Photovoltaic dc voltage boosting isolation device

Abstract

The application provides a photovoltaic direct-current boost isolation device, and relates to the technical field of photovoltaic power generation.The device comprises a photovoltaic input bus unit, an EMI filter unit, a soft-start impact-preventing unit, an isolated DC-DC boost main topology unit, a high-frequency isolation transformer, a rectification and voltage stabilization unit, an output filter unit, a sampling and detection unit, a main control driving unit and a protection unit.The output end of the photovoltaic input bus unit, the EMI filter unit, the soft-start impact-preventing unit, the isolated DC-DC boost main topology unit, the high-frequency isolation transformer, the rectification and voltage stabilization unit and the rectification and voltage stabilization unit are sequentially connected.The driving signal output end of the main control driving unit is connected with the switch control end of the isolated DC-DC boost main topology unit.The application realizes complete electrical isolation between input and output through the high-frequency isolation transformer, reduces the heating of devices, improves the operation efficiency and service life of the whole machine, and is stable in long-term outdoor operation and low in failure rate.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and more specifically, to a photovoltaic DC boost isolation device. Background Technology

[0002] Currently, photovoltaic (PV) power generation systems generally use PV module arrays to output DC 0-820V voltage, which is then converted to AC 380-420V AC voltage by an inverter, stepped up by a transformer, and connected to the national grid. However, the grid's peak-shaving capacity is currently limited, making it difficult for large-scale PV systems to connect to the grid. Off-grid applications are the best solution to the grid connection problem, and are divided into AC off-grid and DC off-grid. AC off-grid requires the construction of grid-connected power generation equipment, which involves large investments and is difficult to implement. DC off-grid, combined with an electric thermal storage load, forms the best solution. Wide-range fluctuating DC power is stepped up and combined before being connected to an inverter or a high-voltage DC grid-connected system. PV arrays are affected by factors such as light intensity, temperature, cloud cover, and inconsistent module degradation, resulting in large fluctuations in output voltage and current. Furthermore, the DC side of the PV system suffers from ground clutter, leakage current, surge voltage, and common-mode interference.

[0003] Existing photovoltaic boost solutions mostly adopt non-isolated boost topologies or ordinary modular non-isolated boost structures, which have obvious shortcomings: non-isolated structures do not have electrical isolation between input and output, making it easy for DC-side faults, short circuits to ground, and high-voltage backflashovers to damage downstream inverter equipment, and even cause DC arcing and fire hazards; traditional single-stage boost topologies have limited boost ratios and cannot be adapted to the new generation of DC 6000V high-voltage DC photovoltaic systems; when multiple components are connected in parallel, there are problems such as uneven power, circulating current interference, voltage drift, and large ripple; at the same time, conventional boost equipment has weak resistance to lightning strikes and surges, poor stability and high failure rate under harsh outdoor conditions, and cannot meet the high reliability, high safety and high gain DC boost grid connection requirements of large photovoltaic power plants. Summary of the Invention

[0004] This invention aims to solve the problems of existing photovoltaic DC boost technology, such as poor electrical isolation and safety, insufficient boost ratio, uneven power distribution in multiple parallel circuits leading to circulating current, large DC ripple and poor power quality, and weak anti-interference and surge resistance.

[0005] To address the aforementioned problems, this invention provides a photovoltaic DC-DC boost isolation device, comprising a photovoltaic input combiner unit, an EMI filter unit, a soft-start anti-surge unit, an isolated DC-DC boost main topology unit, a high-frequency isolation transformer, a rectification and regulation unit, an output filter unit, a sampling and detection unit, a main control drive unit, and a protection unit. The input terminal of the photovoltaic input combiner unit is connected to the output terminal of the photovoltaic array, and the output terminal of the photovoltaic input combiner unit is connected to the input terminal of the EMI filter unit. The output terminal of the EMI filter unit is connected to the input terminal of the soft-start anti-surge unit. The output terminal of the soft-start anti-surge unit is connected to the primary input terminal of the isolated DC-DC boost main topology unit. The primary output terminal of the isolated DC-DC boost main topology unit is connected to the primary winding of the high-frequency isolation transformer. The secondary winding of the high-frequency isolation transformer is connected to the input terminal of the rectification and regulation unit. The output terminal of the rectification and regulation unit is connected to the input terminal of the output filter unit. The output terminal of the output filter unit serves as the high-voltage DC output bus of the device. The sampling and detection unit is connected in parallel to the input side of the photovoltaic input combiner unit, the primary and secondary sides of the high-frequency isolation transformer, and the output bus of the output filter unit. The signal output terminal of the sampling and detection unit is connected to the sampling input terminal of the main control drive unit. The drive signal output terminal of the main control drive unit is connected to the switching control terminal of the isolation DC-DC boost main topology unit. The protection unit is bidirectionally connected to both the main control drive unit and the sampling and detection unit.

[0006] The photovoltaic DC boost isolation device provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: The EMI filtering unit is used to filter out high-frequency noise, common-mode interference, and differential-mode ripple on the photovoltaic DC side, and to suppress lightning surges and voltage spikes. The soft-start surge protection unit is used to slowly build up voltage upon power-up, suppressing capacitor charging inrush current. The high-frequency isolation transformer is the core component for achieving electrical isolation and voltage boosting. Electromagnetic coupling and electrical isolation are achieved between the primary and secondary windings via a magnetic core. The electrical isolation characteristics of the high-frequency isolation transformer are one of the core technological advantages of this invention. The rectification and voltage regulation unit is used to rectify the high-frequency AC voltage output from the secondary side of the high-frequency isolation transformer into a high-voltage DC voltage. The output filtering unit is used to filter out high-frequency ripple on the high-voltage output side, smooth the DC bus voltage, reduce output pulsation, and improve grid-connected power quality. The sampling and detection unit is used to collect electrical and temperature parameters of key components of the device in real time, providing a data basis for the closed-loop control of the main control drive unit. The main control drive unit is the core of the device's intelligent control.

[0007] This invention achieves complete electrical isolation between input and output through a high-frequency isolation transformer, completely blocking the transmission of leakage current, short circuit, surge, and common-mode interference from the photovoltaic side to the high-voltage grid-connected side, eliminating the risks of DC arcing, high-voltage backflash, and equipment breakdown, and greatly improving the operational safety of photovoltaic power plants.

[0008] This invention adopts an input parallel current sharing and output series voltage sharing architecture, combined with digital closed-loop equalization control, to solve the problems of power imbalance, voltage deviation and internal circulating current in traditional multi-branch boost converters, reduce device heat generation and improve the overall operating efficiency and service life.

[0009] This invention can adapt to complex operating conditions such as large fluctuations in photovoltaic day and night illumination, temperature changes, and partial shading. It has a wide voltage regulation range, strong surge resistance and anti-interference ability, and stable long-term outdoor operation with a low failure rate.

[0010] Furthermore, the isolated DC-DC boost main topology unit adopts an LLC resonant soft-switching topology, including a primary-side full-bridge inverter circuit, a resonant capacitor, a resonant inductor, and a transformer magnetizing inductor. The primary-side full-bridge inverter circuit consists of four sets of power switches forming a full-bridge structure, with the control terminals of the four sets of power switches connected to the drive signal output terminals of the main control drive unit. The resonant capacitor and resonant inductor are connected in series between the output terminal of the primary-side full-bridge inverter circuit and the transformer magnetizing inductor. The LLC resonant soft-switching topology achieves zero-voltage turn-on and zero-current turn-off by adjusting the switching frequency.

[0011] Furthermore, the photovoltaic input busbar unit includes a multi-input busbar and a current sharing circuit. The multi-input busbar is used to combine the currents of multiple photovoltaic branches, and the current sharing circuit is used to balance the input current of each photovoltaic branch.

[0012] Furthermore, the EMI filtering unit includes a common-mode filter inductor and a differential-mode filter capacitor. The common-mode filter inductor is connected in series in the lines of the positive and negative input terminals, and the differential-mode filter capacitor is connected in parallel at the output terminal of the common-mode filter inductor. It is used to filter out high-frequency noise, common-mode interference and differential-mode ripple on the photovoltaic DC side, and suppress lightning surges and voltage spikes.

[0013] Furthermore, the soft-start anti-surge unit includes a soft-start resistor and a bypass relay. The soft-start resistor is connected in series in the input circuit to limit the capacitor charging current when powered on. The bypass relay is connected in parallel across the two ends of the soft-start resistor to bypass and short-circuit the soft-start resistor after the soft start is completed.

[0014] Furthermore, the high-frequency isolation transformer includes a primary winding, a secondary winding, and a magnetic core. A magnetic core is provided between the primary winding and the secondary winding, and the magnetic core is used to achieve electromagnetic coupling and electrical isolation.

[0015] Furthermore, the rectification and voltage regulation unit includes a high-voltage rectifier diode group and a voltage regulation control circuit. The high-voltage rectifier diode group is composed of multiple fast recovery diodes connected in series or in parallel, and is used to rectify the high-frequency AC voltage output from the secondary side of the high-frequency isolation transformer into a high-voltage DC voltage. The voltage regulation control circuit is connected to the output terminal of the high-voltage rectifier diode group and is used to suppress output voltage drift.

[0016] Furthermore, the output filtering unit includes an LC filter circuit, which consists of a filter inductor and a filter capacitor, used to filter out high-frequency ripple on the high-voltage output side and smooth the DC bus voltage.

[0017] Furthermore, the sampling and detection unit includes an input voltage sensor, an input current sensor, a transformer temperature sensor, an output voltage sensor, and an output current sensor; the input voltage sensor is connected in parallel to the input side of the device, the input current sensor is connected in series in the input circuit of the device, the transformer temperature sensor is attached to the magnetic core surface of the high-frequency isolation transformer, the output voltage sensor is connected in parallel to the output bus of the output filter unit, and the output current sensor is connected in series in the output circuit of the output filter unit.

[0018] Furthermore, the main control drive unit includes a DSP digital controller and a drive circuit. The sampling input terminal of the DSP digital controller is connected to the signal output terminal of the sampling detection unit, the PWM output terminal of the DSP digital controller is connected to the input terminal of the drive circuit, and the output terminal of the drive circuit is connected to the switching control terminal of the isolated DC-DC boost main topology unit. The DSP digital controller has a built-in MPPT power tracking module, a multi-channel module power self-balancing module, and a dynamic voltage regulation module. The protection unit includes an input undervoltage protection module, an input overvoltage protection module, an output overvoltage protection module, an output overcurrent protection module, a short circuit protection module, an overheat protection module, and a ground leakage protection module; each protection module is bidirectionally connected to the main control drive unit. Attached Figure Description

[0019] Figure 1 This is a system block diagram of a photovoltaic DC boost isolation device according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] See Figure 1This invention discloses a photovoltaic DC-DC boost isolation device, comprising a photovoltaic input combiner unit, an EMI filter unit, a soft-start anti-surge unit, an isolated DC-DC boost main topology unit, a high-frequency isolation transformer, a rectification and regulation unit, an output filter unit, a sampling and detection unit, a main control drive unit, and a protection unit. The input terminal of the photovoltaic input combiner unit is connected to the output terminal of the photovoltaic array, and the output terminal of the photovoltaic input combiner unit is connected to the input terminal of the EMI filter unit. The output terminal of the EMI filter unit is connected to the input terminal of the soft-start anti-surge unit. The output terminal of the soft-start anti-surge unit is connected to the primary input terminal of the isolated DC-DC boost main topology unit. The primary output terminal of the isolated DC-DC boost main topology unit is connected to the primary winding of the high-frequency isolation transformer. The secondary winding of the high-frequency isolation transformer is connected to the input terminal of the rectification and regulation unit. The output terminal of the rectification and regulation unit is connected to the input terminal of the output filter unit. The output terminal of the output filter unit serves as the high-voltage DC output bus of the device. The sampling and detection unit is connected in parallel to the input side of the photovoltaic input combiner unit, the primary and secondary sides of the high-frequency isolation transformer, and the output bus of the output filter unit. The signal output terminal of the sampling and detection unit is connected to the sampling input terminal of the main control drive unit. The drive signal output terminal of the main control drive unit is connected to the switching control terminal of the isolation DC-DC boost main topology unit. The protection unit is bidirectionally connected to both the main control drive unit and the sampling and detection unit.

[0026] The EMI filter unit is used to filter out high-frequency noise, common-mode interference, and differential-mode ripple on the photovoltaic DC side, and to suppress lightning surges and voltage spikes. The soft-start surge protection unit is used to slowly build up voltage during power-up, suppressing capacitor charging inrush current. The high-frequency isolation transformer is the core component for achieving electrical isolation and voltage boost. The high-frequency isolation transformer includes a primary winding, a secondary winding, and a magnetic core. Electromagnetic coupling and electrical isolation are achieved between the primary and secondary windings through the magnetic core. The electrical isolation characteristics of the high-frequency isolation transformer are one of the core technical advantages of this invention. Through the high-frequency isolation transformer, complete electrical isolation is achieved between the input side (photovoltaic side) and the output side (high-voltage DC side), with no direct electrical connection. This characteristic completely blocks the path of photovoltaic side leakage to ground, short circuit to ground, high-voltage backflash, and common-mode interference to the high-voltage grid-connected side, eliminating safety hazards such as DC arcing, equipment breakdown, and system tripping, and greatly improving the operational safety of the photovoltaic power station.

[0027] The rectification and voltage regulation unit rectifies the high-frequency AC voltage output from the secondary side of the high-frequency isolation transformer into a high-voltage DC voltage. The output filtering unit filters out high-frequency ripple on the high-voltage output side, smooths the DC bus voltage, reduces output pulsation, and improves grid-connected power quality. The sampling and detection unit collects electrical and temperature parameters from key components of the device in real time, providing a data foundation for the closed-loop control of the main control and drive unit. The main control and drive unit is the core of the device's intelligent control.

[0028] This invention achieves complete electrical isolation between input and output through a high-frequency isolation transformer, completely blocking the transmission of leakage current, short circuit, surge, and common-mode interference from the photovoltaic side to the high-voltage grid-connected side, eliminating the risks of DC arcing, high-voltage backflash, and equipment breakdown, and greatly improving the operational safety of photovoltaic power plants.

[0029] This invention adopts an input parallel current sharing and output series voltage sharing architecture, combined with digital closed-loop equalization control, to solve the problems of power imbalance, voltage deviation and internal circulating current in traditional multi-branch boost converters, reduce device heat generation and improve the overall operating efficiency and service life.

[0030] This invention can adapt to complex operating conditions such as large fluctuations in photovoltaic day and night illumination, temperature changes, and partial shading. It has a wide voltage regulation range, strong surge resistance and anti-interference ability, and stable long-term outdoor operation with a low failure rate.

[0031] Furthermore, the isolated DC-DC boost main topology unit adopts an LLC resonant soft-switching topology, including a primary-side full-bridge inverter circuit, a resonant capacitor, a resonant inductor, and a transformer magnetizing inductor. The primary-side full-bridge inverter circuit consists of four sets of power switches forming a full-bridge structure, with the control terminals of the four sets of power switches connected to the drive signal output terminals of the main control drive unit. The resonant capacitor and resonant inductor are connected in series between the output terminal of the primary-side full-bridge inverter circuit and the transformer magnetizing inductor. The LLC resonant soft-switching topology achieves zero-voltage turn-on and zero-current turn-off by adjusting the switching frequency.

[0032] This invention relies on LLC resonant topology, transformer boosting, and module series superposition to achieve ultra-high voltage gain, which can stably boost the low-voltage wide-range photovoltaic voltage to 1000V / 1500V high-voltage DC, adapting to the construction standards of the new generation of high-voltage photovoltaic power stations.

[0033] This invention employs LLC resonant soft switching to achieve zero-loss ZVS / ZCS switching, significantly reducing switching losses and electromagnetic interference; the multi-stage filtering structure results in extremely low output DC ripple, excellent power quality, and improved MPPT tracking accuracy and grid connection stability of the downstream inverter.

[0034] The working principle of the LLC resonant soft-switching topology is as follows: The main control drive unit outputs a PWM drive signal with a fixed duty cycle (approximately 50%), controlling four sets of power switching transistors to alternately conduct, inverting the input DC voltage into a high-frequency square wave AC voltage. This high-frequency square wave voltage is applied to the LLC resonant network, which consists of a resonant capacitor, a resonant inductor, and a transformer magnetizing inductance. By adjusting the switching frequency, the resonant network operates near its resonant point, achieving zero-voltage turn-on and zero-current turn-off of the power switching transistors. This switching technology significantly reduces switching losses, bringing them almost to zero, resulting in a significant improvement in overall efficiency. It also reduces electromagnetic interference and extends the lifespan of the power devices.

[0035] Another significant advantage of the LLC resonant topology is its wide input voltage adaptability. When the output voltage of the photovoltaic array fluctuates over a wide range, the main control drive unit can maintain the stability of the output voltage by adjusting the switching frequency without changing the duty cycle. It has excellent voltage regulation characteristics and is suitable for photovoltaic wide-range fluctuation conditions throughout the day.

[0036] Furthermore, the photovoltaic input busbar unit includes a multi-input busbar and a current sharing circuit. The multi-input busbar is used to combine the currents of multiple photovoltaic branches, and the current sharing circuit is used to balance the input current of each photovoltaic branch.

[0037] This invention provides a photovoltaic input busbar unit for combining and sharing the current from multiple photovoltaic branches. In a preferred embodiment, the photovoltaic input busbar unit includes a multi-input busbar and a current sharing circuit. The multi-input busbar combines the current from multiple photovoltaic branches, with each branch connected to the busbar via an independent fuse and a reverse-biased diode. The current sharing circuit balances the input current of each photovoltaic branch, preventing overload in a single branch due to inconsistent component parameters. The current sharing circuit can employ resistive current sharing or active current sharing methods to ensure balanced current distribution across all branches.

[0038] Furthermore, the EMI filtering unit includes a common-mode filter inductor and a differential-mode filter capacitor. The common-mode filter inductor is connected in series in the lines of the positive and negative input terminals, and the differential-mode filter capacitor is connected in parallel at the output terminal of the common-mode filter inductor. It is used to filter out high-frequency noise, common-mode interference and differential-mode ripple on the photovoltaic DC side, and suppress lightning surges and voltage spikes.

[0039] In a preferred embodiment of the present invention, the EMI filtering unit includes a common-mode filter inductor and a differential-mode filter capacitor. The common-mode filter inductor is connected in series in the lines connecting the positive and negative input terminals, presenting a high impedance to common-mode interference signals and effectively suppressing common-mode current. The differential-mode filter capacitor is connected in parallel at the output terminal of the common-mode filter inductor, forming a low-impedance path for differential-mode interference signals and filtering out high-frequency differential-mode ripple. The common-mode filter inductor and the differential-mode filter capacitor together constitute a two-stage EMI filtering network, purifying the input power supply quality and protecting downstream power devices from voltage spikes.

[0040] Furthermore, the soft-start anti-surge unit includes a soft-start resistor and a bypass relay. The soft-start resistor is connected in series in the input circuit to limit the capacitor charging current when powered on. The bypass relay is connected in parallel across the two ends of the soft-start resistor to bypass and short-circuit the soft-start resistor after the soft start is completed.

[0041] In a preferred embodiment of the present invention, the soft-start surge protection unit includes a soft-start resistor and a bypass relay. The soft-start resistor is connected in series in the input circuit. During the initial power-up phase, current flows through the soft-start resistor to charge the filter capacitor. Due to the current-limiting effect of the resistor, the charging current is limited to a safe range, preventing the large current at startup from damaging the switching devices. Once the voltage of the filter capacitor reaches a set value, the bypass relay closes, short-circuiting the soft-start resistor. Current flows through the contacts of the bypass relay, eliminating power loss on the resistor and improving overall efficiency.

[0042] Furthermore, the high-frequency isolation transformer includes a primary winding, a secondary winding, and a magnetic core. A magnetic core is provided between the primary winding and the secondary winding, and the magnetic core is used to achieve electromagnetic coupling and electrical isolation.

[0043] The turns ratio of the primary winding to the secondary winding is determined according to the required voltage boost factor. The insulation withstand voltage between the primary and secondary windings is not less than DC 6000V, achieving a voltage gain of several to tens of times. The high-frequency isolation transformer uses a high-frequency ferrite core or an amorphous nanocrystalline core, characterized by low high-frequency loss and high saturation magnetic flux density. Multiple layers of insulation barriers are installed between the primary and secondary windings to ensure electrical safety under high-voltage conditions.

[0044] Furthermore, the rectification and voltage regulation unit includes a high-voltage rectifier diode group and a voltage regulation control circuit. The high-voltage rectifier diode group is composed of multiple fast recovery diodes connected in series or in parallel, and is used to rectify the high-frequency AC voltage output from the secondary side of the high-frequency isolation transformer into a high-voltage DC voltage. The voltage regulation control circuit is connected to the output terminal of the high-voltage rectifier diode group and is used to suppress output voltage drift.

[0045] In a preferred embodiment of the present invention, the rectification and voltage regulation unit includes a high-voltage rectifier diode group and a voltage regulation control circuit. The high-voltage rectifier diode group has the characteristics of short reverse recovery time and high withstand voltage, making it suitable for high-frequency high-voltage rectification applications. The voltage regulation control circuit is connected to the output terminal of the high-voltage rectifier diode group and suppresses output voltage drift through feedback regulation to ensure a constant high-voltage output.

[0046] Furthermore, the output filtering unit includes an LC filter circuit, which consists of a filter inductor and a filter capacitor, used to filter out high-frequency ripple on the high-voltage output side and smooth the DC bus voltage.

[0047] In a preferred embodiment of the present invention, the output filtering unit includes an LC filter circuit, which consists of a filter inductor and a filter capacitor. The filter inductor is connected in series in the positive output line, presenting high impedance to high-frequency ripple current; the filter capacitor is connected in parallel at the output terminal, forming a low-impedance bypass for high-frequency ripple voltage. The LC filter circuit constitutes a second-order low-pass filter, which can effectively filter out ripple components at the switching frequency and its harmonics, making the output DC voltage smooth and pure.

[0048] Furthermore, the sampling and detection unit includes an input voltage sensor, an input current sensor, a transformer temperature sensor, an output voltage sensor, and an output current sensor; the input voltage sensor is connected in parallel to the input side of the device, the input current sensor is connected in series in the input circuit of the device, the transformer temperature sensor is attached to the magnetic core surface of the high-frequency isolation transformer, the output voltage sensor is connected in parallel to the output bus of the output filter unit, and the output current sensor is connected in series in the output circuit of the output filter unit.

[0049] In a preferred embodiment of the present invention, the sampling and detection unit includes an input voltage sensor, an input current sensor, a transformer temperature sensor, an output voltage sensor, and an output current sensor. The input voltage sensor is connected in parallel to the input side of the device for real-time monitoring of the output voltage of the photovoltaic array; the input current sensor is connected in series in the input circuit of the device for real-time monitoring of the input current; the transformer temperature sensor is attached to the surface of the magnetic core of the high-frequency isolation transformer for real-time monitoring of the transformer temperature to prevent overheating; the output voltage sensor is connected in parallel to the output bus of the output filter unit for real-time monitoring of the high-voltage DC output voltage; and the output current sensor is connected in series in the output circuit of the output filter unit for real-time monitoring of the output current. Each sensor converts the acquired analog signals into standard electrical signals and sends them to the main control drive unit for processing.

[0050] Furthermore, the main control drive unit includes a DSP digital controller and a drive circuit. The sampling input terminal of the DSP digital controller is connected to the signal output terminal of the sampling detection unit, the PWM output terminal of the DSP digital controller is connected to the input terminal of the drive circuit, and the output terminal of the drive circuit is connected to the switching control terminal of the isolated DC-DC boost main topology unit. The DSP digital controller has a built-in MPPT power tracking module, a multi-channel module power self-balancing module, and a dynamic voltage regulation module.

[0051] In a preferred embodiment of the present invention, the main control drive unit includes a DSP digital controller and a drive circuit. The sampling input terminal of the DSP digital controller is connected to the signal output terminal of the sampling detection unit, the PWM output terminal of the DSP digital controller is connected to the input terminal of the drive circuit, and the output terminal of the drive circuit is connected to the switching control terminal of the isolated DC-DC boost main topology unit.

[0052] Furthermore, the protection unit includes an input undervoltage protection module, an input overvoltage protection module, an output overvoltage protection module, an output overcurrent protection module, a short circuit protection module, an overheat protection module, and a ground leakage protection module; each protection module is bidirectionally connected to the main control drive unit.

[0053] When any fault is triggered, the protection unit sends a fault signal to the main control drive unit, which then locks the PWM output and controls the device to stop, increasing the device's safety.

[0054] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A photovoltaic DC boost isolation device, characterized in that, The system includes a photovoltaic input combiner unit, an EMI filter unit, a soft-start anti-surge unit, an isolated DC-DC boost main topology unit, a high-frequency isolation transformer, a rectification and voltage regulation unit, an output filter unit, a sampling and detection unit, a main control drive unit, and a protection unit. The input terminal of the photovoltaic input combiner unit is connected to the output terminal of the photovoltaic array; the output terminal of the photovoltaic input combiner unit is connected to the input terminal of the EMI filter unit; the output terminal of the EMI filter unit is connected to the input terminal of the soft-start anti-surge unit; the output terminal of the soft-start anti-surge unit is connected to the primary input terminal of the isolated DC-DC boost main topology unit; the primary output terminal of the isolated DC-DC boost main topology unit is connected to the primary winding of the high-frequency isolation transformer; the secondary winding of the high-frequency isolation transformer is connected to the input terminal of the rectification and voltage regulation unit; the output terminal of the rectification and voltage regulation unit is connected to the input terminal of the output filter unit; and the output terminal of the output filter unit serves as the high-voltage DC output bus of the device. The sampling and detection unit is connected in parallel to the input side of the photovoltaic input combiner unit, the primary and secondary sides of the high-frequency isolation transformer, and the output bus of the output filter unit. The signal output terminal of the sampling and detection unit is connected to the sampling input terminal of the main control drive unit. The drive signal output terminal of the main control drive unit is connected to the switching control terminal of the isolation DC-DC boost main topology unit. The protection unit is bidirectionally connected to both the main control drive unit and the sampling and detection unit.

2. The photovoltaic DC boost isolation device according to claim 1, characterized in that, The isolated DC-DC boost main topology unit adopts an LLC resonant soft-switching topology, including a primary-side full-bridge inverter circuit, a resonant capacitor, a resonant inductor, and a transformer magnetizing inductor. The primary-side full-bridge inverter circuit consists of four sets of power switches forming a full-bridge structure, with the control terminals of the four sets of power switches connected to the drive signal output terminals of the main control drive unit. The resonant capacitor and resonant inductor are connected in series between the output terminal of the primary-side full-bridge inverter circuit and the transformer magnetizing inductor. The LLC resonant soft-switching topology achieves zero-voltage turn-on and zero-current turn-off by adjusting the switching frequency.

3. The photovoltaic DC boost isolation device according to claim 2, characterized in that, The photovoltaic input busbar unit includes a multi-input busbar and a current sharing circuit. The multi-input busbar is used to combine the currents of multiple photovoltaic branches, and the current sharing circuit is used to balance the input current of each photovoltaic branch.

4. The photovoltaic DC boost isolation device according to claim 3, characterized in that, The EMI filtering unit includes a common-mode filter inductor and a differential-mode filter capacitor. The common-mode filter inductor is connected in series in the lines of the positive and negative input terminals, and the differential-mode filter capacitor is connected in parallel at the output terminal of the common-mode filter inductor. It is used to filter out high-frequency noise, common-mode interference and differential-mode ripple on the photovoltaic DC side, and suppress lightning surges and voltage spikes.

5. The photovoltaic DC boost isolation device according to claim 4, characterized in that, The soft-start anti-impact unit includes a soft-start resistor and a bypass relay. The soft-start resistor is connected in series in the input circuit to limit the capacitor charging current when powered on. The bypass relay is connected in parallel across the two ends of the soft-start resistor to bypass and short-circuit the soft-start resistor after the soft start is completed.

6. The photovoltaic DC boost isolation device according to claim 5, characterized in that, The high-frequency isolation transformer includes a primary winding, a secondary winding, and a magnetic core. A magnetic core is provided between the primary winding and the secondary winding, and the magnetic core is used to achieve electromagnetic coupling and electrical isolation.

7. The photovoltaic DC boost isolation device according to claim 6, characterized in that, The rectifier and voltage regulator unit includes a high-voltage rectifier diode group and a voltage regulation control circuit. The high-voltage rectifier diode group is composed of multiple fast recovery diodes connected in series or in parallel, and is used to rectify the high-frequency AC voltage output from the secondary side of the high-frequency isolation transformer into a high-voltage DC voltage. The voltage regulation control circuit is connected to the output terminal of the high-voltage rectifier diode group and is used to suppress output voltage drift.

8. The photovoltaic DC boost isolation device according to claim 7, characterized in that, The output filtering unit includes an LC filter circuit, which consists of a filter inductor and a filter capacitor. It is used to filter out high-frequency ripple on the high-voltage output side and smooth the DC bus voltage.

9. The photovoltaic DC boost isolation device according to claim 8, characterized in that, The sampling and detection unit includes an input voltage sensor, an input current sensor, a transformer temperature sensor, an output voltage sensor, and an output current sensor. The input voltage sensor is connected in parallel to the input side of the device, the input current sensor is connected in series in the input circuit of the device, the transformer temperature sensor is attached to the magnetic core surface of the high-frequency isolation transformer, the output voltage sensor is connected in parallel to the output bus of the output filter unit, and the output current sensor is connected in series in the output circuit of the output filter unit.

10. The photovoltaic DC boost isolation device according to claim 9, characterized in that, The main control drive unit includes a DSP digital controller and a drive circuit. The sampling input terminal of the DSP digital controller is connected to the signal output terminal of the sampling detection unit, the PWM output terminal of the DSP digital controller is connected to the input terminal of the drive circuit, and the output terminal of the drive circuit is connected to the switching control terminal of the isolated DC-DC boost main topology unit. The DSP digital controller has a built-in MPPT power tracking module, a multi-channel module power self-balancing module, and a dynamic voltage regulation module. The protection unit includes an input undervoltage protection module, an input overvoltage protection module, an output overvoltage protection module, an output overcurrent protection module, a short circuit protection module, an overheat protection module, and a ground leakage protection module; each protection module is bidirectionally connected to the main control drive unit.

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