High-gain low-stress photovoltaic multi-level inverter and control method thereof

A multi-level inverter, low-stress technology, applied in photovoltaic power generation, electrical components, AC power input conversion to DC power output, etc., can solve the problem of voltage reduction at the maximum power point, DC capacitor voltage equalization, and no boost functions and other issues to achieve the effect of reducing control complexity and increasing output level

Active Publication Date: 2021-08-13
ZHENGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, traditional multi-level inverters use a large number of diodes and capacitors, and the DC capacitors of flying-capacitor and diode-clamped inverters still have voltage equalization problems.
In addition, the output voltage of photovoltaic power generation units usually cannot meet the grid-connected requirements. Factors such as sunlight, temperature, and shadow may cause the maximum power point voltage to decrease, while traditional multi-level inverters do not have a boost function.

Method used

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  • High-gain low-stress photovoltaic multi-level inverter and control method thereof
  • High-gain low-stress photovoltaic multi-level inverter and control method thereof
  • High-gain low-stress photovoltaic multi-level inverter and control method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0051] Such as figure 1 As shown, a high-gain low-stress photovoltaic multilevel inverter includes a boost unit, an I-shaped switch structure, and an independent capacitor C 3 and two half-bridge structures; the inverter in this embodiment consists of a boost unit and an independent capacitor C 3 It is formed by connecting the I-shaped switch structure, and using two half-bridge structures instead of the H-bridge to convert the polarity of the output level.

[0052] The boost unit includes a photovoltaic DC power supply E, an electrolytic capacitor C 1 , electrolytic capacitor C 2 , switch tube S 2 , switch tube S 3 , switch tube S 4 , switch tube S 5 , switch tube S 6 and switch S without reverse diode 1 ; The switch tube S 1 The input terminal and the switch tube S 2 The input terminal of the photovoltaic DC power supply E is connected to the positive pole; the switch tube S 1 output terminal with electrolytic capacitor C 1 Anode of the switch tube S 5 The input...

Embodiment 2

[0061] Such as figure 2 As shown, this embodiment provides a scalable high-gain low-stress photovoltaic multilevel inverter, including the high-gain low-stress photovoltaic multilevel inverter described in Embodiment 1 and an expandable module;

[0062] The expandable module includes a switch tube S 16 , switch tube S 17 , switch tube S 18 , switch tube S 19 , switch tube S 20 and electrolytic capacitor C 4 ; The switch tube S 16 The input terminal and the switch tube S 19 The input terminal, electrolytic capacitor C 4 The anode is connected; the switching tube S 16 The output terminal of the switch tube S 18 The input terminal is connected; the switch tube S 17 The input terminal and the switch tube S 18 The output terminals are connected; the switch tube S 17 The output terminal of the switch tube S 20 The output terminal, the electrolytic capacitor C 4 connected to the cathode.

[0063]The boost unit charges all expandable modules at the same time, and each ...

Embodiment 3

[0065] This embodiment provides a control method for a high-gain and low-stress photovoltaic multilevel inverter:

[0066] Generate a driving signal, and control the high-gain and low-stress photovoltaic multilevel inverter described in Embodiment 1 to work in 17 working states and output 17 levels through the driving signal, and the high-gain and low-stress photovoltaic multi-level inverter Level inverter output 4 times voltage gain.

[0067] Specifically, the modulation principle shown in Figure 3(a)-3(d) adopts carrier stacking pulse width modulation technology, using 16 channels of triangular carriers with the same amplitude and frequency to be stacked in sequence, and 1 channel of sine modulation wave After comparison, the obtained 16 channels of original pulse waveforms are logically combined to obtain a gate pulse drive signal for driving the switching tube on and off. The inverter has a large number of output levels, and the principle of the modulation strategy is rep...

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Abstract

The invention provides a high-gain low-stress photovoltaic multi-level inverter According to the inverter, four-time voltage gain and 17-level alternating-current voltage output are realized by using one photovoltaic direct-current power supply, three capacitors and fifteen switching devices. The inverter can generate more levels with fewer switching devices, so that the output harmonic content of the inverter is effectively reduced; the inversion process can be realized without a rear-end H bridge, so that the voltage stress of a switching device is effectively reduced; and the bidirectional current loop in each output level state realizes the capability of carrying an inductive load. In addition, the capacitor voltage ripple of the inverter is small, and the complexity of the controller is simplified due to the advantage of self-balancing of the capacitor voltage.

Description

technical field [0001] The invention relates to a high-gain, low-stress photovoltaic multilevel inverter and a control method thereof, belonging to the field of electric energy conversion and new energy power generation, and in particular to the field of photovoltaic power generation. Background technique [0002] Renewable energy is widely used, and the demand for renewable energy in countries around the world is also increasing day by day. Renewable energy power generation, such as photovoltaic power generation, has become an increasingly important way of power generation. The DC power generated by the photovoltaic cell module needs to be powered by the inverter or connected to the AC grid, so a high-performance inverter is very important in the photovoltaic power generation system. [0003] Compared with two-level inverters, multi-level inverters have less electromagnetic interference and can output higher-quality sinusoidal waveforms while withstanding higher voltages. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/5387H02M1/088H02M1/14H02M1/32
CPCH02M7/53871H02M1/088H02M1/14H02M1/32Y02E10/56
Inventor 王要强张亨泰赖锦木王金凤王克文梁军
Owner ZHENGZHOU UNIV
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