CN204013267U - A kind of control circuit of thermatron - Google Patents
A kind of control circuit of thermatron Download PDFInfo
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- CN204013267U CN204013267U CN201420336167.0U CN201420336167U CN204013267U CN 204013267 U CN204013267 U CN 204013267U CN 201420336167 U CN201420336167 U CN 201420336167U CN 204013267 U CN204013267 U CN 204013267U
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- 230000010355 oscillation Effects 0.000 claims abstract description 7
- 230000000052 comparative effect Effects 0.000 claims description 18
- 238000001514 detection method Methods 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
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Abstract
A control circuit for thermatron, comprising: switch element drive waveforms Circuit tuning, the input of external power control signal and MCU controller; Switch element drive waveforms Circuit tuning comprises the first bleeder circuit, operational amplifier, the second bleeder circuit and the first comparator; The first bleeder circuit is an input that is applicable to the Rectified alternating current of operational amplifier work and outputs to operational amplifier by the Rectified alternating current reduced output voltage of full-wave rectifying circuit output; Another input of operational amplifier is connected with the output of external power control signal by MCU controller; Two inputs of the first comparator are respectively with the output of operational amplifier with is connected the connection of oscillation control signal output circuit; The output of comparator is connected with the control utmost point of switch element by switch element driver circuit; The drive waveforms that this circuit output duty cycle changes, the peak-inverse voltage while reducing switch element cut-off, the power factor (PF) of having improved power supply, raising power work efficiency.
Description
Technical field
The utility model relates to a kind of drive circuit, relates in particular to a kind of drive circuit of thermatron.
Background technology
Insulated gate twin-stage transistor npn npn (IGBT) is the switching device that is widely used in the big or middle power circuit of high frequency.In driving inverter, IH electromagnetic cooker, Switching Power Supply product, there is utilization at domestic environments electromagnetic oven, microwave oven magnetic.Conventionally insulated gate bipolar transistor can produce peak voltage in the course of work in the time that conducting becomes cut-off, in the situation that input service voltage is high, peak voltage is larger especially, this voltage easily causes insulated gate bipolar transistor breakdown and damage, and occurs product failure.In addition,, due to the existence of surge, in the time that surge arrives, if insulated gate bipolar transistor is still in running order, can cause punch through damage because of the voltage sharply raising.
Utility model content
Technical problem underlying to be solved in the utility model has been to provide a kind of control circuit of thermatron, the duty that can export driving switch element in the time of pulsating dc voltage low ebb is large, the little drive waveforms of driving switch element duty when the high paddy of pulsating dc voltage.
Less important technical problem to be solved in the utility model is to provide a kind of control circuit of thermatron, is meeting under the prerequisite of above-mentioned requirements, can in the time that surge arrives, remain cut-off by driving switch element.
In order to solve above-mentioned technical problem, the utility model provides a kind of control circuit of thermatron, comprising: switch element drive waveforms Circuit tuning, the input of external power control signal and MCU controller;
Described switch element drive waveforms Circuit tuning comprises the first bleeder circuit, operational amplifier, the second bleeder circuit and the first comparator;
Described the first bleeder circuit is an input that is applicable to the Rectified alternating current of described operational amplifier work and outputs to described operational amplifier by the Rectified alternating current reduced output voltage of full-wave rectifying circuit output; Another input of described operational amplifier is connected with described external power control signal input by described MCU controller; The output of described operational amplifier is by described the second bleeder circuit and an input that is connected to described the first comparator, and another input of described the first comparator connects oscillation control signal output circuit; The output of described the first comparator is connected with the control utmost point of switch element by switch element driver circuit; The drive waveforms that described switch element drive waveforms Circuit tuning output duty cycle changes, the duty that is embodied in driving switch element in the time of pulsating dc voltage low ebb is large, when the high paddy of pulsating dc voltage, driving switch element duty is little, peak-inverse voltage when control circuit effectively reduces switch element cut-off, the power factor (PF) of having improved power supply, raising power work efficiency.
In a preferred embodiment: also comprise surge protection circuit; Described surge protection circuit is provided with the second comparator and reset circuit, and the comparison input of described the second comparator is connected with reference voltage and comparative voltage respectively; The output of described the second comparator is connected with the control utmost point of switch element by described switch element driver circuit; Described comparative voltage is during lower than described reference voltage, and described surge protection circuit is not worked; When surge arrives, described comparative voltage is higher than described reference voltage, and described the second comparator is pulled low to all the time described reference voltage lower than described comparative voltage by feedback element, thereby drives described switch element to remain cut-off; After surge finishes, described reset circuit drives described reference voltage to reset.
In a preferred embodiment: be connected with diode between the output of described the second comparator and described switch element driver circuit, described diode is closed during lower than described reference voltage at described comparative voltage, in the conducting during higher than described reference voltage of described comparative voltage.
In a preferred embodiment: described reset circuit comprises switching tube, the control utmost point of described switching tube is connected with described MCU controller, grounded emitter, and collector electrode compares input with the negative pole of described the second comparator and is connected.
In a preferred embodiment: described oscillation control signal output circuit comprises sync detection circuit and oscillator, the input of described sync detection circuit is connected to the collector electrode of described switch element.
In a preferred embodiment: described switch element is insulated gate bipolar transistor.
In a preferred embodiment: high frequency triangle wave or sawtooth waveforms that described oscillator output frequency is 20kHz-60kHz.
Compared to prior art, the technical scheme that the utility model provides possesses following beneficial effect:
1. the control circuit of a kind of thermatron that the utility model provides, the duty that can export driving switch element in the time of pulsating dc voltage low ebb is large, the little drive waveforms of driving switch element duty when the high paddy of pulsating dc voltage.Make switch element ON time in the time of high voltage short, when low-voltage, ON time is long.The crest voltage that switch element is produced in the time of cut-off effectively reduces, and has avoided too high crest voltage that switch element is punctured.
2. the control circuit of a kind of thermatron that the utility model provides, the duty that can export driving switch element in the time of pulsating dc voltage low ebb is large, the little drive waveforms of driving switch element duty when the high paddy of pulsating dc voltage.Make outputting drive voltage waveform more level and smooth, improved power factor and efficiency.
3. the duty of driving switch element is large when being embodied directly in pulsating dc voltage low ebb by MCU, the drive waveforms mode that when the high paddy of pulsating dc voltage, driving switch element duty is little, because MCU is difficult to realize the control of output duty cycle linear change, can produce in the course of the work larger operating noise.The technical scheme that the utility model provides can realize the control of output duty cycle linear change, has reduced circuit working noise.
4. the control circuit of a kind of thermatron that the utility model provides; also comprise surge protection circuit; in the time that arriving, surge drive described switch element to remain cut-off; thereby utilize switch element not allow flimsy advantage in the time of cut-off, effectively avoided the switch element causing because of surge to damage.
Brief description of the drawings
Fig. 1 is the integrated circuit schematic diagram of the utility model preferred embodiment;
Fig. 2 is rectification circuit output waveform figure in the utility model preferred embodiment;
Fig. 3 is operational amplifier output waveform figure in the utility model preferred embodiment;
Fig. 4 is the input oscillogram of the first comparator in the utility model preferred embodiment;
Fig. 5 is the output waveform figure of the first comparator in the utility model preferred embodiment;
Embodiment
Below with specific embodiment, the utility model is described further by reference to the accompanying drawings.
With reference to figure 1, a kind of control circuit of thermatron, comprising: switch element drive waveforms Circuit tuning 1, the input 2 of external power control signal and MCU controller 3;
Described switch element drive waveforms Circuit tuning 1 comprises the first bleeder circuit 11, operational amplifier 12, the second bleeder circuit 13 and the first comparator 14;
Described the first bleeder circuit 11 comprises the resistance R 15, the R16 that are connected in series, and the Rectified alternating current reduced output voltage that full-wave rectifying circuit 15 is exported is to be applicable to described operational amplifier 12 Rectified alternating current of working the negative input that outputs to described operational amplifier 12; The electrode input end of described operational amplifier 12 is connected with described external power control signal input 2 by described MCU controller 3; The negative input that the output of described operational amplifier 12 is connected to described operational amplifier 12 by feedback resistance R11 forms feedback; In the present embodiment, between described MCU controller 3 and the electrode input end of operational amplifier 12, be connected with filter capacitor C6 and resistance R 13, R14.
The output of described operational amplifier 12 is by described the second bleeder circuit 13 and the electrode input end that is connected to described the first comparator 14, and the electrode input end of described the first comparator 14 is by anti-interference capacitor C5 ground connection; Described the second bleeder circuit 13 comprises resistance R 9, the R10 that series winding connects; The negative input of described the first comparator 14 connects oscillation control signal output circuit; In the present embodiment, described oscillation control signal output circuit comprises sync detection circuit and oscillator, and the input of described sync detection circuit is connected to the collector electrode of switch element Q1, and in the time of switch element Q1 conducting, grounded collector voltage is 0; The high frequency triangle wave that described oscillator output frequency is 20kHz-60kHz.The output of described the first comparator 14 is connected with the control utmost point of switch element Q1 by switch element driver circuit.
With reference to figure 2-Fig. 5, the workflow of described switch element drive waveforms Circuit tuning 1:
Fig. 2 is the Rectified alternating current oscillogram of exporting after full-wave rectification, and the pulsating direct current electrical waveform of swinging to that this Rectified alternating current is exported after the first bleeder circuit 11 and operational amplifier 12 as shown in Figure 3.After the second bleeder circuit 13, described first electrode input end of comparator 14 and the waveform of negative input are as shown in Figure 4, because the first comparator 14 is exported high level in the time that the voltage of electrode input end is greater than the voltage of negative input, so the drive waveforms of the output of described the first comparator 14 output as shown in Figure 5, from scheming, can find out the drive waveforms that described switch element drive waveforms Circuit tuning 1 output duty cycle changes, the duty that is embodied in driving switch element in the time of pulsating dc voltage low ebb is large, when the high paddy of pulsating dc voltage, driving switch element duty is little.Make switch element Q1 ON time in the time of high voltage short, when low-voltage, ON time is long.The crest voltage that switch element is produced in the time of cut-off effectively reduces, and has avoided too high crest voltage that switch element Q1 is punctured.Meanwhile, the drive waveforms of this change in duty cycle can make the driving voltage waveform of magnetron more level and smooth, has improved power factor and efficiency.Described switch element drive waveforms Circuit tuning 1 can be realized the control of output duty cycle linear change, effectively reduces the current noise existing in circuit.
In the present embodiment, described switch element Q1 is preferably IGBT (insulated gate bipolar transistor).
In the present embodiment, also comprise surge protection circuit 4; Described surge protection circuit 4 is provided with the second comparator 41 and reset circuit 42, and the positive pole of described the second comparator 41 relatively input is connected with reference voltage, and the negative pole of described the second comparator 41 relatively input is connected with comparative voltage.In the present embodiment, described reference voltage is set by series connection divider resistance R4, R5, between the input voltage and ground of described be connected to+5V of series connection divider resistance, the tie point of described series connection divider resistance R4, R5 compares input with the positive pole of described the second comparator 41 and is connected.In the present embodiment, the Rectified alternating current that described full-wave rectifying circuit 15 is exported forms described comparative voltage and is connected with the negative pole comparison input of described the second comparator 41 after divider resistance R2, R3.Between the positive pole comparison input of the output of described the second comparator 41 and described the second comparator 41, be connected with feedback diode D4 and form feedback.The output of described the second comparator 41 is connected with the control utmost point of switch element Q1 with described switch element driver circuit by the negative pole of diode D6.
Described comparative voltage is during lower than described reference voltage, and described the second comparator 41 is exported high level, cannot pass through diode D6, and now described surge protection circuit is not worked.In the time that surge arrives, described comparative voltage is higher than described reference voltage, now described the second comparator 41 output low levels, by feedback diode D4, described reference voltage is pulled low to all the time lower than described comparative voltage, described the second comparator 41 is exported lasting low level, diode D6 conducting, thus drive described switch element Q1 to remain cut-off; After surge finishes, described reset circuit drives described reference voltage to reset.
In the present embodiment, described reset circuit 42 comprises switching tube Q2, and the grounded emitter of described switching tube Q2 is controlled the utmost point and is connected with described MCU controller 3, and collector electrode is connected with the negative input of described the second comparator 41.In the time that surge finishes, described MCU controller 3 drives described switching tube Q2 conducting, thereby makes the negative input ground connection of described the second comparator 41, and reference voltage is again higher than comparative voltage like this, the second comparator 41 is exported high level again, resets thereby realize reference voltage.
The above, it is only utility model preferred embodiment, not the technical scope of utility model is imposed any restrictions, therefore any trickle amendment that every foundation technical spirit of the present utility model is done above example, equivalent variations and modification, all still belong in the scope of technical solutions of the utility model.
Claims (7)
1. a control circuit for thermatron, is characterized in that comprising: switch element drive waveforms Circuit tuning, the input of external power control signal and MCU controller;
Described switch element drive waveforms Circuit tuning comprises the first bleeder circuit, operational amplifier, the second bleeder circuit and the first comparator;
Described the first bleeder circuit is an input that is applicable to the Rectified alternating current of described operational amplifier work and outputs to described operational amplifier by the Rectified alternating current reduced output voltage of full-wave rectifying circuit output; Another input of described operational amplifier is connected with described external power control signal input by described MCU controller; The output of described operational amplifier is by described the second bleeder circuit and an input that is connected to described the first comparator, and another input of described the first comparator connects oscillation control signal output circuit; The output of described the first comparator is connected with the control utmost point of switch element by switch element driver circuit; The drive waveforms that described switch element drive waveforms Circuit tuning output duty cycle changes, while being embodied in pulsating dc voltage low ebb, the duty of driving switch element is large, and when the high paddy of pulsating dc voltage, driving switch element duty is little.
2. the control circuit of a kind of thermatron according to claim 1, is characterized in that: also comprise surge protection circuit; Described surge protection circuit is provided with the second comparator and reset circuit, and the comparison input of described the second comparator is connected with reference voltage and comparative voltage respectively; The output of described the second comparator is connected with the control utmost point of switch element by described switch element driver circuit; Described comparative voltage is during lower than described reference voltage, and described surge protection circuit is not worked; When surge arrives, described comparative voltage is higher than described reference voltage, and described the second comparator is pulled low to all the time described reference voltage lower than described comparative voltage by feedback element, thereby drives described switch element to remain cut-off; After surge finishes, described reset circuit drives described reference voltage to reset.
3. the control circuit of a kind of thermatron according to claim 2, it is characterized in that: between the output of described the second comparator and described switch element driver circuit, be connected with diode, described diode is closed during lower than described reference voltage at described comparative voltage, in the conducting during higher than described reference voltage of described comparative voltage.
4. the control circuit of a kind of thermatron according to claim 2, it is characterized in that: described reset circuit comprises switching tube, the control utmost point of described switching tube is connected with described MCU controller, grounded emitter, and collector electrode compares input with the negative pole of described the second comparator and is connected.
5. the control circuit of a kind of thermatron according to claim 1, it is characterized in that: described oscillation control signal output circuit comprises sync detection circuit and oscillator, the input of described sync detection circuit is connected to the collector electrode of described switch element.
6. the control circuit of a kind of thermatron according to claim 1, is characterized in that: described switch element is insulated gate bipolar transistor.
7. the control circuit of a kind of thermatron according to claim 5, is characterized in that: high frequency triangle wave or sawtooth waveforms that described oscillator output frequency is 20kHz-60kHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420336167.0U CN204013267U (en) | 2014-06-23 | 2014-06-23 | A kind of control circuit of thermatron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420336167.0U CN204013267U (en) | 2014-06-23 | 2014-06-23 | A kind of control circuit of thermatron |
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| CN204013267U true CN204013267U (en) | 2014-12-10 |
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| CN201420336167.0U Expired - Fee Related CN204013267U (en) | 2014-06-23 | 2014-06-23 | A kind of control circuit of thermatron |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106470506A (en) * | 2015-08-17 | 2017-03-01 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and its switching tube open control device and method |
| CN106507523A (en) * | 2016-11-08 | 2017-03-15 | 烟台长青微波科技有限公司 | A kind of constant current mode microwave oven supply power |
-
2014
- 2014-06-23 CN CN201420336167.0U patent/CN204013267U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106470506A (en) * | 2015-08-17 | 2017-03-01 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and its switching tube open control device and method |
| CN106470506B (en) * | 2015-08-17 | 2023-02-17 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and switching-on control device and method of switch tube thereof |
| CN106507523A (en) * | 2016-11-08 | 2017-03-15 | 烟台长青微波科技有限公司 | A kind of constant current mode microwave oven supply power |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141210 |