JP2783073B2 - Pot detection device for induction heating rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pot detecting device for detecting the presence or absence of a pot when starting an induction heating rice cooker utilizing induction heating.

[0002]

2. Description of the Related Art A conventional pot detecting device for an induction heating rice cooker will be described with reference to FIG. A filter 3 is connected to a DC output terminal of a rectifier circuit 2 that converts an AC voltage of the AC power supply 1 into a DC voltage, and shapes the output waveform.
The resonance circuit 4 includes a heating coil 5 and a resonance capacitor 6. A switching element 7 for generating a resonance current is connected to the resonance circuit 4. The switching element 7 is on / off controlled by the control means 8. Reference numeral 9 denotes level conversion means for level-converting the voltage between both ends of the filter 3 to a voltage of 5 V or less. The under-hold means 15 is means for holding the lowest voltage of the output of the level conversion means 9. Reference numeral 10 denotes ZVP generating means for detecting 0 volts of the AC power supply 1 and outputting a detection pulse. The output of the ZVP generating means 10 is connected to a delay means 14 for delaying this output pulse by several hundred microseconds. Numeral 11 indicates that if the voltage of the under-hold means 15 when the detection pulse of the delay means 14 is output falls below a certain voltage, it is determined that the pan is present, and if not, it is determined that there is no pan, and the result is output to the control means 8. This is a determination means. The judging means 11 and the control means 8 are configured in the microprocessor means 12, and the judgment and control are constituted by program judgment and program control. 16 is Vce
Level exchange means, 17 is peak hold means, 18 is V
The ce voltage measuring means 19 is a Vce limiter means.

The operation of the apparatus for detecting a pot in an induction heating rice cooker constructed as described above will be described below.
AC 100 V supplied by the AC power supply 1 is converted to DC by the rectifier circuit 2 and the filter 3 and supplied to the heating coil 5. The detection of the presence or absence of the pot 13 is usually performed before the heat retention or the rice cooking and when the reservation timer for the rice cooking is set. That is, this is to inform the user that the user has inadvertently forgot to set the pot 13 when instructing heat retention, cooking, and the like. In addition, the pot detection is always performed even during operations such as cooking and keeping warm. This is to stop the operation of the induction heating rice cooker immediately if the user removes the pot from the induction heating rice cooker for any reason, so as not to break the circuit. .

[0004] Pot detection at the time of starting heating of the induction heating rice cooker is as follows. Normally, when the specified power is applied to the pan 13, the start-up of the applied power is delayed, so that
Start from about 00 or 300W to specified power, ZV
Each time a P pulse is generated, the control means 8 controls so that the power gradually increases. As a result, the minimum output voltages of the rectifier circuit 2 and the filter 3 gradually decrease from the time of startup until the specified power is applied, and become the lowest when the specified power is reached. When the power supply voltage is not set to the pan 13, the impedance of the resonance circuit 4 increases, the resonance current is a small current, and the output voltages of the rectifier circuit 2 and the filter 3 change when the voltage of the AC power supply is near 0V. The output voltage waveform of the rectifier circuit greatly differs depending on the presence or absence of the pan 2.

[0005] The detection of the presence or absence of the pot at the time of starting is such that the detection of the pot is started after a certain period of time from the start, for example, after 32 ZVP. After the zero volt pulse is output, the presence or absence of the pan is determined after a lapse of a predetermined time, for example, 300 μsec, and the determination is performed 15 times each time zero volt is generated. Is determined. Otherwise, it is determined that there is no pot.

[0006]

However, in the above configuration, the time from the start to the start of the detection of the presence or absence of the pot is constant, and the output voltage of the rectifier circuit is reduced while the output voltage of the rectifier circuit is decreasing. In order to start pot detection after the stabilization time has elapsed, a problem arises in that a false determination of pot presence detection is made due to fluctuations in power supply voltage or the like. In addition, if the time from startup to the start of presence / absence detection is increased to prevent erroneous determinations, the heating will be performed without the pan, so that the switching element will be burdened and the switching element will be destroyed. Occur.

The present invention solves the above-mentioned problems of the conventional configuration, and provides a pot detection device for an induction heating rice cooker that can reliably determine the presence or absence of a pot even if the power supply voltage fluctuates. The primary purpose is to

It is a second object of the present invention to provide a pot detecting device for an induction heating rice cooker, which can determine whether or not the pot is a pot made of a proper material.

It is a third object of the present invention to provide a pot detecting device for an induction heating rice cooker which can reliably determine the difference in pot materials even when the power supply voltage fluctuates.

[0010]

Means for Solving the Problems A first means of the present invention for achieving the first object is a rectifier circuit for rectifying an AC power supply and converting it to a DC, and an AC component connected to the rectifier circuit. A filter to be removed; a resonance circuit connected to the filter and including a heating coil and a resonance capacitor; a switching element connected to the resonance circuit for generating a resonance current; and a voltage of the switching element equal to or less than a predetermined voltage.
The switching element is determined according to the determination result.
Microprocessor means for controlling the microprocessor.
The microprocessor means starts the heating and then switches the switch.
After the voltage of the switching element reaches a predetermined voltage,
Monitoring the voltage of the circuit or of the output of the filter
A pot detecting device for an induction heating rice cooker having a judging means for judging the presence or absence of a pot by the method .

A second means of the present invention for achieving the second object is a rectifier circuit for rectifying an AC power supply and converting it to DC, a filter for removing an AC component connected to the rectifier circuit, and a filter for removing the AC component. It is connected to a resonant circuit composed of the heating coil and the resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, Sui
Determines whether the voltage of the switching element is
Microcontroller that controls the switching element according to the fixed result
A microprocessor means, and the microprocessor means
After the heating starts, the voltage of the switching element
Check the time until the voltage is reached.
In the case of outside, the pot detection device of the induction heating rice cooker which determines that the pot is an irregular pot .

According to a third aspect of the present invention, there is provided a rectifier circuit for rectifying an AC power supply and converting the rectified power to DC, a filter for removing an AC component connected to the rectifier, and a filter for removing the AC component. is connected to a resonant circuit composed of the heating coil and the resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, wherein
Determines whether the voltage of the switching element is higher than a specified voltage
Control the switching element according to the determination result.
Microprocessor means and voltage for measuring AC power supply voltage
The measuring voltage of the measuring means and the voltage measuring means is higher than a predetermined value
Sometimes the judgment time for judging the presence or absence of a pan is short, and
Kiha for judging whether to determine the presence or absence of a pot longer decision time
Time determining means; and
Start measuring the time it takes for the voltage of the
Operating time measuring means, and measured by the starting time measuring means.
Compare the startup time with the time determined by the determination time determination means
If the difference exceeds the specified value, it is an irregular pot.
And a judging means for judging that the pot is a pot detecting device of the induction heating rice cooker.

[0013]

According to the first aspect of the present invention, a microprocessor is provided.
The switching element voltage is predetermined after the stage starts heating.
Rectifier circuit voltage or filter output
The presence or absence of a pan is determined by monitoring the voltage on the power side.
It is what we are trying to do.

[0014] The second means of the present invention is a micropro- cess.
After the sensor starts heating, the switching element
If the time until the pressure reaches the specified voltage is out of the specified range,
In this case, it is determined that the pot is an irregular pot.

[0015] A third means of the present invention is a micropro- cess.
Sessor means measures voltage to determine whether pot is present
Short when the measured voltage of the means is high, and when it is low
Decide for a longer time, switch this time
Time until the voltage of the switching element reaches a predetermined voltage.
Compare, if the difference is out of the predetermined range, use an irregular pot
It is determined that there is.

[0016]

1 to 4 show an embodiment of the first means of the present invention.
This will be described below.

The electric circuit of the induction heating rice cooker has a connection configuration as shown in FIG. That is, the electric circuit of the present embodiment
A rectifier circuit 2 for rectifying the AC power supply 1 and converting it to DC;
Filter 3 for removing AC component connected to rectifier circuit 2
A resonance circuit 4 including a heating coil 5 and a resonance capacitor 6 connected to a filter 3, a switching element 7 connected to the resonance circuit 4 for generating a resonance current, and a switch
To determine whether the voltage of the switching element 7 is equal to or higher than a predetermined voltage.
Microphone for controlling the switching element 7 according to the result
And the voltage of the switching element 7
Vce level conversion means 16 for level conversion,
The peak amplifier holding the maximum voltage of the output of the bell converting means 16
Every time 0 V of the AC power supply 1 is detected.
ZV that generates a low voltage pulse (hereinafter referred to as ZVP)
The output voltage of the P generating means 10 and the rectifier circuit 2 is adjusted to a desired level.
Level conversion means 9 for converting the
Under hold means 15 for holding the minimum output voltage
Have. The microprocessor means 12 comprises a
Of the switching element 7 from the output of the
Vce voltage measuring means 18 for measuring the magnitude of the pressure;
The switching element receives the measurement signal from the e-voltage measuring means 18.
Limit to determine whether the voltage of the child 7 has reached the threshold
Output of the ZVP generating means 10
delay means 14 for delaying about μsec;
In response to the output of the limiter 19, the presence or absence of the pan 13 is determined.
Determining means 11, determining means 11 and limiter means 1
9 for driving the switching element 7 in accordance with the output of
Step 8 is provided.

The signal determined by the determination means 11 is transmitted to the control means.
8 is transmitted. In the present embodiment, the control means 8
Means 11, delay means 14, Vce voltage measuring means 18,
The transmitter 19 is provided in the microprocessor 12.
Is realized by the control program
You. In this embodiment, the level converter 9 is a rectifier circuit 2.
, But it does not matter if it is connected to the filter 3 of the next stage.

The operation of the apparatus for detecting a pot of an induction heating rice cooker constructed as described above will be described below. AC 100 V supplied by the AC power supply 1 is converted into DC by the rectifier circuit 2 and the filter 3 and supplied to the heating coil 5. For the detection of the presence or absence of the pot 13, a timer for cooking rice was set.
And always while cooking and keeping warm
You. Perform pot detection when the reservation timer is set
Is that the user forgets to set the pan 13
It is to convey. Also, during cooking and keeping warm
Pot detection is performed when the user has
When the pot is removed from the cooker, the induction cooker
Stop the circuit operation immediately to avoid breaking the circuit.
It is.

The microprocessor means 12 is illustrated
When no start button is pressed, it is shown in Figure 2.
As described above, the voltage applied to the switching element 7 is gradually increased.
In addition, the voltage is controlled to a specified voltage. That is,
Specified power of 1200 W at once
When the switching element 7 is driven to output
It will be destroyed. Therefore, in this embodiment, the ZVP
For example, about 30 W each time the generating means 10 generates ZVP once
The switching element 7 is marked so as to increase the power step by step.
The applied voltage is increasing. At this time, use
Rectifier circuit 2 or
Represents the minimum output voltage of the filter 3 as shown by the solid line in FIG.
From the moment of start-up, and gradually
It is almost 0. If there is no pot 13
In this case, the impedance of the resonance circuit 4 increases.
Therefore, the output voltage of the rectifier circuit 2 or filter 3
It decreases slightly as indicated by the line. Figure
4 (d) shows the case where the pot 13 is present and the case where it is not present
Output voltage detected by the under-hold means 15 in the case
It shows a pressure waveform. Under hold hands
Stage 15 converts the output voltage of rectifier circuit 2 to a desired level
That holds the lowest voltage of the output of the level converting means 9
It is. As can be seen from FIG.
Rectifier circuit 2 and filter
The waveform of the lowest output voltage of No. 3 is greatly different.

Hereinafter, the presence or absence of the pan 13 is detected based on FIG.
A method for performing the above will be described. FIG. 4 shows the output of the AC power supply 1.
Of the rectifier circuit 2 for rectifying the
Output, operation of delay means 14, and under hold means
15 shows the relationship between the outputs. FIG. 4A shows a rectifier circuit.
4 is generated by the ZVP generating means 10 in FIG.
4C, the ZVP is delayed by the delay means 14 in FIG.
4D, the under-hold means 15 in FIG.
The state of the change of the output minimum voltage is shown. delay
The means 14 reduces the ZVP generated by the ZVP generating means 10 by about 3
The determination means 11 determines that the delay
After determining the presence or absence of pan 13
You. This determination is based on the threshold shown in FIG.
Whether the output voltage of the under hold means 15 is high or low
Is what you are doing. That is, below the threshold
Pot 13 is present when the output voltage of holding means 15 is high
Otherwise, when it is low, it is determined that the pan 13 exists.
Is what it is. This determination is based on the output of the ZVP generation means 10.
The relationship with the threshold was measured 15 times each time the force was received.
At least eight times there is a state higher or lower than the threshold
When the pot 13 does not exist or exists
Has been determined. In other words, prevent malfunction due to noise
Is what it is.

At this time, the judgment means 11
After the voltage of the child 7 has reached a predetermined voltage, it is determined whether or not the pot 13 is present.
It is intended to be set. That is, rectification times
It is performed after the voltage of the path 2 and the filter circuit 3 is stabilized.
Things. Therefore, the determination means 11 determines whether or not the pot 13 is present.
The judgment is more reliable. Determination means 1
1 transmits this determination result to the control means 8. control
Means 8 receives this signal, and when pan 13 is present,
The operation of the switching element 7 is continued, and the pan 13 is not present.
To stop the operation of the switching element 7 when
You.

Note that the determination method of this embodiment is
It is possible to reliably determine the presence or absence of the pan 13 when cooking and keeping warm.
Things. In other words, conventionally, it starts both when cooking rice and when keeping warm
The time elapsed since the moment of the
He knew. However, the output during cooking rice is
For example, it is 1200 W, and the output at the time of heat retention is, for example, 300 W
Because it is W, the switching element depends on when cooking and keeping warm.
The time required for the child 7 to reach the predetermined voltage also varies greatly.
It is. In this regard, in the present embodiment, a constant
To determine the presence or absence of the pan 13 when the time of
And the voltage measured by the Vce voltage measuring means 18 is limited.
The judgment is made when the threshold value of the
Is what has started. Therefore, there is no
Can accurately determine the presence or absence of a pot
You.

In this embodiment, the judgment by the judging means 11 is performed.
Is performed 8 times or more out of 15 times. This
Therefore, malfunction due to noise can be prevented, and reliable judgment can be made.
You can do it.

In this embodiment, the delay, determination, control, means, conversion, and the like are configured using the program of the microprocessor means 12, but may be configured by hardware.

Next, an embodiment of the second means of the present invention will be described with reference to FIG. In this embodiment, the micropro
The sensor means 12 includes a Vce voltage measuring means 18 and a limiter.
Means 19, delay means 14, and start-up time measuring means 20
, Determination means 11 and control means 8. At startup
The interval measuring means 20 is a switch activated by the control means 8.
Time until the voltage of the switching element 7 reaches a predetermined voltage
Is measured. That is, Vce measuring means
The voltage of the switching element 7 detected by 18 is activated.
From the moment when the threshold value detected by the limiter means 19 is reached.
It measures the time until the moment you do it. Of this time
The measurement is performed by counting the number of detection pulses output from the delay unit 14.
By doing In other words, ZVP is 1 second
50 or 60 times in between
The detection pulse passing through the delay means 14
Time and number of times. Determination means 11
Indicates that the startup time measured by the startup time measuring means 20 is
Compare with the preset start time, start heating
Until the voltage of the switching element 7 reaches a predetermined voltage.
If the time at is out of the predetermined range, it is an irregular pot
It has been determined. In this embodiment, the control means 8
Judging means 11, delay means 14, Vce voltage measuring means 18
・ Limiter means 19 ・ Start-up time measuring means 20 is a microphone
According to the control program of the
It has been realized.

The operation of the apparatus for detecting a pot of an induction heating rice cooker configured as described above will be described below.
When the material of the pot 13 is, for example, aluminum
Also, if the user inadvertently removes small items such as spoons
If set, the output of switching element 7 is abnormal
Becomes FIG. 6 shows a state where the Vce voltage measuring means 18 detects the voltage.
Changes in the output voltage of the switching element 7
I have. That is, the load set in the resonance circuit 4 is positive.
If it is not the pan 13, the impedance of the resonance circuit
Changes, the output voltage of the switching element 7 becomes steady.
The time to reach the state also changes. Aluminum
This time is short in the case of a nickel pot, and small items such as spoons
If it is included, it will be longer. In this embodiment,
It focuses on this fact. That is, at startup
Whether the switching element 7 has been activated
Delay until the threshold value of the limiter 19 is reached.
Counting the number of detection pulses output by the extension means 14
The time is measured by: Determination means 11
If this time is out of the predetermined range,
It is determined that there is. Therefore, according to the present embodiment,
In addition to judging the presence or absence of a pan, check whether the material of the pan is
Can detect an object with a blade or knife in it.
Things.

Next, an embodiment of the third means of the present invention will be described with reference to FIGS. The difference from the embodiment of the second means of the present invention is that a power supply voltage measuring means 22 for measuring an AC power supply voltage, a determination time determining means 23 for determining a determination startup time determined by the result, If the activation time measured by the time measuring means 20 is too long or too short as compared with the time determined by the determination time determining means 23, a function of determining that the pot is an irregular pot is provided. And determination means 11 having

The operation of the embodiment will be described below. Figure
As shown in Fig. 8, when the power supply voltage rises,
After that, the voltage of the switching element 7 reaches a predetermined voltage.
The startup time until is shorter. If the power supply voltage drops,
The activation time of the switching element 7 is prolonged. One
In other words, the startup time of the switching element 7 depends on the power supply voltage.
Is what you are doing. In this embodiment, the power supply voltage measuring means
22 is used to measure the power supply voltage, and this signal is used for determination time.
This is transmitted to the determination means 23. Judgment time decision
Setting means 23 determines the presence or absence of a pot when the power supply voltage is high.
The judgment time is short when the power supply voltage is low.
The length of the interval is determined. In other words, the power supply voltage
Therefore, the determination time itself is changed. This
As a result, even if the power supply voltage fluctuates,
Or the type of pot is irregular or a spoon inside the pot
It can be determined even if a knife is inserted.

In the above three present inventions, the specified power has been described by the Vce limiter means based on the magnitude of the collector voltage of the switching element. The same explanation can be given by using a Ton limiter which is a control based on the ON time of the element.

[0031]

As described above, according to the first aspect of the present invention, a rectifier circuit for rectifying an AC power supply and converting it to DC, a filter for removing an AC component connected to the rectifier circuit, It is connected to a resonant circuit composed of the heating coil and the resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, Sui
Determines whether the voltage of the switching element is
Microcontroller that controls the switching element according to the fixed result
A microprocessor means, the microprocessor means comprising:
Means that the voltage of the switching element
When it is detected that the voltage has reached a certain
Or monitor the output voltage of the filter to determine if a pan is present.
With this configuration, it is possible to obtain a device that can reliably determine the presence or absence of a pot.

Further, according to the second means of the present invention, a rectifier circuit for rectifying an AC power supply and converting it to DC, a filter for removing an AC component connected to the rectifier circuit, and a heating coil connected to the filter, A resonance circuit comprising: a resonance capacitor; a switching element connected to the resonance circuit for generating a resonance current; and a voltage of the switching element.
Determines whether the voltage is equal to or higher than a predetermined voltage, and switches
Microprocessor means for controlling the switching element.
And the microprocessor means starts heating after
When the switching element voltage reaches the specified voltage
If this time is out of the specified range,
Since the configuration is such that the pot is determined to be a pot, it is possible to reliably determine that the pot is an unauthorized pot.

According to the third means of the present invention, a rectifier circuit for rectifying an AC power supply and converting it to DC, a filter for removing an AC component connected to the rectifier circuit, a heating coil connected to the filter, A resonance circuit comprising: a resonance capacitor; a switching element connected to the resonance circuit for generating a resonance current; and a voltage of the switching element.
Determines whether the voltage is equal to or higher than a predetermined voltage, and switches according to the determination result.
Microprocessor means for controlling the switching element;
A voltage measuring means for measuring a power supply voltage;
The processor means sends a determination time for determining the presence or absence of a pan
Short when the voltage measured by the pressure measuring means is high,
The heating time is determined
When the switching element voltage reaches the specified voltage
And if the difference is out of the predetermined range, it is irregular
As a configuration for determining that the pot is a pan, it is possible to reliably determine that the pan is an irregular pot even if the power supply voltage fluctuates.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a pot detecting device of an induction heating rice cooker showing an embodiment of a first means of the present invention.

FIG. 2 is a diagram showing a change in applied power of the induction heating rice cooker in the embodiment.

FIG. 3 is an output waveform diagram of a rectifier circuit with and without a pan in the embodiment.

FIG. 4 is an output waveform diagram of the under-hold means when there is a pan and when there is no pan in the embodiment.

FIG. 5 is a circuit configuration diagram of a pot detecting device of an induction heating rice cooker showing an embodiment of the second means of the present invention.

FIG. 6 is a diagram showing a relationship between a starting time and an output voltage of a limiter unit in the embodiment.

FIG. 7 is a circuit configuration diagram of a pot detection device of an induction heating rice cooker in an embodiment of the third means of the present invention.

FIG. 8 is a diagram showing a relationship of a start time due to a change in a power supply voltage in the embodiment.

FIG. 9 is a circuit configuration diagram of a pot detecting device of an induction heating rice cooker showing a conventional embodiment.

[Explanation of symbols]

 2 Rectifier circuit 3 Filter 4 Resonance circuit 5 Heating coil 6 Resonant capacitor 7 Switching element 8 Control means 9 Level conversion means 10 ZVP generation means 11 Judgment means 13 Pot 14 Delay means 15 Under hold means 19 Limiter means 20 Start time measurement means 21 Power supply Voltage measurement means 22 Determination time determination means

Claims (3)

(57) [Claims] 1. A rectifier circuit for rectifying an AC power supply and converting the AC power into DC, a filter connected to the rectifier circuit for removing an AC component, a resonance circuit connected to the filter and including a heating coil and a resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, the scan
Determines whether the voltage of the switching element is
A micro that controls the switching element according to the judgment result
Processor means, the microprocessor means
Means that the voltage of the switching element
When a constant voltage is detected, the voltage of the rectifier circuit or the filter
Pot detection device for induction heating rice cookers that monitors the voltage on the output side of the device and determines the presence or absence of a pot. 2. A rectifier circuit for rectifying an AC power supply and converting the AC power into DC, a filter connected to the rectifier circuit for removing an AC component, a resonance circuit connected to the filter and including a heating coil and a resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, the scan
Determines whether the voltage of the switching element is
A micro that controls the switching element according to the judgment result
Processor means, and the microprocessor means
After the heating starts, the voltage of the switching element
Check the time until the voltage is reached.
A pot detector for an induction cooker that determines that the pot is an unauthorized pot when outside . 3. A rectifier circuit for rectifying an AC power supply and converting it to DC, a filter connected to the rectifier circuit for removing an AC component, a resonance circuit connected to the filter and including a heating coil and a resonance capacitor, a switching element for generating a connected resonant current in the resonant circuit, the scan
Determines whether the voltage of the switching element is
A micro that controls the switching element according to the judgment result
A processor means and a voltage measuring means for measuring the AC power supply voltage;
And a microprocessor means, the presence or absence of a pan
Time when the voltage measured by the voltage measuring means is high
Short when it is low, and long when it is low.
And the voltage of the switching element after heating starts
And the time until the voltage reaches
A pot detection device of an induction cooker that determines that the pot is out of range .