Neutral-point voltage control method of NPC (neutral-point converter) type three-level inverter based on interval selection

A three-level inverter, voltage control method technology, applied in electrical components, output power conversion devices, AC power input conversion to DC power output and other directions, can solve the problem of digital implementation of unfavorable systems, complex calculation of zero-sequence components, etc. question

Inactive Publication Date: 2012-10-03
HUAZHONG UNIV OF SCI & TECH
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Problems solved by technology

A large number of parameters are not conducive to the realization of real-time control systems, and the calcula

Method used

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  • Neutral-point voltage control method of NPC (neutral-point converter) type three-level inverter based on interval selection
  • Neutral-point voltage control method of NPC (neutral-point converter) type three-level inverter based on interval selection
  • Neutral-point voltage control method of NPC (neutral-point converter) type three-level inverter based on interval selection

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Embodiment

[0049] The midpoint voltage control method of the NPC type three-level inverter based on interval selection of the present invention can effectively realize the midpoint voltage control. image 3 A block diagram of the algorithm realization of the present invention is given, and the proportional-integral PI controller is used to obtain the voltage offset Δu, the lower limit of the limiting value is m-1, and the upper limit is 1-m. The adjustment angle can be obtained by multiplying the absolute value of the adjustment amount by 2π clipping. The range of the adjustment angle is 0≤Δθ≤π / 2, and the adjustment angle, the adjustment amount and the modulation wave before adjustment can be substituted into the adjustment function Fcn. The adjusted three-phase modulation wave is obtained, and the adjustment function Fcn is given by equations (6)~(8):

[0050]

[0051]

[0052]

[0053] This method needs to sample the midpoint voltage U np , and the U np with U dc / 2 for com...

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Abstract

The invention discloses a neutral-point voltage control method of an NPC (neutral-point converter) type three-level inverter based on interval selection, belonging to the technical field of power electronics The method comprises the steps: selecting a phase which is maximum in an absolute value in the three phases as an adjusting phase, wherein a peak point of the adjusting phase is taken as a symmetrical point in the adjusting interval and the adjusting range is not greater than pi/2; measuring the neutral-point voltage Unp in real time, comparing the Unp with a given value; determining the voltage offset amount according to the comparison result so as to adjust the modulating wave in the adjusting interval; and comparing the adjusted modulating wave with a carrier wave to output a PWM (pulse-width modulation) signal so as to control the work state of a switch tube of an inverter. With the adoption of the neutral-point voltage control method, fewer parameters are related, and only the neutral-point voltage needs to be detected, so that the method is simple in control structure and convenient to realize.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a control method for the midpoint voltage of an NPC type three-level inverter based on interval selection. Background technique [0002] Compared with the traditional two-level inverter, the diode-clamped (NPC) three-level inverter has changed the number of output phase voltage levels from 2 to 3, and the number of line voltage levels has changed from 3 to 5, closer to the sine wave, can effectively reduce the harmonics of the output waveform under the same switching frequency, under the same conditions, the same voltage output can be obtained from low withstand voltage devices and lower switching frequency, so in the It is widely used in high-voltage and high-power conversion circuits. But the midpoint voltage balance problem is its inherent outstanding problem. Inconsistent DC bus capacitor parameters, unbalanced loads, and different circuit structures a...

Claims

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Application Information

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IPC IPC(8): H02M7/487
Inventor 程善美龚博宁博文刘江
Owner HUAZHONG UNIV OF SCI & TECH
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