SMPS Signal Reconstruction for Voltage Spike Elimination
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Solution Overview
Problem
Switched mode power supplies experience signal disturbances due to parasitic coupling and voltage spikes, leading to incorrect current sensing and potential oscillations, especially in resonant power supplies with PFC stages and LLC converters.
Innovation Solution
A reconstruction apparatus within the current sense processor is employed to eliminate voltage spike disturbances by reconstructing the current sense signal, using primary and secondary stroke circuits and error signals to generate a Vreconstructed signal with a well-defined shape, free from spikes, while maintaining the original signal's amplitude and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional current sensing is used in SMPS with PFC stages and LLC converters, then the system can operate at high switching frequencies, but parasitic coupling and voltage spikes cause signal disturbances leading to incorrect current sensing and oscillations
Solution Approach 1:
The current sensing signal path is segmented into multiple stages: the original sensed signal is divided into a disturbance component and a valid current component. The reconstruction apparatus processes these segments separately, combining them to eliminate disturbances while preserving accurate current information, thereby maintaining reliability at high switching frequencies
Solution Approach 2:
A reconstruction apparatus is introduced as an intermediary between the disturbed current sense signal and the control circuitry. This intermediary processes the signal through primary and secondary stroke circuits, using error signals to reconstruct a clean version of the current signal that eliminates parasitic coupling effects while maintaining the original signal's essential characteristics
2Measurement precision
If signal reconstruction is implemented to eliminate voltage spikes, then current sensing accuracy is improved, but device complexity increases due to additional reconstruction apparatus
Solution Approach 1:
The reconstruction apparatus creates a copy of the original current sense signal through mathematical reconstruction rather than direct physical sensing. By generating a reconstructed signal that mirrors the essential characteristics of the original signal while eliminating disturbances, the system achieves improved measurement precision without requiring completely new sensing hardware
Solution Approach 2:
The reconstruction apparatus employs feedback mechanisms where error signals are generated by comparing the original sensed signal with the reconstructed signal. These error signals are fed back into the reconstruction process to continuously refine and correct the reconstructed current signal, ensuring high accuracy while using a structured approach that manages complexity
Data Source
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AI summary
A switched mode power supply including an alternating current power supply configured to output a voltage, a sense resistor configured to sense a voltage output from the power supply, a current sense processor configured to sense a current level through the sense resistor, sense disturbances in the sensed voltage, and reconstruct the sensed voltage to eliminate the disturbances.