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Sinusoidal pulse width modulation (SPWM) control techniques, computer readable mediums, and apparatus are presented for operating a multilevel converter, in which a desired AC node voltage level is determined through comparison of a plurality of carrier signals or values to at least one reference si

Sinusoidal pulse width modulation (SPWM) control techniques, computer readable mediums, and apparatus are presented for operating a multilevel converter, in which a desired AC node voltage level is determined through comparison of a plurality of carrier signals or values to at least one reference signal or value, and a switching state is selected from a plurality of redundant switching states corresponding to the desired AC node voltage level for generating switching control signals based at least partially on a switched capacitor voltage balancing goal or other control objective.

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1. A power conversion system, comprising: a multilevel converter including first and second DC nodes, an AC node, and a converter circuit including switching devices and a plurality of switched capacitors, the converter circuit operative according to a plurality of switching control signals to provi

1. A power conversion system, comprising: a multilevel converter including first and second DC nodes, an AC node, and a converter circuit including switching devices and a plurality of switched capacitors, the converter circuit operative according to a plurality of switching control signals to provide a plurality of distinct voltage levels at the AC node, the multilevel converter comprising: a first circuit, including a first switching circuit with at least four switching devices connected in series with one another between first and second input nodes, with the AC node connecting two of the plurality of switching devices, and a clamping circuit including first and second clamping elements connected in series with one another between first and second internal nodes of the first switching circuit, and a third internal node joining the first and second clamping elements, anda switched capacitor circuit, including a plurality of capacitor switching devices individually connected between a corresponding DC node and a corresponding input node of the first switching circuit,the plurality of capacitors being individually connected between a corresponding input node of the first switching circuit and the third internal node; anda controller providing the switching control signals to the multilevel converter, the controller configured to compare a plurality of carrier signals or values to at least one reference signal or value to determine a desired AC node voltage level for operation of the multilevel converter, and to select from a plurality of redundant switching states for at least one of the distinct voltage levels at the AC node at least partially according to a control objective;wherein the controller provides the plurality of switching control signals to the plurality of switching devices of the first switching circuit and to the capacitor switching devices to provide the multilevel voltage at the AC node, the controller configured to select from among a plurality of redundant switching states for at least one of the distinct voltage levels at the AC node at least partially according to the desired AC node voltage level and the control objective. 2. The power conversion system of claim 1, wherein the control objective is related to regulating switched capacitor voltages, and wherein the controller is configured to select from the plurality of redundant switching states for the at least one distinct voltage level to facilitate regulation of the voltages of the switched capacitors at least partially according to: the desired AC node voltage level,present voltage conditions of the switched capacitors, anda polarity of a current flowing into or out of the AC node. 3. The power conversion system of claim 2, wherein the controller is configured to select from the plurality of redundant switching states at least partially to regulate the voltages of the switched capacitors to at least one reference level. 4. The power conversion system of claim 1, wherein the plurality of capacitors are individually directly connected to the third internal node. 5. The power conversion system of claim 1, wherein the multilevel converter is configured to selectively provide one of an integer number N voltage levels at the AC node, where N≧4, according to the switching control signals provided by the controller. 6. The power conversion system of claim 1, wherein the multilevel converter is an inverter, and wherein the controller is configured to provide the plurality of switching control signals to cause the multilevel converter to convert DC input power received via the DC nodes to provide AC output power at the AC node at least partially according to the desired AC node voltage level and the control objective. 7. The power conversion system of claim 1, wherein the multilevel converter is a rectifier, and wherein the controller is configured to provide the plurality of switching control signals to cause the multilevel converter to convert AC input power received via the AC node to provide DC output power at the DC nodes. 8. The power conversion system of claim 1, comprising a plurality of multilevel converters forming a multiphase conversion system with a plurality of AC nodes, and wherein the controller is configured to provide the switching control signals to the plurality of multilevel converters according to the plurality of redundant switching states for the at least one distinct voltage level at the corresponding AC nodes at least partially according to a desired AC node voltage level and the control objective. 9. The power conversion system of claim 1, wherein the multilevel converter is configured to selectively provide one of an integer number N voltage levels at the AC node, where N≧4, according to the switching control signals provided by the controller. 10. The power conversion system of claim 1: wherein the multilevel converter is a nested neutral point clamped H-bridge converter comprising first and second nested neutral point clamped (NNPC) converter stages, the individual NNPC converter stages comprising: a first circuit, including a first switching circuit including a plurality of switching devices connected in series with one another between first and second input nodes, with the AC node connecting two of the plurality of switching devices, and a clamping circuit including first and second clamping elements connected in series with one another between first and second internal nodes of the first switching circuit, and a third internal node joining the first and second clamping elements, anda switched capacitor circuit, including a second switching circuit including a plurality of capacitor switching devices individually connected between a corresponding DC node and a corresponding input node of the first switching circuit, and the plurality of capacitors individually connected between a corresponding input node of the first switching circuit and the third internal node; andwherein the controller is configured to provide the switching control signals to the plurality of multilevel converters according to the plurality of redundant switching states for the at least one distinct voltage level at the corresponding AC nodes at least partially according to a desired AC node voltage level and the control objective. 11. A power conversion system, comprising: a multilevel converter including first and second DC nodes, an AC node, and a converter circuit including switching devices and a plurality of switched capacitors, the converter circuit operative according to a plurality of switching control signals to provide a plurality of distinct voltage levels at the AC node; anda controller providing the switching control signals to the multilevel converter, the controller configured to compare a plurality of carrier signals or values to at least one reference final or value to determine a desired AC node voltage level for operation of the multilevel converter, and to select from a plurality of redundant switching states for at least one of the distinct voltage levels at the AC node at least partially according to a control objective;wherein the multilevel converter is a back-to-back converter comprising: at least one multilevel rectifier stage,at least one multilevel inverter stage, andan intermediate DC circuit connected between the multilevel rectifier stage and the multilevel inverter stage;wherein the multilevel rectifier stage and the multilevel inverter stage each include first and second DC nodes, an AC node, and a converter circuit including switching devices and a plurality of switched capacitors, the converter circuit operative according to a plurality of switching control signals from the controller to provide a plurality of distinct voltage levels at the AC node;wherein the controller is configured to provide the plurality of switching control signals to cause the multilevel rectifier stage to convert AC input power received via the AC node to provide DC output power at the DC nodes and to cause the multilevel converter control a voltage level at the AC node at least partially according to a desired AC node voltage level for the rectifier stage and the control objective; andwherein the controller is configured to provide the plurality of switching control signals to cause the multilevel inverter stage to convert DC input power received via the DC nodes to provide AC output power at the AC node at least partially according to a desired AC node voltage level for the inverter stage and the control objective. 12. The power conversion system of claim 1, wherein the control objective is related to common mode rejection and wherein the controller is configured to provide the plurality of switching control signals to at least partially facilitate reduced common mode voltages in the power conversion system. 13. The power conversion system of claim 1, wherein the multilevel converter is a rectifier, and wherein the control objective is related to power factor correction. 14. The power conversion system of claim 1, wherein the multilevel converter is a rectifier, and wherein the control objective is related to regulating a DC voltage across the first and second DC nodes. 15. A power conversion system, comprising: a multilevel converter including first and second DC nodes, an AC node, and a converter circuit including switching devices and a plurality of switched capacitors, the converter circuit operative according to a plurality of switching control signals to provide a plurality of distinct voltage levels at the AC node, the multilevel converter comprising: a first circuit, including a first switching circuit with a plurality of switching devices connected in series with one another between first and second input nodes, with the AC node connecting two of the plurality of switching devices, and a clamping circuit including first and second clamping elements connected in series with one another between first and second internal nodes of the first switching circuit, and a third internal node joining the first and second clamping elements, anda switched capacitor circuit, including a plurality of capacitor switching devices individually connected between a corresponding DC node and a corresponding input node of the first switching circuit,the plurality of capacitors being individually connected between a corresponding input node of the first switching circuit and the third internal node, the plurality of capacitors being individually directly connected to the third internal node; anda controller providing the switching control signals to the multilevel converter, the controller configured to compare a plurality of carrier signals or values to at least one reference signal or value to determine a desired AC node voltage level for operation of the multilevel converter, and to select from a plurality of redundant switching states for at least one of the distinct voltage levels at the AC node at least partially according to a control objective;wherein the controller provides the plurality of switching control signals to the plurality of switching devices of the first switching circuit and to the capacitor switching devices to provide the multilevel voltage at the AC node, the controller configured to select from among a plurality of redundant switching states for at least one of the distinct voltage levels at the AC node at least partially according to the desired AC node voltage level and the control objective. 16. The power conversion system of claim 1, wherein the control objective is related to regulating switched capacitor voltages, and wherein the controller is configured to select from the plurality of redundant switching states for the at least one distinct voltage level to facilitate regulation of the voltages of the switched capacitors at least partially according to: the desired AC node voltage level,present voltage conditions of the switched capacitors, anda polarity of a current flowing into or out of the AC node. 17. The power conversion system of claim 16, wherein the controller is configured to select from the plurality of redundant switching states at least partially to regulate the voltages of the switched capacitors to at least one reference level. 18. The power conversion system of claim 15, wherein the multilevel converter is configured to selectively provide one of an integer number N voltage levels at the AC node, where N≧4, according to the switching control signals provided by the controller. 19. The power conversion system of claim 15, comprising a plurality of multilevel converters forming a multiphase conversion system with a plurality of AC nodes, and wherein the controller is configured to provide the switching control signals to the plurality of multilevel converters according to the plurality of redundant switching states for the at least one distinct voltage level at the corresponding AC nodes at least partially according to a desired AC node voltage level and the control objective. 20. The power conversion system of claim 15, wherein the control objective is related to common mode rejection and wherein the controller is configured to provide the plurality of switching control signals to at least partially facilitate reduced common mode voltages in the power conversion system.