Full-Bridge Switching Circuit Phase Shift Control
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Solution Overview
Problem
Conventional soft switching techniques in full-bridge circuits face challenges in maintaining balanced current stress across switches, leading to inconsistencies in heat generation and reliability due to imbalances in current stress, which complicates cooling mechanisms and switch lifespan.
Innovation Solution
A switching circuit with a full-bridge configuration and a control circuit that outputs specific control signal groups to alternately change the states of switches, ensuring balanced current stress by alternating between two distinct cycles of switch on/off sequences, thereby equalizing current stress across all switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional soft switching techniques are used in full-bridge circuits, then switching loss is reduced and ZVS is achieved, but current stress becomes unbalanced across switches leading to inconsistent heat generation and reliability
Solution Approach 1:
The patent applies periodic action by alternating between two different switching cycles (first cycle and second cycle) with different phase shifts. In the first cycle, the phase shift is set to a first value, and in the second cycle, it is set to a second value. This periodic alternation ensures that current stress is balanced across all switches over time, preventing any single switch from bearing excessive stress continuously, thereby maintaining both low switching loss and high reliability.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the phase shift parameter between two distinct values. By changing the phase shift from a first value to a second value alternately, the current distribution across the switches is optimized. This parameter modulation allows the circuit to achieve zero-voltage switching while distributing current stress evenly, thus resolving the contradiction between energy loss reduction and reliability improvement.
2Device complexity
If conventional switching control is used, then circuit operation is simple, but heat generation is inconsistent across switches requiring complex cooling mechanisms
Solution Approach 1:
The control circuit implements periodic action by alternating between two predefined switching cycles with different phase shift values. This simple periodic alternation balances the heat generation across all switches without requiring complex real-time monitoring or adjustment mechanisms. The uniform heat distribution simplifies the cooling system design while maintaining straightforward control logic.
3Ease of operation
If single-cycle phase-shift control is used, then control is straightforward, but switch lifespan is reduced due to unbalanced current stress
Solution Approach 1:
The patent employs periodic action by alternating between first and second switching cycles with different phase shift values. This periodic alternation distributes current stress evenly across all switches over time, preventing any single switch from experiencing excessive stress continuously. The control remains relatively simple while significantly extending switch lifespan through this alternating cycle approach.
Solution Approach 2:
The patent applies parameter changes by modulating the phase shift between two distinct values in an alternating manner. This parameter variation balances the electrical stress on each switch, ensuring more uniform wear and extending overall switch lifespan. The control complexity remains low as it only requires switching between two predefined parameter sets.
Data Source
AI summary
A switching circuit according to an aspect of the present disclosure includes: a full-bridge circuit including a first leg that includes a first switch and a second switch, and a second leg that includes a third switch and a fourth switch; and a control circuit operative to (a) output a first control signal group that changes the first leg into a state in which the third switch is off and the fourth switch is on after changing the first leg into a state in which the first switch is on and the second switch is off, and (b) output a second control signal group that changes the second leg into a state in which the third switch is off and the fourth switch is on before changing the first leg into a state in which the first switch is on and the second switch is off.