Multi-Phase Multi-Level Converter With Self-Balancing Capacitor Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-level converters are not suitable for high power applications below 1 kV due to high component count, inefficient operation, and capacitor voltage sensing, and they require complex control methods, especially for low voltage applications, and capacitor voltage sensing.
Innovation Solution
A transformer with a primary side circuit comprising a plurality of primary switch legs and a secondary side circuit with secondary rectifier legs, connected in parallel, and a transformer with a phase shift of switching signals, reducing the number of components and enabling efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-level topology is used to achieve wide output voltage range, then the output voltage range is improved, but the device becomes unsuitable for high power requirements
Solution Approach 1:
The converter is divided into multiple phases (three-phase configuration) with each phase handling a portion of the total power. This segmentation allows the system to achieve high power output while maintaining the multi-level voltage conversion capability, as each phase can be independently optimized for power handling.
Solution Approach 2:
The patent transitions from a single-phase multi-level topology to a multi-phase topology, adding the phase dimension to the system. This dimensional change enables the converter to simultaneously achieve wide output voltage range through multi-level switching and high power handling through parallel phase operation.
2Device complexity
If single-phase configuration is used, then the circuit structure is simplified, but large capacitive filters are required at input and output stages
Solution Approach 1:
The single-phase configuration is segmented into multiple phases, which distributes the filtering requirements across phases. The multi-phase structure naturally reduces the ripple current magnitude compared to single-phase, allowing for smaller capacitive filters while maintaining the same output voltage quality.
3Stress or pressure
If n stacked full bridge inverter cells with transformers are used, then high voltage capability is achieved, but the converter employs high number of components and has low efficiency
Solution Approach 1:
The patent merges multiple full bridge inverter cells into a unified multi-phase topology where phases share common components. Instead of using n separate full bridges each with its own transformer, the invention uses a single transformer with multiple phases, significantly reducing the component count while maintaining high voltage capability through the multi-level switching strategy.
4Stress or pressure
If n stacked full bridge inverter cells are used, then high voltage capability is achieved, but the control method becomes highly complicated
Solution Approach 1:
The patent employs homogeneous switching patterns across all phases, where each phase follows the same control logic with appropriate phase shifts. This homogeneous control approach simplifies the overall control complexity compared to managing n independent full bridges, as the same control algorithm can be applied to each phase with minimal modification.
5Reliability
If capacitor voltage sensing circuits are used to maintain DC link capacitor voltages, then voltage balance is achieved, but the number of components and costs increase
Solution Approach 1:
The multi-phase topology enables self-balancing of DC link capacitor voltages through the natural interaction between phases. The phase-shifted switching patterns create circulating currents that automatically equalize capacitor voltages without requiring external sensing and control circuits, thereby reducing component count while maintaining voltage balance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed converter achieves high power output with reduced components, lower voltage and current ripples, balanced resonant currents, and efficient operation, suitable for low voltage applications.
Implementation Method 1
A transformer with a primary side circuit (5) connected to a primary side (3) of the transformer (2)... and a secondary side circuit (7) connected to a secondary side (4) of the transformer (2)
Data Source
AI summary
The disclosure concerns a multi-level multi-phase converter, comprising: a transformer with multiple phases; a primary side circuit connected to a primary side of the transformer, the primary side circuit comprising multiple parallel connected primary switch legs having primary switches, wherein a number N of phases of the transformer corresponds to that of primary switch legs; and a secondary side circuit connected to a secondary side of the transformer, the secondary side circuit comprising multiple secondary rectifier legs with secondary rectifier elements, wherein the secondary rectifier legs are connected in parallel; wherein each of the primary switch legs comprises multiple stacked primary half-bridges connected in series; and each phase of the primary side of the transformer is connected between two primary half-bridges connected in series. The disclosure also concerns a control method for operating the multi-level multi-phase converter.