METHOD AND APPARATUS FOR CURRENT AUTO BALANCING FOR PARALLEL CONVERTER SYSTEMS
First Claim
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1. A power conversion system, comprising:
- a plurality of switching converters having AC terminals connected together; and
a controller programmed for a given AC phase of the plurality of switching converters to;
determine a nominal modulation index,determine a plurality of adjusted modulation indices individually associated with a corresponding one of the plurality of switching converters at least partially according to;
individual switching converter AC current values associated with the given AC phase, andthe nominal modulation index, andcontrol pulse width modulation operation of the plurality of switching converters for the given AC phase according to the corresponding adjusted modulation indices to counteract AC current imbalance in the power conversion system.
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Abstract
Parallel converter current imbalance control apparatus and methods in which individual converter AC currents are measured for each phase, and the AC voltage control modulation indices associated with the converters having the highest and lowest AC currents for a given phase are adjusted to counteract current imbalance between the converters.
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Citations
20 Claims
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1. A power conversion system, comprising:
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a plurality of switching converters having AC terminals connected together; and a controller programmed for a given AC phase of the plurality of switching converters to; determine a nominal modulation index, determine a plurality of adjusted modulation indices individually associated with a corresponding one of the plurality of switching converters at least partially according to; individual switching converter AC current values associated with the given AC phase, and the nominal modulation index, and control pulse width modulation operation of the plurality of switching converters for the given AC phase according to the corresponding adjusted modulation indices to counteract AC current imbalance in the power conversion system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for operating parallel converters to drive a load, the method comprising:
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determining individual switching converter absolute AC current values associated with a given AC phase of the plurality of switching converters; determining a nominal modulation index for the given AC phase; selectively incrementally offsetting at least two adjusted modulation indices in a given pulse width modulation switching cycle for converters for the given AC phase at least partially according to the individual switching converter absolute AC current values to counteract AC current imbalance between the converters for the given AC phase; and controlling pulse width modulation operation of the plurality of switching converters for the given AC phase according to the corresponding adjusted modulation indices. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A non-transitory computer readable medium with computer executable instructions for:
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determining individual switching converter absolute AC current values associated with a given AC phase of a plurality of switching converters used to drive a single load; if the load is motoring, selectively decreasing the AC voltage of a first switching converter having a highest absolute AC current value associated with the given AC phase, and selectively increasing the AC voltage of a second switching converter having a lowest absolute AC current value associated with the given AC phase; and if the load is regenerating, selectively increasing the AC voltage of the first switching converter associated with the given AC phase, and selectively decreasing the AC voltage of the second switching converter associated with the given AC phase. - View Dependent Claims (20)
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Specification