KR890004872Y1 - Power frequency control circuit of microwave range - Google Patents

Abstract

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Description

Microwave power frequency control circuit

1 is a schematic diagram of the present invention.

2 is a detailed circuit diagram of the present invention.

3 is a signal waveform diagram of a main part of the signal conversion section of FIG. 2;

* Explanation of symbols for main parts of the drawings

10: power supply unit 20: signal conversion unit

30: frequency detection unit 40: switch drive unit

50: voltage compensation circuit

The present invention relates to a circuit for controlling any power source frequency to be operated in a microwave oven.

Conventional microwave ovens can be used only in a single frequency of 120V / 60Hz or 120V / 50Hz, and even if the power source frequency of 50Hz and 60Hz combined, there was a drawback to reconnect parts of the microwave oven.

Accordingly, an object of the present invention is to provide a circuit that automatically detects 60 Hz of a power frequency of 50 Hz of 120 V and operates the microwave regardless of the input frequency.

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

1 is a schematic diagram of the present invention, a power source applied to a general microwave oven is supplied to a high voltage transformer (HVT) via a safety switch (SW1-SW3), and the voltage boosted by the high voltage transformer (HVT) is a magnetron (MGT). ) Is supplied and oscillates.

In addition, the power applied to the microwave is stepped down through the low voltage transformer (LVT), and the power supply for supplying the stepped down power to the digital display (Digitron) and at the same time converting to a DC power supply (Vcc) for circuit operation ( 10) and a signal converter 20 for applying the square wave power stepped down by the low voltage transformer LVT to convert the square wave power, and the square wave signal output from the signal converter 20 to apply the square wave power. A frequency sensing unit 30 which is a microcomputer (MIC) for sensing the switch, a switch driving unit 40 for driving the relay switch SW4 by a signal output by sensing a power frequency from the frequency sensing unit 30, and The voltage compensation circuit 50 compensates the voltage capacity supplied to the magnetron MTG according to the switching of the relay switch SW4.

2 is a detailed circuit diagram of the present invention, wherein the power supply unit 10 corresponds to a resistor (R1-R5), a diode (ZD, D1, D2, D5), a capacitor (C4) and a transistor (Q1). Supplying a DC power to the, the signal conversion unit 20 corresponds to the diode (D3), resistors (R3, R4) and transistor (Q2) to convert the input square wave power to square wave power, frequency detection unit 30 Corresponds to a microcomputer (MIC) for applying a square wave power, and the switch driver 40 for driving the relay switch (SW4) driven by a control signal output from the microcomputer (MIC) includes a transistor (Q3) and a diode ( D4), the relay RY2 and the resistor C3.

In addition, the voltage compensating circuit 50 for compensating the power supply voltage applied through the high voltage transformer HVT according to the switching of the relay switch SW4 to be applied to the magnetron MGT includes the capacitors C1 and C2 and the resistor RC1. , RC2).

Next, the above-described configuration will be described based on the waveform diagram of FIG.

The external AC power is stepped down through the low voltage transformer LVT, and the stepped down power supplies the digitron by the resistors R1 and R2 and the zener diode ZD, and the stepped down power supply is the diode D1. And half wave are output by the electrolytic capacitor C4.

The half-wave rectified power is converted into a direct current power supply through the diode D2, the resistor R5, and the transistor Q1, and supplied to each circuit.

Meanwhile, the square wave power supply (A in FIG. 3) stepped down through the low voltage transformer LVT is half-wave rectified by the diode D3 and then divided by the resistors R3 and R4 and applied to the base of the transistor Q2. .

The signal applied to the base of the transistor Q1 (B in FIG. 3) is a positive signal and the transistor Q2 is conducted. As a result, a logic " 0 " appearing in the collector of the transistor Q2 is conducted. The low level signal (C in FIG. 3) is applied to the microcomputer MIC, and conversely, when a negative polarity is applied to transistor Q2, the logic " 1 " (high) appears in the collector of transistor Q2. Level) signal (C in FIG. 3) is applied to the microcomputer MIC.

At this time, the microcomputer MIC performs counting for 1 second according to the input signal, and detects whether the input power is 50 Hz or 60 Hz.

If the microcomputer (MIC) detects that the input power is 60 Hz, it outputs a logic "0" signal through the output terminal of the microcomputer so that the relay driving transistor Q3 is not conducted and at the same time, the relay RY2 is not driven. Relay switch SW4 is " off "

However, when the microcomputer MIC detects that the input power is 50 Hz, a logic " 1 " signal appears at the output of the microcomputer MIC to conduct the transistor Q3, and at the same time, the relay RY2 is driven to relay the switch. (SW4) is "on".

Therefore, when the relay switch SW4 is "on", the capacitors C1 and C2 are connected in parallel so that the voltage applied through the high voltage transformer HVT is compensated and supplied to the magnetron MGT.

The rectifier diode D4 and the capacitor C3 are connected to compensate for the counter electromotive force of the high voltage relay RY2.

As described above, according to the present invention, a power source having a frequency of 50 Hz or 60 Hz can be used as a mixture.

Claims (1)

In a microwave oven in which an external power supply is boosted by a high voltage transformer (HVT) and supplied to a magnetron (MGT), the external power is forced down by a high voltage transformer (HVT) and applied to supply a DC power supply (Vcc) to a circuit. The power supply unit 10, the signal converter 20 for converting the square wave power stepped down through the low voltage transformer (LVT) into a square wave signal, and the output signal of the signal converter 20 is applied to Switching of the switch driver 40 and the relay switch SW4 which are driven by the frequency sensing unit 30 for sensing a frequency and the output signal of the frequency sensing unit 30 to control the switching of the relay switch SW4. And a voltage compensating circuit (50) for compensating the voltage applied through the high voltage transformer (HVT) to be supplied to the magnetron (MGT).