Frequency-Controlled Switch Arm Deadtime Adjustment
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Solution Overview
Problem
In frequency-controlled switch arms, such as H bridges, the deadtime duration is often fixed and excessively long, failing to adapt to varying switching frequencies and electrical magnitudes, leading to inefficient soft switching in DC/DC voltage converter circuits.
Innovation Solution
A method that adjusts the deadtime duration in real-time by measuring the voltage at the midpoint of the switch arm, comparing it with a threshold, and calculating an optimized duration using the formula DT=(t2-t1-1/2·FSW), ensuring efficient soft switching regardless of switching frequency or input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed deadtime is used in frequency-controlled switch arms, then the switching elements are protected from cross-conduction, but the deadtime becomes excessively long and reduces switching efficiency
Solution Approach 1:
The patent applies dynamics by making the deadtime duration variable rather than fixed. The control device adjusts the deadtime dynamically based on the switching frequency and electrical magnitudes (voltage and current) in real-time. This allows the system to maintain sufficient deadtime for cross-conduction protection while minimizing unnecessary time loss during switching operations.
Solution Approach 2:
The patent changes the parameter of deadtime duration from a constant value to a variable parameter that adapts to different operating conditions. By monitoring switching frequency, voltage, and current, the control device modifies the deadtime parameter accordingly, optimizing the balance between reliability and switching efficiency.
2Productivity
If the deadtime is shortened to improve switching speed, then switching efficiency increases, but the risk of cross-conduction between switching elements increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the switching frequency, voltage, and current in the circuit. Based on this feedback information, the control device adjusts the deadtime duration to ensure adequate protection against cross-conduction while maintaining high switching speed. The feedback loop enables real-time optimization of the deadtime parameter.
Solution Approach 2:
The system uses dynamics to adapt the deadtime duration to actual operating conditions. Rather than using a conservative fixed value, the deadtime is dynamically adjusted based on real-time measurements of voltage, current, and switching frequency, allowing faster switching when conditions permit while maintaining safety margins when needed.
3Reliability
If the deadtime is extended to ensure soft switching, then the switching elements are protected, but the switching frequency and overall system efficiency are reduced
Solution Approach 1:
The patent changes the deadtime parameter from a fixed conservative value to a dynamically adjusted value based on actual circuit conditions. By monitoring voltage and current waveforms, the control device determines the minimum deadtime required for soft switching and adjusts accordingly, preventing unnecessary extensions that would limit switching frequency.
Solution Approach 2:
The system performs self-service by automatically adjusting its own deadtime parameter based on real-time measurements of its operating state. The control device monitors the circuit conditions and autonomously modifies the deadtime to achieve soft switching without requiring external intervention or overly conservative fixed settings.
4Device complexity
If a fixed deadtime is used, then the control system is simple, but it cannot adapt to varying switching frequencies and electrical magnitudes
Solution Approach 1:
The patent applies dynamics by transforming the static control system into a dynamic one that adapts to varying conditions. The control device continuously monitors switching frequency, voltage, and current, and adjusts the deadtime parameter in real-time, enabling the system to adapt to different operating points while maintaining reasonable complexity through systematic control logic.
Solution Approach 2:
The system implements feedback mechanisms to detect changes in switching frequency and electrical magnitudes, and uses this information to adjust the deadtime parameter. This feedback-based adaptation enables the system to respond to varying conditions automatically, balancing the need for adaptability with acceptable control system complexity.
Data Source
AI summary
A method for controlling switching of an electrical system comprising having at least one frequency-controlled switch arm, includes the following steps: closing a first top or bottom switch, implementing a predetermined downtime and opening a second switch, for a period corresponding to the control frequency, and then: opening the first switch, comparing the voltage measured at the midpoint with a voltage threshold, determining a second instant t2 at which the voltage measured at the midpoint crosses the voltage threshold, closing the second switch at the second instant t2, calculating a downtime DT adjusted according to a formula which is a function of the control frequency Fsw, a first instant t1 and a second instant t2, the adjusted downtime being implemented as of the subsequent switching.