KR100665057B1 - Microwave Oven and Control Method Thereof - Google Patents

Abstract

The present invention relates to a microwave oven having a magnetron, a power supply unit for supplying a commercial AC power supply, a high voltage transformer for generating a high voltage by the commercial AC power supplied from the power supply unit, and a control method thereof. The microwave oven includes a rectifier smoothing unit for rectifying and smoothing AC power; An inverter unit for converting the DC power that has passed through the rectifying smoother into an AC power of high frequency; A control signal generator for generating a control signal for controlling the inverter unit; When the voltage of the AC power supplied from the power supply exceeds the allowable voltage, characterized in that it comprises a power control unit for controlling the control signal generator to adjust the generation time of the control signal. As a result, the generation time of the control signal can be controlled according to the voltage and current of the AC power input from the power supply, and the operation time of the magnetron can be adjusted.

Description

Microwave Oven and Control Method Thereof

1 is a control block diagram of a microwave oven according to the present invention;

2 is a control flow chart according to the present invention,

3 is a control flow chart according to the steady current flow of the present invention,

4 is a detailed circuit diagram of an abnormal signal detection unit of FIG. 1;

5 is a schematic block diagram of a conventional microwave oven.

<Description of Symbols for Main Parts of Drawings>

 1: power supply unit 3: rectification smoothing unit

 5: inverter 7: high voltage transformer

 9: magnetron 11: power control unit

13 current detection unit 15 inverter control unit

17: oscillation unit 19: output control unit

21: resonance detection unit 23: on-off start unit

25: D / A converter 27: control signal generator

28: abnormal signal detection unit 31: comparator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven and a control method thereof, and more particularly, to a microwave oven and a method of controlling the same, when a transient overvoltage or instantaneous current is applied during operation of the microwave oven.

In general, the operation principle of a microwave oven applies a commercial AC power supplied from a power supply unit to a primary coil of an iron core high voltage transformer to generate a high voltage in a secondary coil. The high voltage generated in the secondary coil of the high voltage transformer heats the cathode filament provided in the magnetron, and the magnetron is oscillated by the applied high voltage to radiate microwave energy. The microwave energy may be converted into thermal energy when cooking with water or a water-containing object (eg, food ingredients, etc.) in a closed space.

5 is a schematic control block diagram according to a conventional microwave oven. As shown in the figure, the conventional microwave oven is a high-voltage transformer 107 for generating a high voltage by a power supply unit 101 for supplying a commercial AC power, a commercial AC power supplied from the power supply 101, and a high pressure The magnetron 109 for generating electromagnetic waves by the high voltage generated by the transformer 107, the rectifying smoothing unit 103 for rectifying and smoothing the commercial AC power supply, and the DC power supply passing through the rectifying smoothing unit 103 are operated at high frequency. An inverter unit 105 for switching to a power source and a signal generator 127 for generating a control signal are provided.

The inverter controller 115 includes a D / A converter 125 for converting a control signal generated from the signal generator 127 into an analog signal, and a control signal converted from the D / A converter 125 is a resonance detection unit. An output controller 119 applied to the controller 121 to control and output a frequency of the control signal detected by the resonance detector 121, and an inverter unit 105 by varying a period of the control signal output from the output controller 119; It has an oscillator 117 to input. The inverter controller 115 further includes an on / off start unit 123 that controls the on / off of the oscillator 117 and the soft start of the oscillator 117 according to the control signal generated by the signal generator 127.

By the way, in such a conventional microwave oven, even if the commercial AC power input through the power supply is smoothed to the DC power through the rectifying smoothing unit, even if the current value converted through the rectifying smoothing unit exceeds a predetermined allowable current value. The control signal is generated in the set cycle at, which may reduce the safety of the circuit.

In addition, even when the voltage of the AC power supplied from the power supply unit exceeds the set voltage or is lower than the allowable lower limit voltage, the control signal is generated at a set period so that the operation of the magnetron cannot be controlled and the safety of the circuit can be reduced.

Accordingly, an object of the present invention is to provide a microwave oven and a control method thereof capable of adjusting the generation time of a control signal generated by the control signal generator.

The object of the present invention is a microwave oven having a magnetron, a power supply for supplying AC power, and a high voltage transformer for generating a high voltage by the AC power supplied from the power supply. A smooth rectification smoothing part; An inverter unit for converting the DC power that has passed through the rectifying smoother into an AC power of high frequency; A control signal generator for generating a control signal for controlling the inverter; When the voltage of the AC power supplied from the power supply exceeds the allowable voltage, it is achieved by a microwave oven, characterized in that it comprises a power control unit for controlling the control signal generator to adjust the generation time of the control signal. .

The power control unit may control the operation time of the magnetron by controlling the control signal generator to adjust the generation time of the control signal when the current value of the DC power supply passing through the rectification smoothing unit exceeds the allowable current value.
And an abnormal signal detection unit for determining whether the control signal generated by the control signal generator is out of an allowable control signal range, and wherein the inverter control unit is configured such that the control signal detected by the abnormal signal detection unit is out of an allowable control signal range. If it is determined, application of the control signal to the magnetron may be blocked.

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A D / A converter for converting the control signal generated from the control signal generator into an analog signal, an output controller for controlling and outputting a frequency of the control signal generated from the control signal generator, and in the output controller The inverter control unit further comprises an oscillator for varying the period of the control signal output to the inverter unit and an on / off start unit for controlling the on-off of the oscillator and soft start of the oscillator according to the control signal. It is desirable to.

The inverter controller controls the on / off time of the on / off start unit based on the time of generation of the control signal generated by the control signal generator, and the on / off start unit has a transistor for switching the on / off time. On and off time can be easily adjusted.

On the other hand, according to another field of the present invention, the object is a high frequency of the magnetron, a power supply for supplying AC power, rectification and smoothing rectifying and smoothing the AC power, and a direct current power through the rectifying smoothing part of the high frequency In the control method of the microwave oven having an inverter unit for converting into an AC power source, a high voltage transformer for generating a high voltage by the DC power from the rectifying and smoothing unit, and a control signal generator for generating a control signal for controlling the inverter unit Determining whether the AC power supplied from the power supply unit exceeds an allowable voltage; If it is determined that the voltage of the AC power supply exceeds the allowable voltage, it is also achieved by the method of controlling a microwave, including controlling the control signal generator to adjust the generation time of the control signal.
Determining whether the current value deviates from an allowable current value by detecting a current value of the DC power supply passing through the rectifying smoothing unit; If it is determined that the current value is out of the allowable current value, it is effective to further include controlling the control signal generator to adjust the generation time of the control signal.

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According to a control signal generated by the control signal generation unit may further include an on-off start unit for controlling the on-off and soft start of the inverter unit, the on-off start unit may use a transistor for adjusting the on-off time of the inverter unit. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a control block diagram of a microwave oven according to the present invention. As shown in this figure, the microwave oven includes a power supply unit 1 for supplying a commercial AC power supply, a high voltage transformer 7 for generating a high voltage by the commercial AC power supplied from the power supply unit 1, and a high pressure. It has a magnetron 9 for generating electromagnetic waves by the high voltage generated in the transformer 7. The microwave oven according to the present invention has a predetermined allowable current value of the input voltage inputted to the high voltage detector 14 and the high voltage transformer 7, which detects whether the voltage of the supply power supply of the power supply 1 exceeds a predetermined allowable upper limit voltage. It further has a current detector 1 for judging whether the current value is exceeded.

The microwave oven is provided with a power control unit 11 for controlling the generation time of the control signal by controlling the control signal generator 27 when the voltage of the AC power supplied from the power supply unit 1 exceeds the allowable voltage. If it is determined that the current value exceeds the allowable current value, the power control unit 11 cuts off the input power input to the magnetron 9, pauses the magnetron 9 for a predetermined rest time, and then resumes the power.

The microwave oven according to the present invention includes a rectification smoothing unit (3) for rectifying and smoothing a commercial AC power supply, an inverter unit (5) for converting a DC power supply passing through the rectifying smoothing unit (3) into a high frequency AC power supply, and a control signal When the current value of the control signal generator 27 and the direct current power supply passing through the rectification smoother 3 exceeds the allowable current value, the control signal generator 27 is controlled to adjust the generation time of the control signal. It further has an inverter control part 15.

The inverter controller 15 may include a D / A converter 25 for converting a control signal generated from the signal generator 27 into an analog signal, and a control signal converted from the D / A converter 25 may include a resonance detector ( 21 and an output control unit 19 for controlling and outputting the frequency of the control signal detected by the resonance detection unit 21, and the period of the control signal output from the output control unit 19 to the inverter unit 5 It has the oscillation part 17 which inputs. The inverter controller 15 controls the on / off of the oscillator 17 and the soft start of the oscillator 17 according to the control signal generated by the signal generator 27, and a control signal. It further has an abnormal signal detection unit 28 for determining whether the control signal generated by the generation unit 27 is out of the allowable control signal range.

The inverter controller 15 adjusts the on / off time of the on / off start unit 23 based on the generation time of the control signal generated by the control signal generator 27, and the on / off start unit 23 is the on / off time. It has a transistor () for switching. If it is determined that the control signal detected by the abnormal signal detection unit 28 is outside the allowable control signal range, the inverter control unit 15 blocks the control signal from being applied to the magnetron 9.

Hereinafter, with reference to FIG. 2 which is a control flowchart of the high voltage detection part of the present invention, and FIG. 3 which is a control flowchart when a steady voltage is introduced into the microwave oven.

First, the commercial AC power is applied from the power supply unit 1, and the control signal is applied from the control signal generator 27 (S11). The voltage of the AC power applied from the power supply unit is detected, and it is determined whether the detected voltage is out of the allowable upper limit voltage (S13, S15). If it is determined that the detection voltage is out of the allowable upper limit voltage, the control signal generation time in the control signal generator 27 is adjusted (S17). The control signal generated through the control signal generator 27 and the applied AC power are applied to the inverter unit 5 based on the detected voltage (S19). Power supplied to the inverter unit 5 is supplied to the high voltage transformer 7 to generate a high voltage (S21), and the high voltage generated from the high voltage transformer 7 is applied to the magnetron 7 to generate electromagnetic waves ( S23).

On the other hand, if it is determined in step S15 that the detected voltage does not deviate from the allowable upper limit voltage, the input commercial AC power is converted into DC power through the rectifying smoothing unit 3 (S25). It is compared whether or not the current value of the DC power source converted through the rectifying smoother 3 into the DC power source exceeds a predetermined allowable current value (S27). If it is determined that the current value is out of the predetermined allowable current value, the control signal generation time in the control signal generator 27 is adjusted (S29). Based on the detected voltage, the control signal generating unit 27 applies the control signal whose generation time is adjusted and the applied AC power to the inverter unit 5 (S31). The power supplied to the inverter unit 5 is supplied to the high voltage transformer 7 to generate a high voltage (S33), and the high voltage generated from the high voltage transformer 7 is applied to the magnetron 7 to generate electromagnetic waves (S35). .

On the other hand, if it is determined in step S27 that the current value of the DC power converted to the DC power through the rectification smoothing unit 3 does not deviate from the predetermined allowable current value, the power supplied through the power supply unit 1 to the inverter unit 5 and The control signal generated by the control signal generator 27 is applied (S37). The power applied to the inverter unit 5 is supplied to the high voltage transformer 7 to generate a high voltage (S39), and the high voltage generated from the high voltage transformer 7 is applied to the magnetron 7 to generate electromagnetic waves (S41). .

Although not shown in the control flow diagram of FIG. 2, which is an embodiment of the present invention, when it is determined in step S25 that the current value exceeds a predetermined allowable current value, the magnetron is rested for a predetermined rest time while controlling the generation time of the control signal. The method may further include restarting the post-operation and stopping the driving of the magnetron when the magnetron is out of the predetermined number of times.

In addition, although FIG. 2 describes the adjustment of the generation time of the control signal by detecting the allowable upper limit voltage of the commercial AC power supply, the time limit of the control signal is adjusted by detecting the allowable lower limit voltage of the AC power used or the allowable upper limit voltage is detected. And it is possible to adjust the generation time of the control signal generated from the control signal generator by sequentially detecting the lower limit voltage.

When the control signal is applied in step S11, determining whether the control signal is out of the allowable control signal range through the abnormal signal detection unit 28, and the control signal detected by the abnormal signal detection unit 28 is in the allowable control signal range. If it is determined to deviate from, it may be added to block the control signal is applied to the magnetron (9).

As shown in FIG. 3, the signal generator 27 generates a control signal together with the power supply from the power supply unit 1 (S51). The inverter control unit 15 branches the control signal generated by the signal generator 27 and applies it to the on / off start unit 23 and the D / A converter 25 (S53). The control signal branched to the D / A converter 25 and the on-off start unit 23 is applied to the output control unit 21 at a predetermined time interval (S55), and the control signal passed through the output control unit 21. Is applied to the input terminal of the oscillation unit 17 (S57). The control signal that has passed through the oscillation unit 17 is applied to the inverter unit 5 with a variable period (S59).

The control signal passed through the inverter unit 5 is applied to the resonance detecting unit 21 (S61), and the inverter control unit 15 determines whether the control signal detected by the resonance detecting unit 21 is an abnormal signal (S63). If the control signal detected by the detector 21 is an abnormal signal, the control signal is blocked from being applied to the output controller 19 (S69).

On the other hand, if it is determined that the detection signal from the resonance detecting unit 21 is not an abnormal signal, the control signal passed through the inverter unit 5 is controlled to be applied to the output control unit 19, and passes through the rectifying smoothing unit 3. The DC power is converted into high frequency AC power based on the control signal applied to the inverter unit 5. The converted high frequency AC power is applied to the high voltage transformer 7 to generate a high voltage, and the control signal passed through the high voltage transformer 7 is applied to the magnetron 9 (S65).

In addition, the control signal applied to the magnetron 9 through the high voltage transformer 7 may also be applied to the resonance detector 21 to determine whether the abnormal control signal, and the resonance frequency applied to the resonance detector 21 If it is determined that the set resonance frequency does not deviate, the control flow is applied to the output control unit 19 and the control flow applied to the oscillation unit 17 and the inverter unit 5 is repeated (S57 to S63). On the contrary, if the resonance frequency is out of the range, the control signal may be blocked from being applied to the output control unit 19.

4 is a detailed circuit diagram of an on-off start unit according to the present invention. As shown in the figure, the on-off start unit 23 switches the on-off time based on the generation time of the control signal generated by the control signal generator 27. At this time, the switching control of the on-off time may be made by the transistor 31.

As such, a control signal generator for generating a control signal for driving the magnetron; When the voltage of the AC power supplied from the power supply exceeds the allowable voltage, by controlling the control signal generator to include a power control unit for adjusting the generation time of the control signal, the control according to the instantaneous overvoltage and instantaneous overcurrent The signal can be adjusted and provided.

As described above, according to the present invention, a microwave oven capable of quickly adjusting the on / off time of the magnetron by adjusting the generation time of the control signal generated by the control signal generator when the momentary overvoltage and the momentary overcurrent are applied A control method is provided.

Claims (10)

In a microwave oven having a magnetron, a power supply for supplying AC power, and a high voltage transformer for generating a high voltage by the AC power supplied from the power supply, A rectifying smoothing unit for rectifying and smoothing the AC power; An inverter unit for converting the DC power that has passed through the rectifying smoother into an AC power of high frequency; A control signal generator for generating a control signal for controlling the inverter; And a power controller configured to control the control signal generator to adjust the generation time of the control signal when the voltage of the AC power supplied from the power supply exceeds an allowable voltage. The method of claim 1, And the power controller controls the control signal generator to adjust the generation time of the control signal when the current value of the DC power supply passing through the rectification smoother exceeds an allowable current value. The method of claim 2, An abnormal signal detection unit for determining whether the control signal generated by the control signal generator is outside the allowable control signal range, further comprising: And the inverter controller blocks the application of the control signal to the magnetron when it is determined that the control signal detected by the abnormal signal detection unit is out of an allowable control signal range. The method according to claim 2 or 3, A D / A converter for converting the control signal generated from the control signal generator into an analog signal, an output controller for controlling and outputting a frequency of the control signal generated from the control signal generator, and in the output controller The inverter controller further includes an oscillator for varying the period of the control signal output to the inverter unit, and an on / off start unit for controlling the on / off of the oscillator and soft start of the oscillator according to the control signal. Microwave oven characterized in that. The method of claim 4, wherein And the inverter controller controls the on / off time of the on / off start unit based on a generation time of the control signal generated by the control signal generator. The method of claim 5, And the on / off start portion has a transistor for switching the on / off time. A magnetron, a power supply unit for supplying AC power, a rectification and smoothing unit for rectifying and smoothing the AC power, an inverter unit for converting DC power passing through the rectifying smoothing unit into high frequency AC power, and the rectifying and smoothing unit A control method of a microwave oven having a high voltage transformer for generating a high voltage by a direct current power supply from a control unit, and a control signal generator for generating a control signal for controlling the inverter unit. Determining whether the AC power supplied from the power supply unit exceeds an allowable voltage; And controlling the control signal generator to adjust the generation time of the control signal when it is determined that the voltage of the AC power exceeds an allowable voltage. The method of claim 7, wherein Determining whether the current value deviates from an allowable current value by detecting a current value of the DC power supply passing through the rectifying smoothing unit; And controlling the control signal generator to adjust the generation time of the control signal when it is determined that the current value is out of the allowable current value. The method according to claim 7 or 8, And an on / off start unit for controlling on / off and soft start of the inverter unit according to the control signal generated by the control signal generator. The method of claim 9, And the on / off start unit has a transistor for controlling the on / off time of the inverter unit.

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