Photovoltaic adapter suitable for direct current light stacking system

Abstract

The invention relates to the technical field of power electronics and new energy power generation, and discloses a photovoltaic adapter suitable for a direct-current stacked light system, which comprises an input filter, an output filter, a BOOST boost, an input anti-reverse connection circuit, an output anti-reverse connection circuit and a buffer circuit, the booster circuit is respectively connected with an input filter, an input anti-reverse-connection circuit, an output filter, an output anti-reverse-connection circuit and a buffer circuit; the input filter circuit is connected with the input anti-reverse-connection circuit; and the output filter circuit is connected with the output anti-reverse connection and buffer circuit. According to the invention, the input is prevented from being reversely connected, the output is prevented from being reversely connected, an MOS tube in the output buffer circuit is normally on or normally off, and the loss is small; mOS tubes in the input anti-reverse-connection circuit and the output anti-reverse-connection circuit have low requirements on driving, do not need to be quickly turned on, ensure the turn-off timeliness, do not need to add a driving chip, and are low in cost; for a communication base station, MOS tube characteristics are used for buffering, the tube turn-on time is prolonged so as to suppress an instantaneous peak generated by charging of an output capacitor, and the impact of output parallel connection of multiple paths of adapters on a direct current bus is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics and new energy power generation, and in particular relates to a photovoltaic adapter suitable for a DC stacking system. Background Art

[0002] Solar energy is the cleanest renewable energy source in the world with the greatest prospects for large-scale development. In the current environment of excessive consumption of primary energy and serious pollution, the use of solar energy has attracted more and more attention.

[0003] With the continuous advancement of solar power generation technology and the reduction of costs, the application prospects of DC stacking technology in the field of base station power supply are very broad, with the advantages of small shielding power loss, safety and reliability, intelligent operation and maintenance, long life, dynamic voltage adjustment, and convenient construction. In the future, with the popularization of 5G networks and the increase in the number of base stations, DC stacking technology will be more widely used and contribute to the sustainable development of the communications industry.

[0004] For communication base stations with the characteristics of wide distribution, small space, low load, and many obstructions, it is more suitable to configure an independent photovoltaic adapter for each photovoltaic module to convert the module voltage to -48V, and then connect it to the DC output busbar of the switching power supply after merging in the combiner box to power the DC load. For communication base stations, the promotion and application of photovoltaic adapters can reduce the input of mains electricity and reduce the carbon emissions of base stations on the one hand, and it is also convenient for the power supply design of remote sites on the other hand.

[0005] At present, the most common photovoltaic adapter adopts asynchronous BOOST topology, with a small number of driving power supplies and driving circuits. However, since the freewheeling tube uses a diode, the entire adapter will have high losses. When lightly loaded, the adapter is in DCM mode (Discontinuous Conduction Mode), the inductor current is intermittent, and the output voltage ripple is high. At present, there is also a solution to replace the freewheeling tube with a MOS tube and improve it to a synchronous BOOST topology, which will improve efficiency. However, after the new MOS tube is introduced, a supporting driving circuit needs to be added, which is relatively costly. The current common solution is to use a bootstrap circuit.

[0006] For the bootstrap circuit, the BOOST topology itself does not have a breakpoint. When a circuit fails, the input and output circuits cannot be completely disconnected. Therefore, the circuit needs to have a breakpoint to ensure the safety of the subsequent load. At the same time, due to the small size and power of the photovoltaic adapter module and the large number of on-site installations, it is very likely that the input and output terminals will be connected in reverse, which will affect the 48V bus of the communication base station and even cause damage to the adapter. Therefore, the adapter needs to have the function of preventing input and output reverse connection. Summary of the invention

[0007] In order to solve the above technical problems, an embodiment of the present invention proposes a photovoltaic adapter suitable for a DC stacked light system, which realizes timely shutdown in case of faults and protection in case of reverse connection of input and output.

[0008] The purpose of the present invention can be achieved through the following technical solutions.

[0009] A photovoltaic adapter suitable for a DC stacked light system comprises an input filter circuit, an output filter circuit, a BOOST boost circuit, an input reverse connection protection circuit, and an output reverse connection protection and buffer circuit.

[0010] The connection relationship is as follows: the BOOST boost circuit is respectively connected to the input filter circuit, the input reverse connection protection circuit, the output filter circuit, the output reverse connection protection and buffer circuit; the input filter circuit is connected to the input reverse connection protection circuit; the output filter circuit is connected to the output reverse connection protection and buffer circuit.

[0011] Preferably, the BOOST boost circuit is composed of an energy storage inductor L, a main control MOS tube Q1 and a freewheeling MOS tube Q2.

[0012] The input reverse connection protection circuit is composed of the input reverse connection protection MOS tube Q3.

[0013] The input filter circuit is composed of filter capacitor Cin.

[0014] The output reverse connection protection and buffer circuit is composed of an output reverse connection protection MOS tube Q4 and an output buffer MOS tube Q5.

[0015] The output filter circuit is composed of filter capacitor Cout.

[0016] The connection relationship is: the D pole of Q3 is connected to the input negative pole, and the S pole is respectively connected to one end of Cin, one end of Cout, the S pole of Q1, and the S pole of Q4; the other end of Cin is connected to the input positive pole and one end of L; the D pole of Q1 is connected to the other end of L and the S pole of Q2; the D pole of Q2 is connected to the output positive pole and the other end of Cout; the D pole of Q4 is connected to the D pole of Q5; and the S pole of Q5 is connected to the output negative pole.

[0017] Preferably, Q3 is controlled by a MCU.

[0018] When the input is reversed: if the output is not connected to the bus, the switching power supply cannot be started and Q3 will not be turned on; if the output is connected to the bus, the switching power supply will be started, but the reverse input will make the input voltage negative and Q3 will not be turned on.

[0019] Preferably, Q4 provides a break point for the loop.

[0020] Preferably, when multiple outputs are connected to a 48V bus, the charging of Cout will produce an instantaneous current impact on the bus at the moment of power-on. To solve this problem, the startup charging current is limited by reducing the Q5 turn-on time and using the MOS tube characteristics for buffering.

[0021] The present invention has the following beneficial effects: the working modes of the MOS tubes in the input anti-reverse connection circuit, the output anti-reverse connection circuit and the output buffer circuit are normally on or normally off, and the loss is relatively small; the MOS tubes in the input anti-reverse connection circuit and the output anti-reverse connection circuit have low requirements on driving, and do not require rapid opening, and only need to ensure the timeliness of shutdown, without the need for additional driver chips, thereby reducing costs; for the application scenario of communication base stations, the characteristics of the MOS tubes are used as a buffer, and the instantaneous spikes generated by the charging of the output capacitors are suppressed by extending the opening time of the MOS tubes, thereby reducing the impact on the DC bus when the outputs of the multi-channel adapters are connected in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a system diagram of the present invention.

[0023] Figure 2 It is a circuit topology diagram of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0025] Example: Figures 1-2 As shown, a photovoltaic adapter suitable for a DC stacked light system, the main topology consists of an input filter circuit, an output filter circuit, a BOOST boost circuit, an input reverse connection protection circuit, an output reverse connection protection and buffer circuit, wherein the BOOST boost circuit is composed of an inductor L, a MOS tube Q1 and a MOS tube Q2; the input reverse connection protection circuit is composed of a MOS tube Q3; the output reverse connection protection and buffer circuit is composed of Q4 and Q5, and extending the conduction time of Q5 can achieve startup current limiting protection.

[0026] The startup logic of the MOS tube is as follows: after the switching power supply is powered on and the MCU is started, the input voltage is first detected. Q3 will be turned on only when the input voltage is within a reasonable range and no reverse current is detected. After the MCU detects that there are no abnormalities, it sends an opening signal to Q4 to connect with the next stage, and then lets Q1 and Q2 start to wave.

[0027] The fault shutdown logic of the MOS tube is: when a fault is detected, a blocking signal is immediately issued to shut down Q1, Q2, and Q4; if no input voltage is detected or the current is reversed, Q3 is quickly shut down, and Q1, Q2, and Q4 are also shut down.

[0028] The above embodiments are descriptions of specific implementation methods of the present invention rather than limitations of the present invention. Technical personnel in the relevant technical field may make various changes and modifications to obtain corresponding equivalent technical solutions without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A photovoltaic adapter suitable for a DC stacking system, characterized in that: Including input filter circuit, output filter circuit, BOOST boost circuit, input reverse connection protection circuit, output reverse connection protection and buffer circuit; The connection relationship is as follows: the BOOST boost circuit is respectively connected to the input filter circuit, the input reverse connection protection circuit, the output filter circuit, the output reverse connection protection and buffer circuit; the input filter circuit is connected to the input reverse connection protection circuit; the output filter circuit is connected to the output reverse connection protection and buffer circuit.

2. A photovoltaic adapter suitable for a DC stacking system according to claim 1, characterized in that: The BOOST boost circuit is composed of an energy storage inductor L, a main control MOS tube Q1 and a freewheeling MOS tube Q2; The input reverse connection protection circuit is composed of the input reverse connection protection MOS tube Q3; The input filter circuit is composed of filter capacitor Cin; The output reverse connection protection and buffer circuit is composed of an output reverse connection protection MOS tube Q4 and an output buffer MOS tube Q5; The output filter circuit is composed of filter capacitor Cout; The connection relationship is: the D pole of Q3 is connected to the input negative pole, and the S pole is respectively connected to one end of Cin, one end of Cout, the S pole of Q1, and the S pole of Q4; the other end of Cin is connected to the input positive pole and one end of L; the D pole of Q1 is connected to the other end of L and the S pole of Q2; the D pole of Q2 is connected to the output positive pole and the other end of Cout; the D pole of Q4 is connected to the D pole of Q5; and the S pole of Q5 is connected to the output negative pole.

3. A photovoltaic adapter suitable for a DC stacking system according to claim 2, characterized in that: Q3 is controlled by MCU; When the input is reversed: if the output is not connected to the bus, the switching power supply cannot be started and Q3 will not be turned on; if the output is connected to the bus, the switching power supply will be started, but the reverse input will make the input voltage negative and Q3 will not be turned on.

4. A photovoltaic adapter suitable for a DC stacking system according to claim 2, characterized in that: Q4 provides a breakpoint for the loop.

5. A photovoltaic adapter suitable for a DC stacking system according to claim 2, characterized in that: When multiple outputs are connected to a 48V bus, the charging of Cout will produce an instantaneous current impact on the bus at the moment of power-on. To solve this problem, the Q5 turn-on time is reduced and the MOS tube characteristics are used for buffering to limit the startup charging current.

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