Soft-Start Conduction Assembly With Current-Based Switch Timing
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Solution Overview
Problem
Conventional soft start methods cause significant power loss and reduce the service life of components during the start-up process due to the gradual increase in conduction angle of conduction devices.
Innovation Solution
A conduction assembly with anti-series connected switch devices and body diodes, where the switch devices are partially ON during start-up, reducing power loss by minimizing conduction through body diodes, and utilizing current detection and zero-crossing turn-off to manage conduction angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conduction angle is gradually increased in multiple cycles during soft start, then the inductive load can be started up smoothly, but the body diode conducts for a longer duration causing large power loss and reduced component service life
Solution Approach 1:
The patent dynamically switches the conduction path from body diode to switch device based on real-time current detection. During the soft start process, when current exceeds a threshold, the control circuit activates the switch device to take over conduction from the body diode, thereby dynamically optimizing the conduction path to reduce power loss while maintaining reliable startup
Solution Approach 2:
The patent changes the conduction state parameter of the switch device from OFF to ON based on current magnitude detection. By monitoring the current flowing through the body diode and comparing it with a preset threshold, the system transitions the switch device to a conducting state when appropriate, thereby reducing the conduction time and power loss of the body diode
2Ease of operation
If the conduction angle is gradually increased in multiple cycles during soft start, then the inductive load can be started up smoothly, but the body diode conducts for a longer duration
Solution Approach 1:
The patent implements a feedback mechanism where the current flowing through the body diode is continuously detected and fed back to the control circuit. Based on this feedback, the control circuit determines when to activate the switch device, thereby optimizing the transition timing and reducing the conduction time of the body diode while maintaining smooth load startup
Solution Approach 2:
The patent prepares the switch device for preliminary activation by monitoring current conditions before the body diode completes its full conduction cycle. When the current exceeds the threshold, the switch device is activated in advance to take over conduction, thereby shortening the overall conduction time of the body diode while ensuring smooth startup
Data Source
AI summary
Embodiments of the present disclosure relate to a method, apparatus for operating a conduction assembly, a start device, and a computer-readable medium. The conduction assembly is coupled between an AC power supply and an inductive load, and comprises a first switch device and a second switch device which are in anti-series connection, the first switch device comprises a first body diode in anti-parallel connection with the first switch device, and the second switch device comprises a second body diode in anti-parallel connection with the second switch device. The method comprises: conducting the conduction assembly at a first conduction angle in a first cycle; conducting the conduction assembly in a second cycle at a second conduction angle that is greater than the first conduction angle, wherein in the first cycle and second cycle, a turn-off timing of the first switch device or the second switch device in anti-parallel connection with the first body diode or second body diode having a conduction direction the same as a current direction is determined based on the current flowing through the conduction assembly. The method proposed here may reduce the power loss of the soft start circuit.