阅读说明：本技术 一种o-z源光伏并网逆变器 (O-Z source photovoltaic grid-connected inverter ) 是由 罗韡 吕哲 王琛琛 周明利 陈兴辉 于 2020-11-30 设计创作，主要内容包括：本发明提供了一种O-Z源光伏并网逆变器,包括：光伏列阵模块,作为电源；O-Z源网络,与光伏列阵模块连接,具有电力二极管、耦合电感线圈以及储能电容；逆变桥,与O-Z源网络连接,并与光伏列阵模块的负极连接；滤波电路,与逆变桥相连；以及电网,与滤波电路相连,其中,电力二极管具有阳极与阴极,阳极与光伏列阵模块的正极连接,耦合电感线圈具有N1侧线圈与N2侧线圈,N1侧线圈的同名端与电力二极管的阴极连接,储能电容具有阳极与阴极,阳极与光伏列阵模块的正极连接,阴极与N2侧线圈的同名端连接,N1侧线圈的异名端和N2侧线圈的异名端均与逆变桥连接。(The invention provides an O-Z source photovoltaic grid-connected inverter, which comprises: the photovoltaic array module is used as a power supply; the O-Z source network is connected with the photovoltaic array module and is provided with a power diode, a coupling inductance coil and an energy storage capacitor; the inverter bridge is connected with the O-Z source network and is connected with the negative electrode of the photovoltaic array module; the filter circuit is connected with the inverter bridge; and the power grid is connected with the filter circuit, the power diode is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module, the coupling inductance coil is provided with an N1 side coil and an N2 side coil, the dotted terminal of the N1 side coil is connected with the cathode of the power diode, the energy storage capacitor is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module, the cathode is connected with the dotted terminal of the N2 side coil, and the synonym terminal of the N1 side coil and the synonym terminal of the N2 side coil are both connected with the inverter bridge.)

1. An O-Z source photovoltaic grid-connected inverter, comprising:

the photovoltaic array module is used as a power supply and is provided with a positive electrode and a negative electrode;

the O-Z source network is connected with the photovoltaic array module and is provided with a power diode, a coupling inductance coil and an energy storage capacitor;

the inverter bridge is connected with the O-Z source network and is connected with the negative electrode of the photovoltaic array module;

the filter circuit is connected with the inverter bridge; and

a power grid connected with the filter circuit,

wherein the power diode is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module,

the coupling inductance coil has an N1 side coil and an N2 side coil coupled by a magnetic core, the dotted terminal of the N1 side coil is connected to the cathode of the power diode,

the energy storage capacitor is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module, the cathode is connected with the same name end of the N2 side coil,

the synonym end of the N1 side coil and the synonym end of the N2 side coil are both connected with the inverter bridge,

in the series branch of the power diode and the N1 side coil, the coupled inductor will increase in voltage and exceed the supply voltage when the inverter bridge side is shorted, causing the power diode to turn off, thereby protecting the circuit,

in a series branch of the energy storage capacitor and the coil at the N2 side, the energy storage capacitor absorbs electric energy when one side of the inverter bridge is short-circuited, and releases electric energy when one side of the inverter bridge works.

2. The O-Z source photovoltaic grid-connected inverter according to claim 1, wherein:

wherein the number of turns of the N1 side coil is greater than the number of turns of the N2 side coil.

3. The O-Z source photovoltaic grid-connected inverter according to claim 1, wherein:

the filter circuit comprises three inductors and three capacitors, wherein the inductors are connected with the inverter bridge, each capacitor is correspondingly connected with each inductor to form a filter, and the current output by the inverter bridge is filtered by the filter circuit and then is output as three-phase alternating current.

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to an O-Z source photovoltaic grid-connected inverter.

Background

With the gradual exhaustion of the traditional fossil energy, the green renewable energy is rapidly developed. In the last decade, solar photovoltaic power generation technology has attracted attention from various countries and has become one of the main ways to utilize solar energy. The research on the solar photovoltaic power generation system is developed, and the research has great theoretical and practical significance for relieving energy and environment problems, improving an energy consumption structure, improving the performance of a distributed power generation system and developing the photovoltaic power generation industry.

The power adjustment system of a typical photovoltaic power generation system is divided into a single-stage control structure and a two-stage control structure, because the maximum power point voltage of a photovoltaic cell fluctuates greatly along with the change of the environment, a single-stage inverter has no direct-current boosting link, in order to meet the grid-connected requirement when the maximum power point voltage is needed, the direct-current bus voltage of the inverter needs to track the fluctuation of the maximum power point voltage of the photovoltaic cell in a large range, and the power capacity of the inverter is large; the two-stage inverter increases the power stage number, reduces the total efficiency, has more hardware circuits, has poor reliability and increases the total cost.

The Z source inverter provides a new solution for a photovoltaic grid-connected system, integrates the advantages of a single-stage circuit and a cascade Boost circuit, has a boosting function, increases the reliability of the inverter, is a single-stage system in essence, and has the advantages of simple structure, high efficiency and the like of the single-stage inverter. Thereby gaining the attention of the industry. Meanwhile, the problems of overlarge capacitor voltage stress, limited boosting capacity, large starting input current and the like in the Z source network of the Z source inverter are gradually exposed.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide an O-Z source photovoltaic grid-connected inverter.

The invention provides an O-Z source photovoltaic grid-connected inverter, which is characterized by comprising the following components: the photovoltaic array module is used as a power supply and is provided with a positive electrode and a negative electrode; the O-Z source network is connected with the photovoltaic array module and is provided with a power diode, a coupling inductance coil and an energy storage capacitor; the inverter bridge is connected with the O-Z source network and is connected with the negative electrode of the photovoltaic array module; the filter circuit is connected with the inverter bridge; and a power grid connected with the filter circuit, wherein the power diode is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module, the coupling inductance coil is provided with an N1 side coil and an N2 side coil which are coupled through a magnetic core, the dotted terminal of the N1 side coil is connected with the cathode of the power diode, the energy storage capacitor is provided with an anode and a cathode, the anode is connected with the anode of the photovoltaic array module, the cathode is connected with the dotted terminal of the N2 side coil, the synonym terminal of the N1 side coil and the synonym terminal of the N2 side coil are both connected with the inverter bridge, in the series branch of the power diode and the N1 side coil, the coupling inductor will increase the voltage above the supply voltage when the inverter bridge side is shorted, causing the power diode to turn off, thereby protecting the circuit, in a series branch of the energy storage capacitor and the coil at the N2 side, the energy storage capacitor absorbs electric energy when one side of the inverter bridge is short-circuited, and releases the electric energy when one side of the inverter bridge works.

The O-Z source photovoltaic grid-connected inverter provided by the invention can also have the following characteristics: the number of turns of the coil at the N1 side is more than that of the coil at the N2 side.

The O-Z source photovoltaic grid-connected inverter provided by the invention can also have the following characteristics: the filter circuit comprises three inductors and three capacitors, wherein the three inductors are connected with the inverter bridge, each capacitor is correspondingly connected with each inductor to form a filter, and the current output by the inverter bridge is filtered by the filter circuit and then is output as three-phase alternating current.

Action and Effect of the invention

According to the O-Z source photovoltaic grid-connected inverter, when the coupling inductance coil is in short circuit at one side of the inverter bridge, the voltage is increased and exceeds the power supply voltage, so that the power diode is turned off, the fault current can be automatically cut off, the response is rapid, the impact of the short-circuit fault on the power supply side is effectively isolated, the chain protection of the front-stage protection equipment is prevented, the dead time does not need to be considered in the control of the rear-stage inverter, and the circuit control difficulty is simplified; the energy storage capacitor absorbs electric energy when one side of the inverter bridge is short-circuited and releases the electric energy when one side of the inverter bridge works, so that the fault current peak value can be limited to a lower level; in addition, the coupling inductance coil adopted by the invention works in a transformer mode under the fault transient state, and the transient current of the coupling inductance coil can not cause magnetic saturation, so that the volume of the coupling inductance coil is also obviously reduced; in addition, compared with the traditional two-stage photovoltaic grid-connected structure, the O-Z source network has fewer required elements and low cost, compared with the traditional Z source network, the O-Z source network has fewer used circuit elements, reduces the cost, solves the problem of large input current during starting, forms a protection circuit, has stronger boosting capacity and provides higher working efficiency.

Drawings

FIG. 1 is a diagram of a main topology of an O-Z source photovoltaic grid-connected inverter in an embodiment of the invention;

FIG. 2 is a diagram of the topology of an O-Z source network in an embodiment of the invention;

FIG. 3 is a waveform diagram of the overall circuit operation of an O-Z source photovoltaic grid-connected inverter based on a simulink platform according to an embodiment of the invention;

FIG. 4 is an equivalent circuit diagram of the voltage relationship of the O-Z source photovoltaic grid-connected inverter in the direct-current state in the embodiment of the invention;

fig. 5 is a voltage relation equivalent circuit diagram of the O-Z source photovoltaic grid-connected inverter in the non-direct-current state in the embodiment of the invention.

Detailed Description

In order to make the technical means and functions of the present invention easy to understand, the present invention is specifically described below with reference to the embodiments and the accompanying drawings.

< example >

Fig. 1 is a main topology structure diagram of an O-Z source photovoltaic grid-connected inverter in an embodiment of the present invention.

As shown in fig. 1, an O-Z source photovoltaic grid-connected inverter 100 of the present embodiment includes a photovoltaic array module 10, an O-Z source network 20, an inverter bridge 30, a filter circuit 40, and a power grid 50.

The photovoltaic array module 10 is used as a power supply and has a positive electrode and a negative electrode.

Fig. 2 is a topology structural diagram of an O-Z source network in an embodiment of the present invention.

As shown in fig. 2, an O-Z source network 20 is connected to the photovoltaic array module 10 and has a power diode 21, a coupling inductor 22, and an energy storage capacitor 23.

The power diode 21 has an anode and a cathode, and the anode is connected to the anode of the photovoltaic array module 10.

The coupling inductor 22 has an N1 side coil 221 and an N2 side coil 222 coupled by a magnetic core, and the end of the N1 side coil 221 having the same name is connected to the cathode of the power diode 21.

The number of turns of the N1 side coil 221 is greater than that of the N2 side coil 222.

The energy storage capacitor 23 has an anode connected to the positive terminal of the photovoltaic array module 10 and a cathode connected to the dotted terminal of the N2 side coil 222.

The inverter bridge 30 is connected with the O-Z source network 20 and is connected with the negative electrode of the photovoltaic array module 10.

The synonym terminal of the N1 side coil 221 and the synonym terminal of the N2 side coil 222 are both connected to the inverter bridge 30.

The filter circuit 40 is connected to the inverter bridge 30.

The filter circuit 40 includes three inductors and three capacitors connected to the inverter bridge, each capacitor is connected to each inductor to form a filter, and the current output from the inverter bridge 30 is filtered by the filter circuit 40 and then output as three-phase alternating current.

The power grid 50 is connected to the filter circuit 40.

In this embodiment, the working process of the O-Z source photovoltaic grid-connected inverter 100 is as follows:

in the series branch of the power diode 21 and the N1 side coil 221, the coupling inductor 20 will increase in voltage above the supply voltage when the inverter bridge 30 side is shorted, causing the power diode 21 to turn off, thereby protecting the circuit.

In the series branch between the energy storage capacitor 23 and the N2 side coil 222, the energy storage capacitor 23 absorbs electric energy when the inverter bridge 30 side is short-circuited, and releases electric energy when the inverter bridge 30 side is operated.

In this embodiment, the O-Z source photovoltaic grid-connected inverter of the present invention is also tested based on a simulink platform, and in this embodiment, the photovoltaic array module 10 provides a voltage of 500V at a dc side, where the energy storage capacitor 23 is 200 μ F, the N1 side coil 221 is 1000 μ H, the N2 side coil 222 is 250 μ H, and the coupling inductor 22 has a mutual inductance of 495 μ H. The waveform of the line voltage output by the dc side voltage through the O-Z source network 20 and the inverter bridge 30 is shown in fig. 3.

Fig. 4 is a voltage relation equivalent circuit diagram of the O-Z source photovoltaic grid-connected inverter in the direct-current state in the embodiment of the invention.

In the through state, power diode 21 is reverse biased open, inverter bridge 30 stores energy in O-Z source network 20 due to the through short, as shown in fig. 4.

Fig. 5 is a voltage relation equivalent circuit diagram of the O-Z source photovoltaic grid-connected inverter in the non-direct-current state in the embodiment of the invention.

As shown in fig. 5, in the non-pass-through state, the bus is equivalent to a current source, and the O-Z source network 20 delivers electric energy to the inverter bridge 30.

Effects and effects of the embodiments

According to the O-Z source photovoltaic grid-connected inverter, when the coupling inductance coil is in short circuit at one side of the inverter bridge, the voltage is increased and exceeds the power supply voltage, so that the power diode is turned off, the fault current can be automatically cut off, the response is rapid, the impact of the short-circuit fault on the power supply side is effectively isolated, the chain protection of the front-stage protection equipment is prevented, the dead time is not required to be considered in the control of the rear-stage inverter, and the circuit control difficulty is simplified; the energy storage capacitor absorbs electric energy when one side of the inverter bridge is short-circuited and releases the electric energy when one side of the inverter bridge works, so that the fault current peak value can be limited to a lower level; in addition, the coupling inductance coil adopted by the invention works in a transformer mode under the fault transient state, and the transient current of the coupling inductance coil can not cause magnetic saturation, so that the volume of the coupling inductance coil is also obviously reduced; in addition, the O-Z source network of the embodiment needs fewer elements and is low in cost compared with a traditional two-stage photovoltaic grid-connected structure, compared with the traditional Z source network, the O-Z source network of the embodiment uses fewer circuit elements, reduces the cost, solves the problem of large input current during starting, forms a protection circuit, is higher in boosting capacity, and provides higher working efficiency.

The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.