Parallel ARCP Converter Leg Control for Current Sharing Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In parallel-connected power converters, current imbalances between units lead to uneven stress on components, resulting in premature wear and increased temperature due to parameter differences and varying impedances, which existing methods have not adequately addressed.
Innovation Solution
A power converter system with parallel-connected ARCP converter legs, where a control arrangement balances current sharing through individual autonomous leg-specific boost current adjustments dependent on the magnitude of each leg's current, adjusting boost currents and times to reduce differential output currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple inverter units are connected in parallel to increase output power capability, then the power output capability is improved, but current imbalance occurs between units due to parameter differences and varying impedances
Solution Approach 1:
The patent applies local quality by providing each parallel-connected inverter unit with individual current sensing and independent control adjustments. Each unit's switching components are controlled based on its own current magnitude, allowing localized adaptation to compensate for parameter differences and impedance variations, thereby achieving current balance while maintaining increased power output capability
Solution Approach 2:
The patent changes control parameters (switching timing, pulse width modulation duty cycles) dynamically based on measured current magnitudes in each parallel unit. By adjusting these parameters in real-time according to actual current conditions, the system compensates for parameter differences and impedance variations, resolving the current imbalance issue while preserving the enhanced power capability
2Reliability
If switch control pulses are modified to balance currents by delaying turn-on or turn-off times, then current balance is improved, but component stress remains uneven and switch wear increases due to higher currents in certain components
Solution Approach 1:
The patent implements feedback control by continuously sensing the current magnitude in each parallel inverter unit and using this information to adjust the switching control pulses. The control system monitors actual current flow and dynamically modifies turn-on/turn-off timing and pulse widths to equalize currents, thereby reducing uneven component stress and preventing premature switch wear while maintaining current balance
Data Source
AI summary
A power converter system includes auxiliary resonant commutated pole converter legs, particularly ARCP half-bridge legs, connected in parallel between a common dc system and a common ac system or between two common dc systems. Commutations of the parallel-connected converter legs are initiated by simultaneous commutation commands. A control arrangement is provided to balance a current sharing between the parallel-connected ARCP converter legs by means of having an individual autonomous leg-specific boost current adjustment for each of the parallel-connected ARCP converter legs for adjusting boost currents in a direction that a differential output current is reduced. Each individual boost current adjustment is dependent on the magnitude of the leg current of the respective ARCP converter leg only.