KR19990060406A - Output Control Circuit of Electromagnetic Induction Heating Rice Cooker - Google Patents

Abstract

The present invention relates to an output control circuit of the electromagnetic induction heating rice cooker, and more particularly, to an output control circuit that can adjust the output of the rice cooker during normal output and rapid cooking.

Output control circuit of the present invention and the heating source; Switching means for generating a switching voltage for driving said heating source by an external input voltage; A pulse width modulator for outputting a pulse signal for turning on / off the switching means; And control means for adjusting a pulse period of the pulse width modulator.

Description

Output Control Circuit of Electromagnetic Induction Heating Rice Cooker

The present invention relates to an output control circuit of the electromagnetic induction heating rice cooker, and more particularly, to an output control circuit that can adjust the output of the rice cooker during normal output and rapid cooking.

Modern is the age of multimedia. This can be defined in many aspects, but one of them is the multimedia of electric equipment. Therefore, for any electronic device, manufacturers provide various functions to consumers by adding other functions, rather than manufacturing the electronic device to have the same function of alternating current, and consumers also demand such various services.

In order to meet these demands, in addition to the cooking function and warming function of the electric induction heating rice cooker, other functions are added, such as the function of boiling porridge or samgyetang. In addition, the cooking function can be divided into cooking function by brown rice or white rice, and in each cooking function, the optimum rice taste can be realized by selecting menu.

In particular, the newly introduced electromagnetic induction heating rice cooker performs a cooking function by the way that the eddy current flows when the magnetic force generated from the coil passes through the pot and the pot itself is heated. In addition, the electronic induction heating rice cooker provides consumers with a glossy and chewy rice taste with variable pressure according to the menu and strong fire power of about 1300W and high efficiency.

Next, a brief look at the configuration of a general electromagnetic induction heating rice cooker with reference to FIG. As shown, the electromagnetic induction heating rice cooker includes a main body 4 and a cover 2 that opens and closes the main body, and an oven 5 is installed in the main body 4 so as to be accommodated therein. The working coil 8 is wound around the lower end of the oven 5, the side heater 9 is installed on the upper side of the oven 5, and the upper heater is installed inside the cover 2. have. The side heater and the upper heater are mainly operated when keeping warm, and sometimes used as an auxiliary heat source during heating.

A bottom sensor Sb is installed on the bottom of the oven 5, and a top sensor St is installed inside the cover 2. The bottom sensor Sb and the top sensor St detect temperatures of the upper and lower portions of the oven 5 during heating, and determine subsequent heating conditions based on the detected temperatures.

Looking at the basic heating principle of the induction heating rice cooker configured as described above, when a current is applied to the working coil (8) is a magnetic material oven (5) is heated by induction (induction) heating, inside the oven (5) Cooking will be done.

Next, with reference to Figure 2 looks at the heating method of the general electromagnetic induction heating rice cooker.

First, a predetermined rice and water are put into the oven 5 for cooking, and when heating is started, a soaking process is performed in which heating is performed for a predetermined time while maintaining a constant temperature (for example, about 65 ° C.). . The soaking process is performed by the working coil, and the current supplied to the working coil is periodically interrupted to maintain a constant temperature (about 65 ° C.) for a predetermined time (about 5 minutes).

After this soaking process, the process of determining the fraction is carried out. The determination of the number of water is to determine the amount (how many servings) of the rice in the oven 5 and to perform the subsequent process based on this. Unlike the soaking process, the phosphorus determination process increases the temperature in the oven while continuously supplying current to the working coil 8. The temperature change of the oven 5 is detected by the time when the top sensor St reaches the predetermined temperature. In other words, it is determined how much rice is built for cooking by the time taken for the temperature of the top sensor St to reach a predetermined temperature. Of course, this time will be determined based on the data input to the internal microprocessor.

When the top sensor St reaches a predetermined temperature, determination of the number of minutes based on the time until then is completed, and the bottom sensor Sb is brought to a constant temperature by induction heating by the working coil 8. It is up. When the determination of the number of minutes is completed, boiling process for cooking is performed from this time. In the boiling process, as the heating source, the working coil 8, the side heater 9, and the upper heater are all operated to supply heat to the oven 5.

This boiling process starts at the present temperature of the bottom sensor Sb at the time of completion of the determination of the number of minutes, and continues until the boiling target temperature at which the bottom sensor Sb is already set is reached. The boiling target temperature of the bottom sensor Sb is set differently depending on conditions such as general rice or brown rice and the number of servings determined in the above-described process. For example, in general rice, the boiling target temperature is set to about 125 ° C. When the boiling process is completed, the moxibustion process is performed.

The moxibustion process is carried out by the working coil (8), consisting of a rest period and moxibustion heating and steam discharge. In more detail, when the boiling target temperature is reached when the boiling target temperature is reached, the current is supplied to the working coil 8 to cut off the first idle process. After a predetermined time has elapsed, the current is periodically interrupted by the working coil 8 to perform primary moxibustion, and then the secondary rest and secondary moxibustion are performed again. After the secondary heating is finished, the solenoid valve 3 is driven to discharge the steam in the oven 6 to the outside, and then enters the warming process.

And the warming process is performed by the side heater (9) and the upper heater, to maintain a certain temperature (about 75 ℃) suitable for warming.

That is, the general cooking operation of the conventional induction heating rice cooker provides the optimum rice taste to the consumer by giving the proper time and the appropriate heating temperature by the soaking process, the phosphorus determination process, the boiling heating process, and the steaming process.

In addition, in the rapid cooking operation of the conventional electromagnetic induction heating rice cooker, the same time and the same heating temperature are given to each process as in the general cooking operation, but only the steaming process is omitted. Therefore, in the conventional rapid cooking operation, the steaming process that takes about 2/5 of the total cooking time is omitted in the general cooking process, and after the boiling process is completed, the process proceeds to the warming process to save time.

Therefore, the conventional electromagnetic induction heating rice cooker limits the maximum amount of heating generated by the working coil 8 to the same value whether the current cooking operation is a general cooking operation or a rapid cooking operation. Therefore, the maximum heating amount in the boiling heating section requiring the maximum heating amount is set to a constant value and a constant time, whether it is a general cooking operation or a rapid cooking operation. When the heating amount of the working coil 8 becomes a certain voltage or more, it is controlled to stop the operation to prevent the risk of fire or mechanical damage of the rice cooker.

However, when cooking in such a form is made, there is a problem that can not provide the optimal taste, such as providing unripe rice to consumers because the rapid cooking skips the moxibustion process for the taste of the whole process in the rapid process It became.

Therefore, the present invention intends to change the reference voltage according to the maximum heating amount in the general cooking operation and the rapid cooking operation. That is, the reference voltage for generating the maximum heating amount in the general cooking operation and the reference voltage for generating the maximum heating heating amount in the rapid cooking operation are set differently, and the reference voltage is changed according to what is the current cooking operation mode, It is to raise the heating amount.

Accordingly, an object of the present invention is to provide an output control circuit of an electromagnetic induction heating rice cooker capable of changing the maximum heating amount according to the selected cooking mode.

1 is a schematic cross-sectional view showing a simple configuration of a general induction heating rice cooker,

2 is an output process diagram showing a heating method of a general electromagnetic induction heating rice cooker,

3 is an output control circuit diagram of another electromagnetic induction heating rice cooker according to the present invention;

4 is a configuration diagram for controlling the operation of the fan in the present invention,

* Explanation of symbols for main parts of the drawings

2: cover 4: body

5: oven 8, 25: working coil

9: Side heater Sb: Bottom sensor

St: Top Sensor 10: Rectifier Circuit

15: smoothing circuit 20: switching unit

30: voltage limit unit 35: drive

40: PWM 45: fan

SW1, SW2, SW3: Switch C: Condenser

Q: Transistor AMP: Comparator

Output control circuit of the electromagnetic induction heating rice cooker according to the present invention for achieving the above object, a heating source; Switching means for generating a switching voltage for driving said heating source by an external input voltage; A pulse width modulator for outputting a pulse signal for turning on / off the switching means; And it characterized in that it comprises a control means for adjusting the pulse period of the pulse width modulator.

The output control circuit of the electromagnetic induction heating rice cooker of the present invention is characterized in that the reference voltage set by the voltage limiting means is set widely in the general cooking mode and the rapid cooking mode.

The output control circuit of the electromagnetic induction heating rice cooker of the present invention is characterized in that the rotational speed of the fan is set differently according to the magnitude of the reference voltage of the voltage limiting means.

The output control circuit of the electromagnetic induction heating rice cooker of the present invention is characterized in that the on / off cycle of the switching voltage supplied to the heating source is set differently in the normal cooking mode and the rapid cooking mode.

Hereinafter, an output control circuit of an electromagnetic induction heating rice cooker according to the present invention will be described in detail with reference to the accompanying drawings.

3 is an output control circuit diagram of the electromagnetic induction heating rice cooker according to the present invention, Figure 4 is a block diagram for controlling the operation of the fan in the present invention.

The output control circuit of the electromagnetic induction heating rice cooker of the present invention inputs AC power from the outside, rectifies the input power and outputs the rectifying circuit 10 and the power output from the rectifying circuit 10 to smooth the DC. A smoothing circuit 15 for converting and outputting a voltage, a working coil 25 for generating magnetic lines when power is applied, and a DC voltage output from the working coil 25 are switched on / off to switch to a high frequency voltage. And a switching unit 20 applied to the working coil 25.

That is, the switching unit 20 is configured to supply a high frequency current to the working coil 25. The switching unit 20 includes a resonance capacitor C and a transistor Q which is a switching element. It is a device to supply high frequency current to the device. That is, the capacitor (C) is connected to both ends of the switching unit 20, the transistor (Q) is connected between the base power supply and the working coil 25, the current path of the working coil 25 It is a configuration that turns on / off. Therefore, when the maximum amount of heating generated by the switching unit 20 is changed by the switching voltage of the switching unit 20 and the voltage applied to the working coil 20 is cut off, the working coil 25 is eventually turned off. It will not be heated.

And, the output control circuit of the electromagnetic induction heating rice cooker of the present invention includes a current limiting unit (30) for monitoring the voltage (Vce) between the transistor (Q) collector terminal and the emitter terminal of the switching unit 20. The current limiter 30 includes a comparator AMP for comparing the transistor voltage Vce with a reference voltage, and the reference voltage of the comparator AMP is changed in the general cooking mode by switching the switch SW2. The reference voltage 1 and the reference voltage 2 in the quick pick-up mode are selected. At this time, the reference voltage 1 will be set to about 1000 volts, the reference voltage 2 is preferably set to about 1100 volts.

The switching operation of the switch SW2 for selecting the reference voltage 1 or the reference voltage 2 of the current limiter 30 is controlled by a control unit (not shown). The controller controls the switch SW2 to select the reference voltage 1 when the cooking mode to be progressed by the external input signal input by the user is selected, and selects the reference voltage 2 when the fast cooking mode is selected. Control switch SW2.

The current limiting unit 30 sets the heating amount of the working coil 25 to the maximum heating amount when the input voltage becomes higher than the reference voltage by comparing the input voltage Vce with the reference voltage 1 or the reference voltage 2. It is determined that the value has been reached. Thereafter, the operation of the working coil 25 is controlled to stop the risk of fire or mechanical damage of the rice cooker.

The command to stop driving of the working coil 25 in the current limiting unit 30 is applied to the drive 35 that controls the driving of the switching unit 20. That is, the output control circuit of the present invention further includes a drive 35 controlling the on / off cycle of the transistor Q of the switching unit 20 to generate a driving voltage of the working coil 25. The drive 35 controls the turn-on period of the transistor Q according to a duty value applied by the pulse pole modulator 40 to be described later. That is, the working coil 25 is driven by the high frequency voltage generated by the duty value. The drive 35 stops the on / off operation of the transistor Q when a stop command is applied from the current limiter 30.

The output control circuit of the present invention includes a pulse width modulator 40 for outputting a pulse width signal for controlling the turn-on time of the working coil 25. The pulse width modulator 40 further includes a switching device SW3 that selects the reference duty as 1 or the reference duty 2 according to the general cooking mode or the rapid cooking mode under the control of a controller (not shown). Therefore, in the general cooking mode, the reference duty 1 is set so that power up to 1300W may be output from the working coil 25, and in the quick cooking mode, the reference may be outputted up to 1600W from the working coil 25. Duty 2 is set. The reference duty 1 is preferably about 25 ms, and the reference duty 2 is preferably about 30 ms.

That is, the output control circuit of the electromagnetic induction heating rice cooker of the present invention controls the output voltage of the working coil 25 to be increased by about 10% when the cooking mode to be advanced is the rapid cooking mode. In addition, when the input voltage of the working coil 25 is sensed and exceeds the specified voltage, the limiting voltage of the voltage limiting unit 30 for stopping the operation of the working coil 25 is also increased by 10% so that an operation problem does not occur. have.

In addition, in the output control circuit of the electromagnetic induction heating rice cooker of the present invention, as shown in Fig. 4, the rotation speed of the fan motor 45 is set differently in the normal cooking mode and the rapid cooking mode. That is, in the rapid cooking mode, the rotation speed of the fan motor 45 is increased to operate in a strong airflow than in the normal cooking mode. The reference rotational speed setting of the fan motor 45 is also made by a controller (not shown). In the general cooking mode, the reference speed 1 is selected, and in the rapid cooking mode, the reference speed 2 is selected by the switching element SW1.

Next will be described the operation of the output control circuit of the electromagnetic induction heating rice cooker according to the present invention having the above configuration.

First, the controller (not shown) determines whether the current mode to be progressed is the general cooking mode or the rapid cooking mode based on the external input signal selected by the user.

Therefore, when the mode selected by the user is the general cooking mode, the switch SW1 for setting the rotational speed of the fan motor 45, the switch SW3 for setting the voltage for generating the maximum driving voltage of the working coil 25, Then, the switch SW2 for setting the voltage for monitoring the input voltage of the working coil 25 is set to the existing one. In addition, when the user-selected mode is the rapid cooking mode, all of the switches SW1, SW2, and SW3 are set to reference 2 (currently shown in FIG. 3).

As described above, the AC power input from the outside is rectified and output through the rectifier circuit 10 while the initial operation is set in the normal cooking mode or the rapid cooking mode, and this voltage passes through the smoothing circuit 15. Is output.

The DC voltage output from the smoothing circuit 15 is applied to the working coil 25 through the switching unit 20, wherein the transistor Q turn-on / off cycle of the switching unit 20 is a pulse width modulator. It is adjusted by the pulse width output from 40. In the general cooking mode, the pulse width modulator 40 outputs a pulse signal having an on / off period of 25 ms, and in the rapid cooking mode, a pulse signal having an on / off period of 30 ms is output. .

The pulse signal output from the pulse width modulator 40 is applied to the gate terminal of the transistor Q through the drive 35, and at this time, the transistor Q is turned on or turned off by the applied pulse signal. While repeating, switch the input power to output high frequency voltage. At this time, the output high frequency voltage drives the working coil 25. Therefore, when the rapid cooking mode is selected, the high frequency voltage generated by switching by the 30 kHz pulse width becomes about 10% higher than the high frequency voltage generated by switching by the 25 kHz pulse width in the general cooking mode.

Meanwhile, the voltage Vce of the transistor Q is input to the comparator AMP of the current limiter 30. The comparator AMP will compare the input voltage Vce with the reference voltage 1 (about 1000 volts) in the normal cooking mode, and compare the input voltage Vce with the reference voltage 2 (about 1100 volts) in the fast cooking mode. When the input voltage is higher than the specified voltage, the control signal for stopping the driving of the working coil 25 is output.

At this time, the stop signal output from the current limiting unit 30 is applied to the drive 35, the drive 35 of the switching unit 20 for generating a driving voltage of the working coil 25 by the stop signal Turn off the operation.

That is, the current limiting unit 30 monitors overheating of the working coil 25 by the reference voltage 1 in the general cooking mode, and monitors overheating of the working coil 25 by the reference voltage 2 in the rapid cooking mode. do. Therefore, when the output voltage of the working coil 25 is increased in the rapid cooking mode, the malfunction of the operation by the current limiting unit 30 is prevented from occurring.

In addition, when the user selects the rapid cooking mode, the heating amount generated by the working coil 25 becomes higher than in the general cooking mode. Therefore, the rotational speed of the fan motor 45 for cooling the overheating of the working coil 25 is also higher than in the general cooking mode to operate in a strong air flow. That is, the reference speed 1 of the fan motor 45 selected in the normal cooking mode is set lower than the reference speed 2 of the fan motor selected in the quick cooking mode.

Although not shown, when the user selects the rapid cooking mode, it is preferable that the controller (not shown) displays the turbo output on the liquid crystal display (not shown) under control.

Therefore, the present invention sets the maximum heating amount generated in the working coil 25 in the general cooking mode and the rapid cooking mode differently. That is, in the rapid cooking mode, the maximum heating amount is increased by about 10% than in the normal cooking mode, and thus the process according to the cooking operation is progressed to speed up the progress time. In addition, the reference voltage for monitoring the overheating of the working coil 25 is also increased by about 10% so that there is no abnormality in the operation of the system.

As described above, the output control circuit of the electromagnetic induction heating rice cooker according to the present invention sets the output amount of the working coil differently in the normal cooking mode and the rapid cooking mode. Therefore, in the fast cooking mode, the cooking operation proceeds to the same process as each process in the normal cooking mode, but the cooking is made within the fast time desired by the user by allowing each processing time to reach faster than the processing time in the general cooking mode. There is an advantage that can provide the best taste while cooking.

Claims (7)

A heating source; Drive means for driving the heating source; External signal input means for outputting a signal according to the quick cooking mode or the normal cooking mode; And And an output control circuit of the electromagnetic induction heating rice cooker comprising a control means for adjusting the output voltage of the driving means by the external input signal. According to claim 1, The drive means; Switching means for generating a switching voltage for driving said heating source by an external input voltage; And a pulse width modulator for outputting a pulse signal for turning on / off the switching means. The method of claim 2, And a voltage limiting means for monitoring the switching voltage of the switching means by the reference voltage set by the control means, and controlling the output of the switching means. The method according to any one of claims 1 to 3, Output control circuit of the electromagnetic induction heating rice cooker further comprises a fan motor rotated at the rotational speed set by the control means. A heating source; Switching means for generating a switching voltage for driving said heating source by an external input voltage; A pulse width modulator for outputting a pulse signal for turning on / off the switching means; And Output control circuit of the electromagnetic induction heating rice cooker comprising a control means for adjusting the pulse period of the pulse width modulator. The method of claim 5, Output control circuit of the electromagnetic induction heating rice cooker further comprises a fan motor rotated at the rotational speed set by the control means. The method according to claim 1 or 2, And a voltage limiting means for monitoring the switching voltage of the switching means by the reference voltage set by the control means and controlling the output of the switching means.