Pids and iso circuits and control methods, apparatuses, media, and systems

Abstract

The application discloses a PID and ISO circuit and a control method, device, medium and system thereof, and relates to the technical field of power electronics. The PID and ISO circuit is characterized in that the output end of a PID power supply is connected to the input end of a voltage transmission module, the first output end of the voltage transmission module is connected to each phase of the alternating current side of a power converter through a voltage introduction module, and the second output end of the voltage transmission module is connected to each phase of the alternating current side of the power converter through a detection resistance module. In the case of switching from the PID mode to the ISO mode, the function of transmitting voltage to each phase of the alternating current side of the power converter by means of the circuit can be used to adjust the voltage between the neutral point of the alternating current side of the power converter and the ground, so that the speed of stabilization is accelerated, the waiting time between the anti-PID effect and the ISO function is shortened, and the reliability of safe operation of the system is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a PID and ISO circuit and its control method, device, medium, and power conversion system. Background Technology

[0002] In the application of power converters, the system may need to implement both anti-PID (Potential Induced Degradation) and ISO (Insulation Resistance Monitoring) effects. Using separate devices to implement these two functions not only increases costs but also leads to mutual interference between the two functions. For example, anti-PID operation can create a ground loop, making ISO monitoring impossible. While time-division multiplexing of the PID power supply to achieve these two functions separately can reduce costs, it requires a long waiting time after anti-PID operation before ISO monitoring can resume. During this extended waiting time, if an insulation abnormality occurs, timely protection cannot be provided, affecting the safe operation of the system. Summary of the Invention

[0003] In view of the above problems, this application provides a PID and ISO circuit and its control method, device, medium, and system to shorten the waiting time between the inverse PID effect and ISO functions, and improve the reliability of the system's safe operation. The specific solution is as follows:

[0004] The first aspect of this application provides a PID and ISO circuit, comprising: a PID power supply, a voltage transmission module, a voltage introduction module, and a sensing resistor module; wherein,

[0005] The output terminal of the PID power supply is connected to the input terminal of the voltage transmission module;

[0006] The first output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter through the voltage introduction module;

[0007] The second output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter through the detection resistor module;

[0008] The voltage transmission module is used to: generate a first voltage through the first output terminal in PID mode, and transmit the first voltage to each phase of the AC side of the power converter through the voltage introduction module to achieve the function of anti-PID effect; when switching from PID mode to ISO mode, generate a second voltage through the first output terminal and transmit the second voltage to each phase of the AC side of the power converter through the voltage introduction module, or generate a third voltage through the second output terminal and transmit the third voltage to each phase of the AC side of the power converter through the sensing resistor module to adjust the neutral point-to-ground voltage of the AC side of the power converter to a preset value; and generate a fourth voltage through the second output terminal and transmit the fourth voltage to each phase of the AC side of the power converter through the sensing resistor module to achieve the ISO function.

[0009] In one possible implementation, the preset value is zero.

[0010] In one possible implementation, the second voltage is in the opposite direction to the first voltage.

[0011] In one possible implementation, the voltage transmission module includes: five switches; wherein,

[0012] The first switch is connected between the positive output terminal of the PID power supply and the positive input terminal of the voltage introduction module;

[0013] The second switch is connected between the negative terminal of the PID power supply output and ground.

[0014] The third switch is connected between the positive terminal of the PID power supply output and ground.

[0015] The fourth switch is connected between the negative output terminal of the PID power supply and the negative input terminal of the voltage introduction module;

[0016] One end of the fifth switch is connected to the positive or negative output terminal of the PID power supply, and the other end of the fifth switch is connected to each phase of the AC side of the power converter through the detection resistor module.

[0017] When the first switch and the second switch are closed, the voltage at the first output terminal is positive; when the third switch and the fourth switch are closed, the voltage at the first output terminal is negative.

[0018] In ISO mode, the fifth switch and the switch used to ground the other pole of the PID power supply are in the closed state.

[0019] In one possible implementation, the voltage transmission module further includes: a sixth switch;

[0020] One end of the fifth switch is connected to the positive output terminal of the PID power supply;

[0021] One end of the sixth switch is connected to the negative terminal of the PID power supply output;

[0022] The other end of the fifth switch is connected to the other end of the sixth switch, and the connection point is connected to each phase of the AC side of the power converter through the detection resistor module;

[0023] In ISO mode, the fifth switch and the second switch are in a closed state, or the sixth switch and the third switch are in a closed state.

[0024] In one possible implementation, corresponding anti-reverse diodes are also provided in each transmission path between the input terminal of the voltage transmission module and the first output terminal;

[0025] And / or, corresponding anti-reverse diodes are also provided in the transmission path between the input terminal of the voltage transmission module and the second output terminal;

[0026] The conduction direction of each anti-reverse diode is the direction in which the PID power supply outputs voltage through the corresponding switch.

[0027] In one possible implementation, the third voltage is the preset value.

[0028] In one possible implementation, the voltage introduction module includes: capacitors and phase transmission bridge arms;

[0029] The transmission bridge arm includes two diodes connected in series. The connection point of the two diodes in series serves as the midpoint of the transmission bridge arm for that phase, and is used to connect the corresponding phase on the AC side of the power converter.

[0030] The capacitor is connected in parallel with each phase transmission bridge arm. The positive terminal of the parallel connection is connected to the positive input terminal of the voltage introduction module, and the negative terminal of the parallel connection is connected to the negative input terminal of the voltage introduction module.

[0031] In one possible implementation, the detection resistor module includes: detection resistors for each phase;

[0032] One end of each of the detection resistors is connected, and the connection point is used to connect to the second output terminal;

[0033] The other end of each of the detection circuits is connected to the corresponding phase on the AC side of the power converter.

[0034] A second aspect of this application provides a control method for PID and ISO circuits, comprising:

[0035] In PID mode, the PID power supply in the PID and ISO circuits transmits voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module in sequence, thereby realizing the function of anti-PID effect.

[0036] When switching from PID mode to ISO mode, the PID power supply is controlled to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the voltage introduction module, or the PID power supply is controlled to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the detection resistor module in the PID and ISO circuits, thereby adjusting the AC side neutral point to ground voltage of the power converter to a preset value.

[0037] After the voltage to ground at the neutral point on the AC side stabilizes, switch to ISO mode.

[0038] In one possible implementation, the preset value is zero.

[0039] In one possible implementation, controlling the PID power supply to sequentially transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module includes:

[0040] The voltage transmission module is controlled to transmit the output voltage of the PID power supply in the opposite direction to that in PID mode, and the voltage is transmitted to each phase of the AC side of the power converter through the voltage introduction module.

[0041] In one possible implementation, controlling the PID power supply to sequentially transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the sensing resistor module in the PID and ISO circuits includes:

[0042] The detection resistor module is grounded through the voltage transmission module and the PID power supply;

[0043] Alternatively, the output voltage of the PID power supply can be controlled to the preset value and transmitted to the detection resistor module through the voltage transmission module.

[0044] In one possible implementation, the following is also included before switching to ISO mode:

[0045] Sample the AC side neutral point to ground voltage of the power converter.

[0046] In one possible implementation, after switching to ISO mode, the following is also included:

[0047] The output voltage of the PID power supply is transmitted to each phase of the AC side of the power converter through the detection resistor module, and the neutral point to ground voltage of the AC side of the power converter is sampled again after the output voltage of the PID power supply stabilizes.

[0048] The ground insulation impedance of the system containing the power converter is calculated based on the two sampling results.

[0049] In one possible implementation, after switching to ISO mode, the following is also included:

[0050] The voltage transmission module is controlled to transmit the output voltage of the PID power supply twice, and transmit it to each phase of the AC side of the power converter through the detection resistor module respectively; the absolute values ​​of the output voltage of the PID power supply are different in the two transmissions, and / or the transmission directions of the output voltage of the PID power supply by the voltage transmission module are opposite.

[0051] Each time the output voltage of the PID power supply stabilizes, the AC side neutral point to ground voltage of the power converter is sampled.

[0052] The ground insulation impedance of the system containing the power converter is calculated based on the two sampling results.

[0053] In one possible implementation, before the PID and ISO circuits switch from PID mode to ISO mode, the following is also included:

[0054] In PID mode, the PID power supply is controlled to transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module in sequence, thereby realizing the function of anti-PID effect.

[0055] A third aspect of this application provides a power conversion system, comprising: at least one power converter, and PID and ISO circuits as described in the first aspect or any implementation thereof; wherein,

[0056] When the number of power converters is 1, the AC side of the power converter is grounded through the PID and ISO circuits; the controller in the power converter controls the PID and ISO circuits to work by executing the control method of the PID and ISO circuits as described in the second aspect or any implementation thereof.

[0057] When the number of power converters is greater than 1, the AC sides of each power converter are connected in parallel, and the connection point is grounded through the PID and ISO circuits; the controller in any of the power converters, or the main controller that is communicatively connected to each of the controllers, controls the operation of the PID and ISO circuits by executing the control method.

[0058] In one possible implementation, when the number of power converters is 1, the PID and ISO circuits are independent of the power converter, or the PID and ISO circuits are integrated inside the power converter.

[0059] The fourth aspect of this application provides a control device for PID and ISO circuits, 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 perform the control method for PID and ISO circuits as described in the second aspect or any implementation thereof.

[0060] The fifth aspect of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute a control method for PID and ISO circuits as described in the second aspect or any implementation thereof.

[0061] Using the above technical solution, the PID and ISO circuits provided in this application have their PID power supply output terminal connected to the input terminal of a voltage transmission module. The first output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter via a voltage introduction module. In PID mode, the voltage transmission module generates a first voltage at its first output terminal and transmits this first voltage to each phase of the AC side of the power converter via the voltage introduction module, thus achieving the function of anti-PID effect. The second output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter via a sensing resistor module. In ISO mode, the voltage transmission module generates a fourth voltage at its second output terminal and transmits this fourth voltage to each phase of the AC side of the power converter via the sensing resistor module, thus achieving the ISO function. Furthermore, when switching from PID mode to ISO mode, the voltage transmission module can generate a second voltage at its first output terminal and transmit this second voltage to each phase of the AC side of the power converter through the voltage introduction module. Alternatively, the voltage transmission module can generate a third voltage at its second output terminal and transmit this third voltage to each phase of the AC side of the power converter through the sensing resistor module, thereby adjusting the neutral point-to-ground voltage of the power converter to a preset value. In other words, the PID power supply can perform the anti-PID effect through the voltage transmission module and the voltage introduction module, or the PID power supply can transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the sensing resistor module to adjust the neutral point-to-ground voltage of the power converter, thereby accelerating its stabilization speed, shortening the waiting time between the anti-PID effect and ISO functions, and improving the reliability of the system's safe operation. Attached Figure Description

[0062] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0063] Figure 1 A schematic diagram showing the structure of the PID and ISO circuits and their connection relationship with the power converter provided in the embodiments of this application;

[0064] Figure 2 A schematic diagram showing the connection relationship of the PID and ISO circuits in the power conversion system provided in the embodiments of this application;

[0065] Figure 3 A schematic diagram of a voltage transmission module in a PID and ISO circuit provided in an embodiment of this application;

[0066] Figure 4 Another structural schematic diagram of the voltage transmission module in the PID and ISO circuits provided in the embodiments of this application;

[0067] Figure 5 Another structural schematic diagram of the voltage transmission module in the PID and ISO circuits provided in the embodiments of this application;

[0068] Figure 6 A circuit diagram of the PID and ISO circuits provided in the embodiments of this application;

[0069] Figure 7 A flowchart of a control method for PID and ISO circuits provided in an embodiment of this application;

[0070] Figure 8 A specific flowchart of a control method for PID and ISO circuits provided in an embodiment of this application;

[0071] Figure 9 Another specific flowchart of the control method for PID and ISO circuits provided in the embodiments of this application;

[0072] Figure 10 This is a schematic diagram of the power converter provided in the embodiments of this application;

[0073] Figure 11 This is a schematic diagram of the control device provided in an embodiment of this application. Detailed Implementation

[0074] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0075] The embodiments of this application are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Those skilled in the art will understand that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0076] The terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0077] The anti-PID effect primarily raises the negative-to-ground voltage of the DC side of the system where the power converter is located, or lowers the positive-to-ground voltage of the DC side of the system. The ISO function, on the other hand, uses the change in the voltage relative to ground at the neutral point N of the grid before and after the ISO power supply is activated to calculate the system's impedance to ground. Time-sharing multiplexing of the PID power supply means: in PID mode, the power converter uses a PID power supply to perform the anti-PID effect; and in ISO mode, the power converter uses a PID power supply instead of an ISO power supply to implement the ISO function. Furthermore, by alternating the anti-PID effect and ISO function in the system, the existence of a ground loop caused by anti-PID operation, which would prevent the system from performing ISO, can be avoided, and the setup cost of the ISO power supply can also be saved.

[0078] However, in the field of photovoltaic power generation applications, when the power converter used as an inverter switches from PID mode to ISO mode, after the PID power supply is disconnected from the system, the distributed capacitance of the photovoltaic panels to ground causes the system ground voltage to take a certain amount of time to stabilize. If the system ground voltage is sampled and used to calculate the system ground impedance when the system ground voltage is not stable, it will lead to inaccurate calculation of the system ground impedance, false alarm of insulation fault, and affect the normal operation of the system.

[0079] To address the aforementioned issues, when the power converter switches from PID mode to ISO mode, a waiting time can be set after the PID power supply is turned off. This waiting time is typically on the order of minutes to hours, allowing the system voltage to stabilize before sampling the system voltage to ground. While this solution can resolve the issue of false insulation fault alarms, the required waiting time varies depending on the size of the distributed capacitance to ground at different sites. To prevent false insulation fault alarms, the waiting time between mode switches should generally be set to the longest possible duration. However, within a long waiting time, if an insulation abnormality occurs in the system, timely protection cannot be provided, affecting the safe operation of the system.

[0080] Therefore, this application provides a PID and ISO circuit to shorten the waiting time between the inverse PID effect and the ISO function, and to improve the reliability of the system's safe operation. The specific solution is as follows:

[0081] like Figure 1 As shown, the PID and ISO circuit 11 includes: a PID power supply 101, a voltage transmission module 102, a voltage introduction module 103, and a sensing resistor module 104; wherein:

[0082] The output terminal of the PID power supply 101 is connected to the input terminal of the voltage transmission module 102, so that the voltage transmission module 102 can transmit the output voltage of the PID power supply 101.

[0083] The first output terminal of the voltage transmission module 102 is connected to each phase of the AC side of the power converter 10 through the voltage introduction module 103; Figure 1 In this context, CPID_P is the positive input terminal of the voltage introduction module 103, and CPID_N is the negative input terminal of the voltage introduction module 103. Specifically, the voltage transmission module 102 can include multiple transmission paths. After receiving the output voltage of the PID power supply 101, the voltage transmission module 102 can transmit the output voltage of the PID power supply 101 through the corresponding transmission path, so that its first output terminal can output the corresponding voltage to the voltage introduction module 103; then the voltage introduction module 103 transmits it to each phase of the AC side of the power converter 10, thereby entering PID mode, that is, transmitting it from the AC side of the power converter 10 to its DC side, realizing the raising or lowering of the corresponding DC side voltage to ground.

[0084] The second output terminal of the voltage transmission module 102 is connected to each phase of the AC side of the power converter 10 through the sensing resistor module 104. Specifically, after receiving the output voltage of the PID power supply 101, the voltage transmission module 102 can transmit the output voltage of the PID power supply 101 through the corresponding transmission path, so that its second output terminal can output the corresponding voltage to the sensing resistor module 104; and then the sensing resistor module 104 transmits it to each phase of the AC side of the power converter 10, thereby providing the power supply voltage required in ISO mode.

[0085] The PID mode is performed when the power converter 10 is running, and the ISO can be performed whether the power converter 10 is running or not.

[0086] In practical applications, the system in which the power converter 10 is located, such as a photovoltaic inverter system or a photovoltaic-storage inverter system, may include one or at least two power converters 10. For example... Figure 2 As shown, when the number of power converters 10 is greater than one, the AC sides of each power converter 10 are connected in parallel, thereby enabling the PID mode to achieve an inverse PID effect for each photovoltaic module connected to the DC side of the system. The system-to-ground impedance calculated by the ISO mode refers to the system's insulation impedance to ground, including the DC-side impedance to ground and the AC-side impedance to ground. The photovoltaic modules connected to the DC side of the system can refer to... Figure 1 The photovoltaic modules between the positive electrode PV+ and the negative electrode PV- of the photovoltaic string shown in the diagram can also refer to... Figure 2 The photovoltaic modules in each photovoltaic string shown refer to the photovoltaic modules between the positive terminal PV1+ and the negative terminal PV1- of the first photovoltaic string, ..., and the photovoltaic modules between the positive terminal PVn+ and the negative terminal PVn- of the nth photovoltaic string. The total DC power supply connected to the DC side of the system can refer to all photovoltaic modules connected in the photovoltaic inverter system, or it can refer to all photovoltaic modules and battery packs connected in the photovoltaic-storage inverter system. The power converter 10 connected to the photovoltaic string can function as an inverter, and the power converter 10 connected to the battery pack can function as a converter. Additionally, Figure 1 In the middle, R + It is the impedance to ground of the positive terminal of the photovoltaic string, C + R is the distributed capacitance present at the positive terminal of the photovoltaic string. - It is the impedance to ground of the negative terminal of the photovoltaic string, C - It is the distributed capacitance present at the negative terminal of the photovoltaic string; Figure 2 In this structure, the positive and negative terminals of each photovoltaic string have parallel connections to ground impedance and distributed capacitance, respectively. For example, the positive terminal PV1+ of the first photovoltaic string has a ground impedance R. +1 and distributed capacitance C +1 The negative terminal PV1- of the first photovoltaic string has a ground impedance R. -1and distributed capacitance C -1 The positive terminal PVn+ of the nth photovoltaic string has a ground impedance R. +n and distributed capacitance C +n The negative terminal PVn- of the nth photovoltaic string has a ground impedance R. -n and distributed capacitance C -n The presence of these distributed capacitances causes the system voltage to ground to change slowly when switching from PID mode to ISO mode, thus preventing it from entering ISO mode in a timely manner.

[0087] To address this issue, this embodiment employs the aforementioned architecture, and the voltage transmission module 102 is configured to perform various functions, such as:

[0088] In PID mode, the voltage transmission module 102 can generate a first voltage through its first output terminal and transmit the first voltage to each phase of the AC side of the power converter 10 through the voltage introduction module 103, thereby realizing the function of anti-PID effect. In practical applications, the first voltage can be a positive DC voltage, which increases the voltage of each phase of the AC side of the power converter 10 on the original basis, thereby raising the negative DC-side voltage to ground of the system; or, the first voltage can be a negative DC voltage, which decreases the voltage of each phase of the AC side of the power converter 10 on the original basis, thereby reducing the positive DC-side voltage to ground of the system. It depends on the specific application environment. For example, it can be set according to the equipment type of the photovoltaic module connected to the DC side of the power converter 10. There is no limitation here, and all are within the protection scope of this application.

[0089] Furthermore, in ISO mode, the voltage transmission module 102 can generate a fourth voltage through its second output terminal and transmit the fourth voltage to each phase of the AC side of the power converter 10 through the detection resistor module 104 to realize the ISO function. In practical applications, realizing the ISO function requires two different power supply voltages, specifically, the absolute values ​​of the two voltages can be different and / or their directions can be different. The case where the absolute values ​​are different can include the two voltages having different values ​​based on the fact that neither of them is zero, or one of them being zero and the other being non-zero. That is, the fourth voltage can include two different voltages that are both non-zero, and by combining the voltage sampling results under these two voltages to solve a system of equations, the magnitude of the system impedance to ground can be calculated. Alternatively, the fourth voltage can also include only one non-zero voltage, and by combining the voltage sampling results of the voltage transmission module 102 when there is no voltage at the second output terminal to solve a system of equations, the magnitude of the system impedance to ground can be calculated. It depends on the specific application environment, and all of them are within the protection scope of this application.

[0090] Additionally, when switching from PID mode to ISO mode, the voltage transmission module 102 can also generate a second voltage through its first output terminal and transmit the second voltage to each phase of the AC side of the power converter 10 through the voltage introduction module 103, thereby neutralizing the AC side of the power converter 10 (e.g., ...). Figure 1 The voltage to ground at point N (as shown in the diagram) is adjusted to a preset value. Unlike the waiting settings during mode switching in traditional solutions, this embodiment utilizes the PID mode to introduce voltage to each phase of the AC side of the power converter 10. When switching from PID mode to ISO mode, it actively intervenes in the change of the neutral point to ground voltage on the AC side of the power converter 10, which can shorten the waiting time in traditional solutions.

[0091] Alternatively, when switching from PID mode to ISO mode, the voltage transmission module 102 can also generate a third voltage through its second output terminal and transmit the third voltage to each phase of the AC side of the power converter 10 through the sensing resistor module 104, thereby adjusting the AC neutral point voltage to ground of the power converter 10 to a preset value. Although the function of introducing voltage to each phase of the AC side of the power converter 10 using ISO mode requires transmission through the sensing resistor module 104, which may cause the time for adjusting the AC neutral point voltage to ground to the preset value to be longer than the solution using PID mode described above in this embodiment, compared with the waiting setting during mode switching in the traditional solution, this solution can also actively intervene in the change of the AC neutral point voltage to ground, that is, it can also shorten the waiting time in the traditional solution.

[0092] The PID and ISO circuit 11 provided in this embodiment, when switching from PID mode to ISO mode, adjusts the neutral point-to-ground voltage of the AC side of the power converter 10 by means of its function of transmitting voltage to each phase of the AC side of the power converter, thereby accelerating its stabilization speed, shortening the waiting time between the anti-PID effect and ISO functions, and improving the reliability of the system's safe operation.

[0093] In practical applications, when switching from PID mode to ISO mode, the AC side neutral point to ground voltage of the power converter 10 is adjusted to a preset value by using the PID function or ISO function in order to stabilize the AC side neutral point to ground voltage of the power converter 10 as soon as possible.

[0094] In one example, before entering ISO mode, a voltage sample can be taken when the AC side neutral point to ground voltage is stable at zero to obtain the AC side neutral point to ground voltage V1 when there is no voltage at the second output terminal of the voltage transmission module 102; after entering ISO mode, the output voltage of the control PID power supply 101 is transmitted to each phase of the AC side of the power converter 10 through the voltage transmission module 102 and the detection resistor module 104 in sequence, and a voltage sample is taken to obtain the AC side neutral point to ground voltage V2 when the fourth voltage is not zero; then, by solving the system of equations based on the two sampling results, the magnitude of the system impedance to ground can be calculated.

[0095] Therefore, in this example, the preset value can be set to zero; of course, the preset value can also be a small value near zero, as long as the AC side neutral point to ground voltage tends to be stable and a stable AC side neutral point to ground voltage V1 can be obtained.

[0096] In practical applications, the neutral point voltage to ground on the AC side can be adjusted to zero by setting the second voltage to be opposite in direction to the first voltage. For example, in PID mode, the first voltage is a positive DC voltage. When switching from PID mode to ISO mode, the second voltage can be set to a negative DC voltage, and the absolute values ​​of the second voltage and the first voltage can be equal or unequal. Alternatively, in PID mode, the first voltage is a negative DC voltage. When switching from PID mode to ISO mode, the second voltage can be set to a positive DC voltage, and the absolute values ​​of the second voltage and the first voltage can be equal or unequal.

[0097] The specific working principle is as follows: When switching from PID mode to ISO mode, the ability of PID mode to raise the DC side negative terminal to ground voltage or lower the DC side positive terminal to ground voltage of the system is used to control the AC side neutral point to ground voltage of power converter 10 to 0V; then, the fluctuation of the AC side neutral point to ground voltage of power converter 10 is judged by a threshold. When the fluctuation is less than the corresponding threshold, the AC side neutral point to ground voltage V1 is sampled at this time; then, ISO mode is entered, PID power supply 101 is turned on, and a non-zero fourth voltage is output to the detection resistor module 104 through the second output terminal of voltage transmission module 102; after the output voltage of PID power supply 101 stabilizes, the AC side neutral point to ground voltage V2 is sampled at this time; finally, the system impedance to ground is calculated using the two AC side neutral point to ground voltages V1 and V2.

[0098] When the fourth voltage includes two different voltages that are both non-zero, the specific principle is similar, except that the two AC side neutral point voltages V1 and V2 are obtained by sampling after changing the voltage of the second output terminal of the voltage transmission module 102, which will not be described in detail here.

[0099] This embodiment utilizes the PID mode to introduce voltage to each phase of the AC side of the power converter 10, actively adjusting the AC side neutral point to ground voltage of the power converter 10. It eliminates the need to set the waiting time according to the longest time limit due to different distributed capacitances, thus shortening the stabilization time of the AC side neutral point to ground voltage of the power converter 10. This also shortens the waiting time in the traditional solution, enabling the system to quickly enter ISO mode.

[0100] Based on the above embodiments, this embodiment provides an exemplary description of the specific circuit structure of the PID and ISO circuit 11, for example:

[0101] Its voltage transmission module 102 may include Figure 3 or Figure 4 (All are in) Figure 2 As shown in the example (based on which example is presented): five switches K1 to K5; specifically:

[0102] like Figure 3 or Figure 4 As shown, the first switch K1 is connected between the positive output terminal of the PID power supply 101 and the positive input terminal CPID_P of the voltage introduction module 103; the second switch K2 is connected between the negative output terminal of the PID power supply 101 and ground (PE as shown in the figure); the third switch K3 is connected between the positive output terminal of the PID power supply 101 and ground; and the fourth switch K4 is connected between the negative output terminal of the PID power supply 101 and the negative input terminal CPID_N of the voltage introduction module 103.

[0103] Specifically, when the first switch K1 and the second switch K2 operate in combination and are both closed, a transmission path is provided for the output voltage of the PID power supply 101, resulting in a positive DC voltage at the first output terminal of the voltage transmission module 102. This means the output voltage of the PID power supply 101 is directly output, specifically a positive value for the first or second voltage mentioned above. When the third switch K3 and the fourth switch K4 operate in combination and are both closed, another transmission path is provided for the output voltage of the PID power supply 101, resulting in a negative DC voltage at the first output terminal of the voltage transmission module 102. This means the output voltage of the PID power supply 101 is output in reverse, specifically a negative value for the first or second voltage mentioned above. In other words, the end of the first switch K1 furthest from the PID power supply 101 and the end of the fourth switch K4 furthest from the PID power supply 101 together constitute the first output terminal of the voltage transmission module 102; while the ends of the second switch K2 and the third switch K3 furthest from the PID power supply 101 are both grounded.

[0104] One end of the fifth switch K5 is connected to the positive output terminal of the PID power supply 101 (e.g., Figure 3 (as shown) or the negative terminal of the output (such as Figure 4 (as shown in the diagram) are connected together, and the other end of the fifth switch K5 is connected to each phase of the AC side of the power converter 10 through the detection resistor module 104; that is, the end of the fifth switch K5 away from the PID power supply 101 serves as the second output terminal of the voltage transmission module 102.

[0105] for Figure 3 In the structure shown, when the second switch K2 and the fifth switch K5 operate in combination and are both closed, a positive DC voltage can be output to each phase of the AC side of the power converter 10 through the detection resistor module 104; for Figure 4 In the structure shown, when the third switch K3 and the fifth switch K5 operate in combination and are both closed, a negative DC voltage can be output to each phase of the AC side of the power converter 10 through the detection resistor module 104. That is, in ISO mode, the fifth switch K5 is closed, and the other terminal of the PID power supply 101 is used for grounding (e.g., a switch...). Figure 3 The second switch K2 or Figure 4 The third switch (K3) in the module is also closed, thus providing a transmission path for the corresponding voltage to the second output terminal of the voltage transmission module 102.

[0106] In practical applications, two transmission paths can also be provided for the second output terminal of the voltage transmission module 102, such as... Figure 5 As shown, with Figure 3 or Figure 4 The difference is that the voltage transmission module 102 also includes: a sixth switch K6; one end of the fifth switch K5 is connected to the positive output terminal of the PID power supply 101; one end of the sixth switch K6 is connected to the negative output terminal of the PID power supply 101; and the other end of the fifth switch K5 and the other end of the sixth switch K6 are connected, and the connection point serves as the second output terminal of the voltage transmission module 102, which is connected to each phase of the AC side of the power converter 10 through the detection resistor module 104.

[0107] Figure 5 In the structure shown, in ISO mode, when the second switch K2 and the fifth switch K5 operate in combination and are both closed, a positive DC voltage transmission path is provided to the second output terminal of the voltage transmission module 102, making the third or fourth voltage positive. Positive DC voltage can be output to each phase of the AC side of the power converter 10 through the detection resistor module 104. When the third switch K3 and the sixth switch K6 operate in combination and are both closed, a negative DC voltage transmission path is provided to the second output terminal of the voltage transmission module 102, making the third or fourth voltage negative. Negative DC voltage can be output to each phase of the AC side of the power converter 10 through the detection resistor module 104.

[0108] In addition, each transmission path in the voltage transmission module 102 can be equipped with a corresponding anti-reverse diode, such as... Figure 3 or Figure 5 The diodes D1 to D3 shown, or Figure 4 The diodes D1 and D2 shown are examples. Specifically, corresponding anti-reverse diodes (such as those shown) can be installed in the branches of each switch connected to the positive terminal of the PID power supply 101 output. Figures 3 to 5 As shown in the diagram, corresponding anti-reverse diodes (not shown) can also be installed in the branches of each switch connected to the negative terminal of the PID power supply 101 output terminal, and corresponding anti-reverse diodes (not shown) can also be installed in the branches of each switch connected to the positive and negative terminals of the PID power supply 101 output terminal. The conduction direction of each anti-reverse diode is the same as the current flow direction in its transmission path, that is, the direction in which the PID power supply 101 outputs voltage through the corresponding switch, which can prevent the AC side of the power converter 10 from backflowing current into the PID power supply 101. In practical applications, corresponding anti-reverse diodes can also be installed only in each transmission path between the input terminal and the first output terminal of the voltage transmission module 102, such as... Figures 3 to 5 The diodes D1 and D2 shown are used; however, no corresponding anti-reverse diodes are provided in the transmission path between the input terminal and the second output terminal of the voltage transmission module 102, which can be omitted. Figure 3 or Figure 5 Diode D3 in the middle.

[0109] This embodiment is merely an exemplary description of the optional structure of the voltage transmission module 102 and is not intended to limit its implementation. As long as different voltages can be generated through its first output terminal to adjust the AC side neutral point to ground voltage when switching from PID mode to ISO mode and shorten the stabilization time of the AC side neutral point to ground voltage, other implementations are also within the protection scope of this application.

[0110] When switching from PID mode to ISO mode, if a third voltage is generated through the second output terminal of the voltage transmission module 102 and transmitted to each phase of the AC side of the power converter 10 through the detection resistor module 104, so as to adjust the AC side neutral point to ground voltage of the power converter 10 to a preset value, then the third voltage can specifically be the preset value described in the above embodiment.

[0111] In one example, this third voltage can be zero. Specifically, it can be controlled... Figure 4 The second switch K2 and the fifth switch K5 are in the closed state, or the control Figure 5The second switch K2 and the sixth switch K6 are closed to ground the second output terminal of the voltage transmission module 102, making the third voltage zero. Alternatively, a transmission path between the input terminal and the second output terminal of the voltage transmission module 102 can be controlled to be open, for example, by controlling... Figure 3 The second switch K2 and the fifth switch K5 are in the closed state, or control Figure 4 The third switch K3 and the fifth switch K5 are in the closed state, or control Figure 5 The second switch K2 and the fifth switch K5 are in the closed state, or the control... Figure 5 The third switch K3 and the sixth switch K6 are in the closed state to transmit the output voltage of the PID power supply 101 to the second output terminal of the voltage transmission module 102, so that the second output terminal of the voltage transmission module 102 generates a third voltage; and control the output voltage of the PID power supply 101 to 0V, thereby making the third voltage zero.

[0112] This embodiment achieves active adjustment of the AC neutral point to ground voltage of the power converter 10 by adjusting the voltage at the end of the sensing resistor module 104 furthest from the AC side of the power converter to zero. Similarly, it does not require setting the waiting time according to the longest time due to different distributed capacitances, which can shorten the stabilization time of the AC neutral point to ground voltage of the power converter 10, that is, shorten the waiting time in the traditional solution, so that the system can quickly enter ISO mode.

[0113] In practical applications, the third voltage can be a small value near zero, as long as the AC side neutral point to ground voltage tends to be stable and a stable AC side neutral point to ground voltage V1 can be obtained, all of which are within the protection scope of this application.

[0114] Based on the above embodiments, the voltage introduction module 103 in the PID and ISO circuit 11 can be adopted... Figure 6 (in order to be in) Figure 5 (Based on the structure shown, the example shown) has the following form, which specifically includes: capacitor C and each phase transmission bridge arm; wherein, each transmission bridge arm includes two diodes connected in series, and the connection point of the two diodes in series serves as the midpoint of the phase transmission bridge arm, used to connect the corresponding phase on the AC side of the power converter 10; the capacitor C is connected in parallel with each phase transmission bridge arm, and the positive terminal of the parallel connection is connected to the positive input terminal CPID_P of the voltage introduction module 103, and the negative terminal of the parallel connection is connected to the negative input terminal CPID_N of the voltage introduction module 103.

[0115] When the first output terminal of the voltage transmission module 102 generates a positive DC voltage, the positive terminal CPID_P of the input terminal of the voltage introduction module 103 is energized, which can be transmitted through the upper bridge arm diodes (such as...) in each transmission bridge arm. Figure 6 The voltage input module 103 shown in the diagram (with three diodes located on the lower side) outputs positive DC voltage to each phase of the AC side of the power converter 10, thereby increasing the voltage of each phase of the AC side of the power converter 10 on top of its original value. When the first output terminal of the voltage transmission module 102 generates a negative DC voltage, the negative terminal CPID_N of the input terminal of the voltage input module 103 is energized, which can be transmitted through the lower bridge arm diodes (such as...) in each transmission bridge arm. Figure 6 The three diodes located on the upper side of the voltage introduction module 103 shown in the figure output negative DC voltage to each phase of the AC side of the power converter 10, thereby reducing the voltage of each phase of the AC side of the power converter 10 on the original basis.

[0116] Alternatively, the sensing resistor module 104 in the PID and ISO circuit 11 can also be used Figure 6 The form shown specifically includes: the detection resistors of each phase; such as Figure 6 As shown, one end of each sensing resistor is connected, and the connection point GRID_N1 serves as the input terminal of the sensing resistor module 104, that is, the end of the sensing resistor module 104 away from the AC side of the power converter, which is used to connect to the second output terminal of the voltage transmission module 102; the other end of each sensing resistor is connected to the corresponding phase of the AC side of the power converter 10.

[0117] When the second output terminal of the voltage transmission module 102 generates a positive DC voltage, this positive DC voltage can be superimposed on each phase of the AC side of the power converter 10 through each detection resistor, thereby increasing the voltage of each phase of the AC side of the power converter 10 on top of its original value. When the second output terminal of the voltage transmission module 102 generates a negative DC voltage, this negative DC voltage can be superimposed on each phase of the AC side of the power converter 10 through each detection resistor, thereby decreasing the voltage of each phase of the AC side of the power converter 10 on top of its original value.

[0118] This embodiment is merely an exemplary description of the optional structure of the voltage introduction module 103 and the detection resistor module 104, and is not intended to limit the implementation of either; any implementation that can achieve the above-mentioned corresponding functions is within the protection scope of this application.

[0119] Another embodiment of this application provides a control method for PID and ISO circuits. The specific structure and working principle of the PID and ISO circuits can be found in the above embodiments, and will not be repeated here.

[0120] The control method is as follows: Figure 7 As shown, it includes:

[0121] S101. In PID mode, the PID power supply in the PID and ISO control circuits transmits voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module in sequence, thereby realizing the function of anti-PID effect.

[0122] When the PID and ISO circuits switch from PID mode to ISO mode, S102 is executed.

[0123] S102. Control the PID power supply to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the voltage introduction module, or control the PID power supply to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the detection resistor module, so as to adjust the neutral point to ground voltage of the AC side of the power converter to a preset value.

[0124] As shown in the above embodiments, the preset value can be zero or a small value, as long as it can characterize that the voltage between the neutral point and ground on the AC side is basically stable and meets the calculation requirements of ISO, both of which are within the protection scope of this application.

[0125] In practical applications, in S102, the control PID power supply transmits voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the voltage introduction module. Specifically, it can include: controlling the voltage transmission module to transmit the output voltage of the PID power supply in the opposite direction to that in PID mode, and transmitting it to each phase of the AC side of the power converter through the voltage introduction module.

[0126] As described in the above embodiments, if the voltage transmission module directly transmits the output voltage of the PID power supply in PID mode, then the voltage transmission module can transmit the output voltage of the PID power supply in reverse during mode switching; if the voltage transmission module transmits the output voltage of the PID power supply in reverse during PID mode, then the voltage transmission module can directly transmit the output voltage of the PID power supply during mode switching; thus, without changing the output voltage of the PID power supply, the voltage transmission module can quickly adjust the AC side neutral point to ground voltage to zero, which can shorten the waiting time when switching modes in traditional schemes, simplify the control strategy, and is easy to implement.

[0127] As described in the above embodiment, in S102, controlling the PID power supply to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the detection resistor module may include: controlling the detection resistor module to be grounded through the voltage transmission module and the PID power supply; for example, controlling Figure 4 The fifth switch K5 or Figure 5The sixth switch K6 is in the closed state, causing the input terminal of the detection resistor module to be connected to the negative terminal of the PID power supply through the voltage transmission module, and then controlling... Figure 4 and Figure 5 The second switch K2 is closed, grounding the negative terminal of the PID power supply and consequently grounding the input terminal of the sensing resistor module. Alternatively, in S102, controlling the PID power supply to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the sensing resistor module may also include: controlling the output voltage of the PID power supply to a preset value and transmitting it to the sensing resistor module through the voltage transmission module; as described in the above embodiments, controlling a transmission path between the input terminal and the second output terminal of the voltage transmission module to be open, and controlling the output voltage of the PID power supply to a preset value, thereby pulling down the input terminal voltage of the sensing resistor module.

[0128] After adjusting the AC side neutral point-to-ground voltage of the power converter to a preset value, the PID mode can be turned off, and after the AC side neutral point-to-ground voltage stabilizes, S103 is executed. After turning off the PID mode, if the fluctuation of the AC side neutral point-to-ground voltage is still greater than the corresponding threshold, a preset time T1 can be waited before making another judgment, until the fluctuation of the AC side neutral point-to-ground voltage is less than or equal to the threshold, indicating that the AC side neutral point-to-ground voltage has stabilized, and S103 can be executed. Due to the adjustment action of the AC side neutral point-to-ground voltage in S102, the preset time T1 will be much shorter than the waiting time in the traditional solution.

[0129] S103, Switch to ISO mode.

[0130] As described in the above embodiments, the control method can be as follows: Figure 8 As shown, S201 is executed before switching to ISO mode, and S202 and S203 are executed sequentially after switching to ISO mode.

[0131] S201, sampling power converter AC side neutral point to ground voltage V1.

[0132] S202. The output voltage of the PID power supply is transmitted to each phase of the AC side of the power converter through the detection resistor module in the PID and ISO circuits. After the output voltage of the PID power supply stabilizes, the neutral point to ground voltage V2 of the AC side of the power converter is sampled again.

[0133] S203. Calculate the ground insulation impedance of the system where the power converter is located based on the two sampling results.

[0134] Alternatively, the control method can also be as follows: Figure 9 As shown, after switching to ISO mode, S301 to S305 are executed sequentially.

[0135] S301, the control voltage transmission module transmits the output voltage of the PID power supply once, and transmits it to each phase of the AC side of the power converter through the detection resistor module in the PID and ISO circuits.

[0136] S302. After the output voltage of the PID power supply stabilizes, sample the AC side neutral point to ground voltage V1 of the power converter.

[0137] S303, the control voltage transmission module transmits the output voltage of the PID power supply again, and transmits it to each phase of the AC side of the power converter through the detection resistor module.

[0138] S304. After the output voltage of the PID power supply stabilizes, sample the AC side neutral point to ground voltage V2 of the power converter.

[0139] In practical applications, the two transmissions of the PID power supply output voltage in S301 and S303 can be performed by reversing the transmission direction of the voltage transmission module to the PID power supply output voltage without changing the PID power supply output voltage itself. That is, in S301, the voltage transmission module is controlled to perform one transmission of the PID power supply output voltage in any direction, and in S303, the voltage transmission module is controlled to change the transmission direction of the PID power supply output voltage before transmitting it again (e.g., ...). Figure 9 (as shown in the diagram); or, in these two transmissions, the transmission directions may be the same, but the absolute values ​​of the output voltage of the PID power supply may be different; or, in these two transmissions, the absolute values ​​of the output voltage of the PID power supply may be different, and the transmission directions may be opposite; it depends on the specific application environment, and all of them are within the protection scope of this application.

[0140] S305. Calculate the ground insulation impedance of the system where the power converter is located based on the two sampling results.

[0141] In this embodiment, when switching from PID mode to ISO mode, the PID and ISO circuits can introduce voltage to each phase of the AC side of the system, actively intervening in the change of AC side neutral point to ground voltage, shortening the stabilization time of AC side neutral point to ground voltage when the PID function is removed from the system, and enabling the system to quickly enter ISO state.

[0142] Another embodiment of this application also provides a power conversion system, such as Figures 1 to 6 The diagram shows: at least one power converter 10, and PID and ISO circuitry 11 as described in any of the above embodiments; wherein:

[0143] When the number of power converters 10 is greater than 1, such as Figures 2 to 6 As shown, the AC sides of each power converter 10 are connected in parallel, and the connection point is grounded through the PID and ISO circuit 11.

[0144] In practical applications, the controllers of each power converter 10 can communicate and perform master-slave control, that is, one of the controllers can be used as the master controller. The master controller can be used to execute the control method of the PID and ISO circuits described in any of the above embodiments to control the operation of the PID and ISO circuits 11.

[0145] Alternatively, the controllers of each power converter 10 can be communicatively connected to a central controller. The specific communication connection method is not limited; various methods in the prior art can be used. In this case, the central controller can execute the control method to control the operation of the PID and ISO circuits 11.

[0146] The structure and working principle of the PID and ISO circuits 11, as well as the specific process of the control method, can be found in the corresponding embodiments described above, and will not be repeated here.

[0147] The power conversion system provided in this embodiment can quickly switch from PID mode to ISO mode, improving the reliability of the system's safe operation.

[0148] Additionally, when the number of power converters 10 is 1, such as Figure 1 As shown, the AC side of the power converter 10 is grounded through the PID and ISO circuit 11; the controller in the power converter 10 controls the operation of the PID and ISO circuit 11 by executing the control method of the PID and ISO circuit as described in any of the above embodiments.

[0149] In practical applications, the PID and ISO circuit 11 can be independent of the power converter 10, such as... Figure 1 As shown in the diagram. At this point, the power conversion system can quickly switch from PID mode to ISO mode, improving the reliability of the system's safe operation.

[0150] Alternatively, the PID and ISO circuits 11 can also be integrated inside the power converter 10. In this case, the power converter 10 can be used as follows: Figure 10 As shown, it specifically includes: a controller 13, a main circuit 12, and the PID and ISO circuit 11; wherein, the PID and ISO circuit 11 is connected between the AC side of the main circuit 12 and ground, and the PID and ISO circuit 11 and the main circuit 12 are respectively controlled by the controller 13; the controller is used to execute the control method. In this case, it is equivalent to... Figure 1 The PID and ISO circuits 11 in the circuit are moved to the power converter 10 to which they are connected, so that the power converter 10 can have anti-PID effect function and ISO function superimposed on the original function, and can quickly switch from PID mode to ISO mode, thereby improving the reliability of the system's safe operation.

[0151] Another embodiment of this application also provides a control device for PID and ISO circuits, such as Figure 11 As shown, the control device may include a memory 301 and a processor 302. The processor 302 may be connected to the power converter or the aforementioned main controller, and may control the switching actions of each switch in the aforementioned PID and ISO circuits 11. In practical applications, the processor 302 may be communicatively connected to the controller or main controller that executes the control method of the PID and ISO circuits, depending on the specific application environment, all of which are within the protection scope of this application.

[0152] The memory 301 can specifically be RAM (random access memory), flash memory, ROM (read only memory), EPROM (Electronic Programmable ROM, a type of non-volatile read-only memory), registers, hard disks, removable disks, etc.

[0153] The memory 301 is used to store computer instructions. When the computer instructions stored in the memory 301 are executed by the processor 302, the processor 302 can be used to execute the control method of the PID and ISO circuits described in any of the above embodiments. The memory 301 can also store data, such as thresholds involved in the above embodiments.

[0154] 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, DSL (digital subscriber line)) 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 media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; or, the available media can be semiconductor media, such as SSDs (solid state disks); the available media can also be other media, without limitation.

[0155] Another embodiment of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the control method of the PID and ISO circuits as described in any of the above embodiments.

[0156] That is, the computer-readable storage medium is used to store the methods or algorithms provided in the above embodiments. Specifically, it can be RAM, flash memory, ROM, EPROM, registers, hard disk, removable disk, or any other form of storage medium in the art.

[0157] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0158] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0159] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement 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 can 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 PID and ISO circuit, characterized in that, include: PID power supply, voltage transmission module, voltage introduction module, and detection resistor module; among which, The output terminal of the PID power supply is connected to the input terminal of the voltage transmission module; The first output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter through the voltage introduction module; The second output terminal of the voltage transmission module is connected to each phase of the AC side of the power converter through the detection resistor module; The voltage transmission module is used to: generate a first voltage through the first output terminal in PID mode, and transmit the first voltage to each phase of the AC side of the power converter through the voltage introduction module to achieve the function of anti-PID effect; when switching from PID mode to ISO mode, generate a second voltage through the first output terminal and transmit the second voltage to each phase of the AC side of the power converter through the voltage introduction module, or generate a third voltage through the second output terminal and transmit the third voltage to each phase of the AC side of the power converter through the detection resistor module, so as to adjust the neutral point voltage to ground of the AC side of the power converter to a preset value; In ISO mode, a fourth voltage is generated through the second output terminal, and the fourth voltage is transmitted to each phase of the AC side of the power converter through the sensing resistor module to realize the ISO function.

2. The PID and ISO circuit according to claim 1, characterized in that, The preset value is zero.

3. The PID and ISO circuit according to claim 1, characterized in that, The second voltage is in the opposite direction to the first voltage.

4. The PID and ISO circuit according to claim 1, characterized in that, The voltage transmission module includes: five switches; wherein... The first switch is connected between the positive output terminal of the PID power supply and the positive input terminal of the voltage introduction module; The second switch is connected between the negative terminal of the PID power supply output and ground. The third switch is connected between the positive terminal of the PID power supply output and ground. The fourth switch is connected between the negative output terminal of the PID power supply and the negative input terminal of the voltage introduction module; One end of the fifth switch is connected to the positive or negative output terminal of the PID power supply, and the other end of the fifth switch is connected to each phase of the AC side of the power converter through the detection resistor module. When the first switch and the second switch are closed, the voltage at the first output terminal is positive; when the third switch and the fourth switch are closed, the voltage at the first output terminal is negative. In ISO mode, the fifth switch and the switch used to ground the other pole of the PID power supply are in the closed state.

5. The PID and ISO circuit according to claim 4, characterized in that, The voltage transmission module further includes: a sixth switch; One end of the fifth switch is connected to the positive output terminal of the PID power supply; One end of the sixth switch is connected to the negative terminal of the PID power supply output; The other end of the fifth switch is connected to the other end of the sixth switch, and the connection point is connected to each phase of the AC side of the power converter through the detection resistor module; In ISO mode, the fifth switch and the second switch are in a closed state, or the sixth switch and the third switch are in a closed state.

6. The PID and ISO circuit according to claim 4, characterized in that, Each transmission path between the input terminal and the first output terminal of the voltage transmission module is also provided with a corresponding anti-reverse diode; And / or, corresponding anti-reverse diodes are also provided in the transmission path between the input terminal of the voltage transmission module and the second output terminal; The conduction direction of each anti-reverse diode is the direction in which the PID power supply outputs voltage through the corresponding switch.

7. The PID and ISO circuit according to any one of claims 1 to 6, characterized in that, The third voltage is the preset value.

8. The PID and ISO circuit according to any one of claims 1 to 6, characterized in that, The voltage introduction module includes: capacitors and each phase transmission bridge arm; The transmission bridge arm includes two diodes connected in series. The connection point of the two diodes in series serves as the midpoint of the transmission bridge arm for that phase, and is used to connect the corresponding phase on the AC side of the power converter. The capacitor is connected in parallel with each phase transmission bridge arm. The positive terminal of the parallel connection is connected to the positive input terminal of the voltage introduction module, and the negative terminal of the parallel connection is connected to the negative input terminal of the voltage introduction module.

9. The PID and ISO circuit according to any one of claims 1 to 6, characterized in that, The detection resistor module includes: detection resistors for each phase; One end of each of the detection resistors is connected, and the connection point is used to connect to the second output terminal; The other end of each of the detection circuits is connected to the corresponding phase on the AC side of the power converter.

10. A control method for PID and ISO circuits, characterized in that, include: In PID mode, the PID power supply in the PID and ISO circuits transmits voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module in sequence, thereby realizing the function of anti-PID effect. When switching from PID mode to ISO mode, the PID power supply is controlled to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the voltage introduction module, or the PID power supply is controlled to transmit voltage to each phase of the AC side of the power converter sequentially through the voltage transmission module and the detection resistor module in the PID and ISO circuits, thereby adjusting the AC side neutral point to ground voltage of the power converter to a preset value. After the voltage to ground at the neutral point on the AC side stabilizes, switch to ISO mode.

11. The control method for PID and ISO circuits according to claim 10, characterized in that, The preset value is zero.

12. The control method for PID and ISO circuits according to claim 10, characterized in that, Controlling the PID power supply to sequentially transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the voltage introduction module includes: The voltage transmission module is controlled to transmit the output voltage of the PID power supply in the opposite direction to that in PID mode, and the voltage is transmitted to each phase of the AC side of the power converter through the voltage introduction module.

13. The control method for PID and ISO circuits according to claim 10, characterized in that, Controlling the PID power supply to sequentially transmit voltage to each phase of the AC side of the power converter through the voltage transmission module and the detection resistor module in the PID and ISO circuits includes: The detection resistor module is grounded through the voltage transmission module and the PID power supply; Alternatively, the output voltage of the PID power supply can be controlled to the preset value and transmitted to the detection resistor module through the voltage transmission module.

14. The control method for PID and ISO circuits according to any one of claims 10 to 13, characterized in that, Before switching to ISO mode, the following are also included: Sample the AC side neutral point to ground voltage of the power converter.

15. The control method for PID and ISO circuits according to claim 14, characterized in that, After switching to ISO mode, it also includes: The output voltage of the PID power supply is transmitted to each phase of the AC side of the power converter through the detection resistor module, and the neutral point to ground voltage of the AC side of the power converter is sampled again after the output voltage of the PID power supply stabilizes. The ground insulation impedance of the system containing the power converter is calculated based on the two sampling results.

16. The control method for PID and ISO circuits according to any one of claims 10 to 13, characterized in that, After switching to ISO mode, it also includes: The voltage transmission module is controlled to transmit the output voltage of the PID power supply twice, and transmit it to each phase of the AC side of the power converter through the detection resistor module respectively; the absolute values ​​of the output voltage of the PID power supply are different in the two transmissions, and / or the transmission directions of the output voltage of the PID power supply by the voltage transmission module are opposite. Each time the output voltage of the PID power supply stabilizes, the AC side neutral point to ground voltage of the power converter is sampled. The ground insulation impedance of the system containing the power converter is calculated based on the two sampling results.

17. A power conversion system, characterized in that, include: At least one power converter, and, as described in any one of claims 1 to 9, PID and ISO circuitry; wherein, When the number of power converters is 1, the AC side of the power converter is grounded through the PID and ISO circuits; the controller in the power converter controls the PID and ISO circuits to work by executing the control method of the PID and ISO circuits as described in any one of claims 10 to 16. When the number of power converters is greater than 1, the AC sides of each power converter are connected in parallel, and the connection point is grounded through the PID and ISO circuits; the controller in any of the power converters, or the main controller that is communicatively connected to each of the controllers, controls the operation of the PID and ISO circuits by executing the control method.

18. The power conversion system according to claim 17, characterized in that, When the number of power converters is 1, the PID and ISO circuits are independent of the power converter, or the PID and ISO circuits are integrated inside the power converter.

19. A control device with PID and ISO circuits, 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 control method of the PID and ISO circuits as described in any one of claims 10 to 16.

20. A computer-readable storage medium, characterized in that, The system contains a computer program that is loaded by a processor to execute the control method for the PID and ISO circuits as described in any one of claims 10 to 16.

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