Photovoltaic inverter, short circuit detection method and photovoltaic inverter system

Abstract

The invention relates to the photovoltaic field, and discloses a photovoltaic inverter, a short circuit detection method and a photovoltaic inversion system. The photovoltaic inverter comprises a booster circuit, an inverter circuit and a control circuit, the inverter circuit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a detection circuit, and the detection circuit is electrically connected with the first switch tube and the second switch tube at a first node and electrically connected with the third switch tube and the fourth switch tube at a second node. When the second node is short-circuited to the ground, the first switch tube is in a conducting state, and the second switch tube, the third switch tube and the fourth switch tube are in a disconnected state, the booster circuit, the first switch tube and the detection circuit can form a loop, and the control circuit can control the first switch tube to be in the conducting state. And the second switch tube, the third switch tube and the fourth switch tube are in an off state, and whether the second node is short-circuited to the ground is detected according to the voltage signal output by the detection circuit. The embodiment can automatically detect whether the second node is short-circuited to the ground or not.

Description

Technical Field

[0001] The present invention relates to the photovoltaic field, and in particular to a photovoltaic inverter, a short-circuit detection method and a photovoltaic inverter system. Background Art

[0002] A photovoltaic inverter is an inverter that can convert the variable DC voltage generated by photovoltaic modules into AC power at the mains frequency.

[0003] In actual use, the negative output pole of the photovoltaic inverter is not allowed to be short-circuited directly to the ground. At present, it is usually necessary for the installer to correctly install the photovoltaic inverter to ensure that the negative output pole of the photovoltaic inverter will not be short-circuited to the ground. After the photovoltaic inverter is installed, it is generally not tested again to ensure that the negative output pole of the photovoltaic inverter will not be short-circuited to the ground. However, when the installer does not correctly install the photovoltaic inverter, resulting in the negative output pole of the photovoltaic inverter being short-circuited to the ground, a large short-circuit current will be generated inside the photovoltaic inverter when the photovoltaic inverter is running, which can easily cause the photovoltaic inverter to heat up severely, or even damage the photovoltaic inverter. Summary of the invention

[0004] An object of the embodiments of the present invention is to provide a photovoltaic inverter, a short-circuit detection method and a photovoltaic inverter system, which can solve the technical problem in the prior art that it is impossible to automatically detect whether the output negative pole of the photovoltaic device is short-circuited to the ground.

[0005] In a first aspect, an embodiment of the present invention provides a photovoltaic inverter, comprising:

[0006] A boost circuit, used for electrically connecting to the photovoltaic module and receiving the voltage output by the photovoltaic module;

[0007] An inverter circuit, comprising a first bridge arm circuit, a second bridge arm circuit and a detection circuit, wherein the first bridge arm circuit comprises a first switch tube and a second switch tube connected in series, the first bridge arm circuit comprises a third switch tube and a fourth switch tube connected in series, the first switch tube and the third switch tube are electrically connected to the boost circuit, the detection circuit comprises a first node and a second node, the detection circuit is electrically connected to the first switch tube and the second switch tube at the first node, respectively, and is electrically connected to the third switch tube and the fourth switch tube at the second node, respectively, wherein when the second node is short-circuited to the ground, and the first switch tube is in a conducting state, and the second switch tube, the third switch tube and the fourth switch tube are in a disconnected state, the boost circuit, the first switch tube and the detection circuit can form a loop, so that the voltage signal output by the detection circuit falls within a first preset voltage range;

[0008] The control circuit is electrically connected to the boost circuit, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube and the detection circuit, respectively, and is used to control the first switch tube to be in an on state, the second switch tube, the third switch tube and the fourth switch tube to be in an off state, and to determine whether the voltage signal output by the detection circuit falls within a first preset voltage range. If so, it is determined that the second node is short-circuited to the ground.

[0009] In a second aspect, an embodiment of the present invention provides a short circuit detection method, which is applied to the photovoltaic inverter as described above. The short circuit detection method includes:

[0010] Controlling the first switch tube to be turned on, and controlling the second switch tube, the third switch tube, and the fourth switch tube to be in an off state, so that when the second node is short-circuited to the ground, the boost circuit, the first switch tube, and the detection circuit form a loop, and the voltage signal output by the detection circuit falls within a first preset voltage range;

[0011] Determining whether the voltage signal output by the detection circuit falls within a first preset voltage range;

[0012] If so, it is determined that the second node is short-circuited to ground.

[0013] In a third aspect, an embodiment of the present invention provides a controller, including:

[0014] at least one processor; and,

[0015] a memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores commands that can be executed by the at least one processor, and the commands are executed by the at least one processor so that the at least one processor can perform the short circuit detection method as described above.

[0017] In a fourth aspect, an embodiment of the present invention provides a non-volatile computer storage medium, wherein the non-volatile computer storage medium stores computer executable commands, and the computer executable commands are used to enable an electronic device to execute the short circuit detection method as described above.

[0018] In a fifth aspect, an embodiment of the present invention provides a photovoltaic inverter system, including:

[0019] Photovoltaic panels, which convert solar energy into electricity;

[0020] The photovoltaic inverter as described above is electrically connected to the photovoltaic assembly.

[0021] In the photovoltaic inverter provided in the embodiment of the present invention, a boost circuit, an inverter circuit and a control circuit are included. The boost circuit can be electrically connected to the photovoltaic module and receive the photovoltaic voltage of the photovoltaic module. The inverter circuit includes a first bridge arm circuit, a second bridge arm circuit and a detection circuit. The first bridge arm circuit includes a first switch tube and a second switch tube connected in series. The first bridge arm circuit includes a third switch tube and a fourth switch tube connected in series. The first switch tube and the third switch tube are electrically connected to the boost circuit. The detection circuit includes a first node and a second node. The detection circuit is electrically connected to the first switch tube and the second switch tube respectively at the first node, and is electrically connected to the third switch tube and the fourth switch tube respectively at the second node. , wherein, when the second node is short-circuited to the ground, and the first switch tube is in the on state, and the second switch tube, the third switch tube and the fourth switch tube are in the off state, the boost circuit, the first switch tube and the detection circuit can form a loop, so that the voltage signal output by the detection circuit falls into the first preset voltage range, and the control circuit is electrically connected to the boost circuit, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube and the detection circuit respectively, and can control the first switch tube to be in the on state, the second switch tube, the third switch tube and the fourth switch tube to be in the off state, and judge whether the voltage signal of the detection circuit falls into the first preset voltage range, and if it falls, it is determined that the second node is short-circuited to the ground. In the photovoltaic inverter, the second node is the output negative electrode of the photovoltaic inverter. Therefore, this embodiment can automatically detect whether the output negative electrode of the photovoltaic inverter is short-circuited to the ground, and avoid the problem that the output negative electrode of the photovoltaic inverter is short-circuited to the ground due to manual installation errors, resulting in serious heating or even damage to the photovoltaic inverter during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more embodiments are illustrated only as examples in the corresponding drawings, and these examples do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0023] Figure 1 is a schematic structural diagram of a photovoltaic inverter system provided by an embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of a photovoltaic inverter provided by an embodiment of the present invention;

[0025] Figure 3 is a schematic structural diagram of a photovoltaic inverter provided by another embodiment of the present invention;

[0026] Figure 4 It is a flow chart of a short circuit detection method provided by an embodiment of the present invention;

[0027] Figure 5is a structural schematic diagram of a short circuit detection device provided by an embodiment of the present invention;

[0028] Figure 6 is a structural schematic diagram of a short circuit detection device provided by another embodiment of the present invention;

[0029] Figure 7 It is a schematic diagram of the hardware structure of a controller provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that, if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, all within the scope of protection of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the device or the flow chart. Furthermore, the words "first", "second", "third", etc. used in the present invention do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0032] The embodiment of the present invention provides a photovoltaic inverter system. Figure 1 The photovoltaic inverter system 100 includes a photovoltaic component 10 and a photovoltaic inverter 20 .

[0033] The photovoltaic module 10 is a power generation device that generates direct current when exposed to sunlight. The photovoltaic module 10 is the core part of the photovoltaic inverter system 100 and is also the most important part of the photovoltaic inverter system 100. Its function is to convert solar energy into electrical energy, or send it to a battery for storage, or drive a load to work.

[0034] The photovoltaic inverter 20 is electrically connected to the photovoltaic assembly 10 and can be electrically connected to the power grid to convert the variable direct current generated by the photovoltaic assembly 10 into alternating current with a commercial power frequency and provide it to the power grid.

[0035] In some embodiments, see Figure 2 The photovoltaic inverter 20 includes a boost circuit 21 , an inverter circuit 22 and a control circuit 23 .

[0036] The boost circuit 21 may be electrically connected to the photovoltaic assembly 10 and receive the voltage output by the photovoltaic assembly 10 .

[0037] The boost circuit 21 includes a third node 20c. The boost circuit 21 can boost the direct current output by the photovoltaic assembly 10 and output the boosted voltage at the third node 20c.

[0038] The inverter circuit 22 is electrically connected to the boost circuit 21 and can invert the boosted voltage output by the boost circuit 21 and then output alternating current to provide to the grid.

[0039] like Figure 2 As shown, the inverter circuit 22 includes a first bridge arm circuit 221 , a second bridge arm circuit 222 and a detection circuit 223 .

[0040] The first bridge arm circuit 221 includes a first switch tube Q1 and a second switch tube Q2 connected in series. The first switch tube Q1 and the second switch tube Q2 are power switch tubes for implementing voltage inversion in the inverter circuit 22. The first switch tube Q1 or the second switch tube Q2 can be any suitable switch component such as a diode, a triode, a MOS tube, an insulated gate bipolar transistor, etc.

[0041] In some embodiments, see Figure 3 The first switch tube Q1 and the second switch tube Q2 are both insulated gate bipolar transistors. The collector of the first switch tube Q1 is electrically connected to the boost circuit 21 at the third node 20c, the gate of the first switch tube Q1 and the gate of the second switch tube Q2 are electrically connected to the control circuit 23, the emitter of the first switch tube Q1 is electrically connected to the collector of the second switch tube Q2 and the detection circuit 223, and the emitter of the second switch tube Q2 is grounded.

[0042] The second bridge arm circuit 222 includes a third switch tube Q3 and a fourth switch tube Q4 connected in series. The third switch tube Q3 and the fourth switch tube Q4 are power switch tubes for implementing voltage inversion in the inverter circuit 22. The third switch tube Q3 or the fourth switch tube Q4 can be any suitable switch component such as a diode, a triode, a MOS tube, an insulated gate bipolar transistor, etc.

[0043] In some embodiments, please refer to Figure 3 The third switch tube Q3 and the fourth switch tube Q4 are both insulated gate bipolar transistors. The collector of the third switch tube Q3 is electrically connected to the boost circuit 21 at the third node 20c, the gate of the third switch tube Q3 and the gate of the fourth switch tube Q4 are electrically connected to the control circuit 23, the emitter of the third switch tube Q3 is electrically connected to the collector of the fourth switch tube Q4 and the detection circuit 223, and the emitter of the fourth switch tube Q4 is grounded.

[0044] The detection circuit 223 includes a first node 20a and a second node 20b. The detection circuit 223 is electrically connected to the first switch tube Q1 and the second switch tube Q2 at the first node 20a, and is electrically connected to the third switch tube Q3 and the fourth switch tube Q4 at the second node 20b.

[0045] When the inverter circuit 22 inverts the boosted voltage output by the boost circuit 21, the first switch tube Q1 and the second switch tube Q2 are turned on alternately, the third switch tube Q3 and the fourth switch tube Q4 are turned on alternately, and the first switch tube Q1 and the fourth switch tube Q4 are synchronously in the on state or the off state, and the second switch tube Q2 and the third switch tube Q3 are synchronously in the on state or the off state.

[0046] When the first switch tube Q1 and the fourth switch tube Q4 are in the on state and the second switch tube Q2 and the third switch tube Q3 are in the off state, the boost circuit 21, the first switch tube Q1, the detection circuit 223 and the fourth switch tube Q4 form a loop, and the voltage output by the detection circuit 223 is positive.

[0047] When the first switch tube Q1 and the fourth switch tube Q4 are in the off state and the second switch tube Q2 and the third switch tube Q3 are in the on state, the boost circuit 21, the third switch tube Q3, the detection circuit 223 and the second switch tube Q2 form a loop, and the voltage output by the detection circuit 223 is negative.

[0048] Therefore, when the inverter circuit 22 inverts the boosted voltage output by the boost circuit 21, the detection circuit 223 can output an AC voltage.

[0049] It is worth noting that the second node 20b is the output negative electrode of the photovoltaic inverter 20, and the output negative electrode of the photovoltaic inverter 20 is not allowed to be directly grounded. If the output negative electrode of the photovoltaic inverter 20 is directly grounded, the second node 20b is short-circuited to the ground. At this time, the fourth switch tube Q4 is equivalent to being short-circuited. Therefore, when the inverter circuit 22 inverts the boosted voltage output by the boost circuit 21, and when the first switch tube Q1 and the fourth switch tube Q4 are in the on state and the second switch tube Q2 and the third switch tube Q3 are in the off state, the boost circuit 21, the first switch tube Q1 and the ground form a loop, generating a large short-circuit current, causing severe heating, and may eventually cause the photovoltaic inverter 20 to age or even be damaged.

[0050] In this embodiment, when the second node 20b is short-circuited to the ground, the first switch tube Q1 is in the on state, and the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are in the off state, the boost circuit 21, the first switch tube Q1 and the detection circuit 223 can form a loop, so that the voltage signal output by the detection circuit 223 falls within the first preset voltage range. The first preset voltage range can be set according to actual conditions and is not limited here.

[0051] The control circuit 23 is electrically connected to the boost circuit 21, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4 and the detection circuit 223 respectively. When the photovoltaic inverter 20 is powered on, the control circuit 23 can control the first switch tube Q1 to be in the on state, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 to be in the off state, and judge whether the voltage signal output by the detection circuit 223 falls into the first preset voltage range. If the voltage signal output by the detection circuit 223 falls into the first preset voltage range, it is determined that the second node 20b is short-circuited to the ground, that is, the output negative pole of the photovoltaic inverter 20 is directly grounded.

[0052] Therefore, this embodiment can automatically detect whether the output negative pole of the photovoltaic inverter is short-circuited to the ground, thereby avoiding the problem that the output negative pole of the photovoltaic inverter is short-circuited to the ground due to manual installation errors, resulting in severe heating or even damage of the photovoltaic inverter during operation.

[0053] In some embodiments, please refer to Figure 3 , the detection circuit 223 includes a first inductor L1 and a first capacitor C1.

[0054] One end of the first inductor L1 is electrically connected to the first switch tube Q1 and the second switch tube Q2 at the first node 20a, the other end of the first inductor L1 is electrically connected to one end of the first capacitor C1 and the control circuit 23, and the other end of the first capacitor C1 is electrically connected to the third switch tube Q3, the fourth switch tube Q4 and the control circuit 23 at the second node 20b.

[0055] In this embodiment, the control circuit 23 controls the first switch tube Q1 to be in the on state, and the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 to be in the off state. If the second node 20b is short-circuited to the ground, the boost circuit 21, the first switch tube Q1, the first inductor L1 and the first capacitor C1 can form a loop, and the DC voltage output by the boost circuit 21 can charge the first capacitor C1 through the loop. Therefore, during the charging process of the first capacitor C1, the voltage across the first capacitor C1 is continuously increased until the voltage across the first capacitor C1 falls into the first preset voltage range; if the second node 20b is not short-circuited to the ground, the boost circuit 21, the first switch tube Q1, the first inductor L1 and the first capacitor C1 do not form a loop. At this time, the first capacitor C1 is not charged, and the voltage across the first capacitor C1 does not fall into the first preset voltage range.

[0056] Therefore, the control circuit 23 only needs to determine whether the voltage across the first capacitor C1 falls within the first preset voltage range to detect whether the second node 20b is short-circuited to the ground.

[0057] In the present embodiment, the first inductor L1 is used as an output inductor in the photovoltaic inverter 20, which has the function of preventing the transmission of high-frequency signals and reducing high-frequency noise interference, and is helpful to ensure the normal operation of the photovoltaic inverter 20. At the same time, the first inductor L1 can also stabilize the output voltage, thereby improving the quality and stability of the output voltage. In addition, the first inductor L1 can also extend the service life of the first capacitor C1, prevent the first capacitor C1 from oscillating, and improve the reliability and stability of the output end of the photovoltaic inverter 20. The first capacitor C1 is used as an output capacitor in the photovoltaic inverter 20. Since the first capacitor C1 has the characteristic of storing electric energy, it can absorb the sudden change and fluctuation of the output voltage, smooth the output voltage, and make the output voltage more stable. In addition, the first capacitor C1 can filter out the high-frequency noise in the output voltage and improve the quality of the output voltage.

[0058] In this embodiment, since the first inductor L1 and the first capacitor C1 are the original hardware circuits of the photovoltaic inverter 20, this embodiment can reuse the original hardware circuits of the photovoltaic inverter 20 for online detection without adding additional hardware circuits. It is convenient to perform short-circuit detection on the photovoltaic inverter without adding additional hardware costs for short-circuit detection.

[0059] In some embodiments, Figure 3 As shown, the boost circuit 21 includes a second inductor L2, a first diode D1, a fifth switch tube Q5 and a second capacitor C2.

[0060] One end of the second inductor L2 is electrically connected to the photovoltaic component 10, and the other end of the second inductor L2 is electrically connected to the anode of the first diode D1 and the fifth switch tube Q5 respectively. The cathode of the first diode D1 is electrically connected to one end of the second capacitor C2, the first switch tube Q1 and the third switch tube Q3 respectively. The other end of the second capacitor C2 is grounded, and the fifth switch tube Q5 is also electrically connected to the control circuit 23.

[0061] When the boost circuit 21 needs to work, the control circuit 23 controls the fifth switch tube Q5 to switch at a certain frequency. When the fifth switch tube Q5 is in the on state, the second inductor L2 is grounded through the fifth switch tube Q5, the first diode D1 is in the off state, and the second inductor L2 uses the direct current output by the photovoltaic component 10 to store energy. The voltage across the second inductor L2 is the direct current voltage output by the photovoltaic component 10; when the fifth switch tube Q5 is in the off state, since the current across the second inductor L2 cannot change suddenly, a voltage is induced, so that the first diode D1 is in the on state, and the energy stored in the second inductor L2 begins to charge the second capacitor C2 through the first diode D1, so that the voltage across the second capacitor C2 increases, and the voltage across the second capacitor C2 can increase to be greater than the voltage output by the photovoltaic component 10, thereby achieving boosting.

[0062] In some embodiments, Figure 3 As shown, the control circuit 23 includes a first voltage sampling circuit 231 , a second voltage sampling circuit 232 and a controller 233 .

[0063] The first voltage sampling circuit 231 is electrically connected to the boost circuit 21 and can sample the voltage output by the photovoltaic assembly 10 .

[0064] The second voltage sampling circuit 232 is electrically connected to the first inductor L1 and the first capacitor C1 at the first node 20a, and is electrically connected to the first capacitor C1 at the second node 20b, and can sample the voltage across the first capacitor C1.

[0065] The controller 233 is electrically connected to the first voltage sampling circuit 231 , the second voltage sampling circuit 232 , the boost circuit 21 , the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 respectively.

[0066] In this embodiment, when the photovoltaic inverter 20 is powered on, the controller 233 detects through the first voltage sampling circuit 231 whether the voltage output by the photovoltaic component 10 falls into the second preset voltage range for a preset time period. If it falls into the second preset voltage range for a preset time period, the first switch tube Q1 is controlled to be turned on, and the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in the disconnected state. The second voltage sampling circuit 232 is used to determine whether the voltage across the first capacitor C1 falls into the first preset voltage range to detect whether the second node 20b is short-circuited to the ground.

[0067] Therefore, in this embodiment, the short circuit detection operation is performed only when the DC voltage output by the photovoltaic module 10 reaches a certain condition, which can improve the reliability and accuracy of the detection.

[0068] In some embodiments, Figure 3 As shown, the photovoltaic inverter 20 further includes a voltage conversion circuit 24 .

[0069] The voltage conversion circuit 24 can be electrically connected to the battery and the controller 233 respectively, and can be electrically connected to the first switch tube Q1 and the third switch tube Q3 at the third node 20c respectively. When the battery power is needed to provide AC power to the power grid, the controller 233 can control the voltage conversion circuit 24 to work. At this time, the voltage conversion circuit 24 can convert the DC power output by the battery into AC power and provide it to the power grid.

[0070] In some embodiments, Figure 3 As shown, the control circuit 23 further includes a third voltage sampling circuit 234 .

[0071] The third voltage sampling circuit 234 is electrically connected to the voltage conversion circuit 24 and the controller 233 respectively, and can sample the voltage output by the battery.

[0072] As described above, when the controller 233 detects that the voltage output by the photovoltaic component 10 does not fall within the second preset voltage range for a preset period of time, the controller 233 detects whether the voltage output by the battery falls within the third preset voltage range for a preset period of time through the third voltage sampling circuit 234. If it falls within the third preset voltage range for a preset period of time, the control voltage conversion circuit 24 converts the voltage output by the battery and applies the output voltage to the third node 20c, controls the first switch tube Q1 to be turned on, and controls the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 to be in the disconnected state, and determines whether the voltage across the first capacitor C1 falls within the first preset voltage range through the second voltage sampling circuit 232 to detect whether the second node 20b is short-circuited to the ground.

[0073] It can be understood that if the second node 20b is short-circuited to the ground, the voltage conversion circuit 24, the first switch tube Q1, the first inductor L1 and the first capacitor C1 can form a loop, and the voltage output by the voltage conversion circuit 24 can charge the first capacitor C1 through the loop, so during the charging process of the first capacitor C1, the voltage across the first capacitor C1 continues to rise until the voltage across the first capacitor C1 falls into the first preset voltage range; if the second node 20b is not short-circuited to the ground, the voltage conversion circuit 24, the first switch tube Q1, the first inductor L1 and the first capacitor C1 do not form a loop, the first capacitor C1 is not charged, and the voltage across the first capacitor C1 does not fall into the first preset voltage range.

[0074] Therefore, the control circuit 23 only needs to determine whether the voltage across the first capacitor C1 falls within the first preset voltage range to detect whether the second node 20b is short-circuited to the ground. In this way, even when the photovoltaic inverter 20 is not connected to the photovoltaic component 10, the present embodiment can also implement short-circuit detection of the photovoltaic inverter 20, thereby improving detection flexibility.

[0075] In some embodiments, see Figure 1 The photovoltaic inverter 20 also includes a switching circuit 25 .

[0076] The switch circuit 25 can be electrically connected to the power grid, and is electrically connected to the detection circuit 223 and the controller 233. When the inverter circuit 22 is inverting, the controller 233 controls the switch circuit 25 to be in a closed state. At this time, the AC power output by the inverter circuit 22 can be provided to the power grid through the switch circuit 25.

[0077] In some embodiments, the switch circuit 25 may include any suitable switch device, such as a relay, a contactor, etc.

[0078] In some embodiments, before detecting whether the voltage output by the photovoltaic component falls within the second preset voltage range for a preset time period, the controller 233 also detects whether the photovoltaic inverter 20 is in a stable state. When the photovoltaic inverter 20 is in a stable state, the controller 233 executes the step of detecting whether the voltage output by the photovoltaic component 20 falls within the second preset voltage range for a preset time period.

[0079] Therefore, in this way, the detection reliability and accuracy can be further improved.

[0080] In some embodiments, Figure 3 As shown, the control circuit 23 further includes a fourth voltage sampling circuit 235 , a fifth voltage sampling circuit 236 , a first current sampling circuit 237 , a second current sampling circuit 238 , a third current sampling circuit 239 and a fourth current sampling circuit 230 .

[0081] The fourth voltage sampling circuit 235 is electrically connected to the controller 233 and is respectively electrically connected to the boost circuit 21 , the first switch tube Q1 and the third switch tube Q3 at the third node 20 c , and can sample the voltage of the third node 20 c .

[0082] The fifth voltage sampling circuit 236 is electrically connected to the controller 233 and can be electrically connected to the grid to sample the voltage of the grid.

[0083] The first current sampling circuit 237 is electrically connected to the boost circuit 21 and the controller 233 respectively, and can sample the current output by the photovoltaic assembly 10 .

[0084] The second current sampling circuit 238 is electrically connected to the voltage conversion circuit 24 and the controller 233 respectively, and can sample the current output by the battery.

[0085] The third current sampling circuit 239 is electrically connected to the controller 233 and is respectively electrically connected to the first switch tube Q1 , the second switch tube Q2 and the detection circuit 223 at the first node 20 a to sample the inverter current.

[0086] The fourth current sampling circuit 230 is electrically connected to the detection circuit 223 and the controller respectively, and can sample the current output by the detection circuit 223 .

[0087] When the photovoltaic inverter 20 is powered on:

[0088] The controller 233 detects through the first voltage sampling circuit 231 whether the voltage effective value change rate of the photovoltaic assembly 10 is less than the preset voltage threshold for a preset time period. If so, it is determined that the voltage output by the photovoltaic assembly 10 is normal; if not, it is determined that the voltage output by the photovoltaic assembly 10 is abnormal.

[0089] The controller 233 detects through the second voltage sampling circuit 232 whether the voltage effective value change rate across the first capacitor C1 is less than the preset voltage threshold for a preset time period. If so, it is determined that the voltage across the first capacitor C1 is normal; if not, it is determined that the voltage across the first capacitor C1 is abnormal.

[0090] The controller 233 detects through the third voltage sampling circuit 234 whether the change rate of the effective value of the voltage output by the battery is less than the preset voltage threshold for a preset time period. If so, it is determined that the voltage output by the battery is normal; if not, it is determined that the voltage output by the battery is abnormal;

[0091] The controller 233 detects through the fourth voltage sampling circuit 235 whether the voltage effective value change rate of the third node 20c is less than the preset voltage threshold for a preset time period. If so, the voltage of the third node 20c is detected to be normal. If not, the voltage of the third node 20c is detected to be abnormal.

[0092] The controller 233 detects through the fifth voltage sampling circuit 236 whether the voltage effective value change rate of the power grid is less than the preset voltage threshold for a preset time period. If so, it is determined that the voltage of the power grid is normal; if not, it is determined that the voltage of the power grid is abnormal;

[0093] The controller 233 detects through the first current sampling circuit 237 whether the effective value change rate of the current output by the photovoltaic assembly 10 is less than the preset current threshold value for a preset time period. If so, it is determined that the current output by the photovoltaic assembly 10 is normal; if not, it is determined that the current output by the photovoltaic assembly 10 is abnormal.

[0094] The controller 233 detects through the second current sampling circuit 238 whether the current effective value change rate of the current output by the battery is less than the preset current threshold value for a preset time period. If so, it is determined that the current output by the battery is normal; if not, it is determined that the current output by the battery is abnormal;

[0095] The controller 233 detects through the third current sampling circuit 239 whether the inverter current effective value change rate is less than the preset current threshold value for a preset time period. If so, it is determined that the inverter current is normal; if not, it is determined that the inverter current is abnormal;

[0096] The controller 233 detects through the fourth current sampling circuit 230 whether the change rate of the effective value of the current output by the detection circuit 223 is less than the preset current threshold for a preset time period. If so, it is determined that the current output by the detection circuit 223 is normal; if not, it is determined that the current output by the detection circuit 223 is abnormal.

[0097] When the controller 233 determines that the voltage and current output by the photovoltaic component 10, the voltage across the first capacitor C1, the voltage and current output by the battery, the voltage at the third node 20c, the voltage inversion current of the grid and the current output by the detection circuit 223 are all normal, it can be determined that the photovoltaic inverter 20 is in a stable state.

[0098] In order to explain the working principle of the photovoltaic inverter 20 provided by the embodiment of the present invention in more detail, Figure 3 To elaborate.

[0099] When the photovoltaic inverter 20 is powered on, the controller 233 detects whether the photovoltaic inverter 20 is in a stable state through the first voltage sampling circuit 231, the second voltage sampling circuit 232, the third voltage sampling circuit 234, the fourth voltage sampling circuit 235, the fifth voltage sampling circuit 236, the first current sampling circuit 237, the second current sampling circuit 238, the third current sampling circuit 239 and the fourth current sampling circuit 230.

[0100] If the photovoltaic inverter 20 is in a stable state, the controller 233 detects whether the DC voltage output by the photovoltaic component 10 falls within the voltage range of 120V-450V for 5 seconds. If the DC voltage output by the photovoltaic component 10 falls within the voltage range of 120V-450V for 5 seconds, the first switch tube Q1 is controlled to be in an on state, and the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are controlled to be in an off state, and the voltage across the first capacitor C1 is detected after waiting for 5 seconds. If the voltage across the first capacitor C1 is within the first preset voltage range, it is determined that the second node 20b is short-circuited to the ground. If the voltage across the first capacitor C1 is not within the first preset voltage range, it is determined that the second node 20b is not short-circuited to the ground.

[0101] When it is determined that the second node 20 b is short-circuited to the ground, the controller 233 ends the detection and generates fault information, where the fault information is used to indicate that the output negative electrode of the photovoltaic inverter 20 is short-circuited to the ground.

[0102] When it is determined that the second 20b is not short-circuited to the ground, the controller 233 outputs a control signal to control the fifth switch tube Q5 to switch at a certain frequency, so that the boost circuit 21 boosts the voltage output by the photovoltaic component 10 and outputs the boosted voltage at the third node 20c. Then, the controller 233 controls the inverter circuit 22 to work, so that the inverter circuit 22 inverts the boosted voltage and outputs AC power. Finally, the controller 233 controls the switch circuit 25 to be in a closed state, so that the AC power output by the inverter circuit 22 is provided to the power grid through the switch circuit 25.

[0103] If the DC voltage output by the photovoltaic component 10 falls within the voltage range of 120V-450V for 5 seconds, the controller 233 detects whether the voltage output by the battery falls within the third preset voltage range for 5 seconds. If the voltage output by the battery falls within the third preset voltage range for 5 seconds, the controller 233 controls the voltage conversion circuit 24 to work. At this time, the voltage conversion circuit 24 converts the voltage output by the battery and applies it to the third node 20c. Then, the controller 233 controls the first switch tube Q1 to be in the on state, and controls the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 to be in the off state, and waits for 5 seconds before detecting the voltage across the first capacitor C1. If the voltage across the first capacitor C1 is within the first preset voltage range, it is determined that the second node 20b is short-circuited to the ground. If the voltage across the first capacitor C1 is not within the first preset voltage range, it is determined that the second node 20b is not short-circuited to the ground.

[0104] When it is determined that the second node 20 b is short-circuited to the ground, the controller 233 ends the detection and generates fault information, where the fault information is used to indicate that the output negative electrode of the photovoltaic inverter 20 is short-circuited to the ground.

[0105] When it is determined that the second 20b is not short-circuited to the ground, the controller 233 controls the inverter circuit 22 to operate, so that the inverter circuit 22 inverts the voltage of the third node 20c and outputs AC power. The controller 233 then controls the switch circuit 25 to be in a closed state, so that the AC power output by the inverter circuit 22 is provided to the power grid through the switch circuit 25.

[0106] The embodiment of the present invention provides a short circuit detection method, which is applied to the photovoltaic inverter as described above. Figure 4 , short circuit detection methods include:

[0107] S41, controlling the first switch tube to be turned on, and controlling the second switch tube, the third switch tube and the fourth switch tube to be in an off state, so that when the second node is short-circuited to the ground, the boost circuit, the first switch tube and the detection circuit form a loop, and the voltage signal output by the detection circuit falls within a first preset voltage range;

[0108] S42, determining whether the voltage signal output by the detection circuit falls within a first preset voltage range;

[0109] S43: If yes, it is determined that the second node is short-circuited to the ground.

[0110] Therefore, this embodiment can automatically detect whether the output negative pole of the photovoltaic inverter is short-circuited to the ground, thereby avoiding the problem that the output negative pole of the photovoltaic inverter is short-circuited to the ground due to manual installation errors, resulting in severe heating or even damage of the photovoltaic inverter during operation.

[0111] In some embodiments, before executing step S41, the short circuit detection method also includes: detecting whether the photovoltaic inverter is in a stable state; if so, detecting whether the photovoltaic voltage falls within a second preset voltage range; if so, controlling the first switch tube to be turned on, and controlling the second switch tube, the third switch tube and the fourth switch tube to be in a disconnected state.

[0112] The embodiment of the present invention provides a short circuit detection device. Figure 5 The short circuit detection device 500 includes a control module 51 , a judgment module 52 and a determination module 53 .

[0113] The control module 51 is used to control the first switch tube to be turned on, and to control the second switch tube, the third switch tube and the fourth switch tube to be in the off state, so that when the second node is short-circuited to the ground, the boost circuit, the first switch tube and the detection circuit form a loop, and the voltage signal output by the detection circuit falls into the first preset voltage range. The judgment module 52 is used to judge whether the voltage signal output by the detection circuit falls into the first preset voltage range. The determination module 53 is used to determine that the second node is short-circuited to the ground when the voltage signal output by the detection circuit falls into the first preset voltage range.

[0114] Therefore, this embodiment can automatically detect whether the output negative pole of the photovoltaic inverter is short-circuited to the ground, thereby avoiding the problem that the output negative pole of the photovoltaic inverter is short-circuited to the ground due to manual installation errors, resulting in severe heating or even damage of the photovoltaic inverter during operation.

[0115] In some embodiments, see Figure 6 The short circuit detection device 500 also includes a first detection module 54 and a second detection module 55 .

[0116] The first detection module 54 is used to detect whether the photovoltaic inverter is in a stable state. The first detection module 54 is used to detect whether the photovoltaic voltage falls within a second preset voltage range when the photovoltaic inverter is in a stable state.

[0117] See also Figure 7 , Figure 7 FIG. 1 is a schematic diagram of the hardware structure of a controller provided by an embodiment of the present invention. Figure 7 As shown, the controller 233 includes one or more processors 2331 and a memory 2332. Figure 7 A processor 2331 is taken as an example.

[0118] The processor 2331 and the memory 2332 may be connected via a bus or other means. Figure 7 The example of connecting through bus is taken in the following.

[0119] The memory 2332 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the short-circuit detection method in the embodiment of the present invention. The processor 2331 executes various functional applications and data processing of the radar calibration device by running the non-volatile software programs, instructions and modules stored in the memory 2332, that is, realizes the short-circuit detection method provided in the above method embodiment and the functions of each module or unit in the above device embodiment.

[0120] The memory 2332 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 2332 includes a memory remotely arranged relative to the processor 2331, and these remote memories may be connected to the processor 2331 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0121] The program instructions / modules are stored in the memory 2332 , and when executed by the one or more processors 2331 , the short circuit detection method in any of the above method embodiments is executed.

[0122] The embodiment of the present invention further provides a non-volatile computer storage medium, wherein the non-volatile computer storage medium stores computer executable instructions, and the computer executable instructions are executed by one or more processors, such as Figure 7 A processor 2331 in the embodiment may enable the one or more processors to execute the short circuit detection method in any of the above method embodiments.

[0123] An embodiment of the present invention further provides a computer program product, which includes a computer program stored on a non-volatile computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by an electronic device, the electronic device executes any one of the short-circuit detection methods.

[0124] The above described device or equipment embodiments are merely illustrative, wherein the unit modules described as separate components may or may not be physically separated, and the components displayed as module units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network module units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0125] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0126] Finally, it should be noted that the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these implementations is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, under the idea of ​​the present invention, the above-mentioned technical features continue to be combined with each other, and there are many other changes in different aspects of the present invention as described above, which are all considered to be within the scope of the present invention specification; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present invention.

Claims

1. A photovoltaic inverter, characterized in that, it includes: A boost circuit for electrically connecting to a photovoltaic module and receiving the voltage output by the photovoltaic module; An inverter circuit, including a first arm circuit, a second arm circuit and a detection circuit. The first arm circuit includes a first switch tube and a second switch tube connected in series. The first arm circuit includes a third switch tube and a fourth switch tube connected in series. The first switch tube and the third switch tube are electrically connected to the boost circuit. The detection circuit includes a first node and a second node. The detection circuit is electrically connected to the first switch tube and the second switch tube at the first node respectively, and is electrically connected to the third switch tube and the fourth switch tube at the second node respectively. Wherein, when the second node is short-circuited to the ground, and the first switch tube is in the on state, and the second switch tube, the third switch tube and the fourth switch tube are in the off state, the boost circuit, the first switch tube and the detection circuit can form a loop, so that the voltage signal output by the detection circuit falls within a first preset voltage range; A control circuit, electrically connected to the boost circuit, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube and the detection circuit respectively, for controlling the first switch tube to be in the on state, and the second switch tube, the third switch tube and the fourth switch tube to be in the off state, and judging whether the voltage signal output by the detection circuit falls within the first preset voltage range. If it falls within, it is determined that the second node is short-circuited to the ground.

2. The photovoltaic inverter according to claim 1, characterized in that, the detection circuit includes a first inductor and a first capacitor; One end of the first inductor is electrically connected to the first switch tube and the second switch tube at the first node respectively, the other end of the first inductor is electrically connected to one end of the first capacitor and the control circuit respectively, and the other end of the first capacitor is electrically connected to the third switch tube, the fourth switch tube and the control circuit at the second node respectively; When the second node is short-circuited to the ground, and the first switch tube is in the on state, and the second switch tube, the third switch tube and the fourth switch tube are in the off state, the boost circuit, the first switch tube, the first inductor and the first capacitor can form a loop, so that the voltage signal across the first capacitor falls within a preset voltage range.

3. The photovoltaic inverter according to claim 2, characterized in that, the control circuit includes: A first voltage sampling circuit, electrically connected to the boost circuit, for sampling the voltage output by the photovoltaic module; A second voltage sampling circuit, electrically connected to the first inductor and the first capacitor at the first node respectively, and electrically connected to the first capacitor at the second node, for sampling the voltage across the first capacitor; A controller, electrically connected to the first voltage sampling circuit, the second voltage sampling circuit, the boost circuit, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube respectively, is configured to detect whether the voltage output by the photovoltaic module falls within a second preset voltage range for a preset duration. If it falls within the second preset voltage range for the preset duration, the controller controls the first switching tube to conduct, and controls the second switching tube, the third switching tube and the fourth switching tube to be in an off state, and determines whether the voltage across the first capacitor falls within a first preset voltage range.

4. The photovoltaic inverter according to claim 3, wherein, before detecting whether the voltage output by the photovoltaic module falls within a second preset voltage range for a preset duration, the controller is further configured to detect whether the photovoltaic inverter is in a stable state. When the photovoltaic inverter is in a stable state, the controller performs the step of detecting whether the voltage output by the photovoltaic module falls within a second preset voltage range for a preset duration.

5. The photovoltaic inverter according to claim 1, wherein, the boost circuit includes a second inductor, a first diode, a fifth switching tube and a second capacitor; one end of the second inductor is configured to be electrically connected to the photovoltaic module, the other end of the second inductor is respectively electrically connected to the anode of the first diode and the fifth switching tube, the cathode of the first diode is respectively electrically connected to one end of the second capacitor, the first switching tube and the third switching tube, the other end of the second capacitor is grounded, and the fifth switching tube is further electrically connected to the control circuit.

6. A short - circuit detection method, wherein, applied to the photovoltaic inverter according to any one of claims 1 to 5, the short - circuit detection method includes: controlling the first switching tube to conduct, and controlling the second switching tube, the third switching tube and the fourth switching tube to be in an off state, so that when the second node is short - circuited to the ground, the boost circuit, the first switching tube and the detection circuit form a loop, and the voltage signal output by the detection circuit falls within a first preset voltage range; judging whether the voltage signal output by the detection circuit falls within a first preset voltage range; if it falls within, determining that the second node is short - circuited to the ground.

7. The short - circuit detection method according to claim 6, wherein, before controlling the first switching tube to conduct, and controlling the second switching tube, the third switching tube and the fourth switching tube to be in an off state, it further includes: detecting whether the photovoltaic inverter is in a stable state; if it is in a stable state, detecting whether the voltage output by the photovoltaic module falls within a second preset voltage range for a preset duration; if it falls within the second preset voltage range for a preset duration, controlling the first switching tube to conduct, and controlling the second switching tube, the third switching tube and the fourth switching tube to be in an off state.

8. A controller, wherein, includes: at least one processor; and, a memory communicatively connected to the at least one processor; wherein, The memory stores commands executable by the at least one processor, and the commands are executed by the at least one processor to enable the at least one processor to execute the short-circuit detection method according to claim 6 or 7.

9. A non-volatile computing storage medium, characterized in that, the non-volatile computer storage medium stores computer-executable commands for causing an electronic device to execute the short-circuit detection method according to claim 6 or 7.

10. A photovoltaic inverter system, characterized in that, comprising: a photovoltaic module for converting solar energy into electrical energy; a photovoltaic inverter according to any one of claims 1 to 5, the photovoltaic inverter being electrically connected to the photovoltaic module.

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