Current Sampling Circuit for LLC Winding Current Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of accurately tracking working current with a smaller time constant in two-stage voltage reduction circuits, particularly in LLC circuit topologies with reduced transformer winding turns, necessitates improved current sampling methods to ensure steady output and reduced power loss.
Innovation Solution
A sampling circuit with multiple winding groups and phase-offset voltage waveforms, combined with an amplification unit, to accurately sample and amplify the working current, compensating for parasitic resistance and temperature variations, and utilizing impedance-matching resistors and calibration units to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of low-voltage winding turns is reduced to one turn or 0.5 turn to achieve higher power density and switching frequency, then the power conversion efficiency and power density are improved, but the time constant for current tracking becomes smaller causing output instability
Solution Approach 1:
The patent segments the current measurement function by introducing separate sampling circuits for different winding groups. Each winding group has its own sampling circuit that measures current independently, then the results are combined. This segmentation allows accurate tracking of working current even with reduced winding turns, resolving the instability issue while maintaining high power density.
Solution Approach 2:
The patent introduces sampling circuits as intermediary components between the windings and the control system. These sampling circuits include sampling resistors and operational amplifiers that accurately measure the current through each winding group. This intermediary measurement system enables precise current tracking without requiring increased winding turns, thus maintaining both efficiency and stability.
2Power
If multiple winding groups are used to increase power handling capability, then the power conversion capacity is improved, but the complexity of current measurement and control increases
Solution Approach 1:
The patent merges the measurement signals from multiple winding groups through a unified control architecture. The sampling circuits for different winding groups are structured similarly, and their outputs are combined in a systematic way that leverages the phase-offset relationship between windings. This merging approach increases power capacity while keeping the measurement system manageable through modular design.
Solution Approach 2:
The patent utilizes the periodic nature of AC power conversion and the phase-offset relationships between winding groups. By sampling currents at appropriate phases and utilizing the predictable phase relationships, the system can accurately measure total working current through coordinated sampling of multiple windings, reducing the complexity of simultaneous multi-point measurement.
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
The solution provides precise current sampling and reduced power loss by minimizing parasitic resistance and conduction loss, ensuring stable operation and efficient power conversion in high-voltage systems.
Implementation Method 1
averaging by superposing the voltage waveforms to obtain a first output signal
Implementation Method 2
a voltage waveform is provided across each winding changing according to a working frequency in operation
Implementation Method 3
provides zero-voltage turn-on (i.e., zero-voltage switching, ZVS) or zero-current turn-on (i.e., zero-current switching, ZCS) of the switch connected with the transformer
Implementation Method 4
provides zero-voltage turn-on (i.e., zero-voltage switching, ZVS) or zero-current turn-on (i.e., zero-current switching, ZCS) of the switch connected with the transformer
Data Source
AI summary
A current sampling circuit is provided. The current sampling circuit includes a sampling unit provided with multiple sampling input terminals, a sampling reference terminal and at least one sampling output terminal. With a symmetric winding arrangement and a phase-offset configuration of control signals of the device, coupling voltage components sent to the current sampling circuit is self-counteracted. An amplification unit is further included in the current sampling circuit. Output signals of the current sampling circuit are calibrated by a calibration unit and compensated for temperature influences by a temperature compensation unit.