Resonant DC-DC Converter Control Device for Light Load Efficiency
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Solution Overview
Problem
Conventional LLC half bridge resonant direct current/direct current converters experience reduced power conversion efficiency due to increased switching actions at lighter loads, as the frequency modulation controller increases switching frequency to maintain output voltage, leading to inefficiencies.
Innovation Solution
A control device with a frequency modulation controller and pulse selector generates synchronization signals and driving signals with adjustable duty cycles to reduce switching actions and maintain output voltage stability, even at lighter loads, by adjusting the frequency and duty cycle based on output information and a correcting threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the frequency modulation controller increases the switching frequency to maintain output voltage under lighter loads, then the output voltage stability is improved, but the number of switching actions increases and power conversion efficiency deteriorates
Solution Approach 1:
The patent applies periodic action by using pulse skipping control where the switch unit operates in periodic intervals rather than continuous switching. The controller selectively skips certain switching cycles based on output voltage feedback, allowing the system to maintain voltage stability while reducing the total number of switching actions. This is achieved by comparing output voltage with a reference voltage and disabling switching pulses when the output voltage exceeds the threshold, thereby creating a periodic on-off pattern that reduces switching losses.
2Power
If the switch unit operates at higher switching frequency to maintain output voltage under lighter loads, then the output voltage control is improved, but the switching losses increase and overall efficiency worsens
Solution Approach 1:
The patent implements dynamics by making the switching frequency adaptive rather than fixed. The controller dynamically adjusts the switching frequency based on real-time output voltage conditions and load requirements. Under lighter loads, the system automatically reduces switching frequency through pulse skipping, while maintaining higher frequency when needed for voltage regulation. This dynamic adaptation allows the system to optimize efficiency across varying operating conditions rather than being constrained by a fixed high switching frequency.
3Measurement precision
If the frequency modulation controller increases switching frequency to maintain output voltage, then the voltage regulation is improved, but the number of switching actions increases causing efficiency loss
Solution Approach 1:
The patent employs feedback control by continuously monitoring the output voltage and using this information to regulate the switching operation. The controller compares the actual output voltage with a reference voltage and adjusts the switching pulse generation accordingly. When output voltage reaches the desired level, the feedback signal triggers pulse skipping to prevent over-voltage while maintaining precise regulation. This closed-loop feedback mechanism ensures accurate voltage control without requiring continuous high-frequency switching, thereby reducing switching losses.
Data Source
AI summary
A control device for controlling a switch unit of a resonant direct current/direct current converter includes a frequency modulation controller and a pulse selector. The frequency modulation controller is adapted to be coupled electrically to the converter for receiving a correcting threshold value and output information of the converter, and for generating a synchronization signal according to the correcting threshold value and the output information received thereby. The pulse selector is adapted to be coupled electrically to the converter and the frequency modulation controller for receiving the correcting threshold value, the output information and the synchronization signal, and for generating a driving signal according to the correcting threshold value, the output information and the synchronization signal received thereby. The driving signal is adapted to drive the switch unit and has a working period. The driving signal switches between high and low signal levels at a frequency that is substantially equal to that of the synchronization signal during the working period.