Multi-Level Step-Up Converter Soft Start Circuit
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Solution Overview
Problem
Existing multi-level step-up converters face challenges with large voltage step-up ratios, requiring specialized high-voltage transistor devices and large magnetic components, which increase volume, efficiency, and cost, and encounter issues during start-up and voltage transients, leading to voltage over-rating and impractical integration of inductors with MOS switch devices.
Innovation Solution
A multi-level step-up converter circuit with N transistor pairs and (N-1) capacitors, where the control module manages switching modes and capacitor charging to reduce voltage swing and inductor requirements, allowing for reduced switch voltage ratings and integration of components on a single substrate, thereby decreasing the inductor value and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large voltage step-up ratios are implemented using conventional step-up converters, then the required voltage conversion capability is achieved, but specialized high-voltage transistor devices and large magnetic components are required, increasing volume, cost, and complexity
Solution Approach 1:
The converter is divided into multiple stages with N transistor pairs and (N-1) capacitors, where each stage handles a portion of the voltage step-up. This segmentation allows the use of lower voltage-rated components in each stage while achieving the overall high voltage step-up ratio, reducing the inductor size by a factor of N^2 and eliminating the need for specialized high-voltage devices
Solution Approach 2:
The patent introduces a multi-level voltage structure by adding the dimension of multiple voltage levels through (N-1) capacitors connected between N transistor pairs. This transforms the conventional single-stage voltage step-up into a multi-level system where voltage is built up incrementally across multiple levels, reducing the voltage stress on individual components and allowing smaller inductors
2Power
If conventional step-up converters are used to achieve high voltage step-up ratios, then voltage conversion is possible, but large inductors are required that determine total volume, efficiency, and cost, making co-integration with MOS switch devices commercially impractical
Solution Approach 1:
By segmenting the voltage step-up function across N transistor pairs and (N-1) capacitors, each component operates at lower voltage stress, enabling standard MOS switch devices to be used instead of specialized high-voltage devices. This segmentation makes co-integration commercially practical as standard devices can be manufactured and integrated using conventional processes
Solution Approach 2:
The patent changes the operating parameters of the transistor devices by distributing the voltage stress across multiple devices in series. Each transistor pair handles only a portion of the total voltage, changing the voltage rating parameter from high-voltage (requiring specialized devices) to low-voltage (compatible with standard MOS devices), thereby enabling ease of manufacture and integration
3Power
If multi-level step-down converter topologies are used at lower voltages, then voltage conversion is achieved, but during start-up switches must withstand full input voltage due to uncharged capacitors, requiring voltage over-rating
Solution Approach 1:
The patent implements a soft-start mechanism that preliminarily charges the (N-1) capacitors before enabling full switching operation. During this preliminary phase, switches are gradually activated while capacitors are charged, ensuring that when normal operation begins, all capacitors are pre-charged and switches only need to withstand their rated voltage portions, not the full input voltage. This eliminates the need for voltage over-rating and improves reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the inductor value by a factor of N^2, decreases power loss, and enables smaller, more efficient converters with reduced switch voltage ratings, allowing for practical integration and improved performance in power conversion applications.
Implementation Method 1
an inductor L. First and second transistors QSR and QMS
Data Source
AI summary
A control circuit for a step-up converter includes a soft start module configured to control states of N transistor pairs of the step-up converter, where N is an integer greater than two. A driver module is in communication with the soft start module and configured to generate a first signal when N transistor pairs of the step-up converter are ready to switch. A first charging circuit is configured to charge (N-1) capacitors of the step-up converter to an input voltage of the step-up converter in response to the first signal and to generate a second signal when charging is complete. A second charging circuit is configured to sequentially charge the (N-1) capacitors of the step-up converter to (N-1) predetermined voltage values in response to the first signal and the second signal and before operation of the step-up converter begins.