Trigger Circuit Zero Current Detection Eliminates High Voltage Components
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power factor correction converters using MOSFETs require external high breakdown voltage elements to detect zero inductor current, leading to increased costs due to the need for high breakdown voltage elements.
Innovation Solution
A trigger circuit that includes an off-time controller and a switching controller to control the turn-off time of a driving switch by sensing the driving current and comparing it to voltages symmetric to zero voltage, eliminating the need for external high breakdown voltage elements by using capacitors and buffer amplifiers to generate switching signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external high breakdown voltage elements are used to detect zero inductor current, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary voltage division network consisting of resistors R1 and R2 that transforms the high-voltage drain signal into a scaled-down version suitable for the comparator. This intermediary circuit enables precise zero-current detection without requiring high breakdown voltage elements directly in the detection path, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical/high-voltage-based detection method with an electronic voltage comparison approach using a comparator and voltage division network. Instead of relying on high breakdown voltage elements to detect current zero-crossing, the system uses electrical voltage comparison to achieve the same detection function with lower voltage requirements and reduced complexity.
2Measurement precision
If external high breakdown voltage elements are used to detect zero inductor current, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive high breakdown voltage elements with standard, low-cost resistors and comparators that are readily available and inexpensive to manufacture. The voltage division network using standard resistors and the comparator circuit achieve the same detection function at a fraction of the cost, significantly improving ease of manufacture while maintaining measurement precision.
Solution Approach 2:
The intermediary voltage division network acts as a cost-reducing mediator by transforming the high-voltage detection requirement into a low-voltage comparison problem. This allows the use of standard, inexpensive electronic components rather than specialized high breakdown voltage elements, thereby reducing manufacturing cost while preserving detection accuracy.
3Device complexity
If fixed frequency control is used, then device complexity is reduced, but adaptability to different operating conditions deteriorates
Solution Approach 1:
The patent implements dynamic frequency adjustment capability through the comparator-based detection system that automatically adapts to different operating conditions. The system can switch between continuous conduction mode and boundary conduction mode based on real-time voltage and current conditions, providing adaptability while maintaining relatively simple circuit architecture through the use of standard electronic components.
Data Source
AI summary
A trigger circuit includes an off-time controller configured to receive a sensing voltage by sensing a driving current and to compare the sensing voltage to first and second certain voltages that are close to a zero voltage value and symmetrical to the zero voltage value to control a turn-off time of a driving switch in order for the sensing voltage to correspond to the zero voltage value at the turn-on time point of the driving switch and a switching controller configured to provide a switching control signal for turning on the driving switch at the turn-on time point of the driving switch.