Voltage-Based Energy Balancing in Modular Multilevel Converters
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Solution Overview
Problem
Conventional methods for balancing energy in modular multilevel converters and switched-capacitor circuits rely heavily on complex current measurements, which are prone to errors and faults, leading to potential system instability and high costs due to the need for precise and frequent data transmission.
Innovation Solution
The solution involves using voltage measurements to estimate module voltages and energy content, treating the system as a coding system where voltage is the central measurement, and employing matrix-vector equations to determine module states and voltages, reducing the reliance on current measurements and simplifying data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex current measurements are used for energy balancing in modular multilevel converters, then measurement precision can be improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the essential information needed for energy balancing by using only voltage measurements instead of complex current measurements. By measuring voltage across capacitors and using the known switching states, the system obtains sufficient data for energy calculation without the need for complex current measurement infrastructure, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent creates a simplified measurement model that copies only the necessary information (voltage levels) rather than measuring all current parameters. This selective copying of essential data reduces the measurement infrastructure complexity while preserving the accuracy needed for energy balancing operations.
2Measurement precision
If frequent and precise current data transmission is implemented, then energy balancing accuracy is improved, but loss of time and communication overhead increase
Solution Approach 1:
The patent extracts only the essential voltage information needed for energy balancing and transmits this simplified data instead of complete current waveforms. This extraction of necessary information reduces communication overhead and transmission time while maintaining the accuracy required for effective energy balancing.
Solution Approach 2:
The patent applies partial action by measuring and transmitting only the specific voltage parameters that are sufficient for energy balancing, rather than transmitting complete current data. This partial measurement approach reduces communication time and overhead while providing adequate precision for the control task.
3Reliability
If extensive current measurement infrastructure is deployed, then measurement coverage is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the critical measurement information from complex current measurements and obtains it through simpler voltage measurements combined with switching state knowledge. This extraction approach maintains measurement reliability for energy balancing purposes while significantly reducing the complexity of the measurement infrastructure required.
Solution Approach 2:
The system uses the already-available switching state information (which is naturally present in the converter operation) in combination with voltage measurements to derive energy information. This self-service approach leverages existing system data to reduce the need for additional complex measurement infrastructure.
Data Source
AI summary
Prior art electronic power supplies having distributed energy stores and/or the possibility to dynamically modify the connectivity of individual stores require complex monitoring of the input and output currents to and from the individual energy stores, often using a multitude of sensors, in order to allow for unrestricted operation. Examples of such power supplies include in particular modular multilevel converters and switched-capacitor circuits. The preen invention describes a possibility to determine the states of charge and energy levels of the energy stores using a small number of measuring systems.