Power conversion device, inverter and photovoltaic power generation system

Abstract

The utility model relates to a power conversion device, an inverter and a photovoltaic power generation system.The power conversion device comprises a power conversion circuit and an alarm circuit, the power conversion circuit comprises a first bridge arm and a second bridge arm which are connected in series, the first bridge arm is used for being connected with an input source, and the second bridge arm is used for being connected with a load; the first bridge arm comprises a first switching tube and a second switching tube which are connected in series, the second bridge arm comprises a third switching tube and a fourth switching tube which are connected in series, and the midpoint of the first bridge arm is connected with the midpoint of the second bridge arm through an inductor; when the first switch tube, the second switch tube and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting reverse connection of the input source. According to the application, the problems of material cost caused by hardware fool-proof and detection circuits and high software complexity caused by software detection can be reduced.

Description

Technical Field

[0001] The present application relates to the field of circuit detection technology, and in particular to a power conversion device, an inverter, and a photovoltaic power generation system. Background Art

[0002] Buck-Boost power converters are essential transmission devices for many new energy systems, such as photovoltaic power generation. Due to the widespread distribution of energy, a large number of these transmission devices are required. This can lead to increased wiring complexity and errors. Related technologies aim to reduce wiring issues through hardware error prevention, by adding detection circuits to detect wiring errors, and by using software to detect wiring errors.

[0003] However, in the above-mentioned related technologies, hardware anti-fouling and detection circuits easily lead to increased material costs when a large amount of wiring is required, and software detection easily leads to increased software complexity or higher requirements for controllers such as CPUs. Utility Model Content

[0004] In view of the above, it is necessary to provide a power conversion device, inverter and photovoltaic power generation system with the function of detecting whether the wiring is wrong, which can reduce the material cost caused by hardware anti-fool and detection circuits and the high software complexity caused by software detection.

[0005] The present application provides a power conversion device, including: a power conversion circuit and an alarm circuit, the power conversion circuit including a first bridge arm and a second bridge arm connected in series, the first bridge arm being used to connect an input source, the second bridge arm being used to connect a load, the first bridge arm including a first switch tube and a second switch tube connected in series, the second bridge arm including a third switch tube and a fourth switch tube connected in series, the midpoint of the first bridge arm being connected to the midpoint of the second bridge arm via an inductor; wherein, when the input source outputs a voltage and the power conversion circuit is not working, the first switch tube, the second switch tube and the third switch tube are all turned off, and the fourth switch tube is turned on; when the first switch tube, the second switch tube and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

[0006] In some embodiments, when the first switch tube, the second switch tube, and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows to the second bridge arm, the power conversion circuit starts to operate.

[0007] In some embodiments, the alarm circuit includes a first acquisition unit connected between the inductor and the first bridge arm and configured to acquire a current of the inductor.

[0008] In some embodiments, the alarm circuit further includes a control unit, which is configured to determine a current direction of the inductor and output a prompt signal when the current direction of the inductor is flowing toward the first bridge arm.

[0009] In some embodiments, the alarm circuit further includes a second acquisition unit, which is connected in parallel with the first bridge arm and to the input source, and is used to acquire the voltage of the first bridge arm.

[0010] In some embodiments, the control unit is further configured to output a prompt signal when the voltage of the first bridge arm detected by the second detection unit is a negative value.

[0011] The present application also provides an inverter, comprising a power conversion device, an inverter circuit, and a DC bus. The input end of the power conversion device is connected to an input source, and the output end of the power conversion device is connected to the inverter circuit via the DC bus. The inverter circuit is used to convert DC power from the DC bus into AC power, and the power conversion device is used to raise or lower the voltage input from the input source to the DC bus. The power conversion device includes: a power conversion circuit and an alarm circuit. The power conversion circuit includes a first bridge arm and a second bridge arm connected in series. The first bridge arm is used to connect to the input source, and the second bridge arm is used to connect to the load. The first bridge arm includes a first switching tube and a second switching tube connected in series. The second bridge arm includes a third switching tube and a fourth switching tube connected in series. The midpoint of the first bridge arm is connected to the midpoint of the second bridge arm via an inductor. When the input source outputs a voltage and the power conversion circuit is not operating, the first switching tube, the second switching tube, and the third switching tube are all turned off, and the fourth switching tube is turned on. When the first switching tube, the second switching tube, and the third switching tube are all turned off, the fourth switching tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

[0012] The present application also provides a photovoltaic power generation system, including photovoltaic modules and inverters; the inverter is used to convert the electric energy generated by the photovoltaic modules into power and transmit it to the power grid or energy storage battery; the inverter includes a power conversion device, an inverter circuit and a DC bus, the input end of the power conversion device is connected to the photovoltaic module source, the output end of the power conversion device is connected to the inverter circuit through the DC bus, the inverter circuit is used to convert the DC power of the DC bus into AC power, and the power conversion device is used to raise or lower the voltage input to the DC bus by the photovoltaic module; the power conversion device includes: a power conversion circuit and an alarm circuit, the power conversion circuit includes a first bridge arm and a second bridge arm connected in series Two bridge arms, the first bridge arm is used to connect the input source, the second bridge arm is used to connect the load, the first bridge arm includes a first switching tube and a second switching tube connected in series, the second bridge arm includes a third switching tube and a fourth switching tube connected in series, and the midpoint of the first bridge arm is connected to the midpoint of the second bridge arm through an inductor; wherein, when the input source outputs a voltage and the power conversion circuit is not working, the first switching tube, the second switching tube and the third switching tube are all turned off, and the fourth switching tube is turned on; when the first switching tube, the second switching tube and the third switching tube are all turned off, the fourth switching tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

[0013] Compared with the prior art, this application has at least the following advantages:

[0014] 1. The power conversion device, inverter and photovoltaic power generation system of the present application, when the input source or photovoltaic module outputs voltage and the power conversion circuit is not working, turns off the first switch tube, the second switch tube and the third switch tube, and turns on the fourth switch tube. At the same time, the alarm circuit determines whether there is a wiring error between the input source or photovoltaic module and the power conversion device based on the current direction of the inductor connecting the first bridge arm and the second bridge arm in the power conversion circuit. This can not only reduce the material cost caused by hardware anti-fool and detection circuits, but also reduce problems such as high software complexity caused by software detection.

[0015] 2. The power conversion device, inverter and photovoltaic power generation system of the present application start working only when the alarm circuit does not output a warning signal indicating reverse connection, that is, when the input source or photovoltaic component is correctly connected to the power conversion device and the current direction of the inductor flows from the first bridge arm to the second bridge arm. This can reduce the problem of damage to the power conversion circuit or inverter caused by direct starting when there is a possible wiring error between the input source or photovoltaic component and the power conversion device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the power conversion device of an embodiment of the present application and its connection relationship with the input source or load.

[0017] Figure 2It is a schematic diagram of the structure of the power conversion circuit in the power conversion device of an embodiment of the present application and an application scenario thereof.

[0018] Figure 3 This application Figure 2 A schematic diagram of a signal flow in a power conversion circuit according to an embodiment.

[0019] Figure 4 This application Figure 2 A schematic diagram of another signal flow of the power conversion circuit of an embodiment.

[0020] Figure 5 It is a schematic diagram of the structure of the inverter and its connection relationship with the photovoltaic module according to the embodiment of the present application.

[0021] Figure 6 It is a schematic diagram of the structure and connection relationship of the photovoltaic power generation system of an embodiment of the present application.

[0022] Description of main component symbols:

[0023] 1. Inverter; 2. Input source; 11. Power conversion device; 12. Load; 21. PV module; BUS, DC bus; 100, PV power generation system; 111. Power conversion circuit; 112. Alarm circuit; 121. Inverter circuit; 1121. Acquisition unit; 1121a, first acquisition unit; 1121b, second acquisition unit; 1122, control unit; Q1, first switching tube; Q2, second switching tube; Q3, third switching tube; Q4, fourth switching tube; L, inductor.

[0024] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0025] In the description of the embodiments of this application, words such as "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "or," and "for example" is intended to present the relevant concepts in a concrete manner.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. It should be understood that, unless otherwise specified in this application, " / " means or. For example, A / B can mean A or B. "And / or" in this application is merely a way to describe the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. "At least one" means one or more. "Multiple" means two or more than two. For example, at least one of a, b or c can mean: a, b, c, a and b, a and c, b and c, a, b and c.

[0027] It should also be noted that the terms "first" and "second" in the description, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0028] Buck, Boost, and Buck-Boost power converters are essential transmission devices for many new energy systems. For example, photovoltaic power generation systems can use Buck, Boost, and Buck-Boost power converters to achieve maximum power point tracking. In photovoltaic power generation systems, because Buck and Boost power converters can only step down or step up voltage, or operate in direct-flow mode, when the sunlight on the photovoltaic panels increases or other factors cause the input voltage to rise, the DC bus voltage also increases. This deteriorates the operating environment of the system's equipment, potentially reducing efficiency. Therefore, Buck-Boost power converters are more commonly used than Buck and Boost power converters.

[0029] Due to the wide distribution of energy, a large number of transmission devices such as Buck-Boost power converters are required. In this case, the wiring complexity and error rate are easily increased. Among the related technologies, one is to reduce wiring problems through hardware error prevention, such as setting the shape of the wiring head and the wiring socket to a one-to-one correspondence. Another is to add detection circuits to detect wiring errors, such as using detection circuits to test the current or voltage of each input point before the device is started. Another is to use software to detect wiring errors, such as adding judgment instructions in the software settings.

[0030] However, in the above-mentioned related technologies, hardware anti-fouling and detection circuits are likely to lead to increased material costs when a large amount of wiring is required, and pure software detection is likely to lead to increased software complexity or higher requirements for controllers such as CPUs.

[0031] To this end, the present application provides a power conversion device, inverter, and photovoltaic power generation system with the ability to detect wiring errors. This reduces material costs associated with hardware error prevention and detection circuits, as well as the high software complexity associated with software detection. Several embodiments are described below with reference to the accompanying drawings. The following embodiments and features within these embodiments may be combined unless they conflict.

[0032] Figure 1 It is a schematic diagram of the structure of the power conversion device 11 and its connection relationship with the input source 2 or the load 12 according to an embodiment of the present application. Figure 2 It is a schematic diagram of the structure of the power conversion circuit 111 in the power conversion device 11 of an embodiment of the present application and an application scenario thereof.

[0033] The present application embodiment first provides a power conversion device 11, see Figure 1 The power conversion device 11 may include: a power conversion circuit 111 and an alarm circuit 112 .

[0034] The power conversion circuit 111 may include a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm being connected in series. The first bridge arm is used to connect to an input source 2, and the second bridge arm is used to connect to a load 12. The input source 2 may be a device that converts various forms of energy into electrical energy, such as a photovoltaic module 21. The load 12 may be a circuit that converts direct current (DC) into alternating current (AC), such as an inverter circuit, or the inverter circuit portion of an inverter device, such as a DC bus. Alternatively, the load 12 may be a circuit used for filtering, etc.

[0035] like Figure 2 As shown, the first bridge arm may include a first switching transistor Q1 and a second switching transistor Q2, with the first switching transistor Q1 and the second switching transistor Q2 connected in series. One end of the first switching transistor Q1 is connected to an output terminal of the input source 2, such as the positive output terminal of the photovoltaic module 21, and the other end of the first switching transistor Q1 is connected to one end of the second switching transistor Q2. The other end of the second switching transistor Q2 is connected to another output terminal of the input source 2, such as the negative output terminal of the photovoltaic module 21. Furthermore, the other end of the second switching transistor Q2 is also connected to the second bridge arm.

[0036] like Figure 2As shown, the second bridge arm may include a third switch Q3 and a fourth switch Q4, with the third switch Q3 and the fourth switch Q4 connected in series. One end of the third switch Q3 is connected to an input terminal of the load 12, such as the positive DC bus BUS of the inverter 1, and the other end of the third switch Q3 is connected to one end of the fourth switch Q4. The other end of the fourth switch Q4 is connected to another input terminal of the load 12, such as the negative DC bus BUS of the inverter 1. Furthermore, the other end of the fourth switch Q4 is also connected to the second switch Q2 of the first bridge arm.

[0037] The midpoint of the first bridge arm and the midpoint of the second bridge arm can be connected via an inductor L, that is, the connection point between the first switch tube Q1 and the second switch tube Q2 and the connection point between the third switch tube Q3 and the fourth switch tube Q4 can be connected via the inductor L. The inductor L can be used to store electrical energy and smooth current.

[0038] In some embodiments, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may be semiconductor switches of the same type. For example, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may be metal-oxide semiconductor field-effect transistors (MOS-FETs), also known as MOS transistors.

[0039] In some embodiments, the first bridge arm may be connected in parallel to a first capacitor, which may be used to filter the current of the input source 2. The second bridge arm may be connected in parallel to a second capacitor, which may be used to filter the current after passing through the first bridge arm and the second bridge arm.

[0040] Figure 3 This application Figure 2 A schematic diagram of a signal flow of the power conversion circuit 111 according to an embodiment. Figure 4 This application Figure 2 A schematic diagram of another signal flow of the power conversion circuit 111 according to an embodiment.

[0041] In the embodiment of the present application, if the input source 2 is connected to the power conversion circuit 111, the power conversion circuit 111 is not started, that is, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all turned off. Figure 3 and Figure 4 If the input source 2 is reversely connected to the power conversion circuit 111, the current of the input source 2 will flow back from the positive output terminal to the negative output terminal through the parasitic diodes (also called body diodes) due to the presence of parasitic diodes in the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4.

[0042] The current return path can be path one: positive output terminal - parasitic diode of the second switch Q2 - parasitic diode of the first switch Q1 - negative output terminal. Path two: positive output terminal - parasitic diode of the fourth switch Q4 - inductor L - parasitic diode of the first switch Q1 - negative output terminal.

[0043] Since the sum of the impedances of the parasitic diode of the fourth switch tube Q4 and the inductor L is greater than the impedance of the parasitic diode of the second switch tube Q2, the return path of the current is path 1, that is, Figure 3 In this case, reverse connection of the input source 2 and the power conversion circuit 111 will cause a short circuit and damage the device. Therefore, the connection between the input source 2 and the power conversion circuit 111 needs to be tested, and the test cannot be performed when the input source 2 and the power conversion circuit 111 are short-circuited. Therefore, the current return path needs to be switched to a path with inductor L to perform reverse connection detection.

[0044] As described above, in order to detect whether the input source 2 and the power conversion circuit 111 are reversely connected without a short circuit, and to reduce the material cost caused by the hardware anti-fouling and detection circuit and the high software complexity caused by software detection, the power conversion device 11 of the embodiment of the present application also includes an alarm circuit 112.

[0045] The alarm circuit 112 is used to collect the current of the inductor L and output a warning signal based on the current direction of the inductor L to indicate that the input source 2 is reversely connected.

[0046] As described above, when the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all turned off, the current return path is path 1, so there is no current on the inductor L. In order to collect the current of the inductor L, when the input source 2 outputs a voltage and the power conversion circuit 111 is not working, the first switch Q1, the second switch Q2, and the third switch Q3 can be turned off, and the fourth switch Q4 can be turned on. At this time, please refer to Figure 4 Since the fourth switch Q4 is turned on, the sum of the impedance of the fourth switch Q4 and the inductor L is less than the impedance of the parasitic diode of the second switch Q2. Therefore, the current return path of the input source 2 will switch to the third path: positive output terminal - fourth switch Q4 - inductor L - parasitic diode of the first switch Q1 - negative output terminal, that is, Figure 4 Indicated by the dotted arrow.

[0047] The alarm circuit 112 can detect whether the input source 2 and the power conversion circuit 111 are reversely connected by collecting the current of the inductor L and, based on the current direction of the inductor L, determining whether the input source 2 is reversely connected to the power conversion circuit 111. Specifically, if the first switch Q1, the second switch Q2, and the third switch Q3 are all off, the fourth switch Q4 is on, and the current of the inductor L flows to the first bridge arm, the input source 2 and the power conversion circuit 111 are reversely connected, and the alarm circuit 112 outputs a prompt signal. Thus, the alarm circuit 112 of the embodiment of the present application can detect whether the input source 2 and the power conversion circuit 111 are reversely connected, while reducing the material cost caused by hardware error prevention and detection circuits, as well as the high software complexity caused by software detection.

[0048] In some embodiments, the power conversion circuit 111 starts operating when the first switch Q1, the second switch Q2, and the third switch Q3 are all off, the fourth switch Q4 is on, and the current of the inductor L flows toward the second bridge arm. That is, if the alarm circuit 112 does not output a reverse connection warning signal, the power conversion circuit 111 only starts operating when the input source 2 or the photovoltaic module 21 is correctly connected to the power conversion device 11 and the current of the inductor L flows from the first bridge arm to the second bridge arm. This can reduce the risk of device damage caused by direct startup when the input source 2 and the power conversion circuit 111 are incorrectly connected.

[0049] In some embodiments, as described above Figure 2 As shown, the alarm circuit 112 includes a collection unit 1121. The collection unit 1121 may include a first collection unit 1121a, which is connected between the inductor L and the first bridge arm and is used to collect the current of the inductor L. In some embodiments, the first collection unit 1121a may include but is not limited to a sampling resistor or a Hall current sensor.

[0050] In some embodiments, the alarm circuit 112 further includes a control unit 1122 , which is configured to determine the current direction of the inductor L and output a prompt signal when the first acquisition unit 1121 a determines that the current direction of the inductor L is flowing toward the first bridge arm.

[0051] In some embodiments, the control unit 1122 may include, but is not limited to, a controller such as a digital signal processor (DSP), a microcontroller unit (MCU), or a central processing unit (CPU). When the power conversion device 11 is used in the inverter 1, the control unit 1122 may share the same controller with other circuits of the inverter 1, such as the inverter circuit 121. In this case, the controller can not only control the switching transistors of the inverter circuit 121 and the power conversion circuit 111 to turn on or off, but can also be used to output a reverse connection prompt signal.

[0052] In some embodiments, the acquisition unit 1121 further includes a second acquisition unit 1121 b , which is connected in parallel with the first bridge arm and to the input source 2 , and is configured to acquire the voltage of the first bridge arm.

[0053] In some embodiments, the control unit 1122 is further configured to output a warning signal when the voltage of the first bridge arm detected by the second detection unit 1121b is negative. In this case, the voltage of the first bridge arm can be detected to determine whether the input source 2 and the power conversion circuit 111 are incorrectly connected, thereby improving the accuracy of the alarm circuit 112 in determining whether the input source 2 is reversely connected.

[0054] Figure 5 Schematic diagram of the structure of the inverter 1 and its connection relationship with the photovoltaic module 21 according to an embodiment of the present application.

[0055] The present application also provides an inverter 1, see Figure 5 Inverter 1 may include a power conversion device 11, an inverter circuit 121, and a DC bus BUS. The input end of power conversion device 11 is connected to input source 2, and the output end of power conversion device 11 is connected to inverter circuit 121 via the DC bus BUS. Inverter circuit 121 is used to convert DC power from the DC bus BUS into AC power. Power conversion device 11 is used to increase or decrease the voltage input from input source 2 to the DC bus BUS. Input source 2 can be a device that converts various forms of energy into electrical energy, such as photovoltaic panels 21.

[0056] The power conversion device 11 may be any one of the power conversion devices 11 involved in the above embodiments of the present application.

[0057] Figure 6 Schematic diagram of the structure and connection relationship of the photovoltaic power generation system 100 according to an embodiment of the present application.

[0058] The present application also provides a photovoltaic power generation system 100. Figure 6The photovoltaic power generation system 100 may include a photovoltaic component 21 and an inverter 1 .

[0059] Among them, the photovoltaic module 21 is connected to the inverter 1 and is used to convert solar energy into electrical energy. The inverter 1 is used to perform power conversion and / or AC-DC conversion on the electrical energy generated by the photovoltaic module 21 and input it into the power grid or energy storage battery; the inverter 1 includes a power conversion device 11, an inverter circuit 121 and a DC bus BUS. The input end of the power conversion device 11 is connected to the photovoltaic module 21, and the output end of the power conversion device 11 is connected to the inverter circuit 121 through the DC bus BUS. The inverter circuit 121 is used to convert the DC power of the DC bus BUS into AC power. The power conversion device 11 is used to raise or lower the voltage of the photovoltaic module 21 input to the DC bus BUS.

[0060] The power conversion device 11 may be any one of the power conversion devices 11 involved in the above embodiments of the present application.

[0061] The power conversion device, inverter and photovoltaic power generation system of the present application, when the input source or photovoltaic component outputs voltage and the power conversion circuit is not working, turn off the first switch tube, the second switch tube and the third switch tube, and turn on the fourth switch tube. At the same time, the alarm circuit determines whether there is a wiring error between the input source or photovoltaic component and the power conversion device based on the current direction of the inductor connecting the first bridge arm and the second bridge arm in the power conversion circuit. This can not only reduce the material cost caused by hardware anti-mistake and detection circuits, but also reduce problems such as high software complexity caused by software detection.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A power conversion device, characterized in that: include: A power conversion circuit and an alarm circuit, the power conversion circuit comprising a first bridge arm and a second bridge arm connected in series, the first bridge arm being used to connect to an input source, the second bridge arm being used to connect to a load, the first bridge arm comprising a first switching tube and a second switching tube connected in series, the second bridge arm comprising a third switching tube and a fourth switching tube connected in series, the midpoint of the first bridge arm being connected to the midpoint of the second bridge arm via an inductor; Wherein, when the input source outputs a voltage and the power conversion circuit is not working, the first switch tube, the second switch tube and the third switch tube are all turned off, and the fourth switch tube is turned on; When the first switch tube, the second switch tube, and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

2. The power conversion device according to claim 1, characterized in that: When the first switch tube, the second switch tube, and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows to the second bridge arm, the power conversion circuit starts to operate.

3. The power conversion device according to claim 1, wherein: The alarm circuit includes a first acquisition unit, which is connected between the inductor and the first bridge arm and is used to collect the current of the inductor.

4. The power conversion device according to claim 3, characterized in that: The alarm circuit further includes a control unit, which is configured to determine a current direction of the inductor and output the prompt signal when the current direction of the inductor is flowing toward the first bridge arm.

5. The power conversion device according to claim 4, characterized in that: The alarm circuit further includes a second acquisition unit, which is connected in parallel with the first bridge arm and to the input source, and is used to acquire the voltage of the first bridge arm.

6. The power conversion device according to claim 5, characterized in that: The control unit is further configured to output the prompt signal when the voltage of the first bridge arm acquired by the second acquisition unit is a negative value.

7. An inverter, characterized in that: The power converter comprises a power conversion device, an inverter circuit, and a DC bus. The input end of the power conversion device is connected to an input source, and the output end of the power conversion device is connected to the inverter circuit via the DC bus. The inverter circuit is used to convert the DC power of the DC bus into AC power. The power conversion device is used to increase or decrease the voltage input from the input source to the DC bus. The power conversion device comprises: A power conversion circuit and an alarm circuit, the power conversion circuit comprising a first bridge arm and a second bridge arm connected in series, the first bridge arm being used to connect to an input source, the second bridge arm being used to connect to a load, the first bridge arm comprising a first switching tube and a second switching tube connected in series, the second bridge arm comprising a third switching tube and a fourth switching tube connected in series, the midpoint of the first bridge arm being connected to the midpoint of the second bridge arm via an inductor; Wherein, when the input source outputs a voltage and the power conversion circuit is not working, the first switch tube, the second switch tube and the third switch tube are all turned off, and the fourth switch tube is turned on; When the first switch tube, the second switch tube, and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

8. A photovoltaic power generation system, characterized in that: It includes a photovoltaic module and an inverter; the inverter is used to convert the electric energy generated by the photovoltaic module into power and transmit it to the power grid or energy storage battery; The inverter includes a power conversion device, an inverter circuit, and a DC bus. The input end of the power conversion device is connected to the photovoltaic module source, and the output end of the power conversion device is connected to the inverter circuit through the DC bus. The inverter circuit is used to convert the DC power of the DC bus into AC power. The power conversion device is used to increase or decrease the voltage input from the photovoltaic module to the DC bus. The power conversion device comprises: A power conversion circuit and an alarm circuit, the power conversion circuit comprising a first bridge arm and a second bridge arm connected in series, the first bridge arm being used to connect to an input source, the second bridge arm being used to connect to a load, the first bridge arm comprising a first switching tube and a second switching tube connected in series, the second bridge arm comprising a third switching tube and a fourth switching tube connected in series, the midpoint of the first bridge arm being connected to the midpoint of the second bridge arm via an inductor; Wherein, when the input source outputs a voltage and the power conversion circuit is not working, the first switch tube, the second switch tube and the third switch tube are all turned off, and the fourth switch tube is turned on; When the first switch tube, the second switch tube, and the third switch tube are all turned off, the fourth switch tube is turned on, and the current of the inductor flows from the second bridge arm to the first bridge arm, the alarm circuit outputs a prompt signal for prompting that the input source is reversely connected.

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