Cascaded Energy Storage Modulation for SOC-Balanced Phase Shifting
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Solution Overview
Problem
The imbalance of states of charge (SOCs) among energy storage batteries in cascaded H-bridge systems due to inconsistent initial phase angles of carriers in carrier phase-shifted pulse width modulation (PS-PWM) leads to uneven power distribution and reduced system efficiency and lifespan.
Innovation Solution
A modulation method that synchronously delays the initial phase angles of carriers applied to submodules in a cascaded energy storage system, maintaining carrier amplitudes unchanged during the delay, allowing multiple carriers with different initial phase angles to influence the same submodule, thereby balancing SOC distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If carrier phase-shifted pulse width modulation (PS-PWM) is used in cascaded H-bridge energy storage system, then output quality and switching frequency are improved, but state of charge (SOC) balance between submodules deteriorates
Solution Approach 1:
The patent implements periodic adjustment of carrier initial phase angles through synchronous delay. The modulation strategy periodically modifies the phase angles of carriers in different submodules to ensure that over one complete modulation period, the total power output of each submodule is equal, thereby achieving SOC balance while maintaining high output quality through PS-PWM
Solution Approach 2:
The patent dynamically changes the initial phase angle parameter of carriers through synchronous delay adjustment. By modifying this parameter periodically, the system achieves equal power distribution across submodules over a modulation period, resolving the SOC imbalance problem while preserving the benefits of PS-PWM modulation
2Stability of the object's composition
If different initial phase angles are applied to carriers in different submodules, then power distribution uniformity is improved, but system complexity increases
Solution Approach 1:
The patent applies different initial phase angles to carriers in different submodules based on their local power output characteristics. Each submodule receives a customized phase angle that compensates for its specific power imbalance, achieving local optimization of power distribution uniformity without requiring complete redesign of the overall modulation system
Solution Approach 2:
The patent implements dynamic adjustment of carrier phase angles through synchronous delay. The phase angles are not fixed but are periodically modified according to real-time power distribution requirements, enabling the system to adaptively maintain power uniformity while managing complexity through systematic control
Data Source
AI summary
Provided in the present application are a modulation method and modulation apparatus for a cascaded energy storage system, and a storage medium. The cascaded energy storage system comprises N sub-modules connected in a cascade mode, where N≥2. The modulation method comprises: according to N carriers, modulating waveform signals that are output by N sub-modules, wherein the N carriers correspond to the N sub-modules on a one-to-one basis; and during modulation, performing at least one instance of synchronization delay on the N carriers, so as to synchronously change initial phase angles of the N carriers, wherein during the synchronization delay, the amplitudes of the carriers remain unchanged.