A DC side voltage equalization control method for a three-phase four-wire three-level inverter
A three-level inverter, three-phase four-wire system technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve problems that cannot be realized, poor algorithm scalability, and algorithm operations Large volume and other problems, to improve the uneven pressure situation, simplify the control, improve the effect of accuracy
Active Publication Date: 2020-04-17
MINNAN INST OF SCI & TECH
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Problems solved by technology
[0003] In the three-phase four-wire system, due to the existence of the neutral line, the method of injecting the zero-sequence voltage component is no longer applicable. For the three-phase four-wire system, the current neutral point voltage balance control mainly has a control method based on the neutral line current injection And 3D-SVPWM modulation method, based on the control method of neutral current injection, adjust the error through PI and other control loops, and generate the corresponding midpoint potential balance current to add the system command current to adjust the midpoint potential, but this method PI controller more complex design
The 3D-SVPWM-based control strategy realizes midpoint potential balance by expanding the subspace of 3D-SVPWM, but its algorithm has a large amount of computation and is only applicable to 3D-SVPWM modulation, which cannot be realized under the currently commonly used dual-carrier SPWM modulation. , the algorithm has poor scalability
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[0040] Below in conjunction with accompanying drawing and specific embodiment, the present invention will be described in further detail:
[0041] Such as Figure 1-Figure 9(d) As shown, an active power filter DC side voltage fluctuation absorbing circuit, step 1: define the upper and lower capacitor voltages of the three-phase four-wire three-level inverter as V dc1 and V dc2 , the output current i of each bridge arm o , then the output voltage of each bridge arm of the three-level SAPF has three situations: +V dc1 ,-V dc2 , 0;
[0042] When the inverter outputs positive voltage +V dc1 when, as attached figure 1 As shown, the current passes through the upper capacitor, so when the current flows into the bridge arm, the upper capacitor charges; and when the current flows out of the bridge arm, the upper capacitor discharges, and the upper and lower capacitor voltage V dc1 , V dc2 and arm current i o The relationship can be expressed as:
[0043]
[0044] When the ...
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The invention relates to the technical field of sockets, and specifically relates to and provides a direct current side voltage sharing control method for a three-phase four-wire system three-level inverter which can be achieved under dual-carrier SPWM modulation and has good algorithm expansibility. When the inverter outputs positive voltage, the inverter outputs negative voltage, and the inverter outputs zero level, a voltage sharing factor is obtained, a value of the voltage sharing factor is obtained by using a dual-carrier SPWM modulation algorithm, and then voltage sharing current required by each of bridge arms is calculated according to a difference of voltage of upper and lower capacitors and is added to a system current loop controller.
Description
technical field [0001] The invention relates to the application field of electric power technology, in particular to a DC side voltage equalization control method of a three-phase four-wire system three-level inverter. Background technique [0002] The unbalanced voltage of the upper and lower capacitors on the DC side is an inherent problem of the capacitor split topology and is also a key point of system control. The imbalance of the midpoint potential will cause distortion of the output voltage waveform, unbalanced pressure on the switching devices and even damage, reducing the DC side capacitance. life expectancy and other serious issues. At present, many scholars have done a lot of research on this problem. For the three-phase three-wire three-level DC side voltage equalization control, there are mainly control strategies based on zero-sequence voltage injection and SVPWM redundant vector. The theory of the control method based on zero-sequence voltage injection is cle...
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IPC IPC(8): H02M7/487H02M7/537
Inventor 陈冬冬高婷婷杨先花许俊杰王陈华黄佳欣
Owner MINNAN INST OF SCI & TECH