Half-Bridge Power Supply Current Sensing Across Switching Modes
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Solution Overview
Problem
Existing switched mode electrical power supply devices face inaccuracies in load current measurements during different switching modes due to limited bandwidth of feedback loops, leading to instability and reduced accuracy, especially at higher frequencies.
Innovation Solution
The device incorporates a load current sensing mechanism with low-side and high-side sensing transistors and regulators, along with refining devices that add decaying current signals to feedback loops to enhance accuracy without altering loop stability, using operational transconductance amplifiers and digital-to-analog converters to adjust refining currents based on dynamic parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bandwidth of feedback loops is increased to improve measurement accuracy at higher frequencies, then measurement precision improves, but loop stability deteriorates
Solution Approach 1:
The feedback loop is segmented into two distinct loops: a high-side feedback loop for measuring load current during the first switching mode, and a low-side feedback loop for measuring load current during the second switching mode. Each loop operates independently with optimized bandwidth characteristics, allowing high measurement accuracy without compromising overall system stability.
Solution Approach 2:
The system dynamically switches between high-side and low-side feedback loops based on the switching mode. The gate driver circuit responds to switching signals to selectively activate the appropriate feedback loop, enabling adaptive measurement accuracy across different operating conditions while maintaining loop stability through controlled transitions.
2Productivity
If switching frequency is increased to improve productivity, then output per unit time increases, but measurement accuracy deteriorates due to limited feedback loop bandwidth
Solution Approach 1:
The system dynamically adapts its feedback mechanism to higher switching frequencies by utilizing the segmented high-side and low-side loops. Each loop is optimized to operate effectively within its specific switching phase, allowing the overall system to maintain measurement accuracy even as switching frequency increases to improve productivity.
3Device complexity
If a single feedback loop is used for both switching modes to simplify the device, then device complexity decreases, but measurement accuracy deteriorates due to bandwidth limitations in one or both modes
Solution Approach 1:
The feedback system is segmented into specialized high-side and low-side loops, each optimized for specific switching modes. This segmentation resolves the contradiction by providing mode-specific measurement optimization while maintaining manageable device complexity through systematic architecture.
Solution Approach 2:
Different feedback loops are assigned to different switching modes based on local requirements. The high-side loop handles the first switching mode while the low-side loop handles the second mode, allowing each loop to be optimized for its specific operational context and achieving high measurement accuracy without excessive complexity.
Data Source
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AI summary
An electrical power supply device configured for providing a load current, the electrical power supply device comprising: a half bridge circuit comprising a high-side power transistor and a low side power transistor; a gate driver circuit configured to drive the high-side power transistor and the low-side power transistor alternatively in a first switching mode; a load current sensing device, wherein the load current sensing device comprises for sensing a portion of the load current in the second switching mode a low-side sensing transistor and a low-side regulator; a load current sensing refining device, wherein the load current sensing refining device comprises a low-side current adding device configured for adding a low-side refining current to a low-side feedback loop during the second switching mode in order to refine a low-side sensing signal for the portion of the load current in the second switching mode at the output of the low-side regulator.