Switching Loss Measurement via Current-Voltage Plotting
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Solution Overview
Problem
Current test tools are unable to measure specific switching losses during specific switching cycles of switching devices, limiting the understanding of power loss and efficiency in switching power supplies.
Innovation Solution
A method and test and measurement instrument that acquire switching voltage and current using probes, plot these on a current versus voltage graph, and calculate switching losses for each cycle, allowing for detailed analysis and graphical representation of ON and OFF switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only maximum, minimum and average statistics for all switching cycles are determined using current test tools, then the measurement process is simple and fast, but the measurement precision and detail of switching loss characterization is insufficient
Solution Approach 1:
The patent segments the switching cycle measurement into distinct phases (turn-on, turn-off, reverse recovery) and provides separate analysis for each phase. The current versus voltage plot is divided into multiple curves representing different switching cycles, allowing detailed examination of specific cycles rather than aggregated statistics only.
Solution Approach 2:
The patent introduces a new dimensional representation by plotting current versus voltage trajectories for each switching cycle. This transforms the measurement from scalar statistics (max, min, average) into two-dimensional trajectory analysis, enabling visualization of the complete switching process including transient behavior that cannot be captured by single-value statistics.
2Loss of information
If detailed measurement of specific switching loss during specific switching cycles is implemented, then the characterization detail is improved, but the ease of operation and measurement speed deteriorates
Solution Approach 1:
The patent performs preliminary acquisition of complete voltage and current waveforms for multiple switching cycles before analysis. The test tool captures full waveform data in advance, then allows selective analysis of specific cycles or phases without requiring re-measurement, thus reducing analysis time while maintaining measurement speed.
Solution Approach 2:
The patent creates graphical copies (current versus voltage curves) of each switching cycle's behavior. These curve representations serve as visual copies that can be analyzed without affecting the original measurement process, enabling detailed examination of specific cycles while the acquisition process remains efficient.
3Reliability
If current versus voltage plots with overlapping curves for multiple switching cycles are generated, then the switching loss characterization is improved, but the device complexity of the test instrument increases
Solution Approach 1:
The patent implements a universal analysis framework where the same test tool and measurement process can analyze different switching cycles, different device types, and different operating conditions using the same current versus voltage plotting methodology. The overlay feature works consistently across multiple cycles and device types, providing reliable comparative assessment without requiring specialized tools for each case.
Data Source
AI summary
The disclosed technology relates to a method and apparatus for graphically displaying a switching cycle of a switching device. A switching voltage and a switching current are acquired for a device under test via a voltage probe and a current probe, respectively, for a plurality of switching cycles of the device under test. The switching current versus the switching voltage is plotted on a current versus voltage plot as a curve for each of the switching cycles. Each of the curves on the current versus voltage plot overlap each other and are displayed to a user.