Interleaved Buck Converter ZVS Control
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Solution Overview
Problem
Conventional interleaved buck converters have low conversion efficiency when the duty cycle is small, as they do not achieve zero voltage switching (ZVS) for either switch when the duty cycle is less than 50%, leading to inefficient power conversion.
Innovation Solution
The interleaved buck converter design includes a controller that synchronizes the switching periods and ON time intervals of two switches, ensuring a time delay between their ON states, allowing for ZVS even at duty cycles less than 50% by adjusting the switching period and ON time interval, thereby maintaining high efficiency across varying duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the conventional interleaved buck converter uses equal time delay (half switching period) between switches, then the circuit structure is simple, but the conversion efficiency is low when duty cycle is less than 50%
Solution Approach 1:
The patent changes the time delay parameter from a fixed value (half switching period) to a variable value (less than half switching period). Specifically, when duty cycle is less than 50%, the time delay is set to be less than half the switching period, enabling ZVS for both switches. When duty cycle is greater than 50%, the time delay equals half the switching period, maintaining simple operation. This dynamic parameter adjustment resolves the contradiction between structural simplicity and conversion efficiency.
2Ease of operation
If the duty cycle is less than 50% in conventional interleaved buck converter, then the switching control is simple, but neither switch achieves zero voltage switching (ZVS)
Solution Approach 1:
The patent introduces dynamic adjustment of the time delay parameter based on the duty cycle. When duty cycle is less than 50%, the time delay is dynamically set to be less than half the switching period, which creates the conditions for ZVS. This dynamic control strategy maintains simple switching control while achieving reliable ZVS operation across different duty cycle ranges.
3Reliability
If the duty cycle is greater than 50% in conventional interleaved buck converter, then both switches achieve ZVS, but the conversion efficiency drops when duty cycle is reduced below 50%
Solution Approach 1:
The patent dynamically adjusts the time delay parameter based on duty cycle to maintain high conversion efficiency across all operating conditions. When duty cycle is reduced below 50%, the time delay is reduced accordingly to ensure both switches achieve ZVS. This parameter adaptation prevents the conversion efficiency drop that occurs in conventional designs when duty cycle is reduced.
Data Source
AI summary
An interleaved buck converter performs buck conversion by controlling operation of each of two switches thereof between an ON state and an OFF state. The switches have the same switching period and the same ON time interval, and a time delay from switching of one of the switches into the ON state to switching of the other one of the switches into the ON state equals the ON time interval of the switches minus a predetermined time interval.