Inverter protection circuit and inverter
By introducing a blocking module between the boost module and the inverter module, the loop of grid voltage flowing into the inverter module is blocked, which solves the problem of power device damage in photovoltaic grid-connected inverters, and realizes stable operation of the inverter and reduces the probability of failure.
Patent Information
- Application Number
- CN202520237553.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-14
- Publication Date
- 2025-12-16
- Estimated Expiration
- 2035-02-14
AI Technical Summary
When the insulation impedance of the PV terminal or wiring to ground in existing photovoltaic grid-connected inverters is abnormal, a circuit is formed between the power device and the grid side, which leads to a high risk of damage to the power device.
A blocking module is introduced between the boost module and the inverter module to block the flow of grid voltage through the ground terminal and the boost module into the inverter module, preventing the formation of short-circuit current. The blocking function is achieved by using devices such as diodes, transistors, field-effect transistors or relays.
It effectively prevents inverter module damage, reduces the probability of photovoltaic grid-connected inverter failure, and ensures stable inverter operation.
Smart Images
Figure CN223680741U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to inverter technical field, concretely relates to inverter protection circuit and inverter. BACKGROUND
[0002] With the development of science and technology, inverter gets extensive application, and the inverter is a converter for converting direct-current power into fixed-frequency fixed-voltage or frequency-regulated voltage alternating current.
[0003] When the insulation impedance of the PV terminal or the wiring of the existing photovoltaic grid-connected inverter is abnormal, for example, when the PV terminal or the wiring is short-circuited to the ground, if the grid voltage is running in the negative half cycle, a loop will be formed between the power panel inverter side lower tube power device and the grid side at this time, and the short-circuit current formed at this time has a high probability of damaging the power device. UTILITY MODEL CONTENTS
[0004] Therefore, the utility model provides an inverter protection circuit and an inverter to solve the problem that the power device of the power panel inverter side and the grid side form a loop to cause the power device to fail.
[0005] In a first aspect, the utility model provides an inverter protection circuit, which is connected with a boost module and an inverter module respectively, the inverter module is connected with the boost module, wherein the boost module is connected with a direct-current input end for receiving a direct-current photovoltaic input voltage, and the direct-current photovoltaic input voltage is boosted and outputted, and the inverter module is used for converting the boosted direct-current photovoltaic input voltage into an alternating voltage and outputting the alternating voltage to a grid end.
[0006] The inverter protection circuit comprises:
[0007] A blocking module is connected between the boost module and the inverter module, and is used for blocking the loop in which the voltage of the grid end flows into the inverter module through the ground end and the boost module when the insulation impedance of the direct-current photovoltaic input end to the ground is abnormal.
[0008] The inverter protection circuit provided by the utility model boosts and outputs the direct-current photovoltaic input voltage through the boost module, and the inverter module converts the boosted direct-current photovoltaic input voltage into an alternating voltage and outputs the alternating voltage to the grid end. At the same time, the blocking module blocks the voltage of the grid end from flowing into the inverter module through the ground end and the boost module, so that when the insulation impedance of the input end or the wiring of the boost module to the ground is abnormal, for example, when the input end or the wiring of the boost module is short-circuited to the ground end, and the grid voltage is running in the negative half cycle of the inverter module, the loop is prevented from being formed between the grid end, the boost module and the inverter module to cause the inverter module to be damaged, and thus the inverter is stably operated, and the probability of failure of the photovoltaic grid-connected inverter is reduced.
[0009] In an alternative embodiment, the boost module comprises a boost unit, the first end of the blocking module is connected to the boost unit, and the second end of the blocking module is connected to the inverter module.
[0010] Alternatively, the boost module comprises a plurality of boost units, the first end of the blocking module is connected to the plurality of boost units respectively, and the second end of the blocking module is connected to the inverter module.
[0011] In an alternative embodiment, the blocking module is connected in the negative loop between the boost module and the inverter module.
[0012] In an alternative embodiment, the boost unit comprises a boost output capacitor, and the inverter module comprises a bus input capacitor of an inverter lower half-bridge arm.
[0013] The first end of the blocking module is connected to the negative end of the boost output capacitor, and the second end of the blocking module is connected to the negative end of the bus output capacitor of the inverter lower half-bridge arm.
[0014] In an alternative embodiment, the blocking module comprises:
[0015] a first diode, the cathode of the first diode is connected to the negative end of the boost output capacitor, and the anode of the first diode is connected to the negative end of the bus output capacitor of the inverter lower half-bridge arm.
[0016] In an alternative embodiment, the blocking module comprises:
[0017] a blocking module composed of a plurality of first diodes in parallel and / or in series, the first end of the blocking module is connected to the negative end of the boost output capacitor, and the second end of the blocking module is connected to the negative end of the bus output capacitor.
[0018] In an alternative embodiment, the blocking module comprises:
[0019] a transistor, the first end of the transistor is connected to the negative end of the boost output capacitor, and the second end of the transistor is connected to the negative end of the bus output capacitor.
[0020] In an alternative embodiment, the blocking module comprises:
[0021] a field effect transistor, the first end of the field effect transistor is connected to the negative end of the boost output capacitor, and the second end of the field effect transistor is connected to the negative end of the bus output capacitor.
[0022] In an alternative embodiment, the blocking module comprises:
[0023] A relay, switch ends of the relay are connected with a negative pole end of the boost output capacitor and a negative pole end of the bus output capacitor respectively, and the relay is used for disconnecting the connection between the negative pole end of the boost output capacitor and the negative pole end of the bus output capacitor after receiving a disconnecting signal.
[0024] A control unit, the control unit is connected with a control end of the relay, and is used for outputting a disconnecting signal when a direct current photovoltaic input negative pole voltage end is short-circuited with a ground end.
[0025] In a second aspect, the utility model provides an inverter, including the inverter protection circuit as described above. BRIEF DESCRIPTION OF DRAWINGS
[0026] In order to more clearly illustrate the specific embodiment of the utility model or the technical scheme in prior art, the following will briefly introduce the drawing needed to be used in the specific embodiment or prior art description, and obviously, the drawing in the following description is some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creative labor.
[0027] Figure 1 It is a structure diagram of an inverter protection circuit according to the utility model embodiment;
[0028] Figure 2 It is a power grid voltage schematic diagram in an inverter protection circuit according to the utility model embodiment;
[0029] Figure 3 It is another structure diagram of an inverter protection circuit according to the utility model embodiment;
[0030] Figure 4 It is still another structure diagram of an inverter protection circuit according to the utility model embodiment;
[0031] Figure 5 It is a detailed structure diagram of an inverter protection circuit according to the utility model embodiment;
[0032] Figure 6 It is a detailed structure diagram of another inverter protection circuit according to the utility model embodiment;
[0033] Figure 7 It is an application schematic diagram of an inverter protection circuit according to the utility model embodiment. DETAILED DESCRIPTION
[0034] The technical solutions of the present application will be described clearly and completely in connection with the drawings. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.
[0035] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0036] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements, or it can be wireless connection, or it can be wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0037] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.
[0038] With the development of science and technology, the inverter is widely used. The inverter is a converter that converts direct current power into fixed frequency and fixed voltage or frequency and voltage adjustable alternating current.
[0039] When the existing photovoltaic grid-connected inverter PV terminal or wiring has abnormal ground insulation impedance, for example, when the PV terminal or wiring is short-circuited to ground, if the grid voltage is running in the negative half cycle, at this time, the lower tube power device of the power board inverter side and the grid side will form a loop, at this time, the short-circuit current formed will have a high probability of damaging the power device.
[0040] To this end, the present embodiment provides an inverter protection circuit, as shown in Figure 1 The inverter protection circuit comprises:
[0041] The inverter protection circuit is connected with the boost module A1 and the inverter module A2 respectively, the inverter module A2 is connected with the boost module A1, wherein the boost module A1 is connected with the DC input end for receiving the DC photovoltaic input voltage, and the DC photovoltaic input voltage is boosted and outputted, and the inverter module A2 is used for converting the boosted DC photovoltaic input voltage into AC voltage and outputting to the grid end N.
[0042] The inverter protection circuit comprises:
[0043] The blocking module 10 is connected between the boost module A1 and the inverter module A2, and is used for blocking the voltage of the grid end N from flowing into the inverter module through the ground end and the boost module when the insulation impedance between the DC input end and the ground is abnormal.
[0044] Specifically, referring to Figure 2 , U R represents the grid voltage, and the grid voltage alternately operates in the positive half cycle and the negative half cycle. If the grid voltage operates in the negative half cycle, a loop is formed between the lower IGBT of the inverter side of the power board and the grid side.
[0045] Optionally, the blocking module 10 can be a unidirectional conduction device, and can also be a device for controlling the conduction between the boost module A1 and the inverter module A2 when the grid voltage operates in the negative half cycle.
[0046] Specifically, referring to Figure 1 , the boost module A1 is connected with the PV+ terminal and the PV- terminal, the boost module A1 receives the DC photovoltaic input voltage generated by the photovoltaic panel through the PV+ terminal and the PV- terminal, the boost module A1 boosts and outputs the DC photovoltaic input voltage, the blocking module 10 transmits the boosted DC photovoltaic input voltage to the inverter module A2, and the inverter module A2 converts the boosted DC photovoltaic input voltage into AC voltage and outputs to the grid end N. At the same time, the blocking module 10 blocks the voltage of the grid end N from flowing into the inverter module A2 through the ground end and the boost module, so that when the insulation impedance between the PV- terminal or the wiring and the ground is abnormal, such as the short circuit between the PV- terminal or the wiring and the ground, referring to Figure 2 , and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the boost module A1 and the inverter module A2, so as to cause damage to the inverter module A2, thereby enabling the inverter to stably operate and reducing the failure probability of the photovoltaic grid-connected inverter.
[0047] In some optional embodiments, as shown in Figure 2 , the boost module A1 comprises one boost unit, the first end of the blocking module 10 is connected with the boost module A1, and the second end of the blocking module 10 is connected with the inverter module A2.
[0048] The boost module A1 includes a plurality of boost units, the first end of the blocking module 10 is connected with the plurality of boost units respectively, and the second end of the blocking module 10 is connected with the inverter module A2.
[0049] Specifically, referring to (A) in FIG. 1, the boost module A1 can include only one boost unit, so that when the insulation impedance of the PV- terminal or the wiring to ground is abnormal, such as the PV- terminal or the wiring to ground is short-circuited, and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the boost unit and the inverter module A2, so as to cause damage to the inverter module A2. Figure 3 Referring to (B) in FIG. 1, the boost module A1 can include a plurality of boost units, the plurality of PV+ terminals can be PV1+, PV2+... PVn+ respectively, the plurality of PV- terminals can be PV1-, PV2-... PVn- respectively, each boost unit is connected with PV+ and PV- to receive the direct-current photovoltaic input voltage and output after boosting to the blocking module 10. Thus, when the insulation impedance of any one or more PV- terminals is abnormal, such as the PV- terminal or the wiring to ground is short-circuited, and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the boost unit and the inverter module A2, so as to cause damage to the inverter module A2.
[0050] Figure 3 In some alternative embodiments, as shown in FIG. 2, the blocking module 10 is connected in the negative loop between the boost module A1 and the inverter module A2.
[0051] Specifically, referring to (A) in FIG. 2, the boost module A1 can include only one boost unit, so that when the insulation impedance of the PV- terminal or the wiring to ground is abnormal, such as the PV- terminal or the wiring to ground is short-circuited, and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the PV- terminal, the boost module A1 and the inverter module A2 to the grid end N, so as to cause damage to the inverter module A2. Figure 4 In some alternative embodiments, as shown in FIG. 2, the blocking module 10 is connected in the negative loop between the boost module A1 and the inverter module A2.
[0052] Figure 4 Specifically, referring to (A) in FIG. 2, the boost module A1 can include only one boost unit, so that when the insulation impedance of the PV- terminal or the wiring to ground is abnormal, such as the PV- terminal or the wiring to ground is short-circuited, and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the PV- terminal, the boost module A1 and the inverter module A2 to the grid end N, so as to cause damage to the inverter module A2.
[0053] In some alternative embodiments, as shown in FIG. 2, the boost unit includes a boost output capacitor C1, and the inverter module A2 includes a bus output capacitor C3 of an inverter lower half-bridge arm.
[0054] The first end of the blocking module 10 is connected with the negative end of the boost output capacitor C1, and the second end of the blocking module 10 is connected with the negative end of the bus output capacitor C3 of the inverter lower half-bridge arm.
[0055] Specifically, referring to (A) in FIG. 2, the boost module A1 can include only one boost unit, so that when the insulation impedance of the PV- terminal or the wiring to ground is abnormal, such as the PV- terminal or the wiring to ground is short-circuited, and the grid voltage operates in the negative half cycle, a loop is prevented from being formed between the grid end N, the PV- terminal, the boost module A1 and the inverter module A2 to the grid end N, so as to cause damage to the inverter module A2. Figure 5 , the boost module A1 includes a first inductor L1, a fourth capacitor C4, a first transistor M1, a second diode D2 and a boost output capacitor C1, so as to output after boosting for a direct current photovoltaic input voltage. The inverter module A2 includes a bus output capacitor C3 of an inverter lower half bridge arm, a bus output capacitor C2 of an inverter upper half bridge arm, three-phase respective power devices M2, three-phase respective LCL filter units composed of a second inductor L2, a third inductor L3 and a fifth capacitor C5, and a relay K1, the three phases being R phase, X phase and G phase respectively, that is, each has a power device M2 and an LCL filter unit.
[0056] Specifically, the PV+ terminal passes through the first inductor L1, the first diode D1, the bus output capacitor C2 of the inverter upper half bridge arm, the bus output capacitor C3 of the inverter lower half bridge arm and the blocking module 10 to return to the PV- terminal, that is, the blocking module 10 makes the current at the negative terminal of the bus output capacitor C3 of the inverter lower half bridge arm flow into the PV- terminal, while preventing the current at the PV- terminal from flowing to the power device and the diode of the inverter module A2, thereby preventing the photovoltaic inverter from failing and making the inverter operate stably.
[0057] It should be noted that the boost output capacitor C1 is used for decoupling of the boost module and the inverter module switch tube action, reducing current ripple, and also plays a role in filtering and energy storage. The bus output capacitor C2 of the inverter upper half bridge arm and the bus output capacitor C3 of the inverter lower half bridge arm mainly play a role in filtering and energy storage.
[0058] In some alternative embodiments, as shown in Figure 6 The blocking module 10 includes:
[0059] A first diode D1, a cathode of the first diode D1 being connected to a negative terminal of the boost output capacitor C1, and an anode of the first diode D1 being connected to a negative terminal of the bus output capacitor C3.
[0060] Specifically, by providing a first diode D1, the PV+ terminal passes through the first inductor L1, the first diode D1, the bus output capacitor C2 of the inverter upper half bridge arm, the bus output capacitor C3 of the inverter lower half bridge arm and the first diode D1 to return to the PV- terminal, while referring to Figure 7 , Figure 7 Taking the R phase as an example, when the PV- terminal and the ground terminal are short-circuited, the current at the grid terminal N is prevented from flowing into the PV- terminal, and the power device and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, thereby causing damage to the power device.
[0061] In some alternative embodiments, the blocking module 10 includes:
[0062] The blocking module 10 is a blocking module composed of a plurality of first diodes D1 in parallel and / or in series, a first end of the blocking module 10 is connected to the negative end of the boost output capacitor C1, and a second end of the blocking module 10 is connected to the negative end of the bus output capacitor C3.
[0063] Specifically, the blocking module 10 can also be a blocking module composed of a plurality of first diodes D1 in parallel and / or in series, so as to prevent the current of the grid end N from flowing into the PV- terminal, and the power devices and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, thereby causing damage to the power devices.
[0064] In some alternative embodiments, the blocking module 10 includes:
[0065] The transistor has a first end connected to the negative end of the boost output capacitor C1 and a second end connected to the negative end of the bus output capacitor C3.
[0066] Specifically, the blocking module 10 can be a transistor, and since the transistor includes a diode, it is not necessary to control the transistor, so that the cathode of the diode in the transistor is connected to the PV- terminal, and the anode of the diode in the transistor is connected to the negative end of the bus output capacitor C3 of the inverter lower half-bridge arm. Thus, when the PV- terminal and the ground end are short-circuited, the current of the grid end N is prevented from flowing into the PV- terminal, and the power devices and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, thereby causing damage to the power devices.
[0067] In some alternative embodiments, the blocking module 10 includes:
[0068] The field effect transistor has a first end connected to the negative end of the boost output capacitor C1 and a second end connected to the negative end of the bus output capacitor C3.
[0069] Specifically, the blocking module 10 can be a field effect transistor, and since the field effect transistor includes a diode, it is not necessary to control the field effect transistor, so that the cathode of the diode in the field effect transistor is connected to the PV- terminal, and the anode of the diode in the field effect transistor is connected to the negative end of the bus output capacitor C3 of the inverter lower half-bridge arm. Thus, when the PV- terminal and the ground end are short-circuited, the current of the grid end N is prevented from flowing into the PV- terminal, and the power devices and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, thereby causing damage to the power devices.
[0070] In some alternative embodiments, the blocking module 10 includes:
[0071] A relay, switch ends of the relay are connected with a negative pole end of the boost output capacitor C1 and a negative pole end of the bus output capacitor C3 respectively, the relay is used for disconnecting the connection between the negative pole end of the boost output capacitor C1 and the negative pole end of the bus output capacitor C3 after receiving a disconnect signal;
[0072] A control unit, the control unit is connected with a control end of the relay, and is used for outputting a disconnect signal when a direct current photovoltaic input negative pole voltage end is short-circuited with a ground end.
[0073] Specifically, the control unit outputs a disconnect signal to the relay when detecting that the direct current photovoltaic input negative pole voltage end (i.e. PV-) is short-circuited with the ground end, so that when the PV- terminal and the ground end are short-circuited, the current of the power grid end N is prevented from flowing into the PV- terminal, and the power device and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, so as to cause damage of the power device.
[0074] In the embodiment, an inverter is provided, the inverter comprises a boost module, an inverter module and the inverter protection circuit, so that when the PV- terminal and the ground end are short-circuited, the current of the power grid end N is prevented from flowing into the PV- terminal, and any power device and the second inductor L2 and the third inductor L3 of the inverter module A2 form a closed loop, so as to cause damage of the power device. It should be noted that since the inverter module A2 comprises three-phase power devices M2, three-phase LCL filter units each consisting of the second inductor L2, the third inductor L3 and the fifth capacitor C5, and the three phases are R phase, X phase and G phase respectively, the power device and the second inductor L2 and the third inductor L3 referred to herein can be any item in the R phase, the X phase and the G phase.
[0075] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.
Claims
1. An inverter protection circuit, characterized in that, The inverter protection circuit is connected to the boost module and the inverter module respectively. The inverter module is connected to the boost module. The boost module is connected to the DC input terminal and is used to receive the DC photovoltaic input voltage, boost the DC photovoltaic input voltage and output it. The inverter module is used to convert the boosted DC photovoltaic input voltage into AC voltage and output it to the grid terminal. The inverter protection circuit includes: A blocking module is connected between the boost module and the inverter module to block the voltage at the grid terminal from flowing into the inverter module through the ground terminal and the boost module when the insulation impedance of the DC input terminal to the ground is abnormal.
2. The inverter protection circuit according to claim 1, characterized in that, The boost module includes a boost unit, the first end of the blocking module is connected to the boost unit, and the second end of the blocking module is connected to the inverter module; Alternatively, the boost module may include multiple boost units, the first end of the blocking module may be connected to the multiple boost units, and the second end of the blocking module may be connected to the inverter module.
3. The inverter protection circuit according to claim 1, characterized in that, The blocking module is connected to the negative circuit between the boost module and the inverter module.
4. The inverter protection circuit according to claim 2, characterized in that, The boost unit includes a boost output capacitor, and the inverter module includes a bus output capacitor for the lower half-bridge arm of the inverter. The first terminal of the blocking module is connected to the negative terminal of the boost output capacitor, and the second terminal of the blocking module is connected to the negative terminal of the bus output capacitor of the lower half-bridge arm of the inverter.
5. The inverter protection circuit according to claim 4, characterized in that, The blocking module includes: A first diode, the cathode of which is connected to the negative terminal of the boost output capacitor, and the anode of which is connected to the negative terminal of the bus output capacitor of the lower half-bridge arm of the inverter.
6. The inverter protection circuit according to claim 4, characterized in that, The blocking module includes: A blocking module consisting of multiple first diodes connected in parallel and / or in series, wherein the first end of the blocking module is connected to the negative terminal of the boost output capacitor, and the second end of the blocking module is connected to the negative terminal of the bus output capacitor.
7. The inverter protection circuit according to claim 4, characterized in that, The blocking module includes: A transistor, wherein the first terminal of the transistor is connected to the negative terminal of the boost output capacitor, and the second terminal of the transistor is connected to the negative terminal of the bus output capacitor.
8. The inverter protection circuit according to claim 4, characterized in that, The blocking module includes: A field-effect transistor (FET) is provided, with its first terminal connected to the negative terminal of the boost output capacitor and its second terminal connected to the negative terminal of the bus output capacitor.
9. The inverter protection circuit according to claim 4, characterized in that, The blocking module includes: A relay, wherein the switching terminals of the relay are respectively connected to the negative terminals of the boost output capacitor and the negative terminals of the bus output capacitor, and the relay is used to disconnect the connection between the negative terminals of the boost output capacitor and the negative terminals of the bus output capacitor after receiving a disconnection signal; The control unit is connected to the control terminal of the relay and is used to output a disconnect signal when the negative voltage terminal of the DC photovoltaic input is short-circuited to the ground terminal.
10. An inverter, characterized in that, The inverter includes an inverter protection circuit as described in any one of claims 1 to 9.