High-voltage wide-range photovoltaic input circuit

Abstract

The utility model relates to a high-voltage wide-range photovoltaic input circuit, which comprises two input circuits, namely an alternating current input circuit and a direct current input circuit. The high-voltage wide-range photovoltaic input circuit adopts a novel circuit form. In a power supply system, a topology of a bridge PFC circuit and a half-bridge LLC circuit is adopted for alternating current; and the direct current adopts a half-bridge LLC topology. According to the utility model, the high-voltage power supply is used for supplying power to a load after inversion, and the voltage input range is controlled to be 300V-1500V, so that the problem of narrow-range high voltage is effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of power conversion, in particular to a high-voltage and wide-range photovoltaic input circuit. Background Art

[0002] Photovoltaic power generation has increasingly become a hot topic for in-depth research and vigorous development in various countries. How to fully utilize the energy converted by photovoltaic arrays and improve photovoltaic conversion efficiency has always been an important direction of photovoltaic system research.

[0003] For example, the document with publication number CN104218831A discloses a topological structure of a photovoltaic inverter with wide DC input and high-voltage AC output. The topological structure of the photovoltaic inverter with wide DC input and high-voltage AC output designed in this invention can realize a wide range of DC input for high-power photovoltaic inverters, improve the DC voltage utilization rate of the photovoltaic array, and reduce circuit power loss; improve the power generation efficiency of the entire photovoltaic system, reduce the AC output current and cable cross-section, reduce the initial investment cost of the power station, and create more benefits for the power station; and provide possibilities for subsequent large-scale wind-solar complementary DC grid-connected systems.

[0004] The typical application range of photovoltaic low voltage is 25V to 145V and 145V to 450V. However, in the case of high voltage input, the narrow input voltage range is limited and cannot meet the photovoltaic high voltage input requirements. Utility Model Content

[0005] (1) Technical problems solved

[0006] In order to solve the above technical problems, the utility model provides a high-voltage, wide-range photovoltaic input circuit, which realizes uninterrupted AC power supply after photovoltaic and battery inputs are inverted, and can be widely used in uninterrupted AC power supply of control equipment.

[0007] (2) Technical solution

[0008] Based on this, the utility model provides the following technical solutions: a high-voltage, wide-range photovoltaic input circuit, which includes two input circuits: an AC input circuit and a DC input circuit;

[0009] The AC input circuit includes a mains input terminal, the mains input terminal is connected to a PFC circuit, the right end of the PFC circuit is connected to a half-bridge LLC circuit, the right end of the half-bridge LLC circuit is connected to an inverter circuit, and the inverter circuit inverts the input voltage and supplies power to the load;

[0010] The DC input circuit includes a photovoltaic DC, which is connected to a half-bridge LLC circuit. The half-bridge LLC circuit resonates with the photovoltaic DC input power and transmits the power to the DC-DC module. The DC-DC module is provided with a battery DC input terminal. The right end of the DC-DC module is connected to an inverter circuit. The inverter circuit inverts the input voltage to achieve the desired output voltage and plays a role in electrical isolation. After inversion, power is supplied to the load.

[0011] The inverter circuit mainly includes four thyristor devices, which are IGBT tube Q6, IGBT tube Q7, IGBT tube Q8, and IGBT tube Q9. The IGBT tube Q6, IGBT tube Q7, IGBT tube Q8, and IGBT tube Q9 are connected in a bridge connection to form a full-bridge structure. The collector of the IGBT tube Q6 and the emitter of the IGBT tube Q8 are connected to the digital controller U dc The emitter of the IGBT tube Q7 and the collector of the IGBT tube Q9 are connected to the left end of the inductor L2, the inductor L2 is connected to the upper end of the capacitor C5, the collector of the IGBT tube Q9 is connected to the lower end of the capacitor C5, and there are inductive loads RL2 on both sides of the right side of the capacitor C5.

[0012] Preferably, the PFC circuit mainly includes four diodes, which are respectively a diode D1, a diode D2, a diode D3, and a diode D4. The diode D1, diode D2, diode D3, and diode D4 are connected in a bridge connection manner. The anode of the diode D1, the anode of the diode D2, the cathode of the diode D3, and the cathode of the diode D4 are connected to the AC220V power supply. The cathode of the diode D1 and the cathode of the diode D2 are connected to the left end of the inductor L1. The right end of the inductor L1 is connected to the anode of the output diode D5 and the collector of the IGBT tube Q1. The anode of the diode D3 and the anode of the diode D4 are connected to the emitter of the IGBT tube Q1. The cathode of the output diode D5 and the emitter of the IGBT tube Q1 are respectively connected to the upper and lower ends of the capacitor C1.

[0013] Preferably, the half-bridge LLC circuit in the AC input circuit mainly includes an IGBT tube Q2 and an IGBT tube Q3, the collector of the IGBT tube Q2 and the emitter of the IGBT tube Q3 are respectively connected to the upper and lower ends of the capacitor C1, the emitter of the IGBT tube Q2 and the collector of the IGBT tube Q3 are connected to the left end of the resonant capacitor Cr1, the right end of the resonant capacitor Cr1 is connected to the left end of the resonant inductor Lr1, the right end of the resonant inductor Lr1 and the emitter of the IGBT tube Q3 are respectively connected to the upper and lower ends of the resonant inductor Lm1, the upper and lower ends of the resonant inductor Lm1 are respectively connected to pins 1 and 2 and pins 3 and 4 of the main transformer T1, pins 3 and 4 of the main transformer T1 are connected to the anode of the rectifier diode D6, pins 7 and 8 of the main transformer T1 are connected to the anode of the rectifier diode D7, and the cathode of the rectifier diode D6 and the cathode of the rectifier diode D7 are respectively connected to the upper and lower ends of the output filter capacitor C3.

[0014] Preferably, the half-bridge LLC circuit in the DC input circuit includes capacitor C2, IGBT tube Q4, IGBT tube Q5, resonant capacitor Cr2, resonant inductor Lr2, resonant inductor Lm2, main transformer T2, rectifier diode D9, rectifier diode D10, and output filter capacitor C4, and the connection structure of the half-bridge LLC circuit in the DC input circuit is consistent with the connection structure of the half-bridge LLC circuit in the AC input circuit.

[0015] Preferably, the output filter capacitor C3 in the half-bridge LLC circuit in the AC input circuit is connected to the anode of the diode D8, and the lower end of the output filter capacitor C3 and the cathode of the diode D8 are connected to the inductive load RL1.

[0016] Preferably, the output filter capacitor C4 in the half-bridge LLC circuit in the DC input circuit is connected to the anode of the diode D11, and the lower end of the output filter capacitor C4 and the cathode of the diode D11 are connected to the inductive load RL1.

[0017] (3) Beneficial effects

[0018] Compared with the existing technology, the present invention provides a high-voltage and wide-range photovoltaic input circuit, which has the following beneficial effects:

[0019] This high-voltage, wide-range photovoltaic input circuit utilizes a novel circuit configuration. In the AC power system, a bridge PFC circuit plus a half-bridge LLC circuit topology is used; the DC circuit uses a half-bridge LLC topology. This achieves the desired output voltage and provides electrical isolation. After inversion, power is supplied to the load, controlling the voltage input range to 300V to 1500V, effectively solving the problem of high voltage in a narrow range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the overall circuit connection diagram of the utility model;

[0021] Figure 2 This is a schematic diagram of the overall circuit connection of the utility model;

[0022] Figure 3 This is a schematic diagram of the connection of the half-bridge LLC circuit of the utility model;

[0023] Figure 4 This is a schematic diagram of the inverter circuit connection of the utility model;

[0024] Figure 5 This is a schematic diagram of the PFC circuit connection of the utility model. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] See also Figure 1-Figure 5 , a high-voltage, wide-range photovoltaic input circuit, specifically including the following embodiments:

[0027] A high-voltage, wide-range photovoltaic input circuit includes two input circuits: an AC input circuit and a DC input circuit. The AC input circuit includes a mains input terminal, which is connected to a PFC circuit. The right end of the PFC circuit is connected to a half-bridge LLC circuit. The right end of the half-bridge LLC circuit is connected to an inverter circuit. The inverter circuit inverts the input voltage and supplies power to the load. The DC input circuit includes a photovoltaic DC, which is connected to the half-bridge LLC circuit. The half-bridge LLC circuit resonates with the photovoltaic DC input power and transmits the power to a DC-DC module. The DC-DC module is provided with a power supply. The DC input end of the battery, the right end of the DC-DC module is connected to the inverter circuit, the inverter circuit inverts the input voltage to achieve the desired output voltage, and plays the role of electrical isolation, after inversion, it supplies power to the load; the inverter circuit mainly includes four thyristor devices, the four thyristor devices are IGBT tube Q6, IGBT tube Q7, IGBT tube Q8, IGBT tube Q9, IGBT tube Q6, IGBT tube Q7, IGBT tube Q8, IGBT tube Q9 are connected in a bridge connection to form a full-bridge structure, the collector of IGBT tube Q6 and the emitter of IGBT tube Q8 are connected to the digital controller U dcThe emitter of IGBT Q7 and the collector of IGBT Q9 are connected to the left end of inductor L2. Inductor L2 is connected to the upper end of capacitor C5. The collector of IGBT Q9 is connected to the lower end of capacitor C5. There are inductive loads RL2 on both sides of the right side of capacitor C5.

[0028] In some embodiments, the PFC circuit mainly includes four diodes, namely diode D1, diode D2, diode D3, and diode D4. Diode D1, diode D2, diode D3, and diode D4 are connected in a bridge connection manner. The anode of diode D1, the anode of diode D2, the cathode of diode D3, and the cathode of diode D4 are connected to the AC220V power supply. The cathode of diode D1 and the cathode of diode D2 are connected to the left end of inductor L1. The right end of inductor L1 is connected to the anode of output diode D5 and the collector of IGBT tube Q1. The anode of diode D3 and the anode of diode D4 are connected to the emitter of IGBT tube Q1. The cathode of output diode D5 and the emitter of IGBT tube Q1 are connected to the upper and lower ends of capacitor C1, respectively. Figure 2 In this example, AC input is fed to the full-bridge rectifier circuit. When IGBT Q1 turns on, the AC current flows only through the inductor, causing the current in inductor L1 to increase. When IGBT Q1 turns off, the current stored in inductor L1 flows through output diode D5 to supply capacitor C1 and inductive load RL1. Simply put, the inductor and switch ensure a constant current flow in the inductor branch, preventing current interruption in the full-bridge rectifier circuit. This improves the power factor.

[0029] In some embodiments, the half-bridge LLC circuit in the AC input circuit mainly includes an IGBT tube Q2 and an IGBT tube Q3. The collector of the IGBT tube Q2 and the emitter of the IGBT tube Q3 are respectively connected to the upper and lower ends of the capacitor C1, the emitter of the IGBT tube Q2 and the collector of the IGBT tube Q3 are connected to the left end of the resonant capacitor Cr1, the right end of the resonant capacitor Cr1 is connected to the left end of the resonant inductor Lr1, the right end of the resonant inductor Lr1 and the emitter of the IGBT tube Q3 are respectively connected to the upper and lower ends of the resonant inductor Lm1, the upper and lower ends of the resonant inductor Lm1 are respectively connected to pins 1 and 2 and pins 3 and 4 of the main transformer T1, pins 3 and 4 of the main transformer T1 are connected to the anode of the rectifier diode D6, pins 7 and 8 of the main transformer T1 are connected to the anode of the rectifier diode D7, and the cathode of the rectifier diode D6 and the rectifier diode The cathode of D7 is respectively connected to the upper and lower ends of the output filter capacitor C3. The half-bridge LLC circuit in the DC input circuit includes capacitor C2, IGBT tube Q4, IGBT tube Q5, resonant capacitor Cr2, resonant inductor Lr2, resonant inductor Lm2, main transformer T2, rectifier diode D9, rectifier diode D10, and output filter capacitor C4. The connection structure of the half-bridge LLC circuit in the DC input circuit is consistent with the connection structure of the half-bridge LLC circuit in the AC input circuit. In the half-bridge LLC circuit in the AC input circuit, the output filter capacitor C3 is connected to the anode of the diode D8, and the lower end of the output filter capacitor C3 and the cathode of the diode D8 are connected to the inductive load RL1. In the half-bridge LLC circuit in the DC input circuit, the output filter capacitor C4 is connected to the anode of the diode D11, and the lower end of the output filter capacitor C4 and the cathode of the diode D11 are connected to the inductive load RL1.

[0030] like Figure 3 As shown, the far right side is the DC input, which serves as the DC voltage output by the PFC and can also serve as the DC power supply input. It can also be the DC voltage of a battery. The DC characteristics of the LLC resonant converter are divided into a zero-voltage operating region and a zero-current operating region. This converter has two resonant frequencies. One is the resonance point of the resonant inductor Lr and the resonant capacitor Cr. The other resonant point is determined by the resonant inductor Lm, the resonant capacitor Cr, and the load conditions. As the load increases, the resonant frequency increases.

[0031] In this application, if Figure 4 As shown in the figure, a single-phase bridge inverter circuit is an electronic circuit that can convert DC power into AC power. It is mainly composed of four thyristor devices, which usually include two diodes and two bidirectional thyristors (using IGBT power switching devices). These devices are connected in a bridge connection manner to form a full-bridge structure, thereby realizing DC to AC conversion.

[0032] 2. Working Mode

[0033] The operation process of a single-phase bridge inverter circuit is divided into several different modes, which mainly depend on the on and off states of each thyristor device. The following are the main operating modes:

[0034] 2.1. IGBT Q6 and IGBT Q8 are turned on, and IGBT Q7 and IGBT Q9 are turned off. When the input DC voltage is in the positive polarity, the thyristors of IGBT Q6 and IGBT Q8 are turned on, while the thyristors of IGBT Q7 and IGBT Q9 are turned off. At this time, the current flows from IGBT Q6 to IGBT Q8, passes through the load, and then returns to the DC power supply.

[0035] The voltage across the load is positive, forming an AC current in the positive half cycle.

[0036] 2.2 IGBT tube Q7 and IGBT tube Q9 are on, IGBT tube Q6 and IGBT tube Q8 are off.

[0037] When the input DC voltage is of reverse polarity, the thyristors of IGBT tubes Q7 and Q9 are turned on, while the thyristors of IGBT tubes Q6 and Q8 are turned off. At this time, the current flows from IGBT tube Q7 to IGBT tube Q9, passes through the load and then returns to the DC power supply. In this state, the voltage across the load is reversed, forming an AC current of the negative half cycle.

[0038] 3. Current direction control

[0039] By controlling the conduction and cutoff of the thyristor, the single-phase bridge inverter circuit can control the direction of the current. In each cycle, the current first flows in one direction (such as from IGBT tube Q6 to IGBT tube Q8), and then changes direction (from IGBT tube Q7 to IGBT tube Q9), thereby forming an alternating AC current.

[0040] 4. Phase control

[0041] By adjusting the firing angle of the thyristor, the conduction time of the thyristor can be controlled, thereby achieving phase control of the AC current. Phase control allows the waveform of the output AC power to be adjusted as needed to meet different application requirements.

[0042] 5. Voltage Regulation Voltage regulation is primarily achieved by changing the conduction time and sequence of the thyristors (SCRs). By precisely controlling the timing and amplitude of the SCR trigger pulses, the output AC voltage can be adjusted, enabling flexible voltage regulation.

[0043] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-voltage, wide-range photovoltaic input circuit, characterized by: There are two types of input circuits in the photovoltaic input circuit: AC input circuit and DC input circuit; The AC input circuit includes a mains input terminal, the mains input terminal is connected to a PFC circuit, the right end of the PFC circuit is connected to a half-bridge LLC circuit, the right end of the half-bridge LLC circuit is connected to an inverter circuit, and the inverter circuit inverts the input voltage and supplies power to the load; The DC input circuit includes a photovoltaic DC, which is connected to a half-bridge LLC circuit. The half-bridge LLC circuit resonates with the photovoltaic DC input power and transmits the power to a DC-DC module. The DC-DC module is provided with a battery DC input terminal. The right end of the DC-DC module is connected to an inverter circuit. The inverter circuit inverts the input voltage and supplies power to the load. The inverter circuit mainly includes four thyristor devices, which are an IGBT tube (Q6), an IGBT tube (Q7), an IGBT tube (Q8), and an IGBT tube (Q9). The IGBT tube (Q6), the IGBT tube (Q7), the IGBT tube (Q8), and the IGBT tube (Q9) are connected in a bridge connection manner to form a full-bridge structure. The collector of the IGBT tube (Q6) and the emitter of the IGBT tube (Q8) are connected to a digital controller (U dc ), the emitter of the IGBT tube (Q7) and the collector of the IGBT tube (Q9) are connected to the left end of the inductor (L2), the inductor (L2) is connected to the upper end of the capacitor (C5), the collector of the IGBT tube (Q9) is connected to the lower end of the capacitor (C5), and there are inductive loads (RL2) on both sides of the right side of the capacitor (C5).

2. A high-voltage, wide-range photovoltaic input circuit according to claim 1, characterized in that: The PFC circuit mainly comprises four diodes, which are respectively a diode (D1), a diode (D2), a diode (D3), and a diode (D4). The diode (D1), the diode (D2), the diode (D3), and the diode (D4) are connected in a bridge connection manner. The anode of the diode (D1), the anode of the diode (D2), the cathode of the diode (D3), and the cathode of the diode (D4) are connected to an AC220V power supply. The cathode of the diode (D1) and the cathode of the diode (D2) are connected to the left end of the inductor (L1). The right end of the inductor (L1) is connected to the anode of the output diode (D5) and the collector of the IGBT tube (Q1). The anode of the diode (D3) and the anode of the diode (D4) are connected to the emitter of the IGBT tube (Q1). The cathode of the output diode (D5) and the emitter of the IGBT tube (Q1) are respectively connected to the upper and lower ends of the capacitor (C1).

3. The high-voltage, wide-range photovoltaic input circuit according to claim 1, characterized in that: The half-bridge LLC circuit in the AC input circuit mainly includes an IGBT tube (Q2) and an IGBT tube (Q3), wherein the collector of the IGBT tube (Q2) and the emitter of the IGBT tube (Q3) are respectively connected to the upper and lower ends of the capacitor (C1), the emitter of the IGBT tube (Q2) and the collector of the IGBT tube (Q3) are connected to the left end of the resonant capacitor (Cr1), the right end of the resonant capacitor (Cr1) is connected to the left end of the resonant inductor (Lr1), the right end of the resonant inductor (Lr1) and the IGBT tube (Q3) are connected to the left end of the resonant inductor (Lr1), and the left end of the resonant inductor (Lr1) is connected to the right end of the resonant inductor (Lr1). The emitter of the resonant inductor (Lm1) is respectively connected to the upper and lower ends of the resonant inductor (Lm1), the upper and lower ends of the resonant inductor (Lm1) are respectively connected to pins 1 and 2 and pins 3 and 4 of the main transformer (T1), pins 3 and 4 of the main transformer (T1) are connected to the anode of the rectifier diode (D6), pins 7 and 8 of the main transformer (T1) are connected to the anode of the rectifier diode (D7), and the cathode of the rectifier diode (D6) and the cathode of the rectifier diode (D7) are respectively connected to the upper and lower ends of the output filter capacitor (C3).

4. The high-voltage, wide-range photovoltaic input circuit according to claim 1, characterized in that: The half-bridge LLC circuit in the DC input circuit comprises a capacitor (C2), an IGBT tube (Q4), an IGBT tube (Q5), a resonant capacitor (Cr2), a resonant inductor (Lr2), a resonant inductor (Lm2), a main transformer (T2), a rectifier diode (D9), a rectifier diode (D10), and an output filter capacitor (C4). The connection structure of the half-bridge LLC circuit in the DC input circuit is consistent with the connection structure of the half-bridge LLC circuit in the AC input circuit.

5. The high-voltage, wide-range photovoltaic input circuit according to claim 3, characterized in that: An output filter capacitor (C3) in a half-bridge LLC circuit in the AC input circuit is connected to the anode of a diode (D8), and a lower end of the output filter capacitor (C3) and a cathode of the diode (D8) are connected to an inductive load (RL1).

6. The high-voltage, wide-range photovoltaic input circuit according to claim 4, characterized in that: An output filter capacitor (C4) in a half-bridge LLC circuit in the DC input circuit is connected to the anode of a diode (D11), and a lower end of the output filter capacitor (C4) and a cathode of the diode (D11) are connected to an inductive load (RL1).

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