ARCP Converter Leg Control for Parallel Current Sharing
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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 differing switch component parameters and impedances, which existing methods struggle to fully address.
Innovation Solution
A power converter system with parallel-connected ARCP converter legs uses individual autonomous leg-specific boost current adjustments based on the magnitude of each leg's current to balance current sharing, adjusting boost currents and times to reduce differential output currents, ensuring more even load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel-connected inverter units are used to increase output power capability, then power capability is improved, but current imbalance occurs between units
Solution Approach 1:
The patent applies local quality by introducing individual current sensing and independent pulse width modulation control for each parallel-connected inverter unit. Each unit's switching devices are controlled based on its own current feedback, allowing localized adjustment of switching timing to compensate for parameter differences and achieve current balancing across all units.
Solution Approach 2:
The patent changes the timing parameters of switching device control pulses based on measured current values. By dynamically adjusting the turn-on and turn-off timing of switching devices in each parallel unit according to its actual current, the system compensates for parameter variations and achieves balanced current distribution among all parallel-connected units.
2Reliability
If switch control pulses are modified to balance currents, then current balance is improved, but component stress increases due to extended conducting times
Solution Approach 1:
The patent implements feedback control by continuously measuring the current in each parallel-connected inverter unit and using this information to adjust the control pulses for switching devices. The measured current values are fed back to the control system, which then modifies the switching timing to achieve current balancing while minimizing the extension of conducting times and associated component stress.
Data Source
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AI summary
A power converter system comprises auxiliary resonant commutated pole (ARCP) 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. (Figures 6 and 7)