Multi-level Buck Converter Voltage Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power converters face challenges with high voltage and high power applications, including component stress, difficulty in selecting switches, and circuit losses, particularly due to the limited switching frequencies of traditional power components like IGBTs and SCRs, and the increased cost of using MOSFETs or silicon carbide devices.
Innovation Solution
A multi-level buck converter design that includes an input capacitor, switches, a clamp capacitor, an output inductor, a clamp switch, a clamp diode, and control circuits to operate in a clamp switch triangular current mode, reducing component stress and circuit losses through a clamping triangle current control method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional power components (IGBTs or SCRs) are used for high voltage and high power applications, then voltage resistance and current resistance are improved, but switching frequency is limited causing large losses
Solution Approach 1:
The patent applies segmentation by dividing the single high-voltage switch into multiple lower-voltage switches arranged in series. Each switch experiences only a portion of the total voltage stress, enabling the use of MOSFETs with lower voltage ratings that can operate at higher switching frequencies, thereby reducing switching losses while maintaining high voltage capability.
2Loss of energy
If MOSFETs or silicon carbide devices are used to improve switching frequency, then switching losses are reduced, but component cost increases
Solution Approach 1:
The patent segments the voltage stress across multiple switches, allowing the use of cost-effective MOSFETs with lower voltage ratings rather than expensive high-voltage MOSFETs or silicon carbide devices. This approach achieves high switching frequency and low losses while using more economical standard-voltage components.
3Strength
If multi-level architecture is applied to reduce voltage stress, then component stress is reduced, but the number of components increases and control complexity increases
Solution Approach 1:
The patent implements a multi-level architecture that segments voltage stress across multiple switches and capacitors, creating distinct voltage levels. This segmentation reduces the voltage burden on each individual component, enabling the use of lower-voltage-rated switches and improving overall system reliability.
Solution Approach 2:
The patent employs periodic switching sequences that systematically transition through different switching states to maintain balanced voltage distribution across the multi-level structure. This periodic control pattern simplifies the management of complex multi-level operations by establishing predictable, repeating cycles.
Data Source
AI summary
A multi-level buck converter includes an input power source, an input capacitor, first to fourth switches, a clamp capacitor, an output inductor, a clamp switch, a clamp diode, an output capacitor, an output load, a current detection circuit, a voltage detection circuit and a control circuit. The current detection circuit detects whether an inductor current of the output inductor exceeds a predetermined current value, and if so, the output clamp signal controls the clamp switch to be turned on. The voltage detection circuit generates a duty cycle control signal according to an error between an output voltage and a target output voltage. The control circuit controls the first to the fourth switches to sequentially enter a first mode, a second mode, a third mode, and a fourth mode in a first part of a duty cycle.