CN214755482U - Overcurrent protection circuit of external fan of photovoltaic inverter - Google Patents
Overcurrent protection circuit of external fan of photovoltaic inverter Download PDFInfo
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- CN214755482U CN214755482U CN202120601782.XU CN202120601782U CN214755482U CN 214755482 U CN214755482 U CN 214755482U CN 202120601782 U CN202120601782 U CN 202120601782U CN 214755482 U CN214755482 U CN 214755482U
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Abstract
The utility model discloses an overcurrent protection circuit of photovoltaic inverter outside fan, it has the supply circuit for the fan power supply, and overcurrent protection circuit is including establishing ties the first switch tube in supply circuit and being used for receiving the control signal input terminal from photovoltaic inverter's control system, and first switch tube is controlled by control signal and switches on or break off, and overcurrent protection circuit still includes: the sampling unit is used for generating a voltage sampling value according to the fan current; the comparison unit is provided with a first input end, a second input end and an output end, wherein the first input end is electrically connected with the sampling unit, the second input end is used for acquiring a protection threshold value, and the output end is electrically connected with the sampling unit; and the control end of the second switch tube is electrically connected with the output end of the comparison unit so as to pull down the control signal after receiving the high level output by the comparison unit. The utility model discloses can be when the outside fan of dc-to-ac converter breaks down, the initiative cuts off the fan return circuit, and the supply circuit device of protection fan does not receive the damage, has improved the reliability of photovoltaic inverter's work.
Description
Technical Field
The utility model relates to an overcurrent protection circuit of photovoltaic inverter outside fan.
Background
The external fan of the photovoltaic inverter is exposed outside the chassis, so that the situation of overcurrent or short circuit of a fan power supply circuit sometimes occurs due to breakage or aging of a power supply line. The existing traditional solutions mainly have: no protection is provided or a current limiting resistor or fuse is added as shown in fig. 1. When short-circuit fault occurs, components such as a fuse, a current-limiting resistor or a circuit switching tube can be fused by overlarge current, passive defense is achieved, the mode is stiff, and response time cannot be controlled. When the fault of the external fan is cleared, the circuit elements are damaged, so that the circuit cannot continue to operate, and the damaged elements need to be frequently replaced to ensure that the circuit continues to operate, so that the use cost is increased.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present invention is to provide an overcurrent protection device for an external fan of a photovoltaic inverter, which can rapidly cut off a power supply circuit when an overcurrent or a short-circuit fault occurs in the external fan, and has a low cost.
In order to achieve the above object, the utility model provides an overcurrent protection circuit of photovoltaic inverter outside fan, include:
an overcurrent protection circuit of a fan outside a photovoltaic inverter, which has a power supply circuit for supplying power to the fan, the overcurrent protection circuit comprises a first switch tube connected in series in the power supply circuit so as to be switched on or off, and a control signal input end for receiving a control signal from a control system of the photovoltaic inverter, the first switch tube can be switched on or off under the control of the control signal, and the overcurrent protection circuit further comprises:
the sampling unit is used for generating a voltage sampling value according to the fan current;
the comparison unit is provided with a first input end, a second input end and an output end, wherein the first input end is electrically connected with the sampling unit, the second input end is used for acquiring the protection threshold value, and the output end is electrically connected with the sampling unit;
and the control end of the second switch tube is electrically connected with the output end of the comparison unit so as to pull down the control signal after receiving the high level output by the comparison unit.
Preferably, the overcurrent protection circuit further includes a control signal pull-up resistor, the power supply circuit has a power supply anode and a power supply cathode, the control signal pull-up resistor and the second switching tube are connected in series to form a first branch, the first branch is connected between the power supply anode and the power supply cathode, and the control signal input terminal is electrically connected to the control end of the first switching tube after being electrically connected to the control signal pull-up resistor and the midpoint of the second switching tube.
More preferably, the first switch tube and the second switch tube are transistors, including but not limited to field effect transistors, and the control terminal is a gate of the field effect transistor.
Preferably, the overcurrent protection circuit further includes a protection signal pull-up resistor, one end of the protection signal pull-up resistor is electrically connected between the control signal pull-up resistor and the positive electrode of the power supply, and the other end of the protection signal pull-up resistor is electrically connected to the output end of the comparison unit.
Preferably, the over-current protection circuit further includes a protection hysteresis circuit electrically connected between the output terminal and the first input terminal of the comparison unit. Thereby enabling the settling time for circuit protection and recovery to be set.
Preferably, the protection hysteresis circuit comprises a diode and a hysteresis resistor connected in series between the output terminal and the first input terminal. By adjusting the diode and the protection resistor, the hysteresis time of the circuit for each protection and recovery can be set.
Preferably, the overcurrent protection circuit further includes a filter circuit for filtering the sampling value of the sampling unit. The sampling value can be filtered to prevent high-frequency interference from causing error protection.
Preferably, the filter circuit includes a capacitor and a filter resistor, a branch formed by connecting the capacitor and the filter resistor in series is connected in parallel to two ends of the sampling unit, and the first input end is electrically connected to a middle point between the capacitor and the filter resistor.
Preferably, the sampling unit is a sampling resistor connected in series in the power supply circuit; and/or the comparison unit is a comparator. Specifically, the comparator is an operational amplifier, and the first input terminal, the second input terminal, and the output terminal are a non-inverting input terminal, an inverting input terminal, and an output terminal of the operational amplifier, respectively.
Preferably, the overcurrent protection circuit further includes a first voltage-dividing resistor and a second voltage-dividing resistor, a branch formed by connecting the first voltage-dividing resistor and the second voltage-dividing resistor in series is connected in parallel to two ends of a power supply of the power supply circuit, and adjusting a preset protection threshold value can be implemented by changing parameters of the first voltage-dividing resistor and the second voltage-dividing resistor. The second input end of the comparison unit is electrically connected to a middle point of the first voltage-dividing resistor and the second voltage-dividing resistor.
The utility model adopts the above scheme, compare prior art and have following advantage:
the utility model discloses an overcurrent protection circuit of photovoltaic inverter outside fan, produce the voltage sampling value through the sampling unit, the comparison unit is received the voltage sampling value and with protection threshold value and corresponding output low level or high level, draw down control signal through switching on the second switch tube when sampling voltage surpasss the protection threshold value, the first switch tube disconnection controlled by this control signal, thereby cut off the supply circuit of fan, when overcurrent or short-circuit fault take place for outside fan, can cut off supply circuit rapidly, prevent the circuit damage, improve photovoltaic inverter's reliability, the cost is lower simultaneously.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art over-current protection circuit;
fig. 2 is a schematic structural diagram of an overcurrent protection circuit of an external fan of a photovoltaic inverter according to an embodiment of the present invention.
Detailed Description
The following detailed description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings, enables the advantages and features of the invention to be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. Furthermore, the technical features mentioned in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 2, the overcurrent protection circuit for the external fan of the photovoltaic inverter provided according to the embodiment has a power supply circuit 10 for supplying power to the fan 1. The overcurrent protection circuit comprises a first switch tube Q1 connected in series in the power supply circuit 10 to make it on or off, and a control signal input terminal E for receiving a control signal from a control system of the photovoltaic inverter, wherein the first switch tube Q1 is controlled by the control signal to make it on or off. The overcurrent protection circuit further includes: the sampling unit is used for generating a voltage sampling value according to the fan current; the comparison unit is provided with a first input end a1 used for being electrically connected with the sampling unit, a second input end a2 used for obtaining a protection threshold value and an output end a3, and is used for receiving the voltage sampling value and correspondingly outputting a low level or a high level after being compared with the protection threshold value; the control terminal of the second switch Q2 is electrically connected to the output terminal a3 of the comparing unit, so as to pull the control signal low after receiving the high level output by the comparing unit, and turn off the first switch Q1.
Specifically, the overcurrent protection circuit further comprises a control signal pull-up resistor R6. The power supply circuit 10 includes a power supply 100, the power supply 100 having a power supply positive pole 101 and a power supply negative pole 102. The control signal pull-up resistor R6 and the second switch tube Q2 are connected in series to form a first branch circuit 20, the first branch circuit 20 is connected between the positive power pole 100 and the negative power pole 101, one end of a control signal input terminal E is electrically connected with a control system (specifically, a DSP chip of the photovoltaic inverter) of the photovoltaic inverter, and the other end of the control signal input terminal E is electrically connected with a middle point of the control signal pull-up resistor R6 and the second switch tube Q2 and then connected to a control end of the first switch tube Q1.
The overcurrent protection circuit further comprises a protection signal pull-up resistor R5, one end of the protection signal pull-up resistor R5 is electrically connected between the control signal pull-up resistor R6 and the positive electrode of the power supply, and the other end of the protection signal pull-up resistor R5 is electrically connected to the output end a3 of the comparison unit.
The overcurrent protection circuit further comprises a protection hysteresis circuit 30 electrically connected between the output end a3 and the first input end a1 of the comparison unit, and the protection hysteresis circuit generates positive feedback to the sampling end when overcurrent protection occurs, so that the protection hysteresis time is increased, and the response time of the overcurrent protection can be correspondingly adjusted. Specifically, the protection hysteresis circuit 30 includes a diode D1 and a hysteresis resistor R7 for increasing the hysteresis time when performing protection, and a branch formed by connecting the diode D1 and the hysteresis resistor R7 in series has one end connected to the output end a3 of the comparing unit U1 and the other end connected to the first input end a1 of the comparing unit.
The overcurrent protection circuit also comprises a filter circuit 40 for filtering the sampling value of the sampling unit so as to prevent high-frequency interference, and the filtering of the sampling value can prevent the high-frequency interference from causing error protection. The filter circuit 40 includes a capacitor C and a filter resistor R4, a branch formed by serially connecting the capacitor C1 and the filter resistor R4 is connected in parallel to two ends of the sampling unit, and the first input end a1 is electrically connected to a middle point of the capacitor C1 and the filter resistor R4.
By adjusting the values of the diode D1, the hysteresis resistor R7, the capacitor C and the filter resistor R4, the hysteresis time of the circuit for each protection and recovery can be set.
In the embodiment, the sampling unit is a sampling resistor R3 connected in series in the power supply circuit. The comparison unit U1 is a comparator. Specifically, the comparator U1 is an operational amplifier, and the first input terminal a1, the second input terminal a2 and the output terminal a3 are a non-inverting input terminal, an inverting input terminal and an output terminal of the operational amplifier, respectively.
The overcurrent protection circuit further comprises a first voltage-dividing resistor R1 and a second voltage-dividing resistor R2, a branch formed by connecting the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 in series is connected in parallel with two ends of a power supply 100 of the power supply circuit, and a second input end a2 of the comparison unit U1 is electrically connected to a middle point of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2. Adjusting the preset protection threshold can be achieved by changing the parameters of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2.
In this embodiment, when the circuit is abnormal, that is, a short circuit or an overcurrent occurs in the circuit, the current I in the circuit increases, a larger sampling voltage is generated at the point a, the sampling unit samples the current flowing through the fan 1 and filters the current through the filter circuit 40, a sampling value is obtained at the point C, the comparison unit compares the sampling value at the point C with a preset protection threshold value at the point B, and when the sampling value is equal to or greater than the protection threshold value, the comparison unit outputs a high level from the output terminal a3 to the point D, so that the second switching tube Q2 is closed, the control signal is pulled low, the first switching tube Q1 is disconnected, and the power supply circuit of the fan 1 is cut off.
Because Q1 is disconnected, the current I in the circuit is reduced, the potential of the point A becomes low, the sampling unit samples the current flowing through the fan 1 and filters the current through the filter circuit 40, a sampling value is obtained at the point C, the sampling value at the point C is compared with the preset protection threshold value at the point B by the comparison unit, when the sampling value is smaller than the protection threshold value, the comparison unit outputs a low level to the point D from the output end a3, the second switch tube Q2 is disconnected, the control signal enables the first switch tube Q1 to be closed, and the power supply circuit of the fan 1 is conducted again.
The above steps are a self-checking cycle procedure, and are implemented by the protection hysteresis circuit 40, after the first switch Q1 is turned off, the diode D1 and the hysteresis resistor R7 in the protection hysteresis circuit 40 generate a positive feedback signal to the first input end a1 of the comparison unit U1, so as to increase the protection hysteresis time. Adjusting the protection hysteresis time can be realized by changing the parameters of the filter resistor R4, the capacitor C1, the protection signal pull-up resistor R5 and the hysteresis resistor R7. The program can protect the circuit from being damaged due to the fact that the circuit is continuously in a short circuit or overcurrent state, and when the circuit is in the short circuit or overcurrent state and the like, the circuit can continuously carry out circulating self-detection until the fault in the circuit is repaired.
In the embodiment, when the external fan of the inverter fails, the current sampling is compared with the protection value, so that the fan loop is actively cut off, and the power supply circuit device of the fan is protected from being damaged. The hysteresis time for circuit protection and recovery can be set. The reliability of the operation of photovoltaic inverter has been improved.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are preferred embodiments, which are intended to enable persons skilled in the art to understand the contents of the present invention and to implement the present invention, and thus, the protection scope of the present invention cannot be limited thereby. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (10)
1. An overcurrent protection circuit of a fan outside a photovoltaic inverter, having a power supply circuit for supplying power to the fan, the overcurrent protection circuit including a first switching tube connected in series in the power supply circuit so as to be turned on or off and a control signal input terminal for receiving a control signal from a control system of the photovoltaic inverter, the first switching tube being capable of being turned on or off by being controlled by the control signal, the overcurrent protection circuit further comprising:
the sampling unit is used for generating a voltage sampling value according to the fan current;
the comparison unit is provided with a first input end, a second input end and an output end, wherein the first input end is electrically connected with the sampling unit, the second input end is used for acquiring a protection threshold value, and the output end is electrically connected with the sampling unit;
and the control end of the second switch tube is electrically connected with the output end of the comparison unit so as to pull down the control signal after receiving the high level output by the comparison unit.
2. The overcurrent protection circuit of claim 1, further comprising a control signal pull-up resistor, wherein the power supply circuit has a positive power supply terminal and a negative power supply terminal, the control signal pull-up resistor and the second switching tube are connected in series to form a first branch, the first branch is connected between the positive power supply terminal and the negative power supply terminal, and the control signal input terminal is electrically connected to a control terminal of the first switching tube after being electrically connected to a midpoint between the control signal pull-up resistor and the second switching tube.
3. The overcurrent protection circuit of claim 2, further comprising a protection signal pull-up resistor, wherein one end of the protection signal pull-up resistor is electrically connected between the control signal pull-up resistor and the positive power supply, and the other end of the protection signal pull-up resistor is electrically connected to the output terminal of the comparison unit.
4. The over-current protection circuit of claim 3, further comprising a protection hysteresis circuit electrically connected between the output terminal and the first input terminal of the comparison unit.
5. The overcurrent protection circuit of claim 4, wherein the protection hysteretic circuit comprises a diode and a hysteretic resistor in series between the output terminal and the first input terminal.
6. The over-current protection circuit according to claim 1, further comprising a filter circuit for filtering the sampled value of the sampling unit.
7. The overcurrent protection circuit of claim 6, wherein the filter circuit comprises a capacitor and a filter resistor, a branch formed by the capacitor and the filter resistor connected in series is connected in parallel to two ends of the sampling unit, and the first input terminal is electrically connected to a middle point between the capacitor and the filter resistor.
8. The overcurrent protection circuit of any one of claims 1 to 7, wherein the sampling unit is a sampling resistor connected in series in the power supply circuit.
9. The overcurrent protection circuit of any one of claims 1 to 7, wherein the comparison unit is a comparator.
10. The over-current protection circuit according to any one of claims 1 to 7, further comprising a first voltage dividing resistor and a second voltage dividing resistor, wherein a branch formed by connecting the first voltage dividing resistor and the second voltage dividing resistor in series is connected in parallel to two ends of a power supply of the power supply circuit, and the second input terminal of the comparing unit is electrically connected to a middle point of the first voltage dividing resistor and the second voltage dividing resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120601782.XU CN214755482U (en) | 2021-03-24 | 2021-03-24 | Overcurrent protection circuit of external fan of photovoltaic inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120601782.XU CN214755482U (en) | 2021-03-24 | 2021-03-24 | Overcurrent protection circuit of external fan of photovoltaic inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214755482U true CN214755482U (en) | 2021-11-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120601782.XU Active CN214755482U (en) | 2021-03-24 | 2021-03-24 | Overcurrent protection circuit of external fan of photovoltaic inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214755482U (en) |
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2021
- 2021-03-24 CN CN202120601782.XU patent/CN214755482U/en active Active
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address |
Address after: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee after: Asway Technology (Shanghai) Co.,Ltd. Address before: No.9 factory building, 198 Xiangyang Road, high tech Zone, Suzhou City, Jiangsu Province, 215011 Patentee before: Esway new energy technology (Jiangsu) Co.,Ltd. |
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| CP03 | Change of name, title or address | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee after: Elsevier Technology Co.,Ltd. Address before: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee before: Asway Technology (Shanghai) Co.,Ltd. |
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| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee after: Elsevier Technology Co.,Ltd. Address before: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee before: Esway Technology (Shanghai) Co.,Ltd. Address after: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee after: Esway Technology (Shanghai) Co.,Ltd. Address before: 200000 room 905b, 757 Mengzi Road, Huangpu District, Shanghai Patentee before: Asway Technology (Shanghai) Co.,Ltd. |
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| CP01 | Change in the name or title of a patent holder |