Parallel Power Converter Current Balancing via Feedback Control
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Solution Overview
Problem
In systems with multiple power converters connected in parallel, current imbalance and output voltage fluctuations occur due to variations in parameters and measurements, leading to inefficiencies in controlling electrical loads.
Innovation Solution
A control system where each power converter has a dedicated control unit, with a 'master' converter sharing its output current with 'slave' converters, allowing for autonomous determination of output voltages and correction voltages to balance currents across the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power converters are connected in parallel to increase power supply, then the power supplied to the electrical load is improved, but current imbalance and voltage fluctuations occur between converters
Solution Approach 1:
The invention implements a feedback mechanism where each converter's control unit measures its own output current and exchanges this information with other converters. The control unit calculates a correction term based on the current imbalance detected through feedback, and adjusts the PWM command accordingly to balance the currents across all parallel converters
Solution Approach 2:
The invention dynamically changes the PWM duty cycle parameter for each converter based on real-time current measurements. By adjusting the PWM command parameter individually for each converter according to its current output and the desired average current, the system achieves current balancing while maintaining increased power supply capability
2Stability of the object's composition
If a centralized control unit is used to synchronize PWM commands, then the synchronization is improved, but the system complexity and vulnerability to single point failure increase
Solution Approach 1:
The invention divides the control function into separate control units for each power converter, with each control unit independently managing its own converter. This segmentation eliminates the single point of failure associated with centralized control while maintaining synchronization through local decision-making based on exchanged current information
Solution Approach 2:
Each control unit autonomously determines its own PWM command by measuring its converter's current, calculating the deviation from the average, and adjusting its output accordingly. This self-service approach reduces system complexity by eliminating the need for a complex centralized controller while maintaining synchronization
3Reliability
If separate control units are used for each inverter stage, then the system reliability is improved, but current balancing becomes difficult due to parameter variations and measurement differences
Solution Approach 1:
The invention uses feedback of actual current measurements from each converter to compensate for parameter variations and measurement differences. Each control unit receives current information from other converters, calculates the imbalance, and adjusts its PWM command to achieve current balancing despite individual converter variations
Solution Approach 2:
The invention dynamically adjusts the PWM duty cycle parameter for each converter based on real-time current measurements and calculated correction terms. This parameter adjustment compensates for manufacturing variations and measurement differences, ensuring consistent current output across all converters
Data Source
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AI summary
The present invention relates to a control system for an electric charge, said system comprising: - A first power converter (VV1) and a second power converter (VV2) connected in parallel, - A first control unit (UC1) associated with the first power converter and a second control unit (UC2) associated with the second power converter, - The second control unit (UC2) comprises a main control module (M1_2) for determining a second output voltage (νσ2) to apply the electric charge and a secondary control module (M2_2) to determine a control voltage (Δvσk) to be applied to said second output voltage (νσ2), said control voltage being determined from the difference between the output current (iσ2) of the second power converter and the output current (iσ1) of the first power converter.