Power Converter with Controllable DC Offset for Parallel Operation
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Solution Overview
Problem
Existing power conversion systems face challenges in efficiently managing differential and common-mode voltages between AC and DC power sources, leading to issues with isolating electrical loads and maintaining consistent voltage levels, particularly when multiple converters are connected in parallel.
Innovation Solution
The system employs a configuration of AC-to-DC and DC-to-DC power converters with controllable DC offsets, using switching legs and filtering elements to manage voltages and ensure compatibility between AC and DC power sources, allowing for bidirectional power flow and parallel connection without creating short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple power converters are connected in parallel to supply power to a single load, then the power supply capacity and system flexibility are improved, but voltage inconsistencies and potential short circuits occur between the converters
Solution Approach 1:
The patent introduces a common-mode voltage control mechanism as an intermediary to mediate between multiple parallel-connected power converters. By controlling the common-mode voltage at each converter's output, the system ensures voltage consistency across all converters while allowing them to operate in parallel, preventing short circuits and maintaining reliable power supply.
Solution Approach 2:
The patent changes the voltage control parameter from solely differential mode voltage to include both differential mode and common-mode voltage control. By adjusting the common-mode voltage parameter, the system resolves voltage inconsistencies that arise when multiple converters operate in parallel, enabling reliable parallel operation while maintaining the improved power supply capacity.
2Reliability
If power converters are designed to convert between AC and DC power with isolation, then electrical load isolation is improved, but the complexity of voltage control increases
Solution Approach 1:
The patent segments the voltage control function into two independent parts: differential mode voltage control and common-mode voltage control. This segmentation allows the isolation function to be maintained while simplifying the overall control complexity, as each mode can be controlled separately through dedicated control circuits rather than requiring a single complex control mechanism.
Solution Approach 2:
The power converter is designed with multi-functionality, simultaneously providing electrical load isolation, differential voltage regulation, and common-mode voltage control. By integrating these functions into a single converter design, the patent achieves improved isolation without proportionally increasing complexity, as the control mechanisms work together in a unified system.
3Object-affected harmful factors
If the common-mode voltage is controlled to prevent short circuits between parallel converters, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the common-mode voltage is continuously monitored and adjusted based on the operating conditions of parallel-connected converters. This feedback approach improves safety by dynamically preventing short circuits while keeping the control circuit complexity manageable, as the system automatically adjusts without requiring complex manual intervention or oversized control hardware.
Data Source
AI summary
An electrical power conversion system includes an alternating current (AC)-to-direct current (DC) power converter that is configured to convert power between AC power and DC power. The AC-to-DC power converter includes switching legs that each connect to a phase of the AC power. Each of the switching legs includes two electronic devices connected in series with one another between a positive DC bus terminal and a negative DC bus terminal. The electrical power conversion system also includes a DC-to-DC power converter that is configured to convert power between the DC bus power and DC terminal power via a positive DC terminal and a negative DC terminal. The DC-to-DC power converter is configured to control a differential voltage between the positive and negative DC terminals and a common-mode voltage that is between a neutral of the AC power and each of the positive and negative DC terminals.