Hybrid Clamped Converter Control for Minimum DC-Bus Capacitance
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Solution Overview
Problem
High-power hybrid clamped converters face challenges in minimizing DC-bus capacitance, leading to increased system cost, volume, and reduced power density due to high voltage fluctuations, with existing methods lacking effective solutions for determining minimum capacitance values.
Innovation Solution
A design method for DC-bus capacitance minimization in hybrid clamped converters, involving the calculation of reference waves, switch duty ratios, neutral point currents, and capacitor voltage fluctuations, allows for the direct determination of minimum DC-bus capacitance values within allowable voltage fluctuation limits, reducing system complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the capacitance of the capacitor is increased to reduce voltage fluctuation, then the voltage stability is improved, but the volume and cost increase significantly
Solution Approach 1:
The patent changes the control parameters of the HCC system, specifically introducing a common-mode voltage component into the reference wave and adjusting switch duty ratios, to alter the voltage fluctuation characteristics without changing capacitor physical parameters
Solution Approach 2:
The patent implements a control method that calculates neutral point currents and adjusts switch duty ratios based on voltage fluctuation characteristics, creating a feedback mechanism that actively compensates for voltage variations, thereby reducing the need for large capacitor values
2Stability of the object's composition
If the capacitance of the capacitor is increased to reduce voltage fluctuation, then the voltage stability is improved, but the system cost increases
Solution Approach 1:
The patent modifies operational parameters including common-mode voltage injection and switch duty ratio control to change the voltage fluctuation profile, enabling the use of smaller, less expensive capacitors while maintaining stability
Solution Approach 2:
The control method uses calculated neutral point currents and voltage fluctuation characteristics to dynamically adjust switching operations, providing active compensation that reduces dependency on expensive high-capacitance components
3Stability of the object's composition
If the capacitance of the capacitor is increased to reduce voltage fluctuation, then the voltage stability is improved, but the power density decreases
Solution Approach 1:
The patent introduces common-mode voltage control and adjusts switching parameters to fundamentally change the voltage fluctuation behavior, enabling reduced capacitor size and improved power density while maintaining stability
Solution Approach 2:
The control system calculates and responds to voltage fluctuation characteristics in real-time, providing active stabilization that allows for smaller capacitor values and higher power density
Data Source
AI summary
The present invention provides a method for DC-bus capacitance minimization of hybrid clamped converter (HCC), which includes: obtaining the system parameters of the HCC during operation; determining the reference wave; determining the duty ratio of each switch according to the reference wave; determining the total neutral point current of the system; the fundamental component of the upper and lower DC-bus capacitor voltage of the system; determining the maximum voltage fluctuation of the upper and lower DC-bus capacitors; determining the minimum DC-bus capacitance value that satisfies the requirements of system capacitor voltage fluctuation by traversing the capacitance value. The present invention not only reduces the design complexity and cost of the high-power HCC system, but also improves the power density and reliability of the converter.