Hybrid AC-DC Converter Using Wide-Bandgap and Silicon Switches
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Solution Overview
Problem
Conventional multilevel rectifiers face limitations in power density, reliability, and efficiency due to electrical stress on solid-state devices and the need for additional gate drivers and voltage balancing circuitry, which increases cost and reduces performance in applications like aerospace and renewable energy systems.
Innovation Solution
A single-phase AC/DC power converter system utilizing a combination of high-frequency wide-bandgap devices and low-frequency silicon-based switches, with a multi-level and two-level conversion stage, to achieve high power density and efficiency while reducing component costs through optimized switching and modulation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional multilevel rectifier topology is used, then voltage level multiplication is achieved, but device count and system complexity increase proportionally
Solution Approach 1:
The converter is divided into two independent single-phase full-bridge converters operating in parallel, each handling a portion of the total power. This segmentation allows the system to achieve high power output without requiring a complex multilevel topology, as each module uses only standard two-level bridges with minimal devices.
Solution Approach 2:
The two independent full-bridge converters serve multiple functions simultaneously: they perform rectification, provide galvanic isolation through transformers, enable parallel power synthesis, and facilitate modular scalability. This multi-functionality eliminates the need for additional dedicated components that would increase overall device count.
2Stability of the object's composition
If voltage balancing circuitry is added to control DC link capacitor voltages, then voltage balance is improved, but power density and efficiency decrease
Solution Approach 1:
The system achieves voltage balance autonomously through natural operation of the two parallel full-bridge converters. The independent control of each converter allows automatic load sharing and voltage equalization without requiring external balancing circuitry, thereby maintaining high power density and efficiency.
Solution Approach 2:
The control system continuously monitors the DC link capacitor voltages and adjusts the switching duties of the two full-bridge converters to maintain voltage balance. This feedback-based control achieves stable voltage composition without adding physical balancing components that would reduce power density.
3Loss of energy
If wide-bandgap devices are used, then switching efficiency is improved, but device cost increases
Solution Approach 1:
Wide-bandgap devices are deployed selectively in specific switching positions where their high-frequency switching capability provides maximum benefit, such as in the primary full-bridge converter handling high-voltage switching. Standard silicon devices are used in other positions where their performance is sufficient, optimizing the overall cost-performance balance of the system.
Solution Approach 2:
The system employs a composite device architecture combining wide-bandgap and silicon-based semiconductors in the same converter system. This hybrid approach leverages the superior switching characteristics of wide-bandgap devices where needed while utilizing the cost-effectiveness and reliability of silicon devices in other applications, achieving both low loss and reasonable cost.
Data Source
AI summary
System and methods for power conversion are provided. Aspects include a first switching module comprising a first set of switches, wherein the first set of switches comprise wide-bandgap devices having a first bandgap, a second switching module comprising a second set of switches, wherein the second set of switches comprise semiconductor devices having a second bandgap, and wherein the first bandgap is larger than the second bandgap, an alternating current (AC) power source connected to the first switching module and the second switching module, a first capacitor bank, a second capacitor bank, and a controller configured to operate the first switching module and the second switching module to create a first direct current (DC) voltage across the first capacitor bank and a second direct current (DC) voltage across the second capacitor bank.