Leakage circuit and inverter
By incorporating voltage divider circuits and switching circuits into the inverter, the problem of energy not being able to be discharged when the inverter is not in operation is solved, thereby improving safety and protecting the machine.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI PYLON TECH CO LTD
- Filing Date
- 2025-05-19
- Publication Date
- 2026-05-01
AI Technical Summary
When the inverter is not working, the electrical energy on the bus cannot be effectively discharged, leading to safety hazards and machine damage.
By setting positive and negative connection terminals, the positive and negative transmission lines are connected respectively, and a voltage divider circuit and a switch circuit are set between them. The voltage divider circuit provides the voltage to start the switch circuit, so that electrical energy is discharged through the switch circuit.
It enables safe discharge of electrical energy when the inverter is not working, improving safety and preventing damage to the machine due to short circuits.
Smart Images
Figure CN224191833U_ABST
Abstract
Description
A discharge circuit and an inverter Technical Field
[0001] This application relates to the field of inverter technology, and more particularly to a discharge circuit and an inverter. Background Technology
[0002] In existing technologies, inverters are used in grid-connected and off-grid scenarios. When the inverter is not operating, there is no power transmission. Because capacitors are installed on the high-voltage bus of the inverter's DC side, if there are many capacitors connected in parallel, the capacitance values of multiple capacitors are large. When the inverter is not operating, the energy in the capacitors has nowhere to be released, resulting in a continuous presence of energy on the bus. Furthermore, when the voltage value of the inverter's high-voltage bus falls below the preset lower limit of the auxiliary power supply's operating voltage, the auxiliary power supply of the inverter stops working, and the energy on the bus cannot be released. If maintenance personnel come into contact with the bus, it will cause safety issues, or other reasons may cause arcing between the positive and negative terminals of the bus, which will damage the machine. Summary of the Invention
[0003] In view of this, the purpose of this application is to provide a discharge circuit and an inverter that can be used to connect positive and negative transmission lines that need to discharge energy by setting a positive connection terminal and a negative connection terminal respectively. A voltage divider circuit is set between the positive connection terminal and the negative connection terminal, and the voltage divider circuit is also connected to a ground terminal. A switching circuit is connected to the positive connection terminal and the voltage divider terminal of the voltage divider circuit so that the voltage divider circuit provides the voltage to start the switching circuit, so that the electrical energy that needs to be discharged between the positive and negative transmission lines can be discharged through the switching circuit. This solves the technical problem that the electrical energy between the positive and negative transmission lines cannot be discharged, and achieves the technical effect of improving safety and avoiding damage to the machine due to short circuit.
[0004] In a first aspect, embodiments of this application provide a bleeder circuit, the bleeder circuit comprising: a positive connection terminal for connecting to a positive transmission line; a negative connection terminal for connecting to a negative transmission line; a voltage divider circuit, wherein a first connection terminal of the voltage divider circuit is connected to the positive connection terminal, and a second connection terminal of the voltage divider circuit is connected to the negative connection terminal and a ground terminal; and a switch circuit, wherein a first connection terminal of the switch circuit is connected to the positive connection terminal, a control terminal of the switch circuit is connected to a preset voltage divider terminal of the voltage divider circuit, and a second connection terminal of the switch circuit is connected to a target voltage divider terminal of the voltage divider circuit.
[0005] Optionally, the switch sub-circuit includes a first control switch and a first resistor, wherein a first connection terminal of the first control switch serves as a first connection terminal of the switch sub-circuit, a second connection terminal of the first control switch is connected to one end of the first resistor, the other end of the first resistor serves as a second connection terminal of the switch sub-circuit, and a control terminal of the first control switch serves as a control terminal of the switch sub-circuit.
[0006] Optionally, the voltage divider circuit includes a first voltage divider unit and a second voltage divider unit, wherein the first connection terminal of the first voltage divider unit serves as the first connection terminal of the voltage divider circuit, the second connection terminal of the first voltage divider unit serves as the second connection terminal of the voltage divider circuit, the first connection terminal of the second voltage divider unit is connected to the first voltage divider terminal, the second connection terminal of the second voltage divider unit is connected to the second connection terminal of the first voltage divider unit, the control terminal of the second voltage divider unit is connected to the second voltage divider terminal of the first voltage divider unit, the third voltage divider terminal of the first voltage divider unit serves as the preset voltage divider terminal of the voltage divider circuit, and the fourth voltage divider terminal of the second voltage divider unit serves as the target voltage divider terminal of the voltage divider circuit.
[0007] Optionally, the first voltage divider unit includes a second resistor, a third resistor, a first diode, and a second diode. One end of the second resistor serves as the first connection terminal of the first voltage divider unit, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the first diode, the other end of the first diode is connected to one end of the second diode, the other end of the second diode serves as the second connection terminal of the first voltage divider unit, the connection between the second resistor and the third resistor serves as the first voltage divider terminal, the connection between the third resistor and the first diode serves as the second voltage divider terminal, and the connection between the first diode and the second diode serves as the third voltage divider terminal.
[0008] Optionally, the second voltage divider unit includes a second control switch, a fourth resistor, and a third diode, wherein the first connection terminal of the second control switch serves as the first connection terminal of the second voltage divider unit, the second connection terminal of the second control switch is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the third diode, the other end of the third diode serves as the second connection terminal of the second voltage divider unit, the control terminal of the second control switch serves as the control terminal of the second voltage divider unit, and the connection between the fourth resistor and the third diode serves as the fourth voltage divider terminal.
[0009] Optionally, the first control switch is a semiconductor field-effect transistor.
[0010] Optionally, the second control switch is a bipolar transistor.
[0011] Optionally, the diode is a Zener diode.
[0012] Secondly, embodiments of this application also provide an inverter, the inverter comprising: a DC bus disposed on the DC side of the inverter, the inverter bus including a positive bus and a negative bus; at least one bus capacitor disposed between the positive bus and the negative bus; an inverter circuit; and a discharge circuit as described in the first aspect or any possible embodiment of the first aspect; wherein the discharge circuit is located between the bus capacitor and the inverter circuit, the positive bus is the positive transmission line, and the negative bus is the negative transmission line.
[0013] Optionally, the inverter further includes an auxiliary power supply disposed between the positive bus and the negative bus.
[0014] This application provides a bleeder circuit and an inverter. The bleeder circuit includes: a positive connection terminal for connecting to a positive transmission line; a negative connection terminal for connecting to a negative transmission line; a voltage divider circuit, wherein a first connection terminal of the voltage divider circuit is connected to the positive connection terminal, and a second connection terminal of the voltage divider circuit is connected to the negative connection terminal and a ground terminal; and a switching circuit, wherein a first connection terminal of the switching circuit is connected to the positive connection terminal, a control terminal of the switching circuit is connected to a preset voltage divider terminal of the voltage divider circuit, and a second connection terminal of the switching circuit is connected to a target voltage divider terminal of the voltage divider circuit. By setting positive and negative connection terminals, the device can be used to connect positive and negative transmission lines that need to discharge energy, respectively. A voltage divider circuit is set between the positive and negative connection terminals, and a switch circuit is connected to the voltage divider terminal of the positive connection terminal and the voltage divider circuit. The voltage divider circuit provides the voltage to start the switch circuit, so that the electrical energy that needs to be discharged between the positive and negative transmission lines can be discharged through the switch circuit. This solves the technical problem that electrical energy between the positive and negative transmission lines cannot be discharged, and achieves the technical effect of improving safety and avoiding damage to the machine due to short circuit.
[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 shows a schematic diagram of a discharge circuit provided in an embodiment of this application.
[0018] Figure 2 shows a circuit diagram of a discharge circuit provided in an embodiment of this application.
[0019] Figure 3 shows a schematic diagram of the structure of an inverter provided in an embodiment of this application. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.
[0021] In existing technologies, in hybrid grid-connected inverters, after the inverter stops, the transmission of electrical energy on the inverter ceases. At this time, the auxiliary power supply connected to the inverter bus will continue to operate until the bus voltage is lower than the preset lower limit of the pulse width modulation (PWM) chip of its auxiliary power supply. The discharge current is microamps (μA level), which makes it difficult to release the electrical energy on the bus and the electrical energy in the capacitor.
[0022] To address the aforementioned problems, this application provides a discharge circuit and inverter. It can connect positive and negative connection terminals to the positive and negative transmission lines requiring energy discharge, respectively. A voltage divider circuit is provided between the positive and negative connection terminals, and a switching sub-circuit is connected to the voltage divider terminal of the voltage divider circuit. The voltage divider circuit provides the voltage to activate the switching sub-circuit, allowing the energy to be discharged between the positive and negative transmission lines to be discharged through the switching sub-circuit. This solves the technical problem of the inability to discharge energy between the positive and negative transmission lines, achieving the technical effects of improved safety and preventing machine damage due to short circuits. Specifically:
[0023] Please refer to Figure 1, which is a schematic diagram of a discharge circuit provided in an embodiment of this application. As shown in Figure 1, the discharge circuit provided in this embodiment includes: a positive connection terminal Y1 for connecting to a positive transmission line; a negative connection terminal Y2 for connecting to a negative transmission line; a voltage divider circuit 101, wherein a first connection terminal of the voltage divider circuit is connected to the positive connection terminal, and a second connection terminal of the voltage divider circuit is connected to the negative connection terminal and the ground terminal GND; and a switch circuit 102, wherein a first connection terminal of the switch circuit is connected to the positive connection terminal, a control terminal of the switch circuit is connected to a preset voltage divider terminal of the voltage divider circuit, and a second connection terminal of the switch circuit is connected to a target voltage divider terminal of the voltage divider circuit.
[0024] The discharge circuit provided in this application can be applied to any scenario requiring energy discharge, i.e., where there is electrical energy to be discharged between the positive and negative transmission lines. When the circuit containing the positive and negative transmission lines is experiencing normal electrical energy flow, the discharge circuit does not need to operate, and the voltage difference between the positive and negative transmission lines is used as the first voltage difference. When the circuit containing the positive and negative transmission lines stops flowing with electrical energy, the discharge circuit needs to operate to discharge the electrical energy between the positive and negative transmission lines, and the voltage difference between the positive and negative transmission lines is used as the second voltage difference. Furthermore, the first voltage difference is greater than the second voltage difference; that is, when the voltage difference between the positive and negative transmission lines falls below a certain level, it is considered that the circuit containing the positive and negative transmission lines has stopped flowing with electrical energy, and energy discharge is required.
[0025] Furthermore, by placing the voltage divider circuit between the positive and negative connection terminals, the control terminal of the switch circuit is connected to the preset voltage divider terminal of the voltage divider circuit, and the second connection terminal of the switch circuit is connected to the target voltage divider terminal of the voltage divider circuit. This allows the preset and target voltage divider terminals to provide the switch circuit with a voltage value obtained by dividing the voltage difference between the positive and negative connection terminals. When the voltage divider value is greater than the preset operating voltage, the switch circuit is in the off state; when the voltage divider value is less than or equal to the preset operating voltage, the switch circuit is in the on state. The preset operating voltage refers to the trigger voltage that changes the switch circuit from the off state to the on state.
[0026] Furthermore, when the voltage difference between the positive and negative terminals, after being divided by the voltage divider circuit, results in a voltage drop greater than the preset operating voltage, the circuit at both terminals is considered to be in a normal power transmission state. When the voltage difference between the positive and negative terminals, after being divided by the voltage divider circuit, results in a voltage drop less than or equal to the preset operating voltage, the circuit at both terminals is considered not to be in a power transmission state, and the power on both terminals needs to be discharged. The switching sub-circuit then changes from an open state to a closed state. Thus, the first terminal of the switching sub-circuit transfers power from the positive terminal to the second terminal, which then discharges the power to the ground terminal via the voltage divider circuit, thereby discharging the power between the positive and negative terminals.
[0027] Please refer to Figure 2, which is a circuit diagram of a discharge circuit provided in an embodiment of this application. As shown in Figure 2, the switch sub-circuit 102 in the discharge circuit includes a first control switch Q1 and a first resistor R1. The first connection terminal of the first control switch serves as the first connection terminal of the switch sub-circuit, the second connection terminal V1 of the first control switch is connected to one end of the first resistor, the other end of the first resistor serves as the second connection terminal of the switch sub-circuit, and the control terminal of the first control switch serves as the control terminal of the switch sub-circuit.
[0028] In other words, when the voltage between the control terminal of the first control switch and the other end of the first resistor reaches the preset operating voltage of the first control switch, the on / off state of the first control switch changes from the off state to the on state. Thus, the electrical energy on the positive connection terminal is transferred to the target voltage divider terminal of the voltage divider circuit through the first control switch and the first resistor. The first resistor serves as a bleeder resistor, and the first control switch is a semiconductor field-effect transistor, specifically a P-type field-effect transistor (PMOS).
[0029] As shown in Figure 2, the voltage divider circuit 101 includes a first voltage divider unit 1011 and a second voltage divider unit 1012. The first connection terminal of the first voltage divider unit serves as the first connection terminal of the voltage divider circuit, and the second connection terminal of the first voltage divider unit serves as the second connection terminal of the voltage divider circuit. The first connection terminal of the second voltage divider unit is connected to the first voltage divider terminal J1 of the first voltage divider unit, and the second connection terminal of the second voltage divider unit is connected to the second connection terminal of the first voltage divider unit. The control terminal of the second voltage divider unit is connected to the second voltage divider terminal J2 of the first voltage divider unit. The third voltage divider terminal J3 of the first voltage divider unit serves as the preset voltage divider terminal of the voltage divider circuit, and the fourth voltage divider terminal of the second voltage divider unit serves as the target voltage divider terminal of the voltage divider circuit.
[0030] In other words, there are electronic components between the first voltage divider terminal and the second voltage divider terminal, and between the second voltage divider terminal and the third voltage divider terminal. That is, the first voltage divider terminal, the second voltage divider terminal, and the third voltage divider terminal correspond to different voltage values.
[0031] Specifically, the first voltage divider unit 1011 includes a second resistor R2, a third resistor R3, a first diode D1, and a second diode D2. One end of the second resistor serves as the first connection terminal of the first voltage divider unit, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the first diode, the other end of the first diode is connected to one end of the second diode, the other end of the second diode serves as the second connection terminal of the first voltage divider unit, the connection between the second resistor and the third resistor serves as the first voltage divider terminal, the connection between the third resistor and the first diode serves as the second voltage divider terminal, and the connection between the first diode and the second diode serves as the third voltage divider terminal.
[0032] In other words, electrical energy at the positive connection terminal flows to the negative connection terminal through the second resistor R2, the third resistor R3, the first diode D1, and the second diode D2. When the voltage at the positive connection terminal is high, the voltage across the second diode is also high; conversely, when the voltage at the positive connection terminal decreases, the voltage across the second diode also decreases. The first voltage divider terminal provides electrical energy to the second voltage divider unit, the second voltage divider terminal controls the on / off state of the second voltage divider unit, and the third voltage divider terminal is connected to the control terminal of the first control switch, meaning the third voltage divider terminal provides voltage to the gate of the first control switch.
[0033] Specifically, the second voltage divider unit 1012 includes a second control switch Q2, a fourth resistor R4, and a third diode D3. The first connection terminal of the second control switch serves as the first connection terminal of the second voltage divider unit, the second connection terminal of the second control switch is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the third diode, the other end of the third diode serves as the second connection terminal of the second voltage divider unit, the control terminal of the second control switch serves as the control terminal of the second voltage divider unit, and the connection between the fourth resistor and the third diode serves as the fourth voltage divider terminal.
[0034] In other words, when the voltage at the positive connection terminal is high, the voltage at the second voltage divider terminal is also high, the second control switch is not turned on, and the second voltage divider unit is in the off state. When the voltage at the positive connection terminal decreases, the voltage at the second voltage divider terminal also decreases. If the voltage at the second voltage divider terminal decreases to the turn-on voltage of the second control switch, the channel state of the second control switch switches from the off state to the on state, that is, the channel state of the second voltage divider unit switches from the off state to the on state. Furthermore, when the channel state of the second control switch switches from the off state to the on state, the electrical energy at the first voltage divider terminal is transferred to the second control switch, the fourth resistor, and the third diode. The voltage at the other end of the first resistor can be easily determined by setting the fourth resistor and the third diode.
[0035] Furthermore, when the voltage value at the third voltage terminal minus the voltage value at the connection between the fourth resistor and the third diode meets the gate-source voltage value required for the first control switch to turn on, the first control switch turns on. Thus, the electrical energy at the positive connection terminal flows from the first control switch, the first resistor, and the third diode to the ground terminal, thereby realizing the discharge of electrical energy.
[0036] In other words, the second and third resistors serve as voltage divider resistors, while the fourth resistor is used to increase safety. For example, the second control switch is a bipolar transistor, specifically a PNP bipolar transistor. The diode used in this application is a Zener diode for voltage regulation. To ensure the inverter operates normally during startup and to prevent current from flowing uniformly through the voltage divider circuit, the resistance values of the second resistor R2 and the third resistor R3 are generally set very high, resulting in a small discharge current flowing through the first voltage divider unit. Furthermore, since the voltage regulation values of the first diode D1 and the second diode D2 are typically in the tens of volts range, the voltage divider circuit alone would still result in a large amount of energy remaining in the bus capacitor, necessitating a switching sub-circuit to discharge this energy. Therefore, the switching sub-circuit discharges the bus voltage to the third diode D3 to meet safety requirements.
[0037] In other words, depending on the environment in which the bleeder circuit is used, the voltage value when the auxiliary power supply on the inverter stops working, after being divided by the voltage divider circuit, should result in a voltage difference between the control terminal of the first control switch and the other end of the first resistor that satisfies the gate-source voltage required for the first control switch to be in the on state. Therefore, appropriate selections should be made for the various electronic components in the voltage divider circuit, including choosing suitable voltage regulation values for the first diode D1, the second diode D2, and the third diode D3, as well as suitable resistance values for the second resistor R2, the third resistor R3, and the fourth resistor R4.
[0038] Based on the same application concept, this application also provides an inverter corresponding to the discharge circuit provided in the above embodiments. Since the principle of the inverter in this application to solve the problem is similar to that of the discharge circuit in the above embodiments of this application, the implementation of the inverter can refer to the implementation of the above embodiments, and the repeated parts will not be described again.
[0039] Please refer to Figure 3, which is a schematic diagram of an inverter provided in an embodiment of this application. As shown in Figure 3, the inverter provided in this embodiment includes: a DC bus, disposed on the DC side of the inverter, the inverter bus including a positive bus BUS1 and a negative bus BUS2; at least one bus capacitor C1, the bus capacitor being disposed between the positive bus and the negative bus; an inverter circuit 20 for converting the DC power on the DC bus into AC power; and a discharge circuit 10 provided in the above embodiment; wherein the discharge circuit is located between the bus capacitor and the inverter circuit, the positive bus is the positive transmission line, and the negative bus is the negative transmission line.
[0040] In this circuit, when multiple bus capacitors are involved, they are connected in parallel between the positive and negative bus. The inverter circuit includes multiple switching transistors, which are controlled to achieve AC-DC conversion or control voltage rise and fall, such as converting DC to AC and vice versa. As shown in Figure 3, one side of the inverter circuit is connected to a bleeder circuit, and the other side is led out as the AC side of the inverter. The AC side of the inverter leads out to the AC bus (BUS3 and BUS4).
[0041] Specifically, the inverter circuit has a DC side on one side and an AC side on the other. The bus capacitor and bleeder circuit are both located on the DC side of the inverter circuit and connected to the DC bus. For example, the DC side of the inverter can be connected to input power sources requiring voltage conversion, such as photovoltaic modules or lithium-ion batteries. The AC side of the inverter is used to connect to mains power or other devices requiring AC input. The inverter circuit converts the electrical energy from the input power source and transmits it to the output device.
[0042] As shown in Figure 3, the inverter also includes an auxiliary power supply 30, which is located between the positive bus and the negative bus, and between the discharge circuit 10 and the inverter circuit 20. For example, the auxiliary power supply is configured to stop operating when the voltage value of the inverter bus is less than a preset lower limit of its operating voltage. That is, when the auxiliary power supply stops controlling the operation of the switching transistors on the inverter circuit, the inverter circuit stops transmitting power, causing the inverter to stop transmitting power, thus preventing the discharge of energy from the inverter bus and its capacitors.
[0043] Furthermore, when the discharge circuit of this application is set between the positive bus and the negative bus of the inverter, the voltage value at the positive connection terminal is divided by the voltage divider circuit. When the voltage value after voltage division is greater than the preset operating voltage of the switching sub-circuit, the switching sub-circuit is in the open state. When the voltage value after voltage division is less than or equal to the preset operating voltage, it is considered that the auxiliary power supply of the inverter stops working and cannot discharge energy. The channel state of the switching sub-circuit is in the conducting state, which does not affect the normal operation of the inverter. It can also quickly discharge the energy on the bus and capacitor when the inverter is turned off.
[0044] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0045] It should also be noted that, unless otherwise explicitly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0046] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A discharge circuit, characterized in that, The discharge circuit includes: a positive connection terminal for connecting to a positive transmission line; a negative connection terminal for connecting to a negative transmission line; a voltage divider circuit, wherein a first connection terminal of the voltage divider circuit is connected to the positive connection terminal, and a second connection terminal of the voltage divider circuit is connected to the negative connection terminal and a ground terminal; and a switch circuit, wherein a first connection terminal of the switch circuit is connected to the positive connection terminal, a control terminal of the switch circuit is connected to a preset voltage divider terminal of the voltage divider circuit, and a second connection terminal of the switch circuit is connected to a target voltage divider terminal of the voltage divider circuit.
2. The discharge circuit according to claim 1, characterized in that, The switching sub-circuit includes a first control switch and a first resistor, wherein a first connection terminal of the first control switch serves as a first connection terminal of the switching sub-circuit, a second connection terminal of the first control switch is connected to one end of the first resistor, the other end of the first resistor serves as a second connection terminal of the switching sub-circuit, and a control terminal of the first control switch serves as a control terminal of the switching sub-circuit.
3. The discharge circuit according to claim 1, characterized in that, The voltage divider circuit includes a first voltage divider unit and a second voltage divider unit. The first connection terminal of the first voltage divider unit serves as the first connection terminal of the voltage divider circuit, and the second connection terminal of the first voltage divider unit serves as the second connection terminal of the voltage divider circuit. The first connection terminal of the second voltage divider unit is connected to the first voltage divider terminal, and the second connection terminal of the second voltage divider unit is connected to the second connection terminal of the first voltage divider unit. The control terminal of the second voltage divider unit is connected to the second voltage divider terminal of the first voltage divider unit. The third voltage divider terminal of the first voltage divider unit serves as the preset voltage divider terminal of the voltage divider circuit, and the fourth voltage divider terminal of the second voltage divider unit serves as the target voltage divider terminal of the voltage divider circuit.
4. The discharge circuit according to claim 3, characterized in that, The first voltage divider unit includes a second resistor, a third resistor, a first diode, and a second diode. One end of the second resistor serves as the first connection terminal of the first voltage divider unit, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the first diode, the other end of the first diode is connected to one end of the second diode, the other end of the second diode serves as the second connection terminal of the first voltage divider unit, the connection between the second resistor and the third resistor serves as the first voltage divider terminal, the connection between the third resistor and the first diode serves as the second voltage divider terminal, and the connection between the first diode and the second diode serves as the third voltage divider terminal.
5. The discharge circuit according to claim 3, characterized in that, The second voltage divider unit includes a second control switch, a fourth resistor, and a third diode. The first connection terminal of the second control switch serves as the first connection terminal of the second voltage divider unit. The second connection terminal of the second control switch is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to one end of the third diode. The other end of the third diode serves as the second connection terminal of the second voltage divider unit. The control terminal of the second control switch serves as the control terminal of the second voltage divider unit. The connection between the fourth resistor and the third diode serves as the fourth voltage divider terminal.
6. The discharge circuit according to claim 2, characterized in that, The first control switch is a semiconductor field-effect transistor.
7. The discharge circuit according to claim 5, characterized in that, The second control switch is a bipolar transistor.
8. The discharge circuit according to claim 4 or 5, characterized in that, The diode is a Zener diode.
9. An inverter, characterized in that, The inverter includes: a DC bus disposed on the DC side of the inverter, the DC bus including a positive bus and a negative bus; at least one bus capacitor disposed between the positive bus and the negative bus; an inverter circuit; and a discharge circuit as described in any one of claims 1 to 8; wherein the discharge circuit is located between the bus capacitor and the inverter circuit, the positive bus is the positive transmission line, and the negative bus is the negative transmission line.
10. The inverter according to claim 9, characterized in that, The inverter also includes an auxiliary power supply, which is located between the positive bus and the negative bus.