High-security MPPT (maximum power point tracking) controller and system

Abstract

The utility model relates to the technical field of photovoltaic power generation, in particular to a high-security MPPT (maximum power point tracking) controller and an insulation impedance detection system based on the MPPT controller. The utility model discloses a high-security MPPT (maximum power point tracking) controller, which comprises an input end and an output end, the control unit is configured to track the maximum power point output by the photovoltaic cell panel; the controllable quick change-over switch is arranged in an output loop of the control unit in series; and the insulation impedance detection module is connected to the controllable quick change-over switch. According to the scheme, the high-security MPPT controller is combined with the insulation impedance detection system based on the MPPT controller, so that the system structure is simplified, the manufacturing cost is reduced, the real-time protection capability and applicability of the system are improved, the safety and reliability of the photovoltaic system are remarkably enhanced, and the photovoltaic system has remarkable practical value and popularization prospect.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic power generation technology, and in particular to a high-security MPPT controller and an insulation impedance detection system based on the MPPT controller. Background Technology

[0002] In photovoltaic (PV) power generation systems, the Maximum Power Point Tracking (MPPT) controller is a key component responsible for optimizing the output power of PV panels to improve the overall system efficiency. However, with the continuous expansion of PV system scale and increasingly stringent grid connection requirements, system safety and reliability have become particularly important.

[0003] In the prior art, there has been some research on insulation impedance detection for photovoltaic systems. For example, existing literature 1 (CN201510789453.1, authorization announcement number CN105356848B) discloses an insulation impedance detection device and method for a photovoltaic inverter with multiple MPPT inputs. This device improves the detection accuracy by setting up multiple sub-circuits and switches to detect the insulation impedance of the photovoltaic system to ground. However, this scheme is mainly applicable to inverters with multiple MPPT inputs, the system structure is complex, the cost is high, and the detection response speed is limited, making it difficult to meet the needs of rapid protection.

[0004] Meanwhile, the inventors of this case discovered that Document 1 primarily targets photovoltaic inverters with multiple MPPT inputs and calculates insulation impedance through continuous switching of external sub-circuits and resistors. Its goal is to improve the accuracy and applicability of insulation impedance detection, but it does not address the issue of how to perform fast and safe insulation impedance detection when the MPPT controller itself outputs. Especially in a system architecture with AC neutral ground, if the MPPT controller is not disconnected from the load or energy storage device before performing insulation impedance detection, a current loop to ground will occur on the DC bus, which can easily lead to hardware damage to the MPPT controller or a short circuit to ground. In this situation, even with a complex circuit topology featuring multiple MPPT inputs, it is difficult to avoid the potential risks caused by the ground loop. Utility Model Content

[0005] The purpose of this invention is to provide a high-security MPPT controller and an insulation impedance detection system based on the MPPT controller to address the shortcomings of existing technologies. The high-security MPPT controller, by adding a controllable fast switching switch to the output of the MPPT controller and combining it with the system design, enables the MPPT to independently detect its insulation status to ground before grid connection and during operation, and to quickly disconnect when an abnormality is detected. It is particularly suitable for photovoltaic or energy storage system architectures with AC side neutral grounding.

[0006] This utility model achieves the above objectives through the following technical solution: a high-security MPPT controller, comprising:

[0007] The input terminal is used to receive electrical energy from photovoltaic panels;

[0008] The output terminal is used to output optimized electrical energy to the load or energy storage device;

[0009] A controllable fast-change switch is connected in series in the output circuit of the control unit; and

[0010] An insulation resistance detection module is connected to the controllable fast switching switch and is used to detect the insulation resistance of the high-security MPPT controller to ground.

[0011] The control unit, configured to achieve maximum power point tracking (MPPT) of the photovoltaic panel output, is used to confirm that the controllable fast switching switch is in the open state before connecting the MPPT controller to a load or energy storage device, and then control the insulation impedance detection module to perform insulation impedance detection. If the controllable fast switching switch is not open, it is disconnected before controlling the insulation impedance detection module to perform insulation impedance detection, ensuring the accuracy of the insulation impedance detection. It is also used to control the controllable fast switching switch to close when the insulation impedance detection module detects that the insulation impedance of the MPPT controller to ground meets a preset condition. Specifically, it determines whether the insulation impedance of the MPPT controller to ground detected by the insulation impedance detection module meets the preset condition. If it does, it controls the controllable fast switching switch to close, connecting the MPPT controller to a load or energy storage device. MPPT stands for Maximum Power Point Tracking. By setting a controllable fast switching switch in series in the output circuit of the MPPT controller and equipping it with an insulation impedance detection module, the insulation impedance of the MPPT controller is detected before connecting it to a load or energy storage device. This technical feature effectively avoids short-circuit faults caused by insufficient insulation resistance, improving the safety and reliability of photovoltaic systems. The control unit is an MCU chip built into the MPPT controller.

[0012] As a further aspect of this invention, the control unit includes a DC / DC conversion circuit for converting the DC power input to the DC bus and, under the action of a control signal, outputting voltage and current matching the load or energy storage device to the DC bus. This DC bus is shared with the insulation resistance detection module and the controllable fast switching switch. Specifically, by integrating the DC / DC conversion circuit into the control unit, efficient conversion of the input power is achieved, ensuring that the output power matches the voltage and current requirements of the load or energy storage device. This not only optimizes energy conversion efficiency but also improves the stability and adaptability of the system, further enhancing the overall performance of the photovoltaic system.

[0013] As a further aspect of this invention, the control unit includes a monitoring circuit for monitoring changes in insulation impedance, so as to immediately control the controllable fast-switching switch to disconnect when a decrease in insulation impedance is detected. Specifically, by integrating the monitoring circuit into the control unit, real-time monitoring of changes in insulation impedance is achieved. When a decrease in insulation impedance is detected, the system can quickly disconnect the switch to prevent potential short-circuit faults. This function significantly improves the real-time protection capability of the system and ensures the safe operation of the photovoltaic system under abnormal conditions.

[0014] As a further embodiment of this utility model: the controllable fast switching switch is disposed inside the control unit, or disposed at any position between the control unit and the output circuit;

[0015] The insulation resistance detection module is an insulation resistance detection circuit installed inside the high-security MPPT controller. Specifically, by flexibly placing a controllable fast-switching switch inside the control unit or at any location in the output circuit, the flexibility and scalability of the system design are improved. Meanwhile, the sensors and processor in the insulation resistance detection module ensure the accuracy and processing efficiency of the detection data, further enhancing the system's reliability and response speed.

[0016] As a further embodiment of this utility model: the insulation impedance detection module is connected to the controllable fast switching switch;

[0017] The control unit is used to confirm that the controllable fast-change switch is in the open state before connecting the high-security MPPT controller to the load or energy storage device, and then control the insulation impedance detection module to perform insulation impedance detection. If the controllable fast-change switch is not open, the controllable fast-change switch is disconnected before controlling the insulation impedance detection module to perform insulation impedance detection, ensuring the accuracy of insulation impedance detection. It is also used to control the controllable fast-change switch to close when the insulation impedance detection module detects that the insulation impedance of the high-security MPPT controller to ground meets a preset condition, thus connecting the high-security MPPT controller to the load or energy storage device. Specifically, the connection relationship between the insulation impedance detection module and the controllable fast-change switch, as well as the operating logic of the control unit under different detection conditions, are further clarified. This technical feature ensures that the system can effectively control the opening and closing state of the switch during the detection process, achieving efficient and reliable insulation impedance detection and control, and improving the overall safety of the system.

[0018] As a further embodiment of this invention: the control unit is used to implement the boost function;

[0019] The controllable fast switching switch is a semiconductor device or other controllable switching device that can be turned on and off. Specifically, by specifying the boost function of the control unit, the type of switching device is clarified, and the grounding method of the connected load or energy storage device is specified. These technical features not only optimize the power transmission efficiency but also ensure the safety and reliability of the system grounding, further improving the overall performance and safety protection capabilities of the photovoltaic system.

[0020] This utility model also provides another technical solution: an insulation impedance detection system based on an MPPT controller, comprising:

[0021] Photovoltaic solar panel assembly;

[0022] The MPPT controller, as the power management unit of the photovoltaic panel array, has an input terminal and an output terminal, with the input terminal connected to the photovoltaic panel array; and

[0023] A load or energy storage device, connected to the output terminal of the MPPT controller, configured as a DC power input device for the DC output of the high-security MPPT controller;

[0024] The MPPT controller mentioned above is any of the high-security MPPT controllers described in the preceding descriptions. Specifically, the high-security MPPT controller is integrated into the entire photovoltaic system, and efficient power conversion and matching are achieved through a DC / DC conversion circuit. This configuration ensures that photovoltaic power can be transmitted to the load or energy storage device in an optimal state, improving the overall energy efficiency and reliability of the system. Simultaneously, by tightly integrating the high-security MPPT controller with the DC / DC conversion circuit, the system structure is simplified, and the overall cost is reduced.

[0025] As a further aspect of this invention: the load or energy storage device includes a DC / AC conversion circuit connected to the controllable fast-switching switch. Specifically, the load or energy storage device can be the power grid. Specifically, by introducing a DC / AC conversion circuit into the load or energy storage device, efficient conversion of DC power to AC power is achieved, enabling the photovoltaic system to be directly connected to the power grid or supply AC loads. This technical feature expands the system's application range, improves the system's compatibility with the power grid, and enhances the system's practicality and market adaptability.

[0026] This utility model provides another technical solution: an insulation impedance detection system based on an MPPT controller, comprising:

[0027] Photovoltaic solar panel assembly;

[0028] The MPPT controller is configured as the power management unit of the photovoltaic panel group;

[0029] A controllable fast-change switch is connected in series in the output circuit of the MPPT controller;

[0030] A load or energy storage device, configured as a DC power input device for use with the DC output of the MPPT controller; and

[0031] An insulation impedance detection module is connected to the controllable fast switching switch and is used to perform insulation impedance detection when the controllable fast switching switch is in the open state before the high-security MPPT controller is connected to the load or energy storage device, that is, to detect the insulation impedance of the MPPT controller to ground.

[0032] The system is configured to confirm that the controllable fast-change switch is in the open state before connecting the MPPT controller to the load or energy storage device, thereby controlling the insulation impedance detection module to perform insulation impedance detection, ensuring the accuracy of the insulation impedance detection. It is also configured to control the controllable fast-change switch to close when the insulation impedance detection module detects that the insulation impedance of the high-security MPPT controller to ground meets a preset condition, thus connecting the high-security MPPT controller to the load or energy storage device. Specifically, the system further clarifies the connection relationships and functional allocation of each component, achieving efficient operation and safety protection through clear functional module division. The linkage mechanism between the insulation impedance detection module and the controllable fast-change switch ensures that the system can quickly take protective measures when abnormal insulation impedance is detected, preventing potential electrical faults and significantly improving the system's safety and reliability.

[0033] As a further embodiment of this utility model:

[0034] The system also includes a control unit. Before connecting the high-security MPPT controller to the load or energy storage device, the control unit confirms that the controllable fast switching switch is in the open state before controlling the insulation impedance detection module to perform insulation impedance detection. If the controllable fast switching switch is not open, the control unit disconnects the switch before controlling the insulation impedance detection module to perform insulation impedance detection, ensuring the accuracy of the insulation impedance detection. The control unit also controls the controllable fast switching switch to close when the insulation impedance detection module detects that the high-security MPPT controller's insulation impedance to ground meets preset conditions, thus connecting the high-security MPPT controller to the load or energy storage device. Specifically, through the dual-function design of the control unit, it is responsible for both insulation impedance detection and switching control, and also ensures the normal grid-connected operation of the system when insulation conditions are met. This technical feature further enhances the overall safety and operational reliability of the system, ensuring the stability of the photovoltaic system under various operating conditions.

[0035] The beneficial effects of this utility model are:

[0036] I. Regarding the high-security MPPT controller in this case:

[0037] 1. Reduced system complexity. Compared to existing technologies that use multiple sub-circuits and switches to detect insulation resistance, this invention only adds a controllable fast-switching switch and an insulation resistance detection module to the control unit output circuit, simplifying the system structure and reducing manufacturing costs and maintenance difficulty.

[0038] 2. Improved detection response speed. By using a fast switching switch and insulation resistance detection module, this invention can quickly perform insulation resistance detection before the MPPT controller is integrated into the system, reducing the detection time, improving the system's real-time protection capability, enabling faster response to potential insulation faults, and reducing the risk of system damage.

[0039] 3. Enhanced applicability and versatility. The insulation impedance detection scheme of this utility model is not limited to inverters with multiple MPPT inputs, but is applicable to single-channel and other types of MPPT controllers, expanding its application range and improving the system's flexibility and adaptability.

[0040] 4. Enhanced system safety and reliability. By ensuring that the MPPT controller's insulation impedance to ground meets preset conditions before grid connection, this invention effectively avoids short-circuit faults caused by insufficient insulation impedance, reduces system hardware losses, and enhances the overall safety and reliability of the photovoltaic system.

[0041] II. Regarding the insulation impedance detection system based on the MPPT controller in this case:

[0042] 1. Simplified system structure: By integrating a high-security MPPT controller and an insulation impedance detection module, this invention reduces the need for additional sub-circuits and switches, simplifies the overall structure of the photovoltaic system, and reduces manufacturing costs and maintenance difficulty.

[0043] 2. Improved detection response speed. The insulation resistance detection module can quickly perform insulation resistance detection before the MPPT controller is integrated into the system, reducing the detection time, improving the system's real-time protection capability, and enabling faster response to potential insulation faults, thus reducing the risk of system damage.

[0044] 3. Enhanced applicability and versatility. This utility model's high-security photovoltaic system is applicable to single-channel and multi-channel MPPT controllers, expanding its application range and improving the system's flexibility and adaptability, making it suitable for photovoltaic power generation systems of different scales and types.

[0045] 4. Improve system safety and reliability: By ensuring that the ground insulation impedance of the high-security MPPT controller meets the preset conditions before grid connection, this utility model effectively avoids short-circuit faults caused by insufficient insulation impedance, reduces system hardware losses, and enhances the overall safety and reliability of the photovoltaic system.

[0046] 5. Facilitates system integration and upgrades. The integrated design of the high-security MPPT controller and insulation impedance detection module makes upgrading and maintaining the photovoltaic system more convenient and facilitates the expansion and optimization of system functions.

[0047] In summary, existing literature focuses primarily on calculating insulation impedance and improving detection accuracy. Our proposed solution addresses the lack of a controllable switch on the MPPT controller's output side, which leads to a ground loop and the inability to perform insulation impedance detection. By installing a controllable fast-switch at the output end, in conjunction with the detection module, it can quickly disconnect even in systems with neutral grounding. This enables insulation impedance detection and fault protection for the MPPT controller before grid connection and during operation. This approach enhances system safety while avoiding the cost and slow response times associated with complex, multi-channel sub-circuit layouts, making it suitable for various applications with single-channel and multi-channel MPPT controllers. Attached Figure Description

[0048] Figure 1 This is a structural connection block diagram of a high-security MPPT controller according to an embodiment of the present application, which is connected to the power grid system via N-line grounding.

[0049] Figure 2 This is a flowchart illustrating a switch closing logic according to an embodiment of this application.

[0050] Figure 3 This is a flowchart illustrating a switch disconnection logic according to an embodiment of this application.

[0051] Figure 4 This is a simplified structural connection block diagram of a photovoltaic system according to an embodiment of this application.

[0052] Figure 5 for Figure 4 A more detailed structural connection diagram based on the existing structure. Detailed Implementation

[0053] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. It is understood that the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present utility model. The connection relationships shown in the drawings are only for clear description and do not limit the connection method.

[0054] In related technologies, there has been some research on insulation impedance detection for photovoltaic systems. For example, existing patent document 1 (CN201510789453.1, authorization announcement number CN105356848B) discloses an insulation impedance detection device and method for a multi-MPPT input photovoltaic inverter. This device sets at least two independently switchable sub-circuits in the multi-MPPT input photovoltaic inverter, connecting them respectively between the positive terminal and ground of each solar panel and between the negative terminal and ground. A controller is used to control and calculate the on / off state of each sub-circuit, thereby calculating the insulation impedance value to ground of the photovoltaic system. This method, by changing the input resistance value, accurately calculates multiple insulation impedance values ​​based on Kirchhoff's laws, and then selects the insulation impedance corresponding to the largest change value as the accurate value of the system, thus improving the detection accuracy.

[0055] However, the inventors discovered that the insulation impedance detection scheme in existing patent document 1 is mainly applied to photovoltaic inverters with multiple MPPT inputs, and its detection method relies on the on / off state changes of sub-circuits, indirectly calculating the insulation impedance value through the connection of resistors. While this method improves the accuracy of detection to some extent, it still has the following shortcomings in practical applications:

[0056] 1. Inability to perform effective insulation resistance testing. When it is necessary to assess the insulation status between the MPPT controller and ground, if the output terminal is directly connected to the system load or energy storage device, and the AC side is grounded with the N line, once a loop is formed between the DC bus and ground, it will be impossible to disconnect the line for separate MPPT ground testing before grid connection, and the system is prone to leakage or short circuit risks.

[0057] 2. The hardware is easily damaged and lacks rapid protection. If there is no controllable switch on the output side, it is difficult to disconnect the circuit in time once insufficient insulation resistance is detected; especially in the case of neutral grounding, the DC side of the MPPT controller is likely to form a loop to ground, which will cause overcurrent and overheating of the device and cause further damage to the hardware.

[0058] 3. Detection response speed and system safety. Even if external sub-circuits or more complex methods are used to improve the accuracy of insulation resistance detection, if there is no switch in the system that can be quickly disconnected, the circuit cannot be cut off in time after a fault is detected, thus failing to meet the requirements for rapid protection.

[0059] Therefore, such as Figures 1-5As shown, embodiments of this application provide a high-security MPPT controller and an insulation impedance detection system based on the MPPT controller. By adding a controllable fast-switching switch to the output of the MPPT controller and integrating it with the system design, the system can independently detect the ground insulation status of the MPPT itself before grid connection and during operation, and quickly disconnect when an abnormality is detected. This is particularly suitable for photovoltaic or energy storage system architectures with AC-side neutral grounding. By setting a controllable fast-switching switch and an integrated DC / DC converter or DC / DC conversion circuit at the output of the control unit, insulation impedance detection of the MPPT controller before it is connected to the system can be achieved, thereby effectively avoiding short-circuit faults caused by insufficient insulation impedance and improving the safety and reliability of the photovoltaic system.

[0060] Example 1: Structure and Function of a High-Security MPPT Controller

[0061] This utility model discloses a high-security MPPT controller, comprising: an input terminal, a control unit, an output terminal, a controllable fast-switching switch, and an insulation resistance detection module. Wherein:

[0062] Input terminal: Used to receive DC power from photovoltaic panels.

[0063] The control unit includes a DC / DC conversion circuit, a maximum power point tracking (MPPT) algorithm, and a monitoring circuit. The DC / DC conversion circuit boosts the DC power received at the input terminal to optimize the output power; through control signals, it achieves voltage and current output matching the load or energy storage device. The maximum power point tracking (MPPT) algorithm tracks the maximum power point output of the photovoltaic panel array, optimizing energy harvesting in the photovoltaic system. The monitoring circuit monitors changes in insulation impedance in real time to ensure safe system operation; when a decrease in insulation impedance is detected, it immediately sends a signal to control the controllable fast switching switch to open. It also controls the controllable fast switching switch to close when the insulation impedance detection module detects that the insulation impedance of the MPPT controller to ground meets a preset condition. The control unit is an MCU chip built into the MPPT controller, used to determine whether the insulation impedance of the MPPT controller to ground detected by the insulation impedance detection module meets the preset condition. If it does, it controls the controllable fast switching switch to close, connecting the high-security MPPT controller to the load or energy storage device.

[0064] Output: Connect to a load or energy storage device to output optimized DC power.

[0065] Controllable fast switching switch: It is set in series in the output circuit of the control unit; it can be a semiconductor device (such as MOSFET) or other controllable switching device; its on / off state is controlled by the control unit.

[0066] Insulation resistance detection module: This is an insulation resistance detection circuit installed inside the high-security MPPT controller, used to detect the insulation resistance of the high-security MPPT controller to ground.

[0067] System workflow:

[0068] Startup Phase: 1. The control unit initializes and sets the switch to the off state; 2. The insulation impedance detection module begins to detect the insulation impedance to ground of the high-security MPPT controller; 3. If the insulation impedance meets the preset conditions, the control unit sends a control signal, closes the switch, and the MPPT controller is connected to the load or energy storage device.

[0069] Operational phase: 1. The control unit continuously optimizes the output of the photovoltaic panel array through the MPPT algorithm; 2. The insulation impedance detection module continuously monitors the insulation impedance; 3. If the insulation impedance is detected to drop below the preset threshold, the control unit immediately disconnects the switch, cuts off the circuit, and prevents short circuit faults.

[0070] Example 2: Overall Structure of an Insulation Impedance Detection System Based on an MPPT Controller

[0071] An insulation resistance detection system based on an MPPT controller. For example... Figure 4 and Figure 5 The system comprises the following main components: a photovoltaic panel array 1, a high-security MPPT controller 2, and a load or energy storage device 4. The high-security MPPT controller 2 also includes a DC / DC conversion circuit, a controllable fast-switching switch 3, and an insulation resistance detection module. Among these:

[0072] The photovoltaic panel assembly consists of multiple photovoltaic panels, which are connected to a high-security MPPT controller via cables.

[0073] The high-security MPPT controller, as a power management unit, is responsible for receiving power from photovoltaic panels and performing maximum power point tracking; it includes an input terminal, an output terminal, a controllable fast switching switch, and an insulation resistance detection module.

[0074] The DC / DC conversion circuit is integrated into the control unit; it boosts the output of the high-security MPPT controller to ensure that the output voltage matches the needs of the load or energy storage device.

[0075] A controllable fast-change switch is connected in series in the output circuit of the control unit; it is connected to the load or energy storage device and controlled by an insulation resistance detection module.

[0076] A load or energy storage device, which can be a power grid or other energy storage device; it accepts the output power of a DC / DC conversion circuit. For example... Figure 1The AC side of the load or energy storage equipment is grounded using the N-line grounding method.

[0077] The insulation impedance detection module is used to detect the insulation impedance of the high-security MPPT controller to ground; insulation impedance detection is performed before grid connection when the controllable fast switching switch is in the open state to ensure system safety.

[0078] System operation process:

[0079] Pre-grid connection test: 1. When the system starts, the control unit sets the switch to the open state; 2. The insulation impedance detection module detects the ground insulation impedance of the high-security MPPT controller; 3. If the insulation impedance meets the preset conditions, the control unit closes the switch, and the MPPT controller is connected to the load or energy storage device to realize the connection between photovoltaic power generation and the load.

[0080] Monitoring and Protection During Operation: 1. During system operation, if the system detects low voltage or abnormal leakage current, the control unit of the MPPT controller immediately disconnects the controllable fast switching switch to cut off the circuit, prevent short-circuit faults, and ensure safe system operation. Specifically, insulation impedance detection is performed only once after power-on. During operation, other parameters are used to determine if there is a short-circuit fault to ground, such as excessively low voltage on the positive / negative busbar.

[0081] Additionally, it's important to note that in practical applications, the AC power on the user side often uses a neutral (N) grounding method (such as in some grid-connected photovoltaic systems or energy storage systems). This means that when the DC side of the photovoltaic system is connected to the neutral-grounded AC side, a loop can easily form between the DC bus and ground. If the traditional MPPT controller output does not have a controllable fast-switching switch, then:

[0082] 1. Lack of independent insulation resistance detection method. When the user side is neutral grounded, it is difficult to disconnect the output terminal of the MPPT controller to measure its insulation resistance to ground in grid-connected or pre-grid-connected state, which can easily lead to leakage or short circuit to ground faults.

[0083] 2. Difficulty in timely disconnection of faulty circuits. If a low resistance or short circuit occurs between the DC bus and ground, and the output cannot be disconnected, it may cause hardware overcurrent damage. In addition, the AC terminal grounded to the neutral line will further increase the flow path of fault current, increasing the fault energy and the degree of damage.

[0084] This design incorporates a controllable fast-change switch (i.e., a controllable fast-change switch) at the output of the MPPT controller. This allows the output to be disconnected and the insulation resistance of the MPPT controller to ground to be detected before grid connection or pre-grid connection. Once the detected value is normal, the switch is closed, connecting the MPPT controller back into the system. The benefits of this approach include:

[0085] 1. No longer dependent on whether the AC side is grounded with a neutral (N) wire: With a controllable switch, even if the user side is grounded with a neutral (N) wire, the MPPT controller can be physically disconnected from the external system first, and safe insulation impedance testing or rapid isolation can be performed in case of a fault, significantly reducing the risk of hardware damage.

[0086] 2. Rapid fault protection: If an abnormal insulation impedance is detected during operation, the control unit can immediately send a signal to disconnect the controllable switch, thereby limiting the fault to a minimum and effectively preventing further damage caused by short circuit to ground.

[0087] 3. Enhance system safety and adaptability: Through the isolation mechanism of this controllable switch, the system can maintain a high level of safety protection and versatility even when facing different user-side grounding methods (including N-line grounding, PE grounding or other forms).

[0088] Therefore, when facing an application environment with AC-side N-line grounding, this solution does not require additional changes to the user-side grounding method, and can also ensure independent detection and fault isolation of the ground insulation impedance through a controllable switch, greatly improving the safety and reliability of the photovoltaic system in complex power grid environments.

[0089] Example 3: Working process of an insulation resistance detection system based on an MPPT controller

[0090] A flowchart of an insulation resistance detection system based on an MPPT controller. The process includes the following steps:

[0091] 1. Start detection: When the system starts, the control unit control switch is in the off state.

[0092] 2. Perform insulation impedance testing: The insulation impedance testing module tests the insulation impedance to ground of the high-security MPPT controller.

[0093] 3. Determine if the insulation resistance meets the conditions:

[0094] If the preset conditions are met, the control unit sends a command to close the switch, connecting the high-security MPPT controller to the load or energy storage device.

[0095] If the conditions are not met, keep the switch off and the system will not operate in parallel with the grid.

[0096] 4. Monitoring during operation: If the system detects low voltage or abnormal leakage current during operation, the control unit of the MPPT controller will immediately disconnect the controllable fast switching switch to cut off the circuit, prevent short circuit faults, and ensure safe operation of the system.

[0097] 5. Protection in case of fault: If the insulation resistance is detected to be lower than the preset threshold, the control unit will immediately disconnect the switch, cut off the circuit, prevent short circuit faults, and ensure the safe operation of the system.

[0098] Through the above embodiments, this utility model provides a high-security MPPT controller and its application scheme in photovoltaic systems, solving the problems of high system complexity, slow detection response speed, and limited applicability in existing technologies. The combination of the high-security MPPT controller and the insulation impedance detection system based on the MPPT controller not only simplifies the system structure and reduces manufacturing costs, but also improves the system's real-time protection capabilities and applicability, significantly enhancing the safety and reliability of photovoltaic systems, and possessing significant practical value and promising prospects for widespread application. In detail:

[0099] 1. System structure optimization: By setting a controllable fast switching switch in series in the output circuit of the MPPT controller and integrating a DC / DC converter and an insulation resistance detection module, this invention reduces the need for additional sub-circuits and switches, simplifies the system structure, and reduces manufacturing costs and maintenance difficulty.

[0100] 2. Improved detection response speed: The controllable fast-change switch allows for rapid circuit disconnection and insulation resistance testing before the MPPT controller is connected to a load or energy storage device. This rapid response capability ensures that the system can identify and block potential insulation faults in the shortest possible time, reducing the risk of system damage due to faults.

[0101] 3. Enhanced applicability and versatility: The high-security MPPT controller of this invention is not limited to photovoltaic inverters with multiple MPPT inputs, but is applicable to single-channel and other types of MPPT controllers, expanding its application range and improving the system's flexibility and adaptability, making it suitable for photovoltaic power generation systems of different scales and types.

[0102] 4. Improve system safety and reliability: By ensuring that the MPPT controller's insulation impedance to ground meets preset conditions before grid connection, this invention effectively avoids short-circuit faults caused by insufficient insulation impedance, reduces system hardware losses, and enhances the overall safety and reliability of the photovoltaic system.

[0103] 5. Facilitates system integration and maintenance: The integrated design of the high-security MPPT controller with the DC / DC converter and insulation impedance detection module makes the upgrading and maintenance of the photovoltaic system more convenient and facilitates the expansion and optimization of system functions.

[0104] In the specification and claims of this application, the terms "comprising / including" and "having / including" and variations thereof are used to specify the presence of the stated features, values, steps or components, but do not exclude the presence or addition of one or more other features, values, steps, components or combinations thereof.

[0105] Some features of this invention are described in different embodiments for clarity; however, these features may also be described in combination in a single embodiment. Conversely, some features of this invention are described only in a single embodiment for brevity; however, these features may also be described individually or in any suitable combination in different embodiments.

[0106] Finally, it should be noted that any cross-referencing or superposition of the various embodiments of this solution by those skilled in the art still falls within the original disclosure scope of this solution. Furthermore, the above descriptions are merely preferred embodiments of this utility model and are not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A high security MPPT controller, characterized in that, include: The input terminal is used to receive electrical energy from photovoltaic panels; The output terminal is used to output optimized electrical energy to the load or energy storage device; A controllable, fast-change switch is connected in series in the output circuit of the control unit; An insulation impedance detection module is connected to the controllable fast-change switch; and The control unit, configured to achieve maximum power point tracking of the photovoltaic panel output, is used to confirm that the controllable fast switching switch is in the off state before the insulation impedance detection module performs insulation impedance detection before the load or energy storage device is connected to the MPPT controller.

2. The high security MPPT controller according to claim 1, wherein, The control unit is also used to control the controllable fast switching switch to close when the insulation impedance detection module detects that the insulation impedance of the MPPT controller to ground meets the preset conditions. The control unit includes a DC / DC conversion circuit for converting the DC power at the input terminal and outputting a voltage and current matching the load or energy storage device to the DC bus under the action of a control signal, and sharing the DC bus with the insulation impedance detection module and the controllable fast switching switch.

3. The high security MPPT controller according to claim 1, wherein, The control unit includes a monitoring circuit for monitoring changes in insulation impedance, so as to immediately control the controllable fast switching switch to disconnect when a decrease in insulation impedance is detected.

4. The high security MPPT controller of claim 1, wherein, The controllable fast switching switch is located inside the control unit or at any position between the control unit and the output circuit. The insulation impedance detection module is an insulation impedance detection circuit installed inside the high-security MPPT controller, used to detect the insulation impedance of the high-security MPPT controller to ground.

5. The high security MPPT controller according to claim 1, wherein, The insulation impedance detection module is connected to the controllable fast switching switch; The control unit is used to confirm that the controllable fast switching switch is in the open state before the high-security MPPT controller is connected to the load or energy storage device, and then the insulation impedance detection module performs insulation impedance detection. It is also used to control the controllable fast switching switch to close and connect the high-security MPPT controller to the load or energy storage device when the insulation impedance detection module detects that the insulation impedance of the high-security MPPT controller to ground meets the preset conditions.

6. The high security MPPT controller of claim 1, wherein, The control unit is used to implement the voltage boosting function; The controllable fast switching switch is a semiconductor device or a controllable switching device.

7. An insulation impedance detection system based on an MPPT controller, characterized by, include: Photovoltaic solar panel assembly; The MPPT controller, as the power management unit of the photovoltaic panel group, has an input terminal and an output terminal, with the input terminal connected to the photovoltaic panel group. as well as A load or energy storage device, connected to the output terminal of the MPPT controller, configured as a DC power input device for the DC output of the high-security MPPT controller; The MPPT controller is the high-security MPPT controller described in any one of claims 1-6.

8. The MPPT controller based insulation impedance detection system of claim 7, wherein, The load or energy storage device includes a DC / AC conversion circuit connected to the controllable fast switching switch.

9. An insulation impedance detection system based on an MPPT controller, characterized by, include: Photovoltaic solar panel assembly; The MPPT controller is configured as the power management unit of the photovoltaic panel group; A controllable fast switch is arranged in series in an output loop of the MPPT controller; A load or energy storage device is configured as a DC power input device for DC output of the MPPT controller; and An insulation impedance detection module is connected to the controllable fast switch and used for detecting insulation impedance of the MPPT controller to ground. The system is configured to, before the MPPT controller is incorporated into the load or energy storage device, first confirm that the controllable fast switch is in an open state, then control the insulation impedance detection module to perform insulation impedance detection, and further configured to, when the insulation impedance detection module detects that the insulation impedance of the MPPT controller to ground meets a preset condition, control the controllable fast switch to be closed, and incorporate the MPPT controller into the load or energy storage device. The system further comprises a control unit configured to, before the MPPT controller is incorporated into the load or energy storage device, first confirm that the controllable fast switch is in an open state, then control the insulation impedance detection module to perform insulation impedance detection, and further configured to, when the insulation impedance detection module detects that the insulation impedance of the MPPT controller to ground meets a preset condition, control the controllable fast switch to be closed, and incorporate the MPPT controller into the load or energy storage device.

10. The MPPT controller based insulation impedance detection system as claimed in claim 9, wherein, ​

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