Interleaved Multi-Bridge Converter for Wide DC Voltage Range
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Solution Overview
Problem
Designing power converters that maintain high efficiency while providing a wide range of DC voltage, from 200 V to 800 V, is challenging, especially for applications like electric vehicle charging, where mechanical DC contacts are bulky, costly, and have limited lifetimes.
Innovation Solution
The power converter employs a pair of transformers with interleaved multi-bridge circuits and a controller that operates in series or parallel modes, along with half or full bridge configurations, to achieve a wide DC voltage range with high efficiency, using high switching frequency and soft switching techniques to reduce losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical DC contacts are used to switch between different voltage ranges, then the power converter can achieve wide DC voltage range, but the device becomes bulky, costly, and has limited lifetime
Solution Approach 1:
The patent replaces mechanical DC contacts with an electronic switching system using IGBTs (insulated-gate bipolar transistors) arranged in bridge circuits. The controller electronically switches between series and parallel configurations of the bridge circuits to achieve different voltage ranges (200V-400V and 400V-800V), eliminating mechanical moving parts and their associated problems of bulk, cost, and limited lifetime.
Solution Approach 2:
The patent implements a dynamic switching system where the controller can change the configuration of the bridge circuits from series to parallel and vice versa based on the required output voltage. This dynamic reconfiguration allows the power converter to adapt to different voltage requirements without mechanical contacts, achieving wide DC voltage range through electronic control.
2Volume of moving object
If high switching frequency is used to reduce converter size, then the power converter becomes more compact, but switching losses increase reducing efficiency
Solution Approach 1:
The patent employs soft switching techniques that change the switching parameters of the IGBTs to achieve zero-voltage switching (ZVS) or zero-current switching (ZCS). This allows high switching frequencies to be used for compact converter design while minimizing switching losses by ensuring switches transition when voltage or current is zero, thereby maintaining high efficiency.
Solution Approach 2:
The patent uses resonant circuits with inductors and capacitors to create periodic oscillations that facilitate soft switching. The resonant action periodically charges and discharges the switching devices, enabling them to switch at optimal moments in the cycle, thus reducing switching losses while allowing high frequency operation for compact size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for a compact, economical, and efficient power converter with a long lifespan, capable of bi-directional power flow and wide DC voltage range, suitable for electric vehicle charging, while avoiding the limitations of mechanical contacts.
Implementation Method 1
A transformer may be used to provide electrical isolation between two electrical circuits
Implementation Method 2
Each power converter stage has a first port connected to the first side of one of the transformers. Each power converter stage has a second port that receives or provides a DC input or output voltage, depending on the direction of power flow. The power converter stages are configured to transfer power between their respective first and second ports
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
According to one aspect of the present disclosure, there is provided an apparatus that includes a first power converter stage connected to a first side of a first transformer, and a second power converter stage connected to a first side of a second transformer. The apparatus further includes an interleaved multi-bridge circuit connected to the second side of the first transformer and to the second side of the second transformer. The apparatus further includes a controller that is configured to operate the interleaved multi-bridge circuit in a parallel mode in which the second sides of the first and second transformers are in parallel at a DC terminal of the interleaved multi-bridge circuit and in a series mode in which the second sides of the first and second transformers are in series at the DC terminal.