Power converter, method, insulation detection equipment, device and medium

Abstract

The invention discloses a power converter, insulation detection equipment, method and device and a medium. The converter comprises a power conversion circuit, an insulation detection circuit and a controller. The insulation detection circuit comprises a detection resistor and a switch which are connected in series; the direct-current positive end of the power conversion circuit is connected with the positive electrode of the corresponding direct-current source, and the direct-current negative end of the power conversion circuit is connected with the negative electrode of the corresponding direct-current source; the power conversion circuit comprises a switching tube and an inductor which are connected in series; the first end of the insulation detection circuit is grounded, and the second end of the insulation detection circuit is connected with the common end of the switch tube and the inductor; the controller obtains the insulation impedance according to the direct current side voltage of the power conversion circuit, the resistance value of the detection resistor and the corresponding voltage to ground before and after the switch is switched off; the voltage to ground is the voltage of the ground to the direct-current negative end or the voltage of the direct-current positive end to the ground, the insulation resistance of the direct-current side of the power converter can be accurately detected, and the operation safety of the power converter is guaranteed.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a power converter, method, insulation testing equipment, device, and medium. Background Technology

[0002] Before a power converter can be put into operation, the insulation resistance to ground on the DC side needs to be tested. For example, if the power converter is used in the photovoltaic or energy storage field, the working environment is relatively harsh. It is usually placed outdoors and affected by weather factors such as dust, rain, snow, and fog. This will cause the insulation resistance to ground of the power converter to change. If the insulation resistance is too low, the leakage current generated will cause electric shock hazard. Therefore, the insulation resistance must be tested. Summary of the Invention

[0003] In view of this, this application provides a power converter, method, insulation testing equipment, apparatus, and medium that can accurately detect the insulation impedance on the DC side of the power converter and ensure the operational safety of the power converter.

[0004] This application provides a power converter, including: a power conversion circuit, an insulation detection circuit, and a controller; the insulation detection circuit includes a detection resistor and a switch connected in series; the DC positive terminal of the power conversion circuit is used to connect to the positive terminal of a corresponding DC source, and the DC negative terminal of the power conversion circuit is used to connect to the negative terminal of a corresponding DC source; the power conversion circuit includes a switch and an inductor connected in series; the first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor; the controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground before and after the switch is opened; wherein, the voltage to ground is the voltage between the ground and the DC negative terminal or the voltage between the DC positive terminal and the ground, and the DC side voltage of the power conversion circuit is the voltage between the DC positive terminal and the DC negative terminal.

[0005] Preferably, the power conversion circuit includes a DC-DC converter circuit, which includes the series-connected switching transistor and inductor.

[0006] Preferably, the DC-DC converter circuit includes a first DC-DC converter circuit and a second DC-DC converter circuit; the input terminal of the first DC-DC converter circuit is connected to a first DC source, the input terminal of the second DC-DC converter circuit is connected to a second DC source, and the output terminals of the first DC-DC converter circuit and the second DC-DC converter circuit are connected in parallel; the first DC-DC converter circuit includes a first inductor and a first switch in series, and the second DC-DC converter circuit includes a second inductor and a second switch in series; the insulation detection circuit further includes a first diode and a second diode; the second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the first inductor and the first switch, and the anode of the second diode is connected to the common terminal of the second inductor and the second switch.

[0007] Preferably, the DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in parallel; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive DC terminal and the negative DC terminal, and the output terminals of the first DC circuit and the second DC circuit are connected in parallel; both the first DC branch and the second DC branch include the series-connected switch and inductor; the second terminal of the insulation detection circuit is connected to the common terminal of the series-connected inductor and switch in the first DC circuit, or connected to the common terminal of the series-connected inductor and switch in the second DC circuit.

[0008] Preferably, the DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit; the first DC-DC conversion circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC conversion circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source, the input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source, and the output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are connected in parallel. The first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include the series-connected switching transistor and inductor; the insulation detection circuit also includes a first diode and a second diode; the second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the series-connected inductor and switching transistor in the first DC circuit, and the anode of the second diode is connected to the common terminal of the series-connected inductor and switching transistor in the third DC circuit, or the anode of the first diode is connected to the common terminal of the series-connected inductor and switching transistor in the second DC circuit, and the anode of the second diode is connected to the common terminal of the series-connected inductor and switching transistor in the fourth DC circuit.

[0009] Preferably, the first DC circuit and the second DC circuit are forward converters or flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0010] Preferably, the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are forward converters, or the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0011] Preferably, the power conversion circuit further includes a DC-AC conversion circuit; the output terminal of the DC-DC conversion circuit is connected to the input terminal of the DC-AC conversion circuit.

[0012] Preferably, the controller is configured to: when the DC-side voltage of the first DC-DC converter circuit is greater than the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the first DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the first diode, and the voltage to ground before and after the switch is opened; when the DC-side voltage of the first DC-DC converter circuit is less than the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the second DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the second diode, and the voltage to ground before and after the switch is opened; and when the DC-side voltage of the first DC-DC converter circuit is equal to the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the second DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the first diode or the second diode, and the voltage to ground before and after the switch is opened.

[0013] Preferably, the controller is specifically used to control all the switching transistors in the power conversion circuit to be disconnected, thereby obtaining the DC side voltage of the power conversion circuit; when the switch is disconnected, the controller obtains the voltage to ground, controls the switch to be closed, and obtains the voltage to ground after the switch is closed.

[0014] This application embodiment also provides an insulation detection method for a power converter. The power converter includes a power conversion circuit and an insulation detection circuit. The insulation detection circuit includes a detection resistor and a switch connected in series. The positive DC terminal of the power conversion circuit is used to connect to the positive terminal of a corresponding DC source, and the negative DC terminal of the power conversion circuit is used to connect to the negative terminal of a corresponding DC source. The power conversion circuit includes a switch and an inductor connected in series. The first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor. The method includes: detecting the DC side voltage of the power conversion circuit, detecting the voltage to ground when the switch is open, and detecting the voltage to ground when the switch is closed; wherein, the voltage to ground is the voltage between the ground and the negative DC terminal or the voltage between the positive DC terminal and the ground, and the DC side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal; the insulation impedance is obtained from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltages to ground before and after the switch is open.

[0015] Preferably, detecting the DC-side voltage of the power conversion circuit, detecting the voltage to ground when the switch is open, and detecting the voltage to ground when the switch is closed specifically includes: controlling all the switching transistors in the power conversion circuit to be open to obtain the DC-side voltage of the power conversion circuit; obtaining the voltage to ground when the switch is open; controlling the switch to be closed to obtain the voltage to ground after the switch is closed.

[0016] Preferably, the method further includes: triggering an alarm when the number of times the insulation impedance is less than a preset impedance exceeds a preset value.

[0017] Preferably, the DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in parallel; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive DC terminal and the negative DC terminal, and the output terminals of the first DC circuit and the second DC circuit are connected in parallel; both the first DC branch and the second DC branch include the series-connected inductor and switch; the second terminal of the insulation detection circuit is connected to the common terminal of the series-connected inductor and switch in the first DC circuit, or connected to the common terminal of the series-connected inductor and switch in the second DC circuit.

[0018] Preferably, the DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit; the first DC-DC conversion circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC conversion circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source, the input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source, and the output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are connected in parallel. The insulation detection circuit further includes a first diode and a second diode; the first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include the series-connected inductor and switch; the second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the series-connected inductor and switch in the first DC circuit, and the anode of the second diode is connected to the common terminal of the series-connected inductor and switch in the third DC circuit, or the anode of the first diode is connected to the common terminal of the series-connected inductor and switch in the second DC circuit, and the anode of the second diode is connected to the common terminal of the series-connected inductor and switch in the fourth DC circuit.

[0019] Preferably, the first DC circuit and the second DC circuit are forward converters or flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0020] Preferably, the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are forward converters, or the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0021] This application embodiment also provides an insulation detection device, including: an insulation detection circuit and a controller; the insulation detection circuit includes a detection resistor and a switch connected in series; a first terminal of the insulation detection circuit is grounded, and a power conversion circuit includes a switch and an inductor connected in series; a second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor; the DC positive terminal of the power conversion circuit is used to connect to the positive terminal of a corresponding DC source, and the DC negative terminal of the power conversion circuit is used to connect to the negative terminal of a corresponding DC source; the controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground before and after the switch is opened; wherein, the voltage to ground is the voltage between the ground and the DC negative terminal or the voltage between the DC positive terminal and the ground, and the DC side voltage of the power conversion circuit is the voltage between the DC positive terminal and the DC negative terminal.

[0022] This application embodiment also provides a control device, including a processor and a memory, wherein the memory is used to store programs, instructions or code, and the processor is used to execute the programs, instructions or code in the memory to complete the insulation detection method for the power converter described above.

[0023] This application also provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the insulation detection method for the power converter described above.

[0024] The power converter provided in this application embodiment is simple and reliable in hardware by adding a detection resistor and a switch. The controller controls the state of the switch, which can disturb the voltage to ground (PE point). The voltage relationship before and after the disturbance can be used to formulate an equation. By solving the equation, the insulation impedance of the DC side of the power converter can be obtained, and the calculation is simple. When the insulation impedance is less than the preset impedance, it indicates that a ground insulation fault has occurred, and an alarm can be triggered in time to avoid more serious accidents. Attached Figure Description

[0025] Figure 1 A schematic diagram of a power converter provided in an embodiment of this application;

[0026] Figure 2 A schematic diagram of yet another power converter provided in the embodiments of this application;

[0027] Figure 3A A schematic diagram of another power converter provided in the embodiments of this application;

[0028] Figure 3B A schematic diagram of yet another power converter provided in the embodiments of this application;

[0029] Figure 4 A schematic diagram showing the connection position of an insulation detection circuit provided in an embodiment of this application;

[0030] Figure 5 for Figure 3A A schematic diagram of the insulation detection equivalent of a power converter;

[0031] Figure 6 for Figure 5 The corresponding equivalent circuit diagram;

[0032] Figure 7A A schematic diagram of another power converter provided in the embodiments of this application;

[0033] Figure 7B A schematic diagram of yet another power converter provided in the embodiments of this application;

[0034] Figure 8 Provided for the embodiments of this application Figure 7A and Figure 7B The corresponding insulation detection circuit diagram;

[0035] Figure 9 Bit Figure 8 The corresponding equivalent circuit diagram;

[0036] Figure 10 A schematic diagram of yet another power converter provided in the embodiments of this application;

[0037] Figure 11This is a schematic diagram of an insulation testing device provided in an embodiment of this application;

[0038] Figure 12 A flowchart illustrating an insulation detection method for a power converter provided in this application embodiment;

[0039] Figure 13 This is a schematic diagram of a control device provided in an embodiment of this application. Detailed Implementation

[0040] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0041] See Figure 1 This figure is a schematic diagram of a power converter provided in an embodiment of this application.

[0042] This application does not specifically limit the DC source connected to the DC side of the power converter to a similar source. For example, it can be a photovoltaic panel, wind power, hydropower, or a battery. For ease of understanding, the following embodiments of this application will use a photovoltaic panel as an example of a DC source.

[0043] The power converter provided in this application includes: a power conversion circuit 1000, an insulation detection circuit, and a controller (not shown in the figure); the insulation detection circuit includes a detection resistor R0 connected in series and a switch S; this application does not specifically limit the specific type of switch S, as long as it is a controllable switch, and the controller can control the closing and opening of switch S. For example, it can be a relay or an IGBT switch.

[0044] The DC positive terminal A of the power conversion circuit 1000 is used to connect to the positive terminal PV+ of the corresponding DC source, and the DC negative terminal B of the power conversion circuit 1000 is used to connect to the negative terminal PV- of the corresponding DC source. It should be understood that the power conversion circuit 1000 may include a DC-AC conversion circuit, a DC-DC conversion circuit, or both. The insulation detection circuit is used to detect the insulation resistance to ground on the DC side of the power conversion circuit 1000, and insulation detection is generally performed when the power conversion circuit 1000 is not powered on.

[0045] The power conversion circuit includes a switch S1 and an inductor T1 connected in series. This application does not specifically limit whether S is connected to the first terminal of the insulation detection circuit or R0 is connected to the first terminal of the insulation detection circuit. Figure 1 In this circuit, the first terminal of switch S1 is connected to the first terminal of the insulation detection circuit, the second terminal of switch S1 is connected to the first terminal of resistor R0, and the second terminal of resistor R0 is connected to the second terminal of the insulation detection circuit. The first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of switch S1 and inductor T1.

[0046] Figure 1 The insulation resistance between PV+ and ground is represented by Rm, and the insulation resistance between ground and PV- is represented by Rn. It should be understood that... Figure 1 Rm and Rn in the diagram are not externally connected impedances, but rather equivalent impedances for ease of understanding.

[0047] The controller controls the state of switch S. Before switch S is open, the sensing resistor R0 is connected to the second terminal; after switch S is open, the sensing resistor R0 is disconnected from the second terminal, thus affecting the magnitude of the PV+ impedance to ground or the magnitude of the ground impedance to PV-. For example, when the second terminal of the insulation detection circuit is connected to point A, and S is closed, R0 is equivalent to being connected in parallel with Rm, affecting the magnitude of the PV+ impedance to ground. The insulation impedance can be obtained by setting up a system of equations.

[0048] The embodiments of this application do not specifically limit the specific implementation of inductor T1. For example, it can be the primary winding of a transformer in an isolated power conversion circuit, or it can be the inductor in a DC-DC conversion circuit in a non-isolated power conversion circuit.

[0049] The DC-side voltage of the power conversion circuit is the voltage between the positive and negative DC terminals, that is, the voltage between PV+ and PV-.

[0050] The controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit (DC side voltage refers to the voltage between PV+ and PV-), the resistance value of the sensing resistor R0, and the voltage to ground before and after the switch S is opened. The voltage to ground is either the voltage between ground and the negative DC terminal or the voltage between the positive DC terminal and ground. The voltage between ground and the negative DC terminal is the voltage between ground and the negative DC terminal when S is closed and the voltage between ground and the negative DC terminal when S is open. Alternatively, the controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the sensing resistor R0, and the voltage between the positive DC terminal and ground before and after the switch S is opened. The insulation impedance is obtained by setting up and solving a system of equations using these parameters.

[0051] It should be understood that the voltage between the positive and negative DC terminals is equal to the sum of the voltage between the positive DC terminal and ground and the voltage between ground and the negative DC terminal. When setting up a system of equations using the relationship between voltage, resistance, and current, either the voltage between ground and the negative DC terminal or the voltage between the positive DC terminal and ground can be used. For ease of understanding, the voltage between ground and the negative DC terminal will be used as an example below.

[0052] The power converter provided in this application embodiment is simple and reliable in hardware, achieved by adding a simple sensing resistor and a switch. The controller controls the state of the switch, thus perturbing the voltage to ground (PE point). The voltage relationship before and after the perturbation can be used to formulate equations, and solving these equations yields the insulation impedance on the DC side of the power converter, making the calculation simple. When the insulation impedance is less than a preset impedance, it indicates a ground insulation fault, allowing for timely alarm and prevention of more serious accidents.

[0053] The following description uses a power converter, including a DC-DC converter circuit and a DC-AC converter, as an example. When the DC-DC converter circuit includes a series-connected switching transistor and an inductor, the second terminal of the insulation detection circuit is connected to the common terminal of the switching transistor and the inductor.

[0054] See Figure 2 This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0055] This application provides an example of a power converter including a DC-DC converter circuit 100 and a DC-AC converter circuit 200. Specifically, it describes an example where an insulation detection circuit is connected in the DC-DC converter circuit 100. The DC-DC converter circuit includes an inductor T1 and a switch S1 connected in series. The first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the inductor T1 and the switch S1. The insulation detection circuit includes a switch S connected in series and a detection resistor R0. Specifically, the first terminal of the switch S is connected to the common terminal, and the second terminal of the switch S is grounded through the detection resistor R0.

[0056] This application does not specifically limit the type of DC-DC converter circuit. For example, it can be a forward converter, flyback converter, Boost converter, Buck converter, or isolated DC-DC converter circuit. When the DC-DC converter circuit is a forward converter or flyback converter, it includes a transformer and a switching transistor; the primary winding of the transformer serves as the inductor in the DC-DC converter circuit. The switching transistor and the primary winding of the transformer are connected in series between the DC positive and DC negative terminals; the second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0057] The following description uses an isolated DC-DC converter circuit as an example. This example uses an isolated DC-DC converter circuit comprising interleaved parallel DC-DC converter circuits. This application does not specifically limit the number of DC-DC converter circuits included in the power converter; it may include one circuit or multiple circuits. When multiple circuits are included, each DC-DC converter circuit is connected to a corresponding photovoltaic panel.

[0058] The following description uses a DC-DC converter circuit, which includes an interleaved parallel first DC circuit and a second DC circuit, as an example. The input terminals of the first and second DC circuits are connected in parallel between the positive and negative DC terminals. The output terminals of the first and second DC circuits are connected in parallel. Both the first and second DC branches include a series-connected switch and an inductor. The second terminal of the insulation detection circuit is connected to the common terminal of the series-connected inductor and switch in the first DC circuit, or to the common terminal of the series-connected inductor and switch in the second DC circuit.

[0059] For ease of understanding, the following description will use the first DC circuit and the second DC circuit as examples to illustrate the first flyback circuit and the second flyback circuit, respectively.

[0060] See Figure 3A This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0061] The power converter provided in this application includes a DC-DC converter circuit 100 and a DC-AC converter circuit 200 as examples. The DC-DC converter circuit 100 includes a first flyback circuit and a second flyback circuit connected in alternating parallel configurations.

[0062] The input terminals of the first flyback circuit and the second flyback circuit are connected in parallel between the positive DC terminal and the negative DC terminal. The output terminals of the first flyback circuit and the second flyback circuit are connected in parallel to the input terminal of the DC-AC converter circuit 200.

[0063] The insulation detection circuit (not shown in the figure) is connected to the first flyback circuit or the second flyback circuit.

[0064] The primary winding of the first transformer T1 in the first flyback circuit is connected in series with the first switch S1. The primary winding of the second transformer T2 in the second flyback circuit is connected in series with the second switch S2. It should be understood that the primary winding of the transformer can be regarded as an inductor, that is, the inductor and the switch are connected in series.

[0065] It should be understood that Figure 3A This only illustrates one implementation of a DC-DC converter circuit. A DC-DC converter circuit can also consist of only one DC circuit; see [link to relevant documentation]. Figure 3B This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0066] from Figure 3B As can be seen, the DC-DC converter circuit 100 only includes one flyback circuit, that is, the flyback circuit includes the first transformer T1 and the first switching transistor S1. For specific connection details, please refer to [reference needed]. Figure 3A The description will not be repeated here.

[0067] for Figure 3AAny flyback circuit can be connected to the insulation detection circuit described above, and to detect the insulation impedance of the DC side of the power converter, it is sufficient to connect the insulation detection circuit to one of the flyback circuits. This application does not specifically limit the location where the insulation detection circuit is connected to the DC-DC converter circuit. The following, in conjunction with the appendix... Figure 4 Three connection positions are introduced.

[0068] See Figure 4 The figure is a schematic diagram of the connection position of an insulation detection circuit provided in an embodiment of this application.

[0069] for Figure 3A The interleaved parallel DC-DC converter circuit shown can have its insulation detection circuit connected to... Figure 4 Point C, as shown, is the common terminal of the primary winding of the series-connected transformer T1 and the switching transistor S1 in the flyback circuit.

[0070] The following is an insulation detection circuit connected to... Figure 4 Taking point C in the diagram as an example, we will provide a detailed explanation. Please refer to [link / reference]. Figure 5 The image is Figure 3A A schematic diagram of the insulation detection equivalent of a power converter.

[0071] The power converter provided in this application embodiment has a switch S and a detection resistor R0 connected in series in the insulation detection circuit and then connected to point C, which is the common terminal of the inductor (primary winding of transformer T1) and the switch S1.

[0072] The following is combined Figure 6 This section describes the specific process for obtaining insulation impedance.

[0073] See Figure 6 The image is Figure 5 The corresponding equivalent circuit diagram.

[0074] When S is disconnected, as follows Figure 6 As shown on the left, R0 is not connected to the circuit. When S is closed, as... Figure 6 As shown on the right, R0 is connected to the circuit.

[0075] Where V1 is the voltage across PV+ and PV-, the voltage across PV- before switch S is closed is V-, and the voltage across PV- after switch S is closed is V+. - Then, according to Kirchhoff's Current Law (KCL), we can obtain the following equation:

[0076]

[0077] Subtracting formula (2) from formula (1) and rearranging, we get:

[0078]

[0079] The insulation resistance of the DC side of the power converter to ground is denoted as Riso. Substituting into formula (3), we can solve it as follows:

[0080]

[0081] Since the resistance value of R0 is known, the voltage above can be measured. Therefore, the DC side insulation impedance of the power converter can be obtained through the above formula (4). The calculation method is simple, and the hardware circuit is also simple. The hardware devices that need to be added only include a resistor and a switch. The cost is low and the reliability is high.

[0082] The above describes the situation of a single photovoltaic panel. The following describes the situation of multiple photovoltaic panels. Each photovoltaic panel corresponds to a DC-DC converter circuit, and the output terminals of multiple DC-DC converter circuits are all connected to the same DC-AC converter circuit.

[0083] The DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit;

[0084] The first DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC converter circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections.

[0085] The input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source. The input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source. The output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are connected in parallel.

[0086] The first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include a series-connected switching transistor and an inductor.

[0087] The insulation detection circuit also includes a first diode and a second diode;

[0088] The second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the inductor and the switch in series in the first DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in series in the third DC circuit, or the anode of the first diode is connected to the common terminal of the inductor and the switch in series in the second DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in series in the fourth DC circuit.

[0089] For ease of understanding, the following description uses the first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit as examples to illustrate the first flyback circuit, the second flyback circuit, the third flyback circuit, and the fourth flyback circuit, respectively.

[0090] See Figure 7A This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0091] The power converter provided in this application embodiment includes a first DC-DC converter circuit and a second DC-DC converter circuit. The input terminal of the first DC-DC converter circuit is connected to a first photovoltaic panel PV1, and the input terminal of the second DC-DC converter circuit is connected to a second photovoltaic panel PV2.

[0092] The first DC-DC converter circuit includes an interleaved first flyback circuit and a second flyback circuit connected in parallel; the first flyback circuit includes a first transformer T1 and a switching transistor S1, and the second flyback circuit includes a second transformer T2 and a switching transistor S2.

[0093] The second DC-DC converter circuit includes a third flyback circuit and a fourth flyback circuit connected in interleaved parallel. The third flyback circuit includes a third transformer T3 and a switching transistor S3, and the fourth flyback circuit includes a fourth transformer T4 and a switching transistor S4.

[0094] The output terminals of the first flyback circuit, the second flyback circuit, the third flyback circuit, and the fourth flyback circuit are connected in parallel to the input terminal of the DC-AC converter circuit 200.

[0095] PV+ and PV- represent the positive and negative electrodes of the photovoltaic panel, respectively.

[0096] When the power converter includes multiple DC-DC converter circuits, only one sense resistor and switch need to be connected. However, each DC-DC converter circuit needs to be connected to a diode. The purpose of connecting the diode is to construct a "virtual bus" of insulation resistance so that in an isolated inverter that drives multiple DC-DC converter circuits in one inverter circuit, insulation detection on the DC side can be performed when any one circuit is powered on.

[0097] The power converter and controller provided in this application embodiment are used to obtain the insulation impedance from the DC-side voltage of the power conversion circuit, the resistance value of the detection resistor, the forward voltage drop of the first diode, and the voltage between ground and the negative DC terminal before and after the switch is turned off. The insulation impedance detection method in a multi-channel DC-DC conversion circuit scenario is described in detail below with reference to the accompanying drawings.

[0098] The above Figure 7AThis introduction only uses the DC power supply of the two-channel DC-DC converter circuit as an interleaved flyback circuit. It should be understood that the two-channel DC-DC converter circuit can be a DC circuit of any topology, such as a non-isolated DC circuit like Boost or Buck, or an isolated DC circuit like a flyback circuit or a forward circuit. The technical solution provided in the embodiments of this application can be used to check the insulation resistance in all of them.

[0099] See Figure 7B This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0100] The power converter provided in this application embodiment includes a DC-DC converter circuit comprising a first DC-DC converter circuit and a second DC-DC converter circuit. The input terminal of the first DC-DC converter circuit is connected to a first DC source PV1, and the input terminal of the second DC-DC converter circuit is connected to a second DC source PV2. The output terminals of the first and second DC-DC converter circuits are connected in parallel, for example, connected together to a DC-AC converter circuit 200. The first DC-DC converter circuit includes a first inductor and a first switch connected in series, and the second DC-DC converter circuit includes a second inductor and a second switch connected in series. The insulation detection circuit further includes a first diode and a second diode. The second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode. The anode of the first diode is connected to the common terminal of the first inductor and the first switch, and the anode of the second diode is connected to the common terminal of the second inductor and the second switch.

[0101] Since both the first and second DC-DC converter circuits include inductors and switching transistors connected in series, the following can be used: Figure 8 Insulation testing is performed using this method.

[0102] See Figure 8 This figure is provided as an embodiment of this application. Figure 7A and Figure 7B The corresponding equivalent circuit diagram for insulation testing.

[0103] In addition to the detection resistor R0 and the switch S, the insulation detection circuit provided in this application embodiment also includes a first diode D1 and a second diode D2.

[0104] The first end of the series connection between the sensing resistor R0 and the switch S is grounded. The second end of the series connection between the sensing resistor R0 and the switch S is connected to the cathode of the first diode D1. The anode of the first diode D1 is connected to the common terminal of the primary winding T1 (represented here by the designation T1 of the first transformer) and the switch S1 in the first flyback circuit. The second end of the series connection between the sensing resistor R0 and the switch S is connected to the cathode of the second diode D2. The anode of the second diode D2 is connected to the common terminal of the primary winding T1 (represented here by the designation T2 of the first transformer) and the switch S3 in the third flyback circuit.

[0105] Figure 8 In the diagram, R1m represents the impedance of the positive electrode PV1+ of the first photovoltaic panel to the ground PE, and R2m represents the impedance of the positive electrode PV2+ of the second photovoltaic panel to the ground PE.

[0106] The resistance of R0 is known. D1 and D2 are used to construct the virtual busbar on the primary side. S is a disturbance switch added for insulation detection.

[0107] The power converter provided in this application embodiment utilizes D1 and D2 to construct a virtual bus on the DC side. By turning switch S on or off, a relationship can be established between R0, R1m, and R2m to obtain a set of related equations. Solving these equations yields the insulation impedance on the DC side. See the following formula for details:

[0108] When S is open and closed Figure 8 The equivalent circuit is as follows Figure 9 As shown, V1 is the voltage across PV1+ and PV-, V2 is the voltage across PV2+ and PV-, the voltage across PE before S is closed is V-, and the voltage across PE after S is closed is V+. - ′, V F Let V1 be the forward voltage drop of the diode, and assuming V1 is greater than V2 (and vice versa), according to Kirchhoff's law, we can obtain the following equation:

[0109]

[0110] Using (5)-(6), we can rearrange to obtain:

[0111]

[0112] The machine's impedance to PE is Riso. Substituting into formula (7), we can solve it as follows:

[0113]

[0114] As can be seen from the above formula (8), the insulation impedance can be obtained by solving the equation using the suppression parameter and the measured voltage.

[0115] It should be understood that the above calculations are based on V1 being greater than V2. Specifically, the controller is used to obtain the insulation impedance based on the DC side voltage of the first DC-DC converter circuit, the resistance value of the sensing resistor, the forward voltage drop of the first diode, and the voltage between ground and the negative DC terminal before and after the switch is opened when the DC side voltage of the first DC-DC converter circuit is greater than that of the second DC-DC converter circuit. When the DC side voltage of the first DC-DC converter circuit is less than that of the second DC-DC converter circuit, the controller obtains the insulation impedance based on the DC side voltage of the second DC-DC converter circuit, the resistance value of the sensing resistor, the forward voltage drop of the second diode, and the voltage between ground and the negative DC terminal before and after the switch is opened. It should also be understood that when the DC side voltage of the first DC-DC converter circuit is equal to that of the second DC-DC converter circuit, the controller obtains the insulation impedance based on the DC side voltage of the second DC-DC converter circuit, the resistance value of the sensing resistor, the forward voltage drop of the first or second diode, and the voltage to ground before and after the switch is opened. That is, when V1 is less than V2, V2 is used, and the voltage drop of D2 is applied; when V1 is equal to V2, either V1 or V2 can be used. If V1 is used, the voltage drop of D1 is applied; if V2 is used, the voltage drop of D2 is applied.

[0116] The power converter provided in this application does not operate when obtaining the DC-side insulation impedance. Therefore, the controller, specifically used to control all switches in the power conversion circuit to be disconnected, does not need to control the switches in the power conversion circuit to cooperate in detecting the insulation impedance, thus reducing control complexity. The controller obtains the DC-side voltage of the power conversion circuit; when the switch is open, it obtains the voltage between ground and the negative DC terminal, controls the switch to close, and obtains the voltage between ground and the negative DC terminal after the switch is closed. Moreover, when multiple DC-DC conversion circuits are included, insulation impedance detection can be completed as long as one photovoltaic panel is energized, without requiring each photovoltaic panel to be energized. Furthermore, when multiple DC sources are included, there are no requirements on the voltage magnitude between the multiple DC sources; two voltages can be equal, one voltage can be large, one voltage can be small, or one voltage can be zero. The insulation impedance acquisition scheme of this application is based on fewer parameters. The fewer parameters, the less sampling error introduced by each parameter, thereby improving the accuracy of the final insulation impedance. Moreover, there is no short circuit between PV+ and PV- in the power converter provided in this application embodiment, thus preventing the power converter from exploding.

[0117] The power converter and controller provided in this application embodiment are also used to issue an alarm when the number of times the insulation impedance is less than the preset impedance exceeds a preset value, so as to perform timely maintenance and avoid insulation faults from causing other serious accidents.

[0118] The power converters described in the above embodiments are all based on isolated DC-DC converter circuits. It should be understood that the insulation impedance detection scheme provided in this application embodiment is also applicable to non-isolated DC-DC converter circuits. For example, when the DC-DC converter circuit is a Boost circuit, and the power converter circuit includes a series-connected switch and an inductor, the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor. For ease of understanding, the specific implementation method is illustrated below with reference to the accompanying drawings.

[0119] See Figure 10 This figure is a schematic diagram of another power converter provided in an embodiment of this application.

[0120] The power converter provided in this application includes a DC-DC converter circuit and a DC-AC converter circuit. The DC-DC converter circuit is described using a Boost circuit as an example. The Boost circuit is a mature circuit architecture. Figure 10 This explanation uses a basic Boost circuit as an example. A Boost circuit consists of an inductor L, a switch Q1, and a diode D. The positive input of the Boost circuit is connected to PV+, and the negative input is connected to PV-. The first end of inductor L is connected to PV+, the second end of inductor L is connected to the anode of diode D, and the second end of inductor L is connected to PV- via the switch Q1.

[0121] It should be understood that the second terminal of the insulation detection circuit provided in the embodiments of this application can be connected between the second terminal of the inductor L and ground.

[0122] Figure 10 Taking the example of connecting the second terminal of the insulation detection circuit between the second terminal of L and ground, the specific principle can be found in [reference needed]. Figure 5 and Figure 6 The insulation impedance is obtained by using formula (4), and the details will not be elaborated here.

[0123] Based on the power converter provided in the above embodiments, this application also provides an insulation detection device, which will be described in detail below with reference to the accompanying drawings. It should be understood that the insulation detection device can exist independently of the power converter. When the power converter uses the insulation detection device to perform DC-side insulation detection, the power converter can be directly connected to the insulation detection device.

[0124] See Figure 11 The figure is a schematic diagram of an insulation testing device provided in an embodiment of this application.

[0125] The insulation testing device provided in this application includes: an insulation testing circuit 600 and a controller 500; the insulation testing circuit 600 includes a detection resistor R0 and a switch S connected in series.

[0126] The first terminal of the insulation detection circuit 600 is grounded. When the power conversion circuit includes a series-connected switch and an inductor, the second terminal of the insulation detection circuit 600 is connected to the common terminal of the switch and the inductor.

[0127] The DC positive terminal of the power conversion circuit is used to connect to the positive terminal of the corresponding photovoltaic panel, and the DC negative terminal of the power conversion circuit is used to connect to the negative terminal of the corresponding photovoltaic panel.

[0128] The controller 500 is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground before and after the switch is opened; wherein, the voltage to ground is the voltage between ground and the negative DC terminal or the voltage between the positive DC terminal and ground, and the DC side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal.

[0129] The controller 500 can be selected from the controller in the power converter, or a separate controller can be set up. This application embodiment does not specifically limit it.

[0130] The insulation testing device provided in this application includes a controller, a detection resistor, and a switch. The hardware is simple and reliable. The controller controls the state of the switch, which can disturb the voltage at the PE point. The voltage relationship before and after the disturbance can be used to formulate an equation. By solving the equation, the insulation impedance of the DC side of the power converter can be obtained. The calculation is simple.

[0131] Based on the power converter and insulation testing device provided in the above embodiments, this application also provides an insulation testing method for a power converter, which will be described in detail below with reference to the accompanying drawings.

[0132] See Figure 12 The figure is a flowchart of an insulation detection method for a power converter provided in an embodiment of this application.

[0133] The insulation detection method for a power converter provided in this application embodiment includes a power conversion circuit, an insulation detection circuit, and a controller. The insulation detection circuit includes a detection resistor and a switch connected in series. The power conversion circuit also includes a switch and an inductor connected in series. The positive DC terminal of the power conversion circuit is used to connect to the positive terminal of the corresponding photovoltaic panel, and the negative DC terminal of the power conversion circuit is used to connect to the negative terminal of the corresponding photovoltaic panel. The first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor.

[0134] The method includes:

[0135] S1301: Detect the DC side voltage of the power conversion circuit, detect the voltage to ground when the switch is open, and detect the voltage to ground when the switch is closed; wherein, the voltage to ground is the voltage between ground and the negative DC terminal or the voltage between the positive DC terminal and ground, and the DC side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal.

[0136] S1302: The insulation impedance is obtained from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the corresponding voltage to ground before and after the switch is opened.

[0137] It should be understood that the voltage between the positive and negative DC terminals is equal to the sum of the voltage between the positive DC terminal and ground and the voltage between ground and the negative DC terminal. When setting up a system of equations using the relationship between voltage, resistance, and current, either the voltage between ground and the negative DC terminal or the voltage between the positive DC terminal and ground can be used. For ease of understanding, the voltage between ground and the negative DC terminal will be used as an example below.

[0138] The insulation detection method for power converters provided in this application involves adding a simple detection resistor and a switch. The hardware is simple and reliable. The controller manages the switch's state, thus perturbing the voltage to ground (PE point). The voltage relationship before and after the perturbation allows for the formulation of equations. Solving these equations yields the insulation impedance on the DC side of the power converter, making the calculation simple. When the insulation impedance is less than a preset impedance, it indicates a ground insulation fault, triggering a timely alarm and preventing more serious accidents.

[0139] One possible implementation involves detecting the DC-side voltage of the power conversion circuit, detecting the voltage to ground when the switch is open, and detecting the voltage to ground when the switch is closed. Specifically, this includes: controlling all the switching transistors in the power conversion circuit to be open to obtain the DC-side voltage of the power conversion circuit; obtaining the voltage to ground when the switch is open; controlling the switch to be closed to obtain the voltage to ground after the switch is closed.

[0140] One possible implementation method also includes: triggering an alarm when the number of times the insulation impedance is less than a preset impedance exceeds a preset value.

[0141] The embodiments of this application do not specifically limit the specific topology of the power conversion circuit. Please refer to the description of the above embodiments of the power converter. It will not be repeated here, but only a few are listed as examples.

[0142] One possible implementation is that the DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in parallel; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals, and the output terminals of the first DC circuit and the second DC circuit are connected in parallel; both the first DC branch and the second DC branch include an inductor and a switch connected in series; the second terminal of the insulation detection circuit is connected to the common terminal of the inductor and the switch connected in series in the first DC circuit, or connected to the common terminal of the inductor and the switch connected in series in the second DC circuit.

[0143] One possible implementation includes a DC-DC converter circuit comprising a first DC-DC converter circuit and a second DC-DC converter circuit; the first DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC converter circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections; the input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source, and the input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source; the output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit... The output terminals are connected in parallel; the insulation detection circuit also includes a first diode and a second diode; the first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include an inductor and a switching transistor connected in series; the second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the inductor and the switching transistor connected in series in the first DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switching transistor connected in series in the third DC circuit, or the anode of the first diode is connected to the common terminal of the inductor and the switching transistor connected in series in the second DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switching transistor connected in series in the fourth DC circuit.

[0144] One possible implementation is that the first DC circuit and the second DC circuit are forward circuits, or the first DC circuit and the second DC circuit are flyback circuits. The forward circuit or flyback circuit includes the primary winding of a transformer and a switching transistor connected in series. The primary winding is an inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive and negative DC terminals. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0145] One possible implementation is that the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are forward circuits, or the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are flyback circuits. The forward circuit or flyback circuit includes the primary winding of a transformer and a switching transistor connected in series. The primary winding is an inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive and negative DC terminals. The second terminal of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

[0146] In one possible implementation, see Figure 13 The figure is a schematic diagram of a control device provided in an embodiment of this application.

[0147] The control device may include a memory 1011 and a processor 1012. The processor 1012 may be connected to the power converter and can drive the switches in the various power conversion circuits of the power converter. For example... Figure 13 As shown, the memory can be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, etc.

[0148] The memory 1011 can store computer instructions. When the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be used to execute the insulation detection method of the power converter. The memory 1011 can also store data, such as the resistance value of the detection resistor involved in the above embodiment.

[0149] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).

[0150] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.

[0151] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Regarding the methods disclosed in the embodiments, since they correspond to the product embodiments disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the description of the product embodiments.

[0152] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power converter, characterized in that, include: The circuit includes a power conversion circuit, an insulation detection circuit, and a controller; the insulation detection circuit comprises a detection resistor and a switch connected in series. The positive DC terminal of the power conversion circuit is used to connect to the positive terminal of the corresponding DC source, and the negative DC terminal of the power conversion circuit is used to connect to the negative terminal of the corresponding DC source; the power conversion circuit includes a series-connected switching transistor and an inductor. The first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the switching transistor and the inductor. The controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground corresponding to the switch before and after it is turned off; wherein, the voltage to ground is the voltage between the ground and the negative DC terminal or the voltage between the positive DC terminal and the ground, and the DC side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal.

2. The power converter according to claim 1, characterized in that, The power conversion circuit includes a DC-DC converter circuit, which includes the series-connected switching transistor and inductor.

3. The power converter according to claim 2, characterized in that, The DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit; The input terminal of the first DC-DC converter is connected to the first DC source, the input terminal of the second DC-DC converter is connected to the second DC source, and the output terminals of the first DC-DC converter and the second DC-DC converter are connected in parallel. The first DC-DC converter circuit includes a first inductor and a first switch connected in series, and the second DC-DC converter circuit includes a second inductor and a second switch connected in series. The insulation detection circuit also includes a first diode and a second diode; The second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the first inductor and the first switch, and the anode of the second diode is connected to the common terminal of the second inductor and the second switch.

4. The power converter according to claim 2, characterized in that, The DC-DC conversion circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections. The input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive DC terminal and the negative DC terminal, and the output terminals of the first DC circuit and the second DC circuit are connected in parallel; both the first DC branch and the second DC branch include the series-connected switching transistor and inductor. The second terminal of the insulation detection circuit is connected to the common terminal of the inductor and the switch in series in the first DC circuit, or to the common terminal of the inductor and the switch in series in the second DC circuit.

5. The power converter according to claim 2, characterized in that, The DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit; The first DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC converter circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections. The input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source. The input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source. The output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are connected in parallel. The first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include the series-connected switching transistor and inductor; The insulation detection circuit also includes a first diode and a second diode; The second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the inductor and the switch in the first DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in the third DC circuit, or the anode of the first diode is connected to the common terminal of the inductor and the switch in the second DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in the fourth DC circuit.

6. The power converter according to claim 4, characterized in that, The first DC circuit and the second DC circuit are forward converters, or the first DC circuit and the second DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second end of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

7. The power converter according to claim 5, characterized in that, The first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are forward converters, or the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second end of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

8. The power converter according to any one of claims 2-5, characterized in that, The power conversion circuit also includes a DC-AC conversion circuit; The output terminal of the DC-DC converter circuit is connected to the input terminal of the DC-AC converter circuit.

9. The power converter according to claim 5, characterized in that, The controller is configured to: when the DC-side voltage of the first DC-DC converter circuit is greater than the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the first DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the first diode, and the voltage to ground before and after the switch is opened; when the DC-side voltage of the first DC-DC converter circuit is less than the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the second DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the second diode, and the voltage to ground before and after the switch is opened; and when the DC-side voltage of the first DC-DC converter circuit is equal to the DC-side voltage of the second DC-DC converter circuit, obtain the insulation impedance based on the DC-side voltage of the second DC-DC converter circuit, the resistance value of the detection resistor, the forward voltage drop of the first diode or the second diode, and the voltage to ground before and after the switch is opened.

10. The power converter according to any one of claims 1-8, characterized in that, The controller is specifically used to control all the switches in the power conversion circuit to be turned off, thereby obtaining the DC side voltage of the power conversion circuit; when the switches are turned off, the controller obtains the voltage to ground, controls the switches to be closed, and obtains the voltage to ground after the switches are closed.

11. An insulation detection method for a power converter, characterized in that, The power converter includes a power conversion circuit and an insulation detection circuit; the insulation detection circuit includes a detection resistor and a switch connected in series; the positive DC terminal of the power conversion circuit is used to connect to the positive terminal of the corresponding DC source, and the negative DC terminal of the power conversion circuit is used to connect to the negative terminal of the corresponding DC source; the power conversion circuit includes a switch and an inductor connected in series, the first terminal of the insulation detection circuit is grounded, and the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor; The method includes: The DC-side voltage of the power conversion circuit is detected, as are the voltage to ground when the switch is open and the voltage to ground when the switch is closed; wherein, the voltage to ground is the voltage between the ground and the negative DC terminal or the voltage between the positive DC terminal and the ground, and the DC-side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal; The insulation impedance is obtained from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground before and after the switch is turned off.

12. The method according to claim 10, characterized in that, Detecting the DC-side voltage of the power conversion circuit, detecting the voltage to ground when the switch is open, and detecting the voltage to ground when the switch is closed, specifically includes: The switching transistors in the power conversion circuit are all turned off to obtain the DC side voltage of the power conversion circuit; when the switch is turned off, the voltage to ground is obtained; the switch is then controlled to close to obtain the voltage to ground after the switch is closed.

13. The method according to claim 10, characterized in that, Also includes: An alarm is triggered when the number of times the insulation resistance is less than the preset impedance exceeds a preset value.

14. The method according to claim 10, characterized in that, The DC-DC conversion circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections. The input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive DC terminal and the negative DC terminal, and the output terminals of the first DC circuit and the second DC circuit are connected in parallel. Both the first DC branch and the second DC branch include the series-connected inductor and switching transistor; The second terminal of the insulation detection circuit is connected to the common terminal of the inductor and the switch in series in the first DC circuit, or to the common terminal of the inductor and the switch in series in the second DC circuit.

15. The method according to claim 13, characterized in that, The DC-DC conversion circuit includes a first DC-DC conversion circuit and a second DC-DC conversion circuit; The first DC-DC converter circuit includes a first DC circuit and a second DC circuit connected in alternating parallel connections; the second DC-DC converter circuit includes a third DC circuit and a fourth DC circuit connected in alternating parallel connections. The input terminals of the first DC circuit and the second DC circuit are connected in parallel between the positive and negative DC terminals of the first DC source. The input terminals of the third DC circuit and the fourth DC circuit are connected in parallel between the positive and negative DC terminals of the second DC source. The output terminals of the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are connected in parallel. The insulation detection circuit also includes a first diode and a second diode; The first DC branch, the second DC circuit, the third DC circuit, and the fourth DC circuit all include the series-connected inductor and switching transistor; The second terminal of the insulation detection circuit is connected to the cathode of the first diode and the cathode of the second diode; the anode of the first diode is connected to the common terminal of the inductor and the switch in the first DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in the third DC circuit, or the anode of the first diode is connected to the common terminal of the inductor and the switch in the second DC circuit, and the anode of the second diode is connected to the common terminal of the inductor and the switch in the fourth DC circuit.

16. The method according to claim 13, characterized in that, The first DC circuit and the second DC circuit are forward converters, or the first DC circuit and the second DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second end of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

17. The method according to claim 15, characterized in that, The first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are forward converters, or the first DC circuit, the second DC circuit, the third DC circuit, and the fourth DC circuit are flyback converters. The forward converter or flyback converter includes the primary winding of a transformer connected in series and the switching transistor. The primary winding is the inductor. The switching transistor and the primary winding of the transformer are connected in series between the positive DC terminal and the negative DC terminal. The second end of the insulation detection circuit is connected to the common terminal of the primary winding and the switching transistor.

18. An insulation testing device, characterized in that, include: An insulation detection circuit and a controller; the insulation detection circuit includes a detection resistor and a switch connected in series; The first terminal of the insulation detection circuit is grounded, and the power conversion circuit includes a switch and an inductor connected in series; the second terminal of the insulation detection circuit is connected to the common terminal of the switch and the inductor. The positive DC terminal of the power conversion circuit is used to connect to the positive terminal of the corresponding DC source, and the negative DC terminal of the power conversion circuit is used to connect to the negative terminal of the corresponding DC source. The controller is used to obtain the insulation impedance from the DC side voltage of the power conversion circuit, the resistance value of the detection resistor, and the voltage to ground corresponding to the switch before and after it is turned off; wherein, the voltage to ground is the voltage between the ground and the negative DC terminal or the voltage between the positive DC terminal and the ground, and the DC side voltage of the power conversion circuit is the voltage between the positive DC terminal and the negative DC terminal.

19. A control device, characterized in that, It includes a processor and a memory, the memory being used to store programs, instructions, or code, and the processor being used to execute the programs, instructions, or code in the memory to perform the insulation detection method for the power converter as described in any one of claims 11-17.

20. A computer-readable storage medium, characterized in that, The device contains a computer program that is loaded by a processor to execute the insulation detection method for the power converter as described in any one of claims 11-17.

Images