Resonant Converter Frequency Tuning for Wide-Range Zero-Voltage Turn-On
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Solution Overview
Problem
Conventional dual-active-bridge (DAB) resonant converters struggle to achieve zero-voltage turn-on across a wide voltage operating range, leading to voltage drops or polarity reversals during switch turn-on, which reduces converter efficiency.
Innovation Solution
The proposed resonant converter and control method adjust the switching frequency to ensure that the output current matches a reference current, allowing all switches to achieve zero-voltage turn-on and preventing voltage drops or polarity reversals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dead time of bridge arm is adjusted to achieve zero-voltage turn-on, then the switch turn-on condition is improved, but the method fails to ensure zero-voltage turn-on under wide voltage operating range due to waveform mismatch between theoretical and actual resonant tank
Solution Approach 1:
The patent implements a feedback control mechanism where the actual resonant tank waveform is continuously monitored and compared with the theoretical waveform. The control system adjusts the switching frequency based on the detected waveform characteristics to maintain zero-voltage turn-on conditions across varying voltage operating ranges, resolving the mismatch between theoretical and actual waveforms.
Solution Approach 2:
The patent dynamically adjusts the switching frequency of the resonant converter based on real-time operating conditions and detected waveform characteristics. This dynamic adaptation allows the system to maintain optimal zero-voltage turn-on performance across a wide voltage operating range, rather than relying on fixed dead time adjustments.
2Device complexity
If zero-voltage turn-on is not achieved, then the switching operation is simplified, but voltage drop or voltage polarity reversal occurs while turning on the switch, resulting in reduced converter efficiency
Solution Approach 1:
The patent employs a self-service mechanism where the resonant tank circuit automatically generates the necessary voltage conditions for zero-voltage turn-on through its natural resonant oscillation. The control system detects these self-generated waveform characteristics and adjusts switching frequency accordingly, eliminating the need for complex external voltage management while maintaining high efficiency.
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
This approach enhances the efficiency of the resonant converter by ensuring zero-voltage turn-on for all switches, thereby minimizing voltage drops and polarity reversals across varying operating conditions.
Implementation Method 1
The resonant tank is electrically connected to the primary circuit and includes a resonant inductor and a resonant capacitor electrically connected in series
Data Source
AI summary
The present disclosure provides a control method applicable for a resonant converter. The control method includes steps of: (a) determining a voltage gain of the resonant converter according to the input voltage, a turn ratio of the transformer and the output voltage, and determining a resonant frequency according to an inductance of the resonant inductor and a capacitance of the resonant capacitor; (b) determining an output current of the resonant converter according to the switching frequency, the voltage gain and the resonant frequency; and (c) adjusting the switching frequency when the output current is not equal to a reference current, and performing the step (b) again.