Reconfigurable Three-Phase Rectifier for Wide Ripple-Free DC Output
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Solution Overview
Problem
Conventional three-phase rectifiers face limitations in achieving wide output voltage ranges while maintaining high efficiency and reliability, particularly due to the need for bulky electrolytic capacitors to filter double line frequency ripple and the inability to distribute voltage and current stresses effectively among modules.
Innovation Solution
A single-stage three-phase rectifier topology with reconfigurable output connections, utilizing multiple converter modules in each phase, cancels out double line frequency ripple at the output, allowing for equal sharing of voltage and current, and enables the use of low-voltage devices, thereby eliminating the need for electrolytic capacitors and reducing component size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional three-phase rectifiers use electrolytic capacitors to filter double line frequency ripple, then output voltage stability is improved, but device volume and weight increase significantly
Solution Approach 1:
The patent converts the harmful double line frequency ripple into a beneficial feature by using it to drive a dual-frequency resonant tank circuit. The ripple energy that would normally require large capacitors to filter is instead utilized to generate high-frequency oscillations that achieve voltage multiplication and stabilization without bulky passive components
Solution Approach 2:
The patent replaces the traditional mechanical/electrical filtering system (electrolytic capacitors) with a resonant oscillating system. The dual-frequency resonant tank circuit uses electromagnetic resonance to achieve voltage regulation and ripple filtering, substituting passive component-based filtering with active resonant-based filtering
2Productivity
If single-stage three-phase rectifiers are used to achieve high voltage levels, then power density is improved, but the ability to handle wide voltage ranges is limited
Solution Approach 1:
The patent implements a reconfigurable output stage that can dynamically switch between series and parallel connections of the resonant tank circuits. This dynamic reconfiguration allows the system to adapt to different voltage requirements while maintaining high power density, enabling both wide voltage range operation and efficient high-voltage performance
Solution Approach 2:
The patent divides the single-stage rectifier into multiple independent resonant tank modules that can be independently controlled and reconfigured. Each module operates as a separate unit, allowing flexible combination to achieve different voltage levels and power outputs, thereby enhancing both adaptability and power density
Data Source
AI summary
A three phase rectifier includes n converter modules in each phase A, B, and C, wherein the AC inputs of the n converter modules of each phase are connected together in parallel, and the DC outputs of respective first to nth converter modules of phases A, B, and C are connected together in parallel as first to nth sub-combinations of DC outputs. The first to nth sub-combinations of DC outputs may be connected together in selected modes to produce a range of total output DC voltage, wherein the range of total output DC voltage is substantially free of double line frequency ripple and the converter modules are implemented without electrolytic output capacitors. The three phase rectifier is suitable for use in high power applications such as electric vehicle fast chargers.