Neutral-point voltage balance and common-mode voltage suppression control method for three-level inverter
A three-level inverter, voltage balance technology, applied in electrical components, output power conversion devices, AC power input into DC power output and other directions, can solve the impact of output waveform quality, uneven voltage division, AC power. Fluctuation and other problems, to overcome the inability of the midpoint voltage to be completely balanced, reduce the common mode voltage output, and achieve the effect of balanced control
Active Publication Date: 2016-06-22
ANHUI UNIVERSITY
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[0002] In the diode-clamped multi-level inverter, the neutral current flows through the two DC side capacitors, which makes the voltage division of the two capacitors uneven and generates corresponding AC fluctuations.
The balance of the midpoint voltage has always been the focus of research and the key to the application of multi-level neutral point clamped inverters. If the midpoint voltage balance of the inverter cannot be guaranteed for a long time, the quality of the output waveform will be seriously affected. impact, even waveform degeneration in extreme cases
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[0029] A control method for mid-point voltage balance and common-mode voltage suppression of a three-level inverter, comprising the following steps:
[0030] S1, taking A large area as an example, define a new virtual vector:
[0031] V NM0 =k A0 V M0 +k A1 V S0 +k A2 V S1 ; among them, k A0 ,k A1 ,k A2 ∈[0,1], and k A0 +k A1 +k A2 = 1; V S0 For the small vector POO / ONN, V S1 For the small vector PPO / OON, V M0 is the medium vector; since the new virtual medium vector includes two pairs of small vectors, the control is more flexible, so it can be adjusted by adjusting the parameter k A0 , k A1 , k A2 Control the action time of the medium vector and each small vector to realize the control of the neutral point voltage balance and other optimization objectives. In practical application k A0 , k A1 , k A2 The value of is to consider the influence of narrow pulse and dead zone.
[0032] In this example, take
[0033] S2, utilize the symmetry of each district ...
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The invention relates to a new space vector modulation method based neutral-point voltage balance and common-mode voltage suppression control method for a three-level inverter. A new virtual middle vector is defined, so that any region in the new space vector diagram comprises two pairs of small vectors; the small vectors with the relatively big neutral-point voltage balance coefficient values are used for modulating the neutral-point voltage balance, and called as neutral-point voltage regulation small vectors VSNP; the other pair of small vectors are used for suppressing the common-mode voltage output and called as common-mode voltage regulation small vectors VSCMV; the common-mode voltage amplitude absolute value is limited within a range of less than or equal to Udc / 6 so as to reduce the common-mode voltage fluctuation; and therefore, a three-phase switching sequence is formed flexibly by reasonably choosing the small vectors with small output common-mode voltages under the premise of ensuring the neutral-point voltage balance so as to suppress the common-mode voltage output of the inverter.
Description
technical field [0001] The invention relates to a three-level inverter control strategy, in particular to a control method for neutral point voltage balance and common-mode voltage suppression of a three-level inverter. Background technique [0002] In the diode-clamped multi-level inverter, the neutral current flows through the two DC side capacitors, which makes the voltage division of the two capacitors uneven and generates corresponding AC fluctuations. The balance of the midpoint voltage has always been the focus of research and the key to the application of multi-level neutral point clamped inverters. If the midpoint voltage balance of the inverter cannot be guaranteed for a long time, the quality of the output waveform will be seriously affected. impact, and even waveform degeneration in extreme cases. In recent years, the neutral point voltage balance of the diode neutral point clamped inverter has been widely concerned by scholars at home and abroad. The control me...
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IPC IPC(8): H02M7/487H02M1/12
CPCH02M1/12H02M7/487H02M1/123
Inventor 芮涛胡存刚王群京罗方林
Owner ANHUI UNIVERSITY