CN209963948U - Device for preventing auxiliary power supply of photovoltaic inverter from being started repeatedly - Google Patents
Device for preventing auxiliary power supply of photovoltaic inverter from being started repeatedly Download PDFInfo
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- CN209963948U CN209963948U CN201920645249.6U CN201920645249U CN209963948U CN 209963948 U CN209963948 U CN 209963948U CN 201920645249 U CN201920645249 U CN 201920645249U CN 209963948 U CN209963948 U CN 209963948U
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Abstract
The application discloses a device for avoiding repeated starting of an auxiliary power supply of a photovoltaic inverter, which comprises a control unit and a power absorption unit, wherein the control unit and the power absorption unit are connected between a positive direct current bus and a negative direct current bus in parallel; the control signal output end of the control unit is connected with the control signal input end of the power absorption unit; the control unit is used for outputting a first control signal to control the power absorption unit to stop working under the condition that the voltage between the positive direct current bus and the negative direct current bus is greater than a threshold voltage; and the power absorption unit is also used for outputting a second control signal to control the power absorption unit to work under the condition that the voltage between the positive direct current bus and the negative direct current bus is not more than the threshold voltage. The power absorption unit is controlled by the control unit; the problem of repeated starting of an auxiliary power supply of the conventional photovoltaic inverter is solved; the device has good low-temperature performance, low failure rate and high reliability.
Description
Technical Field
The application relates to the technical field of power electronics, in particular to a device for avoiding repeated starting of an auxiliary power supply of a photovoltaic inverter.
Background
When the auxiliary power supply gets electricity from the photovoltaic inverter direct current bus, the load carrying capacity of the photovoltaic cell panel is very weak under the low light conditions of morning, evening, overcast and rainy days and the like, the normal power consumption of the auxiliary power supply cannot be met, and the auxiliary power supply can be started and shut down repeatedly. This is determined by the output characteristics of the photovoltaic panel: when the light is weak, the output voltage of the photovoltaic cell panel reaches the starting voltage of the auxiliary power supply, but the loading capacity of the photovoltaic cell panel is very weak at the moment, and after the auxiliary voltage is started, the auxiliary power supply is shut down due to insufficient power of the photovoltaic cell panel; after the auxiliary power supply is shut down, the output voltage of the photovoltaic cell panel recovers to the opening voltage, the opening voltage meets the starting voltage of the auxiliary power supply, the auxiliary power supply is started again, and the auxiliary power supply is repeatedly started when the light is weak.
In order to solve the above problem, as shown in fig. 1, it is general to avoid the repeated start of the auxiliary power source of the photovoltaic inverter by adding a power absorption unit. Referring to fig. 2, fig. 2 is a specific implementation circuit of fig. 1. In the figure, the driving signal of the Q1 is the output voltage of the auxiliary winding of the auxiliary power supply, the auxiliary power supply is not started in weak light, the Q1 is cut off, the Q2 is conducted, and the power absorption unit works. Along with the gradual increase of illumination intensity, the output voltage of the photovoltaic cell panel increases, and when the output voltage of the photovoltaic cell panel reaches the starting voltage of the auxiliary power supply, the auxiliary power supply starts, Q1 is conducted, Q2 is cut off, and the power absorption unit stops working. Because the power absorption unit is cut off from the load of the photovoltaic cell panel, the photovoltaic cell panel has enough power to meet the normal work of the auxiliary power supply, namely, the phenomenon of repeated start-stop after the auxiliary power supply is started can not occur.
The problems of the above solution are: whether the power absorption unit works is completely controlled by the auxiliary power supply, the auxiliary power supply is complex in circuit, and the fault probability is high; if the auxiliary power supply fails or is abnormal, the Q1 cannot be normally conducted, so that the power absorption unit is always in a working state, and when the photovoltaic power is strong, the power absorbed by the power absorption unit far exceeds the normal absorption capacity of the power absorption unit, so that the power absorption unit is damaged, and even the risk of fire is caused; in addition, under the low temperature condition, the auxiliary power supply often can not start normally, leads to the power absorption unit to be in operating condition for a long time, can cause the power absorption unit to damage equally, has the risk of even catching fire.
SUMMERY OF THE UTILITY MODEL
In view of this, an object of the present application is to provide a device for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started, so as to solve the problem of repeated starting of the auxiliary power supply of the existing photovoltaic inverter.
The technical scheme adopted by the application for solving the technical problems is as follows:
according to one aspect of the present application, there is provided an apparatus for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started, the apparatus for preventing the auxiliary power supply of the photovoltaic inverter from being repeatedly started, comprising a control unit and a power absorption unit connected in parallel between a positive direct current bus and a negative direct current bus;
the control signal output end of the control unit is connected with the control signal input end of the power absorption unit;
the control unit is used for outputting a first control signal to control the power absorption unit to stop working under the condition that the voltage between the positive direct current bus and the negative direct current bus is greater than a threshold voltage; and the power absorption unit is also used for outputting a second control signal to control the power absorption unit to work under the condition that the voltage between the positive direct current bus and the negative direct current bus is not more than the threshold voltage.
In one possible embodiment, the control unit includes a reference voltage generating circuit, a voltage dividing circuit, and a comparing circuit;
the reference voltage generating circuit is used for generating a reference voltage;
the voltage division circuit is used for generating a divided voltage according to the voltage between the positive direct current bus and the negative direct current bus;
the comparison circuit is used for comparing the reference voltage with the divided voltage and outputting the first control signal or the second control signal through a control signal output end of the comparison circuit according to a comparison result.
In one possible embodiment, the reference voltage generating circuit includes a tunable shunt regulator, a first resistor, a second resistor, and a third resistor;
one end of the first resistor is connected with the positive direct current bus, and the other end of the first resistor is connected with the first end of the adjustable shunt regulator; one end of the second resistor is connected with the first end of the adjustable parallel voltage stabilizer, and the other end of the second resistor is connected with the second end of the adjustable parallel voltage stabilizer; one end of the third resistor is connected with the second end of the adjustable parallel voltage stabilizer, and the other end of the third resistor is connected with the negative direct current bus; and the third end of the adjustable parallel voltage stabilizer is connected with the negative direct current bus.
In one possible embodiment, the voltage divider circuit includes a fourth resistor and a fifth resistor connected in series.
In one possible embodiment, the comparison circuit includes a comparator, a sixth resistor, a seventh resistor, and an eighth resistor;
the positive input end of the comparator is connected with the divided voltage; the negative input end of the comparator is connected with the reference voltage; one end of the sixth resistor is connected to the reference voltage, and the other end of the sixth resistor is connected with the output end of the comparator; one end of the seventh resistor is connected with the output end of the comparator, and the other end of the seventh resistor is connected with the eighth resistor; the other end of the eighth resistor is connected with the negative direct current bus; the other end of the seventh resistor is the control signal output end.
In a possible implementation, the power absorption unit includes a first switch tube, a second switch tube, a ninth resistor, and a tenth resistor;
the first end of the first switch tube is a control signal input end of the power absorption unit; the second end of the first switch tube is connected with one end of the ninth resistor, and the other end of the ninth resistor is connected with the positive direct current bus; the third end of the first switching tube is connected with the negative direct current bus; the first end of the second switch tube is connected with the second end of the first switch tube; the second end of the second switch tube is connected with the tenth resistor, and the other end of the tenth resistor is connected with the positive direct current bus; and the third end of the second switch tube is connected with the negative direct current bus.
In a possible embodiment, an overcurrent protection device or an overheat protection device is connected in series between the other end of the tenth resistor and the positive dc bus.
According to the device for avoiding the repeated starting of the auxiliary power supply of the photovoltaic inverter, the power absorption unit is controlled by the control unit; the problem of repeated starting of an auxiliary power supply of the conventional photovoltaic inverter is solved; the fault risks such as fire and the like caused by long-term operation of the absorption power unit due to the fact that the auxiliary power supply cannot work normally under the low-temperature condition or after the auxiliary power supply fails are avoided; the device has good low-temperature performance, low failure rate and high reliability.
Drawings
Fig. 1 is a schematic structural diagram of an apparatus for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started according to the prior art;
fig. 2 is a schematic diagram of a circuit structure for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started according to the prior art;
fig. 3 is a schematic structural diagram of an apparatus for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started according to an embodiment of the present disclosure;
fig. 4 is a schematic circuit diagram of a circuit configuration for avoiding repeated startup of an auxiliary power supply of a photovoltaic inverter according to an embodiment of the present application.
The implementation, functional features and advantages of the objectives of the present application will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer and clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
As shown in fig. 3, an embodiment of the present application provides an apparatus for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started, where the apparatus for preventing an auxiliary power supply of a photovoltaic inverter from being repeatedly started includes a control unit and a power absorption unit connected in parallel between a positive dc bus and a negative dc bus;
the control signal output end of the control unit is connected with the control signal input end of the power absorption unit;
the control unit is used for outputting a first control signal to control the power absorption unit to stop working under the condition that the voltage between the positive direct current bus and the negative direct current bus is greater than a threshold voltage; and the power absorption unit is also used for outputting a second control signal to control the power absorption unit to work under the condition that the voltage between the positive direct current BUS BUS + and the negative direct current BUS BUS-is not more than the threshold voltage.
In the present embodiment, the control unit includes a reference voltage generating circuit, a voltage dividing circuit, and a comparing circuit;
the reference voltage generating circuit is used for generating a reference voltage;
the voltage division circuit is used for generating divided voltage according to the voltage between the positive direct current BUS BUS + and the negative direct current BUS BUS-;
the comparison circuit is used for comparing the reference voltage with the divided voltage and outputting the first control signal or the second control signal through a control signal output end of the comparison circuit according to a comparison result.
Referring to fig. 4, the reference voltage generating circuit includes an adjustable shunt regulator T1, a first resistor R1, a second resistor R2, and a third resistor R3;
one end of the first resistor R1 is connected to the positive dc BUS +, and the other end of the first resistor R1 is connected to a first end (shown as 1 in the figure) of the adjustable shunt regulator T1; one end of the second resistor R2 is connected to the first end of the adjustable shunt regulator T1, and the other end of the second resistor R2 is connected to the second end (shown in fig. 2) of the adjustable shunt regulator T1; one end of the third resistor R3 is connected to the second end (shown in fig. 2) of the adjustable shunt regulator T1, and the other end of the third resistor R3 is connected to the negative dc BUS "; the third terminal (shown as 3 in the figure) of the adjustable shunt regulator T1 is connected with the negative direct current BUS BUS-. One end of the second resistor R2 outputs a reference voltage Vref.
In the embodiment, the adjustable shunt regulator T1 may employ TL 431.
Referring to fig. 4, the voltage divider circuit includes a fourth resistor R4 and a fifth resistor R5 connected in series.
Referring to fig. 4, the comparison circuit includes a comparator T2, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8;
the positive input end of the comparator T2 is connected with the divided voltage; the negative input end of the comparator T2 is connected with the reference voltage Vref; one end of the sixth resistor R6 is connected to the reference voltage Vref, and the other end of the sixth resistor R6 is connected to the output end of the comparator T2; one end of the seventh resistor R7 is connected with the output end of the comparator T2, and the other end of the seventh resistor R7 is connected with the eighth resistor R8; the other end of the eighth resistor R8 is connected with the negative direct current BUS BUS-; the other end of the seventh resistor R7 is the control signal output end.
Referring to fig. 4, the power absorption unit includes a first switch Q1, a second switch Q2, a ninth resistor R9, and a tenth resistor R10;
a first end (shown as 1 in the figure) of the first switch tube Q1 is a control signal input end of the power absorption unit; a second end (shown in fig. 2) of the first switching tube Q1 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is connected to the positive dc BUS +; the third end (shown as 3 in the figure) of the first switching tube Q1 is connected with the negative direct current BUS BUS-; a first end (shown as 1 in the figure) of the second switch tube Q2 is connected with a second end (shown as 2 in the figure) of the first switch tube Q1; a second end (shown in fig. 2) of the second switch Q2 is connected to the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the positive dc BUS +; the third terminal (shown as 3 in the figure) of the second switch tube Q2 is connected with the negative direct current BUS-.
Referring to fig. 4 again, an overcurrent protection device Z1 or an overheat protection device Z1 is connected in series between the other end of the tenth resistor R10 and the positive dc BUS +.
To better illustrate the present embodiment, the operation of the apparatus is described below with reference to fig. 4:
1. the illumination gradually changes from weak to strong:
the control unit generates a reference voltage VREF through the adjustable shunt regulator T1, and the reference voltage VREF is used for controlling the switching-in and switching-off of the power absorption unit.
Under weak light, the output voltage of the photovoltaic panel is extremely low and far reaches the starting voltage V1 of the auxiliary power supply, the adjustable shunt regulator T1 cannot work normally, and the repeated starting function of the auxiliary power supply is not influenced no matter whether the power absorption unit is cut off or put into operation.
The light intensity is gradually increased until the adjustable shunt regulator T1 works normally, but the light intensity does not reach the cut-off voltage threshold V2 of the power absorption unit, the output of the comparator T2 is low level, Q1 is cut off, Q2 is conducted, and the power absorption unit is put into use.
When the voltage of the photovoltaic panel increases to be larger than V2, the output of the comparator T2 is in a high level, Q1 is conducted, Q2 is cut off, and the power absorption unit is cut off.
When the voltage of the photovoltaic panel continues to increase to be larger than V1(V1 is larger than or equal to V2), the auxiliary power supply is started, and the auxiliary power supply does not have the problem of repeated starting because the energy of the photovoltaic panel is enough.
2. The illumination gradually becomes weaker from strong:
the illumination is stronger, and photovoltaic board output voltage is very high (auxiliary power source work), and comparator T2 output high level, and Q1 switches on, and Q2 cuts off, and the power absorption unit is amputated.
And the illumination becomes weak, and the auxiliary power supply is turned off due to insufficient output power of the photovoltaic panel.
After the auxiliary power supply is turned off, the output voltage of the photovoltaic panel rises and reaches the starting voltage of the auxiliary power supply, the auxiliary power supply is turned on again, due to the fact that the power of the photovoltaic panel is insufficient, the output voltage of the photovoltaic panel is lower than V2 quickly, namely the bus voltage is less than or equal to V2, the output of the comparator T2 is low level, Q1 is turned off, Q2 is turned on, and the power absorption unit is put into use.
According to the device for avoiding the repeated starting of the auxiliary power supply of the photovoltaic inverter, the power absorption unit is controlled by the control unit; the problem of repeated starting of an auxiliary power supply of the conventional photovoltaic inverter is solved; the fault risks such as fire and the like caused by long-term operation of the absorption power unit due to the fact that the auxiliary power supply cannot work normally under the low-temperature condition or after the auxiliary power supply fails are avoided; the device has good low-temperature performance, low failure rate and high reliability.
The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and are not intended to limit the scope of the claims of the application accordingly. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present application are intended to be within the scope of the claims of the present application.
Claims (7)
1. The device for avoiding the repeated starting of the auxiliary power supply of the photovoltaic inverter is characterized by comprising a control unit and a power absorption unit which are connected in parallel between a positive direct current bus and a negative direct current bus;
the control signal output end of the control unit is connected with the control signal input end of the power absorption unit;
the control unit is used for outputting a first control signal to control the power absorption unit to stop working under the condition that the voltage between the positive direct current bus and the negative direct current bus is greater than a threshold voltage; and the power absorption unit is also used for outputting a second control signal to control the power absorption unit to work under the condition that the voltage between the positive direct current bus and the negative direct current bus is not more than the threshold voltage.
2. The apparatus for avoiding repetitive start-up of an auxiliary power supply of a photovoltaic inverter as set forth in claim 1, wherein said control unit comprises a reference voltage generating circuit, a voltage dividing circuit and a comparing circuit;
the reference voltage generating circuit is used for generating a reference voltage;
the voltage division circuit is used for generating a divided voltage according to the voltage between the positive direct current bus and the negative direct current bus;
the comparison circuit is used for comparing the reference voltage with the divided voltage and outputting the first control signal or the second control signal through a control signal output end of the comparison circuit according to a comparison result.
3. The apparatus for avoiding repetitive start-up of an auxiliary power supply of a photovoltaic inverter as claimed in claim 2, wherein the reference voltage generating circuit comprises an adjustable shunt regulator, a first resistor, a second resistor and a third resistor;
one end of the first resistor is connected with the positive direct current bus, and the other end of the first resistor is connected with the first end of the adjustable shunt regulator; one end of the second resistor is connected with the first end of the adjustable parallel voltage stabilizer, and the other end of the second resistor is connected with the second end of the adjustable parallel voltage stabilizer; one end of the third resistor is connected with the second end of the adjustable parallel voltage stabilizer, and the other end of the third resistor is connected with the negative direct current bus; and the third end of the adjustable parallel voltage stabilizer is connected with the negative direct current bus.
4. The apparatus of claim 2, wherein the voltage divider circuit comprises a fourth resistor and a fifth resistor connected in series.
5. The apparatus for avoiding repetitive start-up of an auxiliary power supply of a photovoltaic inverter as set forth in claim 2, wherein said comparison circuit comprises a comparator, a sixth resistor, a seventh resistor, and an eighth resistor;
the positive input end of the comparator is connected with the divided voltage; the negative input end of the comparator is connected with the reference voltage; one end of the sixth resistor is connected to the reference voltage, and the other end of the sixth resistor is connected with the output end of the comparator; one end of the seventh resistor is connected with the output end of the comparator, and the other end of the seventh resistor is connected with the eighth resistor; the other end of the eighth resistor is connected with the negative direct current bus; the other end of the seventh resistor is the control signal output end.
6. The apparatus for avoiding repeated start-up of an auxiliary power supply of a photovoltaic inverter as claimed in claim 1, wherein the power absorption unit comprises a first switch tube, a second switch tube, a ninth resistor and a tenth resistor;
the first end of the first switch tube is a control signal input end of the power absorption unit; the second end of the first switch tube is connected with one end of the ninth resistor, and the other end of the ninth resistor is connected with the positive direct current bus; the third end of the first switching tube is connected with the negative direct current bus; the first end of the second switch tube is connected with the second end of the first switch tube; the second end of the second switch tube is connected with the tenth resistor, and the other end of the tenth resistor is connected with the positive direct current bus; and the third end of the second switch tube is connected with the negative direct current bus.
7. The apparatus for avoiding repeated start-up of an auxiliary power supply of a photovoltaic inverter as claimed in claim 6, wherein an overcurrent protection device or an overheat protection device is connected in series between the other end of the tenth resistor and the positive DC bus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920645249.6U CN209963948U (en) | 2019-05-07 | 2019-05-07 | Device for preventing auxiliary power supply of photovoltaic inverter from being started repeatedly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920645249.6U CN209963948U (en) | 2019-05-07 | 2019-05-07 | Device for preventing auxiliary power supply of photovoltaic inverter from being started repeatedly |
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| Publication Number | Publication Date |
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| CN209963948U true CN209963948U (en) | 2020-01-17 |
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| CN201920645249.6U Active CN209963948U (en) | 2019-05-07 | 2019-05-07 | Device for preventing auxiliary power supply of photovoltaic inverter from being started repeatedly |
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