Half-Bridge Converter Topology for High-Frequency Asymmetrical Pulses
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Solution Overview
Problem
Existing systems struggle to provide asymmetrical voltage pulses at high frequencies and handle high voltages required for industrial metal surface treatments like electroerosion, anodizing, and electropolishing, and they require high-performance DC power supplies and parallel DC buses, which are prone to short-circuits.
Innovation Solution
A direct current to asymmetrical square wave alternating current converter using a bridge structure with two Half-bridge substructures and SiC MOSFET commuters, allowing high-frequency commutation without requiring high-performance DC power supplies, and enabling parallel operation of two DC buses without short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Full-bridge topology is used to generate asymmetrical voltage pulses, then asymmetrical voltages can be produced, but commutation frequency is limited to around kHz due to DC bus voltage stabilization requirements
Solution Approach 1:
The Full-bridge topology is segmented into two independent Half-bridge substructures, each with its own DC bus and power supply. This segmentation allows each half-bridge to operate independently at high commutation frequencies without requiring the entire DC bus to be stabilized at high frequencies, thus resolving the contradiction between high commutation speed and DC bus voltage stability.
2Adaptability or versatility
If two DC buses are used in parallel to provide different voltages, then asymmetrical voltages can be provided, but short-circuits occur between the two power supplies
Solution Approach 1:
The patent introduces an intermediary control mechanism through the Half-bridge topology and commuting devices that mediates between two DC power supplies with different voltages. The commuting devices control the connection and disconnection of each DC bus independently, preventing direct parallel connection that would cause short-circuits, while still enabling the system to provide asymmetrical voltages.
3Speed
If high-performance DC power supplies with microsecond regulation dynamics are used, then high-frequency commutation can be supported, but system complexity and cost increase
Solution Approach 1:
By segmenting the system into two independent Half-bridge substructures, each power supply only needs to support the commutation frequency of its respective half-bridge, not the full system frequency. This reduces the regulation dynamics requirement from microsecond level to millisecond level, significantly simplifying power supply specifications and reducing system complexity.
Data Source
AI summary
A direct current to asymmetrical square wave alternating current converter is provided that includes two direct current supplies A and B, that provide, respectively, VA and VB output voltages; and four commuting devices (Q1, Q2, Q3 and Q4); in that the power supplies and the commuters form a bridge structure of, at least two Half-bridge substructures, each of which includes two commuting devices and, at least, a direct current power supply. The Half-bridge substructures are connected to each other in the intermediate and low branches, where the work charge RL is connected in the intermediate branch.