PSFB Converter Bridge Arm Turn-Off Loss Balancing
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Solution Overview
Problem
The reliability of phase-shifted full bridge (PSFB) converters is compromised due to uneven lifespan of their bridge arms, leading to differences in turn-off losses that affect overall converter reliability.
Innovation Solution
A control method that alternates the roles of the leading and lagging bridge arms by switching their states based on a timer, adjusting the phase difference and drive frequency to ensure balanced turn-off losses, thereby extending the lifespan and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PSFB converter operates with a fixed leading and lagging bridge arm configuration, then the control is simple and stable, but the turn-off losses become uneven between bridge arms leading to reduced reliability
Solution Approach 1:
The patent applies periodic action by alternating the leading and lagging bridge arm configurations at regular intervals. The controller switches which bridge arm operates as the leading bridge arm and which operates as the lagging bridge arm after a predetermined period, ensuring that each bridge arm experiences both roles over time. This periodic switching equalizes the turn-off losses accumulated in different bridge arms, thereby improving overall converter reliability without requiring complex real-time adjustments
Solution Approach 2:
The patent implements dynamics by making the bridge arm roles dynamic rather than fixed. Instead of permanently assigning specific bridge arms as leading or lagging, the system dynamically reassigns these roles based on operational time or loss accumulation thresholds. This dynamic reassignment allows the system to adapt and balance the thermal and electrical stress across all bridge arms, resolving the reliability issue caused by static configuration
2Speed
If the phase difference between drive signals is abruptly changed to switch bridge arm roles, then the state switching is fast, but voltage spikes and current shocks occur reducing stability
Solution Approach 1:
The patent applies preliminary action by preparing for the bridge arm role switch in advance. Before actually switching the leading and lagging configurations, the controller first adjusts the phase difference between drive signals gradually over a transition period. This preliminary phase difference adjustment ensures that when the bridge arm roles are switched, the voltage and current are already in a stable state, preventing sudden spikes or shocks that would occur with abrupt switching
Solution Approach 2:
The patent implements parameter changes by gradually modifying the phase difference parameter during the bridge arm role transition. Instead of instantly changing the phase difference from one value to another, the controller incrementally adjusts this parameter over time, ensuring that the electrical parameters (voltage and current) remain stable throughout the transition. This controlled parameter change prevents harmful transients while achieving the desired state switch
Data Source
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AI summary
A method for controlling a PSFB converter, an apparatus, and a storage medium are disclosed, and relate to the field of power supply technologies. The method includes: controlling, by a control circuit after controlling a first clock and a second clock to operate in a first state for a time period, the first clock and the second clock to switch to a second state, where when the first clock and the second clock operate in the first state, the first bridge arm is a leading bridge arm, and the second bridge arm is a lagging bridge arm, and when the first clock and the second clock operate in the second state, the first bridge arm is a lagging bridge arm, and the second bridge arm is a leading bridge arm. According to this application, a turn-off loss of the first bridge arm and a turn-off loss of the second bridge arm become almost the same, thereby improving reliability of the PSFB converter.