DC-DC Converter Variable Frequency Control
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Solution Overview
Problem
Full bridge zero-voltage switch converters experience significant efficiency decreases under low-voltage outputs due to conduction losses, as the switch frequency remains constant, leading to greater losses and reduced power delivery.
Innovation Solution
A DC-DC converter design with a first and second bridge in parallel connection, where the bridges are operated in different modes based on detected efficiency parameters, adjusting the driving signals to avoid abrupt waveform changes and optimize efficiency across the full output voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the switch frequency remains constant under low-voltage output, then the switching control is simplified, but the conduction losses increase and efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the switch frequency variable rather than constant. The control module dynamically adjusts the switch frequency based on the output voltage level: using a first switch frequency for high-voltage output and a second switch frequency for low-voltage output. This dynamic frequency adjustment reduces conduction losses at low voltage while maintaining manageable switching control through automated detection and adjustment.
2Loss of energy
If the effective duty ratio is increased to achieve zero-voltage turn-on, then the converter efficiency improves, but the output voltage range is limited
Solution Approach 1:
The patent applies parameter changes by varying the switch frequency based on output voltage levels. The control module detects the output voltage and adjusts the switch frequency accordingly, enabling the converter to maintain high efficiency across a wide output voltage range. This parameter adjustment allows the converter to achieve zero-voltage turn-on at high voltage while extending adaptability to low-voltage outputs through frequency modulation.
3Duration of action of stationary object
If the loop-current is present for a long time due to resonant inductor, then the converter operates continuously, but the conduction losses increase under low-voltage output
Solution Approach 1:
The patent applies periodic action by implementing different switching frequencies for different operating conditions. The control module periodically adjusts the switch frequency based on detected output voltage levels, creating a rhythm of high-frequency switching for high-voltage output and low-frequency switching for low-voltage output. This periodic frequency adjustment reduces conduction losses during low-voltage operation while maintaining continuous converter operation.
Data Source
AI summary
Disclosed herein is a direct current to direct current (DC-DC) converter. The DC-DC converter includes a first bridge and a second bridge. The first bridge includes a first switch and a second switch, whereas the second bridge includes a third switch and a fourth switch. The second bridge is in parallel connection with the first bridge. The second switch is in series connection with the first switch, and the fourth switch is in series connection with the third switch. The DC-DC converter switches between a first mode and a second mode based on a detection signal. Further, a method for controlling the DC-DC converter is also disclosed herein.