteristic that as the output is operated to the high output side, the resistance value that changes in response to the change in the manipulated variable becomes smaller, and the change in the divided voltage signal level also becomes smaller. A variable resistor, for example, a volume used for Off Ju adjustment of audio equipment, is used. (20) is the second 7J'7 valetator (15) of the resonance voltage detection circuit (8), reset circuit (9) and frequency control circuit (10).
) is a NOR gate that receives a signal from This is a small object detection circuit that performs no-load detection, and when it detects a small object, it sends 9- and 71- signals to the above-mentioned remote circuit (9) via an OR gate (22). (23) is a power transformer. (24) shows a control power supply circuit that receives AC 7AL voltage, and consists of a full-wave rectifier circuit (25), a constant voltage circuit (26) connected to this full-wave rectifier circuit (25), and an output content (27). (28) is a zero volt detection circuit connected to this power supply circuit and detects zero volts of the full-wave rectified voltage of the AC'tAL voltage.(29) is the operating state of the frequency conversion circuit (1). , a duty control 4A1 circuit that controls a duty in a stopped state, and the third
The charging resistance is controlled by the comparator (11) of
31) and discharge resistor (32).
The oscillation circuit (34) outputs the charging/discharging voltage of this capacitor (33) by charging and discharging it at a fixed period (for example, one second period), and the detection signal from the small object detection circuit (21) causes the above-mentioned The output of the oscillation circuit (34 circuit (35) for stopping the operation, all the above-mentioned one-pin circuits 34) is inputted to the e input terminal, and also from the output operation means (12) of the frequency control circuit (10). A timing circuit (37) that passes through the output of the fourth frequency converter (36) at the detection timing of the sample voltage detection circuit (28), which receives Nobuo at its input terminal. ), the flip/no flow/block circuit (38) which is set and reset by the interference from this timing circuit (37), and the output of this flip solenoid IJ tube circuit (38) is delayed and the above OR gate (22) is operated. via °C res y l-circuit (9
a delay circuit (39) for transmitting the signal to .It should be noted that the oscillation circuit (
In 34), the resistance value of the charging resistor (31) is set to be small, and the resistance value of the discharging resistor (32) is set to be large, and the time constant of discharging is ten thousand times larger than the time constant of charging the oscillating condelena (33).

Next, the operation will be explained. By turning on the power switch (not shown) of the cooker, direct current 'P1. fA (2) performs full-wave rectification of the alternating current and supplies a pulsating voltage to the frequency conversion circuit (1). At the same time, the MR circuit (23) supplies constant voltage elements Vc and -Vs to the control circuit system such as the frequency control circuit (10) and the duty control circuit (29). The oscillation circuit (34) has started to oscillate, and as shown in Figure 5, the oscillation capacitor (
33) A signal having voltage one-time characteristics that rises steeply from the terminal and rises gently in a downwardly curved state is applied to the e input terminal of the fourth comparator (36).

This comparator (36) is connected to the setting signal from the output operating means (12) transmitted to the input terminal and the oscillation circuit (36).
4) Compare the outputs, and the set signal level is higher than the oscillation circuit (3
4) Outputs "H" when higher than the output, and "L" when the opposite is true.This "H", "L" signal timing circuit (37)
is synchronized with the zero voltage of the AC full-wave rectified voltage and is also transmitted to the Frinosoff IJ knob circuit (38).The signal generated when this solid knob circuit (38) is set and reset 71- is sent to the delay circuit. (39) and is transmitted to the reset circuit (9) through the OR gate (22).

That is, in this duty control circuit 29), the oscillation circuit
34) When the output rises above the set level, the reset circuit (9) is reset, and the oscillation circuit (34) output reaches the set level.
~ When it drops below the level, the cent circuit (9) glue (・/1
- Solve 1 thread. During the short delay time in the delay circuit (39) until the reset circuit (9) is released, the discharge means (40) accumulates in the resonant capacitor (4) of the frequency conversion circuit (1). The electric charge is Ji! ! Powered up.

-'JJ, in the frequency control circuit (10), there is an input current transmitted from the current (not shown) to the end (-(S)) corresponding to the current. and the setting signal at the output operating means (12) is output to the first comparator (1
1), when the setting signal is at a higher level than the input signal, the output of this humparator (11) becomes H", and when the setting signal is lower than the human input signal, the output of this humparator (11) becomes L". Therefore, for retained condensate → J113)
A charge corresponding to the set signal level from the second output operation means (12) is charged, and as a result of this charging, the raw/4-holding capacitor (13) terminal voltage increases to the second converter tough 15.
is supplied to the e input terminal of the main unit. In addition, a transistor (19) is connected to the input terminal of this second comparator (15).
18) A time constant circuit that repeats charging and discharging cyclically by turning on and off 18): 1 → J' (17)
Terminal voltage is supplied. Furthermore, this transistor (19)
is turned ON when the resonance voltage detection circuit (8) detects that the voltage of the switching transistor (5) has become lower than a predetermined voltage. Upon receiving such a signal, the second comparator (15) turns on the switching transistor (5) when the input terminal pressure becomes lower than the θ input terminal voltage, as shown in Figure 6. Outputs an ON signal to
(2) When the input terminal voltage becomes higher than the e input terminal F voltage, an OFF signal υ- is outputted to turn off the switching transistor (5). The NOR gate (20) receives such a switching transistor (5) cl) ON, OFF signal from the frequency 1ift control circuit (lO) and the d of the frequency conversion circuit (1) from the reset circuit (9).
It responds to the FF duty, receives a set signal, and when there is no reset signal, transmits the ON and OFF signals to the drive circuit 7). Accordingly, the drive circuit
) turns the switching transistor (5) ON and OFF. That is, during the period corresponding to the duty ratio determined by the duty control circuit (29), the frequency control circuit (l
Oscillation frequency determined by O〉 / Frequency conversion circuit (1)
oscillates. In addition, when the signal is emitted from the circuit (9), the transistor (14)
The charge in the holding capacitor (13) is discharged, and the second
When a small object is detected by the small object detection circuit (21), the ON signal is no longer output from the comparator (15), this circuit (21) outputs an OR gate (2).
2) sends the detection number 1 to the reset circuit (9),
This reset circuit (9) is reset to 1~, and the oscillation operation of the frequency conversion circuit (1) is stopped in the same manner as described above. At the same time, the detection signal from the small object detection circuit (21) is transmitted to the inhibition circuit (35), which inhibits the operation of the oscillation circuit (34) and the duty control circuit (29). operation is also stopped.

The most important feature of this type of induction heating cooker is the output control means (
12) to gradually increase the set value λ level from the low output side, the holding control 1γ level will be increased as described above (i3).
) increases, the electric charge H2 supplied to the e input terminal of the second inverter (15) increases,
The period of the ON signal output from this comparator (15) becomes longer as shown in FIG. The resonant current flowing in the frequency conversion circuit (1) also increases in proportion to the increase in the length of this 01·) period. The set IM level (dashed line in Figure 5) raised by the operation of the above-mentioned output operating means (12) is the input of the 4th (7) -, 1st and 7th mirator (36) of the duty control circuit (29). This increases the oscillation period of the frequency conversion circuit (1). Conversely, when the set signal level of the output operating means (12) 1 is lowered, the resonance flowing in the frequency conversion circuit (1) increases. As the current decreases, the excavation period duty also decreases.For this reason, the output of the frequency conversion circuit (1) changes with frequency control and tutee control being separated.

By the way, the L output operation means (12) is shown in the 8th section.
As the setting output becomes higher, the amount of change in the setting signal I/H, which changes by -C in response to the change in the operation l, becomes smaller. - Therefore, when setting a high output, the holding type IF change Q between the holding terminals and the terminals changing depending on the amount of operation of the output operating means (12) also becomes small, and the set output becomes high. The switching element increases as < 5 >0';
The rate of increase in the ON period also becomes smaller.

As a result, as shown in FIG. 9, the set output increases and the frequency control means changes when looking only at the inverter oscillation duty period with respect to the operation amount of the output operation means (12). Amount of change in output due to (10) a) becomes smaller.

In addition, as shown in 5.-, as the output setting becomes higher, the level change corresponding to the manipulated variable becomes smaller.H-type setting signals are transmitted from the output operating means (12) to the dual control circuit. It is also transmitted to the (2) input terminal of the first comparator (11) in (29). Furthermore, as mentioned above, this fourth
The signal that can be input to the θ input terminal of the comparator (36) has a gradual rise and downward convex shape as shown in FIG. That is, when a high 01 force is set, the amount of change in duty with respect to a change in the set signal level becomes small. Therefore, as shown in FIG. 10, the operation amount SL of the output operation means is: r)
Change (change in Auty P with respect to 2 becomes smaller at high output setting.

Therefore, the output P adjusted by the control of both the C1 frequency control circuit (lO) and the -i knee7-i control circuit (29) is the first
As shown in country 1, the output operation means (12) IN・i′[
It is corrected so that C changes approximately in proportion to the width.

Note that the setting signal output from the output operating means (12) is T: S (7) x with respect to the operating amount S.
It suffices to use a constant that is proportional to a function that can be expressed in the form of a power (0<x<1). Specifically, the charge/discharge resistor (31:1t32) in the above-mentioned thousand knee'j-i control circuit (29>)'
:') If the values are approximately equal and the time constants of the charging and discharging of the oscillation controller (12) are equal, the J deviation +4 changes in proportion to approximately the 172nd power of the operation amount S of this operating means (12).
However, as in this embodiment, when the discharging resistor 32) is larger than the charging resistor (31) and the discharging time constant of the oscillation capacitor (33) is large, the exponent X of the above operation MS is 0
It must be set to an appropriate value within the range x〈H.

(F) Effects of the Invention As mentioned above, the induction heating cooker of the present invention uses a frequency control means to change the specific frequency within the oscillation chewing period as the set output increases, in response to changes in the operation Jj of the output operation means. Since the amount of change in the output by the control means is minimized, the synergistic effect of the two controls allows a wide range of set outputs to be obtained, and also allows the output to be adjusted in response to changes in the amount of operation of the output operation means when setting high output. The amount of change in the set output can be suppressed, making it easier to set the output at high output settings.

Provided is an induction heating cooker whose output can be easily set over a high range of i/e°C.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the induction heating cooker of the present invention, and FIGS. 2 to 4 show the oscillation period, oscillation period duty, and output of the frequency conversion circuit in the conventional cooker with respect to the operation amount of the output operation means, respectively. A relationship diagram showing changes, FIG. 5 shows the relationship between the input terminal of the main comparator of the present invention and the oscillation period duty of the frequency conversion circuit. ν waveform diagram, FIGS. 6 and 7
The figure shows the relationship between the input terminal to the parator and the ON and OFF signals to the switching resistor and the other main components of the present invention.
The waveform diagrams (not shown), Figures 8 and 9 show the output within the oscillation duty period when the output operating means according to the present invention has a setting of 4:4 with respect to the operation amount. FIG. 3 is a relationship diagram showing changes in the oscillation duty and output of the frequency conversion circuit. (1> Frequency conversion circuit, (2) DC type 11 (, (
7)... Doller f-pu circuit, 8)... Resonance electric ratio detection circuit, (9)... Reset circuit, (10)... Frequency control I
9] Road, (12) Output operation means, (23) Control power supply circuit, (28)...Zero volt detection circuit, (29)
...Duty control circuit, (33>...Oscillation: 1 ndenza, (34)' oscillation circuit. Fig. 2, 111t11, Fig. 4, upper part, P, Fig. 5, Fig. 6. Tun, Fig. 7, Fig. 8, upper part) t, (434shix+u 9th drawing 0 'f-z-4D 11th ヱ' Procedural amendment (spontaneous) November 73, 1980 1, Indication of the case 1982 Patent Application No. 77774 No. 2, Name of the invention Induction heating cooker 6, Relationship to the case of the person making the amendment Patent applicant name (188) Sanyo Electric Co., Ltd. 4, Agent address 2-18-5 Keihan Hondori, Moriguchi City, Amendment Target 0 In the specification, a column for a brief explanation of the drawings. 6. Contents of amendment 0 In the specification, page 16, line 9 is amended as follows. Figures 9, 10, and 11 are in accordance with the present invention.

Claims (1)

[Claims] (1) It has a frequency conversion circuit that generates an alternating current from a DC power supply, and the above-mentioned alternating current is passed through a heating coil in this frequency conversion circuit to avoid generating an alternating current magnetic field, and the heating coil is placed close to the heating coil. In an induction heating cooker that inductively heats cooking utensils, this cooker uses a frequency conversion circuit that generates
-Reruko! Frequency control means for changing the oscillation frequency of the ilE current, duty control means for changing the conversion operation state and stop state (4+) duty ratio of the frequency conversion circuit, and both of the frequency control means and the duty control means. Interlockingly, the surface control means such as tl are adjusted at the same time.
and an output operating means for adjusting the output, wherein as the set output increases, the frequency controlling means changes according to a change in the operating amount of the output operating means within each oscillation duty period at that time. An induction heating cooker characterized by reducing the amount of change in output.