Cyclo-Converter Switching Frequency Control via Phase Segmentation
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Solution Overview
Problem
Existing three-phase resonant cyclo-converters lack effective control mechanisms to manage switching frequency across the full phase of an input power signal, leading to inefficiencies and inaccuracies in output voltage regulation.
Innovation Solution
A closed-loop control system that develops a switching frequency control signal based on accumulated voltage signal values and error signals, using a combination of proportional, integral, and derivative feedback terms to adjust the switching frequency of the cyclo-converter, ensuring precise control over the output voltage across the entire 360-degree phase range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proportional and integral feedback elements are used to control switching frequency, then output voltage can be adjusted, but control over the full phase of input power signal is insufficient
Solution Approach 1:
The control method segments the input power signal phase into multiple discrete phase portions (e.g., 0-60 degrees, 60-120 degrees, etc.). For each phase portion, separate accumulated voltage signal values are maintained and used for control decisions. This segmentation allows the system to apply appropriate control strategies tailored to each phase segment, achieving comprehensive full-phase control while maintaining precise voltage regulation.
2Loss of energy
If single-stage power conversion is used, then efficiency is improved and component size is reduced, but control complexity increases
Solution Approach 1:
The control system implements closed-loop feedback by continuously monitoring the output voltage and comparing it with reference values. The feedback mechanism uses accumulated voltage signal values from previous cycles to adjust the switching frequency dynamically. This feedback approach enables the single-stage converter to maintain high efficiency while achieving precise voltage control through iterative correction, balancing the trade-off between simplicity and control accuracy.
Solution Approach 2:
The system performs preliminary actions by pre-calculating and accumulating voltage signal values for each phase portion before the actual switching operation. This preliminary computation allows the controller to anticipate the required switching frequency adjustments in advance, simplifying the real-time control decision-making process while maintaining precise voltage regulation throughout the full phase range.
Data Source
AI summary
A three-phase resonant cyclo-converter including a closed loop control module for controlling the switching frequency of the cyclo-converter, the closed loop control module including: a voltage signal development module arranged to develop a voltage signal representative of a voltage output waveform of the cyclo-converter, a storage module arranged to accumulate voltage signal values for phase portions of the voltage output waveform, where the voltage signal values are based on a voltage error signal and accumulated historical voltage signal values for the same corresponding phase portions, and a switching frequency control module arranged to develop a switching frequency control signal to control the switching frequency of the cyclo-converter based on the accumulated voltage signal values for corresponding phase portions of the voltage output waveform, and a proportional voltage signal based on a difference between the developed voltage signal and a reference voltage signal.