Parallel Converter Leg Timing Control for Current Sharing
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Solution Overview
Problem
In parallel-connected power converters, current imbalances between units lead to uneven stress on components, premature wear, and increased temperature due to parameter differences and varying impedances, which existing methods struggle to fully address.
Innovation Solution
A power converter system with a control arrangement that adjusts switching instants for each converter leg based on sensed current values, shifting mode A commutation later and mode B commutation earlier by a variable timestep proportional to the current, to balance current sharing between parallel-connected inverter legs.
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 adjusting the switching instants of each inverter unit individually based on its specific current status. The control system modifies turn-on and turn-off times for each unit's switches according to their respective current magnitudes, creating localized adjustments that balance the overall current distribution across parallel units.
Solution Approach 2:
The patent changes the timing parameters of switch control pulses to balance current sharing. By dynamically adjusting the turn-on and turn-off instants of switches in each inverter unit, the system modifies operational parameters to equalize current magnitudes across parallel-connected units, resolving the current imbalance issue.
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 employs dynamics by continuously monitoring current magnitudes in each inverter unit and dynamically adjusting switch control pulses in real-time. The control system adapts the turn-on and turn-off instants based on instantaneous current conditions, creating a dynamic balancing mechanism that responds to changing operational states without imposing excessive stress.
Solution Approach 2:
The patent implements feedback control by measuring the current in each inverter unit and using this information to adjust the switch control pulses. The control system continuously monitors current magnitudes and modifies switching instants accordingly, creating a closed-loop system that balances current distribution while minimizing component stress through intelligent control.
Data Source
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AI summary
Current sharing between the plurality of parallel-connected ARCP or hard-switching converter legs is balanced by a control arrangement (81, 82). The control arrangement senses a leg output current (Io1, Io2) in each of the parallel-connected converter legs (INV1, INV2) and have an individual autonomous leg-specific switching instant adjustment for the main switches (S11, S12, S21, S22) of each of the parallel-connected converter legs to shift the first mode A commutation of the respective converter leg later in time and to shift the second mode B commutation of the respective converter leg earlier in time by a variable timestep proportional to the value of the sensed leg current (Io1, Io2) of the respective converter leg (INV1, INV2). In other words, if the value of the sensed leg output current in one converter leg is larger than in the other converter leg, then in mode A, the higher-current leg will commutate later than the leg with less current, and in mode B, the higher-current leg will commutate earlier than the leg with less current.