Energy Module On-Time Control for Switching Loss Reduction
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Solution Overview
Problem
Existing energy storage systems face issues with switching losses, heat generation, and electromagnetic disturbances due to high switching frequencies, which lead to wear and inefficiencies in battery modules.
Innovation Solution
The use of high-frequency switches with an H-bridge configuration and a string controller that ensures each energy module is turned on for a minimum on-time, dynamically controlling the on-time based on real-time evaluations and system references to reduce switching frequency and harmonics, thereby minimizing wear and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high switching frequencies are used to control the energy modules, then the control bandwidth is improved, but switching losses and heat generation increase
Solution Approach 1:
The patent applies periodic action by implementing a minimum on-time requirement for energy modules. Instead of continuous high-frequency switching, the system uses periodic switching with enforced idle periods (minimum on-time) between switching events. This reduces the overall switching frequency while maintaining control effectiveness through strategic timing of switching events, thereby reducing switching losses and heat generation while preserving adequate control bandwidth.
2Loss of time
If high switching frequencies are used, then the response time is improved, but wear of switches increases
Solution Approach 1:
The periodic action principle reduces switch wear by limiting the frequency of switching operations through the minimum on-time requirement. By enforcing periodic switching with mandatory idle periods, the system reduces the cumulative number of switching events and associated mechanical/electrical stress on switches, thereby extending their operational life and improving reliability while maintaining adequate response time through strategic switching timing.
3Measurement precision
If high switching frequencies are used, then the control precision is improved, but electromagnetic disturbances increase
Solution Approach 1:
The periodic action principle mitigates electromagnetic disturbances by reducing the switching frequency through minimum on-time enforcement. By spacing out switching events and reducing the overall switching rate, the system generates fewer high-frequency electromagnetic transients and reduces electromagnetic interference (EMI) while maintaining control precision through optimized switching timing and synchronization with the grid frequency.
4Loss of energy
If minimum on-time is enforced for energy modules, then switching losses are reduced, but the complexity of control increases
Solution Approach 1:
The periodic action principle simplifies control complexity by implementing a straightforward minimum on-time requirement that creates regular, predictable switching patterns. This periodic enforcement of idle periods between switching events provides a simple control rule that reduces switching losses without requiring complex algorithms, while the regularity of the switching pattern facilitates easier timing synchronization and control implementation.
Data Source
AI summary
The invention relates to a method of controlling the on-time of a plurality of energy modules of an energy storage. The energy storage comprising a plurality of series connected energy modules forming an energy module string. A string controller is controlling which of the individual energy modules that is part of a current path through the energy module string, by control of the status of a plurality of switches. The string controller is controlling the frequency of the energy module string voltage according to an electric system reference related to a system to which the energy storage is connected. And wherein the string controller is controlling the switches of the individual energy modules so that each of the individual energy modules that are required to be included in the current path to establish the energy modules string voltage are included in the current path for at least a minimum on-time.