CN202772558U - Excess temperature protection structure of microwave power device - Google Patents
Excess temperature protection structure of microwave power device Download PDFInfo
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- CN202772558U CN202772558U CN 201220487893 CN201220487893U CN202772558U CN 202772558 U CN202772558 U CN 202772558U CN 201220487893 CN201220487893 CN 201220487893 CN 201220487893 U CN201220487893 U CN 201220487893U CN 202772558 U CN202772558 U CN 202772558U
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- rectifier bridge
- thermistor
- microwave power
- power device
- gated transistor
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Abstract
The utility model discloses an excess temperature protection structure of a microwave power device. The excess temperature protection structure comprises a rectifier bridge, an insulated gate transistor and an IGBT driving circuit, wherein the rectifier bridge supplies power to the insulated gate transistor and an oscillation circuit of the insulated gate transistor, and an emitter of the insulated gate transistor is connected with a cathode of the rectifier bridge. The excess temperature protection structure is characterized in that the position of the cathode of the rectifier bridge is fixed and is electrically connected with one end of a thermistor RH, the other end of the thermal thermistor RH is connected with a temperature detection circuit, and the temperature detection circuit is provided with a feedback terminal which is connected with the IGBT driving circuit and can turn off the IGBT driving circuit. By using the property that the current of the insulated gate transistor and the rectifier bridge is in synchronous temperature rise under large current, a temperature detection point is arranged at the cathode of the rectifier bridge, and the overcurrent situation of the insulated gate transistor is indirectly reflected. The rectifier bridge does not have a long pin, so the thermistor can accurately reflect the temperature rise of a PN junction in a current loop, and proper protection is provided.
Description
Technical field
The utility model relates to a kind of its structure of thermal-shutdown circuit that applies to the household microwave oven power device.
Background technology
As the heating cooker of family expenses, microwave oven has obtained very general use, and its function is also perfect gradually, not only has heating function, and is also developed on fail safe, reliability, makes the more and more hommization of its function.
It is exactly the function that realizes protection that this class circuit has a main automatic measure, and in time rupturing duty device work when namely abnormal conditions occurring to such an extent as to close all heating functions, avoids fault to worsen, and causes extra device or personal injury.Especially, the device of this relatively high power, a primary function realizes overtemperature protection exactly, because the overheated situation that usually means short circuit, large electric current is also the most easily caused danger.Overtemperature protection need to be carried out temperature monitoring to power device, realizes can in time being cut off power supply when the temperature rise of power device surpasses margin of safety.In microwave oven apparatus, a main power device is exactly the gated transistor that drives magnetron work.Common temperature detection mode is to change gated transistor temperature element of its emitter position welding on printed circuit board (PCB), and when its PN junction excess Temperature, heat can import printed circuit board (PCB) by pin, and is in time responded to by the thermometric element.
These class methods have advantage simple in structure, reliable.But gated transistor often pin is longer, gated transistor integral body when work is subject to the radiating treatment of air blast cooling simultaneously, so, the terminal part that is connected with printed circuit board (PCB) of its pin deviation will occur as the point for measuring temperature of its PN junction, and the impact that this deviation also can be subject to the active heat removal air blast cooling is difficult to stablize.
The utility model content
For the above-mentioned problem that affected by air blast cooling for the temperature detection scheme of gated transistor, the utility model proposes a kind of overheat protector structure of microwave power device, its technical scheme is as follows:
The overheat protector structure of microwave power device, comprise a rectifier bridge, a gated transistor and IGBT drive circuit, wherein this rectifier bridge is powered to the oscillating circuit at this gated transistor and place, and the emitter of this gated transistor is connected with the negative pole of this rectifier bridge; Fix and be electrically connected the end of a thermistor RH in the position of the negative pole pin of this rectifier bridge, the other end of this thermistor RH is connected in a temperature sensing circuit; And this temperature sensing circuit has the feedback end that connects and can turn-off this IGBT drive circuit.
As the preferred person of the technical program, can have improvement aspect following:
In the preferred embodiment, this temperature sensing circuit comprises:
Divider resistance R1, the rear potential-divider network that consists of of connecting with this thermistor RH is connected between power supply and the ground;
Comparator OP1, its output forward connects diode D1, and diode D1 is connected in the base stage of switching tube Q1 by base resistance R4, and simultaneously by a resistance R 5 ground connection; The grounded emitter of this switching tube Q1, collector electrode connects this feedback end;
Wherein, the input of this comparator OP1 connects the potential-divider network dividing point of a R2 and R3 formation, and another input connects its dividing point of potential-divider network that is made of R1 and RH; This thermistor RH two ends also have a filter capacitor C1.
In the preferred embodiment, this thermistor RH is a PTC or NTC thermistor.
In the preferred embodiment, this feedback end is connected in the drive circuit 10, the grid control signal end of this IGBT.
In the preferred embodiment, this bridge heap and this gated transistor have the radiator that can be used for the active air cooling heat radiation.
The beneficial effect that the utility model brings is:
1. utilize electric current synchronous character that heats up under large electric current of gated transistor and rectifier bridge, temperature detecting point is arranged at the negative pole of rectifier bridge, thereby has indirectly reflected the overcurrent condition of gated transistor.
2. rectifier bridge can not have long pin, so thermistor can reflect the temperature rise of PN junction in the current circuit more exactly, provides appropriate protection.
Description of drawings
The utility model is described in further detail below in conjunction with accompanying drawing embodiment:
Fig. 1 is the utility model one embodiment general structure schematic diagram;
Fig. 2 is the schematic diagram of its temperature sense circuit 30 parts embodiment illustrated in fig. 1.
Embodiment
As depicted in figs. 1 and 2, the schematic diagram of the utility model one embodiment.
The overheat protector structure of this microwave power device, comprise a rectifier bridge 20, a gated transistor T1 and IGBT drive circuit 10, these rectifier bridge 20 output DCs wherein, by filter inductance L oscillating circuit C, the L1 at this gated transistor T1 and place are powered, and the emitter of this gated transistor T1 is connected with the negative pole of this rectifier bridge 20; Fix and be electrically connected the end of a thermistor RH in the position of the negative pole of this rectifier bridge 20, the other end of this thermistor RH is connected in a temperature sensing circuit 30; And this temperature sensing circuit 30 has the feedback end 31 that connects and can turn-off this IGBT drive circuit.
The technical program is carried out temperature detection to the negative pole of rectifier bridge 20.Its principle considers that rectifier bridge 20 adopts the setting of connecting with gated transistor T1, therefore its size of current is suitable, thereby when large current anomaly appearred in gated transistor T1, the electric current of rectifier bridge 20 also must increase, and rectifier bridge 20 is heated up rapidly.Utilize this character, just temperature detecting point can be arranged at the negative pole of rectifier bridge 20, thereby indirectly reflected the overcurrent condition of gated transistor T1.On the other hand, because gated transistor T1 goes pin itself longer, so the impact that is subject to air blast cooling is larger, if thermistor RH is placed the position of gated transistor T1 emitter, then the inner PN junction itself of itself and gated transistor T1 has the larger temperature difference.And rectifier bridge 20 itself can not have long pin usually; so; by the negative pole at this class rectifier bridge 20 thermistor is set; can reflect more exactly the temperature rise of PN junction in the current circuit; to such an extent as to the feedback end 31 by temperature sensing circuit 30 provides feedback signal to drive circuit 10; in time turn-off gated transistor T1, appropriate protection is provided.
In the present embodiment, this temperature sensing circuit 30 comprises:
Divider resistance R1, the rear potential-divider network that consists of of connecting with this thermistor RH is connected in power supply and the ground;
Comparator OP1, its output forward connects diode D1, the base stage that diode D1 is connected in switching tube Q1 by base resistance R4 just, and simultaneously by a resistance R 5 ground connection; The grounded emitter of this switching tube Q1, collector electrode connects this feedback end; The input of this comparator OP1 connects the potential-divider network dividing point of a R2 and R3 formation, and another input connects its dividing point of potential-divider network that is made of R1 and RH; This thermistor RH two ends also have a filter capacitor C1.And this thermistor RH is a thermistor.Feedback end 31 is connected in the drive circuit 10, the grid control signal end of this IGBT.As seen, this circuit is simple, and is highly sensitive, and adopts comparator to process the temperature sampling result of thermistor RH, directly drags down the grid control current potential of gated transistor T1 when defencive function starts by switching tube Q1, reaches the purpose of rapid protection.
The above, it only is the utility model preferred embodiment, therefore can not limit according to this scope that the utility model is implemented, the equivalence of namely doing according to the utility model claim and description changes and modifies, and all should still belong in the scope that the utility model contains.
Claims (5)
1. the overheat protector structure of microwave power device, comprise a rectifier bridge, a gated transistor and IGBT drive circuit, wherein this rectifier bridge is powered to the oscillating circuit at this gated transistor and place, and the emitter of this gated transistor is connected with the negative pole of this rectifier bridge; It is characterized in that: fix and be electrically connected the end of a thermistor RH in the position of the negative pole pin of this rectifier bridge, the other end of this thermistor RH is connected in a temperature sensing circuit; And this temperature sensing circuit has the feedback end that connects and can turn-off this IGBT drive circuit.
2. the overheat protector structure of described microwave power device according to claim 1, it is characterized in that: this temperature sensing circuit comprises:
Divider resistance R1, the rear potential-divider network that consists of of connecting with this thermistor RH is connected between power supply and the ground;
Comparator OP1, its output forward connects diode D1, and diode D1 is connected in the base stage of switching tube Q1 by base resistance R4, and simultaneously by a resistance R 5 ground connection; The grounded emitter of this switching tube Q1, collector electrode connects this feedback end;
Wherein, the input of this comparator OP1 connects the potential-divider network dividing point of a R2 and R3 formation, and another input connects its dividing point of potential-divider network that is made of R1 and RH; This thermistor RH two ends also have a filter capacitor C1.
3. the overheat protector structure of described microwave power device according to claim 2, it is characterized in that: this thermistor RH is a NTC or PTC thermistor.
4. according to claim 1 and 2 or the overheat protector structure of 3 described microwave power devices, it is characterized in that: this feedback end is connected in the drive circuit 10, the grid control signal end of this IGBT.
5. the overheat protector structure of described microwave power device according to claim 4, it is characterized in that: this bridge heap and this gated transistor have the radiator that can be used for the active air cooling heat radiation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220487893 CN202772558U (en) | 2012-09-20 | 2012-09-20 | Excess temperature protection structure of microwave power device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220487893 CN202772558U (en) | 2012-09-20 | 2012-09-20 | Excess temperature protection structure of microwave power device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202772558U true CN202772558U (en) | 2013-03-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220487893 Expired - Fee Related CN202772558U (en) | 2012-09-20 | 2012-09-20 | Excess temperature protection structure of microwave power device |
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| CN (1) | CN202772558U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105490253A (en) * | 2014-10-10 | 2016-04-13 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system, over-temperature protection method and device for power device of electromagnetic heating system |
| CN108306258A (en) * | 2018-04-04 | 2018-07-20 | 奥然生物科技（上海）有限公司 | A kind of excess temperature detection circuit and thermal-shutdown circuit for heater |
| CN114465202A (en) * | 2022-02-25 | 2022-05-10 | 重庆长安新能源汽车科技有限公司 | IGBT over-temperature protection circuit and method thereof, motor controller and vehicle |
-
2012
- 2012-09-20 CN CN 201220487893 patent/CN202772558U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105490253A (en) * | 2014-10-10 | 2016-04-13 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system, over-temperature protection method and device for power device of electromagnetic heating system |
| CN105490253B (en) * | 2014-10-10 | 2018-06-08 | 佛山市顺德区美的电热电器制造有限公司 | The excess temperature protection method of electromagnetic heating system and its power device, device |
| CN108306258A (en) * | 2018-04-04 | 2018-07-20 | 奥然生物科技（上海）有限公司 | A kind of excess temperature detection circuit and thermal-shutdown circuit for heater |
| CN108306258B (en) * | 2018-04-04 | 2023-12-29 | 奥然生物科技（上海）有限公司 | Over-temperature detection circuit and over-temperature protection circuit for heater |
| CN114465202A (en) * | 2022-02-25 | 2022-05-10 | 重庆长安新能源汽车科技有限公司 | IGBT over-temperature protection circuit and method thereof, motor controller and vehicle |
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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 | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130306 Termination date: 20210920 |