Non-isolated DC-DC Converter with Cross-connected Capacitors for Bi-directional ZVS
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Solution Overview
Problem
Existing non-isolated DC-DC converters face challenges in efficiently performing bi-directional power transfer with zero voltage switching (ZVS) and zero current switching (ZCS) while maintaining soft-switching properties, and in detecting component failures within the power conversion circuitry.
Innovation Solution
The system employs a DC-DC power conversion circuit with a transformer connected via cross-connected capacitors and leakage inductors, where the control circuitry determines the direction and amount of power transfer by controlling the switching of switches on either side of the transformer, implementing ZVS and ZCS, and using sensor data to detect component failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bi-directional power transfer is implemented in non-isolated DC-DC converters, then power transfer flexibility is improved, but achieving zero voltage switching and zero current switching becomes more difficult
Solution Approach 1:
The converter dynamically switches between two operational modes (first mode for forward power transfer, second mode for reverse power transfer) based on the desired direction of power flow. Each mode is optimized with specific switching sequences and capacitor configurations to achieve ZVS/ZCS conditions, allowing the system to adapt its characteristics to maintain soft-switching performance in both directions
Solution Approach 2:
The invention changes the switching parameters and capacitor connection configurations depending on the power transfer direction. By adjusting the on-time of switches and reconfiguring capacitor connections between the two modes, the system optimizes the resonant conditions to achieve zero voltage switching and zero current switching in both forward and reverse power transfer directions
2Productivity
If cross-connected capacitors are used in DC-DC power conversion circuitry, then power transfer efficiency is improved, but component failure detection becomes more difficult
Solution Approach 1:
The control circuitry continuously monitors the operational status of the power conversion circuitry and provides feedback to detect component failures. By observing parameters such as switching characteristics, voltage levels, and current flow patterns during normal operation, the system can identify anomalies indicating capacitor or other component failures
Solution Approach 2:
The system uses its own operational parameters and existing sensing capabilities to detect component failures without requiring external diagnostic equipment. The control circuitry analyzes the behavior of the cross-connected capacitors and other components during power transfer operations to self-diagnose potential failures
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 enables efficient bi-directional power transfer with reduced switching losses and effective component failure detection, maintaining constant off-time for soft-switching and utilizing resonance periods for power recovery.
Implementation Method 1
a first switch and a second switch on either side of a transformer
Implementation Method 2
The off-time for the first switch or the second switch corresponds to one half of a resonance period
Implementation Method 3
a first capacitor and a second capacitor cross-connected across the transformer
Data Source
AI summary
A power transfer system includes DC-DC power conversion circuitry that has a first switch and a second switch on either side of a transformer connected via a common ground with a first capacitor and a second capacitor cross-connected across the transformer. A direction of power transfer is determined, and primary and secondary sides of the DC-DC power conversion circuitry are aligned based on the direction of power transfer. An amount of on-time for the first switch or the second switch is determined based on a quantity of power transfer through the DC-DC power conversion circuitry. The primary and secondary switches are controlled using switching.