Resonant Converter Soft Start for Seamless Voltage and Current Control
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Solution Overview
Problem
Existing power conversion devices face challenges in continuously and efficiently controlling voltage and current during the start-up of frequency-controlled resonant converters, leading to transient states and potential malfunctions due to voltage and current stresses.
Innovation Solution
A power conversion device and its operating method that include a soft start controller to determine and satisfy multiple soft start ending conditions, such as a duty ratio of 50% or more, output current matching command current, and output voltage matching command voltage, to ensure seamless transition and continuous control without transient states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frequency-controlled resonant converter performs soft start operation, then voltage and current stresses on power semiconductor devices and transformers are reduced, but the converter cannot continuously and efficiently control voltage and current during start-up, leading to transient states and potential malfunctions
Solution Approach 1:
The patent implements dynamic switching between two control modes: during soft start operation, frequency control is used to limit voltage and current stresses; once soft start conditions are met, the system dynamically transitions to duty ratio control for continuous and efficient voltage/current regulation. This dynamic mode switching resolves the contradiction by adapting the control strategy to the operational stage.
Solution Approach 2:
The patent changes the control parameter from frequency during soft start to duty ratio after soft start. The soft start controller monitors parameters such as output voltage, output current, and frequency, and when predetermined conditions are met (e.g., output voltage reaches a threshold), it switches to controlling the duty ratio of PWM signals. This parameter change enables continuous control without transient states while maintaining the protective benefits of soft start.
2Object-affected harmful factors
If soft start operation is performed with frequency control, then voltage and current stresses are reduced, but transient states occur and continuous control is lost
Solution Approach 1:
The patent performs preliminary soft start operation using frequency control to gradually build up voltage and current, preventing excessive stresses on power semiconductor devices and transformers. Once predetermined conditions are met (indicating the system has safely reached operational thresholds), the controller preliminarily establishes stable operating parameters before transitioning to duty ratio control, ensuring continuous and stable control without transient states.
Solution Approach 2:
The patent ensures continuity of useful action by seamlessly transitioning from soft start frequency control to post-soft start duty ratio control. The controller continuously monitors soft start conditions (output voltage, current, frequency) and maintains uninterrupted control throughout the transition, eliminating transient states and ensuring stable operation from start-up through full load.
3Ease of operation
If multiple soft start ending conditions are monitored, then seamless transition and continuous control are achieved, but device complexity increases
Solution Approach 1:
The patent implements a universal soft start controller that performs multiple functions: monitoring soft start conditions (output voltage, current, frequency), determining when soft start should end, and switching control modes. This multi-functional controller consolidates what could be separate complex components into a single integrated unit, achieving continuous control without proportionally increasing overall device complexity.
Solution Approach 2:
The patent uses feedback mechanisms where the soft start controller continuously monitors operational parameters (output voltage, current, frequency) and compares them against predetermined thresholds. When feedback indicates that soft start conditions are met, the controller automatically transitions to duty ratio control. This feedback-based automation reduces the need for complex manual control logic while ensuring seamless transition and continuous control.
Data Source
AI summary
A power conversion device is proposed. The device may include a receiver receiving a signal. The device may also include a soft start controller performing a soft start operation, determining two or more soft start ending conditions, and ending the soft start operation if the soft start ending conditions are all satisfied. The device may also include a signal controller controlling a signal after the soft start operation is ended, determining an ending condition of the power conversion device, and ending the power conversion device if the ending condition of the power conversion device is satisfied.