CN202586299U - Structure of over-temperature protection circuit - Google Patents

Abstract

The utility model discloses a structure of an over-temperature protection circuit. The structure comprises a thermosensitive element and a protecting circuit for reading the state of the thermosensitive element, wherein the thermosensitive element is arranged near an oscillating loop including an IGBT (Insulated Gate Bipolar Transistor), and the oscillating loop comprises a bridge rectifier. The structure is characterized in that one end of the thermosensitive element is connected to a negative output end of the bridge rectifier and is grounded herein; the thermosensitive element is fixed at an over-temperature protection point on a printing plate, and the over-temperature protection point is located on the back side of the matching position between a bridge-rectifier heat radiator and the printing plate; and the thermosensitive element is provided with two complete stable heat conduction paths, one stable heat conduction path is communicated with the negative output end of the bridge rectifier, and the other stable heat conduction path penetrates through the printing plate via the heat radiator to reach the back side of the printing plate. The protection circuit in such a structure is provided with two heat current conduction channels for carrying out temperature monitoring on the heat radiator and the bridge rectifier, the over-temperature phenomenon of either the heat radiator or the bridge rectifier can lead to the induction of the thermosensitive element so as to trigger a protection action; and the overtemperature detection is sensitive, and the heat current conduction channels are stable in heat resistance.

Description

A kind of structure of thermal-shutdown circuit

Technical field

The utility model relates to a kind of structure of thermal-shutdown circuit.

Background technology

Apply to the high frequency electric source of IGBT, the power of its load is often bigger, thereby operating current is also corresponding bigger, and temperature rise takes place easily, brings out the damage of semiconductor device easily, even brings potential safety hazard.So, at powerful high frequency electric source, particularly apply in the power supply of IGBT, special thermal-shutdown circuit is set seems essential.

Often also more than one of heater element is such as IGBT itself and the power unit of keeping the IGBT operate as normal; Consider the problem of cost, technology, can not all monitor and the timely temperature early warning data that obtain that so can only be to some good stability, obvious, the representative element of temperature rise be monitored to all heater elements.So, as where designing thermal-shutdown circuit, and confirm its overheat protector point, be the inexorable trend of this type thermal-shutdown circuit design.

The utility model content

To the inexorable trend of above thermal-shutdown circuit design, the utility model discloses a kind of structure of thermal-shutdown circuit, its technical scheme is following:

A kind of structure of thermal-shutdown circuit; Comprise a temperature-sensitive element and the protective circuit that reads this temperature-sensitive element state; Said temperature-sensitive element places one to contain near the oscillation circuit of IGBT; And this oscillation circuit has Yi Qiaodui, and a said temperature-sensitive element wherein end is connected in the negative output terminal of said bridge heap and this ground connection; This temperature-sensitive element is fixed in an overheat protector point on the printing forme, and this overheat protector point is positioned at the reverse side of said bridge heap radiator and said printing forme cooperation place; Said temperature-sensitive element has two complete stable heat conduction paths, and one of which is communicated with the said cathode output end of said bridge heap, and it two passes said printing forme via said radiator and arrive its reverse side.

As some preferred versions of the utility model, can implement as follows:

In one preferred embodiment, said radiator is locked in said printing forme through screw; Said overheat protector point be positioned at said screw latched position near.

In one preferred embodiment, said protective circuit comprises:

One potential-divider network comprises one first resistance and the NTC resistance that are series between power supply and the ground; Said NTC resistance is parallelly connected with a filter capacitor, one of which end ground connection, and the other end connects the negative input end of a comparator;

Its positive input terminal of said comparator connects a reference voltage, and its output connects the grid control signal of said IGBT through a control module; Said NTC resistance is said temperature-sensitive element.

In one preferred embodiment, said IGBT also is assemblied on the said bridge heap radiator, and the two has heat conduction path.

The beneficial effect that the utility model brings is:

1. the protective circuit of this structure has two hot-fluid conduction pathways, and radiator and bridge heap are carried out monitoring temperature simultaneously, and arbitrary its excess temperature phenomenon in the two all can cause the induction of temperature-sensitive element, thus the trigger protection behavior; This mode, excess temperature detects sensitive, and the thermal resistance of hot-fluid conduction pathway is stable, and technology is simple.

2. thermistor is close to screw, has guaranteed the thermal resistance stability of the second hot-fluid conduction pathway more, can use technology controlling and process.

Description of drawings

Embodiment is described further the utility model below in conjunction with accompanying drawing:

Fig. 1 is the upward view of its printing forme 10 parts of the utility model one embodiment;

Fig. 2 is an AA part cross-sectional schematic embodiment illustrated in fig. 1;

Fig. 3 is the utility model embodiment two its protective circuit sketch mapes.

Embodiment

Embodiment one:

As shown in Figure 1, the upward view of its printing forme 10 parts of the utility model one embodiment; Fig. 2 is an AA part cross-sectional schematic embodiment illustrated in fig. 1; Explain in conjunction with this two figure:

This thermal-shutdown circuit is not only that circuit is formed, very importantly the structure of its physics.It comprises a temperature-sensitive element 20 and the protective circuit that reads these temperature-sensitive element 20 states; And temperature-sensitive element places one to contain near the oscillation circuit of IGBT; And this oscillation circuit has bridge heap 11, and bridge heap 11 is supplied with end as the power supply of IGBT oscillation circuit, and this point is more common.

In the present embodiment, temperature-sensitive element 20 a wherein end is connected in the negative output terminal 12 of bridge heap 11, and this tie point is ground connection, sees Fig. 3; Temperature-sensitive element 20 is fixed in an overheat protector point on the printing forme 10, and this overheat protector point is positioned at the reverse side of bridge heap 11 its radiators 13 and printing forme 10 cooperation places; So, can reach a conclusion from Fig. 1 and Fig. 2, temperature-sensitive element 20 has two complete stable heat conduction paths: one of which is to be communicated in the first hot-fluid conduction pathway f1 that bridge is piled 11 cathode output ends 12; Its two, be via radiator 13, pass the reverse side that printing forme 10 arrives printing formes 10, this is the second hot-fluid conduction pathway f2.

It is thus clear that the protective circuit of this structure has two hot-fluid conduction pathways, radiator 13 and bridge heap 11 are carried out monitoring temperature simultaneously, arbitrary its excess temperature phenomenon in the two all can cause the induction of temperature-sensitive element 20, thus the trigger protection behavior; This mode, excess temperature detects sensitive, and the thermal resistance of hot-fluid conduction pathway is stable, and technology is simple.

Thermistor 20 is close to screw 14, has guaranteed the thermal resistance stability of the second hot-fluid conduction pathway f 2 more, can use technology controlling and process.

Embodiment two:

The control circuit that the present technique scenario-frame can adopt is quite extensive, and shown in Figure 3 is present embodiment two, a kind of example that uses NTC resistance, and in this example, a potential-divider network comprises one first resistance R 1 and the NTC resistance R N that are series between power supply and the ground; NTC resistance R N is parallelly connected with a filter capacitor C1, one of which end ground connection, and the other end connects the negative input end of a comparator U1;

Its positive input terminal of comparator U1 connects a reference voltage, and this reference voltage comes from the burning voltage that potential-divider network R2 and R3 take from VCC, and its output of comparator U1 connects the grid control signal Cout of IGBT through a control module 31; NTC resistance R N is the temperature-sensitive element 20 of present embodiment.

It is thus clear that the protective circuit of present embodiment is more succinct, adopt NTC resistance R N to carry out excess temperature and detect, adopt comparator U1 more delicately through control module 31 output grid control signal Cout, response in time.This grid control signal Cout can make IGBT quit work, and forces whole high frequency electric source failure of oscillation, reaches the purpose of protection.

The above; Be merely the utility model preferred embodiment; So can not limit the scope that the utility model is implemented according to this, the equivalence of promptly 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 (4)

1. the structure of a thermal-shutdown circuit comprises a temperature-sensitive element and the protective circuit that reads this temperature-sensitive element state, and said temperature-sensitive element places one to contain near the oscillation circuit of IGBT, and this oscillation circuit has Yi Qiaodui, it is characterized in that:

A said temperature-sensitive element wherein end is connected in the negative output terminal of said bridge heap and this ground connection; This temperature-sensitive element is fixed in an overheat protector point on the printing forme, and this overheat protector point is positioned at the reverse side of said bridge heap radiator and said printing forme cooperation place; Said temperature-sensitive element has two complete stable heat conduction paths, and one of which is communicated with the said cathode output end of said bridge heap, and it two passes said printing forme via said radiator and arrive its reverse side.

2. according to the structure of the said a kind of thermal-shutdown circuit of claim 1, it is characterized in that: said radiator is locked in said printing forme through screw; Said overheat protector point be positioned at said screw latched position near.

3. according to the structure of the said a kind of thermal-shutdown circuit of claim 1, it is characterized in that: said protective circuit comprises:

One potential-divider network comprises one first resistance and the NTC resistance that are series between power supply and the ground; Said NTC resistance is parallelly connected with a filter capacitor, one of which end ground connection, and the other end connects the negative input end of a comparator;

Its positive input terminal of said comparator connects a reference voltage, and its output connects the grid control signal of said IGBT through a control module; Said NTC resistance is said temperature-sensitive element.

4. according to the structure of the said a kind of thermal-shutdown circuit of claim 1, it is characterized in that: said IGBT also is assemblied on the said bridge heap radiator, and the two has heat conduction path.

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