Discharging circuit and inverter

Abstract

The utility model relates to the technical field of power electronics, and discloses a discharge circuit and an inverter, the discharge circuit comprises a voltage division circuit, a reference circuit, a switch circuit and a bleeder circuit, the first end of the voltage division circuit receives the bus voltage of the inverter, and the second end of the voltage division circuit receives the bus voltage of the inverter; the first end of the comparator is also connected with the first end of the switching circuit and the first end of the bleeder circuit, the second end of the comparator is connected with the first end of the reference circuit, and the third end of the comparator is connected with the second end of the reference circuit; the fourth end of the comparator circuit is grounded after being connected with the third end of the reference circuit, the second end of the switching circuit and the second end of the bleeder circuit; the fourth end of the reference circuit is connected with the third end of the switching circuit; and the fourth end of the switching circuit is connected with the third end of the bleeder circuit. According to the utility model, the discharge function can be automatically opened or closed according to the magnitude of the power supply voltage, unnecessary energy consumption is avoided, and the working efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and particularly relates to a discharge circuit and an inverter. Background Art

[0002] In existing photovoltaic grid-connected inverters, the bus voltage is generally divided into positive and negative voltages, electrolytic capacitors are used to support the bus voltage, and resistors are connected in parallel on the positive and negative buses to play a role in voltage equalization and discharging. The resistors always consume power. If the resistance value of the parallel resistor is large, the discharging speed will be slow and the discharging time will be long; if the resistance value of the parallel resistor is small, unnecessary energy consumption will be caused. Content of the Utility Model

[0003] Therefore, the technical problem to be solved by the utility model is to solve the problem in the prior art that the bus discharge circuit cannot automatically start or stop discharging according to the BUS voltage, resulting in high energy consumption, so as to provide a discharge circuit and an inverter.

[0004] To achieve the above object, the utility model provides the following technical solutions:

[0005] In a first aspect, a discharge circuit of the utility model is applied to an inverter. The discharge circuit includes: a voltage dividing circuit, a reference circuit, a switching circuit and a discharging circuit. Among them, for the voltage dividing circuit, its first end receives the bus voltage of the inverter, its first end is also connected to the first end of the switching circuit and the first end of the discharging circuit, its second end is connected to the first end of the reference circuit, its third end is connected to the second end of the reference circuit, and its fourth end is connected to the third end of the reference circuit, the second end of the switching circuit and the second end of the discharging circuit and then grounded. It is used for dividing the bus voltage; for the reference circuit, its fourth end is connected to the third end of the switching circuit, and it is used for switching its own on-off state based on the magnitude of the reference voltage inside it and the voltage at the third end of the voltage dividing circuit; for the switching circuit, its fourth end is connected to the third end of the discharging circuit; when the bus voltage is greater than or equal to a preset voltage, the reference circuit is turned on, so that the voltage at the third end of the switching circuit gradually rises to the conduction voltage drop of the switching circuit, then the switching circuit is turned on and the discharging circuit is turned off, and the bus stops discharging; when the bus voltage is less than the preset voltage, the reference circuit is turned off, so that the voltage at the third end of the switching circuit gradually drops to be lower than the conduction voltage drop of the switching circuit, then the switching circuit is turned off and the discharging circuit is turned on, and the bus voltage starts to discharge through the discharging circuit.

[0006] The discharge circuit provided by the present utility model sets a preset voltage. When the bus voltage is higher than or equal to the preset voltage, the voltage at the third terminal of the voltage dividing circuit is greater than or equal to the reference voltage, causing the reference circuit to conduct. Then, the voltage at the third terminal of the switching circuit gradually increases, causing the switching circuit to conduct and the discharge circuit to cut off. When the bus voltage is lower than the preset voltage, the voltage at the third terminal of the voltage dividing circuit is less than the reference voltage, causing the reference circuit to cut off. Then, the voltage at the third terminal of the switching circuit gradually decreases, causing the switching circuit to cut off and the discharge circuit to conduct. The discharge circuit can automatically switch the on-off states of internal components according to the magnitude of the bus voltage, timely turn on or off the discharge function, ensure no discharge when the bus voltage is high, avoid unnecessary energy consumption, and at the same time can timely discharge when the bus voltage is low, improving the degree of automation and work efficiency.

[0007] In an optional embodiment, the voltage dividing circuit includes: a first resistor, a second resistor, and a third resistor. Among them, for the first resistor, its first terminal is connected to the first terminal of the switching circuit, and its second terminal is connected to the first terminal of the second resistor and the first terminal of the reference circuit; for the second resistor, its second terminal is connected to the first terminal of the third resistor and the second terminal of the reference circuit; for the third resistor, its second terminal is connected to the third terminal of the reference circuit.

[0008] In an optional embodiment, the reference circuit includes: a fourth resistor, a fifth resistor, and a first voltage stabilizing circuit. Among them, for the fourth resistor, its first terminal is connected to the second terminal of the voltage dividing circuit, and its second terminal is connected to the first terminal of the first voltage stabilizing circuit; for the fifth resistor, its first terminal is connected to the second terminal of the first voltage stabilizing circuit and the third terminal of the switching circuit, and its second terminal is connected to the fourth terminal of the voltage dividing circuit; for the first voltage stabilizing circuit, its third terminal is connected to the third terminal of the voltage dividing circuit. When the bus voltage is greater than or equal to the preset voltage, the voltage at the third terminal of the voltage dividing circuit is greater than or equal to the reference voltage inside the first voltage stabilizing circuit, and the first voltage stabilizing circuit conducts; when the bus voltage is less than the preset voltage, the voltage at the third terminal of the voltage dividing circuit is less than the reference voltage inside the first voltage stabilizing circuit, and the first voltage stabilizing circuit cuts off.

[0009] In an optional embodiment, the first voltage stabilizing circuit includes: a programmable precision voltage reference, whose reference terminal is connected to the third terminal of the voltage dividing circuit, its cathode is connected to the second terminal of the fourth resistor, and its anode is connected to the first terminal of the fifth resistor. When the bus voltage is greater than or equal to the preset voltage, the voltage at the third terminal of the voltage dividing circuit is greater than or equal to the reference voltage of the programmable precision voltage reference, and the programmable precision voltage reference conducts; when the bus voltage is less than the preset voltage, the voltage at the third terminal of the voltage dividing circuit is less than the reference voltage of the programmable precision voltage reference, and the programmable precision voltage reference cuts off.

[0010] The discharge circuit provided by the present utility model has a preset reference voltage in the controllable precision voltage stabilizer. When the voltage at the third terminal of the voltage division circuit is greater than or equal to the reference terminal voltage of the controllable precision voltage stabilizer, the controllable precision voltage stabilizer conducts and current flows through its interior; when the voltage at the third terminal of the voltage division circuit is less than the reference terminal voltage of the controllable precision voltage stabilizer, the controllable precision voltage stabilizer cuts off and no current flows through its interior. The controllable precision voltage stabilizer has low cost and high integration.

[0011] In an alternative embodiment, the switching circuit includes: a sixth resistor, a first switching transistor, and a second voltage stabilizing circuit. Among them, for the sixth resistor, its first terminal is connected to the first terminal of the voltage division circuit, and its second terminal is connected to the first terminal of the first switching transistor, the first terminal of the second voltage stabilizing circuit, and the third terminal of the discharging circuit; for the first switching transistor, its control terminal is connected to the fourth terminal of the reference circuit, and its second terminal is connected to the second terminal of the second voltage stabilizing circuit and the third terminal of the reference circuit; the second voltage stabilizing circuit is used to stabilize the voltage between the first terminal and the second terminal of the first switching transistor; when the bus voltage is greater than or equal to the preset voltage, the reference circuit conducts, causing the control terminal voltage of the first switching transistor to gradually rise to the conduction voltage drop of the first switching transistor, and then the first switching transistor conducts and the discharging circuit cuts off; when the bus voltage is less than the preset voltage, the reference circuit cuts off, causing the control terminal voltage of the first switching transistor to gradually drop below the conduction voltage drop of the first switching transistor, and then the first switching transistor cuts off and the discharging circuit conducts.

[0012] In an alternative embodiment, the second voltage stabilizing circuit includes: a zener diode, whose cathode is connected to the first terminal of the first switching transistor and whose anode is connected to the second terminal of the first switching transistor.

[0013] In an alternative embodiment, the discharging circuit includes: a discharging branch, a second switching transistor, and a protection branch. Among them, for the discharging branch, its first terminal is connected to the first terminal of the voltage division circuit, and its second terminal is connected to the first terminal of the second switching transistor; for the second switching transistor, its control terminal is connected to the first terminal of the protection branch and the fourth terminal of the switching circuit, and its second terminal is connected to the second terminal of the protection branch and the second terminal of the switching circuit; the protection branch is used to limit the voltage between the control terminal and the second terminal of the second switching transistor; when the bus voltage is greater than or equal to the preset voltage, the reference circuit conducts, causing the voltage at the third terminal of the switching circuit to gradually rise to the conduction voltage drop of the switching circuit, and then the switching circuit conducts, the second switching transistor cuts off, and the bus stops discharging; when the bus voltage is less than the preset voltage, the reference circuit cuts off, causing the voltage at the third terminal of the switching circuit to gradually drop below the conduction voltage drop of the switching circuit, and then the switching circuit cuts off, the second switching transistor conducts, and the bus voltage starts to discharge through the discharging branch and the second switching transistor.

[0014] In an alternative embodiment, the discharge branch includes a discharge resistor and a fuse. The discharge resistor has its first end connected to the first end of the voltage dividing circuit and its second end connected to the first end of the fuse. The fuse has its second end connected to the first end of the second switching transistor.

[0015] In an alternative embodiment, the protection branch includes a seventh resistor connected in parallel with the control end and the second end of the second switching transistor.

[0016] In a second aspect, the present utility model provides an inverter, which includes an inverter body and the discharge circuit of the first aspect. The positive bus bar in the inverter body is connected to the first end of the voltage dividing circuit, the first end of the switching circuit, and the first end of the discharge circuit. The negative bus bar in the inverter body is connected to the fourth end of the voltage dividing circuit, the third end of the reference circuit, the second end of the switching circuit, and the second end of the discharge circuit. When the positive bus bar voltage of the inverter body is greater than or equal to a preset voltage, the discharge circuit is cut off and the discharge of the positive bus bar voltage of the inverter body stops. When the positive bus bar voltage of the inverter body is less than the preset voltage, the discharge circuit is turned on and the positive bus bar voltage of the inverter body starts to discharge through the discharge circuit.

[0017] The inverter provided by the present utility model sets a preset voltage. When the bus bar voltage of the inverter is higher than or equal to the preset voltage, the voltage at the third end of the voltage dividing circuit is greater than or equal to the reference voltage, causing the reference circuit to conduct. Then, the voltage at the third end of the switching circuit gradually increases, causing the switching circuit to conduct and the discharge circuit to be cut off. When the bus bar voltage of the inverter is lower than the preset voltage, the voltage at the third end of the voltage dividing circuit is less than the reference voltage, causing the reference circuit to be cut off. Then, the voltage at the third end of the switching circuit gradually decreases, causing the switching circuit to be cut off and the discharge circuit to conduct. The discharge circuit can automatically switch the on / off states of the internal components according to the magnitude of the bus bar voltage of the inverter, timely turn on or off the discharge function, ensure that the inverter does not discharge when the bus bar voltage is high, avoid unnecessary energy consumption, and at the same time can discharge in a timely manner when the bus bar voltage of the inverter is low, improving the degree of automation and work efficiency. Description of the Drawings

[0018] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a composition diagram of a specific example of the discharge circuit according to an embodiment of the present utility model;

[0020] Figure 2Structural diagram of a specific circuit of the discharge circuit according to an embodiment of the present utility model;

[0021] Figure 3 Composition diagram of a specific example of the inverter according to an embodiment of the present utility model;

[0022] Figure 4 Specific flowchart of the discharge process of the inverter according to an embodiment of the present utility model. Detailed implementation manners

[0023] Next, the technical solutions of the present utility model will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of them. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0024] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0025] In the description of the present utility model, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0026] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0027] After the PV inverter is powered on, the BUS voltage gradually increases, and at this time, the inverter operates normally and does not need to discharge; when the PV inverter is powered off, the BUS voltage gradually decreases, and at this time, the bus voltage needs to be quickly discharged. In related technologies, the discharge circuit may consume unnecessary energy during normal operation of the inverter, or when the resistance values of the parallel resistors on the positive and negative buses are large, the discharge may be untimely or slow. Therefore,

[0028] This embodiment provides a discharge circuit, as Figure 1 shown, which is applied to an inverter. The discharge circuit includes: a voltage dividing circuit 1, a reference circuit 2, a switching circuit 3, and a discharging circuit 4.

[0029] As Figure 1 shown, for the voltage dividing circuit 1, its first end receives the bus voltage of the inverter, its first end is also connected to the first end of the switching circuit 3 and the first end of the discharging circuit 4, its second end is connected to the first end of the reference circuit 2, its third end is connected to the second end of the reference circuit 2, and its fourth end is connected to the third end of the reference circuit 2, the second end of the switching circuit 3, and the second end of the discharging circuit 4 and then grounded; for the reference circuit 2, its fourth end is connected to the third end of the switching circuit 3, and it is used to switch its own on-off state based on the magnitude of the reference voltage inside it and the voltage at the third end of the voltage dividing circuit 1.

[0030] Specifically, Figure 1 in the voltage dividing circuit 1 is used to divide the bus voltage, and a reference voltage is built in the reference circuit 2. When the bus voltage is greater than or equal to the preset voltage, after the bus voltage is divided by the voltage dividing circuit 1, the voltage at the third end of the voltage dividing circuit 1 will be greater than or equal to the reference voltage inside the reference circuit 2, causing the reference circuit 2 to conduct and current to flow through it; when the bus voltage is less than the preset voltage, after the bus voltage is divided by the voltage dividing circuit 1, the voltage at the third end of the voltage dividing circuit 1 will be less than the reference voltage inside the reference circuit 2, and the reference circuit 2 will be cut off and no current will flow through it.

[0031] It should be noted that the component parameters in the voltage dividing circuit need to be set according to the bus voltage in combination with the reference voltage in the reference circuit, that is, the voltage value after the preset voltage is divided by the voltage dividing circuit should be equal to the reference voltage.

[0032] As Figure 1 shown, for the switching circuit 3, its fourth end is connected to the third end of the discharging circuit 4.

[0033] Specifically, Figure 1When there is current flowing through the reference circuit 2, a voltage drop gradually occurs between its fourth terminal and the ground, causing the voltage at the third terminal of the switching circuit 3 to gradually increase; when it rises to the conduction voltage drop of the switching circuit 3, the switching circuit 3 conducts, pulling the voltage at the third terminal of the discharge circuit 4 down to the ground, causing the discharge circuit 4 to cut off, and there is no discharge path between the bus and the ground, and the bus stops discharging.

[0034] Specifically, Figure 1 When there is no current flowing through the reference circuit 2, the voltage drop between its fourth terminal and the ground gradually becomes 0, causing the voltage at the third terminal of the switching circuit 3 to gradually decrease; when it decreases to below the conduction voltage drop of the switching circuit 3, the switching circuit 3 turns off, raising the voltage at the third terminal of the discharge circuit 4 to the conduction voltage drop of the discharge circuit 4, causing the discharge circuit 4 to conduct, and there is a discharge path between the bus and the ground, and the bus voltage starts to discharge to the ground through the discharge circuit 4.

[0035] The discharge circuit provided in this embodiment, by setting a preset voltage, when the bus voltage is higher than or equal to the preset voltage, the voltage at the third terminal of the voltage dividing circuit is greater than or equal to the reference voltage, causing the reference circuit to conduct. Then, the voltage at the third terminal of the switching circuit gradually increases, causing the switching circuit to conduct and the discharge circuit to cut off; when the bus voltage is lower than the preset voltage, the voltage at the third terminal of the voltage dividing circuit is less than the reference voltage, causing the reference circuit to cut off. Then, the voltage at the third terminal of the switching circuit gradually decreases, causing the switching circuit to cut off and the discharge circuit to conduct. The discharge circuit can automatically switch the on-off states of the internal components according to the magnitude of the bus voltage, timely turn on or off the discharge function, ensure that there is no discharge when the bus voltage is high, avoid unnecessary energy consumption, and at the same time can discharge in a timely manner when the bus voltage is low, improving the degree of automation and work efficiency.

[0036] In some alternative embodiments, such as Figure 2 shown, the voltage dividing circuit 1 includes: a first resistor R1, a second resistor R2, and a third resistor R3. Among them, for the first resistor R1, its first terminal is connected to the first terminal of the switching circuit 3, and its second terminal is connected to the first terminal of the second resistor R2 and the first terminal of the reference circuit 2; for the second resistor R2, its second terminal is connected to the first terminal of the third resistor R3 and the second terminal of the reference circuit 2; for the third resistor R3, its second terminal is connected to the third terminal of the reference circuit 2.

[0037] Specifically, Figure 2 in, after the power supply voltage is divided by the first resistor R1, the second resistor R2, and the third resistor R3, the second terminal of the reference circuit 2 collects the intersection voltage of the second resistor R2 and the third resistor R3; when the bus voltage is greater than or equal to the preset voltage, the intersection voltage will be greater than or equal to the reference voltage; when the bus voltage is less than the preset voltage, the intersection voltage will be less than the reference voltage.

[0038] It should be noted that the resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 need to be set according to the bus voltage in combination with the reference voltage in the reference circuit, that is, the voltage value after the preset voltage is divided by the voltage dividing circuit should be equal to the reference voltage.

[0039] In some alternative embodiments, such as Figure 2 shown, the reference circuit 2 includes: a fourth resistor R4, a fifth resistor R5, and a first voltage stabilizing circuit 21. Among them, for the fourth resistor R4, its first end is connected to the second end of the voltage dividing circuit 1, and its second end is connected to the first end of the first voltage stabilizing circuit 21; for the fifth resistor R5, its first end is connected to the second end of the first voltage stabilizing circuit 21 and the third end of the switching circuit 3, and its second end is connected to the fourth end of the voltage dividing circuit 1; for the first voltage stabilizing circuit 21, its third end is connected to the third end of the voltage dividing circuit 1.

[0040] Specifically, Figure 2 in, when the bus voltage is greater than or equal to the preset voltage, the voltage at the third end of the voltage dividing circuit 1 is greater than or equal to the reference voltage in the first voltage stabilizing circuit 21, and the first voltage stabilizing circuit 21 conducts; when the bus voltage is less than the preset voltage, the voltage at the third end of the voltage dividing circuit 1 is less than the reference voltage in the first voltage stabilizing circuit 21, and the first voltage stabilizing circuit 21 is cut off.

[0041] In some alternative embodiments, such as Figure 2 shown, the first voltage stabilizing circuit 21 includes: a controllable precision voltage stabilizing source U1, whose reference terminal is connected to the third end of the voltage dividing circuit 1, whose cathode is connected to the second end of the fourth resistor R4, and whose anode is connected to the first end of the fifth resistor R5.

[0042] Specifically, Figure 2 in, when the bus voltage is greater than or equal to the preset voltage, the voltage at the third end of the voltage dividing circuit 1 is greater than or equal to the reference terminal voltage of the controllable precision voltage stabilizing source U1, the controllable precision voltage stabilizing source U1 conducts, and there is current flowing through its interior. Thus, after a voltage drop is generated on the fifth resistor R5, the reference voltage of the controllable precision voltage stabilizing source U1 is raised to the sum of the original reference voltage value and the voltage drop on the fifth resistor R5, and finally voltage balance is achieved; when the bus voltage is less than the preset voltage, the voltage at the third end of the voltage dividing circuit 1 is less than the reference terminal voltage of the controllable precision voltage stabilizing source U1, the controllable precision voltage stabilizing source U1 is cut off, and the voltage drop on the fifth resistor R5 gradually decreases to 0.

[0043] Preferably, Figure 2 in, the controllable precision voltage stabilizing source U1 is a TL431 controllable precision voltage stabilizing source, and its reference terminal has a built-in reference voltage.

[0044] In some alternative embodiments, the switching circuit 3 includes: a sixth resistor R6, a first switching transistor Q1, and a second voltage stabilizing circuit 31. Among them, for the sixth resistor R6, its first end is connected to the first end of the voltage dividing circuit 1, and its second end is connected to the first end of the first switching transistor Q1, the first end of the second voltage stabilizing circuit 31, and the third end of the discharging circuit 4; for the first switching transistor Q1, its control end is connected to the fourth end of the reference circuit 2, and its second end is connected to the second end of the second voltage stabilizing circuit 31 and the third end of the reference circuit 2; the second voltage stabilizing circuit 31 is configured to stabilize the voltage between the first end and the second end of the first switching transistor Q1.

[0045] Specifically, Figure 2 in this case, when the bus voltage is greater than or equal to the preset voltage, the reference circuit 2 is turned on. Since there is current flowing through the fifth resistor R5, a voltage drop is generated across the fifth resistor R5. When the voltage drop across the fifth resistor R5 gradually rises to be greater than the conduction voltage drop of the first switching transistor Q1, it will be clamped by the base and emitter of the first switching transistor Q1, and at the same time, the first switching transistor Q1 is turned on.

[0046] Specifically, Figure 2 in this case, when the bus voltage is less than the preset voltage, the reference circuit 2 is turned off. Therefore, the current flowing through the fifth resistor R5 gradually decreases as it discharges to the ground, and the voltage drop across the fifth resistor R5 will gradually decrease to 0. When the voltage drop across the fifth resistor R5 gradually decreases to be less than the conduction voltage drop of the first switching transistor Q1, the first switching transistor Q1 is turned off.

[0047] Optionally, as Figure 2 shown, the second voltage stabilizing circuit 31 includes: a zener diode U2, whose cathode is connected to the first end of the first switching transistor Q1, and whose anode is connected to the second end of the first switching transistor Q1. The specific structure of the second voltage stabilizing circuit 31 is only exemplified hereby and is not limited thereto.

[0048] In some alternative embodiments, as Figure 2 shown, the discharging circuit 4 includes: a discharging branch 41, a second switching transistor Q2, and a protection branch 42. Among them, for the discharging branch 41, its first end is connected to the first end of the voltage dividing circuit 1, and its second end is connected to the first end of the second switching transistor Q2; for the second switching transistor Q2, its control end is connected to the first end of the protection branch 42 and the fourth end of the switching circuit 3, and its second end is connected to the second end of the protection branch 42 and the second end of the switching circuit 3; the protection branch 42 is configured to limit the voltage between the control end and the second end of the second switching transistor Q2.

[0049] Specifically, Figure 2When the bus voltage is greater than or equal to the preset voltage, the reference circuit 2 is turned on, causing the voltage at the third terminal of the switching circuit 3 to gradually rise to the conduction voltage drop of the switching circuit 3. Then, the switching circuit 3 is turned on, and the control terminal voltage of the second switching transistor Q2 is pulled down to ground, causing the second switching transistor Q2 to turn off. There is no discharge path between the bus and ground, and the bus voltage stops discharging.

[0050] Specifically, Figure 2 When the bus voltage is less than the preset voltage, the reference circuit 2 is turned off, causing the voltage at the third terminal of the switching circuit 3 to gradually drop below the conduction voltage drop of the switching circuit 3. Then, the switching circuit 3 is turned off, and the voltage at the control terminal of the second switching transistor Q2 gradually rises from 0V to its conduction voltage drop and then turns on. The bus voltage starts to discharge to ground through the discharge branch 41 and the second switching transistor Q2.

[0051] Specifically, as Figure 2 shown, the discharge branch 41 includes a discharge resistor RD and a fuse FU. Among them, for the discharge resistor RD, its first end is connected to the first end of the voltage dividing circuit 1, and its second end is connected to the first end of the fuse FU; for the fuse FU, its second end is connected to the first end of the second switching transistor Q2. The protection branch 42 includes a seventh resistor R7, which is connected in parallel with the control terminal and the second end of the second switching transistor Q2.

[0052] It should be noted that those skilled in the art can set the specific structures of the discharge branch and the protection branch as needed, and no limitation is made here.

[0053] This embodiment provides an inverter, as Figure 3 shown, which includes an inverter body and the discharge circuit of the above embodiment and any of its optional implementation manners. Among them, the positive bus in the inverter body is connected to the first end of the voltage dividing circuit 1, the first end of the switching circuit 3, and the first end of the discharge circuit 4; the negative bus in the inverter body is connected to the fourth end of the voltage dividing circuit 1, the third end of the reference circuit 2, the second end of the switching circuit 3, and the second end of the discharge circuit 4.

[0054] Specifically, Figure 3 In this case, the discharge circuit is used to discharge the positive and negative bus voltages of the inverter body, so that the energy stored in the BUS can be quickly released to facilitate the maintenance work of the maintenance personnel. Combining the circuit control principles in the above embodiment and any of its optional implementation manners, when the positive bus voltage BUS+ of the inverter body is greater than or equal to the preset voltage, the discharge circuit 4 is turned off, and the positive bus voltage BUS+ of the inverter body stops discharging. The energy output by the inverter body is given to the auxiliary source to avoid repeated starting of related machines; when the photovoltaic panel of the inverter is powered off in weak light, at this time, the positive bus voltage BUS+ of the inverter body is less than the preset voltage, and the discharge circuit 4 is turned on, and the positive bus voltage BUS+ of the inverter body starts to discharge through the discharge circuit 4.

[0055] Specifically, in combination with Figure 2 and Figure 4 , the discharging process of the inverter is as follows:

[0056] (1) Determine whether the BUS voltage of the inverter body exceeds the threshold.

[0057] (2) If it exceeds, control Q2 to cut off and stop discharging.

[0058] (3) If it does not exceed, control Q2 to conduct and start discharging.

[0059] For the inverter provided in this embodiment, by setting a preset voltage, when the bus voltage of the inverter is higher than or equal to the preset voltage, the voltage at the third terminal of the voltage dividing circuit is greater than or equal to the reference voltage, causing the reference circuit to conduct. Then, the voltage at the third terminal of the switching circuit gradually increases, causing the switching circuit to conduct and the discharging circuit to cut off. When the bus voltage of the inverter is lower than the preset voltage, the voltage at the third terminal of the voltage dividing circuit is less than the reference voltage, causing the reference circuit to cut off. Then, the voltage at the third terminal of the switching circuit gradually decreases, causing the switching circuit to cut off and the discharging circuit to conduct. The discharging circuit can automatically switch the on / off states of the internal components according to the magnitude of the bus voltage of the inverter, timely turn on or off the discharging function, ensure that the inverter does not discharge when the bus voltage is relatively high, avoid unnecessary energy consumption, and at the same time can timely discharge when the bus voltage of the inverter is relatively low, improving the degree of automation and work efficiency.

[0060] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A discharge circuit, characterized in that: Applied to an inverter, the discharge circuit comprises: a voltage divider circuit, a reference circuit, a switch circuit and a discharge circuit, wherein: A voltage divider circuit, wherein a first end of the voltage divider circuit receives the bus voltage of the inverter, a first end of the voltage divider circuit is further connected to a first end of the switch circuit and a first end of the discharge circuit, a second end of the voltage divider circuit is connected to a first end of the reference circuit, a third end of the voltage divider circuit is connected to a second end of the reference circuit, a fourth end of the voltage divider circuit is connected to a third end of the reference circuit, a second end of the switch circuit and a second end of the discharge circuit and then is grounded, and is used to divide the bus voltage; A reference circuit, the fourth end of which is connected to the third end of the switch circuit, and is used to switch its own on-off state based on the magnitude of the internal reference voltage and the voltage at the third end of the voltage divider circuit; a switch circuit, a fourth terminal of which is connected to the third terminal of the discharge circuit; When the bus voltage is greater than or equal to a preset voltage, the reference circuit is turned on, so that the voltage at the third terminal of the switch circuit gradually increases to the conduction voltage drop of the switch circuit, the switch circuit is turned on, the discharge circuit is turned off, and the bus stops discharging; When the bus voltage is less than a preset voltage, the reference circuit is cut off, so that the voltage at the third terminal of the switch circuit gradually drops to a value lower than the conduction voltage drop of the switch circuit. Then, the switch circuit is cut off and the discharge circuit is turned on, and the bus voltage starts to be discharged through the discharge circuit.

2. The discharge circuit according to claim 1, characterized in that: The voltage divider circuit includes: a first resistor, a second resistor and a third resistor, wherein: a first resistor, a first end of which is connected to the first end of the switch circuit, and a second end of which is connected to the first end of the second resistor and the first end of the reference circuit; A second resistor, a second end of which is connected to the first end of the third resistor and the second end of the reference circuit; A third resistor has a second end connected to the third end of the reference circuit.

3. The discharge circuit according to claim 1, characterized in that: The reference circuit includes: a fourth resistor, a fifth resistor and a first voltage stabilizing circuit, wherein: a fourth resistor, a first end of which is connected to the second end of the voltage divider circuit, and a second end of which is connected to the first end of the first voltage stabilizing circuit; a fifth resistor, a first end of which is connected to the second end of the first voltage stabilizing circuit and the third end of the switch circuit, and a second end of which is connected to the fourth end of the voltage dividing circuit; A first voltage stabilizing circuit, a third end of which is connected to a third end of the voltage dividing circuit; When the bus voltage is greater than or equal to a preset voltage, the voltage at the third terminal of the voltage divider circuit is greater than or equal to a reference voltage in the first voltage stabilizing circuit, and the first voltage stabilizing circuit is turned on; When the bus voltage is less than a preset voltage, the voltage at the third terminal of the voltage divider circuit is less than a reference voltage in the first voltage stabilizing circuit, and the first voltage stabilizing circuit is cut off.

4. The discharge circuit according to claim 3, characterized in that: The first voltage stabilizing circuit comprises: a controllable precision voltage-stabilizing source, whose reference end is connected to the third end of the voltage-dividing circuit, whose cathode is connected to the second end of the fourth resistor, and whose anode is connected to the first end of the fifth resistor; When the bus voltage is greater than or equal to a preset voltage, the voltage at the third terminal of the voltage divider circuit is greater than or equal to the reference terminal voltage of the controllable precision voltage stabilizing source, and the controllable precision voltage stabilizing source is turned on; When the bus voltage is less than a preset voltage, the voltage at the third terminal of the voltage divider circuit is less than the reference terminal voltage of the controllable precision voltage stabilizing source, and the controllable precision voltage stabilizing source is cut off.

5. The discharge circuit according to claim 1, characterized in that: The switch circuit includes: a sixth resistor, a first switch tube and a second voltage stabilizing circuit, wherein: a sixth resistor, a first end of which is connected to the first end of the voltage divider circuit, and a second end of which is connected to the first end of the first switch tube, the first end of the second voltage stabilizing circuit, and the third end of the discharge circuit; a first switch tube, a control end of which is connected to the fourth end of the reference circuit, and a second end of which is connected to the second end of the second voltage stabilizing circuit and the third end of the reference circuit; A second voltage stabilizing circuit, which is used to stabilize the voltage between the first end and the second end of the first switch tube; When the bus voltage is greater than or equal to a preset voltage, the reference circuit is turned on, so that after the voltage at the control end of the first switch tube gradually increases to the conduction voltage drop of the first switch tube, the first switch tube is turned on and the discharge circuit is turned off; When the bus voltage is less than a preset voltage, the reference circuit is turned off, so that the control terminal voltage of the first switch tube gradually decreases to a level lower than the conduction voltage drop of the first switch tube, and then the first switch tube is turned off and the discharge circuit is turned on.

6. The discharge circuit according to claim 5, characterized in that: The second voltage stabilizing circuit comprises: A voltage regulator tube, a cathode of which is connected to the first end of the first switch tube, and an anode of which is connected to the second end of the first switch tube.

7. The discharge circuit according to claim 1, characterized in that: The discharge circuit includes: a discharge branch, a second switch tube and a protection branch, wherein: a discharge branch, a first end of which is connected to the first end of the voltage divider circuit, and a second end of which is connected to the first end of the second switch tube; a second switch tube, a control end of which is connected to the first end of the protection branch and the fourth end of the switch circuit, and a second end of which is connected to the second end of the protection branch and the second end of the switch circuit; A protection branch, which is used to limit the voltage between the control terminal and the second terminal of the second switch tube; When the bus voltage is greater than or equal to the preset voltage, the reference circuit is turned on, so that the voltage at the third terminal of the switch circuit gradually increases to the conduction voltage drop of the switch circuit, the switch circuit is turned on, the second switch tube is turned off, and the bus stops discharging; When the bus voltage is less than a preset voltage, the reference circuit is cut off, so that the voltage at the third terminal of the switch circuit gradually drops to a value lower than the conduction voltage drop of the switch circuit, and then the switch circuit is cut off, the second switch tube is turned on, and the bus voltage starts to be discharged through the discharge branch and the second switch tube.

8. The discharge circuit according to claim 7, characterized in that: The discharge branch includes: a discharge resistor and a fuse, wherein: a bleeder resistor, a first end of which is connected to the first end of the voltage divider circuit, and a second end of which is connected to the first end of the fuse; A fuse, a second end of which is connected to the first end of the second switch tube.

9. The discharge circuit according to claim 7, characterized in that: The protection branch includes: A seventh resistor is connected in parallel with the control end and the second end of the second switch tube.

10. An inverter, characterized in that: The invention comprises an inverter body and a discharge circuit as claimed in any one of claims 1 to 9, wherein: The positive busbar in the inverter body is connected to the first end of the voltage divider circuit, the first end of the switch circuit and the first end of the discharge circuit; The negative bus in the inverter body is connected to the fourth end of the voltage divider circuit, the third end of the reference circuit, the second end of the switch circuit and the second end of the discharge circuit; When the positive bus voltage of the inverter body is greater than or equal to a preset voltage, the discharge circuit is cut off, and the positive bus voltage of the inverter body stops discharging; When the positive bus voltage of the inverter body is less than a preset voltage, the discharge circuit is turned on, and the positive bus voltage of the inverter body starts to be discharged through the discharge circuit.

Images