KR20020036917A - Microwave oven drive circuit - Google Patents

Abstract

PURPOSE: A microwave oven driving circuit is provided to prevent all of magnetrons from driving when any one fuse is disconnected due to over-current. CONSTITUTION: A microwave oven driving circuit comprises a first and a second commercial AC lines(L1,L2) coupled to a commercial AC power input terminal(AC 110V or 220V) and a first high voltage transformer(HVT1), and a third and a fourth commercial AC lines(L3,L4) coupled to a commercial AC power input terminal and a first coil of a second high voltage transformer(HVT2). A first fuse(FUSE10) is connected between the first commercial AC line(L1) and the first coil of the first high voltage transformer(HVT1). The third commercial AC line(L3) is coupled to the first commercial AC line(L1) via the first fuse(FUSE10) and a second fuse(FUSE20). The fourth commercial AC line(L4) is coupled parallel to the second commercial AC line(L2). A low voltage transformer(LVT) is coupled between the first and the second commercial AC lines(L1,L2) via the first and the second fuses(FUSE10,FUSE20).

Description

Microwave oven drive circuit

The present invention relates to a microwave driving circuit, and more particularly, to a microwave driving circuit capable of effectively blocking the overcurrent inflow of the microwave oven.

In general, a microwave oven is a device for heating / cooking food using microwaves, and includes a general high voltage transformer and a magnetron, and the high voltage transformer generates a high voltage to generate a magnetron. The magnetron emits high frequency (approximately 2450 MHz) microwaves in a confined space where food is stored. Microwaves emitted in this way vibrate the water molecules contained in the food, molecular friction heat is generated in accordance with the vibration of the water molecules is to heat / cook food.

On the other hand, in recent years, a high power / large capacity microwave oven is required in convenience stores and various offices, etc. As a result, high power microwave ovens having a plurality of high voltage transformers and magnetrons are widely used.

1 illustrates such a conventional high power microwave driving circuit.

According to the drawing, the first and second commercial AC lines (L1) and L2 are supplied with a conventional commercial AC power supply (AC 110V or 220V) through one end thereof, and the other end thereof is the first high voltage transformer (HVT1) primary. It is connected to both ends of the coil to form a closed circuit. Here, a first fuse FUSE1, a first door switch SW1 and a monitor switch SW3 are connected in series to the first commercial AC line L1, and a second commercial AC line L2 is connected to the first commercial AC line L2. 1 relay RY1 is connected.

Also, a first node node1 between the first fuse FUSE1 and the first door switch SW1 on the first commercial AC line L1 and a second node between the AC power input terminal and the first relay. The low voltage transformer LVT and the temperature sensor TCO1 and TCO2 are provided between the node2s. The voltage applied at the secondary coil side of the low voltage transformer LVT is supplied for driving the load circuit 10. The load circuit 10 includes a microcomputer 1, a relay driver 2 for driving the first and second relays RY1 and RY2 in response to a signal given by the microcomputer 1, a lamp (not shown), and a fan. A motor (not shown), a timer (not shown), and the like are included.

In the above configuration, the first fuse FUSE1 blocks the overcurrent flowing to the load circuit 1 and the high voltage transformer HVT1, and the door switch SW1 and the monitor switch SW3 are connected to the door (not shown). It is turned on / off according to the open / closed state to perform the safety function when driving the microwave.

Further, on the input side, third and fourth commercial exchange lines L3 and L4 connected in parallel with the first and second commercial exchange lines L1 and L2 are provided, and the third and fourth commercial exchange lines are provided. L3 and L4 are connected to both ends of the primary coil of the second high voltage transformer HVT2 to form another closed circuit. A second fuse FUSE2, a second door switch SW2, and a monitor switch SW4 are connected in series to the third commercial AC line L3, and a second relay is connected to the fourth commercial AC line L4. RY2 is connected, and each action is the same as the above-described fuse FUSE1, door switch SW1, monitor switch SW3 and relay RY1.

In addition, the secondary coils of the first and second high voltage transformers HVT1 and HVT2 have high voltage capacitors HVC1, HVC2, HVD1, HVD2, and magnetron MGT1 (for generating microwaves). MGT2) is provided respectively.

The first and second relays RY1 and RY2 are turned on and off by the microcomputer 1 and the relay driver 2 to supply a commercial AC power to the first and second high voltage transformers HVT1 and HVT2. Switch (AC).

Referring to the operation of the conventional high-power microwave driving circuit configured as described above, when the first and second relays RY1 and RY2 are turned on by the micom 1 and the relay driver 2, the first and second relays are turned on. A commercial AC power is applied to the third and fourth commercial AC lines L3 and L4 together with a second AC line L1 and L2 so that the first and second high voltage transformers HVT1 ( An AC power source AC is applied to the primary coil side of HVT2.

Accordingly, the first and second high voltage transformers HVT1 and HVT2 output a high voltage through a secondary coil to drive the first and second magnetrons MGT1 and MGT2, and the magnetrons MGT1 and MGT2. The food is heated / cooked by the microwaves emitted from).

In addition, when an overcurrent occurs due to the load circuit 10 and the first and second high voltage transformers HVT1 and HVT2, each fuse FUSE1 corresponding to each closed circuit is melted to cut off the overcurrent. Done.

However, in the conventional high-power microwave driving circuit operated as described above, assuming that only the second fuse FUSE2 is melted due to an overcurrent occurring, the closed circuit including the third and fourth commercial AC lines L3 and L4. The current can be interrupted, but other closed circuits of the first and second commercial alternating lines (L1) (L2) can continue to maintain power supply. As a result, when it is used without knowing this, only the circuits of the third and fourth commercial alternating lines L3 and L4 are opened, and by the power supplied through the first and second commercial alternating lines L1 and L2. When the first magnetron MTG1 is driven, heat applied to the cooking object per unit time is reduced, so that normal cooking cannot be performed.

The present invention was devised to improve the above problems, and to provide a microwave driving circuit for preventing a plurality of magnetrons are driven in any one of the fuses due to overcurrent.

1 is a view showing a conventional microwave driving circuit.

2 is a view showing a microwave driving circuit according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: microcomputer 2: relay driver

10: Load circuit FUSE10, FUSE20: Fuse

node1, node2: Connection points L1 to L4: Commercial exchange line

TCO1, TCO2: Temperature sensor LVT: Low voltage transformer

SW1, SW2: Door switch SW3, SW4: Monitor switch

HVT1, HVT2: High voltage transformer MGT1, MGT2: Magnetron

HVC1, HVC2: High Voltage Capacitor HVD1, HVD2: High Voltage Diode

RY1, RY2: relay

The microwave driving circuit according to the present invention for achieving this object is to transform the AC power input to the low voltage transformer to be applied to the load circuit including the relay driver controlled by the microcomputer and the microcomputer, and by transforming the AC power A microwave driving circuit having a plurality of high voltage transformers applied to a corresponding magnetron and a plurality of relays to switch the AC power to each of the high voltage transformers in response to a relay driving signal provided from the relay driver. A first fuse installed on the low voltage transformer and the common current path path to the plurality of high voltage transformers connected in parallel from each other; And a second fuse installed on the common current path path from the first fuse to the low voltage transformer and any one of the high voltage transformers.

Hereinafter, a microwave driving circuit according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a view showing a high-power microwave driving circuit according to a preferred embodiment of the present invention. Elements of the same function as in Fig. 1 are denoted by the same reference numerals.

Referring to the drawings, one end of the first and second commercial AC lines L1 and L2 is connected to a commercial AC power input terminal AC 110V or 220V, and the other end thereof is 1 of the first high voltage transformer HVT1. It is connected to the car coil.

A first fuse FUSE ₁₀ is connected between the first commercial AC line L1 and the first high voltage transformer HVT1.

One end of the third and fourth commercial AC lines L3 and L4 is connected to the commercial AC power input terminal, and the other end thereof is connected to the primary coil of the second high voltage transformer HVT2.

The first high voltage transformer HVT1 and the second high voltage transformer HVT2 are connected in parallel to a commercial AC power supply AC 110V or 220V input terminal.

The third commercial exchange line L3 is connected from the first commercial exchange line L1 via the first fuse FUSE ₁₀ and the second fuse FUSE ₂₀ , and the fourth commercial exchange line L4 is connected to the second commercial exchange line L4. It is connected in parallel with the commercial AC line L2.

The low voltage transformer LVT is connected between the first commercial AC line L1 and the second commercial AC line L2 so as to receive electric power through the first fuse FUSE ₁₀ and the second fuse FUSE ₂₀ .

Meanwhile, the first and second door switches SW1 and SW2 and the first and second monitor switches SW3 and SW4 are connected in series to the first and second commercial AC lines L1 and L3, respectively. Is connected. The first and second relays RY1 and RY2 are connected to the second commercial alternating line L2 and the fourth commercial alternating line L4, respectively.

Low voltage transformer between the first node node1 between the first fuse FUSE10 and the first door switch SW1 and the second node node2 between the second commercial AC line L2 and the first relay RY1. LVT and the first and second temperature sensors TCO1 and TCO2 are connected.

The load circuit 10 is connected to the secondary coil side of the low voltage transformer LVT. The load circuit 10 includes a microcomputer 1 and a relay driver 2 for driving the first and second relays RY1 and RY2 according to signals output from the microcomputer 1 and the microcomputer 1. The load circuit 10 includes a lamp, a fan motor, a timer, and the like, not shown.

In this circuit structure, the second fuse FUSE ₂₀ is melted when an overcurrent flows through the low voltage transformer LVT and / or the second high voltage transformer HVT2.

The first fuse FUSE20 is melted when an overcurrent for the entire driving circuit flows to the first commercial AC line which becomes the common current path path of the entire driving circuit.

Preferably, the first fuse FUSE10 accommodates the amount of current flowing through the first commercial AC line L1 corresponding to the rated power range of the first and second high voltage transformers HVT1 and HVT2 and the low voltage transformer LVT. The second fuse FUSE20 sets the appropriate capacity to perform the operation, and the second fuse FUSE20 receives the third node node3 from the first node node1 corresponding to the rated power range of the low voltage transformer LVT and the second high voltage transformer HVT2. Set an appropriate capacity to accommodate the amount of current to be supplied. As an example, the second fuse applies a dose that is about 1/2 of the determined first fuse dose.

On the secondary coil side of the first and second high voltage transformers (HVT1) and (HVT2), a high pressure capacitor (HVC1) (HVC2), a high voltage diode (HVD1) (HVD2) and a magnetron (MGT1) (MGT2) for generating microwaves are respectively. Prepared.

The first and second relays RY1 and RY2 are turned on and off by the microcomputer 1 and the relay driver 2 to supply a commercial AC power source to the first and second high voltage transformers HVT1 and HVT2. Allow the supply of AC) to be switched.

Referring to the operation of the microwave driving circuit according to the present invention configured as described above in more detail.

First, when a commercial AC power is applied to the low-range driving circuit, power is supplied to the load circuit 10 by the power supplied to the low voltage transformer LVT. The microcomputer 1 and the relay driver 2 are activated by the power supplied to the load circuit 10.

The first and second door switches SW1 and SW2 and the first and second monitor switches SW3 and SW4 are turned on under the control of the microcomputer 1 and the relay driver 2. When the two relays RY1 and RY2 are turned on, the AC power source AC is applied to the primary coil side of the first and second high voltage transformers HVT1 and HVT2.

Accordingly, the first and second high voltage transformers HVT1 and HVT2 output high voltages through the secondary coils to drive the first and second magnetrons MTG1 and MGT2, and the first and second magnetrons The food is heated / cooked by the microwaves emitted from MGT1) (MGT2) as described above through the prior art.

In the state where the microwave oven for high power is driven as described above, when an overcurrent occurs due to the load circuit 10 and the first and second high voltage transformers HVT1 and HVT2, the first fuse FUSE10 has its own. Beyond capacity leads to disconnection. Therefore, since the current supply path to each closed circuit constituting the driving circuit passes through the first commercial AC line L1, the power supply to the entire circuit is cut off when the first fuse FUSE10 is disconnected.

In other words, when the first monitor switch SW3 is connected to A as shown in FIG. 2 and the first door switch SW1 is forcibly turned on while the first relay RY1 is short-circuited, the first fuse FUSE10) is broken. As a result, the microwave stops operating because no current is supplied to the entire circuit.

On the other hand, if an overcurrent exceeding the capacity of the second fuse FUSE20 occurs without exceeding the capacity of the first fuse FUSE10 by the load circuit 10 or the second high voltage transformer HVT2, The second fuse FUSE20 is disconnected while the first fuse FUSE10 is maintained. When the second fuse FUSE20 is disconnected, the power supply to the load circuit 10 is cut off, and as a result, the first and second relays RY1 and RY2 are automatically opened due to the malfunction of the microcomputer and the relay driver. It becomes a state. That is, even if only the second fuse FUSE20 is disconnected, power supply to the entire circuit is cut off by opening the first and second relays RY1.

Therefore, even if only one fuse FUSE10 or FUSE20 of the first and second fuses FUSE10 and FUSE20 is melted, the driving circuit is in an open circuit state and the device is stopped.

As described above, according to the high-power microwave driving circuit according to the present invention, the power supply of the entire circuit is cut off against the overcurrent inflow into any one of a plurality of circuits connected to be diverted from the commercial AC power supply. It can suppress the damage of equipment by over current.

Claims (1)

A low voltage transformer for converting an input AC power to a load circuit including a microcomputer and a relay driver controlled by the microcomputer, and a plurality of high voltage transformers for converting the AC power to the corresponding magnetrons and the relay driver In the microwave driving circuit having a plurality of relays for switching the AC power to each of the high voltage transformer in response to a given relay driving signal, A first fuse installed on the low voltage transformer connected in parallel from the AC power supply and on a common current path path to the plurality of high voltage transformers; And And a second fuse installed on the common current path path from the first fuse to the low voltage transformer and any one of the high voltage transformers.