CN204392616U - The electric control circuit of frequency conversion type microwave oven - Google Patents

Abstract

The electric control circuit of frequency conversion type microwave oven, relates to microwave oven.Be provided with filter circuit, control circuit, high-voltage conversion circuit, magnetron thermostat, the 1st interlocking switch, fan motor, turntable motor, heating system, the 2nd interlocking switch, pilot switch, magnetron, the input outside electric power network power supply of described filter circuit, the N line output terminal of filter circuit connects magnetron thermostat, the input of the L line output terminal connection control circuit of filter circuit, the output of control circuit respectively with pilot bulb, interlocking switch, fan motor, turntable motor, heating system, pilot switch connects, the output of control circuit is respectively by ground wire, signal control line is connected with high-voltage conversion circuit with signal feedback line, signal control line is for sending the startup and power adjustments that control microwave, whether signal feedback line feedback high tension transformer normally works and operating state, the High voltage output termination magnetron of high-voltage conversion circuit, and passed in microwave oven cavity by magnetron generation microwave.

Description

The electric control circuit of frequency conversion type microwave oven

Technical field

The utility model relates to microwave oven, especially relates to a kind of electric control circuit of frequency conversion type microwave oven.

Background technology

Microwave oven is a kind of cooking tools being different from traditional heating mode completely, and the history be born from First microwave oven existing more than 60 year so far, now very universal, its development has brought many convenience.Raytheon Co. of U.S. technician amber west in 1945. spencer finds that microwave energy makes surrounding objects generate heat, and nineteen forty-seven, Raytheon Co. was proposed First household microwave oven by the inspiration that spencer is tested.1967, microwave oven news briefing fair of holding concurrently was held in Chicago, obtained immense success.From then on, microwave oven progresses into huge numbers of families.Microwave oven becomes an invention of great significance of for a change human lives.The culinary art effect that microwave oven is outstanding, becomes the cooking tools that the modern life is important.The whole world is approximately the competition that 6,000 ten thousand microwave oven markets facilitate factory every year.For meeting the requirement in market, constantly strengthening the function of microwave oven, and controlling cost of material as much as possible.The raising of human living standard is also had higher requirement to product.Present microwave oven cooking mode is various, can do various ambrosia.Now continually develop out the microwave oven of the various function combination such as grill microwave oven, microwave oven with light wave, purple light microwave oven, steam microwave oven.Design the hommization that more becomes, the new technology such as touch-controlled key, distant control function, large scale display, voice message, networking is constantly applied to the development and Design of new microwave oven.

Along with people are to environmental protection and energy saving consciousness and improving constantly product quality requirement, along with the development of converter technique, frequency-conversion microwave oven also appears in face of people.It is the perfect adaptation of microwave oven and frequency conversion two kinds of technology, enhances new power to the development of microwave oven.In September, 2000, the state-of-the-art technology frequency-conversion microwave oven listing in microwave oven company of Shanghai National September.Start the application of converter technique on microwave oven.Frequency-conversion microwave oven represents the direction of world's microwave oven development, frequency-conversion microwave oven utilizes high-frequency electrical energy to drive to the boosting of magnetron necessity, and power supply architecture is little, and furnace inner space is more spacious, microwave oven makes Microwave emission power output obtain free adjustment, make heat foods more even, and select best mode of heating according to different food products, the food mouthfeel of culinary art is better, nutrition preserves at most, compared with traditional microwave oven, it is light that frequency-conversion microwave oven has fuselage, and noise is low, power-saving feature.

Summary of the invention

The purpose of this utility model is the electric control circuit providing a kind of frequency conversion type microwave oven.

The utility model is provided with filter circuit, control circuit, high-voltage conversion circuit, magnetron thermostat, the 1st interlocking switch, fan motor, turntable motor, heating system, the 2nd interlocking switch, pilot switch, magnetron;

The input outside electric power network power supply of described filter circuit, the N line output terminal of filter circuit connects magnetron thermostat, the input of the L line output terminal connection control circuit of filter circuit, the output of control circuit respectively with pilot bulb, 1st interlocking switch, fan motor, turntable motor, heating system, 2nd interlocking switch, pilot switch connects, the output of control circuit is respectively by ground wire, signal control line is connected with high-voltage conversion circuit with signal feedback line, signal control line is for sending the startup and power adjustments that control microwave, whether signal feedback line feedback high tension transformer normally works and operating state, the High voltage output termination magnetron of high-voltage conversion circuit, and pass in microwave oven cavity by magnetron generation microwave, 2nd interlocking switch is used for the detection of microwave oven door state.

The utility model adopts interference signal on filter circuit filtering electrical network, and the interference simultaneously suppressing microwave oven to produce enters electrical network, for each system provides electric energy after power filter completes; Control circuit, according to the operation of user, controls the work of whole microwave oven; High-voltage conversion circuit, under the control of control circuit, produces high tension voltage and current signal to magnetron, simultaneously also by the control of feedback controlled circuit; The microwave that magnetron produces imports in microwave oven cavity, heats food; Fan motor dispels the heat to high-voltage conversion circuit and magnetron under the control of control circuit; During heat foods, driven by rotary disc food rotates, and during oven door opening, illuminating lamp lights; Heating system is controlled by control circuit; Microwave oven cavity is containing foodstuff and microwave energy is the place of heat energy.

Control circuit can adopt EM78P447NBWM type 8 single-chip microcomputers.Magnetron can adopt Panasonic 2M236-M42 type frequency shift magnetron.

The utility model is in the circuit design of frequency-conversion microwave oven, and for avoiding occurring that heavy current switches during relay on-off, have employed the soft switch technique of zero passage break-make, this technology substantially reduces the EMI signal of product.In order to ensure under any circumstance use safety, have employed relay dual-drive technology, this technology can ensure that zero microwave exports in abnormal cases.In order to make user have better man-machine interface, have employed buzzer decay sound control system, making prompt tone soft and interesting to listen to; Adopt rotary encoder to carry out the power setting of microwave oven, make the more convenient use of microwave oven, conditioning performance is more perfect.

Control circuit good stability of the present utility model, can completely normally under the interference of normal electrical network work; Make microwave oven safety good, can not dangerously occur during normal or non-normal use user; User can operate very easily and uses and repeatedly need not see operation instruction; Therefore make microwave oven operating efficiency high, energy savings, conditioning speed is fast.

Accompanying drawing explanation

Fig. 1 is the structure composition schematic diagram of the utility model embodiment;

Fig. 2 is the filter circuit schematic diagram of the utility model embodiment;

Fig. 3 is total electrical connection diagram of the utility model embodiment;

Fig. 4 is the relay circuit schematic diagram of the utility model embodiment;

Fig. 5 is the buzzer drive circuit schematic diagram of the utility model embodiment;

Embodiment

Below in conjunction with drawings and Examples, the utility model is described in further detail.

See Fig. 1, the utility model is provided with filter circuit 1, control circuit 2, high-voltage conversion circuit 3, magnetron thermostat 4, the 1st interlocking switch S2, fan motor B1, turntable motor B2, heating system 5, the 2nd interlocking switch S1, pilot switch S3, magnetron 6, the input outside electric power network power supply of described filter circuit 1, the N line output terminal of filter circuit 1 connects magnetron thermostat 4, the input of the L line output terminal connection control circuit 2 of filter circuit 1, the output of control circuit 2 respectively with pilot bulb DS1, 1st interlocking switch S2, fan motor B1, turntable motor B2, heating system 5, 2nd interlocking switch S1, pilot switch S3 connects, the output of control circuit 2 is respectively by ground wire, signal control line is connected with high-voltage conversion circuit 3 with signal feedback line, signal control line is for sending the startup and power adjustments that control microwave, whether signal feedback line feedback high tension transformer normally works and operating state, the High voltage output termination magnetron 6 of high-voltage conversion circuit 3, and produce microwave by magnetron 6 and pass in microwave oven cavity, 2nd interlocking switch S1 is used for the detection of microwave oven door state.

For making working stability reliable, this circuit adopts the filter circuit figure as Fig. 2, and Fuse1 is that current insurance silk does short circuit or the protection of other circuit abnormalities, and VAR piezo-resistance absorbs the High Pressure Difference mode noise signal because thunderbolt or other reasons produce.C1 capacitive absorption differential mode noise signal.Resistance R1 is for the release to electric capacity aftercurrent during unplugg.Inductance L 1 is for suppressing common mode noise signal.Electric capacity C2, C3 are for absorbing common mode noise signal.

Fig. 3 is the electrical connection diagram of whole microwave oven, comprises control circuit, high-voltage conversion circuit and filter circuit.Electric network source L, N line is plugged in power line through three and is connected respectively on the splicing ear of Lin and Nin of microwave oven filter circuit.The ground wire of power line connects on the casing of microwave oven.Filter circuit is at the current insurance silk of the inlet wire termination 250V/15A of L.Power supply after filtering after on the magnetron thermostat (165 DEG C of thermostats) of N line tipping on magnetron, the Main Function of this thermostat is protection magnetron, and when magnetron exceeds 165 DEG C, thermostat disconnects, and ensures that the temperature of magnetron can not be too high.After crossing thermostat, N line is received on control circuit, bulb and the first interlocking switch.Control circuit power source is provided by this wiring and L line.1st interlocking switch S2 is major loop switch, and after door of microwave oven is opened, S2 disconnects, and being connected to fan motor thereafter, turntable motor, heater and high-voltage conversion circuit power supply will all be cut off.Bulb is to light to see clearly food in microwave oven cavity when controlling bulb after oven door opening before being connected on S2.One end of three relay contacts on control circuit is connected to the L line on filter circuit.Another termination bulb, fan and turntable motor of relay R Y2, control illumination, cooling and the rotation of food in cavity.The relay R Y1 other end is received on voltage conversion circuit, control the power supply of high pressure conversion plate, open rear S2 for avoiding the microwave oven door for microwave oven that the problem such as sensitive switch seat generation distortion or wearing and tearing causes after long-term use may not disconnect, microwave may not stop exporting, at high pressure conversion plate both ends of power normally closed sensitive switch S3 in parallel and pilot switch, if door S2 and RY1 does not disconnect when microwave oven is opened, S3 will, power supply short circuit, make the current insurance silk on filter band fuse.The thermostat of another termination of relay R Y3 75 DEG C receives electrothermal tube again, for controlling the heating of heating tube.75 DEG C of thermostats are as on micro-wave oven furnace chamber, and when ensureing to roast, cavity inner temperature can not be too high.2nd interlocking switch S1 is the sensitive switch often opened, and for the detection of MCU microwave oven door state, simultaneously as the Energy control of relay R Y1, RY3, the power supply of block system relay when door is opened, makes microwave and barbecue heater element not work.Control circuit carries out communication to voltage conversion circuit by three lines, is respectively GND line, signal control line and signal feedback line.Control line is for sending the startup and power adjustments that control microwave.Whether feedback line normally works for reacting high tension transformer, and working condition.The High voltage output of high-pressure generator terminates on magnetron, and the electromagnetic wave being produced 2450MHz by magnetron passes in microwave oven cavity again.

In microwave oven, each electronic unit of band forceful electric power all controls by relay.Because relay coil is inductive load, have lasting electric current exist when relay turns off, at relay two ends, also a switching diode, to be discharged by this electric current, avoids the triode producing back electromotive force impulsive control relay.Two the main relays controlling heating tube and high tension transformer power supply have all carried out multiple safety precautions.The power supply of two relays is linked on the power supply of 12V by the sensitive switch be arranged on sensitive switch seat again, has also cut off the power supply of two relays like this while door is opened.Two relays be two-way drive.The I/O of one route MCU is directly driven by resistance, triode, and another route MCU sends or do not send pulse and carries out master control (as shown in Figure 4) to C11.Q7 ability conducting when only having pulse to send, at this moment Q8, Q9 could be effectively to the control of two main relays.The emitter of Q8, Q9 is linked on Q7 triode by D8, and D8 shields equally to triode Q8, Q9, if do not have D8, when RELAY2 turns off, induced current will impact two triodes.

Microwave oven is in button assignment procedure and the course of work, and by the operating state of auditory tone cues microwave oven, sound has buzzer to produce.Because the buzzer sound requires the effect sending soft sound, the driving of buzzer is complicated relative to driven.Drive circuit, as Fig. 5, is sent the square wave of 2kHz by the rated frequency of buzzer by the I/O mouth of MCU, drive buzzer by resistance R16 and NPN triode Q5.The circuit be made up of resistance R10, R11, R12, R13, NPN triode Q4, PNP triode Q2 and electrochemical capacitor C2 provides power supply to buzzer.When buzzer will send sound, of short duration impulse level is sent by the buz_en pin of MCU, when buz_en pin is high level, + 12V can charge to C2 electric capacity provides power supply to buzzer simultaneously, when buz_en pin is low level, the power supply of buzzer is no longer provided by+12V, and the power supply of such buzzer will go down along with the decline decay of voltage when C2 discharges.So just can produce softer audio.When buzzer rings, the c pole tension waveform of C2 electric capacity and Q5 is all just started then to successively decrease gradually comparatively greatly, and therefore sound becomes soft thereupon.

Claims (1)

1. the electric control circuit of frequency conversion type microwave oven, is characterized in that being provided with filter circuit, control circuit, high-voltage conversion circuit, magnetron thermostat, the 1st interlocking switch, fan motor, turntable motor, heating system, the 2nd interlocking switch, pilot switch, magnetron;

The input outside electric power network power supply of described filter circuit, the N line output terminal of filter circuit connects magnetron thermostat, the input of the L line output terminal connection control circuit of filter circuit, the output of control circuit respectively with pilot bulb, 1st interlocking switch, fan motor, turntable motor, heating system, 2nd interlocking switch, pilot switch connects, the output of control circuit is respectively by ground wire, signal control line is connected with high-voltage conversion circuit with signal feedback line, signal control line is for sending the startup and power adjustments that control microwave, whether signal feedback line feedback high tension transformer normally works and operating state, the High voltage output termination magnetron of high-voltage conversion circuit, and pass in microwave oven cavity by magnetron generation microwave, 2nd interlocking switch is used for the detection of microwave oven door state.