CN216959307U - Electric fire prevention current-limiting protector - Google Patents
Electric fire prevention current-limiting protector Download PDFInfo
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- CN216959307U CN216959307U CN202220011625.8U CN202220011625U CN216959307U CN 216959307 U CN216959307 U CN 216959307U CN 202220011625 U CN202220011625 U CN 202220011625U CN 216959307 U CN216959307 U CN 216959307U
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Abstract
The utility model discloses an electric fireproof current-limiting protector, which comprises: the system comprises a solid-state switch unit, a control unit, a current sampling unit, a temperature sampling unit and a power supply unit, wherein the solid-state switch unit, the control unit, the current sampling unit, the temperature sampling unit and the power supply unit are connected in a main loop; the power supply circuit comprises a non-isolated AC/DC converter for taking power from the main circuit; the solid-state switch unit comprises a plurality of pairs of MOSFET pairs which are connected in series in an anti-reverse mode in a source-drain-source mode, and the MOSFET pairs are connected in parallel; the current sampling unit is a single or a plurality of parallel precision resistors; the temperature sampling unit is a temperature-sensitive resistor; the current sampling unit and the solid-state switch unit are connected in series in an L line of the main loop, and a connection point between the current sampling unit and the solid-state switch unit is used as a common reference ground of the current sampling unit, the temperature sampling unit and the upper bridge arm driving circuit. The utility model has the advantages of less isolated power supply, reasonable layout, low cost and small volume design.
Description
Technical Field
The utility model relates to an electric fireproof current-limiting protector.
Background
The traditional mechanical circuit breaker adopts mechanical contacts to break the fault current of a main loop, when short-circuit fault occurs, the protection action completion time is about ten milliseconds, the short-circuit current is suddenly increased to thousands of amperes or even tens of kiloamperes within the short-circuit duration, and a large amount of electric arc sparks are generated, which are all adverse factors of electric fire protection.
The new-type electric fire-proof current-limiting protector (hereinafter referred to as current-limiting protector) is a device using solid electronic switch as breaking main loop fault current, when short-circuit fault occurs, it can quickly limit short-circuit current at microsecond level and implement non-arc breaking so as to obviously reduce electric fire accident and ensure safety of personnel and property in use place.
A current-limiting protector in CN201210545682.5 detects the current of a main loop by using a current transformer; the current detection in the embodiment of CN201821263607.9 adopts a current transformer; the novel arc extinguishing type electric fire prevention short-circuit protection device of CN201120189781.5 adopts the current hall sensor to detect current.
The following technical problems exist in the prior art: the current sampling devices are all current transformers or current Hall sensors, the size of the devices is large, the installation structure space of the current sampling elements needs to be fully considered, and the miniaturization design is not facilitated;
secondly, the current sampling unit, the temperature sampling unit, the driving unit of the power device and the like in the current-limiting protector are usually electrically isolated from each other to prevent the device from being damaged, so that a large amount of isolation power supplies are needed, the cost is improved, and the whole volume of the current-limiting protector is also increased;
in addition, although the temperature-sensitive resistor can be installed in a short distance of the main loop heating device through self insulation treatment, the temperature-sensitive resistor is damaged in the assembling process or insulation materials are aged after the temperature-sensitive resistor and the main loop are used for a long time, so that the isolation power supply is damaged, if the temperature-sensitive resistor and the main loop keep a proper electric gap, the risk of damage of the isolation power supply can be greatly reduced, but the temperature-sensitive resistor has a certain distance from the main loop heating device, so that heat is diffused to the temperature-sensitive resistor through a certain medium, the temperature change of the heating device cannot be quickly reflected by the temperature-sensitive resistor, and meanwhile, the temperature change of the heating device can be reflected by calculation.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is to overcome the defects of the prior art and provide the electric fire-proof current-limiting protector which has less isolated power supplies, is reasonable in layout, and is beneficial to low cost and small volume design.
An electrical fire protection current limiting protector comprising: the system comprises a solid-state switch unit connected in a main loop, a control unit used for controlling the solid-state switch unit, a current sampling unit used for sampling the current of the main loop, a temperature sampling unit used for sampling the temperature of the solid-state switch unit and a power supply unit; the power supply circuit includes a non-isolated AC/DC converter for taking power from a main circuit; the solid-state switch unit comprises a plurality of pairs of MOSFET pairs which are connected in series in an anti-reverse mode in a source-drain-source mode, and the MOSFET pairs are connected in parallel; the current sampling unit is a single or a plurality of precision resistors connected in parallel; the temperature sampling unit is a temperature-sensitive resistor; the current sampling unit and the solid-state switch unit are connected in series in an L line of the main loop, and a connection point between the current sampling unit and the solid-state switch unit is used as a common reference ground of the current sampling unit, the temperature sampling unit and an upper bridge arm driving circuit of the solid-state switch unit.
Preferably, the common reference ground is arranged on a whole copper foil electrically connected with a source pin of the upper bridge MOSFET, the temperature-sensitive resistor is a patch type temperature-sensitive resistor attached near a Tab pin of the MOSFET, one end of the temperature-sensitive resistor is electrically connected with the copper foil, and the Tab pin of the MOSFET is electrically connected with the copper foil.
Furthermore, the electric fireproof current-limiting protector also comprises an overvoltage absorption unit connected in parallel with two ends of the solid-state switch unit.
Preferably, the overvoltage absorption unit is a high-power TVS tube.
Furthermore, the electric fire prevention current-limiting protector also comprises a voltage sampling unit which is used for sampling the voltage of the main loop and outputting the sampling result to the control unit.
Compared with the prior art, the utility model has the following beneficial effects:
in the utility model, the connection point between the current sampling unit and the solid-state switch unit is used as a common reference ground of the current sampling unit, the temperature sampling unit and the upper bridge arm driving circuit of the solid-state switch unit; an isolation device is omitted, and the miniaturization design is facilitated;
the utility model adopts the precise resistor to sample the current, compared with the sampling device in the prior art, the sampling device has the advantages of small volume, high sampling response speed and large sampling current range, is beneficial to miniaturization design, has more timely short-circuit instantaneous protection action, shortens the rise time of the short-circuit current and has better current limiting effect;
the utility model adopts the patch type temperature-sensitive resistor, is attached near the solid-state electronic switch and is positioned at the same copper foil with the heat source of the solid-state electronic switch.
Drawings
FIG. 1 is a schematic block diagram of a circuit according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a current sampling unit, a temperature sampling unit, and a solid state switching unit in an embodiment;
FIG. 3 is a schematic circuit diagram of a temperature sampling unit in an exemplary embodiment;
FIG. 4 is a schematic circuit diagram of a power supply unit in an embodiment;
fig. 5 is a schematic view of an installation structure of the temperature sensitive resistor in the embodiment.
Detailed Description
Aiming at the defects in the prior art, the utility model adopts a temperature-sensitive resistor and a precision resistor as temperature and current sampling components respectively, and uses the connection point between a current sampling unit and a solid-state switch unit as the common reference ground of the current sampling unit, the temperature sampling unit and an upper bridge arm driving circuit of the solid-state switch unit, so as to reduce the use of an isolation device and facilitate the miniaturization design.
The utility model relates to an electric fire-proof current-limiting protector, comprising: the system comprises a solid-state switch unit connected in a main loop, a control unit used for controlling the solid-state switch unit, a current sampling unit used for sampling the current of the main loop, a temperature sampling unit used for sampling the temperature of the solid-state switch unit and a power supply unit; the power supply circuit includes a non-isolated AC/DC converter for taking power from a main circuit; the solid-state switch unit comprises a plurality of pairs of MOSFET pairs which are connected in series in an anti-reverse mode in a source-drain-source mode, and the MOSFET pairs are connected in parallel; the current sampling unit is a single or a plurality of precision resistors connected in parallel; the temperature sampling unit is a temperature-sensitive resistor; the current sampling unit and the solid-state switch unit are connected in series in an L line of the main loop, and a connection point between the current sampling unit and the solid-state switch unit is used as a common reference ground of the current sampling unit, the temperature sampling unit and an upper bridge arm driving circuit of the solid-state switch unit.
Preferably, the common reference ground is arranged on a whole copper foil electrically connected with a source pin of the upper bridge MOSFET, the temperature-sensitive resistor is a patch type temperature-sensitive resistor attached near a Tab pin of the MOSFET, one end of the temperature-sensitive resistor is electrically connected with the copper foil, and the Tab pin of the MOSFET is electrically connected with the copper foil.
Furthermore, the electric fireproof current-limiting protector also comprises an overvoltage absorption unit connected in parallel with two ends of the solid-state switch unit.
Preferably, the overvoltage absorption unit is a high-power TVS tube.
Furthermore, the electric fire prevention current-limiting protector also comprises a voltage sampling unit which is used for sampling the voltage of the main loop and outputting the sampling result to the control unit.
For the public understanding, the technical scheme of the utility model is explained in detail by a specific embodiment and the accompanying drawings:
as shown in fig. 1, the electric fire-proof current-limiting protector of the present embodiment includes: the device comprises a current sampling unit, a solid-state switch unit, an overvoltage absorption unit, a driving unit, a communication unit, a power supply unit, a current conditioning unit, a voltage sampling unit, a control unit, a human-computer interface unit and a temperature sampling unit.
The L input of the main loop is connected with one end of a current sampling unit, the other end of the current sampling unit is connected with one end of a solid-state switch unit, and the other end of the solid-state switch unit is connected with the L output; the overvoltage absorption unit is connected in parallel at two ends of the solid-state switch unit, and the input and the output of the N line of the main loop are directly connected.
The solid-state switching unit in this embodiment selects a plurality of MOSFETs connected in series and in parallel, as shown in fig. 2, two MOSFETs are connected in anti-series in pairs, and the series form is: source-drain-source; and a single pair or a plurality of pairs of MOSFET pairs are connected in parallel to form a solid-state switch unit for realizing the function of switching on or switching off the alternating current.
The driving unit of the embodiment selects a driving chip special for an MOS tube, and the control unit controls the on and off of the solid-state switch unit through the driving unit; the driving unit is divided into an MOSFET upper bridge arm driving circuit and an MOSFET unit lower bridge arm driving circuit; the source electrode and the MOSFET connected with the common reference ground Vo-1 form an upper bridge arm, and the upper bridge arm is close to the power supply side; the MOSFET with the source connected with the load side forms a lower bridge arm, and the lower bridge arm is close to the load side.
As shown in fig. 2, the current sampling unit of this embodiment selects one or more parallel precise sampling resistors to be connected in series to the L line of the main circuit, when the load current flows, voltage signals are generated at two ends of the precise sampling resistors according to ohm's law and sent to the control unit to condition the signals, and the control unit determines the action to be performed by the current-limiting protector according to the conditioned voltage signals: switching on, switching off overload protection and switching off short-circuit protection.
The voltage sampling unit is directly connected with the L1 and the N, the sampled voltage is transmitted to the control unit, and the control unit judges the action to be performed by the current-limiting protector according to the voltage signal: overvoltage protection and undervoltage protection.
As shown in fig. 3, the temperature sampling unit of the present embodiment selects a chip temperature sensitive resistor, and is placed near the source of the MOSFET, and the source is a main heat dissipation path of the MOSFET, so that the temperature of the MOSFET can be better reflected; resistance one end is direct to be connected with MOSFET's source point, is connected with the common point promptly, and the other end is connected to the control unit and carries out voltage signal and takes care of, and the control unit judges the action that current-limiting protector should go on according to the voltage signal after taking care: and starting and stopping the cooling fan and performing over-temperature protection. Temperature sampling principle: one end of the temperature-sensitive resistor is pulled up to the positive power supply through the fixed resistor, the other end of the temperature-sensitive resistor is connected to the negative power supply, the two resistors form a voltage division relation, the resistance value of the temperature-sensitive resistor changes along with the temperature change of the temperature measuring point, the voltages at the two ends of the temperature-sensitive resistor also change, and the voltage is sent to the control unit to perform voltage signal conditioning.
The communication unit adopts an isolation device to realize the function of safely isolating the communication between the control unit and the outside.
The man-machine interface comprises a liquid crystal display screen, a key, an indicator light and a buzzer, and man-machine interaction of functions of the current-limiting protector, such as state information, fault information, parameter information, fault prompt and the like is achieved.
As shown in fig. 4, the power supply unit of this embodiment takes power from the L1 input and the N input of the current-limiting protector, and outputs a first set of power sources Vout +1/Vout-1 as a control loop power source through the non-isolated AC/DC converter; the first group of power supplies output a second group of power supplies Vout +2/Vout-2 through isolated DC/DC conversion to serve as power supplies of the communication unit; the first group of power supplies are subjected to isolated DC/DC conversion to output a third group of power supplies Vout +3/Vout-3 which are used as power supplies of a lower bridge arm driving circuit in the driving unit. Vout-1 of the first group of power supplies is connected with a common point of the current sampling unit and the solid-state switch unit in the L line, and the common point is used as a common reference ground of the current sampling unit, the temperature sampling unit and the upper bridge arm driving circuit; the power supply for current sampling, the power supply for temperature sampling and the driving power supply of the upper bridge arm of the MOSFET are one path of power supply; an isolation device is omitted, and the miniaturization design is facilitated.
The overvoltage absorption unit of the embodiment adopts a high-power TVS tube to absorb overvoltage generated at two ends of the solid-state switch unit when the solid-state switch unit turns off current.
As shown in fig. 5, the common reference ground Vo-1 is a whole copper foil 1, which is connected with a source pin of the upper bridge MOSFET, the chip temperature-sensitive resistor is attached near a Tab pin of the MOSFET, one end of the temperature-sensitive resistor is electrically connected with the copper foil 1, and the Tab pin is electrically connected with the copper foil 1; the MOSFET is used as a heating device, a source pin of the MOSFET conducts most of heat to the copper foil 1, the thermal resistance between the Tab pin and the copper foil is small and can be ignored, and one end of the temperature-sensitive resistor is attached to the copper foil 1 (closely attached to the position of the MOSFET), so that the temperature changes of the MOSFET, the copper foil 1 and the temperature-sensitive resistor can be approximately considered to be synchronous, and the temperature-sensitive resistor can directly reflect the temperature of the MOSFET in real time.
When the reference places of the control loop and the main loop are different, the temperature-sensitive resistor needs to be subjected to insulation treatment when the temperature-sensitive resistor is used for temperature sampling, but the temperature-sensitive resistor is damaged in the assembling process or an insulation material is aged after long-time use, so that power supply short circuit between different reference places is caused; the temperature-sensitive resistor usually keeps a proper electrical gap with the main loop, although the risk can be greatly reduced, the temperature-sensitive resistor has a certain distance with a heating device of the main loop, so that heat is diffused to the temperature-sensitive resistor through a certain medium, the temperature-sensitive resistor cannot quickly reflect the temperature change of the heating device, and meanwhile, the temperature change of the heating device can be reflected only by calculation; one end of the temperature-sensitive resistor in the embodiment is welded on the copper foil 1 in a mounting manner, so that the temperature sampling circuit and the copper foil 1 are at the same potential Vo-1, the temperature-sensitive resistor does not need to be insulated during temperature sampling, and the temperature of the MOSFET can be reflected in real time better and directly.
Claims (5)
1. An electrical fire protection current limiting protector comprising: the system comprises a solid-state switch unit connected in a main loop, a control unit used for controlling the solid-state switch unit, a current sampling unit used for sampling the current of the main loop, a temperature sampling unit used for sampling the temperature of the solid-state switch unit and a power supply unit; wherein the power supply unit comprises a non-isolated AC/DC converter for taking power from the main circuit; the solid-state switch unit comprises a plurality of pairs of MOSFET pairs which are connected in series in an anti-reverse mode in a source-drain-source mode, and the MOSFET pairs are connected in parallel; the current sampling unit is a single or a plurality of precision resistors connected in parallel; the temperature sampling unit is a temperature-sensitive resistor; the current sampling unit and the solid-state switch unit are connected in series in an L line of the main loop, and a connection point between the current sampling unit and the solid-state switch unit is used as a common reference ground of the current sampling unit, the temperature sampling unit and an upper bridge arm driving circuit of the solid-state switch unit.
2. An electrical fire-proof current-limiting protector according to claim 1, wherein the common reference ground is disposed on a whole copper foil electrically connected to a source pin of the upper bridge MOSFET, the temperature-sensitive resistor is a chip temperature-sensitive resistor attached near a Tab pin of the MOSFET, one end of the temperature-sensitive resistor is electrically connected to the copper foil, and the Tab pin of the MOSFET is electrically connected to the copper foil.
3. An electrical fire protection current limiting protector as claimed in claim 1 or 2 further comprising an overvoltage absorption unit connected in parallel across the solid state switching unit.
4. An electrical fire-protection current-limiting protector as claimed in claim 3 wherein the overvoltage absorption unit is a high power TVS tube.
5. An electric fire-proof current-limiting protector according to claim 1 or 2, characterized by further comprising a voltage sampling unit for sampling the main circuit voltage and outputting the sampling result to the control unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220011625.8U CN216959307U (en) | 2022-01-05 | 2022-01-05 | Electric fire prevention current-limiting protector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220011625.8U CN216959307U (en) | 2022-01-05 | 2022-01-05 | Electric fire prevention current-limiting protector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216959307U true CN216959307U (en) | 2022-07-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202220011625.8U Active CN216959307U (en) | 2022-01-05 | 2022-01-05 | Electric fire prevention current-limiting protector |
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|---|---|
| CN (1) | CN216959307U (en) |
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- 2022-01-05 CN CN202220011625.8U patent/CN216959307U/en active Active
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