Coupled-Inductor Resonant Converter for Soft Switching and Soft Start
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hard-switching power converters experience significant switching losses and electromagnetic interference (EMI) due to high slew rate currents and voltages, while resonant power converters face challenges in achieving efficient voltage conversion and soft starting without dedicated elements.
Innovation Solution
The development of new resonant power converters that incorporate coupled inductors for current multiplication, enabling zero voltage switching (ZVS) and zero current switching (ZCS), which minimize switching losses and EMI, and achieve higher efficiency with capacitive divider circuits and controllers that generate control signals for out-of-phase switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hard-switching power converters are used, then voltage conversion is achieved, but significant switching losses and electromagnetic interference occur
Solution Approach 1:
The patent applies resonant oscillation (analogous to mechanical vibration) by incorporating a resonant tank circuit with inductor and capacitor that oscillate at a specific resonant frequency. This resonance enables the switching devices to operate at zero voltage or zero current crossings, eliminating hard-switching losses and reducing electromagnetic interference while maintaining efficient voltage conversion.
2Loss of energy
If resonant power converters are used, then switching losses are minimized, but voltage conversion efficiency and soft starting capability are compromised
Solution Approach 1:
The patent makes the resonant tank circuit serve multiple functions: it enables soft switching to minimize losses, provides efficient voltage conversion through resonant oscillation, and facilitates soft starting by naturally limiting inrush current. The coupled inductor structure further enhances voltage conversion efficiency while maintaining the soft-switching benefits.
Solution Approach 2:
The patent utilizes changes in resonant frequency and impedance parameters of the tank circuit to achieve different operating modes. By adjusting the resonant frequency relative to the switching frequency and modifying the impedance characteristics, the circuit achieves both efficient voltage conversion and soft starting capability without sacrificing switching loss reduction.
3Stress or pressure
If resonant power converters are used, then switching stresses are reduced, but soft starting capability is lost without dedicated elements
Solution Approach 1:
The resonant tank circuit provides self-service for soft starting by naturally limiting inrush current through its resonant characteristics. When power is first applied, the circuit automatically oscillates at its resonant frequency, preventing sudden current surges and enabling gradual startup without requiring external soft-start components. This self-regulating behavior reduces switching stresses while providing inherent soft starting capability.
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
These resonant power converters reduce switching stresses and EMI, achieve higher efficiency, and enable soft starting without dedicated soft starting elements, while maintaining voltage regulation and efficient voltage conversion.
Implementation Method 1
a coupled inductor including N windings magnetically coupled by a magnetic core
Implementation Method 2
total leakage inductance of the coupled inductor and an equivalent capacitance of the capacitance divider circuit collectively form a resonant tank circuit
Data Source
AI summary
A resonant power converter includes a capacitive divider circuit, a coupled inductor, and N switching stages, where N is an integer greater than two. The coupled inductor includes N windings, and total leakage inductance of the coupled inductor and equivalent capacitance of the capacitive divider circuit collectively form a resonant tank circuit of the resonant power converter. Each switching stage is electrically coupled between a respective one of the N windings of the coupled inductor and the capacitive divider circuit. The capacitive divider circuit may include one or more resonant capacitors.