Vienna Rectifier Zero-Sequence Control for Balanced Input Currents
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Solution Overview
Problem
The regulation of DC/DC conversion in three-phase Vienna rectifiers is complex and unreliable due to fluctuating voltages across output capacitors, making it challenging to achieve stable and efficient power factor correction.
Innovation Solution
A method for controlling a three-phase Vienna rectifier by transforming setpoint compound voltages into simple voltages, calculating a zero sequence component, and generating switching signals based on phase currents and modulating values to balance input currents and simplify DC/DC regulation, using equations and comparisons with high-frequency carriers to determine switching signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional duty cycle control methods are used for Vienna rectifier switching arms, then the rectifier can operate with simple control logic, but the output capacitor voltages fluctuate making DC/DC regulation complex and unreliable
Solution Approach 1:
The patent changes the control parameter from simple duty cycles to a combination of common-mode voltage and differential-mode voltage. This parameter transformation allows independent control of output capacitor voltages (through common-mode voltage) and power transfer (through differential-mode voltage), stabilizing the DC/DC regulation and improving reliability while maintaining control simplicity.
2Device complexity
If conventional control methods are used, then the control structure remains simple, but the input currents exhibit ripple and harmonics reducing power factor correction quality
Solution Approach 1:
The patent segments the control of input currents into two independent components: common-mode control for balancing output capacitor voltages and differential-mode control for power factor correction. This segmentation allows each component to be optimized independently, reducing harmonics and improving power factor while keeping the overall control structure manageable.
Solution Approach 2:
The patent introduces common-mode voltage as an intermediary control variable that mediates between the switching arms and the output capacitors. This intermediary allows indirect control of output capacitor voltage balance, which in turn stabilizes the input current waveform and reduces harmonics without requiring complex direct control of each switching arm.
3Ease of manufacture
If standard PWM control is applied to Vienna rectifier, then the switching implementation is straightforward, but the output capacitor voltage balance is poor requiring complex regulation
Solution Approach 1:
The patent adds a common-mode voltage dimension to the traditional differential-mode PWM control. This dimensional extension allows independent adjustment of output capacitor voltages without affecting the power transfer function, achieving precise voltage balance while maintaining straightforward PWM switching implementation.
Data Source
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AI summary
The invention relates to a Method (6) for controlling a three-phase Vienna rectifier, comprising a plurality of controlled power switches, each associated with an electrical phase; the method (6) comprising: - a step of transforming (60) three provided reference line voltages into three phase voltages; - a step of calculating (61) a homopolar component to be injected according to the sign of the phase voltage values and to the average value of the phase currents of the three-phase Vienna rectifier; - a step of calculating "modulating" values for each phase of the three-phase Vienna rectifier according to the calculated homopolar component to be injected and the three phase voltages; and - a step of generating (62) six signals for switching the controlled power switches, according to the sign of the phase currents of the three-phase Vienna rectifier and the "modulating" values that were calculated.