Vienna Rectifier Control for Electric Vehicle Charging
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Solution Overview
Problem
High power charging in electric vehicles leads to significant current fluctuations at the output capacitors of three-phase rectifiers, making it challenging to regulate output voltages effectively, particularly in the context of battery charging where power factor correction is critical.
Innovation Solution
A method of controlling a three-phase Vienna rectifier by determining switch closing combinations that divide voltages between phases into specific states to achieve target phase-to-phase voltages, calculating cyclical ratios for each switch based on desired inter-phase target voltages and current measurements, and applying these controls through a processor to manage duty cycles and reduce current fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power charging is implemented in three-phase rectifiers, then charging power increases, but current fluctuations at output capacitors become significant
Solution Approach 1:
The patent segments the control of output capacitors by independently controlling the duty cycles of switching arms in each phase. This allows separate regulation of current flow to each capacitor, enabling precise control over current distribution and reducing fluctuations while maintaining high charging power.
Solution Approach 2:
The patent dynamically adjusts the duty cycle parameters of the switching arms based on real-time current measurements and control objectives. By changing these control parameters, the system optimizes current distribution to minimize fluctuations at output capacitors while sustaining high power charging levels.
2Ease of operation
If conventional duty cycle control is used in three-phase rectifiers, then control simplicity is maintained, but output voltage regulation precision deteriorates
Solution Approach 1:
The patent implements feedback control by measuring currents in real-time and using this information to adjust the duty cycles of switching arms. This closed-loop approach maintains control simplicity while significantly improving output voltage regulation precision through continuous optimization based on actual system state.
Solution Approach 2:
The patent transitions from static duty cycle control to dynamic control where duty cycles are continuously adjusted based on real-time measurements. This dynamic approach enables precise output voltage regulation while maintaining ease of operation through automated control algorithms.
3Manufacturing precision
If switch closing combinations are optimized for target voltages, then voltage regulation precision improves, but control complexity increases
Solution Approach 1:
The patent segments the control problem by treating each phase and switching arm independently. This segmentation allows optimization of switch closing combinations for each phase based on local requirements, achieving precise voltage regulation without requiring complex coordinated control across all phases simultaneously.
Solution Approach 2:
The patent applies partial control actions by adjusting only the necessary switching arms and duty cycles required to achieve target voltages, rather than controlling all switches equally. This selective approach improves voltage regulation precision while keeping control complexity manageable through focused intervention.
Data Source
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AI summary
The invention concerns a method for controlling a power factor correction circuit of the three-phase Vienna rectifier type (110), comprising a three-phase diode bridge and three switching arms (S1, S2, S3) interconnected at a midpoint (M) to which a first and a second capacitor (C1, C2) are connected for respectively supporting a first and a second output voltage (VDC _high,VDC_low) of the diode bridge, the switches of each arm being controlled according to a regulation of the currents at the input to the rectifier generating phase-to-phase target voltages that are to be produced according to setpoint current values, wherein: - in each period of the setpoint currents, mutually exclusive combinations of switch closures are determined, in order to produce target voltages, and - duty cycles are calculated for each controlled switch from the determined combinations, so as to obtain equal currents in the two capacitors.