Switch Driving Circuit Dynamic Dead Time Control
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Solution Overview
Problem
Conventional switch driving circuits experience hard switching when operating with capacitive loads, leading to increased power loss and potential damage to switching elements due to the high voltage difference between the drain and source electrodes during switching operations.
Innovation Solution
A switch driving circuit that includes a dead time controller and phase detector to generate controlling signals for high-side and low-side switches, allowing for advanced phase alignment of switch turn-on times with resonance current phase changes, thereby reducing dead time and preventing hard switching by optimizing the switching operation based on phase information and voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If zero voltage switching control method is used to turn on switches when voltage difference is about 0V, then conduction loss is decreased, but hard switching is generated when resonance circuit is in capacitive load condition
Solution Approach 1:
The patent implements dynamic dead time adjustment based on the operating state of the resonance circuit. The control device detects whether the resonance circuit is in capacitive or inductive load condition and dynamically adjusts the dead time period accordingly. This dynamic adaptation allows the system to maintain zero voltage switching in capacitive conditions while preventing hard switching, thereby resolving the contradiction between reducing conduction loss and ensuring switching element reliability.
Solution Approach 2:
The patent employs a feedback mechanism where the control device monitors the operating state of the resonance circuit (capacitive or inductive condition) and uses this information to adjust the dead time period. This closed-loop control enables the system to respond to changing load conditions and maintain optimal switching performance, preventing hard switching while minimizing conduction losses.
2Reliability
If dead time is increased to prevent hard switching, then switching element reliability is improved, but switching response time is delayed
Solution Approach 1:
The patent implements dynamic dead time adjustment based on the operating state of the resonance circuit. The control device detects whether the resonance circuit is in capacitive or inductive load condition and dynamically adjusts the dead time period accordingly. This dynamic adaptation allows the system to maintain zero voltage switching in capacitive conditions while preventing hard switching, thereby resolving the contradiction between reducing conduction loss and ensuring switching element reliability.
Solution Approach 2:
The patent changes the dead time parameter based on the detected operating state. When capacitive load condition is detected, the dead time is adjusted to a first value optimized for preventing hard switching. When inductive load condition is detected, the dead time is adjusted to a second value optimized for different switching characteristics. This parameter adaptation resolves the contradiction by optimizing dead time for each specific operating condition.
Data Source
AI summary
The present invention relates to a switch driving circuit and a driving method thereof that are capable of preventing hard switching. The present invention includes: a dead time controller generating an high-side switching driver controlling signal and a low-side switching driver controlling signal controlling the switching operation of the high-side switch and the low-side switch according to a dead time controlling signal; and a phase detector detecting a phase of a resonance current flowing into the second power voltage terminal to generate a phase information signal, wherein one of the high-side switch driver controlling signal and a signal corresponding thereto, and the phase information signal are compared, and if the turn-on time of the high-side switch is later than the phase change of the resonance current, the dead time is controlled for the turn-on time of the high-side switch to advance the phase change of the resonance current.