CN213151926U - Discharge circuit and photovoltaic inverter - Google Patents

Discharge circuit and photovoltaic inverter Download PDF

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Publication number
CN213151926U
CN213151926U CN202021359059.7U CN202021359059U CN213151926U CN 213151926 U CN213151926 U CN 213151926U CN 202021359059 U CN202021359059 U CN 202021359059U CN 213151926 U CN213151926 U CN 213151926U
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China
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circuit
direct current
discharge
output end
current bus
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CN202021359059.7U
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程鹏
李超
李慧鹏
齐红超
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Beijing Dynamic Power Co Ltd
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Beijing Dynamic Power Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Abstract

The embodiment of the application discloses a discharge circuit and a photovoltaic inverter, relates to the technical field of discharge, and aims to prolong the service life of the photovoltaic inverter to a certain extent. The discharge circuit includes: the circuit comprises a discharge circuit unit, a switch subunit circuit and a voltage division subunit circuit; the input end of the switch subunit circuit is used for being connected with the output end of the switching power supply, the first output end of the switch subunit circuit is connected with the first output end of the voltage dividing subunit circuit, and the second output end of the switch subunit circuit is used for being connected with the negative electrode of the direct-current bus; the first input end of the voltage dividing subunit circuit is used for being connected with the positive electrode of the direct current bus, the first output end of the voltage dividing subunit circuit is connected with the first input end of the discharge unit circuit, and the second output end of the voltage dividing subunit circuit is used for being connected with the negative electrode of the direct current bus; and a second input end and a first output end of the discharge unit circuit are respectively used for being correspondingly connected with the positive pole and the negative pole of the direct current bus. The application is suitable for discharging the solar panel.

Description

Discharge circuit and photovoltaic inverter
Technical Field
The application relates to the technical field of discharging, especially relates to a discharge circuit and photovoltaic inverter.
Background
In order to solve the problem of the decreasing energy resources, a solar photovoltaic power generation system is widely applied, the system utilizes the photovoltaic effect of a solar cell semiconductor material to directly convert solar radiation energy into electric energy, a photovoltaic inverter in the solar photovoltaic power generation system can convert variable direct current voltage on a solar polar plate into alternating current, but the output power of the solar polar plate is very small due to weak sunlight in the morning and evening, the output power of the solar polar plate is not enough to support the normal work of a switching power supply in the photovoltaic inverter, but the switching power supply can still be started when the voltage of the solar polar plate is higher, the voltage of the solar polar plate is reduced to be below the working threshold of the switching power supply plate after the starting, at the moment, the switching power supply is cut off again, when the voltage of the solar polar plate is increased again, the switching power supply can be started again, the switching power supply is repeatedly restarted, and the whole photovoltaic inverter, in this way, the service life of the photovoltaic inverter is shortened.
SUMMERY OF THE UTILITY MODEL
In view of this, the present disclosure provides a discharge circuit and a photovoltaic inverter, which can prolong the service life of the photovoltaic inverter to a certain extent.
The embodiment of the application provides a discharge circuit, is applied to photovoltaic inverter, includes: control unit circuit and discharge cell circuit, wherein, the control unit circuit includes: the switch subunit circuit and the voltage division subunit circuit; the input end of the switch subunit circuit is used for being connected with the output end of a switch power supply, the first output end of the switch subunit circuit is connected with the first output end of the voltage dividing subunit circuit, and the second output end of the switch subunit circuit is used for being connected with the negative electrode of the direct-current bus; the first input end of the voltage dividing subunit circuit is used for being connected with the anode of the direct current bus, the first output end of the voltage dividing subunit circuit is connected with the first input end of the discharge unit circuit, and the second output end of the voltage dividing subunit circuit is used for being connected with the cathode of the direct current bus; and the second input end of the discharge unit circuit is connected with the anode of the direct current bus, and the first output end of the discharge unit circuit is connected with the cathode of the direct current bus.
According to a specific implementation manner of the embodiment of the present application, the discharge cell circuit includes: a relay and a discharge resistor; one end of the discharging resistor is used for being connected with the positive electrode of the direct current bus, the other end of the discharging resistor is connected with the first contact terminal of the relay, the second contact terminal of the relay is used for being connected with the negative electrode of the direct current bus, the first coil terminal of the relay is connected with the first output end of the voltage dividing subunit circuit, and the second coil terminal of the relay is used for being connected with the negative electrode of the direct current bus.
According to a specific implementation manner of the embodiment of the present application, the discharge unit circuit further includes: and the first end of the current-limiting resistor is connected with the first coil terminal of the relay, and the second end of the current-limiting resistor is connected with the first output end of the voltage dividing subunit circuit.
According to a specific implementation manner of the embodiment of the present application, the discharge unit circuit further includes: and the cathode of the freewheeling diode is connected with the first coil terminal of the relay, and the anode of the freewheeling diode is used for being connected with the cathode of the direct current bus.
According to a specific implementation manner of the embodiment of the present application, the voltage-dividing subunit circuit includes: the first end of the first resistor is used for being connected with the positive electrode of the direct current bus, the second end of the first resistor and the first end of the second resistor are respectively connected with the first input end of the discharge unit circuit, and the second end of the second resistor is used for being connected with the negative electrode of the direct current bus.
According to a specific implementation manner of the embodiment of the present application, the switch subunit circuit includes: and the base electrode of the triode is used for being connected with the output end of the switching power supply, the collector electrode of the triode is connected with the first output end of the voltage divider subunit circuit, and the emitting electrode of the triode is used for being connected with the negative electrode of the direct current bus.
According to a specific implementation manner of the embodiment of the present application, the switch subunit circuit further includes: the power supply comprises a first resistor and a second resistor, wherein one end of the first resistor is used for being connected with the output end of the switching power supply, the other end of the first resistor is connected with one end of the second resistor and the base electrode of the triode, and the other end of the second resistor is used for being connected with the negative electrode of the direct current bus.
The embodiment of the present application further provides a photovoltaic inverter, including: a switching power supply and a discharge circuit of any of the above embodiments; the input end of the switch power supply is used for being connected with a direct current bus, and the output end of the switch power supply is connected with the input end of a switch subunit circuit in the discharge circuit.
The application provides a discharge circuit and a photovoltaic inverter, the input end of a switch subunit circuit is used for being connected with the output end of a switch power supply, the first output end of the switch subunit circuit is connected with the first output end of a voltage division subunit circuit, the second output end of the switch subunit circuit is used for being connected with the negative pole of a direct current bus, the first input end of the voltage division subunit circuit is used for being connected with the positive pole of the direct current bus, the first output end of the voltage division subunit circuit is connected with the first input end of the discharge unit circuit, the second output end of the voltage division subunit circuit is used for being connected with the negative pole of the direct current bus, the second input end of the discharge unit circuit is used for being connected with the positive pole of the direct current bus, the first output end of the discharge unit circuit is used for being connected with the negative pole of the direct current bus, when the voltage between the direct current buses is small, the switch power supply has, the switching subunit circuit is disconnected, at the moment, the voltage dividing subunit circuit provides working voltage for the discharging unit circuit, so that the discharging unit circuit works, and as the discharging unit circuit is connected with the positive electrode and the negative electrode of the direct current bus, when the discharging unit circuit works, the direct current bus is discharged, so that the voltage between the direct current buses is reduced, the voltage between the direct current buses cannot be in a virtual high phenomenon, and further, the switching power supply in the photovoltaic inverter cannot be repeatedly restarted and turned off, so that the service life of the photovoltaic inverter can be prolonged to a certain extent through the use of the discharging circuit in the embodiment.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic structural diagram of a discharge circuit according to an embodiment of the present disclosure.
Detailed Description
The embodiments of the present application will be described in detail below with reference to the accompanying drawings.
It should be understood that the embodiments described are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 is a schematic structural diagram of a discharge circuit according to an embodiment of the present application, and as shown in fig. 1, the discharge circuit according to the present embodiment is applied to a photovoltaic inverter, and may include: a control unit circuit 1 and a discharge unit circuit 2, wherein the control unit circuit 1 includes: a switch subunit circuit 10 and a voltage divider subunit circuit 12; the input end of the switch subunit circuit 10 is used for being connected with the output end of the switching power supply, the first output end of the switch subunit circuit 10 is connected with the first output end of the voltage dividing subunit circuit 12, and the second output end of the switch subunit circuit 10 is used for being connected with the negative electrode of the direct-current bus; a first input end of the voltage dividing subunit circuit 12 is used for being connected with the positive electrode of the direct current bus, a first output end of the voltage dividing subunit circuit 12 is connected with a first input end of the discharge unit circuit 2, and a second output end of the voltage dividing subunit circuit 12 is used for being connected with the negative electrode of the direct current bus; the second input end of the discharge unit circuit 2 is used for being connected with the positive pole of the direct current bus, and the first output end of the discharge unit circuit 2 is used for being connected with the negative pole of the direct current bus.
The photovoltaic inverter is used in a solar photovoltaic power generation system, can convert variable direct-current voltage generated by a photovoltaic solar panel into alternating current, and can be used by matching with common alternating-current power supply equipment. The photovoltaic inverter comprises a switching power supply, the switching power supply is connected with the direct current bus, and the voltage on the direct current bus is converted into the direct current power supply to be used by other components or circuit modules in the photovoltaic inverter.
The voltage output by the photovoltaic array is stored in a solar panel, which comprises a positive plate and a negative plate, wherein a lead connected with the positive plate can be called as a positive pole of a direct current bus, and a lead connected with the negative plate can be called as a negative pole of the direct current bus.
Because the second input end of the discharge unit circuit 2 is used for being connected with the anode of the direct current bus, and the first output end of the discharge unit circuit 2 is used for being connected with the cathode of the direct current bus, when the discharge unit circuit 2 works, the discharge unit circuit can discharge the direct current bus, so that the voltage between the direct current buses is reduced; when the discharge cell circuit 2 does not operate, the discharge cell circuit 2 does not discharge the dc bus, that is, the voltage between the dc buses does not decrease.
The control unit circuit 1 controls the discharge unit circuit, specifically, controls the discharge unit circuit to operate to discharge the dc bus, or controls the discharge unit circuit not to operate, that is, may not discharge the dc bus.
A first output end of a switch subunit circuit 10 in the control unit circuit 1 is connected with a first output end of a voltage dividing subunit circuit 12, and a second output end of the switch subunit circuit 10 is used for being connected with a negative electrode of a direct current bus, so that the first output end and the second output end of the switch subunit circuit 10 are connected with the first output end and the second output end of the voltage dividing subunit circuit 12 in parallel, an input end of the switch subunit circuit 10 is used for being connected with an output end of a switching power supply, when the output end of the switching power supply has voltage, so that the switch subunit circuit 10 is switched on, the voltage between the first output end and the second output end of the voltage dividing subunit circuit 12 is zero, and at the moment, the discharge unit circuit 1 does not discharge to the direct current bus; when the output end of the switching power supply has no voltage and the switch subunit circuit 10 is disconnected, the voltage between the first output end and the second output end of the voltage dividing subunit circuit 12 is a partial voltage value of the total voltage between the direct current buses, the voltage value enables the discharge unit circuit 1 to work, the second input end of the discharge unit circuit 2 is used for being connected with the positive electrode of the direct current bus, the first output end of the discharge unit circuit 2 is used for being connected with the negative electrode of the direct current bus, and the discharge unit circuit 1 works and can discharge the direct current bus.
When the voltage divider is used, the voltages of the first input end and the second output end of the voltage divider subunit circuit 12 are voltages between the direct current buses, so that the voltages of the first output end and the second output end of the voltage divider subunit circuit 12 can provide voltages for the discharge unit circuit 1, so that the discharge circuit unit 1 discharges the direct current buses.
The use process of the discharge circuit of the embodiment is as follows: when the voltage on the direct current bus is very small, the switching power supply is not enough to be started at the moment, the first input end of the voltage dividing subunit circuit obtains the voltage from the positive electrode of the direct current bus, so that the voltage between the first output end and the second output end of the voltage dividing subunit circuit is partial voltage of the total voltage between the direct current buses, the voltage between the first output end and the second output end of the voltage dividing subunit circuit can enable the discharging unit circuit to work, the second input end of the discharging unit circuit is used for being connected with the positive electrode of the direct current bus, the first output end of the discharging unit circuit is used for being connected with the negative electrode of the direct current bus, and therefore the discharging unit circuit can discharge the voltage between the positive direct current bus and the negative direct current bus, the voltage between the direct current buses is reduced, and the voltage of the direct current bus cannot be in a virtual high condition; the voltage on the direct current bus gradually rises along with the increase of the illumination intensity, when the voltage rises to the voltage enough to enable the switching power supply to work normally, the output end of the switching power supply outputs the voltage, since the input of the switch subunit circuit is adapted to be connected to the output of the switching power supply, then the input of the switch subunit circuit has a voltage, the voltage makes the switch subunit circuit conducted, and the first output terminal of the switch subunit circuit and the second output terminal of the switch subunit circuit are connected in parallel with the first output terminal and the second output terminal of the voltage dividing subunit circuit, so that the first output terminal and the second output terminal of the voltage dividing subunit circuit are short-circuited, thereby making the discharge unit circuit not work, the direct current buses are not discharged, and the whole photovoltaic inverter can work normally due to the fact that the voltage between the direct current buses is enough to enable the switching power supply to work normally.
It can be understood that even though the discharging subunit circuit discharges the dc bus, the voltage on the dc bus gradually increases as the intensity of the light increases, i.e. the discharging subunit circuit discharges the dc bus by an amount smaller than the voltage generated by the solar panel when the light is increased.
In this embodiment, the input terminal of the switch subunit circuit is used to connect to the output terminal of the switching power supply, the first output terminal of the switch subunit circuit is connected to the first output terminal of the voltage divider subunit circuit, the second output terminal of the switch subunit circuit is used to connect to the negative electrode of the dc bus, the first input terminal of the voltage divider subunit circuit is used to connect to the positive electrode of the dc bus, the first output terminal of the voltage divider subunit circuit is connected to the first input terminal of the discharge unit circuit, the second output terminal of the voltage divider subunit circuit is used to connect to the negative electrode of the dc bus, the second input terminal of the discharge unit circuit is used to connect to the positive electrode of the dc bus, the first output terminal of the discharge unit circuit is used to connect to the negative electrode of the dc bus, when the voltage between the dc buses is small, the switching power supply has no output voltage, so that the switch subunit circuit is disconnected, the voltage division subunit circuit provides working voltage for the discharge unit circuit to enable the discharge unit circuit to work, and because the discharge unit circuit is connected with the positive electrode and the negative electrode of the direct current bus, when the discharge unit circuit works, the direct current bus is discharged, the voltage between the direct current buses is reduced, the voltage between the direct current buses cannot be high, and further, a switching power supply in the photovoltaic inverter cannot be repeatedly restarted and turned off, so that the service life of the photovoltaic inverter can be prolonged to a certain extent through the use of the discharge circuit in the embodiment.
Referring to fig. 1, a discharge circuit provided in another embodiment of the present application is substantially the same as the foregoing embodiments, except that a discharge unit circuit 2 of the present embodiment includes: relay RY1 and discharge resistor R3;
one end of a discharge resistor R3 is used for being connected with the positive electrode of the direct-current bus, the other end of the discharge resistor R3 is connected with a first contact terminal of a relay RY1, a second contact terminal of the relay RY1 is used for being connected with the negative electrode of the direct-current bus, a first coil terminal of the relay RY1 is connected with a first output end of the voltage dividing subunit circuit 12, and a second coil terminal of the relay RY1 is used for being connected with the negative electrode of the direct-current bus.
The relay RY1 is an electric control device that generates a predetermined step change in the controlled amount in an electric output circuit when a change in the input amount meets a predetermined requirement.
The resistance value of the discharge resistor R3 can be determined according to the requirement on the discharge speed; a given resistance value may be achieved by series-parallel connection of one or several resistors.
When the voltage between the first output end and the second output end of the voltage dividing subunit circuit 12 is not 0 and the size is enough to enable the coil of the relay RY1 to have current flowing through, the internal contact of the relay is attracted, at the moment, the discharge resistor R3 is connected between the positive electrode and the negative electrode of the direct current bus to form a loop, and the discharge resistor R3 discharges the direct current bus; when the switch subunit circuit 10 is closed, the voltage between the first output end and the second output end of the voltage divider subunit circuit 12 is 0, no current flows in the coil of the relay RY1, so that the internal contacts of the relay are disconnected, and at this time, the discharge resistor R3 is disconnected with the positive electrode and the negative electrode of the dc bus, that is, the dc bus is not discharged.
In order to limit the current flowing through the coil of the relay RY1 and avoid the current flowing through the relay coil from being too large to damage the relay coil, in one example, the discharging unit circuit further comprises: a first end of a current limiting resistor R6 and a first end of a current limiting resistor R6 are connected with a first coil terminal of the relay RY1, and a second end of a current limiting resistor R6 is connected with a first output end of the voltage dividing subunit circuit 12.
It can be understood that when the coil of the relay is energized, a magnetic field is generated to pull in the relay, and at the moment of power failure, due to the action of the magnetic field, a high reverse voltage (called a back electromotive force) is generated across the coil, and the reverse voltage may be several times higher than a power supply voltage, which may possibly cause abnormal operation and even breakdown damage of devices of the control circuit, such as burning out the transistor Q1.
In order to avoid the above problem when the coil of the relay RY1 is de-energized, as an alternative embodiment, as shown in fig. 1, the discharge cell circuit 2 further includes: and the cathode of the freewheeling diode D1 is connected with the first coil terminal of the coil of the relay RY1, and the anode of the freewheeling diode is used for being connected with the cathode of the direct-current bus, namely, the freewheeling diode D1 is reversely connected in parallel at two ends of the coil of the relay RY1, so that reverse voltage generated at two ends of the coil at the moment of power failure has a leakage loop, and the electronic devices in the circuit can be prevented from being damaged.
Referring to fig. 1, a discharge circuit provided in another embodiment of the present application is substantially the same as the foregoing embodiments, except that the voltage divider subunit circuit 12 of the present embodiment includes: the first end of the first resistor R1 is used for being connected with the positive electrode of the direct current bus, the second end of the first resistor R1 and the first end of the second resistor R2 are respectively connected with the first input end of the discharge unit circuit 2, and the second end of the second resistor R2 is used for being connected with the negative electrode of the direct current bus.
The voltage across the first resistor R1 and the second resistor R2 is the voltage between the dc buses, and the second resistor R2 can provide the operating voltage for the discharge unit circuit 2, so that the discharge unit circuit 2 discharges the voltage between the dc buses.
Referring to fig. 1, a discharge circuit provided in another embodiment of the present application is substantially the same as the foregoing embodiments, except that a switch subunit circuit 10 of the present embodiment includes: and a triode Q1, wherein the base electrode of the triode Q1 is used for being connected with the output end of the switching power supply, the collector electrode of the triode Q1 is connected with the first output end of the voltage dividing subunit circuit 12, and the emitter electrode of the triode Q1 is used for being connected with the negative electrode of the direct current bus.
The transistor Q1 is a semiconductor device for controlling current, and is also called a bipolar transistor or a transistor. The function is to amplify the weak signal into an electric signal with larger amplitude value, and the electric signal is also used as a contactless switch. The transistor may have both NPN and PNP configurations, and in one example, the transistor Q1 may be an NPN transistor.
When the switching power supply does not output voltage, the triode Q1 is in a cut-off state, and the voltage dividing subunit circuit 12 collects voltage from the direct current bus to provide voltage for the discharge unit circuit, so that the discharge unit circuit discharges to the direct current bus; when the switching power supply has output voltage, the triode Q1 is in a conducting state, and the first output end and the second output end of the voltage dividing subunit circuit are short-circuited by the triode Q1, so that the voltage dividing subunit circuit cannot provide working voltage for the discharging unit circuit, the discharging unit circuit and the solar positive and negative plates cannot form a loop, and at the moment, the discharging circuit unit does not discharge the direct current bus.
In order to reduce the voltage input to the transistor Q1 to protect the transistor Q1, the switch subunit circuit 10 further includes: one end of the third resistor R4 is used for being connected with the output end of the switching power supply, the other end of the third resistor R4 is connected with one end of the fourth resistor R5 and the base of the triode Q1, and the other end of the fourth resistor R5 is used for being connected with the negative electrode of the direct-current bus.
The present application further provides a photovoltaic inverter, comprising: switching power supplies and discharge circuits in the foregoing embodiments; the input end of the switch power supply is used for being connected with the direct current bus, and the output end of the switch power supply is connected with the input end of the switch subunit circuit in the discharge circuit.
In the embodiment, the output end of the switching power supply is connected with the input end of the switch subunit circuit in the discharge circuit, so that when the voltage on the direct-current bus is small, the discharge circuit discharges the direct-current bus, the virtual high voltage cannot be generated on the direct-current bus, the repeated starting and the turn-off of the photovoltaic inverter are avoided, and the service life of the photovoltaic inverter is prolonged.
The following describes a scheme of the discharge circuit in the present application in detail with a specific embodiment.
Referring to fig. 1, the discharge circuit in the present embodiment includes: the power supply comprises a discharge resistor R3, a relay RY1, voltage division resistors R1 and R2, a triode Q1 and voltage division resistors R4 and R5; one end of the discharge resistor R3 is connected with the positive electrode of the direct-current bus, the other end of the discharge resistor R3 is connected with the first contact of the relay RY1, and the second contact of the relay RY1 is used for being connected with the negative electrode of the direct-current bus; a first coil terminal of the relay RY1 is connected between the voltage dividing resistors R1 and R2 through a current limiting resistor R6, and a freewheeling diode D1 is connected in anti-parallel with a coil of the relay RY 1; one end of the voltage dividing resistor R1 is connected with the anode of the direct current bus, and one end of the voltage dividing resistor R2 is connected with the cathode of the direct current bus; the base electrode of the triode Q1 is connected between the divider resistor R4 and the divider resistor R5, one end of the divider resistor R4 is used for being connected with the output end of the switching power supply, one end of the divider resistor R5 is used for being connected with the negative electrode of the direct current BUS, the source electrode of the triode Q1 is connected between the divider resistor R1 and the divider resistor R2, the emitting electrode of the triode Q1 is used for being connected with the negative electrode of the direct current BUS, BUS + in the figure is the positive electrode of the direct current BUS, and BUS-is the negative electrode of the direct current BUS.
When the voltage output by the solar photovoltaic polar plate rises gradually in the morning, the voltage can start the switching power supply in the photovoltaic inverter but is not enough to maintain the normal operation of the switching power supply, at the moment, the relay is adopted for attracting, so that the discharging resistor is connected with the direct current bus through the direct current bus, the direct current bus can be discharged, and the phenomenon of virtual height of the direct current bus is avoided. When the dc bus voltage is high enough and the normal operation of the switching power supply can be maintained, the switching power supply outputs 5V voltage, the triac Q1 is turned on, and further, the relay is turned off, thereby ending the discharge.
When the output voltage of the photovoltaic polar plate is gradually reduced at night, the switching power supply is powered off, the triode stops working after the power off, the relay is conducted again, the discharging resistor discharges the bus again, the bus voltage can be always reduced, and the switching power supply cannot be restarted.
The relay is automatically controlled by collecting the bus voltage output by the photovoltaic polar plate, and when the polar plate voltage reaches a certain value, the relay is automatically attracted, so that the discharging resistor discharges to the direct current bus. Meanwhile, the relay is controlled by a switching power supply in the inverter, when the bus voltage can support the switching power supply to continuously work, the switching power supply triggers the triode to act, the relay is turned off after the triode is turned on, so that the resistor stops discharging, the photovoltaic polar plate can be automatically discharged in the morning and evening, the photovoltaic inverter is prevented from being restarted repeatedly, and the service life of the photovoltaic inverter can be prolonged.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (8)

1. A discharge circuit applied to a photovoltaic inverter is characterized by comprising: control unit circuit and discharge cell circuit, wherein, the control unit circuit includes: the switch subunit circuit and the voltage division subunit circuit;
the input end of the switch subunit circuit is used for being connected with the output end of a switch power supply, the first output end of the switch subunit circuit is connected with the first output end of the voltage dividing subunit circuit, and the second output end of the switch subunit circuit is used for being connected with the negative electrode of the direct-current bus;
the first input end of the voltage dividing subunit circuit is used for being connected with the anode of the direct current bus, the first output end of the voltage dividing subunit circuit is connected with the first input end of the discharge unit circuit, and the second output end of the voltage dividing subunit circuit is used for being connected with the cathode of the direct current bus;
and the second input end of the discharge unit circuit is connected with the anode of the direct current bus, and the first output end of the discharge unit circuit is connected with the cathode of the direct current bus.
2. The discharge circuit of claim 1, wherein the discharge cell circuit comprises: a relay and a discharge resistor;
one end of the discharging resistor is used for being connected with the positive electrode of the direct current bus, the other end of the discharging resistor is connected with the first contact terminal of the relay, the second contact terminal of the relay is used for being connected with the negative electrode of the direct current bus, the first coil terminal of the relay is connected with the first output end of the voltage dividing subunit circuit, and the second coil terminal of the relay is used for being connected with the negative electrode of the direct current bus.
3. The discharge circuit of claim 2, wherein the discharge cell circuit further comprises: and the first end of the current-limiting resistor is connected with the first coil terminal of the relay, and the second end of the current-limiting resistor is connected with the first output end of the voltage dividing subunit circuit.
4. The discharge circuit of claim 3, wherein the discharge cell circuit further comprises: and the cathode of the freewheeling diode is connected with the first coil terminal of the relay, and the anode of the freewheeling diode is used for being connected with the cathode of the direct current bus.
5. The discharge circuit of claim 1, wherein the voltage-dividing subcell circuit comprises: the first end of the first resistor is used for being connected with the positive electrode of the direct current bus, the second end of the first resistor and the first end of the second resistor are respectively connected with the first input end of the discharge unit circuit, and the second end of the second resistor is used for being connected with the negative electrode of the direct current bus.
6. The discharge circuit of claim 1, wherein the switch subunit circuit comprises: and the base electrode of the triode is used for being connected with the output end of the switching power supply, the collector electrode of the triode is connected with the first output end of the voltage divider subunit circuit, and the emitting electrode of the triode is used for being connected with the negative electrode of the direct current bus.
7. The discharge circuit of claim 6, wherein the switch subunit circuit further comprises: the power supply comprises a first resistor and a second resistor, wherein one end of the first resistor is used for being connected with the output end of the switching power supply, the other end of the first resistor is connected with one end of the second resistor and the base electrode of the triode, and the other end of the second resistor is used for being connected with the negative electrode of the direct current bus.
8. A photovoltaic inverter, comprising: a switching power supply and a discharge circuit as claimed in any one of the preceding claims 1 to 7; the input end of the switch power supply is used for being connected with a direct current bus, and the output end of the switch power supply is connected with the input end of a switch subunit circuit in the discharge circuit.
CN202021359059.7U 2020-07-10 2020-07-10 Discharge circuit and photovoltaic inverter Active CN213151926U (en)

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