Sequential Switch Circuit Driving for Power Converter Efficiency
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Solution Overview
Problem
Switching power supplies face issues with parasitic inductances and capacitances in power transistors leading to voltage fluctuations and short circuits, which are mitigated by introducing dead-time but at the cost of reduced efficiency.
Innovation Solution
A method of driving a switch circuit involves defining a driving sequence with multiple levels and time windows to apply electrical parameters sequentially, allowing for precise control of transistor switching to minimize ringing effects and reduce dead-time, thereby preventing short circuits while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead-time is introduced between transistor switching, then short circuits are prevented, but efficiency is reduced due to increased dead-time
Solution Approach 1:
The gate-source voltage transition is segmented into multiple stages with different slew rates. A first slew rate is applied during an initial time period, then a second slew rate is applied during a subsequent time period. This segmentation allows optimization of both switching speed and voltage fluctuation control, reducing the required dead-time while preventing short circuits.
Solution Approach 2:
The slew rate is made dynamic rather than constant. The system transitions between different slew rates at different stages of the voltage transition. This dynamic adjustment enables faster switching when safe, and slower switching when needed to control voltage fluctuations, thereby reducing overall dead-time while maintaining reliability.
2Object-affected harmful factors
If slow slew rate is applied during the whole transient period, then voltage fluctuations are reduced, but switching time increases and efficiency decreases
Solution Approach 1:
The transient period is divided into segments with different slew rate characteristics. During the first time period, a first slew rate is applied; during the second time period, a second slew rate is applied. This segmentation allows the system to achieve adequate voltage fluctuation control without unnecessarily extending the total switching time.
Solution Approach 2:
The slew rate parameter is changed during the transient period rather than maintaining a constant slow slew rate throughout. By switching between different slew rate values at appropriate moments, the system achieves both voltage fluctuation reduction and acceptable switching speed.
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 approach reduces instances of short circuits and enhances power efficiency by allowing for shorter switching times and reduced voltage oscillations, enabling operation at higher frequencies with improved noise reduction.
Implementation Method 1
Power transistors often display significant parasitic inductances and capacitances at their gate, source and drain
Data Source
AI summary
A sequential driving method for driving a switch circuit of a power converter is presented. The method has the steps of driving a switch circuit which contains a power switch, defining a driving sequence; and applying sequentially an electrical parameter to the power switch, based on the driving sequence. Defining a driving sequence includes defining a plurality of different driving levels associated with the electrical parameter and defining a plurality of time windows within a switching time period. Each time window is associated with a driving level among the plurality of driving levels.