N-Phase Full Bridge Converter Phase Shift Control
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Solution Overview
Problem
Conventional high-power full bridge converters face challenges in managing conduction current and switching losses due to parallel power switches with varying parameters, leading to increased cost and heat dissipation issues, especially as output power increases.
Innovation Solution
An n-phase full bridge power converter is designed with multiple bridge legs and transformers, utilizing n-phase pulse-width modulation (PWM) to balance conduction currents and reduce switching stress, featuring power switches like MOSFETs, BJTs, or IGBTs, with inductors and transformers configured to minimize conduction current in central bridge legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel power switches are used in conventional full bridge converters to handle high power, then the power handling capability is improved, but the conduction current per switch decreases and current distribution becomes uneven due to parameter variations
Solution Approach 1:
The patent divides the single high-power full bridge converter into multiple isolated full bridge modules (first, second, third, and fourth modules). Each module operates independently with its own primary side circuit, secondary side circuit, and control circuit. This segmentation allows each module to handle a portion of the total power while maintaining balanced current distribution, as each module's switches operate with controlled phase shifts rather than requiring precise matching of parallel switches.
2Power
If the number of parallel power switches is increased to handle higher output power, then the power output capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent combines multiple isolated full bridge modules in parallel on the secondary side to achieve high power output. While each individual module uses a standard number of switches (typically 4-6 per bridge), the modular architecture allows power scaling without proportionally increasing the complexity of each module. The modules share common secondary side rectification and filtering circuits, reducing overall component count compared to a single large-scale converter design.
3Loss of energy
If phase-shift modulation is used to reduce switching loss and switching stress, then the efficiency is improved, but the conduction current distribution among parallel switches remains uneven
Solution Approach 1:
The patent introduces phase shift control as an intermediary mechanism between the switching commands and the power transfer. By applying different phase shifts to the gating signals of corresponding switches in adjacent bridge legs (e.g., phase shift θ between first and second legs, phase shift φ between third and fourth legs), the converter achieves balanced current distribution across all switches. This phase shift intermediary allows each switch to operate at optimal switching conditions while maintaining uniform current sharing, thereby reducing both switching losses and current distribution inequalities.
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
The solution effectively reduces conduction current and switching losses, maintaining efficiency while decreasing the number of power switches, thus lowering costs and improving heat management for high-power applications.
Implementation Method 1
a plurality of transformers, each being coupled between two nodes each disposed between two power switches in two adjacent bridge legs on its primary side and coupled to the load device on its secondary side
Implementation Method 2
a plurality of inductors, each being connected between a node and the primary side of one of the transformers corresponding thereto
Implementation Method 3
each bridge leg comprising two power switches Q1 to Q6. Each power switch further comprises a diode, for example an internal stray diode or internal diode in the power switch
Data Source
AI summary
An N-phase full bridge power converter, comprising: a load device; a plurality of bridge legs, each being composed of two power switches; a plurality of transformers, each being coupled between two nodes each disposed between two power switches in two adjacent bridge legs on its primary side and coupled to the load device on its secondary side; and a plurality of inductors, each being connected between a node and the primary side of one of the transformers corresponding thereto.