Modular multilvel converter and control framework for hybrid energy storage
AssigneeNEC Laboratories America, Inc.
InventorsFeng Guo, Yanzhu Ye, Ratnesh Sharma
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Abstract
A modular multilevel converter for hybrid energy storage includes three phases connectable in series to a battery, and in parallel to one another. Each phase includes at least two arms of sub-modules and buffer inductors, and each of the sub-modules comprises a half-bridge and an ultracapacitor. A two layer controller, including a coordination layer and a converter layer, is configured to independently control battery output power and ultracapacitor output power, and to distribute a power load between the battery and the ultracapacitor to optimize the performance of a hybrid energy storage system.
Claims20
A modular multilevel converter for hybrid energy storage, comprising:
- three phases connectable in series to a battery and in parallel to one another, each phase comprising at least two arms of sub-modules and buffer inductors, wherein each of the sub-modules comprises a half-bridge and an ultracapacitor;
- and
- a two layer controller, including a coordination layer and a converter layer, wherein the two layer controller independently controls battery output power and ultracapacitor output power, and distributes a power load between the battery and the ultracapacitor to optimize the performance of a hybrid energy storage system.
A method for controlling a modular multilevel converter based hybrid energy storage system, comprising:
- determining a number of sub-modules to be inserted in a respective upper and lower arm of a phase in the modular multilevel converter;
- determining whether a current in each respective arm is greater than zero;
- selecting sub-modules to engage for each arm based on ultracapacitor voltages for each sub-module in the respective arm in accordance with the determination of whether the current in the respective arm is greater than zero;
- generating gate signals to engage the selected sub-modules;
- and
- distributing power based on the gate signals using a two layer controller including a coordination layer and a converter layer, wherein the two layer controller independently controls battery output power and ultracapacitor output power, and distributes a power load between a battery and an ultracapacitor to optimize the performance of the hybrid energy storage system.
Dependencies are inferred from the claim text.